Re: [PATCH] f2fs: copy all valid xattr data includes the last zero

[Chao Yu <yuchao0@huawei.com>]

On 2017/3/22 16:42, Chao Yu wrote:
> On 2017/3/22 0:18, Jaegeuk Kim wrote:
>> On 03/20, Kinglong Mee wrote:
>>> On 3/20/2017 11:08, Jaegeuk Kim wrote:
>>>> Hi Kinglong,
>>>>
>>>> On 03/18, Kinglong Mee wrote:
>>>>> It's better coping all valid xattr data includes the last zero. 
>>>>
>>>> Why do we need this?
>>>>
>>>> The size of txattr_addr would be larger than the space we need.
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
>>>>> ---
>>>>>  fs/f2fs/xattr.c | 4 ++--
>>>>>  fs/f2fs/xattr.h | 4 ++--
>>>>>  2 files changed, 4 insertions(+), 4 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
>>>>> index aff7619..41785c9 100644
>>>>> --- a/fs/f2fs/xattr.c
>>>>> +++ b/fs/f2fs/xattr.c
>>>>> @@ -249,7 +249,7 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage,
>>>>>  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>>>>  	void *cur_addr, *txattr_addr, *last_addr = NULL;
>>>>>  	nid_t xnid = F2FS_I(inode)->i_xattr_nid;
>>>>> -	unsigned int size = xnid ? VALID_XATTR_BLOCK_SIZE : 0;
>>>
>>> Here maybe does not copy the last zero.
>>
>> The below kzalloc() will make it zero. Any problem?
> 
> There is no problem without this change, but anyway, IMO, it needs to do cleanup
> as it can provider better readability making allocated size and copied size be
> consistent among lookup_all_xattrs, read_all_xattrs and write_all_xattrs.
> 
> And since during allocation we have initialize memory with zero, so I prefer to
> not copy extra reserved xattr space.
> 
> Jaegeuk, Kinglong, how about changing like below:
> 
> ---
>  fs/f2fs/xattr.c | 27 ++++++++++++---------------
>  fs/f2fs/xattr.h |  3 ++-
>  2 files changed, 14 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
> index aff7619e3f96..308b06664068 100644
> --- a/fs/f2fs/xattr.c
> +++ b/fs/f2fs/xattr.c
> @@ -250,15 +250,13 @@ static int lookup_all_xattrs(struct inode *inode, struct
> page *ipage,
>  	void *cur_addr, *txattr_addr, *last_addr = NULL;
>  	nid_t xnid = F2FS_I(inode)->i_xattr_nid;
>  	unsigned int size = xnid ? VALID_XATTR_BLOCK_SIZE : 0;
> -	unsigned int inline_size = 0;
> +	unsigned int inline_size = inline_xattr_size(inode);
>  	int err = 0;
> 
> -	inline_size = inline_xattr_size(inode);
> -
>  	if (!size && !inline_size)
>  		return -ENODATA;
> 
> -	txattr_addr = kzalloc(inline_size + size + sizeof(__u32),
> +	txattr_addr = kzalloc(inline_size + size + RESERVED_XATTR_SIZE,
>  							GFP_F2FS_ZERO);
>  	if (!txattr_addr)
>  		return -ENOMEM;
> @@ -328,13 +326,14 @@ static int read_all_xattrs(struct inode *inode, struct
> page *ipage,
>  {
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>  	struct f2fs_xattr_header *header;
> -	size_t size = PAGE_SIZE, inline_size = 0;
> +	nid_t xnid = F2FS_I(inode)->i_xattr_nid;
> +	unsigned int size = xnid ? VALID_XATTR_BLOCK_SIZE : 0;

Here, always should assign size with VALID_XATTR_BLOCK_SIZE for enospc case in
inline xattr space while adding new xattr entry.

unsigned int size = VALID_XATTR_BLOCK_SIZE;

Thanks,

> +	unsigned int inline_size = inline_xattr_size(inode);
>  	void *txattr_addr;
>  	int err;
> 
> -	inline_size = inline_xattr_size(inode);
> -
> -	txattr_addr = kzalloc(inline_size + size, GFP_F2FS_ZERO);
> +	txattr_addr = kzalloc(inline_size + size + RESERVED_XATTR_SIZE,
> +							GFP_F2FS_ZERO);
>  	if (!txattr_addr)
>  		return -ENOMEM;
> 
> @@ -358,19 +357,19 @@ static int read_all_xattrs(struct inode *inode, struct
> page *ipage,
>  	}
> 
>  	/* read from xattr node block */
> -	if (F2FS_I(inode)->i_xattr_nid) {
> +	if (xnid) {
>  		struct page *xpage;
>  		void *xattr_addr;
> 
>  		/* The inode already has an extended attribute block. */
> -		xpage = get_node_page(sbi, F2FS_I(inode)->i_xattr_nid);
> +		xpage = get_node_page(sbi, xnid);
>  		if (IS_ERR(xpage)) {
>  			err = PTR_ERR(xpage);
>  			goto fail;
>  		}
> 
>  		xattr_addr = page_address(xpage);
> -		memcpy(txattr_addr + inline_size, xattr_addr, PAGE_SIZE);
> +		memcpy(txattr_addr + inline_size, xattr_addr, size);
>  		f2fs_put_page(xpage, 1);
>  	}
> 
> @@ -392,14 +391,12 @@ static inline int write_all_xattrs(struct inode *inode,
> __u32 hsize,
>  				void *txattr_addr, struct page *ipage)
>  {
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> -	size_t inline_size = 0;
> +	size_t inline_size = inline_xattr_size(inode);
>  	void *xattr_addr;
>  	struct page *xpage;
>  	nid_t new_nid = 0;
>  	int err;
> 
> -	inline_size = inline_xattr_size(inode);
> -
>  	if (hsize > inline_size && !F2FS_I(inode)->i_xattr_nid)
>  		if (!alloc_nid(sbi, &new_nid))
>  			return -ENOSPC;
> @@ -454,7 +451,7 @@ static inline int write_all_xattrs(struct inode *inode,
> __u32 hsize,
>  	}
> 
>  	xattr_addr = page_address(xpage);
> -	memcpy(xattr_addr, txattr_addr + inline_size, MAX_XATTR_BLOCK_SIZE);
> +	memcpy(xattr_addr, txattr_addr + inline_size, VALID_XATTR_BLOCK_SIZE);
>  	set_page_dirty(xpage);
>  	f2fs_put_page(xpage, 1);
> 
> diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h
> index d5a94928c116..1e7db8d0806e 100644
> --- a/fs/f2fs/xattr.h
> +++ b/fs/f2fs/xattr.h
> @@ -73,7 +73,8 @@ struct f2fs_xattr_entry {
>  				!IS_XATTR_LAST_ENTRY(entry);\
>  				entry = XATTR_NEXT_ENTRY(entry))
>  #define MAX_XATTR_BLOCK_SIZE	(PAGE_SIZE - sizeof(struct node_footer))
> -#define VALID_XATTR_BLOCK_SIZE	(MAX_XATTR_BLOCK_SIZE - sizeof(__u32))
> +#define RESERVED_XATTR_SIZE	(sizeof(__u32))
> +#define VALID_XATTR_BLOCK_SIZE	(MAX_XATTR_BLOCK_SIZE - RESERVED_XATTR_SIZE)
>  #define MIN_OFFSET(i)		XATTR_ALIGN(inline_xattr_size(i) +	\
>  						VALID_XATTR_BLOCK_SIZE)
> 


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