md/bcache/btree.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
0004  *
0005  * Uses a block device as cache for other block devices; optimized for SSDs.
0006  * All allocation is done in buckets, which should match the erase block size
0007  * of the device.
0008  *
0009  * Buckets containing cached data are kept on a heap sorted by priority;
0010  * bucket priority is increased on cache hit, and periodically all the buckets
0011  * on the heap have their priority scaled down. This currently is just used as
0012  * an LRU but in the future should allow for more intelligent heuristics.
0013  *
0014  * Buckets have an 8 bit counter; freeing is accomplished by incrementing the
0015  * counter. Garbage collection is used to remove stale pointers.
0016  *
0017  * Indexing is done via a btree; nodes are not necessarily fully sorted, rather
0018  * as keys are inserted we only sort the pages that have not yet been written.
0019  * When garbage collection is run, we resort the entire node.
0020  *
0021  * All configuration is done via sysfs; see Documentation/admin-guide/bcache.rst.
0022  */
0023
0024 #include "bcache.h"
0025 #include "btree.h"
0026 #include "debug.h"
0027 #include "extents.h"
0028
0029 #include <linux/slab.h>
0030 #include <linux/bitops.h>
0031 #include <linux/hash.h>
0032 #include <linux/kthread.h>
0033 #include <linux/prefetch.h>
0034 #include <linux/random.h>
0035 #include <linux/rcupdate.h>
0036 #include <linux/sched/clock.h>
0037 #include <linux/rculist.h>
0038 #include <linux/delay.h>
0039 #include <trace/events/bcache.h>
0040
0041 /*
0042  * Todo:
0043  * register_bcache: Return errors out to userspace correctly
0044  *
0045  * Writeback: don't undirty key until after a cache flush
0046  *
0047  * Create an iterator for key pointers
0048  *
0049  * On btree write error, mark bucket such that it won't be freed from the cache
0050  *
0051  * Journalling:
0052  *   Check for bad keys in replay
0053  *   Propagate barriers
0054  *   Refcount journal entries in journal_replay
0055  *
0056  * Garbage collection:
0057  *   Finish incremental gc
0058  *   Gc should free old UUIDs, data for invalid UUIDs
0059  *
0060  * Provide a way to list backing device UUIDs we have data cached for, and
0061  * probably how long it's been since we've seen them, and a way to invalidate
0062  * dirty data for devices that will never be attached again
0063  *
0064  * Keep 1 min/5 min/15 min statistics of how busy a block device has been, so
0065  * that based on that and how much dirty data we have we can keep writeback
0066  * from being starved
0067  *
0068  * Add a tracepoint or somesuch to watch for writeback starvation
0069  *
0070  * When btree depth > 1 and splitting an interior node, we have to make sure
0071  * alloc_bucket() cannot fail. This should be true but is not completely
0072  * obvious.
0073  *
0074  * Plugging?
0075  *
0076  * If data write is less than hard sector size of ssd, round up offset in open
0077  * bucket to the next whole sector
0078  *
0079  * Superblock needs to be fleshed out for multiple cache devices
0080  *
0081  * Add a sysfs tunable for the number of writeback IOs in flight
0082  *
0083  * Add a sysfs tunable for the number of open data buckets
0084  *
0085  * IO tracking: Can we track when one process is doing io on behalf of another?
0086  * IO tracking: Don't use just an average, weigh more recent stuff higher
0087  *
0088  * Test module load/unload
0089  */
0090
0091 #define MAX_NEED_GC     64
0092 #define MAX_SAVE_PRIO       72
0093 #define MAX_GC_TIMES        100
0094 #define MIN_GC_NODES        100
0095 #define GC_SLEEP_MS     100
0096
0097 #define PTR_DIRTY_BIT       (((uint64_t) 1 << 36))
0098
0099 #define PTR_HASH(c, k)                          \
0100     (((k)->ptr[0] >> c->bucket_bits) | PTR_GEN(k, 0))
0101
0102 static struct workqueue_struct *btree_io_wq;
0103
0104 #define insert_lock(s, b)   ((b)->level <= (s)->lock)
0105
0106
0107 static inline struct bset *write_block(struct btree *b)
0108 {
0109     return ((void *) btree_bset_first(b)) + b->written * block_bytes(b->c->cache);
0110 }
0111
0112 static void bch_btree_init_next(struct btree *b)
0113 {
0114     /* If not a leaf node, always sort */
0115     if (b->level && b->keys.nsets)
0116         bch_btree_sort(&b->keys, &b->c->sort);
0117     else
0118         bch_btree_sort_lazy(&b->keys, &b->c->sort);
0119
0120     if (b->written < btree_blocks(b))
0121         bch_bset_init_next(&b->keys, write_block(b),
0122                    bset_magic(&b->c->cache->sb));
0123
0124 }
0125
0126 /* Btree key manipulation */
0127
0128 void bkey_put(struct cache_set *c, struct bkey *k)
0129 {
0130     unsigned int i;
0131
0132     for (i = 0; i < KEY_PTRS(k); i++)
0133         if (ptr_available(c, k, i))
0134             atomic_dec_bug(&PTR_BUCKET(c, k, i)->pin);
0135 }
0136
0137 /* Btree IO */
0138
0139 static uint64_t btree_csum_set(struct btree *b, struct bset *i)
0140 {
0141     uint64_t crc = b->key.ptr[0];
0142     void *data = (void *) i + 8, *end = bset_bkey_last(i);
0143
0144     crc = crc64_be(crc, data, end - data);
0145     return crc ^ 0xffffffffffffffffULL;
0146 }
0147
0148 void bch_btree_node_read_done(struct btree *b)
0149 {
0150     const char *err = "bad btree header";
0151     struct bset *i = btree_bset_first(b);
0152     struct btree_iter *iter;
0153
0154     /*
0155      * c->fill_iter can allocate an iterator with more memory space
0156      * than static MAX_BSETS.
0157      * See the comment arount cache_set->fill_iter.
0158      */
0159     iter = mempool_alloc(&b->c->fill_iter, GFP_NOIO);
0160     iter->size = b->c->cache->sb.bucket_size / b->c->cache->sb.block_size;
0161     iter->used = 0;
0162
0163 #ifdef CONFIG_BCACHE_DEBUG
0164     iter->b = &b->keys;
0165 #endif
0166
0167     if (!i->seq)
0168         goto err;
0169
0170     for (;
0171          b->written < btree_blocks(b) && i->seq == b->keys.set[0].data->seq;
0172          i = write_block(b)) {
0173         err = "unsupported bset version";
0174         if (i->version > BCACHE_BSET_VERSION)
0175             goto err;
0176
0177         err = "bad btree header";
0178         if (b->written + set_blocks(i, block_bytes(b->c->cache)) >
0179             btree_blocks(b))
0180             goto err;
0181
0182         err = "bad magic";
0183         if (i->magic != bset_magic(&b->c->cache->sb))
0184             goto err;
0185
0186         err = "bad checksum";
0187         switch (i->version) {
0188         case 0:
0189             if (i->csum != csum_set(i))
0190                 goto err;
0191             break;
0192         case BCACHE_BSET_VERSION:
0193             if (i->csum != btree_csum_set(b, i))
0194                 goto err;
0195             break;
0196         }
0197
0198         err = "empty set";
0199         if (i != b->keys.set[0].data && !i->keys)
0200             goto err;
0201
0202         bch_btree_iter_push(iter, i->start, bset_bkey_last(i));
0203
0204         b->written += set_blocks(i, block_bytes(b->c->cache));
0205     }
0206
0207     err = "corrupted btree";
0208     for (i = write_block(b);
0209          bset_sector_offset(&b->keys, i) < KEY_SIZE(&b->key);
0210          i = ((void *) i) + block_bytes(b->c->cache))
0211         if (i->seq == b->keys.set[0].data->seq)
0212             goto err;
0213
0214     bch_btree_sort_and_fix_extents(&b->keys, iter, &b->c->sort);
0215
0216     i = b->keys.set[0].data;
0217     err = "short btree key";
0218     if (b->keys.set[0].size &&
0219         bkey_cmp(&b->key, &b->keys.set[0].end) < 0)
0220         goto err;
0221
0222     if (b->written < btree_blocks(b))
0223         bch_bset_init_next(&b->keys, write_block(b),
0224                    bset_magic(&b->c->cache->sb));
0225 out:
0226     mempool_free(iter, &b->c->fill_iter);
0227     return;
0228 err:
0229     set_btree_node_io_error(b);
0230     bch_cache_set_error(b->c, "%s at bucket %zu, block %u, %u keys",
0231                 err, PTR_BUCKET_NR(b->c, &b->key, 0),
0232                 bset_block_offset(b, i), i->keys);
0233     goto out;
0234 }
0235
0236 static void btree_node_read_endio(struct bio *bio)
0237 {
0238     struct closure *cl = bio->bi_private;
0239
0240     closure_put(cl);
0241 }
0242
0243 static void bch_btree_node_read(struct btree *b)
0244 {
0245     uint64_t start_time = local_clock();
0246     struct closure cl;
0247     struct bio *bio;
0248
0249     trace_bcache_btree_read(b);
0250
0251     closure_init_stack(&cl);
0252
0253     bio = bch_bbio_alloc(b->c);
0254     bio->bi_iter.bi_size = KEY_SIZE(&b->key) << 9;
0255     bio->bi_end_io  = btree_node_read_endio;
0256     bio->bi_private = &cl;
0257     bio->bi_opf = REQ_OP_READ | REQ_META;
0258
0259     bch_bio_map(bio, b->keys.set[0].data);
0260
0261     bch_submit_bbio(bio, b->c, &b->key, 0);
0262     closure_sync(&cl);
0263
0264     if (bio->bi_status)
0265         set_btree_node_io_error(b);
0266
0267     bch_bbio_free(bio, b->c);
0268
0269     if (btree_node_io_error(b))
0270         goto err;
0271
0272     bch_btree_node_read_done(b);
0273     bch_time_stats_update(&b->c->btree_read_time, start_time);
0274
0275     return;
0276 err:
0277     bch_cache_set_error(b->c, "io error reading bucket %zu",
0278                 PTR_BUCKET_NR(b->c, &b->key, 0));
0279 }
0280
0281 static void btree_complete_write(struct btree *b, struct btree_write *w)
0282 {
0283     if (w->prio_blocked &&
0284         !atomic_sub_return(w->prio_blocked, &b->c->prio_blocked))
0285         wake_up_allocators(b->c);
0286
0287     if (w->journal) {
0288         atomic_dec_bug(w->journal);
0289         __closure_wake_up(&b->c->journal.wait);
0290     }
0291
0292     w->prio_blocked = 0;
0293     w->journal  = NULL;
0294 }
0295
0296 static void btree_node_write_unlock(struct closure *cl)
0297 {
0298     struct btree *b = container_of(cl, struct btree, io);
0299
0300     up(&b->io_mutex);
0301 }
0302
0303 static void __btree_node_write_done(struct closure *cl)
0304 {
0305     struct btree *b = container_of(cl, struct btree, io);
0306     struct btree_write *w = btree_prev_write(b);
0307
0308     bch_bbio_free(b->bio, b->c);
0309     b->bio = NULL;
0310     btree_complete_write(b, w);
0311
0312     if (btree_node_dirty(b))
0313         queue_delayed_work(btree_io_wq, &b->work, 30 * HZ);
0314
0315     closure_return_with_destructor(cl, btree_node_write_unlock);
0316 }
0317
0318 static void btree_node_write_done(struct closure *cl)
0319 {
0320     struct btree *b = container_of(cl, struct btree, io);
0321
0322     bio_free_pages(b->bio);
0323     __btree_node_write_done(cl);
0324 }
0325
0326 static void btree_node_write_endio(struct bio *bio)
0327 {
0328     struct closure *cl = bio->bi_private;
0329     struct btree *b = container_of(cl, struct btree, io);
0330
0331     if (bio->bi_status)
0332         set_btree_node_io_error(b);
0333
0334     bch_bbio_count_io_errors(b->c, bio, bio->bi_status, "writing btree");
0335     closure_put(cl);
0336 }
0337
0338 static void do_btree_node_write(struct btree *b)
0339 {
0340     struct closure *cl = &b->io;
0341     struct bset *i = btree_bset_last(b);
0342     BKEY_PADDED(key) k;
0343
0344     i->version  = BCACHE_BSET_VERSION;
0345     i->csum     = btree_csum_set(b, i);
0346
0347     BUG_ON(b->bio);
0348     b->bio = bch_bbio_alloc(b->c);
0349
0350     b->bio->bi_end_io   = btree_node_write_endio;
0351     b->bio->bi_private  = cl;
0352     b->bio->bi_iter.bi_size = roundup(set_bytes(i), block_bytes(b->c->cache));
0353     b->bio->bi_opf      = REQ_OP_WRITE | REQ_META | REQ_FUA;
0354     bch_bio_map(b->bio, i);
0355
0356     /*
0357      * If we're appending to a leaf node, we don't technically need FUA -
0358      * this write just needs to be persisted before the next journal write,
0359      * which will be marked FLUSH|FUA.
