2021-09-06 14:38:34

by yebin (H)

Subject: [PATCH -next 2/6] ext4: introduce last_check_time record previous check time

kmmpd:
...
diff = jiffies - last_update_time;
if (diff > mmp_check_interval * HZ) {
...
As "mmp_check_interval = 2 * mmp_update_interval", 'diff' always little
than 'mmp_update_interval', so there will never trigger detection.
Introduce last_check_time record previous check time.

Signed-off-by: Ye Bin <[email protected]>
---
fs/ext4/mmp.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 12af6dc8457b..89797f12a815 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -152,6 +152,7 @@ static int kmmpd(void *data)
int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
unsigned mmp_check_interval;
unsigned long last_update_time;
+ unsigned long last_check_time;
unsigned long diff;
int retval = 0;

@@ -170,6 +171,7 @@ static int kmmpd(void *data)

memcpy(mmp->mmp_nodename, init_utsname()->nodename,
sizeof(mmp->mmp_nodename));
+ last_update_time = jiffies;

while (!kthread_should_stop() && !sb_rdonly(sb)) {
if (!ext4_has_feature_mmp(sb)) {
@@ -198,17 +200,18 @@ static int kmmpd(void *data)
}

diff = jiffies - last_update_time;
- if (diff < mmp_update_interval * HZ)
+ if (diff < mmp_update_interval * HZ) {
schedule_timeout_interruptible(mmp_update_interval *
HZ - diff);
+ diff = jiffies - last_update_time;
+ }

/*
* We need to make sure that more than mmp_check_interval
- * seconds have not passed since writing. If that has happened
- * we need to check if the MMP block is as we left it.
+ * seconds have not passed since check. If that has happened
+ * we need to check if the MMP block is as we write it.
*/
- diff = jiffies - last_update_time;
- if (diff > mmp_check_interval * HZ) {
+ if (jiffies - last_check_time > mmp_check_interval * HZ) {
struct buffer_head *bh_check = NULL;
struct mmp_struct *mmp_check;

@@ -234,6 +237,7 @@ static int kmmpd(void *data)
goto wait_to_exit;
}
put_bh(bh_check);
+ last_check_time = jiffies;
}

/*
--
2.31.1

2021-09-09 02:22:22

by Guoqing Jiang

Subject: Re: [PATCH -next 2/6] ext4: introduce last_check_time record previous check time

On 9/6/21 10:47 PM, Ye Bin wrote:
> kmmpd:
> ...
> diff = jiffies - last_update_time;
> if (diff > mmp_check_interval * HZ) {
> ...
> As "mmp_check_interval = 2 * mmp_update_interval", 'diff' always little
> than 'mmp_update_interval', so there will never trigger detection.
> Introduce last_check_time record previous check time.
>
> Signed-off-by: Ye Bin <[email protected]>
> ---
> fs/ext4/mmp.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
> index 12af6dc8457b..89797f12a815 100644
> --- a/fs/ext4/mmp.c
> +++ b/fs/ext4/mmp.c
> @@ -152,6 +152,7 @@ static int kmmpd(void *data)
> int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
> unsigned mmp_check_interval;
> unsigned long last_update_time;
> + unsigned long last_check_time;
> unsigned long diff;
> int retval = 0;
>
> @@ -170,6 +171,7 @@ static int kmmpd(void *data)
>
> memcpy(mmp->mmp_nodename, init_utsname()->nodename,
> sizeof(mmp->mmp_nodename));
> + last_update_time = jiffies;
>
> while (!kthread_should_stop() && !sb_rdonly(sb)) {
> if (!ext4_has_feature_mmp(sb)) {
> @@ -198,17 +200,18 @@ static int kmmpd(void *data)
> }
>
> diff = jiffies - last_update_time;
> - if (diff < mmp_update_interval * HZ)
> + if (diff < mmp_update_interval * HZ) {
> schedule_timeout_interruptible(mmp_update_interval *
> HZ - diff);
> + diff = jiffies - last_update_time;
> + }
>
> /*
> * We need to make sure that more than mmp_check_interval
> - * seconds have not passed since writing. If that has happened
> - * we need to check if the MMP block is as we left it.
> + * seconds have not passed since check. If that has happened
> + * we need to check if the MMP block is as we write it.
> */
> - diff = jiffies - last_update_time;
> - if (diff > mmp_check_interval * HZ) {
> + if (jiffies - last_check_time > mmp_check_interval * HZ) {

