Re: [PATCH] RFC: loop: Avoid calling blk_mq_freeze_queue() when possible.

[Martijn Coenen]

On Thu, Aug 15, 2019 at 6:34 PM Ming Lei <tom.leiming@xxxxxxxxx> wrote:
> If nothing will change, why does the userspace bother to send
> SET_STATUS?

We don't change transfer, but we do change the offset and sizelimit.
In our specific case, we know there won't be any I/O from userspace at
this point; so from that point of view the freeze wouldn't be
necessary. But I'm not sure how we can make loop aware of that in a
safe way. Ideally we'd just have a way of completely configuring a
loop device before starting the block request queue, but that seems
like a pretty big change.

Martijn

>
>
> Thanks,
> Ming Lei