drivers/lightnvm/pblk-gc.c

   1 /*
   2  * Copyright (C) 2016 CNEX Labs
   3  * Initial release: Javier Gonzalez <[email protected]>
   4  *                  Matias Bjorling <[email protected]>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License version
   8  * 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * pblk-gc.c - pblk's garbage collector
  16  */
  17
  18 #include "pblk.h"
  19 #include <linux/delay.h>
  20
  21 static void pblk_gc_free_gc_rq(struct pblk_gc_rq *gc_rq)
  22 {
  23         if (gc_rq->data)
  24                 vfree(gc_rq->data);
  25         kfree(gc_rq);
  26 }
  27
  28 static int pblk_gc_write(struct pblk *pblk)
  29 {
  30         struct pblk_gc *gc = &pblk->gc;
  31         struct pblk_gc_rq *gc_rq, *tgc_rq;
  32         LIST_HEAD(w_list);
  33
  34         spin_lock(&gc->w_lock);
  35         if (list_empty(&gc->w_list)) {
  36                 spin_unlock(&gc->w_lock);
  37                 return 1;
  38         }
  39
  40         list_cut_position(&w_list, &gc->w_list, gc->w_list.prev);
  41         gc->w_entries = 0;
  42         spin_unlock(&gc->w_lock);
  43
  44         list_for_each_entry_safe(gc_rq, tgc_rq, &w_list, list) {
  45                 pblk_write_gc_to_cache(pblk, gc_rq);
  46                 list_del(&gc_rq->list);
  47                 kref_put(&gc_rq->line->ref, pblk_line_put);
  48                 pblk_gc_free_gc_rq(gc_rq);
  49         }
  50
  51         return 0;
  52 }
  53
  54 static void pblk_gc_writer_kick(struct pblk_gc *gc)
  55 {
  56         wake_up_process(gc->gc_writer_ts);
  57 }
  58
  59 static void pblk_put_line_back(struct pblk *pblk, struct pblk_line *line)
  60 {
  61         struct pblk_line_mgmt *l_mg = &pblk->l_mg;
  62         struct list_head *move_list;
  63
  64         spin_lock(&line->lock);
  65         WARN_ON(line->state != PBLK_LINESTATE_GC);
  66         line->state = PBLK_LINESTATE_CLOSED;
  67         move_list = pblk_line_gc_list(pblk, line);
  68         spin_unlock(&line->lock);
  69
  70         if (move_list) {
  71                 spin_lock(&l_mg->gc_lock);
  72                 list_add_tail(&line->list, move_list);
  73                 spin_unlock(&l_mg->gc_lock);
  74         }
  75 }
  76
  77 static void pblk_gc_line_ws(struct work_struct *work)
  78 {
  79         struct pblk_line_ws *gc_rq_ws = container_of(work,
  80                                                 struct pblk_line_ws, ws);
  81         struct pblk *pblk = gc_rq_ws->pblk;
  82         struct nvm_tgt_dev *dev = pblk->dev;
  83         struct nvm_geo *geo = &dev->geo;
  84         struct pblk_gc *gc = &pblk->gc;
  85         struct pblk_line *line = gc_rq_ws->line;
  86         struct pblk_gc_rq *gc_rq = gc_rq_ws->priv;
  87         int ret;
  88
  89         up(&gc->gc_sem);
  90
  91         gc_rq->data = vmalloc(gc_rq->nr_secs * geo->csecs);
  92         if (!gc_rq->data) {
  93                 pr_err("pblk: could not GC line:%d (%d/%d)\n",
  94                                         line->id, *line->vsc, gc_rq->nr_secs);
  95                 goto out;
  96         }
  97
  98         /* Read from GC victim block */
  99         ret = pblk_submit_read_gc(pblk, gc_rq);
 100         if (ret) {
 101                 pr_err("pblk: failed GC read in line:%d (err:%d)\n",
 102                                                                 line->id, ret);
 103                 goto out;
 104         }
 105
 106         if (!gc_rq->secs_to_gc)
 107                 goto out;
 108
 109 retry:
 110         spin_lock(&gc->w_lock);
 111         if (gc->w_entries >= PBLK_GC_RQ_QD) {
 112                 spin_unlock(&gc->w_lock);
 113                 pblk_gc_writer_kick(&pblk->gc);
 114                 usleep_range(128, 256);
 115                 goto retry;
 116         }
 117         gc->w_entries++;
 118         list_add_tail(&gc_rq->list, &gc->w_list);
 119         spin_unlock(&gc->w_lock);
 120
 121         pblk_gc_writer_kick(&pblk->gc);
 122
 123         kfree(gc_rq_ws);
 124         return;
 125