Before the above checking, seems last_check_time is not initialized yet.
> struct buffer_head *bh_check = NULL;
> struct mmp_struct *mmp_check;
>
> @@ -234,6 +237,7 @@ static int kmmpd(void *data)
> goto wait_to_exit;
> }
> put_bh(bh_check);
> + last_check_time = jiffies;
> }
>
> /*

Thanks,
Guoqing

2021-09-10 08:50:04

by yebin (H)

Subject: Re: [PATCH -next 2/6] ext4: introduce last_check_time record previous check time

On 2021/9/9 10:20, Guoqing Jiang wrote:
>
>
> On 9/6/21 10:47 PM, Ye Bin wrote:
>> kmmpd:
>> ...
>> diff = jiffies - last_update_time;
>> if (diff > mmp_check_interval * HZ) {
>> ...
>> As "mmp_check_interval = 2 * mmp_update_interval", 'diff' always little
>> than 'mmp_update_interval', so there will never trigger detection.
>> Introduce last_check_time record previous check time.
>>
>> Signed-off-by: Ye Bin <[email protected]>
>> ---
>> fs/ext4/mmp.c | 14 +++++++++-----
>> 1 file changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
>> index 12af6dc8457b..89797f12a815 100644
>> --- a/fs/ext4/mmp.c
>> +++ b/fs/ext4/mmp.c
>> @@ -152,6 +152,7 @@ static int kmmpd(void *data)
>> int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
>> unsigned mmp_check_interval;
>> unsigned long last_update_time;
>> + unsigned long last_check_time;
>> unsigned long diff;
>> int retval = 0;
>> @@ -170,6 +171,7 @@ static int kmmpd(void *data)
>> memcpy(mmp->mmp_nodename, init_utsname()->nodename,
>> sizeof(mmp->mmp_nodename));
>> + last_update_time = jiffies;
I'm sorry, actually i want to init 'last_check_time' at here, I will
fix it in v2.
Thanks,
YeBin
>> while (!kthread_should_stop() && !sb_rdonly(sb)) {
>> if (!ext4_has_feature_mmp(sb)) {
>> @@ -198,17 +200,18 @@ static int kmmpd(void *data)
>> }
>> diff = jiffies - last_update_time;
>> - if (diff < mmp_update_interval * HZ)
>> + if (diff < mmp_update_interval * HZ) {
>> schedule_timeout_interruptible(mmp_update_interval *
>> HZ - diff);
>> + diff = jiffies - last_update_time;
>> + }
>> /*
>> * We need to make sure that more than mmp_check_interval
>> - * seconds have not passed since writing. If that has happened
>> - * we need to check if the MMP block is as we left it.
>> + * seconds have not passed since check. If that has happened
>> + * we need to check if the MMP block is as we write it.
>> */
>> - diff = jiffies - last_update_time;
>> - if (diff > mmp_check_interval * HZ) {
>> + if (jiffies - last_check_time > mmp_check_interval * HZ) {
>
> Before the above checking, seems last_check_time is not initialized yet.
>> struct buffer_head *bh_check = NULL;
>> struct mmp_struct *mmp_check;
>> @@ -234,6 +237,7 @@ static int kmmpd(void *data)
>> goto wait_to_exit;
>> }
>> put_bh(bh_check);
>> + last_check_time = jiffies;
>> }
>> /*
>
> Thanks,
> Guoqing
> .
>