Message-ID: <20170907044845.GA5617@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Wed, 6 Sep 2017 21:48:45 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH 3/3] f2fs: support flexible inline xattr size

On 09/06, Chao Yu wrote:
> Hi Jaegeuk,
> 
> Do we have time to test and stabilize this new feature before merge window?

Let's try this in the next merge window. It's too tight to test now. :)

> 
> Thanks,
> 
> On 2017/9/4 18:58, Chao Yu wrote:
> > Now, in product, more and more features based on file encryption were
> > introduced, their demand of xattr space is increasing, however, inline
> > xattr has fixed-size of 200 bytes, once inline xattr space is full, new
> > increased xattr data would occupy additional xattr block which may bring
> > us more space usage and performance regression during persisting.
> > 
> > In order to resolve above issue, it's better to expand inline xattr size
> > flexibly according to user's requirement.
> > 
> > So this patch introduces new filesystem feature 'flexible inline xattr',
> > and new mount option 'inline_xattr_size=%u', once mkfs enables the
> > feature, we can use the option to make f2fs supporting flexible inline
> > xattr size.
> > 
> > To support this feature, we add extra attribute i_inline_xattr_size in
> > inode layout, indicating that how many space inline xattr borrows from
> > block address mapping space in inode layout, by this, we can easily
> > locate and store flexible-sized inline xattr data in inode.
> > 
> > Inode disk layout:
> >   +----------------------+
> >   | .i_mode              |
> >   | ...                  |
> >   | .i_ext               |
> >   +----------------------+
> >   | .i_extra_isize       |
> >   | .i_inline_xattr_size |-----------+
> >   | ...                  |           |
> >   +----------------------+           |
> >   | .i_addr              |           |
> >   |  - block address or  |           |
> >   |  - inline data       |           |
> >   +----------------------+<---+      v
> >   |    inline xattr      |    +---inline xattr range
> >   +----------------------+<---+
> >   | .i_nid               |
> >   +----------------------+
> >   |   node_footer        |
> >   | (nid, ino, offset)   |
> >   +----------------------+
> > 
> > Signed-off-by: Chao Yu <yuchao0@...wei.com>
> > ---
> >  fs/f2fs/f2fs.h          | 43 ++++++++++++++++++++++++++++++-------------
> >  fs/f2fs/inode.c         | 12 ++++++++++++
> >  fs/f2fs/namei.c         |  6 ++++++
> >  fs/f2fs/node.c          |  4 ++--
> >  fs/f2fs/super.c         | 32 +++++++++++++++++++++++++++++++-
> >  fs/f2fs/sysfs.c         |  7 +++++++
> >  fs/f2fs/xattr.c         | 18 +++++++++---------
> >  include/linux/f2fs_fs.h |  5 +++--
> >  8 files changed, 100 insertions(+), 27 deletions(-)
> > 
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 1f24ad4ca1bb..168ad51b7fb9 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -93,6 +93,7 @@ extern char *fault_name[FAULT_MAX];
> >  #define F2FS_MOUNT_GRPQUOTA		0x00100000
> >  #define F2FS_MOUNT_PRJQUOTA		0x00200000
> >  #define F2FS_MOUNT_QUOTA		0x00400000
> > +#define F2FS_MOUNT_INLINE_XATTR_SIZE	0x00800000
> >  
> >  #define clear_opt(sbi, option)	((sbi)->mount_opt.opt &= ~F2FS_MOUNT_##option)
> >  #define set_opt(sbi, option)	((sbi)->mount_opt.opt |= F2FS_MOUNT_##option)
> > @@ -118,6 +119,7 @@ struct f2fs_mount_info {
> >  #define F2FS_FEATURE_EXTRA_ATTR		0x0008
> >  #define F2FS_FEATURE_PRJQUOTA		0x0010
> >  #define F2FS_FEATURE_INODE_CHKSUM	0x0020
