[libvirt] [PATCH 1/2] qemu: don't log error for missing optional sources on stats

[Nikolay Shirokovskiy]

Every time we call all domain stats for inactive domain with
unavailable source we get error message in logs. It's a bit noisy.
While it's arguable whether we need such message or not for mandatory
disks we would like not to see messages for optional disks. Let's
filter at least for cases of local files. Fixing other cases would
require passing flag down the stack to .backendInit of storage
which is ugly.

Stats for active domain are fine because we either drop disks
with unavailable sources or clean source which is handled
by virStorageSourceIsEmpty in qemuDomainGetStatsOneBlockFallback.

We have these logs for successful stats since 25aa7035d which
in turn fixes 596a13713 which added substantial stats for offline
disks.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
---
 src/qemu/qemu_driver.c  | 5 +++++
 src/qemu/qemu_process.c | 9 +++++++++
 src/qemu/qemu_process.h | 2 ++
 3 files changed, 16 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index a52e249..72e4cfe 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -20290,6 +20290,11 @@ qemuDomainGetStatsBlockExportDisk(virDomainDiskDefPtr disk,
     const char *backendstoragealias;
     int ret = -1;
 
+    if (!virDomainObjIsActive(dom) &&
+        qemuProcessMissingLocalOptionalDisk(disk))
+        return qemuDomainGetStatsBlockExportHeader(disk, disk->src, *recordnr,
+                                                   records, nrecords);
+
     for (n = disk->src; virStorageSourceIsBacking(n); n = n->backingStore) {
         if (blockdev) {
             frontendalias = QEMU_DOMAIN_DISK_PRIVATE(disk)->qomName;
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 9cf9718..802274e 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -6070,6 +6070,15 @@ qemuProcessPrepareSEVGuestInput(virDomainObjPtr vm)
 }
 
 
+bool
+qemuProcessMissingLocalOptionalDisk(virDomainDiskDefPtr disk)
+{
+    return disk->startupPolicy == VIR_DOMAIN_STARTUP_POLICY_OPTIONAL &&
+           virStorageSourceIsLocalStorage(disk->src) && disk->src->path &&
+           !virFileExists(disk->src->path);
+}
+
+
 static int
 qemuProcessPrepareHostStorage(virQEMUDriverPtr driver,
                               virDomainObjPtr vm,
diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
index 2037467..52d396d 100644
--- a/src/qemu/qemu_process.h
+++ b/src/qemu/qemu_process.h
@@ -214,4 +214,6 @@ int qemuProcessStartManagedPRDaemon(virDomainObjPtr vm);
 
 void qemuProcessKillManagedPRDaemon(virDomainObjPtr vm);
 
+bool qemuProcessMissingLocalOptionalDisk(virDomainDiskDefPtr disk);
+
 #endif /* __QEMU_PROCESS_H__ */
-- 
1.8.3.1