xfs: add xfs_verify_agino_or_null helper

Add a new helper to check that a per-AG inode pointer is either null or
points somewhere valid within that AG.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_inode_buf.c

@@ -99,8 +99,7 @@ xfs_inode_buf_verify(
 		unlinked_ino = be32_to_cpu(dip->di_next_unlinked);
 		di_ok = dip->di_magic == cpu_to_be16(XFS_DINODE_MAGIC) &&
 			xfs_dinode_good_version(mp, dip->di_version) &&
-			(unlinked_ino == NULLAGINO ||
-			 xfs_verify_agino(mp, agno, unlinked_ino));
+			xfs_verify_agino_or_null(mp, agno, unlinked_ino);
 		if (unlikely(XFS_TEST_ERROR(!di_ok, mp,
 						XFS_ERRTAG_ITOBP_INOTOBP))) {
 			if (readahead) {

fs/xfs/libxfs/xfs_types.c

@@ -115,6 +115,19 @@ xfs_verify_agino(
 	return agino >= first && agino <= last;
 }
 
+/*
+ * Verify that an AG inode number pointer neither points outside the AG
+ * nor points at static metadata, or is NULLAGINO.
+ */
+bool
+xfs_verify_agino_or_null(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	xfs_agino_t		agino)
+{
+	return agino == NULLAGINO || xfs_verify_agino(mp, agno, agino);
+}
+
 /*
  * Verify that an FS inode number pointer neither points outside the
  * filesystem nor points at static AG metadata.

fs/xfs/libxfs/xfs_types.h

@@ -183,6 +183,8 @@ void xfs_agino_range(struct xfs_mount *mp, xfs_agnumber_t agno,
 		xfs_agino_t *first, xfs_agino_t *last);
 bool xfs_verify_agino(struct xfs_mount *mp, xfs_agnumber_t agno,
 		xfs_agino_t agino);
+bool xfs_verify_agino_or_null(struct xfs_mount *mp, xfs_agnumber_t agno,
+		xfs_agino_t agino);
 bool xfs_verify_ino(struct xfs_mount *mp, xfs_ino_t ino);
 bool xfs_internal_inum(struct xfs_mount *mp, xfs_ino_t ino);
 bool xfs_verify_dir_ino(struct xfs_mount *mp, xfs_ino_t ino);

fs/xfs/scrub/agheader.c

@@ -864,19 +864,17 @@ xchk_agi(
 
 	/* Check inode pointers */
 	agino = be32_to_cpu(agi->agi_newino);
-	if (agino != NULLAGINO && !xfs_verify_agino(mp, agno, agino))
+	if (!xfs_verify_agino_or_null(mp, agno, agino))
 		xchk_block_set_corrupt(sc, sc->sa.agi_bp);
 
 	agino = be32_to_cpu(agi->agi_dirino);
-	if (agino != NULLAGINO && !xfs_verify_agino(mp, agno, agino))
+	if (!xfs_verify_agino_or_null(mp, agno, agino))
 		xchk_block_set_corrupt(sc, sc->sa.agi_bp);
 
 	/* Check unlinked inode buckets */
 	for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++) {
 		agino = be32_to_cpu(agi->agi_unlinked[i]);
-		if (agino == NULLAGINO)
-			continue;
-		if (!xfs_verify_agino(mp, agno, agino))
+		if (!xfs_verify_agino_or_null(mp, agno, agino))
 			xchk_block_set_corrupt(sc, sc->sa.agi_bp);
 	}