drivers/md/bcache/btree.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
   4  *
   5  * Uses a block device as cache for other block devices; optimized for SSDs.
   6  * All allocation is done in buckets, which should match the erase block size
   7  * of the device.
   8  *
   9  * Buckets containing cached data are kept on a heap sorted by priority;
  10  * bucket priority is increased on cache hit, and periodically all the buckets
  11  * on the heap have their priority scaled down. This currently is just used as
  12  * an LRU but in the future should allow for more intelligent heuristics.
  13  *
  14  * Buckets have an 8 bit counter; freeing is accomplished by incrementing the
  15  * counter. Garbage collection is used to remove stale pointers.
  16  *
  17  * Indexing is done via a btree; nodes are not necessarily fully sorted, rather
  18  * as keys are inserted we only sort the pages that have not yet been written.
  19  * When garbage collection is run, we resort the entire node.
  20  *
  21  * All configuration is done via sysfs; see Documentation/admin-guide/bcache.rst.
  22  */
  23
  24 #include "bcache.h"
  25 #include "btree.h"
  26 #include "debug.h"
  27 #include "extents.h"
  28
  29 #include <linux/slab.h>
  30 #include <linux/bitops.h>
  31 #include <linux/hash.h>
  32 #include <linux/kthread.h>
  33 #include <linux/prefetch.h>
  34 #include <linux/random.h>
  35 #include <linux/rcupdate.h>
  36 #include <linux/sched/clock.h>
  37 #include <linux/rculist.h>
  38 #include <linux/delay.h>
  39 #include <trace/events/bcache.h>
  40
  41 /*
  42  * Todo:
  43  * register_bcache: Return errors out to userspace correctly
  44  *
  45  * Writeback: don't undirty key until after a cache flush
  46  *
  47  * Create an iterator for key pointers
  48  *
  49  * On btree write error, mark bucket such that it won't be freed from the cache
  50  *
  51  * Journalling:
  52  *   Check for bad keys in replay
  53  *   Propagate barriers
  54  *   Refcount journal entries in journal_replay
  55  *
  56  * Garbage collection:
  57  *   Finish incremental gc
  58  *   Gc should free old UUIDs, data for invalid UUIDs
  59  *
  60  * Provide a way to list backing device UUIDs we have data cached for, and
  61  * probably how long it's been since we've seen them, and a way to invalidate
  62  * dirty data for devices that will never be attached again
  63  *
  64  * Keep 1 min/5 min/15 min statistics of how busy a block device has been, so
  65  * that based on that and how much dirty data we have we can keep writeback
  66  * from being starved
  67  *
  68  * Add a tracepoint or somesuch to watch for writeback starvation
  69  *
  70  * When btree depth > 1 and splitting an interior node, we have to make sure
  71  * alloc_bucket() cannot fail. This should be true but is not completely
  72  * obvious.
  73  *
  74  * Plugging?
  75  *
  76  * If data write is less than hard sector size of ssd, round up offset in open
  77  * bucket to the next whole sector
  78  *
  79  * Superblock needs to be fleshed out for multiple cache devices
  80  *
  81  * Add a sysfs tunable for the number of writeback IOs in flight
  82  *
  83  * Add a sysfs tunable for the number of open data buckets
  84  *
  85  * IO tracking: Can we track when one process is doing io on behalf of another?
  86  * IO tracking: Don't use just an average, weigh more recent stuff higher
  87  *
  88  * Test module load/unload
  89  */
  90
  91 #define MAX_NEED_GC             64
  92 #define MAX_SAVE_PRIO           72
  93 #define MAX_GC_TIMES            100
  94 #define MIN_GC_NODES            100
  95 #define GC_SLEEP_MS             100
  96
  97 #define PTR_DIRTY_BIT           (((uint64_t) 1 << 36))
  98
  99 #define PTR_HASH(c, k)                                                  \
 100         (((k)->ptr[0] >> c->bucket_bits) | PTR_GEN(k, 0))
 101
 102 #define insert_lock(s, b)       ((b)->level <= (s)->lock)
 103
 104 /*
 105  * These macros are for recursing down the btree - they handle the details of
 106  * locking and looking up nodes in the cache for you. They're best treated as
 107  * mere syntax when reading code that uses them.
 108  *
 109  * op->lock determines whether we take a read or a write lock at a given depth.
 110  * If you've got a read lock and find that you need a write lock (i.e. you're
 111  * going to have to split), set op->lock and return -EINTR; btree_root() will
 112  * call you again and you'll have the correct lock.
 113  */
 114
 115 /**
 116  * btree - recurse down the btree on a specified key
 117  * @fn:         function to call, which will be passed the child node
 118  * @key:        key to recurse on
 119  * @b:          parent btree node
 120  * @op:         pointer to struct btree_op
 121  */
 122 #define btree(fn, key, b, op, ...)                                      \
 123 ({                                                                      \
 124         int _r, l = (b)->level - 1;                                     \
 125         bool _w = l <= (op)->lock;                                      \
 126         struct btree *_child = bch_btree_node_get((b)->c, op, key, l,   \
 127                                                   _w, b);               \
 128         if (!IS_ERR(_child)) {                                          \
 129                 _r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__);       \
 130                 rw_unlock(_w, _child);                                  \
 131         } else                                                          \
 132                 _r = PTR_ERR(_child);                                   \
 133         _r;                                                             \
 134 })
 135
 136 /**
 137  * btree_root - call a function on the root of the btree
 138  * @fn:         function to call, which will be passed the child node
 139  * @c:          cache set
 140  * @op:         pointer to struct btree_op
 141  */
 142 #define btree_root(fn, c, op, ...)                                      \
 143 ({                                                                      \
 144         int _r = -EINTR;                                                \
 145         do {                                                            \
 146                 struct btree *_b = (c)->root;                           \
 147                 bool _w = insert_lock(op, _b);                          \
 148                 rw_lock(_w, _b, _b->level);                             \
 149                 if (_b == (c)->root &&                                  \
 150                     _w == insert_lock(op, _b)) {                        \
 151                         _r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__);   \
 152                 }                                                       \
 153                 rw_unlock(_w, _b);                                      \
 154                 bch_cannibalize_unlock(c);                              \
 155                 if (_r == -EINTR)                                       \
 156                         schedule();                                     \
 157         } while (_r == -EINTR);                                         \
 158                                                                         \
 159         finish_wait(&(c)->btree_cache_wait, &(op)->wait);               \
 160         _r;                                                             \
 161 })
 162
 163 static inline struct bset *write_block(struct btree *b)
 164 {
 165         return ((void *) btree_bset_first(b)) + b->written * block_bytes(b->c);
 166 }
 167
 168 static void bch_btree_init_next(struct btree *b)
 169 {
 170         /* If not a leaf node, always sort */
 171         if (b->level && b->keys.nsets)
 172                 bch_btree_sort(&b->keys, &b->c->sort);
 173         else
 174                 bch_btree_sort_lazy(&b->keys, &b->c->sort);
 175
 176         if (b->written < btree_blocks(b))
 177                 bch_bset_init_next(&b->keys, write_block(b),
 178                                    bset_magic(&b->c->sb));
 179
 180 }
 181
 182 /* Btree key manipulation */
 183
 184 void bkey_put(struct cache_set *c, struct bkey *k)
 185 {
 186         unsigned int i;
 187
 188         for (i = 0; i < KEY_PTRS(k); i++)
 189                 if (ptr_available(c, k, i))
 190                         atomic_dec_bug(&PTR_BUCKET(c, k, i)->pin);
 191 }
 192
 193 /* Btree IO */
 194
 195 static uint64_t btree_csum_set(struct btree *b, struct bset *i)
 196 {
 197         uint64_t crc = b->key.ptr[0];
 198         void *data = (void *) i + 8, *end = bset_bkey_last(i);
 199
 200         crc = bch_crc64_update(crc, data, end - data);
 201         return crc ^ 0xffffffffffffffffULL;
 202 }
 203
 204 void bch_btree_node_read_done(struct btree *b)
 205 {
 206         const char *err = "bad btree header";
 207         struct bset *i = btree_bset_first(b);
 208         struct btree_iter *iter;
 209
 210         /*
 211          * c->fill_iter can allocate an iterator with more memory space
 212          * than static MAX_BSETS.
 213          * See the comment arount cache_set->fill_iter.
