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SubjectRe: [f2fs-dev] [PATCH] f2fs: change the method of calculating the number summary blocks
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Hi,

2013-10-28 (월), 08:54 +0000, Fan Li:
> "There is a HTML error in the previous email, so I send this one.If you already received this before, please ignore it.Sorry for the inconvenience"
>
> This patch change the method of calculating the number of summary blocks in function npages_for_summary_flush.
> npages_for_summary_flush uses (SUMMARY_SIZE + 1) as the size of a f2fs_summary while the actual size is just SUMMARY_SIZE.
> As a result, occasionally the return value of npages_for_summary_flush will be bigger than the actual number by one, and the checkpoint won't be written contiguously into disk.
> Besides, struct f2fs_summary can't be split to two pages, so it could take more space than the sum of its size, the current version seems not to take it into account.
>

Again. Please write a description not to exceed 80 columns.

> Signed-off-by: Fan Li <fanofcode.li@samsung.com>
> ---
> fs/f2fs/segment.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 487af61..ba2930f 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -279,9 +279,8 @@ static void __add_sum_entry(struct f2fs_sb_info *sbi, int type,
> */
> int npages_for_summary_flush(struct f2fs_sb_info *sbi) {
> - int total_size_bytes = 0;
> int valid_sum_count = 0;
> - int i, sum_space;
> + int i, sum_in_page;
>
> for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
> if (sbi->ckpt->alloc_type[i] == SSR)
> @@ -290,13 +289,12 @@ int npages_for_summary_flush(struct f2fs_sb_info *sbi)
> valid_sum_count += curseg_blkoff(sbi, i);
> }
>
> - total_size_bytes = valid_sum_count * (SUMMARY_SIZE + 1)
> - + sizeof(struct nat_journal) + 2
> - + sizeof(struct sit_journal) + 2;
> - sum_space = PAGE_CACHE_SIZE - SUM_FOOTER_SIZE;
> - if (total_size_bytes < sum_space)
> + sum_in_page = (PAGE_CACHE_SIZE - 2*SUM_JOURNAL_SIZE - SUM_FOOTER_SIZE)/

sum_in_page = (PAGE_CACHE_SIZE - 2 * SUM_JOURNAL_SIZE -
SUM_FOOTER_SIZE) / SUMMARY_SIZE;

Coding style.

> + SUMMARY_SIZE;
> + if (valid_sum_count <= sum_in_page)
> return 1;
> - else if (total_size_bytes < 2 * sum_space)
> + else if (valid_sum_count-sum_in_page <=
> + (PAGE_CACHE_SIZE-SUM_FOOTER_SIZE)/SUMMARY_SIZE)

ditto.

> return 2;
> return 3;
> }
> --
> 1.7.9.5

--
Jaegeuk Kim
Samsung

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