btrfs: do not abort transaction on failure to update log root

When syncing a log, if we fail to update a log root in the log root tree,
we are aborting the transaction if the failure was not -ENOSPC. This is
excessive because there is a chance that a transaction commit can succeed,
and therefore avoid to turn the filesystem into RO mode. All we need to be
careful about is to mark the log for a full commit, which we already do,
to make sure no one commits a super block pointing to an outdated log root
tree.

So don't abort the transaction if we fail to update a log root in the log
root tree, and log an error if the failure is not -ENOSPC, so that it does
not go completely unnoticed.

CC: [email protected] # 6.0+
Reviewed-by: Josef Bacik <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: fdmanana

fs/btrfs/tree-log.c

@@ -3044,15 +3044,12 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 
 		blk_finish_plug(&plug);
 		btrfs_set_log_full_commit(trans);
-
-		if (ret != -ENOSPC) {
-			btrfs_abort_transaction(trans, ret);
-			mutex_unlock(&log_root_tree->log_mutex);
-			goto out;
-		}
+		if (ret != -ENOSPC)
+			btrfs_err(fs_info,
+				  "failed to update log for root %llu ret %d",
+				  root->root_key.objectid, ret);
 		btrfs_wait_tree_log_extents(log, mark);
 		mutex_unlock(&log_root_tree->log_mutex);
-		ret = BTRFS_LOG_FORCE_COMMIT;
 		goto out;
 	}