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History log of /src/sys/miscfs/genfs
RevisionDateAuthorComments
 1.3 15-Sep-2001  chs a whole bunch of changes to improve performance and robustness under load:

- remove special treatment of pager_map mappings in pmaps. this is
required now, since I've removed the globals that expose the address range.
pager_map now uses pmap_kenter_pa() instead of pmap_enter(), so there's
no longer any need to special-case it.
- eliminate struct uvm_vnode by moving its fields into struct vnode.
- rewrite the pageout path. the pager is now responsible for handling the
high-level requests instead of only getting control after a bunch of work
has already been done on its behalf. this will allow us to UBCify LFS,
which needs tighter control over its pages than other filesystems do.
writing a page to disk no longer requires making it read-only, which
allows us to write wired pages without causing all kinds of havoc.
- use a new PG_PAGEOUT flag to indicate that a page should be freed
on behalf of the pagedaemon when it's unlocked. this flag is very similar
to PG_RELEASED, but unlike PG_RELEASED, PG_PAGEOUT can be cleared if the
pageout fails due to eg. an indirect-block buffer being locked.
this allows us to remove the "version" field from struct vm_page,
and together with shrinking "loan_count" from 32 bits to 16,
struct vm_page is now 4 bytes smaller.
- no longer use PG_RELEASED for swap-backed pages. if the page is busy
because it's being paged out, we can't release the swap slot to be
reallocated until that write is complete, but unlike with vnodes we
don't keep a count of in-progress writes so there's no good way to
know when the write is done. instead, when we need to free a busy
swap-backed page, just sleep until we can get it busy ourselves.
- implement a fast-path for extending writes which allows us to avoid
zeroing new pages. this substantially reduces cpu usage.
- encapsulate the data used by the genfs code in a struct genfs_node,
which must be the first element of the filesystem-specific vnode data
for filesystems which use genfs_{get,put}pages().
- eliminate many of the UVM pagerops, since they aren't needed anymore
now that the pager "put" operation is a higher-level operation.
- enhance the genfs code to allow NFS to use the genfs_{get,put}pages
instead of a modified copy.
- clean up struct vnode by removing all the fields that used to be used by
the vfs_cluster.c code (which we don't use anymore with UBC).
- remove kmem_object and mb_object since they were useless.
instead of allocating pages to these objects, we now just allocate
pages with no object. such pages are mapped in the kernel until they
are freed, so we can use the mapping to find the page to free it.
this allows us to remove splvm() protection in several places.

The sum of all these changes improves write throughput on my
decstation 5000/200 to within 1% of the rate of NetBSD 1.5
and reduces the elapsed time for "make release" of a NetBSD 1.5
source tree on my 128MB pc to 10% less than a 1.5 kernel took.
 1.2 08-Jul-1999  wrstuden branches: 1.2.14; 1.2.16; 1.2.18;
Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.1 12-Jun-1998  cgd branches: 1.1.10;
Rework the way kernel include files are installed. In the new method,
as with user-land programs, include files are installed by each directory
in the tree that has includes to install. (This allows more flexibility
as to what gets installed, makes 'partial installs' easier, and gives us
more options as to which machines' includes get installed at any given
time.) The old SYS_INCLUDES={symlinks,copies} behaviours are _both_
still supported, though at least one bug in the 'symlinks' case is
fixed by this change. Include files can't be build before installation,
so directories that have includes as targets (e.g. dev/pci) have to move
those targets into a different Makefile.
 1.1.10.1 02-Aug-1999  thorpej Update from trunk.
 1.2.18.1 01-Oct-2001  fvdl Catch up with -current.
 1.2.16.1 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.2.14.1 21-Sep-2001  nathanw Catch up to -current.
 1.39 27-Mar-2022  christos dedup the eofs link/symlink methods
 1.38 20-Oct-2021  thorpej Overhaul of the EVFILT_VNODE kevent(2) filter:

- Centralize vnode kevent handling in the VOP_*() wrappers, rather than
forcing each individual file system to deal with it (except VOP_RENAME(),
because VOP_RENAME() is a mess and we currently have 2 different ways
of handling it; at least it's reasonably well-centralized in the "new"
way).
- Add support for NOTE_OPEN, NOTE_CLOSE, NOTE_CLOSE_WRITE, and NOTE_READ,
compatible with the same events in FreeBSD.
- Track which kevent notifications clients are interested in receiving
to avoid doing work for events no one cares about (avoiding, e.g.
taking locks and traversing the klist to send a NOTE_WRITE when
someone is merely watching for a file to be deleted, for example).

In support of the above:

- Add support in vnode_if.sh for specifying PRE- and POST-op handlers,
to be invoked before and after vop_pre() and vop_post(), respectively.
Basic idea from FreeBSD, but implemented differently.
- Add support in vnode_if.sh for specifying CONTEXT fields in the
vop_*_args structures. These context fields are used to convey information
between the file system VOP function and the VOP wrapper, but do not
occupy an argument slot in the VOP_*() call itself. These context fields
are initialized and subsequently interpreted by PRE- and POST-op handlers.
- Version VOP_REMOVE(), uses the a context field for the file system to report
back the resulting link count of the target vnode. Return this in tmpfs,
udf, nfs, chfs, ext2fs, lfs, and ufs.

NetBSD 9.99.92.
 1.37 29-Jun-2021  dholland - Add a new vnode op: VOP_PARSEPATH.
- Move namei_getcomponent to genfs_vnops.c and call it genfs_parsepath.
- Add a parsepath entry to every vnode ops table.

VOP_PARSEPATH takes a directory vnode to be searched and a complete
following path and chooses how much of that path to consume. To begin
with, all parsepath calls are genfs_parsepath, which locates the first
'/' as always.

Note that the call doesn't take the whole struct componentname, only
the string. The other bits of struct componentname should not be
needed and there's no reason to cause potential complications by
exposing them.
 1.36 07-Aug-2020  christos branches: 1.36.6;
accmode should be accmode_t
 1.35 27-Jun-2020  christos Introduce genfs_pathconf() and use it for the default case in all filesystems.
 1.34 16-May-2020  christos Add ACL support for FFS. From FreeBSD.
 1.33 17-Feb-2017  hannken Add generic genfs_suspendctl() and use it for all file systems.
Layered file systems need work.
 1.32 27-Feb-2014  hannken branches: 1.32.6; 1.32.10; 1.32.14;
The current implementation of vn_lock() is racy. Modification of
the vnode operations vector for active vnodes is unsafe because it
is not known whether deadfs or the original file system will be
called.

- Pass down LK_RETRY to the lock operation (hint for deadfs only).

- Change deadfs lock operation to return ENOENT if LK_RETRY is unset.

- Change all other lock operations to check for dead vnode once
the vnode is locked and unlock and return ENOENT in this case.

With these changes in place vnode lock operations will never succeed
after vclean() has marked the vnode as VI_XLOCK and before vclean()
has changed the operations vector.

Adresses PR kern/37706 (Forced unmount of file systems is unsafe)

Discussed on tech-kern.

Welcome to 6.99.33
 1.31 02-May-2013  riastradh branches: 1.31.4;
Fix (harmless) typo in struct genfs_rename_ops::gro_lookup prototype.
 1.30 08-May-2012  riastradh branches: 1.30.2;
Implement a genfs_rename abstraction.

First major step in incrementally adapting all the file systems to a
saner rename VOP protocol.
 1.29 13-Mar-2012  elad Replace the remaining KAUTH_GENERIC_ISSUSER authorization calls with
something meaningful. All relevant documentation has been updated or
written.

Most of these changes were brought up in the following messages:

http://mail-index.netbsd.org/tech-kern/2012/01/18/msg012490.html
http://mail-index.netbsd.org/tech-kern/2012/01/19/msg012502.html
http://mail-index.netbsd.org/tech-kern/2012/02/17/msg012728.html

Thanks to christos, manu, njoly, and jmmv for input.

Huge thanks to pgoyette for spinning these changes through some build
cycles and ATF.
 1.28 30-Nov-2009  pooka branches: 1.28.12; 1.28.16; 1.28.18;
Introduce genfs_statvfs() as pretty much a no-info statvfs and
convert several pseudo file systems to use it.
 1.27 23-Jun-2009  elad Move the implementation of vaccess() to genfs_can_access(), in line with
the other routines of the same spirit.

Adjust file-system code to use it.

Keep vaccess() for KPI compatibility and to keep element of least
surprise. A "diagnostic" message warning that vaccess() is deprecated will
be printed when it's used (obviously, only in DIAGNOSTIC kernels).

No objections on tech-kern@:

http://mail-index.netbsd.org/tech-kern/2009/06/21/msg005310.html
 1.26 07-May-2009  elad Extract the open-coded authorization logic for chtimes() from various
file-systems and put it in a single function, genfs_can_chtimes().

This also makes UDF follow the same policy as all other file-systems.

Mailing list reference:

http://mail-index.netbsd.org/tech-kern/2009/04/27/msg004951.html
 1.25 25-Apr-2009  elad Add genfs_can_mount() and use it to prevent some more code duplication of
the security checks when mounting a device (VOP_ACCESS() + kauth(9) call)).

Proposed with no objections on tech-kern@:

http://mail-index.netbsd.org/tech-kern/2009/04/20/msg004859.html

The vnode is always expected to be locked, so no locking is done outside
the file-system code.
 1.24 22-Apr-2009  elad Per discussion on tech-kern@:

- Replace use of label/goto with returns

- Rename, change prototype of, and move functions from vfs_subr.c to
genfs_vnops.c
 1.23 28-Jan-2008  dholland branches: 1.23.10; 1.23.18; 1.23.24;
Fix some race conditions in rename.
Introduce a per-FS rename lock and new vfsops to manipulate it.
Get this lock while renaming. Also add another relookup() in do_sys_rename,
which is a hack to kludge around some of the worst deficiencies of
ufs_rename.
reviewed-by: pooka (and an earlier rev by ad)
posted on tech-kern with no objections.
 1.22 25-Jan-2008  ad Remove VOP_LEASE. Discussed on tech-kern.
 1.21 24-Apr-2007  perseant branches: 1.21.8; 1.21.14;
Split the VOP interface part of genfs_putpages() from the code. The new
function that does the work, genfs_do_putpages(), now takes as an argument
a pointer to the page that would be waited on, if PGO_BUSYWAIT were not set.
This allows a consumer, e.g. lfs_putpages(), to perform an action outside
the scope of UVM before sleeping on the page in question.
 1.20 11-Dec-2005  christos branches: 1.20.24; 1.20.26; 1.20.30; 1.20.32; 1.20.38;
merge ktrace-lwp.
 1.19 02-Nov-2005  yamt merge yamt-vop branch. remove following VOPs.

VOP_BLKATOFF
VOP_VALLOC
VOP_BALLOC
VOP_REALLOCBLKS
VOP_VFREE
VOP_TRUNCATE
VOP_UPDATE
 1.18 30-Aug-2005  xtraeme branches: 1.18.2;
Remove __P()
 1.17 10-Apr-2003  jdolecek branches: 1.17.2; 1.17.18;
use former genfs_eopnotsupp_rele() as genfs_eopnotsupp(), so that vnodes
are vput()/vrele()d as necessary - some filesystems did use the wrong
one for some ops, and it's just safer to not take the chance

based on suggestion by Bill Studenmund
 1.16 23-Oct-2002  jdolecek merge kqueue branch into -current

kqueue provides a stateful and efficient event notification framework
currently supported events include socket, file, directory, fifo,
pipe, tty and device changes, and monitoring of processes and signals

kqueue is supported by all writable filesystems in NetBSD tree
(with exception of Coda) and all device drivers supporting poll(2)

based on work done by Jonathan Lemon for FreeBSD
initial NetBSD port done by Luke Mewburn and Jason Thorpe
 1.15 18-Dec-2001  chs add some compatibility routines to allow mmap() to work non-UBCified
filesystems (in the same non-coherent fashion that they worked before).
 1.14 06-Dec-2001  chs add a VOP_PUTPAGES method for all the filesystems that don't have pages,
just unlock the interlock.
 1.13 15-Sep-2001  chs a whole bunch of changes to improve performance and robustness under load:

- remove special treatment of pager_map mappings in pmaps. this is
required now, since I've removed the globals that expose the address range.
pager_map now uses pmap_kenter_pa() instead of pmap_enter(), so there's
no longer any need to special-case it.
- eliminate struct uvm_vnode by moving its fields into struct vnode.
- rewrite the pageout path. the pager is now responsible for handling the
high-level requests instead of only getting control after a bunch of work
has already been done on its behalf. this will allow us to UBCify LFS,
which needs tighter control over its pages than other filesystems do.
writing a page to disk no longer requires making it read-only, which
allows us to write wired pages without causing all kinds of havoc.
- use a new PG_PAGEOUT flag to indicate that a page should be freed
on behalf of the pagedaemon when it's unlocked. this flag is very similar
to PG_RELEASED, but unlike PG_RELEASED, PG_PAGEOUT can be cleared if the
pageout fails due to eg. an indirect-block buffer being locked.
this allows us to remove the "version" field from struct vm_page,
and together with shrinking "loan_count" from 32 bits to 16,
struct vm_page is now 4 bytes smaller.
- no longer use PG_RELEASED for swap-backed pages. if the page is busy
because it's being paged out, we can't release the swap slot to be
reallocated until that write is complete, but unlike with vnodes we
don't keep a count of in-progress writes so there's no good way to
know when the write is done. instead, when we need to free a busy
swap-backed page, just sleep until we can get it busy ourselves.
- implement a fast-path for extending writes which allows us to avoid
zeroing new pages. this substantially reduces cpu usage.
- encapsulate the data used by the genfs code in a struct genfs_node,
which must be the first element of the filesystem-specific vnode data
for filesystems which use genfs_{get,put}pages().
- eliminate many of the UVM pagerops, since they aren't needed anymore
now that the pager "put" operation is a higher-level operation.
- enhance the genfs code to allow NFS to use the genfs_{get,put}pages
instead of a modified copy.
- clean up struct vnode by removing all the fields that used to be used by
the vfs_cluster.c code (which we don't use anymore with UBC).
- remove kmem_object and mb_object since they were useless.
instead of allocating pages to these objects, we now just allocate
pages with no object. such pages are mapped in the kernel until they
are freed, so we can use the mapping to find the page to free it.
this allows us to remove splvm() protection in several places.

The sum of all these changes improves write throughput on my
decstation 5000/200 to within 1% of the rate of NetBSD 1.5
and reduces the elapsed time for "make release" of a NetBSD 1.5
source tree on my 128MB pc to 10% less than a 1.5 kernel took.
 1.12 28-May-2001  chs branches: 1.12.2; 1.12.4;
add a genfs_mmap() and change all of the disk-based filesystems
to implement VOP_MMAP() with the genfs version, in preparation for
actually using this VOP.
 1.11 27-Nov-2000  chs branches: 1.11.2;
Initial integration of the Unified Buffer Cache project.
 1.10 03-Aug-1999  wrstuden branches: 1.10.2;
Add support for fcntl(2) to generate VOP_FCNTL calls. Any fcntl
call with F_FSCTL set and F_SETFL calls generate calls to a new
fileop fo_fcntl. Add genfs_fcntl() and soo_fcntl() which return 0
for F_SETFL and EOPNOTSUPP otherwise. Have all leaf filesystems
use genfs_fcntl().

Reviewed by: thorpej
Tested by: wrstuden
 1.9 08-Jul-1999  wrstuden Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.8 13-Aug-1998  kleink branches: 1.8.8;
Add genfs_einval(), which does the obvious thing.
 1.7 10-Aug-1998  matthias create miscfs/genfs/genfs_vnops.c:genfs_enoioctl and make all the other
filesystems use it instead of a private version.
 1.6 25-Jun-1998  thorpej - Rename nqnfs_vop_lease_check() to genfs_lease_check(). If NFSSERVER is
not in the kernel, genfs_lease_check() is simply a no-op. This allows
LKM'd file systems to be exported (previously did not work properly
due to a compile-time decision based on -DNFSSERVER).
- defopt NFSSERVER
 1.5 01-Mar-1998  fvdl Merge with Lite2 + local changes
 1.4 05-Jan-1998  perry RCSID Police.
 1.3 11-Apr-1997  kleink Implement a POSIX compliant genfs VOP_SEEK() and use it in the appropriate
places; by Chris G. Demetriou and myself.
 1.2 07-Sep-1996  mycroft Implement poll(2).
 1.1 01-Sep-1996  mycroft Add a set of generic file system operations that most file systems use.
Also, fix some time stamp bogosities.
 1.8.8.3 02-Aug-1999  thorpej Oops, some prototypes got nuked by mistake.
 1.8.8.2 02-Aug-1999  thorpej Update from trunk.
 1.8.8.1 04-Jul-1999  chs create genfs_getpages() and genfs_putpages().
these should be able to handle most of the local-disk filesystems.
 1.10.2.1 08-Dec-2000  bouyer Sync with HEAD.
 1.11.2.4 11-Nov-2002  nathanw Catch up to -current
 1.11.2.3 08-Jan-2002  nathanw Catch up to -current.
 1.11.2.2 21-Sep-2001  nathanw Catch up to -current.
 1.11.2.1 21-Jun-2001  nathanw Catch up to -current.
 1.12.4.1 01-Oct-2001  fvdl Catch up with -current.
 1.12.2.3 25-Sep-2002  jdolecek implement genfs_kqfilter() - this is based upon ufs_kqfilter(), but uses
vp->v_size for EVFILT_READ
 1.12.2.2 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.12.2.1 10-Jul-2001  lukem prototype genfs_kqfilter()
 1.17.18.3 04-Feb-2008  yamt sync with head.
 1.17.18.2 03-Sep-2007  yamt sync with head.
 1.17.18.1 21-Jun-2006  yamt sync with head.
 1.17.2.1 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.18.2.1 20-Oct-2005  yamt remove genfs_fsync.
 1.20.38.1 03-Sep-2007  wrstuden Sync w/ NetBSD-4-RC_1
 1.20.32.1 11-Jul-2007  mjf Sync with head.
 1.20.30.1 08-Jun-2007  ad Sync with head.
 1.20.26.1 07-May-2007  yamt sync with head.
 1.20.24.1 05-Jun-2007  bouyer Pull up following revision(s) (requested by perseant in ticket #703):
sys/miscfs/genfs/genfs.h 1.21
sys/miscfs/genfs/genfs_vnops.c 1.151
sys/ufs/lfs/lfs.h 1.119, 1.120
sys/ufs/lfs/lfs_bio.c 1.99-101
sys/ufs/lfs/lfs_extern.h 1.89
sys/ufs/lfs/lfs_inode.c 1.108, 1.109
sys/ufs/lfs/lfs_segment.c 1.197, 1.199, 1.200
sys/ufs/lfs/lfs_subr.c 1.69, 1.70
sys/ufs/lfs/lfs_syscalls.c 1.119
sys/ufs/lfs/lfs_vfsops.c 1.234, 1.235
sys/ufs/lfs/lfs_vnops.c 1.195, 1.196, 1.200, 1.202-206

Reduce busy waiting in lfs_putpages(), and other LFS improvements.
 1.21.14.1 18-Feb-2008  mjf Sync with HEAD.
 1.21.8.1 23-Mar-2008  matt sync with HEAD
 1.23.24.2 23-Jul-2009  jym Sync with HEAD.
 1.23.24.1 13-May-2009  jym Sync with HEAD.

Commit is split, to avoid a "too many arguments" protocol error.
 1.23.18.1 28-Apr-2009  skrll Sync with HEAD.
 1.23.10.4 11-Mar-2010  yamt sync with head
 1.23.10.3 18-Jul-2009  yamt sync with head.
 1.23.10.2 16-May-2009  yamt sync with head
 1.23.10.1 04-May-2009  yamt sync with head.
 1.28.18.2 27-Oct-2014  msaitoh Pull up following revision(s) (requested by riastradh in ticket #1135):
sys/miscfs/genfs/genfs.h: revision 1.31
Fix (harmless) typo in struct genfs_rename_ops::gro_lookup prototype.
 1.28.18.1 02-Jul-2012  jdc Pull up revisions:
src/sys/conf/files revision 1.1050
src/sys/miscfs/genfs/genfs.h revision 1.30 via patch
src/sys/miscfs/genfs/genfs_rename.c revision 1.1 via patch
src/sys/rump/librump/rumpvfs/Makefile.rumpvfs revision 1.33
(requested by riastradh in ticket #286).

Implement a genfs_rename abstraction.

First major step in incrementally adapting all the file systems to a
saner rename VOP protocol.
 1.28.16.2 02-Jun-2012  mrg sync to latest -current.
 1.28.16.1 05-Apr-2012  mrg sync to latest -current.
 1.28.12.3 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.28.12.2 23-May-2012  yamt sync with head.
 1.28.12.1 17-Apr-2012  yamt sync with head
 1.30.2.3 03-Dec-2017  jdolecek update from HEAD
 1.30.2.2 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.30.2.1 23-Jun-2013  tls resync from head
 1.31.4.1 18-May-2014  rmind sync with head
 1.32.14.1 21-Apr-2017  bouyer Sync with HEAD
 1.32.10.1 20-Mar-2017  pgoyette Sync with HEAD
 1.32.6.1 28-Aug-2017  skrll Sync with HEAD
 1.36.6.1 01-Aug-2021  thorpej Sync with HEAD.
 1.104 05-Apr-2024  riastradh uvm: Expand v_size <= v_writesize assertions to help diagnostics.

PR kern/58117
 1.103 09-Apr-2023  riastradh genfs: KASSERT(A && B) -> KASSERT(A); KASSERT(B)
 1.102 14-Jan-2022  riastradh genfs(9): Prune dead branch.
 1.101 19-Aug-2020  simonb Remove trailing \n from UVMHIST_LOG() format strings.
 1.100 14-Aug-2020  chs centralize calls from UVM to radixtree into a few functions.
in those functions, assert that the object lock is held in
the correct mode.
 1.99 10-Aug-2020  rin Output offsets in hex for UVMHIST.
 1.98 14-Jun-2020  ad genfs_putpages(): when building a cluster make use of pages in the in the
existing uvm_page_array.
 1.97 25-May-2020  ad - Alter the convention for uvm_page_array slightly, so the basic search
parameters can't change part way through a search: move the "uobj" and
"flags" arguments over to uvm_page_array_init() and store those with the
array.

- With that, detect when it's not possible to find any more pages in the
tree with the given search parameters, and avoid repeated tree lookups if
the caller loops over uvm_page_array_fill_and_peek().
 1.96 17-May-2020  ad Start trying to reduce cache misses on vm_page during fault processing.

- Make PGO_LOCKED getpages imply PGO_NOBUSY and remove the latter. Mark
pages busy only when there's actually I/O to do.

- When doing COW on a uvm_object, don't mess with neighbouring pages. In
all likelyhood they're already entered.

- Don't mess with neighbouring VAs that have existing mappings as replacing
those mappings with same can be quite costly.

- Don't enqueue pages for neighbour faults unless not enqueued already, and
don't activate centre pages unless uvmpdpol says its useful.

Also:

- Make PGO_LOCKED getpages on UAOs work more like vnodes: do gang lookup in
the radix tree, and don't allocate new pages.

- Fix many assertion failures around faults/loans with tmpfs.
 1.95 22-Mar-2020  ad Process concurrent page faults on individual uvm_objects / vm_amaps in
parallel, where the relevant pages are already in-core. Proposed on
tech-kern.

Temporarily disabled on MP architectures with __HAVE_UNLOCKED_PMAP until
adjustments are made to their pmaps.
 1.94 17-Mar-2020  ad Tweak the March 14th change to make page waits interlocked by pg->interlock.
Remove unneeded changes and only deal with the PQ_WANTED flag, to exclude
possible bugs.
 1.93 14-Mar-2020  ad Make uvm_pagemarkdirty() responsible for putting vnodes onto the syncer
work list. Proposed on tech-kern@.
 1.92 14-Mar-2020  ad Make page waits (WANTED vs BUSY) interlocked by pg->interlock. Gets RW
locks out of the equation for sleep/wakeup, and allows observing+waiting
for busy pages when holding only a read lock. Proposed on tech-kern.
 1.91 14-Mar-2020  ad Unused variable.
 1.90 14-Mar-2020  ad - Hide the details of SPCF_SHOULDYIELD and related behind a couple of small
functions: preempt_point() and preempt_needed().

- preempt(): if the LWP has exceeded its timeslice in kernel, strip it of
any priority boost gained earlier from blocking.
 1.89 14-Mar-2020  ad OR into bp->b_cflags; don't overwrite.
 1.88 27-Feb-2020  ad Tighten up the locking around vp->v_iflag a little more after the recent
split of vmobjlock & v_interlock.
 1.87 24-Feb-2020  ad v_interlock -> vmobjlock
 1.86 23-Feb-2020  ad UVM locking changes, proposed on tech-kern:

- Change the lock on uvm_object, vm_amap and vm_anon to be a RW lock.
- Break v_interlock and vmobjlock apart. v_interlock remains a mutex.
- Do partial PV list locking in the x86 pmap. Others to follow later.
 1.85 18-Feb-2020  chs remove the aiodoned thread. I originally added this to provide a thread context
for doing page cache iodone work, but since then biodone() has changed to
hand off all iodone work to a softint thread, so we no longer need the
special-purpose aiodoned thread.
 1.84 15-Jan-2020  ad Merge from yamt-pagecache (after much testing):

- Reduce unnecessary page scan in putpages esp. when an object has a ton of
pages cached but only a few of them are dirty.

- Reduce the number of pmap operations by tracking page dirtiness more
precisely in uvm layer.
 1.83 31-Dec-2019  ad branches: 1.83.2;
- Add and use wrapper functions that take and acquire page interlocks, and pairs
of page interlocks. Require that the page interlock be held over calls to
uvm_pageactivate(), uvm_pagewire() and similar.

- Solve the concurrency problem with page replacement state. Rather than
updating the global state synchronously, set an intended state on
individual pages (active, inactive, enqueued, dequeued) while holding the
page interlock. After the interlock is released put the pages on a 128
entry per-CPU queue for their state changes to be made real in batch.
This results in in a ~400 fold decrease in contention on my test system.
Proposed on tech-kern but modified to use the page interlock rather than
atomics to synchronise as it's much easier to maintain that way, and
cheaper.
 1.82 31-Dec-2019  ad Rename uvm_page_locked_p() -> uvm_page_owner_locked_p()
 1.81 16-Dec-2019  ad genfs_do_putpages(): add a missing call to uvm_page_array_advance().

Spotted by the automated test runs and:

Reported-by: syzbot+adc1f0ce21bcece5307d@syzkaller.appspotmail.com
 1.80 16-Dec-2019  ad Correction to previous for DEBUG case.
 1.79 15-Dec-2019  ad Fix DEBUG build.
 1.78 15-Dec-2019  ad Merge from yamt-pagecache:

- do gang lookup of pages using radixtree.
- remove now unused uvm_object::uo_memq and vm_page::listq.queue.
 1.77 13-Dec-2019  ad Break the global uvm_pageqlock into a per-page identity lock and a private
lock for use of the pagedaemon policy code. Discussed on tech-kern.

PR kern/54209: NetBSD 8 large memory performance extremely low
PR kern/54210: NetBSD-8 processes presumably not exiting
PR kern/54727: writing a large file causes unreasonable system behaviour
 1.76 06-Oct-2019  mlelstv Defer to synchronous I/O before the aiodone work queue exists.
 1.75 11-Jul-2019  maxv Fix (harmless) uninitialized variable: 'pg' could be 'endm', in which case
'pg->uobject' would not be initialized. Just invert the two last conditions
of the KASSERT.

ok hannken@
 1.74 10-Dec-2018  jdolecek assert that WAPBL journal write lock is actually held when called with
PGO_JOURNALLOCKED or IO_JOURNALLOCKED

suggested by mrg@, thanks
 1.73 09-Dec-2018  jdolecek support flag PGO_JOURNALLOCKED also for genfs_getpages()
 1.72 28-May-2018  chs branches: 1.72.2;
add a genfs method to allow a file system to limit the range of pages
that are given to a single GOP_WRITE() call. needed by ZFS.
 1.71 28-Oct-2017  pgoyette branches: 1.71.2;
Update the kernhist(9) kernel history code to address issues identified
in PR kern/52639, as well as some general cleaning-up...

(As proposed on tech-kern@ with additional changes and enhancements.)

Details of changes:

* All history arguments are now stored as uintmax_t values[1], both in
the kernel and in the structures used for exporting the history data
to userland via sysctl(9). This avoids problems on some architectures
where passing a 64-bit (or larger) value to printf(3) can cause it to
process the value as multiple arguments. (This can be particularly
problematic when printf()'s format string is not a literal, since in
that case the compiler cannot know how large each argument should be.)

* Update the data structures used for exporting kernel history data to
include a version number as well as the length of history arguments.

* All [2] existing users of kernhist(9) have had their format strings
updated. Each format specifier now includes an explicit length
modifier 'j' to refer to numeric values of the size of uintmax_t.

* All [2] existing users of kernhist(9) have had their format strings
updated to replace uses of "%p" with "%#jx", and the pointer
arguments are now cast to (uintptr_t) before being subsequently cast
to (uintmax_t). This is needed to avoid compiler warnings about
casting "pointer to integer of a different size."

* All [2] existing users of kernhist(9) have had instances of "%s" or
"%c" format strings replaced with numeric formats; several instances
of mis-match between format string and argument list have been fixed.

* vmstat(1) has been modified to handle the new size of arguments in the
history data as exported by sysctl(9).

* vmstat(1) now provides a warning message if the history requested with
the -u option does not exist (previously, this condition was silently
ignored, with only a single blank line being printed).

* vmstat(1) now checks the version and argument length included in the
data exported via sysctl(9) and exits if they do not match the values
with which vmstat was built.

* The kernhist(9) man-page has been updated to note the additional
requirements imposed on the format strings, along with several other
minor changes and enhancements.

[1] It would have been possible to use an explicit length (for example,
uint64_t) for the history arguments. But that would require another
"rototill" of all the users in the future when we add support for an
architecture that supports a larger size. Also, the printf(3) format
specifiers for explicitly-sized values, such as "%"PRIu64, are much
more verbose (and less aesthetically appealing, IMHO) than simply
using "%ju".

[2] I've tried very hard to find "all [the] existing users of kernhist(9)"
but it is possible that I've missed some of them. I would be glad to
update any stragglers that anyone identifies.
 1.70 27-Jun-2017  hannken Add missing check for dead or dying vnode to the entry of genfs_getpages().
 1.69 04-Jun-2017  hannken Operations fstrans_start() and fstrans_start_nowait() now always
use FSTRANS_SHARED as lock type so remove the lock type argument.

File system state FSTRANS_SUSPENDING is now unused so remove it.

Regen vnode_if files.

Ride 8.99.1 less than a hour ago.
 1.68 01-Apr-2017  dholland branches: 1.68.6;
Clarify meaning of "glocked" argument of genfs_putpages_read.
 1.67 01-Apr-2017  riastradh Simplify genfs_getpages_read async/unlock protocol.

Previously the caller unlocked for error or sync I/O, whereas
genfs_getpages_read unlocked on successful async.

Now caller unlocks in every case, and genfs_getpages_read doesn't
touch the lock.
 1.66 30-Mar-2017  hannken Change last users of FSTRANS_LAZY to FSTRANS_SHARED and change
genfs_suspendctl() to move from FSTRANS_NORMAL to FSTRANS_SUSPENDED
and vice versa.
 1.65 09-Mar-2017  hannken Protect genfs_do_putpages() against vnodes disappearing during
a forced mount update from read-write to read-only.
 1.64 01-Mar-2017  hannken Protect genfs_getpages() against vnodes disappearing during a
forced mount update from read-write to read-only.
 1.63 29-Sep-2016  christos branches: 1.63.2;
don't change the loop counts; noted by mrg@
 1.62 29-Sep-2016  christos Allow sparc kernels to build with SSP by using a constant PAGE_SIZE...
 1.61 06-May-2015  hannken branches: 1.61.2;
Remove miscfs/syncfs and

- move the syncer into kern/vfs_subr.c.

- change the syncer to process the mountlist and VFS_SYNC as appropriate.

- use an API for mount points similiar to the API for vnodes:
- vfs_syncer_add_to_worklist(struct mount *mp) to add
- vfs_syncer_remove_from_worklist(struct mount *mp) to remove a mount.

No objections on tech-kern@
 1.60 12-Apr-2015  skrll Fix UVMHIST build.
 1.59 10-Apr-2015  riastradh Pull VOP_BMAP/VOP_STRATEGY loop from getpages into its own function.

No functional change.

In preparation for a gop_read like the existing gop_write.
 1.58 25-Oct-2013  martin branches: 1.58.6;
Turn a few __unused into __diagused
 1.57 19-Oct-2013  martin Mark a potentially unused variable
 1.56 19-Oct-2013  martin Mark a potentially unused (if an arch implements pmap_update as empty
macro) variable accordingly.
 1.55 22-May-2012  yamt branches: 1.55.2; 1.55.4;
don't block on pager map for read-ahead.
reduce code duplication.
 1.54 29-Apr-2012  chs change vflushbuf() to take the full FSYNC_* flags.
translate FSYNC_LAZY into PGO_LAZY for VOP_PUTPAGES() so that
genfs_do_io() can set the appropriate io priority for the I/O.
this is the first part of addressing PR 46325.
 1.53 31-Oct-2011  yamt branches: 1.53.2; 1.53.6; 1.53.8;
typo in a comment
 1.52 09-Oct-2011  uebayasi Trim unused headers.
 1.51 01-Sep-2011  matt Use the new UVM_KMF_COLORMATCH flag to get a congruent mappings of the user
buffer so we can use unmanaged mappings (pmap_kenter_pa/pmap_kremove).
 1.50 31-Aug-2011  rmind genfs_do_directio: acquire the lock of page owner for now and fix PR/45177.
Will be revisited to avoid locking dance and be more efficient, e.g. we can
use unmanaged-mapping by allocating with colouring in mind.
 1.49 12-Jun-2011  rmind Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.
 1.48 21-Apr-2011  matt branches: 1.48.2;
Move some #ifdefs to prevent a code path change when DEBUG .vs. !DEBUG
Solves problem an assert firing when using NFS on MIPS.
 1.47 18-Apr-2011  rmind G/C unused speedup_syncer() mechanism and thus simplify some code.
Update some comments to reflect the reality. No actual changes to
the (used) syncer logic.

OK ad@
 1.46 06-Dec-2010  uebayasi branches: 1.46.2;
Correct an assertion; pointed out by mrg@ and pooka@, thanks.
 1.45 03-Dec-2010  hannken genfs_do_putpages(): When testing an uobject for dirty or modified
pages skip uninitialized (PG_FAKE) pages (DEBUG only).
 1.44 30-Nov-2010  hannken Always take the object lock before changing vmpage flags. Fixes a deadlock
where a thread is waiting on "genput" but the page in question is neither
BUSY nor WANTED.

No objections from tech-kern@.
 1.43 19-Nov-2010  uebayasi Whitespace.
 1.42 09-Nov-2010  hannken Genfs_getpages(): Break a deadlock where one thread runs VOP_GETPAGES(),
has busy pages and wants the wapbl lock as reader from wapbl_begin(),
another thread has the wapbl lock as reader and waits for a page from
the first thread. Now a third thread calls wapbl_flush() and wants the
wapbl lock as writer.

Move the wapbl_begin() up to a point where genfs_getpages() has no busy
pages yet.
 1.41 03-Nov-2010  uebayasi genfs_getpages: restore vm_page array correctly in PGO_LOCKED error
code path.
 1.40 01-Sep-2010  chs replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.39 19-Aug-2010  pooka print more info in the "past eof" panic
 1.38 08-Aug-2010  chs in genfs_getpages(), mark the vnode dirty (ie. add to syncer worklist
and set VI_WRMAPDIRTY) after we have busied the pages rather than
before. this prevents other threads calling genfs_do_putpages() from
marking the vnode clean again while we're in the process of creating
new writable mappings, since such threads will wait for the page(s) to
become unbusy before proceeding.
fixes the problem recently reported by hannken@ on tech-kern.
 1.37 29-Jul-2010  hannken Add vm page flag PG_MARKER and use it to tag dummy marker pages
in genfs_do_putpages() and uao_put().
Use 'v_uobj.uo_npages' to check for an empty memq.
Put some assertions where these marker pages may not appear.

Ok: YAMAMOTO Takashi <yamt@netbsd.org>
 1.36 30-Jan-2010  uebayasi branches: 1.36.2; 1.36.4;
Reduce the diff between genfs_getpages() and genfs_do_io(). These should be
merged eventually.
 1.35 30-Jan-2010  uebayasi Slightly more descriptive local variable names.
 1.34 29-Jan-2010  uebayasi genfs_getpages: Narrow & clarify the context where I/O happens & vmobjlock is dropped.
 1.33 29-Jan-2010  uebayasi genfs_getpages: Redo previous with a better goto label.
 1.32 28-Jan-2010  uebayasi Revert part which variable initializations within interleaved gotos.

again: if (...) goto err;
void *ptr = alloc();
if (...) goto again;
if (...) goto err1;
...
err1: if (ptr) free(ptr);
err:
return;

This leaks memory if exited with "goto again; -> goto err;".
 1.31 28-Jan-2010  uebayasi genfs_getpages: More constification & localization.
 1.30 28-Jan-2010  uebayasi genfs_getpages: Constify 2 variables, move one. No functional changes.
 1.29 28-Jan-2010  uebayasi genfs_getpages: Constify orignpages. Don't override its meaning by the value
re-calucated from GOP_SIZE(GOP_SIZE_MEM), but assign another variable
(orignmempages).
 1.28 28-Jan-2010  uebayasi Unbreak modules build.
 1.27 28-Jan-2010  uebayasi genfs_getpages: Constify & localize more variables.
 1.26 28-Jan-2010  uebayasi genfs_getpages: Move local variable declarations that are used only for I/O
to where they're used. This helps to track what's going in this lengthy
function.
 1.25 28-Jan-2010  uebayasi genfs_getpages: Localize a few more variables.
 1.24 28-Jan-2010  uebayasi genfs_putpages: Localize a few variables. No functional changes.
 1.23 27-Jan-2010  uebayasi Use genfs_node_*lock().
 1.22 27-Jan-2010  uebayasi Constify some pointers in genfs_getpages() and genfs_do_putpages().
 1.21 21-Oct-2009  rmind Remove uarea swap-out functionality:

- Addresses the issue described in PR/38828.
- Some simplification in threading and sleepq subsystems.
- Eliminates pmap_collect() and, as a side note, allows pmap optimisations.
- Eliminates XS_CTL_DATA_ONSTACK in scsipi code.
- Avoids few scans on LWP list and thus potentially long holds of proc_lock.
- Cuts ~1.5k lines of code. Reduces amd64 kernel size by ~4k.
- Removes __SWAP_BROKEN cases.

Tested on x86, mips, acorn32 (thanks <mpumford>) and partly tested on
acorn26 (thanks to <bjh21>).