> > +#define F2FS_FEATURE_FLEXIBLE_INLINE_XATTR	0x0040
> >  
> >  #define F2FS_HAS_FEATURE(sb, mask)					\
> >  	((F2FS_SB(sb)->raw_super->feature & cpu_to_le32(mask)) != 0)
> > @@ -379,11 +381,14 @@ struct f2fs_flush_device {
> >  
> >  /* for inline stuff */
> >  #define DEF_INLINE_RESERVED_SIZE	1
> > +#define DEF_MIN_INLINE_SIZE		1
> >  static inline int get_extra_isize(struct inode *inode);
> > -#define MAX_INLINE_DATA(inode)	(sizeof(__le32) * \
> > -				(CUR_ADDRS_PER_INODE(inode) - \
> > -				DEF_INLINE_RESERVED_SIZE - \
> > -				F2FS_INLINE_XATTR_ADDRS))
> > +static inline int get_inline_xattr_addrs(struct inode *inode);
> > +#define F2FS_INLINE_XATTR_ADDRS(inode)	get_inline_xattr_addrs(inode)
> > +#define MAX_INLINE_DATA(inode)	(sizeof(__le32) *			\
> > +				(CUR_ADDRS_PER_INODE(inode) -		\
> > +				F2FS_INLINE_XATTR_ADDRS(inode) -	\
> > +				DEF_INLINE_RESERVED_SIZE))
> >  
> >  /* for inline dir */
> >  #define NR_INLINE_DENTRY(inode)	(MAX_INLINE_DATA(inode) * BITS_PER_BYTE / \
> > @@ -592,6 +597,7 @@ struct f2fs_inode_info {
> >  
> >  	int i_extra_isize;		/* size of extra space located in i_addr */
> >  	kprojid_t i_projid;		/* id for project quota */
> > +	int i_inline_xattr_size;	/* inline xattr size */
> >  };
> >  
> >  static inline void get_extent_info(struct extent_info *ext,
> > @@ -1043,6 +1049,7 @@ struct f2fs_sb_info {
> >  	loff_t max_file_blocks;			/* max block index of file */
> >  	int active_logs;			/* # of active logs */
> >  	int dir_level;				/* directory level */
> > +	int inline_xattr_size;			/* inline xattr size */
> >  
> >  	block_t user_block_count;		/* # of user blocks */
> >  	block_t total_valid_block_count;	/* # of valid blocks */
> > @@ -2167,25 +2174,20 @@ static inline int f2fs_has_inline_xattr(struct inode *inode)
> >  
> >  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);
> > +	return CUR_ADDRS_PER_INODE(inode) - F2FS_INLINE_XATTR_ADDRS(inode);
> >  }
> >  
> > -static inline void *inline_xattr_addr(struct page *page)
> > +static inline void *inline_xattr_addr(struct inode *inode, struct page *page)
> >  {
> >  	struct f2fs_inode *ri = F2FS_INODE(page);
> >  
> >  	return (void *)&(ri->i_addr[DEF_ADDRS_PER_INODE -
> > -					F2FS_INLINE_XATTR_ADDRS]);
> > +					F2FS_INLINE_XATTR_ADDRS(inode)]);
> >  }
> >  
> >  static inline int inline_xattr_size(struct inode *inode)
> >  {
> > -	if (f2fs_has_inline_xattr(inode))
> > -		return F2FS_INLINE_XATTR_ADDRS << 2;
> > -	else
> > -		return 0;
> > +	return get_inline_xattr_addrs(inode) * sizeof(__le32);
> >  }
> >  
> >  static inline int f2fs_has_inline_data(struct inode *inode)
> > @@ -2329,6 +2331,16 @@ static inline int get_extra_isize(struct inode *inode)
> >  	return F2FS_I(inode)->i_extra_isize / sizeof(__le32);
> >  }
> >  
> > +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;
> > +}
> > +
> >  #define get_inode_mode(i) \
> >  	((is_inode_flag_set(i, FI_ACL_MODE)) ? \
> >  	 (F2FS_I(i)->i_acl_mode) : ((i)->i_mode))
> > @@ -2984,6 +2996,11 @@ static inline int f2fs_sb_has_inode_chksum(struct super_block *sb)
> >  	return F2FS_HAS_FEATURE(sb, F2FS_FEATURE_INODE_CHKSUM);
> >  }
> >  
> > +static inline int f2fs_sb_has_flexible_inline_xattr(struct super_block *sb)
> > +{
> > +	return F2FS_HAS_FEATURE(sb, F2FS_FEATURE_FLEXIBLE_INLINE_XATTR);
> > +}
> > +
> >  #ifdef CONFIG_BLK_DEV_ZONED
> >  static inline int get_blkz_type(struct f2fs_sb_info *sbi,
> >  			struct block_device *bdev, block_t blkaddr)
> > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> > index c33b05aec1a1..c3e60fa60957 100644
