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b=Cjje+TyJe1CjksRtcHVbhALfF3kCywMkR6E82jRbwK5yU3HW7sthh3PN26Q/IjWK9 uoBC3LrKmpjDstiQkA/8HQHoWfOlVnl1jfLNe0h/9RxM+os0U6iIMEKVlCJEapHf7X 0HtlKwgjbQrYV9JTgwkNTwIDH1kiehlsUxVdaw6tVzC5QFQTV8M+UgytO9uX53CTbk Z9P8A50y9pQciRZBtX2J97yvvXIHMUS5hO0Wk0Bc4QosutayXT3no4xlQQJAg+xTYK vcTcvjoPf4z6R9oXFdGRraqpLcIiIab39GuC4W/GwvTzHVSpe9R5OworkePg0f1Z26 MZXEyTNvhyvSw== Date: Mon, 26 Oct 2026 02:45:42 -0400 From: Mike Snitzer To: sashiko-reviews@lists.linux.dev, Matthew Wilcox , linux-mm@kvack.org, Chuck Lever Cc: Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Christoph Hellwig , Jens Axboe , Jonathan Corbet , Anna Schumaker , Jonathan Flynn Subject: Re: [PATCH v9 6/6] NFSD: drop a shared boundary page only once both WRITEs have written it Message-ID: References: <20261024221152.6965-1-snitzer@kernel.org> <20261024221152.6965-7-snitzer@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: BD0DE40005 X-Rspam-User: X-Stat-Signature: 4k99145fbh93jc5fzrynn3cdjytaukqm X-Spam-Status: No, score=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam03 X-HE-Tag: 1792997143-782765 X-HE-Meta: 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 zHYxP3N3 zxn0ASevSWhwY2VoDBnsUa1qageMCd9Womp8G9TIu4PqzEyHFy2JfKg6UMR3heW7Dm/pXCbH+Ga3X+tfQrQg2RiqaweMqcLZAyNwx09l83R40fES8z8M2izWZxZg7A9iiUQ11yZXIYpimTbo1Op6YGpfSXvIZ/xzXglLzUyIGgaAffwSCXZVRcubb3bs7tKcVim2JyFU+W0jEDfnL2tO/2tZ0+F2ltAQtWEDsTvr96FmveFCv4Gt3l9T5S5B1S2reABcPhLtpWpbKz+H1T3WhM2BR9mo7atNQBt/yJbqtzTYq3ppkmMeyOAz4sPgiwude94LbxIcu3SODezI9Hdv1ZMuexyH7l9kZMx5H Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Sun, Oct 25, 2026 at 10:12:10PM +0000, sashiko-bot@kernel.org wrote: > However, in fs/nfsd/vfs.c:nfsd_write_dio_iters_init(), the boundary > between the buffered prefix or suffix and the direct middle segment is > still cut at max_t(u32, offset_align, PAGE_SIZE): [...] > Should cut in nfsd_write_dio_iters_init() also take > mapping_min_folio_nrbytes(nf->nf_file->f_mapping) into account so that > buffered prefix and suffix segments are cut on unit boundaries? Yes, and a separate patch already does that. "NFSD: cut a misaligned direct-mode WRITE at folio boundaries" replaces the commit in cel/nfsd-testing that added this cut: https://lore.kernel.org/linux-nfs/at0DFod8CcUfus2S@kernel.org/ With it, a misaligned end is cut at cut = max_t(unsigned long, offset_align, mapping_min_folio_nrbytes(nf->nf_file->f_mapping)); so the buffered prefix and suffix end on a boundary of the smallest folio, the same unit that nfsd_write_dio_seg_hold() uses. The cover letter of v9 says that v8 1/7 went out separately. This review ran on the v9 base (cel/nfsd-testing), which does not have that replacement yet. v9 applies on top of the replacement without change. An end that is already aligned to offset_align keeps no buffered segment, mid-folio or not. This keeps such a WRITE direct, on purpose. Mike