[PATCH] kvm tools, 9p: Test for tuncation result

[Cyrill Gorcunov <gorcunov@gmail.com>]

Without 'ret' usage I get

 | cyrill@sun kvm $ make
 |  CC       virtio/9p.o
 | virtio/9p.c: In function ‘virtio_p9_wstat’:
 | virtio/9p.c:448:6: error: variable ‘res’ set but not used [-Werror=unused-but-set-variable]
 | cc1: all warnings being treated as errors
 | make: *** [virtio/9p.o] Error 1

so add a basic check for ftruncate result, this eliminate warning and
we might need to use 'res' status later in caller code.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
CC: Sasha Levin <levinsasha928@gmail.com>
---

Pekka, are you fine with 'kvm-tools,9p' prefix?

 tools/kvm/virtio/9p.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux-2.6.git/tools/kvm/virtio/9p.c
===================================================================
--- linux-2.6.git.orig/tools/kvm/virtio/9p.c
+++ linux-2.6.git/tools/kvm/virtio/9p.c
@@ -445,7 +445,7 @@ static bool virtio_p9_wstat(struct p9_ms
 	struct p9_twstat *twstat = (struct p9_twstat *)msg->msg;
 	struct p9_str *str;
 	struct p9_fid *fid = &p9dev.fids[twstat->fid];
-	int res;
+	int res = 0;

 	if (twstat->stat.length != -1UL)
 		res = ftruncate(fid->fd, twstat->stat.length);
@@ -472,7 +472,8 @@ static bool virtio_p9_wstat(struct p9_ms

 	*outlen = VIRTIO_P9_HDR_LEN;
 	set_p9msg_hdr(outmsg, *outlen, P9_RWSTAT, msg->tag);
-	return true;
+
+	return res == 0;
 }

 static bool virtio_p9_remove(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)