Bug 1671798 - Add facility to use block jobs with backing images without write permission
Summary: Add facility to use block jobs with backing images without write permission
Keywords:
Status: CLOSED DUPLICATE of bug 1717168
Alias: None
Product: Red Hat Enterprise Linux Advanced Virtualization
Classification: Red Hat
Component: qemu-kvm
Version: 8.1
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: 8.0
Assignee: Kevin Wolf
QA Contact: aihua liang
URL:
Whiteboard:
Depends On:
Blocks: 1685989
TreeView+ depends on / blocked
 
Reported: 2019-02-01 16:53 UTC by Peter Krempa
Modified: 2019-06-05 00:55 UTC (History)
6 users (show)

Fixed In Version:
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Clone Of:
: 1685989 (view as bug list)
Environment:
Last Closed: 2019-06-05 00:55:13 UTC
Type: Bug
Target Upstream Version:
Embargoed:


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Description Peter Krempa 2019-02-01 16:53:09 UTC
Description of problem:
When discussing the use of 'auto-read-only' property for use with -blockdev so that libvirt is able to use block jobs I forgot that sVirt labelling of the backing chain images actually forbids the write permission. [1]

This means that the 'auto-read-only' property works as expected and opens the images as read-only in this case. This unfortunately means that when libvirt attempts a block-commit which needs to write into the backing chain we relabel the image to allow write, but qemu will not reopen it any more.

This means that we unfortunately still need a way to control reopening of the images of the backing chain:
1) automatically by block-commit doing the right thing
2) manually by providing an interface to achieve that

Libvirt is relabeling the files anyways so 2) is also acceptable.

[1] Unfortunately it's very unpleasant to run a development git image of libvirt under full enforcing selinux, thus I neglected todo when testing 'auto-read-only'. I'm sorry for that.


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