From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A8DCA3D76; Tue, 2 Sep 2025 08:25:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756801562; cv=none; b=DnIp8/kBy5wJzWShAiKbZrZpskR51skXisnMWrME8xX3oAbCdcMf7gwzu8y2TVyMqZeh5ZfdJ5JrwSoa0BSi7dp+uI78VvI9XSwoNJY5SRyjR15d/EwAecZLHpEzSJT+UNhIwMA3cQepPW8wnIIv/cY143LOP87WtPkxAq+QOcQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756801562; c=relaxed/simple; bh=9CfBYNh+4iSPQYtdoH6uGIT6doeJg35kpISD+8fFxJg=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=nu0munmAKCZ1hv0piIyCAXyQzI5V1CAAjSzarzpHYkvxKcy5XK+ZPXjbYwVvLbyccIa80R/tI+E9G6H8pzbL029a7fJ10Sg6lRExB7sZyShHlzdVm4jeD5vWnTIjX//8+c6uUaB6rKCTc1IkWhLGdz5omKxGpUcgBlIvcKxwFms= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4cGJjK0rjbzKHNRN; Tue, 2 Sep 2025 16:25:57 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id EB89D1A0DCD; Tue, 2 Sep 2025 16:25:56 +0800 (CST) Received: from [10.174.179.143] (unknown [10.174.179.143]) by APP4 (Coremail) with SMTP id gCh0CgCn8IwSqrZo0Mp+BA--.22340S3; Tue, 02 Sep 2025 16:25:56 +0800 (CST) Subject: Re: [PATCH RFC 4/7] md/raid10: convert read/write to use bio_submit_split() To: John Garry , Christoph Hellwig , Yu Kuai Cc: anthony , colyli@kernel.org, hare@suse.de, tieren@fnnas.com, axboe@kernel.dk, tj@kernel.org, josef@toxicpanda.com, song@kernel.org, akpm@linux-foundation.org, neil@brown.name, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-raid@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com, "yukuai (C)" References: <20250825093700.3731633-1-yukuai1@huaweicloud.com> <20250825093700.3731633-5-yukuai1@huaweicloud.com> <6c6b183a-bce7-b01c-8749-6e0b5a078384@huaweicloud.com> <835fe512-4cff-4130-8b67-d30b91d95099@youngman.org.uk> From: Yu Kuai Message-ID: <4a360dec-79ff-1444-6c1e-830f43b13c2f@huaweicloud.com> Date: Tue, 2 Sep 2025 16:25:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgCn8IwSqrZo0Mp+BA--.22340S3 X-Coremail-Antispam: 1UD129KBjvJXoW7Ar47ur4kKFW3GF4UCFW7Jwb_yoW8Gw18pF Z2v3ZYyr4qkF10v3Z7Zw4IqFyrt3yfA34UJFW5JrWFkFyY9FyftFs7GFZ0gFy29ryxJ3sF 9ayYgFykGFs8AaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBF14x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvEwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2ka 0xkIwI1lc7I2V7IY0VAS07AlzVAYIcxG8wCY1x0262kKe7AKxVW8ZVWrXwCF04k20xvY0x 0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E 7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_WrylIxkGc2Ij64vIr41lIxAIcV C0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF 04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7 CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0pRHUDLUUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Hi, 在 2025/09/02 14:58, John Garry 写道: > On 02/09/2025 07:30, Christoph Hellwig wrote: >> On Tue, Sep 02, 2025 at 07:18:01AM +0100, John Garry wrote: >>> BTW, do we realistically expect atomic writes HW support and bad >>> blocks ever >>> to meet? >> >> That's the point I'm trying to make.  bad block tracking is stupid >> with modern hardware.  Both SSDs and HDDs are overprovisioned on >> physical "blocks", and once they run out fine grained bad block tracking >> is not going to help.  І really do not understand why md even tries >> to do this bad block tracking, > > Just because they can try to deal with bad blocks for some (mirroring) > personalities, I suppose. I agree it's useless for enterprise storage, however, for personal storage, there are lots of users using cost-effective (often aging) disks, badblocks tracking can reduce the risk of data lost, and make sure these devices will not become waste. > >> but claiming to support atomic writes >> while it does is actively harmful. >> > > There does not look to be some switch to turn off bad block support. > That's from briefly checking raid10.c anyway. Kuai, any thoughts on > whether we should allow this to be disabled? > I remember that I used to suggest always enable failfast in this case, and badblocks can be bypassed. Anyway, I think it's good to allow this to be disabled, it will behave very similar to failfast. Thanks, Kuai > Thanks, > John > > . >