drivers/md/bcache/btree.c

   1 /*
   2  * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
   3  *
   4  * Uses a block device as cache for other block devices; optimized for SSDs.
   5  * All allocation is done in buckets, which should match the erase block size
   6  * of the device.
   7  *
   8  * Buckets containing cached data are kept on a heap sorted by priority;
   9  * bucket priority is increased on cache hit, and periodically all the buckets
  10  * on the heap have their priority scaled down. This currently is just used as
  11  * an LRU but in the future should allow for more intelligent heuristics.
  12  *
  13  * Buckets have an 8 bit counter; freeing is accomplished by incrementing the
  14  * counter. Garbage collection is used to remove stale pointers.
  15  *
  16  * Indexing is done via a btree; nodes are not necessarily fully sorted, rather
  17  * as keys are inserted we only sort the pages that have not yet been written.
  18  * When garbage collection is run, we resort the entire node.
  19  *
  20  * All configuration is done via sysfs; see Documentation/bcache.txt.
  21  */
  22
  23 #include "bcache.h"
  24 #include "btree.h"
  25 #include "debug.h"
  26 #include "extents.h"
  27
  28 #include <linux/slab.h>
  29 #include <linux/bitops.h>
  30 #include <linux/hash.h>
  31 #include <linux/kthread.h>
  32 #include <linux/prefetch.h>
  33 #include <linux/random.h>
  34 #include <linux/rcupdate.h>
  35 #include <trace/events/bcache.h>
  36
  37 /*
  38  * Todo:
  39  * register_bcache: Return errors out to userspace correctly
  40  *
  41  * Writeback: don't undirty key until after a cache flush
  42  *
  43  * Create an iterator for key pointers
  44  *
  45  * On btree write error, mark bucket such that it won't be freed from the cache
  46  *
  47  * Journalling:
  48  *   Check for bad keys in replay
  49  *   Propagate barriers
  50  *   Refcount journal entries in journal_replay
  51  *
  52  * Garbage collection:
  53  *   Finish incremental gc
  54  *   Gc should free old UUIDs, data for invalid UUIDs
  55  *
  56  * Provide a way to list backing device UUIDs we have data cached for, and
  57  * probably how long it's been since we've seen them, and a way to invalidate
  58  * dirty data for devices that will never be attached again
  59  *
  60  * Keep 1 min/5 min/15 min statistics of how busy a block device has been, so
  61  * that based on that and how much dirty data we have we can keep writeback
  62  * from being starved
  63  *
  64  * Add a tracepoint or somesuch to watch for writeback starvation
  65  *
  66  * When btree depth > 1 and splitting an interior node, we have to make sure
  67  * alloc_bucket() cannot fail. This should be true but is not completely
  68  * obvious.
  69  *
  70  * Plugging?
  71  *
  72  * If data write is less than hard sector size of ssd, round up offset in open
  73  * bucket to the next whole sector
  74  *
  75  * Superblock needs to be fleshed out for multiple cache devices
  76  *
  77  * Add a sysfs tunable for the number of writeback IOs in flight
  78  *
  79  * Add a sysfs tunable for the number of open data buckets
  80  *
  81  * IO tracking: Can we track when one process is doing io on behalf of another?
  82  * IO tracking: Don't use just an average, weigh more recent stuff higher
  83  *
  84  * Test module load/unload
  85  */
  86
  87 #define MAX_NEED_GC             64
  88 #define MAX_SAVE_PRIO           72
  89
  90 #define PTR_DIRTY_BIT           (((uint64_t) 1 << 36))
  91
  92 #define PTR_HASH(c, k)                                                  \
  93         (((k)->ptr[0] >> c->bucket_bits) | PTR_GEN(k, 0))
  94
  95 #define insert_lock(s, b)       ((b)->level <= (s)->lock)
  96
  97 /*
  98  * These macros are for recursing down the btree - they handle the details of
  99  * locking and looking up nodes in the cache for you. They're best treated as
 100  * mere syntax when reading code that uses them.
 101  *
 102  * op->lock determines whether we take a read or a write lock at a given depth.
 103  * If you've got a read lock and find that you need a write lock (i.e. you're
 104  * going to have to split), set op->lock and return -EINTR; btree_root() will
 105  * call you again and you'll have the correct lock.
 106  */
 107
 108 /**
 109  * btree - recurse down the btree on a specified key
 110  * @fn:         function to call, which will be passed the child node
 111  * @key:        key to recurse on
 112  * @b:          parent btree node
 113  * @op:         pointer to struct btree_op
 114  */
 115 #define btree(fn, key, b, op, ...)                                      \
 116 ({                                                                      \
 117         int _r, l = (b)->level - 1;                                     \
 118         bool _w = l <= (op)->lock;                                      \
 119         struct btree *_child = bch_btree_node_get((b)->c, op, key, l,   \
 120                                                   _w, b);               \
 121         if (!IS_ERR(_child)) {                                          \
 122                 _r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__);       \
 123                 rw_unlock(_w, _child);                                  \
 124         } else                                                          \
 125                 _r = PTR_ERR(_child);                                   \
 126         _r;                                                             \
 127 })
 128
 129 /**
 130  * btree_root - call a function on the root of the btree
 131  * @fn:         function to call, which will be passed the child node
 132  * @c:          cache set
 133  * @op:         pointer to struct btree_op
 134  */
 135 #define btree_root(fn, c, op, ...)                                      \
 136 ({                                                                      \
 137         int _r = -EINTR;                                                \
 138         do {                                                            \
 139                 struct btree *_b = (c)->root;                           \
 140                 bool _w = insert_lock(op, _b);                          \
 141                 rw_lock(_w, _b, _b->level);                             \
 142                 if (_b == (c)->root &&                                  \
 143                     _w == insert_lock(op, _b)) {                        \
 144                         _r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__);   \
 145                 }                                                       \
 146                 rw_unlock(_w, _b);                                      \
 147                 bch_cannibalize_unlock(c);                              \
 148                 if (_r == -EINTR)                                       \
 149                         schedule();                                     \
 150         } while (_r == -EINTR);                                         \
 151                                                                         \
 152         finish_wait(&(c)->btree_cache_wait, &(op)->wait);               \
 153         _r;                                                             \
 154 })
 155
 156 static inline struct bset *write_block(struct btree *b)
 157 {
 158         return ((void *) btree_bset_first(b)) + b->written * block_bytes(b->c);
 159 }
 160
 161 static void bch_btree_init_next(struct btree *b)
 162 {
 163         /* If not a leaf node, always sort */
 164         if (b->level && b->keys.nsets)
 165                 bch_btree_sort(&b->keys, &b->c->sort);
 166         else
 167                 bch_btree_sort_lazy(&b->keys, &b->c->sort);
 168
 169         if (b->written < btree_blocks(b))
 170                 bch_bset_init_next(&b->keys, write_block(b),
 171                                    bset_magic(&b->c->sb));
 172
 173 }
 174
 175 /* Btree key manipulation */
 176
 177 void bkey_put(struct cache_set *c, struct bkey *k)
 178 {
 179         unsigned i;
 180
 181         for (i = 0; i < KEY_PTRS(k); i++)
 182                 if (ptr_available(c, k, i))
 183                         atomic_dec_bug(&PTR_BUCKET(c, k, i)->pin);
 184 }
 185
 186 /* Btree IO */
 187
 188 static uint64_t btree_csum_set(struct btree *b, struct bset *i)
 189 {
 190         uint64_t crc = b->key.ptr[0];
 191         void *data = (void *) i + 8, *end = bset_bkey_last(i);
 192
 193         crc = bch_crc64_update(crc, data, end - data);
 194         return crc ^ 0xffffffffffffffffULL;
 195 }
 196
 197 void bch_btree_node_read_done(struct btree *b)
 198 {
 199         const char *err = "bad btree header";
 200         struct bset *i = btree_bset_first(b);
 201         struct btree_iter *iter;
 202
 203         iter = mempool_alloc(b->c->fill_iter, GFP_NOIO);
 204         iter->size = b->c->sb.bucket_size / b->c->sb.block_size;
 205         iter->used = 0;
 206
 207 #ifdef CONFIG_BCACHE_DEBUG
 208         iter->b = &b->keys;
 209 #endif
 210
 211         if (!i->seq)
 212                 goto err;
 213
 214         for (;
 215              b->written < btree_blocks(b) && i->seq == b->keys.set[0].data->seq;
 216              i = write_block(b)) {
 217                 err = "unsupported bset version";
 218                 if (i->version > BCACHE_BSET_VERSION)
 219                         goto err;
 220
 221                 err = "bad btree header";
 222                 if (b->written + set_blocks(i, block_bytes(b->c)) >
 223                     btree_blocks(b))
 224                         goto err;
 225
 226                 err = "bad magic";
 227                 if (i->magic != bset_magic(&b->c->sb))
 228                         goto err;
 229
 230                 err = "bad checksum";
 231                 switch (i->version) {
 232                 case 0:
 233                         if (i->csum != csum_set(i))
 234                                 goto err;
 235                         break;
 236                 case BCACHE_BSET_VERSION:
 237                         if (i->csum != btree_csum_set(b, i))
 238                                 goto err;
 239                         break;
 240                 }
 241
 242                 err = "empty set";
 243                 if (i != b->keys.set[0].data && !i->keys)
 244                         goto err;
 245
 246                 bch_btree_iter_push(iter, i->start, bset_bkey_last(i));
 247
 248                 b->written += set_blocks(i, block_bytes(b->c));
 249         }
 250
 251         err = "corrupted btree";
 252         for (i = write_block(b);
 253              bset_sector_offset(&b->keys, i) < KEY_SIZE(&b->key);
 254              i = ((void *) i) + block_bytes(b->c))
 255                 if (i->seq == b->keys.set[0].data->seq)
 256                         goto err;
