xfs: use xfs_icluster_size_fsb in xfs_imap

Use xfs_icluster_size_fsb() in xfs_imap().

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_ialloc.c b/fs/xfs/xfs_ialloc.c
index 6ee592c..5d7f105 100644
--- a/fs/xfs/xfs_ialloc.c
+++ b/fs/xfs/xfs_ialloc.c
@@ -1377,7 +1377,7 @@
 		return XFS_ERROR(EINVAL);
 	}
 
-	blks_per_cluster = mp->m_inode_cluster_size >> mp->m_sb.sb_blocklog;
+	blks_per_cluster = xfs_icluster_size_fsb(mp);
 
 	/*
 	 * For bulkstat and handle lookups, we have an untrusted inode number
@@ -1398,7 +1398,7 @@
 	 * If the inode cluster size is the same as the blocksize or
 	 * smaller we get to the buffer by simple arithmetics.
 	 */
-	if (mp->m_inode_cluster_size <= mp->m_sb.sb_blocksize) {
+	if (blks_per_cluster == 1) {
 		offset = XFS_INO_TO_OFFSET(mp, ino);
 		ASSERT(offset < mp->m_sb.sb_inopblock);