Merge pull request ceph#56246 from xxhdx1985126/wip-64957

crimson/os/seastore/btree: check for reserved ptrs when determining children stability

Reviewed-by: Yingxin Cheng <[email protected]>
Reviewed-by: Chunmei Liu <[email protected]>

Author: cyx1231st

src/crimson/os/seastore/btree/btree_range_pin.cc

@@ -29,7 +29,7 @@ bool BtreeNodeMapping<key_t, val_t>::is_stable() const
   assert(parent->is_valid());
   assert(pos != std::numeric_limits<uint16_t>::max());
   auto &p = (FixedKVNode<key_t>&)*parent;
-  return p.is_child_stable(pos);
+  return p.is_child_stable(ctx, pos);
 }
 
 template class BtreeNodeMapping<laddr_t, paddr_t>;

src/crimson/os/seastore/btree/fixed_kv_btree.h

@@ -15,8 +15,6 @@
 #include "crimson/os/seastore/btree/btree_range_pin.h"
 #include "crimson/os/seastore/root_block.h"
 
-#define RESERVATION_PTR reinterpret_cast<ChildableCachedExtent*>(0x1)
-
 namespace crimson::os::seastore::lba_manager::btree {
 struct lba_map_val_t;
 }
@@ -25,6 +23,12 @@ namespace crimson::os::seastore {
 
 bool is_valid_child_ptr(ChildableCachedExtent* child);
 
+bool is_reserved_ptr(ChildableCachedExtent* child);
+
+inline ChildableCachedExtent* get_reserved_ptr() {
+  return (ChildableCachedExtent*)0x1;
+}
+
 template <typename T>
 phy_tree_root_t& get_phy_tree_root(root_t& r);
 

src/crimson/os/seastore/btree/fixed_kv_node.cc

@@ -6,7 +6,11 @@
 namespace crimson::os::seastore {
 
 bool is_valid_child_ptr(ChildableCachedExtent* child) {
-  return child != nullptr && child != RESERVATION_PTR;
+  return child != nullptr && child != get_reserved_ptr();
+}
+
+bool is_reserved_ptr(ChildableCachedExtent* child) {
+  return child == get_reserved_ptr();
 }
 
 } // namespace crimson::os::seastore

src/crimson/os/seastore/btree/fixed_kv_node.h

@@ -134,7 +134,7 @@ struct FixedKVNode : ChildableCachedExtent {
       // copy sources when committing this lba node, because
       // we rely on pointers' "nullness" to avoid copying
       // pointers for updated values
-      children[offset] = RESERVATION_PTR;
+      children[offset] = get_reserved_ptr();
     }
   }
 
@@ -229,13 +229,14 @@ struct FixedKVNode : ChildableCachedExtent {
   virtual get_child_ret_t<LogicalCachedExtent>
   get_logical_child(op_context_t<node_key_t> c, uint16_t pos) = 0;
 
-  virtual bool is_child_stable(uint16_t pos) const = 0;
+  virtual bool is_child_stable(op_context_t<node_key_t>, uint16_t pos) const = 0;
 
   template <typename T, typename iter_t>
   get_child_ret_t<T> get_child(op_context_t<node_key_t> c, iter_t iter) {
     auto pos = iter.get_offset();
     assert(children.capacity());
     auto child = children[pos];
+    ceph_assert(!is_reserved_ptr(child));
     if (is_valid_child_ptr(child)) {
       ceph_assert(child->get_type() == T::TYPE);
       return c.cache.template get_extent_viewable_by_trans<T>(c.trans, (T*)child);
@@ -431,7 +432,7 @@ struct FixedKVNode : ChildableCachedExtent {
 	if (!child) {
 	  child = source.children[foreign_it.get_offset()];
 	  // child can be either valid if present, nullptr if absent,
-	  // or RESERVATION_PTR.
+	  // or reserved ptr.
 	}
 	foreign_it++;
 	local_it++;
@@ -596,7 +597,7 @@ struct FixedKVInternalNode
     return get_child_ret_t<LogicalCachedExtent>(child_pos_t(nullptr, 0));
   }
 
-  bool is_child_stable(uint16_t pos) const final {
+  bool is_child_stable(op_context_t<NODE_KEY>, uint16_t pos) const final {
     ceph_abort("impossible");
     return false;
   }
@@ -972,6 +973,7 @@ struct FixedKVLeafNode
   get_child_ret_t<LogicalCachedExtent>
   get_logical_child(op_context_t<NODE_KEY> c, uint16_t pos) final {
     auto child = this->children[pos];
+    ceph_assert(!is_reserved_ptr(child));
     if (is_valid_child_ptr(child)) {
       ceph_assert(child->is_logical());
       return c.cache.template get_extent_viewable_by_trans<
@@ -996,19 +998,26 @@ struct FixedKVLeafNode
   // children are considered stable if any of the following case is true:
   // 1. The child extent is absent in cache
   // 2. The child extent is stable
-  bool is_child_stable(uint16_t pos) const final {
+  //
+  // For reserved mappings, the return values are undefined.
+  bool is_child_stable(op_context_t<NODE_KEY> c, uint16_t pos) const final {
     auto child = this->children[pos];
-    if (is_valid_child_ptr(child)) {
+    if (is_reserved_ptr(child)) {
+      return true;
+    } else if (is_valid_child_ptr(child)) {
       ceph_assert(child->is_logical());
-      return child->is_stable();
+      ceph_assert(
+	child->is_pending_in_trans(c.trans.get_trans_id())
+	|| this->is_stable_written());
+      return c.cache.is_viewable_extent_stable(c.trans, child);
     } else if (this->is_pending()) {
       auto key = this->iter_idx(pos).get_key();
       auto &sparent = this->get_stable_for_key(key);
       auto spos = sparent.child_pos_for_key(key);
       auto child = sparent.children[spos];
       if (is_valid_child_ptr(child)) {
 	ceph_assert(child->is_logical());
-	return child->is_stable();
+	return c.cache.is_viewable_extent_stable(c.trans, child);
       } else {
 	return true;
       }

src/crimson/os/seastore/cache.h

@@ -443,6 +443,15 @@ class Cache {
     return get_absent_extent<T>(t, offset, length, [](T &){});
   }
 
+  bool is_viewable_extent_stable(
+    Transaction &t,
+    CachedExtentRef extent)
+  {
+    assert(extent);
+    auto view = extent->get_transactional_view(t);
+    return view->is_stable();
+  }
+
   using get_extent_ertr = base_ertr;
   get_extent_ertr::future<CachedExtentRef>
   get_extent_viewable_by_trans(

src/crimson/os/seastore/cached_extent.h

@@ -426,6 +426,9 @@ class CachedExtent
   /// Returns true if extent is stable and shared among transactions
   bool is_stable() const {
     return is_stable_written() ||
+	   // MUTATION_PENDING and under-io extents are to-be-stable extents,
+	   // for the sake of caveats that checks the correctness of extents
+	   // states, we consider them stable.
            (is_mutation_pending() &&
             is_pending_io());
   }
@@ -615,6 +618,11 @@ class CachedExtent
     return last_committed_crc;
   }
 
+  /// Returns true if the extent part of the open transaction
+  bool is_pending_in_trans(transaction_id_t id) const {
+    return is_pending() && pending_for_transaction == id;
+  }
+
 private:
   template <typename T>
   friend class read_set_item_t;
@@ -645,11 +653,6 @@ class CachedExtent
     ptr = nptr;
   }
 
-  /// Returns true if the extent part of the open transaction
-  bool is_pending_in_trans(transaction_id_t id) const {
-    return is_pending() && pending_for_transaction == id;
-  }
-
   /// hook for intrusive ref list (mainly dirty or lru list)
   boost::intrusive::list_member_hook<> primary_ref_list_hook;
   using primary_ref_list_member_options = boost::intrusive::member_hook<
@@ -1062,6 +1065,8 @@ class PhysicalNodeMapping {
     child_pos->link_child(c);
   }
 
+  // For reserved mappings, the return values are
+  // undefined although it won't crash
   virtual bool is_stable() const = 0;
   virtual bool is_clone() const = 0;
   bool is_zero_reserved() const {