Date:   Fri, 27 Oct 2017 19:39:05 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     Chao Yu <yuchao0@...wei.com>,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: fix to keep backward compatibility of flexible
 inline xattr feature

On 2017/10/27 19:32, Jaegeuk Kim wrote:
> On 10/27, Chao Yu wrote:
>> On 2017/10/27 18:56, Jaegeuk Kim wrote:
>>> On 10/27, Chao Yu wrote:
>>>> On 2017/10/26 22:05, Jaegeuk Kim wrote:
>>>>> On 10/26, Chao Yu wrote:
>>>>>> 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. This makes much clear to me. It seems we need to handle directory only.
>>>>> Could you please check the dev-test branches in f2fs and f2fs-tools?
>>>>
>>>> This is a little complicated, as for non-inline_{data,dentry} inode, we will get
>>>> addrs number in inode by:
>>>>
>>>> static inline unsigned int addrs_per_inode(struct inode *inode)
>>>> {
>>>> 	if (f2fs_has_inline_xattr(inode))
>>>> 		return CUR_ADDRS_PER_INODE(inode) - F2FS_INLINE_XATTR_ADDRS;
>>>> 	return CUR_ADDRS_PER_INODE(inode);
>>>> }
>>>>
>>>> It only cares about this inode is inline_xattr or not, so, if we reserve 200
>>>> bytes for dir inode, it will cause incompatibility.
>>>>
>>>> So we need add this logic into i_inline_xattr_size calculation? Such as:
>>>>
>>>> a. new_inode:
>>>>
>>>> 	if (f2fs_sb_has_flexible_inline_xattr(sbi->sb)) {
>>>> 		f2fs_bug_on(sbi, !f2fs_has_extra_attr(inode));
>>>> 		if (f2fs_has_inline_xattr)
>>>> 			xattr_size = sbi->inline_xattr_size;
>>>> 	} else if (f2fs_has_inline_xattr(inode) ||
>>>> 			(f2fs_has_inline_dentry(inode) && S_ISDIR(inode->i_mode))) {
>>>
>>> We don't need to check both of them. It'd be enough to check
>>> f2fs_has_inline_dentry(inode).
>>
>> Agreed.
>>
>>>
>>>> 		xattr = DEFAULT_INLINE_XATTR_ADDRS
>>>> 	}
>>>> 	F2FS_I(inode)->i_inline_xattr_size = xattr_size;
>>>>
>>>> b. do_read_inode
>>>>
>>>> 	if (f2fs_sb_has_flexible_inline_xattr(sbi->sb)) {
>>>> 		f2fs_bug_on(sbi, !f2fs_has_extra_attr(inode));
>>>> 		fi->i_inline_xattr_size = le16_to_cpu(ri->i_inline_xattr_size);
>>>> 	} else if (f2fs_has_inline_xattr(inode) ||
>>>> 			(f2fs_has_inline_dentry(inode) && S_ISDIR(inode->i_mode)) {
>>>
>>> Ditto.
>>>
>>> I merged the change in dev-test, so could you check that out again? ;)
>>>
>>> Thanks,
>>>
>>>> 		fi->i_inline_xattr_size = DEFAULT_INLINE_XATTR_ADDRS;
>>>> 	} else {
>>>> 		/*
>>>> 		 * Previous inline_data always reserved 200 bytes, even if
>>>> 		 * inline_xattr is disabled. But only inline_data is safe
>>
>> Minor thing, how about:
>>
>> 	/*
>> 	 * Previous inline data or directory always reserved 200 bytes in
>> 	 * inode layout, even if inline_xattr is disabled, in order to
>> 	 * stablize inline dentry's structure for backward compatibility,
>> 	 * we only get back reserved space for inline data.
>> 	 */
> 
> I slightly changed yours and uploaded. ;)

Have checked, thanks. ;)

Thanks,

> 
> Thanks,
> 
>>
>> Otherwise code in dev-test looks good to me. ;)
>>
>> Thanks,
>>
>>>> 		 * to get back the space.
>>>> 		 */
>>>> 		fi->i_inline_xattr_size = 0;
>>>> 	}
>>>>
>>>> How about this? IMO, it's better to keep codes similar in between new_inode
>>>> and do_read_inode. :)
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>>>
>>>>>> 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@...wei.com>
>>>>>>>>>>>>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>>>>>>>>>>>>> ---
>>>>>>>>>>>>>  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
>>>>>>>>>>>>
>>>>>>>>>>>> .
>>>>>>>>>>>>
>>>>>
>>>>> .
>>>>>

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