[dm-devel] [PATCH 0/3] offload bios to a thread

[Lars Ellenberg]

On Thu, Jun 30, 2016 at 07:15:18PM -0400, Mike Snitzer wrote:
> > Lars, please feel free to see if this set addresses the similar deadlock
> > you saw/fixed with drbd.

I'm pretty sure it will help, but will confirm.

> > We need to converge on an acceptable fix for
> > this problem -- preferably sooner rather than later!
> > 
> > Conversely, Mikulas: if you can easily reproduce the dm-snapshot
> > deadlock please try Lars' fix to see if it is workable for our DM needs.
> 
> I hadn't reviewed Lars' patch yet but Mikulas pointed out to me that
> Lars' patch is focused on the blk_queue_split() path -- and given that
> DM doesn't use this function (nor do DM devices even have a 'bio_split'
> bioset, see commit dbba42d8a9e) it won't fix the DM (snapshot) deadlock.

Don't you get it implicitly when using dm-mq -> blk-mq?

    Lars