Messages in this thread | | | Subject | Re: [PATCH 2/5] f2fs: clear the remaining prefree_map of the section | From | Chao Yu <> | Date | Tue, 17 Jul 2018 17:12:11 +0800 |
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On 2018/7/13 11:28, Yunlong Song wrote: > round 1: section bitmap : 1 1 1 1 1, all valid, prefree_map: 0 0 0 0 0 > then rm data block NO.2, block NO.2 becomes invalid, prefree_map: 0 0 1 0 0 > write_checkpoint: section bitmap: 1 1 0 1 1, prefree_map: 0 0 0 0 0, > prefree of NO.2 is cleared, and no discard issued > > round2: rm data block NO.0, NO.1, NO.3, NO.4 > all invalid, but prefree bit of NO.2 is set and cleared in round1, then > prefree_map: 1 1 0 1 1 > write_checkpoint: section bitmap: 0 0 0 0 0, prefree_map: 0 0 0 1 1, no > valid blocks of this section, so discard issued > but this time prefree bit of NO.3 and NO.4 is skipped...
due to start = start_segno + sbi->segs_per_sec;
> > round3: > write_checkpoint: section bitmap: 0 0 0 0 0, prefree_map: 0 0 0 1 1 - > > 0 0 0 0 0, no valid blocks of this section, so discard issued > this time prefree bit of NO.3 and NO.4 is cleared, but the discard of > this section is sent again...
Could you add this into commit log?
Thanks,
> > On 2018/7/13 11:13, Chao Yu wrote: >> On 2018/7/12 23:09, Yunlong Song wrote: >>> For the case when sbi->segs_per_sec > 1, 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 didn't get it, if # 2 segment is not prefree state, so it still has valid >> blocks there, so we won't issue discard due to below condition, right? >> >> if (!IS_CURSEC(sbi, secno) && >> !get_valid_blocks(sbi, start, true)) >> >> Thanks, >> >>> Signed-off-by: Yunlong Song <yunlong.song@huawei.com> >>> --- >>> fs/f2fs/segment.c | 19 +++++++++++++++++-- >>> 1 file changed, 17 insertions(+), 2 deletions(-) >>> >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >>> index 47b6595..fd38b61 100644 >>> --- a/fs/f2fs/segment.c >>> +++ b/fs/f2fs/segment.c >>> @@ -1684,8 +1684,23 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi, >>> start = start_segno + sbi->segs_per_sec; >>> if (start < end) >>> goto next; >>> - else >>> - end = start - 1; >>> + else { >>> + start_segno = start; >>> + >>> + while (1) { >>> + start = find_next_bit(prefree_map, start_segno, >>> + end + 1); >>> + if (start >= start_segno) >>> + break; >>> + end = find_next_zero_bit(prefree_map, start_segno, >>> + start + 1); >>> + for (i = start; i < end; i++) >>> + clear_bit(i, prefree_map); >>> + dirty_i->nr_dirty[PRE] -= end - start; >>> + } >>> + >>> + end = start_segno - 1; >>> + } >>> } >>> mutex_unlock(&dirty_i->seglist_lock); >>> >>> >> >> . >> >
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