 257
 258         bch_btree_sort_and_fix_extents(&b->keys, iter, &b->c->sort);
 259
 260         i = b->keys.set[0].data;
 261         err = "short btree key";
 262         if (b->keys.set[0].size &&
 263             bkey_cmp(&b->key, &b->keys.set[0].end) < 0)
 264                 goto err;
 265
 266         if (b->written < btree_blocks(b))
 267                 bch_bset_init_next(&b->keys, write_block(b),
 268                                    bset_magic(&b->c->sb));
 269 out:
 270         mempool_free(iter, b->c->fill_iter);
 271         return;
 272 err:
 273         set_btree_node_io_error(b);
 274         bch_cache_set_error(b->c, "%s at bucket %zu, block %u, %u keys",
 275                             err, PTR_BUCKET_NR(b->c, &b->key, 0),
 276                             bset_block_offset(b, i), i->keys);
 277         goto out;
 278 }
 279
 280 static void btree_node_read_endio(struct bio *bio)
 281 {
 282         struct closure *cl = bio->bi_private;
 283         closure_put(cl);
 284 }
 285
 286 static void bch_btree_node_read(struct btree *b)
 287 {
 288         uint64_t start_time = local_clock();
 289         struct closure cl;
 290         struct bio *bio;
 291
 292         trace_bcache_btree_read(b);
 293
 294         closure_init_stack(&cl);
 295
 296         bio = bch_bbio_alloc(b->c);
 297         bio->bi_iter.bi_size = KEY_SIZE(&b->key) << 9;
 298         bio->bi_end_io  = btree_node_read_endio;
 299         bio->bi_private = &cl;
 300         bio_set_op_attrs(bio, REQ_OP_READ, REQ_META|READ_SYNC);
 301
 302         bch_bio_map(bio, b->keys.set[0].data);
 303
 304         bch_submit_bbio(bio, b->c, &b->key, 0);
 305         closure_sync(&cl);
 306
 307         if (bio->bi_error)
 308                 set_btree_node_io_error(b);
 309
 310         bch_bbio_free(bio, b->c);
 311
 312         if (btree_node_io_error(b))
 313                 goto err;
 314
 315         bch_btree_node_read_done(b);
 316         bch_time_stats_update(&b->c->btree_read_time, start_time);
 317
 318         return;
 319 err:
 320         bch_cache_set_error(b->c, "io error reading bucket %zu",
 321                             PTR_BUCKET_NR(b->c, &b->key, 0));
 322 }
 323
 324 static void btree_complete_write(struct btree *b, struct btree_write *w)
 325 {
 326         if (w->prio_blocked &&
 327             !atomic_sub_return(w->prio_blocked, &b->c->prio_blocked))
 328                 wake_up_allocators(b->c);
 329
 330         if (w->journal) {
 331                 atomic_dec_bug(w->journal);
 332                 __closure_wake_up(&b->c->journal.wait);
 333         }
 334
 335         w->prio_blocked = 0;
 336         w->journal      = NULL;
 337 }
 338
 339 static void btree_node_write_unlock(struct closure *cl)
 340 {
 341         struct btree *b = container_of(cl, struct btree, io);
 342
 343         up(&b->io_mutex);
 344 }
 345
 346 static void __btree_node_write_done(struct closure *cl)
 347 {
 348         struct btree *b = container_of(cl, struct btree, io);
 349         struct btree_write *w = btree_prev_write(b);
 350
 351         bch_bbio_free(b->bio, b->c);
 352         b->bio = NULL;
 353         btree_complete_write(b, w);
 354
 355         if (btree_node_dirty(b))
 356                 schedule_delayed_work(&b->work, 30 * HZ);
 357
 358         closure_return_with_destructor(cl, btree_node_write_unlock);
 359 }
 360
 361 static void btree_node_write_done(struct closure *cl)
 362 {
 363         struct btree *b = container_of(cl, struct btree, io);
 364
 365         bio_free_pages(b->bio);
 366         __btree_node_write_done(cl);
 367 }
 368
 369 static void btree_node_write_endio(struct bio *bio)
 370 {
 371         struct closure *cl = bio->bi_private;
 372         struct btree *b = container_of(cl, struct btree, io);
 373
 374         if (bio->bi_error)
 375                 set_btree_node_io_error(b);
 376
 377         bch_bbio_count_io_errors(b->c, bio, bio->bi_error, "writing btree");
 378         closure_put(cl);
 379 }
 380
 381 static void do_btree_node_write(struct btree *b)
 382 {
 383         struct closure *cl = &b->io;
 384         struct bset *i = btree_bset_last(b);
 385         BKEY_PADDED(key) k;
 386
 387         i->version      = BCACHE_BSET_VERSION;
 388         i->csum         = btree_csum_set(b, i);
 389
 390         BUG_ON(b->bio);
 391         b->bio = bch_bbio_alloc(b->c);
 392
 393         b->bio->bi_end_io       = btree_node_write_endio;
 394         b->bio->bi_private      = cl;
 395         b->bio->bi_iter.bi_size = roundup(set_bytes(i), block_bytes(b->c));
 396         bio_set_op_attrs(b->bio, REQ_OP_WRITE, REQ_META|WRITE_SYNC|REQ_FUA);
 397         bch_bio_map(b->bio, i);
 398
 399         /*
 400          * If we're appending to a leaf node, we don't technically need FUA -
 401          * this write just needs to be persisted before the next journal write,
 402          * which will be marked FLUSH|FUA.
 403          *
 404          * Similarly if we're writing a new btree root - the pointer is going to
 405          * be in the next journal entry.
 406          *
 407          * But if we're writing a new btree node (that isn't a root) or
 408          * appending to a non leaf btree node, we need either FUA or a flush
 409          * when we write the parent with the new pointer. FUA is cheaper than a
 410          * flush, and writes appending to leaf nodes aren't blocking anything so
 411          * just make all btree node writes FUA to keep things sane.
 412          */
 413
 414         bkey_copy(&k.key, &b->key);
 415         SET_PTR_OFFSET(&k.key, 0, PTR_OFFSET(&k.key, 0) +
 416                        bset_sector_offset(&b->keys, i));
 417
 418         if (!bio_alloc_pages(b->bio, __GFP_NOWARN|GFP_NOWAIT)) {
 419                 int j;
 420                 struct bio_vec *bv;
 421                 void *base = (void *) ((unsigned long) i & ~(PAGE_SIZE - 1));
 422
 423                 bio_for_each_segment_all(bv, b->bio, j)
 424                         memcpy(page_address(bv->bv_page),
 425                                base + j * PAGE_SIZE, PAGE_SIZE);
 426
 427                 bch_submit_bbio(b->bio, b->c, &k.key, 0);
 428
 429                 continue_at(cl, btree_node_write_done, NULL);
 430         } else {
 431                 b->bio->bi_vcnt = 0;
 432                 bch_bio_map(b->bio, i);
 433
 434                 bch_submit_bbio(b->bio, b->c, &k.key, 0);
 435
 436                 closure_sync(cl);
 437                 continue_at_nobarrier(cl, __btree_node_write_done, NULL);
 438         }
 439 }
 440
 441 void __bch_btree_node_write(struct btree *b, struct closure *parent)
 442 {
 443         struct bset *i = btree_bset_last(b);
 444
 445         lockdep_assert_held(&b->write_lock);
 446
 447         trace_bcache_btree_write(b);
 448
 449         BUG_ON(current->bio_list);
 450         BUG_ON(b->written >= btree_blocks(b));
 451         BUG_ON(b->written && !i->keys);
 452         BUG_ON(btree_bset_first(b)->seq != i->seq);
 453         bch_check_keys(&b->keys, "writing");
 454
 455         cancel_delayed_work(&b->work);
 456
 457         /* If caller isn't waiting for write, parent refcount is cache set */
 458         down(&b->io_mutex);
 459         closure_init(&b->io, parent ?: &b->c->cl);
 460
 461         clear_bit(BTREE_NODE_dirty,      &b->flags);
 462         change_bit(BTREE_NODE_write_idx, &b->flags);
 463
 464         do_btree_node_write(b);
 465
 466         atomic_long_add(set_blocks(i, block_bytes(b->c)) * b->c->sb.block_size,
 467                         &PTR_CACHE(b->c, &b->key, 0)->btree_sectors_written);
 468
 469         b->written += set_blocks(i, block_bytes(b->c));
 470 }
 471
 472 void bch_btree_node_write(struct btree *b, struct closure *parent)
 473 {
 474         unsigned nsets = b->keys.nsets;
 475
 476         lockdep_assert_held(&b->lock);
 477
 478         __bch_btree_node_write(b, parent);
 479
 480         /*
 481          * do verify if there was more than one set initially (i.e. we did a
 482          * sort) and we sorted down to a single set:
 483          */
 484         if (nsets && !b->keys.nsets)
 485                 bch_btree_verify(b);
 486
 487         bch_btree_init_next(b);
 488 }
 489
 490 static void bch_btree_node_write_sync(struct btree *b)
 491 {
 492         struct closure cl;
 493
 494         closure_init_stack(&cl);
 495
 496         mutex_lock(&b->write_lock);
 497         bch_btree_node_write(b, &cl);
 498         mutex_unlock(&b->write_lock);
 499
 500         closure_sync(&cl);
 501 }
 502
 503 static void btree_node_write_work(struct work_struct *w)
 504 {
 505         struct btree *b = container_of(to_delayed_work(w), struct btree, work);
 506
 507         mutex_lock(&b->write_lock);
 508         if (btree_node_dirty(b))
 509                 __bch_btree_node_write(b, NULL);
 510         mutex_unlock(&b->write_lock);
 511 }
 512
 513 static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
 514 {
 515         struct bset *i = btree_bset_last(b);
 516         struct btree_write *w = btree_current_write(b);
 517
 518         lockdep_assert_held(&b->write_lock);
 519
 520         BUG_ON(!b->written);
 521         BUG_ON(!i->keys);
 522
 523         if (!btree_node_dirty(b))
 524                 schedule_delayed_work(&b->work, 30 * HZ);
 525
 526         set_btree_node_dirty(b);
 527
 528         if (journal_ref) {
 529                 if (w->journal &&
 530                     journal_pin_cmp(b->c, w->journal, journal_ref)) {
 531                         atomic_dec_bug(w->journal);
 532                         w->journal = NULL;
 533                 }
 534
 535                 if (!w->journal) {
 536                         w->journal = journal_ref;
 537                         atomic_inc(w->journal);
 538                 }
 539         }
 540
 541         /* Force write if set is too big */
 542         if (set_bytes(i) > PAGE_SIZE - 48 &&
 543             !current->bio_list)
 544                 bch_btree_node_write(b, NULL);
 545 }
 546
 547 /*
 548  * Btree in memory cache - allocation/freeing
 549  * mca -> memory cache
 550  */
 551
 552 #define mca_reserve(c)  (((c->root && c->root->level)           \
 553                           ? c->root->level : 1) * 8 + 16)
 554 #define mca_can_free(c)                                         \
 555         max_t(int, 0, c->btree_cache_used - mca_reserve(c))
 556
 557 static void mca_data_free(struct btree *b)
 558 {
 559         BUG_ON(b->io_mutex.count != 1);
 560
 561         bch_btree_keys_free(&b->keys);
 562
 563         b->c->btree_cache_used--;
 564         list_move(&b->list, &b->c->btree_cache_freed);
 565 }
 566
 567 static void mca_bucket_free(struct btree *b)
 568 {
 569         BUG_ON(btree_node_dirty(b));
 570
 571         b->key.ptr[0] = 0;
 572         hlist_del_init_rcu(&b->hash);