Discussed on <tech-kern>, reviewed by <ad>.
 1.20 18-Apr-2009  pooka Move genfs_null_putpages() from genfs_io.c to genfs_vnops.c -- it does
not really do i/o.
 1.19 23-Feb-2009  rmind genfs_getpages: rework 1.18 revision - move uvm_pagermapout() back.
It is useful to make KVA available ASAP. Per discussion with <yamt>.
 1.18 04-Feb-2009  rmind branches: 1.18.2;
genfs_getpages: move putiobuf() and uvm_pagermapout() outside the glock.
OK by <ad>.
 1.17 16-Jan-2009  yamt - g/c stale function prototypes.
- rename UVM_PAGE_HASH_PENALTY to UVM_PAGE_TREE_PENALTY.
 1.16 01-Dec-2008  joerg Check that the filesystem acutally uses WAPBL before initiating a
transaction for the directio case. Fixes PR 39929 and similiar issues
seen with PostgreSQL.
 1.15 16-Nov-2008  pooka more <sys/buf.h> police
 1.14 31-Oct-2008  christos - allocate 8 pointers on the stack to avoid stack overflow in nfs.
- make that 8 a constant
- remove bogus panic
 1.13 19-Oct-2008  hannken branches: 1.13.2; 1.13.4;
Make genfs_directio() IO_JOURNALLOCKED aware. DirectIO no longer triggers
"locking against myself" panic in wapbl_begin().

Observed and tested by: Frank Kardel <kardel@netbsd.org>
 1.12 10-Oct-2008  hannken Break a deadlock where one thread has a wapbl transaction, calls VOP_GETPAGES
and wants to busy a page while another thread calls VOP_PUTPAGES on the same
vnode, takes pages busy and wants to start a wapbl transaction.

Reviewed by: Jason Thorpe <thorpej@netbsd.org>
 1.11 14-Aug-2008  yamt remove always-true conditionals.
 1.10 11-Aug-2008  yamt constify
 1.9 31-Jul-2008  simonb Merge the simonb-wapbl branch. From the original branch commit:

Add Wasabi System's WAPBL (Write Ahead Physical Block Logging)
journaling code. Originally written by Darrin B. Jewell while
at Wasabi and updated to -current by Antti Kantee, Andy Doran,
Greg Oster and Simon Burge.

OK'd by core@, releng@.
 1.8 04-Jun-2008  ad branches: 1.8.2; 1.8.4;
vm_page: put TAILQ_ENTRY into a union with LIST_ENTRY, so we can use both.
 1.7 14-May-2008  reinoud Import writing part of the UDF file system making optical media like CD's
and DVD's behave like floppy discs. Writing is supported upto and including
version 2.01; version 2.50 and 2.60 will follow.

Also extending the UDF implementation to support symbolic links and
hardlinks.

Added are the mmcformat(8) tool to format rewritable CD/DVD discs and
newfs_udf(8).

Limitations:
all operations can be performed on the file system though the
sheduling is currently optimised for archiving workloads.

mv(1)/rename(2) is currently only implemented for non-directories.
 1.6 19-Apr-2008  hannken branches: 1.6.2; 1.6.4;
Remove a race when pages are released while waiting for fstrans_start().

Fixes PR #38460
 1.5 18-Jan-2008  yamt branches: 1.5.6; 1.5.8;
genfs_do_putpages: DEBUG checks.
 1.4 18-Jan-2008  yamt genfs_do_putpages: ensure that we clean the vnode in the case of PGO_RECLAIM.
 1.3 18-Jan-2008  yamt push pmap_clear_reference calls into pdpolicy code, where reference bits
actually matter.
 1.2 02-Jan-2008  ad Merge vmlocking2 to head.
 1.1 17-Oct-2007  pooka branches: 1.1.4; 1.1.6; 1.1.8; 1.1.10; 1.1.12; 1.1.14; 1.1.16; 1.1.20;
Split I/O-related routines (getpages, putpages, etc.) which are heavily
tied to uvm out of genfs_vnops into genfs_io.c
 1.1.20.2 19-Jan-2008  bouyer Sync with HEAD
 1.1.20.1 02-Jan-2008  bouyer Sync with HEAD
 1.1.16.1 04-Dec-2007  ad Pull the vmlocking changes into a new branch.
 1.1.14.4 23-Mar-2008  matt sync with HEAD
 1.1.14.3 09-Jan-2008  matt sync with HEAD
 1.1.14.2 06-Nov-2007  matt sync with HEAD
 1.1.14.1 17-Oct-2007  matt file genfs_io.c was added on branch matt-armv6 on 2007-11-06 23:33:16 +0000
 1.1.12.1 18-Feb-2008  mjf Sync with HEAD.
 1.1.10.3 21-Jan-2008  yamt sync with head
 1.1.10.2 27-Oct-2007  yamt sync with head.
 1.1.10.1 17-Oct-2007  yamt file genfs_io.c was added on branch yamt-lazymbuf on 2007-10-27 11:35:52 +0000
 1.1.8.2 26-Oct-2007  joerg Sync with HEAD.

Follow the merge of pmap.c on i386 and amd64 and move
pmap_init_tmp_pgtbl into arch/x86/x86/pmap.c. Modify the ACPI wakeup
code to restore CR4 before jumping back into kernel space as the large
page option might cover that.
 1.1.8.1 17-Oct-2007  joerg file genfs_io.c was added on branch jmcneill-pm on 2007-10-26 15:48:52 +0000
 1.1.6.2 23-Oct-2007  ad Sync with head.
 1.1.6.1 17-Oct-2007  ad file genfs_io.c was added on branch vmlocking on 2007-10-23 20:36:43 +0000
 1.1.4.2 18-Oct-2007  yamt sync with head.
 1.1.4.1 17-Oct-2007  yamt file genfs_io.c was added on branch yamt-x86pmap on 2007-10-18 08:33:12 +0000
 1.5.8.2 17-Jun-2008  yamt sync with head.
 1.5.8.1 18-May-2008  yamt sync with head.
 1.5.6.4 17-Jan-2009  mjf Sync with HEAD.
 1.5.6.3 28-Sep-2008  mjf Sync with HEAD.
 1.5.6.2 05-Jun-2008  mjf Sync with HEAD.

Also fix build.
 1.5.6.1 02-Jun-2008  mjf Sync with HEAD.
 1.6.4.3 10-Oct-2008  skrll Sync with HEAD.
 1.6.4.2 18-Sep-2008  wrstuden Sync with wrstuden-revivesa-base-2.
 1.6.4.1 23-Jun-2008  wrstuden Sync w/ -current. 34 merge conflicts to follow.
 1.6.2.5 09-Oct-2010  yamt sync with head
 1.6.2.4 11-Aug-2010  yamt sync with head.
 1.6.2.3 11-Mar-2010  yamt sync with head
 1.6.2.2 04-May-2009  yamt sync with head.
 1.6.2.1 16-May-2008  yamt sync with head.
 1.8.4.2 13-Dec-2008  haad Update haad-dm branch to haad-dm-base2.
 1.8.4.1 19-Oct-2008  haad Sync with HEAD.
 1.8.2.1 10-Jun-2008  simonb Initial commit of Wasabi System's WAPBL (Write Ahead Physical Block
Logging) journaling code. Originally written by Darrin B. Jewell
while at Wasabi and updated to -current by Antti Kantee, Andy Doran,
Greg Oster and Simon Burge.

Still a number of issues - look in doc/BRANCHES for "simonb-wapbl"
for more info.
 1.13.4.5 21-Apr-2012  riz Back out a commit included in the ticket 1750 patch which obviously
doesn't belong there.
 1.13.4.4 21-Apr-2012  riz Pull up following revision(s) (requested by spz in ticket #1750):
crypto/dist/openssl/crypto/mem.c patch
crypto/dist/openssl/crypto/asn1/a_d2i_fp.c patch
crypto/dist/openssl/crypto/buffer/buffer.c patch
sys/miscfs/genfs/genfs_io.c patch

Address CVE-2012-2110.
[spz, ticket #1750]
 1.13.4.3 07-Sep-2010  bouyer branches: 1.13.4.3.2;
Pull up following revision(s) (requested by chs in ticket #1448):
sys/uvm/uvm_pager.h: revision 1.39 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.183 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.83 via patch
sys/miscfs/genfs/genfs_io.c: revision 1.40 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.20 via patch
replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.13.4.2 04-Apr-2009  snj branches: 1.13.4.2.2; 1.13.4.2.4;
Pull up following revision(s) (requested by joerg in ticket #664):
sys/miscfs/genfs/genfs_io.c: revision 1.16
Check that the filesystem acutally uses WAPBL before initiating a
transaction for the directio case. Fixes PR 39929 and similiar issues
seen with PostgreSQL.
 1.13.4.1 02-Nov-2008  snj Pull up following revision(s) (requested by tron in ticket #9):
sys/nfs/nfs_bio.c: revision 1.180
sys/miscfs/genfs/genfs_io.c: revision 1.14
sys/uvm/uvm_extern.h: revision 1.149
- allocate 8 pointers on the stack to avoid stack overflow in nfs.
- make that 8 a constant
- remove bogus panic
 1.13.4.3.2.2 21-Apr-2012  riz Back out a commit included in the ticket 1750 patch which obviously
doesn't belong there.
 1.13.4.3.2.1 21-Apr-2012  riz Pull up following revision(s) (requested by spz in ticket #1750):
crypto/dist/openssl/crypto/mem.c patch
crypto/dist/openssl/crypto/asn1/a_d2i_fp.c patch
crypto/dist/openssl/crypto/buffer/buffer.c patch
sys/miscfs/genfs/genfs_io.c patch

Address CVE-2012-2110.
[spz, ticket #1750]
 1.13.4.2.4.5 29-Feb-2012  matt Improve UVM_PAGE_TRKOWN.
Add more asserts to uvm_page.
 1.13.4.2.4.4 09-Feb-2012  matt Change to use the updated uvm_pageout_* signature.
 1.13.4.2.4.3 25-May-2011  matt Make uvm_map recognize UVM_FLAG_COLORMATCH which tells uvm_map that the
'align' argument specifies the starting color of the KVA range to be returned.

When calling uvm_km_alloc with UVM_KMF_VAONLY, also specify the starting
color of the kva range returned (UMV_KMF_COLORMATCH) and pass those to
uvm_map.

In uvm_pglistalloc, make sure the pages being returned have sequentially
advancing colors (so they can be mapped in a contiguous address range).
Add a few missing UVM_FLAG_COLORMATCH flags to uvm_pagealloc calls.

Make the socket and pipe loan color-safe.

Make the mips pmap enforce strict page color (color(VA) == color(PA)).
 1.13.4.2.4.2 20-May-2011  matt bring matt-nb5-mips64 up to date with netbsd-5-1-RELEASE (except compat).
 1.13.4.2.4.1 29-Apr-2011  matt Fix placement of #ifdef DEBUG / #endif
 1.13.4.2.2.3 21-Apr-2012  riz Back out a commit included in the ticket 1750 patch which obviously
doesn't belong there.
 1.13.4.2.2.2 21-Apr-2012  riz Pull up following revision(s) (requested by spz in ticket #1750):
crypto/dist/openssl/crypto/mem.c patch
crypto/dist/openssl/crypto/asn1/a_d2i_fp.c patch
crypto/dist/openssl/crypto/buffer/buffer.c patch
sys/miscfs/genfs/genfs_io.c patch

Address CVE-2012-2110.
[spz, ticket #1750]
 1.13.4.2.2.1 07-Sep-2010  bouyer Pull up following revision(s) (requested by chs in ticket #1448):
sys/uvm/uvm_pager.h: revision 1.39 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.183 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.83 via patch
sys/miscfs/genfs/genfs_io.c: revision 1.40 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.20 via patch
replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.13.2.3 28-Apr-2009  skrll Sync with HEAD.
 1.13.2.2 03-Mar-2009  skrll Sync with HEAD.
 1.13.2.1 19-Jan-2009  skrll Sync with HEAD.
 1.18.2.1 13-May-2009  jym Sync with HEAD.

Commit is split, to avoid a "too many arguments" protocol error.
 1.36.4.5 31-May-2011  rmind sync with head
 1.36.4.4 21-Apr-2011  rmind sync with head
 1.36.4.3 05-Mar-2011  rmind sync with head
 1.36.4.2 17-Mar-2010  rmind Reorganise UVM locking to protect P->V state and serialise pmap(9)
operations on the same page(s) by always locking their owner. Hence
lock order: "vmpage"-lock -> pmap-lock.

Patch, proposed on tech-kern@, from Andrew Doran.
 1.36.4.1 16-Mar-2010  rmind Change struct uvm_object::vmobjlock to be dynamically allocated with
mutex_obj_alloc(). It allows us to share the locks among UVM objects.
 1.36.2.65 11-Feb-2011  uebayasi Clean up debug code.
 1.36.2.64 21-Nov-2010  uebayasi Clarify things a bit in XIP putpages.
 1.36.2.63 21-Nov-2010  uebayasi Put back XIP putpages, but slightly modifed to be called from the
generic putpages, and to call pgo_get() than a specific function.
Without this, UVM went mad after unmount (vinval, etc.).
 1.36.2.62 21-Nov-2010  uebayasi Rename PGO_ZERO as PGO_HOLE, and s/uvm_page_zeropage/uvm_page_holepage/.
 1.36.2.61 21-Nov-2010  uebayasi Assert.
 1.36.2.60 21-Nov-2010  uebayasi Resurrect PGO_ZERO support.

When vnode pager encounters hole pages in XIP'ed vnodes, it fills
page slots with PGO_ZERO and returns them back to the caller (fault
handler). Fault handlers are responsible to check page slots and
redirect PGO_ZERO to the single "zero page" allocated by calling
uvm_page_zeropage_alloc(9).

The zero page is wired, read-only (PG_RDONLY) page. It's shared
by multiple vnodes, it has no single owner.

XIP'ed vnodes are supposed to be "stable" during I/O (unlocked).
Because XIP'ed mounts are always read-only. There's no chance to
change mappings of XIP'ed vnodes and their XIP'ed pages. Thus the
cached uobj is reused after pgo_get() for PGO_ZERO.

(Do we need a new concept of "read-only UVM object"?)
 1.36.2.59 21-Nov-2010  uebayasi Revert XIP putpages totally.

XIP'ed uobj owns no pages; uvm_object::uo_npages is always 0,
nothing happens.

Upper layer is responsible to unmap pmap-level mappings.
 1.36.2.58 21-Nov-2010  uebayasi Clean up, reduce diff from trunk.
 1.36.2.57 21-Nov-2010  uebayasi Merge getpages finalization code.

In XIP case, there's nothing to do because MMIO device pages are
"staleless", unlike page caches used as I/O buffers.
 1.36.2.56 21-Nov-2010  uebayasi Kill one more goto.
 1.36.2.55 21-Nov-2010  uebayasi Clean up gotos.
 1.36.2.54 21-Nov-2010  uebayasi Clean up ifdefs.
 1.36.2.53 21-Nov-2010  uebayasi Adjust merged XIP getpages page slot offset calculation again so
it really works. Sprinkle a few assertions and UVMHISTs.
 1.36.2.52 20-Nov-2010  uebayasi genfs_do_getpages_xip_io_done: Adjust page condition checks:
- Expect uvn_findpage_xip() returns busy pages.
- Device pages are always initialized (== !uninitialized == !fake).
 1.36.2.51 20-Nov-2010  uebayasi XIP has no "fake" (== unitinialized) pages, because pages are
already initialized when mounted. Adjust getpages loop again.
 1.36.2.50 20-Nov-2010  uebayasi Adjust again when heading page slots are skipped.
 1.36.2.49 20-Nov-2010  uebayasi Fix a bug (offset calculation) in the previous.
 1.36.2.48 20-Nov-2010  uebayasi Snapshot of getpages BMAP loop merge.
 1.36.2.47 19-Nov-2010  uebayasi genfs_*_xip_io: Adjust start offset.
 1.36.2.46 19-Nov-2010  uebayasi Comment.
 1.36.2.45 19-Nov-2010  uebayasi Remove unused code.
 1.36.2.44 19-Nov-2010  uebayasi More adjustment.

Reorder
genfs_node_unlock() -> putiobuf()
to
putiobuf() -> genfs_node_unlock()
but I don't think there's any constraint between these two.
 1.36.2.43 19-Nov-2010  uebayasi Share mode code. Care glock.
 1.36.2.42 19-Nov-2010  uebayasi Reduce code duplication.
 1.36.2.41 19-Nov-2010  uebayasi Reduce code.
 1.36.2.40 19-Nov-2010  uebayasi Reduce unnecessary code.
 1.36.2.39 19-Nov-2010  uebayasi Call XIP getpages() from within the generic one.
 1.36.2.38 19-Nov-2010  uebayasi Really remove XIP hole code.
 1.36.2.37 19-Nov-2010  uebayasi Comment out XIP hole page redirection code. Since makefs(8) doesn't
support hole, and these code paths can be never tested.

(The current XIP is read-only, so hole pages are pointless in
practice.)
 1.36.2.36 19-Nov-2010  uebayasi Adjust XIP putpages to I/O XIP getpages.
 1.36.2.35 19-Nov-2010  uebayasi Make XIP genfs_getpages_xip() return pages in I/O path, preparing
merge into the generic genfs_getpages().
 1.36.2.34 18-Nov-2010  uebayasi Make XIP pager use cdev_mmap() instead of struct vm_physseg.
 1.36.2.33 18-Nov-2010  uebayasi Style change.
 1.36.2.32 16-Nov-2010  uebayasi Factor out the part which lookups physical page "identity" from
UVM object, into sys/uvm/uvm_vnode.c:uvn_findpage_xip(). Eventually
this will become a call to cdev UVM object pager.
 1.36.2.31 15-Nov-2010  uebayasi Move zero-page into a common place, in the hope that it's shared
for other purposes.

According to Chuck Silvers, zero-page mappings don't need to be
explicitly unmapped in putpages(). Follow that advice.
 1.36.2.30 06-Nov-2010  uebayasi Sync with HEAD.
 1.36.2.29 04-Nov-2010  uebayasi Split physical device segment pages from "managed" to "managed
device". Cache that information as a flag PG_DEVICE so that callers
don't need to walk physsegs everytime.

Remove PQ_FIXED, which means that page daemon doesn't need to know
device segment pages at all. But still fault handlers need to know
them.

I think this is what I can do best now.
 1.36.2.28 04-Nov-2010  uebayasi Remove a XXX comment which is only confusing.
 1.36.2.27 22-Oct-2010  uebayasi Sync with HEAD (-D20101022).
 1.36.2.26 27-Sep-2010  uebayasi genfs_do_getpages_xip1: Adjust locking. Although XIP never does real I/O,
it's called without PGO_LOCKED in some cases. Leave vmobjlock unlocked in
that case.
 1.36.2.25 26-Sep-2010  uebayasi Minor fixes.
 1.36.2.24 26-Sep-2010  uebayasi Implement XIP "putpages". Invalidate MMU mappings of pages at the
request of PGO_FREE. PGO_DEACTIVATE and PGO_CLEANIT do nothing, because
XIP pages are neither queued nor writable.

Allocate read-only "zero" page per vnode. Put it at offset 0 of vnode's
uvm_object. This per-vnode "zero" page is mapped to all hole pages of
the vnode. If one of its mapped pages are forced to be PGO_FREE'ed,
all the mappings are invalidated.
 1.36.2.23 26-Sep-2010  uebayasi Wrap long lines.
 1.36.2.22 25-Aug-2010  uebayasi Fix UVMHIST build.

Remove a comment about xip getpages optimization; quick profiling showed
that this routine is not expensive. It'd be better to concentrate on
reducing TLB miss.
 1.36.2.21 17-Aug-2010  uebayasi Sync with HEAD.
 1.36.2.20 12-Aug-2010  uebayasi vm_physseg::start is PFN, not mdpgno, so don't decode it using
pmap_phys_address().
 1.36.2.19 11-Aug-2010  uebayasi In XIP vnode pager, assert that filesystem blocks and pages are aligned.
 1.36.2.18 22-Jul-2010  uebayasi s/PG_XIP/PQ_FIXED/, meaning that the fault handler sees XIP pages as
"fixed", and doesn't pass them to paging activity.

("XIP" is a vnode specific knowledge. It was wrong that the fault
handler had to know such a special thing.)
 1.36.2.17 20-Jul-2010  uebayasi genfs_do_getpages_xip: Simplify code.
 1.36.2.16 15-Jul-2010  uebayasi s/PG_DIRECT/PG_XIP/
 1.36.2.15 12-Jul-2010  uebayasi Reduce more diff by backing out XIP page specific code. Allow XIP pages
to be loaned.
 1.36.2.14 09-Jul-2010  uebayasi opt_direct_page.h is no more.
 1.36.2.13 09-Jul-2010  uebayasi Mark XIP pages as PG_CLEAN and/or PG_BUSY when appropriate. Protect
vnode lock when vm_page::flags is manipulated.
 1.36.2.12 07-Jul-2010  uebayasi To simplify things, revert global vm_page_md hash and allocate struct
vm_page [] for XIP physical segments.
 1.36.2.11 06-Jul-2010  uebayasi Directly allocate zero'ed vm_page for XIP unallocated blocks, instead
of abusing pool page. Move the code to XIP vnode pager in genfs_io.c.
 1.36.2.10 08-Jun-2010  uebayasi Comment.
 1.36.2.9 07-Jun-2010  uebayasi Comment.
 1.36.2.8 31-May-2010  uebayasi Re-define the definition of "device page"; device pages are pages of
device memory. Pages which don't have vm_page (== can't be used for
generic use), but whose PV are tracked, are called "direct pages" from
now.
 1.36.2.7 28-Apr-2010  uebayasi When mounting a block device as XIP, pass registered struct vm_physseg
* as a cookie from the block device to the caller (== mount code).
struct vm_physseg * will be passed to XIP vnode pager
(genfs_do_getpages_xip()), then converted back to paddr_t.

(My future plan is to pass struct vm_physseg * back to the fault handler,
and to pmap_enter() as is.)
 1.36.2.6 23-Mar-2010  uebayasi Put run-time XIP-specific per-mount data in struct specdev, not struct mount.
 1.36.2.5 17-Mar-2010  uebayasi Put comments to reflect my intent about genfs_do_getpages_xip method.
 1.36.2.4 28-Feb-2010  uebayasi Don't always enable XIP on this branch to prepare the merge. Fix build
without XIP in places.
 1.36.2.3 28-Feb-2010  uebayasi To mount block devices as XIP, pass physical address "cookie" used by
bus_space_mmap(9) / pmap_phys_addr(9) via struct mount.
 1.36.2.2 23-Feb-2010  uebayasi genfs_do_getpages_xip: Drop vmobjlock before calling VOP_BMAP, otherwise
deadlock. No idea how this worked for me before.

Directly call uvm_phys_to_vm_page_device() to make a device page cookie.
 1.36.2.1 11-Feb-2010  uebayasi genfs_getpages() for XIP.

Pages are directly mappable, and always there. What we need to do here is
to address filesystem blocks and tell those addresses back to the fault
handler by encoding the physical addresses in struct vm_page * pointers.

(I hate code duplication. What can I do?)
 1.46.2.1 06-Jun-2011  jruoho Sync with HEAD.
 1.48.2.1 23-Jun-2011  cherry Catchup with rmind-uvmplock merge.
 1.53.8.1 07-May-2012  riz Pull up following revision(s) (requested by chs in ticket #204):
sys/fs/sysvbfs/sysvbfs_vnops.c: revision 1.44
sys/ufs/ffs/ffs_vfsops.c: revision 1.277
sys/fs/v7fs/v7fs_vnops.c: revision 1.11
sys/ufs/chfs/chfs_vnops.c: revision 1.7
sys/ufs/ext2fs/ext2fs_readwrite.c: revision 1.61
sys/miscfs/genfs/genfs_io.c: revision 1.54
sys/kern/vfs_wapbl.c: revision 1.52
sys/uvm/uvm_pager.h: revision 1.43
sys/ufs/ffs/ffs_vnops.c: revision 1.121
sys/kern/vfs_subr.c: revision 1.434
sys/fs/msdosfs/msdosfs_vnops.c: revision 1.83
sys/fs/ntfs/ntfs_vnops.c: revision 1.51
sys/fs/udf/udf_subr.c: revision 1.119
sys/miscfs/specfs/spec_vnops.c: revision 1.135
sys/ufs/ext2fs/ext2fs_vnops.c: revision 1.103
sys/fs/udf/udf_vnops.c: revision 1.71
sys/ufs/ufs/ufs_readwrite.c: revision 1.104
change vflushbuf() to take the full FSYNC_* flags.
translate FSYNC_LAZY into PGO_LAZY for VOP_PUTPAGES() so that
genfs_do_io() can set the appropriate io priority for the I/O.
this is the first part of addressing PR 46325.
mark all wapbl I/O as BPRIO_TIMECRITICAL.
this is the second part of addressing PR 46325.
 1.53.6.1 02-Jun-2012  mrg sync to latest -current.
 1.53.2.19 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.53.2.18 22-Apr-2013  yamt revert unnecessary diff
 1.53.2.17 02-Nov-2012  yamt tweak integrity_sync cases
some comments
 1.53.2.16 01-Aug-2012  yamt - fix integrity sync.
putpages for integrity sync (fsync, msync with MS_SYNC, etc) should not
skip pages being written back by other threads.

- adapt to radix tree tag api changes.
 1.53.2.15 01-Aug-2012  yamt remove stale comments
 1.53.2.14 23-May-2012  yamt sync with head.
 1.53.2.13 17-Feb-2012  yamt byebye PG_HOLE as it turned out to be unnecessary.
 1.53.2.12 05-Feb-2012  yamt genfs_gop_write_rwmap: comment
 1.53.2.11 05-Feb-2012  yamt use unsigned
comments
assertions
 1.53.2.10 25-Jan-2012  yamt comment
 1.53.2.9 24-Jan-2012  yamt - g/c #if 0'ed code
- minor optimization
- comments
 1.53.2.8 18-Jan-2012  yamt - bug fixes
- minor optimizations
- assertions
- comments
 1.53.2.7 14-Jan-2012  yamt fix overwrite case
 1.53.2.6 20-Dec-2011  yamt don't inline uvn_findpages in genfs_io.
 1.53.2.5 30-Nov-2011  yamt g/c #if 1
comment
 1.53.2.4 26-Nov-2011  yamt - uvm_page_array_fill: add some more parameters
- uvn_findpages: use gang-lookup
- genfs_putpages: re-enable backward clustering
- mechanical changes after the recent radixtree.h api changes
 1.53.2.3 20-Nov-2011  yamt - simplify code
- comments
 1.53.2.2 10-Nov-2011  yamt - remove uobj->memq
- fix UVM_PAGE_TRKOWN
- comments
 1.53.2.1 02-Nov-2011  yamt page cache related changes

- maintain object pages in radix tree rather than rb tree.
- reduce unnecessary page scan in putpages. esp. when an object has a ton of
pages cached but only a few of them are dirty.
- reduce the number of pmap operations by tracking page dirtiness more
precisely in uvm layer.
- fix nfs commit range tracking.
- fix nfs write clustering. XXX hack
 1.55.4.1 18-May-2014  rmind sync with head
 1.55.2.4 03-Dec-2017  jdolecek update from HEAD
 1.55.2.3 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.55.2.2 10-Oct-2012  bouyer We know vp is not NULL, no need to check
 1.55.2.1 12-Sep-2012  tls Initial snapshot of work to eliminate 64K MAXPHYS. Basically works for
physio (I/O to raw devices); needs more doing to get it going with the
filesystems, but it shouldn't damage data.

All work's been done on amd64 so far. Not hard to add support to other
ports. If others want to pitch in, one very helpful thing would be to
sort out when and how IDE disks can do 128K or larger transfers, and
adjust the various PCI IDE (or at least ahcisata) drivers and wd.c
accordingly -- it would make testing much easier. Another very helpful
thing would be to implement a smart minphys() for RAIDframe along the
lines detailed in the MAXPHYS-NOTES file.
 1.58.6.3 28-Aug-2017  skrll Sync with HEAD
 1.58.6.2 05-Oct-2016  skrll Sync with HEAD
 1.58.6.1 06-Jun-2015  skrll Sync with HEAD
 1.61.2.3 26-Apr-2017  pgoyette Sync with HEAD
 1.61.2.2 20-Mar-2017  pgoyette Sync with HEAD
 1.61.2.1 04-Nov-2016  pgoyette Sync with HEAD
 1.63.2.1 21-Apr-2017  bouyer Sync with HEAD
 1.68.6.3 02-Nov-2017  snj Pull up following revision(s) (requested by pgoyette in ticket #335):
share/man/man9/kernhist.9: 1.5-1.8
sys/arch/acorn26/acorn26/pmap.c: 1.39
sys/arch/arm/arm32/fault.c: 1.105 via patch
sys/arch/arm/arm32/pmap.c: 1.350, 1.359
sys/arch/arm/broadcom/bcm2835_bsc.c: 1.7
sys/arch/arm/omap/if_cpsw.c: 1.20
sys/arch/arm/omap/tiotg.c: 1.7
sys/arch/evbarm/conf/RPI2_INSTALL: 1.3
sys/dev/ic/sl811hs.c: 1.98
sys/dev/usb/ehci.c: 1.256
sys/dev/usb/if_axe.c: 1.83
sys/dev/usb/motg.c: 1.18
sys/dev/usb/ohci.c: 1.274
sys/dev/usb/ucom.c: 1.119
sys/dev/usb/uhci.c: 1.277
sys/dev/usb/uhub.c: 1.137
sys/dev/usb/umass.c: 1.160-1.162
sys/dev/usb/umass_quirks.c: 1.100
sys/dev/usb/umass_scsipi.c: 1.55
sys/dev/usb/usb.c: 1.168
sys/dev/usb/usb_mem.c: 1.70
sys/dev/usb/usb_subr.c: 1.221
sys/dev/usb/usbdi.c: 1.175
sys/dev/usb/usbdi_util.c: 1.67-1.70
sys/dev/usb/usbroothub.c: 1.3
sys/dev/usb/xhci.c: 1.75
sys/external/bsd/drm2/dist/drm/i915/i915_gem.c: 1.34
sys/kern/kern_history.c: 1.15
sys/kern/kern_xxx.c: 1.74
sys/kern/vfs_bio.c: 1.275-1.276
sys/miscfs/genfs/genfs_io.c: 1.71
sys/sys/kernhist.h: 1.21
sys/ufs/ffs/ffs_balloc.c: 1.63
sys/ufs/lfs/lfs_vfsops.c: 1.361
sys/ufs/lfs/ulfs_inode.c: 1.21
sys/ufs/lfs/ulfs_vnops.c: 1.52
sys/ufs/ufs/ufs_inode.c: 1.102
sys/ufs/ufs/ufs_vnops.c: 1.239
sys/uvm/pmap/pmap.c: 1.37-1.39
sys/uvm/pmap/pmap_tlb.c: 1.22
sys/uvm/uvm_amap.c: 1.108
sys/uvm/uvm_anon.c: 1.64
sys/uvm/uvm_aobj.c: 1.126
sys/uvm/uvm_bio.c: 1.91
sys/uvm/uvm_device.c: 1.66
sys/uvm/uvm_fault.c: 1.201
sys/uvm/uvm_km.c: 1.144
sys/uvm/uvm_loan.c: 1.85
sys/uvm/uvm_map.c: 1.353
sys/uvm/uvm_page.c: 1.194
sys/uvm/uvm_pager.c: 1.111
sys/uvm/uvm_pdaemon.c: 1.109
sys/uvm/uvm_swap.c: 1.175
sys/uvm/uvm_vnode.c: 1.103
usr.bin/vmstat/vmstat.c: 1.219
Reorder to test for null before null deref in debug code
--
Reorder to test for null before null deref in debug code
--
KNF
--
No need for '\n' in UVMHIST_LOG
--
normalise a BIOHIST log message
--
Update the kernhist(9) kernel history code to address issues identified
in PR kern/52639, as well as some general cleaning-up...
(As proposed on tech-kern@ with additional changes and enhancements.)
Details of changes:
* All history arguments are now stored as uintmax_t values[1], both in
the kernel and in the structures used for exporting the history data
to userland via sysctl(9). This avoids problems on some architectures
where passing a 64-bit (or larger) value to printf(3) can cause it to
process the value as multiple arguments. (This can be particularly
problematic when printf()'s format string is not a literal, since in
that case the compiler cannot know how large each argument should be.)
* Update the data structures used for exporting kernel history data to
include a version number as well as the length of history arguments.
* All [2] existing users of kernhist(9) have had their format strings
updated. Each format specifier now includes an explicit length
modifier 'j' to refer to numeric values of the size of uintmax_t.
* All [2] existing users of kernhist(9) have had their format strings
updated to replace uses of "%p" with "%#jx", and the pointer
arguments are now cast to (uintptr_t) before being subsequently cast
to (uintmax_t). This is needed to avoid compiler warnings about
casting "pointer to integer of a different size."
* All [2] existing users of kernhist(9) have had instances of "%s" or
"%c" format strings replaced with numeric formats; several instances
of mis-match between format string and argument list have been fixed.
* vmstat(1) has been modified to handle the new size of arguments in the
history data as exported by sysctl(9).
* vmstat(1) now provides a warning message if the history requested with
the -u option does not exist (previously, this condition was silently
ignored, with only a single blank line being printed).
* vmstat(1) now checks the version and argument length included in the
data exported via sysctl(9) and exits if they do not match the values
with which vmstat was built.
* The kernhist(9) man-page has been updated to note the additional
requirements imposed on the format strings, along with several other
minor changes and enhancements.
[1] It would have been possible to use an explicit length (for example,
uint64_t) for the history arguments. But that would require another
"rototill" of all the users in the future when we add support for an
architecture that supports a larger size. Also, the printf(3)
format
specifiers for explicitly-sized values, such as "%"PRIu64, are much
more verbose (and less aesthetically appealing, IMHO) than simply
using "%ju".
[2] I've tried very hard to find "all [the] existing users of
kernhist(9)"
but it is possible that I've missed some of them. I would be glad
to
update any stragglers that anyone identifies.
--
For some reason this single kernel seems to have outgrown its declared
size as a result of the kernhist(9) changes. Bump the size.
XXX The amount of increase may be excessive - anyone with more detailed
XXX knowledge please feel free to further adjust the value
appropriately.
--
Misssed one cast of pointer --> uintptr_t in previous kernhist(9) commit
--
And yet another one. :(
--
Use correct mark-up for NetBSD version.
--
More improvements in grammar and readability.
--
Remove a stray '"' (obvious typo) and add a couple of casts that are
probably needed.
--
And replace an instance of "%p" conversion with "%#jx"
--
Whitespace fix. Give Bl tag table a width. Fix Xr.
 1.68.6.2 05-Jul-2017  martin Pull up following revision(s) (requested by hannken in ticket #84):
sys/miscfs/genfs/genfs_io.c: revision 1.70
Add missing check for dead or dying vnode to the entry of genfs_getpages().
 1.68.6.1 04-Jun-2017  bouyer pullup the following revisions, requested by hannken in ticket #2:
src/share/man/man9/fstrans.9 1.25
src/sys/kern/vfs_mount.c 1.66
src/sys/kern/vfs_subr.c 1.468
src/sys/kern/vfs_trans.c 1.46
src/sys/kern/vfs_vnode.c 1.94, 1.95, 1.96
src/sys/kern/vnode_if.c 1.105, 1.106
src/sys/kern/vnode_if.sh 1.65, 1.66
src/sys/kern/vnode_if.src 1.76
src/sys/miscfs/genfs/genfs_io.c 1.69
src/sys/miscfs/genfs/genfs_vnops.c 1.196, 1.197
src/sys/miscfs/genfs/layer_extern.h 1.40
src/sys/miscfs/genfs/layer_vfsops.c 1.51
src/sys/miscfs/genfs/layer_vnops.c 1.67
src/sys/miscfs/nullfs/null_vnops.c 1.42
src/sys/miscfs/overlay/overlay_vnops.c 1.24
src/sys/miscfs/umapfs/umap_vnops.c 1.60
src/sys/rump/include/rump/rumpvnode_if.h 1.29, 1.30
src/sys/rump/librump/rumpkern/emul.c 1.182
src/sys/rump/librump/rumpvfs/rumpvnode_if.c 1.29, 1.30
src/sys/sys/fstrans.h 1.11
src/sys/sys/vnode.h 1.278
src/sys/sys/vnode_if.h 1.100, 1.101
src/sys/sys/vnode_impl.h 1.14, 1.15
src/sys/ufs/lfs/lfs_pages.c 1.12

Vnode state, lock and fstrans cleanup:
- Rename vnode state "VS_ACTIVE" to "VS_LOADED" and add synthetic
state "VS_ACTIVE" to assert a loaded vnode with usecount > 0.

- Redo FSTRANS in vnode_if.c and use it for VOP_LOCK and VOP_UNLOCK.

- Cleanup the genfs lock operations.

- Make "struct vnode_impl" member "vi_lock" a krwlock_t again.

- Remove the lock type argument from fstrans_start and
fstrans_start_nowait,
remove now unused FSTRANS state "FSTRANS_SUSPENDING".
 1.71.2.2 26-Dec-2018  pgoyette Sync with HEAD, resolve a few conflicts
 1.71.2.1 25-Jun-2018  pgoyette Sync with HEAD
 1.72.2.2 13-Apr-2020  martin Mostly merge changes from HEAD upto 20200411
 1.72.2.1 10-Jun-2019  christos Sync with HEAD
 1.83.2.2 29-Feb-2020  ad Sync with head.
 1.83.2.1 17-Jan-2020  ad Sync with head.
 1.24 14-Mar-2020  ad Update a comment.
 1.23 15-Jan-2020  ad Merge from yamt-pagecache (after much testing):

- Reduce unnecessary page scan in putpages esp. when an object has a ton of
pages cached but only a few of them are dirty.

- Reduce the number of pmap operations by tracking page dirtiness more
precisely in uvm layer.
 1.22 28-May-2018  chs branches: 1.22.2; 1.22.8;
add a genfs method to allow a file system to limit the range of pages
that are given to a single GOP_WRITE() call. needed by ZFS.
 1.21 06-Jun-2013  dholland branches: 1.21.32;
Add missing declaration of struct vnode.
 1.20 01-Sep-2010  chs branches: 1.20.8; 1.20.18;
replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.19 27-Jan-2010  uebayasi branches: 1.19.2; 1.19.4;
Don't forget to tell the result of rw_tryenter().
 1.18 27-Jan-2010  uebayasi Add genfs_node_rdtrylock().
 1.17 14-May-2008  reinoud branches: 1.17.8; 1.17.14; 1.17.16;
Import writing part of the UDF file system making optical media like CD's
and DVD's behave like floppy discs. Writing is supported upto and including
version 2.01; version 2.50 and 2.60 will follow.

Also extending the UDF implementation to support symbolic links and
hardlinks.

Added are the mmcformat(8) tool to format rewritable CD/DVD discs and
newfs_udf(8).

