1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
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
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.
14 * Buckets have an 8 bit counter; freeing is accomplished by incrementing the
15 * counter. Garbage collection is used to remove stale pointers.
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.
21 * All configuration is done via sysfs; see Documentation/admin-guide/bcache.rst.
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>
43 * register_bcache: Return errors out to userspace correctly
45 * Writeback: don't undirty key until after a cache flush
47 * Create an iterator for key pointers
49 * On btree write error, mark bucket such that it won't be freed from the cache
52 * Check for bad keys in replay
54 * Refcount journal entries in journal_replay
57 * Finish incremental gc
58 * Gc should free old UUIDs, data for invalid UUIDs
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
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
68 * Add a tracepoint or somesuch to watch for writeback starvation
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
76 * If data write is less than hard sector size of ssd, round up offset in open
77 * bucket to the next whole sector
79 * Superblock needs to be fleshed out for multiple cache devices
81 * Add a sysfs tunable for the number of writeback IOs in flight
83 * Add a sysfs tunable for the number of open data buckets
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
88 * Test module load/unload
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
97 #define PTR_DIRTY_BIT (((uint64_t) 1 << 36))
99 #define PTR_HASH(c, k) \
100 (((k)->ptr[0] >> c->bucket_bits) | PTR_GEN(k, 0))
102 #define insert_lock(s, b) ((b)->level <= (s)->lock)
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.
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.
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
122 #define btree(fn, key, b, op, ...) \
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, \
128 if (!IS_ERR(_child)) { \
129 _r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__); \
130 rw_unlock(_w, _child); \
132 _r = PTR_ERR(_child); \
137 * btree_root - call a function on the root of the btree
138 * @fn: function to call, which will be passed the child node
140 * @op: pointer to struct btree_op
142 #define btree_root(fn, c, op, ...) \
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__); \
154 bch_cannibalize_unlock(c); \
157 } while (_r == -EINTR); \
159 finish_wait(&(c)->btree_cache_wait, &(op)->wait); \
163 static inline struct bset *write_block(struct btree *b)
165 return ((void *) btree_bset_first(b)) + b->written * block_bytes(b->c);
168 static void bch_btree_init_next(struct btree *b)
170 /* If not a leaf node, always sort */
171 if (b->level && b->keys.nsets)
172 bch_btree_sort(&b->keys, &b->c->sort);
174 bch_btree_sort_lazy(&b->keys, &b->c->sort);
176 if (b->written < btree_blocks(b))
177 bch_bset_init_next(&b->keys, write_block(b),
178 bset_magic(&b->c->sb));
182 /* Btree key manipulation */
184 void bkey_put(struct cache_set *c, struct bkey *k)
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);
195 static uint64_t btree_csum_set(struct btree *b, struct bset *i)
197 uint64_t crc = b->key.ptr[0];
198 void *data = (void *) i + 8, *end = bset_bkey_last(i);
200 crc = bch_crc64_update(crc, data, end - data);
201 return crc ^ 0xffffffffffffffffULL;
204 void bch_btree_node_read_done(struct btree *b)
206 const char *err = "bad btree header";
207 struct bset *i = btree_bset_first(b);
208 struct btree_iter *iter;
210 iter = mempool_alloc(&b->c->fill_iter, GFP_NOIO);
211 iter->size = b->c->sb.bucket_size / b->c->sb.block_size;
214 #ifdef CONFIG_BCACHE_DEBUG
222 b->written < btree_blocks(b) && i->seq == b->keys.set[0].data->seq;
223 i = write_block(b)) {
224 err = "unsupported bset version";
225 if (i->version > BCACHE_BSET_VERSION)
228 err = "bad btree header";
229 if (b->written + set_blocks(i, block_bytes(b->c)) >
234 if (i->magic != bset_magic(&b->c->sb))
237 err = "bad checksum";
238 switch (i->version) {
240 if (i->csum != csum_set(i))
243 case BCACHE_BSET_VERSION:
244 if (i->csum != btree_csum_set(b, i))
250 if (i != b->keys.set[0].data && !i->keys)
253 bch_btree_iter_push(iter, i->start, bset_bkey_last(i));
255 b->written += set_blocks(i, block_bytes(b->c));
258 err = "corrupted btree";
259 for (i = write_block(b);
260 bset_sector_offset(&b->keys, i) < KEY_SIZE(&b->key);
261 i = ((void *) i) + block_bytes(b->c))
262 if (i->seq == b->keys.set[0].data->seq)
265 bch_btree_sort_and_fix_extents(&b->keys, iter, &b->c->sort);
267 i = b->keys.set[0].data;
268 err = "short btree key";
269 if (b->keys.set[0].size &&
270 bkey_cmp(&b->key, &b->keys.set[0].end) < 0)
273 if (b->written < btree_blocks(b))
274 bch_bset_init_next(&b->keys, write_block(b),
275 bset_magic(&b->c->sb));
277 mempool_free(iter, &b->c->fill_iter);
280 set_btree_node_io_error(b);
281 bch_cache_set_error(b->c, "%s at bucket %zu, block %u, %u keys",
282 err, PTR_BUCKET_NR(b->c, &b->key, 0),
283 bset_block_offset(b, i), i->keys);
287 static void btree_node_read_endio(struct bio *bio)
289 struct closure *cl = bio->bi_private;
294 static void bch_btree_node_read(struct btree *b)
296 uint64_t start_time = local_clock();
300 trace_bcache_btree_read(b);
302 closure_init_stack(&cl);
304 bio = bch_bbio_alloc(b->c);
305 bio->bi_iter.bi_size = KEY_SIZE(&b->key) << 9;
306 bio->bi_end_io = btree_node_read_endio;
307 bio->bi_private = &cl;
308 bio->bi_opf = REQ_OP_READ | REQ_META;
310 bch_bio_map(bio, b->keys.set[0].data);
312 bch_submit_bbio(bio, b->c, &b->key, 0);
316 set_btree_node_io_error(b);
318 bch_bbio_free(bio, b->c);
320 if (btree_node_io_error(b))
323 bch_btree_node_read_done(b);
324 bch_time_stats_update(&b->c->btree_read_time, start_time);
328 bch_cache_set_error(b->c, "io error reading bucket %zu",
329 PTR_BUCKET_NR(b->c, &b->key, 0));
332 static void btree_complete_write(struct btree *b, struct btree_write *w)
334 if (w->prio_blocked &&
335 !atomic_sub_return(w->prio_blocked, &b->c->prio_blocked))
336 wake_up_allocators(b->c);
339 atomic_dec_bug(w->journal);
340 __closure_wake_up(&b->c->journal.wait);
347 static void btree_node_write_unlock(struct closure *cl)
349 struct btree *b = container_of(cl, struct btree, io);
354 static void __btree_node_write_done(struct closure *cl)
356 struct btree *b = container_of(cl, struct btree, io);
357 struct btree_write *w = btree_prev_write(b);
359 bch_bbio_free(b->bio, b->c);
361 btree_complete_write(b, w);
363 if (btree_node_dirty(b))
364 schedule_delayed_work(&b->work, 30 * HZ);
366 closure_return_with_destructor(cl, btree_node_write_unlock);
369 static void btree_node_write_done(struct closure *cl)
371 struct btree *b = container_of(cl, struct btree, io);
373 bio_free_pages(b->bio);
374 __btree_node_write_done(cl);
377 static void btree_node_write_endio(struct bio *bio)
379 struct closure *cl = bio->bi_private;
380 struct btree *b = container_of(cl, struct btree, io);
383 set_btree_node_io_error(b);
385 bch_bbio_count_io_errors(b->c, bio, bio->bi_status, "writing btree");
389 static void do_btree_node_write(struct btree *b)
391 struct closure *cl = &b->io;
392 struct bset *i = btree_bset_last(b);
395 i->version = BCACHE_BSET_VERSION;
396 i->csum = btree_csum_set(b, i);
399 b->bio = bch_bbio_alloc(b->c);
401 b->bio->bi_end_io = btree_node_write_endio;
402 b->bio->bi_private = cl;
403 b->bio->bi_iter.bi_size = roundup(set_bytes(i), block_bytes(b->c));
404 b->bio->bi_opf = REQ_OP_WRITE | REQ_META | REQ_FUA;
405 bch_bio_map(b->bio, i);
408 * If we're appending to a leaf node, we don't technically need FUA -
409 * this write just needs to be persisted before the next journal write,
410 * which will be marked FLUSH|FUA.