0360      *
0361      * Similarly if we're writing a new btree root - the pointer is going to
0362      * be in the next journal entry.
0363      *
0364      * But if we're writing a new btree node (that isn't a root) or
0365      * appending to a non leaf btree node, we need either FUA or a flush
0366      * when we write the parent with the new pointer. FUA is cheaper than a
0367      * flush, and writes appending to leaf nodes aren't blocking anything so
0368      * just make all btree node writes FUA to keep things sane.
0369      */
0370
0371     bkey_copy(&k.key, &b->key);
0372     SET_PTR_OFFSET(&k.key, 0, PTR_OFFSET(&k.key, 0) +
0373                bset_sector_offset(&b->keys, i));
0374
0375     if (!bch_bio_alloc_pages(b->bio, __GFP_NOWARN|GFP_NOWAIT)) {
0376         struct bio_vec *bv;
0377         void *addr = (void *) ((unsigned long) i & ~(PAGE_SIZE - 1));
0378         struct bvec_iter_all iter_all;
0379
0380         bio_for_each_segment_all(bv, b->bio, iter_all) {
0381             memcpy(page_address(bv->bv_page), addr, PAGE_SIZE);
0382             addr += PAGE_SIZE;
0383         }
0384
0385         bch_submit_bbio(b->bio, b->c, &k.key, 0);
0386
0387         continue_at(cl, btree_node_write_done, NULL);
0388     } else {
0389         /*
0390          * No problem for multipage bvec since the bio is
0391          * just allocated
0392          */
0393         b->bio->bi_vcnt = 0;
0394         bch_bio_map(b->bio, i);
0395
0396         bch_submit_bbio(b->bio, b->c, &k.key, 0);
0397
0398         closure_sync(cl);
0399         continue_at_nobarrier(cl, __btree_node_write_done, NULL);
0400     }
0401 }
0402
0403 void __bch_btree_node_write(struct btree *b, struct closure *parent)
0404 {
0405     struct bset *i = btree_bset_last(b);
0406
0407     lockdep_assert_held(&b->write_lock);
0408
0409     trace_bcache_btree_write(b);
0410
0411     BUG_ON(current->bio_list);
0412     BUG_ON(b->written >= btree_blocks(b));
0413     BUG_ON(b->written && !i->keys);
0414     BUG_ON(btree_bset_first(b)->seq != i->seq);
0415     bch_check_keys(&b->keys, "writing");
0416
0417     cancel_delayed_work(&b->work);
0418
0419     /* If caller isn't waiting for write, parent refcount is cache set */
0420     down(&b->io_mutex);
0421     closure_init(&b->io, parent ?: &b->c->cl);
0422
0423     clear_bit(BTREE_NODE_dirty,  &b->flags);
0424     change_bit(BTREE_NODE_write_idx, &b->flags);
0425
0426     do_btree_node_write(b);
0427
0428     atomic_long_add(set_blocks(i, block_bytes(b->c->cache)) * b->c->cache->sb.block_size,
0429             &b->c->cache->btree_sectors_written);
0430
0431     b->written += set_blocks(i, block_bytes(b->c->cache));
0432 }
0433
0434 void bch_btree_node_write(struct btree *b, struct closure *parent)
0435 {
0436     unsigned int nsets = b->keys.nsets;
0437
0438     lockdep_assert_held(&b->lock);
0439
0440     __bch_btree_node_write(b, parent);
0441
0442     /*
0443      * do verify if there was more than one set initially (i.e. we did a
0444      * sort) and we sorted down to a single set:
0445      */
0446     if (nsets && !b->keys.nsets)
0447         bch_btree_verify(b);
0448
0449     bch_btree_init_next(b);
0450 }
0451
0452 static void bch_btree_node_write_sync(struct btree *b)
0453 {
0454     struct closure cl;
0455
0456     closure_init_stack(&cl);
0457
0458     mutex_lock(&b->write_lock);
0459     bch_btree_node_write(b, &cl);
0460     mutex_unlock(&b->write_lock);
0461
0462     closure_sync(&cl);
0463 }
0464
0465 static void btree_node_write_work(struct work_struct *w)
0466 {
0467     struct btree *b = container_of(to_delayed_work(w), struct btree, work);
0468
0469     mutex_lock(&b->write_lock);
0470     if (btree_node_dirty(b))
0471         __bch_btree_node_write(b, NULL);
0472     mutex_unlock(&b->write_lock);
0473 }
0474
0475 static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
0476 {
0477     struct bset *i = btree_bset_last(b);
0478     struct btree_write *w = btree_current_write(b);
0479
0480     lockdep_assert_held(&b->write_lock);
0481
0482     BUG_ON(!b->written);
0483     BUG_ON(!i->keys);
0484
0485     if (!btree_node_dirty(b))
0486         queue_delayed_work(btree_io_wq, &b->work, 30 * HZ);
0487
0488     set_btree_node_dirty(b);
0489
0490     /*
0491      * w->journal is always the oldest journal pin of all bkeys
0492      * in the leaf node, to make sure the oldest jset seq won't
0493      * be increased before this btree node is flushed.
0494      */
0495     if (journal_ref) {
0496         if (w->journal &&
0497             journal_pin_cmp(b->c, w->journal, journal_ref)) {
0498             atomic_dec_bug(w->journal);
0499             w->journal = NULL;
0500         }
0501
0502         if (!w->journal) {
0503             w->journal = journal_ref;
0504             atomic_inc(w->journal);
0505         }
0506     }
0507
0508     /* Force write if set is too big */
0509     if (set_bytes(i) > PAGE_SIZE - 48 &&
0510         !current->bio_list)
0511         bch_btree_node_write(b, NULL);
0512 }
0513
0514 /*
0515  * Btree in memory cache - allocation/freeing
0516  * mca -> memory cache
0517  */
0518
0519 #define mca_reserve(c)  (((!IS_ERR_OR_NULL(c->root) && c->root->level) \
0520               ? c->root->level : 1) * 8 + 16)
0521 #define mca_can_free(c)                     \
0522     max_t(int, 0, c->btree_cache_used - mca_reserve(c))
0523
0524 static void mca_data_free(struct btree *b)
0525 {
0526     BUG_ON(b->io_mutex.count != 1);
0527
0528     bch_btree_keys_free(&b->keys);
0529
0530     b->c->btree_cache_used--;
0531     list_move(&b->list, &b->c->btree_cache_freed);
0532 }
0533
0534 static void mca_bucket_free(struct btree *b)
0535 {
0536     BUG_ON(btree_node_dirty(b));
0537
0538     b->key.ptr[0] = 0;
0539     hlist_del_init_rcu(&b->hash);
0540     list_move(&b->list, &b->c->btree_cache_freeable);
0541 }
0542
0543 static unsigned int btree_order(struct bkey *k)
0544 {
0545     return ilog2(KEY_SIZE(k) / PAGE_SECTORS ?: 1);
0546 }
0547
0548 static void mca_data_alloc(struct btree *b, struct bkey *k, gfp_t gfp)
0549 {
0550     if (!bch_btree_keys_alloc(&b->keys,
0551                   max_t(unsigned int,
0552                     ilog2(b->c->btree_pages),
0553                     btree_order(k)),
0554                   gfp)) {
0555         b->c->btree_cache_used++;
0556         list_move(&b->list, &b->c->btree_cache);
0557     } else {
0558         list_move(&b->list, &b->c->btree_cache_freed);
0559     }
0560 }
0561
0562 static struct btree *mca_bucket_alloc(struct cache_set *c,
0563                       struct bkey *k, gfp_t gfp)
0564 {
0565     /*
0566      * kzalloc() is necessary here for initialization,
0567      * see code comments in bch_btree_keys_init().
0568      */
0569     struct btree *b = kzalloc(sizeof(struct btree), gfp);
0570
0571     if (!b)
0572         return NULL;
0573
0574     init_rwsem(&b->lock);
0575     lockdep_set_novalidate_class(&b->lock);
0576     mutex_init(&b->write_lock);
0577     lockdep_set_novalidate_class(&b->write_lock);
0578     INIT_LIST_HEAD(&b->list);
0579     INIT_DELAYED_WORK(&b->work, btree_node_write_work);
0580     b->c = c;
0581     sema_init(&b->io_mutex, 1);
0582
0583     mca_data_alloc(b, k, gfp);
0584     return b;
0585 }
0586
0587 static int mca_reap(struct btree *b, unsigned int min_order, bool flush)
0588 {
0589     struct closure cl;
0590
0591     closure_init_stack(&cl);
0592     lockdep_assert_held(&b->c->bucket_lock);
0593
0594     if (!down_write_trylock(&b->lock))
0595         return -ENOMEM;
0596
0597     BUG_ON(btree_node_dirty(b) && !b->keys.set[0].data);
0598
0599     if (b->keys.page_order < min_order)
0600         goto out_unlock;
0601
0602     if (!flush) {
0603         if (btree_node_dirty(b))
0604             goto out_unlock;
0605
0606         if (down_trylock(&b->io_mutex))
0607             goto out_unlock;
0608         up(&b->io_mutex);
0609     }
0610
0611 retry:
0612     /*
0613      * BTREE_NODE_dirty might be cleared in btree_flush_btree() by
0614      * __bch_btree_node_write(). To avoid an extra flush, acquire
0615      * b->write_lock before checking BTREE_NODE_dirty bit.
0616      */
0617     mutex_lock(&b->write_lock);
0618     /*
0619      * If this btree node is selected in btree_flush_write() by journal
0620      * code, delay and retry until the node is flushed by journal code
0621      * and BTREE_NODE_journal_flush bit cleared by btree_flush_write().
