git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/btree_gc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
   4  * Copyright (C) 2014 Datera Inc.
   5  */
   6
   7 #include "bcachefs.h"
   8 #include "alloc_background.h"
   9 #include "alloc_foreground.h"
  10 #include "bkey_methods.h"
  11 #include "btree_locking.h"
  12 #include "btree_update_interior.h"
  13 #include "btree_io.h"
  14 #include "btree_gc.h"
  15 #include "buckets.h"
  16 #include "clock.h"
  17 #include "debug.h"
  18 #include "ec.h"
  19 #include "error.h"
  20 #include "extents.h"
  21 #include "journal.h"
  22 #include "keylist.h"
  23 #include "move.h"
  24 #include "recovery.h"
  25 #include "replicas.h"
  26 #include "super-io.h"
  27
  28 #include <linux/slab.h>
  29 #include <linux/bitops.h>
  30 #include <linux/freezer.h>
  31 #include <linux/kthread.h>
  32 #include <linux/preempt.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/sched/task.h>
  35 #include <trace/events/bcachefs.h>
  36
  37 static inline void __gc_pos_set(struct bch_fs *c, struct gc_pos new_pos)
  38 {
  39         write_seqcount_begin(&c->gc_pos_lock);
  40         c->gc_pos = new_pos;
  41         write_seqcount_end(&c->gc_pos_lock);
  42 }
  43
  44 static inline void gc_pos_set(struct bch_fs *c, struct gc_pos new_pos)
  45 {
  46         BUG_ON(gc_pos_cmp(new_pos, c->gc_pos) <= 0);
  47         __gc_pos_set(c, new_pos);
  48 }
  49
  50 static int bch2_gc_check_topology(struct bch_fs *c,
  51                                   struct bkey_s_c k,
  52                                   struct bpos *expected_start,
  53                                   struct bpos expected_end,
  54                                   bool is_last)
  55 {
  56         int ret = 0;
  57
  58         if (k.k->type == KEY_TYPE_btree_ptr_v2) {
  59                 struct bkey_s_c_btree_ptr_v2 bp = bkey_s_c_to_btree_ptr_v2(k);
  60
  61                 if (fsck_err_on(bkey_cmp(*expected_start, bp.v->min_key), c,
  62                                 "btree node with incorrect min_key: got %llu:%llu, should be %llu:%llu",
  63                                 bp.v->min_key.inode,
  64                                 bp.v->min_key.offset,
  65                                 expected_start->inode,
  66                                 expected_start->offset)) {
  67                         BUG();
  68                 }
  69         }
  70
  71         *expected_start = bkey_cmp(k.k->p, POS_MAX)
  72                 ? bkey_successor(k.k->p)
  73                 : k.k->p;
  74
  75         if (fsck_err_on(is_last &&
  76                         bkey_cmp(k.k->p, expected_end), c,
  77                         "btree node with incorrect max_key: got %llu:%llu, should be %llu:%llu",
  78                         k.k->p.inode,
  79                         k.k->p.offset,
  80                         expected_end.inode,
  81                         expected_end.offset)) {
  82                 BUG();
  83         }
  84 fsck_err:
  85         return ret;
  86 }
  87
  88 /* marking of btree keys/nodes: */
  89
  90 static int bch2_gc_mark_key(struct bch_fs *c, struct bkey_s_c k,
  91                             u8 *max_stale, bool initial)
  92 {
  93         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  94         const struct bch_extent_ptr *ptr;
  95         unsigned flags =
  96                 BTREE_TRIGGER_GC|
  97                 (initial ? BTREE_TRIGGER_NOATOMIC : 0);
  98         int ret = 0;
  99
 100         if (initial) {
 101                 BUG_ON(journal_seq_verify(c) &&
 102                        k.k->version.lo > journal_cur_seq(&c->journal));
 103
 104                 /* XXX change to fsck check */
 105                 if (fsck_err_on(k.k->version.lo > atomic64_read(&c->key_version), c,
 106                                 "key version number higher than recorded: %llu > %llu",
 107                                 k.k->version.lo,
 108                                 atomic64_read(&c->key_version)))
 109                         atomic64_set(&c->key_version, k.k->version.lo);
 110
 111                 if (test_bit(BCH_FS_REBUILD_REPLICAS, &c->flags) ||
 112                     fsck_err_on(!bch2_bkey_replicas_marked(c, k), c,
 113                                 "superblock not marked as containing replicas (type %u)",
 114                                 k.k->type)) {
 115                         ret = bch2_mark_bkey_replicas(c, k);
 116                         if (ret)
 117                                 return ret;
 118                 }
 119
 120                 bkey_for_each_ptr(ptrs, ptr) {
 121                         struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
 122                         struct bucket *g = PTR_BUCKET(ca, ptr, true);
 123                         struct bucket *g2 = PTR_BUCKET(ca, ptr, false);
 124
 125                         if (mustfix_fsck_err_on(!g->gen_valid, c,
 126                                         "bucket %u:%zu data type %s ptr gen %u missing in alloc btree",
 127                                         ptr->dev, PTR_BUCKET_NR(ca, ptr),
 128                                         bch2_data_types[ptr_data_type(k.k, ptr)],
 129                                         ptr->gen)) {
 130                                 g2->_mark.gen   = g->_mark.gen          = ptr->gen;
 131                                 g2->gen_valid   = g->gen_valid          = true;
 132                         }
 133
 134                         if (mustfix_fsck_err_on(gen_cmp(ptr->gen, g->mark.gen) > 0, c,
 135                                         "bucket %u:%zu data type %s ptr gen in the future: %u > %u",
 136                                         ptr->dev, PTR_BUCKET_NR(ca, ptr),
 137                                         bch2_data_types[ptr_data_type(k.k, ptr)],
 138                                         ptr->gen, g->mark.gen)) {
 139                                 g2->_mark.gen   = g->_mark.gen          = ptr->gen;
 140                                 g2->gen_valid   = g->gen_valid          = true;
 141                                 g2->_mark.data_type             = 0;
 142                                 g2->_mark.dirty_sectors         = 0;
 143                                 g2->_mark.cached_sectors        = 0;
 144                                 set_bit(BCH_FS_FIXED_GENS, &c->flags);
 145                         }
 146                 }
 147         }
 148
 149         bkey_for_each_ptr(ptrs, ptr) {
 150                 struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
 151                 struct bucket *g = PTR_BUCKET(ca, ptr, true);
 152
 153                 if (gen_after(g->oldest_gen, ptr->gen))
 154                         g->oldest_gen = ptr->gen;
 155
 156                 *max_stale = max(*max_stale, ptr_stale(ca, ptr));
 157         }
 158
 159         bch2_mark_key(c, k, 0, k.k->size, NULL, 0, flags);
 160 fsck_err:
 161         return ret;
 162 }
 163
 164 static int btree_gc_mark_node(struct bch_fs *c, struct btree *b, u8 *max_stale,
 165                               bool initial)
 166 {
 167         struct bpos next_node_start = b->data->min_key;
 168         struct btree_node_iter iter;
 169         struct bkey unpacked;
 170         struct bkey_s_c k;
 171         int ret = 0;
