[libvirt] [PATCHv5 03/13] qemu: allow simple domain save to use fd: protocol
This allows direct saves (no compression, no root-squash NFS) to use
the more efficient fd: migration, which in turn avoids a race where
qemu exec: migration can sometimes fail because qemu does a generic
waitpid() that conflicts with the pclose() used by exec:. Further
patches will solve compression and root-squash NFS.
* src/qemu/qemu_driver.c (qemudDomainSaveFlag): Use new function
when there is no compression.
---
v5: adjust earlier in the series
Note that this opens the fd a second time, but gracefully falls back
to the older exec: migration for things like root-squash NFS.
src/qemu/qemu_driver.c | 26 +++++++++++++++++++++++---
1 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index e0e86d3..8aa72f8 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -1823,6 +1823,7 @@ static int qemudDomainSaveFlag(struct qemud_driver *driver,
virDomainPtr dom,
int is_reg = 0;
unsigned long long offset;
virCgroupPtr cgroup = NULL;
+ virBitmapPtr qemuCaps = NULL;
memset(&header, 0, sizeof(header));
memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
@@ -1853,6 +1854,11 @@ static int qemudDomainSaveFlag(struct qemud_driver *driver,
virDomainPtr dom,
}
}
+ if (qemuCapsExtractVersionInfo(vm->def->emulator, vm->def->os.arch,
+ NULL,
+ &qemuCaps) < 0)
+ goto endjob;
+
/* Get XML for the domain */
xml = virDomainDefFormat(vm->def, VIR_DOMAIN_XML_SECURE);
if (!xml) {
@@ -2013,10 +2019,23 @@ static int qemudDomainSaveFlag(struct qemud_driver *driver,
virDomainPtr dom,
if (header.compressed == QEMUD_SAVE_FORMAT_RAW) {
const char *args[] = { "cat", NULL };
+ /* XXX gross - why don't we reuse the fd already opened earlier */
+ int fd = -1;
+
+ if (qemuCapsGet(qemuCaps, QEMU_CAPS_MIGRATE_QEMU_FD) &&
+ priv->monConfig->type == VIR_DOMAIN_CHR_TYPE_UNIX)
+ fd = open(path, O_WRONLY);
qemuDomainObjEnterMonitorWithDriver(driver, vm);
- rc = qemuMonitorMigrateToFile(priv->mon,
- QEMU_MONITOR_MIGRATE_BACKGROUND,
- args, path, offset);
+ if (fd >= 0 && lseek(fd, offset, SEEK_SET) == offset) {
+ rc = qemuMonitorMigrateToFd(priv->mon,
+ QEMU_MONITOR_MIGRATE_BACKGROUND,
+ fd);
+ } else {
+ rc = qemuMonitorMigrateToFile(priv->mon,
+ QEMU_MONITOR_MIGRATE_BACKGROUND,
+ args, path, offset);
+ }
+ VIR_FORCE_CLOSE(fd);
qemuDomainObjExitMonitorWithDriver(driver, vm);
} else {
const char *prog = qemudSaveCompressionTypeToString(header.compressed);
@@ -2099,6 +2118,7 @@ endjob:
}
cleanup:
+ qemuCapsFree(qemuCaps);
VIR_FREE(xml);
if (ret != 0 && is_reg)
unlink(path);
--
1.7.4