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30 Oct 2026 19:24:08 +0000 Received: from EX19MTAUWB001.ant.amazon.com [205.251.233.104:24377] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.63.21:2525] with esmtp (Farcaster) id 7f75e6f1-28f2-4c6d-bf2e-bec889c1f73e; Fri, 30 Oct 2026 19:24:08 +0000 (UTC) X-Farcaster-Flow-ID: 7f75e6f1-28f2-4c6d-bf2e-bec889c1f73e Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.56; Fri, 30 Oct 2026 19:24:08 +0000 Received: from dev-dsk-jamz-1e-e35f4cd9.us-east-1.amazon.com (10.189.35.140) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.56; Fri, 30 Oct 2026 19:24:07 +0000 From: Jimmy Zuber To: NeilBrown CC: Miklos Szeredi , , , Shuah Khan , "Bernd Schubert" , Jim Harris , "Horst Birthelmer" , Luis Henriques Subject: Re: [PATCH v6 1/2] fuse: add FUSE_OPEN_ATOMIC Date: Fri, 30 Oct 2026 19:24:01 +0000 Message-ID: <20261030192401.2543699-1-jamz@amazon.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <179332437497.269288.7305999595462479305@noble.neil.brown.name> References: <179332437497.269288.7305999595462479305@noble.neil.brown.name> X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D031UWC004.ant.amazon.com (10.13.139.246) To EX19D001UWA001.ant.amazon.com (10.13.138.214) On Fri, 30 Oct 2026, NeilBrown wrote: > > - any other file: the server returns the entry only, and the VFS opens > > it; > > Why is this a requirement? I understand that the server *may* choose to > not open the file, so that the open doesn't happen until after the > permission check. But shouldn't be up to the server to decide. This doesn't have to be a requirement, for regular files the server can open if it chooses to. I'll reword. Are you also asking why this is just regular files and not directories too? I could look into that if you'd like? For what it's worth, special files should never get opened by the server on this path, the kernel opens them itself. > > The VFS checks the open after the reply, as for other ->atomic_open() > > filesystems, and the kernel releases the file if the check fails. > > FMODE_CREATED is set only when the server reports FOPEN_CREATED. > > The above para seems to suggest that the server might open a file that > wasn't created. Yeah, atomic_open is a lookup+open on the FUSE server, and that open might be an open-create or just an open. Either way, the server might open a preexisting file. I'll try to make all of this clearer in the next rev, once I've gotten any feedback on directional changes here. Thanks, Jimmy