412 * Similarly if we're writing a new btree root - the pointer is going to
413 * be in the next journal entry.
415 * But if we're writing a new btree node (that isn't a root) or
416 * appending to a non leaf btree node, we need either FUA or a flush
417 * when we write the parent with the new pointer. FUA is cheaper than a
418 * flush, and writes appending to leaf nodes aren't blocking anything so
419 * just make all btree node writes FUA to keep things sane.
422 bkey_copy(&k.key, &b->key);
423 SET_PTR_OFFSET(&k.key, 0, PTR_OFFSET(&k.key, 0) +
424 bset_sector_offset(&b->keys, i));
426 if (!bch_bio_alloc_pages(b->bio, __GFP_NOWARN|GFP_NOWAIT)) {
429 void *base = (void *) ((unsigned long) i & ~(PAGE_SIZE - 1));
431 bio_for_each_segment_all(bv, b->bio, j)
432 memcpy(page_address(bv->bv_page),
433 base + j * PAGE_SIZE, PAGE_SIZE);
435 bch_submit_bbio(b->bio, b->c, &k.key, 0);
437 continue_at(cl, btree_node_write_done, NULL);
440 * No problem for multipage bvec since the bio is
444 bch_bio_map(b->bio, i);
446 bch_submit_bbio(b->bio, b->c, &k.key, 0);
449 continue_at_nobarrier(cl, __btree_node_write_done, NULL);
453 void __bch_btree_node_write(struct btree *b, struct closure *parent)
455 struct bset *i = btree_bset_last(b);
457 lockdep_assert_held(&b->write_lock);
459 trace_bcache_btree_write(b);
461 BUG_ON(current->bio_list);
462 BUG_ON(b->written >= btree_blocks(b));
463 BUG_ON(b->written && !i->keys);
464 BUG_ON(btree_bset_first(b)->seq != i->seq);
465 bch_check_keys(&b->keys, "writing");
467 cancel_delayed_work(&b->work);
469 /* If caller isn't waiting for write, parent refcount is cache set */
471 closure_init(&b->io, parent ?: &b->c->cl);
473 clear_bit(BTREE_NODE_dirty, &b->flags);
474 change_bit(BTREE_NODE_write_idx, &b->flags);
476 do_btree_node_write(b);
478 atomic_long_add(set_blocks(i, block_bytes(b->c)) * b->c->sb.block_size,
479 &PTR_CACHE(b->c, &b->key, 0)->btree_sectors_written);
481 b->written += set_blocks(i, block_bytes(b->c));
484 void bch_btree_node_write(struct btree *b, struct closure *parent)
486 unsigned int nsets = b->keys.nsets;
488 lockdep_assert_held(&b->lock);
490 __bch_btree_node_write(b, parent);
493 * do verify if there was more than one set initially (i.e. we did a
494 * sort) and we sorted down to a single set:
496 if (nsets && !b->keys.nsets)
499 bch_btree_init_next(b);
502 static void bch_btree_node_write_sync(struct btree *b)
506 closure_init_stack(&cl);
508 mutex_lock(&b->write_lock);
509 bch_btree_node_write(b, &cl);
510 mutex_unlock(&b->write_lock);
515 static void btree_node_write_work(struct work_struct *w)
517 struct btree *b = container_of(to_delayed_work(w), struct btree, work);
519 mutex_lock(&b->write_lock);
520 if (btree_node_dirty(b))
521 __bch_btree_node_write(b, NULL);
522 mutex_unlock(&b->write_lock);
525 static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
527 struct bset *i = btree_bset_last(b);
528 struct btree_write *w = btree_current_write(b);
530 lockdep_assert_held(&b->write_lock);
535 if (!btree_node_dirty(b))
536 schedule_delayed_work(&b->work, 30 * HZ);
538 set_btree_node_dirty(b);
542 journal_pin_cmp(b->c, w->journal, journal_ref)) {
543 atomic_dec_bug(w->journal);
548 w->journal = journal_ref;
549 atomic_inc(w->journal);
553 /* Force write if set is too big */
554 if (set_bytes(i) > PAGE_SIZE - 48 &&
556 bch_btree_node_write(b, NULL);
560 * Btree in memory cache - allocation/freeing
561 * mca -> memory cache
564 #define mca_reserve(c) (((c->root && c->root->level) \
565 ? c->root->level : 1) * 8 + 16)
566 #define mca_can_free(c) \
567 max_t(int, 0, c->btree_cache_used - mca_reserve(c))
569 static void mca_data_free(struct btree *b)
571 BUG_ON(b->io_mutex.count != 1);
573 bch_btree_keys_free(&b->keys);
575 b->c->btree_cache_used--;
576 list_move(&b->list, &b->c->btree_cache_freed);
579 static void mca_bucket_free(struct btree *b)
581 BUG_ON(btree_node_dirty(b));
584 hlist_del_init_rcu(&b->hash);
585 list_move(&b->list, &b->c->btree_cache_freeable);
588 static unsigned int btree_order(struct bkey *k)
590 return ilog2(KEY_SIZE(k) / PAGE_SECTORS ?: 1);
593 static void mca_data_alloc(struct btree *b, struct bkey *k, gfp_t gfp)
595 if (!bch_btree_keys_alloc(&b->keys,
597 ilog2(b->c->btree_pages),
600 b->c->btree_cache_used++;
601 list_move(&b->list, &b->c->btree_cache);
603 list_move(&b->list, &b->c->btree_cache_freed);
607 static struct btree *mca_bucket_alloc(struct cache_set *c,
608 struct bkey *k, gfp_t gfp)
610 struct btree *b = kzalloc(sizeof(struct btree), gfp);
615 init_rwsem(&b->lock);
616 lockdep_set_novalidate_class(&b->lock);
617 mutex_init(&b->write_lock);
618 lockdep_set_novalidate_class(&b->write_lock);
619 INIT_LIST_HEAD(&b->list);
620 INIT_DELAYED_WORK(&b->work, btree_node_write_work);
622 sema_init(&b->io_mutex, 1);
624 mca_data_alloc(b, k, gfp);
628 static int mca_reap(struct btree *b, unsigned int min_order, bool flush)
632 closure_init_stack(&cl);
633 lockdep_assert_held(&b->c->bucket_lock);
635 if (!down_write_trylock(&b->lock))
638 BUG_ON(btree_node_dirty(b) && !b->keys.set[0].data);
640 if (b->keys.page_order < min_order)
644 if (btree_node_dirty(b))
647 if (down_trylock(&b->io_mutex))
654 * BTREE_NODE_dirty might be cleared in btree_flush_btree() by
655 * __bch_btree_node_write(). To avoid an extra flush, acquire
656 * b->write_lock before checking BTREE_NODE_dirty bit.
