Merge branch 'reinstate-sync-after-every-write' into 'develop'

Reinstate sync after every write

See merge request open-source/flexnbd-c!51

debian/changelog

@@ -1,3 +1,9 @@
+flexnbd (0.2.1) UNRELEASED; urgency=medium
+
+  * Force a msync after every write, ignoring FUA flag, or lack thereof.
+
+ -- Patrick J Cherry <patrick@bytemark.co.uk>  Tue, 24 Apr 2018 10:27:12 +0100
+
 flexnbd (0.2.0) stable; urgency=medium
 
   [ James Carter ]

src/server/client.c

@@ -470,8 +470,10 @@ void client_reply_to_write(struct client *client,
 			 request.len);
     }
 
-    // Only flush if FUA is set
-    if (request.flags & CMD_FLAG_FUA) {
+    // Only flush if FUA is set -- overridden for now to force flush after each
+    // write.
+    // if (request.flags & CMD_FLAG_FUA) {
+    if (1) {
 	/* multiple of page size */
 	uint64_t from_rounded =
 	    request.from & (~(sysconf(_SC_PAGE_SIZE) - 1));