Make virsh setmaxmem balloon only when successful.

After playing around with virsh setmaxmem for a bit,
I ran into some surprising behavior; if a hypervisor does
not support the virDomainSetMaxMemory() API, but the value
specified for setmaxmem is less than the current amount
of memory in the domain, the domain would be ballooned
down *before* an error was reported.

To make this more consistent, run virDomainSetMaxMemory()
before trying to shrink; that way, if an error is thrown,
no changes to the running domain are made.
Signed-off-by: NChris Lalancette <clalance@redhat.com>

tools/virsh.c

@@ -2596,18 +2596,18 @@ cmdSetmaxmem(vshControl *ctl, const vshCmd *cmd)
         return FALSE;
     }
 
-    if (kilobytes < info.memory) {
-        if (virDomainSetMemory(dom, kilobytes) != 0) {
+    if (virDomainSetMaxMemory(dom, kilobytes) != 0) {
+        vshError(ctl, "%s", _("Unable to change MaxMemorySize"));
         virDomainFree(dom);
-            vshError(ctl, "%s", _("Unable to shrink current MemorySize"));
         return FALSE;
     }
-    }
 
-    if (virDomainSetMaxMemory(dom, kilobytes) != 0) {
-        vshError(ctl, "%s", _("Unable to change MaxMemorySize"));
+    if (kilobytes < info.memory) {
+        if (virDomainSetMemory(dom, kilobytes) != 0) {
+            vshError(ctl, "%s", _("Unable to shrink current MemorySize"));
             ret = FALSE;
         }
+    }
 
     virDomainFree(dom);
     return ret;