[libvirt] [PATCH v3 5/5] blockcommit: turn on active commit
With this in place, I can (finally!) now do:
virsh blockcommit $dom vda --shallow --verbose --pivot
and watch qemu shorten the backing chain by one, followed by
libvirt automatically updating the dumpxml output, effectively
undoing the work of virsh snapshot-commit --no-metadata --disk-only.
Commit is SOOOO much faster than blockpull, when I'm still fairly
close in time to when the temporary qcow2 wrapper file was created
via a snapshot operation!
Still not done: the persistent XML is not updated; which means
stopping and restarting a persistent guest will use the wrong
file and likely fail to boot.
* src/qemu/qemu_driver.c (qemuDomainBlockCommit): Implement live
commit to regular files.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
src/qemu/qemu_driver.c | 40 +++++++++++++++++++++++++++++++++++-----
1 file changed, 35 insertions(+), 5 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index d19ca18..089668d 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15495,9 +15495,12 @@ qemuDomainBlockCommit(virDomainPtr dom,
unsigned int baseIndex = 0;
const char *top_parent = NULL;
bool clean_access = false;
+ virStorageSourcePtr mirror = NULL;
+
- /* XXX Add support for COMMIT_ACTIVE, COMMIT_DELETE */
- virCheckFlags(VIR_DOMAIN_BLOCK_COMMIT_SHALLOW, -1);
+ /* XXX Add support for COMMIT_DELETE */
+ virCheckFlags(VIR_DOMAIN_BLOCK_COMMIT_SHALLOW |
+ VIR_DOMAIN_BLOCK_COMMIT_ACTIVE, -1);
if (!(vm = qemuDomObjFromDomain(dom)))
goto cleanup;
@@ -15545,9 +15548,6 @@ qemuDomainBlockCommit(virDomainPtr dom,
&top_parent)))
goto endjob;
- /* FIXME: qemu 2.0 supports active commit, but as a two-stage
- * process; qemu 2.1 is further improving active commit. We need
- * to start supporting it in libvirt. */
if (topSource == disk->src) {
if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_ACTIVE_COMMIT)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
@@ -15561,6 +15561,14 @@ qemuDomainBlockCommit(virDomainPtr dom,
disk->dst);
goto endjob;
}
+ if (disk->mirror) {
+ virReportError(VIR_ERR_BLOCK_COPY_ACTIVE,
+ _("disk '%s' already in active block job"),
+ disk->dst);
+ goto endjob;
+ }
+ if (VIR_ALLOC(mirror) < 0)
+ goto endjob;
} else if (flags & VIR_DOMAIN_BLOCK_COMMIT_ACTIVE) {
virReportError(VIR_ERR_INVALID_ARG,
_("active commit requested but '%s' is not
active"),
@@ -15607,6 +15615,21 @@ qemuDomainBlockCommit(virDomainPtr dom,
VIR_DISK_CHAIN_READ_WRITE) < 0))
goto endjob;
+ /* For an active commit, clone enough of the base to act as the mirror */
+ if (mirror) {
+ /* XXX Support network commits */
+ if (baseSource->type != VIR_STORAGE_TYPE_FILE &&
+ baseSource->type != VIR_STORAGE_TYPE_BLOCK) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("active commit to non-file not supported yet"));
+ goto endjob;
+ }
+ mirror->type = baseSource->type;
+ if (VIR_STRDUP(mirror->path, baseSource->path) < 0)
+ goto endjob;
+ mirror->format = baseSource->format;
+ }
+
/* Start the commit operation. Pass the user's original spelling,
* if any, through to qemu, since qemu may behave differently
* depending on whether the input was specified as relative or
@@ -15619,6 +15642,12 @@ qemuDomainBlockCommit(virDomainPtr dom,
bandwidth);
qemuDomainObjExitMonitor(driver, vm);
+ if (ret == 0 && mirror) {
+ disk->mirror = mirror;
+ mirror = NULL;
+ disk->mirrorJob = VIR_DOMAIN_BLOCK_JOB_TYPE_ACTIVE_COMMIT;
+ }
+
endjob:
if (ret < 0 && clean_access) {
/* Revert access to read-only, if possible. */
@@ -15629,6 +15658,7 @@ qemuDomainBlockCommit(virDomainPtr dom,
top_parent,
VIR_DISK_CHAIN_READ_ONLY);
}
+ virStorageSourceFree(mirror);
if (!qemuDomainObjEndJob(driver, vm))
vm = NULL;
--
1.9.3