 126 out:
 127         pblk_gc_free_gc_rq(gc_rq);
 128         kref_put(&line->ref, pblk_line_put);
 129         kfree(gc_rq_ws);
 130 }
 131
 132 static void pblk_gc_line_prepare_ws(struct work_struct *work)
 133 {
 134         struct pblk_line_ws *line_ws = container_of(work, struct pblk_line_ws,
 135                                                                         ws);
 136         struct pblk *pblk = line_ws->pblk;
 137         struct pblk_line *line = line_ws->line;
 138         struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 139         struct pblk_line_meta *lm = &pblk->lm;
 140         struct pblk_gc *gc = &pblk->gc;
 141         struct line_emeta *emeta_buf;
 142         struct pblk_line_ws *gc_rq_ws;
 143         struct pblk_gc_rq *gc_rq;
 144         __le64 *lba_list;
 145         unsigned long *invalid_bitmap;
 146         int sec_left, nr_secs, bit;
 147         int ret;
 148
 149         invalid_bitmap = kmalloc(lm->sec_bitmap_len, GFP_KERNEL);
 150         if (!invalid_bitmap)
 151                 goto fail_free_ws;
 152
 153         emeta_buf = pblk_malloc(lm->emeta_len[0], l_mg->emeta_alloc_type,
 154                                                                 GFP_KERNEL);
 155         if (!emeta_buf) {
 156                 pr_err("pblk: cannot use GC emeta\n");
 157                 goto fail_free_bitmap;
 158         }
 159
 160         ret = pblk_line_read_emeta(pblk, line, emeta_buf);
 161         if (ret) {
 162                 pr_err("pblk: line %d read emeta failed (%d)\n", line->id, ret);
 163                 goto fail_free_emeta;
 164         }
 165
 166         /* If this read fails, it means that emeta is corrupted. For now, leave
 167          * the line untouched. TODO: Implement a recovery routine that scans and
 168          * moves all sectors on the line.
 169          */
 170
 171         ret = pblk_recov_check_emeta(pblk, emeta_buf);
 172         if (ret) {
 173                 pr_err("pblk: inconsistent emeta (line %d)\n", line->id);
 174                 goto fail_free_emeta;
 175         }
 176
 177         lba_list = emeta_to_lbas(pblk, emeta_buf);
 178         if (!lba_list) {
 179                 pr_err("pblk: could not interpret emeta (line %d)\n", line->id);
 180                 goto fail_free_emeta;
 181         }
 182
 183         spin_lock(&line->lock);
 184         bitmap_copy(invalid_bitmap, line->invalid_bitmap, lm->sec_per_line);
 185         sec_left = pblk_line_vsc(line);
 186         spin_unlock(&line->lock);
 187
 188         if (sec_left < 0) {
 189                 pr_err("pblk: corrupted GC line (%d)\n", line->id);
 190                 goto fail_free_emeta;
 191         }
 192
 193         bit = -1;
 194 next_rq:
 195         gc_rq = kmalloc(sizeof(struct pblk_gc_rq), GFP_KERNEL);
 196         if (!gc_rq)
 197                 goto fail_free_emeta;
 198
 199         nr_secs = 0;
 200         do {
 201                 bit = find_next_zero_bit(invalid_bitmap, lm->sec_per_line,
 202                                                                 bit + 1);
 203                 if (bit > line->emeta_ssec)
 204                         break;
 205
 206                 gc_rq->paddr_list[nr_secs] = bit;
 207                 gc_rq->lba_list[nr_secs++] = le64_to_cpu(lba_list[bit]);
 208         } while (nr_secs < pblk->max_write_pgs);
 209
 210         if (unlikely(!nr_secs)) {
 211                 kfree(gc_rq);
 212                 goto out;
 213         }
 214
 215         gc_rq->nr_secs = nr_secs;
 216         gc_rq->line = line;
 217
 218         gc_rq_ws = kmalloc(sizeof(struct pblk_line_ws), GFP_KERNEL);
 219         if (!gc_rq_ws)
 220                 goto fail_free_gc_rq;
 221
 222         gc_rq_ws->pblk = pblk;
 223         gc_rq_ws->line = line;
 224         gc_rq_ws->priv = gc_rq;
 225
 226         /* The write GC path can be much slower than the read GC one due to
 227          * the budget imposed by the rate-limiter. Balance in case that we get
 228          * back pressure from the write GC path.
