xfs: use xfs_icluster_size_fsb in xfs_imap

Use xfs_icluster_size_fsb() in xfs_imap().
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

fs/xfs/xfs_ialloc.c

@@ -1377,7 +1377,7 @@ xfs_imap(
 		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 @@ xfs_imap(
 	 * 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);