1 files changed, 436 insertions, 0 deletions

diff --git a/c_src/libbcachefs/movinggc.c b/c_src/libbcachefs/movinggc.c
new file mode 100644
index 00000000..69e06a84
--- /dev/null
+++ b/c_src/libbcachefs/movinggc.c
@@ -0,0 +1,436 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Moving/copying garbage collector
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcachefs.h"
+#include "alloc_background.h"
+#include "alloc_foreground.h"
+#include "btree_iter.h"
+#include "btree_update.h"
+#include "btree_write_buffer.h"
+#include "buckets.h"
+#include "clock.h"
+#include "errcode.h"
+#include "error.h"
+#include "lru.h"
+#include "move.h"
+#include "movinggc.h"
+#include "trace.h"
+
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/math64.h>
+#include <linux/sched/task.h>
+#include <linux/wait.h>
+
+struct buckets_in_flight {
+	struct rhashtable		table;
+	struct move_bucket_in_flight	*first;
+	struct move_bucket_in_flight	*last;
+	size_t				nr;
+	size_t				sectors;
+};
+
+static const struct rhashtable_params bch_move_bucket_params = {
+	.head_offset	= offsetof(struct move_bucket_in_flight, hash),
+	.key_offset	= offsetof(struct move_bucket_in_flight, bucket.k),
+	.key_len	= sizeof(struct move_bucket_key),
+};
+
+static struct move_bucket_in_flight *
+move_bucket_in_flight_add(struct buckets_in_flight *list, struct move_bucket b)
+{
+	struct move_bucket_in_flight *new = kzalloc(sizeof(*new), GFP_KERNEL);
+	int ret;
+
+	if (!new)
+		return ERR_PTR(-ENOMEM);
+
+	new->bucket = b;
+
+	ret = rhashtable_lookup_insert_fast(&list->table, &new->hash,
+					    bch_move_bucket_params);
+	if (ret) {
+		kfree(new);
+		return ERR_PTR(ret);
+	}
+
+	if (!list->first)
+		list->first = new;
+	else
+		list->last->next = new;
+
+	list->last = new;
+	list->nr++;
+	list->sectors += b.sectors;
+	return new;
+}
+
+static int bch2_bucket_is_movable(struct btree_trans *trans,
+				  struct move_bucket *b, u64 time)
+{
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	struct bch_alloc_v4 _a;
+	const struct bch_alloc_v4 *a;
+	int ret;
+
+	if (bch2_bucket_is_open(trans->c,
+				b->k.bucket.inode,
+				b->k.bucket.offset))
+		return 0;
+
+	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_alloc,
+			       b->k.bucket, BTREE_ITER_CACHED);
+	ret = bkey_err(k);
+	if (ret)
+		return ret;
+
+	a = bch2_alloc_to_v4(k, &_a);
+	b->k.gen	= a->gen;
+	b->sectors	= bch2_bucket_sectors_dirty(*a);
+
+	ret = data_type_movable(a->data_type) &&
+		a->fragmentation_lru &&
+		a->fragmentation_lru <= time;
+
+	bch2_trans_iter_exit(trans, &iter);
+	return ret;
+}
+
+static void move_buckets_wait(struct moving_context *ctxt,
+			      struct buckets_in_flight *list,
+			      bool flush)
+{
+	struct move_bucket_in_flight *i;
+	int ret;
+
+	while ((i = list->first)) {
+		if (flush)
+			move_ctxt_wait_event(ctxt, !atomic_read(&i->count));
+
+		if (atomic_read(&i->count))
+			break;
+
+		list->first = i->next;
+		if (!list->first)
+			list->last = NULL;
+
+		list->nr--;
+		list->sectors -= i->bucket.sectors;
+
+		ret = rhashtable_remove_fast(&list->table, &i->hash,
+					     bch_move_bucket_params);
+		BUG_ON(ret);
+		kfree(i);
+	}
+
+	bch2_trans_unlock_long(ctxt->trans);
+}
+
+static bool bucket_in_flight(struct buckets_in_flight *list,
+			     struct move_bucket_key k)
+{
+	return rhashtable_lookup_fast(&list->table, &k, bch_move_bucket_params);
+}
+
+typedef DARRAY(struct move_bucket) move_buckets;
+
+static int bch2_copygc_get_buckets(struct moving_context *ctxt,
+			struct buckets_in_flight *buckets_in_flight,
+			move_buckets *buckets)
+{
