UBI: Unsorted Block Images

diff -auNrp tmp-from/include/mtd/ubi-header.h tmp-to/include/mtd/ubi-header.h
@@ -0,0 +1,360 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Authors: Artem Bityutskiy (Битюцкий Артём)
+ *          Thomas Gleixner
+ *          Frank Haverkamp
+ *          Oliver Lohmann
+ *          Andreas Arnez
+ */
+
+/*
+ * This file defines the layout of UBI headers and all the other UBI on-flash
+ * data structures. May be included by user-space.
+ */
+
+#ifndef __UBI_HEADER_H__
+#define __UBI_HEADER_H__
+
+#include <asm/byteorder.h>
+
+/* The version of UBI images supported by this implementation */
+#define UBI_VERSION 1
+
+/* The highest erase counter value supported by this implementation */
+#define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
+
+/* The initial CRC32 value used when calculating CRC checksums */
+#define UBI_CRC32_INIT 0xFFFFFFFFU
+
+/* Erase counter header magic number (ASCII "UBI#") */
+#define UBI_EC_HDR_MAGIC  0x55424923
+/* Volume identifier header magic number (ASCII "UBI!") */
+#define UBI_VID_HDR_MAGIC 0x55424921
+
+/*
+ * Volume type constants used in the volume identifier header.
+ *
+ * @UBI_VID_DYNAMIC: dynamic volume
+ * @UBI_VID_STATIC: static volume
+ */
+enum {
+	UBI_VID_DYNAMIC = 1,
+	UBI_VID_STATIC  = 2
+};
+
+/*
+ * Compatibility constants used by internal volumes.
+ *
+ * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
+ * to the flash
+ * @UBI_COMPAT_RO: attach this device in read-only mode
+ * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
+ * physical eraseblocks, don't allow the wear-leveling unit to move them
+ * @UBI_COMPAT_REJECT: reject this UBI image
+ */
+enum {
+	UBI_COMPAT_DELETE   = 1,
+	UBI_COMPAT_RO       = 2,
+	UBI_COMPAT_PRESERVE = 4,
+	UBI_COMPAT_REJECT   = 5
+};
+
+/*
+ * ubi16_t/ubi32_t/ubi64_t - 16, 32, and 64-bit integers used in UBI on-flash
+ * data structures.
+ */
+typedef struct {
+	uint16_t int16;
+} __attribute__ ((packed)) ubi16_t;
+
+typedef struct {
+	uint32_t int32;
+} __attribute__ ((packed)) ubi32_t;
+
+typedef struct {
+	uint64_t int64;
+} __attribute__ ((packed)) ubi64_t;
+
+/*
+ * In this implementation of UBI uses the big-endian format for on-flash
+ * integers. The below are the corresponding conversion macros.
+ */
+#define cpu_to_ubi16(x) ((ubi16_t){__cpu_to_be16(x)})
+#define ubi16_to_cpu(x) ((uint16_t)__be16_to_cpu((x).int16))
+
+#define cpu_to_ubi32(x) ((ubi32_t){__cpu_to_be32(x)})
+#define ubi32_to_cpu(x) ((uint32_t)__be32_to_cpu((x).int32))
+
+#define cpu_to_ubi64(x) ((ubi64_t){__cpu_to_be64(x)})
+#define ubi64_to_cpu(x) ((uint64_t)__be64_to_cpu((x).int64))
+
+/* Sizes of UBI headers */
+#define UBI_EC_HDR_SIZE  sizeof(struct ubi_ec_hdr)
+#define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
+
+/* Sizes of UBI headers without the ending CRC */
+#define UBI_EC_HDR_SIZE_CRC  (UBI_EC_HDR_SIZE  - sizeof(ubi32_t))
+#define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(ubi32_t))
+
+/**
+ * struct ubi_ec_hdr - UBI erase counter header.
+ * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
+ * @version: version of UBI implementation which is supposed to accept this
+ * UBI image
+ * @padding1: reserved for future, zeroes
+ * @ec: the erase counter
+ * @vid_hdr_offset: where the VID header starts
+ * @data_offset: where the user data start
+ * @padding2: reserved for future, zeroes
+ * @hdr_crc: erase counter header CRC checksum
+ *
+ * The erase counter header takes 64 bytes and has a plenty of unused space for
+ * future usage. The unused fields are zeroed. The @version field is used to
+ * indicate the version of UBI implementation which is supposed to be able to
+ * work with this UBI image. If @version is greater then the current UBI
+ * version, the image is rejected. This may be useful in future if something
+ * is changed radically. This field is duplicated in the volume identifier
+ * header.
+ *
+ * The @vid_hdr_offset and @data_offset fields contain the offset of the the
+ * volume identifier header and user data, relative to the beginning of the
+ * physical eraseblock. These values have to be the same for all physical
+ * eraseblocks.
+ */
+struct ubi_ec_hdr {
+	ubi32_t magic;
+	uint8_t version;
+	uint8_t padding1[3];
+	ubi64_t ec; /* Warning: the current limit is 31-bit anyway! */
+	ubi32_t vid_hdr_offset;
+	ubi32_t data_offset;
+	uint8_t padding2[36];
+	ubi32_t hdr_crc;
+} __attribute__ ((packed));
+
+/**
+ * struct ubi_vid_hdr - on-flash UBI volume identifier header.
+ * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
+ * @version: UBI implementation version which is supposed to accept this UBI
+ * image (%UBI_VERSION)
+ * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
+ * @copy_flag: if this logical eraseblock was copied from another physical
+ * eraseblock (for wear-leveling reasons)
+ * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
+ * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
+ * @vol_id: ID of this volume
+ * @lnum: logical eraseblock number
+ * @leb_ver: version of this logical eraseblock (IMPORTANT: obsolete, to be
+ * removed, kept only for not breaking older UBI users)
+ * @data_size: how many bytes of data this logical eraseblock contains
+ * @used_ebs: total number of used logical eraseblocks in this volume
+ * @data_pad: how many bytes at the end of this physical eraseblock are not
+ * used
+ * @data_crc: CRC checksum of the data stored in this logical eraseblock
+ * @padding1: reserved for future, zeroes
+ * @sqnum: sequence number
+ * @padding2: reserved for future, zeroes
+ * @hdr_crc: volume identifier header CRC checksum
+ *
+ * The @sqnum is the value of the global sequence counter at the time when this
+ * VID header was created. The global sequence counter is incremented each time
+ * UBI writes a new VID header to the flash, i.e. when it maps a logical
+ * eraseblock to a new physical eraseblock. The global sequence counter is an
+ * unsigned 64-bit integer and we assume it never overflows. The @sqnum
+ * (sequence number) is used to distinguish between older and newer versions of
+ * logical eraseblocks.
+ *
+ * There are 2 situations when there may be more then one physical eraseblock
+ * corresponding to the same logical eraseblock, i.e., having the same @vol_id
+ * and @lnum values in the volume identifier header. Suppose we have a logical
+ * eraseblock L and it is mapped to the physical eraseblock P.
+ *
+ * 1. Because UBI may erase physical eraseblocks asynchronously, the following
+ * situation is possible: L is asynchronously erased, so P is scheduled for
+ * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
+ * so P1 is written to, then an unclean reboot happens. Result - there are 2
+ * physical eraseblocks P and P1 corresponding to the same logical eraseblock
+ * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
+ * flash.
+ *
+ * 2. From time to time UBI moves logical eraseblocks to other physical
+ * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
+ * to P1, and an unclean reboot happens before P is physically erased, there
+ * are two physical eraseblocks P and P1 corresponding to L and UBI has to
+ * select one of them when the flash is attached. The @sqnum field says which
+ * PEB is the original (obviously P will have lower @sqnum) and the copy. But
+ * it is not enough to select the physical eraseblock with the higher sequence
+ * number, because the unclean reboot could have happen in the middle of the
+ * copying process, so the data in P is corrupted. It is also not enough to
+ * just select the physical eraseblock with lower sequence number, because the
+ * data there may be old (consider a case if more data was added to P1 after
+ * the copying). Moreover, the unclean reboot may happen when the erasure of P
+ * was just started, so it result in unstable P, which is "mostly" OK, but
+ * still has unstable bits.
+ *
+ * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
+ * copy. UBI also calculates data CRC when the data is moved and stores it at
+ * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
+ * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
+ * examined. If it is cleared, the situation* is simple and the newer one is
+ * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
+ * checksum is correct, this physical eraseblock is selected (P1). Otherwise
+ * the older one (P) is selected.
+ *
+ * Note, there is an obsolete @leb_ver field which was used instead of @sqnum
+ * in the past. But it is not used anymore and we keep it in order to be able
+ * to deal with old UBI images. It will be removed at some point.
+ *
+ * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
+ * Internal volumes are not seen from outside and are used for various internal
+ * UBI purposes. In this implementation there is only one internal volume - the
+ * layout volume. Internal volumes are the main mechanism of UBI extensions.
+ * For example, in future one may introduce a journal internal volume. Internal
+ * volumes have their own reserved range of IDs.
+ *
+ * The @compat field is only used for internal volumes and contains the "degree
+ * of their compatibility". It is always zero for user volumes. This field
+ * provides a mechanism to introduce UBI extensions and to be still compatible
+ * with older UBI binaries. For example, if someone introduced a journal in
+ * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
+ * journal volume.  And in this case, older UBI binaries, which know nothing
+ * about the journal volume, would just delete this volume and work perfectly
+ * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
+ * - it just ignores the Ext3fs journal.
+ *
+ * The @data_crc field contains the CRC checksum of the contents of the logical
+ * eraseblock if this is a static volume. In case of dynamic volumes, it does
+ * not contain the CRC checksum as a rule. The only exception is when the
+ * data of the physical eraseblock was moved by the wear-leveling unit, then
+ * the wear-leveling unit calculates the data CRC and stores it in the
+ * @data_crc field. And of course, the @copy_flag is %in this case.
+ *
+ * The @data_size field is used only for static volumes because UBI has to know
+ * how many bytes of data are stored in this eraseblock. For dynamic volumes,
+ * this field usually contains zero. The only exception is when the data of the
+ * physical eraseblock was moved to another physical eraseblock for
+ * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
+ * contents and uses both @data_crc and @data_size fields. In this case, the
+ * @data_size field contains data size.
+ *
+ * The @used_ebs field is used only for static volumes and indicates how many
+ * eraseblocks the data of the volume takes. For dynamic volumes this field is
+ * not used and always contains zero.
+ *
+ * The @data_pad is calculated when volumes are created using the alignment
+ * parameter. So, effectively, the @data_pad field reduces the size of logical
+ * eraseblocks of this volume. This is very handy when one uses block-oriented
+ * software (say, cramfs) on top of the UBI volume.
+ */
+struct ubi_vid_hdr {
+	ubi32_t magic;
+	uint8_t version;
+	uint8_t vol_type;
+	uint8_t copy_flag;
+	uint8_t compat;
+	ubi32_t vol_id;
+	ubi32_t lnum;
+	ubi32_t leb_ver; /* obsolete, to be removed, don't use */
+	ubi32_t data_size;
+	ubi32_t used_ebs;
+	ubi32_t data_pad;
+	ubi32_t data_crc;
+	uint8_t padding1[4];
+	ubi64_t sqnum;
+	uint8_t padding2[12];
+	ubi32_t hdr_crc;
+} __attribute__ ((packed));
+
+/* Internal UBI volumes count */
+#define UBI_INT_VOL_COUNT 1
+
+/*
+ * Starting ID of internal volumes. There is reserved room for 4096 internal
+ * volumes.
+ */
+#define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
+
+/* The layout volume contains the volume table */
+
+#define UBI_LAYOUT_VOL_ID        UBI_INTERNAL_VOL_START
+#define UBI_LAYOUT_VOLUME_EBS    2
+#define UBI_LAYOUT_VOLUME_NAME   "layout volume"
+#define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
+
+/* The maximum number of volumes per one UBI device */
+#define UBI_MAX_VOLUMES 128
+
+/* The maximum volume name length */
+#define UBI_VOL_NAME_MAX 127
+
+/* Size of the volume table record */
+#define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
+
+/* Size of the volume table record without the ending CRC */
+#define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(ubi32_t))
+
+/**
+ * struct ubi_vtbl_record - a record in the volume table.
+ * @reserved_pebs: how many physical eraseblocks are reserved for this volume
+ * @alignment: volume alignment
+ * @data_pad: how many bytes are unused at the end of the each physical
+ * eraseblock to satisfy the requested alignment
+ * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @upd_marker: if volume update was started but not finished
+ * @name_len: volume name length
+ * @name: the volume name
+ * @padding2: reserved, zeroes
+ * @crc: a CRC32 checksum of the record
+ *
+ * The volume table records are stored in the volume table, which is stored in
+ * the layout volume. The layout volume consists of 2 logical eraseblock, each
+ * of which contains a copy of the volume table (i.e., the volume table is
+ * duplicated). The volume table is an array of &struct ubi_vtbl_record
+ * objects indexed by the volume ID.
+ *
+ * If the size of the logical eraseblock is large enough to fit
+ * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
+ * records. Otherwise, it contains as many records as it can fit (i.e., size of
+ * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
+ *
+ * The @upd_marker flag is used to implement volume update. It is set to %1
+ * before update and set to %0 after the update. So if the update operation was
+ * interrupted, UBI knows that the volume is corrupted.
+ *
+ * The @alignment field is specified when the volume is created and cannot be
+ * later changed. It may be useful, for example, when a block-oriented file
+ * system works on top of UBI. The @data_pad field is calculated using the
+ * logical eraseblock size and @alignment. The alignment must be multiple to the
+ * minimal flash I/O unit. If @alignment is 1, all the available space of
+ * the physical eraseblocks is used.
+ *
+ * Empty records contain all zeroes and the CRC checksum of those zeroes.
+ */
+struct ubi_vtbl_record {
+	ubi32_t reserved_pebs;
+	ubi32_t alignment;
+	ubi32_t data_pad;
+	uint8_t vol_type;
+	uint8_t upd_marker;
+	ubi16_t name_len;
+	uint8_t name[UBI_VOL_NAME_MAX+1];
+	uint8_t padding2[24];
+	ubi32_t crc;
+} __attribute__ ((packed));
+
+#endif /* !__UBI_HEADER_H__ */

diff -auNrp tmp-from/include/mtd/ubi-user.h tmp-to/include/mtd/ubi-user.h
@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#ifndef __UBI_USER_H__
+#define __UBI_USER_H__
+
+/*
+ * UBI volume creation
+ * ~~~~~~~~~~~~~~~~~~~
+ *
+ * UBI volumes are created via the %UBI_IOCMKVOL IOCTL command of UBI character
+ * device. A &struct ubi_mkvol_req object has to be properly filled and a
+ * pointer to it has to be passed to the IOCTL.
+ *
+ * UBI volume deletion
+ * ~~~~~~~~~~~~~~~~~~~
+ *
+ * To delete a volume, the %UBI_IOCRMVOL IOCTL command of the UBI character
+ * device should be used. A pointer to the 32-bit volume ID hast to be passed
+ * to the IOCTL.
+ *
+ * UBI volume re-size
+ * ~~~~~~~~~~~~~~~~~~
+ *
+ * To re-size a volume, the %UBI_IOCRSVOL IOCTL command of the UBI character
+ * device should be used. A &struct ubi_rsvol_req object has to be properly
+ * filled and a pointer to it has to be passed to the IOCTL.
+ *
+ * UBI volume update
+ * ~~~~~~~~~~~~~~~~~
+ *
+ * Volume update should be done via the %UBI_IOCVOLUP IOCTL command of the
+ * corresponding UBI volume character device. A pointer to a 64-bit update
+ * size should be passed to the IOCTL. After then, UBI expects user to write
+ * this number of bytes to the volume character device. The update is finished
+ * when the claimed number of bytes is passed. So, the volume update sequence
+ * is something like:
+ *
+ * fd = open("/dev/my_volume");
+ * ioctl(fd, UBI_IOCVOLUP, &image_size);
+ * write(fd, buf, image_size);
+ * close(fd);
+ */
+
+/*
+ * When a new volume is created, users may either specify the volume number they
+ * want to create or to let UBI automatically assign a volume number using this
+ * constant.
+ */
+#define UBI_VOL_NUM_AUTO (-1)
+
+/* Maximum volume name length */
+#define UBI_MAX_VOLUME_NAME 127
+
+/* IOCTL commands of UBI character devices */
+
+#define UBI_IOC_MAGIC 'o'
+
+/* Create an UBI volume */
+#define UBI_IOCMKVOL _IOW(UBI_IOC_MAGIC, 0, struct ubi_mkvol_req)
+/* Remove an UBI volume */
+#define UBI_IOCRMVOL _IOW(UBI_IOC_MAGIC, 1, int32_t)
+/* Re-size an UBI volume */
+#define UBI_IOCRSVOL _IOW(UBI_IOC_MAGIC, 2, struct ubi_rsvol_req)
+
+/* IOCTL commands of UBI volume character devices */
+
+#define UBI_VOL_IOC_MAGIC 'O'
+
+/* Start UBI volume update */
+#define UBI_IOCVOLUP _IOW(UBI_VOL_IOC_MAGIC, 0, int64_t)
+/* An eraseblock erasure command, used for debugging, disabled by default */
+#define UBI_IOCEBER _IOW(UBI_VOL_IOC_MAGIC, 1, int32_t)
+
+/*
+ * UBI volume type constants.
+ *
+ * @UBI_DYNAMIC_VOLUME: dynamic volume
+ * @UBI_STATIC_VOLUME:  static volume
+ */
+enum {
+	UBI_DYNAMIC_VOLUME = 3,
+	UBI_STATIC_VOLUME = 4
+};
+
+/**
+ * struct ubi_mkvol_req - volume description data structure used in
+ * volume creation requests.
+ * @vol_id: volume number
+ * @alignment: volume alignment
+ * @bytes: volume size in bytes
+ * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @padding1: reserved for future, not used
+ * @name_len: volume name length
+ * @padding2: reserved for future, not used
+ * @name: volume name
+ *
+ * This structure is used by userspace programs when creating new volumes. The
+ * @used_bytes field is only necessary when creating static volumes.
+ *
+ * The @alignment field specifies the required alignment of the volume logical
+ * eraseblock. This means, that the size of logical eraseblocks will be aligned
+ * to this number, i.e.,
+ *	(UBI device logical eraseblock size) mod (@alignment) = 0.
+ *
+ * To put it differently, the logical eraseblock of this volume may be slightly
+ * shortened in order to make it properly aligned. The alignment has to be
+ * multiple of the flash minimal input/output unit, or %1 to utilize the entire
+ * available space of logical eraseblocks.
+ *
+ * The @alignment field may be useful, for example, when one wants to maintain
+ * a block device on top of an UBI volume. In this case, it is desirable to fit
+ * an integer number of blocks in logical eraseblocks of this UBI volume. With
+ * alignment it is possible to update this volume using plane UBI volume image
+ * BLOBs, without caring about how to properly align them.
+ */
+struct ubi_mkvol_req {
+	int32_t vol_id;
+	int32_t alignment;
+	int64_t bytes;
+	int8_t vol_type;
+	int8_t padding1;
+	int16_t name_len;
+	int8_t padding2[4];
+	char name[UBI_MAX_VOLUME_NAME+1];
+} __attribute__ ((packed));
+
+/**
+ * struct ubi_rsvol_req - a data structure used in volume re-size requests.
+ * @vol_id: ID of the volume to re-size
+ * @bytes: new size of the volume in bytes
+ *
+ * Re-sizing is possible for both dynamic and static volumes. But while dynamic
+ * volumes may be re-sized arbitrarily, static volumes cannot be made to be
+ * smaller then the number of bytes they bear. To arbitrarily shrink a static
+ * volume, it must be wiped out first (by means of volume update operation with
+ * zero number of bytes).
+ */
+struct ubi_rsvol_req {
+	int64_t bytes;
+	int32_t vol_id;
+} __attribute__ ((packed));
+
+#endif /* __UBI_USER_H__ */

diff -auNrp tmp-from/include/linux/mtd/ubi.h tmp-to/include/linux/mtd/ubi.h
@@ -0,0 +1,191 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#ifndef __LINUX_UBI_H__
+#define __LINUX_UBI_H__
+
+#include <asm/ioctl.h>
+#include <linux/types.h>
+#include <mtd/ubi-user.h>
+
+/*
+ * enum ubi_data_type - UBI data type hint constants.
+ *
+ * UBI_DATA_LONGTERM: long-term data
+ * UBI_DATA_SHORTTERM: short-term data
+ * UBI_DATA_UNKNOWN: data persistence is unknown
+ *
+ * These constants are used when data is written to UBI volumes in order to
+ * help the UBI wear-leveling unit to find more appropriate physical
+ * eraseblocks.
