Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes

[Christoph Hellwig <hch@lst.de>]

Hi Dan,

this looks mostly fine to me.  A few code comments below, but except
for this there is another issue with it:  We still have drivers
that share a single request_queue for multiple gendisks, so I wonder

Also I think you probably want one patch for the block framework,
and one to switch SCSI over to it.

> +struct disk_devt {
> +	struct kref kref;
> +	void (*release)(struct kref *);
> +};
> +
> +static inline void put_disk_devt(struct disk_devt *disk_devt)
> +{
> +	if (disk_devt)
> +		kref_put(&disk_devt->kref, disk_devt->release);
> +}
> +
> +static inline void get_disk_devt(struct disk_devt *disk_devt)
> +{
> +	if (disk_devt)
> +		kref_get(&disk_devt->kref);
> +}

Given that we have a user-supplied release callack I'd much rather get
rid of the kref here, use a normal atomic_t and pass the disk_devt
structure to the release callback then a kref.