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/sha.h>
  16
  17 struct bch_hash_info {
  18         u8                      type;
  19         union {
  20                 __le64          crc_key;
  21                 SIPHASH_KEY     siphash_key;
  22         };
  23 };
  24
  25 static inline struct bch_hash_info
  26 bch2_hash_info_init(struct bch_fs *c,
  27                    const struct bch_inode_unpacked *bi)
  28 {
  29         /* XXX ick */
  30         struct bch_hash_info info = {
  31                 .type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
  32                         ~(~0U << INODE_STR_HASH_BITS)
  33         };
  34
  35         switch (info.type) {
  36         case BCH_STR_HASH_CRC32C:
  37         case BCH_STR_HASH_CRC64:
  38                 info.crc_key = bi->bi_hash_seed;
  39                 break;
  40         case BCH_STR_HASH_SIPHASH: {
  41                 SHASH_DESC_ON_STACK(desc, c->sha256);
  42                 u8 digest[SHA256_DIGEST_SIZE];
  43
  44                 desc->tfm = c->sha256;
  45
  46                 crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
  47                                     sizeof(bi->bi_hash_seed), digest);
  48                 memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
  49                 break;
  50         }
  51         default:
  52                 BUG();
  53         }
  54
  55         return info;
  56 }
  57
  58 struct bch_str_hash_ctx {
  59         union {
  60                 u32             crc32c;
  61                 u64             crc64;
  62                 SIPHASH_CTX     siphash;
  63         };
  64 };
  65
  66 static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
  67                                      const struct bch_hash_info *info)
  68 {
  69         switch (info->type) {
  70         case BCH_STR_HASH_CRC32C:
  71                 ctx->crc32c = crc32c(~0, &info->crc_key, sizeof(info->crc_key));
  72                 break;
  73         case BCH_STR_HASH_CRC64:
  74                 ctx->crc64 = crc64_be(~0, &info->crc_key, sizeof(info->crc_key));
  75                 break;
  76         case BCH_STR_HASH_SIPHASH:
  77                 SipHash24_Init(&ctx->siphash, &info->siphash_key);
  78                 break;
  79         default:
  80                 BUG();
  81         }
  82 }
  83
  84 static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
  85                                        const struct bch_hash_info *info,
  86                                        const void *data, size_t len)
  87 {
  88         switch (info->type) {
  89         case BCH_STR_HASH_CRC32C:
  90                 ctx->crc32c = crc32c(ctx->crc32c, data, len);
  91                 break;
  92         case BCH_STR_HASH_CRC64:
  93                 ctx->crc64 = crc64_be(ctx->crc64, data, len);
  94                 break;
  95         case BCH_STR_HASH_SIPHASH:
  96                 SipHash24_Update(&ctx->siphash, data, len);
  97                 break;
  98         default:
  99                 BUG();
 100         }
 101 }
 102
 103 static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
 104                                    const struct bch_hash_info *info)
 105 {
 106         switch (info->type) {
 107         case BCH_STR_HASH_CRC32C:
 108                 return ctx->crc32c;
 109         case BCH_STR_HASH_CRC64:
 110                 return ctx->crc64 >> 1;
 111         case BCH_STR_HASH_SIPHASH:
 112                 return SipHash24_End(&ctx->siphash) >> 1;
 113         default:
 114                 BUG();
 115         }
 116 }
 117
 118 struct bch_hash_desc {
 119         enum btree_id   btree_id;
 120         u8              key_type;
 121
 122         u64             (*hash_key)(const struct bch_hash_info *, const void *);
 123         u64             (*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c);
 124         bool            (*cmp_key)(struct bkey_s_c, const void *);
 125         bool            (*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
 126 };
 127
 128 static __always_inline struct btree_iter *
 129 bch2_hash_lookup(struct btree_trans *trans,
 130                  const struct bch_hash_desc desc,
 131                  const struct bch_hash_info *info,
 132                  u64 inode, const void *key,
 133                  unsigned flags)
 134 {
 135         struct btree_iter *iter;
 136         struct bkey_s_c k;
 137         int ret;
 138
 139         for_each_btree_key(trans, iter, desc.btree_id,
 140                            POS(inode, desc.hash_key(info, key)),
 141                            BTREE_ITER_SLOTS|flags, k, ret) {
 142                 if (iter->pos.inode != inode)
 143                         break;
 144
 145                 if (k.k->type == desc.key_type) {
 146                         if (!desc.cmp_key(k, key))
 147                                 return iter;
 148                 } else if (k.k->type == KEY_TYPE_whiteout) {
 149                         ;
 150                 } else {
 151                         /* hole, not found */
 152                         break;
 153                 }
 154         }
 155
 156         return ERR_PTR(ret ?: -ENOENT);
 157 }
 158
 159 static __always_inline struct btree_iter *
 160 bch2_hash_hole(struct btree_trans *trans,
 161                const struct bch_hash_desc desc,
 162                const struct bch_hash_info *info,
 163                u64 inode, const void *key)
