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Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to do sanity with enabled features
 in image
From:   Chao Yu <yuchao0@huawei.com>
To:     Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>
CC:     <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>
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 <3f170d86-e556-13ae-ce19-3bba3944f5fa@huawei.com>
 <192bae92-2193-570f-7b50-00334271bd2e@huawei.com>
Message-ID: <a16a0c1c-16c6-5fe8-bfc4-7cc0e0866c77@huawei.com>
Date:   Tue, 16 Jul 2019 18:02:21 +0800
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Hi Jaegeuk,

On 2019/5/9 9:15, Chao Yu wrote:
> On 2019/5/5 10:51, Chao Yu wrote:
>> On 2019/5/1 11:22, Jaegeuk Kim wrote:
>>> On 04/29, Chao Yu wrote:
>>>> On 2019-4-28 21:38, Jaegeuk Kim wrote:
>>>>> On 04/24, Chao Yu wrote:
>>>>>> This patch fixes to do sanity with enabled features in image, if
>>>>>> there are features kernel can not recognize, just fail the mount.
>>>>>
>>>>> We need to figure out per-feature-based rejection, since some of them can
>>>>> be set without layout change.

What about adding one field in superblock for compatible features in future?

sb.feature(F2FS_FEATURE_LAST, max] stores uncompatible features
sb.compatible_feature stores compatible features

If we follow above rule when adding one feature, then, we can fail the mount if
sb.feature(F2FS_FEATURE_LAST, max] is valid.

Thanks,

>>>>
>>>> So any suggestion on how to implement this?
>>>
>>> Which features do we need to disallow? When we introduce new features, they
>>
>> I guess it should be the new features.
>>
>>> didn't hurt the previous flow by checking f2fs_sb_has_###().
>>
>> Yes, but new features may use new disk layout, if old kernel handled it with old
>> disk layout, there must be problematic.
>>
>> e.g. format image with -O extra_attr, and mount it with kernel who don't
>> recognize new inode layout.
> 
> Jaegeuk,
> 
> Any thoughts?
> 
> Thanks,
> 
>>
>> Thanks,
>>
>>>
>>>>
>>>> Maybe:
>>>>
>>>> if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 14, 0))
>>>> 	check 4.14+ features
>>>> else if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 9, 0))
>>>> 	check 4.9+ features
>>>> else if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 4, 0))
>>>> 	check 4.4+ features
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>>>
>>>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>>>> ---
>>>>>>  fs/f2fs/f2fs.h  | 13 +++++++++++++
>>>>>>  fs/f2fs/super.c |  9 +++++++++
>>>>>>  2 files changed, 22 insertions(+)
>>>>>>
>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>>> index f5ffc09705eb..15b640967e12 100644
>>>>>> --- a/fs/f2fs/f2fs.h
>>>>>> +++ b/fs/f2fs/f2fs.h
>>>>>> @@ -151,6 +151,19 @@ struct f2fs_mount_info {
>>>>>>  #define F2FS_FEATURE_VERITY		0x0400	/* reserved */
>>>>>>  #define F2FS_FEATURE_SB_CHKSUM		0x0800
>>>>>>  
>>>>>> +#define F2FS_ALL_FEATURES	(F2FS_FEATURE_ENCRYPT |			\
>>>>>> +				F2FS_FEATURE_BLKZONED |			\
>>>>>> +				F2FS_FEATURE_ATOMIC_WRITE |		\
>>>>>> +				F2FS_FEATURE_EXTRA_ATTR |		\
>>>>>> +				F2FS_FEATURE_PRJQUOTA |			\
>>>>>> +				F2FS_FEATURE_INODE_CHKSUM |		\
>>>>>> +				F2FS_FEATURE_FLEXIBLE_INLINE_XATTR |	\
>>>>>> +				F2FS_FEATURE_QUOTA_INO |		\
>>>>>> +				F2FS_FEATURE_INODE_CRTIME |		\
>>>>>> +				F2FS_FEATURE_LOST_FOUND |		\
>>>>>> +				F2FS_FEATURE_VERITY |			\
>>>>>> +				F2FS_FEATURE_SB_CHKSUM)
>>>>>> +
>>>>>>  #define __F2FS_HAS_FEATURE(raw_super, mask)				\
>>>>>>  	((raw_super->feature & cpu_to_le32(mask)) != 0)
>>>>>>  #define F2FS_HAS_FEATURE(sbi, mask)	__F2FS_HAS_FEATURE(sbi->raw_super, mask)
>>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>>>>> index 4f8e9ab48b26..57f2fc6d14ba 100644
>>>>>> --- a/fs/f2fs/super.c
>>>>>> +++ b/fs/f2fs/super.c
>>>>>> @@ -2573,6 +2573,15 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
>>>>>>  		return 1;
>>>>>>  	}
>>>>>>  
>>>>>> +	/* check whether kernel supports all features */
>>>>>> +	if (le32_to_cpu(raw_super->feature) & (~F2FS_ALL_FEATURES)) {
>>>>>> +		f2fs_msg(sb, KERN_INFO,
>>>>>> +			"Unsupported feature:%u: supported:%u",
>>>>>> +			le32_to_cpu(raw_super->feature),
>>>>>> +			F2FS_ALL_FEATURES);
>>>>>> +		return 1;
>>>>>> +	}
>>>>>> +
>>>>>>  	/* check CP/SIT/NAT/SSA/MAIN_AREA area boundary */
>>>>>>  	if (sanity_check_area_boundary(sbi, bh))
>>>>>>  		return 1;
>>>>>> -- 
>>>>>> 2.18.0.rc1
>>> .
>>>
>>
>>
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> Linux-f2fs-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>> .
>>
> 
> 
> _______________________________________________
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> .
>