Limitations:
all operations can be performed on the file system though the
sheduling is currently optimised for archiving workloads.

mv(1)/rename(2) is currently only implemented for non-directories.
 1.16 20-Feb-2007  ad branches: 1.16.38; 1.16.40; 1.16.42; 1.16.44;
Add genfs_node_destroy(). Fixes a lock "leak" seen when running LOCKDEBUG
kernels.
 1.15 15-Feb-2007  ad branches: 1.15.2;
Replace some uses of lockmgr() / simplelocks.
 1.14 14-Oct-2006  yamt add wrapper functions of lockmgr on g_glock.
 1.13 06-Oct-2006  dogcow fix build error in mount_sysvbfs.
 1.12 05-Oct-2006  chs add support for O_DIRECT (I/O directly to application memory,
bypassing any kernel caching for file data).
 1.11 14-May-2006  elad branches: 1.11.8; 1.11.10;
integrate kauth.
 1.10 30-Mar-2006  yamt some cleanups after the introduction of GOP_SIZE_MEM flag.
- remove GOP_SIZE_READ/GOP_SIZE_WRITE flags.
they have not been used since the change.
- ufs_balloc_range: remove code which has been no-op since the change.
thanks Konrad Schroder for explaining the original intention of the code.
- ffs_gop_size: don't extend past eof, in the case of GOP_SIZE_MEM.
otherwise genfs_getpages end up to allocate pages past eof unnecessarily.
 1.9 11-Dec-2005  christos branches: 1.9.4; 1.9.6; 1.9.8; 1.9.10; 1.9.12;
merge ktrace-lwp.
 1.8 23-Jul-2005  yamt update file timestamps for nfsd loaned-read and mmap.
PR/25279. discussed on tech-kern@.
 1.7 17-Jul-2005  yamt ensure that vnodes with dirty pages are always on syncer's queue.

- genfs_putpages: wait for i/o completion of PG_RELEASED/PG_PAGEOUT pages by
setting "wasclean" false when encountering them.
suggested by Stephan Uphoff in PR/24596 (1).

- genfs_putpages: write protect pages when cleaning out, if
we're going to take the vnode off the syncer's queue.
uvm_fault: don't write-map pages unless its vnode is already on
the syncer's queue.

fix PR/24596 (3) but in the different way from the suggested fix.
(to keep our current behaviour, ie. not to require explicit msync.
discussed on tech-kern@.)

- genfs_putpages: don't mistakenly take a vnode off the queue
by introducing a generation number in genfs_node.
genfs_getpages: increment the generation number.
suggested by Stephan Uphoff in PR/24596 (2).

- add some assertions.
 1.6 28-Jun-2005  yamt branches: 1.6.2;
- constify genfs_ops.
- use member designators.
 1.5 24-Sep-2003  yamt branches: 1.5.14;
fix a bug of lfs.

genfs_getpages() can read in more blocks than it should due to faked filesize
of lfs_gop_size(). it's a security problem and it makes gcc3 "internal error"

to fix this,
- in genfs_getpages(), always calculate diskeof and memeof separately
so that filesystems (in this case, lfs) can use different strategies
for them.
- introduce GOP_SIZE_MEM flag and use it to request in-core filesize.
(it was an intention of GOP_SIZE_READ,
but after the above change _READ is not a straightforward name)

after this, no one uses GOP_SIZE_{READ,WRITE} anymore but leave them for now.
 1.4 17-Feb-2003  perseant branches: 1.4.2;
Add code to UBCify LFS. This is still behind "#ifdef LFS_UBC" for now
(there are still some details to work out) but expect that to go
away soon. To support these basic changes (creation of lfs_putpages,
lfs_gop_write, mods to lfs_balloc) several other changes were made, to
wit:

* Create a writer daemon kernel thread whose purpose is to handle page
writes for the pagedaemon, but which also takes over some of the
functions of lfs_check(). This thread is started the first time an
LFS is mounted.

* Add a "flags" parameter to GOP_SIZE. Current values are
GOP_SIZE_READ, meaning that the call should return the size of the
in-core version of the file, and GOP_SIZE_WRITE, meaning that it
should return the on-disk size. One of GOP_SIZE_READ or
GOP_SIZE_WRITE must be specified.

* Instead of using malloc(...M_WAITOK) for everything, reserve enough
resources to get by and use malloc(...M_NOWAIT), using the reserves if
necessary. Use the pool subsystem for structures small enough that
this is feasible. This also obsoletes LFS_THROTTLE.

And a few that are not strictly necessary:

* Moves the LFS inode extensions off onto a separately allocated
structure; getting closer to LFS as an LKM. "Welcome to 1.6O."

* Unified GOP_ALLOC between FFS and LFS.

* Update LFS copyright headers to correct values.

* Actually cast to unsigned in lfs_shellsort, like the comment says.

* Keep track of which segments were empty before the previous
checkpoint; any segments that pass two checkpoints both dirty and
empty can be summarily cleaned. Do this. Right now lfs_segclean
still works, but this should be turned into an effectless
compatibility syscall.
 1.3 18-Dec-2001  chs branches: 1.3.2;
add some compatibility routines to allow mmap() to work non-UBCified
filesystems (in the same non-coherent fashion that they worked before).
 1.2 15-Sep-2001  chs branches: 1.2.2; 1.2.4;
add a forward decl for struct vm_page.
 1.1 15-Sep-2001  chs interfaces and structures used by new genfs_{get,put}pages().
 1.2.4.2 01-Oct-2001  fvdl Catch up with -current.
 1.2.4.1 15-Sep-2001  fvdl file genfs_node.h was added on branch thorpej-devvp on 2001-10-01 12:47:18 +0000
 1.2.2.3 08-Jan-2002  nathanw Catch up to -current.
 1.2.2.2 21-Sep-2001  nathanw Catch up to -current.
 1.2.2.1 15-Sep-2001  nathanw file genfs_node.h was added on branch nathanw_sa on 2001-09-21 22:36:37 +0000
 1.3.2.2 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.3.2.1 18-Dec-2001  thorpej file genfs_node.h was added on branch kqueue on 2002-01-10 20:01:34 +0000
 1.4.2.4 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.4.2.3 21-Sep-2004  skrll Fix the sync with head I botched.
 1.4.2.2 18-Sep-2004  skrll Sync with HEAD.
 1.4.2.1 03-Aug-2004  skrll Sync with HEAD
 1.5.14.1 24-Aug-2005  riz Pull up following revision(s) (requested by yamt in ticket #688):
sys/miscfs/genfs/genfs_vnops.c: revision 1.98 via patch
sys/ufs/ffs/ffs_vfsops.c: revision 1.165
sys/ufs/lfs/lfs_extern.h: revision 1.69
sys/fs/filecorefs/filecore_vfsops.c: revision 1.20
sys/nfs/nfs_node.c: revision 1.80
sys/fs/smbfs/smbfs_node.c: revision 1.24
sys/fs/cd9660/cd9660_vfsops.c: revision 1.24
sys/fs/msdosfs/msdosfs_denode.c: revision 1.8
sys/miscfs/genfs/genfs_node.h: revision 1.6
sys/ufs/lfs/lfs_vfsops.c: revision 1.183
sys/ufs/ext2fs/ext2fs_vfsops.c: revision 1.86
sys/fs/adosfs/advfsops.c: revision 1.23
sys/fs/ntfs/ntfs_vfsops.c: revision 1.31
- constify genfs_ops.
- use member designators.

sys/miscfs/genfs/genfs_vnops.c: revision 1.99 via patch
genfs_getpages: don't forget to put the vnode onto the syncer's work que
ue
even in the case of PGO_LOCKED.

sys/uvm/uvm_bio.c: revision 1.40
sys/uvm/uvm_pager.h: revision 1.29
sys/miscfs/genfs/genfs_vnops.c: revision 1.100 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.50
- introduce PGO_NOBLOCKALLOC and use it for ubc mapping
to prevent unnecessary block allocations in the case that
page size > block size.
- ufs_balloc_range: use VM_PROT_WRITE+PGO_NOBLOCKALLOC rather than
VM_PROT_READ.

sys/uvm/uvm_fault.c: revision 1.96
sys/miscfs/genfs/genfs_vnops.c: revision 1.101 via patch
sys/uvm/uvm_object.h: revision 1.19
sys/miscfs/genfs/genfs_node.h: revision 1.7
ensure that vnodes with dirty pages are always on syncer's queue.
- genfs_putpages: wait for i/o completion of PG_RELEASED/PG_PAGEOUT pages by
setting "wasclean" false when encountering them.
suggested by Stephan Uphoff in PR/24596 (1).
- genfs_putpages: write protect pages when cleaning out, if
we're going to take the vnode off the syncer's queue.
uvm_fault: don't write-map pages unless its vnode is already on
the syncer's queue.
fix PR/24596 (3) but in the different way from the suggested fix.
(to keep our current behaviour, ie. not to require explicit msync.
discussed on tech-kern@.)
- genfs_putpages: don't mistakenly take a vnode off the queue
by introducing a generation number in genfs_node.
genfs_getpages: increment the generation number.
suggested by Stephan Uphoff in PR/24596 (2).
- add some assertions.

sys/miscfs/genfs/genfs_vnops.c: revision 1.102 via patch
genfs_putpages: don't bother to clean the vnode unless VONWORKLST.

sys/ufs/ffs/ffs_vnops.c: revision 1.71
ffs_full_fsync: because VBLK/VCHR can be mmap'ed,
do VOP_PUTPAGES for them as well.

sys/uvm/uvm_fault.c: revision 1.97
uvm_fault: check a correct object in the case of layered filesystems.
fix PR/30811 from Jukka Salmi.

sys/uvm/uvm_object.h: revision 1.20
sys/ufs/ffs/ffs_vfsops.c: revision 1.167
sys/uvm/uvm_bio.c: revision 1.41
sys/ufs/ufs/ufs_vnops.c: revision 1.129
sys/uvm/uvm_mmap.c: revision 1.92
sys/uvm/uvm_fault.c: revision 1.98
sys/kern/vfs_subr.c: revision 1.252
sys/fs/msdosfs/denode.h: revision 1.5
sys/miscfs/genfs/genfs_vnops.c: revision 1.103 via patch
sys/fs/msdosfs/msdosfs_denode.c: revision 1.9
sys/sys/vnode.h: revision 1.141
sys/ufs/ufs/ufs_inode.c: revision 1.51
sys/ufs/ufs/ufs_extern.h: revision 1.45 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.8
sys/ufs/lfs/lfs_vfsops.c: revision 1.184
sys/uvm/uvm_pager.h: revision 1.30
sys/ufs/ext2fs/ext2fs_vfsops.c: revision 1.87
update file timestamps for nfsd loaned-read and mmap.
PR/25279. discussed on tech-kern@.

sys/miscfs/genfs/genfs_vnops.c: revision 1.104 via patch
don't write-protect wired pages. pointed by Chuck Silvers.
for now, leave a vnode on the syncer's queue, as suggested by him.

sys/ufs/ffs/ffs_vnops.c: revision 1.72
revert VCHR part of ffs_vnops.c 1.71.
as VCHR uses the device pager, no point to call VOP_PUTPAGES here.
pointed by Chuck Silvers.
 1.6.2.3 26-Feb-2007  yamt sync with head.
 1.6.2.2 30-Dec-2006  yamt sync with head.
 1.6.2.1 21-Jun-2006  yamt sync with head.
 1.9.12.2 24-May-2006  tron Merge 2006-05-24 NetBSD-current into the "peter-altq" branch.
 1.9.12.1 31-Mar-2006  tron Merge 2006-03-31 NetBSD-current into the "peter-altq" branch.
 1.9.10.3 20-Apr-2006  christos kauth_cred_t -> struct kauth_cred;
 1.9.10.2 19-Apr-2006  elad sync with head.
 1.9.10.1 08-Mar-2006  elad Adapt to kernel authorization KPI.
 1.9.8.2 24-May-2006  yamt sync with head.
 1.9.8.1 01-Apr-2006  yamt sync with head.
 1.9.6.2 01-Jun-2006  kardel Sync with head.
 1.9.6.1 22-Apr-2006  simonb Sync with head.
 1.9.4.1 09-Sep-2006  rpaulo sync with head
 1.11.10.1 22-Oct-2006  yamt sync with head
 1.11.8.1 18-Nov-2006  ad Sync with head.
 1.15.2.1 27-Feb-2007  yamt - sync with head.
- move sched_changepri back to kern_synch.c as it doesn't know PPQ anymore.
 1.16.44.1 23-Jun-2008  wrstuden Sync w/ -current. 34 merge conflicts to follow.
 1.16.42.3 09-Oct-2010  yamt sync with head
 1.16.42.2 11-Mar-2010  yamt sync with head
 1.16.42.1 16-May-2008  yamt sync with head.
 1.16.40.1 18-May-2008  yamt sync with head.
 1.16.38.1 02-Jun-2008  mjf Sync with HEAD.
 1.17.16.1 20-May-2011  matt bring matt-nb5-mips64 up to date with netbsd-5-1-RELEASE (except compat).
 1.17.14.1 07-Sep-2010  bouyer Pull up following revision(s) (requested by chs in ticket #1448):
sys/uvm/uvm_pager.h: revision 1.39 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.183 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.83 via patch
sys/miscfs/genfs/genfs_io.c: revision 1.40 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.20 via patch
replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.17.8.1 07-Sep-2010  bouyer Pull up following revision(s) (requested by chs in ticket #1448):
sys/uvm/uvm_pager.h: revision 1.39 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.183 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.83 via patch
sys/miscfs/genfs/genfs_io.c: revision 1.40 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.20 via patch
replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.19.4.1 05-Mar-2011  rmind sync with head
 1.19.2.1 22-Oct-2010  uebayasi Sync with HEAD (-D20101022).
 1.20.18.1 23-Jun-2013  tls resync from head
 1.20.8.2 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.20.8.1 20-Nov-2011  yamt - simplify code
- comments
 1.21.32.1 25-Jun-2018  pgoyette Sync with HEAD
 1.22.8.1 17-Jan-2020  ad Sync with head.
 1.22.2.1 08-Apr-2020  martin Merge changes from current as of 20200406
 1.7 20-Oct-2021  thorpej Don't use genfs_rename_knote() in the "rename foo over hard-link to itself"
case, which simply results in removing the "from" name; there are assertions
in genfs_rename_knote() that are too strong for that case.

PR kern/56460
 1.6 20-Oct-2021  thorpej Overhaul of the EVFILT_VNODE kevent(2) filter:

- Centralize vnode kevent handling in the VOP_*() wrappers, rather than
forcing each individual file system to deal with it (except VOP_RENAME(),
because VOP_RENAME() is a mess and we currently have 2 different ways
of handling it; at least it's reasonably well-centralized in the "new"
way).
- Add support for NOTE_OPEN, NOTE_CLOSE, NOTE_CLOSE_WRITE, and NOTE_READ,
compatible with the same events in FreeBSD.
- Track which kevent notifications clients are interested in receiving
to avoid doing work for events no one cares about (avoiding, e.g.
taking locks and traversing the klist to send a NOTE_WRITE when
someone is merely watching for a file to be deleted, for example).

In support of the above:

- Add support in vnode_if.sh for specifying PRE- and POST-op handlers,
to be invoked before and after vop_pre() and vop_post(), respectively.
Basic idea from FreeBSD, but implemented differently.
- Add support in vnode_if.sh for specifying CONTEXT fields in the
vop_*_args structures. These context fields are used to convey information
between the file system VOP function and the VOP wrapper, but do not
occupy an argument slot in the VOP_*() call itself. These context fields
are initialized and subsequently interpreted by PRE- and POST-op handlers.
- Version VOP_REMOVE(), uses the a context field for the file system to report
back the resulting link count of the target vnode. Return this in tmpfs,
udf, nfs, chfs, ext2fs, lfs, and ufs.

NetBSD 9.99.92.
 1.5 05-Sep-2020  riastradh genfs_rename: Fix deadlocks in cross-directory cyclic rename.

Reproducer:

A: for (;;) { mkdir("c", 0600); mkdir("c/d", 0600); mkdir("c/d/e", 0600);
rmdir("c/d/e"); rmdir("c/d"); }
B: for (;;) { mkdir("c", 0600); mkdir("c/d", 0600); mkdir("c/d/e", 0600);
rename("c", "c/d/e"); }
C: for (;;) { mkdir("c", 0600); mkdir("c/d", 0600); mkdir("c/d/e", 0600);
rename("c/d/e", "c"); }

Deadlock:

- A holds c and wants to lock d; and either
- B holds . and d and wants to lock c, or
- C holds . and d and wants to lock c.

The problem with these is that genfs_rename_enter_separate in B or C
tried lock order .->d->c->e (in A/B, fdvp->tdvp->fvp->tvp; in A/C,
tdvp->fdvp->tvp->fvp) which violates the ancestor->descendant order
.->c->d->e.

The resolution is to change B to do fdvp->fvp->tdvp->tvp and C to do
tdvp->tvp->fdvp->fvp. But there's an edge case: tvp and fvp might be
the same (hard links), and we can't detect that until after we've
looked them both up -- and in some file systems (I'm looking at you,
ufs), there is no mere lookup operation, only lookup-and-lock, so we
can't even hold the lock on one of tvp or fvp when we look up the
other one if there's a chance they might be the same.

Fortunately the cases
(a) tvp = fvp
(b) tvp or fvp is a directory
are mutually exclusive as long as directories cannot be hard-linked.
In case (a) we can just defer locking {tvp, fvp} until the end, because
it can't possibly have {fdvp or fvp, tdvp or tvp} as descendants. In
case (b) we can just lock them in the order fdvp->fvp->tdvp->tvp or
tdvp->tvp->fdvp->fvp if the first one of {fvp, tvp} is a directory,
because it can't possibly coincide with the second one of {fvp, tvp}.

With this change, we can now prove that the locking order is consistent
with the ancestor->descendant partial ordering. Where two nodes are
incommensurate under that partial ordering, they are only ever locked
by rename and there is only ever one rename at a time.

Proof:

- For same-directory renames, genfs_rename_enter_common locks the
directory first and then the children. The order
directory->child[i] is consistent with ancestor->descendant and
child[0]/child[1] are incommensurate.

- For cross-directory renames:

. While a rename is in progress and the fs-wide rename lock is held,
directories can be created or removed but not changed, so the
outcome of gro_genealogy -- which, given fdvp and tdvp, returns
the node N relating fdvp/N/.../tdvp or null if there is none --
can only transition from finding N to not finding N, if one of
the directories is removed while any of the vnodes are unlocked.
Merely creating directories cannot change the ancestry of tdvp,
and concurrent renames are not possible.

Thus, if a gro_genealogy determined the operation to have the
form fdvp/N/.../tdvp, then it might cease to have that form, but
only because tdvp was removed which will harmlessly cause the
rename to fail later on. Similarly, if gro_genealogy determined
the operation _not_ to have the form fdvp/N/.../tdvp then it
can't begin to have that form until after the rename has
completed.

The lock order is,

=> for fdvp/.../tdvp:
1. lock fdvp
2. lookup(/lock/unlock) fvp (consistent with fdvp->fvp)
3. lock fvp if a directory (consistent with fdvp->fvp)
4. lock tdvp (consistent with fdvp->tdvp and possibly fvp->tdvp)
5. lookup(/lock/unlock) tvp (consistent with tdvp->tvp)
6. lock fvp if a nondirectory (fvp->t* or fvp->fdvp is impossible)
7. lock tvp if not fvp (tvp->f* is impossible unless tvp=fvp)

=> for incommensurate fdvp & tdvp, or for tdvp/.../fdvp:
1. lock tdvp
2. lookup(/lock/unlock) tvp (consistent with tdvp->tvp)
3. lock tvp if a directory (consistent with tdvp->tvp)
4. lock fdvp (either incommensurate with tdvp and/or tvp, or
consistent with tdvp(->tvp)->fdvp)
5. lookup(/lock/unlock) fvp (consistent with fdvp->fvp)
6. lock tvp if a nondirectory (tvp->f* or tvp->tdvp is impossible)
7. lock fvp if not tvp (fvp->t* is impossible unless fvp=tvp)

Deadlocks found by hannken@; resolution worked out with dholland@.

XXX I think we could improve concurrency somewhat -- with a likely
big win for applications like tar and rsync that create many files
with temporary names and then rename them to the permanent one in the
same directory -- by making vfs_renamelock a reader/writer lock: any
number of same-directory renames, or exactly one cross-directory
rename, at any one time.
 1.4 16-May-2020  christos Add ACL support for FFS. From FreeBSD.
 1.3 30-Mar-2017  hannken branches: 1.3.18;
Remove now redundant calls to fstrans_start()/fstrans_done().
 1.2 06-Feb-2014  hannken branches: 1.2.6; 1.2.10; 1.2.14;
Move fstrans_start()/fstrans_done() into genfs_insane_rename() to protect
the complete rename operation like we do for all other vnode operations.
 1.1 08-May-2012  riastradh branches: 1.1.2; 1.1.4; 1.1.6; 1.1.8; 1.1.10;
Implement a genfs_rename abstraction.

First major step in incrementally adapting all the file systems to a
saner rename VOP protocol.
 1.1.10.1 18-May-2014  rmind sync with head
 1.1.8.2 03-Dec-2017  jdolecek update from HEAD
 1.1.8.1 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.1.6.2 02-Jul-2012  jdc Pull up revisions:
src/sys/conf/files revision 1.1050
src/sys/miscfs/genfs/genfs.h revision 1.30 via patch
src/sys/miscfs/genfs/genfs_rename.c revision 1.1 via patch
src/sys/rump/librump/rumpvfs/Makefile.rumpvfs revision 1.33
(requested by riastradh in ticket #286).

Implement a genfs_rename abstraction.

First major step in incrementally adapting all the file systems to a
saner rename VOP protocol.
 1.1.6.1 08-May-2012  jdc file genfs_rename.c was added on branch netbsd-6 on 2012-07-02 18:01:17 +0000
 1.1.4.2 02-Jun-2012  mrg sync to latest -current.
 1.1.4.1 08-May-2012  mrg file genfs_rename.c was added on branch jmcneill-usbmp on 2012-06-02 11:09:36 +0000
 1.1.2.3 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.1.2.2 23-May-2012  yamt sync with head.
 1.1.2.1 08-May-2012  yamt file genfs_rename.c was added on branch yamt-pagecache on 2012-05-23 10:08:14 +0000
 1.2.14.1 21-Apr-2017  bouyer Sync with HEAD
 1.2.10.1 26-Apr-2017  pgoyette Sync with HEAD
 1.2.6.1 28-Aug-2017  skrll Sync with HEAD
 1.3.18.1 13-Sep-2020  martin Pull up following revision(s) (requested by riastradh in ticket #1083):

sys/miscfs/genfs/genfs_rename.c: revision 1.5
tests/fs/vfs/t_renamerace.c: revision 1.37
tests/fs/vfs/t_renamerace.c: revision 1.38

tests/fs/vfs/t_renamerace: Test a screw case hannken@ found.

genfs_rename: Fix deadlocks in cross-directory cyclic rename.

Reproducer:
A: for (;;) { mkdir("c", 0600); mkdir("c/d", 0600); mkdir("c/d/e", 0600);
rmdir("c/d/e"); rmdir("c/d"); }
B: for (;;) { mkdir("c", 0600); mkdir("c/d", 0600); mkdir("c/d/e", 0600);
rename("c", "c/d/e"); }
C: for (;;) { mkdir("c", 0600); mkdir("c/d", 0600); mkdir("c/d/e", 0600);
rename("c/d/e", "c"); }

Deadlock:
- A holds c and wants to lock d; and either
- B holds . and d and wants to lock c, or
- C holds . and d and wants to lock c.

The problem with these is that genfs_rename_enter_separate in B or C
tried lock order .->d->c->e (in A/B, fdvp->tdvp->fvp->tvp; in A/C,
tdvp->fdvp->tvp->fvp) which violates the ancestor->descendant order
.->c->d->e.

The resolution is to change B to do fdvp->fvp->tdvp->tvp and C to do
tdvp->tvp->fdvp->fvp. But there's an edge case: tvp and fvp might be
the same (hard links), and we can't detect that until after we've
looked them both up -- and in some file systems (I'm looking at you,
ufs), there is no mere lookup operation, only lookup-and-lock, so we
can't even hold the lock on one of tvp or fvp when we look up the
other one if there's a chance they might be the same.

Fortunately the cases
(a) tvp = fvp
(b) tvp or fvp is a directory
are mutually exclusive as long as directories cannot be hard-linked.

In case (a) we can just defer locking {tvp, fvp} until the end, because
it can't possibly have {fdvp or fvp, tdvp or tvp} as descendants. In
case (b) we can just lock them in the order fdvp->fvp->tdvp->tvp or
tdvp->tvp->fdvp->fvp if the first one of {fvp, tvp} is a directory,
because it can't possibly coincide with the second one of {fvp, tvp}.

With this change, we can now prove that the locking order is consistent
with the ancestor->descendant partial ordering. Where two nodes are
incommensurate under that partial ordering, they are only ever locked
by rename and there is only ever one rename at a time.

Proof:
- For same-directory renames, genfs_rename_enter_common locks the
directory first and then the children. The order
directory->child[i] is consistent with ancestor->descendant and
child[0]/child[1] are incommensurate.
- For cross-directory renames:
. While a rename is in progress and the fs-wide rename lock is held,
directories can be created or removed but not changed, so the
outcome of gro_genealogy -- which, given fdvp and tdvp, returns
the node N relating fdvp/N/.../tdvp or null if there is none --
can only transition from finding N to not finding N, if one of
the directories is removed while any of the vnodes are unlocked.
Merely creating directories cannot change the ancestry of tdvp,
and concurrent renames are not possible.
Thus, if a gro_genealogy determined the operation to have the
form fdvp/N/.../tdvp, then it might cease to have that form, but
only because tdvp was removed which will harmlessly cause the
rename to fail later on. Similarly, if gro_genealogy determined
the operation _not_ to have the form fdvp/N/.../tdvp then it
can't begin to have that form until after the rename has
completed.
The lock order is,
=> for fdvp/.../tdvp:
1. lock fdvp
2. lookup(/lock/unlock) fvp (consistent with fdvp->fvp)
3. lock fvp if a directory (consistent with fdvp->fvp)
4. lock tdvp (consistent with fdvp->tdvp and possibly fvp->tdvp)
5. lookup(/lock/unlock) tvp (consistent with tdvp->tvp)
6. lock fvp if a nondirectory (fvp->t* or fvp->fdvp is impossible)
7. lock tvp if not fvp (tvp->f* is impossible unless tvp=fvp)
=> for incommensurate fdvp & tdvp, or for tdvp/.../fdvp:
1. lock tdvp
2. lookup(/lock/unlock) tvp (consistent with tdvp->tvp)
3. lock tvp if a directory (consistent with tdvp->tvp)
4. lock fdvp (either incommensurate with tdvp and/or tvp, or
consistent with tdvp(->tvp)->fdvp)
5. lookup(/lock/unlock) fvp (consistent with fdvp->fvp)
6. lock tvp if a nondirectory (tvp->f* or tvp->tdvp is impossible)
7. lock fvp if not tvp (fvp->t* is impossible unless fvp=tvp)

Deadlocks found by hannken@; resolution worked out with dholland@.

XXX I think we could improve concurrency somewhat -- with a likely
big win for applications like tar and rsync that create many files
with temporary names and then rename them to the permanent one in the
same directory -- by making vfs_renamelock a reader/writer lock: any
number of same-directory renames, or exactly one cross-directory
rename, at any one time.
 1.11 08-Jul-2022  hannken Handle IMNT_GONE on the file system we want suspended not its
lowest mount we really suspend.
 1.10 22-Dec-2019  ad Make mntvnode_lock per-mount, and address false sharing of struct mount.
 1.9 20-Feb-2019  hannken Attach "mnt_transinfo" to "dead_rootmount" so every mount has a
valid "mnt_transinfo" and remove now unneeded flag IMNT_HAS_TRANS.

Run fstrans_start()/fstrans_done() on dead_rootmount if FSTRANS_DEAD_ENABLED.
Should become the default for DIAGNOSTIC in the future.
 1.8 05-Oct-2018  hannken Bring back three state file system suspension:

NORMAL -> SUSPENDING -> SUSPENDED

and add operation fstrans_start_lazy() that only blocks while SUSPENDED.

Change vndthread() support operation handle_with_rdwr() to bracket
its file system operations by fstrans_start_lazy() and fstrans_done().

PR kern/53624 (dom0 freeze on domU exit)
 1.7 24-May-2017  hannken branches: 1.7.2; 1.7.8; 1.7.10;
With dounmount() working on a suspended file system remove no longer
needed fields mnt_busynest and mnt_unmounting from struct mount.

Welcome to 7.99.73
 1.6 07-May-2017  hannken Return ENOENT if trying to suspend an unmounted file system.
 1.5 30-Mar-2017  hannken branches: 1.5.4;
Change last users of FSTRANS_LAZY to FSTRANS_SHARED and change
genfs_suspendctl() to move from FSTRANS_NORMAL to FSTRANS_SUSPENDED
and vice versa.
 1.4 17-Feb-2017  hannken Add generic genfs_suspendctl() and use it for all file systems.
Layered file systems need work.
 1.3 30-Nov-2009  pooka branches: 1.3.22; 1.3.40; 1.3.44; 1.3.48;
Introduce genfs_statvfs() as pretty much a no-info statvfs and
convert several pseudo file systems to use it.
 1.2 28-Apr-2008  martin Remove clause 3 and 4 from TNF licenses
 1.1 28-Jan-2008  dholland branches: 1.1.2; 1.1.4; 1.1.10; 1.1.12; 1.1.14; 1.1.16;
Part of the rename patches *doh*
 1.1.16.2 11-Mar-2010  yamt sync with head
 1.1.16.1 16-May-2008  yamt sync with head.
 1.1.14.1 18-May-2008  yamt sync with head.
 1.1.12.2 23-Mar-2008  matt sync with HEAD
 1.1.12.1 28-Jan-2008  matt file genfs_vfsops.c was added on branch matt-armv6 on 2008-03-23 02:05:03 +0000
 1.1.10.1 02-Jun-2008  mjf Sync with HEAD.
 1.1.4.2 18-Feb-2008  mjf Sync with HEAD.
 1.1.4.1 28-Jan-2008  mjf file genfs_vfsops.c was added on branch mjf-devfs on 2008-02-18 21:07:00 +0000
 1.1.2.2 04-Feb-2008  yamt sync with head.
 1.1.2.1 28-Jan-2008  yamt file genfs_vfsops.c was added on branch yamt-lazymbuf on 2008-02-04 09:24:29 +0000
 1.3.48.1 21-Apr-2017  bouyer Sync with HEAD
 1.3.44.2 26-Apr-2017  pgoyette Sync with HEAD
 1.3.44.1 20-Mar-2017  pgoyette Sync with HEAD
 1.3.40.1 28-Aug-2017  skrll Sync with HEAD
 1.3.22.1 03-Dec-2017  jdolecek update from HEAD
 1.5.4.1 11-May-2017  pgoyette Sync with HEAD
 1.7.10.2 08-Apr-2020  martin Merge changes from current as of 20200406
 1.7.10.1 10-Jun-2019  christos Sync with HEAD
 1.7.8.1 20-Oct-2018  pgoyette Sync with head
 1.7.2.1 09-Oct-2018  martin Pull up following revision(s) (requested by hannken in ticket #1052):

sys/kern/vfs_trans.c: revision 1.51
distrib/sets/lists/comp/mi: revision 1.2233
share/man/man9/fstrans.9: revision 1.27
share/man/man9/Makefile: revision 1.431
sys/sys/fstrans.h: revision 1.12
sys/rump/librump/rumpkern/emul.c: revision 1.187
sys/dev/vnd.c: revision 1.266
sys/miscfs/genfs/genfs_vfsops.c: revision 1.8

Bring back three state file system suspension:

NORMAL -> SUSPENDING -> SUSPENDED

and add operation fstrans_start_lazy() that only blocks while SUSPENDED.

Change vndthread() support operation handle_with_rdwr() to bracket
its file system operations by fstrans_start_lazy() and fstrans_done().

PR kern/53624 (dom0 freeze on domU exit)
 1.220 03-Mar-2023  hannken Fix genfs_can_chtimes() to also handle the condition:

If the time pointer is null, then write permission
on the file is also sufficient.

From FreeBSD.

Should fix PR kern/57246 "NFS group permissions regression"
 1.219 27-Mar-2022  christos branches: 1.219.4;
dedup the eofs link/symlink methods
 1.218 27-Mar-2022  christos Expose groupmember as kauth_cred_groupmember and use it.
 1.217 19-Mar-2022  hannken Remove now unused genfs_nolock(), genfs_nounlock() and genfs_noislocked().
 1.216 20-Oct-2021  thorpej Overhaul of the EVFILT_VNODE kevent(2) filter:

- Centralize vnode kevent handling in the VOP_*() wrappers, rather than
forcing each individual file system to deal with it (except VOP_RENAME(),
because VOP_RENAME() is a mess and we currently have 2 different ways
of handling it; at least it's reasonably well-centralized in the "new"
way).
- Add support for NOTE_OPEN, NOTE_CLOSE, NOTE_CLOSE_WRITE, and NOTE_READ,
compatible with the same events in FreeBSD.
- Track which kevent notifications clients are interested in receiving
to avoid doing work for events no one cares about (avoiding, e.g.
taking locks and traversing the klist to send a NOTE_WRITE when
someone is merely watching for a file to be deleted, for example).

In support of the above:

- Add support in vnode_if.sh for specifying PRE- and POST-op handlers,
to be invoked before and after vop_pre() and vop_post(), respectively.
Basic idea from FreeBSD, but implemented differently.
- Add support in vnode_if.sh for specifying CONTEXT fields in the
vop_*_args structures. These context fields are used to convey information
between the file system VOP function and the VOP wrapper, but do not
occupy an argument slot in the VOP_*() call itself. These context fields
are initialized and subsequently interpreted by PRE- and POST-op handlers.
- Version VOP_REMOVE(), uses the a context field for the file system to report
back the resulting link count of the target vnode. Return this in tmpfs,
udf, nfs, chfs, ext2fs, lfs, and ufs.

NetBSD 9.99.92.
 1.215 11-Oct-2021  thorpej Mark the EVFILT_VNODE filters MP-safe.
 1.214 11-Oct-2021  thorpej Setting EV_EOF requires modifying kn->kn_flags. However, that relies on
holding the kq_lock of that note's kq. Rather than exposing this directly,
add new knote_set_eof() and knote_clear_eof() functions that handle the
necessary locking and don't leak as many implementation details to modules.

NetBSD 9.99.91
 1.213 10-Oct-2021  thorpej Must hold kn->kn_kq->kq_lock to modify kn->kn_flags.
 1.212 26-Sep-2021  thorpej Change the kqueue filterops::f_isfd field to filterops::f_flags, and
define a flag FILTEROP_ISFD that has the meaning of the prior f_isfd.
Field and flag name aligned with OpenBSD.

This does not constitute a functional or ABI change, as the field location
and size, and the value placed in that field, are the same as the previous
code, but we're bumping __NetBSD_Version__ so 3rd-party module source code
can adapt, as needed.

NetBSD 9.99.89
 1.211 29-Jun-2021  dholland - Add a new vnode op: VOP_PARSEPATH.
- Move namei_getcomponent to genfs_vnops.c and call it genfs_parsepath.
- Add a parsepath entry to every vnode ops table.

VOP_PARSEPATH takes a directory vnode to be searched and a complete
following path and chooses how much of that path to consume. To begin
with, all parsepath calls are genfs_parsepath, which locates the first
'/' as always.

Note that the call doesn't take the whole struct componentname, only
the string. The other bits of struct componentname should not be
needed and there's no reason to cause potential complications by
exposing them.
 1.210 05-Sep-2020  riastradh branches: 1.210.6;
Round of uvm.h cleanup.

The poorly named uvm.h is generally supposed to be for uvm-internal
users only.

- Narrow it to files that actually need it -- mostly files that need
to query whether curlwp is the pagedaemon, which should maybe be
exposed by an external header.

- Use uvm_extern.h where feasible and uvm_*.h for things not exposed
by it. We should split up uvm_extern.h but this will serve for now
to reduce the uvm.h dependencies.

- Use uvm_stat.h and #ifdef UVMHIST uvm.h for files that use
UVMHIST(ubchist), since ubchist is declared in uvm.h but the
reference evaporates if UVMHIST is not defined, so we reduce header
file dependencies.

- Make uvm_device.h and uvm_swap.h independently includable while
here.

ok chs@
 1.209 07-Aug-2020  christos accmode should be accmode_t
 1.208 27-Jun-2020  christos Introduce genfs_pathconf() and use it for the default case in all filesystems.
 1.207 20-May-2020  christos Fix EPERM vs EACCES on chtimes (thanks @hannken)
 1.206 18-May-2020  christos remove debugging, it is just clutter.
 1.205 18-May-2020  christos Fix EPERM vs EACCES return.
 1.204 16-May-2020  christos Add ACL support for FFS. From FreeBSD.
 1.203 25-Apr-2020  christos Allow root to access and modify system space extended attributes.
XXX: this routine should not be using the string, but the attribute namespace.
I have fixed this in the ACL code.
 1.202 23-Feb-2020  ad Merge from ad-namecache:

- Have a stab at clustering the members of vnode_t and vnode_impl_t in a
more cache-conscious way. With that done, go back to adjusting v_usecount
with atomics and keep vi_lock directly in vnode_impl_t (saves KVA).

- Allow VOP_LOCK(LK_NONE) for the benefit of VFS_VGET() and VFS_ROOT().
Make sure LK_UPGRADE always comes with LK_NOWAIT.

- Make cwdinfo use mostly lockless.
 1.201 23-Feb-2020  ad UVM locking changes, proposed on tech-kern:

- Change the lock on uvm_object, vm_amap and vm_anon to be a RW lock.
- Break v_interlock and vmobjlock apart. v_interlock remains a mutex.
- Do partial PV list locking in the x86 pmap. Others to follow later.
 1.200 01-Dec-2019  ad branches: 1.200.2;
Minor vnode locking changes:

- Stop using atomics to maniupulate v_usecount. It was a mistake to begin
with. It doesn't work as intended unless the XLOCK bit is incorporated in
v_usecount and we don't have that any more. When I introduced this 10+
years ago it was to reduce pressure on v_interlock but it doesn't do that,
it just makes stuff disappear from lockstat output and introduces problems
elsewhere. We could do atomic usecounts on vnodes but there has to be a
well thought out scheme.

- Resurrect LK_UPGRADE/LK_DOWNGRADE which will be needed to work effectively
when there is increased use of shared locks on vnodes.

- Allocate the vnode lock using rw_obj_alloc() to reduce false sharing of
struct vnode.

- Put all of the LRU lists into a single cache line, and do not requeue a
vnode if it's already on the correct list and was requeued recently (less
than a second ago).

