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 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         union {
  37                 __le64          crc_key;
  38                 SIPHASH_KEY     siphash_key;
  39         };
  40 };
  41
  42 static inline struct bch_hash_info
  43 bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
  44 {
  45         /* XXX ick */
  46         struct bch_hash_info info = {
  47                 .type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
  48                         ~(~0U << INODE_STR_HASH_BITS),
  49                 .crc_key = bi->bi_hash_seed,
  50         };
  51
  52         if (unlikely(info.type == BCH_STR_HASH_SIPHASH_OLD)) {
  53                 SHASH_DESC_ON_STACK(desc, c->sha256);
  54                 u8 digest[SHA256_DIGEST_SIZE];
  55
  56                 desc->tfm = c->sha256;
  57
  58                 crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
  59                                     sizeof(bi->bi_hash_seed), digest);
  60                 memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
  61         }
  62
  63         return info;
  64 }
  65
  66 struct bch_str_hash_ctx {
  67         union {
  68                 u32             crc32c;
  69                 u64             crc64;
  70                 SIPHASH_CTX     siphash;
  71         };
  72 };
  73
  74 static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
  75                                      const struct bch_hash_info *info)
  76 {
  77         switch (info->type) {
  78         case BCH_STR_HASH_CRC32C:
  79                 ctx->crc32c = crc32c(~0, &info->crc_key, sizeof(info->crc_key));
  80                 break;
  81         case BCH_STR_HASH_CRC64:
  82                 ctx->crc64 = crc64_be(~0, &info->crc_key, sizeof(info->crc_key));
  83                 break;
  84         case BCH_STR_HASH_SIPHASH_OLD:
  85         case BCH_STR_HASH_SIPHASH:
  86                 SipHash24_Init(&ctx->siphash, &info->siphash_key);
  87                 break;
  88         default:
  89                 BUG();
  90         }
  91 }
  92
  93 static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
  94                                        const struct bch_hash_info *info,
  95                                        const void *data, size_t len)
  96 {
  97         switch (info->type) {
  98         case BCH_STR_HASH_CRC32C:
  99                 ctx->crc32c = crc32c(ctx->crc32c, data, len);
 100                 break;
 101         case BCH_STR_HASH_CRC64:
 102                 ctx->crc64 = crc64_be(ctx->crc64, data, len);
 103                 break;
 104         case BCH_STR_HASH_SIPHASH_OLD:
 105         case BCH_STR_HASH_SIPHASH:
 106                 SipHash24_Update(&ctx->siphash, data, len);
 107                 break;
 108         default:
 109                 BUG();
 110         }
 111 }
 112
 113 static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
 114                                    const struct bch_hash_info *info)
 115 {
 116         switch (info->type) {
 117         case BCH_STR_HASH_CRC32C:
 118                 return ctx->crc32c;
 119         case BCH_STR_HASH_CRC64:
 120                 return ctx->crc64 >> 1;
 121         case BCH_STR_HASH_SIPHASH_OLD:
 122         case BCH_STR_HASH_SIPHASH:
 123                 return SipHash24_End(&ctx->siphash) >> 1;
 124         default:
 125                 BUG();
 126         }
 127 }
 128
 129 struct bch_hash_desc {
 130         enum btree_id   btree_id;
 131         u8              key_type;
 132
 133         u64             (*hash_key)(const struct bch_hash_info *, const void *);
 134         u64             (*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c);
 135         bool            (*cmp_key)(struct bkey_s_c, const void *);
 136         bool            (*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
 137 };
 138
 139 static __always_inline struct btree_iter *
 140 bch2_hash_lookup(struct btree_trans *trans,
 141                  const struct bch_hash_desc desc,
 142                  const struct bch_hash_info *info,
 143                  u64 inode, const void *key,
 144                  unsigned flags)
 145 {
 146         struct btree_iter *iter;
 147         struct bkey_s_c k;
 148         int ret;
 149
 150         for_each_btree_key(trans, iter, desc.btree_id,
