nilfs2: simplify nilfs_mdt_freeze_buffer

nilfs_page_get_nth_block() function used in nilfs_mdt_freeze_buffer()
always returns a valid buffer head, so its validity check can be
removed.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/mdt.c

@@ -493,31 +493,29 @@ int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
 	struct buffer_head *bh_frozen;
 	struct page *page;
 	int blkbits = inode->i_blkbits;
-	int ret = -ENOMEM;
 
 	page = grab_cache_page(&shadow->frozen_data, bh->b_page->index);
 	if (!page)
-		return ret;
+		return -ENOMEM;
 
 	if (!page_has_buffers(page))
 		create_empty_buffers(page, 1 << blkbits, 0);
 
 	bh_frozen = nilfs_page_get_nth_block(page, bh_offset(bh) >> blkbits);
-	if (bh_frozen) {
-		if (!buffer_uptodate(bh_frozen))
-			nilfs_copy_buffer(bh_frozen, bh);
-		if (list_empty(&bh_frozen->b_assoc_buffers)) {
-			list_add_tail(&bh_frozen->b_assoc_buffers,
-				      &shadow->frozen_buffers);
-			set_buffer_nilfs_redirected(bh);
-		} else {
-			brelse(bh_frozen); /* already frozen */
-		}
-		ret = 0;
+
+	if (!buffer_uptodate(bh_frozen))
+		nilfs_copy_buffer(bh_frozen, bh);
+	if (list_empty(&bh_frozen->b_assoc_buffers)) {
+		list_add_tail(&bh_frozen->b_assoc_buffers,
+			      &shadow->frozen_buffers);
+		set_buffer_nilfs_redirected(bh);
+	} else {
+		brelse(bh_frozen); /* already frozen */
 	}
+
 	unlock_page(page);
 	page_cache_release(page);
-	return ret;
+	return 0;
 }
 
 struct buffer_head *