> > --- a/fs/f2fs/inode.c
> > +++ b/fs/f2fs/inode.c
> > @@ -232,6 +232,13 @@ 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))
> > +		fi->i_inline_xattr_size = le16_to_cpu(ri->i_inline_xattr_size);
> > +	else
> > +		fi->i_inline_xattr_size = DEFAULT_INLINE_XATTR_ADDRS;
> > +
> >  	/* check data exist */
> >  	if (f2fs_has_inline_data(inode) && !f2fs_exist_data(inode))
> >  		__recover_inline_status(inode, node_page);
> > @@ -384,6 +391,11 @@ int update_inode(struct inode *inode, struct page *node_page)
> >  	if (f2fs_has_extra_attr(inode)) {
> >  		ri->i_extra_isize = cpu_to_le16(F2FS_I(inode)->i_extra_isize);
> >  
> > +		if (f2fs_sb_has_flexible_inline_xattr(F2FS_I_SB(inode)->sb) &&
> > +			f2fs_has_inline_xattr(inode))
> > +			ri->i_inline_xattr_size =
> > +				cpu_to_le16(F2FS_I(inode)->i_inline_xattr_size);
> > +
> >  		if (f2fs_sb_has_project_quota(F2FS_I_SB(inode)->sb) &&
> >  			F2FS_FITS_IN_INODE(ri, F2FS_I(inode)->i_extra_isize,
> >  								i_projid)) {
> > diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> > index a4dab98c4b7b..b6455b7ca00f 100644
> > --- a/fs/f2fs/namei.c
> > +++ b/fs/f2fs/namei.c
> > @@ -86,6 +86,12 @@ static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
> >  
> >  	if (test_opt(sbi, INLINE_XATTR))
> >  		set_inode_flag(inode, FI_INLINE_XATTR);
> > +
> > +	if (f2fs_sb_has_extra_attr(sbi->sb) &&
> > +		f2fs_sb_has_flexible_inline_xattr(sbi->sb) &&
> > +		f2fs_has_inline_xattr(inode))
> > +		F2FS_I(inode)->i_inline_xattr_size = sbi->inline_xattr_size;
> > +
> >  	if (test_opt(sbi, INLINE_DATA) && f2fs_may_inline_data(inode))
> >  		set_inode_flag(inode, FI_INLINE_DATA);
> >  	if (f2fs_may_inline_dentry(inode))
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index fca87835a1da..a19f3302c967 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -2193,8 +2193,8 @@ void recover_inline_xattr(struct inode *inode, struct page *page)
> >  		goto update_inode;
> >  	}
> >  
> > -	dst_addr = inline_xattr_addr(ipage);
> > -	src_addr = inline_xattr_addr(page);
> > +	dst_addr = inline_xattr_addr(inode, ipage);
> > +	src_addr = inline_xattr_addr(inode, page);
> >  	inline_size = inline_xattr_size(inode);
> >  
> >  	f2fs_wait_on_page_writeback(ipage, NODE, true);
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index a8ff16c50b4c..3298bb3bf417 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -92,6 +92,7 @@ enum {
> >  	Opt_disable_ext_identify,
> >  	Opt_inline_xattr,
> >  	Opt_noinline_xattr,
> > +	Opt_inline_xattr_size,
> >  	Opt_inline_data,
> >  	Opt_inline_dentry,
> >  	Opt_noinline_dentry,
> > @@ -141,6 +142,7 @@ static match_table_t f2fs_tokens = {
> >  	{Opt_disable_ext_identify, "disable_ext_identify"},
> >  	{Opt_inline_xattr, "inline_xattr"},
> >  	{Opt_noinline_xattr, "noinline_xattr"},
> > +	{Opt_inline_xattr_size, "inline_xattr_size=%u"},
> >  	{Opt_inline_data, "inline_data"},
> >  	{Opt_inline_dentry, "inline_dentry"},
> >  	{Opt_noinline_dentry, "noinline_dentry"},
> > @@ -383,6 +385,12 @@ static int parse_options(struct super_block *sb, char *options)
> >  		case Opt_noinline_xattr:
> >  			clear_opt(sbi, INLINE_XATTR);
> >  			break;
> > +		case Opt_inline_xattr_size:
> > +			if (args->from && match_int(args, &arg))
> > +				return -EINVAL;
> > +			set_opt(sbi, INLINE_XATTR_SIZE);
> > +			sbi->inline_xattr_size = arg;
> > +			break;
> >  #else
> >  		case Opt_user_xattr:
> >  			f2fs_msg(sb, KERN_INFO,
> > @@ -604,6 +612,24 @@ static int parse_options(struct super_block *sb, char *options)
> >  				F2FS_IO_SIZE_KB(sbi));