+ */
+enum ubi_data_type {
+	UBI_DATA_LONGTERM = 1,
+	UBI_DATA_SHORTTERM,
+	UBI_DATA_UNKNOWN
+};
+
+/*
+ * enum ubi_open_mode - UBI volume open mode constants.
+ *
+ * UBI_READONLY: read-only mode
+ * UBI_READWRITE: read-write mode
+ * UBI_EXCLUSIVE: exclusive mode
+ */
+enum ubi_open_mode {
+	UBI_READONLY = 1,
+	UBI_READWRITE,
+	UBI_EXCLUSIVE
+};
+
+/**
+ * struct ubi_volume_info - UBI volume description data structure.
+ * @vol_id: volume ID
+ * @ubi_num: UBI device number this volume belongs to
+ * @size: how many physical eraseblocks are reserved for this volume
+ * @used_bytes: how many bytes of data this volume contains
+ * @used_ebs: how many physical eraseblocks of this volume actually contain any
+ * data
+ * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @corrupted: non-zero if the volume is corrupted (static volumes only)
+ * @upd_marker: non-zero if the volume has update marker set
+ * @alignment: volume alignment
+ * @usable_leb_size: how many bytes are available in logical eraseblocks of
+ * this volume
+ * @name_len: volume name length
+ * @name: volume name
+ * @cdev: UBI volume character device major and minor numbers
+ *
+ * The @corrupted flag is only relevant to static volumes and is always zero
+ * for dynamic ones. This is because UBI does not care about dynamic volume
+ * data protection and only cares about protecting static volume data.
+ *
+ * The @upd_marker flag is set if the volume update operation was interrupted.
+ * Before touching the volume data during the update operation, UBI first sets
+ * the update marker flag for this volume. If the volume update operation was
+ * further interrupted, the update marker indicates this. If the update marker
+ * is set, the contents of the volume is certainly damaged and a new volume
+ * update operation has to be started.
+ *
+ * To put it differently, @corrupted and @upd_marker fields have different
+ * semantics:
+ *     o the @corrupted flag means that this static volume is corrupted for some
+ *       reasons, but not because an interrupted volume update
+ *     o the @upd_marker field means that the volume is damaged because of an
+ *       interrupted update operation.
+ *
+ * I.e., the @corrupted flag is never set if the @upd_marker flag is set.
+ *
+ * The @used_bytes and @used_ebs fields are only really needed for static
+ * volumes and contain the number of bytes stored in this static volume and how
+ * many eraseblock this data occupies. In case of dynamic volumes, the
+ * @used_bytes field is equivalent to @size*@usable_leb_size, and the @used_ebs
+ * field is equivalent to @size.
+ *
+ * In general, logical eraseblock size is a property of the UBI device, not
+ * of the UBI volume. Indeed, the logical eraseblock size depends on the
+ * physical eraseblock size and on how much bytes UBI headers consume. But
+ * because of the volume alignment (@alignment), the usable size of logical
+ * eraseblocks if a volume may be less. The following equation is true:
+ * 	@usable_leb_size = LEB size - (LEB size mod @alignment),
+ * where LEB size is the logical eraseblock size defined by the UBI device.
+ *
+ * The alignment is multiple to the minimal flash input/output unit size or %1
+ * if all the available space is used.
+ *
+ * To put this differently, alignment may be considered is a way to change
+ * volume logical eraseblock sizes.
+ */
+struct ubi_volume_info {
+	int ubi_num;
+	int vol_id;
+	int size;
+	long long used_bytes;
+	int used_ebs;
+	int vol_type;
+	int corrupted;
+	int upd_marker;
+	int alignment;
+	int usable_leb_size;
+	int name_len;
+	const char *name;
+	dev_t cdev;
+};
+
+/**
+ * struct ubi_device_info - UBI device description data structure.
+ * @ubi_num: ubi device number
+ * @leb_size: logical eraseblock size on this UBI device
+ * @min_io_size: minimal I/O unit size
+ * @ro_mode: if this device is in read-only mode
+ * @cdev: UBI character device major and minor numbers
+ *
+ * Note, @leb_size is the logical eraseblock size offered by the UBI device.
+ * Volumes of this UBI device may have smaller logical eraseblock size if their
+ * alignment is not equivalent to %1.
+ */
+struct ubi_device_info {
+	int ubi_num;
+	int leb_size;
+	int min_io_size;
+	int ro_mode;
+	dev_t cdev;
+};
+
+/* UBI descriptor given to users when they open UBI volumes */
+struct ubi_volume_desc;
+
+int ubi_get_device_info(int ubi_num, struct ubi_device_info *di);
+void ubi_get_volume_info(struct ubi_volume_desc *desc,
+			 struct ubi_volume_info *vi);
+struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode);
+struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
+					int mode);
+void ubi_close_volume(struct ubi_volume_desc *desc);
+int ubi_eraseblock_read(struct ubi_volume_desc *desc, int lnum, char *buf,
+			int offset, int len, int check);
+int ubi_eraseblock_write(struct ubi_volume_desc *desc, int lnum,
+			 const void *buf, int offset, int len, int dtype);
+int ubi_eraseblock_erase(struct ubi_volume_desc *desc, int lnum);
+int ubi_eraseblock_unmap(struct ubi_volume_desc *desc, int lnum);
+int ubi_eraseblock_is_mapped(struct ubi_volume_desc *desc, int lnum);
+
+/*
+ * This function is the same as the 'ubi_eraseblock_read()' function, but it
+ * does not provide the checking capability.
+ */
+static inline int ubi_read(struct ubi_volume_desc *desc, int lnum, char *buf,
+			   int offset, int len)
+{
+	return ubi_eraseblock_read(desc, lnum, buf, offset, len, 0);
+}
+
+/*
+ * This function is the same as the 'ubi_eraseblock_write()' functions, but it
+ * does not have the data type argument.
+ */
+static inline int ubi_write(struct ubi_volume_desc *desc, int lnum,
+			    const void *buf, int offset, int len)
+{
+	return ubi_eraseblock_write(desc, lnum, buf, offset, len,
+				    UBI_DATA_UNKNOWN);
+}
+
+#endif /* !__LINUX_UBI_H__ */

diff -auNrp tmp-from/drivers/mtd/ubi/ubi.h tmp-to/drivers/mtd/ubi/ubi.h
@@ -0,0 +1,560 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2006, 2007
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#ifndef __UBI_UBI_H__
+#define __UBI_UBI_H__
+
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/mutex.h>
+#include <linux/rwsem.h>
+#include <linux/spinlock.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/string.h>
+#include <linux/mtd/mtd.h>
+
+#include <mtd/ubi-header.h>
+#include <linux/mtd/ubi.h>
+
+#include "scan.h"
+#include "debug.h"
+
+/* Maximum number of supported UBI devices */
+#define UBI_MAX_DEVICES 32
+
+/* UBI name used for character devices, sysfs, etc */
+#define UBI_NAME_STR "ubi"
+
+/* Normal UBI messages */
+#define ubi_msg(fmt, ...) printk(KERN_NOTICE "UBI: " fmt "\n", ##__VA_ARGS__)
+/* UBI warning messages */
+#define ubi_warn(fmt, ...) printk(KERN_WARNING "UBI warning: %s: " fmt "\n", \
+				  __FUNCTION__, ##__VA_ARGS__)
+/* UBI error messages */
+#define ubi_err(fmt, ...) printk(KERN_ERR "UBI error: %s: " fmt "\n", \
+				 __FUNCTION__, ##__VA_ARGS__)
+
+/* Lowest number PEBs reserved for bad PEB handling */
+#define MIN_RESEVED_PEBS 2
+
+/* Background thread name pattern */
+#define UBI_BGT_NAME_PATTERN "ubi_bgt%dd"
+
+/* This marker in the EBA table means that the LEB is um-mapped */
+#define UBI_LEB_UNMAPPED -1
+
+/*
+ * In case of errors, UBI tries to repeat the operation several times before
+ * returning error. The below constant defines how many times UBI re-tries.
+ */
+#define UBI_IO_RETRIES 3
+
+/*
+ * Error codes returned by the I/O unit.
+ *
+ * UBI_IO_PEB_EMPTY: the physical eraseblock is empty, i.e. it contains only
+ * 0xFF bytes
+ * UBI_IO_PEB_FREE: the physical eraseblock is free, i.e. it contains only a
+ * valid erase counter header, and the rest are %0xFF bytes
+ * UBI_IO_BAD_EC_HDR: the erase counter header is corrupted (bad magic or CRC)
+ * UBI_IO_BAD_VID_HDR: the volume identifier header is corrupted (bad magic or
+ * CRC)
+ * UBI_IO_BITFLIPS: bit-flips were detected and corrected
+ */
+enum {
+	UBI_IO_PEB_EMPTY = 1,
+	UBI_IO_PEB_FREE,
+	UBI_IO_BAD_EC_HDR,
+	UBI_IO_BAD_VID_HDR,
+	UBI_IO_BITFLIPS
+};
+
+extern int ubi_devices_cnt;
+extern struct ubi_device *ubi_devices[];
+
+struct ubi_volume_desc;
+
+/**
+ * struct ubi_volume - UBI volume description data structure.
+ * @dev: device object to make use of the the Linux device model
+ * @cdev: character device object to create character device
+ * @ubi: reference to the UBI device description object
+ * @vol_id: volume ID
+ * @readers: number of users holding this volume in read-only mode
+ * @writers: number of users holding this volume in read-write mode
+ * @exclusive: whether somebody holds this volume in exclusive mode
+ * @removed: if the volume was removed
+ * @checked: if this static volume was checked
+ *
+ * @reserved_pebs: how many physical eraseblocks are reserved for this volume
+ * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @usable_leb_size: logical eraseblock size without padding
+ * @used_ebs: how many logical eraseblocks in this volume contain data
+ * @last_eb_bytes: how many bytes are stored in the last logical eraseblock
+ * @used_bytes: how many bytes of data this volume contains
+ * @upd_marker: non-zero if the update marker is set for this volume
+ * @corrupted: non-zero if the volume is corrupted (static volumes only)
+ * @alignment: volume alignment
+ * @data_pad: how many bytes are not used at the end of physical eraseblocks to
+ * satisfy the requested alignment
+ * @name_len: volume name length
+ * @name: volume name
+ *
+ * @updating: whether the volume is being updated
+ * @upd_ebs: how many eraseblocks are expected to be updated
+ * @upd_bytes: how many bytes are expected to be received
+ * @upd_received: how many update bytes were already received
+ * @upd_buf: update buffer which is used to collect update data
+ *
+ * @eba_tbl: EBA table of this volume (LEB->PEB mapping)
+ *
+ * @gluebi_desc: gluebi UBI volume descriptor
+ * @gluebi_refcount: reference count of the gluebi MTD device
+ * @gluebi_mtd: MTD device description object of the gluebi MTD device
+ *
+ * The @corrupted field indicates that the volume's contents is corrupted.
+ * Since UBI protects only static volumes, this field is not relevant to
+ * dynamic volumes - it is user's responsibility to assure their data
+ * integrity.
+ *
+ * The @upd_marker flag indicates that this volume is either being updated at
+ * the moment or is damaged because of an unclean reboot.
+ */
+struct ubi_volume {
+	struct device dev;
+	struct cdev cdev;
+	struct ubi_device *ubi;
+	int vol_id;
+	int readers;
+	int writers;
+	int exclusive;
+	int removed;
+	int checked;
+
+	int reserved_pebs;
+	int vol_type;
+	int usable_leb_size;
+	int used_ebs;
+	int last_eb_bytes;
+	long long used_bytes;
+	int upd_marker;
+	int corrupted;
+	int alignment;
+	int data_pad;
+	int name_len;
+	char name[UBI_VOL_NAME_MAX+1];
+
+	int updating;
+	int upd_ebs;
+	long long upd_bytes;
+	long long upd_received;
+	void *upd_buf;
+
+	int *eba_tbl;
+
+#ifdef CONFIG_MTD_UBI_GLUEBI
+	/* Gluebi-related stuff may be compiled out */
+	struct ubi_volume_desc *gluebi_desc;
+	int gluebi_refcount;
+	struct mtd_info gluebi_mtd;
+#endif
+};
+
+/**
+ * struct ubi_volume_desc - descriptor of the UBI volume returned when it is
+ * opened.
+ * @vol: reference to the corresponding volume description object
+ * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, or %UBI_EXCLUSIVE)
+ */
+struct ubi_volume_desc {
+	struct ubi_volume *vol;
+	int mode;
+};
+
+struct ubi_wl_entry;
+
+/**
+ * struct ubi_device - UBI device description structure
+ * @dev: class device object to use the the Linux device model
+ * @cdev: character device object to create character device
+ * @ubi_num: UBI device number
+ * @ubi_name: UBI device name
+ * @major: character device major number
+ * @vol_count: number of volumes in this UBI device
+ * @volumes: volumes of this UBI device
+ * @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,
+ * @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count, @vol->readers,
+ * @vol->writers, @vol->exclusive, @vol->removed, @vol->mapping and
+ * @vol->eba_tbl.
+ *
+ * @rsvd_pebs: count of reserved physical eraseblocks
+ * @avail_pebs: count of available physical eraseblocks
+ * @beb_rsvd_pebs: how many physical eraseblocks are reserved for bad PEB
+ * handling
+ * @beb_rsvd_level: normal level of PEBs reserved for bad PEB handling
+ *
+ * @vtbl_slots: how many slots are available in the volume table
+ * @vtbl_size: size of the volume table in bytes
+ * @vtbl: in-RAM volume table copy
+ *
+ * @max_ec: current highest erase counter value
+ * @mean_ec: current mean erase counter value
+ *
+ * global_sqnum: global sequence number
+ * @ltree_lock: protects the lock tree and @global_sqnum
+ * @ltree: the lock tree
+ * @vtbl_mutex: protects on-flash volume table
+ *
+ * @used: RB-tree of used physical eraseblocks
+ * @free: RB-tree of free physical eraseblocks
+ * @scrub: RB-tree of physical eraseblocks which need scrubbing
+ * @prot: protection trees
+ * @prot.pnum: protection tree indexed by physical eraseblock numbers
+ * @prot.aec: protection tree indexed by absolute erase counter value
+ * @wl_lock: protects the @used, @free, @prot, @lookuptbl, @abs_ec, @move_from,
+ * @move_to, @move_to_put @erase_pending, @wl_scheduled, and @works
+ * fields
+ * @wl_scheduled: non-zero if the wear-leveling was scheduled
+ * @lookuptbl: a table to quickly find a &struct ubi_wl_entry object for any
+ * physical eraseblock
+ * @abs_ec: absolute erase counter
+ * @move_from: physical eraseblock from where the data is being moved
+ * @move_to: physical eraseblock where the data is being moved to
+ * @move_from_put: if the "from" PEB was put
+ * @move_to_put: if the "to" PEB was put
+ * @works: list of pending works
+ * @works_count: count of pending works
+ * @bgt_thread: background thread description object
+ * @thread_enabled: if the background thread is enabled
+ * @bgt_name: background thread name
+ *
+ * @flash_size: underlying MTD device size (in bytes)
+ * @peb_count: count of physical eraseblocks on the MTD device
+ * @peb_size: physical eraseblock size
+ * @bad_peb_count: count of bad physical eraseblocks
+ * @good_peb_count: count of good physical eraseblocks
+ * @min_io_size: minimal input/output unit size of the underlying MTD device
+ * @hdrs_min_io_size: minimal I/O unit size used for VID and EC headers
+ * @ro_mode: if the UBI device is in read-only mode
+ * @leb_size: logical eraseblock size
+ * @leb_start: starting offset of logical eraseblocks within physical
+ * eraseblocks
+ * @ec_hdr_alsize: size of the EC header aligned to @hdrs_min_io_size
+ * @vid_hdr_alsize: size of the VID header aligned to @hdrs_min_io_size
+ * @vid_hdr_offset: starting offset of the volume identifier header (might be
+ * unaligned)
+ * @vid_hdr_aloffset: starting offset of the VID header aligned to
+ * @hdrs_min_io_size
+ * @vid_hdr_shift: contains @vid_hdr_offset - @vid_hdr_aloffset
+ * @bad_allowed: whether the MTD device admits of bad physical eraseblocks or
+ * not
+ * @mtd: MTD device descriptor
+ */
+struct ubi_device {
+	struct cdev cdev;
+	struct device dev;
+	int ubi_num;
+	char ubi_name[sizeof(UBI_NAME_STR)+5];
+	int major;
+	int vol_count;
+	struct ubi_volume *volumes[UBI_MAX_VOLUMES+UBI_INT_VOL_COUNT];
+	spinlock_t volumes_lock;
+
+	int rsvd_pebs;
+	int avail_pebs;
+	int beb_rsvd_pebs;
+	int beb_rsvd_level;
+
+	int vtbl_slots;
+	int vtbl_size;
+	struct ubi_vtbl_record *vtbl;
+	struct mutex vtbl_mutex;
+
+	int max_ec;
+	int mean_ec;
+
+	/* EBA unit's stuff */
+	unsigned long long global_sqnum;
+	spinlock_t ltree_lock;
+	struct rb_root ltree;
+
+	/* Wear-leveling unit's stuff */
+	struct rb_root used;
+	struct rb_root free;
+	struct rb_root scrub;
+	struct {
+		struct rb_root pnum;
+		struct rb_root aec;
+	} prot;
+	spinlock_t wl_lock;
+	int wl_scheduled;
+	struct ubi_wl_entry **lookuptbl;
+	unsigned long long abs_ec;
+	struct ubi_wl_entry *move_from;
+	struct ubi_wl_entry *move_to;
+	int move_from_put;
+	int move_to_put;
+	struct list_head works;
+	int works_count;
+	struct task_struct *bgt_thread;
+	int thread_enabled;
+	char bgt_name[sizeof(UBI_BGT_NAME_PATTERN)+2];
+
+	/* I/O unit's stuff */
+	long long flash_size;
+	int peb_count;
+	int peb_size;
+	int bad_peb_count;
+	int good_peb_count;
+	int min_io_size;
+	int hdrs_min_io_size;
+	int ro_mode;
+	int leb_size;
+	int leb_start;
+	int ec_hdr_alsize;
+	int vid_hdr_alsize;
+	int vid_hdr_offset;
+	int vid_hdr_aloffset;
+	int vid_hdr_shift;
+	int bad_allowed;
+	struct mtd_info *mtd;
+};
+
+extern struct file_operations ubi_cdev_operations;
+extern struct file_operations ubi_vol_cdev_operations;
+extern struct class *ubi_class;
+
+/* vtbl.c */
+int ubi_change_vtbl_record(struct ubi_device *ubi, int idx,
+			   struct ubi_vtbl_record *vtbl_rec);
+int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_scan_info *si);
+
+/* vmt.c */
+int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req);
+int ubi_remove_volume(struct ubi_volume_desc *desc);
+int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs);
+int ubi_add_volume(struct ubi_device *ubi, int vol_id);
+void ubi_free_volume(struct ubi_device *ubi, int vol_id);
+
+/* upd.c */
+int ubi_start_update(struct ubi_device *ubi, int vol_id, long long bytes);
+int ubi_more_update_data(struct ubi_device *ubi, int vol_id,
+			 const void __user *buf, int count);
+
+/* misc.c */
+int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf, int length);
+int ubi_check_volume(struct ubi_device *ubi, int vol_id);
+void ubi_calculate_reserved(struct ubi_device *ubi);
+
+/* gluebi.c */
+#ifdef CONFIG_MTD_UBI_GLUEBI
+int ubi_create_gluebi(struct ubi_device *ubi, struct ubi_volume *vol);
+int ubi_destroy_gluebi(struct ubi_volume *vol);
+#else
+#define ubi_create_gluebi(ubi, vol) 0
+#define ubi_destroy_gluebi(vol) 0
+#endif
+
+/* eba.c */
+int ubi_eba_unmap_leb(struct ubi_device *ubi, int vol_id, int lnum);
+int ubi_eba_read_leb(struct ubi_device *ubi, int vol_id, int lnum, void *buf,
+		     int offset, int len, int check);
+int ubi_eba_write_leb(struct ubi_device *ubi, int vol_id, int lnum,
+		      const void *buf, int offset, int len,
+		      enum ubi_data_type dtype);
+int ubi_eba_write_leb_st(struct ubi_device *ubi, int vol_id, int lnum,
+			 const void *buf, int len, enum ubi_data_type dtype,
+			 int used_ebs);
+int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
+		     struct ubi_vid_hdr *vid_hdr);
+int ubi_eba_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si);
+void ubi_eba_close(const struct ubi_device *ubi);
+
+/* wl.c */
+int ubi_wl_get_peb(struct ubi_device *ubi, enum ubi_data_type dtype);
+int ubi_wl_put_peb(struct ubi_device *ubi, int pnum, int torture);
+int ubi_wl_flush(struct ubi_device *ubi);
+int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum);
+int ubi_wl_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si);
+void ubi_wl_close(struct ubi_device *ubi);
+
+/* io.c */
+int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
+		int len);
+int ubi_io_write(const struct ubi_device *ubi, const void *buf, int pnum,
+		 int offset, int len);
+int ubi_io_sync_erase(const struct ubi_device *ubi, int pnum, int torture);
+int ubi_io_is_bad(const struct ubi_device *ubi, int pnum);
+int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum);
+int ubi_io_read_ec_hdr(const struct ubi_device *ubi, int pnum,
+		       struct ubi_ec_hdr *ec_hdr, int verbose);
+int ubi_io_write_ec_hdr(const struct ubi_device *ubi, int pnum,
+			struct ubi_ec_hdr *ec_hdr);
+int ubi_io_read_vid_hdr(const struct ubi_device *ubi, int pnum,
+			struct ubi_vid_hdr *vid_hdr, int verbose);
+int ubi_io_write_vid_hdr(const struct ubi_device *ubi, int pnum,
+			 struct ubi_vid_hdr *vid_hdr);
+
+/*
+ * ubi_rb_for_each_entry - walk an RB-tree.
