crimson/os/seastore: cache metadata during trimming to prevent from disk read

I encountered continous disk reads during trimming even though there are sufficient
cache available, in 4K random write test with RBM (RBD).
This is because metadata is note cached if its source is background transaction
within touch_extent(). So, seastore, including the trimming process,  needs to
constantly retrieve metadata (e.g., BACKREF_LEAF).

Signed-off-by: Myoungwon Oh <myoungwon.oh@samsung.com>
(cherry picked from commit 7f253ce5aa98018b5b209fd6e062078d151ad567)

diff --git a/src/crimson/os/seastore/cache.h b/src/crimson/os/seastore/cache.h
index 75463f465fe14c7d68b38701906d8851ab76973e..829d57da19312a0ba46ba28f9dbbdc1037d93fe8 100644 (file)
--- a/src/crimson/os/seastore/cache.h
+++ b/src/crimson/os/seastore/cache.h
@@ -1342,8 +1342,11 @@ public:
       CachedExtent &ext,
       const Transaction::src_t* p_src=nullptr)
   {
-    if (p_src && is_background_transaction(*p_src))
+    if (p_src &&
+       is_background_transaction(*p_src) &&
+       is_logical_type(ext.get_type())) {
       return;
+    }
     if (ext.is_stable_clean() && !ext.is_placeholder()) {
       lru.move_to_top(ext);
     }