From 40591bdbccc47661050d98200ab65e77fa2324bd Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 19 Oct 2017 11:08:51 -0700 Subject: [PATCH] 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: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_bmap.c | 54 +++++++++++------------------------------------- 1 file changed, 12 insertions(+), 42 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 680be05..cdec39b 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -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, ¤t_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) { - *done = true; - goto del_cursor; + + 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) -- 2.7.4