f2fs: multidevice: add stats in debugfs

This patch adds per-device stats in debugfs, the examples
are as below:

mkfs.f2fs -f -c /dev/vdc /dev/vdb
mount /dev/vdb /mnt/f2fs/
cat /sys/kernel/debug/f2fs/status

Multidevice stats:
[seg: inuse dirty full free prefree]
#0 5 0 0 4007 0
#1 1 0 0 8191 0

mkfs.f2fs -f -s 2 -c /dev/vdc /dev/vdb
mount /dev/vdb /mnt/f2fs
cat /sys/kernel/debug/f2fs/status

Multidevice stats:
[seg: inuse dirty full free prefree] [sec: inuse dirty full free prefree]
#0 5 0 0 4005 0 5 0 0 2000 0
#1 1 0 0 8191 0 1 0 0 4095 0

Signed-off-by: Chao Yu <[e-mail]>
Signed-off-by: Jaegeuk Kim <[e-mail]>

fs/f2fs/debug.c

···
 }
 
 #ifdef CONFIG_DEBUG_FS
+static void update_multidevice_stats(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_stat_info *si = F2FS_STAT(sbi);
+	struct f2fs_dev_stats *dev_stats = si->dev_stats;
+	int i, j;
+
+	if (!f2fs_is_multi_device(sbi))
+		return;
+
+	memset(dev_stats, 0, sizeof(struct f2fs_dev_stats) * sbi->s_ndevs);
+	for (i = 0; i < sbi->s_ndevs; i++) {
+		unsigned int start_segno, end_segno;
+		block_t start_blk, end_blk;
+
+		if (i == 0) {
+			start_blk = MAIN_BLKADDR(sbi);
+			end_blk = FDEV(i).end_blk + 1 - SEG0_BLKADDR(sbi);
+		} else {
+			start_blk = FDEV(i).start_blk;
+			end_blk = FDEV(i).end_blk + 1;
+		}
+
+		start_segno = GET_SEGNO(sbi, start_blk);
+		end_segno = GET_SEGNO(sbi, end_blk);
+
+		for (j = start_segno; j < end_segno; j++) {
+			unsigned int seg_blks, sec_blks;
+
+			seg_blks = get_seg_entry(sbi, j)->valid_blocks;
+
+			/* update segment stats */
+			if (IS_CURSEG(sbi, j))
+				dev_stats[i].devstats[0][DEVSTAT_INUSE]++;
+			else if (seg_blks == BLKS_PER_SEG(sbi))
+				dev_stats[i].devstats[0][DEVSTAT_FULL]++;
+			else if (seg_blks != 0)
+				dev_stats[i].devstats[0][DEVSTAT_DIRTY]++;
+			else if (!test_bit(j, FREE_I(sbi)->free_segmap))
+				dev_stats[i].devstats[0][DEVSTAT_FREE]++;
+			else
+				dev_stats[i].devstats[0][DEVSTAT_PREFREE]++;
+
+			if (!__is_large_section(sbi) ||
+				(j % SEGS_PER_SEC(sbi)) != 0)
+				continue;
+
+			sec_blks = get_sec_entry(sbi, j)->valid_blocks;
+
+			/* update section stats */
+			if (IS_CURSEC(sbi, GET_SEC_FROM_SEG(sbi, j)))
+				dev_stats[i].devstats[1][DEVSTAT_INUSE]++;
+			else if (sec_blks == BLKS_PER_SEC(sbi))
+				dev_stats[i].devstats[1][DEVSTAT_FULL]++;
+			else if (sec_blks != 0)
+				dev_stats[i].devstats[1][DEVSTAT_DIRTY]++;
+			else if (!test_bit(GET_SEC_FROM_SEG(sbi, j),
+					FREE_I(sbi)->free_secmap))
+				dev_stats[i].devstats[1][DEVSTAT_FREE]++;
+			else
+				dev_stats[i].devstats[1][DEVSTAT_PREFREE]++;
+		}
+	}
+}
+
 static void update_general_status(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_stat_info *si = F2FS_STAT(sbi);
···
 			si->dirty_seg[type]++;
 		si->valid_blks[type] += blks;
 	}
+
+	update_multidevice_stats(sbi);
 
