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 };
 142
 143 static __always_inline int
 144 bch2_hash_lookup(struct btree_trans *trans,
 145                  struct btree_iter *iter,
 146                  const struct bch_hash_desc desc,
 147                  const struct bch_hash_info *info,
 148                  subvol_inum inum, const void *key,
 149                  unsigned flags)
 150 {
 151         struct bkey_s_c k;
 152         u32 snapshot;
 153         int ret;
 154
 155         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 156         if (ret)
 157                 return ret;
 158
 159         for_each_btree_key(trans, *iter, desc.btree_id,
 160                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 161                            BTREE_ITER_SLOTS|flags, k, ret) {
 162                 if (iter->pos.inode != inum.inum)
 163                         break;
 164
 165                 if (k.k->type == desc.key_type) {
 166                         if (!desc.cmp_key(k, key))
 167                                 return 0;
 168                 } else if (k.k->type == KEY_TYPE_hash_whiteout) {
 169                         ;
 170                 } else {
 171                         /* hole, not found */
 172                         break;
 173                 }
 174         }
 175         bch2_trans_iter_exit(trans, iter);
 176
 177         return ret ?: -ENOENT;
 178 }
 179
 180 static __always_inline int
 181 bch2_hash_hole(struct btree_trans *trans,
 182                struct btree_iter *iter,
 183                const struct bch_hash_desc desc,
 184                const struct bch_hash_info *info,
 185                subvol_inum inum, const void *key)
 186 {
 187         struct bkey_s_c k;
 188         u32 snapshot;
 189         int ret;
 190
 191         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 192         if (ret)
 193                 return ret;
 194
 195         for_each_btree_key(trans, *iter, desc.btree_id,
 196                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 197                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 198                 if (iter->pos.inode != inum.inum)
 199                         break;
 200
 201                 if (k.k->type != desc.key_type)
 202                         return 0;
 203         }
 204         bch2_trans_iter_exit(trans, iter);
 205
 206         return ret ?: -ENOSPC;
 207 }
 208
 209 static __always_inline
 210 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 211                              const struct bch_hash_desc desc,
 212                              const struct bch_hash_info *info,
 213                              struct btree_iter *start)
 214 {
 215         struct btree_iter iter;
 216         struct bkey_s_c k;
 217         int ret;
 218
 219         bch2_trans_copy_iter(&iter, start);
 220
 221         bch2_btree_iter_advance(&iter);
 222
 223         for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, k, ret) {
 224                 if (k.k->type != desc.key_type &&
 225                     k.k->type != KEY_TYPE_hash_whiteout)
 226                         break;
 227
 228                 if (k.k->type == desc.key_type &&
 229                     desc.hash_bkey(info, k) <= start->pos.offset) {
 230                         ret = 1;
 231                         break;
 232                 }
 233         }
 234
 235         bch2_trans_iter_exit(trans, &iter);
 236         return ret;
 237 }
 238
 239 static __always_inline
 240 int bch2_hash_set(struct btree_trans *trans,
 241                   const struct bch_hash_desc desc,
 242                   const struct bch_hash_info *info,
 243                   subvol_inum inum,
 244                   struct bkey_i *insert, int flags)
 245 {
 246         struct btree_iter iter, slot = { NULL };
 247         struct bkey_s_c k;
 248         bool found = false;
 249         u32 snapshot;
 250         int ret;
 251
 252         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 253         if (ret)
 254                 return ret;
 255
 256         for_each_btree_key(trans, iter, desc.btree_id,
 257                            SPOS(inum.inum,
 258                                 desc.hash_bkey(info, bkey_i_to_s_c(insert)),
 259                                 snapshot),
 260                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 261                 if (iter.pos.inode != inum.inum)
 262                         break;
 263
 264                 if (k.k->type == desc.key_type) {
 265                         if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 266                                 goto found;
 267
 268                         /* hash collision: */
 269                         continue;
 270                 }
 271
 272                 if (!slot.path &&
 273                     !(flags & BCH_HASH_SET_MUST_REPLACE))
 274                         bch2_trans_copy_iter(&slot, &iter);
 275
 276                 if (k.k->type != KEY_TYPE_hash_whiteout)
 277                         goto not_found;
 278         }
 279
 280         if (!ret)
 281                 ret = -ENOSPC;
 282 out:
 283         bch2_trans_iter_exit(trans, &slot);
 284         bch2_trans_iter_exit(trans, &iter);
 285
 286         return ret;
 287 found:
 288         found = true;
 289 not_found:
 290
 291         if (!found && (flags & BCH_HASH_SET_MUST_REPLACE)) {
 292                 ret = -ENOENT;
 293         } else if (found && (flags & BCH_HASH_SET_MUST_CREATE)) {
 294                 ret = -EEXIST;
 295         } else {
 296                 if (!found && slot.path)
 297                         swap(iter, slot);
 298
 299                 insert->k.p = iter.pos;
 300                 ret = bch2_trans_update(trans, &iter, insert, 0);
 301         }
 302
 303         goto out;
 304 }
 305
 306 static __always_inline
 307 int bch2_hash_delete_at(struct btree_trans *trans,
 308                         const struct bch_hash_desc desc,
 309                         const struct bch_hash_info *info,
 310                         struct btree_iter *iter,
 311                         unsigned update_flags)
 312 {
 313         struct bkey_i *delete;
 314         int ret;
 315
 316         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 317         ret = PTR_ERR_OR_ZERO(delete);
 318         if (ret)
 319                 return ret;
 320
 321         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 322         if (ret < 0)
 323                 return ret;
 324
 325         bkey_init(&delete->k);
 326         delete->k.p = iter->pos;
 327         delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;
 328
 329         return bch2_trans_update(trans, iter, delete, update_flags);
 330 }
 331
 332 static __always_inline
 333 int bch2_hash_delete(struct btree_trans *trans,
 334                      const struct bch_hash_desc desc,
 335                      const struct bch_hash_info *info,
 336                      subvol_inum inum, const void *key)
 337 {
 338         struct btree_iter iter;
 339         int ret;
 340
 341         ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key,
 342                                 BTREE_ITER_INTENT);
 343         if (ret)
 344                 return ret;
 345
 346         ret = bch2_hash_delete_at(trans, desc, info, &iter, 0);
 347         bch2_trans_iter_exit(trans, &iter);
 348         return ret;
 349 }
 350
 351 #endif /* _BCACHEFS_STR_HASH_H */