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 "super.h"
  12
  13 #include <linux/crc32c.h>
  14 #include <crypto/hash.h>
  15 #include <crypto/sha2.h>
  16
  17 static inline enum bch_str_hash_type
  18 bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt)
  19 {
  20         switch (opt) {
  21         case BCH_STR_HASH_OPT_crc32c:
  22                 return BCH_STR_HASH_CRC32C;
  23         case BCH_STR_HASH_OPT_crc64:
  24                 return BCH_STR_HASH_CRC64;
  25         case BCH_STR_HASH_OPT_siphash:
  26                 return c->sb.features & (1ULL << BCH_FEATURE_new_siphash)
  27                         ? BCH_STR_HASH_SIPHASH
  28                         : BCH_STR_HASH_SIPHASH_OLD;
  29         default:
  30              BUG();
  31         }
  32 }
  33
  34 struct bch_hash_info {
  35         u8                      type;
  36         /*
  37          * For crc32 or crc64 string hashes the first key value of
  38          * the siphash_key (k0) is used as the key.
  39          */
  40         SIPHASH_KEY     siphash_key;
  41 };
  42
  43 static inline struct bch_hash_info
  44 bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
  45 {
  46         /* XXX ick */
  47         struct bch_hash_info info = {
  48                 .type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
  49                         ~(~0U << INODE_STR_HASH_BITS),
  50                 .siphash_key = { .k0 = bi->bi_hash_seed }
  51         };
  52
  53         if (unlikely(info.type == BCH_STR_HASH_SIPHASH_OLD)) {
  54                 SHASH_DESC_ON_STACK(desc, c->sha256);
  55                 u8 digest[SHA256_DIGEST_SIZE];
  56
  57                 desc->tfm = c->sha256;
  58
  59                 crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
  60                                     sizeof(bi->bi_hash_seed), digest);
  61                 memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
  62         }
  63
  64         return info;
  65 }
  66
  67 struct bch_str_hash_ctx {
  68         union {
  69                 u32             crc32c;
  70                 u64             crc64;
  71                 SIPHASH_CTX     siphash;
  72         };
  73 };
  74
  75 static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
  76                                      const struct bch_hash_info *info)
  77 {
  78         switch (info->type) {
  79         case BCH_STR_HASH_CRC32C:
  80                 ctx->crc32c = crc32c(~0, &info->siphash_key.k0,
  81                                      sizeof(info->siphash_key.k0));
  82                 break;
  83         case BCH_STR_HASH_CRC64:
  84                 ctx->crc64 = crc64_be(~0, &info->siphash_key.k0,
  85                                       sizeof(info->siphash_key.k0));
  86                 break;
  87         case BCH_STR_HASH_SIPHASH_OLD:
  88         case BCH_STR_HASH_SIPHASH:
  89                 SipHash24_Init(&ctx->siphash, &info->siphash_key);
  90                 break;
  91         default:
  92                 BUG();
  93         }
  94 }
  95
  96 static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
  97                                        const struct bch_hash_info *info,
  98                                        const void *data, size_t len)
  99 {
 100         switch (info->type) {
 101         case BCH_STR_HASH_CRC32C:
 102                 ctx->crc32c = crc32c(ctx->crc32c, data, len);
 103                 break;
 104         case BCH_STR_HASH_CRC64:
 105                 ctx->crc64 = crc64_be(ctx->crc64, data, len);
 106                 break;
 107         case BCH_STR_HASH_SIPHASH_OLD:
 108         case BCH_STR_HASH_SIPHASH:
 109                 SipHash24_Update(&ctx->siphash, data, len);
 110                 break;
 111         default:
 112                 BUG();
 113         }
 114 }
 115
 116 static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
 117                                    const struct bch_hash_info *info)
 118 {
 119         switch (info->type) {
 120         case BCH_STR_HASH_CRC32C:
 121                 return ctx->crc32c;
 122         case BCH_STR_HASH_CRC64:
 123                 return ctx->crc64 >> 1;
 124         case BCH_STR_HASH_SIPHASH_OLD:
 125         case BCH_STR_HASH_SIPHASH:
 126                 return SipHash24_End(&ctx->siphash) >> 1;
 127         default:
 128                 BUG();
 129         }
 130 }
 131
 132 struct bch_hash_desc {
 133         enum btree_id   btree_id;
 134         u8              key_type;
 135
 136         u64             (*hash_key)(const struct bch_hash_info *, const void *);
 137         u64             (*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c);
 138         bool            (*cmp_key)(struct bkey_s_c, const void *);
 139         bool            (*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
 140 };
 141
 142 static __always_inline int
 143 bch2_hash_lookup(struct btree_trans *trans,
 144                  struct btree_iter *iter,
 145                  const struct bch_hash_desc desc,
 146                  const struct bch_hash_info *info,
 147                  u64 inode, const void *key,
 148                  unsigned flags)
 149 {
 150         struct bkey_s_c k;
 151         int ret;
 152
 153         for_each_btree_key(trans, *iter, desc.btree_id,
 154                            POS(inode, desc.hash_key(info, key)),
 155                            BTREE_ITER_SLOTS|flags, k, ret) {
 156                 if (iter->pos.inode != inode)
 157                         break;
 158
 159                 if (k.k->type == desc.key_type) {
 160                         if (!desc.cmp_key(k, key))
 161                                 return 0;
 162                 } else if (k.k->type == KEY_TYPE_hash_whiteout) {
 163                         ;