 	for (i = 0; i < MAX_CALL_TYPE; i++)
 		si->cp_call_count[i] = atomic_read(&sbi->cp_call_count[i]);
···
 			   si->dirty_count);
 		seq_printf(s, "  - Prefree: %d\n  - Free: %d (%d)\n\n",
 			   si->prefree_count, si->free_segs, si->free_secs);
+		if (f2fs_is_multi_device(sbi)) {
+			seq_puts(s, "Multidevice stats:\n");
+			seq_printf(s, "  [seg:   %8s %8s %8s %8s %8s]",
+					"inuse", "dirty", "full", "free", "prefree");
+			if (__is_large_section(sbi))
+				seq_printf(s, " [sec:   %8s %8s %8s %8s %8s]\n",
+					"inuse", "dirty", "full", "free", "prefree");
+			else
+				seq_puts(s, "\n");
+
+			for (i = 0; i < sbi->s_ndevs; i++) {
+				seq_printf(s, "  #%-2d     %8u %8u %8u %8u %8u", i,
+					si->dev_stats[i].devstats[0][DEVSTAT_INUSE],
+					si->dev_stats[i].devstats[0][DEVSTAT_DIRTY],
+					si->dev_stats[i].devstats[0][DEVSTAT_FULL],
+					si->dev_stats[i].devstats[0][DEVSTAT_FREE],
+					si->dev_stats[i].devstats[0][DEVSTAT_PREFREE]);
+				if (!__is_large_section(sbi)) {
+					seq_puts(s, "\n");
+					continue;
+				}
+				seq_printf(s, "          %8u %8u %8u %8u %8u\n",
+					si->dev_stats[i].devstats[1][DEVSTAT_INUSE],
+					si->dev_stats[i].devstats[1][DEVSTAT_DIRTY],
+					si->dev_stats[i].devstats[1][DEVSTAT_FULL],
+					si->dev_stats[i].devstats[1][DEVSTAT_FREE],
+					si->dev_stats[i].devstats[1][DEVSTAT_PREFREE]);
+			}
+			seq_puts(s, "\n");
+		}
 		seq_printf(s, "CP calls: %d (BG: %d)\n",
 			   si->cp_call_count[TOTAL_CALL],
 			   si->cp_call_count[BACKGROUND]);
···
 {
 	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
 	struct f2fs_stat_info *si;
+	struct f2fs_dev_stats *dev_stats;
 	unsigned long flags;
 	int i;
 
 	si = f2fs_kzalloc(sbi, sizeof(struct f2fs_stat_info), GFP_KERNEL);
 	if (!si)
 		return -ENOMEM;
+
+	dev_stats = f2fs_kzalloc(sbi, sizeof(struct f2fs_dev_stats) *
+						sbi->s_ndevs, GFP_KERNEL);
+	if (!dev_stats) {
+		kfree(si);
+		return -ENOMEM;
+	}
+
+	si->dev_stats = dev_stats;
 
 	si->all_area_segs = le32_to_cpu(raw_super->segment_count);
 	si->sit_area_segs = le32_to_cpu(raw_super->segment_count_sit);
···
 	list_del(&si->stat_list);
 	raw_spin_unlock_irqrestore(&f2fs_stat_lock, flags);
 
+	kfree(si->dev_stats);
 	kfree(si);
 }
 

fs/f2fs/f2fs.h

···
  * debug.c
  */
 #ifdef CONFIG_F2FS_STAT_FS
+enum {
+	DEVSTAT_INUSE,
+	DEVSTAT_DIRTY,
+	DEVSTAT_FULL,
+	DEVSTAT_FREE,
+	DEVSTAT_PREFREE,
+	DEVSTAT_MAX,
+};
+
+struct f2fs_dev_stats {
+	unsigned int devstats[2][DEVSTAT_MAX];		/* 0: segs, 1: secs */
+};
+
 struct f2fs_stat_info {
 	struct list_head stat_list;
 	struct f2fs_sb_info *sbi;
···
 	unsigned int block_count[2];
 	unsigned int inplace_count;
 	unsigned long long base_mem, cache_mem, page_mem;
+	struct f2fs_dev_stats *dev_stats;
 };
 
 static inline struct f2fs_stat_info *F2FS_STAT(struct f2fs_sb_info *sbi)