 214          */
 215         iter = mempool_alloc(&b->c->fill_iter, GFP_NOIO);
 216         iter->size = b->c->sb.bucket_size / b->c->sb.block_size;
 217         iter->used = 0;
 218
 219 #ifdef CONFIG_BCACHE_DEBUG
 220         iter->b = &b->keys;
 221 #endif
 222
 223         if (!i->seq)
 224                 goto err;
 225
 226         for (;
 227              b->written < btree_blocks(b) && i->seq == b->keys.set[0].data->seq;
 228              i = write_block(b)) {
 229                 err = "unsupported bset version";
 230                 if (i->version > BCACHE_BSET_VERSION)
 231                         goto err;
 232
 233                 err = "bad btree header";
 234                 if (b->written + set_blocks(i, block_bytes(b->c)) >
 235                     btree_blocks(b))
 236                         goto err;
 237
 238                 err = "bad magic";
 239                 if (i->magic != bset_magic(&b->c->sb))
 240                         goto err;
 241
 242                 err = "bad checksum";
 243                 switch (i->version) {
 244                 case 0:
 245                         if (i->csum != csum_set(i))
 246                                 goto err;
 247                         break;
 248                 case BCACHE_BSET_VERSION:
 249                         if (i->csum != btree_csum_set(b, i))
 250                                 goto err;
 251                         break;
 252                 }
 253
 254                 err = "empty set";
 255                 if (i != b->keys.set[0].data && !i->keys)
 256                         goto err;
 257
 258                 bch_btree_iter_push(iter, i->start, bset_bkey_last(i));
 259
 260                 b->written += set_blocks(i, block_bytes(b->c));
 261         }
 262
 263         err = "corrupted btree";
 264         for (i = write_block(b);
 265              bset_sector_offset(&b->keys, i) < KEY_SIZE(&b->key);
 266              i = ((void *) i) + block_bytes(b->c))
 267                 if (i->seq == b->keys.set[0].data->seq)
 268                         goto err;
 269
 270         bch_btree_sort_and_fix_extents(&b->keys, iter, &b->c->sort);
 271
 272         i = b->keys.set[0].data;
 273         err = "short btree key";
 274         if (b->keys.set[0].size &&
 275             bkey_cmp(&b->key, &b->keys.set[0].end) < 0)
 276                 goto err;
 277
 278         if (b->written < btree_blocks(b))
 279                 bch_bset_init_next(&b->keys, write_block(b),
 280                                    bset_magic(&b->c->sb));
 281 out:
 282         mempool_free(iter, &b->c->fill_iter);
 283         return;
 284 err:
 285         set_btree_node_io_error(b);
 286         bch_cache_set_error(b->c, "%s at bucket %zu, block %u, %u keys",
 287                             err, PTR_BUCKET_NR(b->c, &b->key, 0),
 288                             bset_block_offset(b, i), i->keys);
 289         goto out;
 290 }
 291
 292 static void btree_node_read_endio(struct bio *bio)
 293 {
 294         struct closure *cl = bio->bi_private;
 295
 296         closure_put(cl);
 297 }
 298
 299 static void bch_btree_node_read(struct btree *b)
 300 {
 301         uint64_t start_time = local_clock();
 302         struct closure cl;
 303         struct bio *bio;
 304
 305         trace_bcache_btree_read(b);
 306
 307         closure_init_stack(&cl);
 308
 309         bio = bch_bbio_alloc(b->c);
 310         bio->bi_iter.bi_size = KEY_SIZE(&b->key) << 9;
 311         bio->bi_end_io  = btree_node_read_endio;
 312         bio->bi_private = &cl;
 313         bio->bi_opf = REQ_OP_READ | REQ_META;
 314
 315         bch_bio_map(bio, b->keys.set[0].data);
 316
 317         bch_submit_bbio(bio, b->c, &b->key, 0);
 318         closure_sync(&cl);
 319
 320         if (bio->bi_status)
 321                 set_btree_node_io_error(b);
 322
 323         bch_bbio_free(bio, b->c);
 324
 325         if (btree_node_io_error(b))
 326                 goto err;
 327
 328         bch_btree_node_read_done(b);
 329         bch_time_stats_update(&b->c->btree_read_time, start_time);
 330
 331         return;
 332 err:
 333         bch_cache_set_error(b->c, "io error reading bucket %zu",
 334                             PTR_BUCKET_NR(b->c, &b->key, 0));
 335 }
 336
 337 static void btree_complete_write(struct btree *b, struct btree_write *w)
 338 {
 339         if (w->prio_blocked &&
 340             !atomic_sub_return(w->prio_blocked, &b->c->prio_blocked))
 341                 wake_up_allocators(b->c);
 342
 343         if (w->journal) {
 344                 atomic_dec_bug(w->journal);
 345                 __closure_wake_up(&b->c->journal.wait);
 346         }
 347
 348         w->prio_blocked = 0;
 349         w->journal      = NULL;
 350 }
 351
 352 static void btree_node_write_unlock(struct closure *cl)
 353 {
 354         struct btree *b = container_of(cl, struct btree, io);
 355
 356         up(&b->io_mutex);
 357 }
 358
 359 static void __btree_node_write_done(struct closure *cl)
 360 {
 361         struct btree *b = container_of(cl, struct btree, io);
 362         struct btree_write *w = btree_prev_write(b);
 363
 364         bch_bbio_free(b->bio, b->c);
 365         b->bio = NULL;
 366         btree_complete_write(b, w);
 367
 368         if (btree_node_dirty(b))
 369                 schedule_delayed_work(&b->work, 30 * HZ);
 370
 371         closure_return_with_destructor(cl, btree_node_write_unlock);
 372 }
 373
 374 static void btree_node_write_done(struct closure *cl)
 375 {
 376         struct btree *b = container_of(cl, struct btree, io);
 377
 378         bio_free_pages(b->bio);
 379         __btree_node_write_done(cl);
 380 }
 381
 382 static void btree_node_write_endio(struct bio *bio)
 383 {
 384         struct closure *cl = bio->bi_private;
 385         struct btree *b = container_of(cl, struct btree, io);
 386
 387         if (bio->bi_status)
 388                 set_btree_node_io_error(b);
 389
 390         bch_bbio_count_io_errors(b->c, bio, bio->bi_status, "writing btree");
 391         closure_put(cl);
 392 }
 393
 394 static void do_btree_node_write(struct btree *b)
 395 {
 396         struct closure *cl = &b->io;
 397         struct bset *i = btree_bset_last(b);
 398         BKEY_PADDED(key) k;
 399
 400         i->version      = BCACHE_BSET_VERSION;
 401         i->csum         = btree_csum_set(b, i);
 402
 403         BUG_ON(b->bio);
 404         b->bio = bch_bbio_alloc(b->c);
 405
 406         b->bio->bi_end_io       = btree_node_write_endio;
 407         b->bio->bi_private      = cl;
 408         b->bio->bi_iter.bi_size = roundup(set_bytes(i), block_bytes(b->c));
 409         b->bio->bi_opf          = REQ_OP_WRITE | REQ_META | REQ_FUA;
 410         bch_bio_map(b->bio, i);
 411
 412         /*
 413          * If we're appending to a leaf node, we don't technically need FUA -
 414          * this write just needs to be persisted before the next journal write,
 415          * which will be marked FLUSH|FUA.
 416          *
 417          * Similarly if we're writing a new btree root - the pointer is going to
 418          * be in the next journal entry.
 419          *
 420          * But if we're writing a new btree node (that isn't a root) or
 421          * appending to a non leaf btree node, we need either FUA or a flush
 422          * when we write the parent with the new pointer. FUA is cheaper than a
 423          * flush, and writes appending to leaf nodes aren't blocking anything so
 424          * just make all btree node writes FUA to keep things sane.
 425          */
 426
 427         bkey_copy(&k.key, &b->key);
 428         SET_PTR_OFFSET(&k.key, 0, PTR_OFFSET(&k.key, 0) +
 429                        bset_sector_offset(&b->keys, i));
 430
 431         if (!bch_bio_alloc_pages(b->bio, __GFP_NOWARN|GFP_NOWAIT)) {
 432                 struct bio_vec *bv;
 433                 void *addr = (void *) ((unsigned long) i & ~(PAGE_SIZE - 1));
 434                 struct bvec_iter_all iter_all;
 435
 436                 bio_for_each_segment_all(bv, b->bio, iter_all) {
 437                         memcpy(page_address(bv->bv_page), addr, PAGE_SIZE);
 438                         addr += PAGE_SIZE;
 439                 }
 440
 441                 bch_submit_bbio(b->bio, b->c, &k.key, 0);
 442
 443                 continue_at(cl, btree_node_write_done, NULL);
 444         } else {
 445                 /*
 446                  * No problem for multipage bvec since the bio is
 447                  * just allocated
 448                  */
 449                 b->bio->bi_vcnt = 0;
 450                 bch_bio_map(b->bio, i);
 451
 452                 bch_submit_bbio(b->bio, b->c, &k.key, 0);
 453
 454                 closure_sync(cl);
 455                 continue_at_nobarrier(cl, __btree_node_write_done, NULL);
 456         }
 457 }
 458
 459 void __bch_btree_node_write(struct btree *b, struct closure *parent)
 460 {
 461         struct bset *i = btree_bset_last(b);
 462
 463         lockdep_assert_held(&b->write_lock);
 464
 465         trace_bcache_btree_write(b);
 466
 467         BUG_ON(current->bio_list);
 468         BUG_ON(b->written >= btree_blocks(b));
 469         BUG_ON(b->written && !i->keys);
 470         BUG_ON(btree_bset_first(b)->seq != i->seq);
 471         bch_check_keys(&b->keys, "writing");
 472
 473         cancel_delayed_work(&b->work);
 474
 475         /* If caller isn't waiting for write, parent refcount is cache set */
 476         down(&b->io_mutex);
 477         closure_init(&b->io, parent ?: &b->c->cl);
 478
 479         clear_bit(BTREE_NODE_dirty,      &b->flags);
 480         change_bit(BTREE_NODE_write_idx, &b->flags);
 481
 482         do_btree_node_write(b);
 483
 484         atomic_long_add(set_blocks(i, block_bytes(b->c)) * b->c->sb.block_size,
 485                         &PTR_CACHE(b->c, &b->key, 0)->btree_sectors_written);
 486
 487         b->written += set_blocks(i, block_bytes(b->c));
 488 }
 489
 490 void bch_btree_node_write(struct btree *b, struct closure *parent)
 491 {
 492         unsigned int nsets = b->keys.nsets;
 493
 494         lockdep_assert_held(&b->lock);
 495
 496         __bch_btree_node_write(b, parent);
 497
 498         /*
 499          * do verify if there was more than one set initially (i.e. we did a
 500          * sort) and we sorted down to a single set:
 501          */
 502         if (nsets && !b->keys.nsets)
 503                 bch_btree_verify(b);
 504
 505         bch_btree_init_next(b);
 506 }
 507
 508 static void bch_btree_node_write_sync(struct btree *b)
 509 {
 510         struct closure cl;
 511
 512         closure_init_stack(&cl);
 513
 514         mutex_lock(&b->write_lock);
 515         bch_btree_node_write(b, &cl);
 516         mutex_unlock(&b->write_lock);
 517
 518         closure_sync(&cl);
 519 }
 520
 521 static void btree_node_write_work(struct work_struct *w)
 522 {
 523         struct btree *b = container_of(to_delayed_work(w), struct btree, work);
 524
 525         mutex_lock(&b->write_lock);
 526         if (btree_node_dirty(b))
 527                 __bch_btree_node_write(b, NULL);
 528         mutex_unlock(&b->write_lock);
 529 }
 530
 531 static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
 532 {
 533         struct bset *i = btree_bset_last(b);
 534         struct btree_write *w = btree_current_write(b);
 535
 536         lockdep_assert_held(&b->write_lock);
 537
 538         BUG_ON(!b->written);
 539         BUG_ON(!i->keys);
 540
 541         if (!btree_node_dirty(b))
 542                 schedule_delayed_work(&b->work, 30 * HZ);
 543
 544         set_btree_node_dirty(b);
 545
 546         if (journal_ref) {
 547                 if (w->journal &&
 548                     journal_pin_cmp(b->c, w->journal, journal_ref)) {
 549                         atomic_dec_bug(w->journal);
 550                         w->journal = NULL;
 551                 }
 552
 553                 if (!w->journal) {
 554                         w->journal = journal_ref;
 555                         atomic_inc(w->journal);
 556                 }
 557         }
 558
 559         /* Force write if set is too big */
 560         if (set_bytes(i) > PAGE_SIZE - 48 &&
 561             !current->bio_list)
 562                 bch_btree_node_write(b, NULL);
 563 }
 564
 565 /*
 566  * Btree in memory cache - allocation/freeing
 567  * mca -> memory cache
 568  */
 569
 570 #define mca_reserve(c)  (((c->root && c->root->level)           \
 571                           ? c->root->level : 1) * 8 + 16)
 572 #define mca_can_free(c)                                         \
 573         max_t(int, 0, c->btree_cache_used - mca_reserve(c))
 574
 575 static void mca_data_free(struct btree *b)
 576 {
 577         BUG_ON(b->io_mutex.count != 1);
 578
 579         bch_btree_keys_free(&b->keys);
 580
 581         b->c->btree_cache_used--;
 582         list_move(&b->list, &b->c->btree_cache_freed);
 583 }
 584
 585 static void mca_bucket_free(struct btree *b)
 586 {
 587         BUG_ON(btree_node_dirty(b));
 588
 589         b->key.ptr[0] = 0;
 590         hlist_del_init_rcu(&b->hash);
 591         list_move(&b->list, &b->c->btree_cache_freeable);
 592 }
 593
 594 static unsigned int btree_order(struct bkey *k)
 595 {
 596         return ilog2(KEY_SIZE(k) / PAGE_SECTORS ?: 1);
 597 }
 598
 599 static void mca_data_alloc(struct btree *b, struct bkey *k, gfp_t gfp)
 600 {
 601         if (!bch_btree_keys_alloc(&b->keys,
 602                                   max_t(unsigned int,
 603                                         ilog2(b->c->btree_pages),
 604                                         btree_order(k)),
 605                                   gfp)) {
 606                 b->c->btree_cache_used++;
 607                 list_move(&b->list, &b->c->btree_cache);
 608         } else {
 609                 list_move(&b->list, &b->c->btree_cache_freed);
 610         }
 611 }
 612
 613 static struct btree *mca_bucket_alloc(struct cache_set *c,
 614                                       struct bkey *k, gfp_t gfp)
 615 {
 616         /*
 617          * kzalloc() is necessary here for initialization,
 618          * see code comments in bch_btree_keys_init().