+ * @rb: a pointer to type 'struct rb_node' to to use as a loop counter
+ * @pos: a pointer to RB-tree entry type to use as a loop counter
+ * @root: RB-tree's root
+ * @member: the name of the 'struct rb_node' within the RB-tree entry
+ */
+#define ubi_rb_for_each_entry(rb, pos, root, member)                         \
+	for (rb = rb_first(root),                                            \
+	     pos = (rb ? container_of(rb, typeof(*pos), member) : NULL);     \
+	     rb;                                                             \
+	     rb = rb_next(rb), pos = container_of(rb, typeof(*pos), member))
+
+/**
+ * ubi_align_up - align an integer to another integer.
+ * @x: the integer to align
+ * @y: the integer to align to
+ *
+ * This function returns the lowest number which is multiple to @y and not less
+ * then @x.
+ */
+static inline int ubi_align_up(int x, int y)
+{
+	return y*(x/y) + (!!(x % y)) * y;
+}
+
+/**
+ * ubi_align_down - align an integer to another integer.
+ * @x: the integer to align
+ * @y: the integer to align to
+ *
+ * This function returns the highest number which is multiple to @y and not
+ * greater then @x.
+ */
+static inline int ubi_align_down(int x, int y)
+{
+	return y*(x/y);
+}
+
+/**
+ * ubi_zalloc_vid_hdr - allocate a volume identifier header object.
+ * @ubi: UBI device description object
+ *
+ * This function returns a pointer to the newly allocated and zero-filled
+ * volume identifier header object in case of success and %NULL in case of
+ * failure.
+ */
+static inline struct ubi_vid_hdr *ubi_zalloc_vid_hdr(const struct ubi_device *ubi)
+{
+	void *vid_hdr;
+
+	vid_hdr = kzalloc(ubi->vid_hdr_alsize, GFP_KERNEL);
+	if (unlikely(!vid_hdr))
+		return NULL;
+
+	/*
+	 * VID headers may be stored at un-aligned flash offsets, so we shift
+	 * the pointer.
+	 */
+	return vid_hdr + ubi->vid_hdr_shift;
+}
+
+/**
+ * ubi_free_vid_hdr - free a volume identifier header object.
+ * @ubi: UBI device description object
+ * @vid_hdr: the object to free
+ */
+static inline void ubi_free_vid_hdr(const struct ubi_device *ubi,
+				    struct ubi_vid_hdr *vid_hdr)
+{
+	void *p = vid_hdr;
+
+	if (unlikely(!p))
+		return;
+
+	kfree(p - ubi->vid_hdr_shift);
+}
+
+/*
+ * This function is equivalent to 'ubi_io_read()', but @offset is relative to
+ * the beginning of the logical eraseblock, not to the beginning of the
+ * physical eraseblock.
+ */
+static inline int ubi_io_read_data(const struct ubi_device *ubi, void *buf,
+				   int pnum, int offset, int len)
+{
+	ubi_assert(offset >= 0);
+	return ubi_io_read(ubi, buf, pnum, offset + ubi->leb_start, len);
+}
+
+/*
+ * This function is equivalent to 'ubi_io_write()', but @offset is relative to
+ * the beginning of the logical eraseblock, not to the beginning of the
+ * physical eraseblock.
+ */
+static inline int ubi_io_write_data(const struct ubi_device *ubi, const void *buf,
+				    int pnum, int offset, int len)
+{
+	ubi_assert(offset >= 0);
+	return ubi_io_write(ubi, buf, pnum, offset + ubi->leb_start, len);
+}
+
+/**
+ * ubi_ro_mode - switch to read-only mode.
+ * @ubi: UBI device description object
+ */
+static inline void ubi_ro_mode(struct ubi_device *ubi)
+{
+	ubi->ro_mode = 1;
+	ubi_warn("switch to read-only mode");
+}
+
+/**
+ * vol_id2idx - get table index by volume ID.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ */
+static inline int vol_id2idx(const struct ubi_device *ubi, int vol_id)
+{
+	if (vol_id >= UBI_INTERNAL_VOL_START)
+		return vol_id - UBI_INTERNAL_VOL_START + ubi->vtbl_slots;
+	else
+		return vol_id;
+}
+
+/**
+ * idx2vol_id - get volume ID by table index.
+ * @ubi: UBI device description object
+ * @idx: table index
+ */
+static inline int idx2vol_id(const struct ubi_device *ubi, int idx)
+{
+	if (idx >= ubi->vtbl_slots)
+		return idx - ubi->vtbl_slots + UBI_INTERNAL_VOL_START;
+	else
+		return idx;
+}
+
+#endif /* !__UBI_UBI_H__ */

diff -auNrp tmp-from/drivers/mtd/ubi/build.c tmp-to/drivers/mtd/ubi/build.c
@@ -0,0 +1,843 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2007
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём),
+ *         Frank Haverkamp
+ */
+
+/*
+ * This file includes UBI initialization and building of UBI devices. At the
+ * moment UBI devices may only be added while UBI is initialized, but dynamic
+ * device add/remove functionality is planned. Also, at the moment we only
+ * attach UBI devices by scanning, which will become a bottleneck when flashes
+ * reach certain large size. Then one may improve UBI and add other methods.
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/stringify.h>
+#include <linux/stat.h>
+#include "ubi.h"
+
+/* Maximum length of the 'mtd=' parameter */
+#define MTD_PARAM_LEN_MAX 64
+
+/**
+ * struct mtd_dev_param - MTD device parameter description data structure.
+ * @name: MTD device name or number string
+ * @vid_hdr_offs: VID header offset
+ * @data_offs: data offset
+ */
+struct mtd_dev_param
+{
+	char name[MTD_PARAM_LEN_MAX];
+	int vid_hdr_offs;
+	int data_offs;
+};
+
+/* Numbers of elements set in the @mtd_dev_param array */
+static int mtd_devs = 0;
+
+/* MTD devices specification parameters */
+static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];
+
+/* Number of UBI devices in system */
+int ubi_devices_cnt;
+
+/* All UBI devices in system */
+struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
+
+/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
+struct class *ubi_class;
+
+/* "Show" method for files in '/<sysfs>/class/ubi/' */
+static ssize_t ubi_version_show(struct class *class, char *buf)
+{
+	return sprintf(buf, "%d\n", UBI_VERSION);
+}
+
+/* UBI version attribute ('/<sysfs>/class/ubi/version') */
+static struct class_attribute ubi_version =
+	__ATTR(version, S_IRUGO, ubi_version_show, NULL);
+
+static ssize_t dev_attribute_show(struct device *dev,
+				  struct device_attribute *attr, char *buf);
+
+/* UBI device attributes (correspond to files in '/<sysfs>/class/ubi/ubiX') */
+static struct device_attribute dev_eraseblock_size =
+	__ATTR(eraseblock_size, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_avail_eraseblocks =
+	__ATTR(avail_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_total_eraseblocks =
+	__ATTR(total_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_volumes_count =
+	__ATTR(volumes_count, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_max_ec =
+	__ATTR(max_ec, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_reserved_for_bad =
+	__ATTR(reserved_for_bad, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_bad_peb_count =
+	__ATTR(bad_peb_count, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_max_vol_count =
+	__ATTR(max_vol_count, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_min_io_size =
+	__ATTR(min_io_size, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_bgt_enabled =
+	__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
+
+/* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
+static ssize_t dev_attribute_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	const struct ubi_device *ubi;
+
+	ubi = container_of(dev, struct ubi_device, dev);
+	if (attr == &dev_eraseblock_size)
+		return sprintf(buf, "%d\n", ubi->leb_size);
+	else if (attr == &dev_avail_eraseblocks)
+		return sprintf(buf, "%d\n", ubi->avail_pebs);
+	else if (attr == &dev_total_eraseblocks)
+		return sprintf(buf, "%d\n", ubi->good_peb_count);
+	else if (attr == &dev_volumes_count)
+		return sprintf(buf, "%d\n", ubi->vol_count);
+	else if (attr == &dev_max_ec)
+		return sprintf(buf, "%d\n", ubi->max_ec);
+	else if (attr == &dev_reserved_for_bad)
+		return sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
+	else if (attr == &dev_bad_peb_count)
+		return sprintf(buf, "%d\n", ubi->bad_peb_count);
+	else if (attr == &dev_max_vol_count)
+		return sprintf(buf, "%d\n", ubi->vtbl_slots);
+	else if (attr == &dev_min_io_size)
+		return sprintf(buf, "%d\n", ubi->min_io_size);
+	else if (attr == &dev_bgt_enabled)
+		return sprintf(buf, "%d\n", ubi->thread_enabled);
+	else
+		BUG();
+
+	return 0;
+}
+
+/* Fake "release" method for UBI devices */
+static void dev_release(struct device *dev) { }
+
+/**
+ * ubi_sysfs_init - initialize sysfs for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int ubi_sysfs_init(struct ubi_device *ubi)
+{
+	int err;
+
+	ubi->dev.release = dev_release;
+	ubi->dev.devt = MKDEV(ubi->major, 0);
+	ubi->dev.class = ubi_class;
+	sprintf(&ubi->dev.bus_id[0], UBI_NAME_STR"%d", ubi->ubi_num);
+	err = device_register(&ubi->dev);
+	if (err)
+		goto out;
+
+	err = device_create_file(&ubi->dev, &dev_eraseblock_size);
+	if (err)
+		goto out_unregister;
+	err = device_create_file(&ubi->dev, &dev_avail_eraseblocks);
+	if (err)
+		goto out_eraseblock_size;
+	err = device_create_file(&ubi->dev, &dev_total_eraseblocks);
+	if (err)
+		goto out_avail_eraseblocks;
+	err = device_create_file(&ubi->dev, &dev_volumes_count);
+	if (err)
+		goto out_total_eraseblocks;
+	err = device_create_file(&ubi->dev, &dev_max_ec);
+	if (err)
+		goto out_volumes_count;
+	err = device_create_file(&ubi->dev, &dev_reserved_for_bad);
+	if (err)
+		goto out_volumes_max_ec;
+	err = device_create_file(&ubi->dev, &dev_bad_peb_count);
+	if (err)
+		goto out_reserved_for_bad;
+	err = device_create_file(&ubi->dev, &dev_max_vol_count);
+	if (err)
+		goto out_bad_peb_count;
+	err = device_create_file(&ubi->dev, &dev_min_io_size);
+	if (err)
+		goto out_max_vol_count;
+	err = device_create_file(&ubi->dev, &dev_bgt_enabled);
+	if (err)
+		goto out_min_io_size;
+
+	return 0;
+
+out_min_io_size:
+	device_remove_file(&ubi->dev, &dev_min_io_size);
+out_max_vol_count:
+	device_remove_file(&ubi->dev, &dev_max_vol_count);
+out_bad_peb_count:
+	device_remove_file(&ubi->dev, &dev_bad_peb_count);
+out_reserved_for_bad:
+	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
+out_volumes_max_ec:
+	device_remove_file(&ubi->dev, &dev_max_ec);
+out_volumes_count:
+	device_remove_file(&ubi->dev, &dev_volumes_count);
+out_total_eraseblocks:
+	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
+out_avail_eraseblocks:
+	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
+out_eraseblock_size:
+	device_remove_file(&ubi->dev, &dev_eraseblock_size);
+out_unregister:
+	device_unregister(&ubi->dev);
+out:
+	ubi_err("failed to initialize sysfs for %s", ubi->ubi_name);
+	return err;
+}
+
+/**
+ * ubi_sysfs_close - close sysfs for an UBI device.
+ * @ubi: UBI device description object
+ */
+static void ubi_sysfs_close(struct ubi_device *ubi)
+{
+	device_remove_file(&ubi->dev, &dev_bgt_enabled);
+	device_remove_file(&ubi->dev, &dev_min_io_size);
+	device_remove_file(&ubi->dev, &dev_max_vol_count);
+	device_remove_file(&ubi->dev, &dev_bad_peb_count);
+	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
+	device_remove_file(&ubi->dev, &dev_max_ec);
+	device_remove_file(&ubi->dev, &dev_volumes_count);
+	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
+	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
+	device_remove_file(&ubi->dev, &dev_eraseblock_size);
+	device_unregister(&ubi->dev);
+}
+
+/**
+ * kill_volumes - destroy all volumes.
+ * @ubi: UBI device description object
+ */
+static void kill_volumes(struct ubi_device *ubi)
+{
+	int i;
+
+	for (i = 0; i < ubi->vtbl_slots; i++)
+		if (ubi->volumes[i])
+			ubi_free_volume(ubi, i);
+}
+
+/**
+ * uif_init - initialize user interfaces for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int uif_init(struct ubi_device *ubi)
+{
+	int i, err;
+	dev_t dev;
+
+	mutex_init(&ubi->vtbl_mutex);
+	spin_lock_init(&ubi->volumes_lock);
+
+	sprintf(ubi->ubi_name, UBI_NAME_STR "%d", ubi->ubi_num);
+
+	/*
+	 * Major numbers for the UBI character devices are allocated
+	 * dynamically. Major numbers of volume character devices are
+	 * equivalent to ones of the corresponding UBI character device. Minor
+	 * numbers of UBI character devices are 0, while minor numbers of
+	 * volume character devices start from 1. Thus, we allocate one major
+	 * number and ubi->vtbl_slots + 1 minor numbers.
+	 */
+	err = alloc_chrdev_region(&dev, 0, ubi->vtbl_slots + 1, ubi->ubi_name);
+	if (err) {
+		ubi_err("cannot register UBI character devices");
+		return err;
+	}
+
+	cdev_init(&ubi->cdev, &ubi_cdev_operations);
+	ubi->major = MAJOR(dev);
+	dbg_msg("%s major is %u", ubi->ubi_name, ubi->major);
+	ubi->cdev.owner = THIS_MODULE;
+
+	dev = MKDEV(ubi->major, 0);
+	err = cdev_add(&ubi->cdev, dev, 1);
+	if (err) {
+		ubi_err("cannot add character device %s", ubi->ubi_name);
+		goto out_unreg;
+	}
+
+	err = ubi_sysfs_init(ubi);
+	if (err)
+		goto out_cdev;
+
+	for (i = 0; i < ubi->vtbl_slots; i++)
+		if (ubi->volumes[i]) {
+			err = ubi_add_volume(ubi, i);
+			if (err)
+				goto out_volumes;
+		}
+
+	return 0;
+
+out_volumes:
+	kill_volumes(ubi);
+	ubi_sysfs_close(ubi);
+out_cdev:
+	cdev_del(&ubi->cdev);
+out_unreg:
+	unregister_chrdev_region(MKDEV(ubi->major, 0),
+				 ubi->vtbl_slots + 1);
+	return err;
+}
+
+/**
+ * uif_close - close user interfaces for an UBI device.
+ * @ubi: UBI device description object
+ */
+static void uif_close(struct ubi_device *ubi)
+{
+	kill_volumes(ubi);
+	ubi_sysfs_close(ubi);
+	cdev_del(&ubi->cdev);
+	unregister_chrdev_region(MKDEV(ubi->major, 0), ubi->vtbl_slots + 1);
+}
+
+/**
+ * attach_by_scanning - attach an MTD device using scanning method.
+ * @ubi: UBI device descriptor
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ *
+ * Note, currently this is the only method to attach UBI devices. Hopefully in
+ * the future we'll have more scalable attaching methods and avoid full media
+ * scanning. But even in this case scanning will be needed as a fall-back
+ * attaching method if there are some on-flash table corruptions.
+ */
+static int attach_by_scanning(struct ubi_device *ubi)
+{
+	int err;
+	struct ubi_scan_info *si;
+
+	si = ubi_scan(ubi);
+	if (IS_ERR(si))
+		return PTR_ERR(si);
+
+	ubi->bad_peb_count = si->bad_peb_count;
+	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
+	ubi->max_ec = si->max_ec;
+	ubi->mean_ec = si->mean_ec;
+
+	err = ubi_read_volume_table(ubi, si);
+	if (err)
+		goto out_si;
+
+	err = ubi_wl_init_scan(ubi, si);
+	if (err)
+		goto out_vtbl;
+
+	err = ubi_eba_init_scan(ubi, si);
+	if (err)
+		goto out_wl;
+
+	ubi_scan_destroy_si(si);
+	return 0;
+
+out_wl:
+	ubi_wl_close(ubi);
+out_vtbl:
+	kfree(ubi->vtbl);
+out_si:
+	ubi_scan_destroy_si(si);
+	return err;
+}
+
+/**
+ * io_init - initialize I/O unit for a given UBI device.
+ * @ubi: UBI device description object
+ *
+ * If @ubi->vid_hdr_offset or @ubi->leb_start is zero, default offsets are
+ * assumed:
+ *   o EC header is always at offset zero - this cannot be changed;
+ *   o VID header starts just after the EC header at the closest address
+ *   aligned to @io->@hdrs_min_io_size;
+ *   o data starts just after the VID header at the closest address aligned to
+ *     @io->@min_io_size
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int io_init(struct ubi_device *ubi)
+{
+	if (ubi->mtd->numeraseregions != 0) {
+		/*
+		 * Some flashes have several erase regions. Different regions
+		 * may have different eraseblock size and other
+		 * characteristics. It looks like mostly multi-region flashes
+		 * have one "main" region and one or more small regions to
+		 * store boot loader code or boot parameters or whatever. I
+		 * guess we should just pick the largest region. But this is
+		 * not implemented.
+		 */
+		ubi_err("multiple regions, not implemented");
+		return -EINVAL;
+	}
+
+	/*
+	 * Note, in this implementation we support MTD devices with 0x7FFFFFFF
+	 * physical eraseblocks maximum.
