The patch titled
Subject: mqueue: sys_mq_open: do not call mnt_drop_write() if read-only
has been removed from the -mm tree. Its filename was
mqueue-sys_mq_open-do-not-call-mnt_drop_write-if-read-only.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Subject: mqueue: sys_mq_open: do not call mnt_drop_write() if read-only
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:
[ 194.714880] =====================================
[ 194.719680] [ BUG: bad unlock balance detected! ]
[ 194.724488] 3.9.0-rc3 #5 Not tainted
[ 194.728159] -------------------------------------
[ 194.732958] a.out/12486 is trying to release lock (sb_writers) at:
[ 194.739355] [<ffffffff811b177f>] mnt_drop_write+0x1f/0x30
[ 194.744851] but there are no more locks to release!
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Doug Ledford <dledford@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/mqueue.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN ipc/mqueue.c~mqueue-sys_mq_open-do-not-call-mnt_drop_write-if-read-only ipc/mqueue.c
--- a/ipc/mqueue.c~mqueue-sys_mq_open-do-not-call-mnt_drop_write-if-read-only
+++ a/ipc/mqueue.c
@@ -840,7 +840,8 @@ 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;
_
Patches currently in -mm which might be from vdavydov@xxxxxxxxxxxxx are
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