0622      */
0623     if (btree_node_journal_flush(b)) {
0624         pr_debug("bnode %p is flushing by journal, retry\n", b);
0625         mutex_unlock(&b->write_lock);
0626         udelay(1);
0627         goto retry;
0628     }
0629
0630     if (btree_node_dirty(b))
0631         __bch_btree_node_write(b, &cl);
0632     mutex_unlock(&b->write_lock);
0633
0634     closure_sync(&cl);
0635
0636     /* wait for any in flight btree write */
0637     down(&b->io_mutex);
0638     up(&b->io_mutex);
0639
0640     return 0;
0641 out_unlock:
0642     rw_unlock(true, b);
0643     return -ENOMEM;
0644 }
0645
0646 static unsigned long bch_mca_scan(struct shrinker *shrink,
0647                   struct shrink_control *sc)
0648 {
0649     struct cache_set *c = container_of(shrink, struct cache_set, shrink);
0650     struct btree *b, *t;
0651     unsigned long i, nr = sc->nr_to_scan;
0652     unsigned long freed = 0;
0653     unsigned int btree_cache_used;
0654
0655     if (c->shrinker_disabled)
0656         return SHRINK_STOP;
0657
0658     if (c->btree_cache_alloc_lock)
0659         return SHRINK_STOP;
0660
0661     /* Return -1 if we can't do anything right now */
0662     if (sc->gfp_mask & __GFP_IO)
0663         mutex_lock(&c->bucket_lock);
0664     else if (!mutex_trylock(&c->bucket_lock))
0665         return -1;
0666
0667     /*
0668      * It's _really_ critical that we don't free too many btree nodes - we
0669      * have to always leave ourselves a reserve. The reserve is how we
0670      * guarantee that allocating memory for a new btree node can always
0671      * succeed, so that inserting keys into the btree can always succeed and
0672      * IO can always make forward progress:
0673      */
0674     nr /= c->btree_pages;
0675     if (nr == 0)
0676         nr = 1;
0677     nr = min_t(unsigned long, nr, mca_can_free(c));
0678
0679     i = 0;
0680     btree_cache_used = c->btree_cache_used;
0681     list_for_each_entry_safe_reverse(b, t, &c->btree_cache_freeable, list) {
0682         if (nr <= 0)
0683             goto out;
0684
0685         if (!mca_reap(b, 0, false)) {
0686             mca_data_free(b);
0687             rw_unlock(true, b);
0688             freed++;
0689         }
0690         nr--;
0691         i++;
0692     }
0693
0694     list_for_each_entry_safe_reverse(b, t, &c->btree_cache, list) {
0695         if (nr <= 0 || i >= btree_cache_used)
0696             goto out;
0697
0698         if (!mca_reap(b, 0, false)) {
0699             mca_bucket_free(b);
0700             mca_data_free(b);
0701             rw_unlock(true, b);
0702             freed++;
0703         }
0704
0705         nr--;
0706         i++;
0707     }
0708 out:
0709     mutex_unlock(&c->bucket_lock);
0710     return freed * c->btree_pages;
0711 }
0712
0713 static unsigned long bch_mca_count(struct shrinker *shrink,
0714                    struct shrink_control *sc)
0715 {
0716     struct cache_set *c = container_of(shrink, struct cache_set, shrink);
0717
0718     if (c->shrinker_disabled)
0719         return 0;
0720
0721     if (c->btree_cache_alloc_lock)
0722         return 0;
0723
0724     return mca_can_free(c) * c->btree_pages;
0725 }
0726
0727 void bch_btree_cache_free(struct cache_set *c)
0728 {
0729     struct btree *b;
0730     struct closure cl;
0731
0732     closure_init_stack(&cl);
0733
0734     if (c->shrink.list.next)
0735         unregister_shrinker(&c->shrink);
0736
0737     mutex_lock(&c->bucket_lock);
0738
0739 #ifdef CONFIG_BCACHE_DEBUG
0740     if (c->verify_data)
0741         list_move(&c->verify_data->list, &c->btree_cache);
0742
0743     free_pages((unsigned long) c->verify_ondisk, ilog2(meta_bucket_pages(&c->cache->sb)));
0744 #endif
0745
0746     list_splice(&c->btree_cache_freeable,
0747             &c->btree_cache);
0748
0749     while (!list_empty(&c->btree_cache)) {
0750         b = list_first_entry(&c->btree_cache, struct btree, list);
0751
0752         /*
0753          * This function is called by cache_set_free(), no I/O
0754          * request on cache now, it is unnecessary to acquire
0755          * b->write_lock before clearing BTREE_NODE_dirty anymore.
0756          */
0757         if (btree_node_dirty(b)) {
0758             btree_complete_write(b, btree_current_write(b));
0759             clear_bit(BTREE_NODE_dirty, &b->flags);
0760         }
0761         mca_data_free(b);
0762     }
0763
0764     while (!list_empty(&c->btree_cache_freed)) {
0765         b = list_first_entry(&c->btree_cache_freed,
0766                      struct btree, list);
0767         list_del(&b->list);
0768         cancel_delayed_work_sync(&b->work);
0769         kfree(b);
0770     }
0771
0772     mutex_unlock(&c->bucket_lock);
0773 }
0774
0775 int bch_btree_cache_alloc(struct cache_set *c)
0776 {
0777     unsigned int i;
0778
0779     for (i = 0; i < mca_reserve(c); i++)
0780         if (!mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL))
0781             return -ENOMEM;
0782
0783     list_splice_init(&c->btree_cache,
0784              &c->btree_cache_freeable);
0785
0786 #ifdef CONFIG_BCACHE_DEBUG
0787     mutex_init(&c->verify_lock);
0788
0789     c->verify_ondisk = (void *)
0790         __get_free_pages(GFP_KERNEL|__GFP_COMP,
0791                  ilog2(meta_bucket_pages(&c->cache->sb)));
0792     if (!c->verify_ondisk) {
0793         /*
0794          * Don't worry about the mca_rereserve buckets
0795          * allocated in previous for-loop, they will be
0796          * handled properly in bch_cache_set_unregister().
0797          */
0798         return -ENOMEM;
0799     }
0800
0801     c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
0802
0803     if (c->verify_data &&
0804         c->verify_data->keys.set->data)
0805         list_del_init(&c->verify_data->list);
0806     else
0807         c->verify_data = NULL;
0808 #endif
0809
0810     c->shrink.count_objects = bch_mca_count;
0811     c->shrink.scan_objects = bch_mca_scan;
0812     c->shrink.seeks = 4;
0813     c->shrink.batch = c->btree_pages * 2;
0814
0815     if (register_shrinker(&c->shrink, "md-bcache:%pU", c->set_uuid))
0816         pr_warn("bcache: %s: could not register shrinker\n",
0817                 __func__);
0818
0819     return 0;
0820 }
0821
0822 /* Btree in memory cache - hash table */
0823
0824 static struct hlist_head *mca_hash(struct cache_set *c, struct bkey *k)
0825 {
0826     return &c->bucket_hash[hash_32(PTR_HASH(c, k), BUCKET_HASH_BITS)];
0827 }
0828
0829 static struct btree *mca_find(struct cache_set *c, struct bkey *k)
0830 {
0831     struct btree *b;
0832
0833     rcu_read_lock();
0834     hlist_for_each_entry_rcu(b, mca_hash(c, k), hash)
0835         if (PTR_HASH(c, &b->key) == PTR_HASH(c, k))
0836             goto out;
0837     b = NULL;
0838 out:
0839     rcu_read_unlock();
0840     return b;
0841 }
0842
0843 static int mca_cannibalize_lock(struct cache_set *c, struct btree_op *op)
0844 {
0845     spin_lock(&c->btree_cannibalize_lock);
0846     if (likely(c->btree_cache_alloc_lock == NULL)) {
0847         c->btree_cache_alloc_lock = current;
0848     } else if (c->btree_cache_alloc_lock != current) {
0849         if (op)
0850             prepare_to_wait(&c->btree_cache_wait, &op->wait,
0851                     TASK_UNINTERRUPTIBLE);
0852         spin_unlock(&c->btree_cannibalize_lock);
0853         return -EINTR;
0854     }
0855     spin_unlock(&c->btree_cannibalize_lock);
0856
0857     return 0;
0858 }
0859
0860 static struct btree *mca_cannibalize(struct cache_set *c, struct btree_op *op,
0861                      struct bkey *k)
0862 {
0863     struct btree *b;
0864
0865     trace_bcache_btree_cache_cannibalize(c);
0866
0867     if (mca_cannibalize_lock(c, op))
0868         return ERR_PTR(-EINTR);
0869
0870     list_for_each_entry_reverse(b, &c->btree_cache, list)
0871         if (!mca_reap(b, btree_order(k), false))
0872             return b;
0873
0874     list_for_each_entry_reverse(b, &c->btree_cache, list)
0875         if (!mca_reap(b, btree_order(k), true))
0876             return b;
0877
0878     WARN(1, "btree cache cannibalize failed\n");
0879     return ERR_PTR(-ENOMEM);
0880 }
0881
0882 /*
0883  * We can only have one thread cannibalizing other cached btree nodes at a time,
0884  * or we'll deadlock. We use an open coded mutex to ensure that, which a
0885  * cannibalize_bucket() will take. This means every time we unlock the root of
0886  * the btree, we need to release this lock if we have it held.
0887  */
0888 static void bch_cannibalize_unlock(struct cache_set *c)
0889 {
0890     spin_lock(&c->btree_cannibalize_lock);
0891     if (c->btree_cache_alloc_lock == current) {
0892         c->btree_cache_alloc_lock = NULL;
0893         wake_up(&c->btree_cache_wait);
0894     }
0895     spin_unlock(&c->btree_cannibalize_lock);
0896 }
0897
0898 static struct btree *mca_alloc(struct cache_set *c, struct btree_op *op,
0899                    struct bkey *k, int level)
0900 {
0901     struct btree *b;
0902
0903     BUG_ON(current->bio_list);
0904
0905     lockdep_assert_held(&c->bucket_lock);
0906
0907     if (mca_find(c, k))
0908         return NULL;
0909
0910     /* btree_free() doesn't free memory; it sticks the node on the end of
0911      * the list. Check if there's any freed nodes there:
0912      */
0913     list_for_each_entry(b, &c->btree_cache_freeable, list)
0914         if (!mca_reap(b, btree_order(k), false))
0915             goto out;
0916
0917     /* We never free struct btree itself, just the memory that holds the on
0918      * disk node. Check the freed list before allocating a new one:
0919      */
0920     list_for_each_entry(b, &c->btree_cache_freed, list)
0921         if (!mca_reap(b, 0, false)) {
0922             mca_data_alloc(b, k, __GFP_NOWARN|GFP_NOIO);
0923             if (!b->keys.set[0].data)
0924                 goto err;
0925             else
0926                 goto out;
0927         }
0928
0929     b = mca_bucket_alloc(c, k, __GFP_NOWARN|GFP_NOIO);
0930     if (!b)
0931         goto err;
0932
0933     BUG_ON(!down_write_trylock(&b->lock));
0934     if (!b->keys.set->data)
0935         goto err;
0936 out:
0937     BUG_ON(b->io_mutex.count != 1);
0938
0939     bkey_copy(&b->key, k);
0940     list_move(&b->list, &c->btree_cache);
0941     hlist_del_init_rcu(&b->hash);
0942     hlist_add_head_rcu(&b->hash, mca_hash(c, k));
0943
0944     lock_set_subclass(&b->lock.dep_map, level + 1, _THIS_IP_);
0945     b->parent   = (void *) ~0UL;
0946     b->flags    = 0;
0947     b->written  = 0;
0948     b->level    = level;
0949
0950     if (!b->level)
0951         bch_btree_keys_init(&b->keys, &bch_extent_keys_ops,
0952                     &b->c->expensive_debug_checks);
0953     else
0954         bch_btree_keys_init(&b->keys, &bch_btree_keys_ops,
0955                     &b->c->expensive_debug_checks);
0956
0957     return b;
0958 err:
0959     if (b)
0960         rw_unlock(true, b);
0961
0962     b = mca_cannibalize(c, op, k);
0963     if (!IS_ERR(b))
0964         goto out;
0965
0966     return b;
0967 }
0968
0969 /*
0970  * bch_btree_node_get - find a btree node in the cache and lock it, reading it
0971  * in from disk if necessary.
0972  *
0973  * If IO is necessary and running under submit_bio_noacct, returns -EAGAIN.
0974  *
0975  * The btree node will have either a read or a write lock held, depending on
0976  * level and op->lock.
