diff options
| -rw-r--r-- | share/man/man9/Makefile | 7 | ||||
| -rw-r--r-- | share/man/man9/vfs_busy.9 | 80 |
2 files changed, 84 insertions, 3 deletions
diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile index 715159021f9..3aa8112c621 100644 --- a/share/man/man9/Makefile +++ b/share/man/man9/Makefile @@ -1,4 +1,4 @@ -# $OpenBSD: Makefile,v 1.115 2006/06/24 14:14:30 deraadt Exp $ +# $OpenBSD: Makefile,v 1.116 2006/07/02 11:54:10 sturm Exp $ # $NetBSD: Makefile,v 1.4 1996/01/09 03:23:01 thorpej Exp $ # Makefile for section 9 (kernel function and variable) manual pages. @@ -23,8 +23,8 @@ MAN= altq.9 audio.9 autoconf.9 boot.9 buffercache.9 bus_dma.9 bus_space.9 \ sensor_add.9 \ shutdownhook_establish.9 sleep.9 spl.9 startuphook_establish.9 \ style.9 syscall.9 systrace.9 sysctl_int.9 \ - tc_init.9 time.9 timeout.9 tvtohz.9 uiomove.9 uvm.9 vfs.9 vfs_cache.9 \ - vaccess.9 vclean.9 vcount.9 vdevgone.9 vfinddev.9 vflush.9 \ + tc_init.9 time.9 timeout.9 tvtohz.9 uiomove.9 uvm.9 vfs.9 vfs_busy.9 \ + vfs_cache.9 vaccess.9 vclean.9 vcount.9 vdevgone.9 vfinddev.9 vflush.9 \ vflushbuf.9 vget.9 vgone.9 vhold.9 vinvalbuf.9 vnode.9 vnsubr.9 \ VOP_GETATTR.9 VOP_LOOKUP.9 vput.9 vrecycle.9 vref.9 vrele.9 \ vwaitforio.9 vwakeup.9 wdog_register.9 @@ -298,6 +298,7 @@ MLINKS+=kern.9 imax.9 kern.9 imin.9 kern.9 lmax.9 kern.9 lmin.9 \ kern.9 strcmp.9 kern.9 strncmp.9 kern.9 strncasecmp.9 \ kern.9 srandom.9 kern.9 getsn.9 +MLINKS+=vfs_busy.9 vfs_isbusy.9 vfs_busy.9 vfs_unbusy.9 MLINKS+=vfs_cache.9 cache_enter.9 vfs_cache.9 cache_lookup.9 \ vfs_cache.9 cache_purge.9 vfs_cache.9 cache_purgevfs.9 \ vfs_cache.9 cache_revlookup.9 diff --git a/share/man/man9/vfs_busy.9 b/share/man/man9/vfs_busy.9 new file mode 100644 index 00000000000..f9a0aff4382 --- /dev/null +++ b/share/man/man9/vfs_busy.9 @@ -0,0 +1,80 @@ +.\" $OpenBSD: vfs_busy.9,v 1.1 2006/07/02 11:54:10 sturm Exp $ +.\" +.\" Copyright (c) 2006 Nikolay Sturm <sturm@openbsd.org> +.\" +.\" Permission to use, copy, modify, and distribute this software for any +.\" purpose with or without fee is hereby granted, provided that the above +.\" copyright notice and this permission notice appear in all copies. +.\" +.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR +.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF +.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +.\" +.Dd June 17, 2006 +.Dt VFS_BUSY 9 +.Os +.Sh NAME +.Nm vfs_busy , +.Nm vfs_isbusy , +.Nm vfs_unbusy +.Nd VFS locking API +.Sh SYNOPSIS +.In sys/mount.h +.Pp +.Ft int +.Fn vfs_busy "struct mount *mp" "int flags" +.Ft int +.Fn vfs_isbusy "struct mount *mp" +.Ft void +.Fn vfs_unbusy "struct mount *mp" +.Sh DESCRIPTION +The +.Nm vfs_busy +API is used to lock mount points to ensure consistent access. +A read lock can be shared between multiple processes, while a write lock is +exclusive. +Normally a write lock is only acquired when unmounting. +.Pp +The +.Fn vfs_busy +function locks the mount point pointed to by +.Fa mp , +where +.Fa flags +describes the type of lock to acquire and whether or not to wait for a +conflicting lock to be released. +The following flags are available: +.Pp +.Bl -tag -width "VB_NOWAITXX" -offset indent -compact +.It VB_READ +Acquire a read lock. +.It VB_WRITE +Acquire a write lock. +.It VB_NOWAIT +Return immediately; do not wait for the conflicting lock to be released. +.It VB_WAIT +Wait for the conflicting lock to be released. +.El +.Pp +If a conflicting lock was encountered, +.Fn vfs_busy +returns an error. +.Pp +The +.Fn vfs_isbusy +function checks whether the given mount point is locked. +.Pp +.Fn vfs_unbusy +unlocks the given mount point. +.Pp +The +.Nm vfs_busy +API is implemented in the file +.Pa sys/kern/vfs_subr.c . +.Sh SEE ALSO +.Xr rwlock 9 , +.Xr vfs 9 |