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 typedef unsigned __bitwise bch_str_hash_flags_t;
  19
  20 enum bch_str_hash_flags {
  21         __BCH_HASH_SET_MUST_CREATE,
  22         __BCH_HASH_SET_MUST_REPLACE,
  23 };
  24
  25 #define BCH_HASH_SET_MUST_CREATE        (__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_CREATE)
  26 #define BCH_HASH_SET_MUST_REPLACE       (__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_REPLACE)
  27
  28 static inline enum bch_str_hash_type
  29 bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt)
  30 {
  31         switch (opt) {
  32         case BCH_STR_HASH_OPT_crc32c:
  33                 return BCH_STR_HASH_crc32c;
  34         case BCH_STR_HASH_OPT_crc64:
  35                 return BCH_STR_HASH_crc64;
  36         case BCH_STR_HASH_OPT_siphash:
  37                 return c->sb.features & (1ULL << BCH_FEATURE_new_siphash)
  38                         ? BCH_STR_HASH_siphash
  39                         : BCH_STR_HASH_siphash_old;
  40         default:
  41              BUG();
  42         }
  43 }
  44
  45 struct bch_hash_info {
  46         u8                      type;
  47         /*
  48          * For crc32 or crc64 string hashes the first key value of
  49          * the siphash_key (k0) is used as the key.
  50          */
  51         SIPHASH_KEY     siphash_key;
  52 };
  53
  54 static inline struct bch_hash_info
  55 bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
  56 {
  57         /* XXX ick */
  58         struct bch_hash_info info = {
  59                 .type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
  60                         ~(~0U << INODE_STR_HASH_BITS),
  61                 .siphash_key = { .k0 = bi->bi_hash_seed }
  62         };
  63
  64         if (unlikely(info.type == BCH_STR_HASH_siphash_old)) {
  65                 SHASH_DESC_ON_STACK(desc, c->sha256);
  66                 u8 digest[SHA256_DIGEST_SIZE];
  67
  68                 desc->tfm = c->sha256;
  69
  70                 crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
  71                                     sizeof(bi->bi_hash_seed), digest);
  72                 memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
  73         }
  74
  75         return info;
  76 }
  77
  78 struct bch_str_hash_ctx {
  79         union {
  80                 u32             crc32c;
  81                 u64             crc64;
  82                 SIPHASH_CTX     siphash;
  83         };
  84 };
  85
  86 static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
  87                                      const struct bch_hash_info *info)
  88 {
  89         switch (info->type) {
  90         case BCH_STR_HASH_crc32c:
  91                 ctx->crc32c = crc32c(~0, &info->siphash_key.k0,
  92                                      sizeof(info->siphash_key.k0));
  93                 break;
  94         case BCH_STR_HASH_crc64:
  95                 ctx->crc64 = crc64_be(~0, &info->siphash_key.k0,
  96                                       sizeof(info->siphash_key.k0));
  97                 break;
  98         case BCH_STR_HASH_siphash_old:
  99         case BCH_STR_HASH_siphash:
 100                 SipHash24_Init(&ctx->siphash, &info->siphash_key);
 101                 break;
 102         default:
 103                 BUG();
 104         }
 105 }
 106
 107 static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
 108                                        const struct bch_hash_info *info,
 109                                        const void *data, size_t len)
 110 {
 111         switch (info->type) {
 112         case BCH_STR_HASH_crc32c:
 113                 ctx->crc32c = crc32c(ctx->crc32c, data, len);
 114                 break;
 115         case BCH_STR_HASH_crc64:
 116                 ctx->crc64 = crc64_be(ctx->crc64, data, len);
 117                 break;
 118         case BCH_STR_HASH_siphash_old:
 119         case BCH_STR_HASH_siphash:
 120                 SipHash24_Update(&ctx->siphash, data, len);
 121                 break;
 122         default:
 123                 BUG();
 124         }
 125 }
 126
 127 static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
 128                                    const struct bch_hash_info *info)
 129 {
 130         switch (info->type) {
 131         case BCH_STR_HASH_crc32c:
 132                 return ctx->crc32c;
 133         case BCH_STR_HASH_crc64:
 134                 return ctx->crc64 >> 1;
 135         case BCH_STR_HASH_siphash_old:
 136         case BCH_STR_HASH_siphash:
