diff --git a/src/common/nbdtypes.c b/src/common/nbdtypes.c
index 08dc0c9..f45bf0f 100644
--- a/src/common/nbdtypes.c
+++ b/src/common/nbdtypes.c
@@ -28,7 +28,8 @@ void nbd_h2r_init( struct nbd_init * from, struct nbd_init_raw * to)
 void nbd_r2h_request( struct nbd_request_raw *from, struct nbd_request * to )
 {
 	to->magic = htobe32( from->magic );
-	to->type = htobe32( from->type );
+	to->flags = htobe16( from->flags );
+	to->type  = htobe16( from->type );
 	to->handle.w = from->handle.w;
 	to->from = htobe64( from->from );
 	to->len = htobe32( from->len );
@@ -37,7 +38,8 @@ void nbd_r2h_request( struct nbd_request_raw *from, struct nbd_request * to )
 void nbd_h2r_request( struct nbd_request * from, struct nbd_request_raw * to )
 {
 	to->magic = be32toh( from->magic );
-	to->type = be32toh( from->type );
+	to->flags = be16toh( from->flags );
+	to->type  = be16toh( from->type );
 	to->handle.w = from->handle.w;
 	to->from = be64toh( from->from );
 	to->len = be32toh( from->len );
diff --git a/src/common/nbdtypes.h b/src/common/nbdtypes.h
index bc4f413..7f406c2 100644
--- a/src/common/nbdtypes.h
+++ b/src/common/nbdtypes.h
@@ -8,20 +8,27 @@
 #define REQUEST_MAGIC 0x25609513
 #define REPLY_MAGIC 0x67446698
 #define REQUEST_READ 0
+
 #define REQUEST_WRITE 1
 #define REQUEST_DISCONNECT 2
+#define REQUEST_FLUSH 3
+#define REQUEST_TRIM 4
+#define REQUEST_WRITE_ZEROES 6
 
-#define NBD_FLAG_HAS_FLAGS         (1 << 0)
-#define NBD_FLAG_READ_ONLY         (1 << 1)
-#define NBD_FLAG_SEND_FLUSH        (1 << 2)
-#define NBD_FLAG_SEND_FUA          (1 << 3)
-#define NBD_FLAG_ROTATIONAL        (1 << 4)
-#define NBD_FLAG_SEND_TRIM         (1 << 5)
-#define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6)
+#define FLAG_HAS_FLAGS         (1 << 0)
+#define FLAG_READ_ONLY         (1 << 1)
+#define FLAG_SEND_FLUSH        (1 << 2)
+#define FLAG_SEND_FUA          (1 << 3)
+#define FLAG_ROTATIONAL        (1 << 4)
+#define FLAG_SEND_TRIM         (1 << 5)
+#define FLAG_SEND_WRITE_ZEROES (1 << 6)
+#define FLAG_CAN_MULTI_CONN    (1 << 8)        /* multiple connections are okay */
+
+#define CMD_FLAG_FUA     (1 << 0) 
+#define CMD_FLAG_NO_HOLE (1 << 1)
 
 /* The top 2 bytes of the type field are overloaded and can contain flags */
-#define REQUEST_MASK 0x0000ffff
-
+// #define REQUEST_MASK 0x0000ffff
 
 /* 1MiB is the de-facto standard for maximum size of header + data */
 #define NBD_MAX_SIZE ( 32 * 1024 * 1024 )
@@ -52,7 +59,8 @@ struct nbd_init_raw {
 
 struct nbd_request_raw {
 	__be32 magic;
-	__be32 type;    /* == READ || == WRITE  */
+	__be16 flags; 
+	__be16 type;    /* == READ || == WRITE || == FLUSH */
 	nbd_handle_t handle;
 	__be64 from;
 	__be32 len;
@@ -74,7 +82,8 @@ struct nbd_init {
 
 struct nbd_request {
 	uint32_t magic;
-	uint32_t type;    /* == READ || == WRITE || == DISCONNECT */
+	uint16_t flags; 
+	uint16_t type;    /* == READ || == WRITE || == DISCONNECT || == FLUSH */
 	nbd_handle_t handle;
 	uint64_t from;
 	uint32_t len;
diff --git a/src/proxy/proxy.c b/src/proxy/proxy.c
index bdc1407..c8af40e 100644
--- a/src/proxy/proxy.c
+++ b/src/proxy/proxy.c
@@ -305,7 +305,7 @@ int proxy_prefetch_for_request( struct proxier* proxy, int state )
 	struct nbd_request_raw* req_raw = (struct nbd_request_raw*) proxy->req.buf;
 	struct nbd_reply_raw *rsp_raw = (struct nbd_reply_raw*) proxy->rsp.buf;
 