 172
 173         *max_stale = 0;
 174
 175         if (!btree_node_type_needs_gc(btree_node_type(b)))
 176                 return 0;
 177
 178         bch2_btree_node_iter_init_from_start(&iter, b);
 179
 180         while ((k = bch2_btree_node_iter_peek_unpack(&iter, b, &unpacked)).k) {
 181                 bch2_bkey_debugcheck(c, b, k);
 182
 183                 ret = bch2_gc_mark_key(c, k, max_stale, initial);
 184                 if (ret)
 185                         break;
 186
 187                 bch2_btree_node_iter_advance(&iter, b);
 188
 189                 if (b->c.level) {
 190                         ret = bch2_gc_check_topology(c, k,
 191                                         &next_node_start,
 192                                         b->data->max_key,
 193                                         bch2_btree_node_iter_end(&iter));
 194                         if (ret)
 195                                 break;
 196                 }
 197         }
 198
 199         return ret;
 200 }
 201
 202 static int bch2_gc_btree(struct bch_fs *c, enum btree_id btree_id,
 203                          bool initial, bool metadata_only)
 204 {
 205         struct btree_trans trans;
 206         struct btree_iter *iter;
 207         struct btree *b;
 208         unsigned depth = metadata_only                  ? 1
 209                 : expensive_debug_checks(c)             ? 0
 210                 : !btree_node_type_needs_gc(btree_id)   ? 1
 211                 : 0;
 212         u8 max_stale = 0;
 213         int ret = 0;
 214
 215         bch2_trans_init(&trans, c, 0, 0);
 216
 217         gc_pos_set(c, gc_pos_btree(btree_id, POS_MIN, 0));
 218
 219         __for_each_btree_node(&trans, iter, btree_id, POS_MIN,
 220                               0, depth, BTREE_ITER_PREFETCH, b) {
 221                 bch2_verify_btree_nr_keys(b);
 222
 223                 gc_pos_set(c, gc_pos_btree_node(b));
 224
 225                 ret = btree_gc_mark_node(c, b, &max_stale, initial);
 226                 if (ret)
 227                         break;
 228
 229                 if (!initial) {
 230                         if (max_stale > 64)
 231                                 bch2_btree_node_rewrite(c, iter,
 232                                                 b->data->keys.seq,
 233                                                 BTREE_INSERT_USE_RESERVE|
 234                                                 BTREE_INSERT_NOWAIT|
 235                                                 BTREE_INSERT_GC_LOCK_HELD);
 236                         else if (!btree_gc_rewrite_disabled(c) &&
 237                                  (btree_gc_always_rewrite(c) || max_stale > 16))
 238                                 bch2_btree_node_rewrite(c, iter,
 239                                                 b->data->keys.seq,
 240                                                 BTREE_INSERT_NOWAIT|
 241                                                 BTREE_INSERT_GC_LOCK_HELD);
 242                 }
 243
 244                 bch2_trans_cond_resched(&trans);
 245         }
 246         ret = bch2_trans_exit(&trans) ?: ret;
 247         if (ret)
 248                 return ret;
 249
 250         mutex_lock(&c->btree_root_lock);
 251         b = c->btree_roots[btree_id].b;
 252         if (!btree_node_fake(b))
 253                 ret = bch2_gc_mark_key(c, bkey_i_to_s_c(&b->key),
 254                                        &max_stale, initial);
 255         gc_pos_set(c, gc_pos_btree_root(b->c.btree_id));
 256         mutex_unlock(&c->btree_root_lock);
 257
 258         return ret;
 259 }
 260
 261 static int bch2_gc_btree_init_recurse(struct bch_fs *c, struct btree *b,
 262                                       struct journal_keys *journal_keys,
 263                                       unsigned target_depth)
 264 {
 265         struct btree_and_journal_iter iter;
 266         struct bkey_s_c k;
 267         struct bpos next_node_start = b->data->min_key;
 268         u8 max_stale = 0;
 269         int ret = 0;
 270
 271         bch2_btree_and_journal_iter_init_node_iter(&iter, journal_keys, b);
 272
 273         while ((k = bch2_btree_and_journal_iter_peek(&iter)).k) {
 274                 bch2_bkey_debugcheck(c, b, k);
 275
 276                 BUG_ON(bkey_cmp(k.k->p, b->data->min_key) < 0);
 277                 BUG_ON(bkey_cmp(k.k->p, b->data->max_key) > 0);
 278
 279                 ret = bch2_gc_mark_key(c, k, &max_stale, true);
 280                 if (ret)
 281                         break;
 282
 283                 if (b->c.level) {
 284                         struct btree *child;
 285                         BKEY_PADDED(k) tmp;
 286
 287                         bkey_reassemble(&tmp.k, k);
 288                         k = bkey_i_to_s_c(&tmp.k);
 289
 290                         bch2_btree_and_journal_iter_advance(&iter);
 291
 292                         ret = bch2_gc_check_topology(c, k,
 293                                         &next_node_start,
 294                                         b->data->max_key,
 295                                         !bch2_btree_and_journal_iter_peek(&iter).k);
 296                         if (ret)
 297                                 break;
 298
 299                         if (b->c.level > target_depth) {
 300                                 child = bch2_btree_node_get_noiter(c, &tmp.k,
 301                                                         b->c.btree_id, b->c.level - 1);
 302                                 ret = PTR_ERR_OR_ZERO(child);
 303                                 if (ret)
 304                                         break;
 305
 306                                 ret = bch2_gc_btree_init_recurse(c, child,
 307                                                 journal_keys, target_depth);
 308                                 six_unlock_read(&child->c.lock);
 309
 310                                 if (ret)
 311                                         break;
 312                         }
 313                 } else {
 314                         bch2_btree_and_journal_iter_advance(&iter);
 315                 }
 316         }
 317
 318         return ret;
 319 }
 320
 321 static int bch2_gc_btree_init(struct bch_fs *c,
 322                               struct journal_keys *journal_keys,
 323                               enum btree_id btree_id,
 324                               bool metadata_only)
 325 {
 326         struct btree *b;
 327         unsigned target_depth = metadata_only           ? 1
 328                 : expensive_debug_checks(c)             ? 0
 329                 : !btree_node_type_needs_gc(btree_id)   ? 1
 330                 : 0;
 331         u8 max_stale = 0;
 332         int ret = 0;
 333
 334         b = c->btree_roots[btree_id].b;
 335
 336         if (btree_node_fake(b))
 337                 return 0;
 338
 339         six_lock_read(&b->c.lock, NULL, NULL);
 340         if (fsck_err_on(bkey_cmp(b->data->min_key, POS_MIN), c,
 341                         "btree root with incorrect min_key: %llu:%llu",
 342                         b->data->min_key.inode,
 343                         b->data->min_key.offset)) {
 344                 BUG();
 345         }
 346
 347         if (fsck_err_on(bkey_cmp(b->data->max_key, POS_MAX), c,
