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AJvYcCUr64IEumQMTEhsqPjNUecZKMdi8/oxVM8++V0YjSUmFcLD+Gfv+d6O51HUmw8OKoYwUSv5icR9Dr+DmQFqxw==@vger.kernel.org X-Gm-Message-State: AOJu0YzbmCiMWZ5QCZggidyAyH4wAR3EZK6d09VJakKjatarFb/6h9uO oLPTb+vw+HPct9BeexO7YGzw9Wg0ikBR6iPPHENa2It9e9vdCNxM8rG5rWG5comsrZkUibhw15g 06RaXEhZka1cReM4HrQ== X-Google-Smtp-Source: AGHT+IGg+LSnQo6vibvjrS5qWozQjW5MNaffdqRfjcCBQJ7iPK24ykKjp0cY1RmxyPOafr+mGOXCfbkKf8lcCFU= X-Received: from wmcq10.prod.google.com ([2002:a05:600c:c10a:b0:46f:aa50:d706]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:37c7:b0:46d:3a07:73cd with SMTP id 5b1f17b1804b1-4711790c31emr141389685e9.23.1761208210774; Thu, 23 Oct 2025 01:30:10 -0700 (PDT) Date: Thu, 23 Oct 2025 08:30:09 +0000 In-Reply-To: <20251022143158.64475-6-dakr@kernel.org> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251022143158.64475-1-dakr@kernel.org> <20251022143158.64475-6-dakr@kernel.org> Message-ID: Subject: Re: [PATCH v3 05/10] rust: uaccess: add UserSliceWriter::write_slice_file() From: Alice Ryhl To: Danilo Krummrich Cc: gregkh@linuxfoundation.org, rafael@kernel.org, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, tmgross@umich.edu, mmaurer@google.com, rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" On Wed, Oct 22, 2025 at 04:30:39PM +0200, Danilo Krummrich wrote: > Add UserSliceWriter::write_slice_file(), which is the same as > UserSliceWriter::write_slice_partial() but updates the given > file::Offset by the number of bytes written. > > This is equivalent to C's `simple_read_from_buffer()` and useful when > dealing with file offsets from file operations. > > Signed-off-by: Danilo Krummrich > --- > rust/kernel/uaccess.rs | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs > index 539e77a09cbc..20ea31781efb 100644 > --- a/rust/kernel/uaccess.rs > +++ b/rust/kernel/uaccess.rs > @@ -495,6 +495,30 @@ pub fn write_slice_partial(&mut self, data: &[u8], offset: usize) -> Result .map_or(Ok(0), |src| self.write_slice(src).map(|()| src.len())) > } > > + /// Writes raw data to this user pointer from a kernel buffer partially. > + /// > + /// This is the same as [`Self::write_slice_partial`] but updates the given [`file::Offset`] by > + /// the number of bytes written. > + /// > + /// This is equivalent to C's `simple_read_from_buffer()`. > + /// > + /// On success, returns the number of bytes written. > + pub fn write_slice_file(&mut self, data: &[u8], offset: &mut file::Offset) -> Result { > + if offset.is_negative() { > + return Err(EINVAL); > + } > + > + let Ok(offset_index) = (*offset).try_into() else { > + return Ok(0); > + }; > + > + let written = self.write_slice_partial(data, offset_index)?; > + > + *offset = offset.saturating_add_usize(written); This addition should never overflow: offset + written <= data.len() <= isize::MAX <= Offset::MAX I can't help but think that maybe this should be a + operation instead? Alice