RE: [PATCH 1/2] tools: hv: use FIFREEZE/FITHAW in hv_vss_daemon

[KY Srinivasan <kys@microsoft.com>]

> -----Original Message-----
> From: Olaf Hering [mailto:olaf@aepfle.de]
> Sent: Tuesday, March 26, 2013 12:47 PM
> To: KY Srinivasan; gregkh@linuxfoundation.org
> Cc: linux-kernel@vger.kernel.org; Olaf Hering
> Subject: [PATCH 1/2] tools: hv: use FIFREEZE/FITHAW in hv_vss_daemon
> 
> As suggested by Paolo Bonzini, use ioctl instead of calling fsfreeze.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>

Thanks Olaf for taking care of this.

Acked by: K. Y. Srinivasan <kys@microsoft.com>

> ---
> 
> NOT runtime tested!!
> 
>  tools/hv/hv_vss_daemon.c | 31 ++++++++++++++++++++++---------
>  1 file changed, 22 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
> index e37d86c..830d606 100644
> --- a/tools/hv/hv_vss_daemon.c
> +++ b/tools/hv/hv_vss_daemon.c
> @@ -21,7 +21,9 @@
>  #include <sys/types.h>
>  #include <sys/socket.h>
>  #include <sys/poll.h>
> +#include <sys/ioctl.h>
>  #include <linux/types.h>
> +#include <fcntl.h>
>  #include <stdio.h>
>  #include <mntent.h>
>  #include <stdlib.h>
> @@ -30,6 +32,7 @@
>  #include <ctype.h>
>  #include <errno.h>
>  #include <arpa/inet.h>
> +#include <linux/fs.h>
>  #include <linux/connector.h>
>  #include <linux/hyperv.h>
>  #include <linux/netlink.h>
> @@ -44,21 +47,35 @@ static struct sockaddr_nl addr;
>  #endif
> 
> 
> +static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op)
> +{
> +	int ret, fd = open(dir, O_RDONLY);
> +
> +	if (fd < 0)
> +		return 1;
> +	ret = ioctl(fd, cmd, 0);
> +	syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno));
> +	close(fd);
> +	return !!ret;
> +}
> +
>  static int vss_operate(int operation)
>  {
>  	char *fs_op;
> -	char cmd[512];
>  	char match[] = "/dev/";
>  	FILE *mounts;
>  	struct mntent *ent;
> +	unsigned int cmd;
>  	int error = 0, root_seen = 0;
> 
>  	switch (operation) {
>  	case VSS_OP_FREEZE:
> -		fs_op = "-f ";
> +		cmd = FIFREEZE;
> +		fs_op = "freeze";
>  		break;
>  	case VSS_OP_THAW:
> -		fs_op = "-u ";
> +		cmd = FITHAW;
> +		fs_op = "thaw";
>  		break;
>  	default:
>  		return -1;
> @@ -75,16 +92,12 @@ static int vss_operate(int operation)
>  			root_seen = 1;
>  			continue;
>  		}
> -		snprintf(cmd, sizeof(cmd), "fsfreeze %s '%s'", fs_op, ent-
> >mnt_dir);
> -		syslog(LOG_INFO, "VSS cmd is %s\n", cmd);
> -		error |= system(cmd);
> +		error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op);
>  	}
>  	endmntent(mounts);
> 
>  	if (root_seen) {
> -		sprintf(cmd, "fsfreeze %s /", fs_op);
> -		syslog(LOG_INFO, "VSS cmd is %s\n", cmd);
> -		error |= system(cmd);
> +		error |= vss_do_freeze("/", cmd, fs_op);
>  	}
> 
>  	return error;
>