 348                         "btree root with incorrect min_key: %llu:%llu",
 349                         b->data->max_key.inode,
 350                         b->data->max_key.offset)) {
 351                 BUG();
 352         }
 353
 354         if (b->c.level >= target_depth)
 355                 ret = bch2_gc_btree_init_recurse(c, b,
 356                                         journal_keys, target_depth);
 357
 358         if (!ret)
 359                 ret = bch2_gc_mark_key(c, bkey_i_to_s_c(&b->key),
 360                                        &max_stale, true);
 361 fsck_err:
 362         six_unlock_read(&b->c.lock);
 363
 364         return ret;
 365 }
 366
 367 static inline int btree_id_gc_phase_cmp(enum btree_id l, enum btree_id r)
 368 {
 369         return  (int) btree_id_to_gc_phase(l) -
 370                 (int) btree_id_to_gc_phase(r);
 371 }
 372
 373 static int bch2_gc_btrees(struct bch_fs *c, struct journal_keys *journal_keys,
 374                           bool initial, bool metadata_only)
 375 {
 376         enum btree_id ids[BTREE_ID_NR];
 377         unsigned i;
 378
 379         for (i = 0; i < BTREE_ID_NR; i++)
 380                 ids[i] = i;
 381         bubble_sort(ids, BTREE_ID_NR, btree_id_gc_phase_cmp);
 382
 383         for (i = 0; i < BTREE_ID_NR; i++) {
 384                 enum btree_id id = ids[i];
 385                 int ret = initial
 386                         ? bch2_gc_btree_init(c, journal_keys,
 387                                              id, metadata_only)
 388                         : bch2_gc_btree(c, id, initial, metadata_only);
 389                 if (ret)
 390                         return ret;
 391         }
 392
 393         return 0;
 394 }
 395
 396 static void mark_metadata_sectors(struct bch_fs *c, struct bch_dev *ca,
 397                                   u64 start, u64 end,
 398                                   enum bch_data_type type,
 399                                   unsigned flags)
 400 {
 401         u64 b = sector_to_bucket(ca, start);
 402
 403         do {
 404                 unsigned sectors =
 405                         min_t(u64, bucket_to_sector(ca, b + 1), end) - start;
 406
 407                 bch2_mark_metadata_bucket(c, ca, b, type, sectors,
 408                                           gc_phase(GC_PHASE_SB), flags);
 409                 b++;
 410                 start += sectors;
 411         } while (start < end);
 412 }
 413
 414 void bch2_mark_dev_superblock(struct bch_fs *c, struct bch_dev *ca,
 415                               unsigned flags)
 416 {
 417         struct bch_sb_layout *layout = &ca->disk_sb.sb->layout;
 418         unsigned i;
 419         u64 b;
 420
 421         /*
 422          * This conditional is kind of gross, but we may be called from the
 423          * device add path, before the new device has actually been added to the
 424          * running filesystem:
 425          */
 426         if (c) {
 427                 lockdep_assert_held(&c->sb_lock);
 428                 percpu_down_read(&c->mark_lock);
 429         }
 430
 431         for (i = 0; i < layout->nr_superblocks; i++) {
 432                 u64 offset = le64_to_cpu(layout->sb_offset[i]);
 433
 434                 if (offset == BCH_SB_SECTOR)
 435                         mark_metadata_sectors(c, ca, 0, BCH_SB_SECTOR,
 436                                               BCH_DATA_sb, flags);
 437
 438                 mark_metadata_sectors(c, ca, offset,
 439                                       offset + (1 << layout->sb_max_size_bits),
 440                                       BCH_DATA_sb, flags);
 441         }
 442
 443         for (i = 0; i < ca->journal.nr; i++) {
 444                 b = ca->journal.buckets[i];
 445                 bch2_mark_metadata_bucket(c, ca, b, BCH_DATA_journal,
 446                                           ca->mi.bucket_size,
 447                                           gc_phase(GC_PHASE_SB), flags);
 448         }
 449
 450         if (c)
 451                 percpu_up_read(&c->mark_lock);
 452 }
 453
 454 static void bch2_mark_superblocks(struct bch_fs *c)
 455 {
 456         struct bch_dev *ca;
 457         unsigned i;
 458
 459         mutex_lock(&c->sb_lock);
 460         gc_pos_set(c, gc_phase(GC_PHASE_SB));
 461
 462         for_each_online_member(ca, c, i)
 463                 bch2_mark_dev_superblock(c, ca, BTREE_TRIGGER_GC);
 464         mutex_unlock(&c->sb_lock);
 465 }
 466
 467 #if 0
 468 /* Also see bch2_pending_btree_node_free_insert_done() */
 469 static void bch2_mark_pending_btree_node_frees(struct bch_fs *c)
 470 {
 471         struct btree_update *as;
 472         struct pending_btree_node_free *d;
 473
 474         mutex_lock(&c->btree_interior_update_lock);
 475         gc_pos_set(c, gc_phase(GC_PHASE_PENDING_DELETE));
 476
 477         for_each_pending_btree_node_free(c, as, d)
 478                 if (d->index_update_done)
 479                         bch2_mark_key(c, bkey_i_to_s_c(&d->key),
 480                                       0, 0, NULL, 0,
 481                                       BTREE_TRIGGER_GC);
 482
 483         mutex_unlock(&c->btree_interior_update_lock);
 484 }
 485 #endif
 486
 487 static void bch2_mark_allocator_buckets(struct bch_fs *c)
 488 {
 489         struct bch_dev *ca;
 490         struct open_bucket *ob;
 491         size_t i, j, iter;
 492         unsigned ci;
 493
 494         percpu_down_read(&c->mark_lock);
 495
 496         spin_lock(&c->freelist_lock);
 497         gc_pos_set(c, gc_pos_alloc(c, NULL));
 498
 499         for_each_member_device(ca, c, ci) {
 500                 fifo_for_each_entry(i, &ca->free_inc, iter)
 501                         bch2_mark_alloc_bucket(c, ca, i, true,
 502                                                gc_pos_alloc(c, NULL),
 503                                                BTREE_TRIGGER_GC);
 504
 505
 506
 507                 for (j = 0; j < RESERVE_NR; j++)
 508                         fifo_for_each_entry(i, &ca->free[j], iter)
 509                                 bch2_mark_alloc_bucket(c, ca, i, true,
 510                                                        gc_pos_alloc(c, NULL),
 511                                                        BTREE_TRIGGER_GC);
 512         }
 513
 514         spin_unlock(&c->freelist_lock);
 515
 516         for (ob = c->open_buckets;
 517              ob < c->open_buckets + ARRAY_SIZE(c->open_buckets);
 518              ob++) {
 519                 spin_lock(&ob->lock);
 520                 if (ob->valid) {
 521                         gc_pos_set(c, gc_pos_alloc(c, ob));
 522                         ca = bch_dev_bkey_exists(c, ob->ptr.dev);
 523                         bch2_mark_alloc_bucket(c, ca, PTR_BUCKET_NR(ca, &ob->ptr), true,
 524                                                gc_pos_alloc(c, ob),
 525                                                BTREE_TRIGGER_GC);
 526                 }
 527                 spin_unlock(&ob->lock);
 528         }
 529
 530         percpu_up_read(&c->mark_lock);
 531 }
 532
 533 static void bch2_gc_free(struct bch_fs *c)
 534 {
 535         struct bch_dev *ca;
 536         unsigned i;
 537
 538         genradix_free(&c->stripes[1]);
 539
 540         for_each_member_device(ca, c, i) {
