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.

Define layerfs as an attribute.

Define filesystem attributes with vfs dependency.

branches: 1.3.120;
merge ktrace-lwp.

nuke trailing whitespace

branches: 1.1.6; 1.1.8; 1.1.14; 1.1.22; 1.1.24;
Cleanup how file system configuration information is declared, grouping
related information together, with the file system code itself.

This is just low-hanging fruit -- more to come.

Field "layerm_vfs" of "struct layer_mount" got superseded by "mnt_lower".
Adapt consumers and remove the now unused field.

Ride 7.99.68

branches: 1.19.18; 1.19.36; 1.19.40; 1.19.44;
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.

branches: 1.18.16; 1.18.18;
Create sysctl entries during module initialisation and destroy them
appropriately.

Many of these file systems are now ready for modularisation.

branches: 1.17.70; 1.17.74; 1.17.76; 1.17.78;
merge ktrace-lwp.

Remove __P()

branches: 1.15.12;
Tweak sysctl setup functions (the macros, actually) for use in lkms,
and tweak lkminit_*.c (where applicable) to call them, and to call
sysctl_teardown() when being unloaded.

This consists of (1) making setup functions not be static when being
compiled as lkms (change to sys/sysctl.h), (2) making prototypes
visible for the various setup functions in header files (changes to
various header files), and (3) making simple "load" and "unload"
functions in the actual lkminit stuff.

linux_sysctl.c also needs its root exposed (ie, made not static) for
this (when built as an lkm).

branches: 1.14.2;
Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.13.16;
Wrap long line and remove name of argument from function prototype.

branches: 1.12.2; 1.12.6;
Typos and grammer fixes in comments (misc/13133 by Michael K. Sanders)

branches: 1.11.6;
Fix doubled 'the's in comments.

branches: 1.10.2;
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.

branches: 1.9.12;
Make the vfs ops and vnodeop_opv symbols match the name of the
file-system option used to configure the file system into the kernel.

branches: 1.8.4;
don't try to use __builtin_return_address() on the Alpha. (It's never
worked as far as I can tell, and apparently crashes the kernel when
invoked here.) From Ross Harvey, PR#3471.

Allow the DIAGNOSTIC to compile with old versions of gcc.

Add locking code to avoid deadlocks on vnode reclaim, which means the
addition of null_lookup, null_lock, null_unlock, null_islocked.

miscfs prototype changes

KERNEL -> _KERNEL

Convert hash tables.

branches: 1.2.2;
New RCS ID's, take two. they're more aesthecially pleasant, and use 'NetBSD'

branches: 1.1.1;
Update to 4.4-Lite fs code, with local changes.

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.

Make message about not loking a vnode in nullfs_create a little quieter -
now only enabled if NULLFS_DIAGNOSTIC and no longer if DEBUG or DIAGNOSTIC.

branches: 1.13.6;
Workaropund fix for PR #5239 from <minoura@kw.netlaputa.ne.jp>:
stop null_node_create() from locking the nullfs mountpoint multiple
times. Avoids a guaranteed, repeatably "locking against myself" panic
during mount of a nullfs filesystem. nullfs filesystems are still as
buggy as ever (e.g., see PR# 4907) but this you at least mount them.

Fix flags mess-up in vget. LK_EXCLUSIVE -> 0 (even indicated in the
comment, d'oh!)

Merge with Lite2 + local changes

add flags arg to hashinit(), to pass to malloc().

PR/4098: Alan Barrett: Fix diagnostic printf formatting.

branches: 1.8.10;
backout previous kprintf changes

printf -> kprintf, sprintf -> ksprintf

Add locking code to avoid deadlocks on vnode reclaim, which means the
addition of null_lookup, null_lock, null_unlock, null_islocked.

miscfs prototype changes

fix device aliasing and lost vnode problems.

Convert hash tables.

branches: 1.2.2;
New RCS ID's, take two. they're more aesthecially pleasant, and use 'NetBSD'

branches: 1.1.1;
Update to 4.4-Lite fs code, with local changes.

Set IMNT_MPSAFE only if the lower layer has it set.

branches: 1.100.2;
Add a helper to set or clear lower mount and use it.
Always add a reference to the lower mount.

Ride 9.99.105

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.

branches: 1.98.2;
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.

Use the module subsystem's ability to process SYSCTL_SETUP() entries to
automate installation of sysctl nodes.

