From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 931E4C433EF for ; Thu, 21 Oct 2021 15:17:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C70260EB8 for ; Thu, 21 Oct 2021 15:17:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230000AbhJUPTr (ORCPT ); Thu, 21 Oct 2021 11:19:47 -0400 Received: from verein.lst.de ([213.95.11.211]:47056 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230103AbhJUPTr (ORCPT ); Thu, 21 Oct 2021 11:19:47 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id ECAB568BEB; Thu, 21 Oct 2021 17:17:28 +0200 (CEST) Date: Thu, 21 Oct 2021 17:17:28 +0200 From: Christoph Hellwig To: Jens Axboe Cc: Christoph Hellwig , martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: please revert the UFS HPB support Message-ID: <20211021151728.GA31600@lst.de> References: <20211021144210.GA28195@lst.de> <84fac5a3-135a-2ac8-5929-a1031a311cb7@kernel.dk> <20211021151520.GA31407@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211021151520.GA31407@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 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.