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Message-ID: <8e906ddb-81d8-b63e-0c19-1ee9fc7f5cbf@huawei.com>
Date: Fri, 2 Aug 2019 15:54:00 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Jaegeuk Kim <jaegeuk@...nel.org>
CC: Chao Yu <chao@...nel.org>,
<linux-f2fs-devel@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 RESEND] f2fs: introduce sb.required_features to store
incompatible features
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@...wei.com>
>>>>>>
>>>>>> 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@...wei.com>
>>>>>> ---
>>>>>> 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:
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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