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 <ebiggers@xxxxxxxxxx>
>>>>> #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
>>>
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>
> .
>
