Messages in this thread | | | Date | Tue, 23 Mar 2021 15:59:39 -0700 | From | Jaegeuk Kim <> | Subject | Re: [PATCH RFC] f2fs: fix to avoid selecting full segment w/ {AT,}SSR allocator |
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On 03/19, Chao Yu wrote: > On 2021/3/19 1:17, Jaegeuk Kim wrote: > > On 02/20, Chao Yu wrote: > > > In cp disabling mode, there could be a condition > > > - target segment has 128 ckpt valid blocks > > > - GC migrates 128 valid blocks to other segment (segment is still in > > > dirty list) > > > - GC migrates 384 blocks to target segment (segment has 128 cp_vblocks > > > and 384 vblocks) > > > - If GC selects target segment via {AT,}SSR allocator, however there is > > > no free space in targe segment. > > > > > > Fixes: 4354994f097d ("f2fs: checkpoint disabling") > > > Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection") > > > Signed-off-by: Chao Yu <yuchao0@huawei.com> > > > --- > > > fs/f2fs/f2fs.h | 1 + > > > fs/f2fs/gc.c | 17 +++++++++++++---- > > > fs/f2fs/segment.c | 20 ++++++++++++++++++++ > > > 3 files changed, 34 insertions(+), 4 deletions(-) > > > > > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > > index ed7807103c8e..9c753eff0814 100644 > > > --- a/fs/f2fs/f2fs.h > > > +++ b/fs/f2fs/f2fs.h > > > @@ -3376,6 +3376,7 @@ block_t f2fs_get_unusable_blocks(struct f2fs_sb_info *sbi); > > > int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable); > > > void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi); > > > int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra); > > > +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno); > > > void f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi); > > > void f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi); > > > void f2fs_restore_inmem_curseg(struct f2fs_sb_info *sbi); > > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > > > index 86ba8ed0b8a7..a1d8062cdace 100644 > > > --- a/fs/f2fs/gc.c > > > +++ b/fs/f2fs/gc.c > > > @@ -392,10 +392,6 @@ static void add_victim_entry(struct f2fs_sb_info *sbi, > > > if (p->gc_mode == GC_AT && > > > get_valid_blocks(sbi, segno, true) == 0) > > > return; > > > - > > > - if (p->alloc_mode == AT_SSR && > > > - get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0) > > > - return; > > > } > > > for (i = 0; i < sbi->segs_per_sec; i++) > > > @@ -736,6 +732,19 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi, > > > if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap)) > > > goto next; > > > + if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) { > > > + /* > > > + * to avoid selecting candidate which has below valid > > > + * block distribution: > > > + * partial blocks are valid and all left ones are valid > > > + * in previous checkpoint. > > > + */ > > > + if (p.alloc_mode == SSR || p.alloc_mode == AT_SSR) { > > > + if (!segment_has_free_slot(sbi, segno)) > > > + goto next; > > > > Do we need to change this to check free_slot instead of get_ckpt_valid_blocks()? > > Jaegeuk, > > LFS was assigned only for GC case, in this case we are trying to select source > section, rather than target segment for SSR/AT_SSR case, so we don't need to > check free_slot. > > - f2fs_gc > - __get_victim > - get_victim(sbi, victim, gc_type, NO_CHECK_TYPE, LFS, 0); > > > > > 732 if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) && > > 733 get_ckpt_valid_blocks(sbi, segno) && > > 734 p.alloc_mode == LFS)) > > BTW, in LFS mode, GC wants to find source section rather than segment, so we > should change to check valid ckpt blocks in every segment of targe section here?
Alright. I refactored a bit on this patch with new one. Could you please take a look?
https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=00152bd7cabd69b4615ebead823ff23887b0e0f7
Thanks,
> > Thanks, > > > > > > > > + } > > > + } > > > + > > > if (is_atgc) { > > > add_victim_entry(sbi, &p, segno); > > > goto next; > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > > index 2d5a82c4ca15..deaf57e13125 100644 > > > --- a/fs/f2fs/segment.c > > > +++ b/fs/f2fs/segment.c > > > @@ -2650,6 +2650,26 @@ static void __refresh_next_blkoff(struct f2fs_sb_info *sbi, > > > seg->next_blkoff++; > > > } > > > +bool segment_has_free_slot(struct f2fs_sb_info *sbi, int segno) > > > +{ > > > + struct sit_info *sit = SIT_I(sbi); > > > + struct seg_entry *se = get_seg_entry(sbi, segno); > > > + int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long); > > > + unsigned long *target_map = SIT_I(sbi)->tmp_map; > > > + unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map; > > > + unsigned long *cur_map = (unsigned long *)se->cur_valid_map; > > > + int i, pos; > > > + > > > + down_write(&sit->sentry_lock); > > > + for (i = 0; i < entries; i++) > > > + target_map[i] = ckpt_map[i] | cur_map[i]; > > > + > > > + pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, 0); > > > + up_write(&sit->sentry_lock); > > > + > > > + return pos < sbi->blocks_per_seg; > > > +} > > > + > > > /* > > > * This function always allocates a used segment(from dirty seglist) by SSR > > > * manner, so it should recover the existing segment information of valid blocks > > > -- > > > 2.29.2 > > . > >
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