Re: [dm-devel] [PATCH 2/8] block: remove the extra kobject reference in bd_link_disk_holder

[Mike Snitzer <snitzer@redhat.com>]

On Sun, Jul 25 2021 at  1:54P -0400,
Christoph Hellwig <hch@lst.de> wrote:

> With the new block_device life time rules there is no way for the
> bdev to go away as long as there is a holder, so remove these.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Might be useful to reference the primary commit that introduced "the
new block_device life time rules" just so readers can inform
themselves.

Reviewed-by: Mike Snitzer <snitzer@redhat.com>

> ---
>  block/holder.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/block/holder.c b/block/holder.c
> index 904a1dcd5c12..960654a71342 100644
> --- a/block/holder.c
> +++ b/block/holder.c
> @@ -92,11 +92,6 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
>  	ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
>  	if (ret)
>  		goto out_del;
> -	/*
> -	 * bdev could be deleted beneath us which would implicitly destroy
> -	 * the holder directory.  Hold on to it.
> -	 */
> -	kobject_get(bdev->bd_holder_dir);
>  
>  	list_add(&holder->list, &bdev->bd_holder_disks);
>  	goto out_unlock;
> @@ -130,7 +125,6 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
>  	if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
>  		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);
>  	}
> -- 
> 2.30.2
> 

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