From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-91.mta0.migadu.com [91.218.175.91]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 763FB37F300 for ; Mon, 7 Sep 2026 09:20:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.91 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788772826; cv=none; b=gf7edwSuhQEt2MlpdMvuQMsXdmvCujAqxLIypxs1bv7xMxGPkiBMpYFBUZGta2pUwoZdKpGMiFfVKcD1PPt1y/bGZ7UUuvj7rWJkwWJgYHkXEYm6QbLLkFRv5V7SFawPgiSN6D2gPpomOCgPFJcDCt3umOTjbwwn5J1UlzohQzg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788772826; c=relaxed/simple; bh=ybMTWC9H/A8W5KkE2argi4jh9MKl4LDBs1eh/rJcz0w=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Tdhj8fZs4bEeGBXkBphMJAbayHxSCEFyw8VHecFod/qA5wNrUQn6ONOZP3XgwG/KpcnQzG6d1e2KprakL4wpDSxMh4W5mHcAD6pSaWKH9H2XyOQSdwEaRzI1GazrxyZuqy3OHng0YY35ZNNQggaAgtS3V1RvsTJy+7uO5r47w2M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Op+sabGr; arc=none smtp.client-ip=91.218.175.91 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Op+sabGr" X-Envelope-To: linux-block@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=ybMTWC9H/A8W5KkE2argi4jh9MKl4LDBs1eh/rJcz0w=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788772822; v=1; x=1789377622; b=Op+sabGrZ8yhZIZSxNrz2TjaRUkQaV/rl8aAbX7Opp2huj53evAOB3vnYNyh4xR4iqhdA9dt Zxv/PdVzmZXS7UvEHhKdAUieGGRYljQxC4l9Ioc/pKIz/xC6/Gnoarh+h9Ooo78yZ1JVHroveqU yxLEWfV7IUVenpMACOvucEvc= X-Envelope-To: linux-block@vger.kernel.org Received: by mta10.migadu.com with ESMTPS id f0a97c76ea9427da; Mon, 07 Sep 2026 09:20:03 +0000 X-Mizu-Trace-ID: f0a97c76ea9427da X-Migadu-Flow: FLOW_OUT Message-ID: <90f94bcd-813d-48f9-a62c-3c703c4a71e6@linux.dev> Date: Mon, 7 Sep 2026 10:19:58 +0100 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] block: cap atomic write size by PI buffer size constraints To: Christoph Hellwig Cc: Jens Axboe , John Garry , "Martin K. Petersen" , linux-block@vger.kernel.org References: <20260907074111.721054-1-hch@lst.de> <20260907074111.721054-3-hch@lst.de> <8c16f727-c840-4a8f-94a7-fbe09bc3735a@linux.dev> <20260907084621.GA7391@lst.de> Content-Language: en-US From: John Garry In-Reply-To: <20260907084621.GA7391@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/7/26 09:46, Christoph Hellwig wrote: > On Mon, Sep 07, 2026 at 09:09:47AM +0100, John Garry wrote: >> On 9/7/26 08:40, Christoph Hellwig wrote: >>> As Sashiko points out, >> >> Do you have a reference for that? I'm just curious, as we don't support >> atomics for integrity writes. Well, for SCSI we don't... we impose this >> restriction via sd_config_atomic(), I need to check for the same in NVMe... > > https://sashiko.dev/#/patchset/20260831064010.2574896-1-hch%40lst.de > > Search for "atomic". cheers So this mentions one issue which Tal addresses in "block: fail atomic writes instead of falling back to buffered I/O" and how we need to be wary of fragmented atomics. As for atomics on disks with integrity support, we decided not to support SCSI WRITE ATOMIC (32) - this one is relevant to PI type 2. But, overall, I'm not sure on this - should we always disable atomics for any disk PI? Is there a use case for the two together? Martin?