Originally most of libvirt domain-specific calls were blocking
during a migration.
A new mechanism to allow specific calls (blkstat/blkinfo) to be
executed in such condition has been implemented.
In the long term it'd be desirable to get a more general
solution to mark further APIs as migration safe, without needing
special case code.
* src/qemu/qemu_migration.c: add some additional job signal
flags for doing blkstat/blkinfo during a migration
* src/qemu/qemu_domain.c: add a condition variable that can be
used to efficiently wait for the migration code to clear the
signal flag
* src/qemu/qemu_driver.c: execute blkstat/blkinfo using the
job signal flags during migration
---
src/qemu/qemu_domain.c | 6 +++
src/qemu/qemu_domain.h | 9 ++++
src/qemu/qemu_driver.c | 103 ++++++++++++++++++++++++++++++++-------------
src/qemu/qemu_migration.c | 35 +++++++++++++++
4 files changed, 123 insertions(+), 30 deletions(-)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index c61f9bf..570d65e 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -110,6 +110,11 @@ static void *qemuDomainObjPrivateAlloc(void)
if (VIR_ALLOC(priv) < 0)
return NULL;
+ if (virCondInit(&priv->signalCond) < 0) {
+ VIR_FREE(priv);
+ return NULL;
+ }
+
return priv;
}
@@ -122,6 +127,7 @@ static void qemuDomainObjPrivateFree(void *data)
qemuDomainPCIAddressSetFree(priv->pciaddrs);
virDomainChrSourceDefFree(priv->monConfig);
VIR_FREE(priv->vcpupids);
+ ignore_value(virCondDestroy(&priv->signalCond));
/* This should never be non-NULL if we get here, but just in case... */
if (priv->mon) {
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 6d24f53..af513e7 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -47,11 +47,19 @@ enum qemuDomainJobSignals {
QEMU_JOB_SIGNAL_SUSPEND = 1 << 1, /* Request VM suspend to finish live migration offline */
QEMU_JOB_SIGNAL_MIGRATE_DOWNTIME = 1 << 2, /* Request migration downtime change */
QEMU_JOB_SIGNAL_MIGRATE_SPEED = 1 << 3, /* Request migration speed change */
+ QEMU_JOB_SIGNAL_BLKSTAT = 1 << 4, /* Request blkstat during migration */
+ QEMU_JOB_SIGNAL_BLKINFO = 1 << 5, /* Request blkinfo during migration */
};
struct qemuDomainJobSignalsData {
unsigned long long migrateDowntime; /* Data for QEMU_JOB_SIGNAL_MIGRATE_DOWNTIME */
unsigned long migrateBandwidth; /* Data for QEMU_JOB_SIGNAL_MIGRATE_SPEED */
+ char *statDevName; /* Device name used by blkstat calls */
+ virDomainBlockStatsPtr blockStat; /* Block statistics for QEMU_JOB_SIGNAL_BLKSTAT */
+ int statRetCode; /* Return code for the blkstat calls */
+ char *infoDevName; /* Device name used by blkinfo calls */
+ virDomainBlockInfoPtr blockInfo; /* Block information for QEMU_JOB_SIGNAL_BLKINFO */
+ int infoRetCode; /* Return code for the blkinfo calls */
};
typedef struct _qemuDomainPCIAddressSet qemuDomainPCIAddressSet;
@@ -61,6 +69,7 @@ typedef struct _qemuDomainObjPrivate qemuDomainObjPrivate;
typedef qemuDomainObjPrivate *qemuDomainObjPrivatePtr;
