1/* 2 md_p.h : physical layout of Linux RAID devices 3 Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 2, or (at your option) 8 any later version. 9 10 You should have received a copy of the GNU General Public License 11 (for example /usr/src/linux/COPYING); if not, write to the Free 12 Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 13*/ 14 15#ifndef _MD_P_H 16#define _MD_P_H 17 18#include <linux/types.h> 19#include <asm/byteorder.h> 20 21/* 22 * RAID superblock. 23 * 24 * The RAID superblock maintains some statistics on each RAID configuration. 25 * Each real device in the RAID set contains it near the end of the device. 26 * Some of the ideas are copied from the ext2fs implementation. 27 * 28 * We currently use 4096 bytes as follows: 29 * 30 * word offset function 31 * 32 * 0 - 31 Constant generic RAID device information. 33 * 32 - 63 Generic state information. 34 * 64 - 127 Personality specific information. 35 * 128 - 511 12 32-words descriptors of the disks in the raid set. 36 * 512 - 911 Reserved. 37 * 912 - 1023 Disk specific descriptor. 38 */ 39 40/* 41 * If x is the real device size in bytes, we return an apparent size of: 42 * 43 * y = (x & ~(MD_RESERVED_BYTES - 1)) - MD_RESERVED_BYTES 44 * 45 * and place the 4kB superblock at offset y. 46 */ 47#define MD_RESERVED_BYTES (64 * 1024) 48#define MD_RESERVED_SECTORS (MD_RESERVED_BYTES / 512) 49 50#define MD_NEW_SIZE_SECTORS(x) ((x & ~(MD_RESERVED_SECTORS - 1)) - MD_RESERVED_SECTORS) 51 52#define MD_SB_BYTES 4096 53#define MD_SB_WORDS (MD_SB_BYTES / 4) 54#define MD_SB_SECTORS (MD_SB_BYTES / 512) 55 56/* 57 * The following are counted in 32-bit words 58 */ 59#define MD_SB_GENERIC_OFFSET 0 60#define MD_SB_PERSONALITY_OFFSET 64 61#define MD_SB_DISKS_OFFSET 128 62#define MD_SB_DESCRIPTOR_OFFSET 992 63 64#define MD_SB_GENERIC_CONSTANT_WORDS 32 65#define MD_SB_GENERIC_STATE_WORDS 32 66#define MD_SB_GENERIC_WORDS (MD_SB_GENERIC_CONSTANT_WORDS + MD_SB_GENERIC_STATE_WORDS) 67#define MD_SB_PERSONALITY_WORDS 64 68#define MD_SB_DESCRIPTOR_WORDS 32 69#define MD_SB_DISKS 27 70#define MD_SB_DISKS_WORDS (MD_SB_DISKS*MD_SB_DESCRIPTOR_WORDS) 71#define MD_SB_RESERVED_WORDS (1024 - MD_SB_GENERIC_WORDS - MD_SB_PERSONALITY_WORDS - MD_SB_DISKS_WORDS - MD_SB_DESCRIPTOR_WORDS) 72#define MD_SB_EQUAL_WORDS (MD_SB_GENERIC_WORDS + MD_SB_PERSONALITY_WORDS + MD_SB_DISKS_WORDS) 73 74/* 75 * Device "operational" state bits 76 */ 77#define MD_DISK_FAULTY 0 /* disk is faulty / operational */ 78#define MD_DISK_ACTIVE 1 /* disk is running or spare disk */ 79#define MD_DISK_SYNC 2 /* disk is in sync with the raid set */ 80#define MD_DISK_REMOVED 3 /* disk is in sync with the raid set */ 81 82#define MD_DISK_WRITEMOSTLY 9 /* disk is "write-mostly" is RAID1 config. 83 * read requests will only be sent here in 84 * dire need 85 */ 86 87typedef struct mdp_device_descriptor_s { 88 __u32 number; /* 0 Device number in the entire set */ 89 __u32 major; /* 1 Device major number */ 90 __u32 minor; /* 2 Device minor number */ 91 __u32 raid_disk; /* 3 The role of the device in the raid set */ 92 __u32 state; /* 4 Operational state */ 93 __u32 reserved[MD_SB_DESCRIPTOR_WORDS - 5]; 94} mdp_disk_t; 95 96#define MD_SB_MAGIC 0xa92b4efc 97 98/* 99 * Superblock state bits 100 */ 101#define MD_SB_CLEAN 0 102#define MD_SB_ERRORS 1 103 104#define MD_SB_BITMAP_PRESENT 8 /* bitmap may be present nearby */ 105 106/* 107 * Notes: 108 * - if an array is being reshaped (restriped) in order to change the 109 * the number of active devices in the array, 'raid_disks' will be 110 * the larger of the old and new numbers. 'delta_disks' will 111 * be the "new - old". So if +ve, raid_disks is the new value, and 112 * "raid_disks-delta_disks" is the old. If -ve, raid_disks is the 113 * old value and "raid_disks+delta_disks" is the new (smaller) value. 