$NetBSD: vfssubr.9,v 1.28 2017/07/03 21:28:48 wiz Exp $
Copyright (c) 2003, 2005, 2006 The NetBSD Foundation, Inc.
All rights reserved.
This code is derived from software contributed to The NetBSD Foundation
by Gregory McGarry.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
.Dd April 17, 2017 .Dt VFSSUBR 9 .Os .Sh NAME .Nm vfssubr , .Nm vfs_getnewfsid , .Nm vfs_getvfs , .Nm vfs_export , .Nm vfs_showexport , .Nm vfs_export_lookup , .Nm vfs_setpublicfs , .Nm vfs_mountedon , .Nm vfs_mountroot , .Nm vfs_unmountall , .Nm vfs_busy , .Nm vfs_unbusy , .Nm vfs_mountalloc , .Nm vfs_rootmountalloc , .Nm vfs_shutdown , .Nm vfs_attach , .Nm vfs_detach , .Nm vfs_reinit , .Nm vfs_getopsbyname , .Nm vfs_suspend , .Nm vfs_resume , .Nm vfs_vnode_iterator_init , .Nm vfs_vnode_iterator_destroy , .Nm vfs_vnode_iterator_next .Nd high-level interface to kernel file system interface .Sh SYNOPSIS n sys/param.h n sys/mount.h n sys/vnode.h .Ft void .Fn vfs_getnewfsid "struct mount *mp" .Ft struct mount * .Fn vfs_getvfs "fsid_t *fsid" .Ft int .Fn vfs_export_lookup "struct mount *mp" "struct netexport *nep" \ "struct export_args *argp" .Ft int .Fn vfs_setpublicfs "struct mount *mp" "struct netexport *nep" \ "struct export_args *argp" .Ft int .Fn vfs_mountedon "struct vnode *vp" .Ft int .Fn vfs_mountroot "void" .Ft void .Fn vfs_unmountall "struct lwp *l" .Ft int .Fn vfs_busy "struct mount *mp" .Ft void .Fn vfs_unbusy "struct mount *mp" .Ft struct mount * .Fn vfs_mountalloc "struct vfsops *vfs" "struct vnode *vp" .Ft int .Fn vfs_rootmountalloc "char *fstypename" "char *devname" \ "struct mount **mpp" .Ft void .Fn vfs_shutdown "void" .Ft int .Fn vfs_attach "struct vfsops *vfs" .Ft int .Fn vfs_detach "struct vfsops *vfs" .Ft void .Fn vfs_reinit "void" .Ft struct vfsops * .Fn vfs_getopsbyname "const char *name" .Ft int .Fn vfs_suspend "struct mount *mp" "int nowait" .Ft void .Fn vfs_resume "struct mount *mp" .Ft void .Fn vfs_vnode_iterator_init "struct mount *mp" "struct vnode_iterator **vip" .Ft void .Fn vfs_vnode_iterator_destroy "struct vnode_iterator *vi" .Ft struct vnode * .Fn vfs_vnode_iterator_next "struct vnode_iterator *vi" "bool (*selector)(void *context, struct vnode *vpp)" "void *context" .Sh DESCRIPTION The high-level functions described in this page are the interface to the kernel file system interface (VFS). .Sh FUNCTIONS l -tag -width compact t Fn vfs_getnewfsid "mp" Get a new unique file system id type for the file system specified by the mount structure .Fa mp . The file system id type is stored in .Em mp->mnt_stat.f_fsidx . t Fn vfs_getvfs "fsid" Lookup a mount point with the file system identifier .Fa fsid . t Fn vfs_export_lookup "mp" "nep" "argp" Check client permission on the exportable file system specified by the mount structure .Fa mp . The argument .Fa nam is the address of the networked client. This function is used by file system type specific functions to verify that the client can access the file system. t Fn vfs_setpublicfs "mp" "nep" "argp" Set the publicly exported file system specified by the mount structure .Fa mp . t Fn vfs_mountedon "vp" Check to see if a file system is mounted on a block device specified by the vnode .Fa vp . t Fn vfs_mountroot "void" Mount the root file system. t Fn vfs_unmountall "l" Unmount all file systems. t Fn vfs_busy "mp" Mark the mount point specified by .Fa mp as busy and get a reference to it. This function is used to synchronize access and to delay unmounting. The caller must hold a pre-existing reference to the mount. t Fn vfs_unbusy "mp" Undo a .Fn vfs_busy on the mount point specified by .Fa mp . t Fn vfs_mountalloc "vfsops" "vp" Allocate and initialise a mount structure, setting .Em mnt_vnodecovered to .Fa vp and .Em mnt_op to .Fa vfsops . On success return the address of the mount structure. Otherwise, return .Dv NULL . t Fn vfs_rootmountalloc "fstypename" "devname" "mpp" Lookup a file system type specified by the name .Fa fstypename and if found allocate and initialise a mount structure for it. The allocated mount structure is marked as busy and returned in the address specified by .Fa mpp . The device the root file system was mounted from is specified by the argument .Fa devname and is recorded in the new mount structure. t Fn vfs_shutdown Sync and unmount all file systems before shutting down. Invoked by .Xr cpu_reboot 9 . t Fn vfs_attach "vfs" Establish file system .Fa vfs and initialise it. t Fn vfs_detach "vfs" Remove file system .Fa vfs from the kernel. t Fn vfs_reinit "void" Reinitialises all file systems within the kernel through file system-specific vfs operation (see .Xr vfsops 9 ) . t Fn vfs_getopsbyname "name" Given a file system name specified by .Fa name , look up the vfs operations for that file system (see .Xr vfsops 9 ) , or return .Dv NULL if file system isn't present in the kernel. t Fn vfs_suspend "mp" "nowait" Request a mounted file system to suspend all operations. All new operations to the file system are stopped. After all operations in progress have completed, the file system is synced to disk and the function returns. If a file system suspension is currently in progress and .Fa nowait is set .Er EWOULDBLOCK is returned. If the operation is successful, zero is returned, otherwise an appropriate error code is returned. t Fn vfs_resume "mp" Request a mounted file system to resume operations. t Fn vfs_vnode_iterator_init "mp" "vip" Allocate and initialize an iterator .Fa vip over all vnodes attached to mount point .Fa mp . t Fn vfs_vnode_iterator_destroy "vi" Free all resources associated with an iterator .Fa vi . t Fn vfs_vnode_iterator_next "vi" "selector" "context" Return the next vnode from iterator .Fa vi . If the operation is successful the vnode has a reference added to it and it is returned. If the iterator is exhausted the function returns .Dv NULL . If an optional .Fa selector function is provided, then this function is called with the .Fa context provided and the candidate vnode to be returned. If the .Fa selector returns .Dv false , then the vnode is skipped; if it returns .Dv true , the vnode is referenced and then returned. .El .Sh CODE REFERENCES The vfs interface functions are implemented within the files
Copyright (c) 2003, 2005, 2006 The NetBSD Foundation, Inc.
All rights reserved.
This code is derived from software contributed to The NetBSD Foundation
by Gregory McGarry.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
.Dd April 17, 2017 .Dt VFSSUBR 9 .Os .Sh NAME .Nm vfssubr , .Nm vfs_getnewfsid , .Nm vfs_getvfs , .Nm vfs_export , .Nm vfs_showexport , .Nm vfs_export_lookup , .Nm vfs_setpublicfs , .Nm vfs_mountedon , .Nm vfs_mountroot , .Nm vfs_unmountall , .Nm vfs_busy , .Nm vfs_unbusy , .Nm vfs_mountalloc , .Nm vfs_rootmountalloc , .Nm vfs_shutdown , .Nm vfs_attach , .Nm vfs_detach , .Nm vfs_reinit , .Nm vfs_getopsbyname , .Nm vfs_suspend , .Nm vfs_resume , .Nm vfs_vnode_iterator_init , .Nm vfs_vnode_iterator_destroy , .Nm vfs_vnode_iterator_next .Nd high-level interface to kernel file system interface .Sh SYNOPSIS n sys/param.h n sys/mount.h n sys/vnode.h .Ft void .Fn vfs_getnewfsid "struct mount *mp" .Ft struct mount * .Fn vfs_getvfs "fsid_t *fsid" .Ft int .Fn vfs_export_lookup "struct mount *mp" "struct netexport *nep" \ "struct export_args *argp" .Ft int .Fn vfs_setpublicfs "struct mount *mp" "struct netexport *nep" \ "struct export_args *argp" .Ft int .Fn vfs_mountedon "struct vnode *vp" .Ft int .Fn vfs_mountroot "void" .Ft void .Fn vfs_unmountall "struct lwp *l" .Ft int .Fn vfs_busy "struct mount *mp" .Ft void .Fn vfs_unbusy "struct mount *mp" .Ft struct mount * .Fn vfs_mountalloc "struct vfsops *vfs" "struct vnode *vp" .Ft int .Fn vfs_rootmountalloc "char *fstypename" "char *devname" \ "struct mount **mpp" .Ft void .Fn vfs_shutdown "void" .Ft int .Fn vfs_attach "struct vfsops *vfs" .Ft int .Fn vfs_detach "struct vfsops *vfs" .Ft void .Fn vfs_reinit "void" .Ft struct vfsops * .Fn vfs_getopsbyname "const char *name" .Ft int .Fn vfs_suspend "struct mount *mp" "int nowait" .Ft void .Fn vfs_resume "struct mount *mp" .Ft void .Fn vfs_vnode_iterator_init "struct mount *mp" "struct vnode_iterator **vip" .Ft void .Fn vfs_vnode_iterator_destroy "struct vnode_iterator *vi" .Ft struct vnode * .Fn vfs_vnode_iterator_next "struct vnode_iterator *vi" "bool (*selector)(void *context, struct vnode *vpp)" "void *context" .Sh DESCRIPTION The