Message-ID: <20171027105632.GA96994@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Fri, 27 Oct 2017 12:56:32 +0200
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     Chao Yu <chao@...nel.org>, 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 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).

> 		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
> 		 * 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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