From: Jaegeuk Kim Subject: Re: [f2fs-dev] [RFC PATCH 10/10] f2fs: fs-verity support Date: Tue, 28 Aug 2018 00:27:56 -0700 Message-ID: <20180828072756.GC29049@jaegeuk-macbookpro.roam.corp.google.com> References: <20180824161642.1144-1-ebiggers@kernel.org> <20180824161642.1144-11-ebiggers@kernel.org> <20180826173507.GC728@sol.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Biggers , Chao Yu , Dmitry Kasatkin , Michael Halcrow , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-ext4@vger.kernel.org, Mimi Zohar , Victor Hsieh To: Chao Yu Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org 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, and I think this should be aligned to the encryption bit. Moreover, we guarantee i_flags less strictly from power-cut than i_advise. > > 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 > >