xfs: refactor btree block header checking functions

Refactor the btree block header checks to have an internal function that
returns the address of the failing check without logging errors.  The
scrubber will call the internal function, while the external version
will maintain the current logging behavior.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_btree.c

@@ -63,44 +63,63 @@ xfs_btree_magic(
 	return magic;
 }
 
-STATIC int				/* error (0 or EFSCORRUPTED) */
-xfs_btree_check_lblock(
-	struct xfs_btree_cur	*cur,	/* btree cursor */
-	struct xfs_btree_block	*block,	/* btree long form block pointer */
-	int			level,	/* level of the btree block */
-	struct xfs_buf		*bp)	/* buffer for block, if any */
+/*
+ * Check a long btree block header.  Return the address of the failing check,
+ * or NULL if everything is ok.
+ */
+xfs_failaddr_t
+__xfs_btree_check_lblock(
+	struct xfs_btree_cur	*cur,
+	struct xfs_btree_block	*block,
+	int			level,
+	struct xfs_buf		*bp)
 {
-	int			lblock_ok = 1; /* block passes checks */
-	struct xfs_mount	*mp;	/* file system mount point */
+	struct xfs_mount	*mp = cur->bc_mp;
 	xfs_btnum_t		btnum = cur->bc_btnum;
-	int			crc;
-
-	mp = cur->bc_mp;
-	crc = xfs_sb_version_hascrc(&mp->m_sb);
+	int			crc = xfs_sb_version_hascrc(&mp->m_sb);
 
 	if (crc) {
-		lblock_ok = lblock_ok &&
-			uuid_equal(&block->bb_u.l.bb_uuid,
-				   &mp->m_sb.sb_meta_uuid) &&
-			block->bb_u.l.bb_blkno == cpu_to_be64(
-				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
+		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid))
+			return __this_address;
+		if (block->bb_u.l.bb_blkno !=
+		    cpu_to_be64(bp ? bp->b_bn : XFS_BUF_DADDR_NULL))
+			return __this_address;
+		if (block->bb_u.l.bb_pad != cpu_to_be32(0))
+			return __this_address;
 	}
 
-	lblock_ok = lblock_ok &&
-		be32_to_cpu(block->bb_magic) == xfs_btree_magic(crc, btnum) &&
-		be16_to_cpu(block->bb_level) == level &&
-		be16_to_cpu(block->bb_numrecs) <=
-			cur->bc_ops->get_maxrecs(cur, level) &&
-		block->bb_u.l.bb_leftsib &&
-		(block->bb_u.l.bb_leftsib == cpu_to_be64(NULLFSBLOCK) ||
-		 XFS_FSB_SANITY_CHECK(mp,
-			be64_to_cpu(block->bb_u.l.bb_leftsib))) &&
-		block->bb_u.l.bb_rightsib &&
-		(block->bb_u.l.bb_rightsib == cpu_to_be64(NULLFSBLOCK) ||
-		 XFS_FSB_SANITY_CHECK(mp,
-			be64_to_cpu(block->bb_u.l.bb_rightsib)));
-
-	if (unlikely(XFS_TEST_ERROR(!lblock_ok, mp,
+	if (be32_to_cpu(block->bb_magic) != xfs_btree_magic(crc, btnum))
+		return __this_address;
+	if (be16_to_cpu(block->bb_level) != level)
+		return __this_address;
+	if (be16_to_cpu(block->bb_numrecs) >
+	    cur->bc_ops->get_maxrecs(cur, level))
+		return __this_address;
+	if (block->bb_u.l.bb_leftsib != cpu_to_be64(NULLFSBLOCK) &&
+	    !xfs_btree_check_lptr(cur, be64_to_cpu(block->bb_u.l.bb_leftsib),
+			level + 1))
+		return __this_address;
+	if (block->bb_u.l.bb_rightsib != cpu_to_be64(NULLFSBLOCK) &&
+	    !xfs_btree_check_lptr(cur, be64_to_cpu(block->bb_u.l.bb_rightsib),
+			level + 1))
+		return __this_address;
+
+	return NULL;
+}
+
+/* Check a long btree block header. */
+int
+xfs_btree_check_lblock(
+	struct xfs_btree_cur	*cur,
+	struct xfs_btree_block	*block,
+	int			level,
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = cur->bc_mp;
+	xfs_failaddr_t		fa;
+
+	fa = __xfs_btree_check_lblock(cur, block, level, bp);
+	if (unlikely(XFS_TEST_ERROR(fa != NULL, mp,
 			XFS_ERRTAG_BTREE_CHECK_LBLOCK))) {
 		if (bp)
 			trace_xfs_btree_corrupt(bp, _RET_IP_);
@@ -110,48 +129,61 @@ xfs_btree_check_lblock(
 	return 0;
 }
 
-STATIC int				/* error (0 or EFSCORRUPTED) */
-xfs_btree_check_sblock(
-	struct xfs_btree_cur	*cur,	/* btree cursor */
-	struct xfs_btree_block	*block,	/* btree short form block pointer */
-	int			level,	/* level of the btree block */
-	struct xfs_buf		*bp)	/* buffer containing block */
+/*
+ * Check a short btree block header.  Return the address of the failing check,
+ * or NULL if everything is ok.
+ */
+xfs_failaddr_t
+__xfs_btree_check_sblock(
+	struct xfs_btree_cur	*cur,
+	struct xfs_btree_block	*block,
+	int			level,
+	struct xfs_buf		*bp)
 {
-	struct xfs_mount	*mp;	/* file system mount point */
-	struct xfs_buf		*agbp;	/* buffer for ag. freespace struct */
-	struct xfs_agf		*agf;	/* ag. freespace structure */
-	xfs_agblock_t		agflen;	/* native ag. freespace length */
-	int			sblock_ok = 1; /* block passes checks */
+	struct xfs_mount	*mp = cur->bc_mp;
 	xfs_btnum_t		btnum = cur->bc_btnum;
-	int			crc;
-
-	mp = cur->bc_mp;
-	crc = xfs_sb_version_hascrc(&mp->m_sb);
-	agbp = cur->bc_private.a.agbp;
-	agf = XFS_BUF_TO_AGF(agbp);
-	agflen = be32_to_cpu(agf->agf_length);
+	int			crc = xfs_sb_version_hascrc(&mp->m_sb);
 
