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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 EDE74C4321A for ; Tue, 11 Jun 2019 01:37:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CEEA420652 for ; Tue, 11 Jun 2019 01:37:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390578AbfFKBh2 (ORCPT ); Mon, 10 Jun 2019 21:37:28 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:18123 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2389168AbfFKBh2 (ORCPT ); Mon, 10 Jun 2019 21:37:28 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 9C5ADD4619E6F16E261B; Tue, 11 Jun 2019 09:37:25 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.205) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 11 Jun 2019 09:37:18 +0800 Subject: Re: [PATCH 1/2] staging: erofs: add requirements field in superblock To: Gao Xiang , Greg Kroah-Hartman , CC: LKML , , "Chao Yu" , Miao Xie , , Fang Wei , References: <20190610093640.96705-1-gaoxiang25@huawei.com> From: Chao Yu Message-ID: Date: Tue, 11 Jun 2019 09:37:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190610093640.96705-1-gaoxiang25@huawei.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/6/10 17:36, Gao Xiang wrote: > There are some backward incompatible optimizations pending > for months, mainly due to on-disk format expensions. > > However, we should ensure that it cannot be mounted with > old kernels. Otherwise, it will causes unexpected behaviors. > > Fixes: ba2b77a82022 ("staging: erofs: add super block operations") > Cc: # 4.19+ > Signed-off-by: Gao Xiang > --- > drivers/staging/erofs/erofs_fs.h | 11 +++++++++-- > drivers/staging/erofs/super.c | 8 ++++++++ > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h > index fa52898df006..531821757845 100644 > --- a/drivers/staging/erofs/erofs_fs.h > +++ b/drivers/staging/erofs/erofs_fs.h > @@ -17,10 +17,16 @@ > #define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2 > #define EROFS_SUPER_OFFSET 1024 > > +/* > + * Any bits that aren't in EROFS_ALL_REQUIREMENTS should be > + * incompatible with this kernel version. > + */ > +#define EROFS_ALL_REQUIREMENTS 0 > + > struct erofs_super_block { > /* 0 */__le32 magic; /* in the little endian */ > /* 4 */__le32 checksum; /* crc32c(super_block) */ > -/* 8 */__le32 features; > +/* 8 */__le32 features; /* extra features for the image */ > /* 12 */__u8 blkszbits; /* support block_size == PAGE_SIZE only */ > /* 13 */__u8 reserved; > > @@ -34,8 +40,9 @@ struct erofs_super_block { > /* 44 */__le32 xattr_blkaddr; > /* 48 */__u8 uuid[16]; /* 128-bit uuid for volume */ > /* 64 */__u8 volume_name[16]; /* volume name */ > +/* 80 */__le32 requirements; /* all mandatory minimum requirements */ > > -/* 80 */__u8 reserved2[48]; /* 128 bytes */ > +/* 84 */__u8 reserved2[44]; /* 128 bytes */ Xiang, It needs to update the comment behind reserved2, it's locating at 132 bytes. > } __packed; > > /* > diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c > index f580d4ef77a1..815e5825db59 100644 > --- a/drivers/staging/erofs/super.c > +++ b/drivers/staging/erofs/super.c > @@ -104,6 +104,14 @@ static int superblock_read(struct super_block *sb) > goto out; > } > > + /* check if the kernel meets all mandatory requirements */ > + if (le32_to_cpu(layout->requirements) & (~EROFS_ALL_REQUIREMENTS)) { > + errln("too old to meet minimum requirements: %x supported: %x", It will be better to give a suggestion to user to upgrade kernel version to match the image with new layout, otherwise it's just a little confused about above printed message. Thanks, > + le32_to_cpu(layout->requirements), > + EROFS_ALL_REQUIREMENTS); > + goto out; > + } > + > sbi->blocks = le32_to_cpu(layout->blocks); > sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr); > #ifdef CONFIG_EROFS_FS_XATTR >