Re: [PATCH] bfq: backport: update internal depth state when queue depth changes

[Greg KH]

On Fri, May 10, 2019 at 04:18:55PM -0400, Sasha Levin wrote:
> On Fri, May 10, 2019 at 10:56:32AM -0700, Eric Wheeler wrote:
> > From: Jens Axboe <axboe@xxxxxxxxx>
> > 
> > commit 77f1e0a52d26242b6c2dba019f6ebebfb9ff701e upstream
> > 
> > A previous commit moved the shallow depth and BFQ depth map calculations
> > to be done at init time, moving it outside of the hotter IO path. This
> > potentially causes hangs if the users changes the depth of the scheduler
> > map, by writing to the 'nr_requests' sysfs file for that device.
> > 
> > Add a blk-mq-sched hook that allows blk-mq to inform the scheduler if
> > the depth changes, so that the scheduler can update its internal state.
> > 
> > Signed-off-by: Eric Wheeler <bfq@xxxxxxxxxxxxxxxxxx>
> > Tested-by: Kai Krakow <kai@xxxxxxxxxxx>
> > Reported-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
> > Fixes: f0635b8a416e ("bfq: calculate shallow depths at init time")
> > Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> 
> I wasn't clear on what was backported here, so I've queued the upstream
> version on 4.19 and 4.14, it doesn't seem to be relevant to older
> branches.

I only see this added to the 5.0 and 4.19 queues, did you forget to push
the 4.14 update?

thanks,

greg k-h