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-rw-r--r--libbcache/btree_gc.c898
1 files changed, 898 insertions, 0 deletions
diff --git a/libbcache/btree_gc.c b/libbcache/btree_gc.c
new file mode 100644
index 0000000..8417187
--- /dev/null
+++ b/libbcache/btree_gc.c
@@ -0,0 +1,898 @@
+/*
+ * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright (C) 2014 Datera Inc.
+ */
+
+#include "bcache.h"
+#include "alloc.h"
+#include "bkey_methods.h"
+#include "btree_locking.h"
+#include "btree_update.h"
+#include "btree_io.h"
+#include "btree_gc.h"
+#include "buckets.h"
+#include "clock.h"
+#include "debug.h"
+#include "error.h"
+#include "extents.h"
+#include "journal.h"
+#include "keylist.h"
+#include "move.h"
+#include "writeback.h"
+
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/rcupdate.h>
+#include <trace/events/bcache.h>
+
+struct range_checks {
+ struct range_level {
+ struct bpos min;
+ struct bpos max;
+ } l[BTREE_MAX_DEPTH];
+ unsigned depth;
+};
+
+static void btree_node_range_checks_init(struct range_checks *r, unsigned depth)
+{
+ unsigned i;
+
+ for (i = 0; i < BTREE_MAX_DEPTH; i++)
+ r->l[i].min = r->l[i].max = POS_MIN;
+ r->depth = depth;
+}
+
+static void btree_node_range_checks(struct cache_set *c, struct btree *b,
+ struct range_checks *r)
+{
+ struct range_level *l = &r->l[b->level];
+
+ struct bpos expected_min = bkey_cmp(l->min, l->max)
+ ? btree_type_successor(b->btree_id, l->max)
+ : l->max;
+
+ cache_set_inconsistent_on(bkey_cmp(b->data->min_key,
+ expected_min), c,
+ "btree node has incorrect min key: %llu:%llu != %llu:%llu",
+ b->data->min_key.inode,
+ b->data->min_key.offset,
+ expected_min.inode,
+ expected_min.offset);
+
+ l->max = b->data->max_key;
+
+ if (b->level > r->depth) {
+ l = &r->l[b->level - 1];
+
+ cache_set_inconsistent_on(bkey_cmp(b->data->min_key,
+ l->min), c,
+ "btree node min doesn't match min of child nodes: %llu:%llu != %llu:%llu",
+ b->data->min_key.inode,
+ b->data->min_key.offset,
+ l->min.inode,
+ l->min.offset);
+
+ cache_set_inconsistent_on(bkey_cmp(b->data->max_key,
+ l->max), c,
+ "btree node max doesn't match max of child nodes: %llu:%llu != %llu:%llu",
+ b->data->max_key.inode,
+ b->data->max_key.offset,
+ l->max.inode,
+ l->max.offset);
+
+ if (bkey_cmp(b->data->max_key, POS_MAX))
+ l->min = l->max =
+ btree_type_successor(b->btree_id,
+ b->data->max_key);
+ }
+}
+
+u8 bch_btree_key_recalc_oldest_gen(struct cache_set *c, struct bkey_s_c k)
+{
+ const struct bch_extent_ptr *ptr;
+ struct cache *ca;
+ u8 max_stale = 0;
+
+ if (bkey_extent_is_data(k.k)) {
+ struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
+
+ rcu_read_lock();
+
+ extent_for_each_online_device(c, e, ptr, ca) {
+ size_t b = PTR_BUCKET_NR(ca, ptr);
+
