ocfs2: use 'osb' instead of 'OCFS2_SB()'

We could use 'osb' instead of 'OCFS2_SB()' to make code more elegant.

Link: http://lkml.kernel.org/r/5A702111.7090907@huawei.com
Signed-off-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <ge.changwei@h3c.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/dir.c

@@ -3072,7 +3072,7 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
 			 * We need to return the correct block within the
 			 * cluster which should hold our entry.
 			 */
-			off = ocfs2_dx_dir_hash_idx(OCFS2_SB(dir->i_sb),
+			off = ocfs2_dx_dir_hash_idx(osb,
 						    &lookup->dl_hinfo);
 			get_bh(dx_leaves[off]);
 			lookup->dl_dx_leaf_bh = dx_leaves[off];