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xfs: fix maxlevels comparisons in the btree staging code

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The btree geometry computation function has an off-by-one error in that
it does not allow maximally tall btrees (nlevels == XFS_BTREE_MAXLEVELS).
This can result in repairs failing unnecessarily on very fragmented
filesystems.  Subsequent patches to remove MAXLEVELS usage in favor of
the per-btree type computations will make this a much more likely
occurrence.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2021-09-16 12:26:46 -07:00
parent 512edfac85
commit 78e8ec83a4
1 changed files with 2 additions and 2 deletions
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4
fs/xfs/libxfs/xfs_btree_staging.c
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@ -662,7 +662,7 @@ xfs_btree_bload_compute_geometry(
xfs_btree_bload_ensure_slack(cur, &bbl->node_slack, 1); xfs_btree_bload_ensure_slack(cur, &bbl->node_slack, 1);
bbl->nr_records = nr_this_level = nr_records; bbl->nr_records = nr_this_level = nr_records;
for (cur->bc_nlevels = 1; cur->bc_nlevels < XFS_BTREE_MAXLEVELS;) { for (cur->bc_nlevels = 1; cur->bc_nlevels <= XFS_BTREE_MAXLEVELS;) {
uint64_t level_blocks; uint64_t level_blocks;
uint64_t dontcare64; uint64_t dontcare64;
unsigned int level = cur->bc_nlevels - 1; unsigned int level = cur->bc_nlevels - 1;
@ -724,7 +724,7 @@ xfs_btree_bload_compute_geometry(
nr_this_level = level_blocks; nr_this_level = level_blocks;
} }
if (cur->bc_nlevels == XFS_BTREE_MAXLEVELS) if (cur->bc_nlevels > XFS_BTREE_MAXLEVELS)
return -EOVERFLOW; return -EOVERFLOW;
bbl->btree_height = cur->bc_nlevels; bbl->btree_height = cur->bc_nlevels;