Re: [PATCH v3 RESEND] f2fs: introduce sb.required_features to store incompatible features

From: Jaegeuk Kim
Date: Fri Aug 09 2019 - 11:26:46 EST

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On 08/06, Chao Yu wrote:
> On 2019/8/6 10:11, Jaegeuk Kim wrote:
> > On 08/06, Chao Yu wrote:
> >> On 2019/8/6 9:24, Jaegeuk Kim wrote:
> >>> On 08/06, Chao Yu wrote:
> >>>> On 2019/8/6 8:35, Jaegeuk Kim wrote:
> >>>>> On 08/02, Chao Yu wrote:
> >>>>>> On 2019/8/2 6:35, Jaegeuk Kim wrote:
> >>>>>>> On 08/01, Chao Yu wrote:
> >>>>>>>> On 2019/8/1 12:22, Jaegeuk Kim wrote:
> >>>>>>>>> On 07/31, Chao Yu wrote:
> >>>>>>>>>> On 2019/7/31 7:18, Jaegeuk Kim wrote:
> >>>>>>>>>>> On 07/29, Chao Yu wrote:
> >>>>>>>>>>>> From: Chao Yu <yuchao0@xxxxxxxxxx>
> >>>>>>>>>>>>
> >>>>>>>>>>>> Later after this patch was merged, all new incompatible feature's
> >>>>>>>>>>>> bit should be added into sb.required_features field, and define new
> >>>>>>>>>>>> feature function with F2FS_INCOMPAT_FEATURE_FUNCS() macro.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Then during mount, we will do sanity check with enabled features in
> >>>>>>>>>>>> image, if there are features in sb.required_features that kernel can
> >>>>>>>>>>>> not recognize, just fail the mount.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
> >>>>>>>>>>>> ---
> >>>>>>>>>>>> v3:
> >>>>>>>>>>>> - change commit title.
> >>>>>>>>>>>> - fix wrong macro name.
> >>>>>>>>>>>> fs/f2fs/f2fs.h | 15 +++++++++++++++
> >>>>>>>>>>>> fs/f2fs/super.c | 10 ++++++++++
> >>>>>>>>>>>> include/linux/f2fs_fs.h | 3 ++-
> >>>>>>>>>>>> 3 files changed, 27 insertions(+), 1 deletion(-)
> >>>>>>>>>>>>
> >>>>>>>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>>>>>>>>>>> index a6eb828af57f..b8e17d4ddb8d 100644
> >>>>>>>>>>>> --- a/fs/f2fs/f2fs.h
> >>>>>>>>>>>> +++ b/fs/f2fs/f2fs.h
> >>>>>>>>>>>> @@ -163,6 +163,15 @@ struct f2fs_mount_info {
> >>>>>>>>>>>> #define F2FS_CLEAR_FEATURE(sbi, mask) \
> >>>>>>>>>>>> (sbi->raw_super->feature &= ~cpu_to_le32(mask))
> >>>>>>>>>>>>
> >>>>>>>>>>>> +#define F2FS_INCOMPAT_FEATURES 0
> >>>>>>>>>>>> +
> >>>>>>>>>>>> +#define F2FS_HAS_INCOMPAT_FEATURE(sbi, mask) \
> >>>>>>>>>>>> + ((sbi->raw_super->required_features & cpu_to_le32(mask)) != 0)
> >>>>>>>>>>>> +#define F2FS_SET_INCOMPAT_FEATURE(sbi, mask) \
> >>>>>>>>>>>> + (sbi->raw_super->required_features |= cpu_to_le32(mask))
> >>>>>>>>>>>> +#define F2FS_CLEAR_INCOMPAT_FEATURE(sbi, mask) \
> >>>>>>>>>>>> + (sbi->raw_super->required_features &= ~cpu_to_le32(mask))
> >>>>>>>>>>>> +
> >>>>>>>>>>>> /*
> >>>>>>>>>>>> * Default values for user and/or group using reserved blocks
> >>>>>>>>>>>> */
> >>>>>>>>>>>> @@ -3585,6 +3594,12 @@ F2FS_FEATURE_FUNCS(lost_found, LOST_FOUND);
> >>>>>>>>>>>> F2FS_FEATURE_FUNCS(sb_chksum, SB_CHKSUM);
> >>>>>>>>>>>> F2FS_FEATURE_FUNCS(casefold, CASEFOLD);
> >>>>>>>>>>>>
> >>>>>>>>>>>> +#define F2FS_INCOMPAT_FEATURE_FUNCS(name, flagname) \
> >>>>>>>>>>>> +static inline int f2fs_sb_has_##name(struct f2fs_sb_info *sbi) \
