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 6DE6EC433F5 for ; Tue, 26 Oct 2021 17:25:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53E416103C for ; Tue, 26 Oct 2021 17:25:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237777AbhJZR2B (ORCPT ); Tue, 26 Oct 2021 13:28:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237780AbhJZR15 (ORCPT ); Tue, 26 Oct 2021 13:27:57 -0400 Received: from mail-il1-x133.google.com (mail-il1-x133.google.com [IPv6:2607:f8b0:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0E66C061745 for ; Tue, 26 Oct 2021 10:25:33 -0700 (PDT) Received: by mail-il1-x133.google.com with SMTP id w10so18150746ilc.13 for ; Tue, 26 Oct 2021 10:25:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=eRyfWMKtLbbwfUe78MgpwTKyNG2DhD4qRhOw6hMcN3A=; b=6jR4PITb12iW50VjhwN5AsYzKaM1pZkI7vhoOuk7YZuycenGt6jZOXKntSQ82ybm9u N/bHrqh23MX6Xbb1zq1XV/AISB5S2oGkQoMa4j3WaBrCig/EaZgRUUknI9WaeBz3Y3ri VNwihD+NCHntcFYCBBlJPsj+c7oLrWFI1nG7sul/68ihSStBAJ63dRmlzLd3K/JXjalV G80qv3xKqEDnQs6L3a6Z9xEYi0a4PjC2uliRki6LTViBDM1It97emYni3JZ31+Oe7c0L SUo+0NyVf5G00prYJPUskySyQHmaCuzPuqVLCGUza3yxmq4VHC04mjhqSi79ysXuKrOe M5RA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=eRyfWMKtLbbwfUe78MgpwTKyNG2DhD4qRhOw6hMcN3A=; b=FVtl5807LfdfyesLS+bpAPQtd9a9Eo/ev3YKhXwF0aQKANZnFOBdGDHUXP6r9HzMn9 CmB8ZU6hp407N7n+TlG3qSs5KnBmtd7hgFCrrgH3+PSP81xCE9bYLe/frjGR/c2xCxAb xpoRpAvivwO51sMyhe4LXc38oF9/Mb3ufXm64Z9zyiOmoiFHtXvzDgUX5GmjmNT5bPKF 0ccKEvP+Dqn32p2DJDOOzgjlXJAJunF/Y2TyZ+s5MMHrDVwLkS8Vtl4IFm8P4Gi2qqEb ltd9esEVGvSHrAK5QtF9vGL2Fpn7mLJIEd+v9xd+69XVknzQBHN0m+SeL7w6N29WLPRx Kdvg== X-Gm-Message-State: AOAM532Lgse9dk3MenKtGtu2EleGS1EkSOlEKwAv6c+MRHdet+lxi4VL zDMZplMoW1KQZwDhzTpIBoS6ex5FwUQbew== X-Google-Smtp-Source: ABdhPJysundZiuH9mj4mrKaC9yQ7XDwTmT9Ji3/Q7aROlf90iW2iA+Fsqc4h7GsO1a1/+gcAYeqynw== X-Received: by 2002:a05:6e02:10c7:: with SMTP id s7mr15851132ilj.172.1635269132859; Tue, 26 Oct 2021 10:25:32 -0700 (PDT) Received: from [192.168.1.30] ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id 81sm10218112iou.21.2021.10.26.10.25.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Oct 2021 10:25:32 -0700 (PDT) Subject: Re: [PATCH] scsi: ufs: mark HPB support as BROKEN To: James Bottomley , Bart Van Assche , Christoph Hellwig , martin.petersen@oracle.com Cc: alim.akhtar@samsung.com, avri.altman@wdc.com, linux-scsi@vger.kernel.org, linux-block@vger.kernel.org References: <20211026071204.1709318-1-hch@lst.de> <99641481-523a-e5a9-db48-dac2b547b4bd@acm.org> <7ed11ee1f8beca9a27c0cb2eb0dcea4dbd557961.camel@HansenPartnership.com> From: Jens Axboe Message-ID: <870e986c-08dd-2fa2-a593-0f97e10d6df5@kernel.dk> Date: Tue, 26 Oct 2021 11:25:31 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <7ed11ee1f8beca9a27c0cb2eb0dcea4dbd557961.camel@HansenPartnership.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 10/26/21 11:19 AM, James Bottomley wrote: > On Tue, 2021-10-26 at 09:36 -0700, Bart Van Assche wrote: >> On 10/26/21 12:12 AM, Christoph Hellwig wrote: >>> The HPB support added this merge window is fundanetally flawed as >>> it >> ^^^^^^^^^^^^ >> fundanetally -> >> fundamentally >> >> Since the implementation can be reworked not to use >> blk_insert_cloned_request() I'm not sure using the word >> "fundamentally" is appropriate. > > I'm not so sure about that. The READ BUFFER implementation runs from a > work queue and looks fine. The WRITE BUFFER implementation is trying > to spawn a second command to precede the queued command which is a > fundamental problem for the block API. It's not clear to me that the > WRITE BUFFER can be fixed because of the tying to the sent command ... > but like I said, the standard is proprietary so I can't look at it to > see if there are alternative ways of achieving the same effect. Is there a model in which this can actually work? If not, or if we aren't sure, I think we'd be better off just reverting the parts involved with that block layer misuse. Simply marking it broken is a half measure that doesn't really solve anything (except send a message). IMHO, it should be reverted and the clone usage we currently export be moved into dm for now. That'll prevent further abuse of this in the future. -- Jens Axboe