crimson/os/seastore/btree: correct lba pointer comments

Signed-off-by: Xuehan Xu <xuxuehan@qianxin.com>
(cherry picked from commit 9bb054b30f66d1b03f0ea6937b08806c4b64f5b6)

diff --git a/src/crimson/os/seastore/btree/fixed_kv_node.h b/src/crimson/os/seastore/btree/fixed_kv_node.h
index a3a9569a669515f46206ce976cf7568de915af2d..a64585a9402cf237ce99a57909ff3819188627db 100644 (file)
--- a/src/crimson/os/seastore/btree/fixed_kv_node.h
+++ b/src/crimson/os/seastore/btree/fixed_kv_node.h
@@ -59,7 +59,7 @@ struct FixedKVNode : ChildableCachedExtent {
    *   b. prior_instance is empty
    *   c. child pointers point at stable children. Child resolution is done
    *      directly via this array.
-   *   c. copy_sources is empty
+   *   d. copy_sources is empty
    * 2. if nodes are mutation_pending:
    *   a. parent is empty and needs to be fixed upon commit
    *   b. prior_instance points to its stable version
@@ -67,7 +67,7 @@ struct FixedKVNode : ChildableCachedExtent {
    *      this transaction. Child resolution is done by first checking this
    *      array, and then recursively resolving via the parent. We copy child
    *      pointers from parent on commit.
-   *   c. copy_sources is empty
+   *   d. copy_sources is empty
    * 3. if nodes are initial_pending
    *   a. parent points at its pending parent on this transaction (must exist)
    *   b. prior_instance is empty or, if it's the result of rewrite, points to
@@ -80,6 +80,8 @@ struct FixedKVNode : ChildableCachedExtent {
    *   d. copy_sources contains the set of stable nodes at the same tree-level(only
    *      its "prior_instance" if the node is the result of a rewrite), with which
    *      the lba range of this node overlaps.
+   * 4. EXIST_CLEAN and EXIST_MUTATION_PENDING belong to 3 above (except that they
+   *   cannot be rewritten) because their parents must be mutated upon remapping.
    */
   std::vector<ChildableCachedExtent*> children;
   std::set<FixedKVNodeRef, copy_source_cmp_t> copy_sources;