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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s0Yi4-00000006aiS-2RiT; Sat, 27 Apr 2024 03:26:44 +0000 Date: Sat, 27 Apr 2024 04:26:44 +0100 From: Matthew Wilcox To: Christoph Hellwig Cc: "Pankaj Raghav (Samsung)" , djwong@kernel.org, brauner@kernel.org, david@fromorbit.com, chandan.babu@oracle.com, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, hare@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, mcgrof@kernel.org, gost.dev@samsung.com, p.raghav@samsung.com Subject: Re: [PATCH v4 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size Message-ID: References: <20240425113746.335530-1-kernel@pankajraghav.com> <20240425113746.335530-8-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: rbnfnx9amepcbtnim46fyot6f8ro4jbr X-Rspamd-Queue-Id: 807ADA0003 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1714188417-727275 X-HE-Meta: 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 mkzd68uc PrrWZvVvp/1O+nnRtk4pNBpP6flQuc/W7iNdMxGE1PdGpuzRsSagD878I6HJhL+W4EjpN1G2hxFVr5PN9vLDQW2P/RIRT//jXAdsbuAkkpjOw+rEFXXVukNCZ5BoFfg5yAEjEji39AzNu/tDV/kyuSLUUN8CpdUZFtXKMuuWAtEfAZVi7n0wqpWc0BhPtsBdelVcY3wF4g2TGzoj9Uy9YiKjsK21HAZ0V67+3ANL/RpG2iRZcAtL+3ig3jw== 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 Thu, Apr 25, 2024 at 11:22:35PM -0700, Christoph Hellwig wrote: > On Thu, Apr 25, 2024 at 01:37:42PM +0200, Pankaj Raghav (Samsung) wrote: > > From: Pankaj Raghav > > > > iomap_dio_zero() will pad a fs block with zeroes if the direct IO size > > < fs block size. iomap_dio_zero() has an implicit assumption that fs block > > size < page_size. This is true for most filesystems at the moment. > > > > If the block size > page size, this will send the contents of the page > > next to zero page(as len > PAGE_SIZE) to the underlying block device, > > causing FS corruption. > > > > iomap is a generic infrastructure and it should not make any assumptions > > about the fs block size and the page size of the system. > > So what happened to the plan to making huge_zero_page a folio and have There's a series of commits in linux-mm with the titles: sparc: use is_huge_zero_pmd() mm: add is_huge_zero_folio() mm: add pmd_folio() mm: convert migrate_vma_collect_pmd to use a folio mm: convert huge_zero_page to huge_zero_folio mm: convert do_huge_pmd_anonymous_page to huge_zero_folio dax: use huge_zero_folio mm: rename mm_put_huge_zero_page to mm_put_huge_zero_folio > it available for non-hugetlb setups? Not only would this be cleaner > and more efficient, but it would actually work for the case where you'd > have to zero more than 1MB on a 4k PAGE_SIZE system, which doesn't > seem impossible with 2MB folios. It is available for non-hugetlb setups. It is however allocated on demand, so it might not be available.