 229          */
 230         while (down_timeout(&gc->gc_sem, msecs_to_jiffies(30000)))
 231                 io_schedule();
 232
 233         kref_get(&line->ref);
 234
 235         INIT_WORK(&gc_rq_ws->ws, pblk_gc_line_ws);
 236         queue_work(gc->gc_line_reader_wq, &gc_rq_ws->ws);
 237
 238         sec_left -= nr_secs;
 239         if (sec_left > 0)
 240                 goto next_rq;
 241
 242 out:
 243         pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
 244         kfree(line_ws);
 245         kfree(invalid_bitmap);
 246
 247         kref_put(&line->ref, pblk_line_put);
 248         atomic_dec(&gc->read_inflight_gc);
 249
 250         return;
 251
 252 fail_free_gc_rq:
 253         kfree(gc_rq);
 254 fail_free_emeta:
 255         pblk_mfree(emeta_buf, l_mg->emeta_alloc_type);
 256 fail_free_bitmap:
 257         kfree(invalid_bitmap);
 258 fail_free_ws:
 259         kfree(line_ws);
 260
 261         pblk_put_line_back(pblk, line);
 262         kref_put(&line->ref, pblk_line_put);
 263         atomic_dec(&gc->read_inflight_gc);
 264
 265         pr_err("pblk: Failed to GC line %d\n", line->id);
 266 }
 267
 268 static int pblk_gc_line(struct pblk *pblk, struct pblk_line *line)
 269 {
 270         struct pblk_gc *gc = &pblk->gc;
 271         struct pblk_line_ws *line_ws;
 272
 273         pr_debug("pblk: line '%d' being reclaimed for GC\n", line->id);
 274
 275         line_ws = kmalloc(sizeof(struct pblk_line_ws), GFP_KERNEL);
 276         if (!line_ws)
 277                 return -ENOMEM;
 278
 279         line_ws->pblk = pblk;
 280         line_ws->line = line;
 281
 282         atomic_inc(&gc->pipeline_gc);
 283         INIT_WORK(&line_ws->ws, pblk_gc_line_prepare_ws);
 284         queue_work(gc->gc_reader_wq, &line_ws->ws);
 285
 286         return 0;
 287 }
 288
 289 static void pblk_gc_reader_kick(struct pblk_gc *gc)
 290 {
 291         wake_up_process(gc->gc_reader_ts);
 292 }
 293
 294 static void pblk_gc_kick(struct pblk *pblk)
 295 {
 296         struct pblk_gc *gc = &pblk->gc;
 297
 298         pblk_gc_writer_kick(gc);
 299         pblk_gc_reader_kick(gc);
 300
 301         /* If we're shutting down GC, let's not start it up again */
 302         if (gc->gc_enabled) {
 303                 wake_up_process(gc->gc_ts);
 304                 mod_timer(&gc->gc_timer,
 305                           jiffies + msecs_to_jiffies(GC_TIME_MSECS));
 306         }
 307 }
 308
 309 static int pblk_gc_read(struct pblk *pblk)
 310 {
 311         struct pblk_gc *gc = &pblk->gc;
 312         struct pblk_line *line;
 313
 314         spin_lock(&gc->r_lock);
 315         if (list_empty(&gc->r_list)) {
 316                 spin_unlock(&gc->r_lock);
 317                 return 1;
 318         }
 319
 320         line = list_first_entry(&gc->r_list, struct pblk_line, list);
 321         list_del(&line->list);
 322         spin_unlock(&gc->r_lock);
 323
 324         pblk_gc_kick(pblk);
 325
 326         if (pblk_gc_line(pblk, line))
 327                 pr_err("pblk: failed to GC line %d\n", line->id);
 328
 329         return 0;
 330 }
 331
 332 static struct pblk_line *pblk_gc_get_victim_line(struct pblk *pblk,
 333                                                  struct list_head *group_list)
 334 {
 335         struct pblk_line *line, *victim;
 336         int line_vsc, victim_vsc;
 337
 338         victim = list_first_entry(group_list, struct pblk_line, list);
 339         list_for_each_entry(line, group_list, list) {
 340                 line_vsc = le32_to_cpu(*line->vsc);
 341                 victim_vsc = le32_to_cpu(*victim->vsc);
 342                 if (line_vsc < victim_vsc)
 343                         victim = line;
 344         }
 345
 346         return victim;
 347 }
 348
 349 static bool pblk_gc_should_run(struct pblk_gc *gc, struct pblk_rl *rl)
 350 {
 351         unsigned int nr_blocks_free, nr_blocks_need;
 352
 353         nr_blocks_need = pblk_rl_high_thrs(rl);
 354         nr_blocks_free = pblk_rl_nr_free_blks(rl);
 355
 356         /* This is not critical, no need to take lock here */
 357         return ((gc->gc_active) && (nr_blocks_need > nr_blocks_free));
 358 }
 359
 360 void pblk_gc_free_full_lines(struct pblk *pblk)
 361 {
 362         struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 363         struct pblk_gc *gc = &pblk->gc;
 364         struct pblk_line *line;
 365
 366         do {
 367                 spin_lock(&l_mg->gc_lock);
 368                 if (list_empty(&l_mg->gc_full_list)) {
 369                         spin_unlock(&l_mg->gc_lock);
 370                         return;
 371                 }
 372
 373                 line = list_first_entry(&l_mg->gc_full_list,
 374                                                         struct pblk_line, list);
 375
 376                 spin_lock(&line->lock);
 377                 WARN_ON(line->state != PBLK_LINESTATE_CLOSED);
 378                 line->state = PBLK_LINESTATE_GC;
 379                 spin_unlock(&line->lock);
 380
 381                 list_del(&line->list);
 382                 spin_unlock(&l_mg->gc_lock);
 383
 384                 atomic_inc(&gc->pipeline_gc);
 385                 kref_put(&line->ref, pblk_line_put);
 386         } while (1);
 387 }
 388
 389 /*
 390  * Lines with no valid sectors will be returned to the free list immediately. If
 391  * GC is activated - either because the free block count is under the determined
 392  * threshold, or because it is being forced from user space - only lines with a
 393  * high count of invalid sectors will be recycled.
 394  */
 395 static void pblk_gc_run(struct pblk *pblk)
 396 {
 397         struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 398         struct pblk_gc *gc = &pblk->gc;
 399         struct pblk_line *line;
 400         struct list_head *group_list;
 401         bool run_gc;
 402         int read_inflight_gc, gc_group = 0, prev_group = 0;
 403
 404         pblk_gc_free_full_lines(pblk);
 405
 406         run_gc = pblk_gc_should_run(&pblk->gc, &pblk->rl);
 407         if (!run_gc || (atomic_read(&gc->read_inflight_gc) >= PBLK_GC_L_QD))
 408                 return;
 409
 410 next_gc_group:
 411         group_list = l_mg->gc_lists[gc_group++];
 412
 413         do {
 414                 spin_lock(&l_mg->gc_lock);
 415                 if (list_empty(group_list)) {
 416                         spin_unlock(&l_mg->gc_lock);
 417                         break;
 418                 }
 419
 420                 line = pblk_gc_get_victim_line(pblk, group_list);
 421
 422                 spin_lock(&line->lock);
 423                 WARN_ON(line->state != PBLK_LINESTATE_CLOSED);
 424                 line->state = PBLK_LINESTATE_GC;
 425                 spin_unlock(&line->lock);
 426
 427                 list_del(&line->list);
 428                 spin_unlock(&l_mg->gc_lock);
 429
 430                 spin_lock(&gc->r_lock);
 431                 list_add_tail(&line->list, &gc->r_list);
 432                 spin_unlock(&gc->r_lock);
 433
 434                 read_inflight_gc = atomic_inc_return(&gc->read_inflight_gc);
 435                 pblk_gc_reader_kick(gc);
 436
 437                 prev_group = 1;
 438
 439                 /* No need to queue up more GC lines than we can handle */
 440                 run_gc = pblk_gc_should_run(&pblk->gc, &pblk->rl);
 441                 if (!run_gc || read_inflight_gc >= PBLK_GC_L_QD)
