From 5d4b43ad260db8d9cceeaae87583d81821ac8cfa Mon Sep 17 00:00:00 2001
From: Samuel Just <sjust@redhat.com>
Date: Fri, 21 Aug 2020 14:32:55 -0700
Subject: [PATCH] crimson/os/seastore/cache: replay_delta handle obsolete
 extents properly

If we see a delta at verison v (v != 0) and we haven't seen version v-1,
we know that the extent is obsolete and can be ignored (presuming that
journal trimming is behaving).

Signed-off-by: Samuel Just <sjust@redhat.com>
---
 src/crimson/os/seastore/cache.cc | 55 ++++++++++++++++++++++----------
 1 file changed, 38 insertions(+), 17 deletions(-)

diff --git a/src/crimson/os/seastore/cache.cc b/src/crimson/os/seastore/cache.cc
index 34ed12d4e93..48ff8a36f07 100644
--- a/src/crimson/os/seastore/cache.cc
+++ b/src/crimson/os/seastore/cache.cc
@@ -319,28 +319,49 @@ Cache::replay_delta(
     root->dirty_from = journal_seq;
     return replay_delta_ertr::now();
   } else {
-    return get_extent_by_type(
-      delta.type,
-      delta.paddr,
-      delta.laddr,
-      delta.length).safe_then([=](auto extent) {
+    auto get_extent_if_cached = [this](paddr_t addr)
+      -> replay_delta_ertr::future<CachedExtentRef> {
+      auto retiter = extents.find_offset(addr);
+      if (retiter != extents.end()) {
+	return replay_delta_ertr::make_ready_future<CachedExtentRef>(&*retiter);
+      } else {
+	return replay_delta_ertr::make_ready_future<CachedExtentRef>();
+      }
+    };
+    auto extent_fut = delta.pversion == 0 ?
+      get_extent_by_type(
+	delta.type,
+	delta.paddr,
+	delta.laddr,
+	delta.length) :
+      get_extent_if_cached(
+	delta.paddr);
+    return extent_fut.safe_then([=, &delta](auto extent) {
+      if (!extent) {
+	assert(delta.pversion > 0);
 	logger().debug(
-	  "replay_delta: replaying {} on {}",
-	  *extent,
+	  "replay_delta: replaying {}, extent not present so delta is obsolete",
 	  delta);
+	return;
+      }
 
-	assert(extent->version == delta.pversion);
+      logger().debug(
+	"replay_delta: replaying {} on {}",
+	  *extent,
+	delta);
 
-	assert(extent->last_committed_crc == delta.prev_crc);
-	extent->apply_delta_and_adjust_crc(record_base, delta.bl);
-	assert(extent->last_committed_crc == delta.final_crc);
+      assert(extent->version == delta.pversion);
 
-	if (extent->version == 0) {
-	  extent->dirty_from = journal_seq;
-	}
-	extent->version++;
-	mark_dirty(extent);
-      });
+      assert(extent->last_committed_crc == delta.prev_crc);
+      extent->apply_delta_and_adjust_crc(record_base, delta.bl);
+      assert(extent->last_committed_crc == delta.final_crc);
+
+      if (extent->version == 0) {
+	extent->dirty_from = journal_seq;
+      }
+      extent->version++;
+      mark_dirty(extent);
+    });
   }
 }
 
-- 
2.39.5