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 75CD81DE89A; Tue, 8 Oct 2024 12:24:57 +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=1728390297; cv=none; b=BPL4PBixk2Usex/NFCXyM+xgTJlJr6pd/xgVR1UHrhLiB3NRJkM3qgVKNfUaGRola0AMgAED8BR0/NFEc93QCAW0OUpOhDQuIjjwi6jGbkjkLlObj3a1zF5u3CTbU+UhSQKojqq5dREYWj9OkvX6haIpbPzq5WT1ikuunLTseKs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728390297; c=relaxed/simple; bh=soYqjmR5rDWWGq+N1p8X4deAQOqe59uVAg9kez8eR5k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nUATp1EOopxZQq3o/xj/dVSZ7sz0roBlbraoaHZDxBXBgPRKKg0LX+5x0cBGWKfQDc16sMqE0kbXyFpqa+tyYvdY+nJ+WZCLeYHmKiHn6RSIHIe9pMhUuWpImrY+8lzSc5KmKUoZIUDby6uBrVZw9sFOCCFJIH0GpQ9ZOGZj4zw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RGhzWKI3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RGhzWKI3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF5BCC4CEC7; Tue, 8 Oct 2024 12:24:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728390297; bh=soYqjmR5rDWWGq+N1p8X4deAQOqe59uVAg9kez8eR5k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RGhzWKI3W8o9/j6VGez2D/PdTS/dTM7ommxS4PolxGo9iwpDRsdNBJHk74foQNu// OTo6aDbWPmlFIHXGVhoIfv1pAl0TWf03A3VXTeovmUk6iXo9BKxeKT9KZF8f9DoBn4 B5cpjH8wuZ7BqCOO1G/ljBRG7cwyytUKiB4MikAo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christian Brauner , Jan Kara , Theodore Tso , Sasha Levin Subject: [PATCH 6.10 249/482] ext4: dont set SB_RDONLY after filesystem errors Date: Tue, 8 Oct 2024 14:05:12 +0200 Message-ID: <20241008115658.091520614@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115648.280954295@linuxfoundation.org> References: <20241008115648.280954295@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ 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 edc692984404d..04b78c479fd7a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -735,11 +735,12 @@ 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 update_super_work(struct work_struct *work) -- 2.43.0