xfs: define a flags field for the AG geometry ioctl structure

Define a flags field for the AG geometry ioctl structure.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_fs.h

@@ -287,7 +287,7 @@ struct xfs_ag_geometry {
 	uint32_t	ag_ifree;	/* o: inodes free */
 	uint32_t	ag_sick;	/* o: sick things in ag */
 	uint32_t	ag_checked;	/* o: checked metadata in ag */
-	uint32_t	ag_reserved32;	/* o: zero */
+	uint32_t	ag_flags;	/* i/o: flags for this ag */
 	uint64_t	ag_reserved[12];/* o: zero */
 };
 #define XFS_AG_GEOM_SICK_SB	(1 << 0)  /* superblock */

fs/xfs/xfs_ioctl.c

@@ -1038,6 +1038,10 @@ xfs_ioc_ag_geometry(
 
 	if (copy_from_user(&ageo, arg, sizeof(ageo)))
 		return -EFAULT;
+	if (ageo.ag_flags)
+		return -EINVAL;
+	if (memchr_inv(&ageo.ag_reserved, 0, sizeof(ageo.ag_reserved)))
+		return -EINVAL;
 
 	error = xfs_ag_get_geometry(mp, ageo.ag_number, &ageo);
 	if (error)