1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Moving/copying garbage collector
4 *
5 * Copyright 2012 Google, Inc.
6 */
7
8#include "bcachefs.h"
9#include "alloc_background.h"
10#include "alloc_foreground.h"
11#include "btree_iter.h"
12#include "btree_update.h"
13#include "btree_write_buffer.h"
14#include "buckets.h"
15#include "clock.h"
16#include "errcode.h"
17#include "error.h"
18#include "lru.h"
19#include "move.h"
20#include "movinggc.h"
21#include "trace.h"
22
23#include <linux/freezer.h>
24#include <linux/kthread.h>
25#include <linux/math64.h>
26#include <linux/sched/task.h>
27#include <linux/wait.h>
28
29struct buckets_in_flight {
30	struct rhashtable		table;
31	struct move_bucket_in_flight	*first;
32	struct move_bucket_in_flight	*last;
33	size_t				nr;
34	size_t				sectors;
35};
36
37static const struct rhashtable_params bch_move_bucket_params = {
38	.head_offset	= offsetof(struct move_bucket_in_flight, hash),
39	.key_offset	= offsetof(struct move_bucket_in_flight, bucket.k),
40	.key_len	= sizeof(struct move_bucket_key),
41};
42
43static struct move_bucket_in_flight *
44move_bucket_in_flight_add(struct buckets_in_flight *list, struct move_bucket b)
45{
46	struct move_bucket_in_flight *new = kzalloc(sizeof(*new), GFP_KERNEL);
47	int ret;
48
49	if (!new)
50		return ERR_PTR(-ENOMEM);
51
52	new->bucket = b;
53
54	ret = rhashtable_lookup_insert_fast(&list->table, &new->hash,
55					    bch_move_bucket_params);
56	if (ret) {
57		kfree(new);
58		return ERR_PTR(ret);
59	}
60
61	if (!list->first)
62		list->first = new;
63	else
64		list->last->next = new;
65
66	list->last = new;
67	list->nr++;
68	list->sectors += b.sectors;
69	return new;
70}
71
72static int bch2_bucket_is_movable(struct btree_trans *trans,
73				  struct move_bucket *b, u64 time)
74{
75	struct btree_iter iter;
76	struct bkey_s_c k;
77	struct bch_alloc_v4 _a;
78	const struct bch_alloc_v4 *a;
79	int ret;
80
81	if (bch2_bucket_is_open(trans->c,
82				b->k.bucket.inode,
83				b->k.bucket.offset))
84		return 0;
85
86	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_alloc,
87			       b->k.bucket, BTREE_ITER_CACHED);
88	ret = bkey_err(k);
89	if (ret)
90		return ret;
91
92	a = bch2_alloc_to_v4(k, &_a);
93	b->k.gen	= a->gen;
94	b->sectors	= bch2_bucket_sectors_dirty(*a);
95
96	ret = data_type_movable(a->data_type) &&
97		a->fragmentation_lru &&
98		a->fragmentation_lru <= time;
99
100	bch2_trans_iter_exit(trans, &iter);
101	return ret;
102}
103
104static void move_buckets_wait(struct moving_context *ctxt,
105			      struct buckets_in_flight *list,
106			      bool flush)
107{
108	struct move_bucket_in_flight *i;
109	int ret;
110
111	while ((i = list->first)) {
112		if (flush)
113			move_ctxt_wait_event(ctxt, !atomic_read(&i->count));
114
115		if (atomic_read(&i->count))
116			break;
117
118		list->first = i->next;
119		if (!list->first)
120			list->last = NULL;
121
122		list->nr--;
123		list->sectors -= i->bucket.sectors;
124
125		ret = rhashtable_remove_fast(&list->table, &i->hash,
126					     bch_move_bucket_params);
127		BUG_ON(ret);
128		kfree(i);
129	}
130
131	bch2_trans_unlock_long(ctxt->trans);
132}
133
134static bool bucket_in_flight(struct buckets_in_flight *list,
135			     struct move_bucket_key k)
136{
137	return rhashtable_lookup_fast(&list->table, &k, bch_move_bucket_params);
138}
139
140typedef DARRAY(struct move_bucket) move_buckets;
141
142static int bch2_copygc_get_buckets(struct moving_context *ctxt,
143			struct buckets_in_flight *buckets_in_flight,
144			move_buckets *buckets)
145{
146	struct btree_trans *trans = ctxt->trans;
147	struct bch_fs *c = trans->c;
148	size_t nr_to_get = max_t(size_t, 16U, buckets_in_flight->nr / 4);
