ocfs2: add last unlock times in locking_state

ocfs2 file system uses locking_state file under debugfs to dump each
ocfs2 file system's dlm lock resources, but the dlm lock resources in
memory are becoming more and more after the files were touched by the
user.  it will become a bit difficult to analyze these dlm lock resource
records in locking_state file by the upper scripts, though some files
are not active for now, which were accessed long time ago.

Then, I'd like to add last pr/ex unlock times in locking_state file for
each dlm lock resource record, the the upper scripts can use last unlock
time to filter inactive dlm lock resource record.

Link: http://lkml.kernel.org/r/20190611015414.27754-1-ghe@suse.com
Signed-off-by: Gang He <ghe@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/dlmglue.c

@@ -460,6 +460,8 @@ static void ocfs2_update_lock_stats(struct ocfs2_lock_res *res, int level,
 
 	if (ret)
 		stats->ls_fail++;
+
+	stats->ls_last = ktime_to_us(ktime_get_real());
 }
 
 static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
@@ -3079,8 +3081,10 @@ static void *ocfs2_dlm_seq_next(struct seq_file *m, void *v, loff_t *pos)
  *	- Lock stats printed
  * New in version 3
  *	- Max time in lock stats is in usecs (instead of nsecs)
+ * New in version 4
+ *	- Add last pr/ex unlock times in usecs
  */
-#define OCFS2_DLM_DEBUG_STR_VERSION 3
+#define OCFS2_DLM_DEBUG_STR_VERSION 4
 static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
 {
 	int i;
@@ -3131,6 +3135,8 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
 # define lock_max_prmode(_l)		((_l)->l_lock_prmode.ls_max)
 # define lock_max_exmode(_l)		((_l)->l_lock_exmode.ls_max)
 # define lock_refresh(_l)		((_l)->l_lock_refresh)
+# define lock_last_prmode(_l)		((_l)->l_lock_prmode.ls_last)
+# define lock_last_exmode(_l)		((_l)->l_lock_exmode.ls_last)
 #else
 # define lock_num_prmode(_l)		(0)
 # define lock_num_exmode(_l)		(0)
@@ -3141,6 +3147,8 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
 # define lock_max_prmode(_l)		(0)
 # define lock_max_exmode(_l)		(0)
 # define lock_refresh(_l)		(0)
+# define lock_last_prmode(_l)		(0ULL)
+# define lock_last_exmode(_l)		(0ULL)
 #endif
 	/* The following seq_print was added in version 2 of this output */
 	seq_printf(m, "%u\t"
@@ -3151,7 +3159,9 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
 		   "%llu\t"
 		   "%u\t"
 		   "%u\t"
-		   "%u\t",
+		   "%u\t"
+		   "%llu\t"
+		   "%llu\t",
 		   lock_num_prmode(lockres),
 		   lock_num_exmode(lockres),
 		   lock_num_prmode_failed(lockres),
@@ -3160,7 +3170,9 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
 		   lock_total_exmode(lockres),
 		   lock_max_prmode(lockres),
 		   lock_max_exmode(lockres),
-		   lock_refresh(lockres));
+		   lock_refresh(lockres),
+		   lock_last_prmode(lockres),
+		   lock_last_exmode(lockres));
 
 	/* End the line */
 	seq_printf(m, "\n");

fs/ocfs2/ocfs2.h

@@ -150,6 +150,7 @@ struct ocfs2_lock_stats {
 
 	/* Storing max wait in usecs saves 24 bytes per inode */
 	u32		ls_max;		/* Max wait in USEC */
+	u64		ls_last;	/* Last unlock time in USEC */
 };
 #endif