 164 {
 165         struct btree_iter *iter;
 166         struct bkey_s_c k;
 167         int ret;
 168
 169         for_each_btree_key(trans, iter, desc.btree_id,
 170                            POS(inode, desc.hash_key(info, key)),
 171                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 172                 if (iter->pos.inode != inode)
 173                         break;
 174
 175                 if (k.k->type != desc.key_type)
 176                         return iter;
 177         }
 178
 179         return ERR_PTR(ret ?: -ENOSPC);
 180 }
 181
 182 static __always_inline
 183 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 184                              const struct bch_hash_desc desc,
 185                              const struct bch_hash_info *info,
 186                              struct btree_iter *start)
 187 {
 188         struct btree_iter *iter;
 189         struct bkey_s_c k;
 190         int ret;
 191
 192         iter = bch2_trans_copy_iter(trans, start);
 193         if (IS_ERR(iter))
 194                 return PTR_ERR(iter);
 195
 196         bch2_btree_iter_next_slot(iter);
 197
 198         for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, k, ret) {
 199                 if (k.k->type != desc.key_type &&
 200                     k.k->type != KEY_TYPE_whiteout)
 201                         break;
 202
 203                 if (k.k->type == desc.key_type &&
 204                     desc.hash_bkey(info, k) <= start->pos.offset) {
 205                         iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 206                         ret = 1;
 207                         break;
 208                 }
 209         }
 210
 211         bch2_trans_iter_put(trans, iter);
 212         return ret;
 213 }
 214
 215 static __always_inline
 216 int bch2_hash_set(struct btree_trans *trans,
 217                   const struct bch_hash_desc desc,
 218                   const struct bch_hash_info *info,
 219                   u64 inode, struct bkey_i *insert, int flags)
 220 {
 221         struct btree_iter *iter, *slot = NULL;
 222         struct bkey_s_c k;
 223         bool found = false;
 224         int ret;
 225
 226         for_each_btree_key(trans, iter, desc.btree_id,
 227                            POS(inode, desc.hash_bkey(info, bkey_i_to_s_c(insert))),
 228                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 229                 if (iter->pos.inode != inode)
 230                         break;
 231
 232                 if (k.k->type == desc.key_type) {
 233                         if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 234                                 goto found;
 235
 236                         /* hash collision: */
 237                         continue;
 238                 }
 239
 240                 if (!slot &&
 241                     !(flags & BCH_HASH_SET_MUST_REPLACE)) {
 242                         slot = bch2_trans_copy_iter(trans, iter);
 243                         if (IS_ERR(slot))
 244                                 return PTR_ERR(slot);
 245                 }
 246
 247                 if (k.k->type != KEY_TYPE_whiteout)
 248                         goto not_found;
 249         }
 250
 251         if (!ret)
 252                 ret = -ENOSPC;
 253 out:
 254         if (slot)
 255                 bch2_trans_iter_put(trans, slot);
 256         bch2_trans_iter_put(trans, iter);
 257
 258         return ret;
 259 found:
 260         found = true;
 261 not_found:
 262
 263         if (!found && (flags & BCH_HASH_SET_MUST_REPLACE)) {
 264                 ret = -ENOENT;
 265         } else if (found && (flags & BCH_HASH_SET_MUST_CREATE)) {
 266                 ret = -EEXIST;
 267         } else {
 268                 if (!found && slot)
 269                         swap(iter, slot);
 270
 271                 insert->k.p = iter->pos;
 272                 bch2_trans_update(trans, iter, insert);
 273         }
 274
 275         goto out;
 276 }
 277
 278 static __always_inline
 279 int bch2_hash_delete_at(struct btree_trans *trans,
 280                         const struct bch_hash_desc desc,
 281                         const struct bch_hash_info *info,
 282                         struct btree_iter *iter)
 283 {
 284         struct bkey_i *delete;
 285         int ret;
 286
 287         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 288         if (ret < 0)
 289                 return ret;
 290
 291         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 292         if (IS_ERR(delete))
 293                 return PTR_ERR(delete);
 294
 295         bkey_init(&delete->k);
 296         delete->k.p = iter->pos;
 297         delete->k.type = ret ? KEY_TYPE_whiteout : KEY_TYPE_deleted;
 298
 299         bch2_trans_update(trans, iter, delete);
 300         return 0;
 301 }
 302
 303 static __always_inline
 304 int bch2_hash_delete(struct btree_trans *trans,
 305                      const struct bch_hash_desc desc,
 306                      const struct bch_hash_info *info,
 307                      u64 inode, const void *key)
 308 {
 309         struct btree_iter *iter;
 310
 311         iter = bch2_hash_lookup(trans, desc, info, inode, key,
 312                                 BTREE_ITER_INTENT);
 313         if (IS_ERR(iter))
 314                 return PTR_ERR(iter);
 315
 316         return bch2_hash_delete_at(trans, desc, info, iter);
 317 }
 318
 319 #endif /* _BCACHEFS_STR_HASH_H */