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AJvYcCXDYjGjv+RV20iZftP/sZ858xWGNQYW0N+vq/r3Pksqf08WnZkCn0YxaQahtWKLldkFR4E0kaZzpQ==@kvack.org X-Gm-Message-State: AOJu0YzoylSRvPOB4pYQkKYhZaLK96j7DLzqlh03FoYkpN88iqSGZmWa lG8wEQ88025tWz1vfG81eJ1JhBkir1SjGOZnLe5PrJM81eL96RZOtdUxbOh9SgIFeyKJ4mMdgOV Yvn4oW7mp09chmKbVLWOwBQmgXDuaRH4= X-Gm-Gg: ASbGncsHmWfGaPNK1gFjp8OkqU9An0I9P9UqmwC2PpNI6zsHyt6B5MlluR2GpvpTw0w A4frBHcst1cy61gowlti0R8LPuW3QlOoUb1dE2EhWTWRB6Z8don7985NjlXpdt6Xm9i7Z430lqF +RQXy2DHLTr4S5+EwE5iDOsICDxkroYJV3MRJQI3innd2bJBqsBXjCBYvLIMm78+e5yQjj4kNEI zaALf5g+EKxT0tLXCR7ZMR+d51wODb8t+OYK1fXCC4FQzFmI/qFvfgIofQ42l+cCGTPhw== X-Google-Smtp-Source: AGHT+IGUMPFl2u4LYkvi5XrfvZZxNf0T7IQ/UmH+m/1OY7Kuxsj34G3KeI/hNPM04GPlwQrdLOPhH+phTrJRXqJlY6k= X-Received: by 2002:ac8:5f48:0:b0:4ee:1a54:d2bd with SMTP id d75a77b69052e-4ee58ab003cmr287861791cf.29.1764179931447; Wed, 26 Nov 2025 09:58:51 -0800 (PST) MIME-Version: 1.0 References: <20251120184211.2379439-1-joannelkoong@gmail.com> <20251120184211.2379439-3-joannelkoong@gmail.com> <5c1630ac-d304-4854-9ba6-5c9cc1f78be5@kernel.org> <504d100d-b8f3-475b-b575-3adfd17627b5@kernel.org> In-Reply-To: <504d100d-b8f3-475b-b575-3adfd17627b5@kernel.org> From: Joanne Koong Date: Wed, 26 Nov 2025 09:58:40 -0800 X-Gm-Features: AWmQ_bnpX_M54rPqypc5h1eZeZ6yR9KrguhyZF92GnYk549xbCVZ2NRiunLmtEI Message-ID: Subject: Re: [PATCH v1 2/2] fs/writeback: skip inodes with potential writeback hang in wait_sb_inodes() To: "David Hildenbrand (Red Hat)" Cc: akpm@linux-foundation.org, linux-mm@kvack.org, shakeel.butt@linux.dev, athul.krishna.kr@protonmail.com, miklos@szeredi.hu, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 649471C0010 X-Stat-Signature: hbr145qbcup7js9t11qqxo6fctxqdcrx X-Rspam-User: X-HE-Tag: 1764179932-810063 X-HE-Meta: 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 /I+XpKdL Kx7KjwVbcT/fZyqnE7eyzPuUTR7tjpqJKE3MkGzaDlnsdSnwdSyoQQGzqd3Ui6ZbP6XxJQ2xLRBF0vp0rkTjTYbMIEF6klj/gj8lH0FHps1iHv6JO0Gv3m6JaXRE6fYFhCX8rtd16L+eoiExQqwvdLq7ZHKhFD1RnHJQLzKDf5o/W7kqbnTBJi3fwFIx7YmSAZJCIy5UpLzeYBHJwDgC2HJxFwkdzXfn+wYb2FjqTcR/b3xS7Je4HqkMza0ECJgMbnJMxH35TF06W1JqUzdN/LXPXtr8mlH4hWCr9e475MFQfZ5cNkCTza+ShR6QBJYBKkqX9okp+kInS+Q7j4hJkiIfpP2NW/ZLiMDhaL+HNPJ4WsGfR8NDI7LdfPaziY7G/ey7ZBVwwOuwZWbloi2DM0xrlgX/xq0xbf1Ol2nJGW7abqgE= 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 Wed, Nov 26, 2025 at 2:55=E2=80=AFAM David Hildenbrand (Red Hat) wrote: > > > >> having a flag that states something like that that > >> "AS_NO_WRITEBACK_WAIT_ON_DATA_SYNC" would probable be what we would wa= nt > >> to add to avoid waiting for writeback with clear semantics why it is o= k > >> in that specific scenario. > > > > Having a separate AS_NO_WRITEBACK_WAIT_ON_DATA_SYNC mapping flag > > sounds reasonable to me and I agree is more clearer semantically. > > Good. Then it's clear that we are not waiting because writeback is > shaky, but because even if it would be working, because we don't have to > because there are no such guarantees. > > Maybe > > AS_NO_DATA_INTEGRITY > > or similar would be cleaner, I'll have to leave that to you and Miklos > to decide what exactly the semantics are that fuse currently doesn't > provide. After reading Miklos's reply, I must have misunderstood this then - my understanding was that the reason we couldn't guarantee data integrity in fuse was because of the temp pages design where checking the writeback flag on the real folio doesn't reflect writeback state, but that removing the temp pages and using the real folio now does guarantee this. But it seems like it's not as simple as that and there's no data integrity guarantees for other reasons. Changing this to AS_NO_DATA_INTEGRITY sounds good to me, if that sounds good to Miklos as well. Or do you have another preference, Miklos? Thanks, Joanne > > > -- > Cheers > > David