Btrfs: reset ret in record_one_backref

I was getting warnings when running find ./ -type f -exec btrfs fi defrag -f {}
\; from record_one_backref because ret was set.  Turns out it was because it was
set to 1 because the search slot didn't come out exact and we never reset it.
So reset it to 0 right after the search so we don't leak this and get
uneccessary warnings.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/inode.c

@@ -2132,6 +2132,7 @@ static noinline int record_one_backref(u64 inum, u64 offset, u64 root_id,
 		WARN_ON(1);
 		return ret;
 	}
+	ret = 0;
 
 	while (1) {
 		cond_resched();
@@ -2181,8 +2182,6 @@ static noinline int record_one_backref(u64 inum, u64 offset, u64 root_id,
 		    old->len || extent_offset + num_bytes <=
 		    old->extent_offset + old->offset)
 			continue;
-
-		ret = 0;
 		break;
 	}