reiserfs: fix unwanted reiserfs lock recursion
authorFrederic Weisbecker <fweisbec@gmail.com>
Thu, 30 Sep 2010 22:15:38 +0000 (15:15 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 1 Oct 2010 17:50:59 +0000 (10:50 -0700)
commit9d8117e72bf453dd9d85e0cd322ce4a0f8bccbc0
treeb04c93fa9d41db9802c576f8dfaf74edb42ebc60
parent3f259d092c7a2fdf217823e8f1838530adb0cdb0
reiserfs: fix unwanted reiserfs lock recursion

Prevent from recursively locking the reiserfs lock in reiserfs_unpack()
because we may call journal_begin() that requires the lock to be taken
only once, otherwise it won't be able to release the lock while taking
other mutexes, ending up in inverted dependencies between the journal
mutex and the reiserfs lock for example.

This fixes:

  =======================================================
  [ INFO: possible circular locking dependency detected ]
  2.6.35.4.4a #3
  -------------------------------------------------------
  lilo/1620 is trying to acquire lock:
   (&journal->j_mutex){+.+...}, at: [<d0325bff>] do_journal_begin_r+0x7f/0x340 [reiserfs]

  but task is already holding lock:
   (&REISERFS_SB(s)->lock){+.+.+.}, at: [<d032a278>] reiserfs_write_lock+0x28/0x40 [reiserfs]

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #1 (&REISERFS_SB(s)->lock){+.+.+.}:
         [<c10562b7>] lock_acquire+0x67/0x80
         [<c12facad>] __mutex_lock_common+0x4d/0x410
         [<c12fb0c8>] mutex_lock_nested+0x18/0x20
         [<d032a278>] reiserfs_write_lock+0x28/0x40 [reiserfs]
         [<d0325c06>] do_journal_begin_r+0x86/0x340 [reiserfs]
         [<d0325f77>] journal_begin+0x77/0x140 [reiserfs]
         [<d0315be4>] reiserfs_remount+0x224/0x530 [reiserfs]
         [<c10b6a20>] do_remount_sb+0x60/0x110
         [<c10cee25>] do_mount+0x625/0x790
         [<c10cf014>] sys_mount+0x84/0xb0
         [<c12fca3d>] syscall_call+0x7/0xb

  -> #0 (&journal->j_mutex){+.+...}:
         [<c10560f6>] __lock_acquire+0x1026/0x1180
         [<c10562b7>] lock_acquire+0x67/0x80
         [<c12facad>] __mutex_lock_common+0x4d/0x410
         [<c12fb0c8>] mutex_lock_nested+0x18/0x20
         [<d0325bff>] do_journal_begin_r+0x7f/0x340 [reiserfs]
         [<d0325f77>] journal_begin+0x77/0x140 [reiserfs]
         [<d0326271>] reiserfs_persistent_transaction+0x41/0x90 [reiserfs]
         [<d030d06c>] reiserfs_get_block+0x22c/0x1530 [reiserfs]
         [<c10db9db>] __block_prepare_write+0x1bb/0x3a0
         [<c10dbbe6>] block_prepare_write+0x26/0x40
         [<d030b738>] reiserfs_prepare_write+0x88/0x170 [reiserfs]
         [<d03294d6>] reiserfs_unpack+0xe6/0x120 [reiserfs]
         [<d0329782>] reiserfs_ioctl+0x272/0x320 [reiserfs]
         [<c10c3188>] vfs_ioctl+0x28/0xa0
         [<c10c3bbd>] do_vfs_ioctl+0x32d/0x5c0
         [<c10c3eb3>] sys_ioctl+0x63/0x70
         [<c12fca3d>] syscall_call+0x7/0xb

  other info that might help us debug this:

  2 locks held by lilo/1620:
   #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<d032945a>] reiserfs_unpack+0x6a/0x120 [reiserfs]
   #1:  (&REISERFS_SB(s)->lock){+.+.+.}, at: [<d032a278>] reiserfs_write_lock+0x28/0x40 [reiserfs]

  stack backtrace:
  Pid: 1620, comm: lilo Not tainted 2.6.35.4.4a #3
  Call Trace:
   [<c10560f6>] __lock_acquire+0x1026/0x1180
   [<c10562b7>] lock_acquire+0x67/0x80
   [<c12facad>] __mutex_lock_common+0x4d/0x410
   [<c12fb0c8>] mutex_lock_nested+0x18/0x20
   [<d0325bff>] do_journal_begin_r+0x7f/0x340 [reiserfs]
   [<d0325f77>] journal_begin+0x77/0x140 [reiserfs]
   [<d0326271>] reiserfs_persistent_transaction+0x41/0x90 [reiserfs]
   [<d030d06c>] reiserfs_get_block+0x22c/0x1530 [reiserfs]
   [<c10db9db>] __block_prepare_write+0x1bb/0x3a0
   [<c10dbbe6>] block_prepare_write+0x26/0x40
   [<d030b738>] reiserfs_prepare_write+0x88/0x170 [reiserfs]
   [<d03294d6>] reiserfs_unpack+0xe6/0x120 [reiserfs]
   [<d0329782>] reiserfs_ioctl+0x272/0x320 [reiserfs]
   [<c10c3188>] vfs_ioctl+0x28/0xa0
   [<c10c3bbd>] do_vfs_ioctl+0x32d/0x5c0
   [<c10c3eb3>] sys_ioctl+0x63/0x70
   [<c12fca3d>] syscall_call+0x7/0xb

Reported-by: Jarek Poplawski <jarkao2@gmail.com>
Tested-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: All since 2.6.32 <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/reiserfs/ioctl.c