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SubjectRe: [f2fs-dev 4/5] f2fs: Key functions to handle inline data
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On Mon, Oct 28, 2013 at 8:43 PM, Jaegeuk Kim <jaegeuk.kim@samsung.com> wrote:
> Hi,
>
> 2013-10-26 (토), 00:01 +0800, Huajun Li:
>> From: Huajun Li <huajun.li@intel.com>
>>
>> Functions to implement inline data read/write, and move inline data to
>> normal data block when file size exceeds inline data limitation.
>>
>> Signed-off-by: Huajun Li <huajun.li@intel.com>
>> Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
>> Signed-off-by: Weihong Xu <weihong.xu@intel.com>
>> ---
>> fs/f2fs/Makefile | 2 +-
>> fs/f2fs/f2fs.h | 7 +++
>> fs/f2fs/inline.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 152 insertions(+), 1 deletion(-)
>> create mode 100644 fs/f2fs/inline.c
>>
>
> [snip]
>
>> +static int __f2fs_convert_inline_data(struct inode *inode, struct page *page)
>> +{
>> + int err;
>> + struct page *ipage;
>> + struct dnode_of_data dn;
>> + void *src_addr, *dst_addr;
>> + struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
>> +
>
> Here.. f2fs_lock_op(sbi);
>
>> + ipage = get_node_page(sbi, inode->i_ino);
>> + if (IS_ERR(ipage))
>> + return PTR_ERR(ipage);
>> +
>
> Need to move f2fs_lock_op prior to get_node_page.
>
>> + /* i_addr[0] is not used for inline data,
>
> Coding style.
> /*
> * ...
> */
>
>> + * so reserving new block will not destroy inline data */
>> + err = f2fs_reserve_block(inode, &dn, 0);
>> + if (err) {
>> + f2fs_put_page(ipage, 1);
>> + f2fs_unlock_op(sbi);
>> + return err;
>> + }
>
> Need to move this too.
>
>> +
>> + src_addr = inline_data_addr(ipage);
>> + dst_addr = page_address(page);
>> + zero_user_segment(page, 0, PAGE_CACHE_SIZE);
>
> + space for readability.
>
>> + /* Copy the whole inline data block */
>> + memcpy(dst_addr, src_addr, MAX_INLINE_DATA);
>> + zero_user_segment(ipage, INLINE_DATA_OFFSET,
>> + INLINE_DATA_OFFSET + MAX_INLINE_DATA);
>> + clear_inode_flag(F2FS_I(inode), FI_INLINE_DATA);
>> + set_raw_inline(F2FS_I(inode),
>> + (struct f2fs_inode *)page_address(ipage));

Thanks for your comments, I will update them according to above comments.

>
> --> sync_inode_page()?
>
IMO, we just handle file data, so do we still need call sync_inode_page() ?

>> +
>> + set_page_dirty(ipage);
>> + f2fs_put_page(ipage, 1);
>> + set_page_dirty(page);
>
> Here... f2fs_unlock_op(sbi);
>
> Here, we need to consider data consistency.
> Let's think about the below scenario.
> 1. inline_data was written.
> 2. sync_fs is done.
> 3. additional data were written.
> : this triggers f2fs_convert_inline_data(), produces a page, and then
> unsets the inline flag.
> 4. checkpoint was done with updated inode page. Note that, checkpoint
> doesn't guarantee any user data.
> 5. sudden power-off is occurred.
> -> Once power-off-recovery is done, we loose the inline_data which was
> written successfully at step #2.
>
> So, I think we need to do f2fs_sync_file() procedure at this moment.
> Any idea?
>

Yes, need consider this case carefully, thanks for your reminder.

Considering sudden power-off may happen before f2fs_sync_file() is
called, so how about following solutions:
...
/* Copy the whole inline data block */
memcpy(dst_addr, src_addr, MAX_INLINE_DATA);

do f2fs_sync_file() procedure ( Or do write_data_page() procedure ? )

zero_user_segment(ipage, INLINE_DATA_OFFSET, INLINE_DATA_OFFSET +
MAX_INLINE_DATA);
clear_inode_flag(F2FS_I(inode), FI_INLINE_DATA);
set_raw_inline(F2FS_I(inode), (struct f2fs_inode *)page_address(ipage));
...

>> +
>> + return 0;
>> +}
>> +
>> +int f2fs_convert_inline_data(struct inode *inode,
>> + struct page *p, unsigned flags)
>> +{
>> + int err;
>> + struct page *page;
>> +
>> + if (p && !p->index) {
>> + page = p;
>> + } else {
>> + page = grab_cache_page_write_begin(inode->i_mapping, 0, flags);
>> + if (IS_ERR(page))
>> + return PTR_ERR(page);
>> + }
>> +
>> + err = __f2fs_convert_inline_data(inode, page);
>> +
>> + if (p && !p->index)
>> + f2fs_put_page(page, 1);
>> +
>> + return err;
>> +}
>> +
>> +int f2fs_write_inline_data(struct inode *inode,
>> + struct page *page, unsigned size)
>> +{
>> + void *src_addr, *dst_addr;
>> + struct page *ipage;
>> + struct dnode_of_data dn;
>> + int err;
>> +
>> + set_new_dnode(&dn, inode, NULL, NULL, 0);
>> + err = get_dnode_of_data(&dn, 0, LOOKUP_NODE);
>> + if (err)
>> + return err;
>> + ipage = dn.inode_page;
>> +
>> + src_addr = page_address(page);
>> + dst_addr = inline_data_addr(ipage);
>> +
>> + zero_user_segment(ipage, INLINE_DATA_OFFSET,
>> + INLINE_DATA_OFFSET + MAX_INLINE_DATA);
>> + memcpy(dst_addr, src_addr, size);
>> + if (!f2fs_has_inline_data(inode))
>> + set_inode_flag(F2FS_I(inode), FI_INLINE_DATA);
>> + set_raw_inline(F2FS_I(inode),
>> + (struct f2fs_inode *)page_address(ipage));
>> + set_page_dirty(ipage);
>> +
>> + if ((F2FS_I(inode)->i_xattr_nid && inode->i_blocks == 2) ||
>> + (!F2FS_I(inode)->i_xattr_nid && inode->i_blocks == 1)) {
>> + f2fs_put_dnode(&dn);
>> + return 0;
>> + }
>> +
>> + /* Release the first data block if it is allocated */
>> + truncate_data_blocks_range(&dn, 1);
>> + f2fs_put_dnode(&dn);
>> +
>> + return 0;
>> +}
>
> --
> Jaegeuk Kim
> Samsung
>
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