+	 */
+
+	ubi->peb_size   = ubi->mtd->erasesize;
+	ubi->peb_count  = ubi->mtd->size / ubi->mtd->erasesize;
+	ubi->flash_size = ubi->mtd->size;
+
+	if (ubi->mtd->block_isbad && ubi->mtd->block_markbad)
+		ubi->bad_allowed = 1;
+
+	ubi->min_io_size = ubi->mtd->writesize;
+	ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;
+
+	ubi_assert(ubi->hdrs_min_io_size > 0);
+	ubi_assert(ubi->hdrs_min_io_size <= ubi->min_io_size);
+	ubi_assert(ubi->min_io_size % ubi->hdrs_min_io_size == 0);
+
+	/* Calculate default aligned sizes of EC and VID headers */
+	ubi->ec_hdr_alsize = ubi_align_up(UBI_EC_HDR_SIZE,
+					  ubi->hdrs_min_io_size);
+	ubi->vid_hdr_alsize = ubi_align_up(UBI_VID_HDR_SIZE,
+					   ubi->hdrs_min_io_size);
+
+	dbg_msg("min_io_size      %d", ubi->min_io_size);
+	dbg_msg("hdrs_min_io_size %d", ubi->hdrs_min_io_size);
+	dbg_msg("ec_hdr_alsize    %d", ubi->ec_hdr_alsize);
+	dbg_msg("vid_hdr_alsize   %d", ubi->vid_hdr_alsize);
+
+	if (ubi->vid_hdr_offset == 0)
+		/* Default offset */
+		ubi->vid_hdr_offset = ubi->vid_hdr_aloffset =
+				      ubi->ec_hdr_alsize;
+	else {
+		ubi->vid_hdr_aloffset = ubi_align_down(ubi->vid_hdr_offset,
+						   ubi->hdrs_min_io_size);
+		ubi->vid_hdr_shift = ubi->vid_hdr_offset -
+					ubi->vid_hdr_aloffset;
+	}
+
+	/* Similar for the data offset */
+	if (ubi->leb_start == 0) {
+		ubi->leb_start = ubi->vid_hdr_offset + ubi->vid_hdr_alsize;
+		ubi->leb_start = ubi_align_up(ubi->leb_start, ubi->min_io_size);
+	}
+
+	dbg_msg("vid_hdr_offset   %d", ubi->vid_hdr_offset);
+	dbg_msg("vid_hdr_aloffset %d", ubi->vid_hdr_aloffset);
+	dbg_msg("vid_hdr_shift    %d", ubi->vid_hdr_shift);
+	dbg_msg("leb_start        %d", ubi->leb_start);
+
+	/* The shift must be aligned to 32-bit boundary */
+	if (ubi->vid_hdr_shift % 4) {
+		ubi_err("unaligned VID header shift %d",
+			ubi->vid_hdr_shift);
+		return -EINVAL;
+	}
+
+	/* Check sanity */
+	if (ubi->vid_hdr_offset < UBI_EC_HDR_SIZE ||
+	    ubi->leb_start < ubi->vid_hdr_offset + UBI_VID_HDR_SIZE ||
+	    ubi->leb_start > ubi->peb_size - UBI_VID_HDR_SIZE ||
+	    ubi->leb_start % ubi->min_io_size) {
+		ubi_err("bad VID header (%d) or data offsets (%d)",
+			ubi->vid_hdr_offset, ubi->leb_start);
+		return -EINVAL;
+	}
+
+	/*
+	 * It may happen that EC and VID headers are situated in one minimal
+	 * I/O unit. In this case we can only accept this UBI image in
+	 * read-only mode.
+	 */
+	if (ubi->vid_hdr_offset + UBI_VID_HDR_SIZE <= ubi->hdrs_min_io_size) {
+		ubi_warn("EC and VID headers are in the same minimal I/O unit, "
+			 "switch to read-only mode");
+		ubi->ro_mode = 1;
+	}
+
+	ubi->leb_size = ubi->peb_size - ubi->leb_start;
+
+	if (!(ubi->mtd->flags & MTD_WRITEABLE)) {
+		ubi_msg("MTD device %d is write-protected, attach in "
+			"read-only mode", ubi->mtd->index);
+		ubi->ro_mode = 1;
+	}
+
+	dbg_msg("leb_size         %d", ubi->leb_size);
+	dbg_msg("ro_mode          %d", ubi->ro_mode);
+
+	/*
+	 * Note, ideally, we have to initialize ubi->bad_peb_count here. But
+	 * unfortunately, MTD does not provide this information. We should loop
+	 * over all physical eraseblocks and invoke mtd->block_is_bad() for
+	 * each physical eraseblock. So, we skip ubi->bad_peb_count
+	 * uninitialized and initialize it after scanning.
+	 */
+
+	return 0;
+}
+
+/**
+ * attach_mtd_dev - attach an MTD device.
+ * @mtd_dev: MTD device name or number string
+ * @vid_hdr_offset: VID header offset
+ * @data_offset: data offset
+ *
+ * This function attaches an MTD device to UBI. It first treats @mtd_dev as the
+ * MTD device name, and tries to open it by this name. If it is unable to open,
+ * it tries to convert @mtd_dev to an integer and open the MTD device by its
+ * number. Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int attach_mtd_dev(const char *mtd_dev, int vid_hdr_offset,
+			  int data_offset)
+{
+	struct ubi_device *ubi;
+	struct mtd_info *mtd;
+	int i, err;
+
+	mtd = get_mtd_device_nm(mtd_dev);
+	if (IS_ERR(mtd)) {
+		int mtd_num;
+		char *endp;
+
+		if (PTR_ERR(mtd) != -ENODEV)
+			return PTR_ERR(mtd);
+
+		/*
+		 * Probably this is not MTD device name but MTD device number -
+		 * check this out.
+		 */
+		mtd_num = simple_strtoul(mtd_dev, &endp, 0);
+		if (*endp != '\0' || mtd_dev == endp) {
+			ubi_err("incorrect MTD device: \"%s\"", mtd_dev);
+			return -ENODEV;
+		}
+
+		mtd = get_mtd_device(NULL, mtd_num);
+		if (IS_ERR(mtd))
+			return PTR_ERR(mtd);
+	}
+
+	/* Check if we already have the same MTD device attached */
+	for (i = 0; i < ubi_devices_cnt; i++)
+		if (ubi_devices[i]->mtd->index == mtd->index) {
+			ubi_err("mtd%d is already attached to ubi%d",
+				mtd->index, i);
+			err = -EINVAL;
+			goto out_mtd;
+		}
+
+	ubi = ubi_devices[ubi_devices_cnt] = kzalloc(sizeof(struct ubi_device),
+						      GFP_KERNEL);
+	if (!ubi) {
+		err = -ENOMEM;
+		goto out_mtd;
+	}
+
+	ubi->ubi_num = ubi_devices_cnt;
+	ubi->mtd = mtd;
+
+	dbg_msg("attaching mtd%d to ubi%d: VID header offset %d data offset %d",
+		ubi->mtd->index, ubi_devices_cnt, vid_hdr_offset, data_offset);
+
+	ubi->vid_hdr_offset = vid_hdr_offset;
+	ubi->leb_start = data_offset;
+	err = io_init(ubi);
+	if (err)
+		goto out_free;
+
+	err = attach_by_scanning(ubi);
+	if (err) {
+		dbg_err("failed to attach by scanning, error %d", err);
+		goto out_free;
+	}
+
+	err = uif_init(ubi);
+	if (err)
+		goto out_detach;
+
+	ubi_devices_cnt += 1;
+
+	ubi_msg("attached mtd%d to ubi%d", ubi->mtd->index, ubi_devices_cnt);
+	ubi_msg("MTD device name:            \"%s\"", ubi->mtd->name);
+	ubi_msg("MTD device size:            %llu MiB", ubi->flash_size >> 20);
+	ubi_msg("physical eraseblock size:   %d bytes (%d KiB)",
+		ubi->peb_size, ubi->peb_size >> 10);
+	ubi_msg("logical eraseblock size:    %d bytes", ubi->leb_size);
+	ubi_msg("number of good PEBs:        %d", ubi->good_peb_count);
+	ubi_msg("number of bad PEBs:         %d", ubi->bad_peb_count);
+	ubi_msg("smallest flash I/O unit:    %d", ubi->min_io_size);
+	ubi_msg("VID header offset:          %d (aligned %d)",
+		ubi->vid_hdr_offset, ubi->vid_hdr_aloffset);
+	ubi_msg("data offset:                %d", ubi->leb_start);
+	ubi_msg("max. allowed volumes:       %d", ubi->vtbl_slots);
+	ubi_msg("wear-leveling threshold:    %d", CONFIG_MTD_UBI_WL_THRESHOLD);
+	ubi_msg("number of internal volumes: %d", UBI_INT_VOL_COUNT);
+	ubi_msg("number of user volumes:     %d",
+		ubi->vol_count - UBI_INT_VOL_COUNT);
+	ubi_msg("available PEBs:             %d", ubi->avail_pebs);
+	ubi_msg("total number of reserved PEBs: %d", ubi->rsvd_pebs);
+	ubi_msg("number of PEBs reserved for bad PEB handling: %d",
+		ubi->beb_rsvd_pebs);
+	ubi_msg("max/mean erase counter: %d/%d", ubi->max_ec, ubi->mean_ec);
+
+	/* Enable the background thread */
+	if (!DBG_DISABLE_BGT) {
+		ubi->thread_enabled = 1;
+		wake_up_process(ubi->bgt_thread);
+	}
+
+	return 0;
+
+out_detach:
+	ubi_eba_close(ubi);
+	ubi_wl_close(ubi);
+	kfree(ubi->vtbl);
+out_free:
+	kfree(ubi);
+out_mtd:
+	put_mtd_device(mtd);
+	ubi_devices[ubi_devices_cnt] = NULL;
+	return err;
+}
+
+/**
+ * detach_mtd_dev - detach an MTD device.
+ * @ubi: UBI device description object
+ */
+static void detach_mtd_dev(struct ubi_device *ubi)
+{
+	int ubi_num = ubi->ubi_num, mtd_num = ubi->mtd->index;
+
+	dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
+	uif_close(ubi);
+	ubi_eba_close(ubi);
+	ubi_wl_close(ubi);
+	kfree(ubi->vtbl);
+	put_mtd_device(ubi->mtd);
+	kfree(ubi_devices[ubi_num]);
+	ubi_devices[ubi_num] = NULL;
+	ubi_devices_cnt -= 1;
+	ubi_assert(ubi_devices_cnt >= 0);
+	ubi_msg("mtd% is detached from ubi%d", mtd_num, ubi_num);
+}
+
+static int __init ubi_init(void)
+{
+	int err, i, k;
+
+	/* Ensure that EC and VID headers have correct size */
+	BUILD_BUG_ON(sizeof(struct ubi_ec_hdr) != 64);
+	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);
+
+	if (mtd_devs > UBI_MAX_DEVICES) {
+		printk("UBI error: too many MTD devices, maximum is %d\n",
+		       UBI_MAX_DEVICES);
+		return -EINVAL;
+	}
+
+	ubi_class = class_create(THIS_MODULE, UBI_NAME_STR);
+	if (IS_ERR(ubi_class))
+		return PTR_ERR(ubi_class);
+
+	err = class_create_file(ubi_class, &ubi_version);
+	if (err)
+		goto out_class;
+
+	/* Attach MTD devices */
+	for (i = 0; i < mtd_devs; i++) {
+		struct mtd_dev_param *p = &mtd_dev_param[i];
+
+		cond_resched();
+
+		if (!p->name) {
+			dbg_err("empty name");
+			err = -EINVAL;
+			goto out_detach;
+		}
+
+		err = attach_mtd_dev(p->name, p->vid_hdr_offs, p->data_offs);
+		if (err)
+			goto out_detach;
+	}
+
+	return 0;
+
+out_detach:
+	for (k = 0; k < i; k++)
+		detach_mtd_dev(ubi_devices[k]);
+	class_remove_file(ubi_class, &ubi_version);
+out_class:
+	class_destroy(ubi_class);
+	return err;
+}
+module_init(ubi_init);
+
+static void __exit ubi_exit(void)
+{
+	int i, n = ubi_devices_cnt;
+
+	for (i = 0; i < n; i++)
+		detach_mtd_dev(ubi_devices[i]);
+	class_remove_file(ubi_class, &ubi_version);
+	class_destroy(ubi_class);
+}
+module_exit(ubi_exit);
+
+/**
+ * bytes_str_to_int - convert a string representing number of bytes to an
+ * integer.
+ * @str: the string to convert
+ *
+ * This function returns positive resulting integer in case of success and a
+ * negative error code in case of failure.
+ */
+static int __init bytes_str_to_int(const char *str)
+{
+	char *endp;
+	unsigned long result;
+
+	result = simple_strtoul(str, &endp, 0);
+	if (str == endp || result < 0) {
+		printk("UBI error: incorrect bytes count: \"%s\"\n", str);
+		return -EINVAL;
+	}
+
+	switch (*endp) {
+	case 'G':
+		result *= 1024;
+	case 'M':
+		result *= 1024;
+	case 'K':
+	case 'k':
+		result *= 1024;
+		if (endp[1] == 'i' && (endp[2] == '\0' ||
+			  endp[2] == 'B'  || endp[2] == 'b'))
+			endp += 2;
+	case '\0':
+		break;
+	default:
+		printk("UBI error: incorrect bytes count: \"%s\"\n", str);
+		return -EINVAL;
+	}
+
+	return result;
+}
+
+/**
+ * ubi_mtd_param_parse - parse the 'mtd=' UBI parameter.
+ * @val: the parameter value to parse
+ * @kp: not used
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of error.
+ */
+static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
+{
+	int i, len;
+	struct mtd_dev_param *p;
+	char buf[MTD_PARAM_LEN_MAX];
+	char *pbuf = &buf[0];
+	char *tokens[3] = {NULL, NULL, NULL};
+
+	if (mtd_devs == UBI_MAX_DEVICES) {
+		printk("UBI error: too many parameters, max. is %d\n",
+		       UBI_MAX_DEVICES);
+		return -EINVAL;
+	}
+
+	len = strnlen(val, MTD_PARAM_LEN_MAX);
+	if (len == MTD_PARAM_LEN_MAX) {
+		printk("UBI error: parameter \"%s\" is too long, max. is %d\n",
+		       val, MTD_PARAM_LEN_MAX);
+		return -EINVAL;
+	}
+
+	if (len == 0) {
+		printk("UBI warning: empty 'mtd=' parameter - ignored\n");
+		return 0;
+	}
+
+	strcpy(buf, val);
+
+	/* Get rid of the final newline */
+	if (buf[len - 1] == '\n')
+		buf[len - 1] = 0;
+
+	for (i = 0; i < 3; i++)
+		tokens[i] = strsep(&pbuf, ",");
+
+	if (pbuf) {
+		printk("UBI error: too many arguments at \"%s\"\n", val);
+		return -EINVAL;
+	}
+
+	if (tokens[0] == '\0')
+		return -EINVAL;
+
+	p = &mtd_dev_param[mtd_devs];
+	strcpy(&p->name[0], tokens[0]);
+
+	if (tokens[1])
+		p->vid_hdr_offs = bytes_str_to_int(tokens[1]);
+	if (tokens[2])
+		p->data_offs = bytes_str_to_int(tokens[2]);
+
+	if (p->vid_hdr_offs < 0)
+		return p->vid_hdr_offs;
+	if (p->data_offs < 0)
+		return p->data_offs;
+
+	mtd_devs += 1;
+	return 0;
+}
+
+module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
+MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: "
+		      "mtd=<name|num>[,<vid_hdr_offs>,<data_offs>]. "
+		      "Multiple \"mtd\" parameters may be specified.\n"
+		      "MTD devices may be specified by their number or name. "
+		      "Optional \"vid_hdr_offs\" and \"data_offs\" parameters "
+		      "specify UBI VID header position and data starting "
+		      "position to be used by UBI.\n"
+		      "Example: mtd=content,1984,2048 mtd=4 - attach MTD device"
+		      "with name content using VID header offset 1984 and data "
+		      "start 2048, and MTD device number 4 using default "
+		      "offsets");
+
+MODULE_VERSION(__stringify(UBI_VERSION));
+MODULE_DESCRIPTION("UBI - Unsorted Block Images");
+MODULE_AUTHOR("Artem Bityutskiy");
+MODULE_LICENSE("GPL");

diff -auNrp tmp-from/drivers/mtd/ubi/scan.c tmp-to/drivers/mtd/ubi/scan.c
@@ -0,0 +1,1374 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * UBI scanning unit.
+ *
+ * This unit is responsible for scanning the flash media, checking UBI
+ * headers and providing complete information about the UBI flash image.
+ *
+ * The scanning information is reoresented by a &struct ubi_scan_info' object.
+ * Information about found volumes is represented by &struct ubi_scan_volume
+ * objects which are kept in volume RB-tree with root at the @volumes field.
+ * The RB-tree is indexed by the volume ID.
+ *
+ * Found logical eraseblocks are represented by &struct ubi_scan_leb objects.
+ * These objects are kept in per-volume RB-trees with the root at the
+ * corresponding &struct ubi_scan_volume object. To put it differently, we keep
+ * an RB-tree of per-volume objects and each of these objects is the root of
+ * RB-tree of per-eraseblock objects.
+ *
+ * Corrupted physical eraseblocks are put to the @corr list, free physical
+ * eraseblocks are put to the @free list and the physical eraseblock to be
+ * erased are put to the @erase list.
+ */
+
+#include <linux/err.h>
+#include <linux/crc32.h>
+#include "ubi.h"
+
+#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
+static int paranoid_check_si(const struct ubi_device *ubi,
+			     struct ubi_scan_info *si);
+#else
+#define paranoid_check_si(ubi, si) 0
+#endif
+
+/* Temporary variables used during scanning */
+static struct ubi_ec_hdr *ech;
+static struct ubi_vid_hdr *vidh;
+
+int ubi_scan_add_to_list(struct ubi_scan_info *si, int pnum, int ec,
+			 struct list_head *list)
+{
+	struct ubi_scan_leb *seb;
+
+	if (list == &si->free)
+		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
+	else if (list == &si->erase)
+		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
+	else if (list == &si->corr)
+		dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
+	else if (list == &si->alien)
+		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
+	else
+		BUG();
+
+	seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
+	if (unlikely(!seb))
+		return -ENOMEM;
+
+	seb->pnum = pnum;
+	seb->ec = ec;
+	list_add_tail(&seb->u.list, list);
+	return 0;
+}
+
+/**
+ * commit_to_mean_value - commit intermediate results to the final mean erase
+ * counter value.
+ * @si: scanning information
+ *
+ * This is a helper function which calculates partial mean erase counter mean
+ * value and adds it to the resulting mean value. As we can work only in
+ * integer arithmetic and we want to calculate the mean value of erase counter
+ * accurately, we first sum erase counter values in @si->ec_sum variable and
+ * count these components in @si->ec_count. If this temporary @si->ec_sum is
+ * going to overflow, we calculate the partial mean value
+ * (@si->ec_sum/@si->ec_count) and add it to @si->mean_ec.
+ */
+static void commit_to_mean_value(struct ubi_scan_info *si)
+{
+	si->ec_sum /= si->ec_count;
+	if (si->ec_sum % si->ec_count >= si->ec_count / 2)
+		si->mean_ec += 1;
+	si->mean_ec += si->ec_sum;
+}
+
+/**
+ * validate_vid_hdr - check that volume identifier header is correct and
+ * consistent.
+ * @vid_hdr: the volume identifier header to check
+ * @sv: information about the volume this logical eraseblock belongs to
+ * @pnum: physical eraseblock number the VID header came from
+ *
+ * This function checks that data stored in @vid_hdr is consistent. Returns
+ * non-zero if an inconsistency was found and zero if not.
+ *
+ * Note, UBI does sanity check of everything it reads from the flash media.
+ * Most of the checks are done in the I/O unit. Here we check that the
+ * information in the VID header is consistent to the information in other VID
+ * headers of the same volume.
+ */
+static int validate_vid_hdr(const struct ubi_vid_hdr *vid_hdr,
+			    const struct ubi_scan_volume *sv, int pnum)
+{
+	int vol_type = vid_hdr->vol_type;
+	int vol_id = ubi32_to_cpu(vid_hdr->vol_id);
+	int used_ebs = ubi32_to_cpu(vid_hdr->used_ebs);
+	int data_pad = ubi32_to_cpu(vid_hdr->data_pad);
+
+	if (sv->leb_count != 0) {
+		int sv_vol_type;
+
+		/*
+		 * This is not the first logical eraseblock belonging to this
+		 * volume. Ensure that the data in its VID header is consistent
+		 * to the data in previous logical eraseblock headers.
+		 */
+
+		if (unlikely(vol_id != sv->vol_id)) {
+			dbg_err("inconsistent vol_id");
+			goto bad;
+		}
+
+		if (sv->vol_type == UBI_STATIC_VOLUME)
+			sv_vol_type = UBI_VID_STATIC;
+		else
+			sv_vol_type = UBI_VID_DYNAMIC;
+
+		if (unlikely(vol_type != sv_vol_type)) {
+			dbg_err("inconsistent vol_type");
+			goto bad;
+		}
+
+		if (unlikely(used_ebs != sv->used_ebs)) {
+			dbg_err("inconsistent used_ebs");
+			goto bad;
+		}
+
+		if (unlikely(data_pad != sv->data_pad)) {
+			dbg_err("inconsistent data_pad");
+			goto bad;
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err("inconsistent VID header at PEB %d", pnum);
+	ubi_dbg_dump_vid_hdr(vid_hdr);
+	ubi_dbg_dump_sv(sv);
+	return -EINVAL;
+}
+
+/**
+ * add_volume - add volume to the scanning information.
+ * @si: scanning information
+ * @vol_id: ID of the volume to add
+ * @pnum: physical eraseblock number
+ * @vid_hdr: volume identifier header
+ *
+ * If the volume corresponding to the @vid_hdr logical eraseblock is already
+ * present in the scanning information, this function does nothing. Otherwise
+ * it adds corresponding volume to the scanning information. Returns a pointer
+ * to the scanning volume object in case of success and a negative error code
+ * in case of failure.
