svn commit: r184073 - head/sys/kern
Konstantin Belousov
kib at FreeBSD.org
Mon Oct 20 10:07:29 UTC 2008
Author: kib
Date: Mon Oct 20 10:07:28 2008
New Revision: 184073
URL: http://svn.freebsd.org/changeset/base/184073
Log:
In vfs_busy(), lockmgr() cannot legitimately sleep, because code checked
MNTK_UNMOUNT before, and mnt_mtx is used as interlock. vfs_busy() always
tries to obtain a shared lock on mnt_lock, the other user is unmount who
tries to drain it, setting MNTK_UNMOUNT before.
Reviewed by: tegge, attilio
Tested by: pho
MFC after: 2 weeks
Modified:
head/sys/kern/vfs_subr.c
Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c Mon Oct 20 08:44:14 2008 (r184072)
+++ head/sys/kern/vfs_subr.c Mon Oct 20 10:07:28 2008 (r184073)
@@ -368,7 +368,7 @@ vfs_busy(struct mount *mp, int flags, st
}
if (interlkp)
mtx_unlock(interlkp);
- lkflags = LK_SHARED | LK_INTERLOCK;
+ lkflags = LK_SHARED | LK_INTERLOCK | LK_NOWAIT;
if (lockmgr(&mp->mnt_lock, lkflags, MNT_MTX(mp)))
panic("vfs_busy: unexpected lock failure");
return (0);
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