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 X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDF5FC4363D for ; Thu, 1 Oct 2020 02:44:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8074B21531 for ; Thu, 1 Oct 2020 02:44:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725800AbgJACoF (ORCPT ); Wed, 30 Sep 2020 22:44:05 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:35855 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725372AbgJACoF (ORCPT ); Wed, 30 Sep 2020 22:44:05 -0400 Received: by mail-pf1-f196.google.com with SMTP id d9so3021351pfd.3 for ; Wed, 30 Sep 2020 19:44:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=Ke0TKP8lQfI5Dj3EHGvZ26tLHgEa3R4DcSNMY/KkU18=; b=AV0HF5IKd18TOYrLUkWqfVD5Q4DCjcBCam3d9mFbe6zOROjZOkbmr5zmIX/rCiFUSr TjbySZ2h8WUi8LJc3ZsLXZOmZjyt8bBDUUGoXgK86r6La/HxMCsl1VKkuWhtz/W0XbVa ZnXBfbjOdlBgWPDgFsXiQUy54NK63ZGEZaFSZ7tmX8djaauyonD1fABcUxHNaDj0RvpS sl7uMiWlFaFMGVy2kRjIgFpKVQsuz87i/ydUnlCQ1ZLv9Qy7zqAiEFR7kcDdZnanVmSl 0HSfjdIcCAKacUysNaI8UHxMMOCM2B6tZw64Z3Ls1BIpEx83CbqU50CdRkT1MVF4W971 tYRQ== X-Gm-Message-State: AOAM532lLYn3ochXDeN3dQA4TuhZYvcdfECJoIUiIgvZ8MFEL4hu0Clk wqIKfYdaAy54qznMno8Pvf3pQNls7G4= X-Google-Smtp-Source: ABdhPJxdY0wQ96sw5VKR2JbB+8qLanEuZcq6XLAxzCUJrLdhfXEBGFl56/9M8NE6v/Ardg8rP+FnFw== X-Received: by 2002:a62:fc51:0:b029:142:4506:9a7b with SMTP id e78-20020a62fc510000b029014245069a7bmr5026969pfh.28.1601520243498; Wed, 30 Sep 2020 19:44:03 -0700 (PDT) Received: from ?IPv6:2601:647:4000:d7:74c0:38d3:8092:91f1? ([2601:647:4000:d7:74c0:38d3:8092:91f1]) by smtp.gmail.com with ESMTPSA id q24sm3926190pfs.206.2020.09.30.19.44.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Sep 2020 19:44:02 -0700 (PDT) Subject: Re: [PATCH 2/4] scsi_dh_alua: return BLK_STS_AGAIN for ALUA transitioning state To: Hannes Reinecke , "Martin K. Petersen" Cc: Christoph Hellwig , James Bottomley , linux-scsi@vger.kernel.org References: <20200930080256.90964-1-hare@suse.de> <20200930080256.90964-3-hare@suse.de> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: <10c29e0a-688c-9cc0-3329-8f97300b8827@acm.org> Date: Wed, 30 Sep 2020 19:44:01 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200930080256.90964-3-hare@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2020-09-30 01:02, Hannes Reinecke wrote: > When the ALUA state indicates transitioning we should not retry > the command immediately, but rather complete the command with > BLK_STS_AGAIN to signal the completion handler that it might > be retried. > This allows multipathing to redirect the command to another path > if possible, and avoid stalls during lengthy transitioning times. > > Signed-off-by: Hannes Reinecke > --- > drivers/scsi/device_handler/scsi_dh_alua.c | 2 +- > drivers/scsi/scsi_lib.c | 5 +++++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c > index 308bda2e9c00..a68222e324e9 100644 > --- a/drivers/scsi/device_handler/scsi_dh_alua.c > +++ b/drivers/scsi/device_handler/scsi_dh_alua.c > @@ -1092,7 +1092,7 @@ static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req) > case SCSI_ACCESS_STATE_LBA: > return BLK_STS_OK; > case SCSI_ACCESS_STATE_TRANSITIONING: > - return BLK_STS_RESOURCE; > + return BLK_STS_AGAIN; > default: > req->rq_flags |= RQF_QUIET; > return BLK_STS_IOERR; > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index f0ee11dc07e4..b628aa0d824c 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1726,6 +1726,11 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, > scsi_device_blocked(sdev)) > ret = BLK_STS_DEV_RESOURCE; > break; > + case BLK_STS_AGAIN: > + scsi_req(req)->result = DID_BUS_BUSY << 16; > + if (req->rq_flags & RQF_DONTPREP) > + scsi_mq_uninit_cmd(cmd); > + break; > default: > if (unlikely(!scsi_device_online(sdev))) > scsi_req(req)->result = DID_NO_CONNECT << 16; Hi Hannes, What will happen if all remote ports have the state "transitioning"? Does the above code resubmit a request immediately in that case? Can this cause spinning with 100% CPU usage if the ALUA device handler notices the transitioning state before multipathd does? Thanks, Bart.