VFS_LOCK_GIANT.9 revision 267654
Copyright (c) 2005 Robert N. M. Watson
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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DAMAGE.
$FreeBSD: releng/9.3/share/man/man9/VFS_LOCK_GIANT.9 153988 2006-01-03 14:00:22Z rwatson $
.Dd September 21, 2005 .Dt VFS_LOCK_GIANT 9 .Os .Sh NAME .Nm VFS_LOCK_GIANT , .Nm VFS_UNLOCK_GIANT .Nd "conditionally lock and unlock Giant around entry into VFS" .Sh SYNOPSIS n sys/param.h n sys/mount.h n sys/vnode.h .Ft int .Fn VFS_LOCK_GIANT "struct mount *mp" .Ft void .Fn VFS_UNLOCK_GIANT "int vfslocked" .Sh DESCRIPTION .Fn VFS_LOCK_GIANT will conditionally acquire the .Va Giant lock if the file system referenced by .Fa mp is marked as MPSAFE or not, returning a flag indicating whether .Va Giant was set, which may later be passed to .Fn VFS_UNLOCK_GIANT . The value of .Fa mp will typically be derived from the mount pointer in a .Vt vnode on which a VFS operation will be performed.
Copyright (c) 2005 Robert N. M. Watson
All rights reserved.
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(s), this list of conditions and the following disclaimer as
the first lines of this file unmodified other than the possible
addition of one or more copyright notices.
2. Redistributions in binary form must reproduce the above copyright
notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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.
$FreeBSD: releng/9.3/share/man/man9/VFS_LOCK_GIANT.9 153988 2006-01-03 14:00:22Z rwatson $
.Dd September 21, 2005 .Dt VFS_LOCK_GIANT 9 .Os .Sh NAME .Nm VFS_LOCK_GIANT , .Nm VFS_UNLOCK_GIANT .Nd "conditionally lock and unlock Giant around entry into VFS" .Sh SYNOPSIS n sys/param.h n sys/mount.h n sys/vnode.h .Ft int .Fn VFS_LOCK_GIANT "struct mount *mp" .Ft void .Fn VFS_UNLOCK_GIANT "int vfslocked" .Sh DESCRIPTION .Fn VFS_LOCK_GIANT will conditionally acquire the .Va Giant lock if the file system referenced by .Fa mp is marked as MPSAFE or not, returning a flag indicating whether .Va Giant was set, which may later be passed to .Fn VFS_UNLOCK_GIANT . The value of .Fa mp will typically be derived from the mount pointer in a .Vt vnode on which a VFS operation will be performed.
p .Fn VFS_UNLOCK_GIANT conditionally releases the .Va Giant lock if the passed .Fa vfslocked argument is non-zero. It is expected that the argument will be derived from the return values of .Fn VFS_LOCK_GIANT or .Xr NDHASGIANT 9 . .Sh RETURN VALUES .Fn VFS_LOCK_GIANT returns a boolean indicating whether or not .Va Giant was acquired. .Sh SEE ALSO .Xr mutex 9 , .Xr NDHASGIANT 9 , .Xr vnode 9 .Sh AUTHORS .An -nosplit MPSAFE VFS support for .Fx was implemented by .An Jeff Roberson .
p This manual page was written by .An Robert Watson . .Sh BUGS Non-MPSAFE file systems exist, requiring callers conditional locking and unlocking of .Va Giant .