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// SPDX-License-Identifier: GPL-2.0
#include "bcachefs.h"
#include "buckets_waiting_for_journal.h"
#include <linux/hash.h>
#include <linux/random.h>
static inline struct bucket_hashed *
bucket_hash(struct buckets_waiting_for_journal_table *t,
unsigned hash_seed_idx, u64 dev_bucket)
{
return t->d + hash_64(dev_bucket ^ t->hash_seeds[hash_seed_idx], t->bits);
}
static void bucket_table_init(struct buckets_waiting_for_journal_table *t, size_t bits)
{
unsigned i;
t->bits = bits;
for (i = 0; i < ARRAY_SIZE(t->hash_seeds); i++)
get_random_bytes(&t->hash_seeds[i], sizeof(t->hash_seeds[i]));
memset(t->d, 0, sizeof(t->d[0]) << t->bits);
}
bool bch2_bucket_needs_journal_commit(struct buckets_waiting_for_journal *b,
u64 flushed_seq,
unsigned dev, u64 bucket)
{
struct buckets_waiting_for_journal_table *t;
u64 dev_bucket = (u64) dev << 56 | bucket;
bool ret = false;
unsigned i;
mutex_lock(&b->lock);
t = b->t;
for (i = 0; i < ARRAY_SIZE(t->hash_seeds); i++) {
struct bucket_hashed *h = bucket_hash(t, i, dev_bucket);
if (h->dev_bucket == dev_bucket) {
ret = h->journal_seq > flushed_seq;
break;
}
}
mutex_unlock(&b->lock);
return ret;
}
static bool bucket_table_insert(struct buckets_waiting_for_journal_table *t,
struct bucket_hashed *new,
u64 flushed_seq)
{
struct bucket_hashed *last_evicted = NULL;
unsigned tries, i;
for (tries = 0; tries < 10; tries++) {
struct bucket_hashed *old, *victim = NULL;
for (i = 0; i < ARRAY_SIZE(t->hash_seeds); i++) {
old = bucket_hash(t, i, new->dev_bucket);
if (old->dev_bucket == new->dev_bucket ||
old->journal_seq <= flushed_seq) {
*old = *new;
return true;
}
if (last_evicted != old)
victim = old;
}
/* hashed to same slot 3 times: */
if (!victim)
break;
/* Failed to find an empty slot: */
swap(*new, *victim);
last_evicted = victim;
}
return false;
}
int bch2_set_bucket_needs_journal_commit(struct buckets_waiting_for_journal *b,
u64 flushed_seq,
unsigned dev, u64 bucket,
u64 journal_seq)
{
struct buckets_waiting_for_journal_table *t, *n;
struct bucket_hashed tmp, new = {
.dev_bucket = (u64) dev << 56 | bucket,
.journal_seq = journal_seq,
};
size_t i, size, new_bits, nr_elements = 1, nr_rehashes = 0;
int ret = 0;
mutex_lock(&b->lock);
if (likely(bucket_table_insert(b->t, &new, flushed_seq)))
goto out;
t = b->t;
size = 1UL << t->bits;
for (i = 0; i < size; i++)
nr_elements += t->d[i].journal_seq > flushed_seq;
new_bits = t->bits + (nr_elements * 3 > size);
n = kvmalloc(sizeof(*n) + (sizeof(n->d[0]) << new_bits), GFP_KERNEL);
if (!n) {
ret = -ENOMEM;
goto out;
}
retry_rehash:
nr_rehashes++;
bucket_table_init(n, new_bits);
tmp = new;
BUG_ON(!bucket_table_insert(n, &tmp, flushed_seq));
for (i = 0; i < 1UL << t->bits; i++) {
if (t->d[i].journal_seq <= flushed_seq)
continue;
tmp = t->d[i];
if (!bucket_table_insert(n, &tmp, flushed_seq))
goto retry_rehash;
}
b->t = n;
kvfree(t);
pr_debug("took %zu rehashes, table at %zu/%zu elements",
nr_rehashes, nr_elements, 1UL << b->t->bits);
out:
mutex_unlock(&b->lock);
return ret;
}
void bch2_fs_buckets_waiting_for_journal_exit(struct bch_fs *c)
{
struct buckets_waiting_for_journal *b = &c->buckets_waiting_for_journal;
kvfree(b->t);
}
#define INITIAL_TABLE_BITS 3
int bch2_fs_buckets_waiting_for_journal_init(struct bch_fs *c)
{
struct buckets_waiting_for_journal *b = &c->buckets_waiting_for_journal;
mutex_init(&b->lock);
b->t = kvmalloc(sizeof(*b->t) +
(sizeof(b->t->d[0]) << INITIAL_TABLE_BITS), GFP_KERNEL);
if (!b->t)
return -ENOMEM;
bucket_table_init(b->t, INITIAL_TABLE_BITS);
return 0;
}
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