mtd,ubi,ubifs: sync with linux v3.15

snyc with linux v3.15:

commit 1860e379875dfe7271c649058aeddffe5afd9d0d
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Jun 8 11:19:54 2014 -0700

    Linux 3.15

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Tom Rini <trini@ti.com>
diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h
index c93914a..22d9004 100644
--- a/include/mtd/ubi-user.h
+++ b/include/mtd/ubi-user.h
@@ -122,6 +122,16 @@
  * used. A pointer to a &struct ubi_set_vol_prop_req object is expected to be
  * passed. The object describes which property should be set, and to which value
  * it should be set.
+ *
+ * Block devices on UBI volumes
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * To create a R/O block device on top of an UBI volume the %UBI_IOCVOLCRBLK
+ * should be used. A pointer to a &struct ubi_blkcreate_req object is expected
+ * to be passed, which is not used and reserved for future usage.
+ *
+ * Conversely, to remove a block device the %UBI_IOCVOLRMBLK should be used,
+ * which takes no arguments.
  */
 
 /*
@@ -179,6 +189,10 @@
 /* Set an UBI volume property */
 #define UBI_IOCSETVOLPROP _IOW(UBI_VOL_IOC_MAGIC, 6, \
 			       struct ubi_set_vol_prop_req)
+/* Create a R/O block device on top of an UBI volume */
+#define UBI_IOCVOLCRBLK _IOW(UBI_VOL_IOC_MAGIC, 7, struct ubi_blkcreate_req)
+/* Remove the R/O block device */
+#define UBI_IOCVOLRMBLK _IO(UBI_VOL_IOC_MAGIC, 8)
 
 /* Maximum MTD device name length supported by UBI */
 #define MAX_UBI_MTD_NAME_LEN 127
@@ -408,4 +422,12 @@
 	__u64 value;
 }  __packed;
 
+/**
+ * struct ubi_blkcreate_req - a data structure used in block creation requests.
+ * @padding: reserved for future, not used, has to be zeroed
+ */
+struct ubi_blkcreate_req {
+	__s8  padding[128];
+}  __packed;
+
 #endif /* __UBI_USER_H__ */