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SubjectRe: [PATCH v2] f2fs: clear the remaining prefree_map of the section
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On 2018/7/17 17:05, Chao Yu wrote:
> On 2018/7/16 18:03, Yunlong Song wrote:
>> For the case when sbi->segs_per_sec > 1 with lfs mode, take
>> section:segment = 5 for example, if the section prefree_map is
>> ...previous section | current section (1 1 0 1 1) | next section...,
>> then the start = x, end = x + 1, after start = start_segno +
>> sbi->segs_per_sec, start = x + 5, then it will skip x + 3 and x + 4, but
>> their bitmap is still set, which will cause duplicated
>> f2fs_issue_discard of this same section in the next write_checkpoint, so
>> fix it.
> I mean:
>
> Subject: [PATCH] f2fs: issue discard align to section in LFS mode
>
> ---
> fs/f2fs/segment.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index f12dad627fb4..6640c790cf64 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1761,6 +1761,7 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
> unsigned int start = 0, end = -1;
> unsigned int secno, start_segno;
> bool force = (cpc->reason & CP_DISCARD);
> + bool need_align = test_opt(sbi, LFS) && sbi->segs_per_sec > 1;
>
> mutex_lock(&dirty_i->seglist_lock);
>
> @@ -1772,10 +1773,15 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
> end = find_next_zero_bit(prefree_map, MAIN_SEGS(sbi),
> start + 1);
>
> - for (i = start; i < end; i++)
> - clear_bit(i, prefree_map);
> + if (need_align) {
> + start = rounddown(start, sbi->segs_per_sec);
> + end = roundup(start, sbi->segs_per_sec);
> + }
>
> - dirty_i->nr_dirty[PRE] -= end - start;
> + for (i = start; i < end; i++) {
> + if (test_and_clear_bit(i, prefree_map))
> + dirty_i->nr_dirty[PRE]--;
> + }
The above part should be put below if (!test_opt(sbi, DISCARD)), or in
test_opt(sbi, DISCARD) == 0 case,
the first segment of the next section will be skipped, if only the first
segment is prefree and all the other
segments of the section are not prefree.

> if (!test_opt(sbi, DISCARD))
> continue;
> @@ -2564,6 +2570,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
> struct discard_policy dpolicy;
> unsigned long long trimmed = 0;
> int err = 0;
> + bool need_align = test_opt(sbi, LFS) && sbi->segs_per_sec > 1;
>
> if (start >= MAX_BLKADDR(sbi) || range->len < sbi->blocksize)
> return -EINVAL;
> @@ -2582,6 +2589,12 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
> end_segno = (end >= MAX_BLKADDR(sbi)) ? MAIN_SEGS(sbi) - 1 :
> GET_SEGNO(sbi, end);
>
> + if (need_align) {
> + start_segno = rounddown(start_segno, sbi->segs_per_sec);
> + end_segno = roundup(end_segno, sbi->segs_per_sec);
> + end_segno = min(end_segno, MAIN_SEGS(sbi) - 1);
> + }
> +
> cpc.reason = CP_DISCARD;
> cpc.trim_minlen = max_t(__u64, 1, F2FS_BYTES_TO_BLK(range->minlen));
> cpc.trim_start = start_segno;

--
Thanks,
Yunlong Song


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