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/*
* Moving/copying garbage collector
*
* Copyright 2012 Google, Inc.
*/
#include "bcache.h"
#include "btree.h"
#include "debug.h"
#include "request.h"
#include <trace/events/bcache.h>
struct moving_io {
struct closure cl;
struct keybuf_key *w;
struct data_insert_op op;
struct bbio bio;
};
static bool moving_pred(struct keybuf *buf, struct bkey *k)
{
struct cache_set *c = container_of(buf, struct cache_set,
moving_gc_keys);
unsigned i;
for (i = 0; i < KEY_PTRS(k); i++) {
struct cache *ca = PTR_CACHE(c, k, i);
struct bucket *g = PTR_BUCKET(c, k, i);
if (GC_SECTORS_USED(g) < ca->gc_move_threshold)
return true;
}
return false;
}
/* Moving GC - IO loop */
static void moving_io_destructor(struct closure *cl)
{
struct moving_io *io = container_of(cl, struct moving_io, cl);
kfree(io);
}
static void write_moving_finish(struct closure *cl)
{
struct moving_io *io = container_of(cl, struct moving_io, cl);
struct bio *bio = &io->bio.bio;
struct bio_vec *bv;
int i;
bio_for_each_segment_all(bv, bio, i)
__free_page(bv->bv_page);
if (io->op.replace_collision)
trace_bcache_gc_copy_collision(&io->w->key);
bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
up(&io->op.c->moving_in_flight);
closure_return_with_destructor(cl, moving_io_destructor);
}
static void read_moving_endio(struct bio *bio, int error)
{
struct moving_io *io = container_of(bio->bi_private,
struct moving_io, cl);
if (error)
io->op.error = error;
bch_bbio_endio(io->op.c, bio, error, "reading data to move");
}
static void moving_init(struct moving_io *io)
{
struct bio *bio = &io->bio.bio;
bio_init(bio);
bio_get(bio);
bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
bio->bi_iter.bi_size = KEY_SIZE(&io->w->key) << 9;
bio->bi_max_vecs = DIV_ROUND_UP(KEY_SIZE(&io->w->key),
PAGE_SECTORS);
bio->bi_private = &io->cl;
bio->bi_io_vec = bio->bi_inline_vecs;
bch_bio_map(bio, NULL);
}
static void write_moving(struct closure *cl)
{
struct moving_io *io = container_of(cl, struct moving_io, cl);
struct data_insert_op *op = &io->op;
if (!op->error) {
moving_init(io);
io->bio.bio.bi_iter.bi_sector = KEY_START(&io->w->key);
op->write_prio = 1;
op->bio = &io->bio.bio;
op->writeback = KEY_DIRTY(&io->w->key);
op->csum = KEY_CSUM(&io->w->key);
bkey_copy(&op->replace_key, &io->w->key);
op->replace = true;
closure_call(&op->cl, bch_data_insert, NULL, cl);
}
continue_at(cl, write_moving_finish, system_wq);
}
static void read_moving_submit(struct closure *cl)
{
struct moving_io *io = container_of(cl, struct moving_io, cl);
struct bio *bio = &io->bio.bio;
bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
continue_at(cl, write_moving, system_wq);
}
static void read_moving(struct cache_set *c)
{
struct keybuf_key *w;
struct moving_io *io;
struct bio *bio;
struct closure cl;
closure_init_stack(&cl);
/* XXX: if we error, background writeback could stall indefinitely */
while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
&MAX_KEY, moving_pred);
if (!w)
break;
io = kzalloc(sizeof(struct moving_io) + sizeof(struct bio_vec)
* DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
GFP_KERNEL);
if (!io)
goto err;
w->private = io;
io->w = w;
io->op.inode = KEY_INODE(&w->key);
io->op.c = c;
moving_init(io);
bio = &io->bio.bio;
bio->bi_rw = READ;
bio->bi_end_io = read_moving_endio;
if (bio_alloc_pages(bio, GFP_KERNEL))
goto err;
trace_bcache_gc_copy(&w->key);
down(&c->moving_in_flight);
closure_call(&io->cl, read_moving_submit, NULL, &cl);
}
if (0) {
err: if (!IS_ERR_OR_NULL(w->private))
kfree(w->private);
bch_keybuf_del(&c->moving_gc_keys, w);
}
closure_sync(&cl);
}
static bool bucket_cmp(struct bucket *l, struct bucket *r)
{
return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
}
static unsigned bucket_heap_top(struct cache *ca)
{
return GC_SECTORS_USED(heap_peek(&ca->heap));
}
void bch_moving_gc(struct cache_set *c)
{
struct cache *ca;
struct bucket *b;
unsigned i;
if (!c->copy_gc_enabled)
return;
mutex_lock(&c->bucket_lock);
for_each_cache(ca, c, i) {
unsigned sectors_to_move = 0;
unsigned reserve_sectors = ca->sb.bucket_size *
min(fifo_used(&ca->free), ca->free.size / 2);
ca->heap.used = 0;
for_each_bucket(b, ca) {
if (!GC_SECTORS_USED(b))
continue;
if (!heap_full(&ca->heap)) {
sectors_to_move += GC_SECTORS_USED(b);
heap_add(&ca->heap, b, bucket_cmp);
} else if (bucket_cmp(b, heap_peek(&ca->heap))) {
sectors_to_move -= bucket_heap_top(ca);
sectors_to_move += GC_SECTORS_USED(b);
ca->heap.data[0] = b;
heap_sift(&ca->heap, 0, bucket_cmp);
}
}
while (sectors_to_move > reserve_sectors) {
heap_pop(&ca->heap, b, bucket_cmp);
sectors_to_move -= GC_SECTORS_USED(b);
}
ca->gc_move_threshold = bucket_heap_top(ca);
pr_debug("threshold %u", ca->gc_move_threshold);
}
mutex_unlock(&c->bucket_lock);
c->moving_gc_keys.last_scanned = ZERO_KEY;
read_moving(c);
}
void bch_moving_init_cache_set(struct cache_set *c)
{
bch_keybuf_init(&c->moving_gc_keys);
sema_init(&c->moving_in_flight, 64);
}
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