> >>>>>>>>>>>> +{ \
> >>>>>>>>>>>> + return F2FS_HAS_INCOMPAT_FEATURE(sbi, F2FS_FEATURE_##flagname); \
> >>>>>>>>>>>> +}
> >>>>>>>>>>>> +
> >>>>>>>>>>>> #ifdef CONFIG_BLK_DEV_ZONED
> >>>>>>>>>>>> static inline bool f2fs_blkz_is_seq(struct f2fs_sb_info *sbi, int devi,
> >>>>>>>>>>>> block_t blkaddr)
> >>>>>>>>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >>>>>>>>>>>> index 5540fee0fe3f..3701dcce90e6 100644
> >>>>>>>>>>>> --- a/fs/f2fs/super.c
> >>>>>>>>>>>> +++ b/fs/f2fs/super.c
> >>>>>>>>>>>> @@ -2513,6 +2513,16 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>> return -EINVAL;
> >>>>>>>>>>>> }
> >>>>>>>>>>>>
> >>>>>>>>>>>> + /* check whether current kernel supports all features on image */
> >>>>>>>>>>>> + if (le32_to_cpu(raw_super->required_features) &
> >>>>>>>>>>>
> >>>>>>>>>>> ...
> >>>>>>>>>>> #define F2FS_FEATURE_VERITY 0x0400 /* reserved */
> >>>>>>>>>>> ...
> >>>>>>>>>>> #define F2FS_FEATURE_CASEFOLD 0x1000
> >>>>>>>>>>> #define F2FS_FEATURE_SUPPORT 0x1BFF
> >>>>>>>>>>>
> >>>>>>>>>>> if (le32_to_cpu(raw_super->required_features) & ~F2FS_FEATURE_SUPPORT) {
> >>>>>>>>>>> ...
> >>>>>>>>>>> return -EINVAL;
> >>>>>>>>>>> }
> >>>>>>>>>>
> >>>>>>>>>> Um, I thought .required_features are used to store new feature flags from 0x0.
> >>>>>>>>>>
> >>>>>>>>>> All 'F2FS_FEATURE_SUPPORT' bits should be stored in sb.feature instead of
> >>>>>>>>>> sb.required_features, I'm confused...
> >>>>>>>>>
> >>>>>>>>> I'm thinking,
> >>>>>>>>>
> >>>>>>>>> f2fs-tools sb->required_features f2fs F2FS_FEATURE_SUPPORT
> >>>>>>>>> v0 0 v0 no_check -> ok
> >>>>>>>>> v1 0x1BFF v0 no_check -> ok
> >>>>>>>>> v0 0 v1 0x1BFF -> ok
> >>>>>>>>> v1 0x1BFF v1 0x1BFF -> ok
> >>>>>>>>> v2 0x3BFF v1 0x1BFF -> fail
> >>>>>>>>> v1 0x1BFF v2 0x3BFF -> ok
> >>>>>>>>> v2 0x3BFF v2 0x3BFF -> ok
> >>>>>>>>
> >>>>>>>> I see, it's a bit waste for 0x1FFF low bits in sb->required_features. Why not
> >>>>>>>> leaving 0x0FFF in sb->feature w/o sanity check. And make all new incompatible
> >>>>>>>> features (including casefold) adding into sb->required_features.
> >>>>>>>
> >>>>>>> I don't think we can define like this, and we still have 32bits feature filed.
> >>>>>>> This would give another confusion to understand. VERITY is reserved only now.
> >>>>>>>
> >>>>>>> #define F2FS_FEATURE_CASEFOLD 0x0001
> >>>>>>
> >>>>>> Oops, so you want to make .required_features being almost a mirror of .feature,
> >>>>>> and do sanity check on it... I can see now. :P
> >>>>>>
> >>>>>> If so, why not just use .feature:
> >>>>>
> >>>>> Sometimes, we don't need to set the flag, but not required at some point.
> >>>>> (e.g., verify)
> >>>>
> >>>> Sorry, I'm not sure whether I have understood your point... :(
> >>>>
> >>>> IIUC of your point, we have defined F2FS_FEATURE_SUPPORT (0x0BFF) which excludes
> >>>> F2FS_FEATURE_VERITY (0x0400) feature bit, then once verity feature merged in
> >>>> kernel, we can add it into F2FS_FEATURE_SUPPORT, any problem we may face here?
