page-read: Drop get_remote_pages

We already have routines that do send-req, recv-info
and recv-page, so no need in yet another one.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/include/page-xfer.h

@@ -52,9 +52,6 @@ extern int check_parent_page_xfer(int fd_type, long id);
  * - dump-side page server sends the raw page data
  */
 
-/* sync receive of remote pages */
-extern int get_remote_pages(int pid, unsigned long addr, int nr_pages, void *dest);
-
 /* async request/receive of remote pages */
 extern int request_remote_pages(int pid, unsigned long addr, int nr_pages);
 extern int receive_remote_pages_info(int *nr_pages, unsigned long *addr, int *pid);

criu/page-xfer.c

@@ -950,36 +950,6 @@ out:
 	return ret ? : status;
 }
 
-int get_remote_pages(int pid, unsigned long addr, int nr_pages, void *dest)
-{
-	int ret;
-	int len = PAGE_SIZE * nr_pages;
-
-	struct page_server_iov pi;
-
-	if (send_psi(page_server_sk, PS_IOV_GET, nr_pages, addr, pid))
-		return -1;
-
-	tcp_nodelay(page_server_sk, true);
-
-	ret = recv(page_server_sk, &pi, sizeof(pi), MSG_WAITALL);
-	if (ret != sizeof(pi))
-		return -1;
-
-	/* zero page */
-	if (pi.cmd == PS_IOV_ZERO)
-		return 0;
-
-	if (pi.nr_pages > nr_pages)
-		return -1;
-
-	ret = recv(page_server_sk, dest, len, MSG_WAITALL);
-	if (ret != len)
-		return -1;
-
-	return 1;
-}
-
 int request_remote_pages(int pid, unsigned long addr, int nr_pages)
 {
 	struct page_server_iov pi = {
@@ -1008,6 +978,10 @@ int receive_remote_pages_info(int *nr_pages, unsigned long *addr, int *pid)
 		return -1;
 	}
 
+	if (pi.cmd == PS_IOV_ZERO)
+		pr_warn("Unexpected ZERO page received for %d.%lx\n",
+				(int)pi.dst_id, (unsigned long)pi.vaddr);
+
 	*nr_pages = pi.nr_pages;
 	*addr = pi.vaddr;
 	*pid = pi.dst_id;

criu/pagemap.c

@@ -414,16 +414,19 @@ static int maybe_read_page_local(struct page_read *pr, unsigned long vaddr,
 static int maybe_read_page_remote(struct page_read *pr, unsigned long vaddr,
 				  int nr, void *buf, unsigned flags)
 {
-	int ret;
+	int ret, pid;
 
-	if (flags & PR_ASYNC)
-		/*
-		 * Note, that for async remote page_read, the actual
-		 * transfer happens in the lazy-pages daemon
-		 */
-		ret = request_remote_pages(pr->pid, vaddr, len / PAGE_SIZE);
-	else
-		ret = get_remote_pages(pr->pid, vaddr, nr, buf);
+	ret = request_remote_pages(pr->pid, vaddr, nr);
+	if ((ret < 0) || (flags & PR_ASYNC))
+		return ret;
+
+	/*
+	 * Note, that for async remote page_read, the actual
+	 * transfer happens in the lazy-pages daemon
+	 */
+	ret = receive_remote_pages_info(&nr, &vaddr, &pid);
+	if (ret == 0)
+		ret = receive_remote_pages(nr * PAGE_SIZE, buf);
 
 	return ret;
 }