From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 51B152E1723; Wed, 27 Aug 2025 07:32:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756279927; cv=none; b=EzMA8A1bEdB/qW6Zfx1/6+/OyOgTu1dvO3H13utfk5MgJBQE1NlnfHN9c7smyVrE7ZzV/osXHftZ0MQe67H8YAGDA+ewx2RNCUtazxaeAx+p0POqSFTAjgWzuR4tuWA4kMOhFAY1JkLSG5MK5nPwswtDf3hewGdL3ctDyUI6MXo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756279927; c=relaxed/simple; bh=m60YP2l0OQVjwwUvCpC26uRwuFUQ8d+ffT/0DA5nFwo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CndKMZIandrtw6IlfhgGGdvXF9qqdU32Ht+KDp4gEphEZli/uVK4g8pS+a+2Wr5y9ggjkBQtWrLSB+8VlD19T4aaawviznyjdw+zwE1yqjdiU5DSOTaKnG7ZJTgkFqeH9UJQKHzUNtprnkSUXbtWuSP9s7KyN4HSczH65iqib5Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=JZ4/k2a3; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="JZ4/k2a3" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=/U7TDdgVS0XTpH2wrHd6NGuad3QpZ7xAtceEl+MVTEg=; b=JZ4/k2a3nNOadUbaZYE/D0bAu6 mKeQBdWkdOBG+Gqmz49R058h9vKZZsKvN2ablsyK/nrxN4SPF8rTbQHOYsYpVKmQS1RUJNSiwZ5z7 3u73+tNJTPsX1CwUJL1gYDote7d1TGUN26gRD30d5/eVdXf7djjgNJs3/XuheiquBQkaOny0cNdkv H0QRKRP0n+0SkwYZ/NhBshQW8y3JM1EAyr6CXNW2RKDG6xv58EWk+M0kUjYABjy59AabK2R/xYrcP n8TW0EfEWpmvAoR3y82jwq8sFf/N5EK21ZRuPZCPb4aCJP0hPDWg3zK73fZuUi/C7UdxY9R91yE6P YoJvugYw==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1urAdS-0000000EQpI-3YHJ; Wed, 27 Aug 2025 07:31:58 +0000 Date: Wed, 27 Aug 2025 00:31:58 -0700 From: Christoph Hellwig To: anthony Cc: Yu Kuai , Christoph Hellwig , 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, John Garry , "yukuai (C)" Subject: Re: [PATCH RFC 4/7] md/raid10: convert read/write to use bio_submit_split() Message-ID: 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> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <835fe512-4cff-4130-8b67-d30b91d95099@youngman.org.uk> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Aug 26, 2025 at 06:35:10PM +0100, anthony wrote: > On 26/08/2025 10:14, Yu Kuai wrote: > > > Umm, that's actually a red flag.  If a device guarantees atomic behavior > > > it can't just fail it.  So I think REQ_ATOMIC should be disallowed > > > for md raid with bad block tracking. > > > > > > > I agree that do not look good, however, John explained while adding this > > that user should retry and fallback without REQ_ATOMIC to make things > > work as usual. > > Whether a device promises atomic write is orthogonal to whether that write > succeeds - it could fail for a whole host of reasons, so why can't "this is > too big to be atomic" just be another reason for failing? Too big to be atomic is a valid failure reason. But the limit needs to be documented in the queue limits beforehand.