From: Xuehan Xu <xxhdx1985126@gmail.com>
Date: Thu, 23 Mar 2023 09:59:12 +0000 (+0000)
Subject: crimson/os/seastore/cache: add comment about backref_extent_entry_t
X-Git-Tag: v18.1.0~34^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=ccccd4a9868c54ee57e445bae9a5b2dde36a458e;p=ceph.git

crimson/os/seastore/cache: add comment about backref_extent_entry_t

Signed-off-by: Xuehan Xu <xxhdx1985126@gmail.com>
(cherry picked from commit 62974a65897edce2afdb16ba99baea0193a0d4a6)
---

diff --git a/src/crimson/os/seastore/cache.h b/src/crimson/os/seastore/cache.h
index 3abb7bb9360c..9289dda0881b 100644
--- a/src/crimson/os/seastore/cache.h
+++ b/src/crimson/os/seastore/cache.h
@@ -1106,6 +1106,14 @@ public:
   /// Dump live extents
   void dump_contents();
 
+  /**
+   * backref_extent_entry_t
+   *
+   * All the backref extent entries have to be indexed by paddr in memory,
+   * so they can be retrived by range during cleaning.
+   *
+   * See BtreeBackrefManager::retrieve_backref_extents_in_range()
+   */
   struct backref_extent_entry_t {
     backref_extent_entry_t(
       paddr_t paddr,