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Date: Mon, 20 Oct 2025 11:41:18 +0200
Message-Id: <DDN1U7ZVN7O7.1OL96WGTK3VJK@kernel.org>
Subject: Re: [PATCH 3/7] rust: debugfs: support for binary large objects
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-kernel@vger.kernel.org>
To: "Alice Ryhl" <aliceryhl@google.com>
From: "Danilo Krummrich" <dakr@kernel.org>
References: <20251003222729.322059-1-dakr@kernel.org>
 <20251003222729.322059-4-dakr@kernel.org> <aPI9tNoh0I3KGDjl@google.com>
 <DDKO9M4P06HS.3UMGG3QR7BX67@kernel.org> <aPS0aTUUwDsXmHFN@google.com>
 <DDM9EDPP7XQN.2SW537AZ7DAZ9@kernel.org> <aPXvJPcSgZdNlGtB@google.com>
 <DDN1PLK58C34.2XF7BCBQNAW5X@kernel.org> <aPYDY8mdHWjyOU3l@google.com>
In-Reply-To: <aPYDY8mdHWjyOU3l@google.com>

On Mon Oct 20, 2025 at 11:39 AM CEST, Alice Ryhl wrote:
> On Mon, Oct 20, 2025 at 11:35:15AM +0200, Danilo Krummrich wrote:
>> On Mon Oct 20, 2025 at 10:13 AM CEST, Alice Ryhl wrote:
>> > I ended up using i64 for simple_read_from_buffer in iov.rs instead of
>> > loff_t. But if they can differ, then yeah let's introduce a loff_t typ=
e
>> > alias.
>>=20
>> No, I don't think they can differ (I used i64 in earlier version that di=
dn't
>> make it to the list as well), but I think it could still make sense to i=
ndicate
>> the relationship with loff_t. When I see an i64, an offset into a buffer=
 is not
>> the first thing that comes to my mind.
>>=20
>> What about uaccess::Offset?
>
> Hmm. That seems wrong. loff_t is a *file position*, so it should go in
> kernel::fs, right? We're only using it in uaccess/iov because they
> happen to have utility methods to help with implementing fops entries.
> None of the "base" uaccess/iov functions use loff_t for anything since
> they deal with sizes in the address space, for which usize is the
> correct type.

Indeed, fair enough.