From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga07-in.huawei.com ([45.249.212.35]:49495 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727052AbeH1NKu (ORCPT ); Tue, 28 Aug 2018 09:10:50 -0400 Subject: Re: [f2fs-dev] [RFC PATCH 10/10] f2fs: fs-verity support To: Jaegeuk Kim , Chao Yu CC: Eric Biggers , Dmitry Kasatkin , Michael Halcrow , , , , , , , Mimi Zohar , Victor Hsieh References: <20180824161642.1144-1-ebiggers@kernel.org> <20180824161642.1144-11-ebiggers@kernel.org> <20180826173507.GC728@sol.localdomain> <20180828072756.GC29049@jaegeuk-macbookpro.roam.corp.google.com> From: Chao Yu Message-ID: <63a19512-e938-d239-9e3c-f6ecc479478c@huawei.com> Date: Tue, 28 Aug 2018 17:20:01 +0800 MIME-Version: 1.0 In-Reply-To: <20180828072756.GC29049@jaegeuk-macbookpro.roam.corp.google.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 2018/8/28 15:27, Jaegeuk Kim wrote: > On 08/27, Chao Yu wrote: >> Hi Eric, >> >> On 2018/8/27 1:35, Eric Biggers wrote: >>> Hi Chao, >>> >>> On Sat, Aug 25, 2018 at 01:54:08PM +0800, Chao Yu wrote: >>>> On 2018/8/25 0:16, Eric Biggers wrote: >>>>> From: Eric Biggers >>>>> #ifdef CONFIG_F2FS_CHECK_FS >>>>> #define f2fs_bug_on(sbi, condition) BUG_ON(condition) >>>>> #else >>>>> @@ -146,7 +149,7 @@ struct f2fs_mount_info { >>>>> #define F2FS_FEATURE_QUOTA_INO 0x0080 >>>>> #define F2FS_FEATURE_INODE_CRTIME 0x0100 >>>>> #define F2FS_FEATURE_LOST_FOUND 0x0200 >>>>> -#define F2FS_FEATURE_VERITY 0x0400 /* reserved */ >>>>> +#define F2FS_FEATURE_VERITY 0x0400 >>>>> >>>>> #define F2FS_HAS_FEATURE(sb, mask) \ >>>>> ((F2FS_SB(sb)->raw_super->feature & cpu_to_le32(mask)) != 0) >>>>> @@ -598,7 +601,7 @@ enum { >>>>> #define FADVISE_ENC_NAME_BIT 0x08 >>>>> #define FADVISE_KEEP_SIZE_BIT 0x10 >>>>> #define FADVISE_HOT_BIT 0x20 >>>>> -#define FADVISE_VERITY_BIT 0x40 /* reserved */ >>>>> +#define FADVISE_VERITY_BIT 0x40 >>>> >>>> As I suggested before, how about moving f2fs' verity_bit from i_fadvise to more >>>> generic i_flags field like ext4, so we can a) remaining more bits for those >>>> demands which really need file advise fields. b) using i_flags bits keeping line >>>> with ext4. Not sure, if user want to know whether the file is verity one, it >>>> will be easy for f2fs to export the status through FS_IOC_SETFLAGS. >>>> >>>> #define EXT4_VERITY_FL 0x00100000 /* Verity protected inode */ >>>> >>>> #define F2FS_VERITY_FL 0x00100000 /* Verity protected inode */ >>>> >>> >>> I don't like using i_advise much either, but I actually don't see either >>> location being much better than the other at the moment. The real problem is an >>> artificial one: the i_flags in f2fs's on-disk format are being assumed to use >> >> Yeah, but since most copied flags from vfs/ext4 are not actually used in f2fs, >> also 0x00100000 bit is not used now, so we can just define it now directly for >> verity bit. >> >> Cleanup and remapping in ioctl interface for those unused flags, we can do it >> latter? > > No, it was reserved by f2fs-tools, That's not a problem, since we didn't use that reserved bit in any of images now, there is no backward compatibility issue. > and I think this should be aligned to the encryption bit. Alright, we could, but if so, i_advise will run out of space earlier, after that we have to add real advice bit into i_inline or i_flags, that would be a little weird. For encryption bit, as a common vfs feature flag, in the beginning of encryption development, it will be better to set it into i_flags, IMO, but now, we have to keep it as it was. > Moreover, we guarantee i_flags less strictly from power-cut than i_advise. IMO, in power-cut scenario, it needs to keep both i_flags and i_advise being recoverable strictly. Any condition that we can not recover i_flags? Thanks, > >> >> Thanks, >> >>> the same numbering scheme as ext4's on-disk format, which makes it seem that >>> they have to be in sync, and that all new ext4 flags (say, EA_INODE) also >>> reserve bits in f2fs and vice versa, when they in fact do not. Instead, f2fs >>> should use its own numbering for its i_flags, and it should map them to/from >>> whatever is needed for common APIs like FS_IOC_{GET,SET}FLAGS and >>> FS_IOC_FS{GET,SET}XATTR. >>> >>> So putting the verity flag in *either* location (i_advise or i_flags) is just >>> kicking the can down the road. If I get around to it I will send a patch that >>> cleans up the f2fs flags properly...> >>> Thanks, >>> >>> - Eric >>> >>> ------------------------------------------------------------------------------ >>> Check out the vibrant tech community on one of the world's most >>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >>> _______________________________________________ >>> Linux-f2fs-devel mailing list >>> Linux-f2fs-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>> > > . >