From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f48.google.com (mail-wr1-f48.google.com [209.85.221.48]) (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 5525B3358A5 for ; Thu, 30 Oct 2025 07:14:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761808473; cv=none; b=BRCN51vd4yqoS6HRnboMNrKVxvsxzPOxQFChkof/kraS7BJkuxfB/YXXYfO4mECzGosJJjC5ykGpPxpZgZZnllSOr7jvAoirmx7ZTcS1rGkOGLa5QakEEEyVxIm1sDvPgkLubmGwJyhltgCFzSqH4uqmByqSW7MHUf0So/AdYt8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761808473; c=relaxed/simple; bh=XMlrJEWTdkAKXDcZVo3PSrnFRhI521tu4gKbZ0l7fQU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rQD7Zc7qEkKwg2bHyQuej1ul1QTOzWl297RanxkwbvHLsE2Yj5PTpFDstHPovBHddpsaebC2VIGQW5fZOHK0Ogp6b6AkgnsB+LiQTf07cSEcyULWFqX7cMihulfq2QS/UwmMUtNlD5sQfm9/rpsNGJ2YKy7cw3z/18dhalkgPXk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=dESBZqrb; arc=none smtp.client-ip=209.85.221.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="dESBZqrb" Received: by mail-wr1-f48.google.com with SMTP id ffacd0b85a97d-3ee64bc6b90so531758f8f.0 for ; Thu, 30 Oct 2025 00:14:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1761808470; x=1762413270; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=aH6T32Cb7TYi8VumYlF/21u6CEuW0X6v+ipNrECbl3c=; b=dESBZqrbJr9m7OWaPAwMJ95tYkFIOS+NwWaX9JNkA9HUJCHaX7GCOWGG5hXziKdzE2 1TAXx65D1LUwmIR0gu45LUHth75+7K9tCEErn+8KTRy12ryjSVruj64pcqKKyDv4UCes Tuq5t6YZwU6DYZFXXKsfhnIrTqB/9Aity/Gelie/uB6OydNiugpotdXyxMmSs07XVsMI YxUB8VGaD2Cc5eLrax3ZzKXs0iRncIkshZtw6FJWDv27YBB8SIgQZoBg7zH4XHWmpQtm tfWvINqsrB2zEIDo/Ql0ABnGkOKTDnE5W8sGgfGj6t49J8t3M8Hd4mP6IKxKKPAgLIPR KHfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761808470; x=1762413270; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=aH6T32Cb7TYi8VumYlF/21u6CEuW0X6v+ipNrECbl3c=; b=jj2GSOdhxOtillrT7JV+XZJaf7Fx+BjG4P+2jSDIHODEPRNe7MOzgta4KRXT5hbciy DgMkLwPrGvJrgBlb+sSdmC9t9CIquUSvQcW4zZbpHDU/JiUusse3Wq02xMp+vEruqWra VkrLa7eaNK6f6t7P/WAhYDNQ94eBiwlihtNmsqzxD9h50N6YhXezI+3Ne+6pMPKG6i6a ZAuFrZ0huu8WLZ0ituUSByd2SQQDomihkdR1HxkDPi62AlAY3QXPyBqPL/B3fkwTTUyU XrL5BH4MY747NGHw45Ood339y8ux8fGAAtD1c6v5brR+b7ACA6nudEi9h3HX0ZH5pqgi eFZQ== X-Forwarded-Encrypted: i=1; AJvYcCV4nY3c7K3KGVOH9jbs6L8NVyFC6nC0D1+jgp699tDjLFRvNUUzykcTGJFN5eH02ZljGrUEyBYt+pw=@vger.kernel.org X-Gm-Message-State: AOJu0Yz/cJye4fqzGBkNUSHml3JhQvHpJeAE9BpjwRXr5XZk3fS2bzT+ 3t9wkMitijXBrC6osYHGTGXo7TKk+wunb5GbWyB/SGDEldT46SYNvmZIRQd7rWtIYm4= X-Gm-Gg: ASbGncsplHrPHJlSLAL6XYnKCivriunWiMMhLJFwLiF2t8cx0eS++y0OEzz/Q/rLwea 1SZh9MT3qh3oHyT280hQckutVeN2cB42S5FwcmeSEGbYDBNpK3Z/LOhL/rARzsQAvT7QRTk3txD aRgI8k0rDsnd3itssE+KqIwne0cvykz7dc5EJ25Eg5r5/fZG5r7euiM3cWauzcl0qhSjvqlGVHj 4TrJowsvO/vJqIiBsTnu3n8GFGquKGPQyiC7nu9ZWVozY9T2Amm1RRviachdyGXef8jVGRdrHf4 nAVGfPDsa7t/zoh/A4qn5CVYkpPjOLlJZvvI3guICTIfn9pqKxqRIOa+lUiJ1uCtURTs5o3102o 0VfO3AVtnpQU2Wnwkga4R8tMxHah3kvGYII3qzPUEOs8yaOhVO9/mhVN7mVNTUxREaV55KP+K+4 6+vY+SgIpbiA7bMCtEep20B1QpLtbdDhwp3uKf9jU= X-Google-Smtp-Source: AGHT+IHn7MtTON5++FHTniNKg/4xSWijqk1ryDdUxKxT7I/HueMz7ChV39hFowYXxw84gLxbWRyTuQ== X-Received: by 2002:a05:6000:43d6:10b0:429:b8e2:1064 with SMTP id ffacd0b85a97d-429b8e211e5mr534668f8f.47.1761808469621; Thu, 30 Oct 2025 00:14:29 -0700 (PDT) Received: from ?IPV6:2403:580d:fda1::299? (2403-580d-fda1--299.ip6.aussiebb.net. [2403:580d:fda1::299]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29498d0c414sm175434765ad.44.2025.10.30.00.14.