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Commit 40591bdb authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Darrick J. Wong
Browse files

xfs: don't rely on extent indices in xfs_bmap_collapse_extents 



Rewrite xfs_bmap_collapse_extents so that we don't rely on extent indices
except for iterating over them.  Not being able to iterate to the next
extent is a sufficient exit condition, and we don't need to do any extent
count games given that:

  a) we already flushed all delalloc extents past our start offset
     before doing the operation
  b) xfs_iext_count() includes delalloc extents anyway

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 11f75b3b

fs/xfs/libxfs/xfs_bmap.c

+12 −42
Original line number Diff line number Diff line
@@ -5637,8 +5637,6 @@ xfs_bmap_collapse_extents( 
	struct xfs_btree_cur	*cur = NULL;

	struct xfs_bmbt_irec	got, prev;

	xfs_extnum_t		current_ext;

	xfs_extnum_t		total_extents;

	xfs_extnum_t		stop_extent;

	xfs_fileoff_t		new_startoff;

	int			error = 0;

	int			logflags = 0;
@@ -5669,52 +5667,31 @@ xfs_bmap_collapse_extents( 
		cur->bc_private.b.flags = 0;

	}



	/*

	 * There may be delalloc extents in the data fork before the range we

	 * are collapsing out, so we cannot use the count of real extents here.

	 * Instead we have to calculate it from the incore fork.

	 */

	total_extents = xfs_iext_count(ifp);

	if (total_extents == 0) {

		*done = true;

		goto del_cursor;

	}



	/*

	 * Look up the extent index for the fsb where we start shifting. We can

	 * henceforth iterate with current_ext as extent list changes are locked

	 * out via ilock.

	 *

	 * If next_fsb lies in a hole beyond which there are no extents we are

	 * done.

	 */

	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext, &got)) {

		*done = true;

		goto del_cursor;

	}

	XFS_WANT_CORRUPTED_RETURN(mp, !isnullstartblock(got.br_startblock));



	stop_extent = total_extents;

	if (current_ext >= stop_extent) {

		error = -EIO;

		goto del_cursor;

	}



	new_startoff = got.br_startoff - offset_shift_fsb;

	if (current_ext) {

		xfs_iext_get_extent(ifp, current_ext - 1, &prev);

	if (xfs_iext_get_extent(ifp, current_ext - 1, &prev)) {

		if (new_startoff < prev.br_startoff + prev.br_blockcount) {

			error = -EINVAL;

			goto del_cursor;

		}



		/* check whether to merge the extent or shift it down */

		if (xfs_bmse_can_merge(&prev, &got, offset_shift_fsb)) {

			error = xfs_bmse_merge(ip, whichfork, offset_shift_fsb,

					current_ext, &got, &prev, cur,

					&logflags, dfops);

			if (error)

				goto del_cursor;



			/* update got after merge */

			if (!xfs_iext_get_extent(ifp, current_ext, &got)) {

				*done = true;

				goto del_cursor;

			}

			goto done;

		}

	} else {
@@ -5728,20 +5705,13 @@ xfs_bmap_collapse_extents( 
			cur, &logflags, dfops, new_startoff);

	if (error)

		goto del_cursor;

	current_ext++;

done:

	/*

	 * If there was an extent merge during the shift, the extent

	 * count can change. Update the total and grade the next record.

	 */

	total_extents = xfs_iext_count(ifp);

	stop_extent = total_extents;

	if (current_ext == stop_extent) {



	if (!xfs_iext_get_extent(ifp, ++current_ext, &got)) {

		 *done = true;

		 goto del_cursor;

	}

	xfs_iext_get_extent(ifp, current_ext, &got);



done:

	*next_fsb = got.br_startoff;

del_cursor:

	if (cur)