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([2603:8080:1b00:3d:9800:76a6:5d39:1458]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5fcf9579744sm2154338eaf.36.2025.02.22.14.13.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 22 Feb 2025 14:13:47 -0800 (PST) Message-ID: <9eb067b6-bde8-4505-a9f9-33f33c323b6d@gmail.com> Date: Sat, 22 Feb 2025 16:13:43 -0600 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH] Fuse: Add backing file support for uring_cmd To: Amir Goldstein Cc: Bernd Schubert , Miklos Szeredi , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org References: <2d9f56ae-7344-4f82-b5da-61522543ef4f@bsbernd.com> <72ac0bc2-ff75-4efe-987e-5002b7687729@gmail.com> Content-Language: en-US From: Moinak Bhattacharyya In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit > So fc->backing_files_map are not really fds registered for IO, > they are essential references to backing inodes. That's essentially what registered FD's are, they fget() the FD and stash them in an internal data structure. It's not necessarily for I/O per se, its more a mechanism to ensure fast Uring access to a given FD. > Could you explain how fd registration into the ring would help here? From my understanding of the previous problem with passthrough, we want to make sure that one can't issue arbitrary write() calls to the open FUSE FD to sneak in an arbitrary file passthrough (I admit, I don't fully understand the concern). In any case, this is obviated by using URING-only mechanisms, right?