diff options
Diffstat (limited to 'c_src/libbcachefs/str_hash.h')
| -rw-r--r-- | c_src/libbcachefs/str_hash.h | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/c_src/libbcachefs/str_hash.h b/c_src/libbcachefs/str_hash.h new file mode 100644 index 00000000..89fdb7c2 --- /dev/null +++ b/c_src/libbcachefs/str_hash.h @@ -0,0 +1,381 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _BCACHEFS_STR_HASH_H +#define _BCACHEFS_STR_HASH_H + +#include "btree_iter.h" +#include "btree_update.h" +#include "checksum.h" +#include "error.h" +#include "inode.h" +#include "siphash.h" +#include "subvolume.h" +#include "super.h" + +#include <linux/crc32c.h> +#include <crypto/hash.h> +#include <crypto/sha2.h> + +typedef unsigned __bitwise bch_str_hash_flags_t; + +enum bch_str_hash_flags { + __BCH_HASH_SET_MUST_CREATE, + __BCH_HASH_SET_MUST_REPLACE, +}; + +#define BCH_HASH_SET_MUST_CREATE (__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_CREATE) +#define BCH_HASH_SET_MUST_REPLACE (__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_REPLACE) + +static inline enum bch_str_hash_type +bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt) +{ + switch (opt) { + case BCH_STR_HASH_OPT_crc32c: + return BCH_STR_HASH_crc32c; + case BCH_STR_HASH_OPT_crc64: + return BCH_STR_HASH_crc64; + case BCH_STR_HASH_OPT_siphash: + return c->sb.features & (1ULL << BCH_FEATURE_new_siphash) + ? BCH_STR_HASH_siphash + : BCH_STR_HASH_siphash_old; + default: + BUG(); + } +} + +struct bch_hash_info { + u8 type; + /* + * For crc32 or crc64 string hashes the first key value of + * the siphash_key (k0) is used as the key. + */ + SIPHASH_KEY siphash_key; +}; + +static inline struct bch_hash_info +bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi) +{ + /* XXX ick */ + struct bch_hash_info info = { + .type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) & + ~(~0U << INODE_STR_HASH_BITS), + .siphash_key = { .k0 = bi->bi_hash_seed } + }; + + if (unlikely(info.type == BCH_STR_HASH_siphash_old)) { + SHASH_DESC_ON_STACK(desc, c->sha256); + u8 digest[SHA256_DIGEST_SIZE]; + + desc->tfm = c->sha256; + + crypto_shash_digest(desc, (void *) &bi->bi_hash_seed, + sizeof(bi->bi_hash_seed), digest); + memcpy(&info.siphash_key, digest, sizeof(info.siphash_key)); + } + + return info; +} + +struct bch_str_hash_ctx { + union { + u32 crc32c; + u64 crc64; + SIPHASH_CTX siphash; + }; +}; + +static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx, + const struct bch_hash_info *info) +{ + switch (info->type) { + case BCH_STR_HASH_crc32c: + ctx->crc32c = crc32c(~0, &info->siphash_key.k0, + sizeof(info->siphash_key.k0)); + break; + case BCH_STR_HASH_crc64: + ctx->crc64 = crc64_be(~0, &info->siphash_key.k0, + sizeof(info->siphash_key.k0)); + break; + case BCH_STR_HASH_siphash_old: + case BCH_STR_HASH_siphash: + SipHash24_Init(&ctx->siphash, &info->siphash_key); + break; + default: + BUG(); + } +} + +static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx, + const struct bch_hash_info *info, + const void *data, size_t len) +{ + switch (info->type) { + case BCH_STR_HASH_crc32c: + ctx->crc32c = crc32c(ctx->crc32c, data, len); + break; + case BCH_STR_HASH_crc64: + ctx->crc64 = crc64_be(ctx->crc64, data, len); + break; + case BCH_STR_HASH_siphash_old: + case BCH_STR_HASH_siphash: + SipHash24_Update(&ctx->siphash, data, len); + break; + default: + BUG(); + } +} + +static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx, + const struct bch_hash_info *info) +{ + switch (info->type) { + case BCH_STR_HASH_crc32c: + return ctx->crc32c; + case BCH_STR_HASH_crc64: + return ctx->crc64 >> 1; + case BCH_STR_HASH_siphash_old: + case BCH_STR_HASH_siphash: + return SipHash24_End(&ctx->siphash) >> 1; + default: + BUG(); + } +} + +struct bch_hash_desc { + enum btree_id btree_id; + u8 key_type; + + u64 (*hash_key)(const struct bch_hash_info *, const void *); + u64 (*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c); + bool (*cmp_key)(struct bkey_s_c, const void *); + bool (*cmp_bkey)(struct bkey_s_c, struct bkey_s_c); + bool (*is_visible)(subvol_inum inum, struct bkey_s_c); +}; + +static inline bool is_visible_key(struct bch_hash_desc desc, subvol_inum inum, struct bkey_s_c k) +{ + return k.k->type == desc.key_type && + (!desc.is_visible || + !inum.inum || + desc.is_visible(inum, k)); +} + +static __always_inline int +bch2_hash_lookup(struct btree_trans *trans, + struct btree_iter *iter, + const struct bch_hash_desc desc, + const struct bch_hash_info *info, + subvol_inum inum, const void *key, + unsigned flags) +{ + struct bkey_s_c k; + u32 snapshot; + int ret; + + ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot); + if (ret) + return ret; + + for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id, + SPOS(inum.inum, desc.hash_key(info, key), snapshot), + POS(inum.inum, U64_MAX), + BTREE_ITER_SLOTS|flags, k, ret) { + if (is_visible_key(desc, inum, k)) { + if (!desc.cmp_key(k, key)) + return 0; + } else if (k.k->type == KEY_TYPE_hash_whiteout) { + ; + } else { + /* hole, not found */ + break; + } + } + bch2_trans_iter_exit(trans, iter); + + return ret ?: -BCH_ERR_ENOENT_str_hash_lookup; +} + +static __always_inline int +bch2_hash_hole(struct btree_trans *trans, + struct btree_iter *iter, + const struct bch_hash_desc desc, + const struct bch_hash_info *info, + subvol_inum inum, const void *key) +{ + struct bkey_s_c k; + u32 snapshot; + int ret; + + ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot); + if (ret) + return ret; + + for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id, + SPOS(inum.inum, desc.hash_key(info, key), snapshot), + POS(inum.inum, U64_MAX), + BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) + if (!is_visible_key(desc, inum, k)) + return 0; + bch2_trans_iter_exit(trans, iter); + + return ret ?: -BCH_ERR_ENOSPC_str_hash_create; +} + +static __always_inline +int bch2_hash_needs_whiteout(struct btree_trans *trans, + const struct bch_hash_desc desc, + const struct bch_hash_info *info, + struct btree_iter *start) +{ + struct btree_iter iter; + struct bkey_s_c k; + int ret; + + bch2_trans_copy_iter(&iter, start); + + bch2_btree_iter_advance(&iter); + + for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, k, ret) { + if (k.k->type != desc.key_type && + k.k->type != KEY_TYPE_hash_whiteout) + break; + + if (k.k->type == desc.key_type && + desc.hash_bkey(info, k) <= start->pos.offset) { + ret = 1; + break; + } + } + + bch2_trans_iter_exit(trans, &iter); + return ret; +} + +static __always_inline +int bch2_hash_set_snapshot(struct btree_trans *trans, + const struct bch_hash_desc desc, + const struct bch_hash_info *info, + subvol_inum inum, u32 snapshot, + struct bkey_i *insert, + bch_str_hash_flags_t str_hash_flags, + int update_flags) +{ + struct btree_iter iter, slot = { NULL }; + struct bkey_s_c k; + bool found = false; + int ret; + + for_each_btree_key_upto_norestart(trans, iter, desc.btree_id, + SPOS(insert->k.p.inode, + desc.hash_bkey(info, bkey_i_to_s_c(insert)), + snapshot), + POS(insert->k.p.inode, U64_MAX), + BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) { + if (is_visible_key(desc, inum, k)) { + if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert))) + goto found; + + /* hash collision: */ + continue; + } + + if (!slot.path && + !(str_hash_flags & BCH_HASH_SET_MUST_REPLACE)) + bch2_trans_copy_iter(&slot, &iter); + + if (k.k->type != KEY_TYPE_hash_whiteout) + goto not_found; + } + + if (!ret) + ret = -BCH_ERR_ENOSPC_str_hash_create; +out: + bch2_trans_iter_exit(trans, &slot); + bch2_trans_iter_exit(trans, &iter); + + return ret; +found: + found = true; +not_found: + + if (!found && (str_hash_flags & BCH_HASH_SET_MUST_REPLACE)) { + ret = -BCH_ERR_ENOENT_str_hash_set_must_replace; + } else if (found && (str_hash_flags & BCH_HASH_SET_MUST_CREATE)) { + ret = -EEXIST; + } else { + if (!found && slot.path) + swap(iter, slot); + + insert->k.p = iter.pos; + ret = bch2_trans_update(trans, &iter, insert, update_flags); + } + + goto out; +} + +static __always_inline +int bch2_hash_set(struct btree_trans *trans, + const struct bch_hash_desc desc, + const struct bch_hash_info *info, + subvol_inum inum, + struct bkey_i *insert, + bch_str_hash_flags_t str_hash_flags) +{ + u32 snapshot; + int ret; + + ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot); + if (ret) + return ret; + + insert->k.p.inode = inum.inum; + + return bch2_hash_set_snapshot(trans, desc, info, inum, + snapshot, insert, str_hash_flags, 0); +} + +static __always_inline +int bch2_hash_delete_at(struct btree_trans *trans, + const struct bch_hash_desc desc, + const struct bch_hash_info *info, + struct btree_iter *iter, + unsigned update_flags) +{ + struct bkey_i *delete; + int ret; + + delete = bch2_trans_kmalloc(trans, sizeof(*delete)); + ret = PTR_ERR_OR_ZERO(delete); + if (ret) + return ret; + + ret = bch2_hash_needs_whiteout(trans, desc, info, iter); + if (ret < 0) + return ret; + + bkey_init(&delete->k); + delete->k.p = iter->pos; + delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted; + + return bch2_trans_update(trans, iter, delete, update_flags); +} + +static __always_inline +int bch2_hash_delete(struct btree_trans *trans, + const struct bch_hash_desc desc, + const struct bch_hash_info *info, + subvol_inum inum, const void *key) +{ + struct btree_iter iter; + int ret; + + ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key, + BTREE_ITER_INTENT); + if (ret) + return ret; + + ret = bch2_hash_delete_at(trans, desc, info, &iter, 0); + bch2_trans_iter_exit(trans, &iter); + return ret; +} + +#endif /* _BCACHEFS_STR_HASH_H */ |