Re: [libvirt PATCH v4 3/4] qemu_migration: get migration blockers before hardcoded checks
On 7/20/22 12:05 PM, Eugenio Pérez wrote:
since qemu 6.0, if migration is blocked for some reason,
'query-migrate'
will return an array of error strings describing the migration blockers.
This can be used to check whether there are any devices blocking
migration, etc.
Enable qemuMigrationSrcIsAllowed to query it.
I reworded the commit log message a bit. Rather than repeating it here,
I'll just point you to the branch I pushed to gitlab (link in my
response to the cover letter).
Signed-off-by: Eugenio Pérez <eperezma(a)redhat.com>
Reviewed-by: Jiri Denemark <jdenemar(a)redhat.com>
---
v4:
* Do not override qemuDomainGetMigrationBlockers error calling again
virReportError.
* Replace ", " with "; " in blockers separators.
v3:
* Report message with a colon.
* Report all blockers instead of only the first.
---
src/qemu/qemu_migration.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index b12cb518ee..2e3044289a 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1414,6 +1414,20 @@ qemuMigrationSrcIsAllowedHostdev(const virDomainDef *def)
return true;
}
+static int
+qemuDomainGetMigrationBlockers(virQEMUDriver *driver,
+ virDomainObj *vm,
+ char ***blockers)
+{
+ qemuDomainObjPrivate *priv = vm->privateData;
+ int rc;
+
+ qemuDomainObjEnterMonitor(driver, vm);
+ rc = qemuMonitorGetMigrationBlockers(priv->mon, blockers);
+ qemuDomainObjExitMonitor(vm);
+
+ return rc;
+}
Note that we've been trying to keep 2 blank lines between each function,
but here you've added a new function in between those 2 blank lines, so
there's only a single blank before and after. I added in the extra blanks.
/**
* qemuMigrationSrcIsAllowed:
@@ -1439,6 +1453,22 @@ qemuMigrationSrcIsAllowed(virQEMUDriver *driver,
int nsnapshots;
int pauseReason;
size_t i;
+ int r;
+
+ /* Ask qemu if it have a migration blocker */
"has a migration blocker"
+ if (virQEMUCapsGet(priv->qemuCaps,
QEMU_CAPS_MIGRATION_BLOCKED_REASONS)) {
+ g_auto(GStrv) blockers = NULL;
+ r = qemuDomainGetMigrationBlockers(driver, vm, &blockers);
+ if (r != 0)
+ return false;
in libvirt we usually return -1 on failure, and check with "if (r < 0)".
And since that is the only use of "r", we prefer to not have the extra
stack variable cluttering things up, so:
if (qemuDomainGetMigrationBlockers(driver, vm, &blockers) < 0)
return false;
+
+ if (blockers && blockers[0]) {
+ g_autofree char *reasons = g_strjoinv("; ", blockers);
+ virReportError(VIR_ERR_OPERATION_INVALID,
+ _("cannot migrate domain: %s"), reasons);
+ return false;
+ }
+ }
/* perform these checks only when migrating to remote hosts */
if (remote) {