 442                         break;
 443         } while (1);
 444
 445         if (!prev_group && pblk->rl.rb_state > gc_group &&
 446                                                 gc_group < PBLK_GC_NR_LISTS)
 447                 goto next_gc_group;
 448 }
 449
 450 static void pblk_gc_timer(struct timer_list *t)
 451 {
 452         struct pblk *pblk = from_timer(pblk, t, gc.gc_timer);
 453
 454         pblk_gc_kick(pblk);
 455 }
 456
 457 static int pblk_gc_ts(void *data)
 458 {
 459         struct pblk *pblk = data;
 460
 461         while (!kthread_should_stop()) {
 462                 pblk_gc_run(pblk);
 463                 set_current_state(TASK_INTERRUPTIBLE);
 464                 io_schedule();
 465         }
 466
 467         return 0;
 468 }
 469
 470 static int pblk_gc_writer_ts(void *data)
 471 {
 472         struct pblk *pblk = data;
 473
 474         while (!kthread_should_stop()) {
 475                 if (!pblk_gc_write(pblk))
 476                         continue;
 477                 set_current_state(TASK_INTERRUPTIBLE);
 478                 io_schedule();
 479         }
 480
 481         return 0;
 482 }
 483
 484 static int pblk_gc_reader_ts(void *data)
 485 {
 486         struct pblk *pblk = data;
 487         struct pblk_gc *gc = &pblk->gc;
 488
 489         while (!kthread_should_stop()) {
 490                 if (!pblk_gc_read(pblk))
 491                         continue;
 492                 set_current_state(TASK_INTERRUPTIBLE);
 493                 io_schedule();
 494         }
 495
 496 #ifdef CONFIG_NVM_DEBUG
 497         pr_info("pblk: flushing gc pipeline, %d lines left\n",
 498                 atomic_read(&gc->pipeline_gc));
 499 #endif
 500
 501         do {
 502                 if (!atomic_read(&gc->pipeline_gc))
 503                         break;
 504
 505                 schedule();
 506         } while (1);
 507
 508         return 0;
 509 }
 510
 511 static void pblk_gc_start(struct pblk *pblk)
 512 {
 513         pblk->gc.gc_active = 1;
 514         pr_debug("pblk: gc start\n");
 515 }
 516
 517 void pblk_gc_should_start(struct pblk *pblk)
 518 {
 519         struct pblk_gc *gc = &pblk->gc;
 520
 521         if (gc->gc_enabled && !gc->gc_active) {
 522                 pblk_gc_start(pblk);
 523                 pblk_gc_kick(pblk);
 524         }
 525 }
 526
 527 void pblk_gc_should_stop(struct pblk *pblk)
 528 {
 529         struct pblk_gc *gc = &pblk->gc;
 530
 531         if (gc->gc_active && !gc->gc_forced)
 532                 gc->gc_active = 0;
 533 }
 534
 535 void pblk_gc_should_kick(struct pblk *pblk)
 536 {
 537         pblk_rl_update_rates(&pblk->rl);
 538 }
 539
 540 void pblk_gc_sysfs_state_show(struct pblk *pblk, int *gc_enabled,
 541                               int *gc_active)
 542 {
 543         struct pblk_gc *gc = &pblk->gc;
 544
 545         spin_lock(&gc->lock);
 546         *gc_enabled = gc->gc_enabled;
 547         *gc_active = gc->gc_active;
 548         spin_unlock(&gc->lock);
 549 }
 550
 551 int pblk_gc_sysfs_force(struct pblk *pblk, int force)
 552 {
 553         struct pblk_gc *gc = &pblk->gc;
 554
 555         if (force < 0 || force > 1)
 556                 return -EINVAL;
 557
 558         spin_lock(&gc->lock);
 559         gc->gc_forced = force;
 560
 561         if (force)
 562                 gc->gc_enabled = 1;
 563         else
 564                 gc->gc_enabled = 0;
 565         spin_unlock(&gc->lock);
 566
 567         pblk_gc_should_start(pblk);
 568
 569         return 0;
 570 }
 571
 572 int pblk_gc_init(struct pblk *pblk)
 573 {
 574         struct pblk_gc *gc = &pblk->gc;
 575         int ret;
 576
