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

drivers/mtd/ubi/build.c

@@ -1298,6 +1298,15 @@ static int __init ubi_init(void)
 		}
 	}
 
+	err = ubiblock_init();
+	if (err) {
+		ubi_err("block: cannot initialize, error %d", err);
+
+		/* See comment above re-ubi_is_module(). */
+		if (ubi_is_module())
+			goto out_detach;
+	}
+
 	return 0;
 
 out_detach:
@@ -1326,6 +1335,8 @@ static void __exit ubi_exit(void)
 {
 	int i;
 
+	ubiblock_exit();
+
 	for (i = 0; i < UBI_MAX_DEVICES; i++)
 		if (ubi_devices[i]) {
 			mutex_lock(&ubi_devices_mutex);

drivers/mtd/ubi/cdev.c

@@ -561,6 +561,26 @@ static long vol_cdev_ioctl(struct file *file, unsigned int cmd,
 		break;
 	}
 
+	/* Create a R/O block device on top of the UBI volume */
+	case UBI_IOCVOLCRBLK:
+	{
+		struct ubi_volume_info vi;
+
+		ubi_get_volume_info(desc, &vi);
+		err = ubiblock_create(&vi);
+		break;
+	}
+
+	/* Remove the R/O block device */
+	case UBI_IOCVOLRMBLK:
+	{
+		struct ubi_volume_info vi;
+
+		ubi_get_volume_info(desc, &vi);
+		err = ubiblock_remove(&vi);
+		break;
+	}
+
 	default:
 		err = -ENOTTY;
 		break;

drivers/mtd/ubi/ubi.h

@@ -864,6 +864,26 @@ int ubi_update_fastmap(struct ubi_device *ubi);
 int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
 		     int fm_anchor);
 
+/* block.c */
+#ifdef CONFIG_MTD_UBI_BLOCK
+int ubiblock_init(void);
+void ubiblock_exit(void);
+int ubiblock_create(struct ubi_volume_info *vi);
+int ubiblock_remove(struct ubi_volume_info *vi);
+#else
+static inline int ubiblock_init(void) { return 0; }
+static inline void ubiblock_exit(void) {}
+static inline int ubiblock_create(struct ubi_volume_info *vi)
+{
+	return -ENOSYS;
+}
+static inline int ubiblock_remove(struct ubi_volume_info *vi)
+{
+	return -ENOSYS;
+}
+#endif
+
+
 /*
  * ubi_rb_for_each_entry - walk an RB-tree.
  * @rb: a pointer to type 'struct rb_node' to use as a loop counter

include/uapi/mtd/ubi-user.h

@@ -134,6 +134,16 @@
  * 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.
  */
 
 /*
@@ -191,6 +201,10 @@
 /* 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
@@ -420,4 +434,12 @@ struct ubi_set_vol_prop_req {
 	__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__ */