init_rwsem(&ubi->work_sem);
        ubi->max_ec = ai->max_ec;
        INIT_LIST_HEAD(&ubi->works);
-#ifdef CONFIG_MTD_UBI_FASTMAP
-       INIT_WORK(&ubi->fm_work, update_fastmap_work_fn);
-#endif
 
        sprintf(ubi->bgt_name, UBI_BGT_NAME_PATTERN, ubi->ubi_num);
 
                ubi_assert(ubi->good_peb_count == found_pebs);
 
        reserved_pebs = WL_RESERVED_PEBS;
-#ifdef CONFIG_MTD_UBI_FASTMAP
-       /* Reserve enough LEBs to store two fastmaps. */
-       reserved_pebs += (ubi->fm_size / ubi->leb_size) * 2;
-#endif
+       ubi_fastmap_init(ubi, &reserved_pebs);
 
        if (ubi->avail_pebs < reserved_pebs) {
                ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)",
 
 static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root);
 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
 static void ubi_fastmap_close(struct ubi_device *ubi);
+static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count)
+{
+       /* Reserve enough LEBs to store two fastmaps. */
+       *count += (ubi->fm_size / ubi->leb_size) * 2;
+       INIT_WORK(&ubi->fm_work, update_fastmap_work_fn);
+}
 #else /* !CONFIG_MTD_UBI_FASTMAP */
 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
 static inline int is_fm_block(struct ubi_device *ubi, int pnum)
        return 0;
 }
 static inline void ubi_fastmap_close(struct ubi_device *ubi) { }
+static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count) { }
 #endif /* CONFIG_MTD_UBI_FASTMAP */
 #endif /* UBI_WL_H */