Messages in this thread | | | From | Daeho Jeong <> | Date | Fri, 10 Sep 2021 07:34:34 -0700 | Subject | Re: [f2fs-dev] [PATCH v4] f2fs: introduce fragment allocation mode mount option |
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On Thu, Sep 9, 2021 at 4:50 PM Chao Yu <chao@kernel.org> wrote: > > On 2021/9/8 2:12, Daeho Jeong wrote: > > On Fri, Sep 3, 2021 at 11:45 PM Chao Yu <chao@kernel.org> wrote: > >> > >> On 2021/9/4 12:40, Daeho Jeong wrote: > >>>> As a per curseg field. > >>>> > >>>>> Maybe, we run into the same race condition issue you told before for > >>>>> fragment_remained_chunk. > >>>>> Could you clarify this more? > >>>> > >>>> e.g. > >>>> > >>>> F2FS_OPTION(sbi).fs_mode = FS_MODE_FRAGMENT_FIXED_BLK > >>>> fragment_chunk_size = 384 > >>>> fragment_hole_size = 384 > >>>> > >>>> When creating hole: > >>>> > >>>> - f2fs_allocate_data_block > >>>> - __refresh_next_blkoff > >>>> chunk locates in [0, 383] of current segment > >>>> seg->next_blkoff = 384 > >>>> sbi->fragment_remained_chunk = 0 > >>>> then we will reset sbi->fragment_remained_chunk to 384 > >>>> and move seg->next_blkoff forward to 768 (384 + 384) > >>>> - __has_curseg_space() returns false > >>>> - allocate_segment() allocates new current segment > >>>> > >>>> So, for such case that hole may cross two segments, hole size may be truncated > >>>> to left size of previous segment. > >>> > >>> First, sbi->fragment_remained_chunk should be seg->fragment_remained_chunk. > >> > >> Oh, correct. > >> > >>> I understand what you mean, so you mean we need to take the leftover > >>> "hole" size over to the next segment? > >>> In the example, the leftover hole size will be (384 - (512-384)). Do > >>> you want to take this over to the next segment? > >> > >> Yes, the left 256 block-sized hole should be created before next chunk > >> in next opened segment. > >> > > > > Chao, > > > > Do you have any decent idea to pass the left hole size to the next > > segment which will be allocated? > > Daeho, > > I guess we can record left hole size in seg->fragment_remained_hole. >
I understand we need a new fragment_remained_hole variable in segment structure. But, I mean.. How can we pass over the left hole size from the previous segment to the next segment?
Thanks,
> Thanks, > > > > > Thanks, > > > >> Thanks, > >> > >>>
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