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SubjectRe: [f2fs-dev 4/5] f2fs: Key functions to handle inline data
From
Date
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));

--> 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?

> +
> + 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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