-	int is_read = ( req->type & REQUEST_MASK ) == REQUEST_READ;
+	int is_read = req->type == REQUEST_READ;
 
 	if ( is_read ) {
 		/* See if we can respond with what's in our prefetch
@@ -435,19 +435,19 @@ int proxy_read_from_downstream( struct proxier *proxy, int state )
 	if ( proxy->req.needle == NBD_REQUEST_SIZE ) {
 		nbd_r2h_request( request_raw, request );
 
-		if ( ( request->type & REQUEST_MASK ) == REQUEST_DISCONNECT ) {
+		if ( request->type == REQUEST_DISCONNECT ) {
 			info( "Received disconnect request from client" );
 			return EXIT;
 		}
 
 		/* Simple validations */
-		if ( ( request->type & REQUEST_MASK ) == REQUEST_READ ) {
+		if ( request->type == REQUEST_READ ) {
 			if (request->len > ( NBD_MAX_SIZE - NBD_REPLY_SIZE ) ) {
 				warn( "NBD read request size %"PRIu32" too large", request->len );
 				return EXIT;
 			}
 		}
-		if ( (request->type & REQUEST_MASK ) == REQUEST_WRITE ) {
+		if ( request->type == REQUEST_WRITE ) {
 			if (request->len > ( NBD_MAX_SIZE - NBD_REQUEST_SIZE ) ) {
 				warn( "NBD write request size %"PRIu32" too large", request->len );
 				return EXIT;
@@ -607,7 +607,7 @@ int proxy_read_from_upstream( struct proxier* proxy, int state )
 			goto disconnect;
 		}
 
-		if ( ( proxy->req_hdr.type & REQUEST_MASK ) == REQUEST_READ ) {
+		if ( proxy->req_hdr.type == REQUEST_READ ) {
 			/* Get the read reply data too. */
 			proxy->rsp.size += proxy->req_hdr.len;
 		}
diff --git a/src/server/client.c b/src/server/client.c
index 9c23a4d..58ba199 100644
--- a/src/server/client.c
+++ b/src/server/client.c
@@ -308,7 +308,7 @@ void client_write_init( struct client * client, uint64_t size )
 	init.magic = INIT_MAGIC;
 	init.size = size;
 	// TODO actually implement these flags!
-	init.flags = NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA;
+	init.flags = FLAG_HAS_FLAGS | FLAG_SEND_FLUSH | FLAG_SEND_FUA;
 	// memset( init.reserved, 0, 124 );
 
 	nbd_h2r_init( &init, &init_raw );
@@ -385,8 +385,8 @@ int client_request_needs_reply( struct client * client,
 	}
 
 	debug(
-		"request type=%"PRIu32", from=%"PRIu64", len=%"PRIu32", handle=0x%08X",
-		request.type, request.from, request.len, request.handle
+		"request type=%"PRIu16", flags=%"PRIu16", from=%"PRIu64", len=%"PRIu32", handle=0x%08X",
+		request.type, request.flags, request.from, request.len, request.handle
 	);
 
 	/* check it's not out of range */
@@ -413,7 +413,8 @@ int client_request_needs_reply( struct client * client,
 		debug("request disconnect");
 		client->disconnect = 1;
 		return 0;
-
+	case REQUEST_FLUSH:
+		break;
 	default:
 		fatal("Unknown request 0x%08X", request.type);
 	}
@@ -474,7 +475,8 @@ void client_reply_to_write( struct client* client, struct nbd_request request )
 		bitset_set_range(client->serve->allocation_map, request.from, request.len);
 	}
 
-	if (1) /* not sure whether this is necessary... */
+	// Only flush if FUA is set
+	if (request.flags & CMD_FLAG_FUA)
 	{
 		/* multiple of 4K page size */
 		uint64_t from_rounded = request.from & (!0xfff);
@@ -490,6 +492,17 @@ void client_reply_to_write( struct client* client, struct nbd_request request )
 	client_write_reply( client, &request, 0);
 }
 
+void client_reply_to_flush( struct client* client, struct nbd_request request ) 
+{
+	debug("request flush from=%"PRIu64", len=%"PRIu32", handle=0x%08X", request.from, request.len, request.handle);
+
+	ERROR_IF_NEGATIVE(
+		fsync(client->fileno),
+		"flush failed"
+	);
+
+	client_write_reply( client, &request, 0);
+}
 
 void client_reply( struct client* client, struct nbd_request request )
 {
@@ -500,6 +513,9 @@ void client_reply( struct client* client, struct nbd_request request )
 	case REQUEST_WRITE:
 		client_reply_to_write( client, request );
 		break;
+	case REQUEST_FLUSH:
+		client_reply_to_flush( client, request );
+		break;
 	}
 }