0977  */
0978 struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op,
0979                  struct bkey *k, int level, bool write,
0980                  struct btree *parent)
0981 {
0982     int i = 0;
0983     struct btree *b;
0984
0985     BUG_ON(level < 0);
0986 retry:
0987     b = mca_find(c, k);
0988
0989     if (!b) {
0990         if (current->bio_list)
0991             return ERR_PTR(-EAGAIN);
0992
0993         mutex_lock(&c->bucket_lock);
0994         b = mca_alloc(c, op, k, level);
0995         mutex_unlock(&c->bucket_lock);
0996
0997         if (!b)
0998             goto retry;
0999         if (IS_ERR(b))
1000             return b;
1001
1002         bch_btree_node_read(b);
1003
1004         if (!write)
1005             downgrade_write(&b->lock);
1006     } else {
1007         rw_lock(write, b, level);
1008         if (PTR_HASH(c, &b->key) != PTR_HASH(c, k)) {
1009             rw_unlock(write, b);
1010             goto retry;
1011         }
1012         BUG_ON(b->level != level);
1013     }
1014
1015     if (btree_node_io_error(b)) {
1016         rw_unlock(write, b);
1017         return ERR_PTR(-EIO);
1018     }
1019
1020     BUG_ON(!b->written);
1021
1022     b->parent = parent;
1023
1024     for (; i <= b->keys.nsets && b->keys.set[i].size; i++) {
1025         prefetch(b->keys.set[i].tree);
1026         prefetch(b->keys.set[i].data);
1027     }
1028
1029     for (; i <= b->keys.nsets; i++)
1030         prefetch(b->keys.set[i].data);
1031
1032     return b;
1033 }
1034
1035 static void btree_node_prefetch(struct btree *parent, struct bkey *k)
1036 {
1037     struct btree *b;
1038
1039     mutex_lock(&parent->c->bucket_lock);
1040     b = mca_alloc(parent->c, NULL, k, parent->level - 1);
1041     mutex_unlock(&parent->c->bucket_lock);
1042
1043     if (!IS_ERR_OR_NULL(b)) {
1044         b->parent = parent;
1045         bch_btree_node_read(b);
1046         rw_unlock(true, b);
1047     }
1048 }
1049
1050 /* Btree alloc */
1051
1052 static void btree_node_free(struct btree *b)
1053 {
1054     trace_bcache_btree_node_free(b);
1055
1056     BUG_ON(b == b->c->root);
1057
1058 retry:
1059     mutex_lock(&b->write_lock);
1060     /*
1061      * If the btree node is selected and flushing in btree_flush_write(),
1062      * delay and retry until the BTREE_NODE_journal_flush bit cleared,
1063      * then it is safe to free the btree node here. Otherwise this btree
1064      * node will be in race condition.
1065      */
1066     if (btree_node_journal_flush(b)) {
1067         mutex_unlock(&b->write_lock);
1068         pr_debug("bnode %p journal_flush set, retry\n", b);
1069         udelay(1);
1070         goto retry;
1071     }
1072
1073     if (btree_node_dirty(b)) {
1074         btree_complete_write(b, btree_current_write(b));
1075         clear_bit(BTREE_NODE_dirty, &b->flags);
1076     }
1077
1078     mutex_unlock(&b->write_lock);
1079
1080     cancel_delayed_work(&b->work);
1081
1082     mutex_lock(&b->c->bucket_lock);
1083     bch_bucket_free(b->c, &b->key);
1084     mca_bucket_free(b);
1085     mutex_unlock(&b->c->bucket_lock);
1086 }
1087
1088 struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
1089                      int level, bool wait,
1090                      struct btree *parent)
1091 {
1092     BKEY_PADDED(key) k;
1093     struct btree *b = ERR_PTR(-EAGAIN);
1094
1095     mutex_lock(&c->bucket_lock);
1096 retry:
1097     if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, wait))
1098         goto err;
1099
1100     bkey_put(c, &k.key);
1101     SET_KEY_SIZE(&k.key, c->btree_pages * PAGE_SECTORS);
1102
1103     b = mca_alloc(c, op, &k.key, level);
1104     if (IS_ERR(b))
1105         goto err_free;
1106
1107     if (!b) {
1108         cache_bug(c,
1109             "Tried to allocate bucket that was in btree cache");
1110         goto retry;
1111     }
1112
1113     b->parent = parent;
1114     bch_bset_init_next(&b->keys, b->keys.set->data, bset_magic(&b->c->cache->sb));
1115
1116     mutex_unlock(&c->bucket_lock);
1117
1118     trace_bcache_btree_node_alloc(b);
1119     return b;
1120 err_free:
1121     bch_bucket_free(c, &k.key);
1122 err:
1123     mutex_unlock(&c->bucket_lock);
1124
1125     trace_bcache_btree_node_alloc_fail(c);
1126     return b;
1127 }
1128
1129 static struct btree *bch_btree_node_alloc(struct cache_set *c,
1130                       struct btree_op *op, int level,
1131                       struct btree *parent)
1132 {
1133     return __bch_btree_node_alloc(c, op, level, op != NULL, parent);
1134 }
1135
1136 static struct btree *btree_node_alloc_replacement(struct btree *b,
1137                           struct btree_op *op)
1138 {
1139     struct btree *n = bch_btree_node_alloc(b->c, op, b->level, b->parent);
1140
1141     if (!IS_ERR_OR_NULL(n)) {
1142         mutex_lock(&n->write_lock);
1143         bch_btree_sort_into(&b->keys, &n->keys, &b->c->sort);
1144         bkey_copy_key(&n->key, &b->key);
1145         mutex_unlock(&n->write_lock);
1146     }
1147
1148     return n;
1149 }
1150
1151 static void make_btree_freeing_key(struct btree *b, struct bkey *k)
1152 {
1153     unsigned int i;
1154
1155     mutex_lock(&b->c->bucket_lock);
1156
1157     atomic_inc(&b->c->prio_blocked);
1158
1159     bkey_copy(k, &b->key);
1160     bkey_copy_key(k, &ZERO_KEY);
1161
1162     for (i = 0; i < KEY_PTRS(k); i++)
1163         SET_PTR_GEN(k, i,
1164                 bch_inc_gen(b->c->cache,
1165                     PTR_BUCKET(b->c, &b->key, i)));
1166
1167     mutex_unlock(&b->c->bucket_lock);
1168 }
1169
1170 static int btree_check_reserve(struct btree *b, struct btree_op *op)
1171 {
1172     struct cache_set *c = b->c;
1173     struct cache *ca = c->cache;
1174     unsigned int reserve = (c->root->level - b->level) * 2 + 1;
1175
1176     mutex_lock(&c->bucket_lock);
1177
1178     if (fifo_used(&ca->free[RESERVE_BTREE]) < reserve) {
1179         if (op)
1180             prepare_to_wait(&c->btree_cache_wait, &op->wait,
1181                     TASK_UNINTERRUPTIBLE);
1182         mutex_unlock(&c->bucket_lock);
1183         return -EINTR;
1184     }
1185
1186     mutex_unlock(&c->bucket_lock);
1187
1188     return mca_cannibalize_lock(b->c, op);
1189 }
1190
1191 /* Garbage collection */
1192
1193 static uint8_t __bch_btree_mark_key(struct cache_set *c, int level,
1194                     struct bkey *k)
1195 {
1196     uint8_t stale = 0;
1197     unsigned int i;
1198     struct bucket *g;
1199
1200     /*
1201      * ptr_invalid() can't return true for the keys that mark btree nodes as
1202      * freed, but since ptr_bad() returns true we'll never actually use them
1203      * for anything and thus we don't want mark their pointers here
1204      */
1205     if (!bkey_cmp(k, &ZERO_KEY))
1206         return stale;
1207
1208     for (i = 0; i < KEY_PTRS(k); i++) {
1209         if (!ptr_available(c, k, i))
1210             continue;
1211
1212         g = PTR_BUCKET(c, k, i);
1213
1214         if (gen_after(g->last_gc, PTR_GEN(k, i)))
1215             g->last_gc = PTR_GEN(k, i);
1216
1217         if (ptr_stale(c, k, i)) {
1218             stale = max(stale, ptr_stale(c, k, i));
1219             continue;
1220         }
1221
1222         cache_bug_on(GC_MARK(g) &&
1223                  (GC_MARK(g) == GC_MARK_METADATA) != (level != 0),
1224                  c, "inconsistent ptrs: mark = %llu, level = %i",
1225                  GC_MARK(g), level);
1226
1227         if (level)
1228             SET_GC_MARK(g, GC_MARK_METADATA);
1229         else if (KEY_DIRTY(k))
1230             SET_GC_MARK(g, GC_MARK_DIRTY);
1231         else if (!GC_MARK(g))
1232             SET_GC_MARK(g, GC_MARK_RECLAIMABLE);
1233
1234         /* guard against overflow */
1235         SET_GC_SECTORS_USED(g, min_t(unsigned int,
1236                          GC_SECTORS_USED(g) + KEY_SIZE(k),
1237                          MAX_GC_SECTORS_USED));
1238
1239         BUG_ON(!GC_SECTORS_USED(g));
1240     }
1241
1242     return stale;
1243 }
1244
1245 #define btree_mark_key(b, k)    __bch_btree_mark_key(b->c, b->level, k)
1246
1247 void bch_initial_mark_key(struct cache_set *c, int level, struct bkey *k)
1248 {
1249     unsigned int i;
1250
1251     for (i = 0; i < KEY_PTRS(k); i++)
1252         if (ptr_available(c, k, i) &&
1253             !ptr_stale(c, k, i)) {
1254             struct bucket *b = PTR_BUCKET(c, k, i);
1255
1256             b->gen = PTR_GEN(k, i);
1257
1258             if (level && bkey_cmp(k, &ZERO_KEY))
1259                 b->prio = BTREE_PRIO;
1260             else if (!level && b->prio == BTREE_PRIO)
1261                 b->prio = INITIAL_PRIO;
1262         }
1263
1264     __bch_btree_mark_key(c, level, k);
1265 }
1266
1267 void bch_update_bucket_in_use(struct cache_set *c, struct gc_stat *stats)
1268 {
1269     stats->in_use = (c->nbuckets - c->avail_nbuckets) * 100 / c->nbuckets;
1270 }
1271
1272 static bool btree_gc_mark_node(struct btree *b, struct gc_stat *gc)
1273 {
1274     uint8_t stale = 0;
1275     unsigned int keys = 0, good_keys = 0;
1276     struct bkey *k;
1277     struct btree_iter iter;
1278     struct bset_tree *t;
1279
1280     gc->nodes++;
1281
1282     for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid) {
1283         stale = max(stale, btree_mark_key(b, k));
1284         keys++;
1285
1286         if (bch_ptr_bad(&b->keys, k))
1287             continue;
1288
1289         gc->key_bytes += bkey_u64s(k);
1290         gc->nkeys++;
1291         good_keys++;
1292
1293         gc->data += KEY_SIZE(k);
1294     }
1295
1296     for (t = b->keys.set; t <= &b->keys.set[b->keys.nsets]; t++)
1297         btree_bug_on(t->size &&
1298                  bset_written(&b->keys, t) &&
1299                  bkey_cmp(&b->key, &t->end) < 0,
1300                  b, "found short btree key in gc");
1301
1302     if (b->c->gc_always_rewrite)
1303         return true;
1304
1305     if (stale > 10)
1306         return true;
1307
1308     if ((keys - good_keys) * 2 > keys)
1309         return true;
1310
1311     return false;
1312 }
1313
1314 #define GC_MERGE_NODES  4U
1315
1316 struct gc_merge_info {
1317     struct btree    *b;
1318     unsigned int    keys;
1319 };
1320
1321 static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
1322                  struct keylist *insert_keys,
1323                  atomic_t *journal_ref,
1324                  struct bkey *replace_key);
1325
1326 static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
1327                  struct gc_stat *gc, struct gc_merge_info *r)
1328 {
1329     unsigned int i, nodes = 0, keys = 0, blocks;
1330     struct btree *new_nodes[GC_MERGE_NODES];
1331     struct keylist keylist;
1332     struct closure cl;
1333     struct bkey *k;
1334
1335     bch_keylist_init(&keylist);
1336
1337     if (btree_check_reserve(b, NULL))
1338         return 0;
1339
1340     memset(new_nodes, 0, sizeof(new_nodes));
1341     closure_init_stack(&cl);
1342
1343     while (nodes < GC_MERGE_NODES && !IS_ERR_OR_NULL(r[nodes].b))
1344         keys += r[nodes++].keys;
1345
1346     blocks = btree_default_blocks(b->c) * 2 / 3;
1347
1348     if (nodes < 2 ||
1349         __set_blocks(b->keys.set[0].data, keys,
1350              block_bytes(b->c->cache)) > blocks * (nodes - 1))