 541                 kvpfree(rcu_dereference_protected(ca->buckets[1], 1),
 542                         sizeof(struct bucket_array) +
 543                         ca->mi.nbuckets * sizeof(struct bucket));
 544                 ca->buckets[1] = NULL;
 545
 546                 free_percpu(ca->usage[1]);
 547                 ca->usage[1] = NULL;
 548         }
 549
 550         free_percpu(c->usage_gc);
 551         c->usage_gc = NULL;
 552 }
 553
 554 static int bch2_gc_done(struct bch_fs *c,
 555                         bool initial, bool metadata_only)
 556 {
 557         struct bch_dev *ca;
 558         bool verify = !metadata_only &&
 559                 (!initial ||
 560                  (c->sb.compat & (1ULL << BCH_COMPAT_FEAT_ALLOC_INFO)));
 561         unsigned i;
 562         int ret = 0;
 563
 564 #define copy_field(_f, _msg, ...)                                       \
 565         if (dst->_f != src->_f) {                                       \
 566                 if (verify)                                             \
 567                         fsck_err(c, _msg ": got %llu, should be %llu"   \
 568                                 , ##__VA_ARGS__, dst->_f, src->_f);     \
 569                 dst->_f = src->_f;                                      \
 570         }
 571 #define copy_stripe_field(_f, _msg, ...)                                \
 572         if (dst->_f != src->_f) {                                       \
 573                 if (verify)                                             \
 574                         fsck_err(c, "stripe %zu has wrong "_msg         \
 575                                 ": got %u, should be %u",               \
 576                                 dst_iter.pos, ##__VA_ARGS__,            \
 577                                 dst->_f, src->_f);                      \
 578                 dst->_f = src->_f;                                      \
 579                 dst->dirty = true;                                      \
 580         }
 581 #define copy_bucket_field(_f)                                           \
 582         if (dst->b[b].mark._f != src->b[b].mark._f) {                   \
 583                 if (verify)                                             \
 584                         fsck_err(c, "bucket %u:%zu gen %u data type %s has wrong " #_f  \
 585                                 ": got %u, should be %u", i, b,         \
 586                                 dst->b[b].mark.gen,                     \
 587                                 bch2_data_types[dst->b[b].mark.data_type],\
 588                                 dst->b[b].mark._f, src->b[b].mark._f);  \
 589                 dst->b[b]._mark._f = src->b[b].mark._f;                 \
 590         }
 591 #define copy_dev_field(_f, _msg, ...)                                   \
 592         copy_field(_f, "dev %u has wrong " _msg, i, ##__VA_ARGS__)
 593 #define copy_fs_field(_f, _msg, ...)                                    \
 594         copy_field(_f, "fs has wrong " _msg, ##__VA_ARGS__)
 595
 596         if (!metadata_only) {
 597                 struct genradix_iter dst_iter = genradix_iter_init(&c->stripes[0], 0);
 598                 struct genradix_iter src_iter = genradix_iter_init(&c->stripes[1], 0);
 599                 struct stripe *dst, *src;
 600                 unsigned i;
 601
 602                 c->ec_stripes_heap.used = 0;
 603
 604                 while ((dst = genradix_iter_peek(&dst_iter, &c->stripes[0])) &&
 605                        (src = genradix_iter_peek(&src_iter, &c->stripes[1]))) {
 606                         BUG_ON(src_iter.pos != dst_iter.pos);
 607
 608                         copy_stripe_field(alive,        "alive");
 609                         copy_stripe_field(sectors,      "sectors");
 610                         copy_stripe_field(algorithm,    "algorithm");
 611                         copy_stripe_field(nr_blocks,    "nr_blocks");
 612                         copy_stripe_field(nr_redundant, "nr_redundant");
 613                         copy_stripe_field(blocks_nonempty,
 614                                           "blocks_nonempty");
 615
 616                         for (i = 0; i < ARRAY_SIZE(dst->block_sectors); i++)
 617                                 copy_stripe_field(block_sectors[i],
 618                                                   "block_sectors[%u]", i);
 619
 620                         if (dst->alive) {
 621                                 spin_lock(&c->ec_stripes_heap_lock);
 622                                 bch2_stripes_heap_insert(c, dst, dst_iter.pos);
 623                                 spin_unlock(&c->ec_stripes_heap_lock);
 624                         }
 625
 626                         genradix_iter_advance(&dst_iter, &c->stripes[0]);
 627                         genradix_iter_advance(&src_iter, &c->stripes[1]);
 628                 }
 629         }
 630
 631         for_each_member_device(ca, c, i) {
 632                 struct bucket_array *dst = __bucket_array(ca, 0);
 633                 struct bucket_array *src = __bucket_array(ca, 1);
 634                 size_t b;
 635
 636                 for (b = 0; b < src->nbuckets; b++) {
 637                         copy_bucket_field(gen);
 638                         copy_bucket_field(data_type);
 639                         copy_bucket_field(owned_by_allocator);
 640                         copy_bucket_field(stripe);
 641                         copy_bucket_field(dirty_sectors);
 642                         copy_bucket_field(cached_sectors);
 643
 644                         dst->b[b].oldest_gen = src->b[b].oldest_gen;
 645                 }
 646         };
 647
 648         bch2_fs_usage_acc_to_base(c, 0);
 649         bch2_fs_usage_acc_to_base(c, 1);
 650
 651         bch2_dev_usage_from_buckets(c);
 652
 653         {
 654                 unsigned nr = fs_usage_u64s(c);
 655                 struct bch_fs_usage *dst = c->usage_base;
 656                 struct bch_fs_usage *src = (void *)
 657                         bch2_acc_percpu_u64s((void *) c->usage_gc, nr);
 658
 659                 copy_fs_field(hidden,           "hidden");
 660                 copy_fs_field(btree,            "btree");
 661
 662                 if (!metadata_only) {
 663                         copy_fs_field(data,     "data");
 664                         copy_fs_field(cached,   "cached");
 665                         copy_fs_field(reserved, "reserved");
 666                         copy_fs_field(nr_inodes,"nr_inodes");
 667
 668                         for (i = 0; i < BCH_REPLICAS_MAX; i++)
 669                                 copy_fs_field(persistent_reserved[i],
 670                                               "persistent_reserved[%i]", i);
 671                 }
 672
 673                 for (i = 0; i < c->replicas.nr; i++) {
 674                         struct bch_replicas_entry *e =
 675                                 cpu_replicas_entry(&c->replicas, i);
 676                         char buf[80];
 677
 678                         if (metadata_only &&
 679                             (e->data_type == BCH_DATA_user ||
 680                              e->data_type == BCH_DATA_cached))
 681                                 continue;
 682
