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b=AsAsoTRypuTTu9iaHHn2KZjbJ/9neXFQJTFwUXCDU+s7ruNnsRvASy0edAeFZE4Z8 j9kUsw8UGriNRqZNG5wR/zf8gLLLIsPvHecCzRobMZ/X07hQgg9yqznIOm5HXI9VBY XnPoQStJZIryWkPphJEAC/giqR0vgcj1ia/zRfjJ+1JOem5el76/mI+vFVbHPqMOsa 4L5FG8RXZ5XQodrhSBQqbUM1dgK2dqd5ggnjttYR7BpouOp7LyGxneTLhxHCdV91sj Q7T/kJtwg1Y+sik6O/xokLJcQlDVhKJbVPoL/m7ybDfpqiu8BRG0U0gcI3f1ffIjOT RbMBAtJuCxcog== Date: Tue, 14 May 2024 20:34:09 -0600 From: Keith Busch To: Matthew Wilcox Cc: "Pankaj Raghav (Samsung)" , 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: X-Rspamd-Queue-Id: 01B17A0005 X-Stat-Signature: xtskhro7r6bfkcbz6awnomaby4kathrg X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1715740454-943603 X-HE-Meta: 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 gy8oMgAo kZl/q/jQAE2yzPzGql4JA5mdqwOTu3+wxmZeUinQaVjqj1L/PswGEEPbE4tCqcm8Vgtjqh/hA4JjnbJZHn+Y43iohZdYdmMNdnvy5cdnG05J4AhdZUAZGe+6yhVY7e9nv1OUmTcItPxn6RKtEVi3hSihFDh5M3AWZGlja6K+dw4ljpy2Q8SrtD1czhOUJzfcreTHUTXtrwvXwOp85lxoXPgtT29JZzhrFKcxqdHDgz3EqCUlsjW5xLQoAMMvQe6SbjIQAOac66Tj7i5g3lFt8PzddR/DyR+3GtPs9ReMz25O4WX0ikV/pWBei4Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000018, 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 15, 2024 at 01:50:53AM +0100, Matthew Wilcox wrote: > 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 ... Wait a second, I think you've gone too far if you're setting the bio op to REQ_OP_WRITE_ZEROES. The block layer handles the difference only through the blkdev_issue_zeroout() helper. If you actually submit a bio with that op to a block device that doesn't support it, you'll just get a BLK_STS_NOTSUPP error from submit_bio_noacct().