From e46ba88614acfec0719f889b7cb09a41f13f7f41 Mon Sep 17 00:00:00 2001
From: Andrew Vagin <avagin@virtuozzo.com>
Date: Fri, 29 Jul 2016 09:41:00 +0300
Subject: [PATCH] files: don't create a transport socket for each file

This is an unix dgram socket which doesn't have an address and
isn't connected to somewhere, so we can use one socket for all processes.

v2: return non-zero code in error cases
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
---
 criu/cr-restore.c        |  6 ++++++
 criu/files.c             | 25 +++++++++++++++++++------
 criu/include/files.h     |  2 ++
 criu/include/servicefd.h |  1 +
 4 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/criu/cr-restore.c b/criu/cr-restore.c
index 5db7cf189..bec321cfb 100644
--- a/criu/cr-restore.c
+++ b/criu/cr-restore.c
@@ -267,6 +267,10 @@ static int root_prepare_shared(void)
 	if (ret)
 		goto err;
 
+	ret = open_transport_socket();
+	if (ret)
+		goto err;
+
 	show_saved_files();
 err:
 	return ret;
@@ -603,6 +607,8 @@ static int restore_one_alive_task(int pid, CoreEntry *core)
 	if (prepare_vmas(current, ta))
 		return -1;
 
+	close_service_fd(TRANSPORT_FD_OFF);
+
 	return sigreturn_restore(pid, ta, args_len, core);
 }
 
diff --git a/criu/files.c b/criu/files.c
index a66a1424d..a29d317e6 100644
--- a/criu/files.c
+++ b/criu/files.c
@@ -1000,11 +1000,7 @@ static int serve_out_fd(int pid, int fd, struct file_desc *d)
 	int sock, ret;
 	struct fdinfo_list_entry *fle;
 
-	sock = socket(PF_UNIX, SOCK_DGRAM, 0);
-	if (sock < 0) {
-		pr_perror("Can't create socket");
-		return -1;
-	}
+	sock = get_service_fd(TRANSPORT_FD_OFF);
 
 	pr_info("\t\tCreate fd for %d\n", fd);
 
@@ -1022,7 +1018,6 @@ static int serve_out_fd(int pid, int fd, struct file_desc *d)
 
 	ret = 0;
 out:
-	close(sock);
 	return ret;
 }
 
@@ -1672,3 +1667,21 @@ char *external_lookup_by_key(char *key)
 	}
 	return NULL;
 }
+
+int open_transport_socket()
+{
+	int sock;
+
+	sock = socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
+	if (sock < 0) {
+		pr_perror("Can't create socket");
+		return -1;
+	}
+	if (install_service_fd(TRANSPORT_FD_OFF, sock) < 0) {
+		close(sock);
+		return -1;
+	}
+	close(sock);
+
+	return 0;
+}
diff --git a/criu/include/files.h b/criu/include/files.h
index e0b853dc4..7513b2157 100644
--- a/criu/include/files.h
+++ b/criu/include/files.h
@@ -201,4 +201,6 @@ extern FdinfoEntry *dup_fdinfo(FdinfoEntry *old, int fd, unsigned flags);
 int dup_fle(struct pstree_item *task, struct fdinfo_list_entry *ple,
 	    int fd, unsigned flags);
 
+extern int open_transport_socket(void);
+
 #endif /* __CR_FILES_H__ */
diff --git a/criu/include/servicefd.h b/criu/include/servicefd.h
index e133752fc..a35f25aa6 100644
--- a/criu/include/servicefd.h
+++ b/criu/include/servicefd.h
@@ -19,6 +19,7 @@ enum sfd_type {
 	CGROUP_YARD,
 	USERNSD_SK,	/* Socket for usernsd */
 	NS_FD_OFF,	/* Node's net namespace fd */
+	TRANSPORT_FD_OFF, /* to transfer file descriptors */
 
 	SERVICE_FD_MAX
 };