Note that there are still a number of device and pseudo-device modules
that create entries tied to individual device units, rather than to the
module itself. These are not changed.

branches: 1.96.2;
Set IMNT_MPSAFE before creating the vnode for the root of the
filesystem. Otherwise, it won't be created with VV_MPSAFE and require
the kernel_lock.

branches: 1.95.4;
Set "mnt_lower" before the first file system operation on the new file system.

branches: 1.94.4; 1.94.12;
Field "layerm_vfs" of "struct layer_mount" got superseded by "mnt_lower".
Adapt consumers and remove the now unused field.

Ride 7.99.68

Change _fstrans_start() to allocate per lwp info for layered file
systems to get a reference on the mount.

Set mnt_lower on successfull mount only.

Add field "mnt_lower" to "struct mount" to track the file system
a layered file system is mounted on.

Welcome to 7.99.65

Add generic genfs_suspendctl() and use it for all file systems.
Layered file systems need work.

branches: 1.90.2; 1.90.4; 1.90.6;
Do not uselessly include <sys/malloc.h>.

branches: 1.89.2;
Change layerfs from hashlist to vcache.
Make VI_LOCKSHARE public again.

Ride 6.99.43

An (un)privileged user can easily make the kernel dereference a NULL
pointer.

The kernel allows 'data' to be NULL; it's the fs's responsibility to
ensure that it isn't NULL (if the fs actually needs data).

ok christos@

branches: 1.87.2;
Change all vfsops to use C99 designated initializers.

No functional changes intended.

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.

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().

branches: 1.84.2; 1.84.4;
- Replace some malloc(9) uses with kmem(9).
- G/C M_IPMOPTS, M_IPMADDR and M_BWMETER.

branches: 1.83.8; 1.83.12; 1.83.14; 1.83.18; 1.83.20;
Introduce struct pathbuf. This is an abstraction to hold a pathname
and the metadata required to interpret it. Callers of namei must now
create a pathbuf and pass it to NDINIT (instead of a string and a
uio_seg), then destroy the pathbuf after the namei session is
complete.

Update all namei call sites accordingly. Add a pathbuf(9) man page and
update namei(9).

The pathbuf interface also now appears in a couple of related
additional places that were passing string/uio_seg pairs that were
later fed into NDINIT. Update other call sites accordingly.

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.

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.

Change the nullfs module's actual name to "null", to match the name
it's installed under and the name of the filesystem.

Fixes PR kern/43110.

branches: 1.79.2; 1.79.4;
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.)

branches: 1.78.4;
PR kern/40110: null, overlay and umap modules loading -> panic (layerfs symbols not there)

Add a layerfs module.

branches: 1.77.2; 1.77.4; 1.77.6; 1.77.12; 1.77.16;
Set up the sysctl tree correctly when loaded as a file system.

branches: 1.76.2;
Convert file systems to dynamically attach with the new module interface.
Make VFS hooks dynamic while we're here and say farewell to VFS_ATTACH and
VFS_HOOKS_ATTACH linksets.

As a consequence, most of the file systems can now be loaded as new style
modules.

Quick sanity check by ad@.

branches: 1.75.2;
- Convert hashinit() to use kmem_alloc(). The hash tables can be large
and it's better to not have them in kmem_map.
- Convert a couple of minor items along the way to kmem_alloc().
- Fix some memory leaks.

PR kern/38057 ffs makes assuptions about devvp file system
PR kern/33406 softdeps get stuck in endless loop

Introduce VFS_FSYNC() and call it when syncing a block device, if it
has a mounted file system.

branches: 1.73.6; 1.73.8; 1.73.10;
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.

Merge vmlocking2 to head.

branches: 1.71.4;
Remove cn_lwp from struct componentname. curlwp should be used
from on. The NDINIT() macro no longer takes the lwp parameter and
associates the credentials of the calling thread with the namei
structure.

branches: 1.70.2;
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

branches: 1.69.4;
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.

branches: 1.68.2; 1.68.4; 1.68.6; 1.68.8;
* nuke the nameidata parameter from VFS_MOUNT(). Nobody on tech-kern
knew what it was supposed to be used for and wrstuden gave a go-ahead
* while rototilling, convert file systems which went easily to
use VFS_PROTOS() instead of manually prototyping the methods

Use eopnotsupp() instead of vfs_stdsuspendctl() and retire the latter.

branches: 1.66.2;
Make set_statvfs_info() take a parameter for the vfs name instead
of always retrieving it from mp->mnt_op->vfs_name

christos ok

Change the VFS_MOUNT() interface so that the 'data' buffer passed to the
fs code is a kernel buffer, pass though the length of the buffer as well.
Since the length of the userspace buffer isn'it (yet) passed through the mount
system call, add a field to the vfsops structure containing the default length.
Split sys_mount() for calls from compat code.
Ride one of the recent kernel version changes - old fs LKMs will load, but
sys_mount() will reject any attempt to use them.

