f2fs: introduce cp_status sysfs entry

This patch adds a new sysfs entry named cp_status, it can output
checkpoint flags in real time.
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -466,6 +466,30 @@ Description:	Show status of f2fs superblock in real time.
 		0x4000 SBI_IS_FREEZING       freefs is in process
 		====== ===================== =================================
 
+What:		/sys/fs/f2fs/<disk>/stat/cp_status
+Date:		September 2022
+Contact:	"Chao Yu" <chao.yu@oppo.com>
+Description:	Show status of f2fs checkpoint in real time.
+
+		=============================== ==============================
+		cp flag				value
+		CP_UMOUNT_FLAG			0x00000001
+		CP_ORPHAN_PRESENT_FLAG		0x00000002
+		CP_COMPACT_SUM_FLAG		0x00000004
+		CP_ERROR_FLAG			0x00000008
+		CP_FSCK_FLAG			0x00000010
+		CP_FASTBOOT_FLAG		0x00000020
+		CP_CRC_RECOVERY_FLAG		0x00000040
+		CP_NAT_BITS_FLAG		0x00000080
+		CP_TRIMMED_FLAG			0x00000100
+		CP_NOCRC_RECOVERY_FLAG		0x00000200
+		CP_LARGE_NAT_BITMAP_FLAG	0x00000400
+		CP_QUOTA_NEED_FSCK_FLAG		0x00000800
+		CP_DISABLED_FLAG		0x00001000
+		CP_DISABLED_QUICK_FLAG		0x00002000
+		CP_RESIZEFS_FLAG		0x00004000
+		=============================== ==============================
+
 What:		/sys/fs/f2fs/<disk>/ckpt_thread_ioprio
 Date:		January 2021
 Contact:	"Daeho Jeong" <daehojeong@google.com>

fs/f2fs/sysfs.c

@@ -128,6 +128,12 @@ static ssize_t sb_status_show(struct f2fs_attr *a,
 	return sprintf(buf, "%lx\n", sbi->s_flag);
 }
 
+static ssize_t cp_status_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	return sprintf(buf, "%x\n", le32_to_cpu(F2FS_CKPT(sbi)->ckpt_flags));
+}
+
 static ssize_t pending_discard_show(struct f2fs_attr *a,
 		struct f2fs_sb_info *sbi, char *buf)
 {
@@ -1029,8 +1035,10 @@ static struct attribute *f2fs_feat_attrs[] = {
 ATTRIBUTE_GROUPS(f2fs_feat);
 
 F2FS_GENERAL_RO_ATTR(sb_status);
+F2FS_GENERAL_RO_ATTR(cp_status);
 static struct attribute *f2fs_stat_attrs[] = {
 	ATTR_LIST(sb_status),
+	ATTR_LIST(cp_status),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs_stat);