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 29 struct 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 37 static 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 43 static struct move_bucket_in_flight * 44 move_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 72 static 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 = a->dirty_sectors; 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 } 103 104 static void move_buckets_wait(struct btree_trans *trans, 105 struct moving_context *ctxt, 106 struct buckets_in_flight *list, 107 bool flush) 108 { 109 struct move_bucket_in_flight *i; 110 int ret; 111 112 while ((i = list->first)) { 113 if (flush) 114 move_ctxt_wait_event(ctxt, trans, !atomic_read(&i->count)); 115 116 if (atomic_read(&i->count)) 117 break; 118 119 list->first = i->next; 120 if (!list->first) 121 list->last = NULL; 122 123 list->nr--; 124 list->sectors -= i->bucket.sectors; 125 126 ret = rhashtable_remove_fast(&list->table, &i->hash, 127 bch_move_bucket_params); 128 BUG_ON(ret); 129 kfree(i); 130 } 131 132 bch2_trans_unlock(trans); 133 } 134 135 static bool bucket_in_flight(struct buckets_in_flight *list, 136 struct move_bucket_key k) 137 { 138 return rhashtable_lookup_fast(&list->table, &k, bch_move_bucket_params); 139 } 140 141 typedef DARRAY(struct move_bucket) move_buckets; 142 143 static int bch2_copygc_get_buckets(struct btree_trans *trans, 144 struct moving_context *ctxt, 145 struct buckets_in_flight *buckets_in_flight, 146 move_buckets *buckets) 147 { 148 struct bch_fs *c = trans->c; 149 struct btree_iter iter; 150 struct bkey_s_c k; 151 size_t nr_to_get = max_t(size_t, 16U, buckets_in_flight->nr / 4); 152 size_t saw = 0, in_flight = 0, not_movable = 0, sectors = 0; 153 int ret; 154 155 move_buckets_wait(trans, ctxt, buckets_in_flight, false); 156 157 ret = bch2_btree_write_buffer_flush(trans); 158 if (bch2_fs_fatal_err_on(ret, c, "%s: error %s from bch2_btree_write_buffer_flush()", 159 __func__, bch2_err_str(ret))) 160 return ret; 161 162 ret = for_each_btree_key2_upto(trans, iter, BTREE_ID_lru, 163 lru_pos(BCH_LRU_FRAGMENTATION_START, 0, 0), 164 lru_pos(BCH_LRU_FRAGMENTATION_START, U64_MAX, LRU_TIME_MAX), 165 0, k, ({ 166 struct move_bucket b = { .k.bucket = u64_to_bucket(k.k->p.offset) }; 167 int ret2 = 0; 168 169 saw++; 170 171 if (!bch2_bucket_is_movable(trans, &b, lru_pos_time(k.k->p))) 172 not_movable++; 173 else if (bucket_in_flight(buckets_in_flight, b.k)) 174 in_flight++; 175 else { 176 ret2 = darray_push(buckets, b) ?: buckets->nr >= nr_to_get; 177 if (ret2 >= 0) 178 sectors += b.sectors; 179 } 180 ret2; 181 })); 182 183 pr_debug("have: %zu (%zu) saw %zu in flight %zu not movable %zu got %zu (%zu)/%zu buckets ret %i", 184 buckets_in_flight->nr, buckets_in_flight->sectors, 185 saw, in_flight, not_movable, buckets->nr, sectors, nr_to_get, ret); 186 187 return ret < 0 ? ret : 0; 188 } 189 190 noinline 191 static int bch2_copygc(struct btree_trans *trans, 192 struct moving_context *ctxt, 193 struct buckets_in_flight *buckets_in_flight) 194 { 195 struct bch_fs *c = trans->c; 196 struct data_update_opts data_opts = { 197 .btree_insert_flags = BCH_WATERMARK_copygc, 198 }; 199 move_buckets buckets = { 0 }; 200 struct move_bucket_in_flight *f; 201 struct move_bucket *i; 202 u64 moved = atomic64_read(&ctxt->stats->sectors_moved); 203 int ret = 0; 204 205 ret = bch2_copygc_get_buckets(trans, ctxt, buckets_in_flight, &buckets); 206 if (ret) 207 goto err; 208 209 darray_for_each(buckets, i) { 210 if (unlikely(freezing(current))) 211 break; 212 213 f = move_bucket_in_flight_add(buckets_in_flight, *i); 214 ret = PTR_ERR_OR_ZERO(f); 215 if (ret == -EEXIST) { /* rare race: copygc_get_buckets returned same bucket more than once */ 216 ret = 0; 217 continue; 218 } 219 if (ret == -ENOMEM) { /* flush IO, continue later */ 220 ret = 0; 221 break; 222 } 223 224 ret = __bch2_evacuate_bucket(trans, ctxt, f, f->bucket.k.bucket, 225 f->bucket.k.gen, data_opts); 226 if (ret) 227 goto err; 228 } 229 err: 230 darray_exit(&buckets); 231 232 /* no entries in LRU btree found, or got to end: */ 233 if (bch2_err_matches(ret, ENOENT)) 234 ret = 0; 235 236 if (ret < 0 && !bch2_err_matches(ret, EROFS)) 237 bch_err_msg(c, ret, "from bch2_move_data()"); 238 239 moved = atomic64_read(&ctxt->stats->sectors_moved) - moved; 240 trace_and_count(c, copygc, c, moved, 0, 0, 0); 241 return ret; 242 } 243 244 /* 245 * Copygc runs when the amount of fragmented data is above some arbitrary 246 * threshold: 247 * 248 * The threshold at the limit - when the device is full - is the amount of space 249 * we reserved in bch2_recalc_capacity; we can't have more than that amount of 250 * disk space stranded due to fragmentation and store everything we have 251 * promised to store. 