Merge tag 'upstream-3.15-rc1' of git://git.infradead.org/linux-ubifs

Pull ubifs updates from Artem Bityutskiy:
 "This pull request includes the 'ubiblock' driver which provides R/O
  block access to UBI volumes.  It is useful for those who want to use
  squashfs on top of raw flash devices.  UBI will provide bit-flip
  handling and wear-levelling in this case (e.g., if there are other UBI
  volumes with R/W UBIFS too).

  The driver is actually pretty small and it is part of the UBI kernel
  subsystem.  Delivered by Ezequiel Garcia, along with a piece of
  documentation on the MTD web site and the user-space tool for creating
  and removing block devices"

* tag 'upstream-3.15-rc1' of git://git.infradead.org/linux-ubifs:
  UBI: block: Remove __initdata from ubiblock_param_ops
  UBI: make UBI_IOCVOLCRBLK take a parameter for future usage
  UBI: rename block device ioctls
  UBI: block: Use ENOSYS as return value when CONFIG_UBIBLOCK=n
  UBI: block: Add CONFIG_BLOCK dependency
  UBI: block: Use 'u64' for the 64-bit dividend
  UBI: block: Mark init-only symbol as __initdata
  UBI: block: do not use term "attach"
  UBI: R/O block driver on top of UBI volumes

drivers/mtd/ubi/Kconfig

@@ -87,4 +87,20 @@ config MTD_UBI_GLUEBI
 	   work on top of UBI. Do not enable this unless you use legacy
 	   software.
 
+config MTD_UBI_BLOCK
+	bool "Read-only block devices on top of UBI volumes"
+	default n
+	depends on BLOCK
+	help
+	   This option enables read-only UBI block devices support. UBI block
+	   devices will be layered on top of UBI volumes, which means that the
+	   UBI driver will transparently handle things like bad eraseblocks and
+	   bit-flips. You can put any block-oriented file system on top of UBI
+	   volumes in read-only mode (e.g., ext4), but it is probably most
+	   practical for read-only file systems, like squashfs.
+
+	   When selected, this feature will be built in the UBI driver.
+
+	   If in doubt, say "N".
+
 endif # MTD_UBI

drivers/mtd/ubi/Makefile

@@ -3,5 +3,6 @@ obj-$(CONFIG_MTD_UBI) += ubi.o
 ubi-y += vtbl.o vmt.o upd.o build.o cdev.o kapi.o eba.o io.o wl.o attach.o
 ubi-y += misc.o debug.o
 ubi-$(CONFIG_MTD_UBI_FASTMAP) += fastmap.o
+ubi-$(CONFIG_MTD_UBI_BLOCK) += block.o
 
 obj-$(CONFIG_MTD_UBI_GLUEBI) += gluebi.o