crimson/os/seastore/object_data_handler: consider a RBM case when che…

…cking if write can be merged

RBM's paddr always indicates physical address, which means it doesn't have the dealayed.
So, this commit adds a condition that checks if given paddr is used for ongoing write.

Signed-off-by: Myoungwon Oh <myoungwon.oh@samsung.com>

src/crimson/os/seastore/object_data_handler.cc

@@ -576,7 +576,8 @@ struct overwrite_plan_t {
   overwrite_plan_t(laddr_t offset,
 		   extent_len_t len,
 		   const lba_pin_list_t& pins,
-		   extent_len_t block_size) :
+		   extent_len_t block_size,
+		   Transaction& t) :
       pin_begin(pins.front()->get_key()),
       pin_end(pins.back()->get_key() + pins.back()->get_length()),
       left_paddr(pins.front()->get_val()),
@@ -589,7 +590,7 @@ struct overwrite_plan_t {
       right_operation(overwrite_operation_t::UNKNOWN),
       block_size(block_size) {
     validate();
-    evaluate_operations();
+    evaluate_operations(t);
     assert(left_operation != overwrite_operation_t::UNKNOWN);
     assert(right_operation != overwrite_operation_t::UNKNOWN);
   }
@@ -617,19 +618,31 @@ struct overwrite_plan_t {
    * original extent into at most three parts: origin-left, part-to-be-modified
    * and origin-right.
    */
-  void evaluate_operations() {
+  void evaluate_operations(Transaction& t) {
     auto actual_write_size = get_pins_size();
     auto aligned_data_size = get_aligned_data_size();
     auto left_ext_size = get_left_extent_size();
     auto right_ext_size = get_right_extent_size();
 
+    auto can_merge = [](Transaction& t, paddr_t paddr) {
+      CachedExtentRef ext;
+      if (paddr.is_relative() || paddr.is_delayed()) {
+	  return true;
+      } else if (t.get_extent(paddr, &ext) ==
+	Transaction::get_extent_ret::PRESENT) {
+	// FIXME: there is no need to lookup the cache if the pin can 
+	// be associated with the extent state
+	if (ext->is_mutable()) {
+	  return true;
+	}
+      }
+      return false;
+    };
     if (left_paddr.is_zero()) {
       actual_write_size -= left_ext_size;
       left_ext_size = 0;
       left_operation = overwrite_operation_t::OVERWRITE_ZERO;
-    // FIXME: left_paddr can be absolute and pending
-    } else if (left_paddr.is_relative() ||
-	       left_paddr.is_delayed()) {
+    } else if (can_merge(t, left_paddr)) {
       aligned_data_size += left_ext_size;
       left_ext_size = 0;
       left_operation = overwrite_operation_t::MERGE_EXISTING;
@@ -639,9 +652,7 @@ struct overwrite_plan_t {
       actual_write_size -= right_ext_size;
       right_ext_size = 0;
       right_operation = overwrite_operation_t::OVERWRITE_ZERO;
-    // FIXME: right_paddr can be absolute and pending
-    } else if (right_paddr.is_relative() ||
-	       right_paddr.is_delayed()) {
+    } else if (can_merge(t, right_paddr)) {
       aligned_data_size += right_ext_size;
       right_ext_size = 0;
       right_operation = overwrite_operation_t::MERGE_EXISTING;
@@ -1148,7 +1159,7 @@ ObjectDataHandler::write_ret ObjectDataHandler::overwrite(
   if (bl.has_value()) {
     assert(bl->length() == len);
   }
-  overwrite_plan_t overwrite_plan(offset, len, _pins, ctx.tm.get_block_size());
+  overwrite_plan_t overwrite_plan(offset, len, _pins, ctx.tm.get_block_size(), ctx.t);
   return seastar::do_with(
     std::move(_pins),
     extent_to_write_list_t(),