[XFS] Fix calculation of reserved AGs for inodes in 32-bit inode mode

Spotted by Roger Willcocks <willcor @at@ gmail.com>

SGI-PV: 944858
SGI-Modid: xfs-linux:xfs-kern:201213a
Signed-off-by: NEric Sandeen <sandeen@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

fs/xfs/xfs_mount.c

@@ -352,7 +352,7 @@ xfs_initialize_perag(
 			icount = sbp->sb_dblocks * sbp->sb_imax_pct;
 			do_div(icount, 100);
 			icount += sbp->sb_agblocks - 1;
-			do_div(icount, mp->m_ialloc_blks);
+			do_div(icount, sbp->sb_agblocks);
 			max_metadata = icount;
 		} else {
 			max_metadata = agcount;