git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/str_hash.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _BCACHEFS_STR_HASH_H
   3 #define _BCACHEFS_STR_HASH_H
   4
   5 #include "btree_iter.h"
   6 #include "btree_update.h"
   7 #include "checksum.h"
   8 #include "error.h"
   9 #include "inode.h"
  10 #include "siphash.h"
  11 #include "subvolume.h"
  12 #include "super.h"
  13
  14 #include <linux/crc32c.h>
  15 #include <crypto/hash.h>
  16 #include <crypto/sha2.h>
  17
  18 static inline enum bch_str_hash_type
  19 bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt)
  20 {
  21         switch (opt) {
  22         case BCH_STR_HASH_OPT_crc32c:
  23                 return BCH_STR_HASH_crc32c;
  24         case BCH_STR_HASH_OPT_crc64:
  25                 return BCH_STR_HASH_crc64;
  26         case BCH_STR_HASH_OPT_siphash:
  27                 return c->sb.features & (1ULL << BCH_FEATURE_new_siphash)
  28                         ? BCH_STR_HASH_siphash
  29                         : BCH_STR_HASH_siphash_old;
  30         default:
  31              BUG();
  32         }
  33 }
  34
  35 struct bch_hash_info {
  36         u8                      type;
  37         /*
  38          * For crc32 or crc64 string hashes the first key value of
  39          * the siphash_key (k0) is used as the key.
  40          */
  41         SIPHASH_KEY     siphash_key;
  42 };
  43
  44 static inline struct bch_hash_info
  45 bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
  46 {
  47         /* XXX ick */
  48         struct bch_hash_info info = {
  49                 .type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
  50                         ~(~0U << INODE_STR_HASH_BITS),
  51                 .siphash_key = { .k0 = bi->bi_hash_seed }
  52         };
  53
  54         if (unlikely(info.type == BCH_STR_HASH_siphash_old)) {
  55                 SHASH_DESC_ON_STACK(desc, c->sha256);
  56                 u8 digest[SHA256_DIGEST_SIZE];
  57
  58                 desc->tfm = c->sha256;
  59
  60                 crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
  61                                     sizeof(bi->bi_hash_seed), digest);
  62                 memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
  63         }
  64
  65         return info;
  66 }
  67
  68 struct bch_str_hash_ctx {
  69         union {
  70                 u32             crc32c;
  71                 u64             crc64;
  72                 SIPHASH_CTX     siphash;
  73         };
  74 };
  75
  76 static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
  77                                      const struct bch_hash_info *info)
  78 {
  79         switch (info->type) {
  80         case BCH_STR_HASH_crc32c:
  81                 ctx->crc32c = crc32c(~0, &info->siphash_key.k0,
  82                                      sizeof(info->siphash_key.k0));
  83                 break;
  84         case BCH_STR_HASH_crc64:
  85                 ctx->crc64 = crc64_be(~0, &info->siphash_key.k0,
  86                                       sizeof(info->siphash_key.k0));
  87                 break;
  88         case BCH_STR_HASH_siphash_old:
  89         case BCH_STR_HASH_siphash:
  90                 SipHash24_Init(&ctx->siphash, &info->siphash_key);
  91                 break;
  92         default:
  93                 BUG();
  94         }
  95 }
  96
  97 static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
  98                                        const struct bch_hash_info *info,
  99                                        const void *data, size_t len)
 100 {
 101         switch (info->type) {
 102         case BCH_STR_HASH_crc32c:
 103                 ctx->crc32c = crc32c(ctx->crc32c, data, len);
 104                 break;
 105         case BCH_STR_HASH_crc64:
 106                 ctx->crc64 = crc64_be(ctx->crc64, data, len);
 107                 break;
 108         case BCH_STR_HASH_siphash_old:
 109         case BCH_STR_HASH_siphash:
 110                 SipHash24_Update(&ctx->siphash, data, len);
 111                 break;
 112         default:
 113                 BUG();
 114         }
 115 }
 116
 117 static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
 118                                    const struct bch_hash_info *info)
 119 {
 120         switch (info->type) {
 121         case BCH_STR_HASH_crc32c:
 122                 return ctx->crc32c;
 123         case BCH_STR_HASH_crc64:
 124                 return ctx->crc64 >> 1;
