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save: support qemu modifying xml on domain save/restore 

With this, it is possible to update the path to a disk backing
image on either the save or restore action, without having to
binary edit the XML embedded in the state file.

This also modifies virDomainSave to output a smaller xml (only
the inactive xml, which is all the more virDomainRestore parses),
while still guaranteeing padding for most typical abi-compatible
xml replacements, necessary so that the next patch for
virDomainSaveImageDefineXML will not cause unnecessary
modifications to the save image file.

* src/qemu/qemu_driver.c (qemuDomainSaveInternal): Add parameter,
only use inactive state, and guarantee padding.
(qemuDomainSaveImageOpen): Add parameter.
(qemuDomainSaveFlags, qemuDomainManagedSave)
(qemuDomainRestoreFlags, qemuDomainObjRestore): Update callers.
This commit is contained in:
Eric Blake 2011-07-18 17:27:59 -06:00
parent ff81956ac6
commit 0ea479f8f6
1 changed files with 68 additions and 42 deletions
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110
src/qemu/qemu_driver.c
View File

@ -2194,7 +2194,7 @@ qemuCompressProgramName(int compress)
static int
qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
virDomainObjPtr vm, const char *path,
int compressed, bool bypass_cache)
int compressed, bool bypass_cache, const char *xmlin)
{
char *xml = NULL;
struct qemud_save_header header;
@ -2205,7 +2205,9 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
qemuDomainObjPrivatePtr priv;
struct stat sb;
bool is_reg = false;
size_t len;
unsigned long long offset;
unsigned long long pad;
int fd = -1;
uid_t uid = getuid();
gid_t gid = getgid();
@ -2240,15 +2242,55 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
}
}
/* Get XML for the domain */
xml = virDomainDefFormat(vm->def, VIR_DOMAIN_XML_SECURE);
/* Get XML for the domain. Restore needs only the inactive xml,
* including secure. We should get the same result whether xmlin
* is NULL or whether it was the live xml of the domain moments
* before. */
if (xmlin) {
virDomainDefPtr def = NULL;
if (!(def = virDomainDefParseString(driver->caps, xmlin,
QEMU_EXPECTED_VIRT_TYPES,
VIR_DOMAIN_XML_INACTIVE))) {
goto endjob;
}
if (!virDomainDefCheckABIStability(vm->def, def)) {
virDomainDefFree(def);
goto endjob;
}
xml = virDomainDefFormat(def, (VIR_DOMAIN_XML_INACTIVE |
VIR_DOMAIN_XML_SECURE));
} else {
xml = virDomainDefFormat(vm->def, (VIR_DOMAIN_XML_INACTIVE |
VIR_DOMAIN_XML_SECURE));
}
if (!xml) {
qemuReportError(VIR_ERR_OPERATION_FAILED,
"%s", _("failed to get domain xml"));
goto endjob;
}
header.xml_len = strlen(xml) + 1;
len = strlen(xml) + 1;
offset = sizeof(header) + len;
/* Due to way we append QEMU state on our header with dd,
* we need to ensure there's a 512 byte boundary. Unfortunately
* we don't have an explicit offset in the header, so we fake
* it by padding the XML string with NUL bytes. Additionally,
* we want to ensure that virDomainSaveImageDefineXML can supply
* slightly larger XML, so we add a miminum padding prior to
* rounding out to page boundaries.
*/
pad = 1024;
pad += (QEMU_MONITOR_MIGRATE_TO_FILE_BS -
((offset + pad) % QEMU_MONITOR_MIGRATE_TO_FILE_BS));
if (VIR_EXPAND_N(xml, len, pad) < 0) {
virReportOOMError();
goto endjob;
}
offset += pad;
header.xml_len = len;
/* Obtain the file handle. */