+ if (__gen_after(ca->oldest_gens[b], ptr->gen))
+ ca->oldest_gens[b] = ptr->gen;
+
+ max_stale = max(max_stale, ptr_stale(ca, ptr));
+ }
+
+ rcu_read_unlock();
+ }
+
+ return max_stale;
+}
+
+/*
+ * For runtime mark and sweep:
+ */
+u8 __bch_btree_mark_key(struct cache_set *c, enum bkey_type type,
+ struct bkey_s_c k)
+{
+ switch (type) {
+ case BKEY_TYPE_BTREE:
+ bch_gc_mark_key(c, k, c->sb.btree_node_size, true);
+ return 0;
+ case BKEY_TYPE_EXTENTS:
+ bch_gc_mark_key(c, k, k.k->size, false);
+ return bch_btree_key_recalc_oldest_gen(c, k);
+ default:
+ BUG();
+ }
+}
+
+static u8 btree_mark_key(struct cache_set *c, struct btree *b,
+ struct bkey_s_c k)
+{
+ return __bch_btree_mark_key(c, btree_node_type(b), k);
+}
+
+static bool btree_gc_mark_node(struct cache_set *c, struct btree *b)
+{
+ if (btree_node_has_ptrs(b)) {
+ struct btree_node_iter iter;
+ struct bkey unpacked;
+ struct bkey_s_c k;
+ u8 stale = 0;
+
+ for_each_btree_node_key_unpack(b, k, &iter,
+ btree_node_is_extents(b),
+ &unpacked) {
+ bkey_debugcheck(c, b, k);
+ stale = max(stale, btree_mark_key(c, b, k));
+ }
+
+ if (btree_gc_rewrite_disabled(c))
+ return false;
+
+ if (stale > 10)
+ return true;
+ }
+
+ if (btree_gc_always_rewrite(c))
+ return true;
+
+ return false;
+}
+
+static inline void __gc_pos_set(struct cache_set *c, struct gc_pos new_pos)
+{
+ write_seqcount_begin(&c->gc_pos_lock);
+ c->gc_pos = new_pos;
+ write_seqcount_end(&c->gc_pos_lock);
+}
+
+static inline void gc_pos_set(struct cache_set *c, struct gc_pos new_pos)
+{
+ BUG_ON(gc_pos_cmp(new_pos, c->gc_pos) <= 0);
+ __gc_pos_set(c, new_pos);
+}
+
+static int bch_gc_btree(struct cache_set *c, enum btree_id btree_id)
+{
+ struct btree_iter iter;
+ struct btree *b;
+ bool should_rewrite;
+ struct range_checks r;
+ unsigned depth = btree_id == BTREE_ID_EXTENTS ? 0 : 1;
+ int ret;
+
+ /*
+ * if expensive_debug_checks is on, run range_checks on all leaf nodes:
+ */
+ if (expensive_debug_checks(c))
+ depth = 0;
+
+ btree_node_range_checks_init(&r, depth);
+
+ for_each_btree_node(&iter, c, btree_id, POS_MIN, depth, b) {
+ btree_node_range_checks(c, b, &r);
+
+ bch_verify_btree_nr_keys(b);
+
+ should_rewrite = btree_gc_mark_node(c, b);
+
+ gc_pos_set(c, gc_pos_btree_node(b));
+
+ if (should_rewrite)
+ bch_btree_node_rewrite(&iter, b, NULL);
+
+ bch_btree_iter_cond_resched(&iter);
+ }
+ ret = bch_btree_iter_unlock(&iter);
+ if (ret)
+ return ret;
+
+ mutex_lock(&c->btree_root_lock);
+
+ b = c->btree_roots[btree_id].b;
+ __bch_btree_mark_key(c, BKEY_TYPE_BTREE, bkey_i_to_s_c(&b->key));
+ gc_pos_set(c, gc_pos_btree_root(b->btree_id));
+
+ mutex_unlock(&c->btree_root_lock);
+ return 0;
+}
+
+static void bch_mark_allocator_buckets(struct cache_set *c)
+{
+ struct cache *ca;
+ struct open_bucket *ob;
+ size_t i, j, iter;