> >  		return -EINVAL;
> >  	}
> > +
> > +	if (test_opt(sbi, INLINE_XATTR_SIZE)) {
> > +		if (!test_opt(sbi, INLINE_XATTR)) {
> > +			f2fs_msg(sb, KERN_ERR,
> > +					"inline_xattr_size option should be "
> > +					"set with inline_xattr option");
> > +			return -EINVAL;
> > +		}
> > +		if (!sbi->inline_xattr_size ||
> > +			sbi->inline_xattr_size >= DEF_ADDRS_PER_INODE -
> > +					F2FS_TOTAL_EXTRA_ATTR_SIZE -
> > +					DEF_INLINE_RESERVED_SIZE -
> > +					DEF_MIN_INLINE_SIZE) {
> > +			f2fs_msg(sb, KERN_ERR,
> > +					"inline xattr size is out of range");
> > +			return -EINVAL;
> > +		}
> > +	}
> >  	return 0;
> >  }
> >  
> > @@ -1045,6 +1071,9 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> >  		seq_puts(seq, ",inline_xattr");
> >  	else
> >  		seq_puts(seq, ",noinline_xattr");
> > +	if (test_opt(sbi, INLINE_XATTR_SIZE))
> > +		seq_printf(seq, ",inline_xattr_size=%u",
> > +					sbi->inline_xattr_size);
> >  #endif
> >  #ifdef CONFIG_F2FS_FS_POSIX_ACL
> >  	if (test_opt(sbi, POSIX_ACL))
> > @@ -1107,6 +1136,7 @@ static void default_options(struct f2fs_sb_info *sbi)
> >  {
> >  	/* init some FS parameters */
> >  	sbi->active_logs = NR_CURSEG_TYPE;
> > +	sbi->inline_xattr_size = DEFAULT_INLINE_XATTR_ADDRS;
> >  
> >  	set_opt(sbi, BG_GC);
> >  	set_opt(sbi, INLINE_XATTR);
> > @@ -1655,7 +1685,7 @@ static loff_t max_file_blocks(void)
> >  
> >  	/*
> >  	 * note: previously, result is equal to (DEF_ADDRS_PER_INODE -
> > -	 * F2FS_INLINE_XATTR_ADDRS), but now f2fs try to reserve more
> > +	 * DEFAULT_INLINE_XATTR_ADDRS), but now f2fs try to reserve more
> >  	 * space in inode.i_addr, it will be more safe to reassign
> >  	 * result as zero.
> >  	 */
> > diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> > index daa48257cc94..595b69862b0e 100644
> > --- a/fs/f2fs/sysfs.c
> > +++ b/fs/f2fs/sysfs.c
> > @@ -100,6 +100,9 @@ static ssize_t features_show(struct f2fs_attr *a,
> >  	if (f2fs_sb_has_inode_chksum(sb))
> >  		len += snprintf(buf + len, PAGE_SIZE - len, "%s%s",
> >  				len ? ", " : "", "inode_checksum");
> > +	if (f2fs_sb_has_flexible_inline_xattr(sb))
> > +		len += snprintf(buf + len, PAGE_SIZE - len, "%s%s",
> > +				len ? ", " : "", "flexible_inline_xattr");
> >  	len += snprintf(buf + len, PAGE_SIZE - len, "\n");
> >  	return len;
> >  }
> > @@ -232,6 +235,7 @@ enum feat_id {
> >  	FEAT_EXTRA_ATTR,
> >  	FEAT_PROJECT_QUOTA,
> >  	FEAT_INODE_CHECKSUM,
> > +	FEAT_FLEXIBLE_INLINE_XATTR,
> >  };
> >  
> >  static ssize_t f2fs_feature_show(struct f2fs_attr *a,
> > @@ -244,6 +248,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
> >  	case FEAT_EXTRA_ATTR:
> >  	case FEAT_PROJECT_QUOTA:
> >  	case FEAT_INODE_CHECKSUM:
> > +	case FEAT_FLEXIBLE_INLINE_XATTR:
> >  		return snprintf(buf, PAGE_SIZE, "supported\n");
> >  	}
> >  	return 0;
> > @@ -314,6 +319,7 @@ F2FS_FEATURE_RO_ATTR(atomic_write, FEAT_ATOMIC_WRITE);
> >  F2FS_FEATURE_RO_ATTR(extra_attr, FEAT_EXTRA_ATTR);
> >  F2FS_FEATURE_RO_ATTR(project_quota, FEAT_PROJECT_QUOTA);
> >  F2FS_FEATURE_RO_ATTR(inode_checksum, FEAT_INODE_CHECKSUM);
> > +F2FS_FEATURE_RO_ATTR(flexible_inline_xattr, FEAT_FLEXIBLE_INLINE_XATTR);
> >  
> >  #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
> >  static struct attribute *f2fs_attrs[] = {
> > @@ -360,6 +366,7 @@ static struct attribute *f2fs_feat_attrs[] = {
> >  	ATTR_LIST(extra_attr),
> >  	ATTR_LIST(project_quota),
> >  	ATTR_LIST(inode_checksum),
> > +	ATTR_LIST(flexible_inline_xattr),
> >  	NULL,
> >  };
> >  
> > diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