+ */
+static struct ubi_scan_volume *add_volume(struct ubi_scan_info *si, int vol_id,
+					  int pnum,
+					  const struct ubi_vid_hdr *vid_hdr)
+{
+	struct ubi_scan_volume *sv;
+	struct rb_node **p = &si->volumes.rb_node, *parent = NULL;
+
+	ubi_assert(vol_id == ubi32_to_cpu(vid_hdr->vol_id));
+
+	/* Walk the volume RB-tree to look if this volume is already present */
+	while (*p) {
+		parent = *p;
+		sv = rb_entry(parent, struct ubi_scan_volume, rb);
+
+		if (vol_id == sv->vol_id)
+			return sv;
+
+		if (vol_id > sv->vol_id)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+
+	/* The volume is absent - add it */
+	sv = kmalloc(sizeof(struct ubi_scan_volume), GFP_KERNEL);
+	if (unlikely(!sv))
+		return ERR_PTR(-ENOMEM);
+
+	sv->highest_lnum = sv->leb_count = 0;
+	si->max_sqnum = 0;
+	sv->vol_id = vol_id;
+	sv->root = RB_ROOT;
+	sv->used_ebs = ubi32_to_cpu(vid_hdr->used_ebs);
+	sv->data_pad = ubi32_to_cpu(vid_hdr->data_pad);
+	sv->compat = vid_hdr->compat;
+	sv->vol_type = vid_hdr->vol_type == UBI_VID_DYNAMIC ? UBI_DYNAMIC_VOLUME
+							    : UBI_STATIC_VOLUME;
+	if (vol_id > si->highest_vol_id)
+		si->highest_vol_id = vol_id;
+
+	rb_link_node(&sv->rb, parent, p);
+	rb_insert_color(&sv->rb, &si->volumes);
+	si->vols_found += 1;
+	dbg_bld("added volume %d", vol_id);
+	return sv;
+}
+
+/**
+ * compare_lebs - find out which logical eraseblock is newer.
+ * @ubi: UBI device description object
+ * @seb: first logical eraseblock to compare
+ * @pnum: physical eraseblock number of the second logical eraseblock to
+ * compare
+ * @vid_hdr: volume identifier header of the second logical eraseblock
+ *
+ * This function compares 2 copies of a LEB and informs which one is newer. In
+ * case of success this function returns a positive value, in case of failure, a
+ * negative error code is returned. The success return codes use the following
+ * bits:
+ *     o bit 0 is cleared: the first PEB (described by @seb) is newer then the
+ *       second PEB (described by @pnum and @vid_hdr);
+ *     o bit 0 is set: the second PEB is newer;
+ *     o bit 1 is cleared: no bit-flips were detected in the newer LEB;
+ *     o bit 1 is set: bit-flips were detected in the newer LEB;
+ *     o bit 2 is cleared: the older LEB is not corrupted;
+ *     o bit 2 is set: the older LEB is corrupted.
+ */
+static int compare_lebs(const struct ubi_device *ubi,
+			const struct ubi_scan_leb *seb, int pnum,
+			const struct ubi_vid_hdr *vid_hdr)
+{
+	void *buf;
+	int len, err, second_is_newer, bitflips = 0, corrupted = 0;
+	uint32_t data_crc, crc;
+	struct ubi_vid_hdr *vidh = NULL;
+	unsigned long long sqnum2 = ubi64_to_cpu(vid_hdr->sqnum);
+
+	if (seb->sqnum == 0 && sqnum2 == 0) {
+		long long abs, v1 = seb->leb_ver, v2 = ubi32_to_cpu(vid_hdr->leb_ver);
+
+		/*
+		 * UBI constantly increases the logical eraseblock version
+		 * number and it can overflow. Thus, we have to bear in mind
+		 * that versions that are close to %0xFFFFFFFF are less then
+		 * versions that are close to %0.
+		 *
+		 * The UBI WL unit guarantees that the number of pending tasks
+		 * is not greater then %0x7FFFFFFF. So, if the difference
+		 * between any two versions is greater or equivalent to
+		 * %0x7FFFFFFF, there was an overflow and the logical
+		 * eraseblock with lower version is actually newer then the one
+		 * with higher version.
+		 *
+		 * FIXME: but this is anyway obsolete and will be removed at
+		 * some point.
+		 */
+
+		dbg_bld("using old crappy leb_ver stuff");
+
+		abs = v1 - v2;
+		if (abs < 0)
+			abs = -abs;
+
+		if (likely(abs < 0x7FFFFFFF))
+			/* Non-overflow situation */
+			second_is_newer = (v2 > v1);
+		else
+			second_is_newer = (v2 < v1);
+	} else
+		/* Obviously the LEB with lower sequence counter is older */
+		second_is_newer = sqnum2 > seb->sqnum;
+
+	/*
+	 * Now we know which copy is newer. If the copy flag of the PEB with
+	 * newer version is not set, then we just return, otherwise we have to
+	 * check data CRC. For the second PEB we already have the VID header,
+	 * for the first one - we'll need to re-read it from flash.
+	 *
+	 * FIXME: this may be optimized so that we wouldn't read twice.
+	 */
+
+	if (second_is_newer) {
+		if (!vid_hdr->copy_flag) {
+			/* It is not a copy, so it is newer */
+			dbg_bld("second PEB %d is newer, copy_flag is unset",
+				pnum);
+			return 1;
+		}
+	} else {
+		pnum = seb->pnum;
+
+		vidh = ubi_zalloc_vid_hdr(ubi);
+		if (!vidh)
+			return -ENOMEM;
+
+		err = ubi_io_read_vid_hdr(ubi, pnum, vidh, 0);
+		if (unlikely(err)) {
+			if (err == UBI_IO_BITFLIPS)
+				bitflips = 1;
+			else {
+				dbg_err("VID of PEB %d header is bad, but it "
+					"was OK earlier", pnum);
+				if (err > 0)
+					err = -EIO;
+
+				goto out_free_vidh;
+			}
+		}
+
+		if (!vidh->copy_flag) {
+			/* It is not a copy, so it is newer */
+			dbg_bld("first PEB %d is newer, copy_flag is unset",
+				pnum);
+			err = bitflips << 1;
+			goto out_free_vidh;
+		}
+
+		vid_hdr = vidh;
+	}
+
+	/* Read the data of the copy and check the CRC */
+
+	len = ubi32_to_cpu(vid_hdr->data_size);
+	buf = kmalloc(len, GFP_KERNEL);
+	if (unlikely(!buf)) {
+		err = -ENOMEM;
+		goto out_free_vidh;
+	}
+
+	err = ubi_io_read_data(ubi, buf, pnum, 0, len);
+	if (unlikely(err && err != UBI_IO_BITFLIPS))
+		goto out_free_buf;
+
+	data_crc = ubi32_to_cpu(vid_hdr->data_crc);
+	crc = crc32(UBI_CRC32_INIT, buf, len);
+	if (unlikely(crc != data_crc)) {
+		dbg_bld("PEB %d CRC error: calculated %#08x, must be %#08x",
+			pnum, crc, data_crc);
+		corrupted = 1;
+		bitflips = 0;
+		second_is_newer = !second_is_newer;
+	} else {
+		dbg_bld("PEB %d CRC is OK", pnum);
+		bitflips = !!err;
+	}
+
+	kfree(buf);
+	ubi_free_vid_hdr(ubi, vidh);
+
+	if (second_is_newer)
+		dbg_bld("second PEB %d is newer, copy_flag is set", pnum);
+	else
+		dbg_bld("first PEB %d is newer, copy_flag is set", pnum);
+
+	return second_is_newer | (bitflips << 1) | (corrupted << 2);
+
+out_free_buf:
+	kfree(buf);
+out_free_vidh:
+	ubi_free_vid_hdr(ubi, vidh);
+	ubi_assert(err < 0);
+	return err;
+}
+
+/**
+ * ubi_scan_add_used - add information about a physical eraseblock to the
+ * scanning information.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ * @pnum: the physical eraseblock number
+ * @ec: erase counter
+ * @vid_hdr: the volume identifier header
+ * @bitflips: if bit-flips were detected when this physical eraseblock was read
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_scan_add_used(const struct ubi_device *ubi, struct ubi_scan_info *si,
+		      int pnum, int ec, const struct ubi_vid_hdr *vid_hdr,
+		      int bitflips)
+{
+	int err, vol_id, lnum;
+	uint32_t leb_ver;
+	unsigned long long sqnum;
+	struct ubi_scan_volume *sv;
+	struct ubi_scan_leb *seb;
+	struct rb_node **p, *parent = NULL;
+
+	vol_id = ubi32_to_cpu(vid_hdr->vol_id);
+	lnum = ubi32_to_cpu(vid_hdr->lnum);
+	sqnum = ubi64_to_cpu(vid_hdr->sqnum);
+	leb_ver = ubi32_to_cpu(vid_hdr->leb_ver);
+
+	dbg_bld("PEB %d, LEB %d:%d, EC %d, sqnum %llu, ver %u, bitflips %d",
+		pnum, vol_id, lnum, ec, sqnum, leb_ver, bitflips);
+
+	sv = add_volume(si, vol_id, pnum, vid_hdr);
+	if (unlikely(IS_ERR(sv)) < 0)
+		return PTR_ERR(sv);
+
+	/*
+	 * Walk the RB-tree of logical eraseblocks of volume @vol_id to look
+	 * if this is the first instance of this logical eraseblock or not.
+	 */
+	p = &sv->root.rb_node;
+	while (*p) {
+		int cmp_res;
+
+		parent = *p;
+		seb = rb_entry(parent, struct ubi_scan_leb, u.rb);
+		if (lnum != seb->lnum) {
+			if (lnum < seb->lnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+			continue;
+		}
+
+		/*
+		 * There is already a physical eraseblock describing the same
+		 * logical eraseblock present.
+		 */
+
+		dbg_bld("this LEB already exists: PEB %d, sqnum %llu, "
+			"LEB ver %u, EC %d", seb->pnum, seb->sqnum,
+			seb->leb_ver, seb->ec);
+
+		/*
+		 * Make sure that the logical eraseblocks have different
+		 * versions. Otherwise the image is bad.
+		 */
+		if (unlikely(seb->leb_ver == leb_ver && leb_ver != 0)) {
+			ubi_err("two LEBs with same version %u", leb_ver);
+			ubi_dbg_dump_seb(seb, 0);
+			ubi_dbg_dump_vid_hdr(vid_hdr);
+			return -EINVAL;
+		}
+
+		/*
+		 * Make sure that the logical eraseblocks have different
+		 * sequence numbers. Otherwise the image is bad.
+		 *
+		 * FIXME: remove 'sqnum != 0' check when leb_ver is removed.
+		 */
+		if (unlikely(seb->sqnum == sqnum && sqnum != 0)) {
+			ubi_err("two LEBs with same sequence number %llu",
+				sqnum);
+			ubi_dbg_dump_seb(seb, 0);
+			ubi_dbg_dump_vid_hdr(vid_hdr);
+			return -EINVAL;
+		}
+
+		/*
+		 * Now we have to drop the older one and preserve the newer
+		 * one.
+		 */
+		cmp_res = compare_lebs(ubi, seb, pnum, vid_hdr);
+		if (unlikely(cmp_res < 0))
+			return cmp_res;
+
+		if (cmp_res & 1) {
+			/*
+			 * This logical eraseblock is newer then the one
+			 * found earlier.
+			 */
+			err = validate_vid_hdr(vid_hdr, sv, pnum);
+			if (unlikely(err))
+				return err;
+
+			if (cmp_res & 4)
+				err = ubi_scan_add_to_list(si, seb->pnum,
+							   seb->ec, &si->corr);
+			else
+				err = ubi_scan_add_to_list(si, seb->pnum,
+							   seb->ec, &si->erase);
+			if (unlikely(err))
+				return err;
+
+			seb->ec = ec;
+			seb->pnum = pnum;
+			seb->scrub = ((cmp_res & 2) || bitflips);
+			seb->sqnum = sqnum;
+			seb->leb_ver = leb_ver;
+
+			if (sv->highest_lnum == lnum)
+				sv->last_data_size =
+					ubi32_to_cpu(vid_hdr->data_size);
+
+			return 0;
+		} else {
+			/*
+			 * This logical eraseblock is older then the one found
+			 * previously.
+			 */
+			if (cmp_res & 4)
+				return ubi_scan_add_to_list(si, pnum, ec,
+							    &si->corr);
+			else
+				return ubi_scan_add_to_list(si, pnum, ec,
+							    &si->erase);
+		}
+	}
+
+	/*
+	 * We've met this logical eraseblock for the first time, add it to the
+	 * scanning information.
+	 */
+
+	err = validate_vid_hdr(vid_hdr, sv, pnum);
+	if (unlikely(err))
+		return err;
+
+	seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
+	if (unlikely(!seb))
+		return -ENOMEM;
+
+	seb->ec = ec;
+	seb->pnum = pnum;
+	seb->lnum = lnum;
+	seb->sqnum = sqnum;
+	seb->scrub = bitflips;
+	seb->leb_ver = leb_ver;
+
+	if (sv->highest_lnum <= lnum) {
+		sv->highest_lnum = lnum;
+		sv->last_data_size = ubi32_to_cpu(vid_hdr->data_size);
+	}
+
+	if (si->max_sqnum < sqnum)
+		si->max_sqnum = sqnum;
+
+	sv->leb_count += 1;
+	rb_link_node(&seb->u.rb, parent, p);
+	rb_insert_color(&seb->u.rb, &sv->root);
+	return 0;
+}
+
+/**
+ * ubi_scan_find_sv - find information about a particular volume in the
+ * scanning information.
+ * @si: scanning information
+ * @vol_id: the requested volume ID
+ *
+ * This function returns a pointer to the volume description or %NULL if there
+ * are no data about this volume in the scanning information.
+ */
+struct ubi_scan_volume *ubi_scan_find_sv(const struct ubi_scan_info *si,
+					 int vol_id)
+{
+	struct ubi_scan_volume *sv;
+	struct rb_node *p = si->volumes.rb_node;
+
+	while (p) {
+		sv = rb_entry(p, struct ubi_scan_volume, rb);
+
+		if (vol_id == sv->vol_id)
+			return sv;
+
+		if (vol_id > sv->vol_id)
+			p = p->rb_left;
+		else
+			p = p->rb_right;
+	}
+
+	return NULL;
+}
+
+/**
+ * ubi_scan_find_seb - find information about a particular logical
+ * eraseblock in the volume scanning information.
+ * @sv: a pointer to the volume scanning information
+ * @lnum: the requested logical eraseblock
+ *
+ * This function returns a pointer to the scanning logical eraseblock or %NULL
+ * if there are no data about it in the scanning volume information.
+ */
+struct ubi_scan_leb *ubi_scan_find_seb(const struct ubi_scan_volume *sv,
+				       int lnum)
+{
+	struct ubi_scan_leb *seb;
+	struct rb_node *p = sv->root.rb_node;
+
+	while (p) {
+		seb = rb_entry(p, struct ubi_scan_leb, u.rb);
+
+		if (lnum == seb->lnum)
+			return seb;
+
+		if (lnum > seb->lnum)
+			p = p->rb_left;
+		else
+			p = p->rb_right;
+	}
+
+	return NULL;
+}
+
+/**
+ * ubi_scan_rm_volume - delete scanning information about a volume.
+ * @si: scanning information
+ * @sv: the volume scanning information to delete
+ */
+void ubi_scan_rm_volume(struct ubi_scan_info *si, struct ubi_scan_volume *sv)
+{
+	struct rb_node *rb;
+	struct ubi_scan_leb *seb;
+
+	dbg_bld("remove scanning information about volume %d", sv->vol_id);
+
+	while ((rb = rb_first(&sv->root))) {
+		seb = rb_entry(rb, struct ubi_scan_leb, u.rb);
+		rb_erase(&seb->u.rb, &sv->root);
+		list_add_tail(&seb->u.list, &si->erase);
+	}
+
+	rb_erase(&sv->rb, &si->volumes);
+	kfree(sv);
+	si->vols_found -= 1;
+}
+
+/**
+ * ubi_scan_erase_peb - erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ * @pnum: physical eraseblock number to erase;
+ * @ec: erase counter value to write (%UBI_SCAN_UNKNOWN_EC if it is unknown)
+ *
+ * This function erases physical eraseblock 'pnum', and writes the erase
+ * counter header to it. This function should only be used on UBI device
+ * initialization stages, when the EBA unit had not been yet initialized. This
+ * function returns zero in case of success and a negative error code in case
+ * of failure.
+ */
+int ubi_scan_erase_peb(const struct ubi_device *ubi,
+		       const struct ubi_scan_info *si, int pnum, int ec)
+{
+	int err;
+	struct ubi_ec_hdr *ec_hdr;
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	if (unlikely((long long)ec >= UBI_MAX_ERASECOUNTER)) {
+		/*
+		 * Erase counter overflow. Upgrade UBI and use 64-bit
+		 * erase counters internally.
+		 */
+		ubi_err("erase counter overflow at PEB %d, EC %d", pnum, ec);
+		return -EINVAL;
+	}
+
+	ec_hdr->ec = cpu_to_ubi64(ec);
+
+	err = ubi_io_sync_erase(ubi, pnum, 0);
+	if (unlikely(err < 0))
+		goto out_free;
+
+	err = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
+
+out_free:
+	kfree(ec_hdr);
+	return err;
+}
+
+/**
+ * ubi_scan_get_free_peb - get a free physical eraseblock.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ *
+ * This function returns a free physical eraseblock. It is supposed to be
+ * called on the UBI initialization stages when the wear-leveling unit is not
+ * initialized yet. This function picks a physical eraseblocks from one of the
+ * lists, writes the EC header if it is needed, and removes it from the list.
+ *
+ * This function returns scanning physical eraseblock information in case of
+ * success and an error code in case of failure.
+ */
+struct ubi_scan_leb *ubi_scan_get_free_peb(const struct ubi_device *ubi,
+					   struct ubi_scan_info *si)
+{
+	int err = 0, i;
+	struct ubi_scan_leb *seb;
+
+	if (!list_empty(&si->free)) {
+		seb = list_entry(si->free.next, struct ubi_scan_leb, u.list);
+		list_del(&seb->u.list);
+		dbg_bld("return free PEB %d, EC %d", seb->pnum, seb->ec);
+		return seb;
+	}
+
+	for (i = 0; i < 2; i++) {
+		struct list_head *head;
+		struct ubi_scan_leb *tmp_seb;
+
+		if (i == 0)
+			head = &si->erase;
+		else
+			head = &si->corr;
+
+		/*
+		 * We try to erase the first physical eraseblock from the @head
+		 * list and pick it if we succeed, or try to erase the
+		 * next one if not. And so forth. We don't want to take care
+		 * about bad eraseblocks here - they'll be handled later.
+		 */
+		list_for_each_entry_safe(seb, tmp_seb, head, u.list) {
+			if (seb->ec == UBI_SCAN_UNKNOWN_EC)
+				seb->ec = si->mean_ec;
+
+			err = ubi_scan_erase_peb(ubi, si, seb->pnum, seb->ec+1);
+			if (unlikely(err))
+				continue;
+
+			seb->ec += 1;
+			list_del(&seb->u.list);
+			dbg_bld("return PEB %d, EC %d", seb->pnum, seb->ec);
+			return seb;
+		}
+	}
+
+	ubi_err("no eraseblocks found");
+	return ERR_PTR(-ENOSPC);
+}
+
+/**
+ * process_eb - read UBI headers, check them and add corresponding data
+ * to the scanning information.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ * @pnum: the physical eraseblock number
+ *
+ * This function returns a zero if the physical eraseblock was succesfully
+ * handled and a negative error code in case of failure.
+ */
+static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si, int pnum)
+{
+	long long ec;
+	int err, bitflips = 0, vol_id, ec_corr = 0;
+
+	dbg_bld("scan PEB %d", pnum);
+
+	/* Skip bad physical eraseblocks */
+	err = ubi_io_is_bad(ubi, pnum);
+	if (unlikely(err < 0))
+		return err;
+	else if (err) {
+		/*
+		 * FIXME: this is actually duty of the I/O unit to initialize
+		 * this, but MTD does not provide enough information.