 573         list_move(&b->list, &b->c->btree_cache_freeable);
 574 }
 575
 576 static unsigned btree_order(struct bkey *k)
 577 {
 578         return ilog2(KEY_SIZE(k) / PAGE_SECTORS ?: 1);
 579 }
 580
 581 static void mca_data_alloc(struct btree *b, struct bkey *k, gfp_t gfp)
 582 {
 583         if (!bch_btree_keys_alloc(&b->keys,
 584                                   max_t(unsigned,
 585                                         ilog2(b->c->btree_pages),
 586                                         btree_order(k)),
 587                                   gfp)) {
 588                 b->c->btree_cache_used++;
 589                 list_move(&b->list, &b->c->btree_cache);
 590         } else {
 591                 list_move(&b->list, &b->c->btree_cache_freed);
 592         }
 593 }
 594
 595 static struct btree *mca_bucket_alloc(struct cache_set *c,
 596                                       struct bkey *k, gfp_t gfp)
 597 {
 598         struct btree *b = kzalloc(sizeof(struct btree), gfp);
 599         if (!b)
 600                 return NULL;
 601
 602         init_rwsem(&b->lock);
 603         lockdep_set_novalidate_class(&b->lock);
 604         mutex_init(&b->write_lock);
 605         lockdep_set_novalidate_class(&b->write_lock);
 606         INIT_LIST_HEAD(&b->list);
 607         INIT_DELAYED_WORK(&b->work, btree_node_write_work);
 608         b->c = c;
 609         sema_init(&b->io_mutex, 1);
 610
 611         mca_data_alloc(b, k, gfp);
 612         return b;
 613 }
 614
 615 static int mca_reap(struct btree *b, unsigned min_order, bool flush)
 616 {
 617         struct closure cl;
 618
 619         closure_init_stack(&cl);
 620         lockdep_assert_held(&b->c->bucket_lock);
 621
 622         if (!down_write_trylock(&b->lock))
 623                 return -ENOMEM;
 624
 625         BUG_ON(btree_node_dirty(b) && !b->keys.set[0].data);
 626
 627         if (b->keys.page_order < min_order)
 628                 goto out_unlock;
 629
 630         if (!flush) {
 631                 if (btree_node_dirty(b))
 632                         goto out_unlock;
 633
 634                 if (down_trylock(&b->io_mutex))
 635                         goto out_unlock;
 636                 up(&b->io_mutex);
 637         }
 638
 639         mutex_lock(&b->write_lock);
 640         if (btree_node_dirty(b))
 641                 __bch_btree_node_write(b, &cl);
 642         mutex_unlock(&b->write_lock);
 643
 644         closure_sync(&cl);
 645
 646         /* wait for any in flight btree write */
 647         down(&b->io_mutex);
 648         up(&b->io_mutex);
 649
 650         return 0;
 651 out_unlock:
 652         rw_unlock(true, b);
 653         return -ENOMEM;
 654 }
 655
 656 static unsigned long bch_mca_scan(struct shrinker *shrink,
 657                                   struct shrink_control *sc)
 658 {
 659         struct cache_set *c = container_of(shrink, struct cache_set, shrink);
 660         struct btree *b, *t;
 661         unsigned long i, nr = sc->nr_to_scan;
 662         unsigned long freed = 0;
 663
 664         if (c->shrinker_disabled)
 665                 return SHRINK_STOP;
 666
 667         if (c->btree_cache_alloc_lock)
 668                 return SHRINK_STOP;
 669
 670         /* Return -1 if we can't do anything right now */
 671         if (sc->gfp_mask & __GFP_IO)
 672                 mutex_lock(&c->bucket_lock);
 673         else if (!mutex_trylock(&c->bucket_lock))
 674                 return -1;
 675
 676         /*
 677          * It's _really_ critical that we don't free too many btree nodes - we
 678          * have to always leave ourselves a reserve. The reserve is how we
 679          * guarantee that allocating memory for a new btree node can always
 680          * succeed, so that inserting keys into the btree can always succeed and
 681          * IO can always make forward progress:
 682          */
 683         nr /= c->btree_pages;
 684         if (nr == 0)
 685                 nr = 1;
 686         nr = min_t(unsigned long, nr, mca_can_free(c));
 687
 688         i = 0;
 689         list_for_each_entry_safe(b, t, &c->btree_cache_freeable, list) {
 690                 if (freed >= nr)
 691                         break;
 692
 693                 if (++i > 3 &&
 694                     !mca_reap(b, 0, false)) {
 695                         mca_data_free(b);
 696                         rw_unlock(true, b);
 697                         freed++;
 698                 }
 699         }
 700
 701         for (i = 0; (nr--) && i < c->btree_cache_used; i++) {
 702                 if (list_empty(&c->btree_cache))
 703                         goto out;
 704
 705                 b = list_first_entry(&c->btree_cache, struct btree, list);
 706                 list_rotate_left(&c->btree_cache);
 707
 708                 if (!b->accessed &&
 709                     !mca_reap(b, 0, false)) {
 710                         mca_bucket_free(b);
 711                         mca_data_free(b);
 712                         rw_unlock(true, b);
 713                         freed++;
 714                 } else
 715                         b->accessed = 0;
 716         }
 717 out:
 718         mutex_unlock(&c->bucket_lock);
 719         return freed;
 720 }
 721
 722 static unsigned long bch_mca_count(struct shrinker *shrink,
 723                                    struct shrink_control *sc)
 724 {
 725         struct cache_set *c = container_of(shrink, struct cache_set, shrink);
 726
 727         if (c->shrinker_disabled)
 728                 return 0;
 729
 730         if (c->btree_cache_alloc_lock)
 731                 return 0;
 732
 733         return mca_can_free(c) * c->btree_pages;
 734 }
 735
 736 void bch_btree_cache_free(struct cache_set *c)
 737 {
 738         struct btree *b;
 739         struct closure cl;
 740         closure_init_stack(&cl);
 741
 742         if (c->shrink.list.next)
 743                 unregister_shrinker(&c->shrink);
 744
 745         mutex_lock(&c->bucket_lock);
 746
 747 #ifdef CONFIG_BCACHE_DEBUG
 748         if (c->verify_data)
 749                 list_move(&c->verify_data->list, &c->btree_cache);
 750
 751         free_pages((unsigned long) c->verify_ondisk, ilog2(bucket_pages(c)));
 752 #endif
 753
 754         list_splice(&c->btree_cache_freeable,
 755                     &c->btree_cache);
 756
 757         while (!list_empty(&c->btree_cache)) {
 758                 b = list_first_entry(&c->btree_cache, struct btree, list);
 759
 760                 if (btree_node_dirty(b))
 761                         btree_complete_write(b, btree_current_write(b));
 762                 clear_bit(BTREE_NODE_dirty, &b->flags);
 763
 764                 mca_data_free(b);
 765         }
 766
 767         while (!list_empty(&c->btree_cache_freed)) {
 768                 b = list_first_entry(&c->btree_cache_freed,
 769                                      struct btree, list);
 770                 list_del(&b->list);
 771                 cancel_delayed_work_sync(&b->work);
 772                 kfree(b);
 773         }
 774
 775         mutex_unlock(&c->bucket_lock);
 776 }
 777
 778 int bch_btree_cache_alloc(struct cache_set *c)
 779 {
 780         unsigned i;
 781
 782         for (i = 0; i < mca_reserve(c); i++)
 783                 if (!mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL))
 784                         return -ENOMEM;
 785
 786         list_splice_init(&c->btree_cache,
 787                          &c->btree_cache_freeable);
 788
 789 #ifdef CONFIG_BCACHE_DEBUG
 790         mutex_init(&c->verify_lock);
 791
 792         c->verify_ondisk = (void *)
 793                 __get_free_pages(GFP_KERNEL|__GFP_COMP, ilog2(bucket_pages(c)));
 794
 795         c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
 796
 797         if (c->verify_data &&
 798             c->verify_data->keys.set->data)
 799                 list_del_init(&c->verify_data->list);
 800         else
 801                 c->verify_data = NULL;
 802 #endif
 803
 804         c->shrink.count_objects = bch_mca_count;
 805         c->shrink.scan_objects = bch_mca_scan;
 806         c->shrink.seeks = 4;
 807         c->shrink.batch = c->btree_pages * 2;
 808
 809         if (register_shrinker(&c->shrink))
 810                 pr_warn("bcache: %s: could not register shrinker",
 811                                 __func__);
 812
 813         return 0;
 814 }
 815
 816 /* Btree in memory cache - hash table */
 817
 818 static struct hlist_head *mca_hash(struct cache_set *c, struct bkey *k)
 819 {
 820         return &c->bucket_hash[hash_32(PTR_HASH(c, k), BUCKET_HASH_BITS)];
 821 }
 822
 823 static struct btree *mca_find(struct cache_set *c, struct bkey *k)
 824 {
 825         struct btree *b;
 826
 827         rcu_read_lock();
 828         hlist_for_each_entry_rcu(b, mca_hash(c, k), hash)
 829                 if (PTR_HASH(c, &b->key) == PTR_HASH(c, k))
 830                         goto out;
 831         b = NULL;
 832 out:
 833         rcu_read_unlock();
 834         return b;
 835 }
 836
 837 static int mca_cannibalize_lock(struct cache_set *c, struct btree_op *op)
 838 {
 839         spin_lock(&c->btree_cannibalize_lock);
 840         if (likely(c->btree_cache_alloc_lock == NULL)) {
 841                 c->btree_cache_alloc_lock = current;
 842         } else if (c->btree_cache_alloc_lock != current) {
 843                 if (op)
 844                         prepare_to_wait(&c->btree_cache_wait, &op->wait,
 845                                         TASK_UNINTERRUPTIBLE);
 846                 spin_unlock(&c->btree_cannibalize_lock);
 847                 return -EINTR;
 848         }
 849         spin_unlock(&c->btree_cannibalize_lock);
 850
 851         return 0;
 852 }
 853
 854 static struct btree *mca_cannibalize(struct cache_set *c, struct btree_op *op,
 855                                      struct bkey *k)
 856 {
 857         struct btree *b;
 858
 859         trace_bcache_btree_cache_cannibalize(c);
 860
 861         if (mca_cannibalize_lock(c, op))
 862                 return ERR_PTR(-EINTR);
 863
 864         list_for_each_entry_reverse(b, &c->btree_cache, list)
 865                 if (!mca_reap(b, btree_order(k), false))
 866                         return b;
 867
 868         list_for_each_entry_reverse(b, &c->btree_cache, list)
 869                 if (!mca_reap(b, btree_order(k), true))
 870                         return b;
 871
 872         WARN(1, "btree cache cannibalize failed\n");
 873         return ERR_PTR(-ENOMEM);
 874 }
 875
 876 /*
 877  * We can only have one thread cannibalizing other cached btree nodes at a time,
 878  * or we'll deadlock. We use an open coded mutex to ensure that, which a
 879  * cannibalize_bucket() will take. This means every time we unlock the root of
 880  * the btree, we need to release this lock if we have it held.