* allow unmount even if rootvp has a usecount > 1 provided that
MNT_FORCE is given
* decrease cargo cult index by getting rid of commented sections
with mntflushbuf() in them - AFAICT the call was removed from our
kernel over 13 years ago with the 4.4BSDlite import

Remove now obsolete vn_start_write() and vn_finished_write() and
corresponding flags.

Revert softdep_trackbufs() to its state before vn_start_write() was added.

Remove from struct mount now unneeded flags IMNT_SUSPEND* and
members mnt_writeopcountupper, mnt_writeopcountlower and mnt_leaf.

Welcome to 4.99.17

branches: 1.62.2; 1.62.6; 1.62.8;
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).

__unused removal on arguments; approved by core.

- sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386

branches: 1.59.2; 1.59.4;
add missing initializers

branches: 1.58.4; 1.58.8;
merge ktrace-lwp.

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.

Remove __P()

branches: 1.55.2;
- Define a VFS_ATTACH() macro that places a reference to a vfsops structure
into the "vfsops" link set.
- Use VFS_ATTACH() where vfsops are declared for individual file systems.
- In vfsinit(), traverse the "vfsops" link set, rather than vfs_list_initial[].

nuke trailing whitespace

branches: 1.53.2; 1.53.4;
Add the system call and VFS infrastructure for file system extended
attributes.

From FreeBSD.

Keep a pointer to the leaf mount. Needed for write gating where a
file system gets suspended and has layered mounts above it.

Welcome to 2.0G

Reviewed by: Bill Studenmund <wrstuden@netbsd.org>

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.

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>

Sysctl descriptions under vfs subtree

Removed remaining caddr_t casts we do not need in miscfs. Recompiled
kernel and ran for a day or so. There are still some caddr_t types in
the arguments of some calls, I will do those separately (later) as
they touch a lot more of the system.
Approved by christos@NetBSD.org.

Replace the statfs() family of system calls with statvfs().
Retain binary compatibility.

branches: 1.46.2;
Tango on sysctl_createv() and flags. The flags have all been renamed,
and sysctl_createv() now uses more arguments.

Remove pointless comment about layerfs_sysctl()

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.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.42.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Adjust for ktrace/lwp changes.

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

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.

MNT_GETARGS support

Die, qaddr_t, die! - mnt_data in struct mount is already effectively
a void *, so stop pretending otherwise.

branches: 1.36.8;
add RCSIDs

Make the size of null node hash table to desiredvnodes instead of 16.

Call hashdone where appropriate.

Cosmetic changes.

branches: 1.32.2;
add a new VFS op, vfs_reinit, which is called when desiredvnodes is
adjusted via sysctl. file systems that have hash tables which are
sized based on the value of this variable now resize those hash tables
using the new value. the max number of FFS softdeps is also recalculated.

convert various file systems to use the <sys/queue.h> macros for
their hash tables.

branches: 1.31.2;
(*fs_mount): do not get the parent vnode back from namei to just release it

branches: 1.30.2;
Typos and grammer fixes in comments (misc/13133 by Michael K. Sanders)

branches: 1.29.2;
make filesystem vnodeop, specop, fifoop and vnodeopv_* arrays const

Update for hashinit() change.

make vfs_getnewfsid only take one argument and fetch the name of the
filesystem from the supplied mount argument. also make makefstype
take a const parameter. update all the callers.

branches: 1.26.2;
Adapt to last VFS changes - add appropriate vfs_done routine.

Fix doubled 'the's in comments.

branches: 1.24.2; 1.24.8;
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.

branches: 1.23.4;
Modify vfsops to seperate vfs_fhtovp() into two routines. vfs_fhtovp() now
only handles the file handle to vnode conversion, and a new call,
vfs_checkexp(), performs the export verification.

Oops. That extra "*" doesn't need to be there.

In nullfs_mount, we need to check if error before VOP_UNLOCK(vp,0) as
vp is initialized iff error==0 in null_node_create.

bzero->memset, bcopy->memcpy, bcmp->memcmp

Merge with Lite2 + local changes

Place a pointer to an array of our vnodeopv_desc *'s in our vfsops
structure, for use by vfs_attach().

Make the vfs ops and vnodeop_opv symbols match the name of the
file-system option used to configure the file system into the kernel.