252 * 253 * But we don't want to be running copygc unnecessarily when the device still 254 * has plenty of free space - rather, we want copygc to smoothly run every so 255 * often and continually reduce the amount of fragmented space as the device 256 * fills up. So, we increase the threshold by half the current free space. 257 */ 258 unsigned long bch2_copygc_wait_amount(struct bch_fs *c) 259 { 260 struct bch_dev *ca; 261 unsigned dev_idx; 262 s64 wait = S64_MAX, fragmented_allowed, fragmented; 263 unsigned i; 264 265 for_each_rw_member(ca, c, dev_idx) { 266 struct bch_dev_usage usage = bch2_dev_usage_read(ca); 267 268 fragmented_allowed = ((__dev_buckets_available(ca, usage, BCH_WATERMARK_stripe) * 269 ca->mi.bucket_size) >> 1); 270 fragmented = 0; 271 272 for (i = 0; i < BCH_DATA_NR; i++) 273 if (data_type_movable(i)) 274 fragmented += usage.d[i].fragmented; 275 276 wait = min(wait, max(0LL, fragmented_allowed - fragmented)); 277 } 278 279 return wait; 280 } 281 282 void bch2_copygc_wait_to_text(struct printbuf *out, struct bch_fs *c) 283 { 284 prt_printf(out, "Currently waiting for: "); 285 prt_human_readable_u64(out, max(0LL, c->copygc_wait - 286 atomic64_read(&c->io_clock[WRITE].now)) << 9); 287 prt_newline(out); 288 289 prt_printf(out, "Currently waiting since: "); 290 prt_human_readable_u64(out, max(0LL, 291 atomic64_read(&c->io_clock[WRITE].now) - 292 c->copygc_wait_at) << 9); 293 prt_newline(out); 294 295 prt_printf(out, "Currently calculated wait: "); 296 prt_human_readable_u64(out, bch2_copygc_wait_amount(c)); 297 prt_newline(out); 298 } 299 300 static int bch2_copygc_thread(void *arg) 301 { 302 struct bch_fs *c = arg; 303 struct btree_trans *trans; 304 struct moving_context ctxt; 305 struct bch_move_stats move_stats; 306 struct io_clock *clock = &c->io_clock[WRITE]; 307 struct buckets_in_flight buckets; 308 u64 last, wait; 309 int ret = 0; 310 311 memset(&buckets, 0, sizeof(buckets)); 312 313 ret = rhashtable_init(&buckets.table, &bch_move_bucket_params); 314 if (ret) { 315 bch_err_msg(c, ret, "allocating copygc buckets in flight"); 316 return ret; 317 } 318 319 set_freezable(); 320 trans = bch2_trans_get(c); 321 322 bch2_move_stats_init(&move_stats, "copygc"); 323 bch2_moving_ctxt_init(&ctxt, c, NULL, &move_stats, 324 writepoint_ptr(&c->copygc_write_point), 325 false); 326 327 while (!ret && !kthread_should_stop()) { 328 bch2_trans_unlock(trans); 329 cond_resched(); 330 331 if (!c->copy_gc_enabled) { 332 move_buckets_wait(trans, &ctxt, &buckets, true); 333 kthread_wait_freezable(c->copy_gc_enabled); 334 } 335 336 if (unlikely(freezing(current))) { 337 move_buckets_wait(trans, &ctxt, &buckets, true); 338 __refrigerator(false); 339 continue; 340 } 341 342 last = atomic64_read(&clock->now); 343 wait = bch2_copygc_wait_amount(c); 344 345 if (wait > clock->max_slop) { 346 c->copygc_wait_at = last; 347 c->copygc_wait = last + wait; 348 move_buckets_wait(trans, &ctxt, &buckets, true); 349 trace_and_count(c, copygc_wait, c, wait, last + wait); 350 bch2_kthread_io_clock_wait(clock, last + wait, 351 MAX_SCHEDULE_TIMEOUT); 352 continue; 353 } 354 355 c->copygc_wait = 0; 356 357 c->copygc_running = true; 358 ret = bch2_copygc(trans, &ctxt, &buckets); 359 c->copygc_running = false; 360 361 wake_up(&c->copygc_running_wq); 362 } 363 364 move_buckets_wait(trans, &ctxt, &buckets, true); 365 rhashtable_destroy(&buckets.table); 366 bch2_trans_put(trans); 367 bch2_moving_ctxt_exit(&ctxt); 368 369 return 0; 370 } 371 372 void bch2_copygc_stop(struct bch_fs *c) 373 { 374 if (c->copygc_thread) { 375 kthread_stop(c->copygc_thread); 376 put_task_struct(c->copygc_thread); 377 } 378 c->copygc_thread = NULL; 379 } 380 381 int bch2_copygc_start(struct bch_fs *c) 382 { 383 struct task_struct *t; 384 int ret; 385 386 if (c->copygc_thread) 387 return 0; 388 389 if (c->opts.nochanges) 390 return 0; 391 392 if (bch2_fs_init_fault("copygc_start")) 393 return -ENOMEM; 394 395 t = kthread_create(bch2_copygc_thread, c, "bch-copygc/%s", c->name); 396 ret = PTR_ERR_OR_ZERO(t); 397 if (ret) { 398 bch_err_msg(c, ret, "creating copygc thread"); 399 return ret; 400 } 401 402 get_task_struct(t); 403 404 c->copygc_thread = t; 405 wake_up_process(c->copygc_thread); 406 407 return 0; 408 } 409 410 void bch2_fs_copygc_init(struct bch_fs *c) 411 { 412 init_waitqueue_head(&c->copygc_running_wq); 413 c->copygc_running = false; 414 } 415