2022-11-22 10:15:38

by Yonggil Song

Subject: [RESEND][PATCH] f2fs: avoid victim selection from previous victim section

When f2fs chooses GC victim in large section & LFS mode,
next_victim_seg[gc_type] is referenced first. After segment is freed,
next_victim_seg[gc_type] has the next segment number.
However, next_victim_seg[gc_type] still has the last segment number
even after the last segment of section is freed. In this case, when f2fs
chooses a victim for the next GC round, the last segment of previous victim
section is chosen as a victim.

Initialize next_victim_seg[gc_type] to NULL_SEGNO for the last segment in
large section.

Fixes: e3080b0120a1 ("f2fs: support subsectional garbage collection")
Signed-off-by: Yonggil Song <[email protected]>
---
fs/f2fs/gc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 0f967b1e98f2..f1b68eda2235 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1749,8 +1749,9 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
get_valid_blocks(sbi, segno, false) == 0)
seg_freed++;

- if (__is_large_section(sbi) && segno + 1 < end_segno)
- sbi->next_victim_seg[gc_type] = segno + 1;
+ if (__is_large_section(sbi))
+ sbi->next_victim_seg[gc_type] =
+ (segno + 1 < end_segno) ? segno + 1 : NULL_SEGNO;
skip:
f2fs_put_page(sum_page, 0);
}
--
2.34.1

2022-11-24 16:00:10

by Chao Yu

Subject: Re: [RESEND][PATCH] f2fs: avoid victim selection from previous victim section

On 2022/11/22 17:03, Yonggil Song wrote:
> When f2fs chooses GC victim in large section & LFS mode,
> next_victim_seg[gc_type] is referenced first. After segment is freed,
> next_victim_seg[gc_type] has the next segment number.
> However, next_victim_seg[gc_type] still has the last segment number
> even after the last segment of section is freed. In this case, when f2fs
> chooses a victim for the next GC round, the last segment of previous victim
> section is chosen as a victim.
>
> Initialize next_victim_seg[gc_type] to NULL_SEGNO for the last segment in
> large section.
>
> Fixes: e3080b0120a1 ("f2fs: support subsectional garbage collection")
> Signed-off-by: Yonggil Song <[email protected]>

Reviewed-by: Chao Yu <[email protected]>

Thanks,