114 */ 115 116 117typedef struct mdp_superblock_s { 118 /* 119 * Constant generic information 120 */ 121 __u32 md_magic; /* 0 MD identifier */ 122 __u32 major_version; /* 1 major version to which the set conforms */ 123 __u32 minor_version; /* 2 minor version ... */ 124 __u32 patch_version; /* 3 patchlevel version ... */ 125 __u32 gvalid_words; /* 4 Number of used words in this section */ 126 __u32 set_uuid0; /* 5 Raid set identifier */ 127 __u32 ctime; /* 6 Creation time */ 128 __u32 level; /* 7 Raid personality */ 129 __u32 size; /* 8 Apparent size of each individual disk */ 130 __u32 nr_disks; /* 9 total disks in the raid set */ 131 __u32 raid_disks; /* 10 disks in a fully functional raid set */ 132 __u32 md_minor; /* 11 preferred MD minor device number */ 133 __u32 not_persistent; /* 12 does it have a persistent superblock */ 134 __u32 set_uuid1; /* 13 Raid set identifier #2 */ 135 __u32 set_uuid2; /* 14 Raid set identifier #3 */ 136 __u32 set_uuid3; /* 15 Raid set identifier #4 */ 137 __u32 gstate_creserved[MD_SB_GENERIC_CONSTANT_WORDS - 16]; 138 139 /* 140 * Generic state information 141 */ 142 __u32 utime; /* 0 Superblock update time */ 143 __u32 state; /* 1 State bits (clean, ...) */ 144 __u32 active_disks; /* 2 Number of currently active disks */ 145 __u32 working_disks; /* 3 Number of working disks */ 146 __u32 failed_disks; /* 4 Number of failed disks */ 147 __u32 spare_disks; /* 5 Number of spare disks */ 148 __u32 sb_csum; /* 6 checksum of the whole superblock */ 149#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN) 150 __u32 events_hi; /* 7 high-order of superblock update count */ 151 __u32 events_lo; /* 8 low-order of superblock update count */ 152 __u32 cp_events_hi; /* 9 high-order of checkpoint update count */ 153 __u32 cp_events_lo; /* 10 low-order of checkpoint update count */ 154#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN) 155 __u32 events_lo; /* 7 low-order of superblock update count */ 156 __u32 events_hi; /* 8 high-order of superblock update count */ 157 __u32 cp_events_lo; /* 9 low-order of checkpoint update count */ 158 __u32 cp_events_hi; /* 10 high-order of checkpoint update count */ 159#else 160#error unspecified endianness 161#endif 162 __u32 recovery_cp; /* 11 recovery checkpoint sector count */ 163 /* There are only valid for minor_version > 90 */ 164 __u64 reshape_position; /* 12,13 next address in array-space for reshape */ 165 __u32 new_level; /* 14 new level we are reshaping to */ 166 __u32 delta_disks; /* 15 change in number of raid_disks */ 167 __u32 new_layout; /* 16 new layout */ 168 __u32 new_chunk; /* 17 new chunk size (bytes) */ 169 __u32 gstate_sreserved[MD_SB_GENERIC_STATE_WORDS - 18]; 170 171 /* 172 * Personality information 173 */ 174 __u32 layout; /* 0 the array's physical layout */ 175 __u32 chunk_size; /* 1 chunk size in bytes */ 176 __u32 root_pv; /* 2 LV root PV */ 177 __u32 root_block; /* 3 LV root block */ 178 __u32 pstate_reserved[MD_SB_PERSONALITY_WORDS - 4]; 179 180 /* 181 * Disks information 182 */ 183 mdp_disk_t disks[MD_SB_DISKS]; 184 185 /* 186 * Reserved 187 */ 188 __u32 reserved[MD_SB_RESERVED_WORDS]; 189 190 /* 191 * Active descriptor 192 */ 193 mdp_disk_t this_disk; 194 195} mdp_super_t; 196 197static inline __u64 md_event(mdp_super_t *sb) { 198 __u64 ev = sb->events_hi; 199 return (ev<<32)| sb->events_lo; 200} 201 202#define MD_SUPERBLOCK_1_TIME_SEC_MASK ((1ULL<<40) - 1) 203 204/* 205 * The version-1 superblock : 206 * All numeric fields are little-endian. 207 * 208 * total size: 256 bytes plus 2 per device. 209 * 1K allows 384 devices. 