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From: Peter Holm <pho@FreeBSD.org>
Date: Mon, 24 Oct 2011 10:35:37 +0000 (UTC)
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Subject: svn commit: r226681 - head/sys/fs/nullfs
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Author: pho
Date: Mon Oct 24 10:35:37 2011
New Revision: 226681
URL: http://svn.freebsd.org/changeset/base/226681

Log:
  Only unlock if the lock is exclusive.
  
  Reported by:	Subbsd <subbsd gmail com>
  Discussed with:	kib

Modified:
  head/sys/fs/nullfs/null_vfsops.c

Modified: head/sys/fs/nullfs/null_vfsops.c
==============================================================================
--- head/sys/fs/nullfs/null_vfsops.c	Mon Oct 24 08:47:23 2011	(r226680)
+++ head/sys/fs/nullfs/null_vfsops.c	Mon Oct 24 10:35:37 2011	(r226681)
@@ -104,11 +104,10 @@ nullfs_mount(struct mount *mp)
 		return (EINVAL);
 
 	/*
-	 * Unlock lower node to avoid deadlock.
-	 * (XXX) VOP_ISLOCKED is needed?
+	 * Unlock lower node to avoid possible deadlock.
 	 */
 	if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
-		VOP_ISLOCKED(mp->mnt_vnodecovered)) {
+	    VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) {
 		VOP_UNLOCK(mp->mnt_vnodecovered, 0);
 		isvnunlocked = 1;
 	}