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 ||
 148                  !inum.inum ||
 149                  desc.is_visible(inum, k));
 150 }
 151
 152 static __always_inline int
 153 bch2_hash_lookup(struct btree_trans *trans,
 154                  struct btree_iter *iter,
 155                  const struct bch_hash_desc desc,
 156                  const struct bch_hash_info *info,
 157                  subvol_inum inum, const void *key,
 158                  unsigned flags)
 159 {
 160         struct bkey_s_c k;
 161         u32 snapshot;
 162         int ret;
 163
 164         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 165         if (ret)
 166                 return ret;
 167
 168         for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 169                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 170                            POS(inum.inum, U64_MAX),
 171                            BTREE_ITER_SLOTS|flags, k, ret) {
 172                 if (is_visible_key(desc, inum, k)) {
 173                         if (!desc.cmp_key(k, key))
 174                                 return 0;
 175                 } else if (k.k->type == KEY_TYPE_hash_whiteout) {
 176                         ;
 177                 } else {
 178                         /* hole, not found */
 179                         break;
 180                 }
 181         }
 182         bch2_trans_iter_exit(trans, iter);
 183
 184         return ret ?: -BCH_ERR_ENOENT_str_hash_lookup;
 185 }
 186
 187 static __always_inline int
 188 bch2_hash_hole(struct btree_trans *trans,
 189                struct btree_iter *iter,
 190                const struct bch_hash_desc desc,
 191                const struct bch_hash_info *info,
 192                subvol_inum inum, const void *key)
 193 {
 194         struct bkey_s_c k;
 195         u32 snapshot;
 196         int ret;
 197
 198         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 199         if (ret)
 200                 return ret;
 201
 202         for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 203                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 204                            POS(inum.inum, U64_MAX),
 205                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret)
 206                 if (!is_visible_key(desc, inum, k))
 207                         return 0;
 208         bch2_trans_iter_exit(trans, iter);
 209
 210         return ret ?: -BCH_ERR_ENOSPC_str_hash_create;
 211 }
 212
 213 static __always_inline
 214 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 215                              const struct bch_hash_desc desc,
 216                              const struct bch_hash_info *info,
 217                              struct btree_iter *start)
 218 {
 219         struct btree_iter iter;
 220         struct bkey_s_c k;
 221         int ret;
 222
 223         bch2_trans_copy_iter(&iter, start);
 224
 225         bch2_btree_iter_advance(&iter);
 226
 227         for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, k, ret) {
 228                 if (k.k->type != desc.key_type &&
 229                     k.k->type != KEY_TYPE_hash_whiteout)
 230                         break;
 231
 232                 if (k.k->type == desc.key_type &&
 233                     desc.hash_bkey(info, k) <= start->pos.offset) {
 234                         ret = 1;
 235                         break;
 236                 }
 237         }
 238
 239         bch2_trans_iter_exit(trans, &iter);
 240         return ret;
 241 }
 242
 243 static __always_inline
 244 int bch2_hash_set_snapshot(struct btree_trans *trans,
 245                            const struct bch_hash_desc desc,
 246                            const struct bch_hash_info *info,
 247                            subvol_inum inum, u32 snapshot,
 248                            struct bkey_i *insert,
 249                            int flags,
 250                            int update_flags)
 251 {
 252         struct btree_iter iter, slot = { NULL };
 253         struct bkey_s_c k;
 254         bool found = false;
 255         int ret;
 256
 257         for_each_btree_key_upto_norestart(trans, iter, desc.btree_id,
 258                            SPOS(insert->k.p.inode,
 259                                 desc.hash_bkey(info, bkey_i_to_s_c(insert)),
 260                                 snapshot),
 261                            POS(insert->k.p.inode, U64_MAX),
 262                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 263                 if (is_visible_key(desc, inum, k)) {
 264                         if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 265                                 goto found;
 266
 267                         /* hash collision: */
 268                         continue;
 269                 }
 270
 271                 if (!slot.path &&
 272                     !(flags & BCH_HASH_SET_MUST_REPLACE))
 273                         bch2_trans_copy_iter(&slot, &iter);
 274
 275                 if (k.k->type != KEY_TYPE_hash_whiteout)
 276                         goto not_found;
 277         }
 278
 279         if (!ret)
 280                 ret = -BCH_ERR_ENOSPC_str_hash_create;
 281 out:
 282         bch2_trans_iter_exit(trans, &slot);
 283         bch2_trans_iter_exit(trans, &iter);
 284
 285         return ret;
 286 found:
 287         found = true;
 288 not_found:
 289
 290         if (!found && (flags & BCH_HASH_SET_MUST_REPLACE)) {
 291                 ret = -BCH_ERR_ENOENT_str_hash_set_must_replace;
 292         } else if (found && (flags & BCH_HASH_SET_MUST_CREATE)) {
 293                 ret = -EEXIST;
 294         } else {
 295                 if (!found && slot.path)
 296                         swap(iter, slot);
 297
 298                 insert->k.p = iter.pos;
 299                 ret = bch2_trans_update(trans, &iter, insert, 0);
 300         }
 301
 302         goto out;
 303 }
 304
 305 static __always_inline
 306 int bch2_hash_set(struct btree_trans *trans,
 307                   const struct bch_hash_desc desc,
 308                   const struct bch_hash_info *info,
 309                   subvol_inum inum,
 310                   struct bkey_i *insert, int flags)
 311 {
 312         u32 snapshot;
 313         int ret;
 314
 315         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 316         if (ret)
 317                 return ret;
 318
 319         insert->k.p.inode = inum.inum;
 320
 321         return bch2_hash_set_snapshot(trans, desc, info, inum,
 322                                       snapshot, insert, flags, 0);
 323 }
 324
 325 static __always_inline
 326 int bch2_hash_delete_at(struct btree_trans *trans,
 327                         const struct bch_hash_desc desc,
 328                         const struct bch_hash_info *info,
 329                         struct btree_iter *iter,
 330                         unsigned update_flags)
 331 {
 332         struct bkey_i *delete;
 333         int ret;
 334
 335         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 336         ret = PTR_ERR_OR_ZERO(delete);
 337         if (ret)
 338                 return ret;
 339
 340         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 341         if (ret < 0)
 342                 return ret;
 343
 344         bkey_init(&delete->k);
 345         delete->k.p = iter->pos;
 346         delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;
 347
 348         return bch2_trans_update(trans, iter, delete, update_flags);
 349 }
 350
 351 static __always_inline
 352 int bch2_hash_delete(struct btree_trans *trans,
 353                      const struct bch_hash_desc desc,
 354                      const struct bch_hash_info *info,
 355                      subvol_inum inum, const void *key)
 356 {
 357         struct btree_iter iter;
 358         int ret;
 359
 360         ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key,
 361                                 BTREE_ITER_INTENT);
 362         if (ret)
 363                 return ret;
 364
 365         ret = bch2_hash_delete_at(trans, desc, info, &iter, 0);
 366         bch2_trans_iter_exit(trans, &iter);
 367         return ret;
 368 }
 369
 370 #endif /* _BCACHEFS_STR_HASH_H */