Kernel build before and after:

119.63s real 1453.16s user 2742.57s system
115.29s real 1401.52s user 2690.94s system
 1.199 25-Oct-2017  maya branches: 1.199.4;
Use C99 initializer for filterops

Mostly done with spatch with touchups for indentation

@@
expression a;
identifier b,c,d;
identifier p;
@@
const struct filterops p =
- { a, b, c, d
+ {
+ .f_isfd = a,
+ .f_attach = b,
+ .f_detach = c,
+ .f_event = d,
};
 1.198 01-Jul-2017  christos Provide EVFILT_WRITE; this is what FreeBSD does and go wants it.
Makes go unit tests pass.
 1.197 04-Jun-2017  hannken Locking a layer vnode using the regular bypass routine is no longer
racy. Undo the change from 2017-03-30 11:16:52, commitid eurqbzuGxGRlryLz
and make vi_lock a krwlock_t again.
 1.196 04-Jun-2017  hannken Now that FSTRANS is part of VOP_*LOCK() remove FSTRANS and vdead_check()
from genfs_.*lock() and assert the vnode state once the vnode is locked.
 1.195 11-Apr-2017  riastradh branches: 1.195.4;
Eliminate now-unused WILLUNLOCK vop flag.
 1.194 30-Mar-2017  hannken Locking a layer vnode is racy as it may become reclaimed before
calling the operation on the lower vnode.

Replace vi_lock with a rw_obj and change layered file systems
to share the lock with the lower vnode.

Layered file systems now use genfs_lock()/_unlock/_islocked().

Welcome to 7.99.67
 1.193 11-Jan-2017  hannken branches: 1.193.2;
Move vnode member v_lock as vi_lock to vnode_impl.h.
 1.192 24-Mar-2014  hannken branches: 1.192.4; 1.192.6; 1.192.8; 1.192.10; 1.192.14;
- Make VI_XLOCK, VI_CLEAN and VI_LOCKSHARE private to kern/vfs_*.c.
- Make vwait() static.
- Add vdead_check() to check a vnode for being or becoming dead.

Discussed on tech-kern.

Welcome to 6.99.38
 1.191 12-Mar-2014  hannken Restructure genfs_deadlock() and genfs_lock() to always lock before
testing for dead node. Use ISSET() to test flags, add assertions.

Save the mount for fstrans_done() before genfs_unlock() unlocks the node.
 1.190 27-Feb-2014  hannken The current implementation of vn_lock() is racy. Modification of
the vnode operations vector for active vnodes is unsafe because it
is not known whether deadfs or the original file system will be
called.

- Pass down LK_RETRY to the lock operation (hint for deadfs only).

- Change deadfs lock operation to return ENOENT if LK_RETRY is unset.

- Change all other lock operations to check for dead vnode once
the vnode is locked and unlock and return ENOENT in this case.

With these changes in place vnode lock operations will never succeed
after vclean() has marked the vnode as VI_XLOCK and before vclean()
has changed the operations vector.

Adresses PR kern/37706 (Forced unmount of file systems is unsafe)

Discussed on tech-kern.

Welcome to 6.99.33
 1.189 30-Mar-2012  njoly branches: 1.189.2; 1.189.4;
uid mismatch for file flags changes is expected to fail with EPERM not
EACCES.
 1.188 13-Mar-2012  elad Replace the remaining KAUTH_GENERIC_ISSUSER authorization calls with
something meaningful. All relevant documentation has been updated or
written.

Most of these changes were brought up in the following messages:

http://mail-index.netbsd.org/tech-kern/2012/01/18/msg012490.html
http://mail-index.netbsd.org/tech-kern/2012/01/19/msg012502.html
http://mail-index.netbsd.org/tech-kern/2012/02/17/msg012728.html

Thanks to christos, manu, njoly, and jmmv for input.

Huge thanks to pgoyette for spinning these changes through some build
cycles and ATF.
 1.187 12-Jun-2011  rmind branches: 1.187.2; 1.187.6;
Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.
 1.186 27-Dec-2010  hannken branches: 1.186.6;
Extend the range of fstrans transactions to a sequence of vnode operations
on a locked vnode. This leaves a suspended file system and therefore a
snapshot with either all or no operations of such a sequence done.
 1.185 30-Nov-2010  dholland Abolish the SAVENAME and HASBUF flags. There is now always a buffer,
so the path in a struct componentname is now always valid during VOP
calls.
 1.184 30-Nov-2010  dholland Abolish struct componentname's cn_pnbuf. Use the path buffer in the
pathbuf object passed to namei as work space instead. (For now a pnbuf
pointer appears in struct nameidata, to support certain unclean things
that haven't been fixed yet, but it will be going away in the future.)

This removes the need for the SAVENAME and HASBUF namei flags.
 1.183 01-Sep-2010  chs replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.182 01-Jul-2010  hannken Remove vlockmgr(). Generic vnode lock operations now use a rwlock located
in the vnode. All LK_* flags move from sys/lock.h to sys/vnode.h. Calls
to vlockmgr() in file systems get replaced with VOP_LOCK() or VOP_UNLOCK().

Welcome to 5.99.34.

Discussed on tech-kern.
 1.181 24-Jun-2010  hannken Clean up vnode lock operations pass 2:

VOP_UNLOCK(vp, flags) -> VOP_UNLOCK(vp): Remove the unneeded flags argument.

Welcome to 5.99.32.

Discussed on tech-kern.
 1.180 24-Jun-2010  hannken genfs_nolock(): LK_INTERLOCK flag no longer possible.
 1.179 24-Jun-2010  hannken Clean up vnode lock operations:

- VOP_LOCK(vp, flags): Limit the set of allowed flags to LK_EXCLUSIVE,
LK_SHARED and LK_NOWAIT. LK_INTERLOCK is no longer allowed as it
makes no sense here.

- VOP_ISLOCKED(vp): Remove the for some time unused return value
LK_EXCLOTHER. Mark this operation as "diagnostic only".
Making a lock decision based on this operation is no longer allowed.

Discussed on tech-kern.
 1.178 06-Jun-2010  hannken Change layered file systems to always pass the locking VOP's down to the
leaf file system. Remove now unused member v_vnlock from struct vnode.
Welcome to 5.99.30

Discussed on tech-kern.
 1.177 08-Apr-2010  pooka Call VOP_ABORTOP in genfs_eopnotsupp. This prevents file system
authors from having to get down on their knees and pray they won't
get POGA'd(*) again.

This plugs componentname leaks in at least smbfs and buggy puffs
servers (buggy servers shouldn't be able to leak kernel memory).

*) principle of greatest astonishment
 1.176 27-Jan-2010  uebayasi branches: 1.176.2; 1.176.4;
Don't forget to tell the result of rw_tryenter().
 1.175 27-Jan-2010  uebayasi Add genfs_node_rdtrylock().
 1.174 20-Nov-2009  roy Allow chown if caller is in the new group.
 1.173 20-Nov-2009  pooka Disallow chown for files the caller does not own.
 1.172 23-Jun-2009  elad Move the implementation of vaccess() to genfs_can_access(), in line with
the other routines of the same spirit.

Adjust file-system code to use it.

Keep vaccess() for KPI compatibility and to keep element of least
surprise. A "diagnostic" message warning that vaccess() is deprecated will
be printed when it's used (obviously, only in DIAGNOSTIC kernels).

No objections on tech-kern@:

http://mail-index.netbsd.org/tech-kern/2009/06/21/msg005310.html
 1.171 07-May-2009  elad Extract the open-coded authorization logic for chtimes() from various
file-systems and put it in a single function, genfs_can_chtimes().

This also makes UDF follow the same policy as all other file-systems.

Mailing list reference:

http://mail-index.netbsd.org/tech-kern/2009/04/27/msg004951.html
 1.170 25-Apr-2009  elad Add genfs_can_mount() and use it to prevent some more code duplication of
the security checks when mounting a device (VOP_ACCESS() + kauth(9) call)).

Proposed with no objections on tech-kern@:

http://mail-index.netbsd.org/tech-kern/2009/04/20/msg004859.html

The vnode is always expected to be locked, so no locking is done outside
the file-system code.
 1.169 22-Apr-2009  elad Per discussion on tech-kern@:

- Replace use of label/goto with returns

- Rename, change prototype of, and move functions from vfs_subr.c to
genfs_vnops.c
 1.168 18-Apr-2009  pooka Move genfs_null_putpages() from genfs_io.c to genfs_vnops.c -- it does
not really do i/o.
 1.167 28-Apr-2008  martin branches: 1.167.8; 1.167.10; 1.167.14; 1.167.16; 1.167.18;
Remove clause 3 and 4 from TNF licenses
 1.166 19-Apr-2008  hannken branches: 1.166.2;
Remove stale include <sys/fstrans.h>.
 1.165 21-Mar-2008  ad branches: 1.165.2;
Catch up with descriptor handling changes. See kern_descrip.c revision
1.173 for details.
 1.164 05-Feb-2008  ad branches: 1.164.6;
Lock v_knlist with the vnode interlock. PR kern/37881.
 1.163 30-Jan-2008  ad Replace struct lock on vnodes with a simpler lock object built on
krwlock_t. This is a step towards removing lockmgr and simplifying
vnode locking. Discussed on tech-kern.
 1.162 25-Jan-2008  riz Since VOP_LEASE is gone, remove genfs_lease_check() too. Now my kernel
builds again. :)
 1.161 17-Jan-2008  ad Fix v_freelisthd assertion failure during call to vdevdone(). No calling
VOPs without a vnode reference!
 1.160 02-Jan-2008  ad Merge vmlocking2 to head.
 1.159 05-Dec-2007  pooka branches: 1.159.4;
Do not "return 1" from kqfilter for errors. That value is passed
directly to the userland caller and results in a mysterious EPERM.
Instead, return EINVAL or something else sensible depending on the
case.
 1.158 17-Oct-2007  pooka branches: 1.158.4; 1.158.6;
Split I/O-related routines (getpages, putpages, etc.) which are heavily
tied to uvm out of genfs_vnops into genfs_io.c
 1.157 10-Oct-2007  ad Merge from vmlocking:

- Split vnode::v_flag into three fields, depending on field locking.
- simple_lock -> kmutex in a few places.
- Fix some simple locking problems.
 1.156 29-Jul-2007  ad branches: 1.156.4; 1.156.6; 1.156.8; 1.156.10;
It's not a good idea for device drivers to modify b_flags, as they don't
need to understand the locking around that field. Instead of setting
B_ERROR, set b_error instead. b_error is 'owned' by whoever completes
the I/O request.
 1.155 09-Jul-2007  ad branches: 1.155.2;
Merge some of the less invasive changes from the vmlocking branch:

- kthread, callout, devsw API changes
- select()/poll() improvements
- miscellaneous MT safety improvements
 1.154 05-Jun-2007  yamt improve post-ubc file overwrite performance in common cases.
ie. when it's safe, actually overwrite blocks rather than doing
read-modify-write.

also fixes PR/33152 and PR/36303.
 1.153 17-May-2007  hannken Fstrans_start() always returns zero, so change its type to void.
 1.152 13-May-2007  yamt use a cached value of v_size. no functional changes.
 1.151 24-Apr-2007  perseant Split the VOP interface part of genfs_putpages() from the code. The new
function that does the work, genfs_do_putpages(), now takes as an argument
a pointer to the page that would be waited on, if PGO_BUSYWAIT were not set.
This allows a consumer, e.g. lfs_putpages(), to perform an action outside
the scope of UVM before sleeping on the page in question.
 1.150 04-Mar-2007  christos branches: 1.150.2; 1.150.4;
Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.
 1.149 22-Feb-2007  thorpej TRUE -> true, FALSE -> false
 1.148 21-Feb-2007  thorpej Replace the Mach-derived boolean_t type with the C99 bool type. A
future commit will replace use of TRUE and FALSE with true and false.
 1.147 20-Feb-2007  ad Add genfs_node_destroy(). Fixes a lock "leak" seen when running LOCKDEBUG
kernels.
 1.146 15-Feb-2007  ad branches: 1.146.2;
Replace some uses of lockmgr() / simplelocks.
 1.145 09-Feb-2007  ad Merge newlock2 to head.
 1.144 29-Jan-2007  hannken Change fstrans enum types to upper case.
No functional change.

From Antti Kantee <pooka@netbsd.org>
 1.143 19-Jan-2007  hannken New file system suspension API to replace vn_start_write and vn_finished_write.
The suspension helpers are now put into file system specific operations.
This means every file system not supporting these helpers cannot be suspended
and therefore snapshots are no longer possible.

Implemented for file systems of type ffs.

The new API is enabled on a kernel option NEWVNGATE. This option is
not enabled by default in any kernel config.

Presented and discussed on tech-kern with much input from
Bill Studenmund <wrstuden@netbsd.org> and YAMAMOTO Takashi <yamt@netbsd.org>.

Welcome to 4.99.9 (new vfs op vfs_suspendctl).
 1.142 27-Dec-2006  yamt remove nqnfs.
 1.141 15-Dec-2006  yamt put ->K loaned pages on the page queue, so that page loaning doesn't
disturb pagedaemon/pdpolicy.
 1.140 30-Nov-2006  pooka branches: 1.140.2; 1.140.4;
* update comments before putpages(): the vm object is always returned
unlocked instead of locked. chuq agrees
* use slock set to &uobj->vmobjlock also for the last simple lock
operation to be consistent with the rest of the function
 1.139 25-Nov-2006  christos instead of const int, use a #define which most of the time will evaluate
in a compile-time constant.
 1.138 16-Nov-2006  christos __unused removal on arguments; approved by core.
 1.137 20-Oct-2006  reinoud Replace the LIST structure mp->mnt_vnodelist to a TAILQ structure since all
vnodes were synced and processed backwards. This meant that the last
accessed node was processed first and the earlierst last.

An extra benefit is the removal of the ugly hack from the Berkly days on
LFS.

In the proces, i've also replaced the various variations hand written loops
by the TAILQ_FOREACH() macro's.
 1.136 14-Oct-2006  yamt add wrapper functions of lockmgr on g_glock.
 1.135 14-Oct-2006  yamt genfs_getpages: use kmem_zalloc.
 1.134 14-Oct-2006  yamt genfs_do_io: iodone handler should be called at splbio.
 1.133 12-Oct-2006  yamt genfs_putpages: don't try to deactivate loaned pages.
reported and tested by Nicolas Joly on current-users@.
 1.132 12-Oct-2006  thorpej genfs_lease_check(): Consume the arguments even if NFSSERVER is not defined.
 1.131 12-Oct-2006  christos - sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386
 1.130 05-Oct-2006  chs add support for O_DIRECT (I/O directly to application memory,
bypassing any kernel caching for file data).
 1.129 15-Sep-2006  yamt branches: 1.129.2;
merge yamt-pdpolicy branch.
- separate page replacement policy from the rest of kernel
- implement an alternative replacement policy
 1.128 23-Jul-2006  ad branches: 1.128.4;
Use the LWP cached credentials where sane.
 1.127 22-Jul-2006  yamt - genfs_getpages: in the case of PGO_LOCKED, check if we can acquire
g_glock as suggested by Chuck Silvers on tech-kern@.
- genfs_rel_pages: handle PGO_DONTCARE so that it can be used for the above.
 1.126 22-Jul-2006  yamt - in genfs_getpages, take g_glock earlier so that it can't be
intervened by truncation.
it also fixes a deadlock. (g_glock vs pages locking order)
- uvm_vnp_setsize: modify v_size while holding v_interlock.

reviewed by Chuck Silvers.
 1.125 14-May-2006  elad integrate kauth.
 1.124 11-Apr-2006  yamt genfs_getpages:
- use "overwrite" variable consistently.
- remove a set-only variable.
no functional changes.
 1.123 30-Mar-2006  yamt some cleanups after the introduction of GOP_SIZE_MEM flag.
- remove GOP_SIZE_READ/GOP_SIZE_WRITE flags.
they have not been used since the change.
- ufs_balloc_range: remove code which has been no-op since the change.
thanks Konrad Schroder for explaining the original intention of the code.
- ffs_gop_size: don't extend past eof, in the case of GOP_SIZE_MEM.
otherwise genfs_getpages end up to allocate pages past eof unnecessarily.
 1.122 01-Mar-2006  yamt branches: 1.122.2; 1.122.4; 1.122.6;
merge yamt-uio_vmspace branch.

- use vmspace rather than proc or lwp where appropriate.
the latter is more natural to specify an address space.
(and less likely to be abused for random purposes.)
- fix a swdmover race.
 1.121 16-Jan-2006  reinoud branches: 1.121.2; 1.121.4;
Add genfs support for directories and softlinks next to regular files and
block devices.

Discussed on tech-kern and ok'd by Chuck
 1.120 11-Jan-2006  yamt use nestiobuf api for genfs.
 1.119 04-Jan-2006  yamt - add simple functions to allocate/free a buffer for i/o.
- make bufpool static.
 1.118 24-Dec-2005  perry branches: 1.118.2;
Remove leading __ from __(const|inline|signed|volatile) -- it is obsolete.
 1.117 15-Dec-2005  yamt fix lock/unlock mismatch in rev.1.115.
reported by Chris Tribo on current-users@.
 1.116 11-Dec-2005  christos merge ktrace-lwp.
 1.115 03-Dec-2005  yamt genfs_compat_getpages: add minimum support of async get. ie. ignore them.
should fix a crash reported by Jukka Salmi on current-users@.
 1.114 02-Dec-2005  yamt genfs_gop_write: use devvp directly as genfs_getpages does.
 1.113 02-Dec-2005  yamt genfs_putpages: initialize marker pages only when needed.
 1.112 30-Nov-2005  yamt revert rev.1.111 as it isn't necessary or correct.
- currently no one in tree has a problem with zero b_lblkno, afaik.
- this buf is used for "devvp", so it doesn't make sense to
use lbn in the "vp".
 1.111 30-Nov-2005  reinoud Learn genfs that (struct buf *)->b_lblkno allways need to point to the
logical block number of the file instead of allways zero.
 1.110 29-Nov-2005  yamt merge yamt-readahead branch.
 1.109 12-Nov-2005  yamt branches: 1.109.2;
genfs_getpages:
- add an assertion.
- call VOP_STRATEGY of underlying vnode directly, rather than
through the filesystem vnode.
- no need to set b_dev here because VOP_STRATEGY will take care of it.
 1.108 02-Nov-2005  yamt merge yamt-vop branch. remove following VOPs.

VOP_BLKATOFF
VOP_VALLOC
VOP_BALLOC
VOP_REALLOCBLKS
VOP_VFREE
VOP_TRUNCATE
VOP_UPDATE
 1.107 07-Oct-2005  elad branches: 1.107.2;
Remove Veriexec bits from genfs, don't #if 0 them.
 1.106 07-Oct-2005  elad Various fixes from blymn@ and myself.

Also, put genfs changes under #if 0, and don't do per-page fingerprints
until this is properly discussed, as requested by yamt@.
 1.105 05-Oct-2005  elad Introduce per-page fingerprints in Veriexec.

This closes a hole pointed out by Thor Lancelot Simon on tech-kern ~3
years ago.

The problem was with running binaries from remote storage, where our
kernel (and Veriexec) has no control over any changes to files.

An attacker could, after the fingerprint has been verified and
program loaded to memory, inject malicious code into the backing
store on the remote storage, followed by a forced flush, causing
a page-in of the malicious data from backing store, bypassing
integrity checks.

Initial implementation by Brett Lymn.
 1.104 26-Jul-2005  yamt don't write-protect wired pages. pointed by Chuck Silvers.
for now, leave a vnode on the syncer's queue, as suggested by him.
 1.103 23-Jul-2005  yamt update file timestamps for nfsd loaned-read and mmap.
PR/25279. discussed on tech-kern@.
 1.102 17-Jul-2005  yamt genfs_putpages: don't bother to clean the vnode unless VONWORKLST.
 1.101 17-Jul-2005  yamt ensure that vnodes with dirty pages are always on syncer's queue.

- genfs_putpages: wait for i/o completion of PG_RELEASED/PG_PAGEOUT pages by
setting "wasclean" false when encountering them.
suggested by Stephan Uphoff in PR/24596 (1).

- genfs_putpages: write protect pages when cleaning out, if
we're going to take the vnode off the syncer's queue.
uvm_fault: don't write-map pages unless its vnode is already on
the syncer's queue.

fix PR/24596 (3) but in the different way from the suggested fix.
(to keep our current behaviour, ie. not to require explicit msync.
discussed on tech-kern@.)

- genfs_putpages: don't mistakenly take a vnode off the queue
by introducing a generation number in genfs_node.
genfs_getpages: increment the generation number.
suggested by Stephan Uphoff in PR/24596 (2).

- add some assertions.
 1.100 17-Jul-2005  yamt - introduce PGO_NOBLOCKALLOC and use it for ubc mapping
to prevent unnecessary block allocations in the case that
page size > block size.

- ufs_balloc_range: use VM_PROT_WRITE+PGO_NOBLOCKALLOC rather than
VM_PROT_READ.
 1.99 16-Jul-2005  yamt genfs_getpages: don't forget to put the vnode onto the syncer's work queue
even in the case of PGO_LOCKED.
 1.98 28-Jun-2005  yamt branches: 1.98.2;
- constify genfs_ops.
- use member designators.
 1.97 29-May-2005  christos - sprinkle const
- avoid shadowed variables.
 1.96 26-Feb-2005  perry branches: 1.96.2;
nuke trailing whitespace
 1.95 16-Feb-2005  chs undo the part of rev. 1.93 that turned the past-EOF check into an assertion.
read() can't request pages past EOF, but mmap() can. apparently I had
disengaged the brain when I said that was ok.
 1.94 25-Jan-2005  wrstuden Extend fsync_range(2) to support the FDISKSYNC flag, which requests
that the sync be propogated out through the disk drive caches.
 1.93 25-Jan-2005  drochner branches: 1.93.2;
-in the read-ahead code, avoid to issue read requests at/past EOF
-because noone should request reads past EOF, or writes past EOF which
are not explicitely marked as file-extending (PGO_PASTEOF), turn
a boundary check into a KASSERT
approved by Chuck Silvers
 1.92 22-Dec-2004  dbj branches: 1.92.2;
check for _KERNEL_OPT around opt include
 1.91 04-Oct-2004  enami Backout previous; seeing many busy page on the pageq is normal.
 1.90 03-Oct-2004  enami So that not to leave pages busy unnecessarily, bound to specified region
when building cluster if we aren't pagedaemon and clean entire cluster
if we are pagedaemon.
 1.89 03-Oct-2004  enami Count obj pages freed by pagedaemon.
 1.88 17-Sep-2004  skrll There's no need to pass a proc value when using UIO_SYSSPACE with
vn_rdwr(9) and uiomove(9).

OK'd by Jason Thorpe
 1.87 27-May-2004  yamt - remove a comment which is no longer true.
- add "XXX vn_lock" comments where we can call VOP_READ/WRITE
without vnode lock held. (genfs_compat_*)
 1.86 25-May-2004  hannken Add ffs internal snapshots. Written by Marshall Kirk McKusick for FreeBSD.

- Not enabled by default. Needs kernel option FFS_SNAPSHOT.
- Change parameters of ffs_blkfree.
- Let the copy-on-write functions return an error so spec_strategy
may fail if the copy-on-write fails.
- Change genfs_*lock*() to use vp->v_vnlock instead of &vp->v_lock.
- Add flag B_METAONLY to VOP_BALLOC to return indirect block buffer.
- Add a function ffs_checkfreefile needed for snapshot creation.
- Add special handling of snapshot files:
Snapshots may not be opened for writing and the attributes are read-only.
Use the mtime as the time this snapshot was taken.
Deny mtime updates for snapshot files.
- Add function transferlockers to transfer any waiting processes from
one lock to another.
- Add vfsop VFS_SNAPSHOT to take a snapshot and make it accessible through
a vnode.
- Add snapshot support to ls, fsck_ffs and dump.

Welcome to 2.0F.

Approved by: Jason R. Thorpe <thorpej@netbsd.org>
 1.85 25-Jan-2004  hannken Make VOP_STRATEGY(bp) a real VOP as discussed on tech-kern.

VOP_STRATEGY(bp) is replaced by one of two new functions:

- VOP_STRATEGY(vp, bp) Call the strategy routine of vp for bp.
- DEV_STRATEGY(bp) Call the d_strategy routine of bp->b_dev for bp.

DEV_STRATEGY(bp) is used only for block-to-block device situations.
 1.84 10-Jan-2004  yamt store a i/o priority hint in struct buf for buffer queue discipline.
 1.83 27-Nov-2003  pk genfs_revoke: use ltsleep() to release the vnode spin lock to avoid a
sleep/wakeup race.
 1.82 24-Sep-2003  yamt fix a bug of lfs.

genfs_getpages() can read in more blocks than it should due to faked filesize
of lfs_gop_size(). it's a security problem and it makes gcc3 "internal error"

to fix this,
- in genfs_getpages(), always calculate diskeof and memeof separately
so that filesystems (in this case, lfs) can use different strategies
for them.
- introduce GOP_SIZE_MEM flag and use it to request in-core filesize.
(it was an intention of GOP_SIZE_READ,
but after the above change _READ is not a straightforward name)

after this, no one uses GOP_SIZE_{READ,WRITE} anymore but leave them for now.
 1.81 07-Aug-2003  agc Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.
 1.80 29-Jun-2003  fvdl branches: 1.80.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.
 1.79 28-Jun-2003  darrenr Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V
 1.78 17-Jun-2003  simonb Micro-optimisation- move the "pgs == NULL" check from the previous
change to immediately after the malloc call. This can't fail in
the non-malloc case.

Reviewd by YAMAMOTO Takashi.
 1.77 15-Jun-2003  yamt genfs_getpages: if number of pages requested is >16,
use malloc/free for array of pointers to vm_page.
otherwise, use on-stack array as used to.
this change fixes assertion failure when nfsd gets a big read request
that isn't aligned with filesystem block.
discussed on tech-kern.
 1.76 23-Apr-2003  tls Correct use of MAXBSIZE where MAXPHYS was intended. This is a necessary
first step towards per-device MAXPHYS, and has the beneficial side effect
of allowing clustering to MAXPHYS even on systems that need to run with
a reduced MAXBSIZE to get more metadata buffers.
 1.75 10-Apr-2003  jdolecek use former genfs_eopnotsupp_rele() as genfs_eopnotsupp(), so that vnodes
are vput()/vrele()d as necessary - some filesystems did use the wrong
one for some ops, and it's just safer to not take the chance

based on suggestion by Bill Studenmund
 1.74 10-Apr-2003  jdolecek improve genfs_eopnotsupp_rele() so that's usable for vop_rename,
which uses WILLPUT for member which may be NULL
handle correctly dvp == vp case for WILLPUT members, so this works
for vop_remove, vop_rename

thanks Bill Studenmund for code&comments on this
 1.73 25-Feb-2003  thorpej Add a new BUF_INIT() macro which initializes b_dep and b_interlock, and
use it. This fixes a few places where either b_dep or b_interlock were
not properly initialized.
 1.72 17-Feb-2003  perseant Add code to UBCify LFS. This is still behind "#ifdef LFS_UBC" for now
(there are still some details to work out) but expect that to go
away soon. To support these basic changes (creation of lfs_putpages,
lfs_gop_write, mods to lfs_balloc) several other changes were made, to
wit:

* Create a writer daemon kernel thread whose purpose is to handle page
writes for the pagedaemon, but which also takes over some of the
functions of lfs_check(). This thread is started the first time an
LFS is mounted.

* Add a "flags" parameter to GOP_SIZE. Current values are
GOP_SIZE_READ, meaning that the call should return the size of the
in-core version of the file, and GOP_SIZE_WRITE, meaning that it
should return the on-disk size. One of GOP_SIZE_READ or
GOP_SIZE_WRITE must be specified.

* Instead of using malloc(...M_WAITOK) for everything, reserve enough
resources to get by and use malloc(...M_NOWAIT), using the reserves if
necessary. Use the pool subsystem for structures small enough that
this is feasible. This also obsoletes LFS_THROTTLE.

And a few that are not strictly necessary:

* Moves the LFS inode extensions off onto a separately allocated
structure; getting closer to LFS as an LKM. "Welcome to 1.6O."

* Unified GOP_ALLOC between FFS and LFS.

* Update LFS copyright headers to correct values.

* Actually cast to unsigned in lfs_shellsort, like the comment says.

* Keep track of which segments were empty before the previous
checkpoint; any segments that pass two checkpoints both dirty and
empty can be summarily cleaned. Do this. Right now lfs_segclean
still works, but this should be turned into an effectless
compatibility syscall.
 1.71 05-Feb-2003  pk Make the buffer cache code MP-safe.
 1.70 21-Jan-2003  christos step 3. Assign lwp properly if null, so that we can PHOLD without segfaulting.
 1.69 18-Jan-2003  thorpej Merge the nathanw_sa branch.
 1.68 15-Nov-2002  yamt genfs_compat_gop_write: set uio_iovcnt correctly.
 1.67 25-Oct-2002  yamt use B_ASYNC for children of nested buffers in genfs_getpages.
ok'ed by Chuck Silvers.
 1.66 23-Oct-2002  jdolecek merge kqueue branch into -current

kqueue provides a stateful and efficient event notification framework
currently supported events include socket, file, directory, fifo,
pipe, tty and device changes, and monitoring of processes and signals

kqueue is supported by all writable filesystems in NetBSD tree
(with exception of Coda) and all device drivers supporting poll(2)

based on work done by Jonathan Lemon for FreeBSD
initial NetBSD port done by Luke Mewburn and Jason Thorpe
 1.65 21-Oct-2002  fvdl Use B_ASYNC in the !PGO_SYNCIO case. Gets back most, if not all, NFS
read throughput performance lost since the introduction of UBC. Spotted
by YAMAMOTO Takashi, many thanks to him.
 1.64 29-May-2002  enami Add missing pageq lock while uvm_pagefree() is called (either directly
or indirectly). Reviewed by chuq.
 1.63 18-May-2002  enami branches: 1.63.2;
Just give up to do readahead rather than waiting busy pages.
While I'm here, added few patchable variable so that one can
easily measure readahead behaviour.
 1.62 14-May-2002  perseant branches: 1.62.2;
Protect v_synclist with splbio(); note that LIST_REMOVE is not an idempotent
operation if more than one LIST_REMOVE happens on interrupt, so both the test
for VONWORKLIST and the LIST_REMOVE(vp, v_synclist) need to be in splbio().
 1.61 10-May-2002  enami Redo rev. 1.57 a bit different way; don't use `tpg' since it may be freed.
Subtract the number of pages behind us when calculating new offset instead.
 1.60 10-May-2002  enami Don't modify the local variable `n' in genfs_putpages(). It should contain
the number of elements in the page array at the beginning of every iteration.
 1.59 09-May-2002  enami When traversing by list, if the page next to us is a page in the cluster,
advance the pointer.
 1.58 09-May-2002  enami - In genfs_putpages(), no need to restrict the cluster within the given
region.
- In uvm_aio_aiodone(), remove assertions no longer true.
 1.57 06-May-2002  enami Since npages may includes number of pages behind us, we can't use it to
update current offset. Instead, use the last page in the run of pages
to calculate new offset.
 1.56 06-May-2002  enami Stylistic change; introduce new local variable and use it instead of
sprinkling different expression to test if we're pagedaemon.
 1.55 26-Apr-2002  enami We don't need to re-activate page in genfs_putpages() when GOP_WRITE returns
ENOMEM (temporary memory shortage) since it is already handled in
uvm_aio_aiodone() for both async/sync case. Discussed with chuq.
 1.54 16-Apr-2002  enami genfs_{compat_}getpages(): For PGO_LOCKED request, it is safe to return
read only page if it was due to read fault. This avoid many unnecessary
read fault introduced by recent nfs_bio.c change. Reviewed by chuq.
 1.53 16-Apr-2002  enami KNF and other misc. cosmetic changes.
 1.52 22-Mar-2002  chs in genfs_compat_getpages(), clear any part of a page that
VOP_READ() doesn't fill in (eg. because it's past EOF).
 1.51 17-Mar-2002  atatat Convert ioctl code to use EPASSTHROUGH instead of -1 or ENOTTY for
indicating an unhandled "command". ERESTART is -1, which can lead to
confusion. ERESTART has been moved to -3 and EPASSTHROUGH has been
placed at -4. No ioctl code should now return -1 anywhere. The
ioctl() system call is now properly restartable.
 1.50 02-Mar-2002  chs don't yield the cpu in genfs_putpages() if we're the pagedaemon.
pointed out by enami. fixes PR 15784.
 1.49 19-Feb-2002  chs fix two problems:
- when yielding the cpu while using the vnode's page list, use a marker page
to keep our place in the list (like the other cases where we drop the lock).
- wait until no one else has the page busy before deciding if the page needs
to be cleaned. a page will be dirty while it's being initialized but will
be marked clean before PG_BUSY is cleared.
both found by enami.
 1.48 13-Feb-2002  enami Don't bother to subtract 0.
 1.47 12-Feb-2002  enami Don't leave junk in pgs[] array since it will be passed to uvn_findpages()
again.
 1.46 26-Jan-2002  chs in genfs_putpages():
- yield the cpu if we've taken too long.
- when traversing by offset, skip over any pages that we clustered.
 1.45 31-Dec-2001  chs in genfs_gop_write(), actually set the B_ASYNC flag on buffers that we're
not going to wait for. this doesn't matter for real devices since we call
VOP_STRATEGY() directly, but NFS uses this flag to decide whether or not
to hand the buffer off to an nfsiod thread.
 1.44 31-Dec-2001  chs in genfs_putpages(), we must wait for any pending write i/os to complete
if the putpages request is synchronous.
 1.43 18-Dec-2001  chs add some compatibility routines to allow mmap() to work non-UBCified
filesystems (in the same non-coherent fashion that they worked before).
 1.42 06-Dec-2001  chs add a VOP_PUTPAGES method for all the filesystems that don't have pages,
just unlock the interlock.
 1.41 30-Nov-2001  christos PR/14781: Matthew Fredette: Clamp the number of read-ahead pages to 16 because
other code has this limit. Also while I am here, convert the magic 16 into
a #define constant and use it in the appropriate places. This is a temporary
fix, since all this read-ahead business is XXXUBC anyway.
 1.40 10-Nov-2001  lukem add RCSIDs
 1.39 03-Oct-2001  enami branches: 1.39.2;
s/genfs_do_putpages/genfs_gop_write/ in uvmhist.
 1.38 21-Sep-2001  chs when zeroing pages past EOF, don't zero the page containing EOF if it
already contains valid data. should fix PRs 13361 and 13436.
 1.37 15-Sep-2001  chs a whole bunch of changes to improve performance and robustness under load:

- remove special treatment of pager_map mappings in pmaps. this is
required now, since I've removed the globals that expose the address range.
pager_map now uses pmap_kenter_pa() instead of pmap_enter(), so there's
no longer any need to special-case it.
- eliminate struct uvm_vnode by moving its fields into struct vnode.
- rewrite the pageout path. the pager is now responsible for handling the
high-level requests instead of only getting control after a bunch of work
has already been done on its behalf. this will allow us to UBCify LFS,
which needs tighter control over its pages than other filesystems do.
writing a page to disk no longer requires making it read-only, which
allows us to write wired pages without causing all kinds of havoc.
- use a new PG_PAGEOUT flag to indicate that a page should be freed
on behalf of the pagedaemon when it's unlocked. this flag is very similar
to PG_RELEASED, but unlike PG_RELEASED, PG_PAGEOUT can be cleared if the
pageout fails due to eg. an indirect-block buffer being locked.
this allows us to remove the "version" field from struct vm_page,
and together with shrinking "loan_count" from 32 bits to 16,
struct vm_page is now 4 bytes smaller.
- no longer use PG_RELEASED for swap-backed pages. if the page is busy
because it's being paged out, we can't release the swap slot to be
reallocated until that write is complete, but unlike with vnodes we
don't keep a count of in-progress writes so there's no good way to
know when the write is done. instead, when we need to free a busy
swap-backed page, just sleep until we can get it busy ourselves.
- implement a fast-path for extending writes which allows us to avoid
zeroing new pages. this substantially reduces cpu usage.
- encapsulate the data used by the genfs code in a struct genfs_node,
which must be the first element of the filesystem-specific vnode data
for filesystems which use genfs_{get,put}pages().
- eliminate many of the UVM pagerops, since they aren't needed anymore
now that the pager "put" operation is a higher-level operation.
- enhance the genfs code to allow NFS to use the genfs_{get,put}pages
instead of a modified copy.
- clean up struct vnode by removing all the fields that used to be used by
the vfs_cluster.c code (which we don't use anymore with UBC).
- remove kmem_object and mb_object since they were useless.
instead of allocating pages to these objects, we now just allocate
pages with no object. such pages are mapped in the kernel until they
are freed, so we can use the mapping to find the page to free it.
this allows us to remove splvm() protection in several places.

The sum of all these changes improves write throughput on my
decstation 5000/200 to within 1% of the rate of NetBSD 1.5
and reduces the elapsed time for "make release" of a NetBSD 1.5
source tree on my 128MB pc to 10% less than a 1.5 kernel took.
 1.36 17-Aug-2001  chs branches: 1.36.2;
make genfs get/put work for block devices as well:
- the "fs bshift" for block devices is always DEV_BSHIFT.
- retrieve the device vnode from VOP_BMAP() and use that to set b_dev
in page i/o buffers.
 1.35 14-Jun-2001  chs branches: 1.35.2;
be sure to allocate dirty zeroed pages to cover blocks we allocate
to resolve a write fault. fixes PR 13201.
also, be sure to allocate blocks for write faults to holes even if
the page is already in memory. fixes PR 13189.
 1.34 28-May-2001  chs add a genfs_mmap() and change all of the disk-based filesystems
to implement VOP_MMAP() with the genfs version, in preparation for
actually using this VOP.
 1.33 26-May-2001  chs replace vm_page_t with struct vm_page *.
 1.32 10-Mar-2001  chs eliminate the VM_PAGER_* error codes in favor of the traditional E* codes.
the mapping is:

VM_PAGER_OK 0
VM_PAGER_BAD <unused>
VM_PAGER_FAIL <unused>
VM_PAGER_PEND 0 (see below)
VM_PAGER_ERROR EIO
VM_PAGER_AGAIN EAGAIN
VM_PAGER_UNLOCK EBUSY
VM_PAGER_REFAULT ERESTART

for async i/o requests, it used to be possible for the request to
be convert to sync, and the pager would return VM_PAGER_OK or VM_PAGER_PEND
to indicate whether the caller should perform post-i/o cleanup.
this is no longer allowed; pagers must now return 0 to indicate that
the async i/o was successfully started, and the caller never needs to
worry about doing the post-i/o cleanup.
 1.31 28-Feb-2001  chs branches: 1.31.2;
in genfs_getpages(), don't try to optimize zeroing past EOF.
fixes PR 12297.
 1.30 27-Feb-2001  chs distinguish between a file's in-memory EOF (which marks the offset at
which we disallow creation of page cache pages) and its on-disk EOF
(which marks the offset at which there is not (yet) data on disk that
we need to read when creating pages). for requests with PGO_PASTEOF,
the in-memory EOF maybe be much larger than the on-disk EOF.
 1.29 18-Feb-2001  chs fix a couple more bugs:
- in genfs_getpages(), unbusy any pages that we don't free in the error path.
- in genfs_putpages(), if we get a bmap error, record that in the master buf.
 1.28 12-Feb-2001  fvdl Oops, removal unintenionally commited debug code.
 1.27 12-Feb-2001  fvdl Format arg nit.
 1.26 05-Feb-2001  chs fix several bugs:
- in the cases where we skip over the i/o loop, increment npages by ridx
so that when the cleanup code starts processing the pgs array at index 0
it'll actually process all of the pages.
- process the PG_RELEASED flag when unbusying pages.
- add some missing MP locking.
- use MIN() and MAX() instead of min() and max() since the latter are
functions which take arguments of type "int" but we call them with
values of type "off_t", so the values could be truncated.
- in the PGO_PASTEOF case, use the larger of the current file size and the
end of the requested range of pages as the file size for this request.
this fixes some problems with sparsing writes to large offsets.
 1.25 22-Jan-2001  fvdl Cast lbn to off_t in a few places, to avoid daddr_t overflow and all sorts
of havoc. From Bill Sommerfeld.
 1.24 27-Dec-2000  chs several bugs:
- in genfs_getpages() don't start read-ahead if we get an error on the
sync read, and always start read-ahead after the range of the sync read
if we do any at all.
- off-by-one error in genfs_size().
 1.23 09-Dec-2000  chs only zero the part of the page after EOF if we're actually
initializing the page.
 1.22 27-Nov-2000  chs allow building without SOFTDEP by adding the pageiodone hook to bio_ops.
 1.21 27-Nov-2000  chs Initial integration of the Unified Buffer Cache project.
 1.20 19-Sep-2000  fvdl Adapt for VOP_FSYNC parameter change.
 1.19 03-Aug-2000  thorpej Convert namei pathname buffer allocation to use the pool allocator.
 1.18 29-May-2000  mycroft branches: 1.18.2;
Stylistic change.
 1.17 13-May-2000  perseant branches: 1.17.2;
Change the sementics of the last parameter from a boolean ("waitfor") to
a set of flags ("flags"). Two flags are defined, UPDATE_WAIT and
UPDATE_DIROP.

