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[16.145.69.213]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-395e4b2af01sm101253a91.14.2026.08.21.13.49.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Aug 2026 13:49:24 -0700 (PDT) From: "Anthony Vardaro (Anthropic)" To: "Darrick J. Wong" Cc: "Anthony Vardaro (Anthropic)" , Carlos Maiolino , linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] xfs: revalidate cached COW fork mappings during writeback Date: Fri, 21 Aug 2026 20:48:43 +0000 Message-ID: <20260821204843.3223395-1-me@anthonyvardaro.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260820161123.GH6072@frogsfrogsfrogs> References: <20260820-b4-xfs-cow-wb-revalidate-v1-1-8a19080799ea@anthonyvardaro.com> <20260820161123.GH6072@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit On Thu, Aug 20, 2026 at 09:11:23AM -0700, Darrick J. Wong wrote: > The buffered write path has similar data/cow fork sequence counter > revalidation code, so would it be a better idea to adapt the writeback > path to sample the sequence counter via xfs_iomap_inode_sequence in > xfs_map_blocks, and re-check that in xfs_imap_valid()? > > I weakly hinted at this a few years ago when we were adapting the > buffered write path, see [1]. > > [1] https://lore.kernel.org/linux-xfs/Y2mcOCpKiDb4nf1X@magnolia/ I think that's reasonable. It's mostly deletion since xfs_bmapi_convert_one_delalloc() already fills wpc->iomap.validity_cookie. I'd still like 1/2 to stay the small private cow_seq check so it can go to older stable trees, which don't have validity_cookie or xfs_iomap_inode_sequence(). So for v2 I'll send two patches: 1/2 for this fix, Cc stable; 2/2 samples xfs_iomap_inode_sequence() in xfs_map_blocks(), compares the cookie in xfs_imap_valid(), and removes data_seq/cow_seq, with the cost measured again. Anthony