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 25DCD30FC27; Sun, 4 Jan 2026 18:54:36 +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=1767552877; cv=none; b=nFDjUFE+5ePtuKGyg6JMY3kDh6nqZX7OOW/odYcs56pjsiNppxkwBDkD24gS+qcfHxQpTzEdzeTiNroeZche1juHi2vuew+pSxKV3/qSXMmutT2wuBsWPsVO5orpaf2FcOTwXJScU9uiE2R95PvvqyKWSszOqllrXDdgiE9rulg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767552877; c=relaxed/simple; bh=5ckW21cSSSQDwyPudbOFi8bdZ2K9Gm5VSRg9b0IN2z4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tPlthES9rN6KBrqxHUh3lF5iYvMlipoWB3zS0Vq1HYtB/NIpFElFetcNvSnEkAz1M8qFzCftQd0zchXLEJPc0qvp+uzBaqx0ru889MTr8QrGf+4bKxfLkyl3ILFj38SlGdtGJiBWceaOBE5KKjxB3tPdPXr/HBelEhWH3zV32ro= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=otFx3rCb; 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="otFx3rCb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DD5FC4CEF7; Sun, 4 Jan 2026 18:54:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767552876; bh=5ckW21cSSSQDwyPudbOFi8bdZ2K9Gm5VSRg9b0IN2z4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=otFx3rCbfqeWsQ/hkeCrE6l/4QCl2MKwjMNEHyGyX64T17Qd+sifh1TJmmKBHvYEC hflTn9bWskCb76Y0CLz7BPa72gSvtUl58oeghHQMrkS6AF9yrZbTmeLnQapyjyQZA0 0of++Cy/z6mKOJhFRTft2Yfx+tqhm3QK+0XdogprWkSKUHDLdyNRpNJ/O/DWNeGJSV cHNIqwE9klCdiH+oysrzU7qyVTfYUfkDv/Cj3Okmx7usCowXPpiYVamlLWWv09u2C4 xQKfLBiUksCjBTvyrZO5+R0TGIWkntMXfFhNwllqDyEPeYB3Hr4K7Y3vBIXNMVKKdT p+xKBzPKaKTIQ== Message-ID: <9f9343f6-c714-4d2f-985b-e832c6960360@kernel.org> Date: Sun, 4 Jan 2026 19:54:32 +0100 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() To: Andrew Morton , Joanne Koong Cc: miklos@szeredi.hu, linux-mm@kvack.org, athul.krishna.kr@protonmail.com, j.neuschaefer@gmx.net, carnil@debian.org, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org References: <20251215030043.1431306-1-joannelkoong@gmail.com> <20251215030043.1431306-2-joannelkoong@gmail.com> <20260103100310.7181968cda53b14def0455b3@linux-foundation.org> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/3/26 19:03, Andrew Morton wrote: > On Sun, 14 Dec 2025 19:00:43 -0800 Joanne Koong wrote: > >> Skip waiting on writeback for inodes that belong to mappings that do not >> have data integrity guarantees (denoted by the AS_NO_DATA_INTEGRITY >> mapping flag). >> >> This restores fuse back to prior behavior where syncs are no-ops. This >> is needed because otherwise, if a system is running a faulty fuse >> server that does not reply to issued write requests, this will cause >> wait_sb_inodes() to wait forever. >> >> Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") >> Reported-by: Athul Krishna >> Reported-by: J. Neuschäfer >> Cc: stable@vger.kernel.org >> Signed-off-by: Joanne Koong >> >> .. >> >> --- a/fs/fs-writeback.c >> +++ b/fs/fs-writeback.c >> @@ -2751,7 +2751,8 @@ static void wait_sb_inodes(struct super_block *sb) >> * do not have the mapping lock. Skip it here, wb completion >> * will remove it. >> */ >> - if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) >> + if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK) || >> + mapping_no_data_integrity(mapping)) >> continue; > > It's not obvious why a no-data-integrity mapping would want to skip > writeback - what do these things have to do with each other? > > So can we please have a v2 which has a comment here explaining this to the > reader? Sorry for not replying earlier, I missed a couple of mails sent to my @redhat address due to @gmail being force-unsubscribed from linux-mm ... Probably sufficient to add at the beginning of the commit: "Above the while() loop in wait_sb_inodes(), we document that we must wait for all pages under writeback for data integrity. Consequently, if a mapping, like fuse, traditionally does not have data integrity semantics, there is no need to wait at all; we can simply skip these inodes. So skip ..." -- Cheers David