 619          */
 620         struct btree *b = kzalloc(sizeof(struct btree), gfp);
 621
 622         if (!b)
 623                 return NULL;
 624
 625         init_rwsem(&b->lock);
 626         lockdep_set_novalidate_class(&b->lock);
 627         mutex_init(&b->write_lock);
 628         lockdep_set_novalidate_class(&b->write_lock);
 629         INIT_LIST_HEAD(&b->list);
 630         INIT_DELAYED_WORK(&b->work, btree_node_write_work);
 631         b->c = c;
 632         sema_init(&b->io_mutex, 1);
 633
 634         mca_data_alloc(b, k, gfp);
 635         return b;
 636 }
 637
 638 static int mca_reap(struct btree *b, unsigned int min_order, bool flush)
 639 {
 640         struct closure cl;
 641
 642         closure_init_stack(&cl);
 643         lockdep_assert_held(&b->c->bucket_lock);
 644
 645         if (!down_write_trylock(&b->lock))
 646                 return -ENOMEM;
 647
 648         BUG_ON(btree_node_dirty(b) && !b->keys.set[0].data);
 649
 650         if (b->keys.page_order < min_order)
 651                 goto out_unlock;
 652
 653         if (!flush) {
 654                 if (btree_node_dirty(b))
 655                         goto out_unlock;
 656
 657                 if (down_trylock(&b->io_mutex))
 658                         goto out_unlock;
 659                 up(&b->io_mutex);
 660         }
 661
 662 retry:
 663         /*
 664          * BTREE_NODE_dirty might be cleared in btree_flush_btree() by
 665          * __bch_btree_node_write(). To avoid an extra flush, acquire
 666          * b->write_lock before checking BTREE_NODE_dirty bit.
 667          */
 668         mutex_lock(&b->write_lock);
 669         /*
 670          * If this btree node is selected in btree_flush_write() by journal
 671          * code, delay and retry until the node is flushed by journal code
 672          * and BTREE_NODE_journal_flush bit cleared by btree_flush_write().
 673          */
 674         if (btree_node_journal_flush(b)) {
 675                 pr_debug("bnode %p is flushing by journal, retry", b);
 676                 mutex_unlock(&b->write_lock);
 677                 udelay(1);
 678                 goto retry;
 679         }
 680
 681         if (btree_node_dirty(b))
 682                 __bch_btree_node_write(b, &cl);
 683         mutex_unlock(&b->write_lock);
 684
 685         closure_sync(&cl);
 686
 687         /* wait for any in flight btree write */
 688         down(&b->io_mutex);
 689         up(&b->io_mutex);
 690
 691         return 0;
 692 out_unlock:
 693         rw_unlock(true, b);
 694         return -ENOMEM;
 695 }
 696
 697 static unsigned long bch_mca_scan(struct shrinker *shrink,
 698                                   struct shrink_control *sc)
 699 {
 700         struct cache_set *c = container_of(shrink, struct cache_set, shrink);
 701         struct btree *b, *t;
 702         unsigned long i, nr = sc->nr_to_scan;
 703         unsigned long freed = 0;
 704         unsigned int btree_cache_used;
 705
 706         if (c->shrinker_disabled)
 707                 return SHRINK_STOP;
 708
 709         if (c->btree_cache_alloc_lock)
 710                 return SHRINK_STOP;
 711
 712         /* Return -1 if we can't do anything right now */
 713         if (sc->gfp_mask & __GFP_IO)
 714                 mutex_lock(&c->bucket_lock);
 715         else if (!mutex_trylock(&c->bucket_lock))
 716                 return -1;
 717
 718         /*
 719          * It's _really_ critical that we don't free too many btree nodes - we
 720          * have to always leave ourselves a reserve. The reserve is how we
 721          * guarantee that allocating memory for a new btree node can always
 722          * succeed, so that inserting keys into the btree can always succeed and
 723          * IO can always make forward progress:
 724          */
 725         nr /= c->btree_pages;
 726         nr = min_t(unsigned long, nr, mca_can_free(c));
 727
 728         i = 0;
 729         btree_cache_used = c->btree_cache_used;
 730         list_for_each_entry_safe(b, t, &c->btree_cache_freeable, list) {
 731                 if (nr <= 0)
 732                         goto out;
 733
 734                 if (++i > 3 &&
 735                     !mca_reap(b, 0, false)) {
 736                         mca_data_free(b);
 737                         rw_unlock(true, b);
 738                         freed++;
 739                 }
 740                 nr--;
 741         }
 742
 743         for (;  (nr--) && i < btree_cache_used; i++) {
 744                 if (list_empty(&c->btree_cache))
 745                         goto out;
 746
 747                 b = list_first_entry(&c->btree_cache, struct btree, list);
 748                 list_rotate_left(&c->btree_cache);
 749
 750                 if (!b->accessed &&
 751                     !mca_reap(b, 0, false)) {
 752                         mca_bucket_free(b);
 753                         mca_data_free(b);
 754                         rw_unlock(true, b);
 755                         freed++;
 756                 } else
 757                         b->accessed = 0;
 758         }
 759 out:
 760         mutex_unlock(&c->bucket_lock);
 761         return freed * c->btree_pages;
 762 }
 763
 764 static unsigned long bch_mca_count(struct shrinker *shrink,
 765                                    struct shrink_control *sc)
 766 {
 767         struct cache_set *c = container_of(shrink, struct cache_set, shrink);
 768
 769         if (c->shrinker_disabled)
 770                 return 0;
 771
 772         if (c->btree_cache_alloc_lock)
 773                 return 0;
 774
 775         return mca_can_free(c) * c->btree_pages;
 776 }
 777
 778 void bch_btree_cache_free(struct cache_set *c)
 779 {
 780         struct btree *b;
 781         struct closure cl;
 782
 783         closure_init_stack(&cl);
 784
 785         if (c->shrink.list.next)
 786                 unregister_shrinker(&c->shrink);
 787
 788         mutex_lock(&c->bucket_lock);
 789
 790 #ifdef CONFIG_BCACHE_DEBUG
 791         if (c->verify_data)
 792                 list_move(&c->verify_data->list, &c->btree_cache);
 793
 794         free_pages((unsigned long) c->verify_ondisk, ilog2(bucket_pages(c)));
 795 #endif
 796
 797         list_splice(&c->btree_cache_freeable,
 798                     &c->btree_cache);
 799
 800         while (!list_empty(&c->btree_cache)) {
 801                 b = list_first_entry(&c->btree_cache, struct btree, list);
 802
 803                 /*
 804                  * This function is called by cache_set_free(), no I/O
 805                  * request on cache now, it is unnecessary to acquire
 806                  * b->write_lock before clearing BTREE_NODE_dirty anymore.
 807                  */
 808                 if (btree_node_dirty(b)) {
 809                         btree_complete_write(b, btree_current_write(b));
 810                         clear_bit(BTREE_NODE_dirty, &b->flags);
 811                 }
 812                 mca_data_free(b);
 813         }
 814
 815         while (!list_empty(&c->btree_cache_freed)) {
 816                 b = list_first_entry(&c->btree_cache_freed,
 817                                      struct btree, list);
 818                 list_del(&b->list);
 819                 cancel_delayed_work_sync(&b->work);
 820                 kfree(b);
 821         }
 822
 823         mutex_unlock(&c->bucket_lock);
 824 }
 825
 826 int bch_btree_cache_alloc(struct cache_set *c)
 827 {
 828         unsigned int i;
 829
 830         for (i = 0; i < mca_reserve(c); i++)
 831                 if (!mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL))
 832                         return -ENOMEM;
 833
 834         list_splice_init(&c->btree_cache,
 835                          &c->btree_cache_freeable);
 836
 837 #ifdef CONFIG_BCACHE_DEBUG
 838         mutex_init(&c->verify_lock);
 839
 840         c->verify_ondisk = (void *)
 841                 __get_free_pages(GFP_KERNEL, ilog2(bucket_pages(c)));
 842
 843         c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
 844
 845         if (c->verify_data &&
 846             c->verify_data->keys.set->data)
 847                 list_del_init(&c->verify_data->list);
 848         else
 849                 c->verify_data = NULL;
 850 #endif
 851
 852         c->shrink.count_objects = bch_mca_count;
 853         c->shrink.scan_objects = bch_mca_scan;
 854         c->shrink.seeks = 4;
 855         c->shrink.batch = c->btree_pages * 2;
 856
 857         if (register_shrinker(&c->shrink))
 858                 pr_warn("bcache: %s: could not register shrinker",
 859                                 __func__);
 860
 861         return 0;
 862 }
 863
 864 /* Btree in memory cache - hash table */
 865
 866 static struct hlist_head *mca_hash(struct cache_set *c, struct bkey *k)
 867 {
 868         return &c->bucket_hash[hash_32(PTR_HASH(c, k), BUCKET_HASH_BITS)];
 869 }
 870
 871 static struct btree *mca_find(struct cache_set *c, struct bkey *k)
 872 {
 873         struct btree *b;
 874
 875         rcu_read_lock();
 876         hlist_for_each_entry_rcu(b, mca_hash(c, k), hash)
 877                 if (PTR_HASH(c, &b->key) == PTR_HASH(c, k))
 878                         goto out;
 879         b = NULL;
 880 out:
 881         rcu_read_unlock();
 882         return b;
 883 }
 884
 885 static int mca_cannibalize_lock(struct cache_set *c, struct btree_op *op)
 886 {
 887         struct task_struct *old;
 888
 889         old = cmpxchg(&c->btree_cache_alloc_lock, NULL, current);
 890         if (old && old != current) {
 891                 if (op)
 892                         prepare_to_wait(&c->btree_cache_wait, &op->wait,
 893                                         TASK_UNINTERRUPTIBLE);
 894                 return -EINTR;
 895         }
 896
 897         return 0;
 898 }
 899
 900 static struct btree *mca_cannibalize(struct cache_set *c, struct btree_op *op,
 901                                      struct bkey *k)
 902 {
 903         struct btree *b;
 904
 905         trace_bcache_btree_cache_cannibalize(c);
 906
 907         if (mca_cannibalize_lock(c, op))
 908                 return ERR_PTR(-EINTR);
 909
 910         list_for_each_entry_reverse(b, &c->btree_cache, list)
 911                 if (!mca_reap(b, btree_order(k), false))
 912                         return b;
 913
 914         list_for_each_entry_reverse(b, &c->btree_cache, list)
 915                 if (!mca_reap(b, btree_order(k), true))
 916                         return b;
 917
 918         WARN(1, "btree cache cannibalize failed\n");
 919         return ERR_PTR(-ENOMEM);
 920 }
 921
 922 /*
 923  * We can only have one thread cannibalizing other cached btree nodes at a time,
 924  * or we'll deadlock. We use an open coded mutex to ensure that, which a
 925  * cannibalize_bucket() will take. This means every time we unlock the root of
 926  * the btree, we need to release this lock if we have it held.