 125         case BCH_STR_HASH_siphash_old:
 126         case BCH_STR_HASH_siphash:
 127                 return SipHash24_End(&ctx->siphash) >> 1;
 128         default:
 129                 BUG();
 130         }
 131 }
 132
 133 struct bch_hash_desc {
 134         enum btree_id   btree_id;
 135         u8              key_type;
 136
 137         u64             (*hash_key)(const struct bch_hash_info *, const void *);
 138         u64             (*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c);
 139         bool            (*cmp_key)(struct bkey_s_c, const void *);
 140         bool            (*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
 141         bool            (*is_visible)(subvol_inum inum, struct bkey_s_c);
 142 };
 143
 144 static inline bool is_visible_key(struct bch_hash_desc desc, subvol_inum inum, struct bkey_s_c k)
 145 {
 146         return k.k->type == desc.key_type &&
 147                 (!desc.is_visible || desc.is_visible(inum, k));
 148 }
 149
 150 static __always_inline int
 151 bch2_hash_lookup(struct btree_trans *trans,
 152                  struct btree_iter *iter,
 153                  const struct bch_hash_desc desc,
 154                  const struct bch_hash_info *info,
 155                  subvol_inum inum, const void *key,
 156                  unsigned flags)
 157 {
 158         struct bkey_s_c k;
 159         u32 snapshot;
 160         int ret;
 161
 162         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 163         if (ret)
 164                 return ret;
 165
 166         for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 167                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 168                            POS(inum.inum, U64_MAX),
 169                            BTREE_ITER_SLOTS|flags, k, ret) {
 170                 if (is_visible_key(desc, inum, k)) {
 171                         if (!desc.cmp_key(k, key))
 172                                 return 0;
 173                 } else if (k.k->type == KEY_TYPE_hash_whiteout) {
 174                         ;
 175                 } else {
 176                         /* hole, not found */
 177                         break;
 178                 }
 179         }
 180         bch2_trans_iter_exit(trans, iter);
 181
 182         return ret ?: -ENOENT;
 183 }
 184
 185 static __always_inline int
 186 bch2_hash_hole(struct btree_trans *trans,
 187                struct btree_iter *iter,
 188                const struct bch_hash_desc desc,
 189                const struct bch_hash_info *info,
 190                subvol_inum inum, const void *key)
 191 {
 192         struct bkey_s_c k;
 193         u32 snapshot;
 194         int ret;
 195
 196         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 197         if (ret)
 198                 return ret;
 199
 200         for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 201                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 202                            POS(inum.inum, U64_MAX),
 203                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret)
 204                 if (!is_visible_key(desc, inum, k))
 205                         return 0;
 206         bch2_trans_iter_exit(trans, iter);
 207
 208         return ret ?: -ENOSPC;
 209 }
 210
 211 static __always_inline
 212 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 213                              const struct bch_hash_desc desc,
 214                              const struct bch_hash_info *info,
 215                              struct btree_iter *start)
 216 {
 217         struct btree_iter iter;
 218         struct bkey_s_c k;
 219         int ret;
 220
 221         bch2_trans_copy_iter(&iter, start);
 222
 223         bch2_btree_iter_advance(&iter);
 224
 225         for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, k, ret) {
 226                 if (k.k->type != desc.key_type &&
 227                     k.k->type != KEY_TYPE_hash_whiteout)
 228                         break;
 229
 230                 if (k.k->type == desc.key_type &&
 231                     desc.hash_bkey(info, k) <= start->pos.offset) {
 232                         ret = 1;
 233                         break;
 234                 }
 235         }
 236
 237         bch2_trans_iter_exit(trans, &iter);
 238         return ret;
 239 }
 240
 241 static __always_inline
 242 int bch2_hash_set_snapshot(struct btree_trans *trans,
 243                            const struct bch_hash_desc desc,
