include/uapi/linux/bcache.h

   1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2 #ifndef _LINUX_BCACHE_H
   3 #define _LINUX_BCACHE_H
   4
   5 /*
   6  * Bcache on disk data structures
   7  */
   8
   9 #include <linux/types.h>
  10
  11 #define BITMASK(name, type, field, offset, size)                \
  12 static inline __u64 name(const type *k)                         \
  13 { return (k->field >> offset) & ~(~0ULL << size); }             \
  14                                                                 \
  15 static inline void SET_##name(type *k, __u64 v)                 \
  16 {                                                               \
  17         k->field &= ~(~(~0ULL << size) << offset);              \
  18         k->field |= (v & ~(~0ULL << size)) << offset;           \
  19 }
  20
  21 /* Btree keys - all units are in sectors */
  22
  23 struct bkey {
  24         __u64   high;
  25         __u64   low;
  26         __u64   ptr[];
  27 };
  28
  29 #define KEY_FIELD(name, field, offset, size)                            \
  30         BITMASK(name, struct bkey, field, offset, size)
  31
  32 #define PTR_FIELD(name, offset, size)                                   \
  33 static inline __u64 name(const struct bkey *k, unsigned i)              \
  34 { return (k->ptr[i] >> offset) & ~(~0ULL << size); }                    \
  35                                                                         \
  36 static inline void SET_##name(struct bkey *k, unsigned i, __u64 v)      \
  37 {                                                                       \
  38         k->ptr[i] &= ~(~(~0ULL << size) << offset);                     \
  39         k->ptr[i] |= (v & ~(~0ULL << size)) << offset;                  \
  40 }
  41
  42 #define KEY_SIZE_BITS           16
  43 #define KEY_MAX_U64S            8
  44
  45 KEY_FIELD(KEY_PTRS,     high, 60, 3)
  46 KEY_FIELD(HEADER_SIZE,  high, 58, 2)
  47 KEY_FIELD(KEY_CSUM,     high, 56, 2)
  48 KEY_FIELD(KEY_PINNED,   high, 55, 1)
  49 KEY_FIELD(KEY_DIRTY,    high, 36, 1)
  50
  51 KEY_FIELD(KEY_SIZE,     high, 20, KEY_SIZE_BITS)
  52 KEY_FIELD(KEY_INODE,    high, 0,  20)
  53
  54 /* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */
  55
  56 static inline __u64 KEY_OFFSET(const struct bkey *k)
  57 {
  58         return k->low;
  59 }
  60
  61 static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
  62 {
  63         k->low = v;
  64 }
  65
  66 /*
  67  * The high bit being set is a relic from when we used it to do binary
  68  * searches - it told you where a key started. It's not used anymore,
  69  * and can probably be safely dropped.
  70  */
  71 #define KEY(inode, offset, size)                                        \
  72 ((struct bkey) {                                                        \
  73         .high = (1ULL << 63) | ((__u64) (size) << 20) | (inode),        \
  74         .low = (offset)                                                 \
  75 })
  76
  77 #define ZERO_KEY                        KEY(0, 0, 0)
  78
  79 #define MAX_KEY_INODE                   (~(~0 << 20))
  80 #define MAX_KEY_OFFSET                  (~0ULL >> 1)
  81 #define MAX_KEY                         KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)
  82
  83 #define KEY_START(k)                    (KEY_OFFSET(k) - KEY_SIZE(k))
  84 #define START_KEY(k)                    KEY(KEY_INODE(k), KEY_START(k), 0)
  85
  86 #define PTR_DEV_BITS                    12
  87
  88 PTR_FIELD(PTR_DEV,                      51, PTR_DEV_BITS)
  89 PTR_FIELD(PTR_OFFSET,                   8,  43)
  90 PTR_FIELD(PTR_GEN,                      0,  8)
  91
  92 #define PTR_CHECK_DEV                   ((1 << PTR_DEV_BITS) - 1)
  93
  94 #define MAKE_PTR(gen, offset, dev)                                      \
  95         ((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
  96
  97 /* Bkey utility code */
  98
  99 static inline unsigned long bkey_u64s(const struct bkey *k)
 100 {
 101         return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
 102 }
 103
 104 static inline unsigned long bkey_bytes(const struct bkey *k)
 105 {
 106         return bkey_u64s(k) * sizeof(__u64);
 107 }
 108
 109 #define bkey_copy(_dest, _src)  memcpy(_dest, _src, bkey_bytes(_src))
 110
 111 static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
 112 {
 113         SET_KEY_INODE(dest, KEY_INODE(src));
 114         SET_KEY_OFFSET(dest, KEY_OFFSET(src));
 115 }
 116
 117 static inline struct bkey *bkey_next(const struct bkey *k)
 118 {
 119         __u64 *d = (void *) k;
 120         return (struct bkey *) (d + bkey_u64s(k));
 121 }
 122
 123 static inline struct bkey *bkey_idx(const struct bkey *k, unsigned nr_keys)
 124 {
 125         __u64 *d = (void *) k;
 126         return (struct bkey *) (d + nr_keys);
 127 }
 128 /* Enough for a key with 6 pointers */
 129 #define BKEY_PAD                8
 130
