With this in place, I can (finally!) now do:
virsh blockcommit $dom vda --shallow --wait --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!
* src/qemu/qemu_driver.c (qemuDomainBlockCommit): Implement live
commit to regular files.
Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
---
src/qemu/qemu_driver.c | 43 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 38 insertions(+), 5 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 728aa85..60dc9c6 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15529,9 +15529,11 @@ qemuDomainBlockCommit(virDomainPtr dom,
char *topPath = NULL;
char *basePath = NULL;
char *backingPath = NULL;
+ virStorageSourcePtr mirror = NULL;
- /* XXX Add support for COMMIT_ACTIVE, COMMIT_DELETE */
+ /* XXX Add support for COMMIT_DELETE */
virCheckFlags(VIR_DOMAIN_BLOCK_COMMIT_SHALLOW |
+ VIR_DOMAIN_BLOCK_COMMIT_ACTIVE |
VIR_DOMAIN_BLOCK_COMMIT_RELATIVE, -1);
if (!(vm = qemuDomObjFromDomain(dom)))
@@ -15578,13 +15580,14 @@ 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) {
/* We assume that no one will backport qemu 2.0 active commit
* to an earlier qemu without also backporting the block job
- * ready event; but this makes sure of that fact */
+ * ready event; but this makes sure of that fact.
+ *
+ * XXX Also need to check other capability bit(s): qemu 1.7
+ * supports async blockjob but not active commit; and qemu 2.0
+ * active commit misbehaves on 0-byte file. */
if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKJOB_ASYNC)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("active commit not supported with this QEMU binary"));
@@ -15597,6 +15600,14 @@ 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"),
@@ -15667,6 +15678,21 @@ qemuDomainBlockCommit(virDomainPtr dom,
}
}
+ /* 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
@@ -15678,6 +15704,12 @@ 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. */
@@ -15688,6 +15720,7 @@ qemuDomainBlockCommit(virDomainPtr dom,
top_parent,
VIR_DISK_CHAIN_READ_ONLY);
}
+ virStorageSourceFree(mirror);
if (!qemuDomainObjEndJob(driver, vm))
vm = NULL;
--
1.9.3
--
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