 881  */
 882 static void bch_cannibalize_unlock(struct cache_set *c)
 883 {
 884         spin_lock(&c->btree_cannibalize_lock);
 885         if (c->btree_cache_alloc_lock == current) {
 886                 c->btree_cache_alloc_lock = NULL;
 887                 wake_up(&c->btree_cache_wait);
 888         }
 889         spin_unlock(&c->btree_cannibalize_lock);
 890 }
 891
 892 static struct btree *mca_alloc(struct cache_set *c, struct btree_op *op,
 893                                struct bkey *k, int level)
 894 {
 895         struct btree *b;
 896
 897         BUG_ON(current->bio_list);
 898
 899         lockdep_assert_held(&c->bucket_lock);
 900
 901         if (mca_find(c, k))
 902                 return NULL;
 903
 904         /* btree_free() doesn't free memory; it sticks the node on the end of
 905          * the list. Check if there's any freed nodes there:
 906          */
 907         list_for_each_entry(b, &c->btree_cache_freeable, list)
 908                 if (!mca_reap(b, btree_order(k), false))
 909                         goto out;
 910
 911         /* We never free struct btree itself, just the memory that holds the on
 912          * disk node. Check the freed list before allocating a new one:
 913          */
 914         list_for_each_entry(b, &c->btree_cache_freed, list)
 915                 if (!mca_reap(b, 0, false)) {
 916                         mca_data_alloc(b, k, __GFP_NOWARN|GFP_NOIO);
 917                         if (!b->keys.set[0].data)
 918                                 goto err;
 919                         else
 920                                 goto out;
 921                 }
 922
 923         b = mca_bucket_alloc(c, k, __GFP_NOWARN|GFP_NOIO);
 924         if (!b)
 925                 goto err;
 926
 927         BUG_ON(!down_write_trylock(&b->lock));
 928         if (!b->keys.set->data)
 929                 goto err;
 930 out:
 931         BUG_ON(b->io_mutex.count != 1);
 932
 933         bkey_copy(&b->key, k);
 934         list_move(&b->list, &c->btree_cache);
 935         hlist_del_init_rcu(&b->hash);
 936         hlist_add_head_rcu(&b->hash, mca_hash(c, k));
 937
 938         lock_set_subclass(&b->lock.dep_map, level + 1, _THIS_IP_);
 939         b->parent       = (void *) ~0UL;
 940         b->flags        = 0;
 941         b->written      = 0;
 942         b->level        = level;
 943
 944         if (!b->level)
 945                 bch_btree_keys_init(&b->keys, &bch_extent_keys_ops,
 946                                     &b->c->expensive_debug_checks);
 947         else
 948                 bch_btree_keys_init(&b->keys, &bch_btree_keys_ops,
 949                                     &b->c->expensive_debug_checks);
 950
 951         return b;
 952 err:
 953         if (b)
 954                 rw_unlock(true, b);
 955
 956         b = mca_cannibalize(c, op, k);
 957         if (!IS_ERR(b))
 958                 goto out;
 959
 960         return b;
 961 }
 962
 963 /**
 964  * bch_btree_node_get - find a btree node in the cache and lock it, reading it
 965  * in from disk if necessary.
 966  *
 967  * If IO is necessary and running under generic_make_request, returns -EAGAIN.
 968  *
 969  * The btree node will have either a read or a write lock held, depending on
 970  * level and op->lock.
 971  */
 972 struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op,
 973                                  struct bkey *k, int level, bool write,
 974                                  struct btree *parent)
 975 {
 976         int i = 0;
 977         struct btree *b;
 978
 979         BUG_ON(level < 0);
 980 retry:
 981         b = mca_find(c, k);
 982
 983         if (!b) {
 984                 if (current->bio_list)
 985                         return ERR_PTR(-EAGAIN);
 986
 987                 mutex_lock(&c->bucket_lock);
 988                 b = mca_alloc(c, op, k, level);
 989                 mutex_unlock(&c->bucket_lock);
 990
 991                 if (!b)
 992                         goto retry;
 993                 if (IS_ERR(b))
 994                         return b;
 995
 996                 bch_btree_node_read(b);
 997
 998                 if (!write)
 999                         downgrade_write(&b->lock);
1000         } else {
1001                 rw_lock(write, b, level);
1002                 if (PTR_HASH(c, &b->key) != PTR_HASH(c, k)) {
1003                         rw_unlock(write, b);
1004                         goto retry;
1005                 }
1006                 BUG_ON(b->level != level);
1007         }
1008
1009         b->parent = parent;
1010         b->accessed = 1;
1011
1012         for (; i <= b->keys.nsets && b->keys.set[i].size; i++) {
1013                 prefetch(b->keys.set[i].tree);
1014                 prefetch(b->keys.set[i].data);
1015         }
1016
1017         for (; i <= b->keys.nsets; i++)
1018                 prefetch(b->keys.set[i].data);
1019
1020         if (btree_node_io_error(b)) {
1021                 rw_unlock(write, b);
1022                 return ERR_PTR(-EIO);
1023         }
1024
1025         BUG_ON(!b->written);
1026
1027         return b;
1028 }
1029
1030 static void btree_node_prefetch(struct btree *parent, struct bkey *k)
1031 {
1032         struct btree *b;
1033
1034         mutex_lock(&parent->c->bucket_lock);
1035         b = mca_alloc(parent->c, NULL, k, parent->level - 1);
1036         mutex_unlock(&parent->c->bucket_lock);
1037
1038         if (!IS_ERR_OR_NULL(b)) {
1039                 b->parent = parent;
1040                 bch_btree_node_read(b);
1041                 rw_unlock(true, b);
1042         }
1043 }
1044
1045 /* Btree alloc */
1046
1047 static void btree_node_free(struct btree *b)
1048 {
1049         trace_bcache_btree_node_free(b);
1050
1051         BUG_ON(b == b->c->root);
1052
1053         mutex_lock(&b->write_lock);
1054
1055         if (btree_node_dirty(b))
1056                 btree_complete_write(b, btree_current_write(b));
1057         clear_bit(BTREE_NODE_dirty, &b->flags);
1058
1059         mutex_unlock(&b->write_lock);
1060
1061         cancel_delayed_work(&b->work);
1062
1063         mutex_lock(&b->c->bucket_lock);
1064         bch_bucket_free(b->c, &b->key);
1065         mca_bucket_free(b);
1066         mutex_unlock(&b->c->bucket_lock);
1067 }
1068
1069 struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
1070                                      int level, bool wait,
1071                                      struct btree *parent)
1072 {
1073         BKEY_PADDED(key) k;
1074         struct btree *b = ERR_PTR(-EAGAIN);
1075
1076         mutex_lock(&c->bucket_lock);
1077 retry:
1078         if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, wait))
1079                 goto err;
1080
1081         bkey_put(c, &k.key);
1082         SET_KEY_SIZE(&k.key, c->btree_pages * PAGE_SECTORS);
1083
1084         b = mca_alloc(c, op, &k.key, level);
1085         if (IS_ERR(b))
1086                 goto err_free;
1087
1088         if (!b) {
1089                 cache_bug(c,
1090                         "Tried to allocate bucket that was in btree cache");
1091                 goto retry;
1092         }
1093
1094         b->accessed = 1;
1095         b->parent = parent;
1096         bch_bset_init_next(&b->keys, b->keys.set->data, bset_magic(&b->c->sb));
1097
1098         mutex_unlock(&c->bucket_lock);
1099
1100         trace_bcache_btree_node_alloc(b);
1101         return b;
1102 err_free:
1103         bch_bucket_free(c, &k.key);
1104 err:
1105         mutex_unlock(&c->bucket_lock);
1106
1107         trace_bcache_btree_node_alloc_fail(c);
1108         return b;
1109 }
1110
1111 static struct btree *bch_btree_node_alloc(struct cache_set *c,
1112                                           struct btree_op *op, int level,
1113                                           struct btree *parent)
1114 {
1115         return __bch_btree_node_alloc(c, op, level, op != NULL, parent);
1116 }
1117
1118 static struct btree *btree_node_alloc_replacement(struct btree *b,
1119                                                   struct btree_op *op)
1120 {
1121         struct btree *n = bch_btree_node_alloc(b->c, op, b->level, b->parent);
1122         if (!IS_ERR_OR_NULL(n)) {
1123                 mutex_lock(&n->write_lock);
1124                 bch_btree_sort_into(&b->keys, &n->keys, &b->c->sort);
1125                 bkey_copy_key(&n->key, &b->key);
1126                 mutex_unlock(&n->write_lock);
1127         }
1128
1129         return n;
1130 }
1131
1132 static void make_btree_freeing_key(struct btree *b, struct bkey *k)
1133 {
1134         unsigned i;
1135
1136         mutex_lock(&b->c->bucket_lock);
1137
1138         atomic_inc(&b->c->prio_blocked);
1139
1140         bkey_copy(k, &b->key);
1141         bkey_copy_key(k, &ZERO_KEY);
1142
1143         for (i = 0; i < KEY_PTRS(k); i++)
1144                 SET_PTR_GEN(k, i,
1145                             bch_inc_gen(PTR_CACHE(b->c, &b->key, i),
1146                                         PTR_BUCKET(b->c, &b->key, i)));
1147
1148         mutex_unlock(&b->c->bucket_lock);
1149 }
1150
1151 static int btree_check_reserve(struct btree *b, struct btree_op *op)
1152 {
1153         struct cache_set *c = b->c;
1154         struct cache *ca;
1155         unsigned i, reserve = (c->root->level - b->level) * 2 + 1;
1156
1157         mutex_lock(&c->bucket_lock);
1158
1159         for_each_cache(ca, c, i)
1160                 if (fifo_used(&ca->free[RESERVE_BTREE]) < reserve) {
1161                         if (op)
1162                                 prepare_to_wait(&c->btree_cache_wait, &op->wait,
1163                                                 TASK_UNINTERRUPTIBLE);
1164                         mutex_unlock(&c->bucket_lock);
1165                         return -EINTR;
1166                 }
1167
1168         mutex_unlock(&c->bucket_lock);
1169
1170         return mca_cannibalize_lock(b->c, op);
1171 }
1172
1173 /* Garbage collection */
1174
1175 static uint8_t __bch_btree_mark_key(struct cache_set *c, int level,
1176                                     struct bkey *k)
1177 {
1178         uint8_t stale = 0;
1179         unsigned i;
1180         struct bucket *g;
1181
1182         /*
1183          * ptr_invalid() can't return true for the keys that mark btree nodes as
1184          * freed, but since ptr_bad() returns true we'll never actually use them
1185          * for anything and thus we don't want mark their pointers here
1186          */
1187         if (!bkey_cmp(k, &ZERO_KEY))
1188                 return stale;
1189
1190         for (i = 0; i < KEY_PTRS(k); i++) {
1191                 if (!ptr_available(c, k, i))
1192                         continue;
1193
1194                 g = PTR_BUCKET(c, k, i);
1195
1196                 if (gen_after(g->last_gc, PTR_GEN(k, i)))
1197                         g->last_gc = PTR_GEN(k, i);
1198
1199                 if (ptr_stale(c, k, i)) {
1200                         stale = max(stale, ptr_stale(c, k, i));
1201                         continue;
1202                 }
1203
1204                 cache_bug_on(GC_MARK(g) &&
1205                              (GC_MARK(g) == GC_MARK_METADATA) != (level != 0),
1206                              c, "inconsistent ptrs: mark = %llu, level = %i",
1207                              GC_MARK(g), level);
1208
1209                 if (level)
1210                         SET_GC_MARK(g, GC_MARK_METADATA);
1211                 else if (KEY_DIRTY(k))
1212                         SET_GC_MARK(g, GC_MARK_DIRTY);
1213                 else if (!GC_MARK(g))
1214                         SET_GC_MARK(g, GC_MARK_RECLAIMABLE);
1215
1216                 /* guard against overflow */
