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

Chao Yu
2024-06-05T03:48:07Z

On 2024/6/3 17:05, Zhiguo Niu wrote:
> On Mon, Jun 3, 2024 at 3:41 PM Chao Yu <chao@kernel.org> wrote:
>>
>> 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) {
>>
> Hi Chao,
>> Oh, I guess you want to fix this:
> Yes, Sorry for not making it clear before.
>>
>> 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.
> 1. I'm not sure if this will increase checkpoint time consumption?

Since it won't increase any IO time, I guess it's fine tolerate time consumed
by initialization of atgc curseg.

> 2. dynamically enabling atgc may have other problems. Is this confirmed?

I think so, checkpoint has avoided most race cases.

So, how do you think of below diff:

---
fs/f2fs/checkpoint.c | 2 ++
fs/f2fs/f2fs.h | 1 +
fs/f2fs/segment.c | 26 +++++++++++++++++++++++---
3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 55d444bec5c0..4a73bd481a25 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1718,6 +1718,8 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
}

f2fs_restore_inmem_curseg(sbi);
+ f2fs_reinit_atgc_curseg(sbi);
+
stat_inc_cp_count(sbi);
stop:
unblock_operations(sbi);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9688df332147..8d385a1c75ad 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3693,6 +3693,7 @@ 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 f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno);
int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi);
+int f2fs_reinit_atgc_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_allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type,
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index bdc2247387e8..6d4273faf061 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2949,12 +2949,12 @@ 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)
+static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi, bool force)
{
struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_ALL_DATA_ATGC);
int ret = 0;

- if (!sbi->am.atgc_enabled)
+ if (!sbi->am.atgc_enabled && !force)
return 0;

f2fs_down_read(&SM_I(sbi)->curseg_lock);
@@ -2971,9 +2971,29 @@ static int __f2fs_init_atgc_curseg(struct f2fs_sb_info *sbi)
f2fs_up_read(&SM_I(sbi)->curseg_lock);
return ret;
}
+
int f2fs_init_inmem_curseg(struct f2fs_sb_info *sbi)
{
- return __f2fs_init_atgc_curseg(sbi);
+ return __f2fs_init_atgc_curseg(sbi, false);
+}
+
+int f2fs_reinit_atgc_curseg(struct f2fs_sb_info *sbi)
+{
+ int ret;
+
+ if (!test_opt(sbi, ATGC))
+ return 0;
+ if (sbi->am.atgc_enabled)
+ return 0;
+ if (SIT_I(sbi)->elapsed_time < sbi->am.age_threshold)
+ return 0;
+
+ ret = __f2fs_init_atgc_curseg(sbi, true);
+ if (!ret) {
+ sbi->am.atgc_enabled = true;
+ f2fs_info(sbi, "reenabled age threshold GC");
+ }
+ return ret;
}

static void __f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi, int type)
--
2.40.1

> thanks！
>>
>> 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;