+ unsigned ci;
+
+ for_each_cache(ca, c, ci) {
+ spin_lock(&ca->freelist_lock);
+
+ fifo_for_each_entry(i, &ca->free_inc, iter)
+ bch_mark_alloc_bucket(ca, &ca->buckets[i], true);
+
+ for (j = 0; j < RESERVE_NR; j++)
+ fifo_for_each_entry(i, &ca->free[j], iter)
+ bch_mark_alloc_bucket(ca, &ca->buckets[i], true);
+
+ spin_unlock(&ca->freelist_lock);
+ }
+
+ for (ob = c->open_buckets;
+ ob < c->open_buckets + ARRAY_SIZE(c->open_buckets);
+ ob++) {
+ const struct bch_extent_ptr *ptr;
+
+ mutex_lock(&ob->lock);
+ rcu_read_lock();
+ open_bucket_for_each_online_device(c, ob, ptr, ca)
+ bch_mark_alloc_bucket(ca, PTR_BUCKET(ca, ptr), true);
+ rcu_read_unlock();
+ mutex_unlock(&ob->lock);
+ }
+}
+
+/*
+ * Mark non btree metadata - prios, journal
+ */
+static void bch_mark_metadata(struct cache_set *c)
+{
+ struct cache *ca;
+ unsigned i;
+
+ for_each_cache(ca, c, i) {
+ unsigned j;
+ u64 *i;
+
+ for (j = 0; j < bch_nr_journal_buckets(ca->disk_sb.sb); j++)
+ bch_mark_metadata_bucket(ca,
+ &ca->buckets[journal_bucket(ca->disk_sb.sb, j)],
+ true);
+
+ spin_lock(&ca->prio_buckets_lock);
+
+ for (i = ca->prio_buckets;
+ i < ca->prio_buckets + prio_buckets(ca) * 2; i++)
+ bch_mark_metadata_bucket(ca, &ca->buckets[*i], true);
+
+ spin_unlock(&ca->prio_buckets_lock);
+ }
+}
+
+/* Also see bch_pending_btree_node_free_insert_done() */
+static void bch_mark_pending_btree_node_frees(struct cache_set *c)
+{
+ struct bucket_stats_cache_set stats = { 0 };
+ struct btree_interior_update *as;
+ struct pending_btree_node_free *d;
+
+ mutex_lock(&c->btree_interior_update_lock);
+ gc_pos_set(c, gc_phase(GC_PHASE_PENDING_DELETE));
+
+ for_each_pending_btree_node_free(c, as, d)
+ if (d->index_update_done)
+ __bch_gc_mark_key(c, bkey_i_to_s_c(&d->key),
+ c->sb.btree_node_size, true,
+ &stats);
+ /*
+ * Don't apply stats - pending deletes aren't tracked in
+ * cache_set_stats:
+ */
+
+ mutex_unlock(&c->btree_interior_update_lock);
+}
+
+/**
+ * bch_gc - recompute bucket marks and oldest_gen, rewrite btree nodes
+ */
+void bch_gc(struct cache_set *c)
+{
+ struct cache *ca;
+ struct bucket *g;
+ struct bucket_mark new;
+ u64 start_time = local_clock();
+ unsigned i;
+ int cpu;
+
+ /*
+ * Walk _all_ references to buckets, and recompute them:
+ *
+ * Order matters here:
+ * - Concurrent GC relies on the fact that we have a total ordering for
+ * everything that GC walks - see gc_will_visit_node(),
+ * gc_will_visit_root()
+ *
+ * - also, references move around in the course of index updates and
+ * various other crap: everything needs to agree on the ordering
+ * references are allowed to move around in - e.g., we're allowed to
+ * start with a reference owned by an open_bucket (the allocator) and
+ * move it to the btree, but not the reverse.
