3.6.11.2 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Vladimir Davydov <vdavy...@parallels.com>
[ Upstream commit 38d78e587d4960d0db94add518d27ee74bad2301 ]
mnt_drop_write() must be called only if mnt_want_write() succeeded,
otherwise the mnt_writers counter will diverge.
mnt_writers counters are used to check if remounting FS as read-only is
OK, so after an extra mnt_drop_write() call, it would be impossible to
remount mqueue FS as read-only. Besides, on umount a warning would be
printed like this one:
=====================================
[ BUG: bad unlock balance detected! ]
3.9.0-rc3 #5 Not tainted
-------------------------------------
a.out/12486 is trying to release lock (sb_writers) at:
mnt_drop_write+0x1f/0x30
but there are no more locks to release!
Signed-off-by: Vladimir Davydov <vdavy...@parallels.com>
Cc: Doug Ledford <dledf...@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
Cc: "Eric W. Biederman" <ebied...@xmission.com>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Steven Rostedt <rost...@goodmis.org>
---
ipc/mqueue.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 9a08acc..9e4cf7f 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -841,7 +841,8 @@ out_putfd:
fd = error;
}
mutex_unlock(&root->d_inode->i_mutex);
- mnt_drop_write(mnt);
+ if (!ro)
+ mnt_drop_write(mnt);
out_putname:
putname(name);
return fd;
--
1.7.10.4
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