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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 9212BC04EB8 for ; Mon, 10 Dec 2018 15:11:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6008520672 for ; Mon, 10 Dec 2018 15:11:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6008520672 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727156AbeLJPLy (ORCPT ); Mon, 10 Dec 2018 10:11:54 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:37844 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726602AbeLJPLy (ORCPT ); Mon, 10 Dec 2018 10:11:54 -0500 Received: by mail-qk1-f194.google.com with SMTP id 131so6641563qkd.4 for ; Mon, 10 Dec 2018 07:11:53 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=EZEXqVsGlcWwd+zxCX0Sx+FyYEo0QQyyCphOF1axsUM=; b=oT+uaqULXQs/ZfodZoQCBxoaHYN2aWAs44NjkxiniK8kvInp6fq0JKXWHl34JP0vAF GzbDHpIFLGTdJb0UHvNb6M6Cpgi8w328x/bTUm4rwzs4qUruogCmdgz0Uz4FyKDm8RxQ Me9PTmQl6bWovwce41HnP3wa5iMc1t4FuuoTJP/XDWzZ6sgRfSWFruyumXlsvl04kGsw cvMy+4TrH3+UuYEeDvTtuIperQ527PxItqHGEZ8AhmpzdI1+Zwy9vKa++jx7/EfcWEN+ EZeqiHWaP6CCdKdq+pwjFMtka/9v4gXt8IG7iDY4cQKRrYAZ+jSPx219ollVpgX8AW9G fpCQ== X-Gm-Message-State: AA+aEWasQuUAVEErU3lXnhS+pAkJZKzkMGFzJ4WFCH9rddTuJhTXFbY3 7mSls85Id0sDHRKlAwa6tYOZkKl1Ezg= X-Google-Smtp-Source: AFSGD/WHiYHLzjbxErlxVHpXTG9zIZJMtMNWvhpF/aOk+de5i1iTqzMUoE+6xH+HpcOx7hVYXSuV+w== X-Received: by 2002:a37:18e5:: with SMTP id 98mr11498917qky.333.1544454713424; Mon, 10 Dec 2018 07:11:53 -0800 (PST) Received: from loberhel74 (035-134-022-126.static.chtrptr.net. [35.134.22.126]) by smtp.gmail.com with ESMTPSA id z8sm8505476qth.34.2018.12.10.07.11.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 10 Dec 2018 07:11:52 -0800 (PST) Message-ID: <1544454711.18488.1.camel@redhat.com> Subject: Re: [PATCH] block: Restore tape support From: Laurence Oberman To: Christoph Hellwig , Bart Van Assche Cc: Jens Axboe , linux-block@vger.kernel.org, Todd Aiken , Keith Busch , stable@vger.kernel.org Date: Mon, 10 Dec 2018 10:11:51 -0500 In-Reply-To: <20181210111729.GA21553@lst.de> References: <20181210030814.13235-1-bvanassche@acm.org> <20181210111729.GA21553@lst.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6 (3.22.6-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, 2018-12-10 at 12:17 +0100, Christoph Hellwig wrote: > On Sun, Dec 09, 2018 at 07:08:14PM -0800, Bart Van Assche wrote: > > According to what I found in > > https://bugzilla.kernel.org/show_bug.cgi?id=201935 patch "block: > > Clear > > kernel memory before copying to user" broke tape access. Hence > > revert > > that patch. > > This looks wrong.  The patch from Keith is obviously correct for > normal usage of bio_copy_user_iov.  The SCSI tape drivers use the > somewhat odd null_mapped case, so we probably need to refine the > checks > for that a bit. I am going to look into that, just connected a tape device so I can reproduce and then see what we need to make it more specific in the st driver. I may need help from folks who understand the bio stuff better than I do. Back when I have more. Regards Laurence