1217                 SET_GC_SECTORS_USED(g, min_t(unsigned,
1218                                              GC_SECTORS_USED(g) + KEY_SIZE(k),
1219                                              MAX_GC_SECTORS_USED));
1220
1221                 BUG_ON(!GC_SECTORS_USED(g));
1222         }
1223
1224         return stale;
1225 }
1226
1227 #define btree_mark_key(b, k)    __bch_btree_mark_key(b->c, b->level, k)
1228
1229 void bch_initial_mark_key(struct cache_set *c, int level, struct bkey *k)
1230 {
1231         unsigned i;
1232
1233         for (i = 0; i < KEY_PTRS(k); i++)
1234                 if (ptr_available(c, k, i) &&
1235                     !ptr_stale(c, k, i)) {
1236                         struct bucket *b = PTR_BUCKET(c, k, i);
1237
1238                         b->gen = PTR_GEN(k, i);
1239
1240                         if (level && bkey_cmp(k, &ZERO_KEY))
1241                                 b->prio = BTREE_PRIO;
1242                         else if (!level && b->prio == BTREE_PRIO)
1243                                 b->prio = INITIAL_PRIO;
1244                 }
1245
1246         __bch_btree_mark_key(c, level, k);
1247 }
1248
1249 static bool btree_gc_mark_node(struct btree *b, struct gc_stat *gc)
1250 {
1251         uint8_t stale = 0;
1252         unsigned keys = 0, good_keys = 0;
1253         struct bkey *k;
1254         struct btree_iter iter;
1255         struct bset_tree *t;
1256
1257         gc->nodes++;
1258
1259         for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid) {
1260                 stale = max(stale, btree_mark_key(b, k));
1261                 keys++;
1262
1263                 if (bch_ptr_bad(&b->keys, k))
1264                         continue;
1265
1266                 gc->key_bytes += bkey_u64s(k);
1267                 gc->nkeys++;
1268                 good_keys++;
1269
1270                 gc->data += KEY_SIZE(k);
1271         }
1272
1273         for (t = b->keys.set; t <= &b->keys.set[b->keys.nsets]; t++)
1274                 btree_bug_on(t->size &&
1275                              bset_written(&b->keys, t) &&
1276                              bkey_cmp(&b->key, &t->end) < 0,
1277                              b, "found short btree key in gc");
1278
1279         if (b->c->gc_always_rewrite)
1280                 return true;
1281
1282         if (stale > 10)
1283                 return true;
1284
1285         if ((keys - good_keys) * 2 > keys)
1286                 return true;
1287
1288         return false;
1289 }
1290
1291 #define GC_MERGE_NODES  4U
1292
1293 struct gc_merge_info {
1294         struct btree    *b;
1295         unsigned        keys;
1296 };
1297
1298 static int bch_btree_insert_node(struct btree *, struct btree_op *,
1299                                  struct keylist *, atomic_t *, struct bkey *);
1300
1301 static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
1302                              struct gc_stat *gc, struct gc_merge_info *r)
1303 {
1304         unsigned i, nodes = 0, keys = 0, blocks;
1305         struct btree *new_nodes[GC_MERGE_NODES];
1306         struct keylist keylist;
1307         struct closure cl;
1308         struct bkey *k;
1309
1310         bch_keylist_init(&keylist);
1311
1312         if (btree_check_reserve(b, NULL))
1313                 return 0;
1314
1315         memset(new_nodes, 0, sizeof(new_nodes));
1316         closure_init_stack(&cl);
1317
1318         while (nodes < GC_MERGE_NODES && !IS_ERR_OR_NULL(r[nodes].b))
1319                 keys += r[nodes++].keys;
1320
1321         blocks = btree_default_blocks(b->c) * 2 / 3;
1322
1323         if (nodes < 2 ||
1324             __set_blocks(b->keys.set[0].data, keys,
1325                          block_bytes(b->c)) > blocks * (nodes - 1))
1326                 return 0;
1327
1328         for (i = 0; i < nodes; i++) {
1329                 new_nodes[i] = btree_node_alloc_replacement(r[i].b, NULL);
1330                 if (IS_ERR_OR_NULL(new_nodes[i]))
1331                         goto out_nocoalesce;
1332         }
1333
1334         /*
1335          * We have to check the reserve here, after we've allocated our new
1336          * nodes, to make sure the insert below will succeed - we also check
1337          * before as an optimization to potentially avoid a bunch of expensive
1338          * allocs/sorts
1339          */
1340         if (btree_check_reserve(b, NULL))
1341                 goto out_nocoalesce;
1342
1343         for (i = 0; i < nodes; i++)
1344                 mutex_lock(&new_nodes[i]->write_lock);
1345
1346         for (i = nodes - 1; i > 0; --i) {
1347                 struct bset *n1 = btree_bset_first(new_nodes[i]);
1348                 struct bset *n2 = btree_bset_first(new_nodes[i - 1]);
1349                 struct bkey *k, *last = NULL;
1350
1351                 keys = 0;
1352
1353                 if (i > 1) {
1354                         for (k = n2->start;
1355                              k < bset_bkey_last(n2);
1356                              k = bkey_next(k)) {
1357                                 if (__set_blocks(n1, n1->keys + keys +
1358                                                  bkey_u64s(k),
1359                                                  block_bytes(b->c)) > blocks)
1360                                         break;
1361
1362                                 last = k;
1363                                 keys += bkey_u64s(k);
1364                         }
1365                 } else {
1366                         /*
1367                          * Last node we're not getting rid of - we're getting
1368                          * rid of the node at r[0]. Have to try and fit all of
1369                          * the remaining keys into this node; we can't ensure
1370                          * they will always fit due to rounding and variable
1371                          * length keys (shouldn't be possible in practice,
1372                          * though)
1373                          */
1374                         if (__set_blocks(n1, n1->keys + n2->keys,
1375                                          block_bytes(b->c)) >
1376                             btree_blocks(new_nodes[i]))
1377                                 goto out_unlock_nocoalesce;
1378
1379                         keys = n2->keys;
1380                         /* Take the key of the node we're getting rid of */
1381                         last = &r->b->key;
1382                 }
1383
1384                 BUG_ON(__set_blocks(n1, n1->keys + keys, block_bytes(b->c)) >
1385                        btree_blocks(new_nodes[i]));
1386
1387                 if (last)
1388                         bkey_copy_key(&new_nodes[i]->key, last);
1389
1390                 memcpy(bset_bkey_last(n1),
1391                        n2->start,
1392                        (void *) bset_bkey_idx(n2, keys) - (void *) n2->start);
1393
1394                 n1->keys += keys;
1395                 r[i].keys = n1->keys;
1396
1397                 memmove(n2->start,
1398                         bset_bkey_idx(n2, keys),
1399                         (void *) bset_bkey_last(n2) -
1400                         (void *) bset_bkey_idx(n2, keys));
1401
1402                 n2->keys -= keys;
1403
1404                 if (__bch_keylist_realloc(&keylist,
1405                                           bkey_u64s(&new_nodes[i]->key)))
1406                         goto out_unlock_nocoalesce;
1407
1408                 bch_btree_node_write(new_nodes[i], &cl);
1409                 bch_keylist_add(&keylist, &new_nodes[i]->key);
1410         }
1411
1412         for (i = 0; i < nodes; i++)
1413                 mutex_unlock(&new_nodes[i]->write_lock);
1414
1415         closure_sync(&cl);
1416
1417         /* We emptied out this node */
1418         BUG_ON(btree_bset_first(new_nodes[0])->keys);
1419         btree_node_free(new_nodes[0]);
1420         rw_unlock(true, new_nodes[0]);
1421         new_nodes[0] = NULL;
1422
1423         for (i = 0; i < nodes; i++) {
1424                 if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b->key)))
1425                         goto out_nocoalesce;
1426
1427                 make_btree_freeing_key(r[i].b, keylist.top);
1428                 bch_keylist_push(&keylist);
1429         }
1430
1431         bch_btree_insert_node(b, op, &keylist, NULL, NULL);
1432         BUG_ON(!bch_keylist_empty(&keylist));
1433
1434         for (i = 0; i < nodes; i++) {
1435                 btree_node_free(r[i].b);
1436                 rw_unlock(true, r[i].b);
1437
1438                 r[i].b = new_nodes[i];
1439         }
1440
1441         memmove(r, r + 1, sizeof(r[0]) * (nodes - 1));
1442         r[nodes - 1].b = ERR_PTR(-EINTR);
1443
1444         trace_bcache_btree_gc_coalesce(nodes);
1445         gc->nodes--;
1446
1447         bch_keylist_free(&keylist);
1448
1449         /* Invalidated our iterator */
1450         return -EINTR;
1451
1452 out_unlock_nocoalesce:
1453         for (i = 0; i < nodes; i++)
1454                 mutex_unlock(&new_nodes[i]->write_lock);
1455
1456 out_nocoalesce:
1457         closure_sync(&cl);
1458         bch_keylist_free(&keylist);
1459
1460         while ((k = bch_keylist_pop(&keylist)))
1461                 if (!bkey_cmp(k, &ZERO_KEY))
1462                         atomic_dec(&b->c->prio_blocked);
1463
1464         for (i = 0; i < nodes; i++)
1465                 if (!IS_ERR_OR_NULL(new_nodes[i])) {
1466                         btree_node_free(new_nodes[i]);
1467                         rw_unlock(true, new_nodes[i]);
1468                 }
1469         return 0;
1470 }
1471
1472 static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op,
1473                                  struct btree *replace)
1474 {
1475         struct keylist keys;
1476         struct btree *n;
1477
1478         if (btree_check_reserve(b, NULL))
1479                 return 0;
1480
1481         n = btree_node_alloc_replacement(replace, NULL);
1482
1483         /* recheck reserve after allocating replacement node */
1484         if (btree_check_reserve(b, NULL)) {
1485                 btree_node_free(n);
1486                 rw_unlock(true, n);
1487                 return 0;
1488         }
1489
1490         bch_btree_node_write_sync(n);
1491
1492         bch_keylist_init(&keys);
1493         bch_keylist_add(&keys, &n->key);
1494
1495         make_btree_freeing_key(replace, keys.top);
1496         bch_keylist_push(&keys);
1497
1498         bch_btree_insert_node(b, op, &keys, NULL, NULL);
1499         BUG_ON(!bch_keylist_empty(&keys));
1500
1501         btree_node_free(replace);
1502         rw_unlock(true, n);
1503
1504         /* Invalidated our iterator */
1505         return -EINTR;
1506 }
1507
1508 static unsigned btree_gc_count_keys(struct btree *b)
1509 {
1510         struct bkey *k;
1511         struct btree_iter iter;
1512         unsigned ret = 0;
1513
1514         for_each_key_filter(&b->keys, k, &iter, bch_ptr_bad)
1515                 ret += bkey_u64s(k);
1516
1517         return ret;
1518 }
1519
1520 static int btree_gc_recurse(struct btree *b, struct btree_op *op,
1521                             struct closure *writes, struct gc_stat *gc)
1522 {
1523         int ret = 0;
1524         bool should_rewrite;
1525         struct bkey *k;
1526         struct btree_iter iter;
1527         struct gc_merge_info r[GC_MERGE_NODES];
1528         struct gc_merge_info *i, *last = r + ARRAY_SIZE(r) - 1;
1529
1530         bch_btree_iter_init(&b->keys, &iter, &b->c->gc_done);
1531
1532         for (i = r; i < r + ARRAY_SIZE(r); i++)
1533                 i->b = ERR_PTR(-EINTR);
1534
1535         while (1) {
1536                 k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad);