+ *
+ * This is necessary to ensure that gc doesn't miss references that
+ * move around - if references move backwards in the ordering GC
+ * uses, GC could skip past them
+ */
+
+ if (test_bit(CACHE_SET_GC_FAILURE, &c->flags))
+ return;
+
+ trace_bcache_gc_start(c);
+
+ /*
+ * Do this before taking gc_lock - bch_disk_reservation_get() blocks on
+ * gc_lock if sectors_available goes to 0:
+ */
+ bch_recalc_sectors_available(c);
+
+ down_write(&c->gc_lock);
+
+ lg_global_lock(&c->bucket_stats_lock);
+
+ /*
+ * Indicates to buckets code that gc is now in progress - done under
+ * bucket_stats_lock to avoid racing with bch_mark_key():
+ */
+ __gc_pos_set(c, GC_POS_MIN);
+
+ /* Save a copy of the existing bucket stats while we recompute them: */
+ for_each_cache(ca, c, i) {
+ ca->bucket_stats_cached = __bch_bucket_stats_read_cache(ca);
+ for_each_possible_cpu(cpu) {
+ struct bucket_stats_cache *p =
+ per_cpu_ptr(ca->bucket_stats_percpu, cpu);
+ memset(p, 0, sizeof(*p));
+ }
+ }
+
+ c->bucket_stats_cached = __bch_bucket_stats_read_cache_set(c);
+ for_each_possible_cpu(cpu) {
+ struct bucket_stats_cache_set *p =
+ per_cpu_ptr(c->bucket_stats_percpu, cpu);
+
+ memset(p->s, 0, sizeof(p->s));
+ p->persistent_reserved = 0;
+ }
+
+ lg_global_unlock(&c->bucket_stats_lock);
+
+ /* Clear bucket marks: */
+ for_each_cache(ca, c, i)
+ for_each_bucket(g, ca) {
+ bucket_cmpxchg(g, new, ({
+ new.owned_by_allocator = 0;
+ new.is_metadata = 0;
+ new.cached_sectors = 0;
+ new.dirty_sectors = 0;
+ }));
+ ca->oldest_gens[g - ca->buckets] = new.gen;
+ }
+
+ /* Walk allocator's references: */
+ bch_mark_allocator_buckets(c);
+
+ /* Walk btree: */
+ while (c->gc_pos.phase < (int) BTREE_ID_NR) {
+ int ret = c->btree_roots[c->gc_pos.phase].b
+ ? bch_gc_btree(c, (int) c->gc_pos.phase)
+ : 0;
+
+ if (ret) {
+ bch_err(c, "btree gc failed: %d", ret);
+ set_bit(CACHE_SET_GC_FAILURE, &c->flags);
+ up_write(&c->gc_lock);
+ return;
+ }
+
+ gc_pos_set(c, gc_phase(c->gc_pos.phase + 1));
+ }
+
+ bch_mark_metadata(c);
+ bch_mark_pending_btree_node_frees(c);
+ bch_writeback_recalc_oldest_gens(c);
+
+ for_each_cache(ca, c, i)
+ atomic_long_set(&ca->saturated_count, 0);
+
+ /* Indicates that gc is no longer in progress: */
+ gc_pos_set(c, gc_phase(GC_PHASE_DONE));
+
+ up_write(&c->gc_lock);
+ trace_bcache_gc_end(c);
+ bch_time_stats_update(&c->btree_gc_time, start_time);
+
+ /*
+ * Wake up allocator in case it was waiting for buckets
+ * because of not being able to inc gens
+ */
+ for_each_cache(ca, c, i)
+ bch_wake_allocator(ca);
+}
+
+/* Btree coalescing */
+
+static void recalc_packed_keys(struct btree *b)
+{
+ struct bkey_packed *k;
