On 08/29, Chao Yu wrote:
> On 2018/8/29 1:01, Jaegeuk Kim wrote:
> > On 08/28, Chao Yu wrote:
> >> 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 <ebigg...@google.com>
> >>>>>>> #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.
> >
> > We're using that.
>
> Oops, if it was in production, I agree to keep it in i_advice, otherwise, we
> still can discuss its location.
>
> >
> >>
> >>> 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?
> >
> > In __f2fs_ioc_setflags, f2fs_mark_inode_dirty_sync(inode, false);
>
> Ah, that's right, do you remember why we treat them with different recoverable
> level?
Since I thought that such the flags wouln't be critical on power cuts, but be
enough for us to guarantee by write_inode() or fsync().
>
> Thanks,
>
> >
> >>
> >> 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
> >>>>>
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> >>>>> _______________________________________________
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> >>>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> >>>>>
> >>>
> >>> .
> >>>
> >
> > .
> >
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