658 mutex_lock(&b->write_lock);
660 * If this btree node is selected in btree_flush_write() by journal
661 * code, delay and retry until the node is flushed by journal code
662 * and BTREE_NODE_journal_flush bit cleared by btree_flush_write().
664 if (btree_node_journal_flush(b)) {
665 pr_debug("bnode %p is flushing by journal, retry", b);
666 mutex_unlock(&b->write_lock);
671 if (btree_node_dirty(b))
672 __bch_btree_node_write(b, &cl);
673 mutex_unlock(&b->write_lock);
677 /* wait for any in flight btree write */
687 static unsigned long bch_mca_scan(struct shrinker *shrink,
688 struct shrink_control *sc)
690 struct cache_set *c = container_of(shrink, struct cache_set, shrink);
692 unsigned long i, nr = sc->nr_to_scan;
693 unsigned long freed = 0;
694 unsigned int btree_cache_used;
696 if (c->shrinker_disabled)
699 if (c->btree_cache_alloc_lock)
702 /* Return -1 if we can't do anything right now */
703 if (sc->gfp_mask & __GFP_IO)
704 mutex_lock(&c->bucket_lock);
705 else if (!mutex_trylock(&c->bucket_lock))
709 * It's _really_ critical that we don't free too many btree nodes - we
710 * have to always leave ourselves a reserve. The reserve is how we
711 * guarantee that allocating memory for a new btree node can always
712 * succeed, so that inserting keys into the btree can always succeed and
713 * IO can always make forward progress:
715 nr /= c->btree_pages;
718 nr = min_t(unsigned long, nr, mca_can_free(c));
721 btree_cache_used = c->btree_cache_used;
722 list_for_each_entry_safe(b, t, &c->btree_cache_freeable, list) {
727 !mca_reap(b, 0, false)) {
735 for (; (nr--) && i < btree_cache_used; i++) {
736 if (list_empty(&c->btree_cache))
739 b = list_first_entry(&c->btree_cache, struct btree, list);
740 list_rotate_left(&c->btree_cache);
743 !mca_reap(b, 0, false)) {
752 mutex_unlock(&c->bucket_lock);
753 return freed * c->btree_pages;
756 static unsigned long bch_mca_count(struct shrinker *shrink,
757 struct shrink_control *sc)
759 struct cache_set *c = container_of(shrink, struct cache_set, shrink);
761 if (c->shrinker_disabled)
764 if (c->btree_cache_alloc_lock)
767 return mca_can_free(c) * c->btree_pages;
770 void bch_btree_cache_free(struct cache_set *c)
775 closure_init_stack(&cl);
777 if (c->shrink.list.next)
778 unregister_shrinker(&c->shrink);
780 mutex_lock(&c->bucket_lock);
782 #ifdef CONFIG_BCACHE_DEBUG
784 list_move(&c->verify_data->list, &c->btree_cache);
786 free_pages((unsigned long) c->verify_ondisk, ilog2(bucket_pages(c)));
789 list_splice(&c->btree_cache_freeable,
792 while (!list_empty(&c->btree_cache)) {
793 b = list_first_entry(&c->btree_cache, struct btree, list);
796 * This function is called by cache_set_free(), no I/O
797 * request on cache now, it is unnecessary to acquire
798 * b->write_lock before clearing BTREE_NODE_dirty anymore.
800 if (btree_node_dirty(b)) {
801 btree_complete_write(b, btree_current_write(b));
802 clear_bit(BTREE_NODE_dirty, &b->flags);
807 while (!list_empty(&c->btree_cache_freed)) {
808 b = list_first_entry(&c->btree_cache_freed,
811 cancel_delayed_work_sync(&b->work);
815 mutex_unlock(&c->bucket_lock);
818 int bch_btree_cache_alloc(struct cache_set *c)
822 for (i = 0; i < mca_reserve(c); i++)
823 if (!mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL))
826 list_splice_init(&c->btree_cache,
827 &c->btree_cache_freeable);
829 #ifdef CONFIG_BCACHE_DEBUG
830 mutex_init(&c->verify_lock);
832 c->verify_ondisk = (void *)
833 __get_free_pages(GFP_KERNEL|__GFP_COMP, ilog2(bucket_pages(c)));
835 c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
837 if (c->verify_data &&
838 c->verify_data->keys.set->data)
839 list_del_init(&c->verify_data->list);
841 c->verify_data = NULL;
844 c->shrink.count_objects = bch_mca_count;
845 c->shrink.scan_objects = bch_mca_scan;
847 c->shrink.batch = c->btree_pages * 2;
849 if (register_shrinker(&c->shrink))
850 pr_warn("bcache: %s: could not register shrinker",
856 /* Btree in memory cache - hash table */
858 static struct hlist_head *mca_hash(struct cache_set *c, struct bkey *k)
860 return &c->bucket_hash[hash_32(PTR_HASH(c, k), BUCKET_HASH_BITS)];
863 static struct btree *mca_find(struct cache_set *c, struct bkey *k)
868 hlist_for_each_entry_rcu(b, mca_hash(c, k), hash)
869 if (PTR_HASH(c, &b->key) == PTR_HASH(c, k))
877 static int mca_cannibalize_lock(struct cache_set *c, struct btree_op *op)
879 spin_lock(&c->btree_cannibalize_lock);
880 if (likely(c->btree_cache_alloc_lock == NULL)) {
881 c->btree_cache_alloc_lock = current;
882 } else if (c->btree_cache_alloc_lock != current) {
884 prepare_to_wait(&c->btree_cache_wait, &op->wait,
885 TASK_UNINTERRUPTIBLE);
886 spin_unlock(&c->btree_cannibalize_lock);
889 spin_unlock(&c->btree_cannibalize_lock);
894 static struct btree *mca_cannibalize(struct cache_set *c, struct btree_op *op,
899 trace_bcache_btree_cache_cannibalize(c);
901 if (mca_cannibalize_lock(c, op))
902 return ERR_PTR(-EINTR);
904 list_for_each_entry_reverse(b, &c->btree_cache, list)
905 if (!mca_reap(b, btree_order(k), false))
908 list_for_each_entry_reverse(b, &c->btree_cache, list)
909 if (!mca_reap(b, btree_order(k), true))
912 WARN(1, "btree cache cannibalize failed\n");
913 return ERR_PTR(-ENOMEM);
917 * We can only have one thread cannibalizing other cached btree nodes at a time,
918 * or we'll deadlock. We use an open coded mutex to ensure that, which a
919 * cannibalize_bucket() will take. This means every time we unlock the root of
920 * the btree, we need to release this lock if we have it held.
