Date: Mon, 20 Oct 2008 10:07:28 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r184073 - head/sys/kern Message-ID: <200810201007.m9KA7SJQ066155@svn.freebsd.org>
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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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