From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1B86A20F149; Fri, 4 Oct 2024 18:27:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066456; cv=none; b=EkPeMDVs+1vSyWVa8RB2vp3hSzZYm9p7c1O50scykKmA4C9TlGh6i/WqL1PQnKsi8KTysLdAa3nz1nONppt/PNysKsf4NwqX3ZTLVD1u492QNSriVOfLHBxigpo6KHxpu6rGN/yr/U4f++GsoxTiAxsfaEbWotZdrcyMkGeyOK8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066456; c=relaxed/simple; bh=OCCs5OiQLjs6eDiIaCmMXrSMp8ufgAgkbAVZDTZJULE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=h8UgbkUajnZ+ZvpjAaecMHo6amPLOWeOdmE2mfDo+g1FB+7eBpWhPoDEUobc8fEtEeRpRvLk2Gg+4JxL2spAcnLmUBwYEahAu1wz0kgoOlUadz7VcpKadigWb9enso4kIA6B9hthyuXMJmmy3gFIbI0zl8+9J+xcY8L53a2qYfc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s4Sn6m11; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="s4Sn6m11" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD335C4CECC; Fri, 4 Oct 2024 18:27:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728066454; bh=OCCs5OiQLjs6eDiIaCmMXrSMp8ufgAgkbAVZDTZJULE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s4Sn6m114q7oHHWX3Tb/837rwN4+VQEV2xk02BFHqHvtjWcU6ffr3ohtycfQ8nbFG RkXU9KswmX9VRFpBt2DM4BKFMeyyg+tULKz/FyxKhykIwcxe0nasAtNl509FrBJuMz hQ3KlrJhRMD/2tXKtllZmfrhuBbXttLh3R7ncfYPLfotz/XfB9iktrmddh5EPUof5a +oucE/xVM+vwjnqPzvfVC2tJkTHBqsloqrZGcDOh4HbhFAVKgK3k/t785JzzWWoOhp F5krOKw1B1ImK6uLGxk1JNmUMJdBhH/RTFzpb7Hw7WBjIrurqsVVVkEKbK0Bi5MKin TAzQIznyKOV1g== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jan Kara , Christian Brauner , Theodore Ts'o , Sasha Levin , adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org Subject: [PATCH AUTOSEL 6.1 09/42] ext4: don't set SB_RDONLY after filesystem errors Date: Fri, 4 Oct 2024 14:26:20 -0400 Message-ID: <20241004182718.3673735-9-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241004182718.3673735-1-sashal@kernel.org> References: <20241004182718.3673735-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.112 Content-Transfer-Encoding: 8bit From: Jan Kara [ Upstream commit d3476f3dad4ad68ae5f6b008ea6591d1520da5d8 ] When the filesystem is mounted with errors=remount-ro, we were setting SB_RDONLY flag to stop all filesystem modifications. We knew this misses proper locking (sb->s_umount) and does not go through proper filesystem remount procedure but it has been the way this worked since early ext2 days and it was good enough for catastrophic situation damage mitigation. Recently, syzbot has found a way (see link) to trigger warnings in filesystem freezing because the code got confused by SB_RDONLY changing under its hands. Since these days we set EXT4_FLAGS_SHUTDOWN on the superblock which is enough to stop all filesystem modifications, modifying SB_RDONLY shouldn't be needed. So stop doing that. Link: https://lore.kernel.org/all/000000000000b90a8e061e21d12f@google.com Reported-by: Christian Brauner Signed-off-by: Jan Kara Reviewed-by: Christian Brauner Link: https://patch.msgid.link/20240805201241.27286-1-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/super.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 3db39758486e9..3bf214d4afef5 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -692,11 +692,12 @@ static void ext4_handle_error(struct super_block *sb, bool force_ro, int error, ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only"); /* - * Make sure updated value of ->s_mount_flags will be visible before - * ->s_flags update + * EXT4_FLAGS_SHUTDOWN was set which stops all filesystem + * modifications. We don't set SB_RDONLY because that requires + * sb->s_umount semaphore and setting it without proper remount + * procedure is confusing code such as freeze_super() leading to + * deadlocks and other problems. */ - smp_wmb(); - sb->s_flags |= SB_RDONLY; } static void flush_stashed_error_work(struct work_struct *work) -- 2.43.0