Re: [PATCH] f2fs: fix to keep backward compatibility of flexible inline xattr feature

[Chao Yu]

On 2017/10/26 19:52, Jaegeuk Kim wrote:
> On 10/26, Chao Yu wrote:
>> Hi Jaegeuk,
>>
>> On 2017/10/26 18:02, Jaegeuk Kim wrote:
>>> Hi Chao,
>>>
>>> On 10/26, Jaegeuk Kim wrote:
>>>> On 10/26, Chao Yu wrote:
>>>>> Hi Jaegeuk,
>>>>>
>>>>> On 2017/10/26 16:42, Jaegeuk Kim wrote:
>>>>>> Hi Chao,
>>>>>>
>>>>>> It seems this is a critical problem, so let me integrate this patch with your
>>>>>> initial patch "f2fs: support flexible inline xattr size".
>>>>>> Let me know, if you have any other concern.
>>>>>
>>>>> Better. ;)
>>>>>
>>>>> Please add commit message of this patch into initial patch "f2fs: support
>>>>> flexible inline xattr size".
>>>
>>> BTW, I read the patch again, and couldn't catch the problem actually.
>>> We didn't assign inline_xattr all the time, instead do if inline_xattr
>>
>> But you can see, MAX_INLINE_DATA is calculated as below, in where we will always
>> reserve F2FS_INLINE_XATTR_ADDRS of 200 bytes, now we will change
>> F2FS_INLINE_XATTR_ADDRS to F2FS_INLINE_XATTR_ADDRS(inode) which is an flexible
>> size, so MAX_INLINE_DATA could be calculated to expand 200 bytes than before,
> 
> That doesn't mean inline_addr is starting after 200 bytes. We're getting the
> address only if inline_xattr is set, no? The below size seems reserving the

This isn't about inline_xattr_addr, it is about MAX_INLINE_DATA size calculation.

For example, in old image, inode is with inline_{data,dentry} flag, but without
inline_xattr flag, it will only use 3688 - 200 bytes for storing inline data/dents,
which means, it reserves 200 bytes.

If we update kernel, get_inline_xattr_addrs will return 0 if inline_xattr flag is not
set, so MAX_INLINE_DATA will be 3688, then inline_dentry page layout will change.

