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https://gitlab.com/libvirt/libvirt.git
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qemu: Split out domain memory saving code to allow reuse
The code that saves domain memory by migration to file can be reused while doing external checkpoints of a machine. This patch extracts the common code and places it in a separate function.
This commit is contained in:
Peter Krempa
parent
ec69ca14f9
commit
2771f8b74c
@ -2608,7 +2608,7 @@ bswap_header(struct qemud_save_header *hdr) {
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/* return -errno on failure, or 0 on success */
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static int
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qemuDomainSaveHeader(int fd, const char *path, char *xml,
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qemuDomainSaveHeader(int fd, const char *path, const char *xml,
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struct qemud_save_header *header)
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{
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int ret = 0;
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@ -2755,6 +2755,130 @@ cleanup:
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return fd;
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}
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/* Helper function to execute a migration to file with a correct save header
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* the caller needs to make sure that the processors are stopped and do all other
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* actions besides saving memory */
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static int
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qemuDomainSaveMemory(struct qemud_driver *driver,
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virDomainObjPtr vm,
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const char *path,
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const char *xml,
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int compressed,
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bool was_running,
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unsigned int flags,
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enum qemuDomainAsyncJob asyncJob)
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{
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struct qemud_save_header header;
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bool bypassSecurityDriver = false;
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bool needUnlink = false;
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int ret = -1;
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int fd = -1;
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int directFlag = 0;
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virFileWrapperFdPtr wrapperFd = NULL;
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unsigned int wrapperFlags = VIR_FILE_WRAPPER_NON_BLOCKING;
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unsigned long long pad;
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unsigned long long offset;
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size_t len;
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memset(&header, 0, sizeof(header));
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memcpy(header.magic, QEMUD_SAVE_PARTIAL, sizeof(header.magic));
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header.version = QEMUD_SAVE_VERSION;
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header.was_running = was_running ? 1 : 0;
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header.compressed = compressed;
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len = strlen(xml) + 1;
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offset = sizeof(header) + len;
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/* Due to way we append QEMU state on our header with dd,
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* we need to ensure there's a 512 byte boundary. Unfortunately
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* we don't have an explicit offset in the header, so we fake
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* it by padding the XML string with NUL bytes. Additionally,
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* we want to ensure that virDomainSaveImageDefineXML can supply
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* slightly larger XML, so we add a miminum padding prior to
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* rounding out to page boundaries.
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*/
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pad = 1024;
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pad += (QEMU_MONITOR_MIGRATE_TO_FILE_BS -
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((offset + pad) % QEMU_MONITOR_MIGRATE_TO_FILE_BS));
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if (VIR_EXPAND_N(xml, len, pad) < 0) {
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virReportOOMError();
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goto cleanup;
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}
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offset += pad;
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header.xml_len = len;
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/* Obtain the file handle. */
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if ((flags & VIR_DOMAIN_SAVE_BYPASS_CACHE)) {
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wrapperFlags |= VIR_FILE_WRAPPER_BYPASS_CACHE;
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directFlag = virFileDirectFdFlag();
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if (directFlag < 0) {
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virReportError(VIR_ERR_OPERATION_FAILED, "%s",
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_("bypass cache unsupported by this system"));
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goto cleanup;
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}
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}
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fd = qemuOpenFile(driver, path, O_WRONLY | O_TRUNC | O_CREAT | directFlag,
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&needUnlink, &bypassSecurityDriver);
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if (fd < 0)
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goto cleanup;
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if (!(wrapperFd = virFileWrapperFdNew(&fd, path, wrapperFlags)))
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goto cleanup;
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/* Write header to file, followed by XML */
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if (qemuDomainSaveHeader(fd, path, xml, &header) < 0)
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goto cleanup;
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/* Perform the migration */
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if (qemuMigrationToFile(driver, vm, fd, offset, path,
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qemuCompressProgramName(compressed),
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bypassSecurityDriver,
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asyncJob) < 0)
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goto cleanup;
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/* Touch up file header to mark image complete. */
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/* Reopen the file to touch up the header, since we aren't set
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* up to seek backwards on wrapperFd. The reopened fd will
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* trigger a single page of file system cache pollution, but
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* that's acceptable. */
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if (VIR_CLOSE(fd) < 0) {
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virReportSystemError(errno, _("unable to close %s"), path);
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goto cleanup;
