zonefs: add support for FS_IOC_GETFSSYSFSPATH

FS_IOC_GETFSSYSFSPATH ioctl expects sysfs sub-path of a filesystem, the
format can be "$FSTYP/$SYSFS_IDENTIFIER" under /sys/fs, it can helps to
standardizes exporting sysfs datas across filesystems.

This patch wires up FS_IOC_GETFSSYSFSPATH for zonefs, it will output
"zonefs/<dev>".

Signed-off-by: Liao Chen <liaochen4@huawei.com>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>

fs/zonefs/sysfs.c

@@ -92,6 +92,7 @@ int zonefs_sysfs_register(struct super_block *sb)
 	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
 	int ret;
 
+	super_set_sysfs_name_id(sb);
 	init_completion(&sbi->s_kobj_unregister);
 	ret = kobject_init_and_add(&sbi->s_kobj, &zonefs_sb_ktype,
 				   zonefs_sysfs_root, "%s", sb->s_id);