linux/ipc
Vladimir Davydov 38d78e587d 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>
2013-03-22 16:41:21 -07:00
..
Makefile Add generic sys_ipc wrapper 2010-03-12 15:52:32 -08:00
compat.c selftests: IPC message queue copy feature test 2013-01-04 16:11:45 -08:00
compat_mq.c ipc: initialize structure memory to zero for compat functions 2010-10-27 18:03:13 -07:00
ipc_sysctl.c ipc: add sysctl to specify desired next object id 2013-01-04 16:11:45 -08:00
ipcns_notifier.c ipc: do not use a negative value to re-enable msgmni automatic recomputing 2008-07-25 10:53:42 -07:00
mq_sysctl.c mqueue: separate mqueue default value from maximum value 2012-05-31 17:49:31 -07:00
mqueue.c mqueue: sys_mq_open: do not call mnt_drop_write() if read-only 2013-03-22 16:41:21 -07:00
msg.c ipc: don't allocate a copy larger than max 2013-03-08 15:05:33 -08:00
msgutil.c ipc: fix potential oops when src msg > 4k w/ MSG_COPY 2013-03-08 15:05:33 -08:00
namespace.c userns: Require CAP_SYS_ADMIN for most uses of setns. 2012-12-14 16:12:03 -08:00
sem.c userns: Convert ipc to use kuid and kgid where appropriate 2012-09-06 22:17:20 -07:00
shm.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
syscall.c ipc: add COMPAT_SHMLBA support 2012-07-30 17:25:20 -07:00
util.c ipc: convert to idr_alloc() 2013-02-27 19:10:19 -08:00
util.h ipc: introduce message queue copy feature 2013-01-04 16:11:45 -08:00