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d=pankajraghav.com; s=MBO0001; t=1715257874; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=syRYsn5YkWqtDoVOn9NFuMpVM6WQHaccjb1P8o4QWJk=; b=ENoWDIlMdBwQF+JZTxrddQuXCrXDJ+v2SKC5XavGOjx+KmlSGRIwmfCuaoeWSfFnH8+wHA StaYVY4Kr7IGwafjdTi4Qkgqj37BX4BeZ3HOoI++h/IiaTr1oWCJjEU2QBjcMpaVzUYZfb UAVH5b+3A0WyHilnOL9AM109fpZ+FqCVqtqfuyHVBAoocTrTgdz1mGISKjvxHYGV7Lrorf d0C6EFvJI+FOS+M8rmeinVfSc9mhtp1qXE1Ubol1xItY2EZcip0kIwoErd61IGMOVVmOJT zgKDepUg03xCT9crOatZUxzBLG/fS2p9Kef8nGb150xtT6w4l01r6fm8UPXVgA== Date: Thu, 9 May 2024 12:31:07 +0000 From: "Pankaj Raghav (Samsung)" To: Christoph Hellwig Cc: hch@lst.de, willy@infradead.org, mcgrof@kernel.org, akpm@linux-foundation.org, brauner@kernel.org, chandan.babu@oracle.com, david@fromorbit.com, djwong@kernel.org, gost.dev@samsung.com, hare@suse.de, john.g.garry@oracle.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, p.raghav@samsung.com, ritesh.list@gmail.com, ziy@nvidia.com Subject: Re: [RFC] iomap: use huge zero folio in iomap_dio_zero Message-ID: <20240509123107.hhi3lzjcn5svejvk@quentin> References: <20240503095353.3798063-8-mcgrof@kernel.org> <20240507145811.52987-1-kernel@pankajraghav.com> <20240508113949.pwyeavrc2rrwsxw2@quentin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam01 X-Stat-Signature: b3xszny69c9hhbz4139k65oky5dy38bo X-Rspam-User: X-Rspamd-Queue-Id: 82BC0A0007 X-HE-Tag: 1715257879-75008 X-HE-Meta: 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 E0U3wwDQ LE4/Af/vsmPL2c/dt35yxrTNxM8z2iUmWXmHkB6hVMWrFw0WPiQzRp1Fh26bkTNIodn/cPkuVvby+wq00MpSU5Ru2OcNwxmoMsSOWa4gw15PjqlgtBGVG0QjAeiUeTWRNY2yqDY/7iSePwrazQSG8pSlN6HmSyARZb1CZLi57vZOqQJcTl33QA4RkOcvl4lhqst6fWL04LygpCiCvbe+jOoFUmu0dvjOmrqXf97CLAwwbcqDas62O7M/Ts4w3dB2cGLPvt34LRBVDdeDzAuMi849Pvzgr2/JfNq8XCMwUPceKi+zG3y3nBvG4ZWfXiSv/PHEOFrEj0IgnfMM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.033243, 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, May 08, 2024 at 04:43:54AM -0700, Christoph Hellwig wrote: > On Wed, May 08, 2024 at 11:39:49AM +0000, Pankaj Raghav (Samsung) wrote: > > At the moment, we can get a reference to the huge zero folio only through > > the mm interface. > > > > Even if change the lower level interface to return THP, it can still fail > > at the mount time and we will need the fallback right? > > Well, that's why I suggest doing it at mount time. Asking for it deep > down in the write code is certainly going to be a bit problematic. Makes sense. But failing to mount because we can't get a huge zero folio seems wrong as we still can't guarantee it even at mount time. With the current infrastructure I don't see anyway of geting a huge zero folio that is guaranteed so that we don't need any fallback. Let me know what you think. -- Pankaj Raghav