JFFS2: add UBI support

This patch make JFFS2 able to work with UBI volumes via the emulated MTD
devices which are directly mapped to these volumes.

Signed-off-by: Artem Bityutskiy <dedekind@infradead.org>
diff --git a/fs/jffs2/os-linux.h b/fs/jffs2/os-linux.h
index e07a0ed..8d92e45 100644
--- a/fs/jffs2/os-linux.h
+++ b/fs/jffs2/os-linux.h
@@ -98,6 +98,9 @@
 #define jffs2_nor_wbuf_flash(c) (0)
 #define jffs2_nor_wbuf_flash_setup(c) (0)
 #define jffs2_nor_wbuf_flash_cleanup(c) do {} while (0)
+#define jffs2_ubivol(c) (0)
+#define jffs2_ubivol_setup(c) (0)
+#define jffs2_ubivol_cleanup(c) do {} while (0)
 
 #else /* NAND and/or ECC'd NOR support present */
 
@@ -133,6 +136,9 @@
 #define jffs2_dataflash(c) (c->mtd->type == MTD_DATAFLASH)
 int jffs2_dataflash_setup(struct jffs2_sb_info *c);
 void jffs2_dataflash_cleanup(struct jffs2_sb_info *c);
+#define jffs2_ubivol(c) (c->mtd->type == MTD_UBIVOLUME)
+int jffs2_ubivol_setup(struct jffs2_sb_info *c);
+void jffs2_ubivol_cleanup(struct jffs2_sb_info *c);
 
 #define jffs2_nor_wbuf_flash(c) (c->mtd->type == MTD_NORFLASH && ! (c->mtd->flags & MTD_BIT_WRITEABLE))
 int jffs2_nor_wbuf_flash_setup(struct jffs2_sb_info *c);