xfs: create a new buf_ops pointer to verify structure metadata

Expose all metadata structure buffer verifier functions via buf_ops.
These will be used by the online scrub mechanism to look for problems
with buffers that are already sitting around in memory.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 0ae3961..cf07585 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -243,10 +243,35 @@ xfs_da3_node_read_verify(
 	}
 }
 
+/* Verify the structure of a da3 block. */
+static xfs_failaddr_t
+xfs_da3_node_verify_struct(
+	struct xfs_buf		*bp)
+{
+	struct xfs_da_blkinfo	*info = bp->b_addr;
+
+	switch (be16_to_cpu(info->magic)) {
+	case XFS_DA3_NODE_MAGIC:
+	case XFS_DA_NODE_MAGIC:
+		return xfs_da3_node_verify(bp);
+	case XFS_ATTR_LEAF_MAGIC:
+	case XFS_ATTR3_LEAF_MAGIC:
+		bp->b_ops = &xfs_attr3_leaf_buf_ops;
+		return bp->b_ops->verify_struct(bp);
+	case XFS_DIR2_LEAFN_MAGIC:
+	case XFS_DIR3_LEAFN_MAGIC:
+		bp->b_ops = &xfs_dir3_leafn_buf_ops;
+		return bp->b_ops->verify_struct(bp);
+	default:
+		return __this_address;
+	}
+}
+
 const struct xfs_buf_ops xfs_da3_node_buf_ops = {
 	.name = "xfs_da3_node",
 	.verify_read = xfs_da3_node_read_verify,
 	.verify_write = xfs_da3_node_write_verify,
+	.verify_struct = xfs_da3_node_verify_struct,
 };
 
 int