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AJvYcCUzuasUPbOF/J5Zn7F15jJDE1v+auRMLhDDQA6uW7ZLZ2r0w3WI8IBsb+kOhtwMIs9BM7wKAOBMmQ==@kvack.org X-Gm-Message-State: AOJu0YzH/0H3DSp/tE524mACMto8s1RuZZJBIucGTOkVmMJsmrX9qOgV fNzUJzVLH5d2Tle3H+rOg0+VSO+6yMmLid2bAbgHiXSwwFmroL5MRZyfSENwNMepmQLtmgb2D7U eIj1+jL3hqHxPjHTvdz1klFaG3e1YEeGj4ufY X-Gm-Gg: AY/fxX79Xu/jDWH03YNHwAJIbpHdP0f8bP5kxErXWFRNNFyhUFG+hpSSv9rFjA3j+rk O9VKa1UjktGmCDMpjRjQkGNzarOp1BoVX/LsjC2ap1+4JuDWS2cH9FLtTyQ8hg1pd/zK2WzqyMT 5s/MO1iLUYFTAnqrqYUtSh4nDbfNG8v777l6rnNOXCCQ2oVnDOVGEj6KiluTkvNQkVNyHhw6zhI WoTpAc5ZNIhauLsUFXKTFBGfX8yRRMmzhtVH7v5jNeC1thk6MZTtQPhuDF/TtpRkzSTTg== X-Google-Smtp-Source: AGHT+IEcXiL8f+s52fan8QBIB8gC3RmFY4+fpmlXK2z6PXVY35c7s9hfXufUtxNhmOF/muXn/qtrDW/8Z7clxD7o+HI= X-Received: by 2002:a05:622a:198f:b0:4f1:e99f:7d74 with SMTP id d75a77b69052e-4ffa76d7eb2mr10837171cf.12.1767642956158; Mon, 05 Jan 2026 11:55:56 -0800 (PST) MIME-Version: 1.0 References: <20251215030043.1431306-1-joannelkoong@gmail.com> <20251215030043.1431306-2-joannelkoong@gmail.com> <20260103100310.7181968cda53b14def0455b3@linux-foundation.org> <9f9343f6-c714-4d2f-985b-e832c6960360@kernel.org> In-Reply-To: <9f9343f6-c714-4d2f-985b-e832c6960360@kernel.org> From: Joanne Koong Date: Mon, 5 Jan 2026 11:55:45 -0800 X-Gm-Features: AQt7F2qxuG4z8c8Qm515xNGzMMbs8p-UQIVayICF-AA8ax8cqWJEnRx16FYQQIw Message-ID: Subject: Re: [PATCH v2 1/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() To: "David Hildenbrand (Red Hat)" Cc: Andrew Morton , 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: tg7nabj3mu15z17r8eozwdwk1whngznt X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 29A37140009 X-Rspam-User: X-HE-Tag: 1767642957-685634 X-HE-Meta: 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 rGIXrbM7 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Jan 4, 2026 at 10:54=E2=80=AFAM David Hildenbrand (Red Hat) wrote: > > 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 n= ot > >> 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 intern= al rb tree") > >> Reported-by: Athul Krishna > >> Reported-by: J. Neusch=C3=A4fer > >> 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 *s= b) > >> * do not have the mapping lock. Skip it here, wb complet= ion > >> * 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 inod= es. > > So skip ..." Sounds good, I'll send out v3 with these changes. Thanks for the feedback, Andrew and David. > > -- > Cheers > > David