+
+ memset(&b->nr, 0, sizeof(b->nr));
+
+ BUG_ON(b->nsets != 1);
+
+ for (k = btree_bkey_first(b, b->set);
+ k != btree_bkey_last(b, b->set);
+ k = bkey_next(k))
+ btree_keys_account_key_add(&b->nr, 0, k);
+}
+
+static void bch_coalesce_nodes(struct btree *old_nodes[GC_MERGE_NODES],
+ struct btree_iter *iter)
+{
+ struct btree *parent = iter->nodes[old_nodes[0]->level + 1];
+ struct cache_set *c = iter->c;
+ unsigned i, nr_old_nodes, nr_new_nodes, u64s = 0;
+ unsigned blocks = btree_blocks(c) * 2 / 3;
+ struct btree *new_nodes[GC_MERGE_NODES];
+ struct btree_interior_update *as;
+ struct btree_reserve *res;
+ struct keylist keylist;
+ struct bkey_format_state format_state;
+ struct bkey_format new_format;
+
+ memset(new_nodes, 0, sizeof(new_nodes));
+ bch_keylist_init(&keylist, NULL, 0);
+
+ /* Count keys that are not deleted */
+ for (i = 0; i < GC_MERGE_NODES && old_nodes[i]; i++)
+ u64s += old_nodes[i]->nr.live_u64s;
+
+ nr_old_nodes = nr_new_nodes = i;
+
+ /* Check if all keys in @old_nodes could fit in one fewer node */
+ if (nr_old_nodes <= 1 ||
+ __set_blocks(old_nodes[0]->data,
+ DIV_ROUND_UP(u64s, nr_old_nodes - 1),
+ block_bytes(c)) > blocks)
+ return;
+
+ res = bch_btree_reserve_get(c, parent, nr_old_nodes,
+ BTREE_INSERT_NOFAIL|
+ BTREE_INSERT_USE_RESERVE,
+ NULL);
+ if (IS_ERR(res)) {
+ trace_bcache_btree_gc_coalesce_fail(c,
+ BTREE_GC_COALESCE_FAIL_RESERVE_GET);
+ return;
+ }
+
+ if (bch_keylist_realloc(&keylist, NULL, 0,
+ (BKEY_U64s + BKEY_EXTENT_U64s_MAX) * nr_old_nodes)) {
+ trace_bcache_btree_gc_coalesce_fail(c,
+ BTREE_GC_COALESCE_FAIL_KEYLIST_REALLOC);
+ goto out;
+ }
+
+ /* Find a format that all keys in @old_nodes can pack into */
+ bch_bkey_format_init(&format_state);
+
+ for (i = 0; i < nr_old_nodes; i++)
+ __bch_btree_calc_format(&format_state, old_nodes[i]);
+
+ new_format = bch_bkey_format_done(&format_state);
+
+ /* Check if repacking would make any nodes too big to fit */
+ for (i = 0; i < nr_old_nodes; i++)
+ if (!bch_btree_node_format_fits(c, old_nodes[i], &new_format)) {
+ trace_bcache_btree_gc_coalesce_fail(c,
+ BTREE_GC_COALESCE_FAIL_FORMAT_FITS);
+ goto out;
+ }
+
+ trace_bcache_btree_gc_coalesce(c, parent, nr_old_nodes);
+
+ as = bch_btree_interior_update_alloc(c);
+
+ for (i = 0; i < nr_old_nodes; i++)
+ bch_btree_interior_update_will_free_node(c, as, old_nodes[i]);
+
+ /* Repack everything with @new_format and sort down to one bset */
+ for (i = 0; i < nr_old_nodes; i++)
+ new_nodes[i] = __btree_node_alloc_replacement(c, old_nodes[i],
+ new_format, res);
+
+ /*
+ * Conceptually we concatenate the nodes together and slice them
+ * up at different boundaries.