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Oct 2025 00:14:29 -0700 (PDT) Message-ID: Date: Thu, 30 Oct 2025 17:44:22 +1030 Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/4] xfs: fallback to buffered I/O for direct I/O when stable writes are required To: Christoph Hellwig , Qu Wenruo Cc: "Darrick J. Wong" , Carlos Maiolino , Christian Brauner , Jan Kara , "Martin K. Petersen" , linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org References: <20251029071537.1127397-1-hch@lst.de> <20251029071537.1127397-5-hch@lst.de> <20251029155306.GC3356773@frogsfrogsfrogs> <20251029163555.GB26985@lst.de> <8f384c85-e432-445e-afbf-0d9953584b05@suse.com> <20251030055851.GA12703@lst.de> <04db952d-2319-4ef9-8986-50e744b00b62@gmx.com> <20251030064917.GA13549@lst.de> <20251030065504.GB13617@lst.de> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=wqu@suse.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNGFF1IFdlbnJ1byA8d3F1QHN1c2UuY29tPsLAlAQTAQgAPgIbAwULCQgHAgYVCAkKCwIE FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXVgBQkQ/lqxAAoJEMI9kfOh Jf6o+jIH/2KhFmyOw4XWAYbnnijuYqb/obGae8HhcJO2KIGcxbsinK+KQFTSZnkFxnbsQ+VY fvtWBHGt8WfHcNmfjdejmy9si2jyy8smQV2jiB60a8iqQXGmsrkuR+AM2V360oEbMF3gVvim 2VSX2IiW9KERuhifjseNV1HLk0SHw5NnXiWh1THTqtvFFY+CwnLN2GqiMaSLF6gATW05/sEd V17MdI1z4+WSk7D57FlLjp50F3ow2WJtXwG8yG8d6S40dytZpH9iFuk12Sbg7lrtQxPPOIEU rpmZLfCNJJoZj603613w/M8EiZw6MohzikTWcFc55RLYJPBWQ+9puZtx1DopW2jOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXWBBQkQ/lrSAAoJEMI9kfOhJf6o cakH+QHwDszsoYvmrNq36MFGgvAHRjdlrHRBa4A1V1kzd4kOUokongcrOOgHY9yfglcvZqlJ qfa4l+1oxs1BvCi29psteQTtw+memmcGruKi+YHD7793zNCMtAtYidDmQ2pWaLfqSaryjlzR /3tBWMyvIeWZKURnZbBzWRREB7iWxEbZ014B3gICqZPDRwwitHpH8Om3eZr7ygZck6bBa4MU o1XgbZcspyCGqu1xF/bMAY2iCDcq6ULKQceuKkbeQ8qxvt9hVxJC2W3lHq8dlK1pkHPDg9wO JoAXek8MF37R8gpLoGWl41FIUb3hFiu3zhDDvslYM4BmzI18QgQTQnotJH8= In-Reply-To: <20251030065504.GB13617@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2025/10/30 17:25, Christoph Hellwig 写道: > On Thu, Oct 30, 2025 at 05:23:32PM +1030, Qu Wenruo wrote: >>> So what is your application going to do if the open fails? >> >> If it can not accept buffered fallback, error out. > > Why would it not be able to accept that? > Because for whatever reasons, although the only reason I can come up with is performance. I thought the old kernel principle is, providing the mechanism not the policy. But the fallback-to-buffered looks more like a policy, and if that's the case user space should be more suitable. Thanks, Qu