Re: [PATCH] f2fs: rebuild sit page from sit info in mem

[Chao Yu <chao@kernel.org>]

On 2018/1/24 10:39, Yunlei He wrote:
> This patch rebuild sit page from sit info in mem instead
> of issue a read io.

At a glance, how about just changing codes in get_next_sit_page?

Thanks,

> 
> Signed-off-by: Yunlei He <heyunlei@huawei.com>
> ---
>  fs/f2fs/segment.c | 53 ++++++++++++++++++++++++-----------------------------
>  fs/f2fs/segment.h | 10 ++++++++++
>  2 files changed, 34 insertions(+), 29 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index e5739ce..9435261 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -3109,34 +3109,6 @@ static struct page *get_current_sit_page(struct f2fs_sb_info *sbi,
>  	return get_meta_page(sbi, current_sit_addr(sbi, segno));
>  }
>  
> -static struct page *get_next_sit_page(struct f2fs_sb_info *sbi,
> -					unsigned int start)
> -{
> -	struct sit_info *sit_i = SIT_I(sbi);
> -	struct page *src_page, *dst_page;
> -	pgoff_t src_off, dst_off;
> -	void *src_addr, *dst_addr;
> -
> -	src_off = current_sit_addr(sbi, start);
> -	dst_off = next_sit_addr(sbi, src_off);
> -
> -	/* get current sit block page without lock */
> -	src_page = get_meta_page(sbi, src_off);
> -	dst_page = grab_meta_page(sbi, dst_off);
> -	f2fs_bug_on(sbi, PageDirty(src_page));
> -
> -	src_addr = page_address(src_page);
> -	dst_addr = page_address(dst_page);
> -	memcpy(dst_addr, src_addr, PAGE_SIZE);
> -
> -	set_page_dirty(dst_page);
> -	f2fs_put_page(src_page, 1);
> -
> -	set_to_next_sit(sit_i, start);
> -
> -	return dst_page;
> -}
> -
>  static struct sit_entry_set *grab_sit_entry_set(void)
>  {
>  	struct sit_entry_set *ses =
> @@ -3261,6 +3233,7 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	 */
>  	list_for_each_entry_safe(ses, tmp, head, set_list) {
>  		struct page *page = NULL;
> +		struct address_space *mapping = META_MAPPING(sbi);
>  		struct f2fs_sit_block *raw_sit = NULL;
>  		unsigned int start_segno = ses->start_segno;
>  		unsigned int end = min(start_segno + SIT_ENTRY_PER_BLOCK,
> @@ -3274,8 +3247,30 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  		if (to_journal) {
>  			down_write(&curseg->journal_rwsem);
>  		} else {
> -			page = get_next_sit_page(sbi, start_segno);
> +			pgoff_t src_off, dst_off;
> +			int i;
> +
> +			src_off = current_sit_addr(sbi, start_segno);
> +			dst_off = next_sit_addr(sbi, src_off);
> +			set_to_next_sit(sit_i, start_segno);
> +repeat:
> +			page = f2fs_grab_cache_page(mapping, dst_off, false);
> +			if (!page) {
> +				cond_resched();
> +				goto repeat;
> +			}
> +
> +			f2fs_wait_on_page_writeback(page, META, true);
> +			set_page_dirty(page);
>  			raw_sit = page_address(page);
> +			if (!PageUptodate(page)) {
> +				for (i = 0; i < end - start_segno; i++) {
> +					se = get_seg_entry(sbi, start_segno + i);
> +					seg_info_to_sit_page(se,
> +							&raw_sit->entries[i]);
> +				}
> +				SetPageUptodate(page);
> +			}
>  		}
>  
>  		/* flush dirty sit entries in region of current sit set */
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 1a807e6..e346d90 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -348,6 +348,16 @@ static inline void seg_info_from_raw_sit(struct seg_entry *se,
>  	se->mtime = le64_to_cpu(rs->mtime);
>  }
>  
> +static inline void seg_info_to_sit_page(struct seg_entry *se,
> +					struct f2fs_sit_entry *rs)
> +{
> +	unsigned short raw_vblocks = (se->type << SIT_VBLOCKS_SHIFT) |
> +					se->valid_blocks;
> +	rs->vblocks = cpu_to_le16(raw_vblocks);
> +	memcpy(rs->valid_map, se->cur_valid_map, SIT_VBLOCK_MAP_SIZE);
> +	rs->mtime = cpu_to_le64(se->mtime);
> +}
> +
>  static inline void seg_info_to_raw_sit(struct seg_entry *se,
>  					struct f2fs_sit_entry *rs)
>  {
> 

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