The max size of the write buffer size can be 64 GB.

Summary: There was an artifical limit on the size of the write buffer size.

Test Plan: make check

Reviewers: haobo

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10911

db/db_impl.cc

@@ -123,7 +123,8 @@ Options SanitizeOptions(const std::string& dbname,
   result.comparator = icmp;
   result.filter_policy = (src.filter_policy != nullptr) ? ipolicy : nullptr;
   ClipToRange(&result.max_open_files,            20,     1000000);
-  ClipToRange(&result.write_buffer_size,         64<<10, 1<<30);
+  ClipToRange(&result.write_buffer_size,         ((size_t)64)<<10,
+                                                 ((size_t)64)<<30);
   ClipToRange(&result.block_size,                1<<10,  4<<20);
   if (result.info_log == nullptr) {
     Status s = CreateLoggerFromOptions(dbname, result.db_log_dir, src.env,