From f9d0aae639820b93284c06f9d77053f35ef880e1 Mon Sep 17 00:00:00 2001
From: Samuel Just <sjust@redhat.com>
Date: Fri, 21 Aug 2020 14:28:50 -0700
Subject: [PATCH] crimson/os/seastore/transaction: let get_extent signal
 retired extents

Signed-off-by: Samuel Just <sjust@redhat.com>
---
 src/crimson/os/seastore/cache.h       | 12 +++++++++---
 src/crimson/os/seastore/transaction.h | 21 ++++++++++++++++-----
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/src/crimson/os/seastore/cache.h b/src/crimson/os/seastore/cache.h
index a31e044e1d60f..f57f1df67df1b 100644
--- a/src/crimson/os/seastore/cache.h
+++ b/src/crimson/os/seastore/cache.h
@@ -161,6 +161,8 @@ public:
    * - t if modified by t
    * - extent_set if already in cache
    * - disk
+   *
+   * t *must not* have retired offset
    */
   template <typename T>
   get_extent_ertr::future<TCachedExtentRef<T>> get_extent(
@@ -168,14 +170,18 @@ public:
     paddr_t offset,       ///< [in] starting addr
     segment_off_t length  ///< [in] length
   ) {
-    if (auto i = t.get_extent(offset)) {
+    CachedExtentRef ret;
+    auto result = t.get_extent(offset, &ret);
+    if (result != Transaction::get_extent_ret::ABSENT) {
+      assert(result != Transaction::get_extent_ret::RETIRED);
       return get_extent_ertr::make_ready_future<TCachedExtentRef<T>>(
-	TCachedExtentRef<T>(static_cast<T*>(&*i)));
+	ret->cast<T>());
     } else {
       return get_extent<T>(offset, length).safe_then(
 	[&t](auto ref) mutable {
 	  t.add_to_read_set(ref);
-	  return get_extent_ertr::make_ready_future<TCachedExtentRef<T>>(std::move(ref));
+	  return get_extent_ertr::make_ready_future<TCachedExtentRef<T>>(
+	    std::move(ref));
 	});
     }
   }
diff --git a/src/crimson/os/seastore/transaction.h b/src/crimson/os/seastore/transaction.h
index 60d295820ebbc..e27531eac8946 100644
--- a/src/crimson/os/seastore/transaction.h
+++ b/src/crimson/os/seastore/transaction.h
@@ -32,16 +32,27 @@ class Transaction {
   pextent_set_t retired_set; ///< list of extents mutated by this transaction
 
 public:
-  CachedExtentRef get_extent(paddr_t addr) {
-    if (auto iter = write_set.find_offset(addr);
+  enum class get_extent_ret {
+    PRESENT,
+    ABSENT,
+    RETIRED
+  };
+  get_extent_ret get_extent(paddr_t addr, CachedExtentRef *out) {
+    if (retired_set.count(addr)) {
+      return get_extent_ret::RETIRED;
+    } else if (auto iter = write_set.find_offset(addr);
 	iter != write_set.end()) {
-      return CachedExtentRef(&*iter);
+      if (out)
+	*out = CachedExtentRef(&*iter);
+      return get_extent_ret::PRESENT;
     } else if (
       auto iter = read_set.find(addr);
       iter != read_set.end()) {
-      return *iter;
+      if (out)
+	*out = CachedExtentRef(*iter);
+      return get_extent_ret::PRESENT;
     } else {
-      return CachedExtentRef();
+      return get_extent_ret::ABSENT;
     }
   }
 
-- 
2.39.5