+ */
+ for (i = nr_new_nodes - 1; i > 0; --i) {
+ struct btree *n1 = new_nodes[i];
+ struct btree *n2 = new_nodes[i - 1];
+
+ struct bset *s1 = btree_bset_first(n1);
+ struct bset *s2 = btree_bset_first(n2);
+ struct bkey_packed *k, *last = NULL;
+
+ /* Calculate how many keys from @n2 we could fit inside @n1 */
+ u64s = 0;
+
+ for (k = s2->start;
+ k < bset_bkey_last(s2) &&
+ __set_blocks(n1->data, le16_to_cpu(s1->u64s) + u64s + k->u64s,
+ block_bytes(c)) <= blocks;
+ k = bkey_next(k)) {
+ last = k;
+ u64s += k->u64s;
+ }
+
+ if (u64s == le16_to_cpu(s2->u64s)) {
+ /* n2 fits entirely in n1 */
+ n1->key.k.p = n1->data->max_key = n2->data->max_key;
+
+ memcpy_u64s(bset_bkey_last(s1),
+ s2->start,
+ le16_to_cpu(s2->u64s));
+ le16_add_cpu(&s1->u64s, le16_to_cpu(s2->u64s));
+
+ set_btree_bset_end(n1, n1->set);
+
+ six_unlock_write(&n2->lock);
+ bch_btree_node_free_never_inserted(c, n2);
+ six_unlock_intent(&n2->lock);
+
+ memmove(new_nodes + i - 1,
+ new_nodes + i,
+ sizeof(new_nodes[0]) * (nr_new_nodes - i));
+ new_nodes[--nr_new_nodes] = NULL;
+ } else if (u64s) {
+ /* move part of n2 into n1 */
+ n1->key.k.p = n1->data->max_key =
+ bkey_unpack_pos(n1, last);
+
+ n2->data->min_key =
+ btree_type_successor(iter->btree_id,
+ n1->data->max_key);
+
+ memcpy_u64s(bset_bkey_last(s1),
+ s2->start, u64s);
+ le16_add_cpu(&s1->u64s, u64s);
+
+ memmove(s2->start,
+ bset_bkey_idx(s2, u64s),
+ (le16_to_cpu(s2->u64s) - u64s) * sizeof(u64));
+ s2->u64s = cpu_to_le16(le16_to_cpu(s2->u64s) - u64s);
+
+ set_btree_bset_end(n1, n1->set);
+ set_btree_bset_end(n2, n2->set);
+ }
+ }
+
+ for (i = 0; i < nr_new_nodes; i++) {
+ struct btree *n = new_nodes[i];
+
+ recalc_packed_keys(n);
+ btree_node_reset_sib_u64s(n);
+
+ bch_btree_build_aux_trees(n);
+ six_unlock_write(&n->lock);
+
+ bch_btree_node_write(c, n, &as->cl, SIX_LOCK_intent, -1);
+ }
+
+ /*
+ * The keys for the old nodes get deleted. We don't want to insert keys
+ * that compare equal to the keys for the new nodes we'll also be
+ * inserting - we can't because keys on a keylist must be strictly
+ * greater than the previous keys, and we also don't need to since the
+ * key for the new node will serve the same purpose (overwriting the key
+ * for the old node).
+ */
+ for (i = 0; i < nr_old_nodes; i++) {
+ struct bkey_i delete;
+ unsigned j;
+
+ for (j = 0; j < nr_new_nodes; j++)
+ if (!bkey_cmp(old_nodes[i]->key.k.p,
+ new_nodes[j]->key.k.p))
+ goto next;
+
+ bkey_init(&delete.k);
+ delete.k.p = old_nodes[i]->key.k.p;
+ bch_keylist_add_in_order(&keylist, &delete);
+next:
+ i = i;
+ }
+
+ /*
+ * Keys for the new nodes get inserted: bch_btree_insert_keys() only
+ * does the lookup once and thus expects the keys to be in sorted order
+ * so we have to make sure the new keys are correctly ordered with
+ * respect to the deleted keys added in the previous loop
+ */
+ for (i = 0; i < nr_new_nodes; i++)
+ bch_keylist_add_in_order(&keylist, &new_nodes[i]->key);
+
+ /* Insert the newly coalesced nodes */
+ bch_btree_insert_node(parent, iter, &keylist, res, as);
+
+ BUG_ON(!bch_keylist_empty(&keylist));
+
+ BUG_ON(iter->nodes[old_nodes[0]->level] != old_nodes[0]);
+
+ BUG_ON(!bch_btree_iter_node_replace(iter, new_nodes[0]));
+
+ for (i = 0; i < nr_new_nodes; i++)
+ btree_open_bucket_put(c, new_nodes[i]);
+
+ /* Free the old nodes and update our sliding window */
+ for (i = 0; i < nr_old_nodes; i++) {
+ bch_btree_node_free_inmem(iter, old_nodes[i]);
+ six_unlock_intent(&old_nodes[i]->lock);
+
+ /*
+ * the index update might have triggered a split, in which case
+ * the nodes we coalesced - the new nodes we just created -
+ * might not be sibling nodes anymore - don't add them to the
+ * sliding window (except the first):
+ */
+ if (!i) {
+ old_nodes[i] = new_nodes[i];
+ } else {
+ old_nodes[i] = NULL;
+ if (new_nodes[i])
+ six_unlock_intent(&new_nodes[i]->lock);
+ }
+ }
+out:
+ bch_keylist_free(&keylist, NULL);
+ bch_btree_reserve_put(c, res);
+}
+
+static int bch_coalesce_btree(struct cache_set *c, enum btree_id btree_id)
+{
+ struct btree_iter iter;
+ struct btree *b;
+ unsigned i;
+
+ /* Sliding window of adjacent btree nodes */
+ struct btree *merge[GC_MERGE_NODES];
+ u32 lock_seq[GC_MERGE_NODES];
+
+ /*
+ * XXX: We don't have a good way of positively matching on sibling nodes
+ * that have the same parent - this code works by handling the cases
+ * where they might not have the same parent, and is thus fragile. Ugh.