Under the old semantics, VOP_UPDATE would block if waitfor were set,
under the assumption that directory operations should be done
synchronously. At least LFS and FFS+softdep do not make this
assumption; FFS+softdep got around the problem by enclosing all relevant
calls to VOP_UPDATE in a "if(!DOINGSOFTDEP(vp))", while LFS simply
ignored waitfor, one of the reasons why NFS-serving an LFS filesystem
did not work properly.

Under the new semantics, the UPDATE_DIROP flag is a hint to the
fs-specific update routine that the call comes from a dirop routine, and
should be wait for, or not, accordingly.

Closes PR#8996.
 1.16 30-Mar-2000  augustss Register, begone!
 1.15 15-Nov-1999  fvdl Add Kirk McKusick's soft updates code to the trunk. Not enabled by
default, as the copyright on the main file (ffs_softdep.c) is such
that is has been put into gnusrc. options SOFTDEP will pull this
in. This code also contains the trickle syncer.

Bump version number to 1.4O
 1.14 23-Oct-1999  fvdl Remove some mentioned members in the vop {un}lock args struct that we
do not actually have.
 1.13 03-Aug-1999  wrstuden branches: 1.13.2; 1.13.4; 1.13.6;
Add support for fcntl(2) to generate VOP_FCNTL calls. Any fcntl
call with F_FSCTL set and F_SETFL calls generate calls to a new
fileop fo_fcntl. Add genfs_fcntl() and soo_fcntl() which return 0
for F_SETFL and EOPNOTSUPP otherwise. Have all leaf filesystems
use genfs_fcntl().

Reviewed by: thorpej
Tested by: wrstuden
 1.12 08-Jul-1999  wrstuden Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.11 05-Mar-1999  mycroft branches: 1.11.4;
Pass null pointers to VOP_UPDATE rather than having all the callers fetch the
current time themselves.
 1.10 13-Aug-1998  kleink Add genfs_einval(), which does the obvious thing.
 1.9 10-Aug-1998  matthias create miscfs/genfs/genfs_vnops.c:genfs_enoioctl and make all the other
filesystems use it instead of a private version.
 1.8 25-Jun-1998  thorpej - Rename nqnfs_vop_lease_check() to genfs_lease_check(). If NFSSERVER is
not in the kernel, genfs_lease_check() is simply a no-op. This allows
LKM'd file systems to be exported (previously did not work properly
due to a compile-time decision based on -DNFSSERVER).
- defopt NFSSERVER
 1.7 05-Jun-1998  kleink * Convert fsync vnode operator implementations and usage from the old
waitfor argument and MNT_WAIT/MNT_NOWAIT to flags and FSYNC_WAIT.
* In genfs_fsync(), honor the FSYNC_NODATA flag.
 1.6 01-Mar-1998  fvdl Merge with Lite2 + local changes
 1.5 05-Jan-1998  perry RCSID Police.
 1.4 11-Apr-1997  kleink Implement a POSIX compliant genfs VOP_SEEK() and use it in the appropriate
places; by Chris G. Demetriou and myself.
 1.3 07-Sep-1996  mycroft Implement poll(2).
 1.2 05-Sep-1996  thorpej Remove some unused variables.
 1.1 01-Sep-1996  mycroft Add a set of generic file system operations that most file systems use.
Also, fix some time stamp bogosities.
 1.11.4.7 31-Aug-1999  perseant Rudimentary support for LFS under UBC:

- LFS-specific VOP_BALLOC and VOP_PUTPAGES vnode ops.

- getblk VREG panic #ifdef'd out (can be reinstated when Ifile is
internalized and Ifile can be made another type from VREG)

- interface to VOP_PUTPAGES changed to pass all pager flags, not
just sync. FS putpages routines must know about the pager flags.

- new LFS magic disk address, -2 ("unwritten"), meaning accounted for
but not assigned to a fixed disk location (since LFS does these two
things separately, and the previous accounting method using buffer
headers no longer will work). Changed references to (foo == (daddr_t)-1)
to (foo < 0). Since disk drivers reject all addresses < 0, this should
not present a problem for other FSs.
 1.11.4.6 09-Aug-1999  chs create a new type "voff_t" for uvm_object offsets
and define it to be "off_t". also, remove pgo_asyncget().
 1.11.4.5 02-Aug-1999  thorpej Update from trunk.
 1.11.4.4 31-Jul-1999  chs genfs_getpages() now handles:
- faults on offsets past the nominal EOF during extending writes.
- returning multiple pages in the !PGO_LOCKED case if multiple pages
are requested.
- using new VOP_BALLOC() interface to for allocating getpages with
blocksize<pagesize.
genfs_putpages() now handles:
- writing pages which do not have full backing store allocated.
 1.11.4.3 12-Jul-1999  chs fix the PGO_OVERWRITE case, I don't know how it was working before.
tidy a few other bits.
 1.11.4.2 11-Jul-1999  chs yet another major rework of the generic getpages.
we now do the block allocations for allocating getpages operations
after reading the pages. for nested i/os, use b_resid rather than
b_bcount to track the amount left to go. return values for
getpages/putpages are now unix errnos rather than VM_PAGER_*.
readahead is gone again for the moment.
 1.11.4.1 04-Jul-1999  chs create genfs_getpages() and genfs_putpages().
these should be able to handle most of the local-disk filesystems.
 1.13.6.1 27-Dec-1999  wrstuden Pull up to last week's -current.
 1.13.4.2 15-Nov-1999  fvdl Sync with -current
 1.13.4.1 19-Oct-1999  fvdl Bring in Kirk McKusick's FFS softdep code on a branch.
 1.13.2.6 12-Mar-2001  bouyer Sync with HEAD.
 1.13.2.5 11-Feb-2001  bouyer Sync with HEAD.
 1.13.2.4 05-Jan-2001  bouyer Sync with HEAD
 1.13.2.3 13-Dec-2000  bouyer Sync with HEAD (for UBC fixes).
 1.13.2.2 08-Dec-2000  bouyer Sync with HEAD.
 1.13.2.1 20-Nov-2000  bouyer Update thorpej_scsipi to -current as of a month ago
 1.17.2.1 22-Jun-2000  minoura Sync w/ netbsd-1-5-base.
 1.18.2.1 14-Dec-2000  he Pull up revision 1.20 (requested by fvdl):
Improve NFS performance, possibly with as much as 100% in
throughput. Please note: this implies a kernel interface change,
VOP_FSYNC gains two arguments.
 1.31.2.22 07-Jan-2003  thorpej In the SA universe, the switch-to-this-LWP decision is made at a
different level than where preempt() calls are made, which renders
the "newlwp" argument useless. Replace it with a "more work to do"
boolean argument. Returning to userspace preempt() calls pass 0.
"Voluntary" preemptions in e.g. uiomove() pass 1. This will be used
to indicate to the SA subsystem that the LWP is not yet finished in
the kernel.

Collapse the SA vs. non-SA cases of preempt() together, making the
conditional code block much smaller, and don't call sa_preempt() if
more work is to come.

NOTE: THIS IS NOT A COMPLETE FIX TO THE preempt()-in-uiomove() PROBLEM
THAT CURRENTLY EXISTS FOR SA PROCESSES.
 1.31.2.21 11-Dec-2002  thorpej Sync with HEAD.
 1.31.2.20 11-Nov-2002  nathanw Catch up to -current
 1.31.2.19 23-Oct-2002  thorpej Fix a merge botch.
 1.31.2.18 23-Oct-2002  thorpej Sync with rev. 1.65.
 1.31.2.17 16-Jul-2002  nathanw pagedaemon_proc really should be a proc, not a LWP.
 1.31.2.16 12-Jul-2002  nathanw No longer need to pull in lwp.h; proc.h pulls it in for us.
 1.31.2.15 24-Jun-2002  nathanw Curproc->curlwp renaming.

Change uses of "curproc->l_proc" back to "curproc", which is more like the
original use. Bare uses of "curproc" are now "curlwp".

"curproc" is now #defined in proc.h as ((curlwp) ? (curlwp)->l_proc) : NULL)
so that it is always safe to reference curproc (*de*referencing curproc
is another story, but that's always been true).
 1.31.2.14 20-Jun-2002  nathanw Catch up to -current.
 1.31.2.13 17-Apr-2002  nathanw Catch up to -current.
 1.31.2.12 01-Apr-2002  nathanw Catch up to -current.
(CVS: It's not just a program. It's an adventure!)
 1.31.2.11 28-Feb-2002  nathanw LWPify.
 1.31.2.10 28-Feb-2002  nathanw Catch up to -current.
 1.31.2.9 09-Jan-2002  nathanw curproc ==> curproc->l_proc
 1.31.2.8 08-Jan-2002  nathanw Catch up to -current.
 1.31.2.7 14-Nov-2001  nathanw Catch up to -current.
 1.31.2.6 08-Oct-2001  nathanw Catch up to -current.
 1.31.2.5 21-Sep-2001  nathanw Catch up to -current.
 1.31.2.4 24-Aug-2001  nathanw Catch up with -current.
 1.31.2.3 21-Jun-2001  nathanw Catch up to -current.
 1.31.2.2 09-Apr-2001  nathanw Catch up with -current.
 1.31.2.1 05-Mar-2001  nathanw Initial commit of scheduler activations and lightweight process support.
 1.35.2.8 02-Oct-2002  jdolecek knote data is now 64bit, g/c obsolete comment
 1.35.2.7 29-Sep-2002  jdolecek don't need cast to (caddr_t) for kn_hook anymore
 1.35.2.6 25-Sep-2002  jdolecek implement genfs_kqfilter() - this is based upon ufs_kqfilter(), but uses
vp->v_size for EVFILT_READ
 1.35.2.5 23-Jun-2002  jdolecek catch up with -current on kqueue branch
 1.35.2.4 16-Mar-2002  jdolecek Catch up with -current.
 1.35.2.3 11-Feb-2002  jdolecek Sync w/ -current.
 1.35.2.2 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.35.2.1 25-Aug-2001  thorpej Merge Aug 24 -current into the kqueue branch.
 1.36.2.5 11-Oct-2001  fvdl Catch up with -current. Fix some bogons in the sparc64 kbd/ms
attach code. cd18xx conversion provided by mrg.
 1.36.2.4 01-Oct-2001  fvdl Catch up with -current.
 1.36.2.3 27-Sep-2001  fvdl Put back line that got misplaced somehow.
 1.36.2.2 26-Sep-2001  fvdl * add a VCLONED vnode flag that indicates a vnode representing a cloned
device.
* rename REVOKEALL to REVOKEALIAS, and add a REVOKECLONE flag, to pass
to VOP_REVOKE
* the revoke system call will revoke all aliases, as before, but not the
clones
* vdevgone is called when detaching a device, so make it use REVOKECLONE
to get rid of all clones as well
* clean up all uses of VOP_OPEN wrt. locking.
* add a few VOPS to spec_vnops that need to do something when it's a
clone vnode (access and getattr)
* add a copy of the vnode vattr structure of the original 'master' vnode
to the specinfo of a cloned vnode. could possibly redirect getattr to
the 'master' vnode, but this has issues with revoke
* add a vdev_reassignvp function that disassociates a vnode from its
original device, and reassociates it with the specified dev_t. to be
used by cloning devices only, in case a new minor is allocated.
* change all direct references in drivers to v_devcookie and v_rdev
to vdev_privdata(vp) and vdev_rdev(vp). for diagnostic purposes
when debugging race conditions that still exist wrt. locking and
revoking vnodes.
* make the locking state of a vnode consistent when passed to
d_open and d_close (unlocked). locked would be better, but has
some deadlock issues
 1.36.2.1 07-Sep-2001  thorpej Commit my "devvp" changes to the thorpej-devvp branch. This
replaces the use of dev_t in most places with a struct vnode *.

This will form the basic infrastructure for real cloning device
support (besides being architecurally cleaner -- it'll be good
to get away from using numbers to represent objects).
 1.39.2.1 12-Nov-2001  thorpej Sync the thorpej-mips-cache branch with -current.
 1.62.2.1 30-May-2002  gehenna Catch up with -current.
 1.63.2.3 26-Aug-2003  tron Pull up revision 1.76 (requested by tls in ticket #1434):
Correct use of MAXBSIZE where MAXPHYS was intended. This is a necessary
first step towards per-device MAXPHYS, and has the beneficial side effect
of allowing clustering to MAXPHYS even on systems that need to run with
a reduced MAXBSIZE to get more metadata buffers.
 1.63.2.2 23-Oct-2002  lukem Pull up revision 1.65 (requested by fvdl in ticket #935):
Use B_ASYNC in the !PGO_SYNCIO case. Gets back most, if not all, NFS
read throughput performance lost since the introduction of UBC. Spotted
by YAMAMOTO Takashi, many thanks to him.
 1.63.2.1 01-Jun-2002  tv Pull up revision 1.64 (requested by enami in ticket #114):
Add missing pageq lock while uvm_pagefree() is called (either directly
or indirectly). Reviewed by chuq.
 1.80.2.11 11-Dec-2005  christos Sync with head.
 1.80.2.10 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.80.2.9 04-Mar-2005  skrll Sync with HEAD.

Hi Perry!
 1.80.2.8 17-Feb-2005  skrll Sync with HEAD.
 1.80.2.7 04-Feb-2005  skrll Sync with HEAD.
 1.80.2.6 17-Jan-2005  skrll Sync with HEAD.
 1.80.2.5 19-Oct-2004  skrll Sync with HEAD
 1.80.2.4 21-Sep-2004  skrll Fix the sync with head I botched.
 1.80.2.3 18-Sep-2004  skrll Sync with HEAD.
 1.80.2.2 03-Aug-2004  skrll Sync with HEAD
 1.80.2.1 02-Jul-2003  darrenr Apply the aborted ktrace-lwp changes to a specific branch. This is just for
others to review, I'm concerned that patch fuziness may have resulted in some
errant code being generated but I'll look at that later by comparing the diff
from the base to the branch with the file I attempt to apply to it. This will,
at the very least, put the changes in a better context for others to review
them and attempt to tinker with removing passing of 'struct lwp' through
the kernel.
 1.92.2.1 29-Apr-2005  kent sync with -current
 1.93.2.3 19-Mar-2005  yamt sync with head. xen and whitespace. xen part is not finished.
 1.93.2.2 12-Feb-2005  yamt sync with head.
 1.93.2.1 25-Jan-2005  yamt file genfs_vnops.c was added on branch yamt-km on 2005-02-12 18:17:53 +0000
 1.96.2.1 24-Aug-2005  riz Pull up following revision(s) (requested by yamt in ticket #688):
sys/miscfs/genfs/genfs_vnops.c: revision 1.98 via patch
sys/ufs/ffs/ffs_vfsops.c: revision 1.165
sys/ufs/lfs/lfs_extern.h: revision 1.69
sys/fs/filecorefs/filecore_vfsops.c: revision 1.20
sys/nfs/nfs_node.c: revision 1.80
sys/fs/smbfs/smbfs_node.c: revision 1.24
sys/fs/cd9660/cd9660_vfsops.c: revision 1.24
sys/fs/msdosfs/msdosfs_denode.c: revision 1.8
sys/miscfs/genfs/genfs_node.h: revision 1.6
sys/ufs/lfs/lfs_vfsops.c: revision 1.183
sys/ufs/ext2fs/ext2fs_vfsops.c: revision 1.86
sys/fs/adosfs/advfsops.c: revision 1.23
sys/fs/ntfs/ntfs_vfsops.c: revision 1.31
- constify genfs_ops.
- use member designators.

sys/miscfs/genfs/genfs_vnops.c: revision 1.99 via patch
genfs_getpages: don't forget to put the vnode onto the syncer's work que
ue
even in the case of PGO_LOCKED.

sys/uvm/uvm_bio.c: revision 1.40
sys/uvm/uvm_pager.h: revision 1.29
sys/miscfs/genfs/genfs_vnops.c: revision 1.100 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.50
- introduce PGO_NOBLOCKALLOC and use it for ubc mapping
to prevent unnecessary block allocations in the case that
page size > block size.
- ufs_balloc_range: use VM_PROT_WRITE+PGO_NOBLOCKALLOC rather than
VM_PROT_READ.

sys/uvm/uvm_fault.c: revision 1.96
sys/miscfs/genfs/genfs_vnops.c: revision 1.101 via patch
sys/uvm/uvm_object.h: revision 1.19
sys/miscfs/genfs/genfs_node.h: revision 1.7
ensure that vnodes with dirty pages are always on syncer's queue.
- genfs_putpages: wait for i/o completion of PG_RELEASED/PG_PAGEOUT pages by
setting "wasclean" false when encountering them.
suggested by Stephan Uphoff in PR/24596 (1).
- genfs_putpages: write protect pages when cleaning out, if
we're going to take the vnode off the syncer's queue.
uvm_fault: don't write-map pages unless its vnode is already on
the syncer's queue.
fix PR/24596 (3) but in the different way from the suggested fix.
(to keep our current behaviour, ie. not to require explicit msync.
discussed on tech-kern@.)
- genfs_putpages: don't mistakenly take a vnode off the queue
by introducing a generation number in genfs_node.
genfs_getpages: increment the generation number.
suggested by Stephan Uphoff in PR/24596 (2).
- add some assertions.

sys/miscfs/genfs/genfs_vnops.c: revision 1.102 via patch
genfs_putpages: don't bother to clean the vnode unless VONWORKLST.

sys/ufs/ffs/ffs_vnops.c: revision 1.71
ffs_full_fsync: because VBLK/VCHR can be mmap'ed,
do VOP_PUTPAGES for them as well.

sys/uvm/uvm_fault.c: revision 1.97
uvm_fault: check a correct object in the case of layered filesystems.
fix PR/30811 from Jukka Salmi.

sys/uvm/uvm_object.h: revision 1.20
sys/ufs/ffs/ffs_vfsops.c: revision 1.167
sys/uvm/uvm_bio.c: revision 1.41
sys/ufs/ufs/ufs_vnops.c: revision 1.129
sys/uvm/uvm_mmap.c: revision 1.92
sys/uvm/uvm_fault.c: revision 1.98
sys/kern/vfs_subr.c: revision 1.252
sys/fs/msdosfs/denode.h: revision 1.5
sys/miscfs/genfs/genfs_vnops.c: revision 1.103 via patch
sys/fs/msdosfs/msdosfs_denode.c: revision 1.9
sys/sys/vnode.h: revision 1.141
sys/ufs/ufs/ufs_inode.c: revision 1.51
sys/ufs/ufs/ufs_extern.h: revision 1.45 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.8
sys/ufs/lfs/lfs_vfsops.c: revision 1.184
sys/uvm/uvm_pager.h: revision 1.30
sys/ufs/ext2fs/ext2fs_vfsops.c: revision 1.87
update file timestamps for nfsd loaned-read and mmap.
PR/25279. discussed on tech-kern@.

sys/miscfs/genfs/genfs_vnops.c: revision 1.104 via patch
don't write-protect wired pages. pointed by Chuck Silvers.
for now, leave a vnode on the syncer's queue, as suggested by him.

sys/ufs/ffs/ffs_vnops.c: revision 1.72
revert VCHR part of ffs_vnops.c 1.71.
as VCHR uses the device pager, no point to call VOP_PUTPAGES here.
pointed by Chuck Silvers.
 1.98.2.10 24-Mar-2008  yamt sync with head.
 1.98.2.9 11-Feb-2008  yamt sync with head.
 1.98.2.8 04-Feb-2008  yamt sync with head.
 1.98.2.7 21-Jan-2008  yamt sync with head
 1.98.2.6 07-Dec-2007  yamt sync with head
 1.98.2.5 27-Oct-2007  yamt sync with head.
 1.98.2.4 03-Sep-2007  yamt sync with head.
 1.98.2.3 26-Feb-2007  yamt sync with head.
 1.98.2.2 30-Dec-2006  yamt sync with head.
 1.98.2.1 21-Jun-2006  yamt sync with head.
 1.107.2.1 20-Oct-2005  yamt remove genfs_fsync.
 1.109.2.4 19-Nov-2005  yamt remove contextless read-ahead code.
 1.109.2.3 18-Nov-2005  yamt - associate read-ahead context to vnode, rather than file.
- revert VOP_READ prototype.
 1.109.2.2 15-Nov-2005  yamt adapt ffs, lfs, nfs.
 1.109.2.1 14-Nov-2005  yamt disable genfs readahead.
 1.118.2.3 01-Feb-2006  yamt sync with head.
 1.118.2.2 15-Jan-2006  yamt sync with head.
 1.118.2.1 31-Dec-2005  yamt adapt some random parts of kernel to uio_vmspace.
 1.121.4.2 01-Jun-2006  kardel Sync with head.
 1.121.4.1 22-Apr-2006  simonb Sync with head.
 1.121.2.1 09-Sep-2006  rpaulo sync with head
 1.122.6.2 24-May-2006  tron Merge 2006-05-24 NetBSD-current into the "peter-altq" branch.
 1.122.6.1 31-Mar-2006  tron Merge 2006-03-31 NetBSD-current into the "peter-altq" branch.
 1.122.4.3 06-May-2006  christos - Move kauth_cred_t declaration to <sys/types.h>
- Cleanup struct ucred; forward declarations that are unused.
- Don't include <sys/kauth.h> in any header, but include it in the c files
that need it.

Approved by core.
 1.122.4.2 19-Apr-2006  elad sync with head.
 1.122.4.1 08-Mar-2006  elad Adapt to kernel authorization KPI.
 1.122.2.5 11-Aug-2006  yamt sync with head
 1.122.2.4 24-May-2006  yamt sync with head.
 1.122.2.3 11-Apr-2006  yamt sync with head
 1.122.2.2 01-Apr-2006  yamt sync with head.
 1.122.2.1 05-Mar-2006  yamt separate page replacement policy from the rest of kernel.
 1.128.4.4 01-Feb-2007  ad Sync with head.
 1.128.4.3 30-Jan-2007  ad Remove support for SA. Ok core@.
 1.128.4.2 12-Jan-2007  ad Sync with head.
 1.128.4.1 18-Nov-2006  ad Sync with head.
 1.129.2.3 18-Dec-2006  yamt sync with head.
 1.129.2.2 10-Dec-2006  yamt sync with head.
 1.129.2.1 22-Oct-2006  yamt sync with head
 1.140.4.1 03-Sep-2007  wrstuden Sync w/ NetBSD-4-RC_1
 1.140.2.1 05-Jun-2007  bouyer Pull up following revision(s) (requested by perseant in ticket #703):
sys/miscfs/genfs/genfs.h 1.21
sys/miscfs/genfs/genfs_vnops.c 1.151
sys/ufs/lfs/lfs.h 1.119, 1.120
sys/ufs/lfs/lfs_bio.c 1.99-101
sys/ufs/lfs/lfs_extern.h 1.89
sys/ufs/lfs/lfs_inode.c 1.108, 1.109
sys/ufs/lfs/lfs_segment.c 1.197, 1.199, 1.200
sys/ufs/lfs/lfs_subr.c 1.69, 1.70
sys/ufs/lfs/lfs_syscalls.c 1.119
sys/ufs/lfs/lfs_vfsops.c 1.234, 1.235
sys/ufs/lfs/lfs_vnops.c 1.195, 1.196, 1.200, 1.202-206

Reduce busy waiting in lfs_putpages(), and other LFS improvements.
 1.146.2.4 17-May-2007  yamt sync with head.
 1.146.2.3 07-May-2007  yamt sync with head.
 1.146.2.2 12-Mar-2007  rmind Sync with HEAD.
 1.146.2.1 27-Feb-2007  yamt - sync with head.
- move sched_changepri back to kern_synch.c as it doesn't know PPQ anymore.
 1.150.4.1 11-Jul-2007  mjf Sync with head.
 1.150.2.15 23-Oct-2007  ad Sync with head.
 1.150.2.14 16-Sep-2007  ad Checkpoint work in progress on the vnode lifecycle and reference counting
stuff. This makes it work properly without kernel_lock and fixes a few
quite old bugs. See vfs_subr.c 1.283.2.17 for details.
 1.150.2.13 01-Sep-2007  yamt fix a race and add a comment about it.
 1.150.2.12 24-Aug-2007  ad Sync with buffer cache locking changes. See buf.h/vfs_bio.c for details.
Some minor portions are incomplete and needs to be verified as a whole.
 1.150.2.11 21-Aug-2007  yamt fix some races around pagedaemon and uvm_wait. ok'ed by Andrew Doran.
 1.150.2.10 19-Aug-2007  ad - Back out the biodone() changes.
- Eliminate B_ERROR (from HEAD).
 1.150.2.9 23-Jun-2007  ad - Lock v_cleanblkhd, v_dirtyblkhd, v_numoutput with the vnode's interlock.
Get rid of global_v_numoutput_lock. Partially incomplete as the buffer
cache locking doesn't work very well and needs an overhaul.
- Some changes to try and make softdep MP safe. Untested.
 1.150.2.8 17-Jun-2007  ad - Increase the number of thread priorities from 128 to 256. How the space
is set up is to be revisited.
- Implement soft interrupts as kernel threads. A generic implementation
is provided, with hooks for fast-path MD code that can run the interrupt
threads over the top of other threads executing in the kernel.
- Split vnode::v_flag into three fields, depending on how the flag is
locked (by the interlock, by the vnode lock, by the file system).
- Miscellaneous locking fixes and improvements.
 1.150.2.7 09-Jun-2007  ad Sync with head.
 1.150.2.6 08-Jun-2007  ad Sync with head.
 1.150.2.5 13-Apr-2007  ad - Fix a (new) bug where vget tries to acquire freed vnodes' interlocks.
- Minor locking fixes.
 1.150.2.4 09-Apr-2007  ad - Add two new arguments to kthread_create1: pri_t pri, bool mpsafe.
- Fork kthreads off proc0 as new LWPs, not new processes.
 1.150.2.3 05-Apr-2007  ad Compile fixes.
 1.150.2.2 21-Mar-2007  ad - Replace more simple_locks, and fix up in a few places.
- Use condition variables.
- LOCK_ASSERT -> KASSERT.
 1.150.2.1 13-Mar-2007  ad Pull in the initial set of changes for the vmlocking branch.
 1.155.2.1 15-Aug-2007  skrll Sync with HEAD.
 1.156.10.2 29-Jul-2007  ad It's not a good idea for device drivers to modify b_flags, as they don't
need to understand the locking around that field. Instead of setting
B_ERROR, set b_error instead. b_error is 'owned' by whoever completes
the I/O request.
 1.156.10.1 29-Jul-2007  ad file genfs_vnops.c was added on branch matt-mips64 on 2007-07-29 12:15:47 +0000
 1.156.8.2 18-Oct-2007  yamt sync with head.
 1.156.8.1 14-Oct-2007  yamt sync with head.
 1.156.6.3 23-Mar-2008  matt sync with HEAD
 1.156.6.2 09-Jan-2008  matt sync with HEAD
 1.156.6.1 06-Nov-2007  matt sync with HEAD
 1.156.4.2 09-Dec-2007  jmcneill Sync with HEAD.
 1.156.4.1 26-Oct-2007  joerg Sync with HEAD.

Follow the merge of pmap.c on i386 and amd64 and move
pmap_init_tmp_pgtbl into arch/x86/x86/pmap.c. Modify the ACPI wakeup
code to restore CR4 before jumping back into kernel space as the large
page option might cover that.
 1.158.6.2 08-Dec-2007  ad Sync with head.
 1.158.6.1 04-Dec-2007  ad Pull the vmlocking changes into a new branch.
 1.158.4.2 18-Feb-2008  mjf Sync with HEAD.
 1.158.4.1 08-Dec-2007  mjf Sync with HEAD.
 1.159.4.2 19-Jan-2008  bouyer Sync with HEAD
 1.159.4.1 02-Jan-2008  bouyer Sync with HEAD
 1.164.6.2 02-Jun-2008  mjf Sync with HEAD.
 1.164.6.1 03-Apr-2008  mjf Sync with HEAD.
 1.165.2.1 18-May-2008  yamt sync with head.
 1.166.2.7 09-Oct-2010  yamt sync with head
 1.166.2.6 11-Aug-2010  yamt sync with head.
 1.166.2.5 11-Mar-2010  yamt sync with head
 1.166.2.4 18-Jul-2009  yamt sync with head.
 1.166.2.3 16-May-2009  yamt sync with head
 1.166.2.2 04-May-2009  yamt sync with head.
 1.166.2.1 16-May-2008  yamt sync with head.
 1.167.18.1 20-May-2011  matt bring matt-nb5-mips64 up to date with netbsd-5-1-RELEASE (except compat).
 1.167.16.1 07-Sep-2010  bouyer Pull up following revision(s) (requested by chs in ticket #1448):
sys/uvm/uvm_pager.h: revision 1.39 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.183 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.83 via patch
sys/miscfs/genfs/genfs_io.c: revision 1.40 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.20 via patch
replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.167.14.2 23-Jul-2009  jym Sync with HEAD.
 1.167.14.1 13-May-2009  jym Sync with HEAD.

Commit is split, to avoid a "too many arguments" protocol error.
 1.167.10.1 07-Sep-2010  bouyer Pull up following revision(s) (requested by chs in ticket #1448):
sys/uvm/uvm_pager.h: revision 1.39 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.183 via patch
sys/ufs/ufs/ufs_inode.c: revision 1.83 via patch
sys/miscfs/genfs/genfs_io.c: revision 1.40 via patch
sys/miscfs/genfs/genfs_node.h: revision 1.20 via patch
replace the earlier workaround for PR 40389 with a better fix.
the earlier change caused data corruption by freeing pages
without invaliding their mappings. instead of the trylock/retry,
just take the genfs-node lock before calling VOP_GETPAGES()
and pass a new flag to tell it that we're already holding this lock.
 1.167.8.1 28-Apr-2009  skrll Sync with HEAD.
 1.176.4.4 05-Mar-2011  rmind sync with head
 1.176.4.3 03-Jul-2010  rmind sync with head
 1.176.4.2 30-May-2010  rmind sync with head
 1.176.4.1 16-Mar-2010  rmind Change struct uvm_object::vmobjlock to be dynamically allocated with
mutex_obj_alloc(). It allows us to share the locks among UVM objects.
 1.176.2.3 22-Oct-2010  uebayasi Sync with HEAD (-D20101022).
 1.176.2.2 17-Aug-2010  uebayasi Sync with HEAD.
 1.176.2.1 30-Apr-2010  uebayasi Sync with HEAD.
 1.186.6.1 23-Jun-2011  cherry Catchup with rmind-uvmplock merge.
 1.187.6.1 05-Apr-2012  mrg sync to latest -current.
 1.187.2.2 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.187.2.1 17-Apr-2012  yamt sync with head
 1.189.4.1 18-May-2014  rmind sync with head
 1.189.2.2 03-Dec-2017  jdolecek update from HEAD
 1.189.2.1 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.192.14.1 08-Jul-2017  snj Pull up following revision(s) (requested by christos in ticket #1442):
sys/kern/kern_event.c: revision 1.92 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.198 via patch
sys/sys/event.h: revision 1.30 via patch
Provide EVFILT_WRITE; this is what FreeBSD does and go wants it.
Makes go unit tests pass.
--
fix file descriptor locking (from joerg).
fixes kernel crashes by running go
 1.192.10.2 26-Apr-2017  pgoyette Sync with HEAD
 1.192.10.1 20-Mar-2017  pgoyette Sync with HEAD
 1.192.8.1 08-Jul-2017  snj Pull up following revision(s) (requested by christos in ticket #1442):
sys/kern/kern_event.c: revision 1.92 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.198 via patch
sys/sys/event.h: revision 1.30 via patch
Provide EVFILT_WRITE; this is what FreeBSD does and go wants it.
Makes go unit tests pass.
--
fix file descriptor locking (from joerg).
fixes kernel crashes by running go
 1.192.6.2 28-Aug-2017  skrll Sync with HEAD
 1.192.6.1 05-Feb-2017  skrll Sync with HEAD
 1.192.4.1 08-Jul-2017  snj Pull up following revision(s) (requested by christos in ticket #1442):
sys/kern/kern_event.c: revision 1.92 via patch
sys/miscfs/genfs/genfs_vnops.c: revision 1.198 via patch
sys/sys/event.h: revision 1.30 via patch
Provide EVFILT_WRITE; this is what FreeBSD does and go wants it.
Makes go unit tests pass.
--
fix file descriptor locking (from joerg).
fixes kernel crashes by running go
 1.193.2.1 21-Apr-2017  bouyer Sync with HEAD
 1.195.4.2 05-Jul-2017  snj Pull up following revision(s) (requested by christos in ticket #91):
sys/kern/kern_event.c: revision 1.92
sys/miscfs/genfs/genfs_vnops.c: revision 1.198
sys/sys/event.h: revision 1.30
Provide EVFILT_WRITE; this is what FreeBSD does and go wants it.
Makes go unit tests pass.
--
fix file descriptor locking (from joerg).
fixes kernel crashes by running go
 1.195.4.1 04-Jun-2017  bouyer pullup the following revisions, requested by hannken in ticket #2:
src/share/man/man9/fstrans.9 1.25
src/sys/kern/vfs_mount.c 1.66
src/sys/kern/vfs_subr.c 1.468
src/sys/kern/vfs_trans.c 1.46
src/sys/kern/vfs_vnode.c 1.94, 1.95, 1.96
src/sys/kern/vnode_if.c 1.105, 1.106
src/sys/kern/vnode_if.sh 1.65, 1.66
src/sys/kern/vnode_if.src 1.76
src/sys/miscfs/genfs/genfs_io.c 1.69
src/sys/miscfs/genfs/genfs_vnops.c 1.196, 1.197
src/sys/miscfs/genfs/layer_extern.h 1.40
src/sys/miscfs/genfs/layer_vfsops.c 1.51
src/sys/miscfs/genfs/layer_vnops.c 1.67
src/sys/miscfs/nullfs/null_vnops.c 1.42
src/sys/miscfs/overlay/overlay_vnops.c 1.24
src/sys/miscfs/umapfs/umap_vnops.c 1.60
src/sys/rump/include/rump/rumpvnode_if.h 1.29, 1.30
src/sys/rump/librump/rumpkern/emul.c 1.182
src/sys/rump/librump/rumpvfs/rumpvnode_if.c 1.29, 1.30
src/sys/sys/fstrans.h 1.11
src/sys/sys/vnode.h 1.278
src/sys/sys/vnode_if.h 1.100, 1.101
src/sys/sys/vnode_impl.h 1.14, 1.15
src/sys/ufs/lfs/lfs_pages.c 1.12

Vnode state, lock and fstrans cleanup:
- Rename vnode state "VS_ACTIVE" to "VS_LOADED" and add synthetic
state "VS_ACTIVE" to assert a loaded vnode with usecount > 0.

- Redo FSTRANS in vnode_if.c and use it for VOP_LOCK and VOP_UNLOCK.

- Cleanup the genfs lock operations.

- Make "struct vnode_impl" member "vi_lock" a krwlock_t again.

- Remove the lock type argument from fstrans_start and
fstrans_start_nowait,
remove now unused FSTRANS state "FSTRANS_SUSPENDING".
 1.199.4.1 08-Apr-2020  martin Merge changes from current as of 20200406
 1.200.2.4 29-Feb-2020  ad Sync with head.
 1.200.2.3 24-Jan-2020  ad vnodes:

- Have own v_usecount again, don't share the uvm_object's refcount.
- Cluster the members of vnode_t and vnode_impl_t in a cache-concious way.
- Go back to having vi_lock directly in vnode_impl_t.
- Go back to having v_usecount adjusted with atomics.
- Start adjusting v_holdcnt with atomics, too.
- Put all the namecache stuff back into vnode_impl_t.
 1.200.2.2 22-Jan-2020  ad Make sure LK_UPGRADE always comes with LK_NOWAIT; dropping the lock in here
is unclean and I wonder if it could screw over fstrans.
 1.200.2.1 18-Jan-2020  ad Allow VOP_LOCK(LK_NONE).
 1.210.6.1 01-Aug-2021  thorpej Sync with HEAD.
 1.219.4.1 05-Mar-2023  martin Pull up following revision(s) (requested by hannken in ticket #111):

sys/miscfs/genfs/genfs_vnops.c: revision 1.220

Fix genfs_can_chtimes() to also handle the condition:

If the time pointer is null, then write permission
on the file is also sufficient.

From FreeBSD.

Should fix PR kern/57246 "NFS group permissions regression"
 1.17 11-Apr-2017  hannken Field "layerm_vfs" of "struct layer_mount" got superseded by "mnt_lower".
Adapt consumers and remove the now unused field.

Ride 7.99.68
 1.16 28-May-2014  hannken branches: 1.16.4; 1.16.8; 1.16.12;
Change field "layerm_tag" to correct type "enum vtagtype".

CID 1216449: Mixing enum types
 1.15 25-May-2014  hannken Change layerfs from hashlist to vcache.
Make VI_LOCKSHARE public again.

