Revert "block: Fix UAF in bd_link_disk_holder()"

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60QE9
CVE: NA

--------------------------------

This reverts commit 01b1ec1d.

Official solution will be applied to mainline, and this solution can't
fix uaf for 'bd_holder_dir' thoroughly. hence revert this temporary
solution. Officail solution will be backported in the next patch.
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

fs/block_dev.c

@@ -1650,7 +1650,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 		}
 	}
 	bdev->bd_openers++;
-	kobject_get(bdev->bd_part->holder_dir);
 	if (for_part)
 		bdev->bd_part_count++;
 	if (mode & FMODE_WRITE)
@@ -1926,7 +1925,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
 	if (for_part)
 		bdev->bd_part_count--;
 
-	kobject_put(bdev->bd_part->holder_dir);
 	if (!--bdev->bd_openers) {
 		WARN_ON_ONCE(bdev->bd_holders);
 		sync_blockdev(bdev);