From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [OSSTest Nested v12 20/21] Don't lvextend if
 actually no more space to extend
Date: Tue, 22 Sep 2015 16:56:14 +0100
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To: Ian Jackson <Ian.Jackson@eu.citrix.com>, Robert Ho <robert.hu@intel.com>
Cc: gordon.jin@intel.com, wei.liu2@citrix.com, di.zheng@intel.com, xen-devel@lists.xen.org
List-Id: xen-devel@lists.xenproject.org

On Wed, 2015-09-16 at 15:27 +0100, Ian Jackson wrote:
> Robert Ho writes ("[OSSTest Nested v12 20/21] Don't lvextend if actually
> no more space to extend"):
> > Though passes if judgement, the
> > 	overall_limit_pe(\$vg_more_free_pe);
> > may final judge no more free_pe to extend.
> > So, check if $vg_more_free_pe is 0, if so, we don't lvextend,
> > otherwise lvextend will report error on nonsense operation.
> 
> I think this should be done by moving the start of the if block to
> after overall_limit_pe.  That would avoid a tested if (and various
> other slight anomalies).

IOW move the overall_limit_pe outside the if? 

Like so:

diff --git a/ts-xen-build-prep b/ts-xen-build-prep
index 03ad35c..b35e91b 100755
--- a/ts-xen-build-prep
+++ b/ts-xen-build-prep
@@ -151,9 +151,9 @@ sub lvextend1 ($$$) {
 
     $do_limit_pe->(\$vg_more_free_pe, 'unstriped');
 
+    overall_limit_pe(\$vg_more_free_pe);
     if ($vg_more_free_pe) {
         logm("$what: unstriped $vg_more_free_pe PEs");
-        overall_limit_pe(\$vg_more_free_pe);
         $more_pe += $vg_more_free_pe;
         target_cmd_root($ho, "lvextend -i1 -l +$vg_more_free_pe $lv");
     }

(untested, but I've just tripped over this in a standalone run myself).

Ian.