[CRIU] [PATCH] zdtm/mnt_tracefs: mount tracefs and don't affect an external mount namepace

[Tycho Andersen]

On Tue, May 24, 2016 at 12:07:54AM +0300, Andrey Vagin wrote:
> From: Andrew Vagin <avagin at virtuozzo.com>
> 
> ====================== Run zdtm/static/mnt_tracefs in uns ======================
> Start test
> ./mnt_tracefs --pidfile=mnt_tracefs.pid --outfile=mnt_tracefs.out --dirname=mnt_tracefs.test
> Run criu dump
> Wait for zdtm/static/mnt_tracefs to die for 0.100000
> Run criu restore
> Run criu dump
> Run criu restore
> Run criu dump
> Run criu restore
> 1: Old mounts lost: set([])
> 1: New mounts appeared: set([('/', '/debugfs/tracing')])
> Wait for zdtm/static/mnt_tracefs to die for 0.100000
> 
> Cc: Tycho Andersen <tycho.andersen at canonical.com>

Acked-by: Tycho Andersen <tycho.andersen at canonical.com>

Thanks, I guess all my test hosts have tracefs mounted because I've
been playing around with this :)

Tycho

> Signed-off-by: Andrew Vagin <avagin at virtuozzo.com>
> ---
>  test/zdtm/static/mnt_tracefs.c | 23 ++++++++---------------
>  1 file changed, 8 insertions(+), 15 deletions(-)
> 
> diff --git a/test/zdtm/static/mnt_tracefs.c b/test/zdtm/static/mnt_tracefs.c
> index 55a7d64..91d4585 100644
> --- a/test/zdtm/static/mnt_tracefs.c
> +++ b/test/zdtm/static/mnt_tracefs.c
> @@ -1,3 +1,5 @@
> +#define _GNU_SOURCE
> +#include <sched.h>
>  #include <sys/mount.h>
>  #include <unistd.h>
>  #include <sys/stat.h>
> @@ -18,8 +20,6 @@ TEST_OPTION(dirname, string, "directory name", 1);
>  int main(int argc, char ** argv)
>  {
>  	char dst[PATH_MAX], *root;
> -	int status;
> -	pid_t pid;
>  
>  	root = getenv("ZDTM_ROOT");
>  	if (root == NULL) {
> @@ -32,23 +32,16 @@ int main(int argc, char ** argv)
>  	if (strcmp(getenv("ZDTM_NEWNS"), "1"))
>  		goto test;
>  
> -	pid = fork();
> -	if (pid < 0)
> +	if (unshare(CLONE_NEWNS)) {
> +		pr_perror("unshare");
>  		return 1;
> -	if (pid == 0) {
> -		test_ext_init(argc, argv);
> -
> -		mkdir(dst, 755);
> -		if (mount("/sys/kernel/debug", dst, NULL, MS_BIND, NULL)) {
> -			pr_perror("mount");
> -			return 1;
> -		}
> -		return 0;
>  	}
>  
> -	wait(&status);
> -	if (status != 0)
> +	mkdir(dst, 755);
> +	if (mount("/sys/kernel/debug", dst, NULL, MS_BIND | MS_REC, NULL)) {
> +		pr_perror("mount");
>  		return 1;
> +	}
>  
>  test:
>  	test_init(argc, argv);
> -- 
> 2.7.4
>