bcache: A block layer cache
Does writethrough and writeback caching, handles unclean shutdown, and has a bunch of other nifty features motivated by real world usage. See the wiki at http://bcache.evilpiepirate.org for more. Signed-off-by: Kent Overstreet <koverstreet@google.com>
This commit is contained in:
Kent Overstreet
254
drivers/md/bcache/movinggc.c
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254
drivers/md/bcache/movinggc.c
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/*
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* Moving/copying garbage collector
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*
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* Copyright 2012 Google, Inc.
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*/
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#include "bcache.h"
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#include "btree.h"
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#include "debug.h"
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#include "request.h"
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struct moving_io {
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struct keybuf_key *w;
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struct search s;
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struct bbio bio;
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};
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static bool moving_pred(struct keybuf *buf, struct bkey *k)
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{
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struct cache_set *c = container_of(buf, struct cache_set,
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moving_gc_keys);
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unsigned i;
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for (i = 0; i < KEY_PTRS(k); i++) {
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struct cache *ca = PTR_CACHE(c, k, i);
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struct bucket *g = PTR_BUCKET(c, k, i);
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if (GC_SECTORS_USED(g) < ca->gc_move_threshold)
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return true;
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}
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return false;
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}
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/* Moving GC - IO loop */
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static void moving_io_destructor(struct closure *cl)
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{
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struct moving_io *io = container_of(cl, struct moving_io, s.cl);
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kfree(io);
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}
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static void write_moving_finish(struct closure *cl)
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{
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struct moving_io *io = container_of(cl, struct moving_io, s.cl);
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struct bio *bio = &io->bio.bio;
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struct bio_vec *bv = bio_iovec_idx(bio, bio->bi_vcnt);
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while (bv-- != bio->bi_io_vec)
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__free_page(bv->bv_page);
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pr_debug("%s %s", io->s.op.insert_collision
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? "collision moving" : "moved",
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pkey(&io->w->key));
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bch_keybuf_del(&io->s.op.c->moving_gc_keys, io->w);
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atomic_dec_bug(&io->s.op.c->in_flight);
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closure_wake_up(&io->s.op.c->moving_gc_wait);
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closure_return_with_destructor(cl, moving_io_destructor);
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}
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static void read_moving_endio(struct bio *bio, int error)
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{
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struct moving_io *io = container_of(bio->bi_private,
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struct moving_io, s.cl);
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if (error)
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io->s.error = error;
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bch_bbio_endio(io->s.op.c, bio, error, "reading data to move");
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}
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static void moving_init(struct moving_io *io)
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{
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struct bio *bio = &io->bio.bio;
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bio_init(bio);
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bio_get(bio);
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bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
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bio->bi_size = KEY_SIZE(&io->w->key) << 9;
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bio->bi_max_vecs = DIV_ROUND_UP(KEY_SIZE(&io->w->key),
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PAGE_SECTORS);
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bio->bi_private = &io->s.cl;
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bio->bi_io_vec = bio->bi_inline_vecs;
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bio_map(bio, NULL);
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}
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static void write_moving(struct closure *cl)
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{
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struct search *s = container_of(cl, struct search, cl);
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struct moving_io *io = container_of(s, struct moving_io, s);
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if (!s->error) {
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trace_bcache_write_moving(&io->bio.bio);
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moving_init(io);
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io->bio.bio.bi_sector = KEY_START(&io->w->key);
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s->op.lock = -1;
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s->op.write_prio = 1;
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s->op.cache_bio = &io->bio.bio;
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s->writeback = KEY_DIRTY(&io->w->key);
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s->op.csum = KEY_CSUM(&io->w->key);
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s->op.type = BTREE_REPLACE;
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bkey_copy(&s->op.replace, &io->w->key);
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closure_init(&s->op.cl, cl);
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bch_insert_data(&s->op.cl);
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}
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continue_at(cl, write_moving_finish, NULL);
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}
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static void read_moving_submit(struct closure *cl)
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{
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struct search *s = container_of(cl, struct search, cl);
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struct moving_io *io = container_of(s, struct moving_io, s);