1351         return 0;
1352
1353     for (i = 0; i < nodes; i++) {
1354         new_nodes[i] = btree_node_alloc_replacement(r[i].b, NULL);
1355         if (IS_ERR_OR_NULL(new_nodes[i]))
1356             goto out_nocoalesce;
1357     }
1358
1359     /*
1360      * We have to check the reserve here, after we've allocated our new
1361      * nodes, to make sure the insert below will succeed - we also check
1362      * before as an optimization to potentially avoid a bunch of expensive
1363      * allocs/sorts
1364      */
1365     if (btree_check_reserve(b, NULL))
1366         goto out_nocoalesce;
1367
1368     for (i = 0; i < nodes; i++)
1369         mutex_lock(&new_nodes[i]->write_lock);
1370
1371     for (i = nodes - 1; i > 0; --i) {
1372         struct bset *n1 = btree_bset_first(new_nodes[i]);
1373         struct bset *n2 = btree_bset_first(new_nodes[i - 1]);
1374         struct bkey *k, *last = NULL;
1375
1376         keys = 0;
1377
1378         if (i > 1) {
1379             for (k = n2->start;
1380                  k < bset_bkey_last(n2);
1381                  k = bkey_next(k)) {
1382                 if (__set_blocks(n1, n1->keys + keys +
1383                          bkey_u64s(k),
1384                          block_bytes(b->c->cache)) > blocks)
1385                     break;
1386
1387                 last = k;
1388                 keys += bkey_u64s(k);
1389             }
1390         } else {
1391             /*
1392              * Last node we're not getting rid of - we're getting
1393              * rid of the node at r[0]. Have to try and fit all of
1394              * the remaining keys into this node; we can't ensure
1395              * they will always fit due to rounding and variable
1396              * length keys (shouldn't be possible in practice,
1397              * though)
1398              */
1399             if (__set_blocks(n1, n1->keys + n2->keys,
1400                      block_bytes(b->c->cache)) >
1401                 btree_blocks(new_nodes[i]))
1402                 goto out_unlock_nocoalesce;
1403
1404             keys = n2->keys;
1405             /* Take the key of the node we're getting rid of */
1406             last = &r->b->key;
1407         }
1408
1409         BUG_ON(__set_blocks(n1, n1->keys + keys, block_bytes(b->c->cache)) >
1410                btree_blocks(new_nodes[i]));
1411
1412         if (last)
1413             bkey_copy_key(&new_nodes[i]->key, last);
1414
1415         memcpy(bset_bkey_last(n1),
1416                n2->start,
1417                (void *) bset_bkey_idx(n2, keys) - (void *) n2->start);
1418
1419         n1->keys += keys;
1420         r[i].keys = n1->keys;
1421
1422         memmove(n2->start,
1423             bset_bkey_idx(n2, keys),
1424             (void *) bset_bkey_last(n2) -
1425             (void *) bset_bkey_idx(n2, keys));
1426
1427         n2->keys -= keys;
1428
1429         if (__bch_keylist_realloc(&keylist,
1430                       bkey_u64s(&new_nodes[i]->key)))
1431             goto out_unlock_nocoalesce;
1432
1433         bch_btree_node_write(new_nodes[i], &cl);
1434         bch_keylist_add(&keylist, &new_nodes[i]->key);
1435     }
1436
1437     for (i = 0; i < nodes; i++)
1438         mutex_unlock(&new_nodes[i]->write_lock);
1439
1440     closure_sync(&cl);
1441
1442     /* We emptied out this node */
1443     BUG_ON(btree_bset_first(new_nodes[0])->keys);
1444     btree_node_free(new_nodes[0]);
1445     rw_unlock(true, new_nodes[0]);
1446     new_nodes[0] = NULL;
1447
1448     for (i = 0; i < nodes; i++) {
1449         if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b->key)))
1450             goto out_nocoalesce;
1451
1452         make_btree_freeing_key(r[i].b, keylist.top);
1453         bch_keylist_push(&keylist);
1454     }
1455
1456     bch_btree_insert_node(b, op, &keylist, NULL, NULL);
1457     BUG_ON(!bch_keylist_empty(&keylist));
1458
1459     for (i = 0; i < nodes; i++) {
1460         btree_node_free(r[i].b);
1461         rw_unlock(true, r[i].b);
1462
1463         r[i].b = new_nodes[i];
1464     }
1465
1466     memmove(r, r + 1, sizeof(r[0]) * (nodes - 1));
1467     r[nodes - 1].b = ERR_PTR(-EINTR);
1468
1469     trace_bcache_btree_gc_coalesce(nodes);
1470     gc->nodes--;
1471
1472     bch_keylist_free(&keylist);
1473
1474     /* Invalidated our iterator */
1475     return -EINTR;
1476
1477 out_unlock_nocoalesce:
1478     for (i = 0; i < nodes; i++)
1479         mutex_unlock(&new_nodes[i]->write_lock);
1480
1481 out_nocoalesce:
1482     closure_sync(&cl);
1483
1484     while ((k = bch_keylist_pop(&keylist)))
1485         if (!bkey_cmp(k, &ZERO_KEY))
1486             atomic_dec(&b->c->prio_blocked);
1487     bch_keylist_free(&keylist);
1488
1489     for (i = 0; i < nodes; i++)
1490         if (!IS_ERR_OR_NULL(new_nodes[i])) {
1491             btree_node_free(new_nodes[i]);
1492             rw_unlock(true, new_nodes[i]);
1493         }
1494     return 0;
1495 }
1496
1497 static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op,
1498                  struct btree *replace)
1499 {
1500     struct keylist keys;
1501     struct btree *n;
1502
1503     if (btree_check_reserve(b, NULL))
1504         return 0;
1505
1506     n = btree_node_alloc_replacement(replace, NULL);
1507
1508     /* recheck reserve after allocating replacement node */
1509     if (btree_check_reserve(b, NULL)) {
1510         btree_node_free(n);
1511         rw_unlock(true, n);
1512         return 0;
1513     }
1514
1515     bch_btree_node_write_sync(n);
1516
1517     bch_keylist_init(&keys);
1518     bch_keylist_add(&keys, &n->key);
1519
1520     make_btree_freeing_key(replace, keys.top);
1521     bch_keylist_push(&keys);
1522
1523     bch_btree_insert_node(b, op, &keys, NULL, NULL);
1524     BUG_ON(!bch_keylist_empty(&keys));
1525
1526     btree_node_free(replace);
1527     rw_unlock(true, n);
1528
1529     /* Invalidated our iterator */
1530     return -EINTR;
1531 }
1532
1533 static unsigned int btree_gc_count_keys(struct btree *b)
1534 {
1535     struct bkey *k;
1536     struct btree_iter iter;
1537     unsigned int ret = 0;
1538
1539     for_each_key_filter(&b->keys, k, &iter, bch_ptr_bad)
1540         ret += bkey_u64s(k);
1541
1542     return ret;
1543 }
1544
1545 static size_t btree_gc_min_nodes(struct cache_set *c)
1546 {
1547     size_t min_nodes;
1548
1549     /*
1550      * Since incremental GC would stop 100ms when front
1551      * side I/O comes, so when there are many btree nodes,
1552      * if GC only processes constant (100) nodes each time,
1553      * GC would last a long time, and the front side I/Os
1554      * would run out of the buckets (since no new bucket
1555      * can be allocated during GC), and be blocked again.
1556      * So GC should not process constant nodes, but varied
1557      * nodes according to the number of btree nodes, which
1558      * realized by dividing GC into constant(100) times,
1559      * so when there are many btree nodes, GC can process
1560      * more nodes each time, otherwise, GC will process less
1561      * nodes each time (but no less than MIN_GC_NODES)
1562      */
1563     min_nodes = c->gc_stats.nodes / MAX_GC_TIMES;
1564     if (min_nodes < MIN_GC_NODES)
1565         min_nodes = MIN_GC_NODES;
1566
1567     return min_nodes;
1568 }
1569
1570
1571 static int btree_gc_recurse(struct btree *b, struct btree_op *op,
1572                 struct closure *writes, struct gc_stat *gc)
1573 {
1574     int ret = 0;
1575     bool should_rewrite;
1576     struct bkey *k;
1577     struct btree_iter iter;
1578     struct gc_merge_info r[GC_MERGE_NODES];
1579     struct gc_merge_info *i, *last = r + ARRAY_SIZE(r) - 1;
1580
1581     bch_btree_iter_init(&b->keys, &iter, &b->c->gc_done);
1582
1583     for (i = r; i < r + ARRAY_SIZE(r); i++)
1584         i->b = ERR_PTR(-EINTR);
1585
1586     while (1) {
1587         k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad);
1588         if (k) {
1589             r->b = bch_btree_node_get(b->c, op, k, b->level - 1,
1590                           true, b);
1591             if (IS_ERR(r->b)) {
1592                 ret = PTR_ERR(r->b);
1593                 break;
1594             }
1595
1596             r->keys = btree_gc_count_keys(r->b);
1597
1598             ret = btree_gc_coalesce(b, op, gc, r);
1599             if (ret)
1600                 break;
1601         }
1602
1603         if (!last->b)
1604             break;
1605
1606         if (!IS_ERR(last->b)) {
1607             should_rewrite = btree_gc_mark_node(last->b, gc);
1608             if (should_rewrite) {
1609                 ret = btree_gc_rewrite_node(b, op, last->b);
1610                 if (ret)
1611                     break;
1612             }
1613
1614             if (last->b->level) {
1615                 ret = btree_gc_recurse(last->b, op, writes, gc);
1616                 if (ret)
1617                     break;
1618             }
1619
1620             bkey_copy_key(&b->c->gc_done, &last->b->key);
1621
1622             /*
1623              * Must flush leaf nodes before gc ends, since replace
1624              * operations aren't journalled
1625              */
1626             mutex_lock(&last->b->write_lock);
1627             if (btree_node_dirty(last->b))
1628                 bch_btree_node_write(last->b, writes);
1629             mutex_unlock(&last->b->write_lock);
1630             rw_unlock(true, last->b);
1631         }
1632
1633         memmove(r + 1, r, sizeof(r[0]) * (GC_MERGE_NODES - 1));
1634         r->b = NULL;
1635
1636         if (atomic_read(&b->c->search_inflight) &&
1637             gc->nodes >= gc->nodes_pre + btree_gc_min_nodes(b->c)) {
1638             gc->nodes_pre =  gc->nodes;
1639             ret = -EAGAIN;
1640             break;
1641         }
1642
1643         if (need_resched()) {
1644             ret = -EAGAIN;
1645             break;
1646         }
1647     }
1648
1649     for (i = r; i < r + ARRAY_SIZE(r); i++)
1650         if (!IS_ERR_OR_NULL(i->b)) {
1651             mutex_lock(&i->b->write_lock);
1652             if (btree_node_dirty(i->b))
1653                 bch_btree_node_write(i->b, writes);
1654             mutex_unlock(&i->b->write_lock);
1655             rw_unlock(true, i->b);
1656         }
1657
1658     return ret;
1659 }
1660
1661 static int bch_btree_gc_root(struct btree *b, struct btree_op *op,
1662                  struct closure *writes, struct gc_stat *gc)
1663 {
1664     struct btree *n = NULL;
1665     int ret = 0;
1666     bool should_rewrite;
1667
1668     should_rewrite = btree_gc_mark_node(b, gc);
1669     if (should_rewrite) {
1670         n = btree_node_alloc_replacement(b, NULL);
1671
1672         if (!IS_ERR_OR_NULL(n)) {
1673             bch_btree_node_write_sync(n);
1674
1675             bch_btree_set_root(n);
1676             btree_node_free(b);
1677             rw_unlock(true, n);
1678
1679             return -EINTR;
1680         }
1681     }
1682
1683     __bch_btree_mark_key(b->c, b->level + 1, &b->key);
1684
1685     if (b->level) {
1686         ret = btree_gc_recurse(b, op, writes, gc);
1687         if (ret)
1688             return ret;
1689     }
1690
1691     bkey_copy_key(&b->c->gc_done, &b->key);
1692
1693     return ret;
1694 }
1695
1696 static void btree_gc_start(struct cache_set *c)