> >>>
> >>> I was thinking the cases like "don't care features" made by mkfs. For example,
> >>> mkfs can set F2FS_FEATURE_BLKZONED, which doesn't need f2fs being supported.
> >>
> >> Yes, I can understand this.
> >>
> >> So F2FS_FEATURE_SUPPORT can exclude them directly?
> >
> > No, I'd like to control it via mkfs. Kernel always needs to say what they can
> > support, IIUC your point.
>
> Oh, it's different macros, we will define F2FS_INCOMPAT_FEATURE_SUPPORT 0x19B9,
> and F2FS_ALL_FEATURE_SUPPORT (0x0001 | 0x0002 ... ).
>
> In sanity check function, we only check .feature with
> F2FS_INCOMPAT_FEATURE_SUPPORT. And of course, meanwhile kernel will say it
> supports features in F2FS_ALL_FEATURE_SUPPORT.

Still I don't get the point where we need multiple macros. Why not user just can
give required_feature in mkfs and check it by kernel later?

>
> Thanks,
>
> >
> >>
> >> excluded:
> >>
> >> #define F2FS_FEATURE_BLKZONED 0x0002
> >> #define F2FS_FEATURE_ATOMIC_WRITE 0x0004
> >> #define F2FS_FEATURE_LOST_FOUND 0x0200
> >>
> >> included:
> >>
> >> #define F2FS_FEATURE_ENCRYPT 0x0001
> >> #define F2FS_FEATURE_EXTRA_ATTR 0x0008
> >> #define F2FS_FEATURE_PRJQUOTA 0x0010
> >> #define F2FS_FEATURE_INODE_CHKSUM 0x0020
> >> #define F2FS_FEATURE_FLEXIBLE_INLINE_XATTR 0x0040
> >> #define F2FS_FEATURE_QUOTA_INO 0x0080
> >> #define F2FS_FEATURE_INODE_CRTIME 0x0100
> >> #define F2FS_FEATURE_SB_CHKSUM 0x0800
> >> //#define F2FS_FEATURE_VERITY 0x0400 /* reserved */
> >> #define F2FS_FEATURE_CASEFOLD 0x1000
> >>
> >> #define F2FS_FEATURE_SUPPORT 0x19B9
> >>
> >> Thanks,
> >>
> >>>
> >>>>
> >>>> Thanks
> >>>>
> >>>>>
> >>>>>>
> >>>>>> kernel tool
> >>>>>> v5.2 .. 1.12
> >>>>>> #define F2FS_FEATURE_SUPPORT 0x0BFF
> >>>>>>
> >>>>>> v5.3 .. 1.13
> >>>>>> #define F2FS_FEATURE_CASEFOLD 0x1000
> >>>>>> #define F2FS_FEATURE_SUPPORT 0x1BFF
> >>>>>>
> >>>>>> v5.4 .. 1.14
> >>>>>> #define F2FS_FEATURE_CASEFOLD 0x1000
> >>>>>> #define F2FS_FEATURE_COMPRESS 0x2000
> >>>>>> #define F2FS_FEATURE_SUPPORT 0x3BFF
> >>>>>>
> >>>>>> f2fs-tools sb->feature f2fs F2FS_FEATURE_SUPPORT
> >>>>>>
> >>>>>> [enable all features in tools]
> >>>>>> v1.12 0x0BFF v5.2 no_check -> ok
> >>>>>> v1.12 0x0BFF v5.3 0x1BFF -> ok
> >>>>>> v1.12 0x0BFF v5.4 0x3BFF -> ok
> >>>>>>
> >>>>>> v1.13 0x1BFF v5.2 that's issue we need to fix
> >>>>>> v1.13 0x1BFF v5.3 0x1BFF -> ok
> >>>>>> v1.13 0x1BFF v5.4 0x3BFF -> ok
> >>>>>>
> >>>>>> v1.14 0x3BFF v5.2 that's issue we need to fix
> >>>>>> v1.14 0x3BFF v5.3 0x1BFF -> fail
> >>>>>> v1.14 0x3BFF v5.4 0x3BFF -> ok
> >>>>>>
> >>>>>> Or am I missing something?