 683                         bch2_replicas_entry_to_text(&PBUF(buf), e);
 684
 685                         copy_fs_field(replicas[i], "%s", buf);
 686                 }
 687         }
 688
 689 #undef copy_fs_field
 690 #undef copy_dev_field
 691 #undef copy_bucket_field
 692 #undef copy_stripe_field
 693 #undef copy_field
 694 fsck_err:
 695         return ret;
 696 }
 697
 698 static int bch2_gc_start(struct bch_fs *c,
 699                          bool metadata_only)
 700 {
 701         struct bch_dev *ca;
 702         unsigned i;
 703         int ret;
 704
 705         BUG_ON(c->usage_gc);
 706
 707         c->usage_gc = __alloc_percpu_gfp(fs_usage_u64s(c) * sizeof(u64),
 708                                          sizeof(u64), GFP_KERNEL);
 709         if (!c->usage_gc) {
 710                 bch_err(c, "error allocating c->usage_gc");
 711                 return -ENOMEM;
 712         }
 713
 714         for_each_member_device(ca, c, i) {
 715                 BUG_ON(ca->buckets[1]);
 716                 BUG_ON(ca->usage[1]);
 717
 718                 ca->buckets[1] = kvpmalloc(sizeof(struct bucket_array) +
 719                                 ca->mi.nbuckets * sizeof(struct bucket),
 720                                 GFP_KERNEL|__GFP_ZERO);
 721                 if (!ca->buckets[1]) {
 722                         percpu_ref_put(&ca->ref);
 723                         bch_err(c, "error allocating ca->buckets[gc]");
 724                         return -ENOMEM;
 725                 }
 726
 727                 ca->usage[1] = alloc_percpu(struct bch_dev_usage);
 728                 if (!ca->usage[1]) {
 729                         bch_err(c, "error allocating ca->usage[gc]");
 730                         percpu_ref_put(&ca->ref);
 731                         return -ENOMEM;
 732                 }
 733         }
 734
 735         ret = bch2_ec_mem_alloc(c, true);
 736         if (ret) {
 737                 bch_err(c, "error allocating ec gc mem");
 738                 return ret;
 739         }
 740
 741         percpu_down_write(&c->mark_lock);
 742
 743         /*
 744          * indicate to stripe code that we need to allocate for the gc stripes
 745          * radix tree, too
 746          */
 747         gc_pos_set(c, gc_phase(GC_PHASE_START));
 748
 749         for_each_member_device(ca, c, i) {
 750                 struct bucket_array *dst = __bucket_array(ca, 1);
 751                 struct bucket_array *src = __bucket_array(ca, 0);
 752                 size_t b;
 753
 754                 dst->first_bucket       = src->first_bucket;
 755                 dst->nbuckets           = src->nbuckets;
 756
 757                 for (b = 0; b < src->nbuckets; b++) {
 758                         struct bucket *d = &dst->b[b];
 759                         struct bucket *s = &src->b[b];
 760
 761                         d->_mark.gen = dst->b[b].oldest_gen = s->mark.gen;
 762                         d->gen_valid = s->gen_valid;
 763
 764                         if (metadata_only &&
 765                             (s->mark.data_type == BCH_DATA_user ||
 766                              s->mark.data_type == BCH_DATA_cached)) {
 767                                 d->_mark = s->mark;
 768                                 d->_mark.owned_by_allocator = 0;
 769                         }
 770                 }
 771         };
 772
 773         percpu_up_write(&c->mark_lock);
 774
 775         return 0;
 776 }
 777
 778 /**
 779  * bch2_gc - walk _all_ references to buckets, and recompute them:
 780  *
 781  * Order matters here:
 782  *  - Concurrent GC relies on the fact that we have a total ordering for
 783  *    everything that GC walks - see  gc_will_visit_node(),
 784  *    gc_will_visit_root()
 785  *
 786  *  - also, references move around in the course of index updates and
 787  *    various other crap: everything needs to agree on the ordering
 788  *    references are allowed to move around in - e.g., we're allowed to
 789  *    start with a reference owned by an open_bucket (the allocator) and
 790  *    move it to the btree, but not the reverse.
 791  *
 792  *    This is necessary to ensure that gc doesn't miss references that
 793  *    move around - if references move backwards in the ordering GC
 794  *    uses, GC could skip past them
 795  */
 796 int bch2_gc(struct bch_fs *c, struct journal_keys *journal_keys,
 797             bool initial, bool metadata_only)
 798 {
 799         struct bch_dev *ca;
 800         u64 start_time = local_clock();
 801         unsigned i, iter = 0;
 802         int ret;
 803
 804         lockdep_assert_held(&c->state_lock);
 805         trace_gc_start(c);
 806
 807         down_write(&c->gc_lock);
 808
 809         /* flush interior btree updates: */
 810         closure_wait_event(&c->btree_interior_update_wait,
 811                            !bch2_btree_interior_updates_nr_pending(c));
 812 again:
 813         ret = bch2_gc_start(c, metadata_only);
 814         if (ret)
 815                 goto out;
 816
 817         bch2_mark_superblocks(c);
 818
 819         ret = bch2_gc_btrees(c, journal_keys, initial, metadata_only);
 820         if (ret)
 821                 goto out;
 822
 823 #if 0
 824         bch2_mark_pending_btree_node_frees(c);
 825 #endif
 826         bch2_mark_allocator_buckets(c);
 827
 828         c->gc_count++;
 829 out:
 830         if (!ret &&
 831             (test_bit(BCH_FS_FIXED_GENS, &c->flags) ||
 832              (!iter && test_restart_gc(c)))) {
 833                 /*
 834                  * XXX: make sure gens we fixed got saved
 835                  */
 836                 if (iter++ <= 2) {
 837                         bch_info(c, "Fixed gens, restarting mark and sweep:");
 838                         clear_bit(BCH_FS_FIXED_GENS, &c->flags);
 839                         __gc_pos_set(c, gc_phase(GC_PHASE_NOT_RUNNING));
 840
 841                         percpu_down_write(&c->mark_lock);
 842                         bch2_gc_free(c);
 843                         percpu_up_write(&c->mark_lock);
 844                         /* flush fsck errors, reset counters */
 845                         bch2_flush_fsck_errs(c);
 846
 847                         goto again;
 848                 }
 849
 850                 bch_info(c, "Unable to fix bucket gens, looping");
 851                 ret = -EINVAL;
 852         }
 853
 854         if (!ret) {
 855                 bch2_journal_block(&c->journal);
 856
 857                 percpu_down_write(&c->mark_lock);
 858                 ret = bch2_gc_done(c, initial, metadata_only);
 859
 860                 bch2_journal_unblock(&c->journal);
 861         } else {
 862                 percpu_down_write(&c->mark_lock);
 863         }
 864
 865         /* Indicates that gc is no longer in progress: */
 866         __gc_pos_set(c, gc_phase(GC_PHASE_NOT_RUNNING));
 867
 868         bch2_gc_free(c);
 869         percpu_up_write(&c->mark_lock);
 870
 871         up_write(&c->gc_lock);
 872
 873         trace_gc_end(c);
 874         bch2_time_stats_update(&c->times[BCH_TIME_btree_gc], start_time);
 875
 876         /*
 877          * Wake up allocator in case it was waiting for buckets
 878          * because of not being able to inc gens
 879          */
 880         for_each_member_device(ca, c, i)
 881                 bch2_wake_allocator(ca);
