crimson/os/seastore/cache: backref buffer minor bug fix

Signed-off-by: Xuehan Xu <xxhdx1985126@gmail.com>

diff --git a/src/crimson/os/seastore/cache.h b/src/crimson/os/seastore/cache.h
index ba6999e5f82e14ef75ba0189de022dc9c16a92ca..6a2b54dbef5dbea948f0c7dc2dd607738292baac 100644 (file)
--- a/src/crimson/os/seastore/cache.h
+++ b/src/crimson/os/seastore/cache.h
@@ -635,12 +635,11 @@ public:
   void trim_backref_bufs(const journal_seq_t &trim_to) {
     LOG_PREFIX(Cache::trim_backref_bufs);
     SUBDEBUG(seastore_cache, "trimming to {}", trim_to);
-    if (backref_buffer) {
+    if (backref_buffer && !backref_buffer->backrefs.empty()) {
       assert(backref_buffer->backrefs.rbegin()->first >= trim_to);
       auto iter = backref_buffer->backrefs.upper_bound(trim_to);
-      SUBDEBUG(seastore_cache, "trim backref buffer up to {}", iter->first);
       backref_buffer->backrefs.erase(
-        backref_buffer->backrefs.begin(), iter);
+       backref_buffer->backrefs.begin(), iter);
     }
   }