 577         gc->gc_ts = kthread_create(pblk_gc_ts, pblk, "pblk-gc-ts");
 578         if (IS_ERR(gc->gc_ts)) {
 579                 pr_err("pblk: could not allocate GC main kthread\n");
 580                 return PTR_ERR(gc->gc_ts);
 581         }
 582
 583         gc->gc_writer_ts = kthread_create(pblk_gc_writer_ts, pblk,
 584                                                         "pblk-gc-writer-ts");
 585         if (IS_ERR(gc->gc_writer_ts)) {
 586                 pr_err("pblk: could not allocate GC writer kthread\n");
 587                 ret = PTR_ERR(gc->gc_writer_ts);
 588                 goto fail_free_main_kthread;
 589         }
 590
 591         gc->gc_reader_ts = kthread_create(pblk_gc_reader_ts, pblk,
 592                                                         "pblk-gc-reader-ts");
 593         if (IS_ERR(gc->gc_reader_ts)) {
 594                 pr_err("pblk: could not allocate GC reader kthread\n");
 595                 ret = PTR_ERR(gc->gc_reader_ts);
 596                 goto fail_free_writer_kthread;
 597         }
 598
 599         timer_setup(&gc->gc_timer, pblk_gc_timer, 0);
 600         mod_timer(&gc->gc_timer, jiffies + msecs_to_jiffies(GC_TIME_MSECS));
 601
 602         gc->gc_active = 0;
 603         gc->gc_forced = 0;
 604         gc->gc_enabled = 1;
 605         gc->w_entries = 0;
 606         atomic_set(&gc->read_inflight_gc, 0);
 607         atomic_set(&gc->pipeline_gc, 0);
 608
 609         /* Workqueue that reads valid sectors from a line and submit them to the
 610          * GC writer to be recycled.
 611          */
 612         gc->gc_line_reader_wq = alloc_workqueue("pblk-gc-line-reader-wq",
 613                         WQ_MEM_RECLAIM | WQ_UNBOUND, PBLK_GC_MAX_READERS);
 614         if (!gc->gc_line_reader_wq) {
 615                 pr_err("pblk: could not allocate GC line reader workqueue\n");
 616                 ret = -ENOMEM;
 617                 goto fail_free_reader_kthread;
 618         }
 619
 620         /* Workqueue that prepare lines for GC */
 621         gc->gc_reader_wq = alloc_workqueue("pblk-gc-line_wq",
 622                                         WQ_MEM_RECLAIM | WQ_UNBOUND, 1);
 623         if (!gc->gc_reader_wq) {
 624                 pr_err("pblk: could not allocate GC reader workqueue\n");
 625                 ret = -ENOMEM;
 626                 goto fail_free_reader_line_wq;
 627         }
 628
 629         spin_lock_init(&gc->lock);
 630         spin_lock_init(&gc->w_lock);
 631         spin_lock_init(&gc->r_lock);
 632
 633         sema_init(&gc->gc_sem, PBLK_GC_RQ_QD);
 634
 635         INIT_LIST_HEAD(&gc->w_list);
 636         INIT_LIST_HEAD(&gc->r_list);
 637
 638         return 0;
 639
 640 fail_free_reader_line_wq:
 641         destroy_workqueue(gc->gc_line_reader_wq);
 642 fail_free_reader_kthread:
 643         kthread_stop(gc->gc_reader_ts);
 644 fail_free_writer_kthread:
 645         kthread_stop(gc->gc_writer_ts);
 646 fail_free_main_kthread:
 647         kthread_stop(gc->gc_ts);
 648
 649         return ret;
 650 }
 651
 652 void pblk_gc_exit(struct pblk *pblk)
 653 {
 654         struct pblk_gc *gc = &pblk->gc;
 655
 656         gc->gc_enabled = 0;
 657         del_timer_sync(&gc->gc_timer);
 658         gc->gc_active = 0;
 659
 660         if (gc->gc_ts)
 661                 kthread_stop(gc->gc_ts);
 662
 663         if (gc->gc_reader_ts)
 664                 kthread_stop(gc->gc_reader_ts);
 665
 666         flush_workqueue(gc->gc_reader_wq);
 667         destroy_workqueue(gc->gc_reader_wq);
 668
 669         flush_workqueue(gc->gc_line_reader_wq);
 670         destroy_workqueue(gc->gc_line_reader_wq);
 671
 672         if (gc->gc_writer_ts)
 673                 kthread_stop(gc->gc_writer_ts);
 674 }