+/*
+ * New much simpler mechanism for clearing out unneeded replicas entries - drop
+ * replicas entries that have 0 sectors used.
+ *
+ * However, we don't track sector counts for journal usage, so this doesn't drop
+ * any BCH_DATA_journal entries; the old bch2_replicas_gc_(start|end) mechanism
+ * is retained for that.
+ */
+int bch2_replicas_gc2(struct bch_fs *c)
+{
+ struct bch_replicas_cpu new = { 0 };
+ unsigned i, nr;
+ int ret = 0;
+
+ bch2_journal_meta(&c->journal);
+retry:
+ nr = READ_ONCE(c->replicas.nr);
+ new.entry_size = READ_ONCE(c->replicas.entry_size);
+ new.entries = kcalloc(nr, new.entry_size, GFP_KERNEL);
+ if (!new.entries) {
+ bch_err(c, "error allocating c->replicas_gc");
+ return -BCH_ERR_ENOMEM_replicas_gc;
+ }
+
+ mutex_lock(&c->sb_lock);
+ percpu_down_write(&c->mark_lock);
+
+ if (nr != c->replicas.nr ||
+ new.entry_size != c->replicas.entry_size) {
+ percpu_up_write(&c->mark_lock);
+ mutex_unlock(&c->sb_lock);
+ kfree(new.entries);
+ goto retry;
+ }
+
+ for (i = 0; i < c->replicas.nr; i++) {
+ struct bch_replicas_entry_v1 *e =
+ cpu_replicas_entry(&c->replicas, i);
+
+ if (e->data_type == BCH_DATA_journal ||
+ c->usage_base->replicas[i] ||
+ percpu_u64_get(&c->usage[0]->replicas[i]) ||
+ percpu_u64_get(&c->usage[1]->replicas[i]) ||
+ percpu_u64_get(&c->usage[2]->replicas[i]) ||
+ percpu_u64_get(&c->usage[3]->replicas[i]))
+ memcpy(cpu_replicas_entry(&new, new.nr++),
+ e, new.entry_size);
+ }
+
+ bch2_cpu_replicas_sort(&new);
+
+ ret = bch2_cpu_replicas_to_sb_replicas(c, &new) ?:
+ replicas_table_update(c, &new);
+
+ kfree(new.entries);
+
+ percpu_up_write(&c->mark_lock);
+
+ if (!ret)
+ bch2_write_super(c);
+
+ mutex_unlock(&c->sb_lock);
+
+ return ret;
+}
+