922 static void bch_cannibalize_unlock(struct cache_set *c)
924 spin_lock(&c->btree_cannibalize_lock);
925 if (c->btree_cache_alloc_lock == current) {
926 c->btree_cache_alloc_lock = NULL;
927 wake_up(&c->btree_cache_wait);
929 spin_unlock(&c->btree_cannibalize_lock);
932 static struct btree *mca_alloc(struct cache_set *c, struct btree_op *op,
933 struct bkey *k, int level)
937 BUG_ON(current->bio_list);
939 lockdep_assert_held(&c->bucket_lock);
944 /* btree_free() doesn't free memory; it sticks the node on the end of
945 * the list. Check if there's any freed nodes there:
947 list_for_each_entry(b, &c->btree_cache_freeable, list)
948 if (!mca_reap(b, btree_order(k), false))
951 /* We never free struct btree itself, just the memory that holds the on
952 * disk node. Check the freed list before allocating a new one:
954 list_for_each_entry(b, &c->btree_cache_freed, list)
955 if (!mca_reap(b, 0, false)) {
956 mca_data_alloc(b, k, __GFP_NOWARN|GFP_NOIO);
957 if (!b->keys.set[0].data)
963 b = mca_bucket_alloc(c, k, __GFP_NOWARN|GFP_NOIO);
967 BUG_ON(!down_write_trylock(&b->lock));
968 if (!b->keys.set->data)
971 BUG_ON(b->io_mutex.count != 1);
973 bkey_copy(&b->key, k);
974 list_move(&b->list, &c->btree_cache);
975 hlist_del_init_rcu(&b->hash);
976 hlist_add_head_rcu(&b->hash, mca_hash(c, k));
978 lock_set_subclass(&b->lock.dep_map, level + 1, _THIS_IP_);
979 b->parent = (void *) ~0UL;
985 bch_btree_keys_init(&b->keys, &bch_extent_keys_ops,
986 &b->c->expensive_debug_checks);
988 bch_btree_keys_init(&b->keys, &bch_btree_keys_ops,
989 &b->c->expensive_debug_checks);
996 b = mca_cannibalize(c, op, k);
1004 * bch_btree_node_get - find a btree node in the cache and lock it, reading it
1005 * in from disk if necessary.
1007 * If IO is necessary and running under generic_make_request, returns -EAGAIN.
1009 * The btree node will have either a read or a write lock held, depending on
1010 * level and op->lock.
1012 struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op,
1013 struct bkey *k, int level, bool write,
1014 struct btree *parent)
1024 if (current->bio_list)
1025 return ERR_PTR(-EAGAIN);
1027 mutex_lock(&c->bucket_lock);
1028 b = mca_alloc(c, op, k, level);
1029 mutex_unlock(&c->bucket_lock);
1036 bch_btree_node_read(b);
1039 downgrade_write(&b->lock);
1041 rw_lock(write, b, level);
1042 if (PTR_HASH(c, &b->key) != PTR_HASH(c, k)) {
1043 rw_unlock(write, b);
1046 BUG_ON(b->level != level);
1049 if (btree_node_io_error(b)) {
1050 rw_unlock(write, b);
1051 return ERR_PTR(-EIO);
1054 BUG_ON(!b->written);
1059 for (; i <= b->keys.nsets && b->keys.set[i].size; i++) {
1060 prefetch(b->keys.set[i].tree);
1061 prefetch(b->keys.set[i].data);
1064 for (; i <= b->keys.nsets; i++)
1065 prefetch(b->keys.set[i].data);
1070 static void btree_node_prefetch(struct btree *parent, struct bkey *k)
1074 mutex_lock(&parent->c->bucket_lock);
1075 b = mca_alloc(parent->c, NULL, k, parent->level - 1);
1076 mutex_unlock(&parent->c->bucket_lock);
1078 if (!IS_ERR_OR_NULL(b)) {
1080 bch_btree_node_read(b);
1087 static void btree_node_free(struct btree *b)
1089 trace_bcache_btree_node_free(b);
1091 BUG_ON(b == b->c->root);
1094 mutex_lock(&b->write_lock);
1096 * If the btree node is selected and flushing in btree_flush_write(),
1097 * delay and retry until the BTREE_NODE_journal_flush bit cleared,
1098 * then it is safe to free the btree node here. Otherwise this btree
1099 * node will be in race condition.
1101 if (btree_node_journal_flush(b)) {
1102 mutex_unlock(&b->write_lock);
1103 pr_debug("bnode %p journal_flush set, retry", b);
1108 if (btree_node_dirty(b)) {
1109 btree_complete_write(b, btree_current_write(b));
1110 clear_bit(BTREE_NODE_dirty, &b->flags);
1113 mutex_unlock(&b->write_lock);
1115 cancel_delayed_work(&b->work);
1117 mutex_lock(&b->c->bucket_lock);
1118 bch_bucket_free(b->c, &b->key);
1120 mutex_unlock(&b->c->bucket_lock);
1123 struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
1124 int level, bool wait,
1125 struct btree *parent)
1128 struct btree *b = ERR_PTR(-EAGAIN);
1130 mutex_lock(&c->bucket_lock);
1132 if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, wait))
1135 bkey_put(c, &k.key);
1136 SET_KEY_SIZE(&k.key, c->btree_pages * PAGE_SECTORS);
1138 b = mca_alloc(c, op, &k.key, level);
1144 "Tried to allocate bucket that was in btree cache");
1150 bch_bset_init_next(&b->keys, b->keys.set->data, bset_magic(&b->c->sb));
1152 mutex_unlock(&c->bucket_lock);
1154 trace_bcache_btree_node_alloc(b);
1157 bch_bucket_free(c, &k.key);
1159 mutex_unlock(&c->bucket_lock);
1161 trace_bcache_btree_node_alloc_fail(c);
1165 static struct btree *bch_btree_node_alloc(struct cache_set *c,
1166 struct btree_op *op, int level,
1167 struct btree *parent)
1169 return __bch_btree_node_alloc(c, op, level, op != NULL, parent);
1172 static struct btree *btree_node_alloc_replacement(struct btree *b,
1173 struct btree_op *op)
1175 struct btree *n = bch_btree_node_alloc(b->c, op, b->level, b->parent);
1177 if (!IS_ERR_OR_NULL(n)) {
1178 mutex_lock(&n->write_lock);
1179 bch_btree_sort_into(&b->keys, &n->keys, &b->c->sort);
1180 bkey_copy_key(&n->key, &b->key);
1181 mutex_unlock(&n->write_lock);
1187 static void make_btree_freeing_key(struct btree *b, struct bkey *k)
1191 mutex_lock(&b->c->bucket_lock);
1193 atomic_inc(&b->c->prio_blocked);
1195 bkey_copy(k, &b->key);
1196 bkey_copy_key(k, &ZERO_KEY);
1198 for (i = 0; i < KEY_PTRS(k); i++)
1200 bch_inc_gen(PTR_CACHE(b->c, &b->key, i),
1201 PTR_BUCKET(b->c, &b->key, i)));
1203 mutex_unlock(&b->c->bucket_lock);
1206 static int btree_check_reserve(struct btree *b, struct btree_op *op)
1208 struct cache_set *c = b->c;
1210 unsigned int i, reserve = (c->root->level - b->level) * 2 + 1;
1212 mutex_lock(&c->bucket_lock);
1214 for_each_cache(ca, c, i)
1215 if (fifo_used(&ca->free[RESERVE_BTREE]) < reserve) {
1217 prepare_to_wait(&c->btree_cache_wait, &op->wait,
1218 TASK_UNINTERRUPTIBLE);
1219 mutex_unlock(&c->bucket_lock);
1223 mutex_unlock(&c->bucket_lock);
1225 return mca_cannibalize_lock(b->c, op);
1228 /* Garbage collection */
1230 static uint8_t __bch_btree_mark_key(struct cache_set *c, int level,
1238 * ptr_invalid() can't return true for the keys that mark btree nodes as
1239 * freed, but since ptr_bad() returns true we'll never actually use them
1240 * for anything and thus we don't want mark their pointers here
