From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk2-f36.google.com (mail-qk2-f36.google.com [74.125.230.228]) (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 BC66828505E for ; Sun, 27 Sep 2026 06:02:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.230.228 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790488956; cv=none; b=Xz4bPlVGTW8gh8YWb3EZbP18jgzgWXKWjH+KkW3JJeO0xCXIQDKAhQAiP3a5sf/IWhyQf62qVAUivnNpKDcLZl3jjLgdSXpboDjw28WSankApP48Gxsh9MSHTUDRt8iWvhmHhF/DU1NRN7MOpcyvbqpeiw8OhwFkZvRdRdPFgoQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790488956; c=relaxed/simple; bh=1jCjtYoS8P7He0eHB/co+eUvc5U6jhinCxysS9BksKw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:MIME-Version: Content-Type; b=CVAG+cODNVZ5N3SQXIHZ0GC+LM01Njd0LWJcTzKEJb6g8rbcPZPvv0PjkeT+6o/YQlDIgnWqWVsr0REsb12E7H5pfOui27rUGy+GPe8ncey+C2NbvhRfqqD1G6zsuSZhcJXbcfxzoiXbXh5SI0LF/i73QNapSqBEz4vC9eCknNw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Y3vS2Wfv; arc=none smtp.client-ip=74.125.230.228 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Y3vS2Wfv" Received: by mail-qk2-f36.google.com with SMTP id d75a77b69052e-533264052d0so7962201cf.1 for ; Sat, 26 Sep 2026 23:02:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790488954; x=1791093754; darn=vger.kernel.org; h=content-type:content-transfer-encoding:mime-version:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=1jCjtYoS8P7He0eHB/co+eUvc5U6jhinCxysS9BksKw=; b=Y3vS2WfvA+l+q781tyXHMb4Mq24JNxDkFriCO7oGUQrSpwuvCK8oNbj+29bV9C+Htx z7ze8JW9+WlOa2VB9vB0epTu5Qf/B6HlVU+UAO8b1B7d2w2z7r9qC5FrZ8HCH4j5ubGg +aaYRxJYRqnJNfPRFr7KmwDlIvgjk/kegIaR/0acgWuPrOgw3tTA6pzeK+I65jN1LG34 d/3drkR2OPvq+DmYFG/jc9uyMtuXZJV7/oJ76v+RxzNcticqlBEPkV9kJ4k8C/9XdmcR lQ6gPjBNandaValARMi+4cFEf5iOc3gKxSxb+Vug3fAbv2j8pe7opRUPzyyqvpmYwmY4 tXMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790488954; x=1791093754; h=content-type:content-transfer-encoding:mime-version:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=1jCjtYoS8P7He0eHB/co+eUvc5U6jhinCxysS9BksKw=; b=Y0n+6hAqsdUEuTRwGHQqbRENo8tV2JM/uwpFEUSmhDbnxVALFZWN92ZnLzTTJwxeRG c/csLBvTPby66BNWVOMnHsyvuc0191tIl/Z/ePBE6zhoog1z8pG+Ok32nDpH06QfNxk1 sSwp861eKNa65pF2BsdePLQ/AnSQ4nBlHfvFijJuBtQTPY8c0UtDVpmccxG0dLBYx6eI wPSgQNu8gEbzpNAoEK/ufTKnRHJ2Z0iIWiCrtFOcJoMP9aMlzv/fd0LdQCza9LEtpR/t QLu7jWEkt5M/aHbqip1hDLAyEdaPaUvLgRvgxQOGZ/d6meuH8XyWV+D3QDx40pmhX4QK WCdQ== X-Forwarded-Encrypted: i=1; AKwUvBwNmDfNaSF28NqLNEU66E4rj7m0kcXt3lP6R9goCA6sgGiau0YSWzjp9v1cVv6/iAwepOk0IMocXxVQAOw=@vger.kernel.org X-Gm-Message-State: AFuF++n0XTvobEvyxTWuRZ5CueWxItmQB2OxA8EHf7g1zrbvfeGSb/aI A1Ck8vIMYzaisQpqdRgxal5GvgOZ1DD/AR4TGVf4NI1WYGBYXrxOUplT X-Gm-Gg: AYBFou21oyIrXgvUQQNEEoMAaRHWDkvcNH2PF/vsV9DgsyZ6sA+HIW1qdlCI1tfYcGF qqkhXhXSaxLltPF1dZ4uBDzmlJPH9EaLJkz705UaGKyr8Y9b3yF7UvTXqYgOJdLodnkMsxkVk9A YcRgDULYlNMoovdoXjJDPVddBpI0jFqBMc+OxSt9GhApS6C/LQsErSqwlakb1rcOWu0WeOmm3O/ dVDQwTd8GXgSxebBt+Z5xtMJprNQNdAhoSDv53DCUWszJk6O6spWJgdF1fo8vmnpOlCpj39sgT7 Bs5dtHfMaoowyHsaqvPn4MvGvtQGW/1KZAKyngkXetfJiSkxOyzSfyHtAY5CrV/6MQOYGCN0WzV c11RkN5ZULozFIX8j9ZZhtVyZ8ewtkKKl6ebrkJkThGEGMqSjc4bLLib6xpXGLJlArHc1KHwjME ZGbAHURDel9+ytU3UD4sD4KIwkEMO37mi6R12QfJt+P/wIR3Yzwn0eOhEkU5Ytn03MD200Ukjup qMNblY3BVli/GYM/61j9Wfor/Ft X-Received: by 2002:a05:622a:13c8:b0:530:e52a:8ef1 with SMTP id d75a77b69052e-5330b5dff3dmr142397731cf.26.1790488953719; Sat, 26 Sep 2026 23:02:33 -0700 (PDT) Received: from daniel-desktop3.localnet ([204.48.76.67]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-5332238c585sm34613801cf.20.2026.09.26.23.02.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 23:02:31 -0700 (PDT) From: Daniel Tang To: =?UTF-8?B?QW5kcsOp?= Almeida , Gabriel Krisman Bertazi , Gabriel Krisman Bertazi , Christian Brauner , linux-fsdevel@vger.kernel.org Cc: Gabriel Krisman Bertazi , Alexander Viro , Jan Kara , Theodore Ts'o , Andreas Dilger , Hugh Dickins , Andrew Morton , Jonathan Corbet , smcv@collabora.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org Subject: [BUG] Is casefold unreported in /proc/mounts? Date: Sun, 27 Sep 2026 02:02:29 -0400 Message-ID: <5193732.31r3eYUQgx@daniel-desktop3> In-Reply-To: <20241021-tonyk-tmpfs-v8-6-f443d5814194@igalia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Upon successfully mounting via `sudo mount -t tmpfs -o casefold test /mnt`, I cannot find a read-only way to determine whether this option is enabled. `mount`, `cat /proc/mounts`, and `cat /proc/mountinfo` only display "rw", "relatime", and "inode64", never "casefold" for both with and without `-o casefold`. The only way on 7.0.0-34-generic to test I found is `mkdir test ; chattr +F test ; echo $?`, but that isn't atomic. Which command can determine, without writing anything, whether someone or some program specified `-o casefold`? If absent, I suggest adding the missing info to `/proc/mounts`, likely `mm/shmem.c:shmem_show_options`. Link: https://lore.kernel.org/r/20241021-tonyk-tmpfs-v8-6-f443d5814194@igalia.com