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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 54E5DC46470 for ; Tue, 7 Aug 2018 18:53:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 198AF2174B for ; Tue, 7 Aug 2018 18:53:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 198AF2174B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S2404039AbeHGVJF (ORCPT ); Tue, 7 Aug 2018 17:09:05 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33212 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404017AbeHGVJF (ORCPT ); Tue, 7 Aug 2018 17:09:05 -0400 Received: from localhost (unknown [194.244.16.108]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 7F4B0D07; Tue, 7 Aug 2018 18:53:21 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Snitzer , Sagi Grimberg , Ilya Dryomov , Jens Axboe , Zdenek Kabelac , Linus Torvalds Subject: [PATCH 4.17 15/18] Partially revert "block: fail op_is_write() requests to read-only partitions" Date: Tue, 7 Aug 2018 20:51:18 +0200 Message-Id: <20180807172313.528528886@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180807172312.964272530@linuxfoundation.org> References: <20180807172312.964272530@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 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 4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Linus Torvalds commit a32e236eb93e62a0f692e79b7c3c9636689559b9 upstream. It turns out that commit 721c7fc701c7 ("block: fail op_is_write() requests to read-only partitions"), while obviously correct, causes problems for some older lvm2 installations. The reason is that the lvm snapshotting will continue to write to the snapshow COW volume, even after the volume has been marked read-only. End result: snapshot failure. This has actually been fixed in newer version of the lvm2 tool, but the old tools still exist, and the breakage was reported both in the kernel bugzilla and in the Debian bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200439 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=900442 The lvm2 fix is here https://sourceware.org/git/?p=lvm2.git;a=commit;h=a6fdb9d9d70f51c49ad11a87ab4243344e6701a3 but until everybody has updated to recent versions, we'll have to weaken the "never write to read-only partitions" check. It now allows the write to happen, but causes a warning, something like this: generic_make_request: Trying to write to read-only block-device dm-3 (partno X) Modules linked in: nf_tables xt_cgroup xt_owner kvm_intel iwlmvm kvm irqbypass iwlwifi CPU: 1 PID: 77 Comm: kworker/1:1 Not tainted 4.17.9-gentoo #3 Hardware name: LENOVO 20B6A019RT/20B6A019RT, BIOS GJET91WW (2.41 ) 09/21/2016 Workqueue: ksnaphd do_metadata RIP: 0010:generic_make_request_checks+0x4ac/0x600 ... Call Trace: generic_make_request+0x64/0x400 submit_bio+0x6c/0x140 dispatch_io+0x287/0x430 sync_io+0xc3/0x120 dm_io+0x1f8/0x220 do_metadata+0x1d/0x30 process_one_work+0x1b9/0x3e0 worker_thread+0x2b/0x3c0 kthread+0x113/0x130 ret_from_fork+0x35/0x40 Note that this is a "revert" in behavior only. I'm leaving alone the actual code cleanups in commit 721c7fc701c7, but letting the previously uncaught request go through with a warning instead of stopping it. Fixes: 721c7fc701c7 ("block: fail op_is_write() requests to read-only partitions") Reported-and-tested-by: WGH Acked-by: Mike Snitzer Cc: Sagi Grimberg Cc: Ilya Dryomov Cc: Jens Axboe Cc: Zdenek Kabelac Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- block/blk-core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2174,11 +2174,12 @@ static inline bool bio_check_ro(struct b if (part->policy && op_is_write(bio_op(bio))) { char b[BDEVNAME_SIZE]; - printk(KERN_ERR + WARN_ONCE(1, "generic_make_request: Trying to write " "to read-only block-device %s (partno %d)\n", bio_devname(bio, b), part->partno); - return true; + /* Older lvm-tools actually trigger this */ + return false; } return false;