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Fri, 13 Feb 2026 02:25:21 -0800 (PST) Message-ID: <4870d506-e29f-4c68-8d93-03aa3a931fa1@gmail.com> Date: Fri, 13 Feb 2026 13:25:20 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: File name is not persisted if opened with O_SYNC and O_TRUNC flags To: Christoph Hellwig Cc: viro@zeniv.linux.org.uk, brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org References: <4b207a36-5789-41d2-ac17-df86d4cde6da@gmail.com> Content-Language: en-US From: Vyacheslav Kovalevsky In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 13/02/2026 10:33, Christoph Hellwig wrote: > On Thu, Feb 12, 2026 at 02:51:47PM +0300, Vyacheslav Kovalevsky wrote: >> Detailed description ==================== Hello, there seems to be an >> issue with O_SYNC flag when used together with O_TRUNC on various >> file systems. Opening a file with O_SYNC (or using fsync(fd)) should >> persist directory entry. > No, it should not. I'm not sure who hallucinated, but O_SYNC has > always always applied to persistency semantics after writes and > nothing else. You are right, opening file with O_SYNC does not persist anything and ftruncate or O_TRUNC do not count as write I/O it seems. Also found an error related to these assumptions in our testing tool. Thanks.