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}
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if (virFileWrapperFdClose(wrapperFd) < 0)
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goto cleanup;
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if ((fd = qemuOpenFile(driver, path, O_WRONLY, NULL, NULL)) < 0)
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goto cleanup;
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memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
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if (safewrite(fd, &header, sizeof(header)) != sizeof(header)) {
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virReportSystemError(errno, _("unable to write %s"), path);
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goto cleanup;
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}
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if (VIR_CLOSE(fd) < 0) {
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virReportSystemError(errno, _("unable to close %s"), path);
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goto cleanup;
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}
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ret = 0;
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cleanup:
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VIR_FORCE_CLOSE(fd);
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virFileWrapperFdCatchError(wrapperFd);
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virFileWrapperFdFree(wrapperFd);
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if (ret != 0 && needUnlink)
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unlink(path);
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return ret;
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}
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/* This internal function expects the driver lock to already be held on
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* entry and the vm must be active + locked. Vm will be unlocked and
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* potentially free'd after this returns (eg transient VMs are freed
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@ -2767,20 +2891,11 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
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int compressed, const char *xmlin, unsigned int flags)
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{
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char *xml = NULL;
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struct qemud_save_header header;
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bool bypassSecurityDriver = false;
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bool was_running = false;
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int ret = -1;
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int rc;
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virDomainEventPtr event = NULL;
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qemuDomainObjPrivatePtr priv;
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bool needUnlink = false;
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size_t len;
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unsigned long long offset;
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unsigned long long pad;
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int fd = -1;
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int directFlag = 0;
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virFileWrapperFdPtr wrapperFd = NULL;
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unsigned int wrapperFlags = VIR_FILE_WRAPPER_NON_BLOCKING;
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qemuDomainObjPrivatePtr priv = vm->privateData;
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if (qemuProcessAutoDestroyActive(driver, vm)) {
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virReportError(VIR_ERR_OPERATION_INVALID,
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@ -2793,24 +2908,15 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
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goto cleanup;
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}
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memset(&header, 0, sizeof(header));
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memcpy(header.magic, QEMUD_SAVE_PARTIAL, sizeof(header.magic));
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header.version = QEMUD_SAVE_VERSION;
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header.compressed = compressed;
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priv = vm->privateData;
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if (qemuDomainObjBeginAsyncJobWithDriver(driver, vm,
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QEMU_ASYNC_JOB_SAVE) < 0)
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goto cleanup;
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memset(&priv->job.info, 0, sizeof(priv->job.info));
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priv->job.info.type = VIR_DOMAIN_JOB_UNBOUNDED;
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/* Pause */
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if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING) {
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header.was_running = 1;
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was_running = true;
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if (qemuProcessStopCPUs(driver, vm, VIR_DOMAIN_PAUSED_SAVE,
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QEMU_ASYNC_JOB_SAVE) < 0)
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goto endjob;
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@ -2821,11 +2927,12 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
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goto endjob;
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}
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}
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/* libvirt.c already guaranteed these two flags are exclusive. */
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/* libvirt.c already guaranteed these two flags are exclusive. */
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if (flags & VIR_DOMAIN_SAVE_RUNNING)
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header.was_running = 1;
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was_running = true;
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else if (flags & VIR_DOMAIN_SAVE_PAUSED)
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header.was_running = 0;
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was_running = false;
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/* Get XML for the domain. Restore needs only the inactive xml,
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* including secure. We should get the same result whether xmlin
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@ -2852,84 +2959,11 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
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"%s", _("failed to get domain xml"));
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goto endjob;
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}
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len = strlen(xml) + 1;
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offset = sizeof(header) + len;
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/* Due to way we append QEMU state on our header with dd,
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* we need to ensure there's a 512 byte boundary. Unfortunately
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* we don't have an explicit offset in the header, so we fake
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* it by padding the XML string with NUL bytes. Additionally,
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* we want to ensure that virDomainSaveImageDefineXML can supply
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* slightly larger XML, so we add a miminum padding prior to
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* rounding out to page boundaries.
