libvirt users - Oct 2011 - delete lvm problem: exited with non-zero status 5 and signal 0

hi,
 I use the libvirt-python to manage my virtual machine. When I delete a
volume use vol.delete(0), sometimes it note me that has occur the error:

                libvirtError: internal error '/sbin/lvremove
                -f /dev/vg.vmms/lvm-v097222.sqa.cm4' exited with
                non-zero status 5 and signal 0:   Can't remove open
                logical volume "lvm-v097222.sqa.cm4".

 then I go to the host and run the command:
        " sudo lvchange -a n /dev/vg.vmms/lvm-v097222.sqa.cm4"
 and then the volume could delete use vol.delete(0).

But it's not often occur, just once in nearly 8.

I know the delete function virStorageBackendLogicalDeleteVol as this:
{
    {
        const char *cmdargv[] = {
            LVREMOVE, "-f",vol->target.path, NULL
        };

    virCheckFlags(0, -1);

    virFileWaitForDevices();

    if (virRun(cmdargv, NULL) < 0)
        return -1;

    return 0;
}

Could I change it like this: ?
        if (virRun(cmdargv, NULL) < 0)
        const char *changeCmdarg[] = {
         LVCHANGE, "-a", "n", vol->target.path, NULL
        };
        if(virRun(changeCmdarg, NULL) < 0)
            return -1;
        else
            if(virRun(cmdargv,NULL) < 0)
                return -1;



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On 10/27/2011 01:21 AM, lingjiao.lc wrote:
> hi,
>   I use the libvirt-python to manage my virtual machine. When I delete a
> volume use vol.delete(0), sometimes it note me that has occur the error:
>
>                  libvirtError: internal error '/sbin/lvremove
>                  -f /dev/vg.vmms/lvm-v097222.sqa.cm4' exited with
>                  non-zero status 5 and signal 0:   Can't remove open
>                  logical volume "lvm-v097222.sqa.cm4".
>
>
> Could I change it like this: ?
>          if (virRun(cmdargv, NULL)<  0)
>          const char *changeCmdarg[] = {
>           LVCHANGE, "-a", "n", vol->target.path,
NULL
>          };
>          if(virRun(changeCmdarg, NULL)<  0)
>              return -1;
>          else
>              if(virRun(cmdargv,NULL)<  0)
>                  return -1;
Changing it like that won't work - virRun fails with -1 if the command 
exits with non-zero status when the second argument is NULL.  But if you 
pass a pointer to an int on the first call, to capture (and ignore) the 
exit status of the first command, then you could get to the second call.

That said, does calling the change command twice, with no sleep in 
between, actually improve the situation?  The problem is that there is 
an inherent race in LVM operations, so we have to have a reliable way to 
tell when the race window is passed.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org