[f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Yangtao Li via Linux-f2fs-devel]

No need to call f2fs_issue_discard_timeout() in f2fs_put_super,
when no discard command requires issue. Since the caller of
f2fs_issue_discard_timeout() usually judges the number of discard
commands before using it. Let's move this logic to
f2fs_issue_discard_timeout().

By the way, use f2fs_realtime_discard_enable to simplify the code.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
 fs/f2fs/segment.c | 6 ++++--
 fs/f2fs/super.c   | 8 ++------
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 9486ca49ecb1..d5f150a08285 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1655,6 +1655,9 @@ bool f2fs_issue_discard_timeout(struct f2fs_sb_info *sbi)
 	struct discard_policy dpolicy;
 	bool dropped;
 
+	if (!atomic_read(&dcc->discard_cmd_cnt))
+		return false;
+
 	__init_discard_policy(sbi, &dpolicy, DPOLICY_UMOUNT,
 					dcc->discard_granularity);
 	__issue_discard_cmd(sbi, &dpolicy);
@@ -2110,8 +2113,7 @@ static void destroy_discard_cmd_control(struct f2fs_sb_info *sbi)
 	 * Recovery can cache discard commands, so in error path of
 	 * fill_super(), it needs to give a chance to handle them.
 	 */
-	if (unlikely(atomic_read(&dcc->discard_cmd_cnt)))
-		f2fs_issue_discard_timeout(sbi);
+	f2fs_issue_discard_timeout(sbi);
 
 	kfree(dcc);
 	SM_I(sbi)->dcc_info = NULL;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 79bf1faf4161..aa1cadfd34a5 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1576,8 +1576,7 @@ static void f2fs_put_super(struct super_block *sb)
 	/* be sure to wait for any on-going discard commands */
 	dropped = f2fs_issue_discard_timeout(sbi);
 
-	if ((f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) &&
-					!sbi->discard_blks && !dropped) {
+	if (f2fs_realtime_discard_enable(sbi) && !sbi->discard_blks && !dropped) {
 		struct cp_control cpc = {
 			.reason = CP_UMOUNT | CP_TRIMMED,
 		};
@@ -2225,7 +2224,6 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	bool no_discard = !test_opt(sbi, DISCARD);
 	bool no_compress_cache = !test_opt(sbi, COMPRESS_CACHE);
 	bool block_unit_discard = f2fs_block_unit_discard(sbi);
-	struct discard_cmd_control *dcc;
 #ifdef CONFIG_QUOTA
 	int i, j;
 #endif
@@ -2406,10 +2404,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 				goto restore_flush;
 			need_stop_discard = true;
 		} else {
-			dcc = SM_I(sbi)->dcc_info;
 			f2fs_stop_discard_thread(sbi);
-			if (atomic_read(&dcc->discard_cmd_cnt))
-				f2fs_issue_discard_timeout(sbi);
+			f2fs_issue_discard_timeout(sbi);
 			need_restart_discard = true;
 		}
 	}
-- 
2.25.1



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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Chao Yu]

On 2022/12/2 12:58, Yangtao Li wrote:
> No need to call f2fs_issue_discard_timeout() in f2fs_put_super,
> when no discard command requires issue. Since the caller of
> f2fs_issue_discard_timeout() usually judges the number of discard
> commands before using it. Let's move this logic to
> f2fs_issue_discard_timeout().
> 
> By the way, use f2fs_realtime_discard_enable to simplify the code.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Yangtao Li <frank.li@vivo.com>
> ---
>   fs/f2fs/segment.c | 6 ++++--
>   fs/f2fs/super.c   | 8 ++------
>   2 files changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 9486ca49ecb1..d5f150a08285 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1655,6 +1655,9 @@ bool f2fs_issue_discard_timeout(struct f2fs_sb_info *sbi)
>   	struct discard_policy dpolicy;
>   	bool dropped;
>   
> +	if (!atomic_read(&dcc->discard_cmd_cnt))
> +		return false;
> +
>   	__init_discard_policy(sbi, &dpolicy, DPOLICY_UMOUNT,
>   					dcc->discard_granularity);
>   	__issue_discard_cmd(sbi, &dpolicy);
> @@ -2110,8 +2113,7 @@ static void destroy_discard_cmd_control(struct f2fs_sb_info *sbi)
>   	 * Recovery can cache discard commands, so in error path of
>   	 * fill_super(), it needs to give a chance to handle them.
>   	 */
> -	if (unlikely(atomic_read(&dcc->discard_cmd_cnt)))
> -		f2fs_issue_discard_timeout(sbi);
> +	f2fs_issue_discard_timeout(sbi);
>   
>   	kfree(dcc);
>   	SM_I(sbi)->dcc_info = NULL;
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 79bf1faf4161..aa1cadfd34a5 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1576,8 +1576,7 @@ static void f2fs_put_super(struct super_block *sb)
>   	/* be sure to wait for any on-going discard commands */
>   	dropped = f2fs_issue_discard_timeout(sbi);
>   
> -	if ((f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) &&
> -					!sbi->discard_blks && !dropped) {
> +	if (f2fs_realtime_discard_enable(sbi) && !sbi->discard_blks && !dropped) {

static inline bool f2fs_realtime_discard_enable(struct f2fs_sb_info *sbi)
{
	return (test_opt(sbi, DISCARD) && f2fs_hw_support_discard(sbi)) ||
					f2fs_hw_should_discard(sbi);
}

It looks the logic is changed?

