crimson/os/seastore/cached_extent: add comments to elaborate why

MUTATION_PENDING and under-io extents are "stable"

Signed-off-by: Xuehan Xu <xuxuehan@qianxin.com>
(cherry picked from commit b1c59ca077597e14a053d47d4961b12ba7a2a1b0)

diff --git a/src/crimson/os/seastore/cached_extent.h b/src/crimson/os/seastore/cached_extent.h
index 18ddbd95796c332d285bdd0ebcdbc6b4e94e01a6..730a0ace9a0b750bfe8743d52e19b73656e40579 100644 (file)
--- a/src/crimson/os/seastore/cached_extent.h
+++ b/src/crimson/os/seastore/cached_extent.h
@@ -426,6 +426,9 @@ public:
   /// 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());
   }