1537                 if (k) {
1538                         r->b = bch_btree_node_get(b->c, op, k, b->level - 1,
1539                                                   true, b);
1540                         if (IS_ERR(r->b)) {
1541                                 ret = PTR_ERR(r->b);
1542                                 break;
1543                         }
1544
1545                         r->keys = btree_gc_count_keys(r->b);
1546
1547                         ret = btree_gc_coalesce(b, op, gc, r);
1548                         if (ret)
1549                                 break;
1550                 }
1551
1552                 if (!last->b)
1553                         break;
1554
1555                 if (!IS_ERR(last->b)) {
1556                         should_rewrite = btree_gc_mark_node(last->b, gc);
1557                         if (should_rewrite) {
1558                                 ret = btree_gc_rewrite_node(b, op, last->b);
1559                                 if (ret)
1560                                         break;
1561                         }
1562
1563                         if (last->b->level) {
1564                                 ret = btree_gc_recurse(last->b, op, writes, gc);
1565                                 if (ret)
1566                                         break;
1567                         }
1568
1569                         bkey_copy_key(&b->c->gc_done, &last->b->key);
1570
1571                         /*
1572                          * Must flush leaf nodes before gc ends, since replace
1573                          * operations aren't journalled
1574                          */
1575                         mutex_lock(&last->b->write_lock);
1576                         if (btree_node_dirty(last->b))
1577                                 bch_btree_node_write(last->b, writes);
1578                         mutex_unlock(&last->b->write_lock);
1579                         rw_unlock(true, last->b);
1580                 }
1581
1582                 memmove(r + 1, r, sizeof(r[0]) * (GC_MERGE_NODES - 1));
1583                 r->b = NULL;
1584
1585                 if (need_resched()) {
1586                         ret = -EAGAIN;
1587                         break;
1588                 }
1589         }
1590
1591         for (i = r; i < r + ARRAY_SIZE(r); i++)
1592                 if (!IS_ERR_OR_NULL(i->b)) {
1593                         mutex_lock(&i->b->write_lock);
1594                         if (btree_node_dirty(i->b))
1595                                 bch_btree_node_write(i->b, writes);
1596                         mutex_unlock(&i->b->write_lock);
1597                         rw_unlock(true, i->b);
1598                 }
1599
1600         return ret;
1601 }
1602
1603 static int bch_btree_gc_root(struct btree *b, struct btree_op *op,
1604                              struct closure *writes, struct gc_stat *gc)
1605 {
1606         struct btree *n = NULL;
1607         int ret = 0;
1608         bool should_rewrite;
1609
1610         should_rewrite = btree_gc_mark_node(b, gc);
1611         if (should_rewrite) {
1612                 n = btree_node_alloc_replacement(b, NULL);
1613
1614                 if (!IS_ERR_OR_NULL(n)) {
1615                         bch_btree_node_write_sync(n);
1616
1617                         bch_btree_set_root(n);
1618                         btree_node_free(b);
1619                         rw_unlock(true, n);
1620
1621                         return -EINTR;
1622                 }
1623         }
1624
1625         __bch_btree_mark_key(b->c, b->level + 1, &b->key);
1626
1627         if (b->level) {
1628                 ret = btree_gc_recurse(b, op, writes, gc);
1629                 if (ret)
1630                         return ret;
1631         }
1632
1633         bkey_copy_key(&b->c->gc_done, &b->key);
1634
1635         return ret;
1636 }
1637
1638 static void btree_gc_start(struct cache_set *c)
1639 {
1640         struct cache *ca;
1641         struct bucket *b;
1642         unsigned i;
1643
1644         if (!c->gc_mark_valid)
1645                 return;
1646
1647         mutex_lock(&c->bucket_lock);
1648
1649         c->gc_mark_valid = 0;
1650         c->gc_done = ZERO_KEY;
1651
1652         for_each_cache(ca, c, i)
1653                 for_each_bucket(b, ca) {
1654                         b->last_gc = b->gen;
1655                         if (!atomic_read(&b->pin)) {
1656                                 SET_GC_MARK(b, 0);
1657                                 SET_GC_SECTORS_USED(b, 0);
1658                         }
1659                 }
1660
1661         mutex_unlock(&c->bucket_lock);
1662 }
1663
1664 static size_t bch_btree_gc_finish(struct cache_set *c)
1665 {
1666         size_t available = 0;
1667         struct bucket *b;
1668         struct cache *ca;
1669         unsigned i;
1670
1671         mutex_lock(&c->bucket_lock);
1672
1673         set_gc_sectors(c);
1674         c->gc_mark_valid = 1;
1675         c->need_gc      = 0;
1676
1677         for (i = 0; i < KEY_PTRS(&c->uuid_bucket); i++)
1678                 SET_GC_MARK(PTR_BUCKET(c, &c->uuid_bucket, i),
1679                             GC_MARK_METADATA);
1680
1681         /* don't reclaim buckets to which writeback keys point */
1682         rcu_read_lock();
1683         for (i = 0; i < c->nr_uuids; i++) {
1684                 struct bcache_device *d = c->devices[i];
1685                 struct cached_dev *dc;
1686                 struct keybuf_key *w, *n;
1687                 unsigned j;
1688
1689                 if (!d || UUID_FLASH_ONLY(&c->uuids[i]))
1690                         continue;
1691                 dc = container_of(d, struct cached_dev, disk);
1692
1693                 spin_lock(&dc->writeback_keys.lock);
1694                 rbtree_postorder_for_each_entry_safe(w, n,
1695                                         &dc->writeback_keys.keys, node)
1696                         for (j = 0; j < KEY_PTRS(&w->key); j++)
1697                                 SET_GC_MARK(PTR_BUCKET(c, &w->key, j),
1698                                             GC_MARK_DIRTY);
1699                 spin_unlock(&dc->writeback_keys.lock);
1700         }
1701         rcu_read_unlock();
1702
1703         for_each_cache(ca, c, i) {
1704                 uint64_t *i;
1705
1706                 ca->invalidate_needs_gc = 0;
1707
1708                 for (i = ca->sb.d; i < ca->sb.d + ca->sb.keys; i++)
1709                         SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
1710
1711                 for (i = ca->prio_buckets;
1712                      i < ca->prio_buckets + prio_buckets(ca) * 2; i++)
1713                         SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
1714
1715                 for_each_bucket(b, ca) {
1716                         c->need_gc      = max(c->need_gc, bucket_gc_gen(b));
1717
1718                         if (atomic_read(&b->pin))
1719                                 continue;
1720
1721                         BUG_ON(!GC_MARK(b) && GC_SECTORS_USED(b));
1722
1723                         if (!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE)
1724                                 available++;
1725                 }
1726         }
1727
1728         mutex_unlock(&c->bucket_lock);
1729         return available;
1730 }
1731
1732 static void bch_btree_gc(struct cache_set *c)
1733 {
1734         int ret;
1735         unsigned long available;
1736         struct gc_stat stats;
1737         struct closure writes;
1738         struct btree_op op;
1739         uint64_t start_time = local_clock();
1740
1741         trace_bcache_gc_start(c);
1742
1743         memset(&stats, 0, sizeof(struct gc_stat));
1744         closure_init_stack(&writes);
1745         bch_btree_op_init(&op, SHRT_MAX);
1746
1747         btree_gc_start(c);
1748
1749         do {
1750                 ret = btree_root(gc_root, c, &op, &writes, &stats);
1751                 closure_sync(&writes);
1752                 cond_resched();
1753
1754                 if (ret && ret != -EAGAIN)
1755                         pr_warn("gc failed!");
1756         } while (ret);
1757
1758         available = bch_btree_gc_finish(c);
1759         wake_up_allocators(c);
1760
1761         bch_time_stats_update(&c->btree_gc_time, start_time);
1762
1763         stats.key_bytes *= sizeof(uint64_t);
1764         stats.data      <<= 9;
1765         stats.in_use    = (c->nbuckets - available) * 100 / c->nbuckets;
1766         memcpy(&c->gc_stats, &stats, sizeof(struct gc_stat));
1767
1768         trace_bcache_gc_end(c);
1769
1770         bch_moving_gc(c);
1771 }
1772
1773 static bool gc_should_run(struct cache_set *c)
1774 {
1775         struct cache *ca;
1776         unsigned i;
1777
1778         for_each_cache(ca, c, i)
1779                 if (ca->invalidate_needs_gc)
1780                         return true;
1781
1782         if (atomic_read(&c->sectors_to_gc) < 0)
1783                 return true;
1784
1785         return false;
1786 }
1787
1788 static int bch_gc_thread(void *arg)
1789 {
1790         struct cache_set *c = arg;
1791
1792         while (1) {
1793                 wait_event_interruptible(c->gc_wait,
1794                            kthread_should_stop() || gc_should_run(c));
1795
1796                 if (kthread_should_stop())
1797                         break;
1798
1799                 set_gc_sectors(c);
1800                 bch_btree_gc(c);
1801         }
1802
1803         return 0;
1804 }
1805
1806 int bch_gc_thread_start(struct cache_set *c)
1807 {
1808         c->gc_thread = kthread_run(bch_gc_thread, c, "bcache_gc");
1809         if (IS_ERR(c->gc_thread))
1810                 return PTR_ERR(c->gc_thread);
1811
1812         return 0;
1813 }
1814
1815 /* Initial partial gc */
1816
1817 static int bch_btree_check_recurse(struct btree *b, struct btree_op *op)
1818 {
1819         int ret = 0;
1820         struct bkey *k, *p = NULL;
1821         struct btree_iter iter;
1822
1823         for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid)
1824                 bch_initial_mark_key(b->c, b->level, k);
1825
1826         bch_initial_mark_key(b->c, b->level + 1, &b->key);
1827
1828         if (b->level) {
1829                 bch_btree_iter_init(&b->keys, &iter, NULL);
1830
1831                 do {
1832                         k = bch_btree_iter_next_filter(&iter, &b->keys,
1833                                                        bch_ptr_bad);
1834                         if (k)
1835                                 btree_node_prefetch(b, k);
1836
1837                         if (p)
1838                                 ret = btree(check_recurse, p, b, op);
1839
1840                         p = k;
1841                 } while (p && !ret);
1842         }
1843
1844         return ret;
1845 }
1846
1847 int bch_btree_check(struct cache_set *c)
1848 {
1849         struct btree_op op;
1850
1851         bch_btree_op_init(&op, SHRT_MAX);
1852
1853         return btree_root(check_recurse, c, &op);
1854 }
1855
1856 void bch_initial_gc_finish(struct cache_set *c)
1857 {
1858         struct cache *ca;
1859         struct bucket *b;
1860         unsigned i;
1861
1862         bch_btree_gc_finish(c);
1863
1864         mutex_lock(&c->bucket_lock);
1865
1866         /*
1867          * We need to put some unused buckets directly on the prio freelist in
1868          * order to get the allocator thread started - it needs freed buckets in
1869          * order to rewrite the prios and gens, and it needs to rewrite prios
1870          * and gens in order to free buckets.
1871          *
1872          * This is only safe for buckets that have no live data in them, which
1873          * there should always be some of.