+	struct btree_trans *trans = ctxt->trans;
+	struct bch_fs *c = trans->c;
+	size_t nr_to_get = max_t(size_t, 16U, buckets_in_flight->nr / 4);
+	size_t saw = 0, in_flight = 0, not_movable = 0, sectors = 0;
+	int ret;
+
+	move_buckets_wait(ctxt, buckets_in_flight, false);
+
+	ret = bch2_btree_write_buffer_tryflush(trans);
+	if (bch2_err_matches(ret, EROFS))
+		return ret;
+
+	if (bch2_fs_fatal_err_on(ret, c, "%s: error %s from bch2_btree_write_buffer_tryflush()",
+				 __func__, bch2_err_str(ret)))
+		return ret;
+
+	ret = for_each_btree_key_upto(trans, iter, BTREE_ID_lru,
+				  lru_pos(BCH_LRU_FRAGMENTATION_START, 0, 0),
+				  lru_pos(BCH_LRU_FRAGMENTATION_START, U64_MAX, LRU_TIME_MAX),
+				  0, k, ({
+		struct move_bucket b = { .k.bucket = u64_to_bucket(k.k->p.offset) };
+		int ret2 = 0;
+
+		saw++;
+
+		ret2 = bch2_bucket_is_movable(trans, &b, lru_pos_time(k.k->p));
+		if (ret2 < 0)
+			goto err;
+
+		if (!ret2)
+			not_movable++;
+		else if (bucket_in_flight(buckets_in_flight, b.k))
+			in_flight++;
+		else {
+			ret2 = darray_push(buckets, b);
+			if (ret2)
+				goto err;
+			sectors += b.sectors;
+		}
+
+		ret2 = buckets->nr >= nr_to_get;
+err:
+		ret2;
+	}));
+
+	pr_debug("have: %zu (%zu) saw %zu in flight %zu not movable %zu got %zu (%zu)/%zu buckets ret %i",
+		 buckets_in_flight->nr, buckets_in_flight->sectors,
+		 saw, in_flight, not_movable, buckets->nr, sectors, nr_to_get, ret);
+
+	return ret < 0 ? ret : 0;
+}
+
+noinline
+static int bch2_copygc(struct moving_context *ctxt,
+		       struct buckets_in_flight *buckets_in_flight,
+		       bool *did_work)
+{
+	struct btree_trans *trans = ctxt->trans;
+	struct bch_fs *c = trans->c;
+	struct data_update_opts data_opts = {
+		.btree_insert_flags = BCH_WATERMARK_copygc,
+	};
+	move_buckets buckets = { 0 };
+	struct move_bucket_in_flight *f;
+	u64 moved = atomic64_read(&ctxt->stats->sectors_moved);
+	int ret = 0;
+
+	ret = bch2_copygc_get_buckets(ctxt, buckets_in_flight, &buckets);
+	if (ret)
+		goto err;
+
+	darray_for_each(buckets, i) {
+		if (kthread_should_stop() || freezing(current))
+			break;
+
+		f = move_bucket_in_flight_add(buckets_in_flight, *i);
+		ret = PTR_ERR_OR_ZERO(f);
+		if (ret == -EEXIST) { /* rare race: copygc_get_buckets returned same bucket more than once */
+			ret = 0;
+			continue;
+		}
+		if (ret == -ENOMEM) { /* flush IO, continue later */
+			ret = 0;
+			break;
+		}
+
+		ret = bch2_evacuate_bucket(ctxt, f, f->bucket.k.bucket,
+					     f->bucket.k.gen, data_opts);
+		if (ret)
+			goto err;
+
+		*did_work = true;
+	}
+err:
+	darray_exit(&buckets);
+
+	/* no entries in LRU btree found, or got to end: */
+	if (bch2_err_matches(ret, ENOENT))
+		ret = 0;
+
+	if (ret < 0 && !bch2_err_matches(ret, EROFS))
+		bch_err_msg(c, ret, "from bch2_move_data()");
+
+	moved = atomic64_read(&ctxt->stats->sectors_moved) - moved;
+	trace_and_count(c, copygc, c, moved, 0, 0, 0);
+	return ret;
+}
+
+/*
+ * Copygc runs when the amount of fragmented data is above some arbitrary
+ * threshold:
+ *
+ * The threshold at the limit - when the device is full - is the amount of space
+ * we reserved in bch2_recalc_capacity; we can't have more than that amount of
+ * disk space stranded due to fragmentation and store everything we have
+ * promised to store.
+ *
+ * But we don't want to be running copygc unnecessarily when the device still
+ * has plenty of free space - rather, we want copygc to smoothly run every so
+ * often and continually reduce the amount of fragmented space as the device
+ * fills up. So, we increase the threshold by half the current free space.
