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#include "bcache.h"
#include "alloc.h"
#include "btree_iter.h"
#include "buckets.h"
#include "clock.h"
#include "extents.h"
#include "io.h"
#include "keylist.h"
#include "move.h"
#include "tier.h"
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <trace/events/bcache.h>
struct tiering_state {
struct cache_group *tier;
unsigned tier_idx;
unsigned sectors;
unsigned stripe_size;
unsigned dev_idx;
struct cache *ca;
};
static bool tiering_pred(struct cache_set *c,
struct tiering_state *s,
struct bkey_s_c k)
{
if (bkey_extent_is_data(k.k)) {
struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
const struct bch_extent_ptr *ptr;
struct cache_member_rcu *mi;
unsigned replicas = 0;
/* Make sure we have room to add a new pointer: */
if (bkey_val_u64s(e.k) + BKEY_EXTENT_PTR_U64s_MAX >
BKEY_EXTENT_VAL_U64s_MAX)
return false;
mi = cache_member_info_get(c);
extent_for_each_ptr(e, ptr)
if (ptr->dev < mi->nr_in_set &&
mi->m[ptr->dev].tier >= s->tier_idx)
replicas++;
cache_member_info_put();
return replicas < c->opts.data_replicas;
}
return false;
}
static void tier_put_device(struct tiering_state *s)
{
if (s->ca)
percpu_ref_put(&s->ca->ref);
s->ca = NULL;
}
/**
* refill_next - move on to refilling the next cache's tiering keylist
*/
static void tier_next_device(struct cache_set *c, struct tiering_state *s)
{
if (!s->ca || s->sectors > s->stripe_size) {
tier_put_device(s);
s->sectors = 0;
s->dev_idx++;
spin_lock(&s->tier->lock);
if (s->dev_idx >= s->tier->nr_devices)
s->dev_idx = 0;
if (s->tier->nr_devices) {
s->ca = s->tier->d[s->dev_idx].dev;
percpu_ref_get(&s->ca->ref);
}
spin_unlock(&s->tier->lock);
}
}
static int issue_tiering_move(struct cache_set *c,
struct tiering_state *s,
struct moving_context *ctxt,
struct bkey_s_c k)
{
int ret;
ret = bch_data_move(c, ctxt, &s->ca->tiering_write_point, k, NULL);
if (!ret) {
trace_bcache_tiering_copy(k.k);
s->sectors += k.k->size;
} else {
trace_bcache_tiering_alloc_fail(c, k.k->size);
}
return ret;
}
/**
* tiering_next_cache - issue a move to write an extent to the next cache
* device in round robin order
*/
static s64 read_tiering(struct cache_set *c, struct cache_group *tier)
{
struct moving_context ctxt;
struct tiering_state s;
struct btree_iter iter;
struct bkey_s_c k;
unsigned nr_devices = READ_ONCE(tier->nr_devices);
int ret;
if (!nr_devices)
return 0;
trace_bcache_tiering_start(c);
memset(&s, 0, sizeof(s));
s.tier = tier;
s.tier_idx = tier - c->cache_tiers;
s.stripe_size = 2048; /* 1 mb for now */
bch_move_ctxt_init(&ctxt, &c->tiering_pd.rate,
nr_devices * SECTORS_IN_FLIGHT_PER_DEVICE);
bch_btree_iter_init(&iter, c, BTREE_ID_EXTENTS, POS_MIN);
while (!kthread_should_stop() &&
!bch_move_ctxt_wait(&ctxt) &&
(k = bch_btree_iter_peek(&iter)).k &&
!btree_iter_err(k)) {
if (!tiering_pred(c, &s, k))
goto next;
tier_next_device(c, &s);
if (!s.ca)
break;
ret = issue_tiering_move(c, &s, &ctxt, k);
if (ret) {
bch_btree_iter_unlock(&iter);
/* memory allocation failure, wait for some IO to finish */
bch_move_ctxt_wait_for_io(&ctxt);
continue;
}
next:
bch_btree_iter_advance_pos(&iter);
//bch_btree_iter_cond_resched(&iter);
/* unlock before calling moving_context_wait() */
bch_btree_iter_unlock(&iter);
cond_resched();
}
bch_btree_iter_unlock(&iter);
tier_put_device(&s);
bch_move_ctxt_exit(&ctxt);
trace_bcache_tiering_end(c, ctxt.sectors_moved, ctxt.keys_moved);
return ctxt.sectors_moved;
}
static int bch_tiering_thread(void *arg)
{
struct cache_set *c = arg;
struct cache_group *tier = &c->cache_tiers[1];
struct io_clock *clock = &c->io_clock[WRITE];
struct cache *ca;
u64 tier_capacity, available_sectors;
unsigned long last;
unsigned i;
set_freezable();
while (!kthread_should_stop()) {
if (kthread_wait_freezable(c->tiering_enabled &&
tier->nr_devices))
break;
while (1) {
struct cache_group *faster_tier;
last = atomic_long_read(&clock->now);
tier_capacity = available_sectors = 0;
rcu_read_lock();
for (faster_tier = c->cache_tiers;
faster_tier != tier;
faster_tier++) {
group_for_each_cache_rcu(ca, faster_tier, i) {
tier_capacity +=
(ca->mi.nbuckets -
ca->mi.first_bucket) << ca->bucket_bits;
available_sectors +=
buckets_available_cache(ca) << ca->bucket_bits;
}
}
rcu_read_unlock();
if (available_sectors < (tier_capacity >> 1))
break;
bch_kthread_io_clock_wait(clock,
last +
available_sectors -
(tier_capacity >> 1));
if (kthread_should_stop())
return 0;
}
read_tiering(c, tier);
}
return 0;
}
void bch_tiering_init_cache_set(struct cache_set *c)
{
bch_pd_controller_init(&c->tiering_pd);
}
int bch_tiering_read_start(struct cache_set *c)
{
struct task_struct *t;
if (c->opts.nochanges)
return 0;
t = kthread_create(bch_tiering_thread, c, "bch_tier_read");
if (IS_ERR(t))
return PTR_ERR(t);
c->tiering_read = t;
wake_up_process(c->tiering_read);
return 0;
}
void bch_tiering_read_stop(struct cache_set *c)
{
if (!IS_ERR_OR_NULL(c->tiering_read)) {
kthread_stop(c->tiering_read);
c->tiering_read = NULL;
}
}
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