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>
diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
new file mode 100644
index 0000000..c69fc92
--- /dev/null
+++ b/drivers/md/bcache/movinggc.c
@@ -0,0 +1,254 @@
+/*
+ * Moving/copying garbage collector
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+struct moving_io {
+ struct keybuf_key *w;
+ struct search s;
+ 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, s.cl);
+ kfree(io);
+}
+
+static void write_moving_finish(struct closure *cl)
+{
+ struct moving_io *io = container_of(cl, struct moving_io, s.cl);
+ struct bio *bio = &io->bio.bio;
+ struct bio_vec *bv = bio_iovec_idx(bio, bio->bi_vcnt);
+
+ while (bv-- != bio->bi_io_vec)
+ __free_page(bv->bv_page);
+
+ pr_debug("%s %s", io->s.op.insert_collision
+ ? "collision moving" : "moved",
+ pkey(&io->w->key));
+
+ bch_keybuf_del(&io->s.op.c->moving_gc_keys, io->w);
+
+ atomic_dec_bug(&io->s.op.c->in_flight);
+ closure_wake_up(&io->s.op.c->moving_gc_wait);
+
+ 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, s.cl);
+
+ if (error)
+ io->s.error = error;
+
+ bch_bbio_endio(io->s.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_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->s.cl;
+ bio->bi_io_vec = bio->bi_inline_vecs;
+ bio_map(bio, NULL);
+}
+
+static void write_moving(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct moving_io *io = container_of(s, struct moving_io, s);
+
+ if (!s->error) {
+ trace_bcache_write_moving(&io->bio.bio);
+
+ moving_init(io);
+
+ io->bio.bio.bi_sector = KEY_START(&io->w->key);
+ s->op.lock = -1;
+ s->op.write_prio = 1;
+ s->op.cache_bio = &io->bio.bio;
+
+ s->writeback = KEY_DIRTY(&io->w->key);
+ s->op.csum = KEY_CSUM(&io->w->key);
+
+ s->op.type = BTREE_REPLACE;
+ bkey_copy(&s->op.replace, &io->w->key);
+
+ closure_init(&s->op.cl, cl);
+ bch_insert_data(&s->op.cl);
+ }
+
+ continue_at(cl, write_moving_finish, NULL);
+}
+
+static void read_moving_submit(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct moving_io *io = container_of(s, struct moving_io, s);
+ struct bio *bio = &io->bio.bio;
+
+ trace_bcache_read_moving(bio);
+ bch_submit_bbio(bio, s->op.c, &io->w->key, 0);
+
+ continue_at(cl, write_moving, bch_gc_wq);
+}
+
+static void read_moving(struct closure *cl)
+{
+ struct cache_set *c = container_of(cl, struct cache_set, moving_gc);
+ struct keybuf_key *w;
+ struct moving_io *io;
+ struct bio *bio;
+
+ /* 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);
+ 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->s.op.inode = KEY_INODE(&w->key);
+ io->s.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;
+
+ pr_debug("%s", pkey(&w->key));
+
+ closure_call(&io->s.cl, read_moving_submit, NULL, &c->gc.cl);
+
+ if (atomic_inc_return(&c->in_flight) >= 64) {
+ closure_wait_event(&c->moving_gc_wait, cl,
+ atomic_read(&c->in_flight) < 64);
+ continue_at(cl, read_moving, bch_gc_wq);
+ }
+ }
+
+ if (0) {
+err: if (!IS_ERR_OR_NULL(w->private))
+ kfree(w->private);
+
+ bch_keybuf_del(&c->moving_gc_keys, w);
+ }
+
+ closure_return(cl);
+}
+
+void bch_moving_gc(struct closure *cl)
+{
+ struct cache_set *c = container_of(cl, struct cache_set, gc.cl);
+ struct cache *ca;
+ struct bucket *b;
+ unsigned i;
+
+ bool bucket_cmp(struct bucket *l, struct bucket *r)
+ {
+ return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
+ }
+
+ unsigned top(struct cache *ca)
+ {
+ return GC_SECTORS_USED(heap_peek(&ca->heap));
+ }
+
+ if (!c->copy_gc_enabled)
+ closure_return(cl);
+
+ 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 -= 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 = top(ca);
+
+ pr_debug("threshold %u", ca->gc_move_threshold);
+ }
+
+ mutex_unlock(&c->bucket_lock);
+
+ c->moving_gc_keys.last_scanned = ZERO_KEY;
+
+ closure_init(&c->moving_gc, cl);
+ read_moving(&c->moving_gc);
+
+ closure_return(cl);
+}
+
+void bch_moving_init_cache_set(struct cache_set *c)
+{
+ bch_keybuf_init(&c->moving_gc_keys, moving_pred);
+}