1242 if (!bkey_cmp(k, &ZERO_KEY))
1245 for (i = 0; i < KEY_PTRS(k); i++) {
1246 if (!ptr_available(c, k, i))
1249 g = PTR_BUCKET(c, k, i);
1251 if (gen_after(g->last_gc, PTR_GEN(k, i)))
1252 g->last_gc = PTR_GEN(k, i);
1254 if (ptr_stale(c, k, i)) {
1255 stale = max(stale, ptr_stale(c, k, i));
1259 cache_bug_on(GC_MARK(g) &&
1260 (GC_MARK(g) == GC_MARK_METADATA) != (level != 0),
1261 c, "inconsistent ptrs: mark = %llu, level = %i",
1265 SET_GC_MARK(g, GC_MARK_METADATA);
1266 else if (KEY_DIRTY(k))
1267 SET_GC_MARK(g, GC_MARK_DIRTY);
1268 else if (!GC_MARK(g))
1269 SET_GC_MARK(g, GC_MARK_RECLAIMABLE);
1271 /* guard against overflow */
1272 SET_GC_SECTORS_USED(g, min_t(unsigned int,
1273 GC_SECTORS_USED(g) + KEY_SIZE(k),
1274 MAX_GC_SECTORS_USED));
1276 BUG_ON(!GC_SECTORS_USED(g));
1282 #define btree_mark_key(b, k) __bch_btree_mark_key(b->c, b->level, k)
1284 void bch_initial_mark_key(struct cache_set *c, int level, struct bkey *k)
1288 for (i = 0; i < KEY_PTRS(k); i++)
1289 if (ptr_available(c, k, i) &&
1290 !ptr_stale(c, k, i)) {
1291 struct bucket *b = PTR_BUCKET(c, k, i);
1293 b->gen = PTR_GEN(k, i);
1295 if (level && bkey_cmp(k, &ZERO_KEY))
1296 b->prio = BTREE_PRIO;
1297 else if (!level && b->prio == BTREE_PRIO)
1298 b->prio = INITIAL_PRIO;
1301 __bch_btree_mark_key(c, level, k);
1304 void bch_update_bucket_in_use(struct cache_set *c, struct gc_stat *stats)
1306 stats->in_use = (c->nbuckets - c->avail_nbuckets) * 100 / c->nbuckets;
1309 static bool btree_gc_mark_node(struct btree *b, struct gc_stat *gc)
1312 unsigned int keys = 0, good_keys = 0;
1314 struct btree_iter iter;
1315 struct bset_tree *t;
1319 for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid) {
1320 stale = max(stale, btree_mark_key(b, k));
1323 if (bch_ptr_bad(&b->keys, k))
1326 gc->key_bytes += bkey_u64s(k);
1330 gc->data += KEY_SIZE(k);
1333 for (t = b->keys.set; t <= &b->keys.set[b->keys.nsets]; t++)
1334 btree_bug_on(t->size &&
1335 bset_written(&b->keys, t) &&
1336 bkey_cmp(&b->key, &t->end) < 0,
1337 b, "found short btree key in gc");
1339 if (b->c->gc_always_rewrite)
1345 if ((keys - good_keys) * 2 > keys)
1351 #define GC_MERGE_NODES 4U
1353 struct gc_merge_info {
1358 static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
1359 struct keylist *insert_keys,
1360 atomic_t *journal_ref,
1361 struct bkey *replace_key);
1363 static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
1364 struct gc_stat *gc, struct gc_merge_info *r)
1366 unsigned int i, nodes = 0, keys = 0, blocks;
1367 struct btree *new_nodes[GC_MERGE_NODES];
1368 struct keylist keylist;
1372 bch_keylist_init(&keylist);
1374 if (btree_check_reserve(b, NULL))
1377 memset(new_nodes, 0, sizeof(new_nodes));
1378 closure_init_stack(&cl);
1380 while (nodes < GC_MERGE_NODES && !IS_ERR_OR_NULL(r[nodes].b))
1381 keys += r[nodes++].keys;
1383 blocks = btree_default_blocks(b->c) * 2 / 3;
1386 __set_blocks(b->keys.set[0].data, keys,
1387 block_bytes(b->c)) > blocks * (nodes - 1))
1390 for (i = 0; i < nodes; i++) {
1391 new_nodes[i] = btree_node_alloc_replacement(r[i].b, NULL);
1392 if (IS_ERR_OR_NULL(new_nodes[i]))
1393 goto out_nocoalesce;
1397 * We have to check the reserve here, after we've allocated our new
1398 * nodes, to make sure the insert below will succeed - we also check
1399 * before as an optimization to potentially avoid a bunch of expensive
1402 if (btree_check_reserve(b, NULL))
1403 goto out_nocoalesce;
1405 for (i = 0; i < nodes; i++)
1406 mutex_lock(&new_nodes[i]->write_lock);
1408 for (i = nodes - 1; i > 0; --i) {
1409 struct bset *n1 = btree_bset_first(new_nodes[i]);
1410 struct bset *n2 = btree_bset_first(new_nodes[i - 1]);
1411 struct bkey *k, *last = NULL;
1417 k < bset_bkey_last(n2);
1419 if (__set_blocks(n1, n1->keys + keys +
1421 block_bytes(b->c)) > blocks)
1425 keys += bkey_u64s(k);
1429 * Last node we're not getting rid of - we're getting
1430 * rid of the node at r[0]. Have to try and fit all of
1431 * the remaining keys into this node; we can't ensure
1432 * they will always fit due to rounding and variable
1433 * length keys (shouldn't be possible in practice,
1436 if (__set_blocks(n1, n1->keys + n2->keys,
1437 block_bytes(b->c)) >
1438 btree_blocks(new_nodes[i]))
1439 goto out_unlock_nocoalesce;
1442 /* Take the key of the node we're getting rid of */
1446 BUG_ON(__set_blocks(n1, n1->keys + keys, block_bytes(b->c)) >
1447 btree_blocks(new_nodes[i]));
1450 bkey_copy_key(&new_nodes[i]->key, last);
1452 memcpy(bset_bkey_last(n1),
1454 (void *) bset_bkey_idx(n2, keys) - (void *) n2->start);
1457 r[i].keys = n1->keys;
1460 bset_bkey_idx(n2, keys),
1461 (void *) bset_bkey_last(n2) -
1462 (void *) bset_bkey_idx(n2, keys));
1466 if (__bch_keylist_realloc(&keylist,
1467 bkey_u64s(&new_nodes[i]->key)))
1468 goto out_unlock_nocoalesce;
1470 bch_btree_node_write(new_nodes[i], &cl);
1471 bch_keylist_add(&keylist, &new_nodes[i]->key);
1474 for (i = 0; i < nodes; i++)
1475 mutex_unlock(&new_nodes[i]->write_lock);
1479 /* We emptied out this node */
1480 BUG_ON(btree_bset_first(new_nodes[0])->keys);
1481 btree_node_free(new_nodes[0]);
1482 rw_unlock(true, new_nodes[0]);
1483 new_nodes[0] = NULL;
1485 for (i = 0; i < nodes; i++) {
1486 if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b->key)))
1487 goto out_nocoalesce;
1489 make_btree_freeing_key(r[i].b, keylist.top);
1490 bch_keylist_push(&keylist);
1493 bch_btree_insert_node(b, op, &keylist, NULL, NULL);
1494 BUG_ON(!bch_keylist_empty(&keylist));
1496 for (i = 0; i < nodes; i++) {
1497 btree_node_free(r[i].b);
1498 rw_unlock(true, r[i].b);
1500 r[i].b = new_nodes[i];
1503 memmove(r, r + 1, sizeof(r[0]) * (nodes - 1));
1504 r[nodes - 1].b = ERR_PTR(-EINTR);
1506 trace_bcache_btree_gc_coalesce(nodes);
1509 bch_keylist_free(&keylist);
1511 /* Invalidated our iterator */
1514 out_unlock_nocoalesce:
1515 for (i = 0; i < nodes; i++)
1516 mutex_unlock(&new_nodes[i]->write_lock);
1520 bch_keylist_free(&keylist);
1522 while ((k = bch_keylist_pop(&keylist)))
1523 if (!bkey_cmp(k, &ZERO_KEY))
1524 atomic_dec(&b->c->prio_blocked);
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]);
1534 static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op,
1535 struct btree *replace)
1537 struct keylist keys;
1540 if (btree_check_reserve(b, NULL))
1543 n = btree_node_alloc_replacement(replace, NULL);
