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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s72r8-00000009gPC-08RP; Wed, 15 May 2024 00:50:54 +0000 Date: Wed, 15 May 2024 01:50:53 +0100 From: Matthew Wilcox To: "Pankaj Raghav (Samsung)" Cc: hch@lst.de, 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: References: <20240503095353.3798063-8-mcgrof@kernel.org> <20240507145811.52987-1-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240507145811.52987-1-kernel@pankajraghav.com> X-Stat-Signature: uuguopo3ffwrqh1mbrjkc38mm1rsbhg4 X-Rspamd-Queue-Id: 457A0160009 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1715734265-790213 X-HE-Meta: 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 Cpnx3vB7 sIoROJOH5VjN4PlnbC4LDsjfQ3F+/QnVX5ltVYqQOLY+pmnExlMEjvI1IExNdWD/mCOzuiXws6lZMEbg6nYCF4vXgqUh6OLKyCyGLfY1u305rBr3Ul8dt3m3c5FNHKZI3sdqyFHVui7jEqjEP2Gmu1cceXKx8ivNUVAaYupCFkuRNMQWzU/xpyKeFmIgKh7R8qEAOZSBQY2qmdHKqMM3lfz9TAFiKLnpqioTrHdVD+L2niyslOm7mj1G4F94S97lWiNGE 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, May 07, 2024 at 04:58:12PM +0200, Pankaj Raghav (Samsung) wrote: > Instead of looping with ZERO_PAGE, use a huge zero folio to zero pad the > block. Fallback to ZERO_PAGE if mm_get_huge_zero_folio() fails. So the block people say we're doing this all wrong. We should be issuing a REQ_OP_WRITE_ZEROES bio, and the block layer will take care of using the ZERO_PAGE if the hardware doesn't natively support WRITE_ZEROES or a DISCARD that zeroes or ... I suspect all these places should be checked to see if they can use WRITE_ZEROES too: fs/bcachefs/checksum.c: page_address(ZERO_PAGE(0)), page_len); fs/bcachefs/io_write.c: if (bv->bv_page != ZERO_PAGE(0)) fs/bcachefs/quota.c: if (memcmp(mq, page_address(ZERO_PAGE(0)), sizeof(*mq))) { fs/cramfs/inode.c: return page_address(ZERO_PAGE(0)); fs/crypto/bio.c: ret = bio_add_page(bio, ZERO_PAGE(0), bytes_this_page, 0); fs/crypto/bio.c: ZERO_PAGE(0), pages[i], fs/direct-io.c: dio->pages[0] = ZERO_PAGE(0); fs/direct-io.c: page = ZERO_PAGE(0); fs/iomap/direct-io.c: struct page *page = ZERO_PAGE(0);