xfs: create inode pointer verifiers

Create some helper functions to check that inode pointers point to
somewhere within the filesystem and not at the static AG metadata.
Move xfs_internal_inum and create a directory inode check function.
We will use these functions in scrub and elsewhere.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index dfd643909f85..e11f8af8a725 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -2664,3 +2664,93 @@ xfs_ialloc_pagi_init(
 		xfs_trans_brelse(tp, bp);
 	return 0;
 }
+
+/* Calculate the first and last possible inode number in an AG. */
+void
+xfs_ialloc_agino_range(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	xfs_agino_t		*first,
+	xfs_agino_t		*last)
+{
+	xfs_agblock_t		bno;
+	xfs_agblock_t		eoag;
+
+	eoag = xfs_ag_block_count(mp, agno);
+
+	/*
+	 * Calculate the first inode, which will be in the first
+	 * cluster-aligned block after the AGFL.
+	 */
+	bno = round_up(XFS_AGFL_BLOCK(mp) + 1,
+			xfs_ialloc_cluster_alignment(mp));
+	*first = XFS_OFFBNO_TO_AGINO(mp, bno, 0);
+
+	/*
+	 * Calculate the last inode, which will be at the end of the
+	 * last (aligned) cluster that can be allocated in the AG.
+	 */
+	bno = round_down(eoag, xfs_ialloc_cluster_alignment(mp));
+	*last = XFS_OFFBNO_TO_AGINO(mp, bno, 0) - 1;
+}
+
+/*
+ * Verify that an AG inode number pointer neither points outside the AG
+ * nor points at static metadata.
+ */
+bool
+xfs_verify_agino(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	xfs_agino_t		agino)
+{
+	xfs_agino_t		first;
+	xfs_agino_t		last;
+
+	xfs_ialloc_agino_range(mp, agno, &first, &last);
+	return agino >= first && agino <= last;
+}
+
+/*
+ * Verify that an FS inode number pointer neither points outside the
+ * filesystem nor points at static AG metadata.
+ */
+bool
+xfs_verify_ino(
+	struct xfs_mount	*mp,
+	xfs_ino_t		ino)
+{
+	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, ino);
+	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ino);
+
+	if (agno >= mp->m_sb.sb_agcount)
+		return false;
+	if (XFS_AGINO_TO_INO(mp, agno, agino) != ino)
+		return false;
+	return xfs_verify_agino(mp, agno, agino);
+}
+
+/* Is this an internal inode number? */
+bool
+xfs_internal_inum(
+	struct xfs_mount	*mp,
+	xfs_ino_t		ino)
+{
+	return ino == mp->m_sb.sb_rbmino || ino == mp->m_sb.sb_rsumino ||
+		(xfs_sb_version_hasquota(&mp->m_sb) &&
+		 xfs_is_quota_inode(&mp->m_sb, ino));
+}
+
+/*
+ * Verify that a directory entry's inode number doesn't point at an internal
+ * inode, empty space, or static AG metadata.
+ */
+bool
+xfs_verify_dir_ino(
+	struct xfs_mount	*mp,
+	xfs_ino_t		ino)
+{
+	if (xfs_internal_inum(mp, ino))
+		return false;
+	return xfs_verify_ino(mp, ino);
+}