- fix disk usage monitoring

- try to stop background build script monitor in a clean way

build

@@ -605,7 +605,7 @@ vm_img_mkfs()
 
 background_monitor_process()
 {
-  max=0
+  max_disk=0
   max_mem=0
   while sleep 5; do
 
@@ -630,14 +630,16 @@ background_monitor_process()
     fi
 
     # disk storage usage
-    if [ -x /usr/bin/df ]; then
-      c=(`/usr/bin/df -m $1 | tail -n 1`)
+    if type -p df >& /dev/null; then
+      c=(`df -m / | tail -n 1`)
 
-      if [ ${c[2]} -gt $max ]; then
-        max="${c[2]}"
-        echo -n $max > /.build/_statistics.df
+      if [ ${c[2]} -gt $max_disk ]; then
+        max_disk="${c[2]}"
+        echo -n $max_disk > /.build/_statistics.df
       fi
     fi
+
+    [ -e /.build/_statistics.exit ] && exit 0
   done
 }
 
@@ -697,7 +699,7 @@ detect_vm_2nd_stage()
     HOST="$MYHOSTNAME"
 
     # fork a process monitoring max filesystem fillment during build
-    background_monitor_process / >& /dev/null &
+    background_monitor_process &
 
     return 0
 }
@@ -2291,6 +2293,10 @@ for SPECFILE in "${SPECFILES[@]}" ; do
     test -d "$SRCDIR" && cd "$SRCDIR"
 done
 
+if test -n "$RUNNING_IN_VM" -a -n "$VM_SWAP"; then
+    touch /.build/_statistics.exit
+fi
+
 RPMS=`find $BUILD_ROOT/$TOPDIR/RPMS -type f -name "*.rpm" 2>/dev/null || true`
 DEBS=`find $BUILD_ROOT/$TOPDIR/DEBS -type f -name "*.deb" 2>/dev/null || true`