NetBSD/share/man/man9/vfssubr.9

217 lines
6.5 KiB
Groff

.\" $NetBSD: vfssubr.9,v 1.20 2010/12/02 12:54:13 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 May 9, 2009
.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
.Nd high-level interface to kernel file system interface
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.In 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" "int flags" "struct simplelock *interlkp"
.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"
.Sh DESCRIPTION
The high-level functions described in this page are the interface to
the kernel file system interface (VFS).
.Sh FUNCTIONS
.Bl -tag -width compact
.It 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-\*[Gt]mnt_stat.f_fsidx .
.It Fn vfs_getvfs "fsid"
Lookup a mount point with the file system identifier
.Fa fsid .
.It 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.
.It Fn vfs_setpublicfs "mp" "nep" "argp"
Set the publicly exported file system specified by the mount structure
.Fa mp .
.It Fn vfs_mountedon "vp"
Check to see if a file system is mounted on a block device specified
by the vnode
.Fa vp .
.It Fn vfs_mountroot "void"
Mount the root file system.
.It Fn vfs_unmountall "l"
Unmount all file systems.
.It Fn vfs_busy "mp" "flags" "interlkp"
Mark the mount point specified by
.Fa mp
as busy.
This function is used to synchronize access and to delay unmounting.
The interlock specified by argument
.Fa interlkp
is not released on failure.
.It Fn vfs_unbusy "mp"
Free the busy file system specified by the mount structure
.Fa mp .
.It 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, mark the mount structure as busy and return its address.
Otherwise, return
.Dv NULL .
.It 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 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.
.It Fn vfs_shutdown
Sync and unmount all file systems before shutting down.
Invoked by
.Xr cpu_reboot 9 .
.It Fn vfs_attach "vfs"
Establish file system
.Fa vfs
and initialise it.
.It Fn vfs_detach "vfs"
Remove file system
.Fa vfs
from the kernel.
.It Fn vfs_reinit "void"
Reinitialises all file systems within the kernel through file
system-specific vfs operation (see
.Xr vfsops 9 ) .
.It 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.
.It 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.
.It Fn vfs_resume "mp"
Request a mounted file system to resume operations.
.El
.Sh CODE REFERENCES
The vfs interface functions are implemented within the files
.Pa sys/kern/vfs_subr.c
and
.Pa 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