1545 /* recheck reserve after allocating replacement node */
1546 if (btree_check_reserve(b, NULL)) {
1552 bch_btree_node_write_sync(n);
1554 bch_keylist_init(&keys);
1555 bch_keylist_add(&keys, &n->key);
1557 make_btree_freeing_key(replace, keys.top);
1558 bch_keylist_push(&keys);
1560 bch_btree_insert_node(b, op, &keys, NULL, NULL);
1561 BUG_ON(!bch_keylist_empty(&keys));
1563 btree_node_free(replace);
1566 /* Invalidated our iterator */
1570 static unsigned int btree_gc_count_keys(struct btree *b)
1573 struct btree_iter iter;
1574 unsigned int ret = 0;
1576 for_each_key_filter(&b->keys, k, &iter, bch_ptr_bad)
1577 ret += bkey_u64s(k);
1582 static size_t btree_gc_min_nodes(struct cache_set *c)
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)
1600 min_nodes = c->gc_stats.nodes / MAX_GC_TIMES;
1601 if (min_nodes < MIN_GC_NODES)
1602 min_nodes = MIN_GC_NODES;
1608 static int btree_gc_recurse(struct btree *b, struct btree_op *op,
1609 struct closure *writes, struct gc_stat *gc)
1612 bool should_rewrite;
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;
1618 bch_btree_iter_init(&b->keys, &iter, &b->c->gc_done);
1620 for (i = r; i < r + ARRAY_SIZE(r); i++)
1621 i->b = ERR_PTR(-EINTR);
1624 k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad);
1626 r->b = bch_btree_node_get(b->c, op, k, b->level - 1,
1629 ret = PTR_ERR(r->b);
1633 r->keys = btree_gc_count_keys(r->b);
1635 ret = btree_gc_coalesce(b, op, gc, r);
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);
1651 if (last->b->level) {
1652 ret = btree_gc_recurse(last->b, op, writes, gc);
1657 bkey_copy_key(&b->c->gc_done, &last->b->key);
1660 * Must flush leaf nodes before gc ends, since replace
1661 * operations aren't journalled
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);
1670 memmove(r + 1, r, sizeof(r[0]) * (GC_MERGE_NODES - 1));
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;
1680 if (need_resched()) {
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);
1698 static int bch_btree_gc_root(struct btree *b, struct btree_op *op,
1699 struct closure *writes, struct gc_stat *gc)
1701 struct btree *n = NULL;
1703 bool should_rewrite;
1705 should_rewrite = btree_gc_mark_node(b, gc);
1706 if (should_rewrite) {
1707 n = btree_node_alloc_replacement(b, NULL);
1709 if (!IS_ERR_OR_NULL(n)) {
1710 bch_btree_node_write_sync(n);
1712 bch_btree_set_root(n);
1720 __bch_btree_mark_key(b->c, b->level + 1, &b->key);
1723 ret = btree_gc_recurse(b, op, writes, gc);
1728 bkey_copy_key(&b->c->gc_done, &b->key);
1733 static void btree_gc_start(struct cache_set *c)
1739 if (!c->gc_mark_valid)
1742 mutex_lock(&c->bucket_lock);
1744 c->gc_mark_valid = 0;
1745 c->gc_done = ZERO_KEY;
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)) {
1752 SET_GC_SECTORS_USED(b, 0);
1756 mutex_unlock(&c->bucket_lock);
1759 static void bch_btree_gc_finish(struct cache_set *c)
1765 mutex_lock(&c->bucket_lock);
1768 c->gc_mark_valid = 1;
1771 for (i = 0; i < KEY_PTRS(&c->uuid_bucket); i++)
1772 SET_GC_MARK(PTR_BUCKET(c, &c->uuid_bucket, i),
1775 /* don't reclaim buckets to which writeback keys point */
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;
1783 if (!d || UUID_FLASH_ONLY(&c->uuids[i]))
1785 dc = container_of(d, struct cached_dev, disk);
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),
1793 spin_unlock(&dc->writeback_keys.lock);
1797 c->avail_nbuckets = 0;
1798 for_each_cache(ca, c, i) {
1801 ca->invalidate_needs_gc = 0;
1803 for (i = ca->sb.d; i < ca->sb.d + ca->sb.keys; i++)
1804 SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
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);
1810 for_each_bucket(b, ca) {
1811 c->need_gc = max(c->need_gc, bucket_gc_gen(b));
1813 if (atomic_read(&b->pin))
1816 BUG_ON(!GC_MARK(b) && GC_SECTORS_USED(b));
1818 if (!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE)
1819 c->avail_nbuckets++;
1823 mutex_unlock(&c->bucket_lock);
1826 static void bch_btree_gc(struct cache_set *c)
1829 struct gc_stat stats;
1830 struct closure writes;
1832 uint64_t start_time = local_clock();
1834 trace_bcache_gc_start(c);
1836 memset(&stats, 0, sizeof(struct gc_stat));
1837 closure_init_stack(&writes);
1838 bch_btree_op_init(&op, SHRT_MAX);
1842 /* if CACHE_SET_IO_DISABLE set, gc thread should stop too */
1844 ret = btree_root(gc_root, c, &op, &writes, &stats);
1845 closure_sync(&writes);
1849 schedule_timeout_interruptible(msecs_to_jiffies
1852 pr_warn("gc failed!");
1853 } while (ret && !test_bit(CACHE_SET_IO_DISABLE, &c->flags));
1855 bch_btree_gc_finish(c);
1856 wake_up_allocators(c);
1858 bch_time_stats_update(&c->btree_gc_time, start_time);
1860 stats.key_bytes *= sizeof(uint64_t);
1862 bch_update_bucket_in_use(c, &stats);
1863 memcpy(&c->gc_stats, &stats, sizeof(struct gc_stat));
1865 trace_bcache_gc_end(c);
1870 static bool gc_should_run(struct cache_set *c)
1875 for_each_cache(ca, c, i)
1876 if (ca->invalidate_needs_gc)
1879 if (atomic_read(&c->sectors_to_gc) < 0)
1885 static int bch_gc_thread(void *arg)
1887 struct cache_set *c = arg;
1890 wait_event_interruptible(c->gc_wait,
1891 kthread_should_stop() ||
1892 test_bit(CACHE_SET_IO_DISABLE, &c->flags) ||
1895 if (kthread_should_stop() ||
1896 test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1903 wait_for_kthread_stop();
1907 int bch_gc_thread_start(struct cache_set *c)
1909 c->gc_thread = kthread_run(bch_gc_thread, c, "bcache_gc");
1910 return PTR_ERR_OR_ZERO(c->gc_thread);
1913 /* Initial partial gc */
1915 static int bch_btree_check_recurse(struct btree *b, struct btree_op *op)
1918 struct bkey *k, *p = NULL;
1919 struct btree_iter iter;
1921 for_each_key_filter(&b->keys, k, &iter, bch_ptr_invalid)
1922 bch_initial_mark_key(b->c, b->level, k);
1924 bch_initial_mark_key(b->c, b->level + 1, &b->key);
1927 bch_btree_iter_init(&b->keys, &iter, NULL);
1930 k = bch_btree_iter_next_filter(&iter, &b->keys,
1933 btree_node_prefetch(b, k);
1935 * initiallize c->gc_stats.nodes
1936 * for incremental GC
1938 b->c->gc_stats.nodes++;
1942 ret = btree(check_recurse, p, b, op);
1945 } while (p && !ret);
1951 int bch_btree_check(struct cache_set *c)
1955 bch_btree_op_init(&op, SHRT_MAX);
1957 return btree_root(check_recurse, c, &op);
1960 void bch_initial_gc_finish(struct cache_set *c)
1966 bch_btree_gc_finish(c);
1968 mutex_lock(&c->bucket_lock);
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.