struct _qemuDomainObjPrivate {
virCond jobCond; /* Use in conjunction with main virDomainObjPtr lock */
+ virCond signalCond; /* Use to coordinate the safe queries during migration */
enum qemuDomainJob jobActive; /* Currently running job */
unsigned int jobSignals; /* Signals for running job */
struct qemuDomainJobSignalsData jobSignalsData; /* Signal specific data */
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 4f288d3..f7b2cb4 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5082,15 +5082,6 @@ qemudDomainBlockStats (virDomainPtr dom,
goto cleanup;
}
- if (qemuDomainObjBeginJob(vm) < 0)
- goto cleanup;
-
- if (!virDomainObjIsActive(vm)) {
- qemuReportError(VIR_ERR_OPERATION_INVALID,
- "%s", _("domain is not running"));
- goto endjob;
- }
-
for (i = 0 ; i < vm->def->ndisks ; i++) {
if (STREQ(path, vm->def->disks[i]->dst)) {
disk = vm->def->disks[i];
@@ -5101,29 +5092,57 @@ qemudDomainBlockStats (virDomainPtr dom,
if (!disk) {
qemuReportError(VIR_ERR_INVALID_ARG,
_("invalid path: %s"), path);
- goto endjob;
+ goto cleanup;
}
if (!disk->info.alias) {
qemuReportError(VIR_ERR_INTERNAL_ERROR,
_("missing disk device alias name for %s"), disk->dst);
- goto endjob;
+ goto cleanup;
}
priv = vm->privateData;
- qemuDomainObjEnterMonitor(vm);
- ret = qemuMonitorGetBlockStatsInfo(priv->mon,
- disk->info.alias,
- &stats->rd_req,
- &stats->rd_bytes,
- &stats->wr_req,
- &stats->wr_bytes,
- &stats->errs);
- qemuDomainObjExitMonitor(vm);
+ if ((priv->jobActive == QEMU_JOB_MIGRATION_OUT)
+ || (priv->jobActive == QEMU_JOB_SAVE)) {
+ virDomainObjRef(vm);
+ while (priv->jobSignals & QEMU_JOB_SIGNAL_BLKSTAT)
+ ignore_value(virCondWait(&priv->signalCond, &vm->lock));
+
+ priv->jobSignals |= QEMU_JOB_SIGNAL_BLKSTAT;
+ priv->jobSignalsData.statDevName = disk->info.alias;
+ priv->jobSignalsData.blockStat = stats;
+ priv->jobSignalsData.statRetCode = -1;
+
+ while (priv->jobSignals & QEMU_JOB_SIGNAL_BLKSTAT)
+ ignore_value(virCondWait(&priv->signalCond, &vm->lock));
+
+ ret = priv->jobSignalsData.statRetCode;
+ if (virDomainObjUnref(vm) == 0)
+ vm = NULL;
+ } else {
+ if (qemuDomainObjBeginJob(vm) < 0)
+ goto cleanup;
+
+ if (!virDomainObjIsActive(vm)) {
+ qemuReportError(VIR_ERR_OPERATION_INVALID,
+ "%s", _("domain is not running"));
+ goto endjob;
+ }
+
+ qemuDomainObjEnterMonitor(vm);
+ ret = qemuMonitorGetBlockStatsInfo(priv->mon,
+ disk->info.alias,
+ &stats->rd_req,
+ &stats->rd_bytes,
+ &stats->wr_req,
+ &stats->wr_bytes,
+ &stats->errs);
+ qemuDomainObjExitMonitor(vm);
endjob:
- if (qemuDomainObjEndJob(vm) == 0)
- vm = NULL;
+ if (qemuDomainObjEndJob(vm) == 0)
+ vm = NULL;
+ }
cleanup:
if (vm)
@@ -5527,20 +5546,44 @@ static int qemuDomainGetBlockInfo(virDomainPtr dom,
format != VIR_STORAGE_FILE_RAW &&
S_ISBLK(sb.st_mode)) {
qemuDomainObjPrivatePtr priv = vm->privateData;
- if (qemuDomainObjBeginJob(vm) < 0)
- goto cleanup;
- if (!virDomainObjIsActive(vm))
- ret = 0;