Ride 6.99.43
 1.14 06-Jun-2010  hannken branches: 1.14.18; 1.14.32;
Change layered file systems to always pass the locking VOP's down to the
leaf file system. Remove now unused member v_vnlock from struct vnode.
Welcome to 5.99.30

Discussed on tech-kern.
 1.13 30-Jan-2008  ad branches: 1.13.10; 1.13.30; 1.13.32;
Replace struct lock on vnodes with a simpler lock object built on
krwlock_t. This is a step towards removing lockmgr and simplifying
vnode locking. Discussed on tech-kern.
 1.12 10-Oct-2007  ad branches: 1.12.4;
Merge from vmlocking:

- Split vnode::v_flag into three fields, depending on field locking.
- simple_lock -> kmutex in a few places.
- Fix some simple locking problems.
 1.11 11-Dec-2005  christos branches: 1.11.30; 1.11.44; 1.11.46; 1.11.48;
merge ktrace-lwp.
 1.10 25-Sep-2005  jmmv Follow compat naming tradition: rename compat_export_args to export_args30.
 1.9 23-Sep-2005  jmmv Apply the NFS exports list rototill patch:

- Remove all NFS related stuff from file system specific code.
- Drop the vfs_checkexp hook and generalize it in the new nfs_check_export
function, thus removing redundancy from all file systems.
- Move all NFS export-related stuff from kern/vfs_subr.c to the new
file sys/nfs/nfs_export.c. The former was becoming large and its code
is always compiled, regardless of the build options. Using the latter,
the code is only compiled in when NFSSERVER is enabled. While doing this,
also make some functions in nfs_subs.c conditional to NFSSERVER.
- Add a new command in nfssvc(2), called NFSSVC_SETEXPORTSLIST, that takes a
path and a set of export entries. At the moment it can only clear the
exports list or append entries, one by one, but it is done in a way that
allows setting the whole set of entries atomically in the future (see the
comment in mountd_set_exports_list or in doc/TODO).
- Change mountd(8) to use the nfssvc(2) system call instead of mount(2) so
that it becomes file system agnostic. In fact, all this whole thing was
done to remove a 'XXX' block from this utility!
- Change the mount*, newfs and fsck* userland utilities to not deal with NFS
exports initialization; done internally by the kernel when initializing
the NFS support for each file system.
- Implement an interface for VFS (called VFS hooks) so that several kernel
subsystems can run arbitrary code upon receipt of specific VFS events.
At the moment, this only provides support for unmount and is used to
destroy NFS exports lists from the file systems being unmounted, though it
has room for extension.

Thanks go to yamt@, chs@, thorpej@, wrstuden@ and others for their comments
and advice in the development of this patch.
 1.8 30-Aug-2005  xtraeme Remove __P()
 1.7 24-Jul-2005  erh Provide a sysctl (vfs.layerfs.debug) to control verbose output when
LAYERFS_DIAGNOSTIC is turned on.
 1.6 28-May-2004  wrstuden branches: 1.6.12;
Since VOP_UPCALL() has been a long time in coming, add this partial
fix for layered-file-removal. It will work for the case of accessing
and deleting a file through the layered file system. Accessing via
the layer and deleting on the underlying still won't work, nor will
accessing via complicated structures (like two umap layers over a
given file systems).

We still need VOP_UPCALL(), but this is better than things were before.

This patch has been discussed off & on for a while. This incarnation
was tested by hannken at netbsd dot org.
 1.5 07-Aug-2003  agc branches: 1.5.2;
Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.
 1.4 07-Jun-2001  wiz branches: 1.4.22;
Typos in comments (misc/13133 by Michael K. Sanders)
 1.3 30-Mar-2000  simonb branches: 1.3.6;
Delete redundant decl of layer_node_create(), it's in layer_extern.h.
 1.2 13-Mar-2000  soren Fix doubled 'the's in comments.
 1.1 08-Jul-1999  wrstuden branches: 1.1.2; 1.1.4;
Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.1.4.1 20-Nov-2000  bouyer Update thorpej_scsipi to -current as of a month ago
 1.1.2.2 02-Aug-1999  thorpej Update from trunk.
 1.1.2.1 08-Jul-1999  thorpej file layer.h was added on branch chs-ubc2 on 1999-08-02 22:27:34 +0000
 1.3.6.1 21-Jun-2001  nathanw Catch up to -current.
 1.4.22.4 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.4.22.3 21-Sep-2004  skrll Fix the sync with head I botched.
 1.4.22.2 18-Sep-2004  skrll Sync with HEAD.
 1.4.22.1 03-Aug-2004  skrll Sync with HEAD
 1.5.2.1 30-May-2004  tron Pull up revision 1.6 (requested by wrstuden in ticket #424):
Since VOP_UPCALL() has been a long time in coming, add this partial
fix for layered-file-removal. It will work for the case of accessing
and deleting a file through the layered file system. Accessing via
the layer and deleting on the underlying still won't work, nor will
accessing via complicated structures (like two umap layers over a
given file systems).
We still need VOP_UPCALL(), but this is better than things were before.
This patch has been discussed off & on for a while. This incarnation
was tested by hannken at netbsd dot org.
 1.6.12.3 04-Feb-2008  yamt sync with head.
 1.6.12.2 27-Oct-2007  yamt sync with head.
 1.6.12.1 21-Jun-2006  yamt sync with head.
 1.11.48.1 14-Oct-2007  yamt sync with head.
 1.11.46.2 23-Mar-2008  matt sync with HEAD
 1.11.46.1 06-Nov-2007  matt sync with HEAD
 1.11.44.1 26-Oct-2007  joerg Sync with HEAD.

Follow the merge of pmap.c on i386 and amd64 and move
pmap_init_tmp_pgtbl into arch/x86/x86/pmap.c. Modify the ACPI wakeup
code to restore CR4 before jumping back into kernel space as the large
page option might cover that.
 1.11.30.1 13-Mar-2007  ad Pull in the initial set of changes for the vmlocking branch.
 1.12.4.1 18-Feb-2008  mjf Sync with HEAD.
 1.13.32.1 03-Jul-2010  rmind sync with head
 1.13.30.1 17-Aug-2010  uebayasi Sync with HEAD.
 1.13.10.1 11-Aug-2010  yamt sync with head.
 1.14.32.1 10-Aug-2014  tls Rebase.
 1.14.18.2 03-Dec-2017  jdolecek update from HEAD
 1.14.18.1 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.16.12.1 21-Apr-2017  bouyer Sync with HEAD
 1.16.8.1 26-Apr-2017  pgoyette Sync with HEAD
 1.16.4.1 28-Aug-2017  skrll Sync with HEAD
 1.41 17-Jan-2020  ad VFS_VGET(), VFS_ROOT(), VFS_FHTOVP(): give them a "int lktype" argument, to
allow us to get shared locks (or no lock) on the returned vnode. Matches
FreeBSD.
 1.40 04-Jun-2017  hannken branches: 1.40.6; 1.40.12;
Locking a layer vnode using the regular bypass routine is no longer
racy. Undo the change from 2017-03-30 11:16:52, commitid eurqbzuGxGRlryLz
and make vi_lock a krwlock_t again.
 1.39 30-Mar-2017  hannken branches: 1.39.6;
Locking a layer vnode is racy as it may become reclaimed before
calling the operation on the lower vnode.

Replace vi_lock with a rw_obj and change layered file systems
to share the lock with the lower vnode.

Layered file systems now use genfs_lock()/_unlock/_islocked().

Welcome to 7.99.67
 1.38 17-Feb-2017  hannken Add generic genfs_suspendctl() and use it for all file systems.
Layered file systems need work.
 1.37 27-Jan-2017  hannken Handle v_writecount from layer_open(), layer_close() and layer_revoke()
so lower file system vnodes get marked as open for writing.
 1.36 25-May-2014  hannken branches: 1.36.4; 1.36.8; 1.36.12;
Change layerfs from hashlist to vcache.
Make VI_LOCKSHARE public again.

Ride 6.99.43
 1.35 27-Feb-2014  hannken branches: 1.35.2;
The current implementation of vn_lock() is racy. Modification of
the vnode operations vector for active vnodes is unsafe because it
is not known whether deadfs or the original file system will be
called.

- Pass down LK_RETRY to the lock operation (hint for deadfs only).

- Change deadfs lock operation to return ENOENT if LK_RETRY is unset.

- Change all other lock operations to check for dead vnode once
the vnode is locked and unlock and return ENOENT in this case.

With these changes in place vnode lock operations will never succeed
after vclean() has marked the vnode as VI_XLOCK and before vclean()
has changed the operations vector.

Adresses PR kern/37706 (Forced unmount of file systems is unsafe)

Discussed on tech-kern.

Welcome to 6.99.33
 1.34 01-Feb-2012  dholland branches: 1.34.6; 1.34.10;
Change the syscall API for quotas over to the new non-proplib one.

- struct vfs_quotactl_args -> struct quotactl_args
- add sys/stdint.h to sys/quotactl.h for clean userland build
- install sys/quotactl.h in /usr/include
- update set lists for same
- add new marshalling code in libquota
- add new unmarshalling code in vfs_syscalls.c
- discard proplib interpreter code in vfs_quotactl.c
- add dispatching code for the 14 quotactl ops in vfs_quotactl.c
- mark the proplib quotactl syscall obsolete
- add a new syscall number for the new quotactl syscall
- change the name of the syscall to __quotactl()
- remove the decl of the old quotactl from quota/quotaprop.h
- add a decl of the new quotactl to sys/quotactl.h
- update the libc build
- update ktruss
- remove proplib marshalling code from libquota
- update copy of syscall table in gdb ppc sources
- hack rumphijack to accomodate new quotactl name (as I recall,
pooka wanted such a name change to simplify something, but I
don't really see what/how)

This change appears to require a kernel version bump for rumpish
reasons.
 1.33 29-Jan-2012  dholland Remove the extra op argument to VFS_QUOTACTL() - the op is now stored
purely in the args structure.

This change requires a kernel version bump.
 1.32 29-Jan-2012  dholland Introduce struct vfs_quotactl_args. Use it.

This change uglifies vfs_quotactl some in order to make room for
moving operation-specific but FS-independent logic out of ufs_quota.c.

Note: this change requires a kernel version bump.
 1.31 29-Jan-2012  dholland Move the proplib-based quota command dispatching (that is, the code
that knows the magic string names for the allowed actions) out of
UFS-specific code and to fs-independent code.

This introduces QUOTACTL_* operation codes and changes the signature
of VFS_QUOTACTL() again for compile safety.

Note: this change requires a kernel version bump.
 1.30 29-Jan-2012  dholland Move the code for iterating over the multiple RPC calls in a quota
proplib XML packet to vfs_quotactl.c out of sys/ufs/ufs.

Add a dummy extra arg to VFS_QUOTACTL for compile safety.

Note: this change requires a kernel version bump.
 1.29 11-Jul-2011  hannken branches: 1.29.2; 1.29.6;
Change VOP_BWRITE() to take a vnode as its first argument like all other
VOPs do. Layered file systems no longer have to modify bp->b_vp and run
into trouble when an async VOP_BWRITE() uses the wrong vnode.

- change all occurences of VOP_BWRITE(bp) to VOP_BWRITE(bp->b_vp, bp).
- remove layer_bwrite().
- welcome to 5.99.55

Adresses PR kern/38762 panic: vwakeup: neg numoutput

No objections from tech-kern@.
 1.28 06-Mar-2011  bouyer merge the bouyer-quota2 branch. This adds a new on-disk format
to store disk quota usage and limits, integrated with ffs
metadata. Usage is checked by fsck_ffs (no more quotacheck)
and is covered by the WAPBL journal. Enabled with kernel
option QUOTA2 (added where QUOTA was enabled in kernel config files),
turned on with tunefs(8) on a per-filesystem
basis. mount_mfs(8) can also turn quotas on.

See http://mail-index.netbsd.org/tech-kern/2011/02/19/msg010025.html
for details.
 1.27 10-Jan-2011  hannken branches: 1.27.2; 1.27.4;
Add layer_revoke() that adjusts the lower vnode use count to be at least as
high as the upper vnode count before passing down the VOP_REVOKE().

This way vclean() check for active (vp->v_usecount > 1) vnodes gets it right.

Should fix PR kern/43456.
 1.26 02-Jul-2010  hannken LK_INTERLOCK is no longer a valid flag for VOP_LOCK(). This makes
layer_*lock*() obsolete. Remove them and handle lock operations
with the generic bypass function.

Ride 5.99.34.
 1.25 02-Jul-2010  rmind Slightly clean-up layerfs and nullfs: update the big description more to
the reality (remove duplicate one in nullfs, merge some differences from
it), KNF, improve and update some comments, add few KASSERT()s, remove
unused declarations, avoid double inclusion of headers, misc.

No functional changes.
 1.24 28-Jan-2008  dholland branches: 1.24.10; 1.24.30; 1.24.32;
Fix some race conditions in rename.
Introduce a per-FS rename lock and new vfsops to manipulate it.
Get this lock while renaming. Also add another relookup() in do_sys_rename,
which is a hack to kludge around some of the worst deficiencies of
ufs_rename.
reviewed-by: pooka (and an earlier rev by ad)
posted on tech-kern with no objections.
 1.23 26-Nov-2007  pooka Remove the "struct lwp *" argument from all VFS and VOP interfaces.
The general trend is to remove it from all kernel interfaces and
this is a start. In case the calling lwp is desired, curlwp should
be used.

quick consensus on tech-kern
 1.22 13-Jul-2006  martin branches: 1.22.28; 1.22.30; 1.22.36;
Fix alignement problems for fhandle_t, exposed by gcc4.1.

While touching all vptofh/fhtovp functions, get rid of VFS_MAXFIDSIZ,
version the getfh(2) syscall and explicitly pass the size available in
the filehandle from userland.

Discussed on tech-kern, with lots of help from yamt (thanks!).
 1.21 14-May-2006  elad branches: 1.21.4;
integrate kauth.
 1.20 11-Dec-2005  christos branches: 1.20.4; 1.20.6; 1.20.8; 1.20.10; 1.20.12;
merge ktrace-lwp.
 1.19 23-Sep-2005  jmmv Apply the NFS exports list rototill patch:

- Remove all NFS related stuff from file system specific code.
- Drop the vfs_checkexp hook and generalize it in the new nfs_check_export
function, thus removing redundancy from all file systems.
- Move all NFS export-related stuff from kern/vfs_subr.c to the new
file sys/nfs/nfs_export.c. The former was becoming large and its code
is always compiled, regardless of the build options. Using the latter,
the code is only compiled in when NFSSERVER is enabled. While doing this,
also make some functions in nfs_subs.c conditional to NFSSERVER.
- Add a new command in nfssvc(2), called NFSSVC_SETEXPORTSLIST, that takes a
path and a set of export entries. At the moment it can only clear the
exports list or append entries, one by one, but it is done in a way that
allows setting the whole set of entries atomically in the future (see the
comment in mountd_set_exports_list or in doc/TODO).
- Change mountd(8) to use the nfssvc(2) system call instead of mount(2) so
that it becomes file system agnostic. In fact, all this whole thing was
done to remove a 'XXX' block from this utility!
- Change the mount*, newfs and fsck* userland utilities to not deal with NFS
exports initialization; done internally by the kernel when initializing
the NFS support for each file system.
- Implement an interface for VFS (called VFS hooks) so that several kernel
subsystems can run arbitrary code upon receipt of specific VFS events.
At the moment, this only provides support for unmount and is used to
destroy NFS exports lists from the file systems being unmounted, though it
has room for extension.

Thanks go to yamt@, chs@, thorpej@, wrstuden@ and others for their comments
and advice in the development of this patch.
 1.18 30-Aug-2005  xtraeme Remove __P()
 1.17 30-Jun-2004  hannken branches: 1.17.12;
Do LAYERFS_REMOVED for vop_rmdir.

Reviewed by: Bill Studenmund <wrstuden@netbsd.org>
 1.16 07-Jun-2004  yamt do a LAYERFS_REMOVED hack for vop_rename as well.
 1.15 29-May-2004  wrstuden Add layerfs_snapshot() as a handler routine for VFS_SNAPSHOT() calls
through a layered file system.

Note: we don't actually support snapshots through a layered file system,
and this routine returns an error. However we: 1) have clearly documented
what needs fixing (which isn't trivial to fix) and 2) if we do fix
this, all layered file systems can take advantage of it at once.
 1.14 28-May-2004  wrstuden Since VOP_UPCALL() has been a long time in coming, add this partial
fix for layered-file-removal. It will work for the case of accessing
and deleting a file through the layered file system. Accessing via
the layer and deleting on the underlying still won't work, nor will
accessing via complicated structures (like two umap layers over a
given file systems).

We still need VOP_UPCALL(), but this is better than things were before.

This patch has been discussed off & on for a while. This incarnation
was tested by hannken at netbsd dot org.
 1.13 27-Apr-2004  jrf First pass for some caddr_t removal and changes to get rid of it where we
no longer use and/or need it

- removed casts from unionfs, deadfs and fdesc
(there are more to hunt down still)
- changed vfs_quotactl args argumet from caddr_t to void *
- changed vfs_quotactl structures/callers to reflect the api change

Compiled fine and ran for about a day. Approved/reviewed by
christos@netbsd.org and gimpy@netbsd.org.
 1.12 21-Apr-2004  christos Replace the statfs() family of system calls with statvfs().
Retain binary compatibility.
 1.11 25-Jan-2004  hannken branches: 1.11.2;
Make VOP_STRATEGY(bp) a real VOP as discussed on tech-kern.

VOP_STRATEGY(bp) is replaced by one of two new functions:

- VOP_STRATEGY(vp, bp) Call the strategy routine of vp for bp.
- DEV_STRATEGY(bp) Call the d_strategy routine of bp->b_dev for bp.

DEV_STRATEGY(bp) is used only for block-to-block device situations.
 1.10 04-Dec-2003  atatat Dynamic sysctl.

Gone are the old kern_sysctl(), cpu_sysctl(), hw_sysctl(),
vfs_sysctl(), etc, routines, along with sysctl_int() et al. Now all
nodes are registered with the tree, and nodes can be added (or
removed) easily, and I/O to and from the tree is handled generically.

Since the nodes are registered with the tree, the mapping from name to
number (and back again) can now be discovered, instead of having to be
hard coded. Adding new nodes to the tree is likewise much simpler --
the new infrastructure handles almost all the work for simple types,
and just about anything else can be done with a small helper function.

All existing nodes are where they were before (numerically speaking),
so all existing consumers of sysctl information should notice no
difference.

PS - I'm sorry, but there's a distinct lack of documentation at the
moment. I'm working on sysctl(3/8/9) right now, and I promise to
watch out for buses.
 1.9 07-Aug-2003  agc Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.
 1.8 29-Jun-2003  fvdl branches: 1.8.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.
 1.7 29-Jun-2003  thorpej Undo part of the ktrace/lwp changes. In particular:
* Remove the "lwp *" argument that was added to vget(). Turns out
that nothing actually used it!
* Remove the "lwp *" arguments that were added to VFS_ROOT(), VFS_VGET(),
and VFS_FHTOVP(); all they did was pass it to vget() (which, as noted
above, didn't use it).
* Remove all of the "lwp *" arguments to internal functions that were added
just to appease the above.
 1.6 28-Jun-2003  darrenr Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V
 1.5 06-Dec-2001  chs add VOP_GETPAGES and VOP_PUTPAGES methods for layered filesystems.
drop the interlock on the upper layer, acquire the interlock on the
lower layer.
 1.4 07-Jun-2001  wiz branches: 1.4.2;
Typos in comments (misc/13133 by Michael K. Sanders)
 1.3 16-Mar-2000  jdolecek branches: 1.3.6;
Add new VFS op routine - vfs_done and call it on filesystem detach
in vfs_detach(). vfs_done may free global filesystem's resources,
typically those allocated in respective filesystem's init function.
Needed so those filesystems which went in via LKM have a chance to
clean after themselves before unloading. This fixes random panics
when LKM for filesystem using pools was loaded and unloaded several
times.

For each leaf filesystem, add appropriate vfs_done routine.
 1.2 13-Mar-2000  soren Fix doubled 'the's in comments.
 1.1 08-Jul-1999  wrstuden branches: 1.1.2; 1.1.4;
Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.1.4.1 20-Nov-2000  bouyer Update thorpej_scsipi to -current as of a month ago
 1.1.2.2 02-Aug-1999  thorpej Update from trunk.
 1.1.2.1 08-Jul-1999  thorpej file layer_extern.h was added on branch chs-ubc2 on 1999-08-02 22:27:34 +0000
 1.3.6.2 08-Jan-2002  nathanw Catch up to -current.
 1.3.6.1 21-Jun-2001  nathanw Catch up to -current.
 1.4.2.1 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.8.2.6 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.8.2.5 21-Sep-2004  skrll Fix the sync with head I botched.
 1.8.2.4 18-Sep-2004  skrll Sync with HEAD.
 1.8.2.3 24-Aug-2004  skrll Undo part of the ktrace/lwp changes. In particular:
* Remove the "lwp *" argument that was added to vget(). Turns out
that nothing actually used it!
* Remove the "lwp *" arguments that were added to VFS_ROOT(), VFS_VGET(),
and VFS_FHTOVP(); all they did was pass it to vget() (which, as noted
above, didn't use it).
* Remove all of the "lwp *" arguments to internal functions that were added
just to appease the above.
 1.8.2.2 03-Aug-2004  skrll Sync with HEAD
 1.8.2.1 02-Jul-2003  darrenr Apply the aborted ktrace-lwp changes to a specific branch. This is just for
others to review, I'm concerned that patch fuziness may have resulted in some
errant code being generated but I'll look at that later by comparing the diff
from the base to the branch with the file I attempt to apply to it. This will,
at the very least, put the changes in a better context for others to review
them and attempt to tinker with removing passing of 'struct lwp' through
the kernel.
 1.11.2.3 02-Jul-2004  he Pull up revision 1.17 (requested by hannken in ticket #575):
Do LAYERFS_REMOVED for vop_rmdir.
 1.11.2.2 21-Jun-2004  tron Pull up revision 1.16 (requested by yamt in ticket #512):
do a LAYERFS_REMOVED hack for vop_rename as well.
 1.11.2.1 30-May-2004  tron Pull up revision 1.14 (requested by wrstuden in ticket #424):
Since VOP_UPCALL() has been a long time in coming, add this partial
fix for layered-file-removal. It will work for the case of accessing
and deleting a file through the layered file system. Accessing via
the layer and deleting on the underlying still won't work, nor will
accessing via complicated structures (like two umap layers over a
given file systems).
We still need VOP_UPCALL(), but this is better than things were before.
This patch has been discussed off & on for a while. This incarnation
was tested by hannken at netbsd dot org.
 1.17.12.4 04-Feb-2008  yamt sync with head.
 1.17.12.3 07-Dec-2007  yamt sync with head
 1.17.12.2 30-Dec-2006  yamt sync with head.
 1.17.12.1 21-Jun-2006  yamt sync with head.
 1.20.12.1 24-May-2006  tron Merge 2006-05-24 NetBSD-current into the "peter-altq" branch.
 1.20.10.2 20-Apr-2006  christos kauth_cred_t -> struct kauth_cred;
 1.20.10.1 08-Mar-2006  elad Adapt to kernel authorization KPI.
 1.20.8.2 11-Aug-2006  yamt sync with head
 1.20.8.1 24-May-2006  yamt sync with head.
 1.20.6.1 01-Jun-2006  kardel Sync with head.
 1.20.4.1 09-Sep-2006  rpaulo sync with head
 1.21.4.1 13-Jul-2006  gdamore Merge from HEAD.
 1.22.36.2 18-Feb-2008  mjf Sync with HEAD.
 1.22.36.1 08-Dec-2007  mjf Sync with HEAD.
 1.22.30.2 23-Mar-2008  matt sync with HEAD
 1.22.30.1 09-Jan-2008  matt sync with HEAD
 1.22.28.1 27-Nov-2007  joerg Sync with HEAD. amd64 Xen support needs testing.
 1.24.32.3 21-Apr-2011  rmind sync with head
 1.24.32.2 05-Mar-2011  rmind sync with head
 1.24.32.1 03-Jul-2010  rmind sync with head
 1.24.30.1 17-Aug-2010  uebayasi Sync with HEAD.
 1.24.10.1 11-Aug-2010  yamt sync with head.
 1.27.4.1 20-Jan-2011  bouyer Snapshot of work in progress on a modernised disk quota system:
- new quotactl syscall (versionned for backward compat), which takes
as parameter a path to a mount point, and a prop_dictionary
(in plistref format) describing commands and arguments.
For each command, status and data are returned as a prop_dictionary.
quota commands features will be added to take advantage of this,
exporting quota data or getting quota commands as plists.

- new on disk-format storage (all 64bit wide), integrated to metadata for
ffs (and playing nicely with wapbl).
Quotas are enabled on a ffs filesystem via superblock flags.
tunefs(8) can enable or disable quotas.
On a quota-enabled filesystem, fsck_ffs(8) will track per-uid/gid
block and inode usages, and will check and update quotas in Pass 6.
quota usage and limits are stored in unliked files (one for users,
one for groups)l fsck_ffs(8) will create the files if needed, or
free them if needed. This means that after enabling or disabling
quotas on a filesystem; a fsck_ffs(8) run is required.
quotacheck(8) is not needed any more, on a unclean shutdown
fsck or journal replay will take care of fixing quotas.
newfs(8) can create a ready-to-mount quota-enabled filesystem
(superblock flags are set and quota inodes are created).
Other new features or semantic changes:
- default quota datas, applied to users or groups which don't already
have a quota entry
- per-user/group grace time (instead of a filesystem global one)
- 0 really means "nothing allowed at all", not "no limit".
If you want "no limit", set the limit to UQUAD_MAX (tools will
understand "unlimited" and "-")

A quota file is structured as follow:
it starts with a header, containing a few per-filesystem values,
and the default quota limits.
Quota entries are linked together as a simple list, each entry has a
pointer (as an offset withing the file) to the next.
The header has a pointer to a list of free quota entries, and
a hash table of in-use entries. The size of the hash table depends
on the filesystem block size (header+hash table should fit in the
first block). The file is not sparse and is a multiple of
filesystem block size (when the free quota entry list is empty a new
filesystem block is allocated). quota entries to not cross
filesystem block boundaries.

In memory, the kernel keeps a cache of recently used quota entries
as a reference to the block number, and offset withing the block.
The quota entry itself is keept in the buf cache.

fsck_ffs(8), tunefs(8) and newfs(8) supports are completed (with
related atf tests :)
The kernel can update disk usage and report it via quotactl(2).

Todo: enforce quotas limits (limits are not checked by kernel yet)
update repquota, edquota and rpc.rquotad to the new world
implement compat_50_quotactl ioctl.
update quotactl(2) man page

fsck_ffs required fixes so that allocating new blocks or inodes will
properly update the superblock and cg sumaries. This was not an issue up
to now because superblock and cg sumaries check happened last, but now
allocations or frees can happen in pass 6.
 1.27.2.1 06-Jun-2011  jruoho Sync with HEAD.
 1.29.6.1 18-Feb-2012  mrg merge to -current.
 1.29.2.2 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.29.2.1 17-Apr-2012  yamt sync with head
 1.34.10.1 18-May-2014  rmind sync with head
 1.34.6.2 03-Dec-2017  jdolecek update from HEAD
 1.34.6.1 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.35.2.1 10-Aug-2014  tls Rebase.
 1.36.12.1 21-Apr-2017  bouyer Sync with HEAD
 1.36.8.2 26-Apr-2017  pgoyette Sync with HEAD
 1.36.8.1 20-Mar-2017  pgoyette Sync with HEAD
 1.36.4.2 28-Aug-2017  skrll Sync with HEAD
 1.36.4.1 05-Feb-2017  skrll Sync with HEAD
 1.39.6.1 04-Jun-2017  bouyer pullup the following revisions, requested by hannken in ticket #2:
src/share/man/man9/fstrans.9 1.25
src/sys/kern/vfs_mount.c 1.66
src/sys/kern/vfs_subr.c 1.468
src/sys/kern/vfs_trans.c 1.46
src/sys/kern/vfs_vnode.c 1.94, 1.95, 1.96
src/sys/kern/vnode_if.c 1.105, 1.106
src/sys/kern/vnode_if.sh 1.65, 1.66
src/sys/kern/vnode_if.src 1.76
src/sys/miscfs/genfs/genfs_io.c 1.69
src/sys/miscfs/genfs/genfs_vnops.c 1.196, 1.197
src/sys/miscfs/genfs/layer_extern.h 1.40
src/sys/miscfs/genfs/layer_vfsops.c 1.51
src/sys/miscfs/genfs/layer_vnops.c 1.67
src/sys/miscfs/nullfs/null_vnops.c 1.42
src/sys/miscfs/overlay/overlay_vnops.c 1.24
src/sys/miscfs/umapfs/umap_vnops.c 1.60
src/sys/rump/include/rump/rumpvnode_if.h 1.29, 1.30
src/sys/rump/librump/rumpkern/emul.c 1.182
src/sys/rump/librump/rumpvfs/rumpvnode_if.c 1.29, 1.30
src/sys/sys/fstrans.h 1.11
src/sys/sys/vnode.h 1.278
src/sys/sys/vnode_if.h 1.100, 1.101
src/sys/sys/vnode_impl.h 1.14, 1.15
src/sys/ufs/lfs/lfs_pages.c 1.12

Vnode state, lock and fstrans cleanup:
- Rename vnode state "VS_ACTIVE" to "VS_LOADED" and add synthetic
state "VS_ACTIVE" to assert a loaded vnode with usecount > 0.

- Redo FSTRANS in vnode_if.c and use it for VOP_LOCK and VOP_UNLOCK.

- Cleanup the genfs lock operations.

- Make "struct vnode_impl" member "vi_lock" a krwlock_t again.

- Remove the lock type argument from fstrans_start and
fstrans_start_nowait,
remove now unused FSTRANS state "FSTRANS_SUSPENDING".
 1.40.12.1 17-Jan-2020  ad Sync with head.
 1.40.6.1 08-Apr-2020  martin Merge changes from current as of 20200406
 1.39 10-Apr-2022  andvar fix various typos in comments and output/log messages.
 1.38 13-Apr-2020  ad Replace most uses of vp->v_usecount with a call to vrefcnt(vp), a function
that hides the details and does atomic_load_relaxed(). Signature matches
FreeBSD.
 1.37 09-Nov-2014  maxv branches: 1.37.20; 1.37.30;
Do not uselessly include <sys/malloc.h>.
 1.36 25-May-2014  hannken branches: 1.36.2;
Change layerfs from hashlist to vcache.
Make VI_LOCKSHARE public again.

Ride 6.99.43
 1.35 10-Feb-2014  hannken branches: 1.35.2;
Change layerfs_vget(), layerfs_fhtovp() and the various layer xxx_mount()
functions to unlock/relock the node for the call to layer_node_create().

Finally remove dirty hacks (LK_NOWAIT, kpause) from layer_node_find().
 1.34 09-Feb-2014  hannken When layer_node_alloc() finds another thread already inserted the node
into the hashlist and discards the now unneeded node it will raise a
panic "dead but not clean".

Reorder the initialization and use ungetnewvnode() to discard the node.
 1.33 29-Jan-2014  hannken Allow layer_node_create() with unlocked lower node and change
layer_bypass() to enter nodes from creation operations unlocked.
 1.32 12-Jun-2011  rmind branches: 1.32.2; 1.32.12; 1.32.16;
Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.
 1.31 21-Jul-2010  hannken branches: 1.31.6;
Make holding v_interlock mandatory for callers of vget().

Announced some time ago on tech-kern.
 1.30 02-Jul-2010  rmind Slightly clean-up layerfs and nullfs: update the big description more to
the reality (remove duplicate one in nullfs, merge some differences from
it), KNF, improve and update some comments, add few KASSERT()s, remove
unused declarations, avoid double inclusion of headers, misc.

No functional changes.
 1.29 06-Jun-2010  hannken Change layered file systems to always pass the locking VOP's down to the
leaf file system. Remove now unused member v_vnlock from struct vnode.
Welcome to 5.99.30

Discussed on tech-kern.
 1.28 08-Jan-2010  pooka branches: 1.28.2; 1.28.4;
The VATTR_NULL/VREF/VHOLD/HOLDRELE() macros lost their will to live
years ago when the kernel was modified to not alter ABI based on
DIAGNOSTIC, and now just call the respective function interfaces
(in lowercase). Plenty of mix'n match upper/lowercase has creeped
into the tree since then. Nuke the macros and convert all callsites
to lowercase.

no functional change
 1.27 15-Mar-2009  cegger ansify function definitions
 1.26 14-Mar-2009  dsl Change about 4500 of the K&R function definitions to ANSI ones.
There are still about 1600 left, but they have ',' or /* ... */
in the actual variable definitions - which my awk script doesn't handle.
There are also many that need () -> (void).
(The script does handle misordered arguments.)
 1.25 24-Jan-2008  ad branches: 1.25.10; 1.25.18; 1.25.24;
specfs changes for PR kern/37717 (raidclose() is no longer called on
shutdown). There are still problems with device access and a PR will be
filed.

- Kill checkalias(). Allow multiple vnodes to reference a single device.

- Don't play dangerous tricks with block vnodes to ensure that only one
vnode can describe a block device. Instead, prohibit concurrent opens of
block devices. As a bonus remove the unreliable code that prevents
multiple file system mounts on the same device. It's no longer needed.

- Track opens by vnode and by device. Issue cdev_close() when the last open
goes away, instead of abusing vnode::v_usecount to tell if the device is
open.
 1.24 23-Jan-2008  ad layer_node_find: if we find a node being cleaned out, then ignore it and
continue. A thread trying to clean out the extant layer vnode needs to
acquire the shared lock (i.e. the lower vnode's lock), which our caller
already holds. To allow the cleaning to succeed the current thread must make
progress. So, for a brief time more than one vnode in a layered file system
may refer to a single vnode in the lower file system.
 1.23 02-Jan-2008  ad Merge vmlocking2 to head.
 1.22 10-Oct-2007  ad branches: 1.22.4; 1.22.6; 1.22.10;
Merge from vmlocking:

- Split vnode::v_flag into three fields, depending on field locking.
- simple_lock -> kmutex in a few places.
- Fix some simple locking problems.
 1.21 09-Dec-2006  chs branches: 1.21.6; 1.21.18; 1.21.20; 1.21.22;
a smorgasbord of improvements to vnode locking and path lookup:
- LOCKPARENT is no longer relevant for lookup(), relookup() or VOP_LOOKUP().
these now always return the parent vnode locked. namei() works as before.
lookup() and various other paths no longer acquire vnode locks in the
wrong order via vrele(). fixes PR 32535.
as a nice side effect, path lookup is also up to 25% faster.
- the above allows us to get rid of PDIRUNLOCK.
- also get rid of WANTPARENT (just use LOCKPARENT and unlock it).
- remove an assumption in layer_node_find() that all file systems implement
a recursive VOP_LOCK() (unionfs doesn't).
- require that all file systems supply vfs_vptofh and vfs_fhtovp routines.
fill in eopnotsupp() for file systems that don't support being exported
and remove the checks for NULL. (layerfs calls these without checking.)
- in union_lookup1(), don't change refcounts in the ISDOTDOT case, just
adjust which vnode is locked. fixes PR 33374.
- apply fixes for ufs_rename() from ufs_vnops.c rev. 1.61 to ext2fs_rename().
 1.20 25-Nov-2006  elad branches: 1.20.2;
Part of PR/33280: Christian Ehrhardt: In the error path (which probably
can't happen) lmp->layerm_hashlock is not unlocked.
 1.19 24-Nov-2006  wiz s/existance/existence/, from Zafer.
 1.18 11-Dec-2005  christos branches: 1.18.20; 1.18.22;
merge ktrace-lwp.
 1.17 30-Aug-2005  xtraeme Remove __P()
 1.16 24-Jul-2005  erh Provide a sysctl (vfs.layerfs.debug) to control verbose output when
LAYERFS_DIAGNOSTIC is turned on.
 1.15 07-Aug-2003  agc branches: 1.15.16;
Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.
 1.14 29-Jun-2003  fvdl branches: 1.14.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.
 1.13 29-Jun-2003  thorpej Undo part of the ktrace/lwp changes. In particular:
* Remove the "lwp *" argument that was added to vget(). Turns out
that nothing actually used it!
* Remove the "lwp *" arguments that were added to VFS_ROOT(), VFS_VGET(),
and VFS_FHTOVP(); all they did was pass it to vget() (which, as noted
above, didn't use it).
* Remove all of the "lwp *" arguments to internal functions that were added
just to appease the above.
 1.12 28-Jun-2003  darrenr Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V
 1.11 20-Feb-2002  enami Don't use MALLOC for variable sized allocation.
 1.10 15-Nov-2001  lukem don't need <sys/types.h> when including <sys/param.h>
 1.9 10-Nov-2001  lukem add RCSIDs
 1.8 07-Jun-2001  wiz branches: 1.8.2; 1.8.6;
Typos in comments (misc/13133 by Michael K. Sanders)
 1.7 27-Nov-2000  chs branches: 1.7.2;
Initial integration of the Unified Buffer Cache project.
 1.6 16-Mar-2000  jdolecek Add new VFS op routine - vfs_done and call it on filesystem detach
in vfs_detach(). vfs_done may free global filesystem's resources,
typically those allocated in respective filesystem's init function.
Needed so those filesystems which went in via LKM have a chance to
clean after themselves before unloading. This fixes random panics
when LKM for filesystem using pools was loaded and unloaded several
times.

For each leaf filesystem, add appropriate vfs_done routine.
 1.5 13-Mar-2000  soren Fix doubled 'the's in comments.
 1.4 25-Oct-1999  wrstuden Since we don't put layered device nodes in the spechash hash chains,
initialize vp->v_hashchain to NULL.
 1.3 15-Jul-1999  wrstuden branches: 1.3.2; 1.3.4; 1.3.6; 1.3.8;
Define VLAYER and make layered fs's set this flag when creating their vnodes.

getnewvnode now checks this bit, and it if's set makes sure a vnode's not
locked before removing it from the free list.

