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[87.205.15.91]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4bb4e2adf53sm159789845e9.15.2026.11.13.07.20.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Nov 2026 07:20:04 -0800 (PST) Message-ID: Date: Fri, 13 Nov 2026 16:20:02 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/2] kernfs, sysfs: add SYSFS_NO_SPLICE to refuse splice on writable opens To: Tejun Heo Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , Ian Kent , Danilo Krummrich , Johan Hovold , Len Brown , Pavel Machek , Jens Axboe , Alexander Viro , Christian Brauner , Jan Kara , driver-core@lists.linux.dev, linux-pm@vger.kernel.org, autofs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+002fb7b2d0bc53bf7e75@syzkaller.appspotmail.com References: <07d063ef8ebcfc7f4e05c7318a423728@kernel.org> Content-Language: en-US From: Krystian Kaniewski In-Reply-To: <07d063ef8ebcfc7f4e05c7318a423728@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/12/26 16:11, Tejun Heo wrote: Hello Tejun, > Hello, Krystian. > > On Thu, Nov 12, 2026 at 03:17:01PM +0100, Krystian Kaniewski wrote: >> Read-only opens keep splice support because they cannot reach >> ->write(). > > The patch looks fine to me, but I'm not sure whether the read-only > exemption is necessary. Is it addressing an actual problem? busybox, for > example, just falls back to regular reads when sendfile() fails with > -EINVAL, and refusing splice reads on read-write opens while allowing them > on read-only ones seems more confusing than anything else. Would it be > simpler to refuse splice for all opens of the file? > > Thanks. > > -- > tejun The read-only exemption was only intended to minimize the behavior change. It is not addressing a known user or regression. I agree that refusing splice for all opens would be simpler and give SYSFS_NO_SPLICE consistent semantics. I can make that change in v4. Thanks, -- Krystian Kaniewski