 882
 883         /*
 884          * At startup, allocations can happen directly instead of via the
 885          * allocator thread - issue wakeup in case they blocked on gc_lock:
 886          */
 887         closure_wake_up(&c->freelist_wait);
 888         return ret;
 889 }
 890
 891 /*
 892  * For recalculating oldest gen, we only need to walk keys in leaf nodes; btree
 893  * node pointers currently never have cached pointers that can become stale:
 894  */
 895 static int bch2_gc_btree_gens(struct bch_fs *c, enum btree_id id)
 896 {
 897         struct btree_trans trans;
 898         struct btree_iter *iter;
 899         struct bkey_s_c k;
 900         int ret;
 901
 902         bch2_trans_init(&trans, c, 0, 0);
 903
 904         for_each_btree_key(&trans, iter, id, POS_MIN, BTREE_ITER_PREFETCH, k, ret) {
 905                 struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
 906                 const struct bch_extent_ptr *ptr;
 907
 908                 percpu_down_read(&c->mark_lock);
 909                 bkey_for_each_ptr(ptrs, ptr) {
 910                         struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
 911                         struct bucket *g = PTR_BUCKET(ca, ptr, false);
 912
 913                         if (gen_after(g->gc_gen, ptr->gen))
 914                                 g->gc_gen = ptr->gen;
 915
 916                         if (gen_after(g->mark.gen, ptr->gen) > 32) {
 917                                 /* rewrite btree node */
 918
 919                         }
 920                 }
 921                 percpu_up_read(&c->mark_lock);
 922         }
 923
 924         bch2_trans_exit(&trans);
 925         return ret;
 926 }
 927
 928 int bch2_gc_gens(struct bch_fs *c)
 929 {
 930         struct bch_dev *ca;
 931         struct bucket_array *buckets;
 932         struct bucket *g;
 933         unsigned i;
 934         int ret;
 935
 936         /*
 937          * Ideally we would be using state_lock and not gc_lock here, but that
 938          * introduces a deadlock in the RO path - we currently take the state
 939          * lock at the start of going RO, thus the gc thread may get stuck:
 940          */
 941         down_read(&c->gc_lock);
 942
 943         for_each_member_device(ca, c, i) {
 944                 down_read(&ca->bucket_lock);
 945                 buckets = bucket_array(ca);
 946
 947                 for_each_bucket(g, buckets)
 948                         g->gc_gen = g->mark.gen;
 949                 up_read(&ca->bucket_lock);
 950         }
 951
 952         for (i = 0; i < BTREE_ID_NR; i++)
 953                 if (btree_node_type_needs_gc(i)) {
 954                         ret = bch2_gc_btree_gens(c, i);
 955                         if (ret) {
 956                                 bch_err(c, "error recalculating oldest_gen: %i", ret);
 957                                 goto err;
 958                         }
 959                 }
 960
 961         for_each_member_device(ca, c, i) {
 962                 down_read(&ca->bucket_lock);
 963                 buckets = bucket_array(ca);
 964
 965                 for_each_bucket(g, buckets)
 966                         g->oldest_gen = g->gc_gen;
 967                 up_read(&ca->bucket_lock);
 968         }
 969
 970         c->gc_count++;
 971 err:
 972         up_read(&c->gc_lock);
 973         return ret;
 974 }
 975
 976 /* Btree coalescing */
 977
 978 static void recalc_packed_keys(struct btree *b)
 979 {
 980         struct bset *i = btree_bset_first(b);
 981         struct bkey_packed *k;
 982
 983         memset(&b->nr, 0, sizeof(b->nr));
 984
 985         BUG_ON(b->nsets != 1);
 986
 987         vstruct_for_each(i, k)
 988                 btree_keys_account_key_add(&b->nr, 0, k);
 989 }
 990
 991 static void bch2_coalesce_nodes(struct bch_fs *c, struct btree_iter *iter,
 992                                 struct btree *old_nodes[GC_MERGE_NODES])
 993 {
 994         struct btree *parent = btree_node_parent(iter, old_nodes[0]);
 995         unsigned i, nr_old_nodes, nr_new_nodes, u64s = 0;
 996         unsigned blocks = btree_blocks(c) * 2 / 3;
 997         struct btree *new_nodes[GC_MERGE_NODES];
 998         struct btree_update *as;
 999         struct keylist keylist;
1000         struct bkey_format_state format_state;
1001         struct bkey_format new_format;
1002
1003         memset(new_nodes, 0, sizeof(new_nodes));
1004         bch2_keylist_init(&keylist, NULL);
1005
1006         /* Count keys that are not deleted */
1007         for (i = 0; i < GC_MERGE_NODES && old_nodes[i]; i++)
1008                 u64s += old_nodes[i]->nr.live_u64s;
1009
1010         nr_old_nodes = nr_new_nodes = i;
1011
1012         /* Check if all keys in @old_nodes could fit in one fewer node */
1013         if (nr_old_nodes <= 1 ||
1014             __vstruct_blocks(struct btree_node, c->block_bits,
1015                              DIV_ROUND_UP(u64s, nr_old_nodes - 1)) > blocks)
1016                 return;
1017
1018         /* Find a format that all keys in @old_nodes can pack into */
1019         bch2_bkey_format_init(&format_state);
1020
1021         for (i = 0; i < nr_old_nodes; i++)
1022                 __bch2_btree_calc_format(&format_state, old_nodes[i]);
1023
1024         new_format = bch2_bkey_format_done(&format_state);
1025
1026         /* Check if repacking would make any nodes too big to fit */
1027         for (i = 0; i < nr_old_nodes; i++)
1028                 if (!bch2_btree_node_format_fits(c, old_nodes[i], &new_format)) {
1029                         trace_btree_gc_coalesce_fail(c,
1030                                         BTREE_GC_COALESCE_FAIL_FORMAT_FITS);
1031                         return;
1032                 }
1033
1034         if (bch2_keylist_realloc(&keylist, NULL, 0,
1035                         (BKEY_U64s + BKEY_EXTENT_U64s_MAX) * nr_old_nodes)) {
1036                 trace_btree_gc_coalesce_fail(c,
1037                                 BTREE_GC_COALESCE_FAIL_KEYLIST_REALLOC);
1038                 return;
1039         }
1040
1041         as = bch2_btree_update_start(iter->trans, iter->btree_id,
1042                         btree_update_reserve_required(c, parent) + nr_old_nodes,
1043                         BTREE_INSERT_NOFAIL|
1044                         BTREE_INSERT_USE_RESERVE,
1045                         NULL);
1046         if (IS_ERR(as)) {
1047                 trace_btree_gc_coalesce_fail(c,
1048                                 BTREE_GC_COALESCE_FAIL_RESERVE_GET);
1049                 bch2_keylist_free(&keylist, NULL);
1050                 return;
1051         }
1052
1053         trace_btree_gc_coalesce(c, old_nodes[0]);
1054
1055         for (i = 0; i < nr_old_nodes; i++)
1056                 bch2_btree_interior_update_will_free_node(as, old_nodes[i]);
1057
1058         /* Repack everything with @new_format and sort down to one bset */
1059         for (i = 0; i < nr_old_nodes; i++)
1060                 new_nodes[i] =
1061                         __bch2_btree_node_alloc_replacement(as, old_nodes[i],
1062                                                             new_format);
1063
1064         /*
1065          * Conceptually we concatenate the nodes together and slice them
1066          * up at different boundaries.
