xfs: cancel dfops on xfs_defer_finish() error

The current semantics of xfs_defer_finish() require the caller to
call xfs_defer_cancel() on error. This is slightly inconsistent with
transaction commit error handling where a failed commit cleans up
the transaction before returning.

More significantly, the only requirement for exposure of
->dop_pending outside of xfs_defer_finish() is so that
xfs_defer_cancel() can drain it on error. Since the only recourse of
xfs_defer_finish() errors is cancellation, mirror the transaction
logic and cancel remaining dfops before returning from
xfs_defer_finish() with an error.

Beside simplifying xfs_defer_finish() semantics, this ensures that
xfs_defer_finish() always returns with an empty ->dop_pending and
thus facilitates removal of the list from xfs_defer_ops.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_attr.c

@@ -590,7 +590,7 @@ xfs_attr_leaf_addname(
 			goto out_defer_cancel;
 		error = xfs_defer_finish(&args->trans);
 		if (error)
-			goto out_defer_cancel;
+			return error;
 
 		/*
 		 * Commit the current trans (including the inode) and start
@@ -678,7 +678,7 @@ xfs_attr_leaf_addname(
 				goto out_defer_cancel;
 			error = xfs_defer_finish(&args->trans);
 			if (error)
-				goto out_defer_cancel;
+				return error;
 		}
 
 		/*
@@ -741,7 +741,7 @@ xfs_attr_leaf_removename(
 			goto out_defer_cancel;
 		error = xfs_defer_finish(&args->trans);
 		if (error)
-			goto out_defer_cancel;
+			return error;
 	}
 	return 0;
 out_defer_cancel:
@@ -867,7 +867,7 @@ restart:
 				goto out_defer_cancel;
 			error = xfs_defer_finish(&args->trans);
 			if (error)
-				goto out_defer_cancel;
+				goto out;
 
 			/*
 			 * Commit the node conversion and start the next
@@ -891,7 +891,7 @@ restart:
 			goto out_defer_cancel;
 		error = xfs_defer_finish(&args->trans);
 		if (error)
-			goto out_defer_cancel;
+			goto out;
 	} else {
 		/*
 		 * Addition succeeded, update Btree hashvals.
@@ -987,7 +987,7 @@ restart:
 				goto out_defer_cancel;
 			error = xfs_defer_finish(&args->trans);
 			if (error)
-				goto out_defer_cancel;
+				goto out;
 		}
 
 		/*
@@ -1110,7 +1110,7 @@ xfs_attr_node_removename(
 			goto out_defer_cancel;
 		error = xfs_defer_finish(&args->trans);
 		if (error)
-			goto out_defer_cancel;
+			goto out;
 		/*
 		 * Commit the Btree join operation and start a new trans.
 		 */
@@ -1141,7 +1141,7 @@ xfs_attr_node_removename(
 				goto out_defer_cancel;
 			error = xfs_defer_finish(&args->trans);
 			if (error)
-				goto out_defer_cancel;
+				goto out;
 		} else
 			xfs_trans_brelse(args->trans, bp);
 	}

fs/xfs/libxfs/xfs_attr_remote.c

@@ -488,7 +488,7 @@ xfs_attr_rmtval_set(
 			goto out_defer_cancel;
 		error = xfs_defer_finish(&args->trans);
 		if (error)
-			goto out_defer_cancel;
+			return error;
 
 		ASSERT(nmap == 1);
 		ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
@@ -628,7 +628,7 @@ xfs_attr_rmtval_remove(
 			goto out_defer_cancel;
 		error = xfs_defer_finish(&args->trans);
 		if (error)
-			goto out_defer_cancel;
+			return error;
 
 		/*
 		 * Close out trans and start the next one in the chain.

fs/xfs/libxfs/xfs_defer.c

@@ -416,14 +416,15 @@ xfs_defer_finish_noroll(
 	}
 
 out:
-	if (error)
+	if (error) {
 		trace_xfs_defer_finish_error((*tp)->t_mountp, (*tp)->t_dfops,
 					     error);
-	 else
+		xfs_defer_cancel(*tp);
-		trace_xfs_defer_finish_done((*tp)->t_mountp, (*tp)->t_dfops,
+		return error;
-					    _RET_IP_);
+	}
 
-	return error;
+	trace_xfs_defer_finish_done((*tp)->t_mountp, (*tp)->t_dfops, _RET_IP_);
+	return 0;
 }
 
 int

fs/xfs/xfs_bmap_util.c

@@ -1624,7 +1624,7 @@ xfs_swap_extent_rmap(
 			error = xfs_defer_finish(tpp);
 			tp = *tpp;
 			if (error)
-				goto out_defer;
+				goto out;
 
 			tirec.br_startoff += rlen;
 			if (tirec.br_startblock != HOLESTARTBLOCK &&

fs/xfs/xfs_dquot.c

@@ -371,7 +371,7 @@ xfs_dquot_disk_alloc(
 	tp = *tpp;
 	if (error) {
 		xfs_buf_relse(bp);
-		goto error1;
+		goto error0;
 	}
 	*bpp = bp;
 	return 0;

fs/xfs/xfs_inode.c

@@ -1571,7 +1571,7 @@ xfs_itruncate_extents_flags(
 		 */
 		error = xfs_defer_finish(&tp);
 		if (error)
-			goto out_bmap_cancel;
+			goto out;
 
 		error = xfs_trans_roll_inode(&tp, ip);
 		if (error)

fs/xfs/xfs_reflink.c

@@ -518,10 +518,8 @@ xfs_reflink_cancel_cow_blocks(
 
 			/* Roll the transaction */
 			error = xfs_defer_finish(tpp);
-			if (error) {
+			if (error)
-				xfs_defer_cancel(*tpp);
 				break;
-			}
 
 			/* Remove the mapping from the CoW fork. */
 			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);

fs/xfs/xfs_trans.c

@@ -933,10 +933,8 @@ __xfs_trans_commit(
 		     !(tp->t_flags & XFS_TRANS_PERM_LOG_RES));
 	if (!regrant && (tp->t_flags & XFS_TRANS_PERM_LOG_RES)) {
 		error = xfs_defer_finish_noroll(&tp);
-		if (error) {
+		if (error)
-			xfs_defer_cancel(tp);
 			goto out_unreserve;
-		}
 	}
 
 	/*