+ *
+ * Perhaps redo this to use multiple linked iterators?
+ */
+ memset(merge, 0, sizeof(merge));
+
+ __for_each_btree_node(&iter, c, btree_id, POS_MIN, 0, b, U8_MAX) {
+ memmove(merge + 1, merge,
+ sizeof(merge) - sizeof(merge[0]));
+ memmove(lock_seq + 1, lock_seq,
+ sizeof(lock_seq) - sizeof(lock_seq[0]));
+
+ merge[0] = b;
+
+ for (i = 1; i < GC_MERGE_NODES; i++) {
+ if (!merge[i] ||
+ !six_relock_intent(&merge[i]->lock, lock_seq[i]))
+ break;
+
+ if (merge[i]->level != merge[0]->level) {
+ six_unlock_intent(&merge[i]->lock);
+ break;
+ }
+ }
+ memset(merge + i, 0, (GC_MERGE_NODES - i) * sizeof(merge[0]));
+
+ bch_coalesce_nodes(merge, &iter);
+
+ for (i = 1; i < GC_MERGE_NODES && merge[i]; i++) {
+ lock_seq[i] = merge[i]->lock.state.seq;
+ six_unlock_intent(&merge[i]->lock);
+ }
+
+ lock_seq[0] = merge[0]->lock.state.seq;
+
+ if (test_bit(CACHE_SET_GC_STOPPING, &c->flags)) {
+ bch_btree_iter_unlock(&iter);
+ return -ESHUTDOWN;
+ }
+
+ bch_btree_iter_cond_resched(&iter);
+
+ /*
+ * If the parent node wasn't relocked, it might have been split
+ * and the nodes in our sliding window might not have the same
+ * parent anymore - blow away the sliding window:
+ */
+ if (iter.nodes[iter.level + 1] &&
+ !btree_node_intent_locked(&iter, iter.level + 1))
+ memset(merge + 1, 0,
+ (GC_MERGE_NODES - 1) * sizeof(merge[0]));
+ }
+ return bch_btree_iter_unlock(&iter);
+}
+
+/**
+ * bch_coalesce - coalesce adjacent nodes with low occupancy
+ */
+void bch_coalesce(struct cache_set *c)
+{
+ u64 start_time;
+ enum btree_id id;
+
+ if (btree_gc_coalesce_disabled(c))
+ return;
+
+ if (test_bit(CACHE_SET_GC_FAILURE, &c->flags))
+ return;
+
+ down_read(&c->gc_lock);
+ trace_bcache_gc_coalesce_start(c);
+ start_time = local_clock();
+
+ for (id = 0; id < BTREE_ID_NR; id++) {
+ int ret = c->btree_roots[id].b
+ ? bch_coalesce_btree(c, id)
+ : 0;
+
+ if (ret) {
+ if (ret != -ESHUTDOWN)
+ bch_err(c, "btree coalescing failed: %d", ret);
+ set_bit(CACHE_SET_GC_FAILURE, &c->flags);
+ return;
+ }
+ }
+
+ bch_time_stats_update(&c->btree_coalesce_time, start_time);
+ trace_bcache_gc_coalesce_end(c);
+ up_read(&c->gc_lock);
+}
+
+static int bch_gc_thread(void *arg)
+{
+ struct cache_set *c = arg;
+ struct io_clock *clock = &c->io_clock[WRITE];
+ unsigned long last = atomic_long_read(&clock->now);
+ unsigned last_kick = atomic_read(&c->kick_gc);
+
+ set_freezable();
+
