Bug 814102 - mirroring starts anyway with "existing" mode and a non-existing target
mirroring starts anyway with "existing" mode and a non-existing target
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: qemu-kvm (Show other bugs)
Unspecified Unspecified
urgent Severity medium
: rc
: ---
Assigned To: Jeff Cody
Virtualization Bugs
: ZStream
Depends On:
Blocks: 844627 861905 864962
  Show dependency treegraph
Reported: 2012-04-19 05:09 EDT by Shaolong Hu
Modified: 2013-02-21 08:07 EST (History)
13 users (show)

See Also:
Fixed In Version: qemu-kvm-
Doc Type: Bug Fix
Doc Text:
A mirroring operation set to "existing" mode was executed even when a target did not exist. Consequently, snapshot-related operations could not be performed because the block device was in use by the mirroring job. Now, a mirror block job is not created if the target bdrv_open() call fails, so mirroring does not start when the target does not exist.
Story Points: ---
Clone Of:
: 861905 (view as bug list)
Last Closed: 2013-02-21 08:07:34 EST
Type: Bug
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Shaolong Hu 2012-04-19 05:09:57 EDT
Description of problem:
mirroring with "existing" mode and a non-existing target starts anyway.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1.boot guest with QMP
2.in QMP connection, /root/sn1 does not exist:
{ "execute" : "__com.redhat_drive-mirror", "arguments" : { "device" : "drive-virtio-disk0", "target" : "/root/sn1", "format": "qcow2", "mode": "existing", "full" : false } }
3.mirror starts:
(qemu) info block-jobs
Type mirror, device drive-virtio-disk0: Completed 0 of 0 bytes, speed limit 0 bytes/s
(qemu) info block-jobs
Type mirror, device drive-virtio-disk0: Completed 0 of 0 bytes, speed limit 0 bytes/s
4.following snapshot related operation complains block device in use.
Comment 2 Jeff Cody 2012-05-29 13:49:23 EDT
I am able to partially reproduce this on qemu-kvm-  When I attempt to mirror to a non-existent target while in existing mode, I do get a valid error back:

{"error": {"class": "OpenFileFailed", "desc": "Could not open '/tmp/sn1'", "data": {"filename": "/tmp/sn1"}}}

However, I am still seeing item 4 from comment #1, when trying to subsequently perform a snapshot on the device:

{ "execute": "transaction", "arguments":
  {'actions': [
    { 'type': 'blockdev-snapshot-sync', 'data' :
      { 'device': 'virtio0', 'snapshot-file': '/tmp/f16-snap1.qcow2' } }
     ] } }

{"error": {"class": "DeviceInUse", "desc": "Device 'virtio0' is in use", "data": {"device": "virtio0"}}}
Comment 3 Jeff Cody 2012-05-30 14:55:38 EDT
The 'DeviceInUse' condition after a failed mirroring attempt happens because the block job is created (which sets the BDS to be 'in use'), but on failure of opening the BDS, the block job is not cleaned up.

The simple solution would be to just not start the block job if opening the BDS fails.
Comment 14 Shaolong Hu 2012-11-30 02:42:47 EST
Verified on qemu-kvm-rhev-

1.{ "execute": "qmp_capabilities" }
{"return": {}}

2.{ "execute": "__com.redhat_drive-mirror", "arguments": { "device": "drive-virtio-disk0", "target": "/root/sn1", "format": "qcow2", "mode": "existing" } }
{"error": {"class": "OpenFileFailed", "desc": "Could not open '/root/sn1': No such file or directory", "data": {"filename": "/root/sn1", "__com.redhat_error_message": "No such file or directory"}}}

3.{ "execute": "blockdev-snapshot-sync", "arguments": { "device": "drive-virtio-disk0", "snapshot-file": "/root/sn1", "format": "qcow2" } }
{"return": {}}

4.(qemu) info block
drive-virtio-disk0: removable=0 io-status=ok file=/root/sn1 backing_file=RHEL6.4 ro=0 drv=qcow2 encrypted=0
Comment 16 errata-xmlrpc 2013-02-21 08:07:34 EST
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.


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