Btrfs: don't leak transaction in btrfs_sync_file()

In btrfs_sync_file(), if the call to btrfs_log_dentry_safe() returns
a negative error (for e.g. -ENOMEM via btrfs_log_inode()), we would
return without ending/freeing the transaction.
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/file.c

@@ -1859,8 +1859,8 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 
 	ret = btrfs_log_dentry_safe(trans, root, dentry);
 	if (ret < 0) {
-		mutex_unlock(&inode->i_mutex);
-		goto out;
+		/* Fallthrough and commit/free transaction. */
+		ret = 1;
 	}
 
 	/* we've logged all the items and now have a consistent