From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83164C64E90 for ; Tue, 1 Dec 2020 02:40:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CA3920857 for ; Tue, 1 Dec 2020 02:40:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727156AbgLACkC (ORCPT ); Mon, 30 Nov 2020 21:40:02 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:8892 "EHLO szxga07-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727041AbgLACkC (ORCPT ); Mon, 30 Nov 2020 21:40:02 -0500 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4ClRB729kwz761J; Tue, 1 Dec 2020 10:38:55 +0800 (CST) Received: from [10.136.114.67] (10.136.114.67) by smtp.huawei.com (10.3.19.206) with Microsoft SMTP Server (TLS) id 14.3.487.0; Tue, 1 Dec 2020 10:39:16 +0800 Subject: Re: [f2fs-dev] [PATCH v2] f2fs: compress: add compress_inode to cache compressed blocks To: Eric Biggers CC: , , References: <20201126103709.80006-1-yuchao0@huawei.com> <7ecb947e-2f8c-abd7-c116-c82c474fded7@huawei.com> From: Chao Yu Message-ID: <11c11980-1cef-eac5-d42a-4acd4d87565c@huawei.com> Date: Tue, 1 Dec 2020 10:39:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.136.114.67] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/12/1 2:11, Eric Biggers wrote: > On Fri, Nov 27, 2020 at 09:01:47AM +0800, Chao Yu wrote: >> On 2020/11/27 1:55, Eric Biggers wrote: >>> On Thu, Nov 26, 2020 at 06:37:09PM +0800, Chao Yu wrote: >>>> Support to use address space of inner inode to cache compressed block, >>>> in order to improve cache hit ratio of random read. >>>> >>>> Signed-off-by: Chao Yu >>> >>> If the file is also encrypted, are the compressed pages that are cached still >>> encrypted, or are they decrypted? >> >> In current implementation, they are decrypted in cache. >> > > One of the things the FS_IOC_REMOVE_ENCRYPTION key ioctl is supposed to > accomplish is evicting all the pagecache pages for all encrypted files that were > using a particular key. This happens as a consequence of the ioctl evicting the > inodes that were using that key. If the user is also using the init_on_free=1 > kernel command-line option to enable automatic zeroing of all freed memory, that > should cause those inode's pagecache pages (which contain decrypted data) to be > zeroed, so that they can't be compromised later by an online attack. > > This new filesystem-wide cache containing decrypted pages might break that. It > sounds like when an inode is evicted, its cached pages won't necessarily be > evicted from this new filesystem-wide cache. Correct. > > Can you ensure that pages get evicted from this new cache when the inode to > which they belong is evicted? Not yet with current implementation, let me consider to find a way to make sure all cached compressed pages being evicted during f2fs_evict_inode(). Thanks, > > - Eric > . >