 927  */
 928 static void bch_cannibalize_unlock(struct cache_set *c)
 929 {
 930         if (c->btree_cache_alloc_lock == current) {
 931                 c->btree_cache_alloc_lock = NULL;
 932                 wake_up(&c->btree_cache_wait);
 933         }
 934 }
 935
 936 static struct btree *mca_alloc(struct cache_set *c, struct btree_op *op,
 937                                struct bkey *k, int level)
 938 {
 939         struct btree *b;
 940
 941         BUG_ON(current->bio_list);
 942
 943         lockdep_assert_held(&c->bucket_lock);
 944
 945         if (mca_find(c, k))
 946                 return NULL;
 947
 948         /* btree_free() doesn't free memory; it sticks the node on the end of
 949          * the list. Check if there's any freed nodes there:
 950          */
 951         list_for_each_entry(b, &c->btree_cache_freeable, list)
 952                 if (!mca_reap(b, btree_order(k), false))
 953                         goto out;
 954
 955         /* We never free struct btree itself, just the memory that holds the on
 956          * disk node. Check the freed list before allocating a new one:
 957          */
 958         list_for_each_entry(b, &c->btree_cache_freed, list)
 959                 if (!mca_reap(b, 0, false)) {
 960                         mca_data_alloc(b, k, __GFP_NOWARN|GFP_NOIO);
 961                         if (!b->keys.set[0].data)
 962                                 goto err;
 963                         else
 964                                 goto out;
 965                 }
 966
 967         b = mca_bucket_alloc(c, k, __GFP_NOWARN|GFP_NOIO);
 968         if (!b)
 969                 goto err;
 970
 971         BUG_ON(!down_write_trylock(&b->lock));
 972         if (!b->keys.set->data)
 973                 goto err;
 974 out:
 975         BUG_ON(b->io_mutex.count != 1);
 976
 977         bkey_copy(&b->key, k);
 978         list_move(&b->list, &c->btree_cache);
 979         hlist_del_init_rcu(&b->hash);
 980         hlist_add_head_rcu(&b->hash, mca_hash(c, k));
 981
 982         lock_set_subclass(&b->lock.dep_map, level + 1, _THIS_IP_);
 983         b->parent       = (void *) ~0UL;
 984         b->flags        = 0;
 985         b->written      = 0;
 986         b->level        = level;
 987
 988         if (!b->level)
 989                 bch_btree_keys_init(&b->keys, &bch_extent_keys_ops,
 990                                     &b->c->expensive_debug_checks);
 991         else
 992                 bch_btree_keys_init(&b->keys, &bch_btree_keys_ops,
 993                                     &b->c->expensive_debug_checks);
 994
 995         return b;
 996 err:
 997         if (b)
 998                 rw_unlock(true, b);
 999
1000         b = mca_cannibalize(c, op, k);
1001         if (!IS_ERR(b))
1002                 goto out;
1003
1004         return b;
1005 }
1006
1007 /*
1008  * bch_btree_node_get - find a btree node in the cache and lock it, reading it
1009  * in from disk if necessary.
1010  *
1011  * If IO is necessary and running under generic_make_request, returns -EAGAIN.
1012  *
1013  * The btree node will have either a read or a write lock held, depending on
1014  * level and op->lock.
1015  */
1016 struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op,
1017                                  struct bkey *k, int level, bool write,
1018                                  struct btree *parent)
1019 {
1020         int i = 0;
1021         struct btree *b;
1022
1023         BUG_ON(level < 0);
1024 retry:
1025         b = mca_find(c, k);
1026
1027         if (!b) {
1028                 if (current->bio_list)
1029                         return ERR_PTR(-EAGAIN);
1030
1031                 mutex_lock(&c->bucket_lock);
1032                 b = mca_alloc(c, op, k, level);
1033                 mutex_unlock(&c->bucket_lock);
1034
1035                 if (!b)
1036                         goto retry;
1037                 if (IS_ERR(b))
1038                         return b;
1039
1040                 bch_btree_node_read(b);
1041
1042                 if (!write)
1043                         downgrade_write(&b->lock);
1044         } else {
1045                 rw_lock(write, b, level);
1046                 if (PTR_HASH(c, &b->key) != PTR_HASH(c, k)) {
1047                         rw_unlock(write, b);
1048                         goto retry;
1049                 }
1050                 BUG_ON(b->level != level);
1051         }
1052
1053         if (btree_node_io_error(b)) {
1054                 rw_unlock(write, b);
1055                 return ERR_PTR(-EIO);
1056         }
1057
1058         BUG_ON(!b->written);
1059
1060         b->parent = parent;
1061         b->accessed = 1;
1062
1063         for (; i <= b->keys.nsets && b->keys.set[i].size; i++) {
1064                 prefetch(b->keys.set[i].tree);
1065                 prefetch(b->keys.set[i].data);
1066         }
1067
1068         for (; i <= b->keys.nsets; i++)
1069                 prefetch(b->keys.set[i].data);
1070
1071         return b;
1072 }
1073
1074 static void btree_node_prefetch(struct btree *parent, struct bkey *k)
1075 {
1076         struct btree *b;
1077
1078         mutex_lock(&parent->c->bucket_lock);
1079         b = mca_alloc(parent->c, NULL, k, parent->level - 1);
1080         mutex_unlock(&parent->c->bucket_lock);
1081
1082         if (!IS_ERR_OR_NULL(b)) {
1083                 b->parent = parent;
1084                 bch_btree_node_read(b);
1085                 rw_unlock(true, b);
1086         }
1087 }
1088
1089 /* Btree alloc */
1090
1091 static void btree_node_free(struct btree *b)
1092 {
1093         trace_bcache_btree_node_free(b);
1094
1095         BUG_ON(b == b->c->root);
1096
1097 retry:
1098         mutex_lock(&b->write_lock);
1099         /*
1100          * If the btree node is selected and flushing in btree_flush_write(),
1101          * delay and retry until the BTREE_NODE_journal_flush bit cleared,
1102          * then it is safe to free the btree node here. Otherwise this btree
1103          * node will be in race condition.
1104          */
1105         if (btree_node_journal_flush(b)) {
1106                 mutex_unlock(&b->write_lock);
1107                 pr_debug("bnode %p journal_flush set, retry", b);
1108                 udelay(1);
1109                 goto retry;
1110         }
1111
1112         if (btree_node_dirty(b)) {
1113                 btree_complete_write(b, btree_current_write(b));
1114                 clear_bit(BTREE_NODE_dirty, &b->flags);
1115         }
1116
1117         mutex_unlock(&b->write_lock);
1118
1119         cancel_delayed_work(&b->work);
1120
1121         mutex_lock(&b->c->bucket_lock);
1122         bch_bucket_free(b->c, &b->key);
1123         mca_bucket_free(b);
1124         mutex_unlock(&b->c->bucket_lock);
1125 }
1126
1127 struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
1128                                      int level, bool wait,
1129                                      struct btree *parent)
1130 {
1131         BKEY_PADDED(key) k;
1132         struct btree *b = ERR_PTR(-EAGAIN);
1133
1134         mutex_lock(&c->bucket_lock);
1135 retry:
1136         if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, wait))
1137                 goto err;
1138
1139         bkey_put(c, &k.key);
1140         SET_KEY_SIZE(&k.key, c->btree_pages * PAGE_SECTORS);
1141
1142         b = mca_alloc(c, op, &k.key, level);
1143         if (IS_ERR(b))
1144                 goto err_free;
1145
1146         if (!b) {
1147                 cache_bug(c,
1148                         "Tried to allocate bucket that was in btree cache");
1149                 goto retry;
1150         }
1151
1152         b->accessed = 1;
1153         b->parent = parent;
1154         bch_bset_init_next(&b->keys, b->keys.set->data, bset_magic(&b->c->sb));
1155
1156         mutex_unlock(&c->bucket_lock);
1157
1158         trace_bcache_btree_node_alloc(b);
1159         return b;
1160 err_free:
1161         bch_bucket_free(c, &k.key);
1162 err:
1163         mutex_unlock(&c->bucket_lock);
1164
1165         trace_bcache_btree_node_alloc_fail(c);
1166         return b;
1167 }
1168
1169 static struct btree *bch_btree_node_alloc(struct cache_set *c,
1170                                           struct btree_op *op, int level,
1171                                           struct btree *parent)
1172 {
1173         return __bch_btree_node_alloc(c, op, level, op != NULL, parent);
1174 }
1175
1176 static struct btree *btree_node_alloc_replacement(struct btree *b,
1177                                                   struct btree_op *op)
1178 {
1179         struct btree *n = bch_btree_node_alloc(b->c, op, b->level, b->parent);
1180
1181         if (!IS_ERR_OR_NULL(n)) {
1182                 mutex_lock(&n->write_lock);
1183                 bch_btree_sort_into(&b->keys, &n->keys, &b->c->sort);
1184                 bkey_copy_key(&n->key, &b->key);
1185                 mutex_unlock(&n->write_lock);
1186         }
1187
1188         return n;
1189 }
1190
1191 static void make_btree_freeing_key(struct btree *b, struct bkey *k)
1192 {
1193         unsigned int i;
1194
1195         mutex_lock(&b->c->bucket_lock);
1196
1197         atomic_inc(&b->c->prio_blocked);
1198
1199         bkey_copy(k, &b->key);
1200         bkey_copy_key(k, &ZERO_KEY);
1201
1202         for (i = 0; i < KEY_PTRS(k); i++)
1203                 SET_PTR_GEN(k, i,
1204                             bch_inc_gen(PTR_CACHE(b->c, &b->key, i),
1205                                         PTR_BUCKET(b->c, &b->key, i)));
1206
1207         mutex_unlock(&b->c->bucket_lock);
1208 }
1209
1210 static int btree_check_reserve(struct btree *b, struct btree_op *op)
1211 {
1212         struct cache_set *c = b->c;
1213         struct cache *ca;
1214         unsigned int i, reserve = (c->root->level - b->level) * 2 + 1;
1215
1216         mutex_lock(&c->bucket_lock);
1217
1218         for_each_cache(ca, c, i)
1219                 if (fifo_used(&ca->free[RESERVE_BTREE]) < reserve) {
1220                         if (op)
1221                                 prepare_to_wait(&c->btree_cache_wait, &op->wait,
1222                                                 TASK_UNINTERRUPTIBLE);
1223                         mutex_unlock(&c->bucket_lock);
1224                         return -EINTR;
1225                 }
1226
1227         mutex_unlock(&c->bucket_lock);
1228
1229         return mca_cannibalize_lock(b->c, op);
1230 }
1231
1232 /* Garbage collection */
1233
1234 static uint8_t __bch_btree_mark_key(struct cache_set *c, int level,
1235                                     struct bkey *k)
1236 {
1237         uint8_t stale = 0;
1238         unsigned int i;
1239         struct bucket *g;
1240
1241         /*
1242          * ptr_invalid() can't return true for the keys that mark btree nodes as
1243          * freed, but since ptr_bad() returns true we'll never actually use them
1244          * for anything and thus we don't want mark their pointers here
1245          */
1246         if (!bkey_cmp(k, &ZERO_KEY))
1247                 return stale;
1248
1249         for (i = 0; i < KEY_PTRS(k); i++) {
1250                 if (!ptr_available(c, k, i))
1251                         continue;
1252
1253                 g = PTR_BUCKET(c, k, i);
1254
1255                 if (gen_after(g->last_gc, PTR_GEN(k, i)))
1256                         g->last_gc = PTR_GEN(k, i);
1257
1258                 if (ptr_stale(c, k, i)) {
1259                         stale = max(stale, ptr_stale(c, k, i));
1260                         continue;
1261                 }
1262
1263                 cache_bug_on(GC_MARK(g) &&
1264                              (GC_MARK(g) == GC_MARK_METADATA) != (level != 0),
1265                              c, "inconsistent ptrs: mark = %llu, level = %i",
1266                              GC_MARK(g), level);
1267
1268                 if (level)
1269                         SET_GC_MARK(g, GC_MARK_METADATA);
