[CRIU] [PATCH v2] files: don't create a transport socket for each file

[Pavel Emelyanov]

On 07/29/2016 09:41 AM, Andrey Vagin wrote:
> From: Andrew Vagin <avagin at virtuozzo.com>
> 
> 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 at 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 9bd1747..6c83d7f 100644
> --- a/criu/cr-restore.c
> +++ b/criu/cr-restore.c
> @@ -271,6 +271,10 @@ static int root_prepare_shared(void)
>  	if (ret)
>  		goto err;
>  
> +	ret = open_transport_socket();

It has to be per-netns, I guess, and thus -- sit on struct ns_id
in the struct { } net?

> +	if (ret)
> +		goto err;
> +
>  	show_saved_files();
>  err:
>  	return ret;
> @@ -711,6 +715,8 @@ static int restore_one_alive_task(int pid, CoreEntry *core)
>  	if (prepare_vmas(current, ta))
>  		return -1;
>  
> +	close_service_fd(TRANSPORT_FD_OFF);
> +
>  	if (setup_uffd(pid, ta))
>  		return -1;
>  
> diff --git a/criu/files.c b/criu/files.c
> index a66a142..a29d317 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 e0b853d..7513b21 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 e133752..a35f25a 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
>  };
>