[PATCH 4/4] xfs: compare btree block keys to parent block's keys during scrub

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

When we're done checking all the records/keys in a btree block, compute
the low and high key of the block and compare them to the associated key
in the parent btree block.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_btree.c |    4 ++--
 fs/xfs/libxfs/xfs_btree.h |    4 ++++
 fs/xfs/scrub/btree.c      |   46 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 2 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index b3cd82a..848f371 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -2027,7 +2027,7 @@ xfs_btree_lookup(
 }
 
 /* Find the high key storage area from a regular key. */
-STATIC union xfs_btree_key *
+union xfs_btree_key *
 xfs_btree_high_key_from_key(
 	struct xfs_btree_cur	*cur,
 	union xfs_btree_key	*key)
@@ -2101,7 +2101,7 @@ xfs_btree_get_node_keys(
 }
 
 /* Derive the keys for any btree block. */
-STATIC void
+void
 xfs_btree_get_keys(
 	struct xfs_btree_cur	*cur,
 	struct xfs_btree_block	*block,
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index be82f41..b57501c 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -541,5 +541,9 @@ int64_t xfs_btree_diff_two_ptrs(struct xfs_btree_cur *cur,
 void xfs_btree_get_sibling(struct xfs_btree_cur *cur,
 			   struct xfs_btree_block *block,
 			   union xfs_btree_ptr *ptr, int lr);
+void xfs_btree_get_keys(struct xfs_btree_cur *cur,
+		struct xfs_btree_block *block, union xfs_btree_key *key);
+union xfs_btree_key *xfs_btree_high_key_from_key(struct xfs_btree_cur *cur,
+		union xfs_btree_key *key);
 
 #endif	/* __XFS_BTREE_H__ */
diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
index 9ccf763..9e8b67a 100644
--- a/fs/xfs/scrub/btree.c
+++ b/fs/xfs/scrub/btree.c
@@ -358,6 +358,50 @@ xfs_scrub_btree_get_block(
 }
 
 /*
+ * Check that the low and high keys of this block match the keys stored
+ * in the parent block.
+ */
+STATIC void
+xfs_scrub_btree_block_keys(
+	struct xfs_scrub_btree		*bs,
+	int				level,
+	struct xfs_btree_block		*block)
+{
+	union xfs_btree_key		block_keys;
+	struct xfs_btree_cur		*cur = bs->cur;
+	union xfs_btree_key		*high_bk;
+	union xfs_btree_key		*parent_keys;
+	union xfs_btree_key		*high_pk;
+	struct xfs_btree_block		*parent_block;
+	struct xfs_buf			*bp;
+
+	if (level >= cur->bc_nlevels - 1)
+		return;
+
+	/* Calculate the keys for this block. */
+	xfs_btree_get_keys(cur, block, &block_keys);
+
+	/* Obtain the parent's copy of the keys for this block. */
+	parent_block = xfs_btree_get_block(cur, level + 1, &bp);
+	parent_keys = xfs_btree_key_addr(cur, cur->bc_ptrs[level + 1],
+			parent_block);
+
+	if (cur->bc_ops->diff_two_keys(cur, &block_keys, parent_keys) != 0)
+		xfs_scrub_btree_set_corrupt(bs->sc, cur, 1);
+
+	if (!(cur->bc_flags & XFS_BTREE_OVERLAPPING))
+		return;
+
+	/* Get high keys */
+	high_bk = xfs_btree_high_key_from_key(cur, &block_keys);
+	high_pk = xfs_btree_high_key_addr(cur, cur->bc_ptrs[level + 1],
+			parent_block);
+
+	if (cur->bc_ops->diff_two_keys(cur, high_bk, high_pk) != 0)
+		xfs_scrub_btree_set_corrupt(bs->sc, cur, 1);
+}
+
+/*
  * Visit all nodes and leaves of a btree.  Check that all pointers and
  * records are in order, that the keys reflect the records, and use a callback
  * so that the caller can verify individual records.
@@ -418,6 +462,7 @@ xfs_scrub_btree(
 			/* End of leaf, pop back towards the root. */
 			if (cur->bc_ptrs[level] >
 			    be16_to_cpu(block->bb_numrecs)) {
+				xfs_scrub_btree_block_keys(&bs, level, block);
 				if (level < cur->bc_nlevels - 1)
 					cur->bc_ptrs[level + 1]++;
 				level++;
@@ -442,6 +487,7 @@ xfs_scrub_btree(
 
 		/* End of node, pop back towards the root. */
 		if (cur->bc_ptrs[level] > be16_to_cpu(block->bb_numrecs)) {
+			xfs_scrub_btree_block_keys(&bs, level, block);
 			if (level < cur->bc_nlevels - 1)
 				cur->bc_ptrs[level + 1]++;
 			level++;