1976 * This is only safe for buckets that have no live data in them, which
1977 * there should always be some of.
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]))
1985 if (bch_can_invalidate_bucket(ca, b) &&
1987 __bch_invalidate_one_bucket(ca, b);
1988 if (!fifo_push(&ca->free[RESERVE_PRIO],
1990 fifo_push(&ca->free[RESERVE_BTREE],
1996 mutex_unlock(&c->bucket_lock);
1999 /* Btree insertion */
2001 static bool btree_insert_key(struct btree *b, struct bkey *k,
2002 struct bkey *replace_key)
2004 unsigned int status;
2006 BUG_ON(bkey_cmp(k, &b->key) > 0);
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");
2013 trace_bcache_btree_insert_key(b, k, replace_key != NULL,
2020 static size_t insert_u64s_remaining(struct btree *b)
2022 long ret = bch_btree_keys_u64s_remaining(&b->keys);
2025 * Might land in the middle of an existing extent and have to split it
2027 if (b->keys.ops->is_extents)
2028 ret -= KEY_MAX_U64S;
2030 return max(ret, 0L);
2033 static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
2034 struct keylist *insert_keys,
2035 struct bkey *replace_key)
2038 int oldsize = bch_count_data(&b->keys);
2040 while (!bch_keylist_empty(insert_keys)) {
2041 struct bkey *k = insert_keys->keys;
2043 if (bkey_u64s(k) > insert_u64s_remaining(b))
2046 if (bkey_cmp(k, &b->key) <= 0) {
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);
2056 bch_cut_back(&b->key, &temp.key);
2057 bch_cut_front(&b->key, insert_keys->keys);
2059 ret |= btree_insert_key(b, &temp.key, replace_key);
2067 op->insert_collision = true;
2069 BUG_ON(!bch_keylist_empty(insert_keys) && b->level);
2071 BUG_ON(bch_count_data(&b->keys) < oldsize);
2075 static int btree_split(struct btree *b, struct btree_op *op,
2076 struct keylist *insert_keys,
2077 struct bkey *replace_key)
2080 struct btree *n1, *n2 = NULL, *n3 = NULL;
2081 uint64_t start_time = local_clock();
2083 struct keylist parent_keys;
2085 closure_init_stack(&cl);
2086 bch_keylist_init(&parent_keys);
2088 if (btree_check_reserve(b, op)) {
2092 WARN(1, "insufficient reserve for split\n");
2095 n1 = btree_node_alloc_replacement(b, op);
2099 split = set_blocks(btree_bset_first(n1),
2100 block_bytes(n1->c)) > (btree_blocks(b) * 4) / 5;
2103 unsigned int keys = 0;
2105 trace_bcache_btree_node_split(b, btree_bset_first(n1)->keys);
2107 n2 = bch_btree_node_alloc(b->c, op, b->level, b->parent);
2112 n3 = bch_btree_node_alloc(b->c, op, b->level + 1, NULL);
2117 mutex_lock(&n1->write_lock);
2118 mutex_lock(&n2->write_lock);
2120 bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2123 * Has to be a linear search because we don't have an auxiliary
2127 while (keys < (btree_bset_first(n1)->keys * 3) / 5)
2128 keys += bkey_u64s(bset_bkey_idx(btree_bset_first(n1),
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));
2135 btree_bset_first(n2)->keys = btree_bset_first(n1)->keys - keys;
2136 btree_bset_first(n1)->keys = keys;
2138 memcpy(btree_bset_first(n2)->start,
2139 bset_bkey_last(btree_bset_first(n1)),
2140 btree_bset_first(n2)->keys * sizeof(uint64_t));
2142 bkey_copy_key(&n2->key, &b->key);
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);
2149 trace_bcache_btree_node_compact(b, btree_bset_first(n1)->keys);
2151 mutex_lock(&n1->write_lock);
2152 bch_btree_insert_keys(n1, op, insert_keys, replace_key);
2155 bch_keylist_add(&parent_keys, &n1->key);
2156 bch_btree_node_write(n1, &cl);
2157 mutex_unlock(&n1->write_lock);
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);
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 */
2173 bch_btree_set_root(n1);
2175 /* Split a non root node */
2177 make_btree_freeing_key(b, parent_keys.top);
2178 bch_keylist_push(&parent_keys);
2180 bch_btree_insert_node(b->parent, op, &parent_keys, NULL, NULL);
2181 BUG_ON(!bch_keylist_empty(&parent_keys));
2185 rw_unlock(true, n1);
2187 bch_time_stats_update(&b->c->btree_split_time, start_time);
2191 bkey_put(b->c, &n2->key);
2192 btree_node_free(n2);
2193 rw_unlock(true, n2);
2195 bkey_put(b->c, &n1->key);
2196 btree_node_free(n1);
2197 rw_unlock(true, n1);
2199 WARN(1, "bcache: btree split failed (level %u)", b->level);
2201 if (n3 == ERR_PTR(-EAGAIN) ||
2202 n2 == ERR_PTR(-EAGAIN) ||
2203 n1 == ERR_PTR(-EAGAIN))
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)
2216 BUG_ON(b->level && replace_key);
2218 closure_init_stack(&cl);
2220 mutex_lock(&b->write_lock);
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 */
2226 if (bch_keylist_nkeys(insert_keys) > insert_u64s_remaining(b)) {
2227 mutex_unlock(&b->write_lock);
2231 BUG_ON(write_block(b) != btree_bset_last(b));
2233 if (bch_btree_insert_keys(b, op, insert_keys, replace_key)) {
2235 bch_btree_leaf_dirty(b, journal_ref);
2237 bch_btree_node_write(b, &cl);
2240 mutex_unlock(&b->write_lock);
2242 /* wait for btree node write if necessary, after unlock */
2247 if (current->bio_list) {
2248 op->lock = b->c->root->level + 1;
2250 } else if (op->lock <= b->c->root->level) {
2251 op->lock = b->c->root->level + 1;
2254 /* Invalidated all iterators */
2255 int ret = btree_split(b, op, insert_keys, replace_key);
2257 if (bch_keylist_empty(insert_keys))
2265 int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
2266 struct bkey *check_key)
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;
2274 bch_keylist_init(&insert);
2277 rw_unlock(false, b);
2278 rw_lock(true, b, b->level);
2280 if (b->key.ptr[0] != btree_ptr ||
2281 b->seq != seq + 1) {
2282 op->lock = b->level;
2287 SET_KEY_PTRS(check_key, 1);
2288 get_random_bytes(&check_key->ptr[0], sizeof(uint64_t));
2290 SET_PTR_DEV(check_key, 0, PTR_CHECK_DEV);
2292 bch_keylist_add(&insert, check_key);
2294 ret = bch_btree_insert_node(b, op, &insert, NULL, NULL);
2296 BUG_ON(!ret && !bch_keylist_empty(&insert));
2299 downgrade_write(&b->lock);
2303 struct btree_insert_op {
