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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35837C77B7A for ; Wed, 31 May 2023 01:49:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232098AbjEaBty (ORCPT ); Tue, 30 May 2023 21:49:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44858 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233909AbjEaBtw (ORCPT ); Tue, 30 May 2023 21:49:52 -0400 Received: from out-1.mta0.migadu.com (out-1.mta0.migadu.com [IPv6:2001:41d0:1004:224b::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8515F113 for ; Tue, 30 May 2023 18:49:50 -0700 (PDT) Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1685497788; h=from:from: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; bh=u48UJmA/2Yjt1kKlLoKXVdzACrCJ2AOYz6a3+Scc6hM=; b=QQ/o6PusxfcxNV/jqDmr7ib7MPO7mmnIvGVQd3fIWB7KsmtqT9S7Xd6jKQnDyHaOXXHtlC dJIvk9B0YdH4Lumj32Lgwr7B+r2lLn4Gfs3sN7N+1cmSRQPp6ONX+J11oShzrx+6e9vpdx T5CFGOOhQEFykdQRL2v/Jd6sPN9DT90= Date: Wed, 31 May 2023 09:49:43 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v2] md/raid5: don't allow concurrent reshape with recovery Content-Language: en-US To: Yu Kuai , song@kernel.org, pmenzel@molgen.mpg.de Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, "yukuai (C)" References: <20230529133410.2125914-1-yukuai1@huaweicloud.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Guoqing Jiang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 5/31/23 09:22, Yu Kuai wrote: > Hi, > > 在 2023/05/31 9:06, Guoqing Jiang 写道: >> >> >> On 5/29/23 21:34, Yu Kuai wrote: >>> From: Yu Kuai >>> >>> Commit 0aecb06e2249 ("md/raid5: don't allow replacement while reshape >>> is in progress") fixes that replacement can be set if reshape is >>> interrupted, which will cause that array can't be assembled. I just pulled md tree, but can't find the commit id either in md-next or md-fixes . gjiang@pc:~/storage/md> git branch  master  md-fixes * md-next gjiang@pc:~/storage/md> git branch --contain 0aecb06e2249 error: malformed object name 0aecb06e2249 >>> There is a similar problem on the other side, if recovery is >>> interrupted, then reshape can start, which will cause the same problem. >>> >>> Fix the problem by not starting to reshape while recovery is still in >>> progress. >>> >>> Signed-off-by: Yu Kuai >>> --- >>> Changes in v2: >>>   - fix some typo in commit message. >>> >>>   drivers/md/raid5.c | 8 ++++++++ >>>   1 file changed, 8 insertions(+) >>> >>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c >>> index 8686d629e3f2..6615abf54d3f 100644 >>> --- a/drivers/md/raid5.c >>> +++ b/drivers/md/raid5.c >>> @@ -8525,6 +8525,7 @@ static int raid5_start_reshape(struct mddev >>> *mddev) >>>       struct r5conf *conf = mddev->private; >>>       struct md_rdev *rdev; >>>       int spares = 0; >>> +    int i; >>>       unsigned long flags; >>>       if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) >>> @@ -8536,6 +8537,13 @@ static int raid5_start_reshape(struct mddev >>> *mddev) >>>       if (has_failed(conf)) >>>           return -EINVAL; >>> +    /* raid5 can't handle concurrent reshape and recovery */ >>> +    if (mddev->recovery_cp < MaxSector) >>> +        return -EBUSY; >>> +    for (i = 0; i < conf->raid_disks; i++) >>> +        if (rdev_mdlock_deref(mddev, conf->disks[i].replacement)) >>> +            return -EBUSY; >>> + >> >> Does it mean reshape and recovery  can happen in parallel without the >> change? >> I really doubt about it given any kind of internal io (resync, >> reshape and recovery) >> is handled by resync thread. And IIUC either md_do_sync or >> md_check_recovery >> should avoid it, no need to do it in personality layer. >> > > They can't, in this case recovery is interrupted, then recovery can't > make progress, and md_check_recovery() will start reshape, and after > reshape is done, recovery will continue, and data will be corrupted > because raid456 reshape doesn't handle replacement. So, do reshape first then recovery, right? I don't see concurrent reshape and recovery happen based on your description, if concurrent reshape and recovery is possible then I believe we really have big trouble. > And by the way in raid456 is that if system reboot, this array can't be > assembled, raid5_run() will fail if reshape and replacement are both > set. Assemble an array need to read data from sb, I don't know which place record replacement, I probably misunderstand something. Thanks, Guoqing