1697 {
1698     struct cache *ca;
1699     struct bucket *b;
1700
1701     if (!c->gc_mark_valid)
1702         return;
1703
1704     mutex_lock(&c->bucket_lock);
1705
1706     c->gc_mark_valid = 0;
1707     c->gc_done = ZERO_KEY;
1708
1709     ca = c->cache;
1710     for_each_bucket(b, ca) {
1711         b->last_gc = b->gen;
1712         if (!atomic_read(&b->pin)) {
1713             SET_GC_MARK(b, 0);
1714             SET_GC_SECTORS_USED(b, 0);
1715         }
1716     }
1717
1718     mutex_unlock(&c->bucket_lock);
1719 }
1720
1721 static void bch_btree_gc_finish(struct cache_set *c)
1722 {
1723     struct bucket *b;
1724     struct cache *ca;
1725     unsigned int i, j;
1726     uint64_t *k;
1727
1728     mutex_lock(&c->bucket_lock);
1729
1730     set_gc_sectors(c);
1731     c->gc_mark_valid = 1;
1732     c->need_gc  = 0;
1733
1734     for (i = 0; i < KEY_PTRS(&c->uuid_bucket); i++)
1735         SET_GC_MARK(PTR_BUCKET(c, &c->uuid_bucket, i),
1736                 GC_MARK_METADATA);
1737
1738     /* don't reclaim buckets to which writeback keys point */
1739     rcu_read_lock();
1740     for (i = 0; i < c->devices_max_used; i++) {
1741         struct bcache_device *d = c->devices[i];
1742         struct cached_dev *dc;
1743         struct keybuf_key *w, *n;
1744
1745         if (!d || UUID_FLASH_ONLY(&c->uuids[i]))
1746             continue;
1747         dc = container_of(d, struct cached_dev, disk);
1748
1749         spin_lock(&dc->writeback_keys.lock);
1750         rbtree_postorder_for_each_entry_safe(w, n,
1751                     &dc->writeback_keys.keys, node)
1752             for (j = 0; j < KEY_PTRS(&w->key); j++)
1753                 SET_GC_MARK(PTR_BUCKET(c, &w->key, j),
1754                         GC_MARK_DIRTY);
1755         spin_unlock(&dc->writeback_keys.lock);
1756     }
1757     rcu_read_unlock();
1758
1759     c->avail_nbuckets = 0;
1760
1761     ca = c->cache;
1762     ca->invalidate_needs_gc = 0;
1763
1764     for (k = ca->sb.d; k < ca->sb.d + ca->sb.keys; k++)
1765         SET_GC_MARK(ca->buckets + *k, GC_MARK_METADATA);
1766
1767     for (k = ca->prio_buckets;
1768          k < ca->prio_buckets + prio_buckets(ca) * 2; k++)
1769         SET_GC_MARK(ca->buckets + *k, GC_MARK_METADATA);
1770
1771     for_each_bucket(b, ca) {
1772         c->need_gc  = max(c->need_gc, bucket_gc_gen(b));
1773
1774         if (atomic_read(&b->pin))
1775             continue;
1776
1777         BUG_ON(!GC_MARK(b) && GC_SECTORS_USED(b));
1778
1779         if (!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE)
1780             c->avail_nbuckets++;
1781     }
1782
1783     mutex_unlock(&c->bucket_lock);
1784 }
1785
1786 static void bch_btree_gc(struct cache_set *c)
1787 {
1788     int ret;
1789     struct gc_stat stats;
1790     struct closure writes;
1791     struct btree_op op;
1792     uint64_t start_time = local_clock();
1793
1794     trace_bcache_gc_start(c);
1795
1796     memset(&stats, 0, sizeof(struct gc_stat));
1797     closure_init_stack(&writes);
1798     bch_btree_op_init(&op, SHRT_MAX);
1799
1800     btree_gc_start(c);
1801
1802     /* if CACHE_SET_IO_DISABLE set, gc thread should stop too */
1803     do {
1804         ret = bcache_btree_root(gc_root, c, &op, &writes, &stats);
1805         closure_sync(&writes);
1806         cond_resched();
1807
1808         if (ret == -EAGAIN)
1809             schedule_timeout_interruptible(msecs_to_jiffies
1810                                (GC_SLEEP_MS));
1811         else if (ret)
1812             pr_warn("gc failed!\n");
1813     } while (ret && !test_bit(CACHE_SET_IO_DISABLE, &c->flags));
1814
1815     bch_btree_gc_finish(c);
1816     wake_up_allocators(c);
1817
1818     bch_time_stats_update(&c->btree_gc_time, start_time);
1819
1820     stats.key_bytes *= sizeof(uint64_t);
1821     stats.data  <<= 9;
1822     bch_update_bucket_in_use(c, &stats);
1823     memcpy(&c->gc_stats, &stats, sizeof(struct gc_stat));
1824
1825     trace_bcache_gc_end(c);
1826
1827     bch_moving_gc(c);
1828 }
1829
1830 static bool gc_should_run(struct cache_set *c)
1831 {
1832     struct cache *ca = c->cache;
1833
1834     if (ca->invalidate_needs_gc)
1835         return true;
1836
1837     if (atomic_read(&c->sectors_to_gc) < 0)
1838         return true;
1839
1840     return false;
1841 }
1842
1843 static int bch_gc_thread(void *arg)
1844 {
1845     struct cache_set *c = arg;
1846
1847     while (1) {
1848         wait_event_interruptible(c->gc_wait,
1849                kthread_should_stop() ||
1850                test_bit(CACHE_SET_IO_DISABLE, &c->flags) ||
1851                gc_should_run(c));
1852
1853         if (kthread_should_stop() ||
1854             test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1855             break;
1856
1857         set_gc_sectors(c);
1858         bch_btree_gc(c);
1859     }
1860
1861     wait_for_kthread_stop();
1862     return 0;
1863 }
1864
1865 int bch_gc_thread_start(struct cache_set *c)
1866 {
1867     c->gc_thread = kthread_run(bch_gc_thread, c, "bcache_gc");
1868     return PTR_ERR_OR_ZERO(c->gc_thread);
1869 }
1870
1871 /* Initial partial gc */
1872
1873 static int bch_btree_check_recurse(struct btree *b, struct btree_op *op)
1874 {
1875     int ret = 0;
1876     struct bkey *k, *p = NULL;
1877     struct btree_iter iter;
1878
1879     for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid)
1880         bch_initial_mark_key(b->c, b->level, k);
1881
1882     bch_initial_mark_key(b->c, b->level + 1, &b->key);
1883
1884     if (b->level) {
1885         bch_btree_iter_init(&b->keys, &iter, NULL);
1886
1887         do {
1888             k = bch_btree_iter_next_filter(&iter, &b->keys,
1889                                bch_ptr_bad);
1890             if (k) {
1891                 btree_node_prefetch(b, k);
1892                 /*
1893                  * initiallize c->gc_stats.nodes
1894                  * for incremental GC
1895                  */
1896                 b->c->gc_stats.nodes++;
1897             }
1898
1899             if (p)
1900                 ret = bcache_btree(check_recurse, p, b, op);
1901
1902             p = k;
1903         } while (p && !ret);
1904     }
1905
1906     return ret;
1907 }
1908
1909
1910 static int bch_btree_check_thread(void *arg)
1911 {
1912     int ret;
1913     struct btree_check_info *info = arg;
1914     struct btree_check_state *check_state = info->state;
1915     struct cache_set *c = check_state->c;
1916     struct btree_iter iter;
1917     struct bkey *k, *p;
1918     int cur_idx, prev_idx, skip_nr;
1919
1920     k = p = NULL;
1921     cur_idx = prev_idx = 0;
1922     ret = 0;
1923
1924     /* root node keys are checked before thread created */
1925     bch_btree_iter_init(&c->root->keys, &iter, NULL);
1926     k = bch_btree_iter_next_filter(&iter, &c->root->keys, bch_ptr_bad);
1927     BUG_ON(!k);
1928
1929     p = k;
1930     while (k) {
1931         /*
1932          * Fetch a root node key index, skip the keys which
1933          * should be fetched by other threads, then check the
1934          * sub-tree indexed by the fetched key.
1935          */
1936         spin_lock(&check_state->idx_lock);
1937         cur_idx = check_state->key_idx;
1938         check_state->key_idx++;
1939         spin_unlock(&check_state->idx_lock);
1940
1941         skip_nr = cur_idx - prev_idx;
1942
1943         while (skip_nr) {
1944             k = bch_btree_iter_next_filter(&iter,
1945                                &c->root->keys,
1946                                bch_ptr_bad);
1947             if (k)
1948                 p = k;
1949             else {
1950                 /*
1951                  * No more keys to check in root node,
1952                  * current checking threads are enough,
1953                  * stop creating more.
1954                  */
1955                 atomic_set(&check_state->enough, 1);
1956                 /* Update check_state->enough earlier */
1957                 smp_mb__after_atomic();
1958                 goto out;
1959             }
1960             skip_nr--;
1961             cond_resched();
1962         }
1963
1964         if (p) {
1965             struct btree_op op;
1966
1967             btree_node_prefetch(c->root, p);
1968             c->gc_stats.nodes++;
1969             bch_btree_op_init(&op, 0);
1970             ret = bcache_btree(check_recurse, p, c->root, &op);
1971             if (ret)
1972                 goto out;
1973         }
1974         p = NULL;
1975         prev_idx = cur_idx;
1976         cond_resched();
1977     }
1978
1979 out:
1980     info->result = ret;
1981     /* update check_state->started among all CPUs */
1982     smp_mb__before_atomic();
1983     if (atomic_dec_and_test(&check_state->started))
1984         wake_up(&check_state->wait);
1985
1986     return ret;
1987 }
1988
1989
1990
1991 static int bch_btree_chkthread_nr(void)
1992 {
1993     int n = num_online_cpus()/2;
1994
1995     if (n == 0)
1996         n = 1;
1997     else if (n > BCH_BTR_CHKTHREAD_MAX)
1998         n = BCH_BTR_CHKTHREAD_MAX;
1999
2000     return n;
2001 }
2002
2003 int bch_btree_check(struct cache_set *c)
2004 {
2005     int ret = 0;
2006     int i;
2007     struct bkey *k = NULL;
2008     struct btree_iter iter;
2009     struct btree_check_state check_state;
2010
2011     /* check and mark root node keys */
2012     for_each_key_filter(&c->root->keys, k, &iter, bch_ptr_invalid)
2013         bch_initial_mark_key(c, c->root->level, k);
2014
2015     bch_initial_mark_key(c, c->root->level + 1, &c->root->key);
2016
2017     if (c->root->level == 0)
2018         return 0;
2019
2020     memset(&check_state, 0, sizeof(struct btree_check_state));
2021     check_state.c = c;
2022     check_state.total_threads = bch_btree_chkthread_nr();
2023     check_state.key_idx = 0;
2024     spin_lock_init(&check_state.idx_lock);
2025     atomic_set(&check_state.started, 0);
2026     atomic_set(&check_state.enough, 0);
2027     init_waitqueue_head(&check_state.wait);
2028
2029     rw_lock(0, c->root, c->root->level);
2030     /*
2031      * Run multiple threads to check btree nodes in parallel,
2032      * if check_state.enough is non-zero, it means current
2033      * running check threads are enough, unncessary to create
2034      * more.
2035      */
2036     for (i = 0; i < check_state.total_threads; i++) {
2037         /* fetch latest check_state.enough earlier */
2038         smp_mb__before_atomic();
2039         if (atomic_read(&check_state.enough))
2040             break;
2041
2042         check_state.infos[i].result = 0;
2043         check_state.infos[i].state = &check_state;
2044
2045         check_state.infos[i].thread =
2046             kthread_run(bch_btree_check_thread,
2047                     &check_state.infos[i],
2048                     "bch_btrchk[%d]", i);
2049         if (IS_ERR(check_state.infos[i].thread)) {
2050             pr_err("fails to run thread bch_btrchk[%d]\n", i);
2051             for (--i; i >= 0; i--)
2052                 kthread_stop(check_state.infos[i].thread);
2053             ret = -ENOMEM;
2054             goto out;
2055         }
2056         atomic_inc(&check_state.started);
2057     }
2058
2059     /*
2060      * Must wait for all threads to stop.
