Re: [PATCH v4 1/2] block: Add run_todo() operation

[Bart Van Assche <bvanassche@acm.org>]

On 9/19/26 3:50 AM, Tetsuo Handa wrote:
> Add run_todo() block device operation which provides a hook for performing
> synchronous cleanup without disk->open_mutex held, which is needed by the
> loop devices.

I like the "post_release()" name much better. I think it is more clear
and more descriptive than "run_todo()".

> diff --git a/block/bdev.c b/block/bdev.c
> index cd8323083740..8f09aafbae11 100644
> --- a/block/bdev.c
> +++ b/block/bdev.c
> @@ -974,6 +974,8 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
>   	bool unblock_events = true;
>   	struct gendisk *disk = bdev->bd_disk;
>   	int ret;
> +	struct module *fops_owner = NULL;
> +	void (*run_todo)(struct gendisk *disk) = NULL;
>   
>   	if (holder) {
>   		mode |= BLK_OPEN_EXCL;
> @@ -996,6 +998,7 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
>   	ret = -EBUSY;
>   	if (!bdev_may_open(bdev, mode))
>   		goto put_module;
> +	run_todo = disk->fops->run_todo;
>   	if (bdev_is_partition(bdev))
>   		ret = blkdev_get_part(bdev, mode);
>   	else
> @@ -1037,12 +1040,15 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
>   
>   	return 0;
>   put_module:
> -	module_put(disk->fops->owner);
> +	fops_owner = disk->fops->owner;
>   abort_claiming:
>   	if (holder)
>   		bd_abort_claiming(bdev, holder);
>   	mutex_unlock(&disk->open_mutex);
>   	disk_unblock_events(disk);
> +	if (run_todo)
> +		run_todo(disk);
> +	module_put(fops_owner);
>   	return ret;
>   }
The above changes introduce a bug: these changes cause module_put()
to be called if try_module_get() fails. I think that's wrong.

Thanks,

Bart.