Re: [PATCH] f2fs: enable atgc if atgc_age_threshold from user is less than elapsed_time

Chao Yu
2024-06-03T07:41:10Z

On 2024/5/20 19:36, Zhiguo Niu wrote:
> Now atgc can be enabled based on the following conditions:
> -ATGC mount option is set
> -elapsed_time is more than atgc_age_threshold already
> but these conditions are check when umounted->mounted device again.
> If the device has not be umounted->mounted for a long time, atgc can
> not work even the above conditions met.
>
> It is better to enable atgc dynamiclly when user change atgc_age_threshold
> meanwhile this vale is less than elapsed_time and ATGC mount option is on.
>
> Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
> ---
> fs/f2fs/f2fs.h | 1 +
> fs/f2fs/segment.c | 9 ++++-----
> fs/f2fs/sysfs.c | 16 ++++++++++++++++
> 3 files changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 1974b6a..e441d2d 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -3694,6 +3694,7 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
> int 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);
> +int f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi);
> int f2fs_allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,
> unsigned int start, unsigned int end);
> int f2fs_allocate_new_section(struct f2fs_sb_info *sbi, int type, bool force);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 71dc8042..44923d4 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2931,14 +2931,11 @@ static int get_atssr_segment(struct f2fs_sb_info *sbi, int type,
> return ret;
> }
>
> -static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
> +int f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
> {
> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_ALL_DATA_ATGC);
> int ret = 0;
>
> - if (!sbi->am.atgc_enabled)
> - return 0;
> -
> f2fs_down_read(&SM_I(sbi)->curseg_lock);
>
> mutex_lock(&curseg->curseg_mutex);
> @@ -2955,7 +2952,9 @@ static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
> }
> int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi)
> {
> - return __f2fs_init_atgc_curseg(sbi);
> + if (!sbi->am.atgc_enabled)
> + return 0;
> + return f2fs_init_atgc_curseg(sbi);
> }
>
> static void __f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi, int type)
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 09d3ecf..72676c5 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -673,6 +673,22 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
> return count;
> }
>
> + if (!strcmp(a->attr.name, "atgc_age_threshold")) {
> + if (t < 0)
> + return -EINVAL;
> + sbi->am.age_threshold = t;
> + if (sbi->am.atgc_enabled)
> + return count;
> +
> + if (test_opt(sbi, ATGC) &&
> + le64_to_cpu(sbi->ckpt->elapsed_time) >= t) {

Oh, I guess you want to fix this:

static void init_atgc_management(struct f2fs_sb_info *sbi)
{
...
if (test_opt(sbi, ATGC) &&
SIT_I(sbi)->elapsed_time >= DEF_GC_THREAD_AGE_THRESHOLD)
am->atgc_enabled = true;

What about enabling atgc_enabled during checkpoint once elapsed time is
satisfed w/ the condition? I guess this can give another chance whenever
CP is been triggered, and it can avoid the racing condition as well.

Thanks,

> + if (f2fs_init_atgc_curseg(sbi))
> + return -EINVAL;
> + sbi->am.atgc_enabled = true;
> + }
> + return count;
> + }
> +
> if (!strcmp(a->attr.name, "gc_segment_mode")) {
> if (t < MAX_GC_MODE)
> sbi->gc_segment_mode = t;