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*/
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pad = 1024;
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pad += (QEMU_MONITOR_MIGRATE_TO_FILE_BS -
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((offset + pad) % QEMU_MONITOR_MIGRATE_TO_FILE_BS));
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if (VIR_EXPAND_N(xml, len, pad) < 0) {
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virReportOOMError();
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ret = qemuDomainSaveMemory(driver, vm, path, xml, compressed,
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was_running, flags, QEMU_ASYNC_JOB_SAVE);
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if (ret < 0)
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goto endjob;
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}
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offset += pad;
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header.xml_len = len;
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/* Obtain the file handle. */
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if ((flags & VIR_DOMAIN_SAVE_BYPASS_CACHE)) {
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wrapperFlags |= VIR_FILE_WRAPPER_BYPASS_CACHE;
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directFlag = virFileDirectFdFlag();
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if (directFlag < 0) {
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virReportError(VIR_ERR_OPERATION_FAILED, "%s",
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_("bypass cache unsupported by this system"));
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goto cleanup;
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}
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}
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fd = qemuOpenFile(driver, path, O_WRONLY | O_TRUNC | O_CREAT | directFlag,
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&needUnlink, &bypassSecurityDriver);
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if (fd < 0)
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goto endjob;
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if (!(wrapperFd = virFileWrapperFdNew(&fd, path, wrapperFlags)))
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goto endjob;
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/* Write header to file, followed by XML */
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if (qemuDomainSaveHeader(fd, path, xml, &header) < 0) {
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VIR_FORCE_CLOSE(fd);
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goto endjob;
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}
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/* Perform the migration */
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if (qemuMigrationToFile(driver, vm, fd, offset, path,
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qemuCompressProgramName(compressed),
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bypassSecurityDriver,
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QEMU_ASYNC_JOB_SAVE) < 0)
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goto endjob;
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/* Touch up file header to mark image complete. */
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/* Reopen the file to touch up the header, since we aren't set
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* up to seek backwards on wrapperFd. The reopened fd will
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* trigger a single page of file system cache pollution, but
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* that's acceptable. */
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if (VIR_CLOSE(fd) < 0) {
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virReportSystemError(errno, _("unable to close %s"), path);
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goto endjob;
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}
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if (virFileWrapperFdClose(wrapperFd) < 0)
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goto endjob;
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fd = qemuOpenFile(driver, path, O_WRONLY, NULL, NULL);
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if (fd < 0)
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goto endjob;
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memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
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if (safewrite(fd, &header, sizeof(header)) != sizeof(header)) {
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virReportSystemError(errno, _("unable to write %s"), path);
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goto endjob;
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}
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if (VIR_CLOSE(fd) < 0) {
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virReportSystemError(errno, _("unable to close %s"), path);
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goto endjob;
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}
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ret = 0;
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/* Shut it down */
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qemuProcessStop(driver, vm, VIR_DOMAIN_SHUTOFF_SAVED, 0);
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@ -2946,25 +2980,20 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
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endjob:
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if (vm) {
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if (ret != 0) {
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if (header.was_running && virDomainObjIsActive(vm)) {
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if (was_running && virDomainObjIsActive(vm)) {
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rc = qemuProcessStartCPUs(driver, vm, dom->conn,
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VIR_DOMAIN_RUNNING_SAVE_CANCELED,
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QEMU_ASYNC_JOB_SAVE);
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if (rc < 0)
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VIR_WARN("Unable to resume guest CPUs after save failure");
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}
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virFileWrapperFdCatchError(wrapperFd);
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}
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if (qemuDomainObjEndAsyncJob(driver, vm) == 0)
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vm = NULL;
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}
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cleanup:
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VIR_FORCE_CLOSE(fd);
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virFileWrapperFdFree(wrapperFd);
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VIR_FREE(xml);
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if (ret != 0 && needUnlink)
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unlink(path);
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if (event)
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qemuDomainEventQueue(driver, event);
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if (vm)
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