[PATCH 5/6] xfs: flag empty xattr leaf blocks for optimization

Darrick J. Wong
2023-12-31T20:36:14Z

Empty xattr leaf blocks at offset zero are a waste of space but
otherwise harmless. If we encounter one, flag it as an opportunity for
optimization.

If we encounter empty attr leaf blocks anywhere else in the attr fork,
that's corruption.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/scrub/attr.c | 11 +++++++++++
fs/xfs/scrub/dabtree.h | 2 ++
2 files changed, 13 insertions(+)

diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
index 7dccbc849b19b..07e8ca840745c 100644
--- a/fs/xfs/scrub/attr.c
+++ b/fs/xfs/scrub/attr.c
@@ -420,6 +420,17 @@ xchk_xattr_block(
xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
hdrsize = xfs_attr3_leaf_hdr_size(leaf);

+ /*
+ * Empty xattr leaf blocks mapped at block 0 are probably a byproduct
+ * of a race between setxattr and a log shutdown. Anywhere else in the
+ * attr fork is a corruption.
+ */
+ if (leafhdr.count == 0) {
+ if (blk->blkno == 0)
+ xchk_da_set_preen(ds, level);
+ else
+ xchk_da_set_corrupt(ds, level);
+ }
if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
xchk_da_set_corrupt(ds, level);
if (leafhdr.firstused > mp->m_attr_geo->blksize)
diff --git a/fs/xfs/scrub/dabtree.h b/fs/xfs/scrub/dabtree.h
index d654c125feb4d..de291e3b77dd8 100644
--- a/fs/xfs/scrub/dabtree.h
+++ b/fs/xfs/scrub/dabtree.h
@@ -37,6 +37,8 @@ bool xchk_da_process_error(struct xchk_da_btree *ds, int level, int *error);
void xchk_da_set_corrupt(struct xchk_da_btree *ds, int level);
void xchk_da_set_preen(struct xchk_da_btree *ds, int level);

+void xchk_da_set_preen(struct xchk_da_btree *ds, int level);
+
int xchk_da_btree_hash(struct xchk_da_btree *ds, int level, __be32 *hashp);
int xchk_da_btree(struct xfs_scrub *sc, int whichfork,
xchk_da_btree_rec_fn scrub_fn, void *private);