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| author | Vladimir Davydov <vdavydov@parallels.com> | 2013-03-22 15:04:51 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-03-22 16:41:21 -0700 |
| commit | 38d78e587d4960d0db94add518d27ee74bad2301 (patch) | |
| tree | 3022cdde7ae5acd60be295f3d3fd9c78814e41c4 | |
| parent | ca4b3f302c90de5e516296e581c31c80125cd24b (diff) | |
| download | linux-stable-38d78e587d4960d0db94add518d27ee74bad2301.tar.gz linux-stable-38d78e587d4960d0db94add518d27ee74bad2301.tar.bz2 linux-stable-38d78e587d4960d0db94add518d27ee74bad2301.zip | |
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:
=====================================
[ 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 <vdavydov@parallels.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | ipc/mqueue.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c index e5c4f609f22c..3953fda2e8bd 100644 --- a/ipc/mqueue.c +++ b/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; |