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(size: sizeof(*new), GFP_KERNEL);
47 int ret;
48
49 if (!new)
50 return ERR_PTR(error: -ENOMEM);
51
52 new->bucket = b;
53
54 ret = rhashtable_lookup_insert_fast(ht: &list->table, obj: &new->hash,
55 params: bch_move_bucket_params);
56 if (ret) {
57 kfree(objp: new);
58 return ERR_PTR(error: 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(c: trans->c,
82 dev: b->k.bucket.inode,
83 bucket: b->k.bucket.offset))
84 return 0;
85
86 k = bch2_bkey_get_iter(trans, iter: &iter, btree_id: BTREE_ID_alloc,
87 pos: b->k.bucket, flags: BTREE_ITER_CACHED);
88 ret = bkey_err(k);
89 if (ret)
90 return ret;
91
92 a = bch2_alloc_to_v4(k, convert: &_a);
93 b->k.gen = a->gen;
94 b->sectors = bch2_bucket_sectors_dirty(a: *a);
95
96 ret = data_type_movable(type: 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(v: &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(ht: &list->table, obj: &i->hash,
126 params: bch_move_bucket_params);
127 BUG_ON(ret);
128 kfree(objp: 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(ht: &list->table, key: &k, params: 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, list: buckets_in_flight, flush: 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(v: &ctxt->stats->sectors_moved);
210 int ret = 0;
211
212 ret = bch2_copygc_get_buckets(ctxt, buckets_in_flight, buckets: &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(list: buckets_in_flight, b: *i);
221 ret = PTR_ERR_OR_ZERO(ptr: 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(v: &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, watermark: 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(type: 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(size: sizeof(struct buckets_in_flight), GFP_KERNEL);
317 if (!buckets)
318 return -ENOMEM;
319 ret = rhashtable_init(ht: &buckets->table, params: &bch_move_bucket_params);
320 bch_err_msg(c, ret, "allocating copygc buckets in flight");
321 if (ret) {
322 kfree(objp: 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(wp: &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: &ctxt, list: buckets, flush: 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: &ctxt, list: buckets, flush: true);
347 __refrigerator(check_kthr_stop: false);
348 continue;
349 }
350
351 last = atomic64_read(v: &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: &ctxt, list: buckets, flush: 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: &ctxt, buckets_in_flight: buckets, did_work: &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: &ctxt, list: buckets, flush: true);
385
386 rhashtable_destroy(ht: &buckets->table);
387 kfree(objp: 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(k: c->copygc_thread);
398 put_task_struct(t: 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(ptr: 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(tsk: 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

source code of linux/fs/bcachefs/movinggc.c