 244                            const struct bch_hash_info *info,
 245                            subvol_inum inum, u32 snapshot,
 246                            struct bkey_i *insert,
 247                            int flags,
 248                            int update_flags)
 249 {
 250         struct btree_iter iter, slot = { NULL };
 251         struct bkey_s_c k;
 252         bool found = false;
 253         int ret;
 254
 255         for_each_btree_key_upto_norestart(trans, iter, desc.btree_id,
 256                            SPOS(insert->k.p.inode,
 257                                 desc.hash_bkey(info, bkey_i_to_s_c(insert)),
 258                                 snapshot),
 259                            POS(insert->k.p.inode, U64_MAX),
 260                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 261                 if (!inum.subvol || is_visible_key(desc, inum, k)) {
 262                         if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 263                                 goto found;
 264
 265                         /* hash collision: */
 266                         continue;
 267                 }
 268
 269                 if (!slot.path &&
 270                     !(flags & BCH_HASH_SET_MUST_REPLACE))
 271                         bch2_trans_copy_iter(&slot, &iter);
 272
 273                 if (k.k->type != KEY_TYPE_hash_whiteout)
 274                         goto not_found;
 275         }
 276
 277         if (!ret)
 278                 ret = -ENOSPC;
 279 out:
 280         bch2_trans_iter_exit(trans, &slot);
 281         bch2_trans_iter_exit(trans, &iter);
 282
 283         return ret;
 284 found:
 285         found = true;
 286 not_found:
 287
 288         if (!found && (flags & BCH_HASH_SET_MUST_REPLACE)) {
 289                 ret = -ENOENT;
 290         } else if (found && (flags & BCH_HASH_SET_MUST_CREATE)) {
 291                 ret = -EEXIST;
 292         } else {
 293                 if (!found && slot.path)
 294                         swap(iter, slot);
 295
 296                 insert->k.p = iter.pos;
 297                 ret = bch2_trans_update(trans, &iter, insert, 0);
 298         }
 299
 300         goto out;
 301 }
 302
 303 static __always_inline
 304 int bch2_hash_set(struct btree_trans *trans,
 305                   const struct bch_hash_desc desc,
 306                   const struct bch_hash_info *info,
 307                   subvol_inum inum,
 308                   struct bkey_i *insert, int flags)
 309 {
 310         u32 snapshot;
 311         int ret;
 312
 313         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 314         if (ret)
 315                 return ret;
 316
 317         insert->k.p.inode = inum.inum;
 318
 319         return bch2_hash_set_snapshot(trans, desc, info, inum,
 320                                       snapshot, insert, flags, 0);
 321 }
 322
 323 static __always_inline
 324 int bch2_hash_delete_at(struct btree_trans *trans,
 325                         const struct bch_hash_desc desc,
 326                         const struct bch_hash_info *info,
 327                         struct btree_iter *iter,
 328                         unsigned update_flags)
 329 {
 330         struct bkey_i *delete;
 331         int ret;
 332
 333         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 334         ret = PTR_ERR_OR_ZERO(delete);
 335         if (ret)
 336                 return ret;
 337
 338         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 339         if (ret < 0)
 340                 return ret;
 341
 342         bkey_init(&delete->k);
 343         delete->k.p = iter->pos;
 344         delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;
 345
 346         return bch2_trans_update(trans, iter, delete, update_flags);
 347 }
 348
 349 static __always_inline
 350 int bch2_hash_delete(struct btree_trans *trans,
 351                      const struct bch_hash_desc desc,
 352                      const struct bch_hash_info *info,
 353                      subvol_inum inum, const void *key)
 354 {
 355         struct btree_iter iter;
 356         int ret;
 357
 358         ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key,
 359                                 BTREE_ITER_INTENT);
 360         if (ret)
 361                 return ret;
 362
 363         ret = bch2_hash_delete_at(trans, desc, info, &iter, 0);
 364         bch2_trans_iter_exit(trans, &iter);
 365         return ret;
 366 }
 367
 368 #endif /* _BCACHEFS_STR_HASH_H */