 131 #define BKEY_PADDED(key)                                        \
 132         union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }
 133
 134 /* Superblock */
 135
 136 /* Version 0: Cache device
 137  * Version 1: Backing device
 138  * Version 2: Seed pointer into btree node checksum
 139  * Version 3: Cache device with new UUID format
 140  * Version 4: Backing device with data offset
 141  */
 142 #define BCACHE_SB_VERSION_CDEV          0
 143 #define BCACHE_SB_VERSION_BDEV          1
 144 #define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
 145 #define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
 146 #define BCACHE_SB_MAX_VERSION           4
 147
 148 #define SB_SECTOR                       8
 149 #define SB_SIZE                         4096
 150 #define SB_LABEL_SIZE                   32
 151 #define SB_JOURNAL_BUCKETS              256U
 152 /* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
 153 #define MAX_CACHES_PER_SET              8
 154
 155 #define BDEV_DATA_START_DEFAULT         16      /* sectors */
 156
 157 struct cache_sb {
 158         __u64                   csum;
 159         __u64                   offset; /* sector where this sb was written */
 160         __u64                   version;
 161
 162         __u8                    magic[16];
 163
 164         __u8                    uuid[16];
 165         union {
 166                 __u8            set_uuid[16];
 167                 __u64           set_magic;
 168         };
 169         __u8                    label[SB_LABEL_SIZE];
 170
 171         __u64                   flags;
 172         __u64                   seq;
 173         __u64                   pad[8];
 174
 175         union {
 176         struct {
 177                 /* Cache devices */
 178                 __u64           nbuckets;       /* device size */
 179
 180                 __u16           block_size;     /* sectors */
 181                 __u16           bucket_size;    /* sectors */
 182
 183                 __u16           nr_in_set;
 184                 __u16           nr_this_dev;
 185         };
 186         struct {
 187                 /* Backing devices */
 188                 __u64           data_offset;
 189
 190                 /*
 191                  * block_size from the cache device section is still used by
 192                  * backing devices, so don't add anything here until we fix
 193                  * things to not need it for backing devices anymore
 194                  */
 195         };
 196         };
 197
 198         __u32                   last_mount;     /* time_t */
 199
 200         __u16                   first_bucket;
 201         union {
 202                 __u16           njournal_buckets;
 203                 __u16           keys;
 204         };
 205         __u64                   d[SB_JOURNAL_BUCKETS];  /* journal buckets */
 206 };
 207
 208 static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
 209 {
 210         return sb->version == BCACHE_SB_VERSION_BDEV
 211                 || sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
 212 }
 213
 214 BITMASK(CACHE_SYNC,                     struct cache_sb, flags, 0, 1);
 215 BITMASK(CACHE_DISCARD,                  struct cache_sb, flags, 1, 1);
 216 BITMASK(CACHE_REPLACEMENT,              struct cache_sb, flags, 2, 3);
 217 #define CACHE_REPLACEMENT_LRU           0U
 218 #define CACHE_REPLACEMENT_FIFO          1U
 219 #define CACHE_REPLACEMENT_RANDOM        2U
 220
 221 BITMASK(BDEV_CACHE_MODE,                struct cache_sb, flags, 0, 4);
 222 #define CACHE_MODE_WRITETHROUGH         0U
 223 #define CACHE_MODE_WRITEBACK            1U
 224 #define CACHE_MODE_WRITEAROUND          2U
 225 #define CACHE_MODE_NONE                 3U
 226 BITMASK(BDEV_STATE,                     struct cache_sb, flags, 61, 2);
 227 #define BDEV_STATE_NONE                 0U
 228 #define BDEV_STATE_CLEAN                1U
 229 #define BDEV_STATE_DIRTY                2U
 230 #define BDEV_STATE_STALE                3U
 231
 232 /*
 233  * Magic numbers
 234  *
 235  * The various other data structures have their own magic numbers, which are
 236  * xored with the first part of the cache set's UUID
 237  */
 238
 239 #define JSET_MAGIC                      0x245235c1a3625032ULL
 240 #define PSET_MAGIC                      0x6750e15f87337f91ULL
 241 #define BSET_MAGIC                      0x90135c78b99e07f5ULL
 242
 243 static inline __u64 jset_magic(struct cache_sb *sb)
 244 {
 245         return sb->set_magic ^ JSET_MAGIC;
 246 }
 247
 248 static inline __u64 pset_magic(struct cache_sb *sb)
 249 {
 250         return sb->set_magic ^ PSET_MAGIC;
 251 }
 252
 253 static inline __u64 bset_magic(struct cache_sb *sb)
 254 {
 255         return sb->set_magic ^ BSET_MAGIC;
 256 }
 257
 258 /*
 259  * Journal
 260  *
 261  * On disk format for a journal entry:
 262  * seq is monotonically increasing; every journal entry has its own unique
 263  * sequence number.
