ocfs2: use time64_t to represent orphan scan times

struct timespec is not y2038 safe.  Use time64_t which is y2038 safe to
represent orphan scan times.  time64_t is sufficient here as only the
seconds delta times are relevant.

Also use appropriate time functions that return time in time64_t format.
Time functions now return monotonic time instead of real time as only
delta scan times are relevant and these values are not persistent across
reboots.

The format string for the debug print is still using long as this is
only the time elapsed since the last scan and long is sufficient to
represent this value.

Link: http://lkml.kernel.org/r/1475365138-20567-1-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/journal.c

@@ -1947,7 +1947,7 @@ static void ocfs2_queue_orphan_scan(struct ocfs2_super *osb)
 	 */
 	seqno++;
 	os->os_count++;
-	os->os_scantime = CURRENT_TIME;
+	os->os_scantime = ktime_get_seconds();
 unlock:
 	ocfs2_orphan_scan_unlock(osb, seqno);
 out:
@@ -2004,7 +2004,7 @@ void ocfs2_orphan_scan_start(struct ocfs2_super *osb)
 	struct ocfs2_orphan_scan *os;
 
 	os = &osb->osb_orphan_scan;
-	os->os_scantime = CURRENT_TIME;
+	os->os_scantime = ktime_get_seconds();
 	if (ocfs2_is_hard_readonly(osb) || ocfs2_mount_local(osb))
 		atomic_set(&os->os_state, ORPHAN_SCAN_INACTIVE);
 	else {

fs/ocfs2/ocfs2.h

@@ -224,7 +224,7 @@ struct ocfs2_orphan_scan {
 	struct ocfs2_super 	*os_osb;
 	struct ocfs2_lock_res 	os_lockres;     /* lock to synchronize scans */
 	struct delayed_work 	os_orphan_scan_work;
-	struct timespec		os_scantime;  /* time this node ran the scan */
+	time64_t		os_scantime;  /* time this node ran the scan */
 	u32			os_count;      /* tracks node specific scans */
 	u32  			os_seqno;       /* tracks cluster wide scans */
 	atomic_t		os_state;              /* ACTIVE or INACTIVE */

fs/ocfs2/super.c

@@ -337,7 +337,7 @@ static int ocfs2_osb_dump(struct ocfs2_super *osb, char *buf, int len)
 		out += snprintf(buf + out, len - out, "Disabled\n");
 	else
 		out += snprintf(buf + out, len - out, "%lu seconds ago\n",
-				(get_seconds() - os->os_scantime.tv_sec));
+				(unsigned long)(ktime_get_seconds() - os->os_scantime));
 
 	out += snprintf(buf + out, len - out, "%10s => %3s  %10s\n",
 			"Slots", "Num", "RecoGen");