Re: [PATCH v2 1/4] nfs/blocklayout: Fix premature PR key unregistration

[Christoph Hellwig <hch@lst.de>]

On Fri, Jun 21, 2024 at 12:22:29PM -0400, cel@kernel.org wrote:
> @@ -367,14 +391,7 @@ bl_parse_scsi(struct nfs_server *server, struct pnfs_block_dev *d,
>  		goto out_blkdev_put;
>  	}
>  
> -	error = ops->pr_register(file_bdev(d->bdev_file), 0, d->pr_key, true);
> -	if (error) {
> -		pr_err("pNFS: failed to register key for block device %s.",
> -				file_bdev(d->bdev_file)->bd_disk->disk_name);
> -		goto out_blkdev_put;
> -	}
> -
> -	d->pr_registered = true;
> +	d->pr_register = bl_pr_register_scsi;

I think this will break complex (slice, concat, stripe) volumes,
as we'll never call ->pr_register for them at all.  We'll also need
a register callback for them, which then calls into underlying
volume, similar to how bl_parse_deviceid works.  That would also
do away with the need for the d->pr_register callback, we could
just do the swithc on the volume types which might be more
efficient.  (the same is actually true for the ->map callback,
but that's a separate cleanup).