 264  *
 265  * last_seq is the oldest journal entry that still has keys the btree hasn't
 266  * flushed to disk yet.
 267  *
 268  * version is for on disk format changes.
 269  */
 270
 271 #define BCACHE_JSET_VERSION_UUIDv1      1
 272 #define BCACHE_JSET_VERSION_UUID        1       /* Always latest UUID format */
 273 #define BCACHE_JSET_VERSION             1
 274
 275 struct jset {
 276         __u64                   csum;
 277         __u64                   magic;
 278         __u64                   seq;
 279         __u32                   version;
 280         __u32                   keys;
 281
 282         __u64                   last_seq;
 283
 284         BKEY_PADDED(uuid_bucket);
 285         BKEY_PADDED(btree_root);
 286         __u16                   btree_level;
 287         __u16                   pad[3];
 288
 289         __u64                   prio_bucket[MAX_CACHES_PER_SET];
 290
 291         union {
 292                 struct bkey     start[0];
 293                 __u64           d[0];
 294         };
 295 };
 296
 297 /* Bucket prios/gens */
 298
 299 struct prio_set {
 300         __u64                   csum;
 301         __u64                   magic;
 302         __u64                   seq;
 303         __u32                   version;
 304         __u32                   pad;
 305
 306         __u64                   next_bucket;
 307
 308         struct bucket_disk {
 309                 __u16           prio;
 310                 __u8            gen;
 311         } __attribute((packed)) data[];
 312 };
 313
 314 /* UUIDS - per backing device/flash only volume metadata */
 315
 316 struct uuid_entry {
 317         union {
 318                 struct {
 319                         __u8    uuid[16];
 320                         __u8    label[32];
 321                         __u32   first_reg;
 322                         __u32   last_reg;
 323                         __u32   invalidated;
 324
 325                         __u32   flags;
 326                         /* Size of flash only volumes */
 327                         __u64   sectors;
 328                 };
 329
 330                 __u8            pad[128];
 331         };
 332 };
 333
 334 BITMASK(UUID_FLASH_ONLY,        struct uuid_entry, flags, 0, 1);
 335
 336 /* Btree nodes */
 337
 338 /* Version 1: Seed pointer into btree node checksum
 339  */
 340 #define BCACHE_BSET_CSUM                1
 341 #define BCACHE_BSET_VERSION             1
 342
 343 /*
 344  * Btree nodes
 345  *
 346  * On disk a btree node is a list/log of these; within each set the keys are
 347  * sorted
 348  */
 349 struct bset {
 350         __u64                   csum;
 351         __u64                   magic;
 352         __u64                   seq;
 353         __u32                   version;
 354         __u32                   keys;
 355
 356         union {
 357                 struct bkey     start[0];
 358                 __u64           d[0];
 359         };
 360 };
 361
 362 /* OBSOLETE */
 363
 364 /* UUIDS - per backing device/flash only volume metadata */
 365
 366 struct uuid_entry_v0 {
 367         __u8            uuid[16];
 368         __u8            label[32];
 369         __u32           first_reg;
 370         __u32           last_reg;
 371         __u32           invalidated;
 372         __u32           pad;
 373 };
 374
 375 #endif /* _LINUX_BCACHE_H */