149	size_t saw = 0, in_flight = 0, not_movable = 0, sectors = 0;
150	int ret;
151
152	move_buckets_wait(ctxt, buckets_in_flight, false);
153
154	ret = bch2_btree_write_buffer_tryflush(trans);
155	if (bch2_err_matches(ret, EROFS))
156		return ret;
157
158	if (bch2_fs_fatal_err_on(ret, c, "%s: from bch2_btree_write_buffer_tryflush()", bch2_err_str(ret)))
159		return ret;
160
161	ret = for_each_btree_key_upto(trans, iter, BTREE_ID_lru,
162				  lru_pos(BCH_LRU_FRAGMENTATION_START, 0, 0),
163				  lru_pos(BCH_LRU_FRAGMENTATION_START, U64_MAX, LRU_TIME_MAX),
164				  0, k, ({
165		struct move_bucket b = { .k.bucket = u64_to_bucket(k.k->p.offset) };
166		int ret2 = 0;
167
168		saw++;
169
170		ret2 = bch2_bucket_is_movable(trans, &b, lru_pos_time(k.k->p));
171		if (ret2 < 0)
172			goto err;
173
174		if (!ret2)
175			not_movable++;
176		else if (bucket_in_flight(buckets_in_flight, b.k))
177			in_flight++;
178		else {
179			ret2 = darray_push(buckets, b);
180			if (ret2)
181				goto err;
182			sectors += b.sectors;
183		}
184
185		ret2 = buckets->nr >= nr_to_get;
186err:
187		ret2;
188	}));
189
190	pr_debug("have: %zu (%zu) saw %zu in flight %zu not movable %zu got %zu (%zu)/%zu buckets ret %i",
191		 buckets_in_flight->nr, buckets_in_flight->sectors,
192		 saw, in_flight, not_movable, buckets->nr, sectors, nr_to_get, ret);
193
194	return ret < 0 ? ret : 0;
195}
196
197noinline
198static int bch2_copygc(struct moving_context *ctxt,
199		       struct buckets_in_flight *buckets_in_flight,
200		       bool *did_work)
201{
202	struct btree_trans *trans = ctxt->trans;
203	struct bch_fs *c = trans->c;
204	struct data_update_opts data_opts = {
205		.btree_insert_flags = BCH_WATERMARK_copygc,
206	};
207	move_buckets buckets = { 0 };
208	struct move_bucket_in_flight *f;
209	u64 moved = atomic64_read(&ctxt->stats->sectors_moved);
210	int ret = 0;
211
212	ret = bch2_copygc_get_buckets(ctxt, buckets_in_flight, &buckets);
213	if (ret)
214		goto err;
215
216	darray_for_each(buckets, i) {
217		if (kthread_should_stop() || freezing(current))
218			break;
219
220		f = move_bucket_in_flight_add(buckets_in_flight, *i);
221		ret = PTR_ERR_OR_ZERO(f);
222		if (ret == -EEXIST) { /* rare race: copygc_get_buckets returned same bucket more than once */
223			ret = 0;
224			continue;
225		}
226		if (ret == -ENOMEM) { /* flush IO, continue later */
227			ret = 0;
228			break;
229		}
230
231		ret = bch2_evacuate_bucket(ctxt, f, f->bucket.k.bucket,
232					     f->bucket.k.gen, data_opts);
233		if (ret)
234			goto err;
235
236		*did_work = true;
237	}
238err:
239	darray_exit(&buckets);
240
241	/* no entries in LRU btree found, or got to end: */
242	if (bch2_err_matches(ret, ENOENT))
243		ret = 0;
244
245	if (ret < 0 && !bch2_err_matches(ret, EROFS))
246		bch_err_msg(c, ret, "from bch2_move_data()");
247
248	moved = atomic64_read(&ctxt->stats->sectors_moved) - moved;
249	trace_and_count(c, copygc, c, moved, 0, 0, 0);
250	return ret;
251}
252
253/*
254 * Copygc runs when the amount of fragmented data is above some arbitrary
255 * threshold:
256 *
257 * The threshold at the limit - when the device is full - is the amount of space
258 * we reserved in bch2_recalc_capacity; we can't have more than that amount of
259 * disk space stranded due to fragmentation and store everything we have
260 * promised to store.
261 *
262 * But we don't want to be running copygc unnecessarily when the device still
263 * has plenty of free space - rather, we want copygc to smoothly run every so
264 * often and continually reduce the amount of fragmented space as the device
265 * fills up. So, we increase the threshold by half the current free space.
