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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 6D807C43142 for ; Thu, 2 Aug 2018 13:31:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23E892150E for ; Thu, 2 Aug 2018 13:31:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="aMYiAP5e" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23E892150E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387601AbeHBPWa (ORCPT ); Thu, 2 Aug 2018 11:22:30 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:43923 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387569AbeHBPWa (ORCPT ); Thu, 2 Aug 2018 11:22:30 -0400 Received: by mail-io0-f194.google.com with SMTP id y10-v6so1777460ioa.10; Thu, 02 Aug 2018 06:31:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0pHMjIl6Vb3EaDIrGcHCh8h5y95IxbFQUCGvk51MQuA=; b=aMYiAP5eD+YvuS/s6Mym/DoyDbW7LlcDVkyKTegf6Tzbj/iPz7LOL9tAzeVlz30inR itdAbYPaQxOTlS4LjdLg/Agrd8eykgpe2xsUVPBo/VBmsGeLADPwvK85DkAoLnBaFIf4 lFZVIcjOjlq3XOA2q13xHqKGzRnW9n/Q+m37/YVQheljeN9uYAljq+qvmVX6Flfg4Pzf ndbyw6Z0YwyWK7xprvxxkXkWqMfPoKCX/Dqn0Fek0RGdG7MZk1hBEZsYu4RXZrQU9WBt 8+NDF1tNyb7MtLuze0ElJFg8hSOO1JBO0e0hKIrkCvp9R7IzuCi4qrJ6JrRVtNOOJAYI PIaw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0pHMjIl6Vb3EaDIrGcHCh8h5y95IxbFQUCGvk51MQuA=; b=VMxrF/yWeJdBCwk6bQa9Y0dQ7CT3R+busCXMZSEzyYsBT+JUsa4QY9lAsRndtnWk+n EPHNXW6kEPEUAET5mCzxTIoKHVhekNiBQJkyI4A0Mr2TbbTk/Lj6WsGZfeNKg6mNxJql CO8Xmie88soD7gy9k0HU+BOFuuPzirr5Ma/mDsn6o11DZrXt62wWZP2vmOppuua0qZpB /CNZNMV9ba/jL7UEhTIgKgsxWBl7kE3ppKy/qXaOhSouiv1sx0TzHWuSJ5j9jkyaqiHJ viO+HThzf0hUJgg18ilK6UUEYsQxq9Qi3F4aLTfb6hQclsN2c10s/Um31wduqBC1C/mC xROQ== X-Gm-Message-State: AOUpUlEw/4V3t7+KJWwAeQJdvn3nDxsBjWVigvYGqU5C3NjFAPNz3XeY uZg0lmBzRfG8WhB+nTmocWMzadEt+wfczih+RiY= X-Google-Smtp-Source: AA+uWPwD1Y8d67O6AK1SPI4au+aKG/ADzPy2RwHC5UpDNFEGHljRv7C4bgYSQ56GfI1T2atrwaSIts7rlgl0XFJkI+8= X-Received: by 2002:a6b:b5ca:: with SMTP id e193-v6mr2332128iof.153.1533216676133; Thu, 02 Aug 2018 06:31:16 -0700 (PDT) MIME-Version: 1.0 References: <226835ba-2197-b850-6e5b-8ba14f7fd016@torlan.ru> In-Reply-To: <226835ba-2197-b850-6e5b-8ba14f7fd016@torlan.ru> From: Ilya Dryomov Date: Thu, 2 Aug 2018 15:31:05 +0200 Message-ID: Subject: Re: LVM snapshot broke between 4.14 and 4.16 To: wgh@torlan.ru Cc: Jens Axboe , linux-block , linux-kernel@vger.kernel.org, Sagi Grimberg , Mike Snitzer , dm-devel@redhat.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 2, 2018 at 2:26 PM WGH wrote: > > (I originally reported this problem here: > https://bugzilla.kernel.org/show_bug.cgi?id=200439) > > When I updated from 4.14 to 4.16, my LVM snapshotting script broke for > no apparent reason. > > My script has the following line, and it fails like this: > + lvcreate --size 5G --snapshot --name snap0 --permission r > /dev/mapper/vg0-lvol_rootfs > device-mapper: create ioctl on > vg0-snap0-cowLVM-sDdIeh9cecWdaNyRfZC31mxgfwTa4sOeHMJXVOykGVRtfP6Aii7IHvwS066AOLOM-cow > failed: Device or resource busy > Failed to lock logical volume vg0/lvol_rootfs. > Aborting. Manual intervention required. > > At the same time, some errors appear in dmesg as well: > [ 26.145279] generic_make_request: Trying to write to read-only > block-device dm-3 (partno 0) > [ 26.145288] device-mapper: persistent snapshot: write_header failed > [ 26.145847] device-mapper: table: 253:4: snapshot: Failed to read > snapshot metadata > [ 26.145851] device-mapper: ioctl: error adding target to table > > I bisected the vanilla kernel, and the first bad commit is > [721c7fc701c71f693307d274d2b346a1ecd4a534] block: fail op_is_write() > requests to read-only partitions Adding Mike and dm-devel. >From a quick look, --permission r sets DM_READONLY_FLAG, which makes dm mark the disk read-only with set_disk_ro(dm_disk(md), 1) in do_resume(). A bit later it tries to write to the disk from write_header(): return chunk_io(ps, ps->header_area, 0, REQ_OP_WRITE, 0, 1); Thanks, Ilya