UBI-Utils: Updated headers for latest UBI

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>

1 files changed, 145 insertions, 164 deletions

diff --git a/include/mtd/ubi-header.h b/include/mtd/ubi-header.h
index ca96fc9..c003d98 100644
--- a/include/mtd/ubi-header.h
+++ b/include/mtd/ubi-header.h
@@ -24,36 +24,30 @@
 
 /*
  * This file defines the layout of UBI headers and all the other UBI on-flash
- * data structures.
+ * data structures. May be included by user-space.
  */
 
 #ifndef __UBI_HEADER_H__
 #define __UBI_HEADER_H__
 
-#include <mtd_swab.h>
+#include <asm/byteorder.h>
 
-/* The version of this UBI implementation */
+/* The version of UBI images supported by this implementation */
 #define UBI_VERSION 1
 
-/* The highest erase counter value supported by this implementation of UBI */
+/* 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
 
-/*
- * Magic numbers of the UBI headers.
- *
- * @UBI_EC_HDR_MAGIC: erase counter header magic number (ASCII "UBI#")
- * @UBI_VID_HDR_MAGIC: volume identifier header magic number (ASCII "UBI!")
- */
-enum {
-	UBI_EC_HDR_MAGIC  = 0x55424923,
-	UBI_VID_HDR_MAGIC = 0x55424921
-};
+/* 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
 
 /*
- * Molume type constants used in volume identifier headers.
+ * Volume type constants used in the volume identifier header.
  *
  * @UBI_VID_DYNAMIC: dynamic volume
  * @UBI_VID_STATIC: static volume
@@ -97,59 +91,50 @@ typedef struct {
 } __attribute__ ((packed)) ubi64_t;
 
 /*
- * In this implementation UBI uses the big-endian format for on-flash integers.
- * The below are the corresponding endianess conversion macros.
+ * 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_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_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))
+#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.
- */
+/* 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.
- */
+/* 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))
 
-/*
- * How much private data may internal volumes store in the VID header.
- */
-#define UBI_VID_HDR_IVOL_DATA_SIZE 12
-
 /**
  * struct ubi_ec_hdr - UBI erase counter header.
- *
- * @magic: the erase counter header magic number (%UBI_EC_HDR_MAGIC)
- * @version: the version of UBI implementation which is supposed to accept this
- * UBI image (%UBI_VERSION)
+ * @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 begins
- * @data_offset: where the user data begins
+ * @vid_hdr_offset: where the VID header starts
+ * @data_offset: where the user data start
  * @padding2: reserved for future, zeroes
- * @hdr_crc: the erase counter header CRC checksum
+ * @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 rejecter. This may be useful in future if something
+ * 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
- * eraseblock. These values have to be the same for all eraseblocks.
+ * physical eraseblock. These values have to be the same for all physical
+ * eraseblocks.
  */
 struct ubi_ec_hdr {
 	ubi32_t magic;
@@ -164,77 +149,108 @@ struct ubi_ec_hdr {
 
 /**
  * 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: a flag indicating if this physical eraseblock was created by
- * means of copying an original physical eraseblock to ensure wear-leveling.
- * @compat: compatibility of this volume (%UBI_COMPAT_DELETE,
+ * @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: volume ID
+ * @vol_id: ID of this volume
  * @lnum: logical eraseblock number
- * @leb_ver: eraseblock copy number
- * @data_size: how many bytes of data this eraseblock contains.
+ * @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 eraseblock are not used
- * @data_crc: CRC checksum of data containing in this eraseblock
+ * @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
- * @ivol_data: private data of internal volumes
+ * @sqnum: sequence number
+ * @padding2: reserved for future, zeroes
  * @hdr_crc: volume identifier header CRC checksum
  *
- * The @leb_ver and the @copy_flag fields are used to distinguish between older
- * and newer copies of logical eraseblocks, as well as to guarantee robustness
- * to unclean reboots. As UBI erases logical eraseblocks asynchronously, it has
- * to distinguish between older and newer copies of eraseblocks. This is done
- * using the @version field. On the other hand, when UBI moves an eraseblock,
- * its version is also increased and the @copy_flag is set to 1. Additionally,
- * when moving eraseblocks, UBI calculates data CRC and stores it in the
- * @data_crc field, even for dynamic volumes.
+ * 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.
  *
- * Thus, if there are 2 eraseblocks of the same volume and logical number, UBI
- * uses the following algorithm to pick one of them. It first picks the one
- * with larger version (say, A). If @copy_flag is not set, then A is picked. If
- * @copy_flag is set, UBI checks the CRC of the eraseblock (@data_crc). This is
- * needed to ensure that copying was finished. If the CRC is all right, A is
- * picked. If not, the older eraseblock is picked.
+ * 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.
  *
- * Note, the @leb_ver field may overflow. Thus, if you have 2 versions A and B,
- * then A > B if abs(A-B) < 0x7FFFFFFF, and A < B otherwise.
+ * 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 different
- * internal UBI purposes. In this implementation there are only two internal
- * volumes: the layout volume and the update volume. Internal volumes are the
- * main mechanism of UBI extensions. For example, in future one may introduce a
- * journal internal volume.
+ * 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. This field 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 an
- * journal internal volume in future, he would probably use %UBI_COMPAT_DELETE
- * compatibility.  And in this case, older UBI binaries, which know nothing
- * about the journal volume, would just delete this and work perfectly fine.
- * This is somewhat similar to what Ext2fs does when it is fed by an Ext3fs
- * image - it just ignores the Ext3fs journal.
+ * 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
+ * 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
- * logical eraseblock was moved by the wear-leveling unit, then the
- * wear-leveling unit calculates the eraseblocks' CRC and stores it at
- * @data_crc.
+ * 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 always used for static volumes because we want to
- * know about how many bytes of data are stored in this eraseblock.  For
- * dynamic eraseblocks, this field usually contains zero. The only exception is
- * when the logical eraseblock is moved to another physical eraseblock due to
+ * 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 the size of logical eraseblock of this volume
- * (which may vary owing to @alignment).
+ * @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
@@ -244,11 +260,6 @@ struct ubi_ec_hdr {
  * 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.
- *
- * The @ivol_data contains private data of internal volumes. This might be very
- * handy to store data in the VID header, not in the eraseblock's contents. For
- * example it may make life of simple boot-loaders easier. The @ivol_data field
- * contains zeroes for user volumes.
  */
 struct ubi_vid_hdr {
 	ubi32_t magic;
@@ -258,117 +269,87 @@ struct ubi_vid_hdr {
 	uint8_t compat;
 	ubi32_t vol_id;
 	ubi32_t lnum;
-	ubi32_t leb_ver;
+	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[12];
-	uint8_t ivol_data[UBI_VID_HDR_IVOL_DATA_SIZE];
+	uint8_t padding1[4];
+	ubi64_t sqnum;
+	uint8_t padding2[12];
 	ubi32_t hdr_crc;
 } __attribute__ ((packed));
 
