bfs: fix Lockdep warning
Eric Sesterhenn [Sat, 13 Sep 2008 09:33:12 +0000 (02:33 -0700)]
This fixes:

  =============================================
  [ INFO: possible recursive locking detected ]
  2.6.27-rc5-00283-g70bb089 #68
  ---------------------------------------------
  touch/6855 is trying to acquire lock:
   (&info->bfs_lock){--..}, at: [<c02262f5>] bfs_delete_inode+0x9e/0x18c

  but task is already holding lock:
   (&info->bfs_lock){--..}, at: [<c0226c00>] bfs_create+0x45/0x187

  other info that might help us debug this:
  2 locks held by touch/6855:
   #0:  (&type->i_mutex_dir_key#5){--..}, at: [<c018ad13>] do_filp_open+0x10b/0x62f
   #1:  (&info->bfs_lock){--..}, at: [<c0226c00>] bfs_create+0x45/0x187

  stack backtrace:
  Pid: 6855, comm: touch Not tainted 2.6.27-rc5-00283-g70bb089 #68
   [<c013e769>] validate_chain+0x458/0x9f4
   [<c013bece>] ? trace_hardirqs_off+0xb/0xd
   [<c013f36b>] __lock_acquire+0x666/0x6e0
   [<c013f440>] lock_acquire+0x5b/0x77
   [<c02262f5>] ? bfs_delete_inode+0x9e/0x18c
   [<c06aab74>] mutex_lock_nested+0xbc/0x234
   [<c02262f5>] ? bfs_delete_inode+0x9e/0x18c
   [<c02262f5>] ? bfs_delete_inode+0x9e/0x18c
   [<c02262f5>] bfs_delete_inode+0x9e/0x18c
   [<c0226257>] ? bfs_delete_inode+0x0/0x18c
   [<c01925e1>] generic_delete_inode+0x94/0xfe
   [<c019265d>] generic_drop_inode+0x12/0x12f
   [<c0191b7e>] iput+0x4b/0x4e
   [<c0226d1e>] bfs_create+0x163/0x187
   [<c0188b42>] vfs_create+0xa6/0x114
   [<c018adb5>] do_filp_open+0x1ad/0x62f
   [<c0107cdc>] ? native_sched_clock+0x82/0x96
   [<c06ac309>] ? _spin_unlock+0x27/0x3c
   [<c019379e>] ? alloc_fd+0xbf/0xc9
   [<c06ae2f4>] ? sub_preempt_count+0x9d/0xab
   [<c019379e>] ? alloc_fd+0xbf/0xc9
   [<c0180391>] do_sys_open+0x42/0xb8
   [<c041d564>] ? trace_hardirqs_on_thunk+0xc/0x10
   [<c0180449>] sys_open+0x1e/0x26
   [<c01038bd>] sysenter_do_call+0x12/0x31
   =======================

The problem is that we don't unlock the bfs->lock mutex before calling
iput (we do in the other cases).

Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/bfs/dir.c

index 87ee5cc..ed8feb0 100644 (file)
@@ -125,8 +125,8 @@ static int bfs_create(struct inode *dir, struct dentry *dentry, int mode,
                                                        inode->i_ino);
        if (err) {
                inode_dec_link_count(inode);
-               iput(inode);
                mutex_unlock(&info->bfs_lock);
+               iput(inode);
                return err;
        }
        mutex_unlock(&info->bfs_lock);