 137                 return SipHash24_End(&ctx->siphash) >> 1;
 138         default:
 139                 BUG();
 140         }
 141 }
 142
 143 struct bch_hash_desc {
 144         enum btree_id   btree_id;
 145         u8              key_type;
 146
 147         u64             (*hash_key)(const struct bch_hash_info *, const void *);
 148         u64             (*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c);
 149         bool            (*cmp_key)(struct bkey_s_c, const void *);
 150         bool            (*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
 151         bool            (*is_visible)(subvol_inum inum, struct bkey_s_c);
 152 };
 153
 154 static inline bool is_visible_key(struct bch_hash_desc desc, subvol_inum inum, struct bkey_s_c k)
 155 {
 156         return k.k->type == desc.key_type &&
 157                 (!desc.is_visible ||
 158                  !inum.inum ||
 159                  desc.is_visible(inum, k));
 160 }
 161
 162 static __always_inline int
 163 bch2_hash_lookup(struct btree_trans *trans,
 164                  struct btree_iter *iter,
 165                  const struct bch_hash_desc desc,
 166                  const struct bch_hash_info *info,
 167                  subvol_inum inum, const void *key,
 168                  unsigned flags)
 169 {
 170         struct bkey_s_c k;
 171         u32 snapshot;
 172         int ret;
 173
 174         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 175         if (ret)
 176                 return ret;
 177
 178         for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 179                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 180                            POS(inum.inum, U64_MAX),
 181                            BTREE_ITER_SLOTS|flags, k, ret) {
 182                 if (is_visible_key(desc, inum, k)) {
 183                         if (!desc.cmp_key(k, key))
 184                                 return 0;
 185                 } else if (k.k->type == KEY_TYPE_hash_whiteout) {
 186                         ;
 187                 } else {
 188                         /* hole, not found */
 189                         break;
 190                 }
 191         }
 192         bch2_trans_iter_exit(trans, iter);
 193
 194         return ret ?: -BCH_ERR_ENOENT_str_hash_lookup;
 195 }
 196
 197 static __always_inline int
 198 bch2_hash_hole(struct btree_trans *trans,
 199                struct btree_iter *iter,
 200                const struct bch_hash_desc desc,
 201                const struct bch_hash_info *info,
 202                subvol_inum inum, const void *key)
 203 {
 204         struct bkey_s_c k;
 205         u32 snapshot;
 206         int ret;
 207
 208         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 209         if (ret)
 210                 return ret;
 211
 212         for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 213                            SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 214                            POS(inum.inum, U64_MAX),
 215                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret)
 216                 if (!is_visible_key(desc, inum, k))
 217                         return 0;
 218         bch2_trans_iter_exit(trans, iter);
 219
 220         return ret ?: -BCH_ERR_ENOSPC_str_hash_create;
 221 }
 222
 223 static __always_inline
 224 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 225                              const struct bch_hash_desc desc,
 226                              const struct bch_hash_info *info,
 227                              struct btree_iter *start)
 228 {
 229         struct btree_iter iter;
 230         struct bkey_s_c k;
 231         int ret;
 232
 233         bch2_trans_copy_iter(&iter, start);
 234
 235         bch2_btree_iter_advance(&iter);
 236
 237         for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, k, ret) {
 238                 if (k.k->type != desc.key_type &&
 239                     k.k->type != KEY_TYPE_hash_whiteout)
 240                         break;
 241
 242                 if (k.k->type == desc.key_type &&
 243                     desc.hash_bkey(info, k) <= start->pos.offset) {
 244                         ret = 1;
 245                         break;
 246                 }
 247         }
 248
 249         bch2_trans_iter_exit(trans, &iter);
 250         return ret;
 251 }
 252
 253 static __always_inline
 254 int bch2_hash_set_snapshot(struct btree_trans *trans,
 255                            const struct bch_hash_desc desc,
 256                            const struct bch_hash_info *info,
