f2fs: introduce sb_status sysfs node

Introduce /sys/fs/f2fs/<devname>/stat/sb_status to show superblock
status in real time as a hexadecimal value.

value           sb status macro                 description

0x1             SBI_IS_DIRTY,                   /* dirty flag for checkpoint */
0x2             SBI_IS_CLOSE,                   /* specify unmounting */
0x4             SBI_NEED_FSCK,                  /* need fsck.f2fs to fix */
0x8             SBI_POR_DOING,                  /* recovery is doing or not */
0x10            SBI_NEED_SB_WRITE,              /* need to recover superblock */
0x20            SBI_NEED_CP,                    /* need to checkpoint */
0x40            SBI_IS_SHUTDOWN,                /* shutdown by ioctl */
0x80            SBI_IS_RECOVERED,               /* recovered orphan/data */
0x100           SBI_CP_DISABLED,                /* CP was disabled last mount */
0x200           SBI_CP_DISABLED_QUICK,          /* CP was disabled quickly */
0x400           SBI_QUOTA_NEED_FLUSH,           /* need to flush quota info in CP */
0x800           SBI_QUOTA_SKIP_FLUSH,           /* skip flushing quota in current CP */
0x1000          SBI_QUOTA_NEED_REPAIR,          /* quota file may be corrupted */
0x2000          SBI_IS_RESIZEFS,                /* resizefs is in process */
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -377,3 +377,26 @@ Description:	This gives a control to limit the bio size in f2fs.
 		Default is zero, which will follow underlying block layer limit,
 		whereas, if it has a certain bytes value, f2fs won't submit a
 		bio larger than that size.
+
+What:		/sys/fs/f2fs/<disk>/stat/sb_status
+Date:		December 2020
+Contact:	"Chao Yu" <yuchao0@huawei.com>
+Description:	Show status of f2fs superblock in real time.
+
+		====== ===================== =================================
+		value  sb status macro       description
+		0x1    SBI_IS_DIRTY          dirty flag for checkpoint
+		0x2    SBI_IS_CLOSE          specify unmounting
+		0x4    SBI_NEED_FSCK         need fsck.f2fs to fix
+		0x8    SBI_POR_DOING         recovery is doing or not
+		0x10   SBI_NEED_SB_WRITE     need to recover superblock
+		0x20   SBI_NEED_CP           need to checkpoint
+		0x40   SBI_IS_SHUTDOWN       shutdown by ioctl
+		0x80   SBI_IS_RECOVERED      recovered orphan/data
+		0x100  SBI_CP_DISABLED       CP was disabled last mount
+		0x200  SBI_CP_DISABLED_QUICK CP was disabled quickly
+		0x400  SBI_QUOTA_NEED_FLUSH  need to flush quota info in CP
+		0x800  SBI_QUOTA_SKIP_FLUSH  skip flushing quota in current CP
+		0x1000 SBI_QUOTA_NEED_REPAIR quota file may be corrupted
+		0x2000 SBI_IS_RESIZEFS       resizefs is in process
+		====== ===================== =================================

fs/f2fs/sysfs.c

@@ -96,6 +96,12 @@ static ssize_t lifetime_write_kbytes_show(struct f2fs_attr *a,
 				sbi->sectors_written_start) >> 1)));
 }
 
+static ssize_t sb_status_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	return sprintf(buf, "%lx\n", sbi->s_flag);
+}
+
 static ssize_t features_show(struct f2fs_attr *a,
 		struct f2fs_sb_info *sbi, char *buf)
 {
@@ -702,7 +708,9 @@ static struct attribute *f2fs_feat_attrs[] = {
 };
 ATTRIBUTE_GROUPS(f2fs_feat);
 
+F2FS_GENERAL_RO_ATTR(sb_status);
 static struct attribute *f2fs_stat_attrs[] = {
+	ATTR_LIST(sb_status),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs_stat);