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Pavel Hrdina 8e66473781 qemu_snapshot: introduce external snapshot revert support
When reverting to external snapshot we need to create new overlay qcow2
files from the disk files the VM had when the snapshot was taken.

There are some specifics and limitations when reverting to a snapshot:

1) When reverting to last snapshot we need to first create new overlay
   files before we can safely delete the old overlay files in case the
   creation fails so we have still recovery option when we error out.

   These new files will not have the suffix as when the snapshot was
   created as renaming the original files in order to use the same file
   names as when the snapshot was created would add unnecessary
   complexity to the code.

2) When reverting to any snapshot we will always create overlay files
   for every disk the VM had when the snapshot was done. Otherwise we
   would have to figure out if there is any other qcow2 image already
   using any of the VM disks as backing store and that itself might be
   extremely complex and in some cases impossible.

3) When reverting from any state the current overlay files will be
   always removed as that VM state is not meant to be saved. It's the
   same as with internal snapshots. If user want's to keep the current
   state before reverting they need to create a new snapshot. For now
   this will only work if the current snapshot is the last.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
2023-08-22 16:06:20 +02:00
2019-05-31 17:54:28 +02:00
2023-04-06 12:48:22 +02:00
2023-03-13 13:29:07 +01:00
2023-08-17 23:21:13 +02:00
2019-09-06 12:47:46 +02:00
2022-03-17 14:33:12 +01:00
2020-01-16 13:04:11 +00:00
2020-08-03 09:26:48 +02:00
2019-10-18 17:32:52 +02:00
2015-06-16 13:46:20 +02:00
2023-08-01 11:49:29 +02:00
2020-08-03 15:08:28 +02:00

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==============================
Libvirt API for virtualization
==============================

Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.

For some of these hypervisors, it provides a stateful management
daemon which runs on the virtualization host allowing access to the
API both by non-privileged local users and remote users.

Layered packages provide bindings of the libvirt C API into other
languages including Python, Perl, PHP, Go, Java, OCaml, as well as
mappings into object systems such as GObject, CIM and SNMP.

Further information about the libvirt project can be found on the
website:

https://libvirt.org


License
=======

The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.0 (or later). See the files ``COPYING.LESSER``
and ``COPYING`` for full license terms & conditions.


Installation
============

Instructions on building and installing libvirt can be found on the website:

https://libvirt.org/compiling.html

Contributing
============

The libvirt project welcomes contributions in many ways. For most components
the best way to contribute is to send patches to the primary development
mailing list. Further guidance on this can be found on the website:

https://libvirt.org/contribute.html


Contact
=======

The libvirt project has two primary mailing lists:

* libvirt-users@redhat.com (**for user discussions**)
* libvir-list@redhat.com (**for development only**)

Further details on contacting the project are available on the website:

https://libvirt.org/contact.html
Description
Libvirt native C API and daemons
Readme 676 MiB
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