xfs: remove all boilerplate defer init/finish code

At this point, the transaction subsystem completely manages deferred
items internally such that the common and boilerplate
xfs_trans_alloc() -> xfs_defer_init() -> xfs_defer_finish() ->
xfs_trans_commit() sequence can be replaced with a simple
transaction allocation and commit.

Remove all such boilerplate deferred ops code. In doing so, we
change each case over to use the dfops in the transaction and
specifically eliminate:

- The on-stack dfops and associated xfs_defer_init() call, as the
  internal dfops is initialized on transaction allocation.
- xfs_bmap_finish() calls that precede a final xfs_trans_commit() of
  a transaction.
- xfs_defer_cancel() calls in error handlers that precede a
  transaction cancel.

The only deferred ops calls that remain are those that are
non-deterministic with respect to the final commit of the associated
transaction or are open-coded due to special handling.

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

1 files changed, 6 insertions, 37 deletions

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 1a4617c74c6a..ddb5f1200d3d 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -792,7 +792,6 @@ xfs_free_eofblocks(
 	int			nimaps;
 	struct xfs_bmbt_irec	imap;
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_defer_ops	dfops;
 
 	/*
 	 * Figure out if there are any blocks beyond the end
@@ -832,7 +831,6 @@ xfs_free_eofblocks(
 			ASSERT(XFS_FORCED_SHUTDOWN(mp));
 			return error;
 		}
-		xfs_defer_init(tp, &dfops);
 
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		xfs_trans_ijoin(tp, ip, 0);
@@ -880,7 +878,6 @@ xfs_alloc_file_space(
 	int			rt;
 	xfs_trans_t		*tp;
 	xfs_bmbt_irec_t		imaps[1], *imapp;
-	struct xfs_defer_ops	dfops;
 	uint			qblocks, resblks, resrtextents;
 	int			error;
 
@@ -973,7 +970,6 @@ xfs_alloc_file_space(
 
 		xfs_trans_ijoin(tp, ip, 0);
 
-		xfs_defer_init(tp, &dfops);
 		error = xfs_bmapi_write(tp, ip, startoffset_fsb,
 					allocatesize_fsb, alloc_type, resblks,
 					imapp, &nimaps);
@@ -983,10 +979,6 @@ xfs_alloc_file_space(
 		/*
 		 * Complete the transaction
 		 */
-		error = xfs_defer_finish(&tp, tp->t_dfops);
-		if (error)
-			goto error0;
-
 		error = xfs_trans_commit(tp);
 		xfs_iunlock(ip, XFS_ILOCK_EXCL);
 		if (error)
@@ -1005,8 +997,7 @@ xfs_alloc_file_space(
 
 	return error;
 
-error0:	/* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
-	xfs_defer_cancel(&dfops);
+error0:	/* unlock inode, unreserve quota blocks, cancel trans */
 	xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
 
 error1:	/* Just cancel transaction */
@@ -1024,7 +1015,6 @@ xfs_unmap_extent(
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_trans	*tp;
-	struct xfs_defer_ops	dfops;
 	uint			resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 	int			error;
 
@@ -1042,23 +1032,17 @@ xfs_unmap_extent(
 
 	xfs_trans_ijoin(tp, ip, 0);
 
-	xfs_defer_init(tp, &dfops);
 	error = xfs_bunmapi(tp, ip, startoffset_fsb, len_fsb, 0, 2, done);
 	if (error)
-		goto out_bmap_cancel;
+		goto out_trans_cancel;
 
 	xfs_defer_ijoin(tp->t_dfops, ip);
-	error = xfs_defer_finish(&tp, tp->t_dfops);
-	if (error)
-		goto out_bmap_cancel;
 
 	error = xfs_trans_commit(tp);
 out_unlock:
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	return error;
 
-out_bmap_cancel:
-	xfs_defer_cancel(tp->t_dfops);
 out_trans_cancel:
 	xfs_trans_cancel(tp);
 	goto out_unlock;
@@ -1310,7 +1294,6 @@ xfs_collapse_file_space(
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_trans	*tp;
 	int			error;
-	struct xfs_defer_ops	dfops;
 	xfs_fileoff_t		next_fsb = XFS_B_TO_FSB(mp, offset + len);
 	xfs_fileoff_t		shift_fsb = XFS_B_TO_FSB(mp, len);
 	uint			resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
@@ -1343,22 +1326,16 @@ xfs_collapse_file_space(
 			goto out_trans_cancel;
 		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 
-		xfs_defer_init(tp, &dfops);
 		error = xfs_bmap_collapse_extents(tp, ip, &next_fsb, shift_fsb,
 				&done);
 		if (error)
-			goto out_bmap_cancel;
+			goto out_trans_cancel;
 
-		error = xfs_defer_finish(&tp, tp->t_dfops);
-		if (error)
-			goto out_bmap_cancel;
 		error = xfs_trans_commit(tp);
 	}
 
 	return error;
 
-out_bmap_cancel:
-	xfs_defer_cancel(tp->t_dfops);
 out_trans_cancel:
 	xfs_trans_cancel(tp);
 	return error;
@@ -1385,7 +1362,6 @@ xfs_insert_file_space(
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_trans	*tp;
 	int			error;
-	struct xfs_defer_ops	dfops;
 	xfs_fileoff_t		stop_fsb = XFS_B_TO_FSB(mp, offset);
 	xfs_fileoff_t		next_fsb = NULLFSBLOCK;
 	xfs_fileoff_t		shift_fsb = XFS_B_TO_FSB(mp, len);
@@ -1421,22 +1397,17 @@ xfs_insert_file_space(
 
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
-		xfs_defer_init(tp, &dfops);
 		error = xfs_bmap_insert_extents(tp, ip, &next_fsb, shift_fsb,
 				&done, stop_fsb);
 		if (error)
-			goto out_bmap_cancel;
+			goto out_trans_cancel;
 
-		error = xfs_defer_finish(&tp, tp->t_dfops);
-		if (error)
-			goto out_bmap_cancel;
 		error = xfs_trans_commit(tp);
 	}
 
 	return error;
 
-out_bmap_cancel:
-	xfs_defer_cancel(tp->t_dfops);
+out_trans_cancel:
 	xfs_trans_cancel(tp);
 	return error;
 }
@@ -1607,7 +1578,7 @@ xfs_swap_extent_rmap(
 
 		/* Unmap the old blocks in the source file. */
 		while (tirec.br_blockcount) {
-			xfs_defer_init(tp, tp->t_dfops);
+			ASSERT(tp->t_firstblock == NULLFSBLOCK);
 			trace_xfs_swap_extent_rmap_remap_piece(tip, &tirec);
 
 			/* Read extent from the source file */
@@ -1831,7 +1802,6 @@ xfs_swap_extents(
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_trans	*tp;
-	struct xfs_defer_ops	dfops;
 	struct xfs_bstat	*sbp = &sxp->sx_stat;
 	int			src_log_flags, target_log_flags;
 	int			error = 0;
@@ -1900,7 +1870,6 @@ xfs_swap_extents(
 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
 	if (error)
 		goto out_unlock;
-	xfs_defer_init(tp, &dfops);
 
 	/*
 	 * Lock and join the inodes to the tansaction so that transaction commit