Added test for FUA acceptance.

Although I think this might be a bit useless as servers normally just
ingore flags.

src/server/client.c

@@ -483,6 +483,7 @@ void client_reply_to_write( struct client* client, struct nbd_request request )
 		/* multiple of 4K page size */
 		uint64_t from_rounded = request.from & (!0xfff);
 		uint64_t len_rounded = request.len + (request.from - from_rounded);
+		debug("Calling msync from=%"PRIu64", len=%"PRIu64"",from_rounded, len_rounded);
 
 		FATAL_IF_NEGATIVE(
 			msync( client->mapped + from_rounded,

tests/acceptance/flexnbd.rb

@@ -195,6 +195,7 @@ module FlexNBD
       @ctrl = "/tmp/.flexnbd.ctrl.#{Time.now.to_i}.#{rand}"
       @ip = ip
       @port = port
+      @pid = @wait_thread = nil
       @kill = []
       @prefetch_proxy = false
     end

tests/acceptance/flexnbd/fake_source.rb

@@ -40,11 +40,12 @@ module FlexNBD
       end
     end
 
-    def send_request(type, handle = 'myhandle', from = 0, len = 0, magic = REQUEST_MAGIC)
+    def send_request(type, handle = 'myhandle', from = 0, len = 0, magic = REQUEST_MAGIC, flags = 0)
       raise 'Bad handle' unless handle.length == 8
 
       @sock.write(magic)
-      @sock.write([type].pack('N'))
+      @sock.write([flags].pack('n'))
+      @sock.write([type].pack('n'))
       @sock.write(handle)
       @sock.write([n64(from)].pack('q'))
       @sock.write([len].pack('N'))
@@ -53,7 +54,11 @@ module FlexNBD
     def write_write_request(from, len, handle = 'myhandle')
       send_request(1, handle, from, len)
     end
-    
+
+    def write_write_request_with_fua(from, len, handle = 'myhandle')
+      send_request(1, handle, from, len, REQUEST_MAGIC, 1)
+    end
+
     def write_flush_request(handle = 'myhandle')
       send_request(3, handle, 0, 0)
     end
@@ -99,6 +104,11 @@ module FlexNBD
       write_data(data)
     end
 
+    def write_with_fua(from, data)
+      write_write_request_with_fua(from, data.length)
+      write_data(data)
+    end
+
     def flush
       write_flush_request
     end

tests/acceptance/test_serve_mode.rb

@@ -1,7 +1,6 @@
 require 'test/unit'
 require 'environment'
 require 'flexnbd/fake_source'
-require 'pp'
 
 class TestServeMode < Test::Unit::TestCase
   def setup
@@ -118,4 +117,14 @@ class TestServeMode < Test::Unit::TestCase
       assert_equal 0, rsp[:error]
     end
   end
+
+  def test_write_with_fua_is_accepted
+    connect_to_server do |client|
+      # Start with a file of all-zeroes.
+      client.write_with_fua(0, "\x00" * @env.file1.size)
+      rsp = client.read_response
+      assert_equal FlexNBD::REPLY_MAGIC, rsp[:magic]
+      assert_equal 0, rsp[:error]
+    end
+  end
 end