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linux/fs/bcachefs/str_hash.h
Kent Overstreet 3eb26d0157 bcachefs: bch2_trans_get_iter() no longer returns errors 
Since we now always preallocate the maximum number of iterators when we
initialize a btree transaction, getting an iterator never fails - we can
delete a fair amount of error path code.

This patch also simplifies the iterator allocation code a bit.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-10-22 17:08:48 -04:00

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/* 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 "super.h"
#include <linux/crc32c.h>
#include <crypto/hash.h>
#include <crypto/sha2.h>
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;
union {
__le64 crc_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),
.crc_key = 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->crc_key, sizeof(info->crc_key));
break;
case BCH_STR_HASH_CRC64:
ctx->crc64 = crc64_be(~0, &info->crc_key, sizeof(info->crc_key));
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);
};
static __always_inline struct btree_iter *
bch2_hash_lookup(struct btree_trans *trans,
const struct bch_hash_desc desc,
const struct bch_hash_info *info,
u64 inode, const void *key,
unsigned flags)
{
struct btree_iter *iter;
struct bkey_s_c k;
int ret;
for_each_btree_key(trans, iter, desc.btree_id,
POS(inode, desc.hash_key(info, key)),
BTREE_ITER_SLOTS|flags, k, ret) {
if (iter->pos.inode != inode)
break;
if (k.k->type == desc.key_type) {
if (!desc.cmp_key(k, key))
return iter;
} else if (k.k->type == KEY_TYPE_whiteout) {
;
} else {
/* hole, not found */
break;
}
}
bch2_trans_iter_put(trans, iter);
return ERR_PTR(ret ?: -ENOENT);
}
static __always_inline struct btree_iter *
bch2_hash_hole(struct btree_trans *trans,
const struct bch_hash_desc desc,
const struct bch_hash_info *info,
u64 inode, const void *key)
{
struct btree_iter *iter;
struct bkey_s_c k;
int ret;
for_each_btree_key(trans, iter, desc.btree_id,
POS(inode, desc.hash_key(info, key)),
BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
if (iter->pos.inode != inode)
break;
if (k.k->type != desc.key_type)
return iter;
}
iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
bch2_trans_iter_put(trans, iter);
return ERR_PTR(ret ?: -ENOSPC);
}
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;
iter = bch2_trans_copy_iter(trans, start);
bch2_btree_iter_next_slot(iter);
for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, k, ret) {
if (k.k->type != desc.key_type &&
k.k->type != KEY_TYPE_whiteout)
break;
if (k.k->type == desc.key_type &&
desc.hash_bkey(info, k) <= start->pos.offset) {
iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
ret = 1;
break;
}
}
bch2_trans_iter_put(trans, iter);
return ret;
}
static __always_inline
int bch2_hash_set(struct btree_trans *trans,
const struct bch_hash_desc desc,
const struct bch_hash_info *info,
u64 inode, struct bkey_i *insert, int flags)
{
struct btree_iter *iter, *slot = NULL;
struct bkey_s_c k;
bool found = false;
int ret;
for_each_btree_key(trans, iter, desc.btree_id,
POS(inode, desc.hash_bkey(info, bkey_i_to_s_c(insert))),
BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
if (iter->pos.inode != inode)
break;
if (k.k->type == desc.key_type) {
if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
goto found;
/* hash collision: */
continue;
}
if (!slot &&
!(flags & BCH_HASH_SET_MUST_REPLACE))
slot = bch2_trans_copy_iter(trans, iter);
if (k.k->type != KEY_TYPE_whiteout)
goto not_found;
}
if (!ret)
ret = -ENOSPC;
out:
bch2_trans_iter_put(trans, slot);
bch2_trans_iter_put(trans, iter);
return ret;
found:
found = true;
not_found:
if (!found && (flags & BCH_HASH_SET_MUST_REPLACE)) {
ret = -ENOENT;
} else if (found && (flags & BCH_HASH_SET_MUST_CREATE)) {
ret = -EEXIST;
} else {
if (!found && slot)
swap(iter, slot);
insert->k.p = iter->pos;
bch2_trans_update(trans, iter, insert, 0);
}
goto out;
}
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)
{
struct bkey_i *delete;
int ret;
ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
if (ret < 0)
return ret;
delete = bch2_trans_kmalloc(trans, sizeof(*delete));
if (IS_ERR(delete))
return PTR_ERR(delete);
bkey_init(&delete->k);
delete->k.p = iter->pos;
delete->k.type = ret ? KEY_TYPE_whiteout : KEY_TYPE_deleted;
bch2_trans_update(trans, iter, delete, 0);
return 0;
}
static __always_inline
int bch2_hash_delete(struct btree_trans *trans,
const struct bch_hash_desc desc,
const struct bch_hash_info *info,
u64 inode, const void *key)
{
struct btree_iter *iter;
int ret;
iter = bch2_hash_lookup(trans, desc, info, inode, key,
BTREE_ITER_INTENT);
if (IS_ERR(iter))
return PTR_ERR(iter);
ret = bch2_hash_delete_at(trans, desc, info, iter);
bch2_trans_iter_put(trans, iter);
return ret;
}
#endif /* _BCACHEFS_STR_HASH_H */
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