 	if (crc) {
-		sblock_ok = sblock_ok &&
-			uuid_equal(&block->bb_u.s.bb_uuid,
-				   &mp->m_sb.sb_meta_uuid) &&
-			block->bb_u.s.bb_blkno == cpu_to_be64(
-				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
+			return __this_address;
+		if (block->bb_u.s.bb_blkno !=
+		    cpu_to_be64(bp ? bp->b_bn : XFS_BUF_DADDR_NULL))
+			return __this_address;
 	}
 
-	sblock_ok = sblock_ok &&
-		be32_to_cpu(block->bb_magic) == xfs_btree_magic(crc, btnum) &&
-		be16_to_cpu(block->bb_level) == level &&
-		be16_to_cpu(block->bb_numrecs) <=
-			cur->bc_ops->get_maxrecs(cur, level) &&
-		(block->bb_u.s.bb_leftsib == cpu_to_be32(NULLAGBLOCK) ||
-		 be32_to_cpu(block->bb_u.s.bb_leftsib) < agflen) &&
-		block->bb_u.s.bb_leftsib &&
-		(block->bb_u.s.bb_rightsib == cpu_to_be32(NULLAGBLOCK) ||
-		 be32_to_cpu(block->bb_u.s.bb_rightsib) < agflen) &&
-		block->bb_u.s.bb_rightsib;
-
-	if (unlikely(XFS_TEST_ERROR(!sblock_ok, mp,
+	if (be32_to_cpu(block->bb_magic) != xfs_btree_magic(crc, btnum))
+		return __this_address;
+	if (be16_to_cpu(block->bb_level) != level)
+		return __this_address;
+	if (be16_to_cpu(block->bb_numrecs) >
+	    cur->bc_ops->get_maxrecs(cur, level))
+		return __this_address;
+	if (block->bb_u.s.bb_leftsib != cpu_to_be32(NULLAGBLOCK) &&
+	    !xfs_btree_check_sptr(cur, be32_to_cpu(block->bb_u.s.bb_leftsib),
+			level + 1))
+		return __this_address;
+	if (block->bb_u.s.bb_rightsib != cpu_to_be32(NULLAGBLOCK) &&
+	    !xfs_btree_check_sptr(cur, be32_to_cpu(block->bb_u.s.bb_rightsib),
+			level + 1))
+		return __this_address;
+
+	return NULL;
+}
+
+/* Check a short btree block header. */
+STATIC int
+xfs_btree_check_sblock(
+	struct xfs_btree_cur	*cur,
+	struct xfs_btree_block	*block,
+	int			level,
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = cur->bc_mp;
+	xfs_failaddr_t		fa;
+
+	fa = __xfs_btree_check_sblock(cur, block, level, bp);
+	if (unlikely(XFS_TEST_ERROR(fa != NULL, mp,
 			XFS_ERRTAG_BTREE_CHECK_SBLOCK))) {
 		if (bp)
 			trace_xfs_btree_corrupt(bp, _RET_IP_);

fs/xfs/libxfs/xfs_btree.h

@@ -255,6 +255,14 @@ typedef struct xfs_btree_cur
  */
 #define	XFS_BUF_TO_BLOCK(bp)	((struct xfs_btree_block *)((bp)->b_addr))
 
+/*
+ * Internal long and short btree block checks.  They return NULL if the
+ * block is ok or the address of the failed check otherwise.
+ */
+xfs_failaddr_t __xfs_btree_check_lblock(struct xfs_btree_cur *cur,
+		struct xfs_btree_block *block, int level, struct xfs_buf *bp);
+xfs_failaddr_t __xfs_btree_check_sblock(struct xfs_btree_cur *cur,
+		struct xfs_btree_block *block, int level, struct xfs_buf *bp);
 
 /*
  * Check that block header is ok.

fs/xfs/libxfs/xfs_types.h

@@ -47,6 +47,12 @@ typedef uint64_t	xfs_filblks_t;	/* number of blocks in a file */
 typedef int64_t		xfs_srtblock_t;	/* signed version of xfs_rtblock_t */
 typedef int64_t		xfs_sfiloff_t;	/* signed block number in a file */
 
+/*
+ * New verifiers will return the instruction address of the failing check.
+ * NULL means everything is ok.
+ */
+typedef void *		xfs_failaddr_t;
+
 /*
  * Null values for the types.
  */

fs/xfs/xfs_linux.h

@@ -142,6 +142,13 @@ typedef __u32			xfs_nlink_t;
 #define SYNCHRONIZE()	barrier()
 #define __return_address __builtin_return_address(0)
 
+/*
+ * Return the address of a label.  Use barrier() so that the optimizer
+ * won't reorder code to refactor the error jumpouts into a single
+ * return, which throws off the reported address.
+ */
+#define __this_address	({ __label__ __here; __here: barrier(); &&__here; })
+
 #define XFS_PROJID_DEFAULT	0
 
 #define MIN(a,b)	(min(a,b))