On 10/13/2012 06:00 PM, Eric Blake wrote:
> This is the bare minimum to kick off a block commit. In particular,
> flags support is missing (shallow requires us to crawl the backing
> chain to determine the file name to pass to the qemu monitor command;
> delete requires us to track what needs to be deleted at the time
> the completion event fires). Also, we are relying on qemu to do
> error checking (such as validating 'top' and 'base' as being members
> of the backing chain), including the fact that the current qemu code
> does not support committing the active layer (although it is still
> planned to add that before qemu 1.3). Since the active layer won't
> change, we have it easy and do not have to alter the domain XML.
> Additionally, this will fail if SELinux is enforcing, because we fail
> to grant qemu proper read/write access to the files it will modify.
>
> * src/qemu/qemu_driver.c (qemuDomainBlockCommit): New function.
> (qemuDriver): Register it.
> ---
>
> Change from v1:
> allow NULL top (let qemu reject it instead)
> drop unused event variable
>
> src/qemu/qemu_driver.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 75 insertions(+)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 6588b82..a9fd93a 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -12540,6 +12540,80 @@ qemuDomainBlockPull(virDomainPtr dom, const char *path, unsigned long bandwidth,
> return qemuDomainBlockRebase(dom, path, NULL, bandwidth, flags);
> }
>
> +
> +static int
> +qemuDomainBlockCommit(virDomainPtr dom, const char *path, const char *base,
> + const char *top, unsigned long bandwidth,
> + unsigned int flags)
> +{
> + struct qemud_driver *driver = dom->conn->privateData;
> + qemuDomainObjPrivatePtr priv;
> + virDomainObjPtr vm = NULL;
> + char *device = NULL;
> + int ret = -1;
> + int idx;
> + virDomainDiskDefPtr disk;
> +
> + virCheckFlags(0, -1);
> +
> + if (!(vm = qemuDomObjFromDomain(dom)))
> + goto cleanup;
> + priv = vm->privateData;
> +
> + if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
> + goto cleanup;
> +
> + if (!virDomainObjIsActive(vm)) {
> + virReportError(VIR_ERR_OPERATION_INVALID,
> + "%s", _("domain is not running"));
> + goto endjob;
> + }
> + if (!qemuCapsGet(priv->caps, QEMU_CAPS_BLOCK_COMMIT)) {
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> + _("online commit not supported with this QEMU binary"));
> + goto endjob;
> + }
> +
> + device = qemuDiskPathToAlias(vm, path, &idx);
> + if (!device)
> + goto endjob;
> + disk = vm->def->disks[idx];
> +
> + if (!disk->src) {
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> + _("disk %s has no source file to be committed"),
> + disk->dst);
> + goto endjob;
> + }
> +
> + if (!top)
> + top = disk->src;
> +
> + /* XXX For now, we are relying on qemu to check that 'top' and
> + * 'base' resolve to members of the backing chain in correct
> + * order; but if we ever get more paranoid and track the backing
> + * chain ourself, we should be pre-validating the data rather than
> + * relying on qemu. For that matter, we need to be changing the
> + * SELinux label on both 'base' and the parent of 'top', so that
> + * qemu can open(O_RDWR) those files for the duration of the
> + * commit. */
> + qemuDomainObjEnterMonitor(driver, vm);
> + ret = qemuMonitorBlockCommit(priv->mon, device, top, base, bandwidth);
> + qemuDomainObjExitMonitor(driver, vm);
> +
> +endjob:
> + if (qemuDomainObjEndJob(driver, vm) == 0) {
> + vm = NULL;
> + goto cleanup;
> + }
> +
> +cleanup:
> + VIR_FREE(device);
> + if (vm)
> + virDomainObjUnlock(vm);
> + return ret;
> +}
> +
> static int
> qemuDomainOpenGraphics(virDomainPtr dom,
> unsigned int idx,
> @@ -13882,6 +13956,7 @@ static virDriver qemuDriver = {
> .domainBlockJobSetSpeed = qemuDomainBlockJobSetSpeed, /* 0.9.4 */
> .domainBlockPull = qemuDomainBlockPull, /* 0.9.4 */
> .domainBlockRebase = qemuDomainBlockRebase, /* 0.9.10 */
> + .domainBlockCommit = qemuDomainBlockCommit, /* 0.10.3 */
> .isAlive = qemuIsAlive, /* 0.9.8 */
> .nodeSuspendForDuration = nodeSuspendForDuration, /* 0.9.8 */
> .domainSetBlockIoTune = qemuDomainSetBlockIoTune, /* 0.9.8 */
ACK (with the version change you've already said you would make).
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