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 struct btree_iter *
 143 bch2_hash_lookup(struct btree_trans *trans,
 144                  const struct bch_hash_desc desc,
 145                  const struct bch_hash_info *info,
 146                  u64 inode, const void *key,
 147                  unsigned flags)
 148 {
 149         struct btree_iter *iter;
 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 iter;
 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_put(trans, iter);
 170
 171         return ERR_PTR(ret ?: -ENOENT);
 172 }
 173
 174 static __always_inline struct btree_iter *
 175 bch2_hash_hole(struct btree_trans *trans,
 176                const struct bch_hash_desc desc,
 177                const struct bch_hash_info *info,
 178                u64 inode, const void *key)
 179 {
 180         struct btree_iter *iter;
 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 iter;
 192         }
 193
 194         iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 195         bch2_trans_iter_put(trans, iter);
 196
 197         return ERR_PTR(ret ?: -ENOSPC);
 198 }
 199
 200 static __always_inline
 201 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 202                              const struct bch_hash_desc desc,
 203                              const struct bch_hash_info *info,
 204                              struct btree_iter *start)
 205 {
 206         struct btree_iter *iter;
 207         struct bkey_s_c k;
 208         int ret;
 209
 210         iter = bch2_trans_copy_iter(trans, start);
 211
 212         bch2_btree_iter_next_slot(iter);
 213
 214         for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, k, ret) {
 215                 if (k.k->type != desc.key_type &&
 216                     k.k->type != KEY_TYPE_hash_whiteout)
 217                         break;
 218
 219                 if (k.k->type == desc.key_type &&
 220                     desc.hash_bkey(info, k) <= start->pos.offset) {
 221                         iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 222                         ret = 1;
 223                         break;
 224                 }
 225         }
 226
 227         bch2_trans_iter_put(trans, iter);
 228         return ret;
 229 }
 230
 231 static __always_inline
 232 int bch2_hash_set(struct btree_trans *trans,
 233                   const struct bch_hash_desc desc,
 234                   const struct bch_hash_info *info,
 235                   u64 inode, struct bkey_i *insert, int flags)
 236 {
 237         struct btree_iter *iter, *slot = NULL;
 238         struct bkey_s_c k;
 239         bool found = false;
 240         int ret;
 241
 242         for_each_btree_key(trans, iter, desc.btree_id,
 243                            POS(inode, desc.hash_bkey(info, bkey_i_to_s_c(insert))),
 244                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 245                 if (iter->pos.inode != inode)
 246                         break;
 247
 248                 if (k.k->type == desc.key_type) {
 249                         if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 250                                 goto found;
 251
 252                         /* hash collision: */
 253                         continue;
 254                 }
 255
 256                 if (!slot &&
 257                     !(flags & BCH_HASH_SET_MUST_REPLACE))
 258                         slot = bch2_trans_copy_iter(trans, iter);
 259
 260                 if (k.k->type != KEY_TYPE_hash_whiteout)
 261                         goto not_found;
 262         }
 263
 264         if (!ret)
 265                 ret = -ENOSPC;
 266 out:
 267         bch2_trans_iter_put(trans, slot);
 268         bch2_trans_iter_put(trans, iter);
 269
 270         return ret;
 271 found:
 272         found = true;
 273 not_found:
 274
 275         if (!found && (flags & BCH_HASH_SET_MUST_REPLACE)) {
 276                 ret = -ENOENT;
 277         } else if (found && (flags & BCH_HASH_SET_MUST_CREATE)) {
 278                 ret = -EEXIST;
 279         } else {
 280                 if (!found && slot)
 281                         swap(iter, slot);
 282
 283                 insert->k.p = iter->pos;
 284                 ret = bch2_trans_update(trans, iter, insert, 0);
 285         }
 286
 287         goto out;
 288 }
 289
 290 static __always_inline
 291 int bch2_hash_delete_at(struct btree_trans *trans,
 292                         const struct bch_hash_desc desc,
 293                         const struct bch_hash_info *info,
 294                         struct btree_iter *iter)
 295 {
 296         struct bkey_i *delete;
 297         int ret;
 298
 299         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 300         ret = PTR_ERR_OR_ZERO(delete);
 301         if (ret)
 302                 return ret;
 303
 304         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 305         if (ret < 0)
 306                 return ret;
 307
 308         bkey_init(&delete->k);
 309         delete->k.p = iter->pos;
 310         delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;
 311
 312         return bch2_trans_update(trans, iter, delete, 0);
 313 }
 314
 315 static __always_inline
 316 int bch2_hash_delete(struct btree_trans *trans,
 317                      const struct bch_hash_desc desc,
 318                      const struct bch_hash_info *info,
 319                      u64 inode, const void *key)
 320 {
 321         struct btree_iter *iter;
 322         int ret;
 323
 324         iter = bch2_hash_lookup(trans, desc, info, inode, key,
 325                                 BTREE_ITER_INTENT);
 326         if (IS_ERR(iter))
 327                 return PTR_ERR(iter);
 328
 329         ret = bch2_hash_delete_at(trans, desc, info, iter);
 330         bch2_trans_iter_put(trans, iter);
 331         return ret;
 332 }
 333
 334 #endif /* _BCACHEFS_STR_HASH_H */