xfs: move the min and max group block numbers to xfs_group

Move the min and max agblock numbers to the generic xfs_group structure
so that we can start building validators for extents within an rtgroup.
While we're at it, use check_add_overflow for the extent length
computation because that has much better overflow checking.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 33 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_group.h b/fs/xfs/libxfs/xfs_group.h
index 5b7362277c3f..242b05627c7a 100644
--- a/fs/xfs/libxfs/xfs_group.h
+++ b/fs/xfs/libxfs/xfs_group.h
@@ -12,6 +12,10 @@ struct xfs_group {
 	atomic_t		xg_ref;		/* passive reference count */
 	atomic_t		xg_active_ref;	/* active reference count */
 
+	/* Precalculated geometry info */
+	uint32_t		xg_block_count;	/* max usable gbno */
+	uint32_t		xg_min_gbno;	/* min usable gbno */
+
 #ifdef __KERNEL__
 	/* -- kernel only structures below this line -- */
 
@@ -128,4 +132,33 @@ xfs_fsb_to_gbno(
 	return fsbno & mp->m_groups[type].blkmask;
 }
 
+static inline bool
+xfs_verify_gbno(
+	struct xfs_group	*xg,
+	uint32_t		gbno)
+{
+	if (gbno >= xg->xg_block_count)
+		return false;
+	if (gbno < xg->xg_min_gbno)
+		return false;
+	return true;
+}
+
+static inline bool
+xfs_verify_gbext(
+	struct xfs_group	*xg,
+	uint32_t		gbno,
+	uint32_t		glen)
+{
+	uint32_t		end;
+
+	if (!xfs_verify_gbno(xg, gbno))
+		return false;
+	if (glen == 0 || check_add_overflow(gbno, glen - 1, &end))
+		return false;
+	if (!xfs_verify_gbno(xg, end))
+		return false;
+	return true;
+}
+
 #endif /* __LIBXFS_GROUP_H */