On Thu, Jun 13, 2019 at 05:33:49PM -0700, Tejun Heo wrote: > From: Chris Mason <clm@xxxxxx> > > Async CRCs and compression submit IO through helper threads, which > means they have IO priority inversions when cgroup IO controllers are > in use. > > This flags all of the writes submitted by btrfs helper threads as > REQ_CGROUP_PUNT. submit_bio() will punt these to dedicated per-blkcg > work items to avoid the priority inversion. > > For the compression code, we take a reference on the wbc's blkg css and > pass it down to the async workers. > > For the async crcs, the bio already has the correct css, we just need to > tell the block layer to use REQ_CGROUP_PUNT. > > Signed-off-by: Chris Mason <clm@xxxxxx> > Modified-and-reviewed-by: Tejun Heo <tj@xxxxxxxxxx> > --- Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Thanks, Josef