+		 */
+		si->bad_peb_count += 1;
+		return 0;
+	}
+
+	err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+	if (unlikely(err < 0))
+		return err;
+	else if (unlikely(err == UBI_IO_BITFLIPS))
+		bitflips = 1;
+	else if (err == UBI_IO_PEB_EMPTY)
+		return ubi_scan_add_to_list(si, pnum, UBI_SCAN_UNKNOWN_EC,
+					    &si->erase);
+	else if (err == UBI_IO_BAD_EC_HDR) {
+		/*
+		 * We have to also look at the VID header, possibly it is not
+		 * corrupted. Set %bitflips flag in order to make this PEB be
+		 * moved and EC be re-created.
+		 */
+		ec_corr = 1;
+		ec = UBI_SCAN_UNKNOWN_EC;
+		bitflips = 1;
+	}
+
+	si->is_empty = 0;
+
+	if (!ec_corr) {
+		/* Make sure UBI version is OK */
+		if (unlikely(ech->version != UBI_VERSION)) {
+			ubi_err("this UBI version is %d, image version is %d",
+				UBI_VERSION, (int)ech->version);
+			return -EINVAL;
+		}
+
+		ec = ubi64_to_cpu(ech->ec);
+		if (unlikely(ec > UBI_MAX_ERASECOUNTER)) {
+			/*
+			 * Erase counter overflow. The EC headers have 64 bits
+			 * reserved, but we anyway make use of only 31 bit
+			 * values, as this seems to be enough for any existing
+			 * flash. Upgrade UBI and use 64-bit erase counters
+			 * internally.
+			 */
+			ubi_err("erase counter overflow, max is %d",
+				UBI_MAX_ERASECOUNTER);
+			ubi_dbg_dump_ec_hdr(ech);
+			return -EINVAL;
+		}
+	}
+
+	/* OK, we've done with the EC header, let's look at the VID header */
+
+	err = ubi_io_read_vid_hdr(ubi, pnum, vidh, 0);
+	if (unlikely(err < 0))
+		return err;
+	else if (unlikely(err == UBI_IO_BITFLIPS))
+		bitflips = 1;
+	else if (unlikely(err == UBI_IO_BAD_VID_HDR ||
+		 (err == UBI_IO_PEB_FREE && ec_corr))) {
+		/* VID header is corrupted */
+		err = ubi_scan_add_to_list(si, pnum, ec, &si->corr);
+		if (err)
+			return err;
+		goto adjust_mean_ec;
+	} else if (err == UBI_IO_PEB_FREE) {
+		/* No VID header - the physical eraseblock is free */
+		err = ubi_scan_add_to_list(si, pnum, ec, &si->free);
+		if (unlikely(err))
+			return err;
+		goto adjust_mean_ec;
+	}
+
+	vol_id = ubi32_to_cpu(vidh->vol_id);
+	if (vol_id > UBI_MAX_VOLUMES && vol_id != UBI_LAYOUT_VOL_ID) {
+		int lnum = ubi32_to_cpu(vidh->lnum);
+
+		/* Unsupported internal volume */
+		switch (vidh->compat) {
+		case UBI_COMPAT_DELETE:
+			ubi_msg("\"delete\" compatible internal volume %d:%d"
+				" found, remove it", vol_id, lnum);
+			err = ubi_scan_add_to_list(si, pnum, ec, &si->corr);
+			if (unlikely(err))
+				return err;
+			break;
+
+		case UBI_COMPAT_RO:
+			ubi_msg("read-only compatible internal volume %d:%d"
+				" found, switch to read-only mode",
+				vol_id, lnum);
+			ubi->ro_mode = 1;
+			break;
+
+		case UBI_COMPAT_PRESERVE:
+			ubi_msg("\"preserve\" compatible internal volume %d:%d"
+				" found", vol_id, lnum);
+			err = ubi_scan_add_to_list(si, pnum, ec, &si->alien);
+			if (unlikely(err))
+				return err;
+			si->alien_peb_count += 1;
+			return 0;
+
+		case UBI_COMPAT_REJECT:
+			ubi_err("incompatible internal volume %d:%d found",
+				vol_id, lnum);
+			return -EINVAL;
+		}
+	}
+
+	/* Both UBI headers seem to be fine */
+	err = ubi_scan_add_used(ubi, si, pnum, ec, vidh, bitflips);
+	if (unlikely(err))
+		return err;
+
+adjust_mean_ec:
+	if (!ec_corr) {
+		if (si->ec_sum + ec < ec) {
+			commit_to_mean_value(si);
+			si->ec_sum = 0;
+			si->ec_count = 0;
+		} else {
+			si->ec_sum += ec;
+			si->ec_count += 1;
+		}
+
+		if (ec > si->max_ec)
+			si->max_ec = ec;
+		if (ec < si->min_ec)
+			si->min_ec = ec;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_scan - scan an MTD device.
+ * @ubi: UBI device description object
+ *
+ * This function does full scanning of an MTD device and returns complete
+ * information about it. In case of failure, an error code is returned.
+ */
+struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
+{
+	int err, pnum;
+	struct rb_node *rb1, *rb2;
+	struct ubi_scan_volume *sv;
+	struct ubi_scan_leb *seb;
+	struct ubi_scan_info *si;
+
+	si = kzalloc(sizeof(struct ubi_scan_info), GFP_KERNEL);
+	if (!si)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&si->corr);
+	INIT_LIST_HEAD(&si->free);
+	INIT_LIST_HEAD(&si->erase);
+	INIT_LIST_HEAD(&si->alien);
+	si->volumes = RB_ROOT;
+	si->is_empty = 1;
+
+	err = -ENOMEM;
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech)
+		goto out_si;
+
+	vidh = ubi_zalloc_vid_hdr(ubi);
+	if (!vidh)
+		goto out_ech;
+
+	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
+		cond_resched();
+
+		dbg_msg("process PEB %d", pnum);
+		err = process_eb(ubi, si, pnum);
+		if (unlikely(err < 0))
+			goto out_vidh;
+	}
+
+	dbg_msg("scanning is finished");
+
+	/* Finish mean erase counter calculations */
+	if (si->ec_count)
+		commit_to_mean_value(si);
+
+	if (si->is_empty)
+		ubi_msg("empty MTD device detected");
+
+	/*
+	 * In case of unknown erase counter we use the mean erase counter
+	 * value.
+	 */
+	ubi_rb_for_each_entry(rb1, sv, &si->volumes, rb) {
+		ubi_rb_for_each_entry(rb2, seb, &sv->root, u.rb)
+			if (seb->ec == UBI_SCAN_UNKNOWN_EC)
+				seb->ec = si->mean_ec;
+	}
+
+	list_for_each_entry(seb, &si->free, u.list) {
+		if (seb->ec == UBI_SCAN_UNKNOWN_EC)
+			seb->ec = si->mean_ec;
+	}
+
+	list_for_each_entry(seb, &si->corr, u.list)
+		if (seb->ec == UBI_SCAN_UNKNOWN_EC)
+			seb->ec = si->mean_ec;
+
+	list_for_each_entry(seb, &si->erase, u.list)
+		if (seb->ec == UBI_SCAN_UNKNOWN_EC)
+			seb->ec = si->mean_ec;
+
+	err = paranoid_check_si(ubi, si);
+	if (err) {
+		if (err > 0)
+			err = -EINVAL;
+		goto out_vidh;
+	}
+
+	ubi_free_vid_hdr(ubi, vidh);
+	kfree(ech);
+
+	return si;
+
+out_vidh:
+	ubi_free_vid_hdr(ubi, vidh);
+out_ech:
+	kfree(ech);
+out_si:
+	ubi_scan_destroy_si(si);
+	return ERR_PTR(err);
+}
+
+/**
+ * destroy_sv - free the scanning volume information
+ * @sv: scanning volume information
+ *
+ * This function destroys the volume RB-tree (@sv->root) and the scanning
+ * volume information.
+ */
+static void destroy_sv(struct ubi_scan_volume *sv)
+{
+	struct ubi_scan_leb *seb;
+	struct rb_node *this = sv->root.rb_node;
+
+	while (this) {
+		if (this->rb_left)
+			this = this->rb_left;
+		else if (this->rb_right)
+			this = this->rb_right;
+		else {
+			seb = rb_entry(this, struct ubi_scan_leb, u.rb);
+			this = rb_parent(this);
+			if (this) {
+				if (this->rb_left == &seb->u.rb)
+					this->rb_left = NULL;
+				else
+					this->rb_right = NULL;
+			}
+
+			kfree(seb);
+		}
+	}
+	kfree(sv);
+}
+
+/**
+ * ubi_scan_destroy_si - destroy scanning information.
+ * @si: scanning information
+ */
+void ubi_scan_destroy_si(struct ubi_scan_info *si)
+{
+	struct ubi_scan_leb *seb, *seb_tmp;
+	struct ubi_scan_volume *sv;
+	struct rb_node *rb;
+
+	list_for_each_entry_safe(seb, seb_tmp, &si->alien, u.list) {
+		list_del(&seb->u.list);
+		kfree(seb);
+	}
+	list_for_each_entry_safe(seb, seb_tmp, &si->erase, u.list) {
+		list_del(&seb->u.list);
+		kfree(seb);
+	}
+	list_for_each_entry_safe(seb, seb_tmp, &si->corr, u.list) {
+		list_del(&seb->u.list);
+		kfree(seb);
+	}
+	list_for_each_entry_safe(seb, seb_tmp, &si->free, u.list) {
+		list_del(&seb->u.list);
+		kfree(seb);
+	}
+
+	/* Destroy the volume RB-tree */
+	rb = si->volumes.rb_node;
+	while (rb) {
+		if (rb->rb_left)
+			rb = rb->rb_left;
+		else if (rb->rb_right)
+			rb = rb->rb_right;
+		else {
+			sv = rb_entry(rb, struct ubi_scan_volume, rb);
+
+			rb = rb_parent(rb);
+			if (rb) {
+				if (rb->rb_left == &sv->rb)
+					rb->rb_left = NULL;
+				else
+					rb->rb_right = NULL;
+			}
+
+			destroy_sv(sv);
+		}
+	}
+
+	kfree(si);
+}
+
+#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
+
+/**
+ * paranoid_check_si - check if the scanning information is correct and
+ * consistent.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ *
+ * This function returns zero if the scanning information is all right, %1 if
+ * not and a negative error code if an error occurred.
+ */
+static int paranoid_check_si(const struct ubi_device *ubi,
+			     struct ubi_scan_info *si)
+{
+	int pnum, err, vols_found = 0;
+	struct rb_node *rb1, *rb2;
+	struct ubi_scan_volume *sv;
+	struct ubi_scan_leb *seb, *last_seb;
+	uint8_t *buf;
+
+	/*
+	 * At first, check that scanning information is ok.
+	 */
+	ubi_rb_for_each_entry(rb1, sv, &si->volumes, rb) {
+		int leb_count = 0;
+
+		cond_resched();
+
+		vols_found += 1;
+
+		if (unlikely(si->is_empty)) {
+			ubi_err("bad is_empty flag");
+			goto bad_sv;
+		}
+
+		if (unlikely(sv->vol_id < 0 || sv->highest_lnum < 0 ||
+			     sv->leb_count < 0 || sv->vol_type < 0 ||
+			     sv->used_ebs < 0 || sv->data_pad < 0 ||
+			     sv->last_data_size < 0)) {
+			ubi_err("negative values");
+			goto bad_sv;
+		}
+
+		if (unlikely(sv->vol_id >= UBI_MAX_VOLUMES &&
+			     sv->vol_id < UBI_INTERNAL_VOL_START)) {
+			ubi_err("bad vol_id");
+			goto bad_sv;
+		}
+
+		if (unlikely(sv->vol_id > si->highest_vol_id)) {
+			ubi_err("highest_vol_id is %d, but vol_id %d is there",
+				si->highest_vol_id, sv->vol_id);
+			goto out;
+		}
+
+		if (unlikely(sv->vol_type != UBI_DYNAMIC_VOLUME &&
+			     sv->vol_type != UBI_STATIC_VOLUME)) {
+			ubi_err("bad vol_type");
+			goto bad_sv;
+		}
+
+		if (unlikely(sv->data_pad > ubi->leb_size / 2)) {
+			ubi_err("bad data_pad");
+			goto bad_sv;
+		}
+
+		last_seb = NULL;
+		ubi_rb_for_each_entry(rb2, seb, &sv->root, u.rb) {
+			cond_resched();
+
+			last_seb = seb;
+			leb_count += 1;
+
+			if (unlikely(seb->pnum < 0 || seb->ec < 0)) {
+				ubi_err("negative values");
+				goto bad_seb;
+			}
+
+			if (unlikely(seb->ec < si->min_ec)) {
+				ubi_err("bad si->min_ec (%d), %d found",
+					si->min_ec, seb->ec);
+				goto bad_seb;
+			}
+
+			if (unlikely(seb->ec > si->max_ec)) {
+				ubi_err("bad si->max_ec (%d), %d found",
+					si->max_ec, seb->ec);
+				goto bad_seb;
+			}
+
+			if (unlikely(seb->pnum >= ubi->peb_count)) {
+				ubi_err("too high PEB number %d, total PEBs %d",
+					seb->pnum, ubi->peb_count);
+				goto bad_seb;
+			}
+
+			if (sv->vol_type == UBI_STATIC_VOLUME) {
+				if (unlikely(seb->lnum >= sv->used_ebs)) {
+					ubi_err("bad lnum or used_ebs");
+					goto bad_seb;
+				}
+			} else {
+				if (unlikely(sv->used_ebs != 0)) {
+					ubi_err("non-zero used_ebs");
+					goto bad_seb;
+				}
+			}
+
+			if (unlikely(seb->lnum > sv->highest_lnum)) {
+				ubi_err("incorrect highest_lnum or lnum");
+				goto bad_seb;
+			}
+		}
+
+		if (unlikely(sv->leb_count != leb_count)) {
+			ubi_err("bad leb_count, %d objects in the tree",
+				leb_count);
+			goto bad_sv;
+		}
+
+		if (!last_seb)
+			continue;
+
+		seb = last_seb;
+
+		if (unlikely(seb->lnum != sv->highest_lnum)) {
+			ubi_err("bad highest_lnum");
+			goto bad_seb;
+		}
+	}
+
+	if (vols_found != si->vols_found) {
+		ubi_err("bad si->vols_found %d, should be %d",
+			si->vols_found, vols_found);
+		goto out;
+	}
+
+	/* Check that scanning information is correct */
+	ubi_rb_for_each_entry(rb1, sv, &si->volumes, rb) {
+		last_seb = NULL;
+		ubi_rb_for_each_entry(rb2, seb, &sv->root, u.rb) {
+			int vol_type;
+
+			cond_resched();
+
+			last_seb = seb;
+
+			err = ubi_io_read_vid_hdr(ubi, seb->pnum, vidh, 1);
+			if (unlikely(err) && err != UBI_IO_BITFLIPS) {
+				ubi_err("VID header is not OK (%d)", err);
+				if (err > 0)
+					err = -EIO;
+				return err;
+			}
+
+			vol_type = vidh->vol_type == UBI_VID_DYNAMIC ?
+				   UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
+			if (unlikely(sv->vol_type != vol_type)) {
+				ubi_err("bad vol_type");
+				goto bad_vid_hdr;
+			}
+
+			if (unlikely(seb->sqnum != ubi64_to_cpu(vidh->sqnum))) {
+				ubi_err("bad sqnum %llu", seb->sqnum);
+				goto bad_vid_hdr;
+			}
+
+			if (unlikely(sv->vol_id !=
+				     ubi32_to_cpu(vidh->vol_id))) {
+				ubi_err("bad vol_id %d", sv->vol_id);
+				goto bad_vid_hdr;
+			}
+
+			if (unlikely(sv->compat != vidh->compat)) {
+				ubi_err("bad compat %d", vidh->compat);
+				goto bad_vid_hdr;
+			}
+
+			if (unlikely(seb->lnum != ubi32_to_cpu(vidh->lnum))) {
+				ubi_err("bad lnum %d", seb->lnum);
+				goto bad_vid_hdr;
+			}
+
+			if (unlikely(sv->used_ebs !=
+				     ubi32_to_cpu(vidh->used_ebs))) {
+				ubi_err("bad used_ebs %d", sv->used_ebs);
+				goto bad_vid_hdr;
+			}
+
+			if (unlikely(sv->data_pad !=
+				     ubi32_to_cpu(vidh->data_pad))) {
+				ubi_err("bad data_pad %d", sv->data_pad);
+				goto bad_vid_hdr;
+			}
+
+			if (unlikely(seb->leb_ver !=
+				     ubi32_to_cpu(vidh->leb_ver))) {
+				ubi_err("bad leb_ver %u", seb->leb_ver);
+				goto bad_vid_hdr;
+			}
+		}
+
+		if (!last_seb)
+			continue;
+
+		if (unlikely(sv->highest_lnum != ubi32_to_cpu(vidh->lnum))) {
+			ubi_err("bad highest_lnum %d", sv->highest_lnum);
+			goto bad_vid_hdr;
+		}
+
+		if (unlikely(sv->last_data_size !=
+			     ubi32_to_cpu(vidh->data_size))) {
+			ubi_err("bad last_data_size %d", sv->last_data_size);
+			goto bad_vid_hdr;
+		}
+	}
+
+	/*
+	 * Make sure that all the physical eraseblocks are in one of the lists
+	 * or trees.
+	 */
+	buf = kmalloc(ubi->peb_count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	memset(buf, 1, ubi->peb_count);
+	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
+		err = ubi_io_is_bad(ubi, pnum);
+		if (unlikely(err < 0))
+			return err;
+		else if (err)
+			buf[pnum] = 0;
+	}
+
+	ubi_rb_for_each_entry(rb1, sv, &si->volumes, rb)
+		ubi_rb_for_each_entry(rb2, seb, &sv->root, u.rb)
+			buf[seb->pnum] = 0;
+
+	list_for_each_entry(seb, &si->free, u.list)
+		buf[seb->pnum] = 0;
+
+	list_for_each_entry(seb, &si->corr, u.list)
+		buf[seb->pnum] = 0;
+
+	list_for_each_entry(seb, &si->erase, u.list)
+		buf[seb->pnum] = 0;
+
+	list_for_each_entry(seb, &si->alien, u.list)
+		buf[seb->pnum] = 0;
+
+	err = 0;
+	for (pnum = 0; pnum < ubi->peb_count; pnum++)
+		if (unlikely(buf[pnum])) {
+			ubi_err("PEB %d is not referred", pnum);
+			err = 1;
+		}
+
+	kfree(buf);
+	if (err)
+		goto out;
+	return 0;
+
+bad_seb:
+	ubi_err("bad scanning information about LEB %d", seb->lnum);
+	ubi_dbg_dump_seb(seb, 0);
+	ubi_dbg_dump_sv(sv);
+	goto out;
+
+bad_sv:
+	ubi_err("bad scanning information about volume %d", sv->vol_id);
+	ubi_dbg_dump_sv(sv);
+	goto out;
+
+bad_vid_hdr:
+	ubi_err("bad scanning information about volume %d", sv->vol_id);
+	ubi_dbg_dump_sv(sv);
+	ubi_dbg_dump_vid_hdr(vidh);
+
+out:
+	ubi_dbg_dump_stack();
+	return 1;
+}
+
+#endif /* CONFIG_MTD_UBI_DEBUG_PARANOID */

167 lines not on this page · raw message

diff -auNrp tmp-from/drivers/mtd/ubi/io.c tmp-to/drivers/mtd/ubi/io.c
@@ -0,0 +1,1263 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2006, 2007
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * UBI input/output unit.
+ *
+ * This unit provides a uniform way to work with all kinds of the underlying
+ * MTD devices. It also implements handy functions for reading and writing UBI
+ * headers.
+ *
+ * We are trying to have a paranoid mindset and not to trust to what we read
+ * from the flash media in order to be more secure and robust. So this unit
+ * validates every single header it reads from the flash media.
+ *
+ * Some words about how the eraseblock headers are stored.
+ *
+ * The erase counter header is always stored at offset zero. By default, the
+ * VID header is stored after the EC header at the closest aligned offset
+ * (i.e. aligned to the minimum I/O unit size). Data starts next to the VID
+ * header at the closest aligned offset. But this default layout may be
+ * changed. For example, for different reasons (e.g., optimization) UBI may be
+ * asked to put the VID header at further offset, and even at an unaligned
+ * offset. Of course, if the offset of the VID header is unaligned, UBI adds
+ * proper padding in front of it. Data offset may also be changed but it has to
+ * be aligned.
+ *
+ * About minimal I/O units. In general, UBI assumes flash device model where
+ * there is only one minimal I/O unit size. E.g., in case of NOR flash it is 1,
+ * in case of NAND flash it is a NAND page, etc. This is reported by MTD in the
+ * @ubi->mtd->writesize field. But as an exception, UBI admits of using another
+ * (smaller) minimal I/O unit size for EC and VID headers to make it possible
+ * to do different optimizations.