Thanks,


>   		struct cp_control cpc = {
>   			.reason = CP_UMOUNT | CP_TRIMMED,
>   		};
> @@ -2225,7 +2224,6 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
>   	bool no_discard = !test_opt(sbi, DISCARD);
>   	bool no_compress_cache = !test_opt(sbi, COMPRESS_CACHE);
>   	bool block_unit_discard = f2fs_block_unit_discard(sbi);
> -	struct discard_cmd_control *dcc;
>   #ifdef CONFIG_QUOTA
>   	int i, j;
>   #endif
> @@ -2406,10 +2404,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
>   				goto restore_flush;
>   			need_stop_discard = true;
>   		} else {
> -			dcc = SM_I(sbi)->dcc_info;
>   			f2fs_stop_discard_thread(sbi);
> -			if (atomic_read(&dcc->discard_cmd_cnt))
> -				f2fs_issue_discard_timeout(sbi);
> +			f2fs_issue_discard_timeout(sbi);
>   			need_restart_discard = true;
>   		}
>   	}


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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Yangtao Li via Linux-f2fs-devel]

Hi,

> static inline bool f2fs_realtime_discard_enable(struct f2fs_sb_info *sbi) {
> 	return (test_opt(sbi, DISCARD) && f2fs_hw_support_discard(sbi)) ||
> 					f2fs_hw_should_discard(sbi);
> }

> It looks the logic is changed?

For a storage device that does not support discard, and we have not actually
issued any discard command. I don't think it is necessary and f2fs should not
be equipped with trim markers.

Thx,
Yangtao


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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Chao Yu]

On 2022/12/12 21:05, Yangtao Li wrote:
> Hi,
> 
>> static inline bool f2fs_realtime_discard_enable(struct f2fs_sb_info *sbi) {
>> 	return (test_opt(sbi, DISCARD) && f2fs_hw_support_discard(sbi)) ||
>> 					f2fs_hw_should_discard(sbi);
>> }
> 
>> It looks the logic is changed?
> 
> For a storage device that does not support discard, and we have not actually
> issued any discard command. I don't think it is necessary and f2fs should not
> be equipped with trim markers.

The difference here is, if we use f2fs_realtime_discard_enable() in
f2fs_put_super(), we will only write checkpoint w/ CP_TRIMMED flag
when discard option is enable and device supports discard.

But actually, if discard option is disabled, we still needs to give
put_super() a chance to write checkpoint w/ CP_TRIMMED flag.

Thanks,

> 
> Thx,
> Yangtao


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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Yangtao Li via Linux-f2fs-devel]

Hi Chao,

> The difference here is, if we use f2fs_realtime_discard_enable() in
> f2fs_put_super(), we will only write checkpoint w/ CP_TRIMMED flag
> when discard option is enable and device supports discard.

> But actually, if discard option is disabled, we still needs to give
> put_super() a chance to write checkpoint w/ CP_TRIMMED flag.

Why do we still have to set the CP_TRIMMED flag when the discard opt is not set.
Did I miss something?

Thx,
Yangtao


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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Chao Yu]

On 2022/12/12 22:14, Yangtao Li wrote:
> Hi Chao,
> 
>> The difference here is, if we use f2fs_realtime_discard_enable() in
>> f2fs_put_super(), we will only write checkpoint w/ CP_TRIMMED flag
>> when discard option is enable and device supports discard.
> 
>> But actually, if discard option is disabled, we still needs to give
>> put_super() a chance to write checkpoint w/ CP_TRIMMED flag.
> 
> Why do we still have to set the CP_TRIMMED flag when the discard opt is not set.
> Did I miss something?

Hi Yangtao,

I guess it's up to scenario. e.g.

mount w/ nodiscard and use FITRIM to trigger in-batch discard,
if we set CP_TRIMMED flag during umount, next time, after mount
w/ discard, it doesn't to issue redundant discard.