2061      */
2062     wait_event(check_state.wait, atomic_read(&check_state.started) == 0);
2063
2064     for (i = 0; i < check_state.total_threads; i++) {
2065         if (check_state.infos[i].result) {
2066             ret = check_state.infos[i].result;
2067             goto out;
2068         }
2069     }
2070
2071 out:
2072     rw_unlock(0, c->root);
2073     return ret;
2074 }
2075
2076 void bch_initial_gc_finish(struct cache_set *c)
2077 {
2078     struct cache *ca = c->cache;
2079     struct bucket *b;
2080
2081     bch_btree_gc_finish(c);
2082
2083     mutex_lock(&c->bucket_lock);
2084
2085     /*
2086      * We need to put some unused buckets directly on the prio freelist in
2087      * order to get the allocator thread started - it needs freed buckets in
2088      * order to rewrite the prios and gens, and it needs to rewrite prios
2089      * and gens in order to free buckets.
2090      *
2091      * This is only safe for buckets that have no live data in them, which
2092      * there should always be some of.
2093      */
2094     for_each_bucket(b, ca) {
2095         if (fifo_full(&ca->free[RESERVE_PRIO]) &&
2096             fifo_full(&ca->free[RESERVE_BTREE]))
2097             break;
2098
2099         if (bch_can_invalidate_bucket(ca, b) &&
2100             !GC_MARK(b)) {
2101             __bch_invalidate_one_bucket(ca, b);
2102             if (!fifo_push(&ca->free[RESERVE_PRIO],
2103                b - ca->buckets))
2104                 fifo_push(&ca->free[RESERVE_BTREE],
2105                       b - ca->buckets);
2106         }
2107     }
2108
2109     mutex_unlock(&c->bucket_lock);
2110 }
2111
2112 /* Btree insertion */
2113
2114 static bool btree_insert_key(struct btree *b, struct bkey *k,
2115                  struct bkey *replace_key)
2116 {
2117     unsigned int status;
2118
2119     BUG_ON(bkey_cmp(k, &b->key) > 0);
2120
2121     status = bch_btree_insert_key(&b->keys, k, replace_key);
2122     if (status != BTREE_INSERT_STATUS_NO_INSERT) {
2123         bch_check_keys(&b->keys, "%u for %s", status,
2124                    replace_key ? "replace" : "insert");
2125
2126         trace_bcache_btree_insert_key(b, k, replace_key != NULL,
2127                           status);
2128         return true;
2129     } else
2130         return false;
2131 }
2132
2133 static size_t insert_u64s_remaining(struct btree *b)
2134 {
2135     long ret = bch_btree_keys_u64s_remaining(&b->keys);
2136
2137     /*
2138      * Might land in the middle of an existing extent and have to split it
2139      */
2140     if (b->keys.ops->is_extents)
2141         ret -= KEY_MAX_U64S;
2142
2143     return max(ret, 0L);
2144 }
2145
2146 static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
2147                   struct keylist *insert_keys,
2148                   struct bkey *replace_key)
2149 {
2150     bool ret = false;
2151     int oldsize = bch_count_data(&b->keys);
2152
2153     while (!bch_keylist_empty(insert_keys)) {
2154         struct bkey *k = insert_keys->keys;
2155
2156         if (bkey_u64s(k) > insert_u64s_remaining(b))
2157             break;
2158
2159         if (bkey_cmp(k, &b->key) <= 0) {
2160             if (!b->level)
2161                 bkey_put(b->c, k);
2162
2163             ret |= btree_insert_key(b, k, replace_key);
2164             bch_keylist_pop_front(insert_keys);
2165         } else if (bkey_cmp(&START_KEY(k), &b->key) < 0) {
2166             BKEY_PADDED(key) temp;
2167             bkey_copy(&temp.key, insert_keys->keys);
2168
2169             bch_cut_back(&b->key, &temp.key);
2170             bch_cut_front(&b->key, insert_keys->keys);
2171
2172             ret |= btree_insert_key(b, &temp.key, replace_key);
2173             break;
2174         } else {
2175             break;
2176         }
2177     }
2178
2179     if (!ret)
2180         op->insert_collision = true;
2181
2182     BUG_ON(!bch_keylist_empty(insert_keys) && b->level);
2183
2184     BUG_ON(bch_count_data(&b->keys) < oldsize);
2185     return ret;
2186 }
2187
2188 static int btree_split(struct btree *b, struct btree_op *op,
2189                struct keylist *insert_keys,
2190                struct bkey *replace_key)
2191 {
2192     bool split;
2193     struct btree *n1, *n2 = NULL, *n3 = NULL;
2194     uint64_t start_time = local_clock();
2195     struct closure cl;
2196     struct keylist parent_keys;
2197
2198     closure_init_stack(&cl);
2199     bch_keylist_init(&parent_keys);
2200
2201     if (btree_check_reserve(b, op)) {
2202         if (!b->level)
2203             return -EINTR;
2204         else
2205             WARN(1, "insufficient reserve for split\n");
2206     }
2207
2208     n1 = btree_node_alloc_replacement(b, op);
2209     if (IS_ERR(n1))
2210         goto err;
2211
2212     split = set_blocks(btree_bset_first(n1),
2213                block_bytes(n1->c->cache)) > (btree_blocks(b) * 4) / 5;
2214
2215     if (split) {
2216         unsigned int keys = 0;
2217
2218         trace_bcache_btree_node_split(b, btree_bset_first(n1)->keys);
2219
2220         n2 = bch_btree_node_alloc(b->c, op, b->level, b->parent);
2221         if (IS_ERR(n2))
2222             goto err_free1;
2223
2224         if (!b->parent) {
2225             n3 = bch_btree_node_alloc(b->c, op, b->level + 1, NULL);
2226             if (IS_ERR(n3))
2227                 goto err_free2;
2228         }
2229
2230         mutex_lock(&n1->write_lock);
2231         mutex_lock(&n2->write_lock);
2232
2233         bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2234
2235         /*
2236          * Has to be a linear search because we don't have an auxiliary
2237          * search tree yet
2238          */
2239
2240         while (keys < (btree_bset_first(n1)->keys * 3) / 5)
2241             keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1),
2242                             keys));
2243
2244         bkey_copy_key(&n1->key,
2245                   bset_bkey_idx(btree_bset_first(n1), keys));
2246         keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1), keys));
2247
2248         btree_bset_first(n2)->keys = btree_bset_first(n1)->keys - keys;
2249         btree_bset_first(n1)->keys = keys;
2250
2251         memcpy(btree_bset_first(n2)->start,
2252                bset_bkey_last(btree_bset_first(n1)),
2253                btree_bset_first(n2)->keys * sizeof(uint64_t));
2254
2255         bkey_copy_key(&n2->key, &b->key);
2256
2257         bch_keylist_add(&parent_keys, &n2->key);
2258         bch_btree_node_write(n2, &cl);
2259         mutex_unlock(&n2->write_lock);
2260         rw_unlock(true, n2);
2261     } else {
2262         trace_bcache_btree_node_compact(b, btree_bset_first(n1)->keys);
2263
2264         mutex_lock(&n1->write_lock);
2265         bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2266     }
2267
2268     bch_keylist_add(&parent_keys, &n1->key);
2269     bch_btree_node_write(n1, &cl);
2270     mutex_unlock(&n1->write_lock);
2271
2272     if (n3) {
2273         /* Depth increases, make a new root */
2274         mutex_lock(&n3->write_lock);
2275         bkey_copy_key(&n3->key, &MAX_KEY);
2276         bch_btree_insert_keys(n3, op, &parent_keys, NULL);
2277         bch_btree_node_write(n3, &cl);
2278         mutex_unlock(&n3->write_lock);
2279
2280         closure_sync(&cl);
2281         bch_btree_set_root(n3);
2282         rw_unlock(true, n3);
2283     } else if (!b->parent) {
2284         /* Root filled up but didn't need to be split */
2285         closure_sync(&cl);
2286         bch_btree_set_root(n1);
2287     } else {
2288         /* Split a non root node */
2289         closure_sync(&cl);
2290         make_btree_freeing_key(b, parent_keys.top);
2291         bch_keylist_push(&parent_keys);
2292
2293         bch_btree_insert_node(b->parent, op, &parent_keys, NULL, NULL);
2294         BUG_ON(!bch_keylist_empty(&parent_keys));
2295     }
2296
2297     btree_node_free(b);
2298     rw_unlock(true, n1);
2299
2300     bch_time_stats_update(&b->c->btree_split_time, start_time);
2301
2302     return 0;
2303 err_free2:
2304     bkey_put(b->c, &n2->key);
2305     btree_node_free(n2);
2306     rw_unlock(true, n2);
2307 err_free1:
2308     bkey_put(b->c, &n1->key);
2309     btree_node_free(n1);
2310     rw_unlock(true, n1);
2311 err:
2312     WARN(1, "bcache: btree split failed (level %u)", b->level);
2313
2314     if (n3 == ERR_PTR(-EAGAIN) ||
2315         n2 == ERR_PTR(-EAGAIN) ||
2316         n1 == ERR_PTR(-EAGAIN))
2317         return -EAGAIN;
2318
2319     return -ENOMEM;
2320 }
2321
2322 static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
2323                  struct keylist *insert_keys,
2324                  atomic_t *journal_ref,
2325                  struct bkey *replace_key)
2326 {
2327     struct closure cl;
2328
2329     BUG_ON(b->level && replace_key);
2330
2331     closure_init_stack(&cl);
2332
2333     mutex_lock(&b->write_lock);
2334
2335     if (write_block(b) != btree_bset_last(b) &&
2336         b->keys.last_set_unwritten)
2337         bch_btree_init_next(b); /* just wrote a set */
2338
2339     if (bch_keylist_nkeys(insert_keys) > insert_u64s_remaining(b)) {
2340         mutex_unlock(&b->write_lock);
2341         goto split;
2342     }
2343
2344     BUG_ON(write_block(b) != btree_bset_last(b));
2345
2346     if (bch_btree_insert_keys(b, op, insert_keys, replace_key)) {
2347         if (!b->level)
2348             bch_btree_leaf_dirty(b, journal_ref);
2349         else
2350             bch_btree_node_write(b, &cl);
2351     }
2352
2353     mutex_unlock(&b->write_lock);
2354
2355     /* wait for btree node write if necessary, after unlock */
2356     closure_sync(&cl);
2357
2358     return 0;
2359 split:
2360     if (current->bio_list) {
2361         op->lock = b->c->root->level + 1;
2362         return -EAGAIN;
2363     } else if (op->lock <= b->c->root->level) {
2364         op->lock = b->c->root->level + 1;
2365         return -EINTR;
2366     } else {
2367         /* Invalidated all iterators */
2368         int ret = btree_split(b, op, insert_keys, replace_key);
2369
2370         if (bch_keylist_empty(insert_keys))
2371             return 0;
2372         else if (!ret)
2373             return -EINTR;
2374         return ret;
2375     }
2376 }
2377
2378 int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
2379                    struct bkey *check_key)
2380 {
2381     int ret = -EINTR;
2382     uint64_t btree_ptr = b->key.ptr[0];
2383     unsigned long seq = b->seq;
2384     struct keylist insert;
2385     bool upgrade = op->lock == -1;
2386
2387     bch_keylist_init(&insert);
2388
2389     if (upgrade) {
2390         rw_unlock(false, b);
2391         rw_lock(true, b, b->level);
2392
2393         if (b->key.ptr[0] != btree_ptr ||
2394             b->seq != seq + 1) {
2395             op->lock = b->level;
2396             goto out;
