block: remove delayed holder registration

Now that dm has been fixed to track of holder registrations before
add_disk, the somewhat buggy block layer code can be safely removed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20221115141054.1051801-8-yukuai1@huaweicloud.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -478,10 +478,6 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 		goto out_put_holder_dir;
 	}
 
-	ret = bd_register_pending_holders(disk);
-	if (ret < 0)
-		goto out_put_slave_dir;
-
 	ret = blk_register_queue(disk);
 	if (ret)
 		goto out_put_slave_dir;

block/holder.c

@@ -29,19 +29,6 @@ static void del_symlink(struct kobject *from, struct kobject *to)
 	sysfs_remove_link(from, kobject_name(to));
 }
 
-static int __link_disk_holder(struct block_device *bdev, struct gendisk *disk)
-{
-	int ret;
-
-	ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
-	if (ret)
-		return ret;
-	ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
-	if (ret)
-		del_symlink(disk->slave_dir, bdev_kobj(bdev));
-	return ret;
-}
-
 /**
  * bd_link_disk_holder - create symlinks between holding disk and slave bdev
  * @bdev: the claimed slave bdev
@@ -75,6 +62,9 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
 	struct bd_holder_disk *holder;
 	int ret = 0;
 
+	if (WARN_ON_ONCE(!disk->slave_dir))
+		return -EINVAL;
+
 	mutex_lock(&disk->open_mutex);
 
 	WARN_ON_ONCE(!bdev->bd_holder);
@@ -94,34 +84,32 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
 	INIT_LIST_HEAD(&holder->list);
 	holder->bdev = bdev;
 	holder->refcnt = 1;
-	if (disk->slave_dir) {
-		ret = __link_disk_holder(bdev, disk);
-		if (ret) {
-			kfree(holder);
-			goto out_unlock;
-		}
-	}
-
+	ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
+	if (ret)
+		goto out_free_holder;
+	ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
+	if (ret)
+		goto out_del_symlink;
 	list_add(&holder->list, &disk->slave_bdevs);
+
 	/*
 	 * del_gendisk drops the initial reference to bd_holder_dir, so we need
 	 * to keep our own here to allow for cleanup past that point.
 	 */
 	kobject_get(bdev->bd_holder_dir);
+	mutex_unlock(&disk->open_mutex);
+	return 0;
 
+out_del_symlink:
+	del_symlink(disk->slave_dir, bdev_kobj(bdev));
+out_free_holder:
+	kfree(holder);
 out_unlock:
 	mutex_unlock(&disk->open_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
 
-static void __unlink_disk_holder(struct block_device *bdev,
-		struct gendisk *disk)
-{
-	del_symlink(disk->slave_dir, bdev_kobj(bdev));
-	del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
-}
-
 /**
  * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
  * @bdev: the calimed slave bdev
@@ -136,11 +124,14 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
 {
 	struct bd_holder_disk *holder;
 
+	if (WARN_ON_ONCE(!disk->slave_dir))
+		return;
+
 	mutex_lock(&disk->open_mutex);
 	holder = bd_find_holder_disk(bdev, disk);
 	if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
-		if (disk->slave_dir)
-			__unlink_disk_holder(bdev, disk);
+		del_symlink(disk->slave_dir, bdev_kobj(bdev));
+		del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
 		kobject_put(bdev->bd_holder_dir);
 		list_del_init(&holder->list);
 		kfree(holder);
@@ -148,24 +139,3 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
 	mutex_unlock(&disk->open_mutex);
 }
 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
-
-int bd_register_pending_holders(struct gendisk *disk)
-{
-	struct bd_holder_disk *holder;
-	int ret;
-
-	mutex_lock(&disk->open_mutex);
-	list_for_each_entry(holder, &disk->slave_bdevs, list) {
-		ret = __link_disk_holder(holder->bdev, disk);
-		if (ret)
-			goto out_undo;
-	}
-	mutex_unlock(&disk->open_mutex);
-	return 0;
-
-out_undo:
-	list_for_each_entry_continue_reverse(holder, &disk->slave_bdevs, list)
-		__unlink_disk_holder(holder->bdev, disk);
-	mutex_unlock(&disk->open_mutex);
-	return ret;
-}

include/linux/blkdev.h

@@ -833,7 +833,6 @@ void set_capacity(struct gendisk *disk, sector_t size);
 #ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
 void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk);
-int bd_register_pending_holders(struct gendisk *disk);
 #else
 static inline int bd_link_disk_holder(struct block_device *bdev,
 				      struct gendisk *disk)
@@ -844,10 +843,6 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev,
 					 struct gendisk *disk)
 {
 }
-static inline int bd_register_pending_holders(struct gendisk *disk)
-{
-	return 0;
-}
 #endif /* CONFIG_BLOCK_HOLDER_DEPRECATED */
 
 dev_t part_devt(struct gendisk *disk, u8 partno);