[libvirt] [PATCH] qemu: don't check for backing chains for formats w/o snapshot support

[Martin Kletzander]

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1019926
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=868673

Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
---
 src/libvirt_private.syms  |  2 +-
 src/qemu/qemu_domain.c    |  3 +++
 src/util/virstoragefile.c | 15 +++++++++++++++
 src/util/virstoragefile.h |  2 ++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 0e81f2f..42c0185 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1834,6 +1834,7 @@ virStorageFileIsClusterFS;
 virStorageFileProbeFormat;
 virStorageFileProbeFormatFromBuf;
 virStorageFileResize;
+virStorageFormatMaySupportSnapshots;
 virStorageIsFile;
 virStorageNetHostDefClear;
 virStorageNetHostDefCopy;
@@ -1850,7 +1851,6 @@ virStorageSourcePoolModeTypeToString;
 virStorageTypeFromString;
 virStorageTypeToString;

-
 # util/virstring.h
 virArgvToString;
 virAsprintfInternal;
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index cdd4601..abc2a68 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -2250,6 +2250,9 @@ qemuDomainCheckDiskPresence(virQEMUDriverPtr driver,
         if (!virDomainDiskGetSource(disk))
             continue;

+        if (!virStorageFormatMaySupportSnapshots(disk->src.format))
+            continue;
+
         if (qemuDomainDetermineDiskChain(driver, vm, disk, false) >= 0 &&
             qemuDiskChainCheckBroken(disk) >= 0)
             continue;
diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index ea80c1d..c781a6b 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -1730,3 +1730,18 @@ virStorageSourceClear(virStorageSourcePtr def)
     virStorageNetHostDefFree(def->nhosts, def->hosts);
     virStorageSourceAuthClear(def);
 }
+
+bool
+virStorageFormatMaySupportSnapshots(enum virStorageFileFormat format)
+{
+    if (format == VIR_STORAGE_FILE_AUTO ||
+        format == VIR_STORAGE_FILE_AUTO_SAFE)
+        return true;
+
+    /* Better safe than sorry */
+    if (format <= VIR_STORAGE_FILE_NONE ||
+        format >= VIR_STORAGE_FILE_LAST)
+        return false;
+
+    return !!fileTypeInfo[format].getBackingStore;
+}
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index 1b8b14f..bcbfb88 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -339,4 +339,6 @@ void virStorageSourcePoolDefFree(virStorageSourcePoolDefPtr def);
 void virStorageSourceClear(virStorageSourcePtr def);
 int virStorageSourceGetActualType(virStorageSourcePtr def);

+bool virStorageFormatMaySupportSnapshots(enum virStorageFileFormat format);
+
 #endif /* __VIR_STORAGE_FILE_H__ */
-- 
1.9.2