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 AF7ED202960; Wed, 25 Jun 2025 11:49:34 +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=1750852174; cv=none; b=tX1vVw5WtOKQg+L4w7iz45zf6XFobX1AYbswy6uBTgUvNPUCnNqvJraYutvXWxJjFCZU+a7wWlw176ATLvVAnS8l+Upn42aqJ3M4PpKodam4nduUEI9A3RPs3rAo/j+1tDaPFlqFWXWB9I3cP87NsbPQMK+HULPklZzQ/BB1YMs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750852174; c=relaxed/simple; bh=T1y3v9XdjqwUNBwRwDZhB4swEe9RAFJ8LTgmJ+dg8As=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=YjE4i0fm+9vJtv63bhkNjg4MC2RL71/JZy84+R0x1qJvCrBcY4iCgnyfq6unkiHuzCvJE1caaTeVo5fQMCCthLZkJwz/rZJwAVmDOFELSidZS7e31s97WTwUU+MDmTr4OGRLQF+QPkNfZ/JQVXkr8AxgPYy+RT7OhxmjQ0URNyo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fa5MXmON; 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="fa5MXmON" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7021EC4CEEE; Wed, 25 Jun 2025 11:49:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750852174; bh=T1y3v9XdjqwUNBwRwDZhB4swEe9RAFJ8LTgmJ+dg8As=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=fa5MXmONwvk8WoVsE1V1pkVfqSOZufYpkxlDr3XZB5+M1eKvbLbh+bgaGAk9XeBMS WfUUdaG74p7Z1QoQu7R65NIktezweOb25P17IjEnqX1EN+XpV11mT/R+HwgyAGbR9G 2qiQwDFYPGcWRwMAV/pJAIR0ATn5GUAhVH+q5fAQGL1Y2HquDArlPNHkg3qbFJUk0c dggsyx04RPUIY3l0WUuMZK9Ou2dGiN5LLJJpb71sBJfPxe38ewzc9WH0NGzMkiU+hy AOaGo3zTzeYfgjPzOYYEg8V973WCQfAPt0cWnCq0pVB9s7zNn51nUTDRwTCebYp7mm BOifEejKgUy3A== Message-ID: <6ac46aa32eee969d9d8bc55be035247e3fdc0ac8.camel@kernel.org> Subject: Re: [PATCH] xfs: report a writeback error on a read() call From: Jeff Layton To: Christoph Hellwig Cc: Yafang Shao , david@fromorbit.com, djwong@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, yc1082463@gmail.com Date: Wed, 25 Jun 2025 07:49:31 -0400 In-Reply-To: References: <51cc5d2e-b7b1-4e48-9a8c-d6563bbc5e2d@gmail.com> <88e4b40b61f0860c28409bd50e3ae5f1d9c0410b.camel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2025-06-25 at 04:21 -0700, Christoph Hellwig wrote: > On Wed, Jun 25, 2025 at 06:40:07AM -0400, Jeff Layton wrote: > > Another option: > >=20 > > We could expose this functionality in preadv2() with a new RWF_WBERR > > flag (better names welcome). That way applications could opt-in to > > checking for writeback errors like this. With that, the application is > > at least explicitly saying that it wants this behavior. >=20 > That sounds like a really strange interface to me. >=20 > I have to admit I don't fully understand the use case where an > application cares about these errors, but also doesn't use f(data)sync > or sync(fs) to actually persist the data. If we can come up with a > coherent use case for that we should simply add a new syscall or fcntl > to query the delayed writeback errors instead of overloading other > interfaces. It is weird, but I do sort of get the motivation. In a some cases you want to be able to stream writes as fast as possible and let the kernel lazily write that back (because you don't want to block a thread), but knowing if a prior writeback error has occurred is a good thing too. Another idea: add a new generic ioctl() that checks for writeback errors without syncing anything. That would be fairly simple to do and sounds like it would be useful, but I'd want to hear a better description of the use-case before we did anything like that. --=20 Jeff Layton