1270                 else if (KEY_DIRTY(k))
1271                         SET_GC_MARK(g, GC_MARK_DIRTY);
1272                 else if (!GC_MARK(g))
1273                         SET_GC_MARK(g, GC_MARK_RECLAIMABLE);
1274
1275                 /* guard against overflow */
1276                 SET_GC_SECTORS_USED(g, min_t(unsigned int,
1277                                              GC_SECTORS_USED(g) + KEY_SIZE(k),
1278                                              MAX_GC_SECTORS_USED));
1279
1280                 BUG_ON(!GC_SECTORS_USED(g));
1281         }
1282
1283         return stale;
1284 }
1285
1286 #define btree_mark_key(b, k)    __bch_btree_mark_key(b->c, b->level, k)
1287
1288 void bch_initial_mark_key(struct cache_set *c, int level, struct bkey *k)
1289 {
1290         unsigned int i;
1291
1292         for (i = 0; i < KEY_PTRS(k); i++)
1293                 if (ptr_available(c, k, i) &&
1294                     !ptr_stale(c, k, i)) {
1295                         struct bucket *b = PTR_BUCKET(c, k, i);
1296
1297                         b->gen = PTR_GEN(k, i);
1298
1299                         if (level && bkey_cmp(k, &ZERO_KEY))
1300                                 b->prio = BTREE_PRIO;
1301                         else if (!level && b->prio == BTREE_PRIO)
1302                                 b->prio = INITIAL_PRIO;
1303                 }
1304
1305         __bch_btree_mark_key(c, level, k);
1306 }
1307
1308 void bch_update_bucket_in_use(struct cache_set *c, struct gc_stat *stats)
1309 {
1310         stats->in_use = (c->nbuckets - c->avail_nbuckets) * 100 / c->nbuckets;
1311 }
1312
1313 static bool btree_gc_mark_node(struct btree *b, struct gc_stat *gc)
1314 {
1315         uint8_t stale = 0;
1316         unsigned int keys = 0, good_keys = 0;
1317         struct bkey *k;
1318         struct btree_iter iter;
1319         struct bset_tree *t;
1320
1321         gc->nodes++;
1322
1323         for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid) {
1324                 stale = max(stale, btree_mark_key(b, k));
1325                 keys++;
1326
1327                 if (bch_ptr_bad(&b->keys, k))
1328                         continue;
1329
1330                 gc->key_bytes += bkey_u64s(k);
1331                 gc->nkeys++;
1332                 good_keys++;
1333
1334                 gc->data += KEY_SIZE(k);
1335         }
1336
1337         for (t = b->keys.set; t <= &b->keys.set[b->keys.nsets]; t++)
1338                 btree_bug_on(t->size &&
1339                              bset_written(&b->keys, t) &&
1340                              bkey_cmp(&b->key, &t->end) < 0,
1341                              b, "found short btree key in gc");
1342
1343         if (b->c->gc_always_rewrite)
1344                 return true;
1345
1346         if (stale > 10)
1347                 return true;
1348
1349         if ((keys - good_keys) * 2 > keys)
1350                 return true;
1351
1352         return false;
1353 }
1354
1355 #define GC_MERGE_NODES  4U
1356
1357 struct gc_merge_info {
1358         struct btree    *b;
1359         unsigned int    keys;
1360 };
1361
1362 static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
1363                                  struct keylist *insert_keys,
1364                                  atomic_t *journal_ref,
1365                                  struct bkey *replace_key);
1366
1367 static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
1368                              struct gc_stat *gc, struct gc_merge_info *r)
1369 {
1370         unsigned int i, nodes = 0, keys = 0, blocks;
1371         struct btree *new_nodes[GC_MERGE_NODES];
1372         struct keylist keylist;
1373         struct closure cl;
1374         struct bkey *k;
1375
1376         bch_keylist_init(&keylist);
1377
1378         if (btree_check_reserve(b, NULL))
1379                 return 0;
1380
1381         memset(new_nodes, 0, sizeof(new_nodes));
1382         closure_init_stack(&cl);
1383
1384         while (nodes < GC_MERGE_NODES && !IS_ERR_OR_NULL(r[nodes].b))
1385                 keys += r[nodes++].keys;
1386
1387         blocks = btree_default_blocks(b->c) * 2 / 3;
1388
1389         if (nodes < 2 ||
1390             __set_blocks(b->keys.set[0].data, keys,
1391                          block_bytes(b->c)) > blocks * (nodes - 1))
1392                 return 0;
1393
1394         for (i = 0; i < nodes; i++) {
1395                 new_nodes[i] = btree_node_alloc_replacement(r[i].b, NULL);
1396                 if (IS_ERR_OR_NULL(new_nodes[i]))
1397                         goto out_nocoalesce;
1398         }
1399
1400         /*
1401          * We have to check the reserve here, after we've allocated our new
1402          * nodes, to make sure the insert below will succeed - we also check
1403          * before as an optimization to potentially avoid a bunch of expensive
1404          * allocs/sorts
1405          */
1406         if (btree_check_reserve(b, NULL))
1407                 goto out_nocoalesce;
1408
1409         for (i = 0; i < nodes; i++)
1410                 mutex_lock(&new_nodes[i]->write_lock);
1411
1412         for (i = nodes - 1; i > 0; --i) {
1413                 struct bset *n1 = btree_bset_first(new_nodes[i]);
1414                 struct bset *n2 = btree_bset_first(new_nodes[i - 1]);
1415                 struct bkey *k, *last = NULL;
1416
1417                 keys = 0;
1418
1419                 if (i > 1) {
1420                         for (k = n2->start;
1421                              k < bset_bkey_last(n2);
1422                              k = bkey_next(k)) {
1423                                 if (__set_blocks(n1, n1->keys + keys +
1424                                                  bkey_u64s(k),
1425                                                  block_bytes(b->c)) > blocks)
1426                                         break;
1427
1428                                 last = k;
1429                                 keys += bkey_u64s(k);
1430                         }
1431                 } else {
1432                         /*
1433                          * Last node we're not getting rid of - we're getting
1434                          * rid of the node at r[0]. Have to try and fit all of
1435                          * the remaining keys into this node; we can't ensure
1436                          * they will always fit due to rounding and variable
1437                          * length keys (shouldn't be possible in practice,
1438                          * though)
1439                          */
1440                         if (__set_blocks(n1, n1->keys + n2->keys,
1441                                          block_bytes(b->c)) >
1442                             btree_blocks(new_nodes[i]))
1443                                 goto out_nocoalesce;
1444
1445                         keys = n2->keys;
1446                         /* Take the key of the node we're getting rid of */
1447                         last = &r->b->key;
1448                 }
1449
1450                 BUG_ON(__set_blocks(n1, n1->keys + keys, block_bytes(b->c)) >
1451                        btree_blocks(new_nodes[i]));
1452
1453                 if (last)
1454                         bkey_copy_key(&new_nodes[i]->key, last);
1455
1456                 memcpy(bset_bkey_last(n1),
1457                        n2->start,
1458                        (void *) bset_bkey_idx(n2, keys) - (void *) n2->start);
1459
1460                 n1->keys += keys;
1461                 r[i].keys = n1->keys;
1462
1463                 memmove(n2->start,
1464                         bset_bkey_idx(n2, keys),
1465                         (void *) bset_bkey_last(n2) -
1466                         (void *) bset_bkey_idx(n2, keys));
1467
1468                 n2->keys -= keys;
1469
1470                 if (__bch_keylist_realloc(&keylist,
1471                                           bkey_u64s(&new_nodes[i]->key)))
1472                         goto out_nocoalesce;
1473
1474                 bch_btree_node_write(new_nodes[i], &cl);
1475                 bch_keylist_add(&keylist, &new_nodes[i]->key);
1476         }
1477
1478         for (i = 0; i < nodes; i++)
1479                 mutex_unlock(&new_nodes[i]->write_lock);
1480
1481         closure_sync(&cl);
1482
1483         /* We emptied out this node */
1484         BUG_ON(btree_bset_first(new_nodes[0])->keys);
1485         btree_node_free(new_nodes[0]);
1486         rw_unlock(true, new_nodes[0]);
1487         new_nodes[0] = NULL;
1488
1489         for (i = 0; i < nodes; i++) {
1490                 if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b->key)))
1491                         goto out_nocoalesce;
1492
1493                 make_btree_freeing_key(r[i].b, keylist.top);
1494                 bch_keylist_push(&keylist);
1495         }
1496
1497         bch_btree_insert_node(b, op, &keylist, NULL, NULL);
1498         BUG_ON(!bch_keylist_empty(&keylist));
1499
1500         for (i = 0; i < nodes; i++) {
1501                 btree_node_free(r[i].b);
1502                 rw_unlock(true, r[i].b);
1503
1504                 r[i].b = new_nodes[i];
1505         }
1506
1507         memmove(r, r + 1, sizeof(r[0]) * (nodes - 1));
1508         r[nodes - 1].b = ERR_PTR(-EINTR);
1509
1510         trace_bcache_btree_gc_coalesce(nodes);
1511         gc->nodes--;
1512
1513         bch_keylist_free(&keylist);
1514
1515         /* Invalidated our iterator */
1516         return -EINTR;
1517
1518 out_nocoalesce:
1519         closure_sync(&cl);
1520
1521         while ((k = bch_keylist_pop(&keylist)))
1522                 if (!bkey_cmp(k, &ZERO_KEY))
1523                         atomic_dec(&b->c->prio_blocked);
1524         bch_keylist_free(&keylist);
1525
1526         for (i = 0; i < nodes; i++)
1527                 if (!IS_ERR_OR_NULL(new_nodes[i])) {
1528                         btree_node_free(new_nodes[i]);
1529                         rw_unlock(true, new_nodes[i]);
1530                 }
1531         return 0;
1532 }
1533
1534 static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op,
1535                                  struct btree *replace)
1536 {
1537         struct keylist keys;
1538         struct btree *n;
1539
1540         if (btree_check_reserve(b, NULL))
1541                 return 0;
1542
1543         n = btree_node_alloc_replacement(replace, NULL);
1544
1545         /* recheck reserve after allocating replacement node */
1546         if (btree_check_reserve(b, NULL)) {
1547                 btree_node_free(n);
1548                 rw_unlock(true, n);
1549                 return 0;
1550         }
1551
1552         bch_btree_node_write_sync(n);
1553
1554         bch_keylist_init(&keys);
1555         bch_keylist_add(&keys, &n->key);
1556
1557         make_btree_freeing_key(replace, keys.top);
1558         bch_keylist_push(&keys);
1559
1560         bch_btree_insert_node(b, op, &keys, NULL, NULL);
1561         BUG_ON(!bch_keylist_empty(&keys));
1562
1563         btree_node_free(replace);
1564         rw_unlock(true, n);
1565
1566         /* Invalidated our iterator */
1567         return -EINTR;
1568 }
1569
1570 static unsigned int btree_gc_count_keys(struct btree *b)
1571 {
1572         struct bkey *k;
1573         struct btree_iter iter;
1574         unsigned int ret = 0;
1575
1576         for_each_key_filter(&b->keys, k, &iter, bch_ptr_bad)
1577                 ret += bkey_u64s(k);
1578
1579         return ret;
1580 }
1581
1582 static size_t btree_gc_min_nodes(struct cache_set *c)
1583 {
1584         size_t min_nodes;
1585
1586         /*
1587          * Since incremental GC would stop 100ms when front
1588          * side I/O comes, so when there are many btree nodes,
1589          * if GC only processes constant (100) nodes each time,
1590          * GC would last a long time, and the front side I/Os
1591          * would run out of the buckets (since no new bucket
1592          * can be allocated during GC), and be blocked again.
