On 10/25/21 11:26 AM, Greg Kroah-Hartman wrote:
Is there a link to where the HPB developer said they would look into this? Perhaps until that happens this should be marked as BROKEN?
Hi Greg, Daejun wrote the following on Thursday: "I will find out how to make the HPB code without blk_insert_cloned_request() API." Unfortunately that email was sent as MIME-encoded so it was only received by the people Cc-ed on that email and has not been archived by any of the websites that archives linux-scsi or linux-block emails. The email that I received is available below. I think it is fine to make this email public given the presence of two mailing lists in the Cc-list. Thanks, Bart. -------- Forwarded Message -------- Subject: Re: please revert the UFS HPB support Date: Fri, 22 Oct 2021 07:41:43 +0900 From: 박대준 <pdaejun@xxxxxxxxx> To: Bart Van Assche <bvanassche@xxxxxxx> CC: Christoph Hellwig <hch@xxxxxx>, Jens Axboe <axboe@xxxxxxxxx>, martin.petersen@xxxxxxxxxx, linux-scsi@xxxxxxxxxxxxxxx, linux-block@xxxxxxxxxxxxxxx, Daejun Park <daejun7.park@xxxxxxxxxxx>, Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Hi Bart, 2021년 10월 22일 (금) 오전 1:23, Bart Van Assche <bvanassche@xxxxxxx <mailto:bvanassche@xxxxxxx>>님이 작성: On 10/21/21 8:17 AM, Christoph Hellwig wrote: > On Thu, Oct 21, 2021 at 05:15:20PM +0200, Christoph Hellwig wrote: >>>> I just noticed the UFS HPB support landed in 5.15, and just as >>>> before it is completely broken by allocating another request on >>>> the same device and then reinserting it in the queue. It is bad >>>> enough that we have to live with blk_insert_cloned_request for >>>> dm-mpath, but this is too big of an API abuse to make it into >>>> a release. We need to drop this code ASAP, and I can prepare >>>> a patch for that. >>> >>> That sounds awful, do you have a link to the offending commit(s)? >> >> I'll need to look for it, busy in calls right now, but just grep for >> blk_insert_cloned_request. > > Might as well finish the git blame: > > commit 41d8a9333cc96f5ad4dd7a52786585338257d9f1 > Author: Daejun Park <daejun7.park@xxxxxxxxxxx <mailto:daejun7.park@xxxxxxxxxxx>> > Date: Mon Jul 12 18:00:25 2021 +0900 > > scsi: ufs: ufshpb: Add HPB 2.0 support > > Version 2.0 of HBP supports reads of varying sizes from 4KB to 1MB. > > A read operation <= 32KB is supported as single HPB read. A read between > 36KB and 1MB is supported by a combination of write buffer command and HPB > read command to deliver more PPN. The write buffer commands may not be > issued immediately due to busy tags. To use HPB read more aggressively, the > driver can requeue the write buffer command. The requeue threshold is > implemented as timeout and can be modified with requeue_timeout_ms entry in > sysfs. (+Daejun) Daejun, can the HPB code be reworked such that it does not use blk_insert_cloned_request()? I'm concerned that if the HPB code is not reworked that it will be removed from the upstream kernel. Thanks, Bart. I will find out how to make the HPB code without blk_insert_cloned_request() API. Thanks, Daejun