- else {
+
+ if ((priv->jobActive == QEMU_JOB_MIGRATION_OUT)
+ || (priv->jobActive == QEMU_JOB_SAVE)) {
+ virDomainObjRef(vm);
+ while (priv->jobSignals & QEMU_JOB_SIGNAL_BLKINFO)
+ ignore_value(virCondWait(&priv->signalCond, &vm->lock));
+
+ priv->jobSignals |= QEMU_JOB_SIGNAL_BLKINFO;
+ priv->jobSignalsData.infoDevName = disk->info.alias;
+ priv->jobSignalsData.blockInfo = info;
+ priv->jobSignalsData.infoRetCode = -1;
+
+ while (priv->jobSignals & QEMU_JOB_SIGNAL_BLKINFO)
+ ignore_value(virCondWait(&priv->signalCond, &vm->lock));
+
+ ret = priv->jobSignalsData.infoRetCode;
+ if (virDomainObjUnref(vm) == 0)
+ vm = NULL;
+ } else {
+ if (qemuDomainObjBeginJob(vm) < 0)
+ goto cleanup;
+
+ if (!virDomainObjIsActive(vm)) {
+ qemuReportError(VIR_ERR_OPERATION_INVALID,
+ "%s", _("domain is not running"));
+ goto endjob;
+ }
+
qemuDomainObjEnterMonitor(vm);
ret = qemuMonitorGetBlockExtent(priv->mon,
disk->info.alias,
&info->allocation);
qemuDomainObjExitMonitor(vm);
- }
- if (qemuDomainObjEndJob(vm) == 0)
- vm = NULL;
+endjob:
+ if (qemuDomainObjEndJob(vm) == 0)
+ vm = NULL;
+ }
} else {
ret = 0;
}
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 6738a53..21fdb4c 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -158,6 +158,38 @@ qemuMigrationWaitForCompletion(struct qemud_driver *driver, virDomainObjPtr vm)
VIR_WARN0("Unable to set migration speed");
}
+ if (priv->jobSignals & QEMU_JOB_SIGNAL_BLKSTAT) {
+ qemuDomainObjEnterMonitorWithDriver(driver, vm);
+ rc = qemuMonitorGetBlockStatsInfo(priv->mon,
+ priv->jobSignalsData.statDevName,
+ &priv->jobSignalsData.blockStat->rd_req,
+ &priv->jobSignalsData.blockStat->rd_bytes,
+ &priv->jobSignalsData.blockStat->wr_req,
+ &priv->jobSignalsData.blockStat->wr_bytes,
+ &priv->jobSignalsData.blockStat->errs);
+ qemuDomainObjExitMonitorWithDriver(driver, vm);
+
+ priv->jobSignalsData.statRetCode = rc;
+ priv->jobSignals ^= QEMU_JOB_SIGNAL_BLKSTAT;
+
+ if (rc < 0)
+ VIR_WARN0("Unable to get block statistics");
+ }
+
+ if (priv->jobSignals & QEMU_JOB_SIGNAL_BLKINFO) {
+ qemuDomainObjEnterMonitorWithDriver(driver, vm);
+ rc = qemuMonitorGetBlockExtent(priv->mon,
+ priv->jobSignalsData.infoDevName,
+ &priv->jobSignalsData.blockInfo->allocation);
+ qemuDomainObjExitMonitorWithDriver(driver, vm);
+
+ priv->jobSignalsData.infoRetCode = rc;
+ priv->jobSignals ^= QEMU_JOB_SIGNAL_BLKINFO;
+
+ if (rc < 0)
+ VIR_WARN0("Unable to get block information");
+ }
+
/* Repeat check because the job signals might have caused
* guest to die
*/
@@ -223,6 +255,8 @@ qemuMigrationWaitForCompletion(struct qemud_driver *driver, virDomainObjPtr vm)
break;
}
+ virCondSignal(&priv->signalCond);
+
virDomainObjUnlock(vm);
qemuDriverUnlock(driver);
@@ -233,6 +267,7 @@ qemuMigrationWaitForCompletion(struct qemud_driver *driver, virDomainObjPtr vm)
}
cleanup:
+ virCondBroadcast(&priv->signalCond);
return ret;
}
--
1.7.1
--
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