On Thu, Jul 09, 2009 at 07:24:11PM +0200, Paolo Bonzini wrote:
> This patch uses a "migrate"+"cont" combination to implement "virsh dump"
> for QEMU guests (BZ507551).
>
> The code is mostly based on qemudDomainSave, except that the XML
> prolog is not included as it is not needed to examine the dump
> with e.g. crash.
Does crash actually understand the QEMU migrate data format ? I'm
rather (pleasantly) surprised if it does ...
> 2009-07-08 Paolo Bonzini <bonzini@xxxxxxx>
>
> * qemu_driver.c (qemudDomainCoreDump): New.
> (qemuDriver): Add core dump function.
> ---
> src/qemu_driver.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 84 insertions(+), 1 deletions(-)
>
> diff --git a/src/qemu_driver.c b/src/qemu_driver.c
> index 95ea882..546a691 100644
> --- a/src/qemu_driver.c
> +++ b/src/qemu_driver.c
> @@ -2844,6 +2844,89 @@ cleanup:
> }
>
>
> +static int qemudDomainCoreDump(virDomainPtr dom,
> + const char *path,
> + int flags ATTRIBUTE_UNUSED) {
> + struct qemud_driver *driver = dom->conn->privateData;
> + virDomainObjPtr vm;
> + char *command = NULL;
> + char *info = NULL;
> + char *safe_path = NULL;
> + int ret = -1;
> +
> + qemuDriverLock(driver);
> + vm = virDomainFindByUUID(&driver->domains, dom->uuid);
Since you don't touch 'driver' again after this point you can safely
unlock it right here. This avoids blocking the whole QEMU driver
while the dump is taking place
> +
> + if (!vm) {
> + char uuidstr[VIR_UUID_STRING_BUFLEN];
> + virUUIDFormat(dom->uuid, uuidstr);
> + qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_DOMAIN,
> + _("no domain with matching uuid '%s'"), uuidstr);
> + goto cleanup;
> + }
> +
> + if (!virDomainIsActive(vm)) {
> + qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_INVALID,
> + "%s", _("domain is not running"));
> + goto cleanup;
> + }
> +
> + /* Migrate to file */
> + safe_path = qemudEscapeShellArg(path);
> + if (!safe_path) {
> + virReportOOMError(dom->conn);
> + goto cleanup;
> + }
> + if (virAsprintf(&command, "migrate \"exec:"
> + "dd of='%s' 2>/dev/null"
> + "\"", safe_path) == -1) {
> + virReportOOMError(dom->conn);
> + command = NULL;
> + goto cleanup;
> + }
> +
> + if (qemudMonitorCommand(vm, command, &info) < 0) {
> + qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
> + "%s", _("migrate operation failed"));
> + goto cleanup;
> + }
> +
> + DEBUG ("%s: migrate reply: %s", vm->def->name, info);
> +
> + /* If the command isn't supported then qemu prints:
> + * unknown command: migrate" */
> + if (strstr(info, "unknown command:")) {
> + qemudReportError (dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT,
> + "%s",
> + _("'migrate' not supported by this qemu"));
> + goto cleanup;
> + }
> +
> + /* Migrate always stops the VM. However, since the monitor is always
> + attached to a pty for libvirt, it will support synchronous
> + operations so we get here just after the end of the migration. */
> + if (vm->state == VIR_DOMAIN_RUNNING) {
> + if (qemudMonitorCommand(vm, "cont", &info) < 0) {
> + qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
> + "%s", _("continue operation failed"));
> + goto cleanup;
> + }
> + DEBUG("Reply %s", info);
> + VIR_FREE(info);
> + }
> + ret = 0;
> +
> +cleanup:
> + VIR_FREE(safe_path);
> + VIR_FREE(command);
> + VIR_FREE(info);
> + if (vm)
> + virDomainObjUnlock(vm);
> + qemuDriverUnlock(driver);
> + return ret;
> +}
> +
> +
> static int qemudDomainSetVcpus(virDomainPtr dom, unsigned int nvcpus) {
> struct qemud_driver *driver = dom->conn->privateData;
> virDomainObjPtr vm;
> @@ -5310,7 +5393,7 @@ static virDriver qemuDriver = {
> qemudDomainGetInfo, /* domainGetInfo */
> qemudDomainSave, /* domainSave */
> qemudDomainRestore, /* domainRestore */
> - NULL, /* domainCoreDump */
> + qemudDomainCoreDump, /* domainCoreDump */
> qemudDomainSetVcpus, /* domainSetVcpus */
> #if HAVE_SCHED_GETAFFINITY
> qemudDomainPinVcpu, /* domainPinVcpu */
ACK, only a minor locking optimization needed
Daniel
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