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

[Jaegeuk Kim]

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
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
> >>>>
> >>>> .
> >>>>