/* path might be a pre-existing block dev, in which case
* we need to skip the create step, and also avoid unlink
* in the failure case */
@ -2269,29 +2311,6 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
}
}
offset = sizeof(header) + header.xml_len;
/* Due to way we append QEMU state on our header with dd,
* we need to ensure there's a 512 byte boundary. Unfortunately
* we don't have an explicit offset in the header, so we fake
* it by padding the XML string with NULLs.
*/
if (offset % QEMU_MONITOR_MIGRATE_TO_FILE_BS) {
unsigned long long pad =
QEMU_MONITOR_MIGRATE_TO_FILE_BS -
(offset % QEMU_MONITOR_MIGRATE_TO_FILE_BS);
if (VIR_REALLOC_N(xml, header.xml_len + pad) < 0) {
virReportOOMError();
goto endjob;
}
memset(xml + header.xml_len, 0, pad);
offset += pad;
header.xml_len += pad;
}
/* Obtain the file handle. */
/* First try creating the file as root */
if (bypass_cache) {
directFlag = virFileDirectFdFlag();
@ -2462,11 +2481,6 @@ qemuDomainSaveFlags(virDomainPtr dom, const char *path, const char *dxml,
virDomainObjPtr vm = NULL;
virCheckFlags(VIR_DOMAIN_SAVE_BYPASS_CACHE, -1);
if (dxml) {
qemuReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
_("xml modification unsupported"));
return -1;
}
qemuDriverLock(driver);
@ -2504,7 +2518,8 @@ qemuDomainSaveFlags(virDomainPtr dom, const char *path, const char *dxml,
}
ret = qemuDomainSaveInternal(driver, dom, vm, path, compressed,
(flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0);
(flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0,
dxml);
vm = NULL;
cleanup:
@ -2568,7 +2583,8 @@ qemuDomainManagedSave(virDomainPtr dom, unsigned int flags)
compressed = QEMUD_SAVE_FORMAT_RAW;
ret = qemuDomainSaveInternal(driver, dom, vm, name, compressed,
(flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0);
(flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0,
NULL);
vm = NULL;
cleanup:
@ -3711,7 +3727,8 @@ qemuDomainSaveImageOpen(struct qemud_driver *driver,
const char *path,
virDomainDefPtr *ret_def,
struct qemud_save_header *ret_header,
bool bypass_cache, virFileDirectFdPtr *directFd)
bool bypass_cache, virFileDirectFdPtr *directFd,
const char *xmlin)
{
int fd;
struct qemud_save_header header;
@ -3795,6 +3812,20 @@ qemuDomainSaveImageOpen(struct qemud_driver *driver,
QEMU_EXPECTED_VIRT_TYPES,
VIR_DOMAIN_XML_INACTIVE)))
goto error;
if (xmlin) {
virDomainDefPtr def2 = NULL;
if (!(def2 = virDomainDefParseString(driver->caps, xmlin,
QEMU_EXPECTED_VIRT_TYPES,
VIR_DOMAIN_XML_INACTIVE)))
goto error;
if (!virDomainDefCheckABIStability(def, def2)) {
virDomainDefFree(def2);
goto error;
}
virDomainDefFree(def);
def = def2;
}
VIR_FREE(xml);
@ -3929,17 +3960,12 @@ qemuDomainRestoreFlags(virConnectPtr conn,
virFileDirectFdPtr directFd = NULL;
virCheckFlags(VIR_DOMAIN_SAVE_BYPASS_CACHE, -1);
if (dxml) {
qemuReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
_("xml modification unsupported"));
return -1;
}
qemuDriverLock(driver);
fd = qemuDomainSaveImageOpen(driver, path, &def, &header,
(flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0,
&directFd);
&directFd, dxml);
if (fd < 0)
goto cleanup;
@ -3999,7 +4025,7 @@ qemuDomainObjRestore(virConnectPtr conn,
virFileDirectFdPtr directFd = NULL;
fd = qemuDomainSaveImageOpen(driver, path, &def, &header,
bypass_cache, &directFd);
bypass_cache, &directFd, NULL);
if (fd < 0)
goto cleanup;