 257                            subvol_inum inum, u32 snapshot,
 258                            struct bkey_i *insert,
 259                            bch_str_hash_flags_t str_hash_flags,
 260                            int update_flags)
 261 {
 262         struct btree_iter iter, slot = { NULL };
 263         struct bkey_s_c k;
 264         bool found = false;
 265         int ret;
 266
 267         for_each_btree_key_upto_norestart(trans, iter, desc.btree_id,
 268                            SPOS(insert->k.p.inode,
 269                                 desc.hash_bkey(info, bkey_i_to_s_c(insert)),
 270                                 snapshot),
 271                            POS(insert->k.p.inode, U64_MAX),
 272                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 273                 if (is_visible_key(desc, inum, k)) {
 274                         if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 275                                 goto found;
 276
 277                         /* hash collision: */
 278                         continue;
 279                 }
 280
 281                 if (!slot.path &&
 282                     !(str_hash_flags & BCH_HASH_SET_MUST_REPLACE))
 283                         bch2_trans_copy_iter(&slot, &iter);
 284
 285                 if (k.k->type != KEY_TYPE_hash_whiteout)
 286                         goto not_found;
 287         }
 288
 289         if (!ret)
 290                 ret = -BCH_ERR_ENOSPC_str_hash_create;
 291 out:
 292         bch2_trans_iter_exit(trans, &slot);
 293         bch2_trans_iter_exit(trans, &iter);
 294
 295         return ret;
 296 found:
 297         found = true;
 298 not_found:
 299
 300         if (!found && (str_hash_flags & BCH_HASH_SET_MUST_REPLACE)) {
 301                 ret = -BCH_ERR_ENOENT_str_hash_set_must_replace;
 302         } else if (found && (str_hash_flags & BCH_HASH_SET_MUST_CREATE)) {
 303                 ret = -EEXIST;
 304         } else {
 305                 if (!found && slot.path)
 306                         swap(iter, slot);
 307
 308                 insert->k.p = iter.pos;
 309                 ret = bch2_trans_update(trans, &iter, insert, update_flags);
 310         }
 311
 312         goto out;
 313 }
 314
 315 static __always_inline
 316 int bch2_hash_set(struct btree_trans *trans,
 317                   const struct bch_hash_desc desc,
 318                   const struct bch_hash_info *info,
 319                   subvol_inum inum,
 320                   struct bkey_i *insert,
 321                   bch_str_hash_flags_t str_hash_flags)
 322 {
 323         u32 snapshot;
 324         int ret;
 325
 326         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 327         if (ret)
 328                 return ret;
 329
 330         insert->k.p.inode = inum.inum;
 331
 332         return bch2_hash_set_snapshot(trans, desc, info, inum,
 333                                       snapshot, insert, str_hash_flags, 0);
 334 }
 335
 336 static __always_inline
 337 int bch2_hash_delete_at(struct btree_trans *trans,
 338                         const struct bch_hash_desc desc,
 339                         const struct bch_hash_info *info,
 340                         struct btree_iter *iter,
 341                         unsigned update_flags)
 342 {
 343         struct bkey_i *delete;
 344         int ret;
 345
 346         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 347         ret = PTR_ERR_OR_ZERO(delete);
 348         if (ret)
 349                 return ret;
 350
 351         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 352         if (ret < 0)
 353                 return ret;
 354
 355         bkey_init(&delete->k);
 356         delete->k.p = iter->pos;
 357         delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;
 358
 359         return bch2_trans_update(trans, iter, delete, update_flags);
 360 }
 361
 362 static __always_inline
 363 int bch2_hash_delete(struct btree_trans *trans,
 364                      const struct bch_hash_desc desc,
 365                      const struct bch_hash_info *info,
 366                      subvol_inum inum, const void *key)
 367 {
 368         struct btree_iter iter;
 369         int ret;
 370
 371         ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key,
 372                                 BTREE_ITER_INTENT);
 373         if (ret)
 374                 return ret;
 375
 376         ret = bch2_hash_delete_at(trans, desc, info, &iter, 0);
 377         bch2_trans_iter_exit(trans, &iter);
 378         return ret;
 379 }
 380
 381 #endif /* _BCACHEFS_STR_HASH_H */