PR/4098: Alan Barrett: Fix diagnostic printf formatting.

branches: 1.15.4;
this is nullfs, not lofs

branches: 1.14.6;
Change the second and third args to struct vfsops' (*vfs_mount)() to
'const char *', and 'void *', respectively. The second arg is taken directly
from user arguments, and is const there, so must be const in the prototypes
and functions. The third arg is also taken directly from user arguments.
It doesn't have to be changed, but since it's cleaner to keep the type
the same as the user arg's type, and I'm already making the 'const char *'
change...

backout previous kprintf changes

printf -> kprintf, sprintf -> ksprintf

Add locking code to avoid deadlocks on vnode reclaim, which means the
addition of null_lookup, null_lock, null_unlock, null_islocked.

miscfs prototype changes

don't assume the f_fsnamelen is nul-truncated or longer than MFSNAMELEN

copy*str() should use size_t.

use u_long for copyin*

return EOPNOTSUPP from fhtovp and vptofh functions; doing otherwise
correctly is not possible.

Clean up the code to frob mnt_stat a (tiny) bit.

Call foo_statfs() from a common place when mounting.

stat the file system at mount time, for `df -n', et al.

branches: 1.2.2;
New RCS ID's, take two. they're more aesthecially pleasant, and use 'NetBSD'

branches: 1.1.1;
Update to 4.4-Lite fs code, with local changes.

Add ACL support for FFS. From FreeBSD.

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.

branches: 1.41.6;
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

Handle v_writecount from layer_open(), layer_close() and layer_revoke()
so lower file system vnodes get marked as open for writing.

branches: 1.39.6; 1.39.10; 1.39.14;
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

branches: 1.38.2; 1.38.12; 1.38.16;
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@.

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.

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.

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.

branches: 1.34.74; 1.34.96; 1.34.98;
merge ktrace-lwp.

Remove __P()

branches: 1.32.4;
nuke trailing whitespace

branches: 1.31.4; 1.31.6;
Do LAYERFS_REMOVED for vop_rmdir.

Reviewed by: Bill Studenmund <wrstuden@netbsd.org>

do a LAYERFS_REMOVED hack for vop_rename as well.

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.

branches: 1.28.2;
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.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.26.6;
restore ancestral RCS ID from 4.4BSD-Lite2

add the entry for layer_getpages() to the VOP tables of the
layered file systems that need it.

add VOP_GETPAGES and VOP_PUTPAGES methods for layered filesystems.
drop the interlock on the upper layer, acquire the interlock on the
lower layer.

don't need <sys/types.h> when including <sys/param.h>

add RCSIDs

Fix typo in comment.

branches: 1.20.2; 1.20.6;
Some more corrections by Michael K. Sanders.

Typos and grammer fixes in comments (misc/13133 by Michael K. Sanders)

branches: 1.18.2;
make filesystem vnodeop, specop, fifoop and vnodeopv_* arrays const

Fix doubled 'the's in comments.

branches: 1.16.2;
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.

branches: 1.15.4;
We must handle MNT_NODEV at open time, so add an open op for null and union,
and do proper checks in union_open(). Fix to nullfs from OpenBSD, extended
to umap and union by me.

vinvalbuf, called from vclean, could cause a locking-against-self
deadlock in VOP_FSYNC() if the unreferenced vnode picked for
reclamation happened to be stacked on top of a vnode the process
already had locked. This could happen if the same filesystem was
accessed both through a union mount and directly; it seemed to happen
most frequently when the direct access was through NFS.

Avoid this deadlock by changing vinvalbuf to pass a new FSYNC_RECLAIM
flag bit to VOP_FSYNC() to indicate that a reclaim is in progress and
only a `shallow' fsync is necessary.

Do nothing in *_fsync() in umapfs, nullfs, and unionfs when
FSYNC_RECLAIM is set; the underlying vnodes will shortly be released
in *_reclaim and may be reclaimed (and fsync'ed) later.

Merge with Lite2 + local changes

Make the vfs ops and vnodeop_opv symbols match the name of the
file-system option used to configure the file system into the kernel.

PR/4098: Alan Barrett: Fix diagnostic printf formatting.

branches: 1.10.4;
NULL => 0 (Arne Juul; PR#3629)

backout previous kprintf changes

printf -> kprintf, sprintf -> ksprintf

Add locking code to avoid deadlocks on vnode reclaim, which means the
addition of null_lookup, null_lock, null_unlock, null_islocked.

fix screw-up in the prototyping changes: print pointers with %p, NOT
by casting them to (unsigned int) then printing with %x.

miscfs prototype changes

Convert hash tables.

Fix a null pointer dereference during rename(2).

branches: 1.2.2;
New RCS ID's, take two. they're more aesthecially pleasant, and use 'NetBSD'

branches: 1.1.1;
Update to 4.4-Lite fs code, with local changes.