1 files changed, 57 insertions, 0 deletions
diff --git a/src/librbd/io/Utils.cc b/src/librbd/io/Utils.cc
new file mode 100644
index 00000000..1b50561a
--- /dev/null
+++ b/src/librbd/io/Utils.cc
@@ -0,0 +1,57 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "librbd/io/Utils.h"
+#include "include/buffer.h"
+#include "osd/osd_types.h"
+
+namespace librbd {
+namespace io {
+namespace util {
+
+bool assemble_write_same_extent(
+    const ObjectExtent &object_extent, const ceph::bufferlist& data,
+    ceph::bufferlist *ws_data, bool force_write) {
+  size_t data_len = data.length();
+
+  if (!force_write) {
+    bool may_writesame = true;
+    for (auto& q : object_extent.buffer_extents) {
+      if (!(q.first % data_len == 0 && q.second % data_len == 0)) {
+        may_writesame = false;
+        break;
+      }
+    }
+
+    if (may_writesame) {
+      ws_data->append(data);
+      return true;
+    }
+  }
+
+  for (auto& q : object_extent.buffer_extents) {
+    bufferlist sub_bl;
+    uint64_t sub_off = q.first % data_len;
+    uint64_t sub_len = data_len - sub_off;
+    uint64_t extent_left = q.second;
+    while (extent_left >= sub_len) {
+      sub_bl.substr_of(data, sub_off, sub_len);
+      ws_data->claim_append(sub_bl);
+      extent_left -= sub_len;
+      if (sub_off) {
+	sub_off = 0;
+	sub_len = data_len;
+      }
+    }
+    if (extent_left) {
+      sub_bl.substr_of(data, sub_off, extent_left);
+      ws_data->claim_append(sub_bl);
+    }
+  }
+  return false;
+}
+
+} // namespace util
+} // namespace io
+} // namespace librbd
+