-/**
- * struct ubi_vid_hdr_upd_vol - private data of the update internal volume
- * stored in volume identifier headers.
- *
- * @vol_id: volume ID of the volume under update
- * @padding: zeroes
- */
-struct ubi_vid_hdr_upd_vol {
-	ubi32_t vol_id;
-	uint8_t padding[UBI_VID_HDR_IVOL_DATA_SIZE-4];
-} __attribute__ ((packed));
-
-/*
- * Count of internal UBI volumes.
- */
-#define UBI_INT_VOL_COUNT 2
+/* Internal UBI volumes count */
+#define UBI_INT_VOL_COUNT 1
 
 /*
- * Internal volume IDs start from this digit. There is a reserved room for 4096
- * internal volumes.
+ * Starting ID of internal volumes. There is reserved room for 4096 internal
+ * volumes.
  */
 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
 
 /*
- * enum ubi_internal_volume_numbers - volume IDs of internal UBI volumes.
+ * IDs of internal UBI volumes.
  *
- * %UBI_LAYOUT_VOL_ID: volume ID of the layout volume
- * %UBI_UPDATE_VOL_ID: volume ID of the update volume
+ * %UBI_LAYOUT_VOL_ID: layout volume ID
  */
 enum {
 	UBI_LAYOUT_VOL_ID = UBI_INTERNAL_VOL_START,
-	UBI_UPDATE_VOL_ID = UBI_INTERNAL_VOL_START + 1
 };
+ 
+/* The layout volume contains the volume table */
 
-/*
- * Number of logical eraseblocks reserved for internal volumes.
- */
-#define UBI_LAYOUT_VOLUME_EBS 2
-#define UBI_UPDATE_VOLUME_EBS 1
-
-/*
- * Names of internal volumes
- */
-#define UBI_LAYOUT_VOLUME_NAME "The layout volume"
-#define UBI_UPDATE_VOLUME_NAME "The update volume"
-
-/*
- * Compatibility flags of internal volumes.
- */
+#define UBI_LAYOUT_VOLUME_EBS    2
+#define UBI_LAYOUT_VOLUME_NAME   "The layout volume"
 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
-#define UBI_UPDATE_VOLUME_COMPAT UBI_COMPAT_REJECT
 
-/*
- * The maximum number of volumes per one UBI device.
- */
+/* The maximum number of volumes per one UBI device */
 #define UBI_MAX_VOLUMES 128
 
-/*
- * The maximum volume name length.
- */
+/* The maximum volume name length */
 #define UBI_VOL_NAME_MAX 127
 
-/*
- * Size of volume table records.
- */
+/* Size of the volume table record */
 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vol_tbl_record)
 
-/*
- * Size of volume table records without the ending CRC.
- */
+/* 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_vol_tbl_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 not used at the end of the eraseblocks to
- * satisfy the requested 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)
- * @padding1: reserved, zeroes
- * @name_len: the volume name length
+ * @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 layout volume consists of 2 logical eraseblock, each of which contains
- * the volume table (i.e., the volume table is duplicated). The volume table is
- * an array of &struct ubi_vol_tbl_record objects indexed by the volume ID.
+ * 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_vol_tbl_record
+ * objects indexed by the volume ID.
  *
  * If the size of the logical eraseblock is large enough to fit
- * %UBI_MAX_VOLUMES, the volume table contains %UBI_MAX_VOLUMES records.
- * Otherwise, it contains as much records as can be fit (i.e., size of logical
- * eraseblock divided by sizeof(struct ubi_vol_tbl_record)).
+ * %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_vol_tbl_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
- * eraseblocks is used.
+ * the physical eraseblocks is used.
  *
  * Empty records contain all zeroes and the CRC checksum of those zeroes.
  */
@@ -377,7 +358,7 @@ struct ubi_vol_tbl_record {
 	ubi32_t alignment;
 	ubi32_t data_pad;
 	uint8_t vol_type;
-	uint8_t padding1;
+	uint8_t upd_marker;
 	ubi16_t name_len;
 	uint8_t name[UBI_VOL_NAME_MAX+1];
 	uint8_t padding2[24];