+ while (1) {
+ unsigned long next = last + c->capacity / 16;
+
+ while (atomic_long_read(&clock->now) < next) {
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ if (kthread_should_stop()) {
+ __set_current_state(TASK_RUNNING);
+ return 0;
+ }
+
+ if (atomic_read(&c->kick_gc) != last_kick) {
+ __set_current_state(TASK_RUNNING);
+ break;
+ }
+
+ bch_io_clock_schedule_timeout(clock, next);
+ try_to_freeze();
+ }
+
+ last = atomic_long_read(&clock->now);
+ last_kick = atomic_read(&c->kick_gc);
+
+ bch_gc(c);
+ bch_coalesce(c);
+
+ debug_check_no_locks_held();
+ }
+
+ return 0;
+}
+
+void bch_gc_thread_stop(struct cache_set *c)
+{
+ set_bit(CACHE_SET_GC_STOPPING, &c->flags);
+
+ if (!IS_ERR_OR_NULL(c->gc_thread))
+ kthread_stop(c->gc_thread);
+}
+
+int bch_gc_thread_start(struct cache_set *c)
+{
+ clear_bit(CACHE_SET_GC_STOPPING, &c->flags);
+
+ c->gc_thread = kthread_create(bch_gc_thread, c, "bcache_gc");
+ if (IS_ERR(c->gc_thread))
+ return PTR_ERR(c->gc_thread);
+
+ wake_up_process(c->gc_thread);
+ return 0;
+}
+
+/* Initial GC computes bucket marks during startup */
+
+static void bch_initial_gc_btree(struct cache_set *c, enum btree_id id)
+{
+ struct btree_iter iter;
+ struct btree *b;
+ struct range_checks r;
+
+ btree_node_range_checks_init(&r, 0);
+
+ if (!c->btree_roots[id].b)
+ return;
+
+ /*
+ * We have to hit every btree node before starting journal replay, in
+ * order for the journal seq blacklist machinery to work:
+ */
+ for_each_btree_node(&iter, c, id, POS_MIN, 0, b) {
+ btree_node_range_checks(c, b, &r);
+
+ if (btree_node_has_ptrs(b)) {
+ struct btree_node_iter node_iter;
+ struct bkey unpacked;
+ struct bkey_s_c k;
+
+ for_each_btree_node_key_unpack(b, k, &node_iter,
+ btree_node_is_extents(b),
+ &unpacked)
+ btree_mark_key(c, b, k);
+ }
+
+ bch_btree_iter_cond_resched(&iter);
+ }
+
+ bch_btree_iter_unlock(&iter);
+
+ __bch_btree_mark_key(c, BKEY_TYPE_BTREE,
+ bkey_i_to_s_c(&c->btree_roots[id].b->key));
+}
+
+int bch_initial_gc(struct cache_set *c, struct list_head *journal)
+{
+ enum btree_id id;
+
+ if (journal) {
+ for (id = 0; id < BTREE_ID_NR; id++)
+ bch_initial_gc_btree(c, id);
+
+ bch_journal_mark(c, journal);
+ }
+
+ bch_mark_metadata(c);
+
+ gc_pos_set(c, gc_phase(GC_PHASE_DONE));
+ set_bit(CACHE_SET_INITIAL_GC_DONE, &c->flags);
+
+ return 0;
+}
generated by cgit v1.2.3 (git 2.46.0) at 2025-07-01 04:09:50 +0000