2305 struct keylist *keys;
2306 atomic_t *journal_ref;
2307 struct bkey *replace_key;
2310 static int btree_insert_fn(struct btree_op *b_op, struct btree *b)
2312 struct btree_insert_op *op = container_of(b_op,
2313 struct btree_insert_op, op);
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))
2323 int bch_btree_insert(struct cache_set *c, struct keylist *keys,
2324 atomic_t *journal_ref, struct bkey *replace_key)
2326 struct btree_insert_op op;
2329 BUG_ON(current->bio_list);
2330 BUG_ON(bch_keylist_empty(keys));
2332 bch_btree_op_init(&op.op, 0);
2334 op.journal_ref = journal_ref;
2335 op.replace_key = replace_key;
2337 while (!ret && !bch_keylist_empty(keys)) {
2339 ret = bch_btree_map_leaf_nodes(&op.op, c,
2340 &START_KEY(keys->keys),
2347 pr_err("error %i", ret);
2349 while ((k = bch_keylist_pop(keys)))
2351 } else if (op.op.insert_collision)
2357 void bch_btree_set_root(struct btree *b)
2362 closure_init_stack(&cl);
2364 trace_bcache_btree_set_root(b);
2366 BUG_ON(!b->written);
2368 for (i = 0; i < KEY_PTRS(&b->key); i++)
2369 BUG_ON(PTR_BUCKET(b->c, &b->key, i)->prio != BTREE_PRIO);
2371 mutex_lock(&b->c->bucket_lock);
2372 list_del_init(&b->list);
2373 mutex_unlock(&b->c->bucket_lock);
2377 bch_journal_meta(b->c, &cl);
2381 /* Map across nodes or keys */
2383 static int bch_btree_map_nodes_recurse(struct btree *b, struct btree_op *op,
2385 btree_map_nodes_fn *fn, int flags)
2387 int ret = MAP_CONTINUE;
2391 struct btree_iter iter;
2393 bch_btree_iter_init(&b->keys, &iter, from);
2395 while ((k = bch_btree_iter_next_filter(&iter, &b->keys,
2397 ret = btree(map_nodes_recurse, k, b,
2398 op, from, fn, flags);
2401 if (ret != MAP_CONTINUE)
2406 if (!b->level || flags == MAP_ALL_NODES)
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)
2415 return btree_root(map_nodes_recurse, c, op, from, fn, flags);
2418 static int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op,
2419 struct bkey *from, btree_map_keys_fn *fn,
2422 int ret = MAP_CONTINUE;
2424 struct btree_iter iter;
2426 bch_btree_iter_init(&b->keys, &iter, from);
2428 while ((k = bch_btree_iter_next_filter(&iter, &b->keys, bch_ptr_bad))) {
2431 : btree(map_keys_recurse, k, b, op, from, fn, flags);
2434 if (ret != MAP_CONTINUE)
2438 if (!b->level && (flags & MAP_END_KEY))
2439 ret = fn(op, b, &KEY(KEY_INODE(&b->key),
2440 KEY_OFFSET(&b->key), 0));
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)
2448 return btree_root(map_keys_recurse, c, op, from, fn, flags);
2453 static inline int keybuf_cmp(struct keybuf_key *l, struct keybuf_key *r)
2455 /* Overlapping keys compare equal */
2456 if (bkey_cmp(&l->key, &START_KEY(&r->key)) <= 0)
2458 if (bkey_cmp(&START_KEY(&l->key), &r->key) >= 0)
2463 static inline int keybuf_nonoverlapping_cmp(struct keybuf_key *l,
2464 struct keybuf_key *r)
2466 return clamp_t(int64_t, bkey_cmp(&l->key, &r->key), -1, 1);
2471 unsigned int nr_found;
2474 keybuf_pred_fn *pred;
2477 static int refill_keybuf_fn(struct btree_op *op, struct btree *b,
2480 struct refill *refill = container_of(op, struct refill, op);
2481 struct keybuf *buf = refill->buf;
2482 int ret = MAP_CONTINUE;
2484 if (bkey_cmp(k, refill->end) > 0) {
2489 if (!KEY_SIZE(k)) /* end key */
2492 if (refill->pred(buf, k)) {
2493 struct keybuf_key *w;
2495 spin_lock(&buf->lock);
2497 w = array_alloc(&buf->freelist);
2499 spin_unlock(&buf->lock);
2504 bkey_copy(&w->key, k);
2506 if (RB_INSERT(&buf->keys, w, node, keybuf_cmp))
2507 array_free(&buf->freelist, w);
2511 if (array_freelist_empty(&buf->freelist))
2514 spin_unlock(&buf->lock);
2517 buf->last_scanned = *k;
2521 void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
2522 struct bkey *end, keybuf_pred_fn *pred)
2524 struct bkey start = buf->last_scanned;
2525 struct refill refill;
2529 bch_btree_op_init(&refill.op, -1);
2530 refill.nr_found = 0;
2535 bch_btree_map_keys(&refill.op, c, &buf->last_scanned,
2536 refill_keybuf_fn, MAP_END_KEY);
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));
2543 spin_lock(&buf->lock);
2545 if (!RB_EMPTY_ROOT(&buf->keys)) {
2546 struct keybuf_key *w;
2548 w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2549 buf->start = START_KEY(&w->key);
2551 w = RB_LAST(&buf->keys, struct keybuf_key, node);
2554 buf->start = MAX_KEY;
2558 spin_unlock(&buf->lock);
2561 static void __bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2563 rb_erase(&w->node, &buf->keys);
2564 array_free(&buf->freelist, w);
2567 void bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w)
2569 spin_lock(&buf->lock);
2570 __bch_keybuf_del(buf, w);
2571 spin_unlock(&buf->lock);
2574 bool bch_keybuf_check_overlapping(struct keybuf *buf, struct bkey *start,
2578 struct keybuf_key *p, *w, s;
2582 if (bkey_cmp(end, &buf->start) <= 0 ||
2583 bkey_cmp(start, &buf->end) >= 0)
2586 spin_lock(&buf->lock);
2587 w = RB_GREATER(&buf->keys, s, node, keybuf_nonoverlapping_cmp);
2589 while (w && bkey_cmp(&START_KEY(&w->key), end) < 0) {
2591 w = RB_NEXT(w, node);
2596 __bch_keybuf_del(buf, p);
2599 spin_unlock(&buf->lock);
2603 struct keybuf_key *bch_keybuf_next(struct keybuf *buf)
2605 struct keybuf_key *w;
2607 spin_lock(&buf->lock);
2609 w = RB_FIRST(&buf->keys, struct keybuf_key, node);
2611 while (w && w->private)
2612 w = RB_NEXT(w, node);
2615 w->private = ERR_PTR(-EINTR);
2617 spin_unlock(&buf->lock);
2621 struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
2624 keybuf_pred_fn *pred)
2626 struct keybuf_key *ret;
2629 ret = bch_keybuf_next(buf);
2633 if (bkey_cmp(&buf->last_scanned, end) >= 0) {
2634 pr_debug("scan finished");
2638 bch_refill_keybuf(c, buf, end, pred);
2644 void bch_keybuf_init(struct keybuf *buf)
2646 buf->last_scanned = MAX_KEY;
2647 buf->keys = RB_ROOT;
2649 spin_lock_init(&buf->lock);
2650 array_allocator_init(&buf->freelist);