From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f73.google.com (mail-ej1-f73.google.com [209.85.218.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B30E38F63E for ; Mon, 16 Mar 2026 10:52:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773658359; cv=none; b=Zbp58DgGWlkAIFlbZfph6nvtLeJq7gqVsHj4qjydI6MRMaNo5wA8OUTIw86ga5QwTj4LKT48xupB8KnYm2fLFHKSeLtKq/G0N4pCt++beWY6DGnss3zoL9KPGwFUCeLzQUC6v15jDJuu6HYTJn1IelFs2LEve3i5cQ2SXAf0qsA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773658359; c=relaxed/simple; bh=L26jm5jX24iJ3KU18ihZvHPzNtD1XydWhsRzUBY1WTE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=q/ObdTcIJ8RiLk93v/67nhXBHnS0Rgfk71gc3XwQuw208HhDJXTSxJaJ4hFff1N0xizIs/R+oameG3OROkJOIwLuo9iPE3Ept3vYOTHQVQQO12F4Cv59YmfQujH+ZL4W4TsApsyVbs/xU+cnHB4GJ5rKVwxz8hfvSY6CoLmDgR4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=n0mYfS2R; arc=none smtp.client-ip=209.85.218.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="n0mYfS2R" Received: by mail-ej1-f73.google.com with SMTP id a640c23a62f3a-b9766fcff6fso329872166b.0 for ; Mon, 16 Mar 2026 03:52:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773658356; x=1774263156; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=W2E+qOfGop+QubRQ5BjqIf2g5ptnhpPI53+IOJpnWpE=; b=n0mYfS2RCtrEsy9SwWQwLvPwLry19aIbQS++V/6FquchFRX0DMV94ZzYDwM/+GeSAL 5tIvCHA9AL2Phab61tuF9GlYDbPlmBL53J4PrpUTSywBmY9sS6md7T8jx+RH0RfVjXtg nUjgjzpuefqlEd5NYh8dOlQFFk61ShcoIp2Aq+c1zNjnVpHAoc5KwDJtD7D/p7L8xzH/ sRnq5tgAkZ2t1zXirJ1x17Di23CjcBr/rv2M6rhtvlURllmRReQJRp4etYIz6NgQddPY 1D2xtSRjYJt2GrCHn60iADvXonRCDAPFkSEqJVHbSHTYYuLGh4X6M9KKY7I8xKQw9sh8 lyyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773658356; x=1774263156; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=W2E+qOfGop+QubRQ5BjqIf2g5ptnhpPI53+IOJpnWpE=; b=AUueIaMsb/fl1U8N5tiFXsEmBKZvcP9k9toSBSNa6/Mro4BoSA3/M5GBY7HIweicme WUoX00M9noFC58F9oINnn050nLCjZeZuD/RdfcuwoTEh5SJdbJ1vZH2Iil4gmQRrA3zQ 8KSzj584lBqCNbw/5yFJ1OyTY/DApgOhsA0VU0FgmsiajYRs8/HKhvBTlaOOXb3dymkz 7mr9R+SSHCeUsGUB8rkN3rmL9VTJFn8Zp34/WsAExK7EOvoBSFtjkFZ9+OXZSxCbp5F8 K1DDmZsv4Z9KaKpuXrN7UcwnCyiWpMSqaLG4XooZSfWY6xDbEZ7GBPEaWoxHCirH4z1n qFxA== X-Forwarded-Encrypted: i=1; AJvYcCXIRqs4MW5OpketK9VeXpm0ZE23tMYwlwwN403eHki+GIjZe3NARu5PBzk8zjg0T0PLh+ZECXq4wDw/O990zw==@vger.kernel.org X-Gm-Message-State: AOJu0YxMhYUjceLBt9ARoFYberm/LyBhurq4e3Gp9QlbfgaCyBbtlx1l zGURwHryCCHA/23cr8YySeU70CRxXgoCzQi4axs66Iu4OFCwhL76e3oSOIJNkmzdkoAW88elx1S XXqQ3axopdcErfS7onA== X-Received: from ejcuc33.prod.google.com ([2002:a17:907:c8a1:b0:b93:4f5f:7d88]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a17:907:1c0a:b0:b97:a39d:ae3d with SMTP id a640c23a62f3a-b97a39dc4c4mr350209766b.44.1773658355573; Mon, 16 Mar 2026 03:52:35 -0700 (PDT) Date: Mon, 16 Mar 2026 10:52:34 +0000 In-Reply-To: <20260216-rnull-v6-19-rc5-send-v1-20-de9a7af4b469@kernel.org> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260216-rnull-v6-19-rc5-send-v1-0-de9a7af4b469@kernel.org> <20260216-rnull-v6-19-rc5-send-v1-20-de9a7af4b469@kernel.org> Message-ID: Subject: Re: [PATCH 20/79] block: rnull: add discard support From: Alice Ryhl To: Andreas Hindborg Cc: Boqun Feng , Jens Axboe , Miguel Ojeda , Gary Guo , "=?utf-8?B?QmrDtnJu?= Roy Baron" , Benno Lossin , Trevor Gross , Danilo Krummrich , FUJITA Tomonori , Frederic Weisbecker , Lyude Paul , Thomas Gleixner , Anna-Maria Behnsen , John Stultz , Stephen Boyd , Lorenzo Stoakes , "Liam R. Howlett" , linux-block@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="utf-8" On Mon, Feb 16, 2026 at 12:35:07AM +0100, Andreas Hindborg wrote: > +configfs_attribute!(DeviceConfig, 10, > + show: |this, page| show_field(this.data.lock().discard, page), > + store: |this, page| store_with_power_check(this, page, |this, page| { > + if !this.data.lock().memory_backed { > + return Err(EINVAL); > + } > + this.data.lock().discard = kstrtobool_bytes(page)?; Similar to the race I mentioned earlier with store_with_power_check(), this is also a TOCTOU race. > + discard: u8 { > + default: 0, > + description: > + "Support discard operations (requires memory-backed null_blk device). Default: false", > + }, kstrtobool again here... > -type TreeNode = Owned; > +const _CHEKC_STATUS_WIDTH: () = build_assert!((PAGE_SIZE >> SECTOR_SHIFT) <= 64); Use static_assert! or assert! here. Alice