xfs: check inobt record alignment on big block filesystems

On a big block filesystem, there may be multiple inobt records covering
a single inode cluster.  These records obviously won't be aligned to
cluster alignment rules, and they must cover the entire cluster.  Teach
scrub to check for these things.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>

fs/xfs/scrub/ialloc.c

@@ -47,6 +47,12 @@ xchk_setup_ag_iallocbt(
 struct xchk_iallocbt {
 	/* Number of inodes we see while scanning inobt. */
 	unsigned long long	inodes;
+
+	/* Expected next startino, for big block filesystems. */
+	xfs_agino_t		next_startino;
+
+	/* Expected end of the current inode cluster. */
+	xfs_agino_t		next_cluster_ino;
 };
 
 /*
@@ -277,6 +283,7 @@ xchk_iallocbt_rec_alignment(
 	struct xfs_inobt_rec_incore	*irec)
 {
 	struct xfs_mount		*mp = bs->sc->mp;
+	struct xchk_iallocbt		*iabt = bs->private;
 
 	/*
 	 * finobt records have different positioning requirements than inobt
@@ -300,6 +307,27 @@ xchk_iallocbt_rec_alignment(
 		return;
 	}
 
+	if (iabt->next_startino != NULLAGINO) {
+		/*
+		 * We're midway through a cluster of inodes that is mapped by
+		 * multiple inobt records.  Did we get the record for the next
+		 * irec in the sequence?
+		 */
+		if (irec->ir_startino != iabt->next_startino) {
+			xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
+			return;
+		}
+
+		iabt->next_startino += XFS_INODES_PER_CHUNK;
+
+		/* Are we done with the cluster? */
+		if (iabt->next_startino >= iabt->next_cluster_ino) {
+			iabt->next_startino = NULLAGINO;
+			iabt->next_cluster_ino = NULLAGINO;
+		}
+		return;
+	}
+
 	/* inobt records must be aligned to cluster and inoalignmnt size. */
 	if (irec->ir_startino & (mp->m_cluster_align_inodes - 1)) {
 		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
@@ -310,6 +338,17 @@ xchk_iallocbt_rec_alignment(
 		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);
 		return;
 	}
+
+	if (mp->m_inodes_per_cluster <= XFS_INODES_PER_CHUNK)
+		return;
+
+	/*
+	 * If this is the start of an inode cluster that can be mapped by
+	 * multiple inobt records, the next inobt record must follow exactly
+	 * after this one.
+	 */
+	iabt->next_startino = irec->ir_startino + XFS_INODES_PER_CHUNK;
+	iabt->next_cluster_ino = irec->ir_startino + mp->m_inodes_per_cluster;
 }
 
 /* Scrub an inobt/finobt record. */
@@ -474,6 +513,8 @@ xchk_iallocbt(
 	struct xfs_btree_cur	*cur;
 	struct xchk_iallocbt	iabt = {
 		.inodes		= 0,
+		.next_startino	= NULLAGINO,
+		.next_cluster_ino = NULLAGINO,
 	};
 	int			error;