Libvirt currently has trouble with pools built on dev mapper devices as the partition naming works a little differently.  This BZ is a dup of 593785.

*** This bug has been marked as a duplicate of bug 593785 ***

Bug 593785 is about volume creation on mapper device, this bug is about volume deletion operation, So they are different bug.

And I also re-tested this bug with libvirt-0.8.1-15.el6.x86_64 (Bug 593785 has been fixed on the -15 version), this issue still reproduced, so I reopened this bug.


# rpm -q libvirt
libvirt-0.8.1-15.el6.x86_64

# virsh pool-list --all
Name                 State      Autostart 
-----------------------------------------
default              active     yes       
xx                   active     no 

# virsh pool-dumpxml xx
<pool type='disk'>
  <name>xx</name>
  <uuid>ec1942d9-0bf3-7793-f46b-83cc839772fd</uuid>
  <capacity>42944186880</capacity>
  <allocation>1052803584</allocation>
  <available>41891351040</available>
  <source>
    <device path='/dev/mapper/mpatha'>
    <freeExtent start='1052835840' end='42944186880'/>
    </device>
    <format type='dos'/>
  </source>
  <target>
    <path>/dev</path>
    <permissions>
      <mode>0700</mode>
      <owner>-1</owner>
      <group>-1</group>
    </permissions>
  </target>
</pool>

# virsh vol-list xx
Name                 Path                                    
-----------------------------------------
mpathap1             /dev/mapper/mpathap1

# ll /dev/mapper/mpatha*
lrwxrwxrwx. 1 root root 7 Jul 15 12:51 /dev/mapper/mpatha -> ../dm-0
lrwxrwxrwx. 1 root root 7 Jul 15 12:51 /dev/mapper/mpathap1 -> ../dm-1

# virsh vol-delete --pool xx mpathap1
error: Failed to delete vol mpathap1
error: internal error Volume path 'dm-1' did not start with parent pool source device name.

Ok, fair enough; I'll look into it.

So, it turns out that it is essentially the same problem as the BZ I thought it was a dup of, but it is indeed a separate bug.  I'm working on a fix.

the problem is the logic of "virStorageBackendDiskDeleteVol" doesn't work for device mapper volume at all.


    devname = basename(devpath);
    srcname = basename(pool->def->source.devices[0].path);
    DEBUG("devname=%s, srcname=%s", devname, srcname);

    if (!STRPREFIX(devname, srcname)) {
        virStorageReportError(VIR_ERR_INTERNAL_ERROR,
                              _("Volume path '%s' did not start with parent "
                                "pool source device name '%s'."), devname,
                              srcname);
        goto cleanup;
    }

e.g. For jialiu's case:

devname = "dm-1"
srcname = "mpatha"

And the method to calculate partion number also not correct for a device mapper volume.

    part_num = devname + strlen(srcname);

Fortunately, we quit with the check before, we need a new logic for device mapper volume.

As you've noticed, the problem here is that the logic to calculate the partition number isn't correct when the underlying device is a dm device.  The logic I used in the create case is at:

https://www.redhat.com/archives/libvir-list/2010-July/msg00186.html

committed upstream as:

ae3275c0bb538e29eab840153ccc748cd5023cf7

http://post-office.corp.redhat.com/archives/rhvirt-patches/2011-February/msg01080.html

patch posted internally. move to POST.

Verified this bug PASS with libvirt-0.8.7-7.el6.x86_64
- kernel-2.6.32-113.el6.x86_64
- qemu-kvm-0.12.1.2-2.147.el6.x86_64

1. # cat xx.xml
<pool type='disk'>
  <name>xx</name>
  <source>
    <device path='/dev/mapper/mpathc'/>
  </source>
  <target>
    <path>/dev</path>
  </target>
</pool>
# virsh pool-create xx.xml
Pool xx created from xx.xml

2. # virsh vol-create-as --pool xx --name xx-1 --capacity 2G
Vol xx-1 created
# virsh vol-list xx
Name                 Path                                    
-----------------------------------------
xx-1                 /dev/mapper/mpathcp1 
# ll /dev/mapper/
total 0
crw-rw----. 1 root root  10, 58 Feb 21 13:11 control
lrwxrwxrwx. 1 root root       7 Feb 21 13:42 mpathb -> ../dm-1
lrwxrwxrwx. 1 root root       7 Feb 21 13:42 mpathc -> ../dm-0
brw-rw----. 1 root disk 253,  2 Feb 21 14:03 mpathcp1
# fdisk /dev/mapper/mpathc

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): p

Disk /dev/mapper/mpathc: 21.3 GB, 21346910208 bytes
23 heads, 16 sectors/track, 113296 cylinders
Units = cylinders of 368 * 512 = 188416 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000c1644

             Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpathcp1               1       11398     2097152   83  Linux

3. # virsh vol-delete /dev/mapper/mpathcp1 --pool xx
Vol /dev/mapper/mpathcp1 deleted

4. # virsh pool-list --all
Name                 State      Autostart 
-----------------------------------------
default              active     yes       
xx                   active     no 
# virsh vol-list xx
Name                 Path                                    
-----------------------------------------
# ll /dev/mapper/
total 0
crw-rw----. 1 root root 10, 58 Feb 21 13:11 control
lrwxrwxrwx. 1 root root      7 Feb 21 13:42 mpathb -> ../dm-1
lrwxrwxrwx. 1 root root      7 Feb 21 13:42 mpathc -> ../dm-0

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2011-0596.html