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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sOghm-00000000xck-3ywy; Tue, 02 Jul 2024 16:50:10 +0000 Date: Tue, 2 Jul 2024 17:50:10 +0100 From: Matthew Wilcox To: Christoph Hellwig Cc: "Pankaj Raghav (Samsung)" , david@fromorbit.com, chandan.babu@oracle.com, djwong@kernel.org, brauner@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, yang@os.amperecomputing.com, linux-mm@kvack.org, john.g.garry@oracle.com, linux-fsdevel@vger.kernel.org, hare@suse.de, p.raghav@samsung.com, mcgrof@kernel.org, gost.dev@samsung.com, cl@os.amperecomputing.com, linux-xfs@vger.kernel.org, Zi Yan Subject: Re: [PATCH v8 06/10] iomap: fix iomap_dio_zero() for fs bs > system page size Message-ID: References: <20240625114420.719014-1-kernel@pankajraghav.com> <20240625114420.719014-7-kernel@pankajraghav.com> <20240702074203.GA29410@lst.de> <20240702101556.jdi5anyr3v5zngnv@quentin> <20240702120250.GA17373@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240702120250.GA17373@lst.de> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 67C56180024 X-Stat-Signature: 1dh5gx9uo4rp546w1if1z4jtxph5d1gn X-HE-Tag: 1719939020-958611 X-HE-Meta: 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 1PvBYQKs 5VPbf/RqnnYlruGTuTHtiroHRlJjaJBsgf6Hj5ohlmhgavSqjBoMIAkaH8NCGejUS7jAFIJgtsxHgvlynREEd5JddL6pMhwJFqq878JjlJAR1JJdBHvEd+7HX3JHiuhd1EE/OXVpFvC5i8NXhavJW5wf77/iP8hvg8eMUxj3PDT5Cu2JlvDqhRaBkBaSwRO53nRjdSTDU+kvtAIgaCnFXCyhY4BmxbicCKTHqLDaM+NvZ8ji/PvtXrd0HkDl78j7EuyIg 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 Tue, Jul 02, 2024 at 02:02:50PM +0200, Christoph Hellwig wrote: > On Tue, Jul 02, 2024 at 10:15:56AM +0000, Pankaj Raghav (Samsung) wrote: > > Willy suggested we could use raw pages as we don't need the metadata > > from using a folio. [0] > > Ok, that feels weird but I'll defer to his opinion in that case. Let me see if I can make you feel less weird about it, since I think this is something that people should have a clear feeling about. In the Glorious Future, when we've separated pages and folios from each other, folios are conceptually memory that gets mapped to userspace. They have refcounts, mapcounts, a pointer to a file's mapping or an anon vma's anon_vma, an index within that object, an LRU list, a dirty flag, a lock bit, and so on. We don't need any of that here. We might choose to use a special memdesc for accounting purposes, but there's no need to allocate a folio for it. For now, leaving it as a plain allocation of pages seems like the smartest option, and we can revisit in the future.