1874          */
1875         for_each_cache(ca, c, i) {
1876                 for_each_bucket(b, ca) {
1877                         if (fifo_full(&ca->free[RESERVE_PRIO]) &&
1878                             fifo_full(&ca->free[RESERVE_BTREE]))
1879                                 break;
1880
1881                         if (bch_can_invalidate_bucket(ca, b) &&
1882                             !GC_MARK(b)) {
1883                                 __bch_invalidate_one_bucket(ca, b);
1884                                 if (!fifo_push(&ca->free[RESERVE_PRIO],
1885                                    b - ca->buckets))
1886                                         fifo_push(&ca->free[RESERVE_BTREE],
1887                                                   b - ca->buckets);
1888                         }
1889                 }
1890         }
1891
1892         mutex_unlock(&c->bucket_lock);
1893 }
1894
1895 /* Btree insertion */
1896
1897 static bool btree_insert_key(struct btree *b, struct bkey *k,
1898                              struct bkey *replace_key)
1899 {
1900         unsigned status;
1901
1902         BUG_ON(bkey_cmp(k, &b->key) > 0);
1903
1904         status = bch_btree_insert_key(&b->keys, k, replace_key);
1905         if (status != BTREE_INSERT_STATUS_NO_INSERT) {
1906                 bch_check_keys(&b->keys, "%u for %s", status,
1907                                replace_key ? "replace" : "insert");
1908
1909                 trace_bcache_btree_insert_key(b, k, replace_key != NULL,
1910                                               status);
1911                 return true;
1912         } else
1913                 return false;
1914 }
1915
1916 static size_t insert_u64s_remaining(struct btree *b)
1917 {
1918         long ret = bch_btree_keys_u64s_remaining(&b->keys);
1919
1920         /*
1921          * Might land in the middle of an existing extent and have to split it
1922          */
1923         if (b->keys.ops->is_extents)
1924                 ret -= KEY_MAX_U64S;
1925
1926         return max(ret, 0L);
1927 }
1928
1929 static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
1930                                   struct keylist *insert_keys,
1931                                   struct bkey *replace_key)
1932 {
1933         bool ret = false;
1934         int oldsize = bch_count_data(&b->keys);
1935
1936         while (!bch_keylist_empty(insert_keys)) {
1937                 struct bkey *k = insert_keys->keys;
1938
1939                 if (bkey_u64s(k) > insert_u64s_remaining(b))
1940                         break;
1941
1942                 if (bkey_cmp(k, &b->key) <= 0) {
1943                         if (!b->level)
1944                                 bkey_put(b->c, k);
1945
1946                         ret |= btree_insert_key(b, k, replace_key);
1947                         bch_keylist_pop_front(insert_keys);
1948                 } else if (bkey_cmp(&START_KEY(k), &b->key) < 0) {
1949                         BKEY_PADDED(key) temp;
1950                         bkey_copy(&temp.key, insert_keys->keys);
1951
1952                         bch_cut_back(&b->key, &temp.key);
1953                         bch_cut_front(&b->key, insert_keys->keys);
1954
1955                         ret |= btree_insert_key(b, &temp.key, replace_key);
1956                         break;
1957                 } else {
1958                         break;
1959                 }
1960         }
1961
1962         if (!ret)
1963                 op->insert_collision = true;
1964
1965         BUG_ON(!bch_keylist_empty(insert_keys) && b->level);
1966
1967         BUG_ON(bch_count_data(&b->keys) < oldsize);
1968         return ret;
1969 }
1970
1971 static int btree_split(struct btree *b, struct btree_op *op,
1972                        struct keylist *insert_keys,
1973                        struct bkey *replace_key)
1974 {
1975         bool split;
1976         struct btree *n1, *n2 = NULL, *n3 = NULL;
1977         uint64_t start_time = local_clock();
1978         struct closure cl;
1979         struct keylist parent_keys;
1980
1981         closure_init_stack(&cl);
1982         bch_keylist_init(&parent_keys);
1983
1984         if (btree_check_reserve(b, op)) {
1985                 if (!b->level)
1986                         return -EINTR;
1987                 else
1988                         WARN(1, "insufficient reserve for split\n");
1989         }
1990
1991         n1 = btree_node_alloc_replacement(b, op);
1992         if (IS_ERR(n1))
1993                 goto err;
1994
1995         split = set_blocks(btree_bset_first(n1),
1996                            block_bytes(n1->c)) > (btree_blocks(b) * 4) / 5;
1997
1998         if (split) {
1999                 unsigned keys = 0;
2000
2001                 trace_bcache_btree_node_split(b, btree_bset_first(n1)->keys);
2002
2003                 n2 = bch_btree_node_alloc(b->c, op, b->level, b->parent);
2004                 if (IS_ERR(n2))
2005                         goto err_free1;
2006
2007                 if (!b->parent) {
2008                         n3 = bch_btree_node_alloc(b->c, op, b->level + 1, NULL);
2009                         if (IS_ERR(n3))
2010                                 goto err_free2;
2011                 }
2012
2013                 mutex_lock(&n1->write_lock);
2014                 mutex_lock(&n2->write_lock);
2015
2016                 bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2017
2018                 /*
2019                  * Has to be a linear search because we don't have an auxiliary
2020                  * search tree yet
2021                  */
2022
2023                 while (keys < (btree_bset_first(n1)->keys * 3) / 5)
2024                         keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1),
2025                                                         keys));
2026
2027                 bkey_copy_key(&n1->key,
2028                               bset_bkey_idx(btree_bset_first(n1), keys));
2029                 keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1), keys));
2030
2031                 btree_bset_first(n2)->keys = btree_bset_first(n1)->keys - keys;
2032                 btree_bset_first(n1)->keys = keys;
2033
2034                 memcpy(btree_bset_first(n2)->start,
2035                        bset_bkey_last(btree_bset_first(n1)),
2036                        btree_bset_first(n2)->keys * sizeof(uint64_t));
2037
2038                 bkey_copy_key(&n2->key, &b->key);
2039
2040                 bch_keylist_add(&parent_keys, &n2->key);
2041                 bch_btree_node_write(n2, &cl);
2042                 mutex_unlock(&n2->write_lock);
2043                 rw_unlock(true, n2);
2044         } else {
2045                 trace_bcache_btree_node_compact(b, btree_bset_first(n1)->keys);
2046
2047                 mutex_lock(&n1->write_lock);
2048                 bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2049         }
2050
2051         bch_keylist_add(&parent_keys, &n1->key);
2052         bch_btree_node_write(n1, &cl);
2053         mutex_unlock(&n1->write_lock);
2054
2055         if (n3) {
2056                 /* Depth increases, make a new root */
2057                 mutex_lock(&n3->write_lock);
2058                 bkey_copy_key(&n3->key, &MAX_KEY);
2059                 bch_btree_insert_keys(n3, op, &parent_keys, NULL);
2060                 bch_btree_node_write(n3, &cl);
2061                 mutex_unlock(&n3->write_lock);
2062
2063                 closure_sync(&cl);
2064                 bch_btree_set_root(n3);
2065                 rw_unlock(true, n3);
2066         } else if (!b->parent) {
2067                 /* Root filled up but didn't need to be split */
2068                 closure_sync(&cl);
2069                 bch_btree_set_root(n1);
2070         } else {
2071                 /* Split a non root node */
2072                 closure_sync(&cl);
2073                 make_btree_freeing_key(b, parent_keys.top);
2074                 bch_keylist_push(&parent_keys);
2075
2076                 bch_btree_insert_node(b->parent, op, &parent_keys, NULL, NULL);
2077                 BUG_ON(!bch_keylist_empty(&parent_keys));
2078         }
2079
2080         btree_node_free(b);
2081         rw_unlock(true, n1);
2082
2083         bch_time_stats_update(&b->c->btree_split_time, start_time);
2084
2085         return 0;
2086 err_free2:
2087         bkey_put(b->c, &n2->key);
2088         btree_node_free(n2);
2089         rw_unlock(true, n2);
2090 err_free1:
2091         bkey_put(b->c, &n1->key);
2092         btree_node_free(n1);
2093         rw_unlock(true, n1);
2094 err:
2095         WARN(1, "bcache: btree split failed (level %u)", b->level);
2096
2097         if (n3 == ERR_PTR(-EAGAIN) ||
2098             n2 == ERR_PTR(-EAGAIN) ||
2099             n1 == ERR_PTR(-EAGAIN))
2100                 return -EAGAIN;
2101
2102         return -ENOMEM;
2103 }
2104
2105 static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
2106                                  struct keylist *insert_keys,
2107                                  atomic_t *journal_ref,
2108                                  struct bkey *replace_key)
2109 {
2110         struct closure cl;
2111
2112         BUG_ON(b->level && replace_key);
2113
2114         closure_init_stack(&cl);
2115
2116         mutex_lock(&b->write_lock);
2117
2118         if (write_block(b) != btree_bset_last(b) &&
2119             b->keys.last_set_unwritten)
2120                 bch_btree_init_next(b); /* just wrote a set */
2121
2122         if (bch_keylist_nkeys(insert_keys) > insert_u64s_remaining(b)) {
2123                 mutex_unlock(&b->write_lock);
2124                 goto split;
2125         }
2126
2127         BUG_ON(write_block(b) != btree_bset_last(b));
2128
2129         if (bch_btree_insert_keys(b, op, insert_keys, replace_key)) {
2130                 if (!b->level)
2131                         bch_btree_leaf_dirty(b, journal_ref);
2132                 else
2133                         bch_btree_node_write(b, &cl);
2134         }
2135
2136         mutex_unlock(&b->write_lock);
2137
2138         /* wait for btree node write if necessary, after unlock */
2139         closure_sync(&cl);
2140
2141         return 0;
2142 split:
2143         if (current->bio_list) {
2144                 op->lock = b->c->root->level + 1;
2145                 return -EAGAIN;
2146         } else if (op->lock <= b->c->root->level) {
2147                 op->lock = b->c->root->level + 1;
2148                 return -EINTR;
2149         } else {
2150                 /* Invalidated all iterators */
2151                 int ret = btree_split(b, op, insert_keys, replace_key);
2152
2153                 if (bch_keylist_empty(insert_keys))
2154                         return 0;
2155                 else if (!ret)
2156                         return -EINTR;
2157                 return ret;
2158         }
2159 }
2160
2161 int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
2162                                struct bkey *check_key)
2163 {
2164         int ret = -EINTR;
2165         uint64_t btree_ptr = b->key.ptr[0];
2166         unsigned long seq = b->seq;
2167         struct keylist insert;
2168         bool upgrade = op->lock == -1;
2169
2170         bch_keylist_init(&insert);
2171
2172         if (upgrade) {
2173                 rw_unlock(false, b);
2174                 rw_lock(true, b, b->level);
2175
2176                 if (b->key.ptr[0] != btree_ptr ||
2177                    b->seq != seq + 1) {
2178                        op->lock = b->level;
2179                         goto out;
2180                }
2181         }
2182
2183         SET_KEY_PTRS(check_key, 1);
2184         get_random_bytes(&check_key->ptr[0], sizeof(uint64_t));
2185
2186         SET_PTR_DEV(check_key, 0, PTR_CHECK_DEV);
2187