Closes PR 7954 by Alan Barrett <apb@iafrica.com>.
 1.2 12-Jul-1999  wrstuden Fix tyop pointed out by Chuck Silvers <chuq@chuq.com>.
 1.1 08-Jul-1999  wrstuden Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.3.8.1 27-Dec-1999  wrstuden Pull up to last week's -current.
 1.3.6.1 15-Nov-1999  fvdl Sync with -current
 1.3.4.2 08-Dec-2000  bouyer Sync with HEAD.
 1.3.4.1 20-Nov-2000  bouyer Update thorpej_scsipi to -current as of a month ago
 1.3.2.2 02-Aug-1999  thorpej Update from trunk.
 1.3.2.1 15-Jul-1999  thorpej file layer_subr.c was added on branch chs-ubc2 on 1999-08-02 22:27:34 +0000
 1.7.2.4 28-Feb-2002  nathanw Catch up to -current.
 1.7.2.3 08-Jan-2002  nathanw Catch up to -current.
 1.7.2.2 14-Nov-2001  nathanw Catch up to -current.
 1.7.2.1 21-Jun-2001  nathanw Catch up to -current.
 1.8.6.1 12-Nov-2001  thorpej Sync the thorpej-mips-cache branch with -current.
 1.8.2.2 16-Mar-2002  jdolecek Catch up with -current.
 1.8.2.1 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.14.2.6 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.14.2.5 21-Sep-2004  skrll Fix the sync with head I botched.
 1.14.2.4 18-Sep-2004  skrll Sync with HEAD.
 1.14.2.3 24-Aug-2004  skrll Undo part of the ktrace/lwp changes. In particular:
* Remove the "lwp *" argument that was added to vget(). Turns out
that nothing actually used it!
* Remove the "lwp *" arguments that were added to VFS_ROOT(), VFS_VGET(),
and VFS_FHTOVP(); all they did was pass it to vget() (which, as noted
above, didn't use it).
* Remove all of the "lwp *" arguments to internal functions that were added
just to appease the above.
 1.14.2.2 03-Aug-2004  skrll Sync with HEAD
 1.14.2.1 02-Jul-2003  darrenr Apply the aborted ktrace-lwp changes to a specific branch. This is just for
others to review, I'm concerned that patch fuziness may have resulted in some
errant code being generated but I'll look at that later by comparing the diff
from the base to the branch with the file I attempt to apply to it. This will,
at the very least, put the changes in a better context for others to review
them and attempt to tinker with removing passing of 'struct lwp' through
the kernel.
 1.15.16.5 04-Feb-2008  yamt sync with head.
 1.15.16.4 21-Jan-2008  yamt sync with head
 1.15.16.3 27-Oct-2007  yamt sync with head.
 1.15.16.2 30-Dec-2006  yamt sync with head.
 1.15.16.1 21-Jun-2006  yamt sync with head.
 1.18.22.1 10-Dec-2006  yamt sync with head.
 1.18.20.1 12-Jan-2007  ad Sync with head.
 1.20.2.1 17-Feb-2007  tron Apply patch (requested by chs in ticket #422):
- Fix various deadlock problems with nullfs and unionfs.
- Speed up path lookups by upto 25%.
 1.21.22.1 14-Oct-2007  yamt sync with head.
 1.21.20.3 23-Mar-2008  matt sync with HEAD
 1.21.20.2 09-Jan-2008  matt sync with HEAD
 1.21.20.1 06-Nov-2007  matt sync with HEAD
 1.21.18.1 26-Oct-2007  joerg Sync with HEAD.

Follow the merge of pmap.c on i386 and amd64 and move
pmap_init_tmp_pgtbl into arch/x86/x86/pmap.c. Modify the ACPI wakeup
code to restore CR4 before jumping back into kernel space as the large
page option might cover that.
 1.21.6.2 17-Jun-2007  ad - Increase the number of thread priorities from 128 to 256. How the space
is set up is to be revisited.
- Implement soft interrupts as kernel threads. A generic implementation
is provided, with hooks for fast-path MD code that can run the interrupt
threads over the top of other threads executing in the kernel.
- Split vnode::v_flag into three fields, depending on how the flag is
locked (by the interlock, by the vnode lock, by the file system).
- Miscellaneous locking fixes and improvements.
 1.21.6.1 13-Mar-2007  ad Pull in the initial set of changes for the vmlocking branch.
 1.22.10.1 02-Jan-2008  bouyer Sync with HEAD
 1.22.6.3 12-Dec-2007  ad layer_node_alloc: copy VV_MPSAFE from lowervp.
 1.22.6.2 06-Dec-2007  ad - layer_node_find: fix a race.
- Use kmem_alloc/free.
 1.22.6.1 04-Dec-2007  ad Pull the vmlocking changes into a new branch.
 1.22.4.1 18-Feb-2008  mjf Sync with HEAD.
 1.25.24.1 13-May-2009  jym Sync with HEAD.

Commit is split, to avoid a "too many arguments" protocol error.
 1.25.18.1 28-Apr-2009  skrll Sync with HEAD.
 1.25.10.3 11-Aug-2010  yamt sync with head.
 1.25.10.2 11-Mar-2010  yamt sync with head
 1.25.10.1 04-May-2009  yamt sync with head.
 1.28.4.5 30-May-2011  rmind - Amend getnewvnode(9) to take the lock for sharing, not a vnode.
- Update tmpfs to perform vnode and UVM object lock sharing correctly.
 1.28.4.4 19-May-2011  rmind Implement sharing of vnode_t::v_interlock amongst vnodes:
- Lock is shared amongst UVM objects using uvm_obj_setlock() or getnewvnode().
- Adjust vnode cache to handle unsharing, add VI_LOCKSHARE flag for that.
- Use sharing in tmpfs and layerfs for underlying object.
- Simplify locking in ubc_fault().
- Sprinkle some asserts.

Discussed with ad@.
 1.28.4.3 05-Mar-2011  rmind sync with head
 1.28.4.2 03-Jul-2010  rmind sync with head
 1.28.4.1 16-Mar-2010  rmind Change struct uvm_object::vmobjlock to be dynamically allocated with
mutex_obj_alloc(). It allows us to share the locks among UVM objects.
 1.28.2.1 17-Aug-2010  uebayasi Sync with HEAD.
 1.31.6.1 23-Jun-2011  cherry Catchup with rmind-uvmplock merge.
 1.32.16.1 18-May-2014  rmind sync with head
 1.32.12.2 03-Dec-2017  jdolecek update from HEAD
 1.32.12.1 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.32.2.1 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.35.2.1 10-Aug-2014  tls Rebase.
 1.36.2.1 17-Jan-2015  martin Pull up following revision(s) (requested by maxv in ticket #427):
sys/compat/svr4/svr4_schedctl.c: revision 1.8
sys/netinet/tcp_timer.c: revision 1.88
sys/miscfs/genfs/layer_vfsops.c: revision 1.45
sys/compat/svr4/svr4_ioctl.c: revision 1.37
sys/ufs/chfs/chfs_vfsops.c: revision 1.14
sys/miscfs/fdesc/fdesc_vfsops.c: revision 1.91
sys/compat/linux/arch/i386/linux_ptrace.c: revision 1.30
sys/compat/common/kern_time_50.c: revision 1.28
sys/netinet6/ip6_forward.c: revision 1.74
sys/miscfs/umapfs/umap_vnops.c: revision 1.57
sys/compat/svr4/svr4_fcntl.c: revision 1.74
distrib/sets/lists/comp/mi: revision 1.1931
sys/netinet6/udp6_output.c: revision 1.46
sys/fs/puffs/puffs_compat.c: revision 1.3
sys/fs/udf/udf_rename.c: revision 1.11
sys/compat/svr4/svr4_filio.c: revision 1.24
sys/fs/udf/udf_rename.c: revision 1.12
sys/netinet/tcp_usrreq.c: revision 1.202
sys/miscfs/umapfs/umap_subr.c: revision 1.29
sys/compat/linux/common/linux_fadvise64.c: revision 1.3
sys/netinet/if_atm.c: revision 1.34
sys/miscfs/procfs/procfs_subr.c: revision 1.106
sys/miscfs/genfs/layer_subr.c: revision 1.37
sys/netinet/tcp_sack.c: revision 1.30
sys/compat/freebsd/freebsd_misc.c: revision 1.33
sys/compat/freebsd/freebsd_file.c: revision 1.33
sys/ufs/chfs/chfs_vnode.c: revision 1.12
sys/compat/svr4/svr4_ttold.c: revision 1.34
sys/compat/linux/common/linux_file.c: revision 1.114
sys/compat/linux/arch/mips/linux_machdep.c: revision 1.43
sys/compat/linux/common/linux_signal.c: revision 1.76
sys/compat/common/compat_util.c: revision 1.46
sys/compat/linux/arch/arm/linux_ptrace.c: revision 1.18
sys/compat/svr4/svr4_sockio.c: revision 1.36
sys/compat/linux/arch/arm/linux_machdep.c: revision 1.32
sys/compat/svr4/svr4_signal.c: revision 1.66
sys/kern/kern_exec.c: revision 1.410
sys/fs/puffs/puffs_vfsops.c: revision 1.115
sys/compat/svr4/svr4_exec_elf64.c: revision 1.15
sys/compat/linux/arch/i386/linux_machdep.c: revision 1.159
sys/compat/linux/arch/alpha/linux_machdep.c: revision 1.50
sys/compat/linux32/common/linux32_misc.c: revision 1.24
sys/netinet/in_pcb.c: revision 1.153
sys/sys/malloc.h: revision 1.116
sys/compat/common/if_43.c: revision 1.9
share/man/man9/Makefile: revision 1.380
sys/netinet/tcp_vtw.c: revision 1.12
sys/miscfs/umapfs/umap_vfsops.c: revision 1.95
sys/ufs/ext2fs/ext2fs_vfsops.c: revision 1.186
sys/compat/common/uipc_syscalls_43.c: revision 1.46
sys/ufs/ext2fs/ext2fs_vnops.c: revision 1.115
sys/fs/puffs/puffs_msgif.c: revision 1.97
sys/compat/svr4/svr4_ipc.c: revision 1.27
sys/compat/linux/common/linux_exec.c: revision 1.117
sys/ufs/ext2fs/ext2fs_readwrite.c: revision 1.66
sys/netinet/tcp_output.c: revision 1.179
sys/compat/svr4/svr4_termios.c: revision 1.28
sys/fs/udf/udf_strat_bootstrap.c: revision 1.4
sys/fs/puffs/puffs_subr.c: revision 1.67
sys/fs/puffs/puffs_node.c: revision 1.36
sys/miscfs/overlay/overlay_vnops.c: revision 1.21
sys/fs/cd9660/cd9660_node.c: revision 1.34
sys/netinet/raw_ip.c: revision 1.146
sys/sys/mallocvar.h: revision 1.13
sys/miscfs/overlay/overlay_vfsops.c: revision 1.63
share/man/man9/malloc.9: revision 1.50
sys/netinet6/dest6.c: revision 1.18
sys/compat/linux/common/linux_uselib.c: revision 1.33
sys/compat/linux/common/linux_socket.c: revision 1.120
share/man/man9/malloc.9: revision 1.51
sys/netinet/tcp_subr.c: revision 1.257
sys/compat/linux/common/linux_socketcall.c: revision 1.45
sys/compat/linux/common/linux_fadvise64_64.c: revision 1.3
sys/compat/freebsd/freebsd_ipc.c: revision 1.17
sys/compat/linux/common/linux_misc_notalpha.c: revision 1.109
sys/compat/linux/arch/alpha/linux_pipe.c: revision 1.17
sys/netinet6/in6_pcb.c: revision 1.132
sys/netinet6/in6_ifattach.c: revision 1.94
sys/compat/svr4/svr4_exec_elf32.c: revision 1.15
sys/miscfs/nullfs/null_vfsops.c: revision 1.90
sys/fs/cd9660/cd9660_util.c: revision 1.12
sys/compat/linux/arch/powerpc/linux_machdep.c: revision 1.48
sys/compat/freebsd/freebsd_exec_elf32.c: revision 1.20
sys/miscfs/procfs/procfs_vfsops.c: revision 1.94
sys/compat/linux/arch/powerpc/linux_ptrace.c: revision 1.28
sys/compat/linux/common/linux_sched.c: revision 1.67
sys/compat/linux/common/linux_exec_aout.c: revision 1.67
sys/compat/linux/common/linux_pipe.c: revision 1.67
sys/compat/linux/common/linux_llseek.c: revision 1.34
sys/compat/linux/arch/mips/linux_ptrace.c: revision 1.10
Do not uselessly include <sys/malloc.h>.
Cleanup:
- remove struct kmembuckets (dead)
- correctly deadify MALLOC_XX
- remove MALLOC_DEFINE_LIMIT and MALLOC_JUSTDEFINE_LIMIT (dead)
- remove malloc_roundup(), malloc_type_setlimit(), MALLOC_DEFINE_LIMIT()
and MALLOC_JUSTDEFINE_LIMIT() from man 9 malloc
New sentence, new line. Bump date for previous.
Obsolete malloc_roundup(9), malloc_type_setlimit(9) and MALLOC_DEFINE_LIMIT(9)
man pages.
 1.37.30.1 20-Apr-2020  bouyer Sync with HEAD
 1.37.20.1 21-Apr-2020  martin Sync with HEAD
 1.56 09-Dec-2022  hannken Harden layered file systems usage of field "mnt_lower" against
forced unmounts of the lower layer.

- Dont allow "dead_rootmount" as lower layer.

- Take file system busy before a vfs operation walks down the stack.

Reported-by: syzbot+27b35e5675b1753cec03@syzkaller.appspotmail.com
Reported-by: syzbot+99071492e3de2eff49e9@syzkaller.appspotmail.com
 1.55 18-Jul-2022  thorpej Make kqueue event status for vnodes shareable, and for stacked file systems
like nullfs, make the upper vnode share that status with the lower vnode.

And, lo, NetBSD 9.99.99.

Fixes PR kern/56713.
 1.54 23-Feb-2020  ad UVM locking changes, proposed on tech-kern:

- Change the lock on uvm_object, vm_amap and vm_anon to be a RW lock.
- Break v_interlock and vmobjlock apart. v_interlock remains a mutex.
- Do partial PV list locking in the x86 pmap. Others to follow later.
 1.53 17-Jan-2020  ad VFS_VGET(), VFS_ROOT(), VFS_FHTOVP(): give them a "int lktype" argument, to
allow us to get shared locks (or no lock) on the returned vnode. Matches
FreeBSD.
 1.52 07-Aug-2019  pgoyette branches: 1.52.2;
Many years ago someone created a new __link_set_sysctl_funcs to hold
the list of routines that need to be called for setting up sysctl
variables. This worked great for all code included in the kernel
itself, but didn't deal with modules that want to create their own
sysctl data. So, we ended up with a lot of #ifdef _MODULE blocks
so modules could explicitly call their setup functions when loaded
as non-built-in modules.

So today, we complete the task that was started so many years ago.

When modules are loaded, after we've called xxx_modcmd(INIT...) we
check if the module contains its own __link_set_sysctl_funcs, and
if so we call the functions listed. We add a struct sysctllog member
to the struct module so we can call sysctl_teardown() when the module
gets unloaded. (The sequence of events ensures that the sysctl stuff
doesn't get created until the rest of the module's init code does any
required memory allocation.)

So, no more need to explicitly call the sysctl setup routines when
built as a loadable module.
 1.51 04-Jun-2017  hannken branches: 1.51.6;
Locking a layer vnode using the regular bypass routine is no longer
racy. Undo the change from 2017-03-30 11:16:52, commitid eurqbzuGxGRlryLz
and make vi_lock a krwlock_t again.
 1.50 01-Jun-2017  chs branches: 1.50.2;
remove checks for failure after memory allocation calls that cannot fail:

kmem_alloc() with KM_SLEEP
kmem_zalloc() with KM_SLEEP
percpu_alloc()
pserialize_create()
psref_class_create()

all of these paths include an assertion that the allocation has not failed,
so callers should not assert that again.
 1.49 11-Apr-2017  hannken Field "layerm_vfs" of "struct layer_mount" got superseded by "mnt_lower".
Adapt consumers and remove the now unused field.

Ride 7.99.68
 1.48 30-Mar-2017  hannken Locking a layer vnode is racy as it may become reclaimed before
calling the operation on the lower vnode.

Replace vi_lock with a rw_obj and change layered file systems
to share the lock with the lower vnode.

Layered file systems now use genfs_lock()/_unlock/_islocked().

Welcome to 7.99.67
 1.47 17-Feb-2017  hannken Add generic genfs_suspendctl() and use it for all file systems.
Layered file systems need work.
 1.46 20-Apr-2015  riastradh branches: 1.46.2; 1.46.4;
Cull unused vnode v_iflags: VI_LAYER, VI_LOCKSHARE.
 1.45 09-Nov-2014  maxv branches: 1.45.2;
Do not uselessly include <sys/malloc.h>.
 1.44 25-May-2014  hannken branches: 1.44.2;
Change layerfs from hashlist to vcache.
Make VI_LOCKSHARE public again.

Ride 6.99.43
 1.43 25-Feb-2014  pooka branches: 1.43.2;
Ensure that the top level sysctl nodes (kern, vfs, net, ...) exist before
the sysctl link sets are processed, and remove redundancy.

Shaves >13kB off of an amd64 GENERIC, not to mention >1k duplicate
lines of code.
 1.42 10-Feb-2014  hannken Change layerfs_vget(), layerfs_fhtovp() and the various layer xxx_mount()
functions to unlock/relock the node for the call to layer_node_create().

Finally remove dirty hacks (LK_NOWAIT, kpause) from layer_node_find().
 1.41 31-May-2012  pgoyette branches: 1.41.2; 1.41.4;
Ooopppsss! sysctl nodes created during module load time cannot be
PERMANENT
 1.40 31-May-2012  pgoyette When built as module, track sysctl node creations, and destroy them on
module exit.
 1.39 01-Feb-2012  dholland Change the syscall API for quotas over to the new non-proplib one.

- struct vfs_quotactl_args -> struct quotactl_args
- add sys/stdint.h to sys/quotactl.h for clean userland build
- install sys/quotactl.h in /usr/include
- update set lists for same
- add new marshalling code in libquota
- add new unmarshalling code in vfs_syscalls.c
- discard proplib interpreter code in vfs_quotactl.c
- add dispatching code for the 14 quotactl ops in vfs_quotactl.c
- mark the proplib quotactl syscall obsolete
- add a new syscall number for the new quotactl syscall
- change the name of the syscall to __quotactl()
- remove the decl of the old quotactl from quota/quotaprop.h
- add a decl of the new quotactl to sys/quotactl.h
- update the libc build
- update ktruss
- remove proplib marshalling code from libquota
- update copy of syscall table in gdb ppc sources
- hack rumphijack to accomodate new quotactl name (as I recall,
pooka wanted such a name change to simplify something, but I
don't really see what/how)

This change appears to require a kernel version bump for rumpish
reasons.
 1.38 29-Jan-2012  dholland Remove the extra op argument to VFS_QUOTACTL() - the op is now stored
purely in the args structure.

This change requires a kernel version bump.
 1.37 29-Jan-2012  dholland Introduce struct vfs_quotactl_args. Use it.

This change uglifies vfs_quotactl some in order to make room for
moving operation-specific but FS-independent logic out of ufs_quota.c.

Note: this change requires a kernel version bump.
 1.36 29-Jan-2012  dholland Move the proplib-based quota command dispatching (that is, the code
that knows the magic string names for the allowed actions) out of
UFS-specific code and to fs-independent code.

This introduces QUOTACTL_* operation codes and changes the signature
of VFS_QUOTACTL() again for compile safety.

Note: this change requires a kernel version bump.
 1.35 29-Jan-2012  dholland Move the code for iterating over the multiple RPC calls in a quota
proplib XML packet to vfs_quotactl.c out of sys/ufs/ufs.

Add a dummy extra arg to VFS_QUOTACTL for compile safety.

Note: this change requires a kernel version bump.
 1.34 06-Mar-2011  bouyer branches: 1.34.4; 1.34.8;
merge the bouyer-quota2 branch. This adds a new on-disk format
to store disk quota usage and limits, integrated with ffs
metadata. Usage is checked by fsck_ffs (no more quotacheck)
and is covered by the WAPBL journal. Enabled with kernel
option QUOTA2 (added where QUOTA was enabled in kernel config files),
turned on with tunefs(8) on a per-filesystem
basis. mount_mfs(8) can also turn quotas on.

See http://mail-index.netbsd.org/tech-kern/2011/02/19/msg010025.html
for details.
 1.33 02-Jul-2010  rmind branches: 1.33.2; 1.33.4;
Slightly clean-up layerfs and nullfs: update the big description more to
the reality (remove duplicate one in nullfs, merge some differences from
it), KNF, improve and update some comments, add few KASSERT()s, remove
unused declarations, avoid double inclusion of headers, misc.

No functional changes.
 1.32 08-Jan-2010  pooka branches: 1.32.2; 1.32.4;
The VATTR_NULL/VREF/VHOLD/HOLDRELE() macros lost their will to live
years ago when the kernel was modified to not alter ABI based on
DIAGNOSTIC, and now just call the respective function interfaces
(in lowercase). Plenty of mix'n match upper/lowercase has creeped
into the tree since then. Nuke the macros and convert all callsites
to lowercase.

no functional change
 1.31 14-Mar-2009  dsl Change about 4500 of the K&R function definitions to ANSI ones.
There are still about 1600 left, but they have ',' or /* ... */
in the actual variable definitions - which my awk script doesn't handle.
There are also many that need () -> (void).
(The script does handle misordered arguments.)
 1.30 05-Dec-2008  ad branches: 1.30.4;
PR kern/40110: null, overlay and umap modules loading -> panic (layerfs symbols not there)

Add a layerfs module.
 1.29 28-Jan-2008  dholland branches: 1.29.6; 1.29.10; 1.29.16; 1.29.18;
Fix some race conditions in rename.
Introduce a per-FS rename lock and new vfsops to manipulate it.
Get this lock while renaming. Also add another relookup() in do_sys_rename,
which is a hack to kludge around some of the worst deficiencies of
ufs_rename.
reviewed-by: pooka (and an earlier rev by ad)
posted on tech-kern with no objections.
 1.28 08-Dec-2007  ad Use kmem_alloc/free.
 1.27 26-Nov-2007  pooka branches: 1.27.2;
Remove the "struct lwp *" argument from all VFS and VOP interfaces.
The general trend is to remove it from all kernel interfaces and
this is a start. In case the calling lwp is desired, curlwp should
be used.

quick consensus on tech-kern
 1.26 16-Nov-2006  christos branches: 1.26.12; 1.26.22; 1.26.24; 1.26.30;
__unused removal on arguments; approved by core.
 1.25 12-Oct-2006  christos - sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386
 1.24 13-Jul-2006  martin branches: 1.24.4; 1.24.6;
Fix alignement problems for fhandle_t, exposed by gcc4.1.

While touching all vptofh/fhtovp functions, get rid of VFS_MAXFIDSIZ,
version the getfh(2) syscall and explicitly pass the size available in
the filehandle from userland.

Discussed on tech-kern, with lots of help from yamt (thanks!).
 1.23 14-May-2006  elad branches: 1.23.4;
integrate kauth.
 1.22 11-Dec-2005  christos branches: 1.22.4; 1.22.6; 1.22.8; 1.22.10; 1.22.12;
merge ktrace-lwp.
 1.21 23-Sep-2005  jmmv Apply the NFS exports list rototill patch:

- Remove all NFS related stuff from file system specific code.
- Drop the vfs_checkexp hook and generalize it in the new nfs_check_export
function, thus removing redundancy from all file systems.
- Move all NFS export-related stuff from kern/vfs_subr.c to the new
file sys/nfs/nfs_export.c. The former was becoming large and its code
is always compiled, regardless of the build options. Using the latter,
the code is only compiled in when NFSSERVER is enabled. While doing this,
also make some functions in nfs_subs.c conditional to NFSSERVER.
- Add a new command in nfssvc(2), called NFSSVC_SETEXPORTSLIST, that takes a
path and a set of export entries. At the moment it can only clear the
exports list or append entries, one by one, but it is done in a way that
allows setting the whole set of entries atomically in the future (see the
comment in mountd_set_exports_list or in doc/TODO).
- Change mountd(8) to use the nfssvc(2) system call instead of mount(2) so
that it becomes file system agnostic. In fact, all this whole thing was
done to remove a 'XXX' block from this utility!
- Change the mount*, newfs and fsck* userland utilities to not deal with NFS
exports initialization; done internally by the kernel when initializing
the NFS support for each file system.
- Implement an interface for VFS (called VFS hooks) so that several kernel
subsystems can run arbitrary code upon receipt of specific VFS events.
At the moment, this only provides support for unmount and is used to
destroy NFS exports lists from the file systems being unmounted, though it
has room for extension.

Thanks go to yamt@, chs@, thorpej@, wrstuden@ and others for their comments
and advice in the development of this patch.
 1.20 24-Jul-2005  erh Provide a sysctl (vfs.layerfs.debug) to control verbose output when
LAYERFS_DIAGNOSTIC is turned on.
 1.19 29-May-2004  wrstuden branches: 1.19.12;
Add layerfs_snapshot() as a handler routine for VFS_SNAPSHOT() calls
through a layered file system.

Note: we don't actually support snapshots through a layered file system,
and this routine returns an error. However we: 1) have clearly documented
what needs fixing (which isn't trivial to fix) and 2) if we do fix
this, all layered file systems can take advantage of it at once.
 1.18 25-May-2004  atatat Sysctl descriptions under vfs subtree
 1.17 22-May-2004  christos Unfortunately, we need to allocate space here. Pointed out by Juan RP.
 1.16 22-May-2004  christos we are copying all the infomation from statvfs here; we don't need an
intermediate copy on the stack.
 1.15 27-Apr-2004  jrf First pass for some caddr_t removal and changes to get rid of it where we
no longer use and/or need it

- removed casts from unionfs, deadfs and fdesc
(there are more to hunt down still)
- changed vfs_quotactl args argumet from caddr_t to void *
- changed vfs_quotactl structures/callers to reflect the api change

Compiled fine and ran for about a day. Approved/reviewed by
christos@netbsd.org and gimpy@netbsd.org.
 1.14 21-Apr-2004  christos Replace the statfs() family of system calls with statvfs().
Retain binary compatibility.
 1.13 24-Mar-2004  atatat branches: 1.13.2;
Tango on sysctl_createv() and flags. The flags have all been renamed,
and sysctl_createv() now uses more arguments.
 1.12 17-Jan-2004  atatat Rename sysctl setup function to match "reality"
 1.11 04-Dec-2003  atatat Dynamic sysctl.

Gone are the old kern_sysctl(), cpu_sysctl(), hw_sysctl(),
vfs_sysctl(), etc, routines, along with sysctl_int() et al. Now all
nodes are registered with the tree, and nodes can be added (or
removed) easily, and I/O to and from the tree is handled generically.

Since the nodes are registered with the tree, the mapping from name to
number (and back again) can now be discovered, instead of having to be
hard coded. Adding new nodes to the tree is likewise much simpler --
the new infrastructure handles almost all the work for simple types,
and just about anything else can be done with a small helper function.

All existing nodes are where they were before (numerically speaking),
so all existing consumers of sysctl information should notice no
difference.

PS - I'm sorry, but there's a distinct lack of documentation at the
moment. I'm working on sysctl(3/8/9) right now, and I promise to
watch out for buses.
 1.10 07-Aug-2003  agc Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.
 1.9 29-Jun-2003  fvdl branches: 1.9.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.
 1.8 29-Jun-2003  thorpej Undo part of the ktrace/lwp changes. In particular:
* Remove the "lwp *" argument that was added to vget(). Turns out
that nothing actually used it!
* Remove the "lwp *" arguments that were added to VFS_ROOT(), VFS_VGET(),
and VFS_FHTOVP(); all they did was pass it to vget() (which, as noted
above, didn't use it).
* Remove all of the "lwp *" arguments to internal functions that were added
just to appease the above.
 1.7 28-Jun-2003  darrenr Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V
 1.6 16-Apr-2003  christos PR/1796: John Kohl: statfs misbehaves under chrooted environments.

- Under chroot it displays only the visible filesystems with appropriate paths.
- The statfs f_mntonname gets adjusted to contain the real path from root.
- While was there, fixed a bug in ext2fs, locking problems with vfs_getfsstat(),
and factored out some of the vfsop statfs() code to copy_statfs_info(). This
fixes the problem where some filesystems forgot to set fsid.
- Made coda look more like a normal fs.
 1.5 15-Nov-2001  lukem don't need <sys/types.h> when including <sys/param.h>
 1.4 10-Nov-2001  lukem add RCSIDs
 1.3 07-Jun-2001  wiz branches: 1.3.2; 1.3.6;
Typos in comments (misc/13133 by Michael K. Sanders)
 1.2 13-Mar-2000  soren branches: 1.2.6;
Fix doubled 'the's in comments.
 1.1 08-Jul-1999  wrstuden branches: 1.1.2; 1.1.4;
Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.1.4.1 20-Nov-2000  bouyer Update thorpej_scsipi to -current as of a month ago
 1.1.2.2 02-Aug-1999  thorpej Update from trunk.
 1.1.2.1 08-Jul-1999  thorpej file layer_vfsops.c was added on branch chs-ubc2 on 1999-08-02 22:27:34 +0000
 1.2.6.3 08-Jan-2002  nathanw Catch up to -current.
 1.2.6.2 14-Nov-2001  nathanw Catch up to -current.
 1.2.6.1 21-Jun-2001  nathanw Catch up to -current.
 1.3.6.1 12-Nov-2001  thorpej Sync the thorpej-mips-cache branch with -current.
 1.3.2.1 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.9.2.6 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.9.2.5 21-Sep-2004  skrll Fix the sync with head I botched.
 1.9.2.4 18-Sep-2004  skrll Sync with HEAD.
 1.9.2.3 24-Aug-2004  skrll Undo part of the ktrace/lwp changes. In particular:
* Remove the "lwp *" argument that was added to vget(). Turns out
that nothing actually used it!
* Remove the "lwp *" arguments that were added to VFS_ROOT(), VFS_VGET(),
and VFS_FHTOVP(); all they did was pass it to vget() (which, as noted
above, didn't use it).
* Remove all of the "lwp *" arguments to internal functions that were added
just to appease the above.
 1.9.2.2 03-Aug-2004  skrll Sync with HEAD
 1.9.2.1 02-Jul-2003  darrenr Apply the aborted ktrace-lwp changes to a specific branch. This is just for
others to review, I'm concerned that patch fuziness may have resulted in some
errant code being generated but I'll look at that later by comparing the diff
from the base to the branch with the file I attempt to apply to it. This will,
at the very least, put the changes in a better context for others to review
them and attempt to tinker with removing passing of 'struct lwp' through
the kernel.
 1.13.2.1 29-May-2004  tron Pull up revision 1.18 (requested by atatat in ticket #393):
Sysctl descriptions under vfs subtree
 1.19.12.5 04-Feb-2008  yamt sync with head.
 1.19.12.4 21-Jan-2008  yamt sync with head
 1.19.12.3 07-Dec-2007  yamt sync with head
 1.19.12.2 30-Dec-2006  yamt sync with head.
 1.19.12.1 21-Jun-2006  yamt sync with head.
 1.22.12.1 24-May-2006  tron Merge 2006-05-24 NetBSD-current into the "peter-altq" branch.
 1.22.10.2 06-May-2006  christos - Move kauth_cred_t declaration to <sys/types.h>
- Cleanup struct ucred; forward declarations that are unused.
- Don't include <sys/kauth.h> in any header, but include it in the c files
that need it.

Approved by core.
 1.22.10.1 08-Mar-2006  elad Adapt to kernel authorization KPI.
 1.22.8.2 11-Aug-2006  yamt sync with head
 1.22.8.1 24-May-2006  yamt sync with head.
 1.22.6.1 01-Jun-2006  kardel Sync with head.
 1.22.4.1 09-Sep-2006  rpaulo sync with head
 1.23.4.1 13-Jul-2006  gdamore Merge from HEAD.
 1.24.6.2 10-Dec-2006  yamt sync with head.
 1.24.6.1 22-Oct-2006  yamt sync with head
 1.24.4.1 18-Nov-2006  ad Sync with head.
 1.26.30.3 18-Feb-2008  mjf Sync with HEAD.
 1.26.30.2 27-Dec-2007  mjf Sync with HEAD.
 1.26.30.1 08-Dec-2007  mjf Sync with HEAD.
 1.26.24.2 23-Mar-2008  matt sync with HEAD
 1.26.24.1 09-Jan-2008  matt sync with HEAD
 1.26.22.2 09-Dec-2007  jmcneill Sync with HEAD.
 1.26.22.1 27-Nov-2007  joerg Sync with HEAD. amd64 Xen support needs testing.
 1.26.12.1 09-Dec-2007  reinoud Pullup to HEAD
 1.27.2.2 08-Dec-2007  ad Sync with head.
 1.27.2.1 06-Dec-2007  ad - layer_node_find: fix a race.
- Use kmem_alloc/free.
 1.29.18.2 28-Apr-2009  skrll Sync with HEAD.
 1.29.18.1 19-Jan-2009  skrll Sync with HEAD.
 1.29.16.1 13-Dec-2008  haad Update haad-dm branch to haad-dm-base2.
 1.29.10.3 11-Aug-2010  yamt sync with head.
 1.29.10.2 11-Mar-2010  yamt sync with head
 1.29.10.1 04-May-2009  yamt sync with head.
 1.29.6.1 17-Jan-2009  mjf Sync with HEAD.
 1.30.4.1 13-May-2009  jym Sync with HEAD.

Commit is split, to avoid a "too many arguments" protocol error.
 1.32.4.2 21-Apr-2011  rmind sync with head
 1.32.4.1 03-Jul-2010  rmind sync with head
 1.32.2.1 17-Aug-2010  uebayasi Sync with HEAD.
 1.33.4.1 20-Jan-2011  bouyer Snapshot of work in progress on a modernised disk quota system:
- new quotactl syscall (versionned for backward compat), which takes
as parameter a path to a mount point, and a prop_dictionary
(in plistref format) describing commands and arguments.
For each command, status and data are returned as a prop_dictionary.
quota commands features will be added to take advantage of this,
exporting quota data or getting quota commands as plists.

- new on disk-format storage (all 64bit wide), integrated to metadata for
ffs (and playing nicely with wapbl).
Quotas are enabled on a ffs filesystem via superblock flags.
tunefs(8) can enable or disable quotas.
On a quota-enabled filesystem, fsck_ffs(8) will track per-uid/gid
block and inode usages, and will check and update quotas in Pass 6.
quota usage and limits are stored in unliked files (one for users,
one for groups)l fsck_ffs(8) will create the files if needed, or
free them if needed. This means that after enabling or disabling
quotas on a filesystem; a fsck_ffs(8) run is required.
quotacheck(8) is not needed any more, on a unclean shutdown
fsck or journal replay will take care of fixing quotas.
newfs(8) can create a ready-to-mount quota-enabled filesystem
(superblock flags are set and quota inodes are created).
Other new features or semantic changes:
- default quota datas, applied to users or groups which don't already
have a quota entry
- per-user/group grace time (instead of a filesystem global one)
- 0 really means "nothing allowed at all", not "no limit".
If you want "no limit", set the limit to UQUAD_MAX (tools will
understand "unlimited" and "-")

A quota file is structured as follow:
it starts with a header, containing a few per-filesystem values,
and the default quota limits.
Quota entries are linked together as a simple list, each entry has a
pointer (as an offset withing the file) to the next.
The header has a pointer to a list of free quota entries, and
a hash table of in-use entries. The size of the hash table depends
on the filesystem block size (header+hash table should fit in the
first block). The file is not sparse and is a multiple of
filesystem block size (when the free quota entry list is empty a new
filesystem block is allocated). quota entries to not cross
filesystem block boundaries.

In memory, the kernel keeps a cache of recently used quota entries
as a reference to the block number, and offset withing the block.
The quota entry itself is keept in the buf cache.

fsck_ffs(8), tunefs(8) and newfs(8) supports are completed (with
related atf tests :)
The kernel can update disk usage and report it via quotactl(2).

