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From: Daeho Jeong <daeho43@gmail.com>
To: Chao Yu <chao@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com,
	Daeho Jeong <daehojeong@google.com>
Subject: Re: [f2fs-dev] [PATCH v4] f2fs: introduce fragment allocation mode mount option
Date: Fri, 10 Sep 2021 07:34:34 -0700	[thread overview]
Message-ID: <CACOAw_z+yfNN3p3U3Ji0vLe7xDP4vkVy11RdzwwcRwwnSTjsFg@mail.gmail.com> (raw)
In-Reply-To: <a59d23b9-961f-4129-7491-59f88923366a@kernel.org>

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,
> >>
> >>>

  reply	other threads:[~2021-09-10 14:34 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 17:24 Daeho Jeong
2021-09-02 23:57 ` [f2fs-dev] " Chao Yu
2021-09-03 20:33   ` Daeho Jeong
2021-09-04  3:33     ` Chao Yu
2021-09-04  4:40       ` Daeho Jeong
2021-09-04  6:45         ` Chao Yu
2021-09-07 18:12           ` Daeho Jeong
2021-09-09 23:50             ` Chao Yu
2021-09-10 14:34               ` Daeho Jeong [this message]
2021-09-10 15:24                 ` Daeho Jeong
2021-09-11 10:42                   ` Chao Yu
2021-09-10 23:13 ` Jaegeuk Kim
2021-09-11 23:45   ` [f2fs-dev] " Chao Yu
2021-09-20 22:57     ` Jaegeuk Kim
2021-09-22 15:23       ` Chao Yu

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