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 <redacted>
---
  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;
  		}
  
  		 /*