+ */
+unsigned long bch2_copygc_wait_amount(struct bch_fs *c)
+{
+	s64 wait = S64_MAX, fragmented_allowed, fragmented;
+
+	for_each_rw_member(c, ca) {
+		struct bch_dev_usage usage = bch2_dev_usage_read(ca);
+
+		fragmented_allowed = ((__dev_buckets_available(ca, usage, BCH_WATERMARK_stripe) *
+				       ca->mi.bucket_size) >> 1);
+		fragmented = 0;
+
+		for (unsigned i = 0; i < BCH_DATA_NR; i++)
+			if (data_type_movable(i))
+				fragmented += usage.d[i].fragmented;
+
+		wait = min(wait, max(0LL, fragmented_allowed - fragmented));
+	}
+
+	return wait;
+}
+
+void bch2_copygc_wait_to_text(struct printbuf *out, struct bch_fs *c)
+{
+	prt_printf(out, "Currently waiting for:     ");
+	prt_human_readable_u64(out, max(0LL, c->copygc_wait -
+					atomic64_read(&c->io_clock[WRITE].now)) << 9);
+	prt_newline(out);
+
+	prt_printf(out, "Currently waiting since:   ");
+	prt_human_readable_u64(out, max(0LL,
+					atomic64_read(&c->io_clock[WRITE].now) -
+					c->copygc_wait_at) << 9);
+	prt_newline(out);
+
+	prt_printf(out, "Currently calculated wait: ");
+	prt_human_readable_u64(out, bch2_copygc_wait_amount(c));
+	prt_newline(out);
+}
+
+static int bch2_copygc_thread(void *arg)
+{
+	struct bch_fs *c = arg;
+	struct moving_context ctxt;
+	struct bch_move_stats move_stats;
+	struct io_clock *clock = &c->io_clock[WRITE];
+	struct buckets_in_flight *buckets;
+	u64 last, wait;
+	int ret = 0;
+
+	buckets = kzalloc(sizeof(struct buckets_in_flight), GFP_KERNEL);
+	if (!buckets)
+		return -ENOMEM;
+	ret = rhashtable_init(&buckets->table, &bch_move_bucket_params);
+	bch_err_msg(c, ret, "allocating copygc buckets in flight");
+	if (ret) {
+		kfree(buckets);
+		return ret;
+	}
+
+	set_freezable();
+
+	bch2_move_stats_init(&move_stats, "copygc");
+	bch2_moving_ctxt_init(&ctxt, c, NULL, &move_stats,
+			      writepoint_ptr(&c->copygc_write_point),
+			      false);
+
+	while (!ret && !kthread_should_stop()) {
+		bool did_work = false;
+
+		bch2_trans_unlock_long(ctxt.trans);
+		cond_resched();
+
+		if (!c->copy_gc_enabled) {
+			move_buckets_wait(&ctxt, buckets, true);
+			kthread_wait_freezable(c->copy_gc_enabled ||
+					       kthread_should_stop());
+		}
+
+		if (unlikely(freezing(current))) {
+			move_buckets_wait(&ctxt, buckets, true);
+			__refrigerator(false);
+			continue;
+		}
+
+		last = atomic64_read(&clock->now);
+		wait = bch2_copygc_wait_amount(c);
+
+		if (wait > clock->max_slop) {
+			c->copygc_wait_at = last;
+			c->copygc_wait = last + wait;
+			move_buckets_wait(&ctxt, buckets, true);
+			trace_and_count(c, copygc_wait, c, wait, last + wait);
+			bch2_kthread_io_clock_wait(clock, last + wait,
+					MAX_SCHEDULE_TIMEOUT);
+			continue;
+		}
+
+		c->copygc_wait = 0;
+
+		c->copygc_running = true;
+		ret = bch2_copygc(&ctxt, buckets, &did_work);
+		c->copygc_running = false;
+
+		wake_up(&c->copygc_running_wq);
+
+		if (!wait && !did_work) {
+			u64 min_member_capacity = bch2_min_rw_member_capacity(c);
+
+			if (min_member_capacity == U64_MAX)
+				min_member_capacity = 128 * 2048;
+
+			bch2_trans_unlock_long(ctxt.trans);
+			bch2_kthread_io_clock_wait(clock, last + (min_member_capacity >> 6),
+					MAX_SCHEDULE_TIMEOUT);
+		}
+	}
+
+	move_buckets_wait(&ctxt, buckets, true);
+
+	rhashtable_destroy(&buckets->table);
+	kfree(buckets);
+	bch2_moving_ctxt_exit(&ctxt);
+	bch2_move_stats_exit(&move_stats, c);
+
+	return 0;
+}
+
+void bch2_copygc_stop(struct bch_fs *c)
+{
+	if (c->copygc_thread) {
+		kthread_stop(c->copygc_thread);
+		put_task_struct(c->copygc_thread);
+	}
+	c->copygc_thread = NULL;
+}
+
+int bch2_copygc_start(struct bch_fs *c)
+{
+	struct task_struct *t;
+	int ret;
+
+	if (c->copygc_thread)
+		return 0;
+
+	if (c->opts.nochanges)
+		return 0;
+
+	if (bch2_fs_init_fault("copygc_start"))
+		return -ENOMEM;
+
+	t = kthread_create(bch2_copygc_thread, c, "bch-copygc/%s", c->name);
+	ret = PTR_ERR_OR_ZERO(t);
+	bch_err_msg(c, ret, "creating copygc thread");
+	if (ret)
+		return ret;
+
+	get_task_struct(t);
+
+	c->copygc_thread = t;
+	wake_up_process(c->copygc_thread);
+
+	return 0;
+}
+
+void bch2_fs_copygc_init(struct bch_fs *c)
+{
+	init_waitqueue_head(&c->copygc_running_wq);
+	c->copygc_running = false;
+}