From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E49B02135B8; Fri, 18 Sep 2026 07:41:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789717274; cv=none; b=pwMGw0J9fnofs/gSogM+emnVWVO6Ejt2NLTiy6kcecK9MESPVJKX1tlOjdMZv7whLU/hP6X3kAD2uvWRwwqUKCnDVJ3/McR7SQ9rkhvFHkV67AiuuypMelxWU5w0Brg2nTpv5nfUtwM8MM3liQOb2BK7imxIG5EsPQ2KHS+1qZM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789717274; c=relaxed/simple; bh=VaQRPbdE5ZMe79jiWvwqKPU9sGCSdXB4T4pwiTG7a9M=; h=MIME-Version:Date:From:To:Cc:Message-Id:In-Reply-To:References: Subject:Content-Type; b=JUVtBtt0uyqxd47nnBexwcC4+DeIqxxXkfoQe828YfdchzYZ/d9RwXyyKW0hq/gwAIZRUqeF4aL6wsRcfF3FOGnp+f5PKDnh3ModVvDYrb2mqA8kVaobH3Nfv8FP1C5/S2/3XUcQ5ZgmL/zWNSOAC6dTvhcPumuByDR+goagwBY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P4NkIfkD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P4NkIfkD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95B921F000FF; Fri, 18 Sep 2026 07:41:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789717261; bh=iSPd4nZ0D11kwmK8/wKlqzxDQXWnyxbAgGRwTuBgXfE=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=P4NkIfkDo0AkRReJINxUCR30LavYTQsZPVg4igvjTgTaOxiOzVzNY8DN2TYLVIRtR AIpfPwao4ZsAu+dbYCSa0crrGQBWlu5Tml1+goIEzA/B4qaDlgd6tf+3wyYzLo1KYZ ZzJSesqWG0usN0EXLTQvMAVOzTUNCmGsBe3hpK9aqiUDHE8TejnbjTB+nkDoIaWgNk 7n/oe125Zxii4fEDEPIFDBfbgXgWQkLNxoMFKtsMh/cDJ9YSpVeerGnjbx/Bh1/scQ aG1z/SDtQczuBk0U8zLag0DKL5jpmw7506FQB0AiKPIXgLceN01GmOcDU8Mc1kXINb G7UljOLdxZUxg== Received: from ams-compute-02.internal (ams-compute-02.internal [10.64.2.62]) by mailfauth.ams.internal (Postfix) with ESMTP id E1838198005E; Fri, 18 Sep 2026 03:40:58 -0400 (EDT) Received: from ams-imap-11 ([10.64.2.31]) by ams-compute-02.internal (MEProxy); Fri, 18 Sep 2026 03:40:58 -0400 X-ME-Sender: X-ME-Proxy-Cause: dmFkZTGa4VA+2O+Tz0pIvtRzJ3ayOXhSXYw7OYrYkJhCWqbenIbEz3WyksuMKE9P7JxZPw GWgEpDpU3aAv1OU5+esIL/88+Xl6f0uciIzMG1Er8aE+vW271njkNfxFULwkmgLrONnhuO 4+lXAENCTrdeKNJD1tJS8oFVge6qKbhpNTyLZLIUlZyLvT8ofvpPWbdZTVDqY3TlGHdwHc X+eoJXNkH3h0fO7ymlvLv2vdQeIGjqmfFK1TVarAGQ+x11awu87vS66ObYP35e3rFYO2qu m+iV1bhctzQ/8V8Ey9WQf23/BewK6YKIq22phOlTGrkguQ22gn8G3QnnBlBBe0hmaAwSI7 K7yFEehOwJSw3wvjx/8CwKtJAvW2V/SMVoz0OwvM5Q9CzfvSiXjZf2iLIlZXvbvrupf79o QP82+sPQPs1OvEU8WzlYR+6BnPLy1SUAHVgZpBdGoJBd3VGvpEAbvepFeBkLCMRosMB835 Sztz88FHOfe4YKV2YK4l5t2pv6Utk/SXP0mzd6bDWsSAzwwfMD8qEdVvHSPW2JbDFsbcOQ bjCa3oveW6kIjGdy4ZMM/E6IaZQNUg2PZyxkKRTeYKcEL0I3wrBOBR58AZ9FKH49OO6ugr 0Wki4d99/sYqXfAEcBxJypu9FM0+sirklnITFurt77fVGkJ9onjRM0WGXvRw X-ME-Proxy: Feedback-ID: ice86485a:Fastmail Received: by mailuser.ams.internal (Postfix, from userid 501) id 639C3F8007E; Fri, 18 Sep 2026 03:40:57 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Fri, 18 Sep 2026 09:40:37 +0200 From: "Ard Biesheuvel" To: "Prashant Singh" , "Jeremy Kerr" Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, "Jonathan Corbet" , linux-doc@vger.kernel.org Message-Id: <203b540d-2a53-4080-9344-dcf9063e62fe@app.fastmail.com> In-Reply-To: <20260917165035.15187-1-singhpra@juniper.net> References: <20260917071600.5587-1-singhpra@juniper.net> <60d0b7a5-cc1f-4841-b4f2-754e1b921794@app.fastmail.com> <20260917165035.15187-1-singhpra@juniper.net> Subject: Re: [PATCH] efivarfs: avoid slow QueryVariableInfo() in statfs() Content-Type: text/plain Content-Transfer-Encoding: 7bit On Thu, 17 Sep 2026, at 18:50, Prashant Singh wrote: > On Thu, 17 Sep 2026, at 10:36, Ard Biesheuvel wrote: >> Could we instead introduce a mount option that disables used/available >> reporting entirely? Feel free to set the default to 'disabled' when >> CONFIG_PREEMPT_RT is set. > > Will do. I'll add a bool mount option (e.g. statfs_capacity) that, when > disabled, skips QueryVariableInfo() in statfs() and reports 0 > used/available, defaulting to disabled under CONFIG_PREEMPT_RT. > Let's call it nostatfs. > If you'd rather df still show numbers without the per-statfs firmware > call, I could instead prime the value once at mount and serve that > (stale but non-zero) as a "cached" mode -- i.e. a tri-state option: > > statfs_capacity=live|cached|off > live - current behaviour: rate-limited QueryVariableInfo() on statfs() > cached - prime once at mount, serve the static value (no per-statfs call) > off - report 0 used/available (no firmware call at all) > > default: live on non-RT, off on CONFIG_PREEMPT_RT > > Happy either way. > No, let's keep it simple. Thanks.