f2fs: show mounted time

Let's show mounted time.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -318,3 +318,8 @@ Date:		September 2019
 Contact:	"Hridya Valsaraju" <hridya@google.com>
 Description:	Average number of valid blocks.
 		Available when CONFIG_F2FS_STAT_FS=y.
+
+What:		/sys/fs/f2fs/<disk>/mounted_time_sec
+Date:		February 2020
+Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>
+Description:	Show the mounted time in secs of this partition.

fs/f2fs/debug.c

@@ -301,6 +301,9 @@ static int stat_show(struct seq_file *s, void *v)
 			   si->ssa_area_segs, si->main_area_segs);
 		seq_printf(s, "(OverProv:%d Resv:%d)]\n\n",
 			   si->overp_segs, si->rsvd_segs);
+		seq_printf(s, "Current Time Sec: %llu / Mounted Time Sec: %llu\n\n",
+					ktime_get_boottime_seconds(),
+					SIT_I(si->sbi)->mounted_time);
 		if (test_opt(si->sbi, DISCARD))
 			seq_printf(s, "Utilization: %u%% (%u valid blocks, %u discard blocks)\n",
 				si->utilization, si->valid_count, si->discard_blks);

fs/f2fs/segment.c

@@ -4071,7 +4071,7 @@ static int build_sit_info(struct f2fs_sb_info *sbi)
 	sit_i->dirty_sentries = 0;
 	sit_i->sents_per_block = SIT_ENTRY_PER_BLOCK;
 	sit_i->elapsed_time = le64_to_cpu(sbi->ckpt->elapsed_time);
-	sit_i->mounted_time = ktime_get_real_seconds();
+	sit_i->mounted_time = ktime_get_boottime_seconds();
 	init_rwsem(&sit_i->sentry_lock);
 	return 0;
 }

fs/f2fs/segment.h

@@ -756,7 +756,7 @@ static inline unsigned long long get_mtime(struct f2fs_sb_info *sbi,
 						bool base_time)
 {
 	struct sit_info *sit_i = SIT_I(sbi);
-	time64_t diff, now = ktime_get_real_seconds();
+	time64_t diff, now = ktime_get_boottime_seconds();
 
 	if (now >= sit_i->mounted_time)
 		return sit_i->elapsed_time + now - sit_i->mounted_time;

fs/f2fs/sysfs.c

@@ -185,6 +185,12 @@ static ssize_t encoding_show(struct f2fs_attr *a,
 	return sprintf(buf, "(none)");
 }
 
+static ssize_t mounted_time_sec_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	return sprintf(buf, "%llu", SIT_I(sbi)->mounted_time);
+}
+
 #ifdef CONFIG_F2FS_STAT_FS
 static ssize_t moved_blocks_foreground_show(struct f2fs_attr *a,
 				struct f2fs_sb_info *sbi, char *buf)
@@ -544,6 +550,7 @@ F2FS_GENERAL_RO_ATTR(features);
 F2FS_GENERAL_RO_ATTR(current_reserved_blocks);
 F2FS_GENERAL_RO_ATTR(unusable);
 F2FS_GENERAL_RO_ATTR(encoding);
+F2FS_GENERAL_RO_ATTR(mounted_time_sec);
 #ifdef CONFIG_F2FS_STAT_FS
 F2FS_STAT_ATTR(STAT_INFO, f2fs_stat_info, cp_foreground_calls, cp_count);
 F2FS_STAT_ATTR(STAT_INFO, f2fs_stat_info, cp_background_calls, bg_cp_count);
@@ -621,6 +628,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(reserved_blocks),
 	ATTR_LIST(current_reserved_blocks),
 	ATTR_LIST(encoding),
+	ATTR_LIST(mounted_time_sec),
 #ifdef CONFIG_F2FS_STAT_FS
 	ATTR_LIST(cp_foreground_calls),
 	ATTR_LIST(cp_background_calls),