Btrfs devel - Apr 2013 - [PATCH] Btrfs: fix lockdep warning

The locking order for stuff is

__sb_start_write
ordered_mutex

but with sync() we don''t do __sb_start_write for some strange reason,
which
means that our iput in wait_ordered_extents could start a transaction which does
the __sb_start_write while we''re holding the ordered_mutex.  Fix this
by using
delayed iput in sync.  Thanks,

Reported-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
---
 fs/btrfs/super.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index bb60fe5..2a0bece 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -866,7 +866,7 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
 		return 0;
 	}
 
-	btrfs_wait_ordered_extents(root, 0);
+	btrfs_wait_ordered_extents(root, 1);
 
 	trans = btrfs_attach_transaction_barrier(root);
 	if (IS_ERR(trans)) {
-- 
1.7.7.6

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On Wed, Apr 17, 2013 at 12:19:16PM -0400, Josef Bacik
wrote:
> The locking order for stuff is
> 
> __sb_start_write
> ordered_mutex
> 
> but with sync() we don''t do __sb_start_write for some strange
reason, which
> means that our iput in wait_ordered_extents could start a transaction which
does
> the __sb_start_write while we''re holding the ordered_mutex.  Fix
this by using
> delayed iput in sync.  Thanks,
No lockdep warning anymore.

david
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