 151                            POS(inode, desc.hash_key(info, key)),
 152                            BTREE_ITER_SLOTS|flags, k, ret) {
 153                 if (iter->pos.inode != inode)
 154                         break;
 155
 156                 if (k.k->type == desc.key_type) {
 157                         if (!desc.cmp_key(k, key))
 158                                 return iter;
 159                 } else if (k.k->type == KEY_TYPE_whiteout) {
 160                         ;
 161                 } else {
 162                         /* hole, not found */
 163                         break;
 164                 }
 165         }
 166         bch2_trans_iter_put(trans, iter);
 167
 168         return ERR_PTR(ret ?: -ENOENT);
 169 }
 170
 171 static __always_inline struct btree_iter *
 172 bch2_hash_hole(struct btree_trans *trans,
 173                const struct bch_hash_desc desc,
 174                const struct bch_hash_info *info,
 175                u64 inode, const void *key)
 176 {
 177         struct btree_iter *iter;
 178         struct bkey_s_c k;
 179         int ret;
 180
 181         for_each_btree_key(trans, iter, desc.btree_id,
 182                            POS(inode, desc.hash_key(info, key)),
 183                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 184                 if (iter->pos.inode != inode)
 185                         break;
 186
 187                 if (k.k->type != desc.key_type)
 188                         return iter;
 189         }
 190
 191         iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 192         bch2_trans_iter_put(trans, iter);
 193
 194         return ERR_PTR(ret ?: -ENOSPC);
 195 }
 196
 197 static __always_inline
 198 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 199                              const struct bch_hash_desc desc,
 200                              const struct bch_hash_info *info,
 201                              struct btree_iter *start)
 202 {
 203         struct btree_iter *iter;
 204         struct bkey_s_c k;
 205         int ret;
 206
 207         iter = bch2_trans_copy_iter(trans, start);
 208
 209         bch2_btree_iter_next_slot(iter);
 210
 211         for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, k, ret) {
 212                 if (k.k->type != desc.key_type &&
 213                     k.k->type != KEY_TYPE_whiteout)
 214                         break;
 215
 216                 if (k.k->type == desc.key_type &&
 217                     desc.hash_bkey(info, k) <= start->pos.offset) {
 218                         iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 219                         ret = 1;
 220                         break;
 221                 }
 222         }
 223
 224         bch2_trans_iter_put(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 &&
 254                     !(flags & BCH_HASH_SET_MUST_REPLACE))
 255                         slot = bch2_trans_copy_iter(trans, iter);
 256
 257                 if (k.k->type != KEY_TYPE_whiteout)
 258                         goto not_found;
 259         }
 260
 261         if (!ret)
 262                 ret = -ENOSPC;
 263 out:
 264         bch2_trans_iter_put(trans, slot);
 265         bch2_trans_iter_put(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)
 278                         swap(iter, slot);
 279
 280                 insert->k.p = iter->pos;
 281                 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         ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 297         if (ret < 0)
 298                 return ret;
 299
 300         delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 301         if (IS_ERR(delete))
 302                 return PTR_ERR(delete);
 303
 304         bkey_init(&delete->k);
 305         delete->k.p = iter->pos;
 306         delete->k.type = ret ? KEY_TYPE_whiteout : KEY_TYPE_deleted;
 307
 308         bch2_trans_update(trans, iter, delete, 0);
 309         return 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         iter = bch2_hash_lookup(trans, desc, info, inode, key,
 322                                 BTREE_ITER_INTENT);
 323         if (IS_ERR(iter))
 324                 return PTR_ERR(iter);
 325
 326         ret = bch2_hash_delete_at(trans, desc, info, iter);
 327         bch2_trans_iter_put(trans, iter);
 328         return ret;
 329 }
 330
 331 #endif /* _BCACHEFS_STR_HASH_H */