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Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to do sanity with enabled features
 in image
To:     Jaegeuk Kim <jaegeuk@kernel.org>
CC:     Chao Yu <chao@kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>
References: <20190424094850.118323-1-yuchao0@huawei.com>
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 <373f4633-d331-5cf3-74b7-e982072bc4b4@kernel.org>
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 <3f170d86-e556-13ae-ce19-3bba3944f5fa@huawei.com>
 <192bae92-2193-570f-7b50-00334271bd2e@huawei.com>
 <a16a0c1c-16c6-5fe8-bfc4-7cc0e0866c77@huawei.com>
 <20190723013546.GA60778@jaegeuk-macbookpro.roam.corp.google.com>
 <00726135-f210-7791-a372-ef9cb1ae209f@huawei.com>
 <20190729054706.GB94090@jaegeuk-macbookpro.roam.corp.google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <bed4eb2f-2261-5f88-1359-b00881a174da@huawei.com>
Date:   Mon, 29 Jul 2019 15:09:29 +0800
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On 2019/7/29 13:47, Jaegeuk Kim wrote:
> On 07/23, Chao Yu wrote:
>> On 2019/7/23 9:35, Jaegeuk Kim wrote:
>>> On 07/16, Chao Yu wrote:
>>>> 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.
>>>
>>> How about adding required_features flag in sb to check part of features only?
>>
>> You mean all incompatible features can be add into sb.required_features later
>> like this?
>>
>> __le32 required_features;	/* incompatible feature to old kernel */
>>
>> And we can check required_features with supported features in current kernel?
> 
> Yeah, I think so.

Copied, let me update the patch.

Thanks,

> 
>>
>> if (le32_to_cpu(raw_super->required_features) &
>> 	(~NOW_SUPPORTED_FEATURES_IN_CURRENT_KERNEL)) {
>> 	print msg & ret error;
>> }
>>
>> Thanks,
>>
>>>
>>>>
>>>> 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
>>>>>> .
>>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Linux-f2fs-devel mailing list
>>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>>>>> .
>>>>>
>>> .
>>>
> .
>