Ext2: use unlikely to improve the efficiency of the kernel

Because the function 'sb_getblk' seldomly fails to return
NULL value. It will be better to use unlikely to optimize it.
Signed-off-by: NWang shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: NJan Kara <jack@suse.cz>

fs/ext2/super.c

@@ -1500,7 +1500,7 @@ static ssize_t ext2_quota_write(struct super_block *sb, int type,
 			bh = sb_bread(sb, tmp_bh.b_blocknr);
 		else
 			bh = sb_getblk(sb, tmp_bh.b_blocknr);
-		if (!bh) {
+		if (unlikely(!bh)) {
 			err = -EIO;
 			goto out;
 		}

fs/ext2/xattr.c

@@ -662,7 +662,7 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
 			ea_idebug(inode, "creating block %d", block);
 
 			new_bh = sb_getblk(sb, block);
-			if (!new_bh) {
+			if (unlikely(!new_bh)) {
 				ext2_free_blocks(inode, block, 1);
 				mark_inode_dirty(inode);
 				error = -EIO;