1 files changed, 153 insertions, 0 deletions
diff --git a/src/crimson/os/seastore/lba_manager/btree/btree_range_pin.cc b/src/crimson/os/seastore/lba_manager/btree/btree_range_pin.cc
new file mode 100644
index 000000000..a86c3cc57
--- /dev/null
+++ b/src/crimson/os/seastore/lba_manager/btree/btree_range_pin.cc
@@ -0,0 +1,153 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "crimson/common/log.h"
+
+#include "crimson/os/seastore/lba_manager/btree/btree_range_pin.h"
+
+namespace {
+  seastar::logger& logger() {
+    return crimson::get_logger(ceph_subsys_filestore);
+  }
+}
+
+namespace crimson::os::seastore::lba_manager::btree {
+
+void btree_range_pin_t::take_pin(btree_range_pin_t &other)
+{
+  assert(other.extent);
+  assert(other.pins);
+  other.pins->replace_pin(*this, other);
+  pins = other.pins;
+  other.pins = nullptr;
+
+  if (other.has_ref()) {
+    other.drop_ref();
+    acquire_ref();
+  }
+}
+
+btree_range_pin_t::~btree_range_pin_t()
+{
+  assert(!pins == !is_linked());
+  assert(!ref);
+  if (pins) {
+    logger().debug("{}: removing {}", __func__, *this);
+    pins->remove_pin(*this, true);
+  }
+  extent = nullptr;
+}
+
+void btree_pin_set_t::replace_pin(btree_range_pin_t &to, btree_range_pin_t &from)
+{
+  pins.replace_node(pins.iterator_to(from), to);
+}
+
+void btree_pin_set_t::remove_pin(btree_range_pin_t &pin, bool do_check_parent)
+{
+  logger().debug("{}: {}", __func__, pin);
+  assert(pin.is_linked());
+  assert(pin.pins);
+  assert(!pin.ref);
+
+  pins.erase(pin);
+  pin.pins = nullptr;
+
+  if (do_check_parent) {
+    check_parent(pin);
+  }
+}
+
+btree_range_pin_t *btree_pin_set_t::maybe_get_parent(
+  const lba_node_meta_t &meta)
+{
+  auto cmeta = meta;
+  cmeta.depth++;
+  auto iter = pins.upper_bound(cmeta, btree_range_pin_t::meta_cmp_t());
+  if (iter == pins.begin()) {
+    return nullptr;
+  } else {
+    --iter;
+    if (iter->range.is_parent_of(meta)) {
+      return &*iter;
+    } else {
+      return nullptr;
+    }
+  }
+}
+
+const btree_range_pin_t *btree_pin_set_t::maybe_get_first_child(
+  const lba_node_meta_t &meta) const
+{
+  if (meta.depth == 0) {
+    return nullptr;
+  }
+
+  auto cmeta = meta;
+  cmeta.depth--;
+
+  auto iter = pins.lower_bound(cmeta, btree_range_pin_t::meta_cmp_t());
+  if (iter == pins.end()) {
+    return nullptr;
+  } else if (meta.is_parent_of(iter->range)) {
+    return &*iter;
+  } else {
+    return nullptr;
+  }
+}
+
+void btree_pin_set_t::release_if_no_children(btree_range_pin_t &pin)
+{
+  assert(pin.is_linked());
+  if (maybe_get_first_child(pin.range) == nullptr) {
+    pin.drop_ref();
+  }
+}
+
+void btree_pin_set_t::add_pin(btree_range_pin_t &pin)
+{
+  assert(!pin.is_linked());
+  assert(!pin.pins);
+  assert(!pin.ref);
+
+  auto [prev, inserted] = pins.insert(pin);
+  if (!inserted) {
+    logger().error("{}: unable to add {}, found {}", __func__, pin, *prev);
+    assert(0 == "impossible");
+    return;
+  }
+  pin.pins = this;
+  if (!pin.is_root()) {
+    auto *parent = maybe_get_parent(pin.range);
+    assert(parent);
+    if (!parent->has_ref()) {
+      logger().debug("{}: acquiring parent {}", __func__,
+		     static_cast<void*>(parent));
+      parent->acquire_ref();
+    } else {
+      logger().debug("{}: parent has ref {}", __func__,
+		     static_cast<void*>(parent));
+    }
+  }
+  if (maybe_get_first_child(pin.range) != nullptr) {
+    logger().debug("{}: acquiring self {}", __func__, pin);
+    pin.acquire_ref();
+  }
+}
+
+void btree_pin_set_t::retire(btree_range_pin_t &pin)
+{
+  pin.drop_ref();
+  remove_pin(pin, false);
+}
+
+void btree_pin_set_t::check_parent(btree_range_pin_t &pin)
+{
+  auto parent = maybe_get_parent(pin.range);
+  if (parent) {
+    logger().debug("{}: releasing parent {}", __func__, *parent);
+    release_if_no_children(*parent);
+  }
+}
+
+}