1593          * So GC should not process constant nodes, but varied
1594          * nodes according to the number of btree nodes, which
1595          * realized by dividing GC into constant(100) times,
1596          * so when there are many btree nodes, GC can process
1597          * more nodes each time, otherwise, GC will process less
1598          * nodes each time (but no less than MIN_GC_NODES)
1599          */
1600         min_nodes = c->gc_stats.nodes / MAX_GC_TIMES;
1601         if (min_nodes < MIN_GC_NODES)
1602                 min_nodes = MIN_GC_NODES;
1603
1604         return min_nodes;
1605 }
1606
1607
1608 static int btree_gc_recurse(struct btree *b, struct btree_op *op,
1609                             struct closure *writes, struct gc_stat *gc)
1610 {
1611         int ret = 0;
1612         bool should_rewrite;
1613         struct bkey *k;
1614         struct btree_iter iter;
1615         struct gc_merge_info r[GC_MERGE_NODES];
1616         struct gc_merge_info *i, *last = r + ARRAY_SIZE(r) - 1;
1617
1618         bch_btree_iter_init(&b->keys, &iter, &b->c->gc_done);
1619
1620         for (i = r; i < r + ARRAY_SIZE(r); i++)
1621                 i->b = ERR_PTR(-EINTR);
1622
1623         while (1) {
1624                 k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad);
1625                 if (k) {
1626                         r->b = bch_btree_node_get(b->c, op, k, b->level - 1,
1627                                                   true, b);
1628                         if (IS_ERR(r->b)) {
1629                                 ret = PTR_ERR(r->b);
1630                                 break;
1631                         }
1632
1633                         r->keys = btree_gc_count_keys(r->b);
1634
1635                         ret = btree_gc_coalesce(b, op, gc, r);
1636                         if (ret)
1637                                 break;
1638                 }
1639
1640                 if (!last->b)
1641                         break;
1642
1643                 if (!IS_ERR(last->b)) {
1644                         should_rewrite = btree_gc_mark_node(last->b, gc);
1645                         if (should_rewrite) {
1646                                 ret = btree_gc_rewrite_node(b, op, last->b);
1647                                 if (ret)
1648                                         break;
1649                         }
1650
1651                         if (last->b->level) {
1652                                 ret = btree_gc_recurse(last->b, op, writes, gc);
1653                                 if (ret)
1654                                         break;
1655                         }
1656
1657                         bkey_copy_key(&b->c->gc_done, &last->b->key);
1658
1659                         /*
1660                          * Must flush leaf nodes before gc ends, since replace
1661                          * operations aren't journalled
1662                          */
1663                         mutex_lock(&last->b->write_lock);
1664                         if (btree_node_dirty(last->b))
1665                                 bch_btree_node_write(last->b, writes);
1666                         mutex_unlock(&last->b->write_lock);
1667                         rw_unlock(true, last->b);
1668                 }
1669
1670                 memmove(r + 1, r, sizeof(r[0]) * (GC_MERGE_NODES - 1));
1671                 r->b = NULL;
1672
1673                 if (atomic_read(&b->c->search_inflight) &&
1674                     gc->nodes >= gc->nodes_pre + btree_gc_min_nodes(b->c)) {
1675                         gc->nodes_pre =  gc->nodes;
1676                         ret = -EAGAIN;
1677                         break;
1678                 }
1679
1680                 if (need_resched()) {
1681                         ret = -EAGAIN;
1682                         break;
1683                 }
1684         }
1685
1686         for (i = r; i < r + ARRAY_SIZE(r); i++)
1687                 if (!IS_ERR_OR_NULL(i->b)) {
1688                         mutex_lock(&i->b->write_lock);
1689                         if (btree_node_dirty(i->b))
1690                                 bch_btree_node_write(i->b, writes);
1691                         mutex_unlock(&i->b->write_lock);
1692                         rw_unlock(true, i->b);
1693                 }
1694
1695         return ret;
1696 }
1697
1698 static int bch_btree_gc_root(struct btree *b, struct btree_op *op,
1699                              struct closure *writes, struct gc_stat *gc)
1700 {
1701         struct btree *n = NULL;
1702         int ret = 0;
1703         bool should_rewrite;
1704
1705         should_rewrite = btree_gc_mark_node(b, gc);
1706         if (should_rewrite) {
1707                 n = btree_node_alloc_replacement(b, NULL);
1708
1709                 if (!IS_ERR_OR_NULL(n)) {
1710                         bch_btree_node_write_sync(n);
1711
1712                         bch_btree_set_root(n);
1713                         btree_node_free(b);
1714                         rw_unlock(true, n);
1715
1716                         return -EINTR;
1717                 }
1718         }
1719
1720         __bch_btree_mark_key(b->c, b->level + 1, &b->key);
1721
1722         if (b->level) {
1723                 ret = btree_gc_recurse(b, op, writes, gc);
1724                 if (ret)
1725                         return ret;
1726         }
1727
1728         bkey_copy_key(&b->c->gc_done, &b->key);
1729
1730         return ret;
1731 }
1732
1733 static void btree_gc_start(struct cache_set *c)
1734 {
1735         struct cache *ca;
1736         struct bucket *b;
1737         unsigned int i;
1738
1739         if (!c->gc_mark_valid)
1740                 return;
1741
1742         mutex_lock(&c->bucket_lock);
1743
1744         c->gc_mark_valid = 0;
1745         c->gc_done = ZERO_KEY;
1746
1747         for_each_cache(ca, c, i)
1748                 for_each_bucket(b, ca) {
1749                         b->last_gc = b->gen;
1750                         if (!atomic_read(&b->pin)) {
1751                                 SET_GC_MARK(b, 0);
1752                                 SET_GC_SECTORS_USED(b, 0);
1753                         }
1754                 }
1755
1756         mutex_unlock(&c->bucket_lock);
1757 }
1758
1759 static void bch_btree_gc_finish(struct cache_set *c)
1760 {
1761         struct bucket *b;
1762         struct cache *ca;
1763         unsigned int i;
1764
1765         mutex_lock(&c->bucket_lock);
1766
1767         set_gc_sectors(c);
1768         c->gc_mark_valid = 1;
1769         c->need_gc      = 0;
1770
1771         for (i = 0; i < KEY_PTRS(&c->uuid_bucket); i++)
1772                 SET_GC_MARK(PTR_BUCKET(c, &c->uuid_bucket, i),
1773                             GC_MARK_METADATA);
1774
1775         /* don't reclaim buckets to which writeback keys point */
1776         rcu_read_lock();
1777         for (i = 0; i < c->devices_max_used; i++) {
1778                 struct bcache_device *d = c->devices[i];
1779                 struct cached_dev *dc;
1780                 struct keybuf_key *w, *n;
1781                 unsigned int j;
1782
1783                 if (!d || UUID_FLASH_ONLY(&c->uuids[i]))
1784                         continue;
1785                 dc = container_of(d, struct cached_dev, disk);
1786
1787                 spin_lock(&dc->writeback_keys.lock);
1788                 rbtree_postorder_for_each_entry_safe(w, n,
1789                                         &dc->writeback_keys.keys, node)
1790                         for (j = 0; j < KEY_PTRS(&w->key); j++)
1791                                 SET_GC_MARK(PTR_BUCKET(c, &w->key, j),
1792                                             GC_MARK_DIRTY);
1793                 spin_unlock(&dc->writeback_keys.lock);
1794         }
1795         rcu_read_unlock();
1796
1797         c->avail_nbuckets = 0;
1798         for_each_cache(ca, c, i) {
1799                 uint64_t *i;
1800
1801                 ca->invalidate_needs_gc = 0;
1802
1803                 for (i = ca->sb.d; i < ca->sb.d + ca->sb.keys; i++)
1804                         SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
1805
1806                 for (i = ca->prio_buckets;
1807                      i < ca->prio_buckets + prio_buckets(ca) * 2; i++)
1808                         SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
1809
1810                 for_each_bucket(b, ca) {
1811                         c->need_gc      = max(c->need_gc, bucket_gc_gen(b));
1812
1813                         if (atomic_read(&b->pin))
1814                                 continue;
1815
1816                         BUG_ON(!GC_MARK(b) && GC_SECTORS_USED(b));
1817
1818                         if (!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE)
1819                                 c->avail_nbuckets++;
1820                 }
1821         }
1822
1823         mutex_unlock(&c->bucket_lock);
1824 }
1825
1826 static void bch_btree_gc(struct cache_set *c)
1827 {
1828         int ret;
1829         struct gc_stat stats;
1830         struct closure writes;
1831         struct btree_op op;
1832         uint64_t start_time = local_clock();
1833
1834         trace_bcache_gc_start(c);
1835
1836         memset(&stats, 0, sizeof(struct gc_stat));
1837         closure_init_stack(&writes);
1838         bch_btree_op_init(&op, SHRT_MAX);
1839
1840         btree_gc_start(c);
1841
1842         /* if CACHE_SET_IO_DISABLE set, gc thread should stop too */
1843         do {
1844                 ret = btree_root(gc_root, c, &op, &writes, &stats);
1845                 closure_sync(&writes);
1846                 cond_resched();
1847
1848                 if (ret == -EAGAIN)
1849                         schedule_timeout_interruptible(msecs_to_jiffies
1850                                                        (GC_SLEEP_MS));
1851                 else if (ret)
1852                         pr_warn("gc failed!");
1853         } while (ret && !test_bit(CACHE_SET_IO_DISABLE, &c->flags));
1854
1855         bch_btree_gc_finish(c);
1856         wake_up_allocators(c);
1857
1858         bch_time_stats_update(&c->btree_gc_time, start_time);
1859
1860         stats.key_bytes *= sizeof(uint64_t);
1861         stats.data      <<= 9;
1862         bch_update_bucket_in_use(c, &stats);
1863         memcpy(&c->gc_stats, &stats, sizeof(struct gc_stat));
1864
1865         trace_bcache_gc_end(c);
1866
1867         bch_moving_gc(c);
1868 }
1869
1870 static bool gc_should_run(struct cache_set *c)
1871 {
1872         struct cache *ca;
1873         unsigned int i;
1874
1875         for_each_cache(ca, c, i)
1876                 if (ca->invalidate_needs_gc)
1877                         return true;
1878
1879         if (atomic_read(&c->sectors_to_gc) < 0)
1880                 return true;
1881
1882         return false;
1883 }
1884
1885 static int bch_gc_thread(void *arg)
1886 {
1887         struct cache_set *c = arg;
1888
1889         while (1) {
1890                 wait_event_interruptible(c->gc_wait,
1891                            kthread_should_stop() ||
1892                            test_bit(CACHE_SET_IO_DISABLE, &c->flags) ||
1893                            gc_should_run(c));
1894
1895                 if (kthread_should_stop() ||
1896                     test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1897                         break;
1898
1899                 set_gc_sectors(c);
1900                 bch_btree_gc(c);
1901         }
1902
1903         wait_for_kthread_stop();
1904         return 0;
1905 }
1906
1907 int bch_gc_thread_start(struct cache_set *c)
1908 {
1909         c->gc_thread = kthread_run(bch_gc_thread, c, "bcache_gc");
1910         return PTR_ERR_OR_ZERO(c->gc_thread);
1911 }
1912
1913 /* Initial partial gc */
1914
1915 static int bch_btree_check_recurse(struct btree *b, struct btree_op *op)
1916 {
1917         int ret = 0;
1918         struct bkey *k, *p = NULL;
1919         struct btree_iter iter;
1920
1921         for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid)
1922                 bch_initial_mark_key(b->c, b->level, k);
1923
1924         bch_initial_mark_key(b->c, b->level + 1, &b->key);
1925
1926         if (b->level) {
1927                 bch_btree_iter_init(&b->keys, &iter, NULL);
1928
1929                 do {
1930                         k = bch_btree_iter_next_filter(&iter, &b->keys,
1931                                                        bch_ptr_bad);
1932                         if (k) {
1933                                 btree_node_prefetch(b, k);
1934                                 /*
1935                                  * initiallize c->gc_stats.nodes
1936                                  * for incremental GC
1937                                  */
1938                                 b->c->gc_stats.nodes++;
1939                         }
1940
1941                         if (p)
1942                                 ret = btree(check_recurse, p, b, op);
1943
1944                         p = k;
1945                 } while (p && !ret);
1946         }
1947
1948         return ret;
1949 }
1950
1951 int bch_btree_check(struct cache_set *c)
1952 {
1953         struct btree_op op;
1954
1955         bch_btree_op_init(&op, SHRT_MAX);
1956
1957         return btree_root(check_recurse, c, &op);
1958 }
1959
1960 void bch_initial_gc_finish(struct cache_set *c)
1961 {
1962         struct cache *ca;
1963         struct bucket *b;
1964         unsigned int i;
1965
1966         bch_btree_gc_finish(c);
1967
1968         mutex_lock(&c->bucket_lock);
1969
1970         /*
1971          * We need to put some unused buckets directly on the prio freelist in
1972          * order to get the allocator thread started - it needs freed buckets in
1973          * order to rewrite the prios and gens, and it needs to rewrite prios
1974          * and gens in order to free buckets.
