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imf02.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=lst.de; spf=pass (imf02.hostedemail.com: domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1780379269; b=zJFE26J8w0MGcCHjKcqFaIp8saz4qGEEiD19lGuRp/imvmAK+Qog1r39vJTHQvqnRR9RCU jCzT6VTiE2+SeD2xNv0oXdyFyAwSbE3bEtVcFG6+zzIv1QFeMNG05HzqPJfjQJkspj1bG0 8H5m9GcGBlqXY5H/4uRyELTd//61ASw= Received: by verein.lst.de (Postfix, from userid 2407) id 5ACDD68B05; Tue, 2 Jun 2026 07:47:43 +0200 (CEST) Date: Tue, 2 Jun 2026 07:47:43 +0200 From: Christoph Hellwig To: Ojaswin Mujoo Cc: Daniel Gomez , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, djwong@kernel.org, john.g.garry@oracle.com, willy@infradead.org, hch@lst.de, ritesh.list@gmail.com, jack@suse.cz, Luis Chamberlain , dgc@kernel.org, tytso@mit.edu, p.raghav@samsung.com, andres@anarazel.de, brauner@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pankaj.raghav@linux.dev, Daniel Gomez Subject: Re: [RFC PATCH v2 0/5] Add buffered write-through support to iomap & xfs Message-ID: <20260602054743.GA32657@lst.de> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EBB6680008 X-Stat-Signature: nw4otuurqe7u4kaawaumhrpzpqd1mdu8 X-Rspam-User: X-HE-Tag: 1780379268-252666 X-HE-Meta: U2FsdGVkX18hD+avi+jkj7EVlqnc4CEmr0ZCUA5pUhhTxxDuz6SH9EfzZEhhy8VaIwyWW3rVs1M95SIxZzBTCweeG9Vnh06ca8KjTpfJT+ZhswX/fP3i6icjKCmvoIUNhR1cspTyY+1VqiLcVLzW1KGSyR2JXzfvfwlDEUmDfdvhPP96HxrFBPsKcPYrOds9jCUSIQ47fVioQqqG+nz5oqqntURqTWoYrGZo+73B+MYuAqDZTbE3WW4+tOvfF9bjpNxYTrglal1pvyidMYBIAjdIeJh+TT+EQ5sAAMHPbn41tApEL660j5hKCSPgO+Y53typLRAJ2nMkaHXHrr7/n4DuGRfqpASzATOqmyKe7hxFEpRgSO4bllb2227qxs6UlDRG3MkdHWyiEvVOdOyH6SOufuv/RByKBZpGA/Ka4QvN0pBMcHzj7AjsvzdEBv+n/N9XoM+Wff5JA3fxj6Dy5q4zvN3sKvEspnwd1c5s+SMzzID9DcTXbV3T2L+DN/N/ZZgVNE9119zbBIV9Sk8ZQfaFlpxATz7u0ox99PSLCuccoAgHSPOUyGaYwxuCmbnpi4koShz/xZ4eXysc7CPe1avIZXuDJqvAZSN5Z7+URs6xh5ITsVNeJlbY3l1kocGkX/zYaVPXZL2xNNvNPpCdjgs51vbqwcFvwvbr3rbtj2wfN13Xs3ohMaZCR8txrrKMZaHA89+/dMDjeOb97CWJUOIYK6ITcB9NKlxQzEQjbX1fm3dgHJhXqkZz1aZLkKFmREvFeQVoQexriw+OaJ7PoNyzXQdIG6e9JlgNyiCvMfkmIaVpjSNc8+tWF3zRuzKUcwJ+2HuYYwla5ZT6TJkFHrtt+6+jS4MOqEMO3zT/IHKO5pnvWk9YfmxZRz9E7oPs2c3HKMTZbT1NIv0hY3T/X8HNL9yp0ykd9DHlteb/vU5b0wwYIM7A3eTeKTcAST0fM0pPoYo1G54r8k7xYh4 E03eaeOG rXB/DUV5UHie5P0Jf6RThc6ZLq4Xr2dlyd9afiCAbTSXSHynOEtIdLWoOiHFM5QpseFnD4tHn15qv9JYuKxxq7xQVG8P0Mbm2ORsFw0Z8Y7eDhXqBK1MljgEHJtgzqf9FsVEiT6tKVkVPg1tM7mjjtfUFaoSQcvI4fvVXVG3ipIn0KdsPaX12+cxBFC250zoczFTi Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 01, 2026 at 10:19:18PM +0530, Ojaswin Mujoo wrote: > > So this week I spent some time looking into the failure of g/457. > I was able to replicate it in my setup and after analysing it, this is > actually an issue in my xfstests patch. The issue is that to verify > RWF_WRITETHROUGH support I do a 4kb write on the fd during the test prep > phase. However "out-of-band" write makes the actual contents of the file > different from what fsx expected (It reads it in before the problematic > write), causing the test failure. Why does this get out of sync? One of the arguments for RWF_WRITETHROUGH vs direct I/O was that it avoids the content getting out of sync.