1067          */
1068         for (i = nr_new_nodes - 1; i > 0; --i) {
1069                 struct btree *n1 = new_nodes[i];
1070                 struct btree *n2 = new_nodes[i - 1];
1071
1072                 struct bset *s1 = btree_bset_first(n1);
1073                 struct bset *s2 = btree_bset_first(n2);
1074                 struct bkey_packed *k, *last = NULL;
1075
1076                 /* Calculate how many keys from @n2 we could fit inside @n1 */
1077                 u64s = 0;
1078
1079                 for (k = s2->start;
1080                      k < vstruct_last(s2) &&
1081                      vstruct_blocks_plus(n1->data, c->block_bits,
1082                                          u64s + k->u64s) <= blocks;
1083                      k = bkey_next_skip_noops(k, vstruct_last(s2))) {
1084                         last = k;
1085                         u64s += k->u64s;
1086                 }
1087
1088                 if (u64s == le16_to_cpu(s2->u64s)) {
1089                         /* n2 fits entirely in n1 */
1090                         n1->key.k.p = n1->data->max_key = n2->data->max_key;
1091
1092                         memcpy_u64s(vstruct_last(s1),
1093                                     s2->start,
1094                                     le16_to_cpu(s2->u64s));
1095                         le16_add_cpu(&s1->u64s, le16_to_cpu(s2->u64s));
1096
1097                         set_btree_bset_end(n1, n1->set);
1098
1099                         six_unlock_write(&n2->c.lock);
1100                         bch2_btree_node_free_never_inserted(c, n2);
1101                         six_unlock_intent(&n2->c.lock);
1102
1103                         memmove(new_nodes + i - 1,
1104                                 new_nodes + i,
1105                                 sizeof(new_nodes[0]) * (nr_new_nodes - i));
1106                         new_nodes[--nr_new_nodes] = NULL;
1107                 } else if (u64s) {
1108                         /* move part of n2 into n1 */
1109                         n1->key.k.p = n1->data->max_key =
1110                                 bkey_unpack_pos(n1, last);
1111
1112                         n2->data->min_key = bkey_successor(n1->data->max_key);
1113
1114                         memcpy_u64s(vstruct_last(s1),
1115                                     s2->start, u64s);
1116                         le16_add_cpu(&s1->u64s, u64s);
1117
1118                         memmove(s2->start,
1119                                 vstruct_idx(s2, u64s),
1120                                 (le16_to_cpu(s2->u64s) - u64s) * sizeof(u64));
1121                         s2->u64s = cpu_to_le16(le16_to_cpu(s2->u64s) - u64s);
1122
1123                         set_btree_bset_end(n1, n1->set);
1124                         set_btree_bset_end(n2, n2->set);
1125                 }
1126         }
1127
1128         for (i = 0; i < nr_new_nodes; i++) {
1129                 struct btree *n = new_nodes[i];
1130
1131                 recalc_packed_keys(n);
1132                 btree_node_reset_sib_u64s(n);
1133
1134                 bch2_btree_build_aux_trees(n);
1135
1136                 bch2_btree_update_add_new_node(as, n);
1137                 six_unlock_write(&n->c.lock);
1138
1139                 bch2_btree_node_write(c, n, SIX_LOCK_intent);
1140         }
1141
1142         /*
1143          * The keys for the old nodes get deleted. We don't want to insert keys
1144          * that compare equal to the keys for the new nodes we'll also be
1145          * inserting - we can't because keys on a keylist must be strictly
1146          * greater than the previous keys, and we also don't need to since the
1147          * key for the new node will serve the same purpose (overwriting the key
1148          * for the old node).
1149          */
1150         for (i = 0; i < nr_old_nodes; i++) {
1151                 struct bkey_i delete;
1152                 unsigned j;
1153
1154                 for (j = 0; j < nr_new_nodes; j++)
1155                         if (!bkey_cmp(old_nodes[i]->key.k.p,
1156                                       new_nodes[j]->key.k.p))
1157                                 goto next;
1158
1159                 bkey_init(&delete.k);
1160                 delete.k.p = old_nodes[i]->key.k.p;
1161                 bch2_keylist_add_in_order(&keylist, &delete);
1162 next:
1163                 i = i;
1164         }
1165
1166         /*
1167          * Keys for the new nodes get inserted: bch2_btree_insert_keys() only
1168          * does the lookup once and thus expects the keys to be in sorted order
1169          * so we have to make sure the new keys are correctly ordered with
1170          * respect to the deleted keys added in the previous loop
1171          */
1172         for (i = 0; i < nr_new_nodes; i++)
1173                 bch2_keylist_add_in_order(&keylist, &new_nodes[i]->key);
1174
1175         /* Insert the newly coalesced nodes */
1176         bch2_btree_insert_node(as, parent, iter, &keylist, 0);
1177
1178         BUG_ON(!bch2_keylist_empty(&keylist));
1179
1180         BUG_ON(iter->l[old_nodes[0]->c.level].b != old_nodes[0]);
1181
1182         bch2_btree_iter_node_replace(iter, new_nodes[0]);
1183
1184         for (i = 0; i < nr_new_nodes; i++)
1185                 bch2_btree_update_get_open_buckets(as, new_nodes[i]);
1186
1187         /* Free the old nodes and update our sliding window */
1188         for (i = 0; i < nr_old_nodes; i++) {
1189                 bch2_btree_node_free_inmem(c, old_nodes[i], iter);
1190
1191                 /*
1192                  * the index update might have triggered a split, in which case
1193                  * the nodes we coalesced - the new nodes we just created -
1194                  * might not be sibling nodes anymore - don't add them to the
1195                  * sliding window (except the first):
1196                  */
1197                 if (!i) {
1198                         old_nodes[i] = new_nodes[i];
1199                 } else {
1200                         old_nodes[i] = NULL;
1201                 }
1202         }
1203
1204         for (i = 0; i < nr_new_nodes; i++)
1205                 six_unlock_intent(&new_nodes[i]->c.lock);
1206
1207         bch2_btree_update_done(as);
1208         bch2_keylist_free(&keylist, NULL);
1209 }
1210
1211 static int bch2_coalesce_btree(struct bch_fs *c, enum btree_id btree_id)
1212 {
1213         struct btree_trans trans;
1214         struct btree_iter *iter;
1215         struct btree *b;
1216         bool kthread = (current->flags & PF_KTHREAD) != 0;
1217         unsigned i;
1218
1219         /* Sliding window of adjacent btree nodes */
1220         struct btree *merge[GC_MERGE_NODES];
1221         u32 lock_seq[GC_MERGE_NODES];
1222
1223         bch2_trans_init(&trans, c, 0, 0);
1224
1225         /*
1226          * XXX: We don't have a good way of positively matching on sibling nodes
1227          * that have the same parent - this code works by handling the cases
1228          * where they might not have the same parent, and is thus fragile. Ugh.