+ *
+ * This is extremely useful in case of NAND flashes which admit of several
+ * write operations to one NAND page. In this case UBI can fit EC and VID
+ * headers at one NAND page. Thus, UBI may use "sub-page" size as the minimal
+ * I/O unit for the headers (the @ubi->hdrs_min_io_size field). But it still
+ * reports NAND page size (@ubi->min_io_size) as a minimal I/O unit for the UBI
+ * users.
+ *
+ * Example: some Samsung NANDs with 2KiB pages allow 4x 512-byte writes, so
+ * although the minimal I/O unit is 2K, UBI uses 512 bytes for EC and VID
+ * headers.
+ *
+ * Q: why not just to treat sub-page as a minimal I/O unit of this flash
+ * device, e.g., make @ubi->min_io_size = 512 in the example above?
+ *
+ * A: because when writing a sub-page, MTD still writes a full 2K page but the
+ * bytes which are no relevant to the sub-page are 0xFF. So, basically, writing
+ * 4x512 sub-pages is 4 times slower then writing one 2KiB NAND page. Thus, we
+ * prefer to use sub-pages only for EV and VID headers.
+ *
+ * As it was noted above, the VID header may start at a non-aligned offset.
+ * For example, in case of a 2KiB page NAND flash with a 512 bytes sub-page,
+ * the VID header may reside at offset 1984 which is the last 64 bytes of the
+ * last sub-page (EC header is always at offset zero). This causes some
+ * difficulties when reading and writing VID headers.
+ *
+ * Suppose we have a 64-byte buffer and we read a VID header at it. We change
+ * the data and want to write this VID header out. As we can only write in
+ * 512-byte chunks, we have to allocate one more buffer and copy our VID header
+ * to offset 448 of this buffer.
+ *
+ * The I/O unit does the following trick in order to avoid this extra copy.
+ * It always allocates a @ubi->vid_hdr_alsize bytes buffer for the VID header
+ * and returns a pointer to offset @ubi->vid_hdr_shift of this buffer. When the
+ * VID header is being written out, it shifts the VID header pointer back and
+ * writes the whole sub-page.
+ */
+
+#include <linux/crc32.h>
+#include <linux/err.h>
+#include "ubi.h"
+
+#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
+static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum);
+static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum);
+static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
+				 const struct ubi_ec_hdr *ec_hdr);
+static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum);
+static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
+				  const struct ubi_vid_hdr *vid_hdr);
+static int paranoid_check_all_ff(const struct ubi_device *ubi, int pnum,
+				 int offset, int len);
+#else
+#define paranoid_check_not_bad(ubi, pnum) 0
+#define paranoid_check_peb_ec_hdr(ubi, pnum)  0
+#define paranoid_check_ec_hdr(ubi, pnum, ec_hdr)  0
+#define paranoid_check_peb_vid_hdr(ubi, pnum) 0
+#define paranoid_check_vid_hdr(ubi, pnum, vid_hdr) 0
+#define paranoid_check_all_ff(ubi, pnum, offset, len) 0
+#endif
+
+/**
+ * ubi_io_read - read data from a physical eraseblock.
+ * @ubi: UBI device description object
+ * @buf: buffer where to store the read data
+ * @pnum: physical eraseblock number to read from
+ * @offset: offset within the physical eraseblock from where to read
+ * @len: how many bytes to read
+ *
+ * This function reads data from offset @offset of physical eraseblock @pnum
+ * and stores the read data in the @buf buffer. The following return codes are
+ * possible:
+ *
+ * o %0 if all the requested data were successfully read;
+ * o %UBI_IO_BITFLIPS if all the requested data were successfully read, but
+ *   correctable bit-flips were detected; this is harmless but may indicate
+ *   that this eraseblock may become bad soon (but do not have to);
+ * o %-EBADMSG if the MTD subsystem reported about data data integrity
+ *   problems, for example it can me an ECC error in case of NAND; this most
+ *   probably means that the data is corrupted;
+ * o %-EIO if some I/O error occurred;
+ * o other negative error codes in case of other errors.
+ */
+int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
+		int len)
+{
+	int err, retries = 0;
+	size_t read;
+	loff_t addr;
+
+	dbg_io("read %d bytes from PEB %d:%d", len, pnum, offset);
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+	ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
+	ubi_assert(len > 0);
+
+	err = paranoid_check_not_bad(ubi, pnum);
+	if (unlikely(err))
+		return err > 0 ? -EINVAL : err;
+
+	addr = (loff_t)pnum * ubi->peb_size + offset;
+retry:
+	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
+	if (unlikely(err)) {
+		if (err == -EUCLEAN) {
+			/*
+			 * -EUCLEAN is reported if there was a bit-flip which
+			 * was corrected, so this is harmless.
+			 */
+			ubi_msg("fixable bit-flip detected at PEB %d", pnum);
+			ubi_assert(len == read);
+			return UBI_IO_BITFLIPS;
+		}
+
+		if (read != len && retries++ < UBI_IO_RETRIES) {
+			dbg_io("error %d while reading %d bytes from PEB %d:%d, "
+			       "read only %zd bytes, retry",
+			       err, len, pnum, offset, read);
+			yield();
+			goto retry;
+		}
+
+		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
+			"read %zd bytes", err, len, pnum, offset, read);
+		ubi_dbg_dump_stack();
+	} else {
+		ubi_assert(len == read);
+
+		if (ubi_dbg_is_bitflip()) {
+			ubi_msg("bit-flip (emulated)");
+			err = UBI_IO_BITFLIPS;
+		}
+	}
+
+	return err;
+}
+
+/**
+ * ubi_io_write - write data to a physical eraseblock.
+ * @ubi: UBI device description object
+ * @buf: buffer with the data to write
+ * @pnum: physical eraseblock number to write to
+ * @offset: offset within the physical eraseblock where to write
+ * @len: how many bytes to write
+ *
+ * This function writes @len bytes of data from buffer @buf to offset @offset
+ * of physical eraseblock @pnum. If all the data were successfully written,
+ * zero is returned. If an error occurred, this function returns a negative
+ * error code. If %-EIO is returned, the physical eraseblock most probably went
+ * bad.
+ *
+ * Note, in case of an error, it is possible that something was still written
+ * to the flash media, but may be some garbage.
+ */
+int ubi_io_write(const struct ubi_device *ubi, const void *buf, int pnum,
+		 int offset, int len)
+{
+	int err;
+	size_t written;
+	loff_t addr;
+
+	dbg_io("write %d bytes to PEB %d:%d", len, pnum, offset);
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+	ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
+	ubi_assert(offset % ubi->hdrs_min_io_size == 0);
+	ubi_assert(len > 0 && len % ubi->hdrs_min_io_size == 0);
+
+	if (unlikely(ubi->ro_mode)) {
+		ubi_err("read-only mode");
+		return -EROFS;
+	}
+
+	/* The below has to be compiled out if paranoid checks are disabled */
+
+	err = paranoid_check_not_bad(ubi, pnum);
+	if (unlikely(err))
+		return err > 0 ? -EINVAL : err;
+
+	/* The area we are writing to has to contain all 0xFF bytes */
+	err = paranoid_check_all_ff(ubi, pnum, offset, len);
+	if (unlikely(err))
+		return err > 0 ? -EINVAL : err;
+
+	if (offset >= ubi->leb_start) {
+		/*
+		 * We write to the data area of the physical eraseblock. Make
+		 * sure it has valid EC and VID headers.
+		 */
+		err = paranoid_check_peb_ec_hdr(ubi, pnum);
+		if (unlikely(err))
+			return err > 0 ? -EINVAL : err;
+		err = paranoid_check_peb_vid_hdr(ubi, pnum);
+		if (unlikely(err))
+			return err > 0 ? -EINVAL : err;
+	}
+
+	if (ubi_dbg_is_write_failure()) {
+		ubi_err("cannot write %d bytes to PEB %d:%d "
+			"(emulated)", len, pnum, offset);
+		ubi_dbg_dump_stack();
+		return -EIO;
+	}
+
+	addr = (loff_t)pnum * ubi->peb_size + offset;
+	err = ubi->mtd->write(ubi->mtd, addr, len, &written, buf);
+	if (unlikely(err)) {
+		ubi_err("error %d while writing %d bytes to PEB %d:%d, written"
+			" %zd bytes", err, len, pnum, offset, written);
+		ubi_dbg_dump_stack();
+	} else
+		ubi_assert(written == len);
+
+	return err;
+}
+
+/**
+ * erase_callback - MTD erasure call-back.
+ * @ei: MTD erase information object.
+ *
+ * Note, even though MTD erase interface is asynchronous, all the current
+ * implementations are synchronous anyway.
+ */
+static void erase_callback(struct erase_info *ei)
+{
+	wake_up_interruptible((wait_queue_head_t *)ei->priv);
+}
+
+/**
+ * do_sync_erase - synchronously erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to erase
+ *
+ * This function synchronously erases physical eraseblock @pnum and returns
+ * zero in case of success and a negative error code in case of failure. If
+ * %-EIO is returned, the physical eraseblock most probably went bad.
+ */
+static int do_sync_erase(const struct ubi_device *ubi, int pnum)
+{
+	int err, retries = 0;
+	struct erase_info ei;
+	wait_queue_head_t wq;
+
+	dbg_io("erase PEB %d", pnum);
+
+retry:
+	init_waitqueue_head(&wq);
+	memset(&ei, 0, sizeof(struct erase_info));
+
+	ei.mtd      = ubi->mtd;
+	ei.addr     = pnum * ubi->peb_size;
+	ei.len      = ubi->peb_size;
+	ei.callback = erase_callback;
+	ei.priv     = (unsigned long)&wq;
+
+	err = ubi->mtd->erase(ubi->mtd, &ei);
+	if (unlikely(err)) {
+		if (retries++ < UBI_IO_RETRIES) {
+			dbg_io("error %d while erasing PEB %d, retry",
+			       err, pnum);
+			yield();
+			goto retry;
+		}
+		ubi_err("cannot erase PEB %d, error %d", pnum, err);
+		ubi_dbg_dump_stack();
+		return err;
+	}
+
+	err = wait_event_interruptible(wq, ei.state == MTD_ERASE_DONE ||
+					   ei.state == MTD_ERASE_FAILED);
+	if (unlikely(err)) {
+		ubi_err("interrupted PEB %d erasure", pnum);
+		return -EINTR;
+	}
+
+	if (unlikely(ei.state == MTD_ERASE_FAILED)) {
+		if (retries++ < UBI_IO_RETRIES) {
+			dbg_io("error while erasing PEB %d, retry", pnum);
+			yield();
+			goto retry;
+		}
+		ubi_err("cannot erase PEB %d", pnum);
+		ubi_dbg_dump_stack();
+		return -EIO;
+	}
+
+	err = paranoid_check_all_ff(ubi, pnum, 0, ubi->peb_size);
+	if (unlikely(err))
+		return err > 0 ? -EINVAL : err;
+
+	if (ubi_dbg_is_erase_failure() && !err) {
+		ubi_err("cannot erase PEB %d (emulated)", pnum);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * check_pattern - check if buffer contains only a certain byte pattern.
+ * @buf: buffer to check
+ * @patt: the pattern to check
+ * @size: buffer size in bytes
+ *
+ * This function returns %1 in there are only @patt bytes in @buf, and %0 if
+ * something else was also found.
+ */
+static int check_pattern(const void *buf, uint8_t patt, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		if (((const uint8_t *)buf)[i] != patt)
+			return 0;
+	return 1;
+}
+
+/* Patterns to write to a physical eraseblock when torturing it */
+static uint8_t patterns[] = {0xa5, 0x5a, 0x0};
+
+/**
+ * torture_peb - test a supposedly bad physical eraseblock.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to test
+ *
+ * This function returns %-EIO if the physical eraseblock did not pass the
+ * test, a positive number of erase operations done if the test was
+ * successfully passed, and other negative error codes in case of other errors.
+ */
+static int torture_peb(const struct ubi_device *ubi, int pnum)
+{
+	void *buf;
+	int err, i, patt_count;
+
+	buf = kmalloc(ubi->peb_size, GFP_KERNEL);
+	if (unlikely(!buf))
+		return -ENOMEM;
+
+	patt_count = ARRAY_SIZE(patterns);
+	ubi_assert(patt_count > 0);
+
+	for (i = 0; i < patt_count; i++) {
+		err = do_sync_erase(ubi, pnum);
+		if (unlikely(err))
+			goto out;
+
+		/* Make sure the PEB contains only 0xFF bytes */
+		err = ubi_io_read(ubi, buf, pnum, 0, ubi->peb_size);
+		if (unlikely(err))
+			goto out;
+
+		err = check_pattern(buf, 0xFF, ubi->peb_size);
+		if (unlikely(err == 0)) {
+			ubi_err("erased PEB %d, but a non-0xFF byte found",
+				pnum);
+			err = -EIO;
+			goto out;
+		}
+
+		/* Write a pattern and check it */
+		memset(buf, patterns[i], ubi->peb_size);
+		err = ubi_io_write(ubi, buf, pnum, 0, ubi->peb_size);
+		if (unlikely(err))
+			goto out;
+
+		memset(buf, ~patterns[i], ubi->peb_size);
+		err = ubi_io_read(ubi, buf, pnum, 0, ubi->peb_size);
+		if (unlikely(err))
+			goto out;
+
+		err = check_pattern(buf, patterns[i], ubi->peb_size);
+		if (unlikely(err == 0)) {
+			ubi_err("pattern %x checking failed for PEB %d",
+				patterns[i], pnum);
+			err = -EIO;
+			goto out;
+		}
+	}
+
+	err = patt_count;
+
+out:
+	if (unlikely(err == UBI_IO_BITFLIPS || err == -EBADMSG))
+		/*
+		 * If a bit-flip or data integrity error was detected, the test
+		 * has not passed because it happened on a freshly erased
+		 * physical eraseblock which means something is wrong with it.
+		 */
+		err = -EIO;
+	kfree(buf);
+	return err;
+}
+
+/**
+ * ubi_io_sync_erase - synchronously erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number to erase
+ * @torture: if this physical eraseblock has to be tortured
+ *
+ * This function synchronously erases physical eraseblock @pnum. If @torture
+ * flag is not zero, the physical eraseblock is checked by means of writing
+ * different patterns to it and reading them back. If the torturing is enabled,
+ * the physical eraseblock is erased more then once.
+ *
+ * This function returns the number of erasures made in case of success, %-EIO
+ * if the erasure failed or the torturing test failed, and other negative error
+ * codes in case of other errors. Note, %-EIO means that the physical
+ * eraseblock is bad.
+ */
+int ubi_io_sync_erase(const struct ubi_device *ubi, int pnum, int torture)
+{
+	int err, ret = 0;
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	err = paranoid_check_not_bad(ubi, pnum);
+	if (unlikely(err != 0))
+		return err > 0 ? -EINVAL : err;
+
+	if (unlikely(ubi->ro_mode)) {
+		ubi_err("read-only mode");
+		return -EROFS;
+	}
+
+	if (torture) {
+		ret = torture_peb(ubi, pnum);
+		if (unlikely(ret < 0))
+			return ret;
+	}
+
+	err = do_sync_erase(ubi, pnum);
+	if (unlikely(err))
+		return err;
+
+	return ret + 1;
+}
+
+/**
+ * ubi_io_is_bad - check if a physical eraseblock is bad.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ *
+ * This function returns a positive number if the physical eraseblock is bad,
+ * zero if not, and a negative error code if an error occurred.
+ */
+int ubi_io_is_bad(const struct ubi_device *ubi, int pnum)
+{
+	struct mtd_info *mtd = ubi->mtd;
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	if (ubi->bad_allowed) {
+		int ret;
+
+		ret = mtd->block_isbad(mtd, (loff_t)pnum * ubi->peb_size);
+		if (unlikely(ret < 0))
+			ubi_err("error %d while checking if PEB %d is bad",
+				ret, pnum);
+		else if (ret)
+			dbg_io("PEB %d is bad", pnum);
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_io_mark_bad - mark a physical eraseblock as bad.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to mark
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+	struct mtd_info *mtd = ubi->mtd;
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	if (unlikely(ubi->ro_mode)) {
+		ubi_err("read-only mode");
+		return -EROFS;
+	}
+
+	if (!ubi->bad_allowed)
+		return 0;
+
+	err = mtd->block_markbad(mtd, (loff_t)pnum * ubi->peb_size);
+	if (unlikely(err))
+		ubi_err("cannot mark PEB %d bad, error %d", pnum, err);
+	return err;
+}
+
+/**
+ * validate_ec_hdr - validate an erase counter header.
+ * @ubi: UBI device description object
+ * @ec_hdr: the erase counter header to check
+ *
+ * This function returns zero if the erase counter header is OK, and %1 if
+ * not.
+ */
+static int validate_ec_hdr(const struct ubi_device *ubi,
+			   const struct ubi_ec_hdr *ec_hdr)
+{
+	long long ec;
+	int vid_hdr_offset, leb_start;
+
+	ec = ubi64_to_cpu(ec_hdr->ec);
+	vid_hdr_offset = ubi32_to_cpu(ec_hdr->vid_hdr_offset);
+	leb_start = ubi32_to_cpu(ec_hdr->data_offset);
+
+	if (unlikely(ec_hdr->version != UBI_VERSION)) {
+		ubi_err("node with incompatible UBI version found: "
+			"this UBI version is %d, image version is %d",
+			UBI_VERSION, (int)ec_hdr->version);
+		goto bad;
+	}
+
+	if (unlikely(vid_hdr_offset != ubi->vid_hdr_offset)) {
+		ubi_err("bad VID header offset %d, expected %d",
+			vid_hdr_offset, ubi->vid_hdr_offset);
+		goto bad;
+	}
+
+	if (unlikely(leb_start != ubi->leb_start)) {
+		ubi_err("bad data offset %d, expected %d",
+			leb_start, ubi->leb_start);
+		goto bad;
+	}
+
+	if (unlikely(ec < 0 || ec > UBI_MAX_ERASECOUNTER)) {
+		ubi_err("bad erase counter %lld", ec);
+		goto bad;
+	}
+
+	return 0;
+
+bad:
+	ubi_err("bad EC header");
+	ubi_dbg_dump_ec_hdr(ec_hdr);
+	ubi_dbg_dump_stack();
+	return 1;
+}
+
+/**
+ * ubi_io_read_ec_hdr - read and check an erase counter header.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock to read from
+ * @ec_hdr: a &struct ubi_ec_hdr object where to store the read erase counter
+ * header
+ * @verbose: be verbose if the header is corrupted or was not found
+ *
+ * This function reads erase counter header from physical eraseblock @pnum and
+ * stores it in @ec_hdr. This function also checks CRC checksum of the read
+ * erase counter header. The following codes may be returned:
+ *
+ * o %0 if the CRC checksum is correct and the header was successfully read;
+ * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
+ *   and corrected by the flash driver; this is harmless but may indicate that
+ *   this eraseblock may become bad soon (but may be not);
+ * o %UBI_IO_BAD_EC_HDR if the erase counter header is corrupted (a CRC error);
+ * o %UBI_IO_PEB_EMPTY if the physical eraseblock is empty;
+ * o a negative error code in case of failure.
+ */
+int ubi_io_read_ec_hdr(const struct ubi_device *ubi, int pnum,
+		       struct ubi_ec_hdr *ec_hdr, int verbose)
+{
+	int err, read_err = 0;
+	uint32_t crc, magic, hdr_crc;
+
+	dbg_io("read EC header from PEB %d", pnum);
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
+	if (unlikely(err)) {
+		if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
+			return err;
+
+		/*
+		 * We read all the data, but either a correctable bit-flip
+		 * occurred, or MTD reported about some data integrity error,
+		 * like an ECC error in case of NAND. The former is harmless,
+		 * the later may mean that the read data is corrupted. But we
+		 * have a CRC check-sum and we will detect this. If the EC
+		 * header is still OK, we just report this as there was a
+		 * bit-flip.
+		 */
+		read_err = err;
+	}
+
+	magic = ubi32_to_cpu(ec_hdr->magic);
+	if (unlikely(magic != UBI_EC_HDR_MAGIC)) {
+		/*
+		 * The magic field is wrong. Let's check if we have read all
+		 * 0xFF. If yes, this physical eraseblock is assumed to be
+		 * empty.
+		 *
+		 * But if there was a read error, we do not test it for all
+		 * 0xFFs. Even if it does contain all 0xFFs, this error
+		 * indicates that something is still wrong with this physical
+		 * eraseblock and we anyway cannot treat it as empty.
