[PATCH] nvme-loop: set blocking flag

[Christoph Hellwig]

On Thu, Oct 17, 2024 at 11:39:24AM -0600, Jens Axboe wrote:
> On 10/17/24 11:20 AM, Keith Busch wrote:
> > From: Keith Busch <kbusch at kernel.org>
> > 
> > Commit 505363957fad ("nvmet: fix nvme status code when namespace is
> > disabled") introduced a mutex lock in the io path for target. The loop
> > target connects this to the blk-mq submission side, so it requires the
> > blocking flag set so that queue_rq doesn't happen inside an rcu context.
> 
> Looks fine to me, but might be worth looking at doing that a bit
> differently so that the target loop driver can remain non-blocking
> as it should be considerably more efficient.

Yes.  When designing the nvmet code back in the day (gosh do I feel old)
we tried to avoid blocking in the main handling thread in general.

So if we can get rid of the mutex that would be great.