diff options
Diffstat (limited to 'include/mtd/ubi-header.h')
| -rw-r--r-- | include/mtd/ubi-header.h | 309 |
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]; |