> > index 4829f1b38478..252adbb7126a 100644
> > --- a/fs/f2fs/xattr.c
> > +++ b/fs/f2fs/xattr.c
> > @@ -217,12 +217,12 @@ static struct f2fs_xattr_entry *__find_xattr(void *base_addr, int index,
> >  	return entry;
> >  }
> >  
> > -static struct f2fs_xattr_entry *__find_inline_xattr(void *base_addr,
> > -					void **last_addr, int index,
> > -					size_t len, const char *name)
> > +static struct f2fs_xattr_entry *__find_inline_xattr(struct inode *inode,
> > +				void *base_addr, void **last_addr, int index,
> > +				size_t len, const char *name)
> >  {
> >  	struct f2fs_xattr_entry *entry;
> > -	unsigned int inline_size = F2FS_INLINE_XATTR_ADDRS << 2;
> > +	unsigned int inline_size = inline_xattr_size(inode);
> >  
> >  	list_for_each_xattr(entry, base_addr) {
> >  		if ((void *)entry + sizeof(__u32) > base_addr + inline_size ||
> > @@ -250,13 +250,13 @@ static int read_inline_xattr(struct inode *inode, struct page *ipage,
> >  	void *inline_addr;
> >  
> >  	if (ipage) {
> > -		inline_addr = inline_xattr_addr(ipage);
> > +		inline_addr = inline_xattr_addr(inode, ipage);
> >  	} else {
> >  		page = get_node_page(sbi, inode->i_ino);
> >  		if (IS_ERR(page))
> >  			return PTR_ERR(page);
> >  
> > -		inline_addr = inline_xattr_addr(page);
> > +		inline_addr = inline_xattr_addr(inode, page);
> >  	}
> >  	memcpy(txattr_addr, inline_addr, inline_size);
> >  	f2fs_put_page(page, 1);
> > @@ -309,7 +309,7 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage,
> >  		if (err)
> >  			goto out;
> >  
> > -		*xe = __find_inline_xattr(txattr_addr, &last_addr,
> > +		*xe = __find_inline_xattr(inode, txattr_addr, &last_addr,
> >  						index, len, name);
> >  		if (*xe)
> >  			goto check;
> > @@ -404,7 +404,7 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize,
> >  		void *inline_addr;
> >  
> >  		if (ipage) {
> > -			inline_addr = inline_xattr_addr(ipage);
> > +			inline_addr = inline_xattr_addr(inode, ipage);
> >  			f2fs_wait_on_page_writeback(ipage, NODE, true);
> >  			set_page_dirty(ipage);
> >  		} else {
> > @@ -413,7 +413,7 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize,
> >  				alloc_nid_failed(sbi, new_nid);
> >  				return PTR_ERR(page);
> >  			}
> > -			inline_addr = inline_xattr_addr(page);
> > +			inline_addr = inline_xattr_addr(inode, page);
> >  			f2fs_wait_on_page_writeback(page, NODE, true);
> >  		}
> >  		memcpy(inline_addr, txattr_addr, inline_size);
> > diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> > index 2a0c453d7235..50a8ee501bf1 100644
> > --- a/include/linux/f2fs_fs.h
> > +++ b/include/linux/f2fs_fs.h
> > @@ -184,7 +184,8 @@ struct f2fs_extent {
> >  } __packed;
> >  
> >  #define F2FS_NAME_LEN		255
> > -#define F2FS_INLINE_XATTR_ADDRS	50	/* 200 bytes for inline xattrs */
> > +/* 200 bytes for inline xattrs by default */
> > +#define DEFAULT_INLINE_XATTR_ADDRS	50
> >  #define DEF_ADDRS_PER_INODE	923	/* Address Pointers in an Inode */
> >  #define CUR_ADDRS_PER_INODE(inode)	(DEF_ADDRS_PER_INODE - \
> >  					get_extra_isize(inode))
> > @@ -238,7 +239,7 @@ struct f2fs_inode {
> >  	union {
> >  		struct {
> >  			__le16 i_extra_isize;	/* extra inode attribute size */
> > -			__le16 i_padding;	/* padding */
> > +			__le16 i_inline_xattr_size;	/* inline xattr size, unit: 4 bytes */
> >  			__le32 i_projid;	/* project id */
> >  			__le32 i_inode_checksum;/* inode meta checksum */
> >  			__le32 i_extra_end[0];	/* for attribute size calculation */
> > 

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