Thanks,

> last 200 bytes which we just didn't use fully before.
> 
> Thanks,
> 
>>
>> It is okay for regular or symlink inode generated in old kernel to enlarge
>> MAX_INLINE_DATA in new kernel, as reserved 200 bytes in inode are zero all the
>> time, for directory, it will be problematic because our layout of inline
>> dentry page is fixed and calculated according to MAX_INLINE_DATA, so if
>> MAX_INLINE_DATA is enlarged, fields offset in dentry structure will relocate,
>> result in incompatibility.
>>
>> #define MAX_INLINE_DATA(inode)	(sizeof(__le32) * \
>> 				(CUR_ADDRS_PER_INODE(inode) - \
>> 				DEF_INLINE_RESERVED_SIZE - \
>> 				F2FS_INLINE_XATTR_ADDRS))
>>
>>> is set. Have you done some tests with this? I'm failing tests with these
>>> changes.
>>
>> Oh, sorry, I just tested with this patch without the modification of f2fs-tools,
>> fstest didn't report any errors so far.
>>
>> Thanks,
>>
>>>
>>>>>
>>>>> And please fix related issue in f2fs-tools with below diff code:
>>>>
>>>> Okay, merged.
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> ---
>>>>>  include/f2fs_fs.h | 9 ++++++---
>>>>>  1 file changed, 6 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
>>>>> index 2db7495804fd..a0e15ba85d97 100644
>>>>> --- a/include/f2fs_fs.h
>>>>> +++ b/include/f2fs_fs.h
>>>>> @@ -1047,11 +1047,14 @@ static inline int __get_extra_isize(struct f2fs_inode *inode)
>>>>>  extern struct f2fs_configuration c;
>>>>>  static inline int get_inline_xattr_addrs(struct f2fs_inode *inode)
>>>>>  {
>>>>> -	if (!(inode->i_inline & F2FS_INLINE_XATTR))
>>>>> +	if ((c.feature & cpu_to_le32(F2FS_FEATURE_EXTRA_ATTR)) &&
>>>>> +		(c.feature & cpu_to_le32(F2FS_FEATURE_FLEXIBLE_INLINE_XATTR)))
>>>>> +		return le16_to_cpu(inode->i_inline_xattr_size);
>>>>> +	else if (!(inode->i_inline & F2FS_INLINE_XATTR) &&
>>>>> +		(S_ISREG(inode->i_mode) || S_ISLNK(inode->i_mode)))
>>>>>  		return 0;
>>>>> -	if (!(c.feature & cpu_to_le32(F2FS_FEATURE_FLEXIBLE_INLINE_XATTR)))
>>>>> +	else
>>>>>  		return DEFAULT_INLINE_XATTR_ADDRS;
>>>>> -	return le16_to_cpu(inode->i_inline_xattr_size);
>>>>>  }
>>>>>
>>>>>  #define get_extra_isize(node)	__get_extra_isize(&node->i)
>>>>> -- 
>>>>>
>>>>> Thanks,
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> On 10/25, Chao Yu wrote:
>>>>>>> Previously, in inode layout, we will always reserve 200 bytes for inline
>>>>>>> xattr space no matter the inode enables inline xattr feature or not, due
>>>>>>> to this reason, max inline size of inode is fixed, but now, if inline
>>>>>>> xattr is not enabled, max inline size of inode will be enlarged by 200
>>>>>>> bytes, for regular and symlink inode, it will be safe to reuse resevered
>>>>>>> space as they are all zero, but for directory, we need to keep the
>>>>>>> reservation for stablizing directory structure.
>>>>>>>
>>>>>>> Reported-by: Sheng Yong <shengyong1@xxxxxxxxxx>
>>>>>>> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
>>>>>>> ---
>>>>>>>  fs/f2fs/f2fs.h  |  5 +----
>>>>>>>  fs/f2fs/inode.c | 15 ++++++++++++---
>>>>>>>  fs/f2fs/namei.c |  2 ++
>>>>>>>  3 files changed, 15 insertions(+), 7 deletions(-)
>>>>>>>
>>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>>>> index 2af1d31ae74b..7ddd0d085e3b 100644
>>>>>>> --- a/fs/f2fs/f2fs.h
>>>>>>> +++ b/fs/f2fs/f2fs.h
>>>>>>> @@ -2393,10 +2393,7 @@ static inline int get_extra_isize(struct inode *inode)
>>>>>>>  static inline int f2fs_sb_has_flexible_inline_xattr(struct super_block *sb);
>>>>>>>  static inline int get_inline_xattr_addrs(struct inode *inode)
>>>>>>>  {
>>>>>>> -	if (!f2fs_has_inline_xattr(inode))
>>>>>>> -		return 0;
>>>>>>> -	if (!f2fs_sb_has_flexible_inline_xattr(F2FS_I_SB(inode)->sb))
>>>>>>> -		return DEFAULT_INLINE_XATTR_ADDRS;
>>>>>>> +
>>>>>>>  	return F2FS_I(inode)->i_inline_xattr_size;
>>>>>>>  }
>>>>>>>  
>>>>>>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
>>>>>>> index bb876737e653..7f31b22c9efa 100644
>>>>>>> --- a/fs/f2fs/inode.c
>>>>>>> +++ b/fs/f2fs/inode.c
>>>>>>> @@ -232,10 +232,19 @@ static int do_read_inode(struct inode *inode)
>>>>>>>  	fi->i_extra_isize = f2fs_has_extra_attr(inode) ?
>>>>>>>  					le16_to_cpu(ri->i_extra_isize) : 0;
>>>>>>>  
>>>>>>> -	if (!f2fs_has_inline_xattr(inode))
>>>>>>> -		fi->i_inline_xattr_size = 0;
>>>>>>> -	else if (f2fs_sb_has_flexible_inline_xattr(sbi->sb))
>>>>>>> +	/*
>>>>>>> +	 * Previously, we will always reserve DEFAULT_INLINE_XATTR_ADDRS size
>>>>>>> +	 * space for inline xattr datas, if inline xattr is not enabled, we
>>>>>>> +	 * can expect all zero in reserved area, so for regular or symlink,
>>>>>>> +	 * it will be safe to reuse reserved area, but for directory, we
>>>>>>> +	 * should keep the reservation for stablizing directory structure.
>>>>>>> +	 */
>>>>>>> +	if (f2fs_has_extra_attr(inode) &&
>>>>>>> +		f2fs_sb_has_flexible_inline_xattr(sbi->sb))
>>>>>>>  		fi->i_inline_xattr_size = le16_to_cpu(ri->i_inline_xattr_size);
>>>>>>> +	else if (!f2fs_has_inline_xattr(inode) &&
>>>>>>> +		(S_ISREG(inode->i_mode) || S_ISLNK(inode->i_mode)))
>>>>>>> +		fi->i_inline_xattr_size = 0;
>>>>>>>  	else
>>>>>>>  		fi->i_inline_xattr_size = DEFAULT_INLINE_XATTR_ADDRS;
>>>>>>>  
>>>>>>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>>>>>>> index e6f86d5d97b9..a1c56a14c191 100644
>>>>>>> --- a/fs/f2fs/namei.c
>>>>>>> +++ b/fs/f2fs/namei.c
>>>>>>> @@ -91,6 +91,8 @@ static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
>>>>>>>  		f2fs_sb_has_flexible_inline_xattr(sbi->sb) &&
>>>>>>>  		f2fs_has_inline_xattr(inode))
>>>>>>>  		F2FS_I(inode)->i_inline_xattr_size = sbi->inline_xattr_size;
>>>>>>> +	else
>>>>>>> +		F2FS_I(inode)->i_inline_xattr_size = 0;
>>>>>>>  
>>>>>>>  	if (test_opt(sbi, INLINE_DATA) && f2fs_may_inline_data(inode))
>>>>>>>  		set_inode_flag(inode, FI_INLINE_DATA);
>>>>>>> -- 
>>>>>>> 2.13.1.388.g69e6b9b4f4a9
>>>>>>
>>>>>> .
>>>>>>