socket: increase socket buffers for restoring queues (v2)

Sizes of send and recv buffers are set to maximum to restore queues,
after that sizes of buffers are restored.

O_NONBLOCK is set to a socket to prevent blocking during restore.

#2411

v2: do the same for unix sockets.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/sockets.h

@@ -30,6 +30,7 @@ extern int dump_socket(struct fd_parms *p, int lfd, const struct cr_fdset *cr_fd
 extern int dump_socket_opts(int sk, SkOptsEntry *soe);
 extern int restore_socket_opts(int sk, SkOptsEntry *soe);
 extern void release_skopts(SkOptsEntry *);
+extern int restore_prepare_socket(int sk);
 
 extern int sk_collect_one(int ino, int family, struct socket_desc *d);
 extern int collect_sockets(int pid);

sk-queue.c

@@ -16,6 +16,7 @@
 #include "crtools.h"
 #include "util.h"
 #include "util-net.h"
+#include "sockets.h"
 
 #include "sk-queue.h"
 
@@ -189,19 +190,12 @@ void show_sk_queues(int fd, struct cr_options *o)
 int restore_sk_queue(int fd, unsigned int peer_id)
 {
 	struct sk_packet *pkt, *tmp;
-	int ret, img_fd, flags;
+	int ret, img_fd;
 
 	pr_info("Trying to restore recv queue for %u\n", peer_id);
 
-	flags = fcntl(fd, F_GETFL, 0);
-	if (flags == -1) {
-		pr_perror("Unable to get flags for %d", fd);
+	if (restore_prepare_socket(fd))
 		return -1;
-	}
-	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) ) {
-		pr_perror("Unable to set O_NONBLOCK for %d", fd);
-		return -1;
-	}
 
 	img_fd = open_image_ro(CR_FD_SK_QUEUES);
 	if (img_fd < 0)
@@ -255,11 +249,6 @@ int restore_sk_queue(int fd, unsigned int peer_id)
 		xfree(pkt);
 	}
 
-	if (fcntl(fd, F_SETFL, flags) ) {
-		pr_perror("Unable to restore flags for %d", fd);
-		goto err;
-	}
-
 	close(img_fd);
 	return 0;
 err:

sk-tcp.c

@@ -379,6 +379,9 @@ static int send_tcp_queue(int sk, int queue, u32 len, int imgfd)
 
 static int restore_tcp_queues(int sk, TcpStreamEntry *tse, int fd)
 {
+	if (restore_prepare_socket(sk))
+		return -1;
+
 	if (tse->inq_len &&
 			send_tcp_queue(sk, TCP_RECV_QUEUE, tse->inq_len, fd))
 		return -1;

sockets.c

@@ -204,6 +204,38 @@ int do_restore_opt(int sk, int level, int name, void *val, int len)
 	return 0;
 }
 
+/*
+ * Set sizes of buffers to maximum and prevent blocking
+ * Caller of this fn should call other socket restoring
+ * routines to drop the non-blocking and set proper send
+ * and receive buffers.
+ */
+int restore_prepare_socket(int sk)
+{
+	int flags;
+
+	/* In kernel a bufsize has type int and a value is doubled. */
+	u32 maxbuf = INT_MAX / 2;
+
+	if (restore_opt(sk, SOL_SOCKET, SO_SNDBUFFORCE, &maxbuf))
+		return -1;
+	if (restore_opt(sk, SOL_SOCKET, SO_RCVBUFFORCE, &maxbuf))
+		return -1;
+
+	/* Prevent blocking on restore */
+	flags = fcntl(sk, F_GETFL, 0);
+	if (flags == -1) {
+		pr_perror("Unable to get flags for %d", sk);
+		return -1;
+	}
+	if (fcntl(sk, F_SETFL, flags | O_NONBLOCK) ) {
+		pr_perror("Unable to set O_NONBLOCK for %d", sk);
+		return -1;
+	}
+
+	return 0;
+}
+
 int restore_socket_opts(int sk, SkOptsEntry *soe)
 {
 	int ret = 0, val;