static void h_remove(struct hash_table *ht, struct entry *e)
{
unsigned h = hash_64(from_oblock(e->oblock), ht->hash_bits);
struct entry *prev;
/*
* The down side of using a singly linked list is we have to
* iterate the bucket to remove an item.
*/
e = __h_lookup(ht, h, e->oblock, &prev);
if (e)
__h_unlink(ht, h, e, prev);
}
static struct entry *hash_lookup(struct mq_policy *mq, dm_oblock_t oblock)
{
unsigned h = hash_64(from_oblock(oblock), mq->hash_bits);
struct hlist_head *bucket = mq->table + h;
struct entry *e;
hlist_for_each_entry(e, bucket, hlist)
if (e->oblock == oblock) {
hlist_del(&e->hlist);
hlist_add_head(&e->hlist, bucket);
return e;
}
return NULL;
}
/*
* Also moves each entry to the front of the bucket.
*/
static struct entry *h_lookup(struct hash_table *ht, dm_oblock_t oblock)
{
struct entry *e, *prev;
unsigned h = hash_64(from_oblock(oblock), ht->hash_bits);
e = __h_lookup(ht, h, oblock, &prev);
if (e && prev) {
/*
* Move to the front because this entry is likely
* to be hit again.
*/
__h_unlink(ht, h, e, prev);
__h_insert(ht, h, e);
}
return e;
}
static void iot_update_stats(struct io_tracker *t, struct bio *bio)
{
if (bio->bi_iter.bi_sector == from_oblock(t->last_end_oblock) + 1)
t->nr_seq_samples++;
else {
/*
* Just one non-sequential IO is enough to reset the
* counters.
*/
if (t->nr_seq_samples) {
t->nr_seq_samples = 0;
t->nr_rand_samples = 0;
}
t->nr_rand_samples++;
}
t->last_end_oblock = to_oblock(bio_end_sector(bio) - 1);
}
/*
* Simple hash table implementation. Should replace with the standard hash
* table that's making its way upstream.
*/
static void hash_insert(struct mq_policy *mq, struct entry *e)
{
unsigned h = hash_64(from_oblock(e->oblock), mq->hash_bits);
hlist_add_head(&e->hlist, mq->table + h);
}
static void h_insert(struct hash_table *ht, struct entry *e)
{
unsigned h = hash_64(from_oblock(e->oblock), ht->hash_bits);
__h_insert(ht, h, e);
}
static dm_oblock_t to_hblock(struct smq_policy *mq, dm_oblock_t b)
{
sector_t r = from_oblock(b);
(void) sector_div(r, mq->cache_blocks_per_hotspot_block);
return to_oblock(r);
}