1229          *
1230          * Perhaps redo this to use multiple linked iterators?
1231          */
1232         memset(merge, 0, sizeof(merge));
1233
1234         __for_each_btree_node(&trans, iter, btree_id, POS_MIN,
1235                               BTREE_MAX_DEPTH, 0,
1236                               BTREE_ITER_PREFETCH, b) {
1237                 memmove(merge + 1, merge,
1238                         sizeof(merge) - sizeof(merge[0]));
1239                 memmove(lock_seq + 1, lock_seq,
1240                         sizeof(lock_seq) - sizeof(lock_seq[0]));
1241
1242                 merge[0] = b;
1243
1244                 for (i = 1; i < GC_MERGE_NODES; i++) {
1245                         if (!merge[i] ||
1246                             !six_relock_intent(&merge[i]->c.lock, lock_seq[i]))
1247                                 break;
1248
1249                         if (merge[i]->c.level != merge[0]->c.level) {
1250                                 six_unlock_intent(&merge[i]->c.lock);
1251                                 break;
1252                         }
1253                 }
1254                 memset(merge + i, 0, (GC_MERGE_NODES - i) * sizeof(merge[0]));
1255
1256                 bch2_coalesce_nodes(c, iter, merge);
1257
1258                 for (i = 1; i < GC_MERGE_NODES && merge[i]; i++) {
1259                         lock_seq[i] = merge[i]->c.lock.state.seq;
1260                         six_unlock_intent(&merge[i]->c.lock);
1261                 }
1262
1263                 lock_seq[0] = merge[0]->c.lock.state.seq;
1264
1265                 if (kthread && kthread_should_stop()) {
1266                         bch2_trans_exit(&trans);
1267                         return -ESHUTDOWN;
1268                 }
1269
1270                 bch2_trans_cond_resched(&trans);
1271
1272                 /*
1273                  * If the parent node wasn't relocked, it might have been split
1274                  * and the nodes in our sliding window might not have the same
1275                  * parent anymore - blow away the sliding window:
1276                  */
1277                 if (btree_iter_node(iter, iter->level + 1) &&
1278                     !btree_node_intent_locked(iter, iter->level + 1))
1279                         memset(merge + 1, 0,
1280                                (GC_MERGE_NODES - 1) * sizeof(merge[0]));
1281         }
1282         return bch2_trans_exit(&trans);
1283 }
1284
1285 /**
1286  * bch_coalesce - coalesce adjacent nodes with low occupancy
1287  */
1288 void bch2_coalesce(struct bch_fs *c)
1289 {
1290         enum btree_id id;
1291
1292         down_read(&c->gc_lock);
1293         trace_gc_coalesce_start(c);
1294
1295         for (id = 0; id < BTREE_ID_NR; id++) {
1296                 int ret = c->btree_roots[id].b
1297                         ? bch2_coalesce_btree(c, id)
1298                         : 0;
1299
1300                 if (ret) {
1301                         if (ret != -ESHUTDOWN)
1302                                 bch_err(c, "btree coalescing failed: %d", ret);
1303                         return;
1304                 }
1305         }
1306
1307         trace_gc_coalesce_end(c);
1308         up_read(&c->gc_lock);
1309 }
1310
1311 static int bch2_gc_thread(void *arg)
1312 {
1313         struct bch_fs *c = arg;
1314         struct io_clock *clock = &c->io_clock[WRITE];
1315         unsigned long last = atomic_long_read(&clock->now);
1316         unsigned last_kick = atomic_read(&c->kick_gc);
1317         int ret;
1318
1319         set_freezable();
1320
1321         while (1) {
1322                 while (1) {
1323                         set_current_state(TASK_INTERRUPTIBLE);
1324
1325                         if (kthread_should_stop()) {
1326                                 __set_current_state(TASK_RUNNING);
1327                                 return 0;
1328                         }
1329
1330                         if (atomic_read(&c->kick_gc) != last_kick)
1331                                 break;
1332
1333                         if (c->btree_gc_periodic) {
1334                                 unsigned long next = last + c->capacity / 16;
1335
1336                                 if (atomic_long_read(&clock->now) >= next)
1337                                         break;
1338
1339                                 bch2_io_clock_schedule_timeout(clock, next);
1340                         } else {
1341                                 schedule();
1342                         }
1343
1344                         try_to_freeze();
1345                 }
1346                 __set_current_state(TASK_RUNNING);
1347
1348                 last = atomic_long_read(&clock->now);
1349                 last_kick = atomic_read(&c->kick_gc);
1350
1351                 /*
1352                  * Full gc is currently incompatible with btree key cache:
1353                  */
1354 #if 0
1355                 ret = bch2_gc(c, NULL, false, false);
1356 #else
1357                 ret = bch2_gc_gens(c);
1358 #endif
1359                 if (ret)
1360                         bch_err(c, "btree gc failed: %i", ret);
1361
1362                 debug_check_no_locks_held();
1363         }
1364
1365         return 0;
1366 }
1367
1368 void bch2_gc_thread_stop(struct bch_fs *c)
1369 {
1370         struct task_struct *p;
1371
1372         p = c->gc_thread;
1373         c->gc_thread = NULL;
1374
1375         if (p) {
1376                 kthread_stop(p);
1377                 put_task_struct(p);
1378         }
1379 }
1380
1381 int bch2_gc_thread_start(struct bch_fs *c)
1382 {
1383         struct task_struct *p;
1384
1385         BUG_ON(c->gc_thread);
1386
1387         p = kthread_create(bch2_gc_thread, c, "bch_gc");
1388         if (IS_ERR(p))
1389                 return PTR_ERR(p);
1390
1391         get_task_struct(p);
1392         c->gc_thread = p;
1393         wake_up_process(p);
1394         return 0;
1395 }