1 files changed, 254 insertions, 0 deletions

diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
new file mode 100644
index 000000000000..8589512c972e
--- /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;
+        bch_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 (bch_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);
+}
+
+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 closure *cl)
+{
+        struct cache_set *c = container_of(cl, struct cache_set, gc.cl);
+        struct cache *ca;
+        struct bucket *b;
+        unsigned i;
+
+        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 -= 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;
+
+        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);
+}