+		 */
+		if (read_err != -EBADMSG &&
+		    check_pattern(ec_hdr, 0xFF, UBI_EC_HDR_SIZE)) {
+			/* The physical eraseblock is supposedly empty */
+
+			/*
+			 * The below is just a paranoid check, it has to be
+			 * compiled out if paranoid checks are disabled.
+			 */
+			err = paranoid_check_all_ff(ubi, pnum, 0,
+						    ubi->peb_size);
+			if (unlikely(err))
+				return err > 0 ? UBI_IO_BAD_EC_HDR : err;
+
+			if (verbose)
+				ubi_warn("no EC header found at PEB %d, "
+					 "only 0xFF bytes", pnum);
+			return UBI_IO_PEB_EMPTY;
+		}
+
+		/*
+		 * This is not a valid erase counter header, and these are not
+		 * 0xFF bytes. Report that the header is corrupted.
+		 */
+		if (verbose) {
+			ubi_warn("bad magic number at PEB %d: %08x instead of "
+				 "%08x", pnum, magic, UBI_EC_HDR_MAGIC);
+			ubi_dbg_dump_ec_hdr(ec_hdr);
+		}
+		return UBI_IO_BAD_EC_HDR;
+	}
+
+	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
+	hdr_crc = ubi32_to_cpu(ec_hdr->hdr_crc);
+
+	if (unlikely(hdr_crc != crc)) {
+		if (verbose) {
+			ubi_warn("bad EC header CRC at PEB %d, calculated %#08x,"
+				 " read %#08x", pnum, crc, hdr_crc);
+			ubi_dbg_dump_ec_hdr(ec_hdr);
+		}
+		return UBI_IO_BAD_EC_HDR;
+	}
+
+	/* And of course validate what has just been read from the media */
+	err = validate_ec_hdr(ubi, ec_hdr);
+	if (unlikely(err)) {
+		ubi_err("validation failed for PEB %d", pnum);
+		return -EINVAL;
+	}
+
+	return read_err ? UBI_IO_BITFLIPS : 0;
+}
+
+/**
+ * ubi_io_write_ec_hdr - write an erase counter header.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock to write to
+ * @ec_hdr: the erase counter header to write
+ *
+ * This function writes erase counter header described by @ec_hdr to physical
+ * eraseblock @pnum. It also fills most fields of @ec_hdr before writing, so
+ * the caller do not have to fill them. Callers must only fill the @ec_hdr->ec
+ * field.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure. If %-EIO is returned, the physical eraseblock most probably
+ * went bad.
+ */
+int ubi_io_write_ec_hdr(const struct ubi_device *ubi, int pnum,
+			struct ubi_ec_hdr *ec_hdr)
+{
+	int err;
+	uint32_t crc;
+
+	dbg_io("write EC header to PEB %d", pnum);
+	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
+
+	ec_hdr->magic = cpu_to_ubi32(UBI_EC_HDR_MAGIC);
+	ec_hdr->version = UBI_VERSION;
+	ec_hdr->vid_hdr_offset = cpu_to_ubi32(ubi->vid_hdr_offset);
+	ec_hdr->data_offset = cpu_to_ubi32(ubi->leb_start);
+	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
+	ec_hdr->hdr_crc = cpu_to_ubi32(crc);
+
+	err = paranoid_check_ec_hdr(ubi, pnum, ec_hdr);
+	if (unlikely(err))
+		return -EINVAL;
+
+	err = ubi_io_write(ubi, ec_hdr, pnum, 0, ubi->ec_hdr_alsize);
+	return err;
+}
+
+/**
+ * validate_vid_hdr - validate a volume identifier header.
+ * @ubi: UBI device description object
+ * @vid_hdr: the volume identifier header to check
+ *
+ * This function checks that data stored in the volume identifier header
+ * @vid_hdr. Returns zero if the VID header is OK and %1 if not.
+ */
+static int validate_vid_hdr(const struct ubi_device *ubi,
+			    const struct ubi_vid_hdr *vid_hdr)
+{
+	int vol_type = vid_hdr->vol_type;
+	int copy_flag = vid_hdr->copy_flag;
+	int vol_id = ubi32_to_cpu(vid_hdr->vol_id);
+	int lnum = ubi32_to_cpu(vid_hdr->lnum);
+	int compat = vid_hdr->compat;
+	int data_size = ubi32_to_cpu(vid_hdr->data_size);
+	int used_ebs = ubi32_to_cpu(vid_hdr->used_ebs);
+	int data_pad = ubi32_to_cpu(vid_hdr->data_pad);
+	int data_crc = ubi32_to_cpu(vid_hdr->data_crc);
+	int usable_leb_size = ubi->leb_size - data_pad;
+
+	if (unlikely(copy_flag != 0 && copy_flag != 1)) {
+		dbg_err("bad copy_flag");
+		goto bad;
+	}
+
+	if (unlikely(vol_id < 0 || lnum < 0 || data_size < 0 || used_ebs < 0 ||
+		     data_pad < 0)) {
+		dbg_err("negative values");
+		goto bad;
+	}
+
+	if (unlikely(vol_id >= UBI_MAX_VOLUMES &&
+		     vol_id < UBI_INTERNAL_VOL_START)) {
+		dbg_err("bad vol_id");
+		goto bad;
+	}
+
+	if (unlikely(vol_id < UBI_INTERNAL_VOL_START && compat != 0)) {
+		dbg_err("bad compat");
+		goto bad;
+	}
+
+	if (unlikely(vol_id >= UBI_INTERNAL_VOL_START &&
+		     compat != UBI_COMPAT_DELETE &&
+		     compat != UBI_COMPAT_RO &&
+		     compat != UBI_COMPAT_PRESERVE &&
+		     compat != UBI_COMPAT_REJECT)) {
+		dbg_err("bad compat");
+		goto bad;
+	}
+
+	if (unlikely(vol_type != UBI_VID_DYNAMIC &&
+		     vol_type != UBI_VID_STATIC)) {
+		dbg_err("bad vol_type");
+		goto bad;
+	}
+
+	if (unlikely(data_pad >= ubi->leb_size / 2)) {
+		dbg_err("bad data_pad");
+		goto bad;
+	}
+
+	if (vol_type == UBI_VID_STATIC) {
+		/*
+		 * Although from high-level point of view static volumes may
+		 * contain zero bytes of data, but no VID headers can contain
+		 * zero at these fields, because they empty volumes do not have
+		 * mapped logical eraseblocks.
+		 */
+		if (unlikely(used_ebs == 0)) {
+			dbg_err("zero used_ebs");
+			goto bad;
+		}
+		if (unlikely(data_size == 0)) {
+			dbg_err("zero data_size");
+			goto bad;
+		}
+		if (lnum < used_ebs - 1) {
+			if (unlikely(data_size != usable_leb_size)) {
+				dbg_err("bad data_size");
+				goto bad;
+			}
+		} else if (lnum == used_ebs - 1) {
+			if (unlikely(data_size == 0)) {
+				dbg_err("bad data_size at last LEB");
+				goto bad;
+			}
+		} else {
+			dbg_err("too high lnum");
+			goto bad;
+		}
+	} else {
+		if (copy_flag == 0) {
+			if (unlikely(data_crc != 0)) {
+				dbg_err("non-zero data CRC");
+				goto bad;
+			}
+			if (unlikely(data_size != 0)) {
+				dbg_err("non-zero data_size");
+				goto bad;
+			}
+		} else {
+			if (unlikely(data_size == 0)) {
+				dbg_err("zero data_size of copy");
+				goto bad;
+			}
+		}
+		if (unlikely(used_ebs != 0)) {
+			dbg_err("bad used_ebs");
+			goto bad;
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err("bad VID header");
+	ubi_dbg_dump_vid_hdr(vid_hdr);
+	ubi_dbg_dump_stack();
+	return 1;
+}
+
+/**
+ * ubi_io_read_vid_hdr - read and check a volume identifier header.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number to read from
+ * @vid_hdr: &struct ubi_vid_hdr object where to store the read volume
+ * identifier header
+ * @verbose: be verbose if the header is corrupted or wasn't found
+ *
+ * This function reads the volume identifier header from physical eraseblock
+ * @pnum and stores it in @vid_hdr. It also checks CRC checksum of the read
+ * volume identifier header. The following codes may be returned:
+ *
+ * o %0 if the CRC checksum is correct and the header was successfully read;
+ * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
+ *   and corrected by the flash driver; this is harmless but may indicate that
+ *   this eraseblock may become bad soon;
+ * o %UBI_IO_BAD_VID_HRD if the volume identifier header is corrupted (a CRC
+ *   error detected);
+ * o %UBI_IO_PEB_FREE if the physical eraseblock is free (i.e., there is no VID
+ *   header there);
+ * o a negative error code in case of failure.
+ */
+int ubi_io_read_vid_hdr(const struct ubi_device *ubi, int pnum,
+			struct ubi_vid_hdr *vid_hdr, int verbose)
+{
+	int err, read_err = 0;
+	uint32_t crc, magic, hdr_crc;
+	void *p;
+
+	dbg_io("read VID header from PEB %d", pnum);
+	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
+
+	p = (char *)vid_hdr - ubi->vid_hdr_shift;
+	err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
+			  ubi->vid_hdr_alsize);
+	if (unlikely(err)) {
+		if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
+			return err;
+
+		/*
+		 * We read all the data, but either a correctable bit-flip
+		 * occurred, or MTD reported about some data integrity error,
+		 * like an ECC error in case of NAND. The former is harmless,
+		 * the later may mean the read data is corrupted. But we have a
+		 * CRC check-sum and we will identify this. If the VID header is
+		 * still OK, we just report this as there was a bit-flip.
+		 */
+		read_err = err;
+	}
+
+	magic = ubi32_to_cpu(vid_hdr->magic);
+	if (unlikely(magic != UBI_VID_HDR_MAGIC)) {
+		/*
+		 * If we have read all 0xFF bytes, the VID header probably does
+		 * not exist and the physical eraseblock is assumed to be free.
+		 *
+		 * But if there was a read error, we do not test the data for
+		 * 0xFFs. Even if it does contain all 0xFFs, this error
+		 * indicates that something is still wrong with this physical
+		 * eraseblock and it cannot be regarded as free.
+		 */
+		if (likely(read_err != -EBADMSG) &&
+		    check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
+			/* The physical eraseblock is supposedly free */
+
+			/*
+			 * The below is just a paranoid check, it has to be
+			 * compiled out if paranoid checks are disabled.
+			 */
+			err = paranoid_check_all_ff(ubi, pnum, ubi->leb_start,
+						    ubi->leb_size);
+			if (unlikely(err))
+				return err > 0 ? UBI_IO_BAD_VID_HDR : err;
+
+			if (verbose)
+				ubi_warn("no VID header found at PEB %d, "
+					 "only 0xFF bytes", pnum);
+			return UBI_IO_PEB_FREE;
+		}
+
+		/*
+		 * This is not a valid VID header, and these are not 0xFF
+		 * bytes. Report that the header is corrupted.
+		 */
+		if (verbose) {
+			ubi_warn("bad magic number at PEB %d: %08x instead of "
+				 "%08x", pnum, magic, UBI_VID_HDR_MAGIC);
+			ubi_dbg_dump_vid_hdr(vid_hdr);
+		}
+		return UBI_IO_BAD_VID_HDR;
+	}
+
+	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
+	hdr_crc = ubi32_to_cpu(vid_hdr->hdr_crc);
+
+	if (unlikely(hdr_crc != crc)) {
+		if (verbose) {
+			ubi_warn("bad CRC at PEB %d, calculated %#08x, "
+				 "read %#08x", pnum, crc, hdr_crc);
+			ubi_dbg_dump_vid_hdr(vid_hdr);
+		}
+		return UBI_IO_BAD_VID_HDR;
+	}
+
+	/* Validate the VID header that we have just read */
+	err = validate_vid_hdr(ubi, vid_hdr);
+	if (unlikely(err)) {
+		ubi_err("validation failed for PEB %d", pnum);
+		return -EINVAL;
+	}
+
+	return read_err ? UBI_IO_BITFLIPS : 0;
+}
+
+/**
+ * ubi_io_write_vid_hdr - write a volume identifier header.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to write to
+ * @vid_hdr: the volume identifier header to write
+ *
+ * This function writes the volume identifier header described by @vid_hdr to
+ * physical eraseblock @pnum. This function automatically fills the
+ * @vid_hdr->magic and the @vid_hdr->version fields, as well as calculates
+ * header CRC checksum and stores it at vid_hdr->hdr_crc.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure. If %-EIO is returned, the physical eraseblock probably went
+ * bad.
+ */
+int ubi_io_write_vid_hdr(const struct ubi_device *ubi, int pnum,
+			 struct ubi_vid_hdr *vid_hdr)
+{
+	int err;
+	uint32_t crc;
+	void *p;
+
+	dbg_io("write VID header to PEB %d", pnum);
+	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
+
+	err = paranoid_check_peb_ec_hdr(ubi, pnum);
+	if (unlikely(err))
+		return err > 0 ? -EINVAL: err;
+
+	vid_hdr->magic = cpu_to_ubi32(UBI_VID_HDR_MAGIC);
+	vid_hdr->version = UBI_VERSION;
+	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
+	vid_hdr->hdr_crc = cpu_to_ubi32(crc);
+
+	err = paranoid_check_vid_hdr(ubi, pnum, vid_hdr);
+	if (unlikely(err))
+		return -EINVAL;
+
+	p = (char *)vid_hdr - ubi->vid_hdr_shift;
+	err = ubi_io_write(ubi, p, pnum, ubi->vid_hdr_aloffset,
+			   ubi->vid_hdr_alsize);
+	return err;
+}
+
+#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
+
+/**
+ * paranoid_check_not_bad - ensure that a physical eraseblock is not bad.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number to check
+ *
+ * This function returns zero if the physical eraseblock is good, a positive
+ * number if it is bad and a negative error code if an error occurred.
+ */
+static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+
+	err = ubi_io_is_bad(ubi, pnum);
+	if (likely(!err))
+		return err;
+
+	ubi_err("paranoid check failed for PEB %d", pnum);
+	ubi_dbg_dump_stack();
+	return err;
+}
+
+/**
+ * paranoid_check_ec_hdr - check if an erase counter header is all right.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number the erase counter header belongs to
+ * @ec_hdr: the erase counter header to check
+ *
+ * This function returns zero if the erase counter header contains valid
+ * values, and %1 if not.
+ */
+static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
+				 const struct ubi_ec_hdr *ec_hdr)
+{
+	int err;
+	uint32_t magic;
+
+	magic = ubi32_to_cpu(ec_hdr->magic);
+	if (unlikely(magic != UBI_EC_HDR_MAGIC)) {
+		ubi_err("bad magic %#08x, must be %#08x",
+			magic, UBI_EC_HDR_MAGIC);
+		goto fail;
+	}
+
+	err = validate_ec_hdr(ubi, ec_hdr);
+	if (unlikely(err)) {
+		ubi_err("paranoid check failed for PEB %d", pnum);
+		goto fail;
+	}
+
+	return 0;
+
+fail:
+	ubi_dbg_dump_ec_hdr(ec_hdr);
+	ubi_dbg_dump_stack();
+	return 1;
+}
+
+/**
+ * paranoid_check_peb_ec_hdr - check that the erase counter header of a
+ * physical eraseblock is in-place and is all right.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ *
+ * This function returns zero if the erase counter header is all right, %1 if
+ * not, and a negative error code if an error occurred.
+ */
+static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+	uint32_t crc, hdr_crc;
+	struct ubi_ec_hdr *ec_hdr;
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (unlikely(!ec_hdr))
+		return -ENOMEM;
+
+	err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
+	if (unlikely(err) && err != UBI_IO_BITFLIPS && err != -EBADMSG)
+		goto exit;
+
+	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
+	hdr_crc = ubi32_to_cpu(ec_hdr->hdr_crc);
+	if (unlikely(hdr_crc != crc)) {
+		ubi_err("bad CRC, calculated %#08x, read %#08x", crc, hdr_crc);
+		ubi_err("paranoid check failed for PEB %d", pnum);
+		ubi_dbg_dump_ec_hdr(ec_hdr);
+		ubi_dbg_dump_stack();
+		err = 1;
+		goto exit;
+	}
+
+	err = paranoid_check_ec_hdr(ubi, pnum, ec_hdr);
+
+exit:
+	kfree(ec_hdr);
+	return err;
+}
+
+/**
+ * paranoid_check_vid_hdr - check that a volume identifier header is all right.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number the volume identifier header belongs to
+ * @vid_hdr: the volume identifier header to check
+ *
+ * This function returns zero if the volume identifier header is all right, and
+ * %1 if not.
+ */
+static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
+				  const struct ubi_vid_hdr *vid_hdr)
+{
+	int err;
+	uint32_t magic;
+
+	magic = ubi32_to_cpu(vid_hdr->magic);
+	if (unlikely(magic != UBI_VID_HDR_MAGIC)) {
+		ubi_err("bad VID header magic %#08x at PEB %d, must be %#08x",
+			magic, pnum, UBI_VID_HDR_MAGIC);
+		goto fail;
+	}
+
+	err = validate_vid_hdr(ubi, vid_hdr);
+	if (unlikely(err)) {
+		ubi_err("paranoid check failed for PEB %d", pnum);
+		goto fail;
+	}
+
+	return err;
+
+fail:
+	ubi_err("paranoid check failed for PEB %d", pnum);
+	ubi_dbg_dump_vid_hdr(vid_hdr);
+	ubi_dbg_dump_stack();
+	return 1;
+
+}
+
+/**
+ * paranoid_check_peb_vid_hdr - check that the volume identifier header of a
+ * physical eraseblock is in-place and is all right.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ *
+ * This function returns zero if the volume identifier header is all right,
+ * %1 if not, and a negative error code if an error occurred.
+ */
+static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+	uint32_t crc, hdr_crc;
+	struct ubi_vid_hdr *vid_hdr;
+	void *p;
+
+	vid_hdr = ubi_zalloc_vid_hdr(ubi);
+	if (unlikely(!vid_hdr))
+		return -ENOMEM;
+
+	p = (char *)vid_hdr - ubi->vid_hdr_shift;
+	err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
+			  ubi->vid_hdr_alsize);
+	if (unlikely(err) && err != UBI_IO_BITFLIPS && err != -EBADMSG)
+		goto exit;
+
+	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_EC_HDR_SIZE_CRC);
+	hdr_crc = ubi32_to_cpu(vid_hdr->hdr_crc);
+	if (unlikely(hdr_crc != crc)) {
+		ubi_err("bad VID header CRC at PEB %d, calculated %#08x, "
+			"read %#08x", pnum, crc, hdr_crc);
+		ubi_err("paranoid check failed for PEB %d", pnum);
+		ubi_dbg_dump_vid_hdr(vid_hdr);
+		ubi_dbg_dump_stack();
+		err = 1;
+		goto exit;
+	}
+
+	err = paranoid_check_vid_hdr(ubi, pnum, vid_hdr);
+
+exit:
+	ubi_free_vid_hdr(ubi, vid_hdr);
+	return err;
+}
+
+/**
+ * paranoid_check_all_ff - check that a region of flash is empty.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ * @offset: the starting offset within the physical eraseblock to check
+ * @len: the length of the region to check
+ *
+ * This function returns zero if only 0xFF bytes are present at offset
+ * @offset of the physical eraseblock @pnum, %1 if not, and a negative error
+ * code if an error occurred.
+ */
+static int paranoid_check_all_ff(const struct ubi_device *ubi, int pnum,
+				 int offset, int len)
+{
+	size_t read;
+	int err;
+	void *buf;
+	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
+
+	buf = kzalloc(len, GFP_KERNEL);
+	if (unlikely(!buf))
+		return -ENOMEM;
+
+	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
+	if (unlikely(err && err != -EUCLEAN)) {
+		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
+			"read %zd bytes", err, len, pnum, offset, read);
+		goto error;
+	}
+
+	err = check_pattern(buf, 0xFF, len);
+	if (unlikely(err == 0)) {
+		ubi_err("flash region at PEB %d:%d, length %d does not "
+			"contain all 0xFF bytes", pnum, offset, len);
+		goto fail;
+	}
+
+	kfree(buf);
+	return 0;
+
+fail:
+	ubi_err("paranoid check failed for PEB %d", pnum);
+	dbg_err("hex dump of the %d-%d region", offset, offset + len);
+	ubi_dbg_hexdump(buf, len);
+	err = 1;
+error:
+	ubi_dbg_dump_stack();
+	kfree(buf);
+	return err;
+}
+
+#endif /* CONFIG_MTD_UBI_DEBUG_PARANOID */