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struct bio *bio = &io->bio.bio;
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trace_bcache_read_moving(bio);
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bch_submit_bbio(bio, s->op.c, &io->w->key, 0);
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continue_at(cl, write_moving, bch_gc_wq);
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}
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static void read_moving(struct closure *cl)
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{
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struct cache_set *c = container_of(cl, struct cache_set, moving_gc);
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struct keybuf_key *w;
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struct moving_io *io;
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struct bio *bio;
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/* XXX: if we error, background writeback could stall indefinitely */
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while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
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w = bch_keybuf_next_rescan(c, &c->moving_gc_keys, &MAX_KEY);
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if (!w)
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break;
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io = kzalloc(sizeof(struct moving_io) + sizeof(struct bio_vec)
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* DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
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GFP_KERNEL);
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if (!io)
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goto err;
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w->private = io;
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io->w = w;
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io->s.op.inode = KEY_INODE(&w->key);
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io->s.op.c = c;
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moving_init(io);
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bio = &io->bio.bio;
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bio->bi_rw = READ;
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bio->bi_end_io = read_moving_endio;
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if (bio_alloc_pages(bio, GFP_KERNEL))
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goto err;
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pr_debug("%s", pkey(&w->key));
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closure_call(&io->s.cl, read_moving_submit, NULL, &c->gc.cl);
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if (atomic_inc_return(&c->in_flight) >= 64) {
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closure_wait_event(&c->moving_gc_wait, cl,
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atomic_read(&c->in_flight) < 64);
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continue_at(cl, read_moving, bch_gc_wq);
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}
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}
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if (0) {
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err: if (!IS_ERR_OR_NULL(w->private))
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kfree(w->private);
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bch_keybuf_del(&c->moving_gc_keys, w);
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}
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closure_return(cl);
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}
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void bch_moving_gc(struct closure *cl)
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{
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struct cache_set *c = container_of(cl, struct cache_set, gc.cl);
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struct cache *ca;
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struct bucket *b;
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unsigned i;
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bool bucket_cmp(struct bucket *l, struct bucket *r)
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{
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return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
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}
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unsigned top(struct cache *ca)
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{
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return GC_SECTORS_USED(heap_peek(&ca->heap));
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}
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if (!c->copy_gc_enabled)
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closure_return(cl);
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mutex_lock(&c->bucket_lock);
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for_each_cache(ca, c, i) {
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unsigned sectors_to_move = 0;
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unsigned reserve_sectors = ca->sb.bucket_size *
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min(fifo_used(&ca->free), ca->free.size / 2);
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ca->heap.used = 0;
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for_each_bucket(b, ca) {
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if (!GC_SECTORS_USED(b))
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continue;
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if (!heap_full(&ca->heap)) {
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sectors_to_move += GC_SECTORS_USED(b);
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heap_add(&ca->heap, b, bucket_cmp);
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} else if (bucket_cmp(b, heap_peek(&ca->heap))) {
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sectors_to_move -= top(ca);
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sectors_to_move += GC_SECTORS_USED(b);
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ca->heap.data[0] = b;
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heap_sift(&ca->heap, 0, bucket_cmp);
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}
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}
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while (sectors_to_move > reserve_sectors) {
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heap_pop(&ca->heap, b, bucket_cmp);
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sectors_to_move -= GC_SECTORS_USED(b);
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}
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ca->gc_move_threshold = top(ca);
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pr_debug("threshold %u", ca->gc_move_threshold);
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}
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mutex_unlock(&c->bucket_lock);
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c->moving_gc_keys.last_scanned = ZERO_KEY;
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closure_init(&c->moving_gc, cl);
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read_moving(&c->moving_gc);
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closure_return(cl);
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}
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void bch_moving_init_cache_set(struct cache_set *c)
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{
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bch_keybuf_init(&c->moving_gc_keys, moving_pred);
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}
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