Todo: enforce quotas limits (limits are not checked by kernel yet)
update repquota, edquota and rpc.rquotad to the new world
implement compat_50_quotactl ioctl.
update quotactl(2) man page

fsck_ffs required fixes so that allocating new blocks or inodes will
properly update the superblock and cg sumaries. This was not an issue up
to now because superblock and cg sumaries check happened last, but now
allocations or frees can happen in pass 6.
 1.33.2.1 06-Jun-2011  jruoho Sync with HEAD.
 1.34.8.2 02-Jun-2012  mrg sync to latest -current.
 1.34.8.1 18-Feb-2012  mrg merge to -current.
 1.34.4.3 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.34.4.2 30-Oct-2012  yamt sync with head
 1.34.4.1 17-Apr-2012  yamt sync with head
 1.41.4.1 18-May-2014  rmind sync with head
 1.41.2.2 03-Dec-2017  jdolecek update from HEAD
 1.41.2.1 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.43.2.1 10-Aug-2014  tls Rebase.
 1.44.2.1 17-Jan-2015  martin Pull up following revision(s) (requested by maxv in ticket #427):
sys/compat/svr4/svr4_schedctl.c: revision 1.8
sys/netinet/tcp_timer.c: revision 1.88
sys/miscfs/genfs/layer_vfsops.c: revision 1.45
sys/compat/svr4/svr4_ioctl.c: revision 1.37
sys/ufs/chfs/chfs_vfsops.c: revision 1.14
sys/miscfs/fdesc/fdesc_vfsops.c: revision 1.91
sys/compat/linux/arch/i386/linux_ptrace.c: revision 1.30
sys/compat/common/kern_time_50.c: revision 1.28
sys/netinet6/ip6_forward.c: revision 1.74
sys/miscfs/umapfs/umap_vnops.c: revision 1.57
sys/compat/svr4/svr4_fcntl.c: revision 1.74
distrib/sets/lists/comp/mi: revision 1.1931
sys/netinet6/udp6_output.c: revision 1.46
sys/fs/puffs/puffs_compat.c: revision 1.3
sys/fs/udf/udf_rename.c: revision 1.11
sys/compat/svr4/svr4_filio.c: revision 1.24
sys/fs/udf/udf_rename.c: revision 1.12
sys/netinet/tcp_usrreq.c: revision 1.202
sys/miscfs/umapfs/umap_subr.c: revision 1.29
sys/compat/linux/common/linux_fadvise64.c: revision 1.3
sys/netinet/if_atm.c: revision 1.34
sys/miscfs/procfs/procfs_subr.c: revision 1.106
sys/miscfs/genfs/layer_subr.c: revision 1.37
sys/netinet/tcp_sack.c: revision 1.30
sys/compat/freebsd/freebsd_misc.c: revision 1.33
sys/compat/freebsd/freebsd_file.c: revision 1.33
sys/ufs/chfs/chfs_vnode.c: revision 1.12
sys/compat/svr4/svr4_ttold.c: revision 1.34
sys/compat/linux/common/linux_file.c: revision 1.114
sys/compat/linux/arch/mips/linux_machdep.c: revision 1.43
sys/compat/linux/common/linux_signal.c: revision 1.76
sys/compat/common/compat_util.c: revision 1.46
sys/compat/linux/arch/arm/linux_ptrace.c: revision 1.18
sys/compat/svr4/svr4_sockio.c: revision 1.36
sys/compat/linux/arch/arm/linux_machdep.c: revision 1.32
sys/compat/svr4/svr4_signal.c: revision 1.66
sys/kern/kern_exec.c: revision 1.410
sys/fs/puffs/puffs_vfsops.c: revision 1.115
sys/compat/svr4/svr4_exec_elf64.c: revision 1.15
sys/compat/linux/arch/i386/linux_machdep.c: revision 1.159
sys/compat/linux/arch/alpha/linux_machdep.c: revision 1.50
sys/compat/linux32/common/linux32_misc.c: revision 1.24
sys/netinet/in_pcb.c: revision 1.153
sys/sys/malloc.h: revision 1.116
sys/compat/common/if_43.c: revision 1.9
share/man/man9/Makefile: revision 1.380
sys/netinet/tcp_vtw.c: revision 1.12
sys/miscfs/umapfs/umap_vfsops.c: revision 1.95
sys/ufs/ext2fs/ext2fs_vfsops.c: revision 1.186
sys/compat/common/uipc_syscalls_43.c: revision 1.46
sys/ufs/ext2fs/ext2fs_vnops.c: revision 1.115
sys/fs/puffs/puffs_msgif.c: revision 1.97
sys/compat/svr4/svr4_ipc.c: revision 1.27
sys/compat/linux/common/linux_exec.c: revision 1.117
sys/ufs/ext2fs/ext2fs_readwrite.c: revision 1.66
sys/netinet/tcp_output.c: revision 1.179
sys/compat/svr4/svr4_termios.c: revision 1.28
sys/fs/udf/udf_strat_bootstrap.c: revision 1.4
sys/fs/puffs/puffs_subr.c: revision 1.67
sys/fs/puffs/puffs_node.c: revision 1.36
sys/miscfs/overlay/overlay_vnops.c: revision 1.21
sys/fs/cd9660/cd9660_node.c: revision 1.34
sys/netinet/raw_ip.c: revision 1.146
sys/sys/mallocvar.h: revision 1.13
sys/miscfs/overlay/overlay_vfsops.c: revision 1.63
share/man/man9/malloc.9: revision 1.50
sys/netinet6/dest6.c: revision 1.18
sys/compat/linux/common/linux_uselib.c: revision 1.33
sys/compat/linux/common/linux_socket.c: revision 1.120
share/man/man9/malloc.9: revision 1.51
sys/netinet/tcp_subr.c: revision 1.257
sys/compat/linux/common/linux_socketcall.c: revision 1.45
sys/compat/linux/common/linux_fadvise64_64.c: revision 1.3
sys/compat/freebsd/freebsd_ipc.c: revision 1.17
sys/compat/linux/common/linux_misc_notalpha.c: revision 1.109
sys/compat/linux/arch/alpha/linux_pipe.c: revision 1.17
sys/netinet6/in6_pcb.c: revision 1.132
sys/netinet6/in6_ifattach.c: revision 1.94
sys/compat/svr4/svr4_exec_elf32.c: revision 1.15
sys/miscfs/nullfs/null_vfsops.c: revision 1.90
sys/fs/cd9660/cd9660_util.c: revision 1.12
sys/compat/linux/arch/powerpc/linux_machdep.c: revision 1.48
sys/compat/freebsd/freebsd_exec_elf32.c: revision 1.20
sys/miscfs/procfs/procfs_vfsops.c: revision 1.94
sys/compat/linux/arch/powerpc/linux_ptrace.c: revision 1.28
sys/compat/linux/common/linux_sched.c: revision 1.67
sys/compat/linux/common/linux_exec_aout.c: revision 1.67
sys/compat/linux/common/linux_pipe.c: revision 1.67
sys/compat/linux/common/linux_llseek.c: revision 1.34
sys/compat/linux/arch/mips/linux_ptrace.c: revision 1.10
Do not uselessly include <sys/malloc.h>.
Cleanup:
- remove struct kmembuckets (dead)
- correctly deadify MALLOC_XX
- remove MALLOC_DEFINE_LIMIT and MALLOC_JUSTDEFINE_LIMIT (dead)
- remove malloc_roundup(), malloc_type_setlimit(), MALLOC_DEFINE_LIMIT()
and MALLOC_JUSTDEFINE_LIMIT() from man 9 malloc
New sentence, new line. Bump date for previous.
Obsolete malloc_roundup(9), malloc_type_setlimit(9) and MALLOC_DEFINE_LIMIT(9)
man pages.
 1.45.2.2 28-Aug-2017  skrll Sync with HEAD
 1.45.2.1 06-Jun-2015  skrll Sync with HEAD
 1.46.4.1 21-Apr-2017  bouyer Sync with HEAD
 1.46.2.2 26-Apr-2017  pgoyette Sync with HEAD
 1.46.2.1 20-Mar-2017  pgoyette Sync with HEAD
 1.50.2.1 04-Jun-2017  bouyer pullup the following revisions, requested by hannken in ticket #2:
src/share/man/man9/fstrans.9 1.25
src/sys/kern/vfs_mount.c 1.66
src/sys/kern/vfs_subr.c 1.468
src/sys/kern/vfs_trans.c 1.46
src/sys/kern/vfs_vnode.c 1.94, 1.95, 1.96
src/sys/kern/vnode_if.c 1.105, 1.106
src/sys/kern/vnode_if.sh 1.65, 1.66
src/sys/kern/vnode_if.src 1.76
src/sys/miscfs/genfs/genfs_io.c 1.69
src/sys/miscfs/genfs/genfs_vnops.c 1.196, 1.197
src/sys/miscfs/genfs/layer_extern.h 1.40
src/sys/miscfs/genfs/layer_vfsops.c 1.51
src/sys/miscfs/genfs/layer_vnops.c 1.67
src/sys/miscfs/nullfs/null_vnops.c 1.42
src/sys/miscfs/overlay/overlay_vnops.c 1.24
src/sys/miscfs/umapfs/umap_vnops.c 1.60
src/sys/rump/include/rump/rumpvnode_if.h 1.29, 1.30
src/sys/rump/librump/rumpkern/emul.c 1.182
src/sys/rump/librump/rumpvfs/rumpvnode_if.c 1.29, 1.30
src/sys/sys/fstrans.h 1.11
src/sys/sys/vnode.h 1.278
src/sys/sys/vnode_if.h 1.100, 1.101
src/sys/sys/vnode_impl.h 1.14, 1.15
src/sys/ufs/lfs/lfs_pages.c 1.12

Vnode state, lock and fstrans cleanup:
- Rename vnode state "VS_ACTIVE" to "VS_LOADED" and add synthetic
state "VS_ACTIVE" to assert a loaded vnode with usecount > 0.

- Redo FSTRANS in vnode_if.c and use it for VOP_LOCK and VOP_UNLOCK.

- Cleanup the genfs lock operations.

- Make "struct vnode_impl" member "vi_lock" a krwlock_t again.

- Remove the lock type argument from fstrans_start and
fstrans_start_nowait,
remove now unused FSTRANS state "FSTRANS_SUSPENDING".
 1.51.6.2 13-Apr-2020  martin Mostly merge changes from HEAD upto 20200411
 1.51.6.1 08-Apr-2020  martin Merge changes from current as of 20200406
 1.52.2.2 29-Feb-2020  ad Sync with head.
 1.52.2.1 17-Jan-2020  ad Sync with head.
 1.72 20-Oct-2021  thorpej Overhaul of the EVFILT_VNODE kevent(2) filter:

- Centralize vnode kevent handling in the VOP_*() wrappers, rather than
forcing each individual file system to deal with it (except VOP_RENAME(),
because VOP_RENAME() is a mess and we currently have 2 different ways
of handling it; at least it's reasonably well-centralized in the "new"
way).
- Add support for NOTE_OPEN, NOTE_CLOSE, NOTE_CLOSE_WRITE, and NOTE_READ,
compatible with the same events in FreeBSD.
- Track which kevent notifications clients are interested in receiving
to avoid doing work for events no one cares about (avoiding, e.g.
taking locks and traversing the klist to send a NOTE_WRITE when
someone is merely watching for a file to be deleted, for example).

In support of the above:

- Add support in vnode_if.sh for specifying PRE- and POST-op handlers,
to be invoked before and after vop_pre() and vop_post(), respectively.
Basic idea from FreeBSD, but implemented differently.
- Add support in vnode_if.sh for specifying CONTEXT fields in the
vop_*_args structures. These context fields are used to convey information
between the file system VOP function and the VOP wrapper, but do not
occupy an argument slot in the VOP_*() call itself. These context fields
are initialized and subsequently interpreted by PRE- and POST-op handlers.
- Version VOP_REMOVE(), uses the a context field for the file system to report
back the resulting link count of the target vnode. Return this in tmpfs,
udf, nfs, chfs, ext2fs, lfs, and ufs.

NetBSD 9.99.92.
 1.71 16-May-2020  christos Add ACL support for FFS. From FreeBSD.
 1.70 13-Apr-2020  ad Replace most uses of vp->v_usecount with a call to vrefcnt(vp), a function
that hides the details and does atomic_load_relaxed(). Signature matches
FreeBSD.
 1.69 04-Apr-2020  ad branches: 1.69.2;
Merge the remaining changes from the ad-namecache branch, affecting namei()
and getcwd():

- push vnode locking back as far as possible.
- do most lookups directly in the namecache, avoiding vnode locks & refs.
- don't block new refs to vnodes across VOP_INACTIVE().
- get shared locks for VOP_LOOKUP() if the file system supports it.
- correct lock types for VOP_ACCESS() / VOP_GETATTR() in a few places.

Possible future enhancements:

- make the lookups lockless.
- support dotdot lookups by being lockless and inferring absence of chroot.
- maybe make it work for layered file systems.
- avoid vnode references at the root & cwd.
 1.68 23-Feb-2020  ad UVM locking changes, proposed on tech-kern:

- Change the lock on uvm_object, vm_amap and vm_anon to be a RW lock.
- Break v_interlock and vmobjlock apart. v_interlock remains a mutex.
- Do partial PV list locking in the x86 pmap. Others to follow later.
 1.67 04-Jun-2017  hannken branches: 1.67.6; 1.67.12;
Operations fstrans_start() and fstrans_start_nowait() now always
use FSTRANS_SHARED as lock type so remove the lock type argument.

File system state FSTRANS_SUSPENDING is now unused so remove it.

Regen vnode_if files.

Ride 8.99.1 less than a hour ago.
 1.66 26-May-2017  riastradh branches: 1.66.2;
Make VOP_RECLAIM do the last unlock of the vnode.

VOP_RECLAIM naturally has exclusive access to the vnode, so having it
locked on entry is not strictly necessary -- but it means if there
are any final operations that must be done on the vnode, such as
ffs_update, requiring exclusive access to it, we can now kassert that
the vnode is locked in those operations.

We can't just have the caller release the last lock because some file
systems don't use genfs_lock, and require the vnode to remain valid
for VOP_UNLOCK to work, notably unionfs.
 1.65 24-May-2017  hannken Protect layer_getpages against vnodes disappearing during a
forced unmount.
 1.64 07-May-2017  hannken Move v_writecount adjustment from revoke to reclaim.
 1.63 26-Apr-2017  riastradh branches: 1.63.2;
Change VOP_REMOVE and VOP_RMDIR to preserve lock/ref on dvp.

No change to vp -- the plan is to replace the node by the
componentname in the vop parameters, and let all directory vops do
lookups internally.

Proposed on tech-kern with no objections:
https://mail-index.netbsd.org/tech-kern/2017/04/17/msg021825.html
 1.62 11-Apr-2017  riastradh Make VOP_INACTIVE preserve vnode lock on return.

Discussed on tech-kern:
https://mail-index.netbsd.org/tech-kern/2017/04/01/msg021751.html

Ride 7.99.68, a bumpy bus of incremental vfs improvements!
 1.61 30-Mar-2017  hannken Locking a layer vnode is racy as it may become reclaimed before
calling the operation on the lower vnode.

Replace vi_lock with a rw_obj and change layered file systems
to share the lock with the lower vnode.

Layered file systems now use genfs_lock()/_unlock/_islocked().

Welcome to 7.99.67
 1.60 27-Jan-2017  hannken Handle v_writecount from layer_open(), layer_close() and layer_revoke()
so lower file system vnodes get marked as open for writing.
 1.59 20-Aug-2016  hannken branches: 1.59.2;
Remove now obsolete operation vcache_remove().

Welcome to 7.99.36
 1.58 25-May-2014  hannken branches: 1.58.4; 1.58.8;
Change layerfs from hashlist to vcache.
Make VI_LOCKSHARE public again.

Ride 6.99.43
 1.57 24-Mar-2014  hannken branches: 1.57.2;
- Make VI_XLOCK, VI_CLEAN and VI_LOCKSHARE private to kern/vfs_*.c.
- Make vwait() static.
- Add vdead_check() to check a vnode for being or becoming dead.

Discussed on tech-kern.

Welcome to 6.99.38
 1.56 12-Mar-2014  hannken Restructure layer_lock() to always lock before testing for dead node.
Use ISSET() to test flags, add assertions.
 1.55 27-Feb-2014  hannken The current implementation of vn_lock() is racy. Modification of
the vnode operations vector for active vnodes is unsafe because it
is not known whether deadfs or the original file system will be
called.

- Pass down LK_RETRY to the lock operation (hint for deadfs only).

- Change deadfs lock operation to return ENOENT if LK_RETRY is unset.

- Change all other lock operations to check for dead vnode once
the vnode is locked and unlock and return ENOENT in this case.

With these changes in place vnode lock operations will never succeed
after vclean() has marked the vnode as VI_XLOCK and before vclean()
has changed the operations vector.

Adresses PR kern/37706 (Forced unmount of file systems is unsafe)

Discussed on tech-kern.

Welcome to 6.99.33
 1.54 07-Feb-2014  hannken Change vnode operation lookup to return the resulting vnode *vpp unlocked.
Change cache_lookup() to return an unlocked vnode.

Discussed on tech-kern@

Welcome to 6.99.31
 1.53 29-Jan-2014  hannken Allow layer_node_create() with unlocked lower node and change
layer_bypass() to enter nodes from creation operations unlocked.
 1.52 23-Jan-2014  hannken Change vnode operations create, mknod, mkdir and symlink to return
the resulting vnode *vpp unlocked.

Discussed on tech-kern@

Welcome to 6.99.30
 1.51 10-Oct-2012  dholland branches: 1.51.2;
In layer_lookup(), clear *vpp before returning EROFS, as otherwise a
stale value can be returned and this causes a diagnostic panic in
namei.

In relookup(), clear *vpp before calling VOP_LOOKUP, as is done in
lookup_once(), as an additional precautionary measure.

(in theory both of these fixes are not required together)

Should fix PR 47040.
 1.50 11-Jul-2011  hannken branches: 1.50.2; 1.50.8; 1.50.12;
Layer_fsync(): when syncing a device node call spec_fsync() to clean the
layer node before descending to the lower file system.

Adresses PR kern/38762 panic: vwakeup: neg numoutput
 1.49 11-Jul-2011  hannken Change VOP_BWRITE() to take a vnode as its first argument like all other
VOPs do. Layered file systems no longer have to modify bp->b_vp and run
into trouble when an async VOP_BWRITE() uses the wrong vnode.

- change all occurences of VOP_BWRITE(bp) to VOP_BWRITE(bp->b_vp, bp).
- remove layer_bwrite().
- welcome to 5.99.55

Adresses PR kern/38762 panic: vwakeup: neg numoutput

No objections from tech-kern@.
 1.48 12-Jun-2011  rmind Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.
 1.47 03-Apr-2011  rmind branches: 1.47.2;
- Use offsetof() in VOPARG_OFFSETOF() instead of re-implementing it.
- Remove VDESC_NOMAP_VPP and VDESC_VPP_WILLRELE.
- Remove VRELEL_NOINACTIVE and VRELEL_ONHEAD.
 1.46 13-Jan-2011  hannken branches: 1.46.2;
Layer_revoke(): change previous to always take an extra reference on the
lower vnode before passing down the VOP_REVOKE(). This way VOP_REVOKE()
on a layered file system always inactivates and closes the lower vnode.

Should finally fix PR kern/43456.
 1.45 10-Jan-2011  hannken Add layer_revoke() that adjusts the lower vnode use count to be at least as
high as the upper vnode count before passing down the VOP_REVOKE().

This way vclean() check for active (vp->v_usecount > 1) vnodes gets it right.

Should fix PR kern/43456.
 1.44 02-Jan-2011  hannken layer_inactive: With specnodes introduced during vmlocking2
it is safe to cache device nodes.

Tested with nullfs only as unionfs with device nodes panics.
 1.43 02-Jul-2010  hannken LK_INTERLOCK is no longer a valid flag for VOP_LOCK(). This makes
layer_*lock*() obsolete. Remove them and handle lock operations
with the generic bypass function.

Ride 5.99.34.
 1.42 02-Jul-2010  rmind Slightly clean-up layerfs and nullfs: update the big description more to
the reality (remove duplicate one in nullfs, merge some differences from
it), KNF, improve and update some comments, add few KASSERT()s, remove
unused declarations, avoid double inclusion of headers, misc.

No functional changes.
 1.41 24-Jun-2010  hannken Clean up vnode lock operations pass 2:

VOP_UNLOCK(vp, flags) -> VOP_UNLOCK(vp): Remove the unneeded flags argument.

Welcome to 5.99.32.

Discussed on tech-kern.
 1.40 06-Jun-2010  hannken Change layered file systems to always pass the locking VOP's down to the
leaf file system. Remove now unused member v_vnlock from struct vnode.
Welcome to 5.99.30

Discussed on tech-kern.
 1.39 08-Jan-2010  pooka branches: 1.39.2; 1.39.4;
The VATTR_NULL/VREF/VHOLD/HOLDRELE() macros lost their will to live
years ago when the kernel was modified to not alter ABI based on
DIAGNOSTIC, and now just call the respective function interfaces
(in lowercase). Plenty of mix'n match upper/lowercase has creeped
into the tree since then. Nuke the macros and convert all callsites
to lowercase.

no functional change
 1.38 14-Mar-2009  dsl ANSIfy another 1261 function definitions.
The only ones left in sys are beyond by sed script!
(or in sys/dist or sys/external)
Mostly they have function pointer parameters.
 1.37 14-Feb-2009  plunky consistency checks made inside #ifdef SAFETY should really
be #ifdef DIAGNOSTIC
 1.36 03-Jan-2009  dholland branches: 1.36.2;
Clarify a comment
 1.35 30-Jan-2008  ad branches: 1.35.6; 1.35.10; 1.35.18; 1.35.20;
Replace struct lock on vnodes with a simpler lock object built on
krwlock_t. This is a step towards removing lockmgr and simplifying
vnode locking. Discussed on tech-kern.
 1.34 02-Jan-2008  ad Merge vmlocking2 to head.
 1.33 22-Dec-2007  dyoung Bug fix: at the top of layer_bypass(), save a pointer to the mount
point for re-use at the bottom, instead of trying to re-read the
mount point from a potentially vrele()'d vnode.
 1.32 10-Oct-2007  ad branches: 1.32.4; 1.32.6; 1.32.10;
Merge from vmlocking:

- Split vnode::v_flag into three fields, depending on field locking.
- simple_lock -> kmutex in a few places.
- Fix some simple locking problems.
 1.31 16-Apr-2007  enami branches: 1.31.6; 1.31.8; 1.31.10;
Don't expand RCS id of ancestor file. The id itself is actually copied
from null_vnops.c since the log message of rev. 1.1 implies the copy.
 1.30 16-Apr-2007  chs define a pager flag PGO_RECLAIM, similar to FSYNC_RECLAIM, and use it
to skip unnecessary flushing when layered file system vnodes are recycled.
this also prevents a deadlock with the dodgy LFS putpages routine.
fixes the non-LFS part of PR 36150.
 1.29 09-Dec-2006  chs branches: 1.29.2; 1.29.6; 1.29.8;
a smorgasbord of improvements to vnode locking and path lookup:
- LOCKPARENT is no longer relevant for lookup(), relookup() or VOP_LOOKUP().
these now always return the parent vnode locked. namei() works as before.
lookup() and various other paths no longer acquire vnode locks in the
wrong order via vrele(). fixes PR 32535.
as a nice side effect, path lookup is also up to 25% faster.
- the above allows us to get rid of PDIRUNLOCK.
- also get rid of WANTPARENT (just use LOCKPARENT and unlock it).
- remove an assumption in layer_node_find() that all file systems implement
a recursive VOP_LOCK() (unionfs doesn't).
- require that all file systems supply vfs_vptofh and vfs_fhtovp routines.
fill in eopnotsupp() for file systems that don't support being exported
and remove the checks for NULL. (layerfs calls these without checking.)
- in union_lookup1(), don't change refcounts in the ISDOTDOT case, just
adjust which vnode is locked. fixes PR 33374.
- apply fixes for ufs_rename() from ufs_vnops.c rev. 1.61 to ext2fs_rename().
 1.28 25-Nov-2006  elad branches: 1.28.2;
Part of PR/33280: Christian Ehrhardt: If LK_INTERLOCK is set
vp->v_interlock may be unlocked twice: Once explicitly and a second time
implicilty by lockmgr. LK_INTERLOCK is cleared from the variable flags but
not from ap->a_flags which is used with lockmgr. This is not so much of a
problem because there seems to be no call site that actually uses
LK_INTERLOCK with layer_unlock or VOP_UNLOCK.

okay martin@
 1.27 14-May-2006  elad branches: 1.27.8; 1.27.10;
integrate kauth.
 1.26 11-Dec-2005  christos branches: 1.26.4; 1.26.6; 1.26.8; 1.26.10; 1.26.12;
merge ktrace-lwp.
 1.25 30-Aug-2005  xtraeme Remove __P()
 1.24 26-Feb-2005  perry branches: 1.24.4;
nuke trailing whitespace
 1.23 30-Jun-2004  hannken branches: 1.23.4; 1.23.6;
Do LAYERFS_REMOVED for vop_rmdir.

Reviewed by: Bill Studenmund <wrstuden@netbsd.org>
 1.22 19-Jun-2004  yamt layer_islocked: check a status of the lower vnode as well.
 1.21 16-Jun-2004  wrstuden Make sure we actually locked the parent vnode before we clear
PDIRUNLOCK. The whole reason we have the flag is to note (rare)
cases where we are supposed to have the parent directory locked
but don't. Permits error handling code to know what to do with
the parrent vnode (vrele() vs vput()).
 1.20 16-Jun-2004  yamt - eliminate gratuitous differences between umap_bypass() and layer_bypass().
- fix a typo in a comment.
no functional changes are intended.
 1.19 16-Jun-2004  yamt missing error recover from layer_node_create failure.
 1.18 11-Jun-2004  yamt umap_lookup/layer_lookup: NULL out *ap->a_vpp after calling
underlying filesystem because some caller including lookup()
assume that *vpp is NULL on error.
 1.17 07-Jun-2004  yamt do a LAYERFS_REMOVED hack for vop_rename as well.
 1.16 28-May-2004  wrstuden Since VOP_UPCALL() has been a long time in coming, add this partial
fix for layered-file-removal. It will work for the case of accessing
and deleting a file through the layered file system. Accessing via
the layer and deleting on the underlying still won't work, nor will
accessing via complicated structures (like two umap layers over a
given file systems).

We still need VOP_UPCALL(), but this is better than things were before.

This patch has been discussed off & on for a while. This incarnation
was tested by hannken at netbsd dot org.
 1.15 21-Apr-2004  christos Replace the statfs() family of system calls with statvfs().
Retain binary compatibility.
 1.14 25-Jan-2004  hannken branches: 1.14.2;
Make VOP_STRATEGY(bp) a real VOP as discussed on tech-kern.

VOP_STRATEGY(bp) is replaced by one of two new functions:

- VOP_STRATEGY(vp, bp) Call the strategy routine of vp for bp.
- DEV_STRATEGY(bp) Call the d_strategy routine of bp->b_dev for bp.

DEV_STRATEGY(bp) is used only for block-to-block device situations.
 1.13 30-Nov-2003  wiz Typo fixes in comments from jmc@openbsd.
 1.12 17-Nov-2003  wiz Various typo fixes from Jonathon Gray via jmc@openbsd.
 1.11 07-Aug-2003  agc Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.
 1.10 06-Dec-2001  chs branches: 1.10.16;
add VOP_GETPAGES and VOP_PUTPAGES methods for layered filesystems.
drop the interlock on the upper layer, acquire the interlock on the
lower layer.
 1.9 15-Nov-2001  lukem don't need <sys/types.h> when including <sys/param.h>
 1.8 10-Nov-2001  lukem add RCSIDs
 1.7 24-Jul-2001  assar branches: 1.7.4;
change vop_symlink and vop_mknod to return vpp (the created node)
refed, so that the caller can actually use it. update callers and
file systems that implement these vnode operations
 1.6 07-Jun-2001  wiz branches: 1.6.2;
Typos in comments (misc/13133 by Michael K. Sanders)
 1.5 21-Dec-2000  enami branches: 1.5.2;
Don't cache a device vnode in a layer node cache once the layer node
is inactivated. Otherwise, the device won't closed.
 1.4 19-Sep-2000  fvdl Adapt for VOP_FSYNC parameter change.
 1.3 30-Mar-2000  augustss branches: 1.3.4;
Register, begone!
 1.2 13-Mar-2000  soren Fix doubled 'the's in comments.
 1.1 08-Jul-1999  wrstuden branches: 1.1.2; 1.1.4;
Introduce layer library in genfs. This set of files abstracts most of
the functionality of nullfs. The latter is now just a mount & unmount
routine, and a few tables. umapfs borrow most of this infrastructure.

Both fs's are now nfs-exportable.

All layered fs's share a common format to private mount & private
vnode structs (which a particular fs can extend).

Also add genfs_noerr_rele(), a vnode op which will vrele/vput
operand vnodes appropriately.
 1.1.4.2 05-Jan-2001  bouyer Sync with HEAD
 1.1.4.1 20-Nov-2000  bouyer Update thorpej_scsipi to -current as of a month ago
 1.1.2.2 02-Aug-1999  thorpej Update from trunk.
 1.1.2.1 08-Jul-1999  thorpej file layer_vnops.c was added on branch chs-ubc2 on 1999-08-02 22:27:34 +0000
 1.3.4.1 14-Dec-2000  he Pull up revision 1.4 (requested by fvdl):
Improve NFS performance, possibly with as much as 100% in
throughput. Please note: this implies a kernel interface change,
VOP_FSYNC gains two arguments.
 1.5.2.4 08-Jan-2002  nathanw Catch up to -current.
 1.5.2.3 14-Nov-2001  nathanw Catch up to -current.
 1.5.2.2 24-Aug-2001  nathanw Catch up with -current.
 1.5.2.1 21-Jun-2001  nathanw Catch up to -current.
 1.6.2.2 10-Jan-2002  thorpej Sync kqueue branch with -current.
 1.6.2.1 03-Aug-2001  lukem update to -current
 1.7.4.1 12-Nov-2001  thorpej Sync the thorpej-mips-cache branch with -current.
 1.10.16.6 10-Nov-2005  skrll Sync with HEAD. Here we go again...
 1.10.16.5 04-Mar-2005  skrll Sync with HEAD.

Hi Perry!
 1.10.16.4 27-Oct-2004  skrll Fix various comments that describe the argument structures
 1.10.16.3 21-Sep-2004  skrll Fix the sync with head I botched.
 1.10.16.2 18-Sep-2004  skrll Sync with HEAD.
 1.10.16.1 03-Aug-2004  skrll Sync with HEAD
 1.14.2.4 02-Jul-2004  he Pull up revision 1.23 (requested by hannken in ticket #575):
Do LAYERFS_REMOVED for vop_rmdir.
 1.14.2.3 21-Jun-2004  tron Pull up revision 1.18 (requested by yamt in ticket #514):
umap_lookup/layer_lookup: NULL out *ap->a_vpp after calling
underlying filesystem because some caller including lookup()
assume that *vpp is NULL on error.
 1.14.2.2 21-Jun-2004  tron Pull up revision 1.17 (requested by yamt in ticket #512):
do a LAYERFS_REMOVED hack for vop_rename as well.
 1.14.2.1 30-May-2004  tron Pull up revision 1.16 (requested by wrstuden in ticket #424):
Since VOP_UPCALL() has been a long time in coming, add this partial
fix for layered-file-removal. It will work for the case of accessing
and deleting a file through the layered file system. Accessing via
the layer and deleting on the underlying still won't work, nor will
accessing via complicated structures (like two umap layers over a
given file systems).
We still need VOP_UPCALL(), but this is better than things were before.
This patch has been discussed off & on for a while. This incarnation
was tested by hannken at netbsd dot org.
 1.23.6.1 19-Mar-2005  yamt sync with head. xen and whitespace. xen part is not finished.
 1.23.4.1 29-Apr-2005  kent sync with -current
 1.24.4.6 04-Feb-2008  yamt sync with head.
 1.24.4.5 21-Jan-2008  yamt sync with head
 1.24.4.4 27-Oct-2007  yamt sync with head.
 1.24.4.3 03-Sep-2007  yamt sync with head.
 1.24.4.2 30-Dec-2006  yamt sync with head.
 1.24.4.1 21-Jun-2006  yamt sync with head.
 1.26.12.1 24-May-2006  tron Merge 2006-05-24 NetBSD-current into the "peter-altq" branch.
 1.26.10.2 06-May-2006  christos - Move kauth_cred_t declaration to <sys/types.h>
- Cleanup struct ucred; forward declarations that are unused.
- Don't include <sys/kauth.h> in any header, but include it in the c files
that need it.

Approved by core.
 1.26.10.1 08-Mar-2006  elad Adapt to kernel authorization KPI.
 1.26.8.1 24-May-2006  yamt sync with head.
 1.26.6.1 01-Jun-2006  kardel Sync with head.
 1.26.4.1 09-Sep-2006  rpaulo sync with head
 1.27.10.1 10-Dec-2006  yamt sync with head.
 1.27.8.1 12-Jan-2007  ad Sync with head.
 1.28.2.3 14-Nov-2012  riz Pull up following revision(s) (requested by dholland in ticket #1466):
sys/kern/vfs_lookup.c: revision 1.195
sys/miscfs/genfs/layer_vnops.c: revision 1.51
In layer_lookup(), clear *vpp before returning EROFS, as otherwise a
stale value can be returned and this causes a diagnostic panic in
namei.
In relookup(), clear *vpp before calling VOP_LOOKUP, as is done in
lookup_once(), as an additional precautionary measure.
(in theory both of these fixes are not required together)
Should fix PR 47040.
 1.28.2.2 16-Apr-2007  bouyer branches: 1.28.2.2.6;
Pull up following revision(s) (requested by chs in ticket #577):
sys/kern/vfs_subr.c: revision 1.287
sys/fs/union/union_vnops.c: revision 1.20
sys/miscfs/genfs/layer_vnops.c: revision 1.30
sys/uvm/uvm_pager.h: revision 1.35
define a pager flag PGO_RECLAIM, similar to FSYNC_RECLAIM, and use it
to skip unnecessary flushing when layered file system vnodes are recycled.
this also prevents a deadlock with the dodgy LFS putpages routine.
fixes the non-LFS part of PR 36150.
 1.28.2.1 17-Feb-2007  tron Apply patch (requested by chs in ticket #422):
- Fix various deadlock problems with nullfs and unionfs.
- Speed up path lookups by upto 25%.
 1.28.2.2.6.1 14-Nov-2012  riz Pull up following revision(s) (requested by dholland in ticket #1466):
sys/kern/vfs_lookup.c: revision 1.195
sys/miscfs/genfs/layer_vnops.c: revision 1.51
In layer_lookup(), clear *vpp before returning EROFS, as otherwise a
stale value can be returned and this causes a diagnostic panic in
namei.
In relookup(), clear *vpp before calling VOP_LOOKUP, as is done in
lookup_once(), as an additional precautionary measure.
(in theory both of these fixes are not required together)
Should fix PR 47040.
 1.29.8.1 11-Jul-2007  mjf Sync with head.
 1.29.6.4 16-Sep-2007  ad Checkpoint work in progress on the vnode lifecycle and reference counting
stuff. This makes it work properly without kernel_lock and fixes a few
quite old bugs. See vfs_subr.c 1.283.2.17 for details.
 1.29.6.3 15-Jul-2007  ad Sync with head.
 1.29.6.2 08-Jun-2007  ad Sync with head.
 1.29.6.1 13-Mar-2007  ad Pull in the initial set of changes for the vmlocking branch.
 1.29.2.1 07-May-2007  yamt sync with head.
 1.31.10.1 14-Oct-2007  yamt sync with head.
 1.31.8.3 23-Mar-2008  matt sync with HEAD
 1.31.8.2 09-Jan-2008  matt sync with HEAD
 1.31.8.1 06-Nov-2007  matt sync with HEAD
 1.31.6.1 26-Oct-2007  joerg Sync with HEAD.

Follow the merge of pmap.c on i386 and amd64 and move
pmap_init_tmp_pgtbl into arch/x86/x86/pmap.c. Modify the ACPI wakeup
code to restore CR4 before jumping back into kernel space as the large
page option might cover that.
 1.32.10.1 02-Jan-2008  bouyer Sync with HEAD
 1.32.6.5 26-Dec-2007  ad Sync with head.
 1.32.6.4 12-Dec-2007  ad Correct a comment.
 1.32.6.3 10-Dec-2007  ad - Don't drain the vnode lock in vclean(); reference counting and XLOCK
should be enough.
- LK_SETRECURSE is gone.
 1.32.6.2 06-Dec-2007  ad - layer_node_find: fix a race.
- Use kmem_alloc/free.
 1.32.6.1 04-Dec-2007  ad Pull the vmlocking changes into a new branch.
 1.32.4.1 18-Feb-2008  mjf Sync with HEAD.
 1.35.20.1 06-Nov-2012  riz Pull up following revision(s) (requested by dholland in ticket #1814):
sys/kern/vfs_lookup.c: revision 1.195
sys/miscfs/genfs/layer_vnops.c: revision 1.51
In layer_lookup(), clear *vpp before returning EROFS, as otherwise a
stale value can be returned and this causes a diagnostic panic in
namei.
In relookup(), clear *vpp before calling VOP_LOOKUP, as is done in
lookup_once(), as an additional precautionary measure.
(in theory both of these fixes are not required together)
Should fix PR 47040.
 1.35.18.3 28-Apr-2009  skrll Sync with HEAD.
 1.35.18.2 03-Mar-2009  skrll Sync with HEAD.
 1.35.18.1 19-Jan-2009  skrll Sync with HEAD.
 1.35.10.3 11-Aug-2010  yamt sync with head.
 1.35.10.2 11-Mar-2010  yamt sync with head
 1.35.10.1 04-May-2009  yamt sync with head.
 1.35.6.1 17-Jan-2009  mjf Sync with HEAD.
 1.36.2.1 13-May-2009  jym Sync with HEAD.

Commit is split, to avoid a "too many arguments" protocol error.
 1.39.4.5 19-May-2011  rmind Implement sharing of vnode_t::v_interlock amongst vnodes:
- Lock is shared amongst UVM objects using uvm_obj_setlock() or getnewvnode().
- Adjust vnode cache to handle unsharing, add VI_LOCKSHARE flag for that.
- Use sharing in tmpfs and layerfs for underlying object.
- Simplify locking in ubc_fault().
- Sprinkle some asserts.

Discussed with ad@.
 1.39.4.4 21-Apr-2011  rmind sync with head
 1.39.4.3 05-Mar-2011  rmind sync with head
 1.39.4.2 03-Jul-2010  rmind sync with head
 1.39.4.1 16-Mar-2010  rmind Change struct uvm_object::vmobjlock to be dynamically allocated with
mutex_obj_alloc(). It allows us to share the locks among UVM objects.
 1.39.2.1 17-Aug-2010  uebayasi Sync with HEAD.
 1.46.2.1 06-Jun-2011  jruoho Sync with HEAD.
 1.47.2.1 23-Jun-2011  cherry Catchup with rmind-uvmplock merge.
 1.50.12.3 03-Dec-2017  jdolecek update from HEAD
 1.50.12.2 20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.50.12.1 20-Nov-2012  tls Resync to 2012-11-19 00:00:00 UTC
 1.50.8.1 18-Nov-2012  msaitoh Pull up following revision(s) (requested by dholland in ticket #664):
sys/kern/vfs_lookup.c: revision 1.195
sys/miscfs/genfs/layer_vnops.c: revision 1.51
In layer_lookup(), clear *vpp before returning EROFS, as otherwise a
stale value can be returned and this causes a diagnostic panic in
namei.
In relookup(), clear *vpp before calling VOP_LOOKUP, as is done in
lookup_once(), as an additional precautionary measure.
(in theory both of these fixes are not required together)
Should fix PR 47040.
 1.50.2.2 22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.50.2.1 30-Oct-2012  yamt sync with head
 1.51.2.1 18-May-2014  rmind sync with head
 1.57.2.1 10-Aug-2014  tls Rebase.
 1.58.8.2 26-Apr-2017  pgoyette Sync with HEAD
 1.58.8.1 20-Mar-2017  pgoyette Sync with HEAD
 1.58.4.3 28-Aug-2017  skrll Sync with HEAD
 1.58.4.2 05-Feb-2017  skrll Sync with HEAD
 1.58.4.1 05-Oct-2016  skrll Sync with HEAD
 1.59.2.1 21-Apr-2017  bouyer Sync with HEAD
 1.63.2.1 11-May-2017  pgoyette Sync with HEAD
 1.66.2.1 04-Jun-2017  bouyer pullup the following revisions, requested by hannken in ticket #2:
src/share/man/man9/fstrans.9 1.25
src/sys/kern/vfs_mount.c 1.66
src/sys/kern/vfs_subr.c 1.468
src/sys/kern/vfs_trans.c 1.46
src/sys/kern/vfs_vnode.c 1.94, 1.95, 1.96
src/sys/kern/vnode_if.c 1.105, 1.106
src/sys/kern/vnode_if.sh 1.65, 1.66
src/sys/kern/vnode_if.src 1.76
src/sys/miscfs/genfs/genfs_io.c 1.69
src/sys/miscfs/genfs/genfs_vnops.c 1.196, 1.197
src/sys/miscfs/genfs/layer_extern.h 1.40
src/sys/miscfs/genfs/layer_vfsops.c 1.51
src/sys/miscfs/genfs/layer_vnops.c 1.67
src/sys/miscfs/nullfs/null_vnops.c 1.42
src/sys/miscfs/overlay/overlay_vnops.c 1.24
src/sys/miscfs/umapfs/umap_vnops.c 1.60
src/sys/rump/include/rump/rumpvnode_if.h 1.29, 1.30
src/sys/rump/librump/rumpkern/emul.c 1.182
src/sys/rump/librump/rumpvfs/rumpvnode_if.c 1.29, 1.30
src/sys/sys/fstrans.h 1.11
src/sys/sys/vnode.h 1.278
src/sys/sys/vnode_if.h 1.100, 1.101
src/sys/sys/vnode_impl.h 1.14, 1.15
src/sys/ufs/lfs/lfs_pages.c 1.12

Vnode state, lock and fstrans cleanup:
- Rename vnode state "VS_ACTIVE" to "VS_LOADED" and add synthetic
state "VS_ACTIVE" to assert a loaded vnode with usecount > 0.

- Redo FSTRANS in vnode_if.c and use it for VOP_LOCK and VOP_UNLOCK.

- Cleanup the genfs lock operations.

- Make "struct vnode_impl" member "vi_lock" a krwlock_t again.

- Remove the lock type argument from fstrans_start and
fstrans_start_nowait,
remove now unused FSTRANS state "FSTRANS_SUSPENDING".
 1.67.12.2 29-Feb-2020  ad Sync with head.
 1.67.12.1 19-Jan-2020  ad Set IMNT_SHRLOOKUP and use it for the in-cache case. Need to check what
more can be done with tmpfs though, it can probably do the whole lookup.
 1.67.6.2 21-Apr-2020  martin Sync with HEAD
 1.67.6.1 08-Apr-2020  martin Merge changes from current as of 20200406
 1.69.2.1 20-Apr-2020  bouyer Sync with HEAD

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