2397         }
2398     }
2399
2400     SET_KEY_PTRS(check_key, 1);
2401     get_random_bytes(&check_key->ptr[0], sizeof(uint64_t));
2402
2403     SET_PTR_DEV(check_key, 0, PTR_CHECK_DEV);
2404
2405     bch_keylist_add(&insert, check_key);
2406
2407     ret = bch_btree_insert_node(b, op, &insert, NULL, NULL);
2408
2409     BUG_ON(!ret && !bch_keylist_empty(&insert));
2410 out:
2411     if (upgrade)
2412         downgrade_write(&b->lock);
2413     return ret;
2414 }
2415
2416 struct btree_insert_op {
2417     struct btree_op op;
2418     struct keylist  *keys;
2419     atomic_t    *journal_ref;
2420     struct bkey *replace_key;
2421 };
2422
2423 static int btree_insert_fn(struct btree_op *b_op, struct btree *b)
2424 {
2425     struct btree_insert_op *op = container_of(b_op,
2426                     struct btree_insert_op, op);
2427
2428     int ret = bch_btree_insert_node(b, &op->op, op->keys,
2429                     op->journal_ref, op->replace_key);
2430     if (ret && !bch_keylist_empty(op->keys))
2431         return ret;
2432     else
2433         return MAP_DONE;
2434 }
2435
2436 int bch_btree_insert(struct cache_set *c, struct keylist *keys,
2437              atomic_t *journal_ref, struct bkey *replace_key)
2438 {
2439     struct btree_insert_op op;
2440     int ret = 0;
2441
2442     BUG_ON(current->bio_list);
2443     BUG_ON(bch_keylist_empty(keys));
2444
2445     bch_btree_op_init(&op.op, 0);
2446     op.keys     = keys;
2447     op.journal_ref  = journal_ref;
2448     op.replace_key  = replace_key;
2449
2450     while (!ret && !bch_keylist_empty(keys)) {
2451         op.op.lock = 0;
2452         ret = bch_btree_map_leaf_nodes(&op.op, c,
2453                            &START_KEY(keys->keys),
2454                            btree_insert_fn);
2455     }
2456
2457     if (ret) {
2458         struct bkey *k;
2459
2460         pr_err("error %i\n", ret);
2461
2462         while ((k = bch_keylist_pop(keys)))
2463             bkey_put(c, k);
2464     } else if (op.op.insert_collision)
2465         ret = -ESRCH;
2466
2467     return ret;
2468 }
2469
2470 void bch_btree_set_root(struct btree *b)
2471 {
2472     unsigned int i;
2473     struct closure cl;
2474
2475     closure_init_stack(&cl);
2476
2477     trace_bcache_btree_set_root(b);
2478
2479     BUG_ON(!b->written);
2480
2481     for (i = 0; i < KEY_PTRS(&b->key); i++)
2482         BUG_ON(PTR_BUCKET(b->c, &b->key, i)->prio != BTREE_PRIO);
2483
2484     mutex_lock(&b->c->bucket_lock);
2485     list_del_init(&b->list);
2486     mutex_unlock(&b->c->bucket_lock);
2487
2488     b->c->root = b;
2489
2490     bch_journal_meta(b->c, &cl);
2491     closure_sync(&cl);
2492 }
2493
2494 /* Map across nodes or keys */
2495
2496 static int bch_btree_map_nodes_recurse(struct btree *b, struct btree_op *op,
2497                        struct bkey *from,
2498                        btree_map_nodes_fn *fn, int flags)
2499 {
2500     int ret = MAP_CONTINUE;
2501
2502     if (b->level) {
2503         struct bkey *k;
2504         struct btree_iter iter;
2505
2506         bch_btree_iter_init(&b->keys, &iter, from);
2507
2508         while ((k = bch_btree_iter_next_filter(&iter, &b->keys,
2509                                bch_ptr_bad))) {
2510             ret = bcache_btree(map_nodes_recurse, k, b,
2511                     op, from, fn, flags);
2512             from = NULL;
2513
2514             if (ret != MAP_CONTINUE)
2515                 return ret;
2516         }
2517     }
2518
2519     if (!b->level || flags == MAP_ALL_NODES)
2520         ret = fn(op, b);
2521
2522     return ret;
2523 }
2524
2525 int __bch_btree_map_nodes(struct btree_op *op, struct cache_set *c,
2526               struct bkey *from, btree_map_nodes_fn *fn, int flags)
2527 {
2528     return bcache_btree_root(map_nodes_recurse, c, op, from, fn, flags);
2529 }
2530
2531 int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op,
2532                       struct bkey *from, btree_map_keys_fn *fn,
2533                       int flags)
2534 {
2535     int ret = MAP_CONTINUE;
2536     struct bkey *k;
2537     struct btree_iter iter;
2538
2539     bch_btree_iter_init(&b->keys, &iter, from);
2540
2541     while ((k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad))) {
2542         ret = !b->level
2543             ? fn(op, b, k)
2544             : bcache_btree(map_keys_recurse, k,
2545                        b, op, from, fn, flags);
2546         from = NULL;
2547
2548         if (ret != MAP_CONTINUE)
2549             return ret;
2550     }
2551
2552     if (!b->level && (flags & MAP_END_KEY))
2553         ret = fn(op, b, &KEY(KEY_INODE(&b->key),
2554                      KEY_OFFSET(&b->key), 0));
2555
2556     return ret;
2557 }
2558
2559 int bch_btree_map_keys(struct btree_op *op, struct cache_set *c,
2560                struct bkey *from, btree_map_keys_fn *fn, int flags)
2561 {
2562     return bcache_btree_root(map_keys_recurse, c, op, from, fn, flags);
2563 }
2564
2565 /* Keybuf code */
2566
2567 static inline int keybuf_cmp(struct keybuf_key *l, struct keybuf_key *r)
2568 {
2569     /* Overlapping keys compare equal */
2570     if (bkey_cmp(&l->key, &START_KEY(&r->key)) <= 0)
2571         return -1;
2572     if (bkey_cmp(&START_KEY(&l->key), &r->key) >= 0)
2573         return 1;
2574     return 0;
2575 }
2576
2577 static inline int keybuf_nonoverlapping_cmp(struct keybuf_key *l,
2578                         struct keybuf_key *r)
2579 {
2580     return clamp_t(int64_t, bkey_cmp(&l->key, &r->key), -1, 1);
2581 }
2582
2583 struct refill {
2584     struct btree_op op;
2585     unsigned int    nr_found;
2586     struct keybuf   *buf;
2587     struct bkey *end;
2588     keybuf_pred_fn  *pred;
2589 };
2590
2591 static int refill_keybuf_fn(struct btree_op *op, struct btree *b,
2592                 struct bkey *k)
2593 {
2594     struct refill *refill = container_of(op, struct refill, op);
2595     struct keybuf *buf = refill->buf;
2596     int ret = MAP_CONTINUE;
2597
2598     if (bkey_cmp(k, refill->end) > 0) {
2599         ret = MAP_DONE;
2600         goto out;
2601     }
2602
2603     if (!KEY_SIZE(k)) /* end key */
2604         goto out;
2605
2606     if (refill->pred(buf, k)) {
2607         struct keybuf_key *w;
2608
2609         spin_lock(&buf->lock);
2610
2611         w = array_alloc(&buf->freelist);
2612         if (!w) {
2613             spin_unlock(&buf->lock);
2614             return MAP_DONE;
2615         }
2616
2617         w->private = NULL;
2618         bkey_copy(&w->key, k);
2619
2620         if (RB_INSERT(&buf->keys, w, node, keybuf_cmp))
2621             array_free(&buf->freelist, w);
2622         else
2623             refill->nr_found++;
2624
2625         if (array_freelist_empty(&buf->freelist))
2626             ret = MAP_DONE;
2627
2628         spin_unlock(&buf->lock);
2629     }
2630 out:
2631     buf->last_scanned = *k;
2632     return ret;
2633 }
2634
2635 void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
2636                struct bkey *end, keybuf_pred_fn *pred)
2637 {
2638     struct bkey start = buf->last_scanned;
2639     struct refill refill;
2640
2641     cond_resched();
2642
2643     bch_btree_op_init(&refill.op, -1);
2644     refill.nr_found = 0;
2645     refill.buf  = buf;
2646     refill.end  = end;
2647     refill.pred = pred;
2648
2649     bch_btree_map_keys(&refill.op, c, &buf->last_scanned,
2650                refill_keybuf_fn, MAP_END_KEY);
2651
2652     trace_bcache_keyscan(refill.nr_found,
2653                  KEY_INODE(&start), KEY_OFFSET(&start),
2654                  KEY_INODE(&buf->last_scanned),
2655                  KEY_OFFSET(&buf->last_scanned));
2656
2657     spin_lock(&buf->lock);
2658
2659     if (!RB_EMPTY_ROOT(&buf->keys)) {
2660         struct keybuf_key *w;
2661
2662         w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2663         buf->start  = START_KEY(&w->key);
2664
2665         w = RB_LAST(&buf->keys, struct keybuf_key, node);
2666         buf->end    = w->key;
2667     } else {
2668         buf->start  = MAX_KEY;
2669         buf->end    = MAX_KEY;
2670     }
2671
2672     spin_unlock(&buf->lock);
2673 }
2674
2675 static void __bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2676 {
2677     rb_erase(&w->node, &buf->keys);
2678     array_free(&buf->freelist, w);
2679 }
2680
2681 void bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2682 {
2683     spin_lock(&buf->lock);
2684     __bch_keybuf_del(buf, w);
2685     spin_unlock(&buf->lock);
2686 }
2687
2688 bool bch_keybuf_check_overlapping(struct keybuf *buf, struct bkey *start,
2689                   struct bkey *end)
2690 {
2691     bool ret = false;
2692     struct keybuf_key *p, *w, s;
2693
2694     s.key = *start;
2695
2696     if (bkey_cmp(end, &buf->start) <= 0 ||
2697         bkey_cmp(start, &buf->end) >= 0)
2698         return false;
2699
2700     spin_lock(&buf->lock);
2701     w = RB_GREATER(&buf->keys, s, node, keybuf_nonoverlapping_cmp);
2702
2703     while (w && bkey_cmp(&START_KEY(&w->key), end) < 0) {
2704         p = w;
2705         w = RB_NEXT(w, node);
2706
2707         if (p->private)
2708             ret = true;
2709         else
2710             __bch_keybuf_del(buf, p);
2711     }
2712
2713     spin_unlock(&buf->lock);
2714     return ret;
2715 }
2716
2717 struct keybuf_key *bch_keybuf_next(struct keybuf *buf)
2718 {
2719     struct keybuf_key *w;
2720
2721     spin_lock(&buf->lock);
2722
2723     w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2724
2725     while (w && w->private)
2726         w = RB_NEXT(w, node);
2727
2728     if (w)
2729         w->private = ERR_PTR(-EINTR);
2730
2731     spin_unlock(&buf->lock);
2732     return w;
2733 }
2734
2735 struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
2736                       struct keybuf *buf,
2737                       struct bkey *end,
2738                       keybuf_pred_fn *pred)
2739 {
2740     struct keybuf_key *ret;
2741
2742     while (1) {
2743         ret = bch_keybuf_next(buf);
2744         if (ret)
2745             break;
2746
2747         if (bkey_cmp(&buf->last_scanned, end) >= 0) {
2748             pr_debug("scan finished\n");
2749             break;
2750         }
2751
2752         bch_refill_keybuf(c, buf, end, pred);
2753     }
2754
2755     return ret;
2756 }
2757
2758 void bch_keybuf_init(struct keybuf *buf)
2759 {
2760     buf->last_scanned   = MAX_KEY;
2761     buf->keys       = RB_ROOT;
2762
2763     spin_lock_init(&buf->lock);
2764     array_allocator_init(&buf->freelist);
2765 }
2766
2767 void bch_btree_exit(void)
2768 {
2769     if (btree_io_wq)
2770         destroy_workqueue(btree_io_wq);
2771 }
2772
2773 int __init bch_btree_init(void)
2774 {
2775     btree_io_wq = alloc_workqueue("bch_btree_io", WQ_MEM_RECLAIM, 0);
2776     if (!btree_io_wq)
2777         return -ENOMEM;
2778
2779     return 0;
2780 }