210 */ 211struct mdp_superblock_1 { 212 /* constant array information - 128 bytes */ 213 __le32 magic; /* MD_SB_MAGIC: 0xa92b4efc - little endian */ 214 __le32 major_version; /* 1 */ 215 __le32 feature_map; /* bit 0 set if 'bitmap_offset' is meaningful */ 216 __le32 pad0; /* always set to 0 when writing */ 217 218 __u8 set_uuid[16]; /* user-space generated. */ 219 char set_name[32]; /* set and interpreted by user-space */ 220 221 __le64 ctime; /* lo 40 bits are seconds, top 24 are microseconds or 0*/ 222 __le32 level; /* -4 (multipath), -1 (linear), 0,1,4,5 */ 223 __le32 layout; /* only for raid5 and raid10 currently */ 224 __le64 size; /* used size of component devices, in 512byte sectors */ 225 226 __le32 chunksize; /* in 512byte sectors */ 227 __le32 raid_disks; 228 __le32 bitmap_offset; /* sectors after start of superblock that bitmap starts 229 * NOTE: signed, so bitmap can be before superblock 230 * only meaningful of feature_map[0] is set. 231 */ 232 233 /* These are only valid with feature bit '4' */ 234 __le32 new_level; /* new level we are reshaping to */ 235 __le64 reshape_position; /* next address in array-space for reshape */ 236 __le32 delta_disks; /* change in number of raid_disks */ 237 __le32 new_layout; /* new layout */ 238 __le32 new_chunk; /* new chunk size (512byte sectors) */ 239 __le32 new_offset; /* signed number to add to data_offset in new 240 * layout. 0 == no-change. This can be 241 * different on each device in the array. 242 */ 243 244 /* constant this-device information - 64 bytes */ 245 __le64 data_offset; /* sector start of data, often 0 */ 246 __le64 data_size; /* sectors in this device that can be used for data */ 247 __le64 super_offset; /* sector start of this superblock */ 248 __le64 recovery_offset;/* sectors before this offset (from data_offset) have been recovered */ 249 __le32 dev_number; /* permanent identifier of this device - not role in raid */ 250 __le32 cnt_corrected_read; /* number of read errors that were corrected by re-writing */ 251 __u8 device_uuid[16]; /* user-space setable, ignored by kernel */ 252 __u8 devflags; /* per-device flags. Only one defined...*/ 253#define WriteMostly1 1 /* mask for writemostly flag in above */ 254 /* Bad block log. If there are any bad blocks the feature flag is set. 255 * If offset and size are non-zero, that space is reserved and available 256 */ 257 __u8 bblog_shift; /* shift from sectors to block size */ 258 __le16 bblog_size; /* number of sectors reserved for list */ 259 __le32 bblog_offset; /* sector offset from superblock to bblog, 260 * signed - not unsigned */ 261 262 /* array state information - 64 bytes */ 263 __le64 utime; /* 40 bits second, 24 bits microseconds */ 264 __le64 events; /* incremented when superblock updated */ 265 __le64 resync_offset; /* data before this offset (from data_offset) known to be in sync */ 266 __le32 sb_csum; /* checksum up to devs[max_dev] */ 267 __le32 max_dev; /* size of devs[] array to consider */ 268 __u8 pad3[64-32]; /* set to 0 when writing */ 269 270 /* device state information. Indexed by dev_number. 271 * 2 bytes per device 272 * Note there are no per-device state flags. State information is rolled 273 * into the 'roles' value. If a device is spare or faulty, then it doesn't 274 * have a meaningful role. 275 */ 276 __le16 dev_roles[0]; /* role in array, or 0xffff for a spare, or 0xfffe for faulty */ 277}; 278 279/* feature_map bits */ 280#define MD_FEATURE_BITMAP_OFFSET 1 281#define MD_FEATURE_RECOVERY_OFFSET 2 /* recovery_offset is present and 282 * must be honoured 283 */ 284#define MD_FEATURE_RESHAPE_ACTIVE 4 285#define MD_FEATURE_BAD_BLOCKS 8 /* badblock list is not empty */ 286#define MD_FEATURE_REPLACEMENT 16 /* This device is replacing an 287 * active device with same 'role'. 288 * 'recovery_offset' is also set. 289 */ 290#define MD_FEATURE_RESHAPE_BACKWARDS 32 /* Reshape doesn't change number 291 * of devices, but is going 292 * backwards anyway. 293 */ 294#define MD_FEATURE_NEW_OFFSET 64 /* new_offset must be honoured */ 295#define MD_FEATURE_RECOVERY_BITMAP 128 /* recovery that is happening 296 * is guided by bitmap. 297 */ 298#define MD_FEATURE_ALL (MD_FEATURE_BITMAP_OFFSET \ 299 |MD_FEATURE_RECOVERY_OFFSET \ 300 |MD_FEATURE_RESHAPE_ACTIVE \ 301 |MD_FEATURE_BAD_BLOCKS \ 302 |MD_FEATURE_REPLACEMENT \ 303 |MD_FEATURE_RESHAPE_BACKWARDS \ 304 |MD_FEATURE_NEW_OFFSET \ 305 |MD_FEATURE_RECOVERY_BITMAP \ 306 ) 307 308#endif 309