 164                 } else {
 165                         /* hole, not found */
 166                         break;
 167                 }
 168         }
 169         bch2_trans_iter_exit(trans, iter);
 170
 171         return ret ?: -ENOENT;
 172 }
 173
 174 static __always_inline int
 175 bch2_hash_hole(struct btree_trans *trans,
 176                struct btree_iter *iter,
 177                const struct bch_hash_desc desc,
 178                const struct bch_hash_info *info,
 179                u64 inode, const void *key)
 180 {
 181         struct bkey_s_c k;
 182         int ret;
 183
 184         for_each_btree_key(trans, *iter, desc.btree_id,
 185                            POS(inode, desc.hash_key(info, key)),
 186                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 187                 if (iter->pos.inode != inode)
 188                         break;
 189
 190                 if (k.k->type != desc.key_type)
 191                         return 0;
 192         }
 193         bch2_trans_iter_exit(trans, iter);
 194
 195         return ret ?: -ENOSPC;
 196 }
 197
 198 static __always_inline
 199 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 200                              const struct bch_hash_desc desc,
 201                              const struct bch_hash_info *info,
 202                              struct btree_iter *start)
 203 {
 204         struct btree_iter iter;
 205         struct bkey_s_c k;
 206         int ret;
 207
 208         bch2_trans_copy_iter(&iter, start);
 209
 210         bch2_btree_iter_advance(&iter);
 211
 212         for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, k, ret) {
 213                 if (k.k->type != desc.key_type &&
 214                     k.k->type != KEY_TYPE_hash_whiteout)
 215                         break;
 216
 217                 if (k.k->type == desc.key_type &&
 218                     desc.hash_bkey(info, k) <= start->pos.offset) {
 219                         ret = 1;
 220                         break;
 221                 }
 222         }
 223
 224         bch2_trans_iter_exit(trans, &iter);
 225         return ret;
 226 }
 227
 228 static __always_inline
 229 int bch2_hash_set(struct btree_trans *trans,
 230                   const struct bch_hash_desc desc,
 231                   const struct bch_hash_info *info,
 232                   u64 inode, struct bkey_i *insert, int flags)
 233 {
 234         struct btree_iter iter, slot = { NULL };
 235         struct bkey_s_c k;
 236         bool found = false;
 237         int ret;
 238
 239         for_each_btree_key(trans, iter, desc.btree_id,
 240                            POS(inode, desc.hash_bkey(info, bkey_i_to_s_c(insert))),
 241                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 242                 if (iter.pos.inode != inode)
 243                         break;
 244
 245                 if (k.k->type == desc.key_type) {
 246                         if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 247                                 goto found;
 248
 249                         /* hash collision: */
 250                         continue;
 251                 }
 252
 253                 if (!slot.path &&
 254                     !(flags & BCH_HASH_SET_MUST_REPLACE))
 255                         bch2_trans_copy_iter(&slot, &iter);
 256
 257                 if (k.k->type != KEY_TYPE_hash_whiteout)
 258                         goto not_found;
 259         }
 260
 261         if (!ret)
 262                 ret = -ENOSPC;
 263 out:
 264         bch2_trans_iter_exit(trans, &slot);
 265         bch2_trans_iter_exit(trans, &iter);
 266
 267         return ret;
 268 found:
 269         found = true;
 270 not_found:
 271
 272         if (!found && (flags & BCH_HASH_SET_MUST_REPLACE)) {
 273                 ret = -ENOENT;
 274         } else if (found && (flags & BCH_HASH_SET_MUST_CREATE)) {
 275                 ret = -EEXIST;
 276         } else {
 277                 if (!found && slot.path)
 278                         swap(iter, slot);
 279
 280                 insert->k.p = iter.pos;
 281                 ret = bch2_trans_update(trans, &iter, insert, 0);
 282         }
 283
 284         goto out;
 285 }
 286
 287 static __always_inline
 288 int bch2_hash_delete_at(struct btree_trans *trans,
 289                         const struct bch_hash_desc desc,
 290                         const struct bch_hash_info *info,
 291                         struct btree_iter *iter)
 292 {
 293         struct bkey_i *delete;
 294         int ret;
 295
 296         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 297         ret = PTR_ERR_OR_ZERO(delete);
 298         if (ret)
 299                 return ret;
 300
 301         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 302         if (ret < 0)
 303                 return ret;
 304
 305         bkey_init(&delete->k);
 306         delete->k.p = iter->pos;
 307         delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;
 308
 309         return bch2_trans_update(trans, iter, delete, 0);
 310 }
 311
 312 static __always_inline
 313 int bch2_hash_delete(struct btree_trans *trans,
 314                      const struct bch_hash_desc desc,
 315                      const struct bch_hash_info *info,
 316                      u64 inode, const void *key)
 317 {
 318         struct btree_iter iter;
 319         int ret;
 320
 321         ret = bch2_hash_lookup(trans, &iter, desc, info, inode, key,
 322                                 BTREE_ITER_INTENT);
 323         if (ret)
 324                 return ret;
 325
 326         ret = bch2_hash_delete_at(trans, desc, info, &iter);
 327         bch2_trans_iter_exit(trans, &iter);
 328         return ret;
 329 }
 330
 331 #endif /* _BCACHEFS_STR_HASH_H */