1975          *
1976          * This is only safe for buckets that have no live data in them, which
1977          * there should always be some of.
1978          */
1979         for_each_cache(ca, c, i) {
1980                 for_each_bucket(b, ca) {
1981                         if (fifo_full(&ca->free[RESERVE_PRIO]) &&
1982                             fifo_full(&ca->free[RESERVE_BTREE]))
1983                                 break;
1984
1985                         if (bch_can_invalidate_bucket(ca, b) &&
1986                             !GC_MARK(b)) {
1987                                 __bch_invalidate_one_bucket(ca, b);
1988                                 if (!fifo_push(&ca->free[RESERVE_PRIO],
1989                                    b - ca->buckets))
1990                                         fifo_push(&ca->free[RESERVE_BTREE],
1991                                                   b - ca->buckets);
1992                         }
1993                 }
1994         }
1995
1996         mutex_unlock(&c->bucket_lock);
1997 }
1998
1999 /* Btree insertion */
2000
2001 static bool btree_insert_key(struct btree *b, struct bkey *k,
2002                              struct bkey *replace_key)
2003 {
2004         unsigned int status;
2005
2006         BUG_ON(bkey_cmp(k, &b->key) > 0);
2007
2008         status = bch_btree_insert_key(&b->keys, k, replace_key);
2009         if (status != BTREE_INSERT_STATUS_NO_INSERT) {
2010                 bch_check_keys(&b->keys, "%u for %s", status,
2011                                replace_key ? "replace" : "insert");
2012
2013                 trace_bcache_btree_insert_key(b, k, replace_key != NULL,
2014                                               status);
2015                 return true;
2016         } else
2017                 return false;
2018 }
2019
2020 static size_t insert_u64s_remaining(struct btree *b)
2021 {
2022         long ret = bch_btree_keys_u64s_remaining(&b->keys);
2023
2024         /*
2025          * Might land in the middle of an existing extent and have to split it
2026          */
2027         if (b->keys.ops->is_extents)
2028                 ret -= KEY_MAX_U64S;
2029
2030         return max(ret, 0L);
2031 }
2032
2033 static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
2034                                   struct keylist *insert_keys,
2035                                   struct bkey *replace_key)
2036 {
2037         bool ret = false;
2038         int oldsize = bch_count_data(&b->keys);
2039
2040         while (!bch_keylist_empty(insert_keys)) {
2041                 struct bkey *k = insert_keys->keys;
2042
2043                 if (bkey_u64s(k) > insert_u64s_remaining(b))
2044                         break;
2045
2046                 if (bkey_cmp(k, &b->key) <= 0) {
2047                         if (!b->level)
2048                                 bkey_put(b->c, k);
2049
2050                         ret |= btree_insert_key(b, k, replace_key);
2051                         bch_keylist_pop_front(insert_keys);
2052                 } else if (bkey_cmp(&START_KEY(k), &b->key) < 0) {
2053                         BKEY_PADDED(key) temp;
2054                         bkey_copy(&temp.key, insert_keys->keys);
2055
2056                         bch_cut_back(&b->key, &temp.key);
2057                         bch_cut_front(&b->key, insert_keys->keys);
2058
2059                         ret |= btree_insert_key(b, &temp.key, replace_key);
2060                         break;
2061                 } else {
2062                         break;
2063                 }
2064         }
2065
2066         if (!ret)
2067                 op->insert_collision = true;
2068
2069         BUG_ON(!bch_keylist_empty(insert_keys) && b->level);
2070
2071         BUG_ON(bch_count_data(&b->keys) < oldsize);
2072         return ret;
2073 }
2074
2075 static int btree_split(struct btree *b, struct btree_op *op,
2076                        struct keylist *insert_keys,
2077                        struct bkey *replace_key)
2078 {
2079         bool split;
2080         struct btree *n1, *n2 = NULL, *n3 = NULL;
2081         uint64_t start_time = local_clock();
2082         struct closure cl;
2083         struct keylist parent_keys;
2084
2085         closure_init_stack(&cl);
2086         bch_keylist_init(&parent_keys);
2087
2088         if (btree_check_reserve(b, op)) {
2089                 if (!b->level)
2090                         return -EINTR;
2091                 else
2092                         WARN(1, "insufficient reserve for split\n");
2093         }
2094
2095         n1 = btree_node_alloc_replacement(b, op);
2096         if (IS_ERR(n1))
2097                 goto err;
2098
2099         split = set_blocks(btree_bset_first(n1),
2100                            block_bytes(n1->c)) > (btree_blocks(b) * 4) / 5;
2101
2102         if (split) {
2103                 unsigned int keys = 0;
2104
2105                 trace_bcache_btree_node_split(b, btree_bset_first(n1)->keys);
2106
2107                 n2 = bch_btree_node_alloc(b->c, op, b->level, b->parent);
2108                 if (IS_ERR(n2))
2109                         goto err_free1;
2110
2111                 if (!b->parent) {
2112                         n3 = bch_btree_node_alloc(b->c, op, b->level + 1, NULL);
2113                         if (IS_ERR(n3))
2114                                 goto err_free2;
2115                 }
2116
2117                 mutex_lock(&n1->write_lock);
2118                 mutex_lock(&n2->write_lock);
2119
2120                 bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2121
2122                 /*
2123                  * Has to be a linear search because we don't have an auxiliary
2124                  * search tree yet
2125                  */
2126
2127                 while (keys < (btree_bset_first(n1)->keys * 3) / 5)
2128                         keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1),
2129                                                         keys));
2130
2131                 bkey_copy_key(&n1->key,
2132                               bset_bkey_idx(btree_bset_first(n1), keys));
2133                 keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1), keys));
2134
2135                 btree_bset_first(n2)->keys = btree_bset_first(n1)->keys - keys;
2136                 btree_bset_first(n1)->keys = keys;
2137
2138                 memcpy(btree_bset_first(n2)->start,
2139                        bset_bkey_last(btree_bset_first(n1)),
2140                        btree_bset_first(n2)->keys * sizeof(uint64_t));
2141
2142                 bkey_copy_key(&n2->key, &b->key);
2143
2144                 bch_keylist_add(&parent_keys, &n2->key);
2145                 bch_btree_node_write(n2, &cl);
2146                 mutex_unlock(&n2->write_lock);
2147                 rw_unlock(true, n2);
2148         } else {
2149                 trace_bcache_btree_node_compact(b, btree_bset_first(n1)->keys);
2150
2151                 mutex_lock(&n1->write_lock);
2152                 bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2153         }
2154
2155         bch_keylist_add(&parent_keys, &n1->key);
2156         bch_btree_node_write(n1, &cl);
2157         mutex_unlock(&n1->write_lock);
2158
2159         if (n3) {
2160                 /* Depth increases, make a new root */
2161                 mutex_lock(&n3->write_lock);
2162                 bkey_copy_key(&n3->key, &MAX_KEY);
2163                 bch_btree_insert_keys(n3, op, &parent_keys, NULL);
2164                 bch_btree_node_write(n3, &cl);
2165                 mutex_unlock(&n3->write_lock);
2166
2167                 closure_sync(&cl);
2168                 bch_btree_set_root(n3);
2169                 rw_unlock(true, n3);
2170         } else if (!b->parent) {
2171                 /* Root filled up but didn't need to be split */
2172                 closure_sync(&cl);
2173                 bch_btree_set_root(n1);
2174         } else {
2175                 /* Split a non root node */
2176                 closure_sync(&cl);
2177                 make_btree_freeing_key(b, parent_keys.top);
2178                 bch_keylist_push(&parent_keys);
2179
2180                 bch_btree_insert_node(b->parent, op, &parent_keys, NULL, NULL);
2181                 BUG_ON(!bch_keylist_empty(&parent_keys));
2182         }
2183
2184         btree_node_free(b);
2185         rw_unlock(true, n1);
2186
2187         bch_time_stats_update(&b->c->btree_split_time, start_time);
2188
2189         return 0;
2190 err_free2:
2191         bkey_put(b->c, &n2->key);
2192         btree_node_free(n2);
2193         rw_unlock(true, n2);
2194 err_free1:
2195         bkey_put(b->c, &n1->key);
2196         btree_node_free(n1);
2197         rw_unlock(true, n1);
2198 err:
2199         WARN(1, "bcache: btree split failed (level %u)", b->level);
2200
2201         if (n3 == ERR_PTR(-EAGAIN) ||
2202             n2 == ERR_PTR(-EAGAIN) ||
2203             n1 == ERR_PTR(-EAGAIN))
2204                 return -EAGAIN;
2205
2206         return -ENOMEM;
2207 }
2208
2209 static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
2210                                  struct keylist *insert_keys,
2211                                  atomic_t *journal_ref,
2212                                  struct bkey *replace_key)
2213 {
2214         struct closure cl;
2215
2216         BUG_ON(b->level && replace_key);
2217
2218         closure_init_stack(&cl);
2219
2220         mutex_lock(&b->write_lock);
2221
2222         if (write_block(b) != btree_bset_last(b) &&
2223             b->keys.last_set_unwritten)
2224                 bch_btree_init_next(b); /* just wrote a set */
2225
2226         if (bch_keylist_nkeys(insert_keys) > insert_u64s_remaining(b)) {
2227                 mutex_unlock(&b->write_lock);
2228                 goto split;
2229         }
2230
2231         BUG_ON(write_block(b) != btree_bset_last(b));
2232
2233         if (bch_btree_insert_keys(b, op, insert_keys, replace_key)) {
2234                 if (!b->level)
2235                         bch_btree_leaf_dirty(b, journal_ref);
2236                 else
2237                         bch_btree_node_write(b, &cl);
2238         }
2239
2240         mutex_unlock(&b->write_lock);
2241
2242         /* wait for btree node write if necessary, after unlock */
2243         closure_sync(&cl);
2244
2245         return 0;
2246 split:
2247         if (current->bio_list) {
2248                 op->lock = b->c->root->level + 1;
2249                 return -EAGAIN;
2250         } else if (op->lock <= b->c->root->level) {
2251                 op->lock = b->c->root->level + 1;
2252                 return -EINTR;
2253         } else {
2254                 /* Invalidated all iterators */
2255                 int ret = btree_split(b, op, insert_keys, replace_key);
2256
2257                 if (bch_keylist_empty(insert_keys))
2258                         return 0;
2259                 else if (!ret)
2260                         return -EINTR;
2261                 return ret;
2262         }
2263 }
2264
2265 int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
2266                                struct bkey *check_key)
2267 {
2268         int ret = -EINTR;
2269         uint64_t btree_ptr = b->key.ptr[0];
2270         unsigned long seq = b->seq;
2271         struct keylist insert;
2272         bool upgrade = op->lock == -1;
2273
2274         bch_keylist_init(&insert);
2275
2276         if (upgrade) {
2277                 rw_unlock(false, b);
2278                 rw_lock(true, b, b->level);
2279
2280                 if (b->key.ptr[0] != btree_ptr ||
2281                     b->seq != seq + 1) {
2282                         op->lock = b->level;
2283                         goto out;
2284                 }
2285         }
2286
2287         SET_KEY_PTRS(check_key, 1);
2288         get_random_bytes(&check_key->ptr[0], sizeof(uint64_t));
2289