> >>>>>>
> >>>>>> Thanks,
> >>>>>>
> >>>>>>>
> >>>>>>>>
> >>>>>>>> Then that would be:
> >>>>>>>>
> >>>>>>>> kernel tool
> >>>>>>>> v5.2 .. 1.12
> >>>>>>>> #define F2FS_FEATURE_SUPPORT 0x0000
> >>>>>>>>
> >>>>>>>> v5.3 .. 1.13
> >>>>>>>> #define F2FS_FEATURE_CASEFOLD 0x0001
> >>>>>>>> #define F2FS_FEATURE_SUPPORT 0x0001
> >>>>>>>>
> >>>>>>>> v5.4 .. 1.14
> >>>>>>>> #define F2FS_FEATURE_CASEFOLD 0x0001
> >>>>>>>> #define F2FS_FEATURE_COMPRESS 0x0002
> >>>>>>>> #define F2FS_FEATURE_SUPPORT 0x0003
> >>>>>>>>
> >>>>>>>> f2fs-tools sb->required_features f2fs F2FS_FEATURE_SUPPORT
> >>>>>>>>
> >>>>>>>> v1.12 0x0000 v5.2 no_check -> ok
> >>>>>>>> v1.12 0x0000 v5.3 0x0001 -> ok
> >>>>>>>> v1.12 0x0000 v5.4 0x0003 -> ok
> >>>>>>>>
> >>>>>>>> v1.13 0x0001 v5.2 that's issue we need to fix
> >>>>>>>> v1.13 0x0001 v5.3 0x0001 -> ok
> >>>>>>>> v1.13 0x0001 v5.4 0x0003 -> ok
> >>>>>>>>
> >>>>>>>> v1.14 0x0003 v5.2 that's issue we need to fix
> >>>>>>>> v1.14 0x0003 v5.3 0x0001 -> fail
> >>>>>>>> v1.14 0x0003 v5.4 0x0003 -> ok
> >>>>>>>>
> >>>>>>>> And all compatible features can be added into sb->feature[_VERITY, ....].
> >>>>>>>>
> >>>>>>>> Would that okay to you?
> >>>>>>>>
> >>>>>>>> Thanks,
> >>>>>>>>
> >>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> Thanks,
> >>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>> + ~F2FS_INCOMPAT_FEATURES) {
> >>>>>>>>>>>> + f2fs_info(sbi, "Unsupported feature: %x: supported: %x",
> >>>>>>>>>>>> + le32_to_cpu(raw_super->required_features) ^
> >>>>>>>>>>>> + F2FS_INCOMPAT_FEATURES,
> >>>>>>>>>>>> + F2FS_INCOMPAT_FEATURES);
> >>>>>>>>>>>> + return -EINVAL;
> >>>>>>>>>>>> + }
> >>>>>>>>>>>> +
> >>>>>>>>>>>> /* Check checksum_offset and crc in superblock */
> >>>>>>>>>>>> if (__F2FS_HAS_FEATURE(raw_super, F2FS_FEATURE_SB_CHKSUM)) {
> >>>>>>>>>>>> crc_offset = le32_to_cpu(raw_super->checksum_offset);
> >>>>>>>>>>>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> >>>>>>>>>>>> index a2b36b2e286f..4141be3f219c 100644
> >>>>>>>>>>>> --- a/include/linux/f2fs_fs.h
> >>>>>>>>>>>> +++ b/include/linux/f2fs_fs.h
> >>>>>>>>>>>> @@ -117,7 +117,8 @@ struct f2fs_super_block {
> >>>>>>>>>>>> __u8 hot_ext_count; /* # of hot file extension */
> >>>>>>>>>>>> __le16 s_encoding; /* Filename charset encoding */
> >>>>>>>>>>>> __le16 s_encoding_flags; /* Filename charset encoding flags */
> >>>>>>>>>>>> - __u8 reserved[306]; /* valid reserved region */
> >>>>>>>>>>>> + __le32 required_features; /* incompatible features to old kernel */
> >>>>>>>>>>>> + __u8 reserved[302]; /* valid reserved region */
> >>>>>>>>>>>> __le32 crc; /* checksum of superblock */
> >>>>>>>>>>>> } __packed;
> >>>>>>>>>>>>
> >>>>>>>>>>>> --
> >>>>>>>>>>>> 2.22.0
> >>>>>>>>>>> .
> >>>>>>>>>>>
> >>>>>>>>> .
> >>>>>>>>>
> >>>>>>> .
> >>>>>>>
> >>>>> .
> >>>>>
> >>> .
> >>>
> > .
> >

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