On Thu, Jul 13, 2017 at 09:50:23AM -0700, Shaohua Li wrote:

quoted

As said in the last mail I think there is no point in having this call..

I'm hesitant to do this. bio_associate_blkcg/bio_associate_current can be
called in any time for a bio, so we not just attach cgroup info to info in bio
submit (maybe the bio_associate_blkcg/bio_associate_current callers do sumbit
always, but I didn't audit yet).

bio_associate_current is only called from blk_throtl_assoc_bio, which
is only called from blk_throtl_bio, which is only called from
blkcg_bio_issue_check, which is only called from
generic_make_request_checks, which is only called from
generic_make_request, which at that point consumes the bio from the
callers perspective.

bio_associate_blkcg might be a different story, but then we should
treat both very differently.

The other reason is I'd like
blk_throtl_bio_endio is only called once for the whole bio not for splitted
bio, so this depends on bio_free to free cgroup info for chained bio which
always does bio_put.

Then we'll need to fix that.  We really should not require every
caller of bio_init to pair it with a new uninit call, which would be
a whole lot more work.