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=-8.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 5DB57C07E99 for ; Mon, 5 Jul 2021 13:02:38 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 05DCB6144E for ; Mon, 5 Jul 2021 13:02:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 05DCB6144E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625490156; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=l6HYUmoUG9RTn7HHSgyoOyJlFBwpENOvtYwWhmcEYYA=; b=jV+bmQsqusFhzE0Wo03LvEzFT1pvsx61i3WWvATvsPtkJUP3a5Kt48N/G6VxVdDn1JCqUP qWLeSV1XGe+OobBgzQVuAt92weMv5Ewu3C4jV73RbDb0u32mpZknUbkwPesAbb6SPhJpUp M4ZpDXeJ2Zo9ghUAiMrz+MMF7yLc260= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-515-LRlRAvWpMK2zZDIeFxm0Uw-1; Mon, 05 Jul 2021 09:02:35 -0400 X-MC-Unique: LRlRAvWpMK2zZDIeFxm0Uw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 903D956B2C; Mon, 5 Jul 2021 13:02:29 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7259860C0F; Mon, 5 Jul 2021 13:02:27 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 46C121809C99; Mon, 5 Jul 2021 13:02:20 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 165D2Hxv018626 for ; Mon, 5 Jul 2021 09:02:17 -0400 Received: by smtp.corp.redhat.com (Postfix) id 31A2F2023437; Mon, 5 Jul 2021 13:02:17 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast01.extmail.prod.ext.rdu2.redhat.com [10.11.55.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2C63C2023434 for ; Mon, 5 Jul 2021 13:02:13 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-2.mimecast.com [207.211.31.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D87AD89C7DC for ; Mon, 5 Jul 2021 13:02:13 +0000 (UTC) Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-251-6T2nDMfuMsqoQfxaLF3NCg-1; Mon, 05 Jul 2021 09:02:12 -0400 X-MC-Unique: 6T2nDMfuMsqoQfxaLF3NCg-1 Received: by mail-wm1-f69.google.com with SMTP id z4-20020a1ce2040000b02901ee8d8e151eso9873644wmg.1 for ; Mon, 05 Jul 2021 06:02:12 -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:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=EQiaDZSDRoWhnvLd0y+F7CVOe8BAX1HmtgpDqCLODno=; b=r/510Z33qIwb5WabACn+funvWrSg8QwM5TjbFYS/A2ffs/3rj6rnVYy95TJDijlpB4 8eIEtDhY+s9ZO2Z2MkNIJRuSLxKQW3a2B5Qt+SzgYZzDWuX2+x44vMwAnXe6Y5v6Cjsh Zbcwblf4V6DSaVCGNJWqEJGVFpLR8W6KCBIW0zmPUisiDM7Q0mSETR/Kbh3Aci1z8CVl wEYQq5HiM6baAdthfWQVbQz0ntX3yLup9OXtZizvzCVO0jzmoPY4UVAwiUyc4Akr6unt hNn/VBB7KyMp2DQqN2HLFzvM+plUgFHRGwbc9zR/nijgvaLxwc0z5IPf4yRfmC+u/Y75 Dn0w== X-Gm-Message-State: AOAM533munhsU9i68nXnSrYcrKrjZIB/jmznP2OmBn5eXNpuTv9OZfV9 msMuzALXMflHK8ZhAjzo8o2t3MdAWSZ0juh7+IJwQkqKzFL10UwuEbEwFTDerxWJVwuXgPdSGdR HBoFdd8pIDexpq8Y= X-Received: by 2002:a7b:ca43:: with SMTP id m3mr14772428wml.74.1625490131334; Mon, 05 Jul 2021 06:02:11 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzS6R45eQdBafjJCfhd1vm8LmWsahyCdE9gLBl2N2UbSQMBfrvMPQtX8pBLO/KLwWonQWqk0g== X-Received: by 2002:a7b:ca43:: with SMTP id m3mr14772386wml.74.1625490130998; Mon, 05 Jul 2021 06:02:10 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id 16sm12186756wmk.18.2021.07.05.06.02.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Jul 2021 06:02:09 -0700 (PDT) To: Martin Wilck , Christoph Hellwig References: <20210628151558.2289-1-mwilck@suse.com> <20210628151558.2289-4-mwilck@suse.com> <20210701075629.GA25768@lst.de> <20210701113442.GA10793@lst.de> <003727e7a195cb0f525cc2d7abda3a19ff16eb98.camel@suse.com> From: Paolo Bonzini Message-ID: Date: Mon, 5 Jul 2021 15:02:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <003727e7a195cb0f525cc2d7abda3a19ff16eb98.camel@suse.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-loop: dm-devel@redhat.com Cc: linux-scsi@vger.kernel.org, Daniel Wagner , Mike Snitzer , emilne@redhat.com, linux-block@vger.kernel.org, dm-devel@redhat.com, "Martin K. Petersen" , nkoenig@redhat.com, Bart Van Assche , Alasdair G Kergon Subject: Re: [dm-devel] [PATCH v5 3/3] dm mpath: add CONFIG_DM_MULTIPATH_SG_IO - failover for SG_IO X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" On 02/07/21 16:21, Martin Wilck wrote: >> SG_IO gives you raw access to the SCSI logic unit, and you get to >> keep the pieces if anything goes wrong. > > That's a very fragile user space API, on the fringe of being useless > IMO. Indeed. If SG_IO is for raw access to an ITL nexus, it shouldn't be supported at all by mpath devices. If on the other hand SG_IO is for raw access to a LUN, there is no reason for it to not support failover. Paolo -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel