Merge pull request ceph#57262 from xxhdx1985126/wip-seastore-clone-remap-refcount

crimson/os/seastore/lba_manager: don't increase intermediate mappings' refcount if LBAManager::clone_mapping() is called to remap mappings

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

Author: cyx1231st

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

@@ -1516,6 +1516,8 @@ class FixedKVBtree {
     };
 
     auto v = parent->template get_child<internal_node_t>(c, node_iter);
+    // checking the lba child must be atomic with creating
+    // and linking the absent child
     if (v.has_child()) {
       return v.get_child_fut().safe_then(
         [on_found=std::move(on_found), node_iter, c,
@@ -1584,6 +1586,8 @@ class FixedKVBtree {
     };
 
     auto v = parent->template get_child<leaf_node_t>(c, node_iter);
+    // checking the lba child must be atomic with creating
+    // and linking the absent child
     if (v.has_child()) {
       return v.get_child_fut().safe_then(
         [on_found=std::move(on_found), node_iter, c,
@@ -2137,6 +2141,8 @@ class FixedKVBtree {
     };
 
     auto v = parent_pos.node->template get_child<NodeType>(c, donor_iter);
+    // checking the lba child must be atomic with creating
+    // and linking the absent child
     if (v.has_child()) {
       return v.get_child_fut().safe_then(
         [do_merge=std::move(do_merge), &pos,

src/crimson/os/seastore/cache.cc

@@ -58,6 +58,7 @@ Cache::~Cache()
   ceph_assert(extents.empty());
 }
 
+// TODO: this method can probably be removed in the future
 Cache::retire_extent_ret Cache::retire_extent_addr(
   Transaction &t, paddr_t addr, extent_len_t length)
 {
@@ -104,6 +105,33 @@ Cache::retire_extent_ret Cache::retire_extent_addr(
   return retire_extent_iertr::now();
 }
 
+void Cache::retire_absent_extent_addr(
+  Transaction &t, paddr_t addr, extent_len_t length)
+{
+#ifndef NDEBUG
+  CachedExtentRef ext;
+  auto result = t.get_extent(addr, &ext);
+  assert(result != Transaction::get_extent_ret::PRESENT
+    && result != Transaction::get_extent_ret::RETIRED);
+  assert(!query_cache(addr, nullptr));
+#endif
+  LOG_PREFIX(Cache::retire_absent_extent_addr);
+  // add a new placeholder to Cache
+  ext = CachedExtent::make_cached_extent_ref<
+    RetiredExtentPlaceholder>(length);
+  ext->init(CachedExtent::extent_state_t::CLEAN,
+	    addr,
+	    PLACEMENT_HINT_NULL,
+	    NULL_GENERATION,
+	    TRANS_ID_NULL);
+  DEBUGT("retire {}~{} as placeholder, add extent -- {}",
+	 t, addr, length, *ext);
+  const auto t_src = t.get_src();
+  add_extent(ext, &t_src);
+  t.add_to_read_set(ext);
+  t.add_to_retired_set(ext);
+}
+
 void Cache::dump_contents()
 {
   LOG_PREFIX(Cache::dump_contents);

src/crimson/os/seastore/cache.h

@@ -246,6 +246,9 @@ class Cache {
   retire_extent_ret retire_extent_addr(
     Transaction &t, paddr_t addr, extent_len_t length);
 
+  void retire_absent_extent_addr(
+    Transaction &t, paddr_t addr, extent_len_t length);
+
   /**
    * get_root
    *
@@ -927,7 +930,7 @@ class Cache {
     paddr_t remap_paddr,
     extent_len_t remap_length,
     laddr_t original_laddr,
-    std::optional<ceph::bufferptr> &&original_bptr) {
+    std::optional<ceph::bufferptr> &original_bptr) {
     LOG_PREFIX(Cache::alloc_remapped_extent);
     assert(remap_laddr >= original_laddr);
     TCachedExtentRef<T> ext;

src/crimson/os/seastore/lba_manager.h

@@ -124,8 +124,7 @@ class LBAManager {
    */
   virtual ref_ret decref_extent(
     Transaction &t,
-    laddr_t addr,
-    bool cascade_remove) = 0;
+    laddr_t addr) = 0;
 
   /**
    * Increments ref count on extent
@@ -136,15 +135,34 @@ class LBAManager {
     Transaction &t,
     laddr_t addr) = 0;
 
+  struct remap_entry {
+    extent_len_t offset;
+    extent_len_t len;
+    remap_entry(extent_len_t _offset, extent_len_t _len) {
+      offset = _offset;
+      len = _len;
+    }
+  };
+  struct lba_remap_ret_t {
+    ref_update_result_t ruret;
+    std::vector<LBAMappingRef> remapped_mappings;
+  };
+  using remap_iertr = ref_iertr;
+  using remap_ret = remap_iertr::future<lba_remap_ret_t>;
+
   /**
-   * Increments ref count on extent
+   * remap_mappings
    *
-   * @return returns resulting refcount
+   * Remap an original mapping into new ones
+   * Return the old mapping's info and new mappings
    */
-  virtual ref_ret incref_extent(
+  virtual remap_ret remap_mappings(
     Transaction &t,
-    laddr_t addr,
-    int delta) = 0;
+    LBAMappingRef orig_mapping,
+    std::vector<remap_entry> remaps,
+    std::vector<LogicalCachedExtentRef> extents  // Required if and only
+						 // if pin isn't indirect
+    ) = 0;
 
   /**
    * Should be called after replay on each cached extent.