From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9BCC867C47 for ; Fri, 26 Jan 2024 07:09:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706252953; cv=none; b=HzK40v9IdQ78WQzmQaoVQ5AnGy7p73oKhBZl02vnI/Z9A0iADzah4EbQTBVC1D2yWT+gBkvohrfkiFBkr84pFhUa3mvMlVFeeEAX+nXEmtGbsxxs2iTUoLO8T6aromC6dKnUnjMfK6kGjujUPX41Wh+eo1SqtJ9Gf3Z+tFUaV04= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706252953; c=relaxed/simple; bh=cTdXTUJA/3QYCJl4mkRFCs4Trvp1qOlbfbijYebuVxI=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=TdS8Bo8OYPekigTOEIiDoJhfDSxJyLrktlGkQ152C4CEllCWf/4aK08qCVlwSamvDH2yra21z/0BQ3f/8+DX8XPXGhVHjqhc/TkDE2plSInf2KPdUuSw1DoC0M8oGGYlvtJy/tfFCgXk6Po3mNr5KPbRHdMqsi7PWbQ97CPjfhg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YhYq2GFk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YhYq2GFk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96B20C433F1; Fri, 26 Jan 2024 07:09:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706252953; bh=cTdXTUJA/3QYCJl4mkRFCs4Trvp1qOlbfbijYebuVxI=; h=Date:Subject:To:References:From:In-Reply-To:From; b=YhYq2GFkBL3gQ/o3Nx553e4+VA6ccSOK0vtQI9PcLOhrsvmSiOXnBID0dJ9WktF9d 7mOoYaiTV2cn93NeBSV8EZQWZbpuIWJlPVNguRTq1XLsfrnzzpwKMJ/YSOCDhki+/2 fbV6Cm3ADw8f96FJIcakVB3J5zPGOj7kwAtSzlgowZ53a8fdv2Mku3TaD58gyJx4uQ fsE3hmPcm5wPzgiXiHHCdqOtOJaVLrPPW+WFb7lyzTnWIpPYDPkgLfVEH4K7JsNJJr 4rOsidGqWiOHFDDYKBV9LYN2T9TxziDAj7s/m9GqbaiMsG0c999aAfkworQNVo1TUk 2Lja3jbianqcQ== Message-ID: <89fcb470-2e21-43a3-a428-000e1c6ab706@kernel.org> Date: Fri, 26 Jan 2024 16:09:11 +0900 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] null_blk: Always split BIOs to respect queue limits Content-Language: en-US To: Hannes Reinecke , Jens Axboe , linux-block@vger.kernel.org References: <20240126005032.1985245-1-dlemoal@kernel.org> <84dce2ee-5d71-47a4-b114-3ca69b3c31fb@suse.de> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <84dce2ee-5d71-47a4-b114-3ca69b3c31fb@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/26/24 16:05, Hannes Reinecke wrote: > On 1/26/24 01:50, Damien Le Moal wrote: >> The function null_submit_bio() used for null_blk devices configured >> with a BIO-based queue never splits BIOs according to the queue limits >> set with the various module and configfs parameters that the user can >> specify. >> >> Add a call to bio_split_to_limits() to correctly handle large >> BIOs that need splitting. Doing so also fixes issues with zoned devices >> as a large BIO may cross over a zone boundary, which breaks null_blk >> zone emulation. >> > That feels so wrong. Why would we need to apply queue limits to a bio? > (Yes, I know why. We still shouldn't be doing it.) Splitting is at least needed for zoned devices. Otherwise, everything breaks with the zone emulation. > Maybe indeed time to kill the bio-based path. I have nothing against that :) > > But until that happens: > > Reviewed-by: Hannes Reinecke > > Cheers, > > Hannes -- Damien Le Moal Western Digital Research