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Subject: Re: [PATCH] f2fs: fix to do sanity with enabled features in image
To:     Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>
CC:     <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>
References: <20190424094850.118323-1-yuchao0@huawei.com>
 <20190428133802.GB37346@jaegeuk-macbookpro.roam.corp.google.com>
 <373f4633-d331-5cf3-74b7-e982072bc4b4@kernel.org>
 <20190501032242.GA84420@jaegeuk-macbookpro.roam.corp.google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <3f170d86-e556-13ae-ce19-3bba3944f5fa@huawei.com>
Date:   Sun, 5 May 2019 10:51:35 +0800
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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.
>>
>> 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.

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
> .
>