Re: [libvirt] [PATCH v3 0/4] Allow to make disk optional on migration

This is a 3rd version of patches [1]. Diff to v2 includes Daniel's review and some other improvements. The aim of these patches is to mark CDROM and floppy optional, thus they might get dropped during migration, domain startup, restore, etc. The granularity is set on disk level, so user can decide which cd-roms are important and which not. There are 3 levels of optionality: - mandatory - fail if missing for any reason (the default) - requisite - fail if missing on boot up, drop if missing on migrate/restore/revert - optional - drop if missing at any start attempt. To assign a disk one of these, just append 'on_missing' attribute to its <source>. If a domain is then eventually started (migrated, restored, whatever), we check for source path being accessible (currently only qemu driver is supported) from hypervisor's POV. This is done by virFileAccessibleAs() function. Currently, only uid+gid are considered. Ideally, this should be extended to SElinux labeling and cgroups. 1: https://www.redhat.com/archives/libvir-list/2011-October/msg00032.html Michal Privoznik (4): conf: Introduce optional on_missing attribute for cdrom and floppy util: Create virFileAccessibleAs function qemu: implement on_missing on_missing: Emit event on disk source dropping daemon/remote.c | 37 ++++++++++ docs/formatdomain.html.in | 26 ++++++- docs/schemas/domaincommon.rng | 22 +++++- examples/domain-events/events-c/event-test.c | 27 +++++++- examples/domain-events/events-python/event-test.py | 4 + include/libvirt/libvirt.h.in | 28 +++++++ python/libvirt-override-virConnect.py | 9 +++ python/libvirt-override.c | 51 +++++++++++++ src/conf/domain_conf.c | 43 ++++++++++- src/conf/domain_conf.h | 11 +++ src/conf/domain_event.c | 50 +++++++++++++ src/conf/domain_event.h | 7 ++ src/libvirt_private.syms | 4 + src/qemu/qemu_domain.c | 73 +++++++++++++++++++ src/qemu/qemu_domain.h | 4 + src/qemu/qemu_process.c | 4 + src/remote/remote_driver.c | 34 +++++++++ src/remote/remote_protocol.x | 9 ++- src/remote_protocol-structs | 5 ++ src/util/util.c | 76 ++++++++++++++++++++ src/util/util.h | 3 + .../qemuxml2xmlout-disk-cdrom-empty.xml | 31 ++++++++ 22 files changed, 548 insertions(+), 10 deletions(-) create mode 100644 tests/qemuxml2xmloutdata/qemuxml2xmlout-disk-cdrom-empty.xml