2188         bch_keylist_add(&insert, check_key);
2189
2190         ret = bch_btree_insert_node(b, op, &insert, NULL, NULL);
2191
2192         BUG_ON(!ret && !bch_keylist_empty(&insert));
2193 out:
2194         if (upgrade)
2195                 downgrade_write(&b->lock);
2196         return ret;
2197 }
2198
2199 struct btree_insert_op {
2200         struct btree_op op;
2201         struct keylist  *keys;
2202         atomic_t        *journal_ref;
2203         struct bkey     *replace_key;
2204 };
2205
2206 static int btree_insert_fn(struct btree_op *b_op, struct btree *b)
2207 {
2208         struct btree_insert_op *op = container_of(b_op,
2209                                         struct btree_insert_op, op);
2210
2211         int ret = bch_btree_insert_node(b, &op->op, op->keys,
2212                                         op->journal_ref, op->replace_key);
2213         if (ret && !bch_keylist_empty(op->keys))
2214                 return ret;
2215         else
2216                 return MAP_DONE;
2217 }
2218
2219 int bch_btree_insert(struct cache_set *c, struct keylist *keys,
2220                      atomic_t *journal_ref, struct bkey *replace_key)
2221 {
2222         struct btree_insert_op op;
2223         int ret = 0;
2224
2225         BUG_ON(current->bio_list);
2226         BUG_ON(bch_keylist_empty(keys));
2227
2228         bch_btree_op_init(&op.op, 0);
2229         op.keys         = keys;
2230         op.journal_ref  = journal_ref;
2231         op.replace_key  = replace_key;
2232
2233         while (!ret && !bch_keylist_empty(keys)) {
2234                 op.op.lock = 0;
2235                 ret = bch_btree_map_leaf_nodes(&op.op, c,
2236                                                &START_KEY(keys->keys),
2237                                                btree_insert_fn);
2238         }
2239
2240         if (ret) {
2241                 struct bkey *k;
2242
2243                 pr_err("error %i", ret);
2244
2245                 while ((k = bch_keylist_pop(keys)))
2246                         bkey_put(c, k);
2247         } else if (op.op.insert_collision)
2248                 ret = -ESRCH;
2249
2250         return ret;
2251 }
2252
2253 void bch_btree_set_root(struct btree *b)
2254 {
2255         unsigned i;
2256         struct closure cl;
2257
2258         closure_init_stack(&cl);
2259
2260         trace_bcache_btree_set_root(b);
2261
2262         BUG_ON(!b->written);
2263
2264         for (i = 0; i < KEY_PTRS(&b->key); i++)
2265                 BUG_ON(PTR_BUCKET(b->c, &b->key, i)->prio != BTREE_PRIO);
2266
2267         mutex_lock(&b->c->bucket_lock);
2268         list_del_init(&b->list);
2269         mutex_unlock(&b->c->bucket_lock);
2270
2271         b->c->root = b;
2272
2273         bch_journal_meta(b->c, &cl);
2274         closure_sync(&cl);
2275 }
2276
2277 /* Map across nodes or keys */
2278
2279 static int bch_btree_map_nodes_recurse(struct btree *b, struct btree_op *op,
2280                                        struct bkey *from,
2281                                        btree_map_nodes_fn *fn, int flags)
2282 {
2283         int ret = MAP_CONTINUE;
2284
2285         if (b->level) {
2286                 struct bkey *k;
2287                 struct btree_iter iter;
2288
2289                 bch_btree_iter_init(&b->keys, &iter, from);
2290
2291                 while ((k = bch_btree_iter_next_filter(&iter, &b->keys,
2292                                                        bch_ptr_bad))) {
2293                         ret = btree(map_nodes_recurse, k, b,
2294                                     op, from, fn, flags);
2295                         from = NULL;
2296
2297                         if (ret != MAP_CONTINUE)
2298                                 return ret;
2299                 }
2300         }
2301
2302         if (!b->level || flags == MAP_ALL_NODES)
2303                 ret = fn(op, b);
2304
2305         return ret;
2306 }
2307
2308 int __bch_btree_map_nodes(struct btree_op *op, struct cache_set *c,
2309                           struct bkey *from, btree_map_nodes_fn *fn, int flags)
2310 {
2311         return btree_root(map_nodes_recurse, c, op, from, fn, flags);
2312 }
2313
2314 static int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op,
2315                                       struct bkey *from, btree_map_keys_fn *fn,
2316                                       int flags)
2317 {
2318         int ret = MAP_CONTINUE;
2319         struct bkey *k;
2320         struct btree_iter iter;
2321
2322         bch_btree_iter_init(&b->keys, &iter, from);
2323
2324         while ((k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad))) {
2325                 ret = !b->level
2326                         ? fn(op, b, k)
2327                         : btree(map_keys_recurse, k, b, op, from, fn, flags);
2328                 from = NULL;
2329
2330                 if (ret != MAP_CONTINUE)
2331                         return ret;
2332         }
2333
2334         if (!b->level && (flags & MAP_END_KEY))
2335                 ret = fn(op, b, &KEY(KEY_INODE(&b->key),
2336                                      KEY_OFFSET(&b->key), 0));
2337
2338         return ret;
2339 }
2340
2341 int bch_btree_map_keys(struct btree_op *op, struct cache_set *c,
2342                        struct bkey *from, btree_map_keys_fn *fn, int flags)
2343 {
2344         return btree_root(map_keys_recurse, c, op, from, fn, flags);
2345 }
2346
2347 /* Keybuf code */
2348
2349 static inline int keybuf_cmp(struct keybuf_key *l, struct keybuf_key *r)
2350 {
2351         /* Overlapping keys compare equal */
2352         if (bkey_cmp(&l->key, &START_KEY(&r->key)) <= 0)
2353                 return -1;
2354         if (bkey_cmp(&START_KEY(&l->key), &r->key) >= 0)
2355                 return 1;
2356         return 0;
2357 }
2358
2359 static inline int keybuf_nonoverlapping_cmp(struct keybuf_key *l,
2360                                             struct keybuf_key *r)
2361 {
2362         return clamp_t(int64_t, bkey_cmp(&l->key, &r->key), -1, 1);
2363 }
2364
2365 struct refill {
2366         struct btree_op op;
2367         unsigned        nr_found;
2368         struct keybuf   *buf;
2369         struct bkey     *end;
2370         keybuf_pred_fn  *pred;
2371 };
2372
2373 static int refill_keybuf_fn(struct btree_op *op, struct btree *b,
2374                             struct bkey *k)
2375 {
2376         struct refill *refill = container_of(op, struct refill, op);
2377         struct keybuf *buf = refill->buf;
2378         int ret = MAP_CONTINUE;
2379
2380         if (bkey_cmp(k, refill->end) > 0) {
2381                 ret = MAP_DONE;
2382                 goto out;
2383         }
2384
2385         if (!KEY_SIZE(k)) /* end key */
2386                 goto out;
2387
2388         if (refill->pred(buf, k)) {
2389                 struct keybuf_key *w;
2390
2391                 spin_lock(&buf->lock);
2392
2393                 w = array_alloc(&buf->freelist);
2394                 if (!w) {
2395                         spin_unlock(&buf->lock);
2396                         return MAP_DONE;
2397                 }
2398
2399                 w->private = NULL;
2400                 bkey_copy(&w->key, k);
2401
2402                 if (RB_INSERT(&buf->keys, w, node, keybuf_cmp))
2403                         array_free(&buf->freelist, w);
2404                 else
2405                         refill->nr_found++;
2406
2407                 if (array_freelist_empty(&buf->freelist))
2408                         ret = MAP_DONE;
2409
2410                 spin_unlock(&buf->lock);
2411         }
2412 out:
2413         buf->last_scanned = *k;
2414         return ret;
2415 }
2416
2417 void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
2418                        struct bkey *end, keybuf_pred_fn *pred)
2419 {
2420         struct bkey start = buf->last_scanned;
2421         struct refill refill;
2422
2423         cond_resched();
2424
2425         bch_btree_op_init(&refill.op, -1);
2426         refill.nr_found = 0;
2427         refill.buf      = buf;
2428         refill.end      = end;
2429         refill.pred     = pred;
2430
2431         bch_btree_map_keys(&refill.op, c, &buf->last_scanned,
2432                            refill_keybuf_fn, MAP_END_KEY);
2433
2434         trace_bcache_keyscan(refill.nr_found,
2435                              KEY_INODE(&start), KEY_OFFSET(&start),
2436                              KEY_INODE(&buf->last_scanned),
2437                              KEY_OFFSET(&buf->last_scanned));
2438
2439         spin_lock(&buf->lock);
2440
2441         if (!RB_EMPTY_ROOT(&buf->keys)) {
2442                 struct keybuf_key *w;
2443                 w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2444                 buf->start      = START_KEY(&w->key);
2445
2446                 w = RB_LAST(&buf->keys, struct keybuf_key, node);
2447                 buf->end        = w->key;
2448         } else {
2449                 buf->start      = MAX_KEY;
2450                 buf->end        = MAX_KEY;
2451         }
2452
2453         spin_unlock(&buf->lock);
2454 }
2455
2456 static void __bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2457 {
2458         rb_erase(&w->node, &buf->keys);
2459         array_free(&buf->freelist, w);
2460 }
2461
2462 void bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2463 {
2464         spin_lock(&buf->lock);
2465         __bch_keybuf_del(buf, w);
2466         spin_unlock(&buf->lock);
2467 }
2468
2469 bool bch_keybuf_check_overlapping(struct keybuf *buf, struct bkey *start,
2470                                   struct bkey *end)
2471 {
2472         bool ret = false;
2473         struct keybuf_key *p, *w, s;
2474         s.key = *start;
2475
2476         if (bkey_cmp(end, &buf->start) <= 0 ||
2477             bkey_cmp(start, &buf->end) >= 0)
2478                 return false;
2479
2480         spin_lock(&buf->lock);
2481         w = RB_GREATER(&buf->keys, s, node, keybuf_nonoverlapping_cmp);
2482
2483         while (w && bkey_cmp(&START_KEY(&w->key), end) < 0) {
2484                 p = w;
2485                 w = RB_NEXT(w, node);
2486
2487                 if (p->private)
2488                         ret = true;
2489                 else
2490                         __bch_keybuf_del(buf, p);
2491         }
2492
2493         spin_unlock(&buf->lock);
2494         return ret;
2495 }
2496
2497 struct keybuf_key *bch_keybuf_next(struct keybuf *buf)
2498 {
2499         struct keybuf_key *w;
2500         spin_lock(&buf->lock);
2501
2502         w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2503
2504         while (w && w->private)
2505                 w = RB_NEXT(w, node);
2506
2507         if (w)
2508                 w->private = ERR_PTR(-EINTR);
2509
2510         spin_unlock(&buf->lock);
2511         return w;
2512 }
2513
2514 struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
2515                                           struct keybuf *buf,
2516                                           struct bkey *end,
2517                                           keybuf_pred_fn *pred)
2518 {
2519         struct keybuf_key *ret;
2520
2521         while (1) {
2522                 ret = bch_keybuf_next(buf);
2523                 if (ret)
2524                         break;
2525
2526                 if (bkey_cmp(&buf->last_scanned, end) >= 0) {
2527                         pr_debug("scan finished");
2528                         break;
2529                 }
2530
2531                 bch_refill_keybuf(c, buf, end, pred);
2532         }
2533
2534         return ret;
2535 }
2536
2537 void bch_keybuf_init(struct keybuf *buf)
2538 {
2539         buf->last_scanned       = MAX_KEY;
2540         buf->keys               = RB_ROOT;
2541
2542         spin_lock_init(&buf->lock);
2543         array_allocator_init(&buf->freelist);
2544 }