[PATCH v2 1/2] blk-mq: add tagset quiesce interface

[Christoph Hellwig]

On Wed, Oct 19, 2022 at 10:15:26AM +0300, Sagi Grimberg wrote:
> nvme-tcp will opportunistically try a network send directly from
> .queue_rq(), but always with MSG_DONTWAIT, so that is not a problem.
>
> nbd though can block in .queue_rq() with blocking network sends, however
> afaict nbd allocates a tagset per nbd_device, and also a request_queue
> per device, so its effectively the same if the srcu is in the tagset or
> in the request_queue.

Yes, the only multiple request_queue per tag_set cases right now
are nvme-tcp and mmc.  There have been patches from iSCSI, but they
seem to be stuck.