266 */
267unsigned long bch2_copygc_wait_amount(struct bch_fs *c)
268{
269	s64 wait = S64_MAX, fragmented_allowed, fragmented;
270
271	for_each_rw_member(c, ca) {
272		struct bch_dev_usage usage = bch2_dev_usage_read(ca);
273
274		fragmented_allowed = ((__dev_buckets_available(ca, usage, BCH_WATERMARK_stripe) *
275				       ca->mi.bucket_size) >> 1);
276		fragmented = 0;
277
278		for (unsigned i = 0; i < BCH_DATA_NR; i++)
279			if (data_type_movable(i))
280				fragmented += usage.d[i].fragmented;
281
282		wait = min(wait, max(0LL, fragmented_allowed - fragmented));
283	}
284
285	return wait;
286}
287
288void bch2_copygc_wait_to_text(struct printbuf *out, struct bch_fs *c)
289{
290	prt_printf(out, "Currently waiting for:     ");
291	prt_human_readable_u64(out, max(0LL, c->copygc_wait -
292					atomic64_read(&c->io_clock[WRITE].now)) << 9);
293	prt_newline(out);
294
295	prt_printf(out, "Currently waiting since:   ");
296	prt_human_readable_u64(out, max(0LL,
297					atomic64_read(&c->io_clock[WRITE].now) -
298					c->copygc_wait_at) << 9);
299	prt_newline(out);
300
301	prt_printf(out, "Currently calculated wait: ");
302	prt_human_readable_u64(out, bch2_copygc_wait_amount(c));
303	prt_newline(out);
304}
305
306static int bch2_copygc_thread(void *arg)
307{
308	struct bch_fs *c = arg;
309	struct moving_context ctxt;
310	struct bch_move_stats move_stats;
311	struct io_clock *clock = &c->io_clock[WRITE];
312	struct buckets_in_flight *buckets;
313	u64 last, wait;
314	int ret = 0;
315
316	buckets = kzalloc(sizeof(struct buckets_in_flight), GFP_KERNEL);
317	if (!buckets)
318		return -ENOMEM;
319	ret = rhashtable_init(&buckets->table, &bch_move_bucket_params);
320	bch_err_msg(c, ret, "allocating copygc buckets in flight");
321	if (ret) {
322		kfree(buckets);
323		return ret;
324	}
325
326	set_freezable();
327
328	bch2_move_stats_init(&move_stats, "copygc");
329	bch2_moving_ctxt_init(&ctxt, c, NULL, &move_stats,
330			      writepoint_ptr(&c->copygc_write_point),
331			      false);
332
333	while (!ret && !kthread_should_stop()) {
334		bool did_work = false;
335
336		bch2_trans_unlock_long(ctxt.trans);
337		cond_resched();
338
339		if (!c->copy_gc_enabled) {
340			move_buckets_wait(&ctxt, buckets, true);
341			kthread_wait_freezable(c->copy_gc_enabled ||
342					       kthread_should_stop());
343		}
344
345		if (unlikely(freezing(current))) {
346			move_buckets_wait(&ctxt, buckets, true);
347			__refrigerator(false);
348			continue;
349		}
350
351		last = atomic64_read(&clock->now);
352		wait = bch2_copygc_wait_amount(c);
353
354		if (wait > clock->max_slop) {
355			c->copygc_wait_at = last;
356			c->copygc_wait = last + wait;
357			move_buckets_wait(&ctxt, buckets, true);
358			trace_and_count(c, copygc_wait, c, wait, last + wait);
359			bch2_kthread_io_clock_wait(clock, last + wait,
360					MAX_SCHEDULE_TIMEOUT);
361			continue;
362		}
363
364		c->copygc_wait = 0;
365
366		c->copygc_running = true;
367		ret = bch2_copygc(&ctxt, buckets, &did_work);
368		c->copygc_running = false;
369
370		wake_up(&c->copygc_running_wq);
371
372		if (!wait && !did_work) {
373			u64 min_member_capacity = bch2_min_rw_member_capacity(c);
374
375			if (min_member_capacity == U64_MAX)
376				min_member_capacity = 128 * 2048;
377
378			bch2_trans_unlock_long(ctxt.trans);
379			bch2_kthread_io_clock_wait(clock, last + (min_member_capacity >> 6),
380					MAX_SCHEDULE_TIMEOUT);
381		}
382	}
383
384	move_buckets_wait(&ctxt, buckets, true);
385
386	rhashtable_destroy(&buckets->table);
387	kfree(buckets);
388	bch2_moving_ctxt_exit(&ctxt);
389	bch2_move_stats_exit(&move_stats, c);
390
391	return 0;
392}
393
394void bch2_copygc_stop(struct bch_fs *c)
395{
396	if (c->copygc_thread) {
397		kthread_stop(c->copygc_thread);
398		put_task_struct(c->copygc_thread);
399	}
400	c->copygc_thread = NULL;
401}
402
403int bch2_copygc_start(struct bch_fs *c)
404{
405	struct task_struct *t;
406	int ret;
407
408	if (c->copygc_thread)
409		return 0;
410
411	if (c->opts.nochanges)
412		return 0;
413
414	if (bch2_fs_init_fault("copygc_start"))
415		return -ENOMEM;
416
417	t = kthread_create(bch2_copygc_thread, c, "bch-copygc/%s", c->name);
418	ret = PTR_ERR_OR_ZERO(t);
419	bch_err_msg(c, ret, "creating copygc thread");
420	if (ret)
421		return ret;
422
423	get_task_struct(t);
424
425	c->copygc_thread = t;
426	wake_up_process(c->copygc_thread);
427
428	return 0;
429}
430
431void bch2_fs_copygc_init(struct bch_fs *c)
432{
433	init_waitqueue_head(&c->copygc_running_wq);
434	c->copygc_running = false;
435}
436