On 12/6/18 8:09 PM, Jianchao Wang wrote: > Hi Jens > > Please consider this patchset for 4.21. > > It refactors the code of issue request directly to unify the interface > and make the code clearer and more readable. > > This patch set is rebased on the recent for-4.21/block and add the 1st > patch which inserts the non-read-write request to hctx dispatch > list to avoid to involve merge and io scheduler when bypass_insert > is true, otherwise, inserting is ignored, BLK_STS_RESOURCE is returned > and the caller will fail forever. > > The 2nd patch refactors the code of issue request directly to unify the > helper interface which could handle all the cases. > > The 3rd patch make blk_mq_sched_insert_requests issue requests directly > with 'bypass' false, then it needn't to handle the non-issued requests > any more. > > The 4th patch replace and kill the blk_mq_request_issue_directly. Sorry to keep iterating on this, but let's default to inserting to the dispatch list if we ever see busy from a direct dispatch. I'm fine with doing that for 4.21, as suggested by Ming, I just didn't want to fiddle with it for 4.20. This will prevent any merging on the request going forward, which I think is a much safer default. You do this already for some cases. Let's do it unconditionally for a request that was ever subjected to ->queue_rq() and we didn't either error or finish after the fact. -- Jens Axboe
