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Bug 1430679

Summary:	Increase the wipe of bytes when build a logical pool which already has a label on target volume device
Product:	Red Hat Enterprise Linux 7	Reporter:	Pei Zhang <pzhang>
Component:	libvirt	Assignee:	John Ferlan <jferlan>
Status:	CLOSED ERRATA	QA Contact:	yisun
Severity:	medium	Docs Contact:
Priority:	medium
Version:	7.4	CC:	dyuan, jferlan, lmen, rbalakri, xuzhang, yisun
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Unspecified
Whiteboard:
Fixed In Version:	libvirt-3.2.0-1.el7	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2017-08-01 17:24:15 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Pei Zhang 2017-03-09 09:50:28 UTC

Description of problem:
Refer to https://bugzilla.redhat.com/show_bug.cgi?id=1373711#c7

Version-Release number of selected component (if applicable):
libvirt-3.1.0-2.el7.x86_64
qemu-kvm-rhev-2.8.0-6.el7.x86_64

How reproducible:
100%

Steps to Reproduce:

1.check device label (ext2/ext3/ext4)
# blkid /dev/sdb 
/dev/sdb: UUID="393a7576-1b80-4f81-92e7-67871fd58e10" TYPE="ext4" 

2. define a logical pool as following:
# virsh pool-dumpxml logical
<pool type='logical'>
  <name>logical</name>
  <uuid>04e3685b-137b-4f13-8eec-31949a9ee9f5</uuid>
  <capacity unit='bytes'>0</capacity>
  <allocation unit='bytes'>0</allocation>
  <available unit='bytes'>0</available>
  <source>
    <device path='/dev/sdb'/>
    <name>logical</name>
    <format type='lvm2'/>
  </source>
  <target>
    <path>/dev/logical</path>
    <permissions>
      <mode>0755</mode>
    </permissions>
  </target>
</pool>

3.build pool with nothing.
# virsh pool-build logical
error: Failed to build pool logical
error: Storage pool already built: Format of device '/dev/sdb' does not match the expected format 'LVM2_member', forced overwrite is necessary

4. as above, build pool with --overwrite, it also fails to build.
# virsh pool-build logical --overwrite
error: Failed to build pool logical
error: internal error: Child process (/usr/sbin/pvcreate /dev/sdb) unexpected exit status 5: WARNING: ext4 signature detected on /dev/sdb at offset 1080. Wipe it? [y/n]: [n]
  Aborted wiping of ext4.
  1 existing signature left on the device.

5. test with other file systems such as xfs and vfat, repeat steps 1-3
then build pool with --overwrite, it can build successfully.

Actual results:
As step4, it fails to build pool with --overwrite.

Expected results:
Build pool successfullly with --overwrite.

Additional info:

As following, perhaps for existing file system ext2/3/4, it should wipe 1080+512 bytes.
1.pvcreate when target volume device has xfs label.

# parted /dev/sdb p
...
Number  Start  End     Size    File system  Flags
 1      0.00B  4008MB  4008MB  xfs

# pvcreate /dev/sdb 
WARNING: xfs signature detected on /dev/sdb at offset 0. Wipe it? [y/n]: n

2.pvcreate when target volume device has ext4 label.
# parted /dev/sdb p
...
Number  Start  End     Size    File system  Flags
 1      0.00B  4008MB  4008MB  ext4
# pvcreate /dev/sdb 
WARNING: ext4 signature detected on /dev/sdb at offset 1080. Wipe it? [y/n]: n

Comment 2 John Ferlan 2017-03-24 17:48:33 UTC

Posted a patch upstream:

http://www.redhat.com/archives/libvir-list/2017-March/msg01192.html

Comment 3 John Ferlan 2017-03-27 16:58:08 UTC

Pushed patch upstream:

commit 6760cc4bfddb84a8ab33e8b008c0440013c17499
Author: John Ferlan <jferlan>
Date:   Fri Mar 24 12:25:27 2017 -0400

    logical: Need to overwrite/clear more than just first 512 bytes

...

$ git describe 6760cc4bfddb84a8ab33e8b008c0440013c17499
v3.1.0-382-g6760cc4
$

Comment 5 yisun 2017-04-06 08:21:25 UTC

Verified with libvirt-3.2.0-1.el7.x86_64

Steps:
1. prepare a ext4 block device
## blkid /dev/sdf
/dev/sdf: UUID="62e6c23c-3ace-4029-b5ff-f62e1d4c2496" TYPE="ext4" 

2. prepare a logical pool xml
## cat pool.logical 
<pool type='logical'>
  <name>lpool</name>
  <capacity unit='bytes'>0</capacity>
  <allocation unit='bytes'>0</allocation>
  <available unit='bytes'>0</available>
  <source>
    <device path='/dev/sdf'/>
    <name>logical</name>
    <format type='lvm2'/>
  </source>
  <target>
    <path>/dev/ltest</path>
    <permissions>
      <mode>0755</mode>
    </permissions>
  </target>
</pool>

3. define the pool
## virsh pool-define pool.logical 
Pool lpool defined from pool.logical

4. build the pool without --overwrite
## virsh pool-build lpool
error: Failed to build pool lpool
error: Storage pool already built: Format of device '/dev/sdf' does not match the expected format 'LVM2_member', forced overwrite is necessary

5. build the pool with --overwrite
## virsh pool-build lpool --overwrite
Pool lpool built

6. start the pool
## virsh pool-start lpool
Pool lpool started

7. check the pool existing in pool list
## virsh pool-list | grep lpool
 lpool                active     no        

8. check the block device has correct type
## blkid /dev/sdf
/dev/sdf: UUID="9vfnr6-iLfl-WVLL-BBL8-9AIu-ewDA-ulQCbw" TYPE="LVM2_member"

Comment 6 errata-xmlrpc 2017-08-01 17:24:15 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2017:1846

Comment 7 errata-xmlrpc 2017-08-02 00:03:43 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2017:1846