2290         SET_PTR_DEV(check_key, 0, PTR_CHECK_DEV);
2291
2292         bch_keylist_add(&insert, check_key);
2293
2294         ret = bch_btree_insert_node(b, op, &insert, NULL, NULL);
2295
2296         BUG_ON(!ret && !bch_keylist_empty(&insert));
2297 out:
2298         if (upgrade)
2299                 downgrade_write(&b->lock);
2300         return ret;
2301 }
2302
2303 struct btree_insert_op {
2304         struct btree_op op;
2305         struct keylist  *keys;
2306         atomic_t        *journal_ref;
2307         struct bkey     *replace_key;
2308 };
2309
2310 static int btree_insert_fn(struct btree_op *b_op, struct btree *b)
2311 {
2312         struct btree_insert_op *op = container_of(b_op,
2313                                         struct btree_insert_op, op);
2314
2315         int ret = bch_btree_insert_node(b, &op->op, op->keys,
2316                                         op->journal_ref, op->replace_key);
2317         if (ret && !bch_keylist_empty(op->keys))
2318                 return ret;
2319         else
2320                 return MAP_DONE;
2321 }
2322
2323 int bch_btree_insert(struct cache_set *c, struct keylist *keys,
2324                      atomic_t *journal_ref, struct bkey *replace_key)
2325 {
2326         struct btree_insert_op op;
2327         int ret = 0;
2328
2329         BUG_ON(current->bio_list);
2330         BUG_ON(bch_keylist_empty(keys));
2331
2332         bch_btree_op_init(&op.op, 0);
2333         op.keys         = keys;
2334         op.journal_ref  = journal_ref;
2335         op.replace_key  = replace_key;
2336
2337         while (!ret && !bch_keylist_empty(keys)) {
2338                 op.op.lock = 0;
2339                 ret = bch_btree_map_leaf_nodes(&op.op, c,
2340                                                &START_KEY(keys->keys),
2341                                                btree_insert_fn);
2342         }
2343
2344         if (ret) {
2345                 struct bkey *k;
2346
2347                 pr_err("error %i", ret);
2348
2349                 while ((k = bch_keylist_pop(keys)))
2350                         bkey_put(c, k);
2351         } else if (op.op.insert_collision)
2352                 ret = -ESRCH;
2353
2354         return ret;
2355 }
2356
2357 void bch_btree_set_root(struct btree *b)
2358 {
2359         unsigned int i;
2360         struct closure cl;
2361
2362         closure_init_stack(&cl);
2363
2364         trace_bcache_btree_set_root(b);
2365
2366         BUG_ON(!b->written);
2367
2368         for (i = 0; i < KEY_PTRS(&b->key); i++)
2369                 BUG_ON(PTR_BUCKET(b->c, &b->key, i)->prio != BTREE_PRIO);
2370
2371         mutex_lock(&b->c->bucket_lock);
2372         list_del_init(&b->list);
2373         mutex_unlock(&b->c->bucket_lock);
2374
2375         b->c->root = b;
2376
2377         bch_journal_meta(b->c, &cl);
2378         closure_sync(&cl);
2379 }
2380
2381 /* Map across nodes or keys */
2382
2383 static int bch_btree_map_nodes_recurse(struct btree *b, struct btree_op *op,
2384                                        struct bkey *from,
2385                                        btree_map_nodes_fn *fn, int flags)
2386 {
2387         int ret = MAP_CONTINUE;
2388
2389         if (b->level) {
2390                 struct bkey *k;
2391                 struct btree_iter iter;
2392
2393                 bch_btree_iter_init(&b->keys, &iter, from);
2394
2395                 while ((k = bch_btree_iter_next_filter(&iter, &b->keys,
2396                                                        bch_ptr_bad))) {
2397                         ret = btree(map_nodes_recurse, k, b,
2398                                     op, from, fn, flags);
2399                         from = NULL;
2400
2401                         if (ret != MAP_CONTINUE)
2402                                 return ret;
2403                 }
2404         }
2405
2406         if (!b->level || flags == MAP_ALL_NODES)
2407                 ret = fn(op, b);
2408
2409         return ret;
2410 }
2411
2412 int __bch_btree_map_nodes(struct btree_op *op, struct cache_set *c,
2413                           struct bkey *from, btree_map_nodes_fn *fn, int flags)
2414 {
2415         return btree_root(map_nodes_recurse, c, op, from, fn, flags);
2416 }
2417
2418 static int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op,
2419                                       struct bkey *from, btree_map_keys_fn *fn,
2420                                       int flags)
2421 {
2422         int ret = MAP_CONTINUE;
2423         struct bkey *k;
2424         struct btree_iter iter;
2425
2426         bch_btree_iter_init(&b->keys, &iter, from);
2427
2428         while ((k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad))) {
2429                 ret = !b->level
2430                         ? fn(op, b, k)
2431                         : btree(map_keys_recurse, k, b, op, from, fn, flags);
2432                 from = NULL;
2433
2434                 if (ret != MAP_CONTINUE)
2435                         return ret;
2436         }
2437
2438         if (!b->level && (flags & MAP_END_KEY))
2439                 ret = fn(op, b, &KEY(KEY_INODE(&b->key),
2440                                      KEY_OFFSET(&b->key), 0));
2441
2442         return ret;
2443 }
2444
2445 int bch_btree_map_keys(struct btree_op *op, struct cache_set *c,
2446                        struct bkey *from, btree_map_keys_fn *fn, int flags)
2447 {
2448         return btree_root(map_keys_recurse, c, op, from, fn, flags);
2449 }
2450
2451 /* Keybuf code */
2452
2453 static inline int keybuf_cmp(struct keybuf_key *l, struct keybuf_key *r)
2454 {
2455         /* Overlapping keys compare equal */
2456         if (bkey_cmp(&l->key, &START_KEY(&r->key)) <= 0)
2457                 return -1;
2458         if (bkey_cmp(&START_KEY(&l->key), &r->key) >= 0)
2459                 return 1;
2460         return 0;
2461 }
2462
2463 static inline int keybuf_nonoverlapping_cmp(struct keybuf_key *l,
2464                                             struct keybuf_key *r)
2465 {
2466         return clamp_t(int64_t, bkey_cmp(&l->key, &r->key), -1, 1);
2467 }
2468
2469 struct refill {
2470         struct btree_op op;
2471         unsigned int    nr_found;
2472         struct keybuf   *buf;
2473         struct bkey     *end;
2474         keybuf_pred_fn  *pred;
2475 };
2476
2477 static int refill_keybuf_fn(struct btree_op *op, struct btree *b,
2478                             struct bkey *k)
2479 {
2480         struct refill *refill = container_of(op, struct refill, op);
2481         struct keybuf *buf = refill->buf;
2482         int ret = MAP_CONTINUE;
2483
2484         if (bkey_cmp(k, refill->end) > 0) {
2485                 ret = MAP_DONE;
2486                 goto out;
2487         }
2488
2489         if (!KEY_SIZE(k)) /* end key */
2490                 goto out;
2491
2492         if (refill->pred(buf, k)) {
2493                 struct keybuf_key *w;
2494
2495                 spin_lock(&buf->lock);
2496
2497                 w = array_alloc(&buf->freelist);
2498                 if (!w) {
2499                         spin_unlock(&buf->lock);
2500                         return MAP_DONE;
2501                 }
2502
2503                 w->private = NULL;
2504                 bkey_copy(&w->key, k);
2505
2506                 if (RB_INSERT(&buf->keys, w, node, keybuf_cmp))
2507                         array_free(&buf->freelist, w);
2508                 else
2509                         refill->nr_found++;
2510
2511                 if (array_freelist_empty(&buf->freelist))
2512                         ret = MAP_DONE;
2513
2514                 spin_unlock(&buf->lock);
2515         }
2516 out:
2517         buf->last_scanned = *k;
2518         return ret;
2519 }
2520
2521 void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
2522                        struct bkey *end, keybuf_pred_fn *pred)
2523 {
2524         struct bkey start = buf->last_scanned;
2525         struct refill refill;
2526
2527         cond_resched();
2528
2529         bch_btree_op_init(&refill.op, -1);
2530         refill.nr_found = 0;
2531         refill.buf      = buf;
2532         refill.end      = end;
2533         refill.pred     = pred;
2534
2535         bch_btree_map_keys(&refill.op, c, &buf->last_scanned,
2536                            refill_keybuf_fn, MAP_END_KEY);
2537
2538         trace_bcache_keyscan(refill.nr_found,
2539                              KEY_INODE(&start), KEY_OFFSET(&start),
2540                              KEY_INODE(&buf->last_scanned),
2541                              KEY_OFFSET(&buf->last_scanned));
2542
2543         spin_lock(&buf->lock);
2544
2545         if (!RB_EMPTY_ROOT(&buf->keys)) {
2546                 struct keybuf_key *w;
2547
2548                 w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2549                 buf->start      = START_KEY(&w->key);
2550
2551                 w = RB_LAST(&buf->keys, struct keybuf_key, node);
2552                 buf->end        = w->key;
2553         } else {
2554                 buf->start      = MAX_KEY;
2555                 buf->end        = MAX_KEY;
2556         }
2557
2558         spin_unlock(&buf->lock);
2559 }
2560
2561 static void __bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2562 {
2563         rb_erase(&w->node, &buf->keys);
2564         array_free(&buf->freelist, w);
2565 }
2566
2567 void bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2568 {
2569         spin_lock(&buf->lock);
2570         __bch_keybuf_del(buf, w);
2571         spin_unlock(&buf->lock);
2572 }
2573
2574 bool bch_keybuf_check_overlapping(struct keybuf *buf, struct bkey *start,
2575                                   struct bkey *end)
2576 {
2577         bool ret = false;
2578         struct keybuf_key *p, *w, s;
2579
2580         s.key = *start;
2581
2582         if (bkey_cmp(end, &buf->start) <= 0 ||
2583             bkey_cmp(start, &buf->end) >= 0)
2584                 return false;
2585
2586         spin_lock(&buf->lock);
2587         w = RB_GREATER(&buf->keys, s, node, keybuf_nonoverlapping_cmp);
2588
2589         while (w && bkey_cmp(&START_KEY(&w->key), end) < 0) {
2590                 p = w;
2591                 w = RB_NEXT(w, node);
2592
2593                 if (p->private)
2594                         ret = true;
2595                 else
2596                         __bch_keybuf_del(buf, p);
2597         }
2598
2599         spin_unlock(&buf->lock);
2600         return ret;
2601 }
2602
2603 struct keybuf_key *bch_keybuf_next(struct keybuf *buf)
2604 {
2605         struct keybuf_key *w;
2606
2607         spin_lock(&buf->lock);
2608
2609         w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2610
2611         while (w && w->private)
2612                 w = RB_NEXT(w, node);
2613
2614         if (w)
2615                 w->private = ERR_PTR(-EINTR);
2616
2617         spin_unlock(&buf->lock);
2618         return w;
2619 }
2620
2621 struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
2622                                           struct keybuf *buf,
2623                                           struct bkey *end,
2624                                           keybuf_pred_fn *pred)
2625 {
2626         struct keybuf_key *ret;
2627
2628         while (1) {
2629                 ret = bch_keybuf_next(buf);
2630                 if (ret)
2631                         break;
2632
2633                 if (bkey_cmp(&buf->last_scanned, end) >= 0) {
2634                         pr_debug("scan finished");
2635                         break;
2636                 }
2637
2638                 bch_refill_keybuf(c, buf, end, pred);
2639         }
2640
2641         return ret;
2642 }
2643
2644 void bch_keybuf_init(struct keybuf *buf)
2645 {
2646         buf->last_scanned       = MAX_KEY;
2647         buf->keys               = RB_ROOT;
2648
2649         spin_lock_init(&buf->lock);
2650         array_allocator_init(&buf->freelist);
2651 }