Thanks,

> 
> Thx,
> Yangtao


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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Jaegeuk Kim]

On 12/12, Chao Yu wrote:
> On 2022/12/12 22:14, Yangtao Li wrote:
> > Hi Chao,
> > 
> > > The difference here is, if we use f2fs_realtime_discard_enable() in
> > > f2fs_put_super(), we will only write checkpoint w/ CP_TRIMMED flag
> > > when discard option is enable and device supports discard.
> > 
> > > But actually, if discard option is disabled, we still needs to give
> > > put_super() a chance to write checkpoint w/ CP_TRIMMED flag.
> > 
> > Why do we still have to set the CP_TRIMMED flag when the discard opt is not set.
> > Did I miss something?
> 
> Hi Yangtao,
> 
> I guess it's up to scenario. e.g.
> 
> mount w/ nodiscard and use FITRIM to trigger in-batch discard,
> if we set CP_TRIMMED flag during umount, next time, after mount
> w/ discard, it doesn't to issue redundant discard.

If fitrim was called with a range, we can get a wrong FI_TRIMMED flag. Isn't it
better to get a full discard range after remount even though some are redundant?

> 
> Thanks,
> 
> > 
> > Thx,
> > Yangtao


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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Chao Yu]

On 2022/12/13 6:45, Jaegeuk Kim wrote:
> On 12/12, Chao Yu wrote:
>> On 2022/12/12 22:14, Yangtao Li wrote:
>>> Hi Chao,
>>>
>>>> The difference here is, if we use f2fs_realtime_discard_enable() in
>>>> f2fs_put_super(), we will only write checkpoint w/ CP_TRIMMED flag
>>>> when discard option is enable and device supports discard.
>>>
>>>> But actually, if discard option is disabled, we still needs to give
>>>> put_super() a chance to write checkpoint w/ CP_TRIMMED flag.
>>>
>>> Why do we still have to set the CP_TRIMMED flag when the discard opt is not set.
>>> Did I miss something?
>>
>> Hi Yangtao,
>>
>> I guess it's up to scenario. e.g.
>>
>> mount w/ nodiscard and use FITRIM to trigger in-batch discard,
>> if we set CP_TRIMMED flag during umount, next time, after mount
>> w/ discard, it doesn't to issue redundant discard.
> 
> If fitrim was called with a range, we can get a wrong FI_TRIMMED flag. Isn't it

We can set CP_TRIMMED flag only if fitrim was called on full range w/ 4k granularity,
due to it will check sbi->discard_blks variable to make sure there is no range we
haven't trimmed.

> better to get a full discard range after remount even though some are redundant?

If nodiscard is set, and sbi->discard_blks becomes zero, it says a full range fitrim
was been triggered.

So, previous check condition has no problem, right?

	if ((f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) &&
					!sbi->discard_blks && !dropped) {

Thanks,

> 
>>
>> Thanks,
>>
>>>
>>> Thx,
>>> Yangtao


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Re: [f2fs-dev] [PATCH v2] f2fs: don't call f2fs_issue_discard_timeout() when discard_cmd_cnt is 0 in f2fs_put_super()

[Jaegeuk Kim]

On 12/13, Chao Yu wrote:
> On 2022/12/13 6:45, Jaegeuk Kim wrote:
> > On 12/12, Chao Yu wrote:
> > > On 2022/12/12 22:14, Yangtao Li wrote:
> > > > Hi Chao,
> > > > 
> > > > > The difference here is, if we use f2fs_realtime_discard_enable() in
> > > > > f2fs_put_super(), we will only write checkpoint w/ CP_TRIMMED flag
> > > > > when discard option is enable and device supports discard.
> > > > 
> > > > > But actually, if discard option is disabled, we still needs to give
> > > > > put_super() a chance to write checkpoint w/ CP_TRIMMED flag.
> > > > 
> > > > Why do we still have to set the CP_TRIMMED flag when the discard opt is not set.
> > > > Did I miss something?
> > > 
> > > Hi Yangtao,
> > > 
> > > I guess it's up to scenario. e.g.
> > > 
> > > mount w/ nodiscard and use FITRIM to trigger in-batch discard,
> > > if we set CP_TRIMMED flag during umount, next time, after mount
> > > w/ discard, it doesn't to issue redundant discard.
> > 
> > If fitrim was called with a range, we can get a wrong FI_TRIMMED flag. Isn't it
> 
> We can set CP_TRIMMED flag only if fitrim was called on full range w/ 4k granularity,
> due to it will check sbi->discard_blks variable to make sure there is no range we
> haven't trimmed.
> 
> > better to get a full discard range after remount even though some are redundant?
> 
> If nodiscard is set, and sbi->discard_blks becomes zero, it says a full range fitrim
> was been triggered.

That gives another assumption, and I prefer to make it simple.

> 
> So, previous check condition has no problem, right?
> 
> 	if ((f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) &&
> 					!sbi->discard_blks && !dropped) {
> 
> Thanks,
> 
> > 
> > > 
> > > Thanks,
> > > 
> > > > 
> > > > Thx,
> > > > Yangtao


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