xfs: always scrub record/key order of interior records

In commit d47fef9342d0, we removed the firstrec and firstkey fields of
struct xchk_btree because Christoph thought they were unnecessary
because we could use the record index in the btree cursor.  This is
incorrect because bc_ptrs (now bc_levels[].ptr) tracks the cursor
position within a specific btree block, not within the entire level.

The end result is that scrub no longer detects situations where the
rightmost record of a block is identical to the leftmost record of that
block's right sibling.  Fix this regression by reintroducing record
validity booleans so that order checking skips *only* the leftmost
record/key in each level.

Fixes: d47fef9342d0 ("xfs: don't track firstrec/firstkey separately in xchk_btree")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
index d9ab280..4ec3b1c 100644 (file)
--- a/fs/xfs/scrub/btree.c
+++ b/fs/xfs/scrub/btree.c
@@ -151,11 +151,12 @@ xchk_btree_rec(
 
        trace_xchk_btree_rec(bs->sc, cur, 0);
 
-       /* If this isn't the first record, are they in order? */
-       if (cur->bc_levels[0].ptr > 1 &&
+       /* Are all records across all record blocks in order? */
+       if (bs->lastrec_valid &&
            !cur->bc_ops->recs_inorder(cur, &bs->lastrec, rec))
                xchk_btree_set_corrupt(bs->sc, cur, 0);
        memcpy(&bs->lastrec, rec, cur->bc_ops->rec_len);
+       bs->lastrec_valid = true;
 
        if (cur->bc_nlevels == 1)
                return;
@@ -198,11 +199,12 @@ xchk_btree_key(
 
        trace_xchk_btree_key(bs->sc, cur, level);
 
-       /* If this isn't the first key, are they in order? */
-       if (cur->bc_levels[level].ptr > 1 &&
-           !cur->bc_ops->keys_inorder(cur, &bs->lastkey[level - 1], key))
+       /* Are all low keys across all node blocks in order? */
+       if (bs->lastkey[level - 1].valid &&
+           !cur->bc_ops->keys_inorder(cur, &bs->lastkey[level - 1].key, key))
                xchk_btree_set_corrupt(bs->sc, cur, level);
-       memcpy(&bs->lastkey[level - 1], key, cur->bc_ops->key_len);
+       memcpy(&bs->lastkey[level - 1].key, key, cur->bc_ops->key_len);
+       bs->lastkey[level - 1].valid = true;
 
        if (level + 1 >= cur->bc_nlevels)
                return;

diff --git a/fs/xfs/scrub/btree.h b/fs/xfs/scrub/btree.h
index 639e44e..9d7b9ee 100644 (file)
--- a/fs/xfs/scrub/btree.h
+++ b/fs/xfs/scrub/btree.h
@@ -31,6 +31,11 @@ typedef int (*xchk_btree_rec_fn)(
        struct xchk_btree               *bs,
        const union xfs_btree_rec       *rec);
 
+struct xchk_btree_key {
+       union xfs_btree_key             key;
+       bool                            valid;
+};
+
 struct xchk_btree {
        /* caller-provided scrub state */
        struct xfs_scrub                *sc;
@@ -40,11 +45,12 @@ struct xchk_btree {
        void                            *private;
 
        /* internal scrub state */
+       bool                            lastrec_valid;
        union xfs_btree_rec             lastrec;
        struct list_head                to_check;
 
        /* this element must come last! */
-       union xfs_btree_key             lastkey[];
+       struct xchk_btree_key           lastkey[];
 };
 
 /*