2024-05-29 08:45:22

by Chao Yu

[permalink] [raw]
Subject: Re: [PATCH] f2fs: fix to avoid use SSR allocate when do defragment

On 2024/5/29 16:19, Zhiguo Niu wrote:
> SSR allocate mode will be used when doing file defragment
> if ATGC is working at the same time, that is because
> set_page_private_gcing may make CURSEG_ALL_DATA_ATGC segment
> type got in f2fs_allocate_data_block when defragment page
> is writeback, which may cause file fragmentation is worse.
>
> A file with 2 fragmentations is changed as following after defragment:
>
> ----------------file info-------------------
> sensorsdata :
> --------------------------------------------
> dev [254:48]
> ino [0x 3029 : 12329]
> mode [0x 81b0 : 33200]
> nlink [0x 1 : 1]
> uid [0x 27e6 : 10214]
> gid [0x 27e6 : 10214]
> size [0x 242000 : 2367488]
> blksize [0x 1000 : 4096]
> blocks [0x 1210 : 4624]
> --------------------------------------------
>
> file_pos start_blk end_blk blks
> 0 11361121 11361207 87
> 356352 11361215 11361216 2
> 364544 11361218 11361218 1
> 368640 11361220 11361221 2
> 376832 11361224 11361225 2
> 385024 11361227 11361238 12
> 434176 11361240 11361252 13
> 487424 11361254 11361254 1
> 491520 11361271 11361279 9
> 528384 3681794 3681795 2
> 536576 3681797 3681797 1
> 540672 3681799 3681799 1
> 544768 3681803 3681803 1
> 548864 3681805 3681805 1
> 552960 3681807 3681807 1
> 557056 3681809 3681809 1
>
> A new FI flag FI_DEFRAG_IN_PROGRESS is introduced to avoid
> this scenarios.
>
> Signed-off-by: Zhiguo Niu <[email protected]>
> ---
> fs/f2fs/f2fs.h | 1 +
> fs/f2fs/file.c | 2 ++
> fs/f2fs/segment.c | 3 ++-
> 3 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 4044e67..9281c5e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -803,6 +803,7 @@ enum {
> FI_COW_FILE, /* indicate COW file */
> FI_ATOMIC_COMMITTED, /* indicate atomic commit completed except disk sync */
> FI_ATOMIC_REPLACE, /* indicate atomic replace */
> + FI_DEFRAG_IN_PROGRESS, /* indicate file was defragmenting */
> FI_MAX, /* max flag, never be used */
> };
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 5c0b281..93d2767 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -2717,6 +2717,7 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
> goto out;
> }
>
> + set_inode_flag(inode, FI_DEFRAG_IN_PROGRESS);
> map.m_lblk = pg_start;
> map.m_len = pg_end - pg_start;
> total = 0;
> @@ -2772,6 +2773,7 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
> clear_out:
> clear_inode_flag(inode, FI_SKIP_WRITES);
> out:
> + clear_inode_flag(inode, FI_DEFRAG_IN_PROGRESS);
> clear_inode_flag(inode, FI_OPU_WRITE);
> unlock_out:
> inode_unlock(inode);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 7caf20a..dd6f8ac 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -3482,7 +3482,8 @@ static int __get_segment_type_6(struct f2fs_io_info *fio)
> if (page_private_gcing(fio->page)) {
> if (fio->sbi->am.atgc_enabled &&
> (fio->io_type == FS_DATA_IO) &&
> - (fio->sbi->gc_mode != GC_URGENT_HIGH))
> + (fio->sbi->gc_mode != GC_URGENT_HIGH) &&
> + !is_inode_flag_set(inode, FI_DEFRAG_IN_PROGRESS))

How about checking FI_OPU_WRITE flag?

Thanks,

> return CURSEG_ALL_DATA_ATGC;
> else
> return CURSEG_COLD_DATA;