xfs: remove XFS_BMAP_MAX_SHIFT_EXTENTS

The define was always set to 1, which means looping until we reach is
was dead code from the start.

Also remove an initialization of next_fsb for the done case that doesn't
fit the new code flow - it was never checked by the caller in the done
case to start with.
Signed-off-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>

fs/xfs/libxfs/xfs_bmap.c

@@ -5703,8 +5703,7 @@ xfs_bmse_shift_one(
 /*
  * Shift extent records to the left/right to cover/create a hole.
  *
- * The maximum number of extents to be shifted in a single operation is
- * @num_exts. @stop_fsb specifies the file offset at which to stop shift and the
+ * @stop_fsb specifies the file offset at which to stop shift and the
  * file offset where we've left off is returned in @next_fsb. @offset_shift_fsb
  * is the length by which each extent is shifted. If there is no hole to shift
  * the extents into, this will be considered invalid operation and we abort
@@ -5720,14 +5719,12 @@ xfs_bmap_shift_extents(
 	xfs_fileoff_t		stop_fsb,
 	xfs_fsblock_t		*firstblock,
 	struct xfs_defer_ops	*dfops,
-	enum shift_direction	direction,
-	int			num_exts)
+	enum shift_direction	direction)
 {
 	struct xfs_btree_cur		*cur = NULL;
 	struct xfs_bmbt_irec            got;
 	struct xfs_mount		*mp = ip->i_mount;
 	struct xfs_ifork		*ifp;
-	xfs_extnum_t			nexts = 0;
 	xfs_extnum_t			current_ext;
 	xfs_extnum_t			total_extents;
 	xfs_extnum_t			stop_extent;
@@ -5825,31 +5822,27 @@ xfs_bmap_shift_extents(
 		}
 	}
 
-	while (nexts++ < num_exts) {
-		error = xfs_bmse_shift_one(ip, whichfork, offset_shift_fsb,
-					   &current_ext, &got, cur, &logflags,
-					   direction, dfops);
-		if (error)
-			goto del_cursor;
-		/*
-		 * If there was an extent merge during the shift, the extent
-		 * count can change. Update the total and grade the next record.
-		 */
-		if (direction == SHIFT_LEFT) {
-			total_extents = xfs_iext_count(ifp);
-			stop_extent = total_extents;
-		}
+	error = xfs_bmse_shift_one(ip, whichfork, offset_shift_fsb,
+				   &current_ext, &got, cur, &logflags,
+				   direction, dfops);
+	if (error)
+		goto del_cursor;
+	/*
+	 * If there was an extent merge during the shift, the extent
+	 * count can change. Update the total and grade the next record.
+	 */
+	if (direction == SHIFT_LEFT) {
+		total_extents = xfs_iext_count(ifp);
+		stop_extent = total_extents;
+	}
 
-		if (current_ext == stop_extent) {
-			*done = 1;
-			*next_fsb = NULLFSBLOCK;
-			break;
-		}
-		xfs_iext_get_extent(ifp, current_ext, &got);
+	if (current_ext == stop_extent) {
+		*done = 1;
+		goto del_cursor;
 	}
+	xfs_iext_get_extent(ifp, current_ext, &got);
 
-	if (!*done)
-		*next_fsb = got.br_startoff;
+	*next_fsb = got.br_startoff;
 
 del_cursor:
 	if (cur)

fs/xfs/libxfs/xfs_bmap.h

@@ -183,15 +183,6 @@ static inline bool xfs_bmap_is_real_extent(struct xfs_bmbt_irec *irec)
 		!isnullstartblock(irec->br_startblock);
 }
 
-/*
- * This macro is used to determine how many extents will be shifted
- * in one write transaction. We could require two splits,
- * an extent move on the first and an extent merge on the second,
- * So it is proper that one extent is shifted inside write transaction
- * at a time.
- */
-#define XFS_BMAP_MAX_SHIFT_EXTENTS	1
-
 enum shift_direction {
 	SHIFT_LEFT = 0,
 	SHIFT_RIGHT,
@@ -240,8 +231,7 @@ uint	xfs_default_attroffset(struct xfs_inode *ip);
 int	xfs_bmap_shift_extents(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
 		int *done, xfs_fileoff_t stop_fsb, xfs_fsblock_t *firstblock,
-		struct xfs_defer_ops *dfops, enum shift_direction direction,
-		int num_exts);
+		struct xfs_defer_ops *dfops, enum shift_direction direction);
 int	xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
 int	xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
 		xfs_fileoff_t off, xfs_filblks_t len, xfs_filblks_t prealloc,

fs/xfs/xfs_bmap_util.c

@@ -1359,14 +1359,9 @@ xfs_collapse_file_space(
 		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 
 		xfs_defer_init(&dfops, &first_block);
-
-		/*
-		 * We are using the write transaction in which max 2 bmbt
-		 * updates are allowed
-		 */
 		error = xfs_bmap_shift_extents(tp, ip, &next_fsb, shift_fsb,
 				&done, stop_fsb, &first_block, &dfops,
-				SHIFT_LEFT, XFS_BMAP_MAX_SHIFT_EXTENTS);
+				SHIFT_LEFT);
 		if (error)
 			goto out_bmap_cancel;
 
@@ -1438,14 +1433,9 @@ xfs_insert_file_space(
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 		xfs_defer_init(&dfops, &first_block);
-
-		/*
-		 * We are using the write transaction in which max 2 bmbt
-		 * updates are allowed
-		 */
 		error = xfs_bmap_shift_extents(tp, ip, &next_fsb, shift_fsb,
 				&done, stop_fsb, &first_block, &dfops,
-				SHIFT_RIGHT, XFS_BMAP_MAX_SHIFT_EXTENTS);
+				SHIFT_RIGHT);
 		if (error)
 			goto out_bmap_cancel;