high-level functions described in this page are the interface to the kernel file system interface (VFS). .Sh FUNCTIONS l -tag -width compact t Fn vfs_getnewfsid "mp" Get a new unique file system id type for the file system specified by the mount structure .Fa mp . The file system id type is stored in .Em mp->mnt_stat.f_fsidx . t Fn vfs_getvfs "fsid" Lookup a mount point with the file system identifier .Fa fsid . t Fn vfs_export_lookup "mp" "nep" "argp" Check client permission on the exportable file system specified by the mount structure .Fa mp . The argument .Fa nam is the address of the networked client. This function is used by file system type specific functions to verify that the client can access the file system. t Fn vfs_setpublicfs "mp" "nep" "argp" Set the publicly exported file system specified by the mount structure .Fa mp . t Fn vfs_mountedon "vp" Check to see if a file system is mounted on a block device specified by the vnode .Fa vp . t Fn vfs_mountroot "void" Mount the root file system. t Fn vfs_unmountall "l" Unmount all file systems. t Fn vfs_busy "mp" Mark the mount point specified by .Fa mp as busy and get a reference to it. This function is used to synchronize access and to delay unmounting. The caller must hold a pre-existing reference to the mount. t Fn vfs_unbusy "mp" Undo a .Fn vfs_busy on the mount point specified by .Fa mp . t Fn vfs_mountalloc "vfsops" "vp" Allocate and initialise a mount structure, setting .Em mnt_vnodecovered to .Fa vp and .Em mnt_op to .Fa vfsops . On success return the address of the mount structure. Otherwise, return .Dv NULL . t Fn vfs_rootmountalloc "fstypename" "devname" "mpp" Lookup a file system type specified by the name .Fa fstypename and if found allocate and initialise a mount structure for it. The allocated mount structure is marked as busy and returned in the address specified by .Fa mpp . The device the root file system was mounted from is specified by the argument .Fa devname and is recorded in the new mount structure. t Fn vfs_shutdown Sync and unmount all file systems before shutting down. Invoked by .Xr cpu_reboot 9 . t Fn vfs_attach "vfs" Establish file system .Fa vfs and initialise it. t Fn vfs_detach "vfs" Remove file system .Fa vfs from the kernel. t Fn vfs_reinit "void" Reinitialises all file systems within the kernel through file system-specific vfs operation (see .Xr vfsops 9 ) . t Fn vfs_getopsbyname "name" Given a file system name specified by .Fa name , look up the vfs operations for that file system (see .Xr vfsops 9 ) , or return .Dv NULL if file system isn't present in the kernel. t Fn vfs_suspend "mp" "nowait" Request a mounted file system to suspend all operations. All new operations to the file system are stopped. After all operations in progress have completed, the file system is synced to disk and the function returns. If a file system suspension is currently in progress and .Fa nowait is set .Er EWOULDBLOCK is returned. If the operation is successful, zero is returned, otherwise an appropriate error code is returned. t Fn vfs_resume "mp" Request a mounted file system to resume operations. t Fn vfs_vnode_iterator_init "mp" "vip" Allocate and initialize an iterator .Fa vip over all vnodes attached to mount point .Fa mp . t Fn vfs_vnode_iterator_destroy "vi" Free all resources associated with an iterator .Fa vi . t Fn vfs_vnode_iterator_next "vi" "selector" "context" Return the next vnode from iterator .Fa vi . If the operation is successful the vnode has a reference added to it and it is returned. If the iterator is exhausted the function returns .Dv NULL . If an optional .Fa selector function is provided, then this function is called with the .Fa context provided and the candidate vnode to be returned. If the .Fa selector returns .Dv false , then the vnode is skipped; if it returns .Dv true , the vnode is referenced and then returned. .El .Sh CODE REFERENCES The vfs interface functions are implemented within the files
a sys/kern/vfs_mount.c ,
a sys/kern/vfs_subr.c and
a sys/kern/vfs_init.c . .Sh SEE ALSO .Xr intro 9 , .Xr namei 9 , .Xr vfs 9 , .Xr vfsops 9 , .Xr vnode 9 , .Xr vnodeops 9
Indexes created Sat Sep 20 22:09:52 GMT 2025