[libvirt] [PATCH 04/10] qemu: snapshot: Restrict file existance check only for local storage

[Peter Krempa]

Soon we'll allow more protocols and storage types with snapshots where
we in some cases can't check whether the storage already exists.
Restrict the sanity checks whether the destination images exist or not
for local storage where it's easy. For any other case we will fail
later.

Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
 src/qemu/qemu_driver.c | 44 ++++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 29a47af0a2..52540eb77d 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15022,32 +15022,34 @@ qemuDomainSnapshotPrepareDiskExternal(virDomainDiskDefPtr disk,
             return -1;
     }

-    if (virStorageFileInit(snapdisk->src) < 0)
-        return -1;
+    if (virStorageSourceIsLocalStorage(snapdisk->src)) {
+        if (virStorageFileInit(snapdisk->src) < 0)
+            return -1;

-    rc = virStorageFileStat(snapdisk->src, &st);
-    err = errno;
+        rc = virStorageFileStat(snapdisk->src, &st);
+        err = errno;

-    virStorageFileDeinit(snapdisk->src);
+        virStorageFileDeinit(snapdisk->src);

-    if (rc < 0) {
-        if (err != ENOENT) {
-            virReportSystemError(err,
-                                 _("unable to stat for disk %s: %s"),
-                                 snapdisk->name, snapdisk->src->path);
-            return -1;
-        } else if (reuse) {
-            virReportSystemError(err,
-                                 _("missing existing file for disk %s: %s"),
-                                 snapdisk->name, snapdisk->src->path);
+        if (rc < 0) {
+            if (err != ENOENT) {
+                virReportSystemError(err,
+                                     _("unable to stat for disk %s: %s"),
+                                     snapdisk->name, snapdisk->src->path);
+                return -1;
+            } else if (reuse) {
+                virReportSystemError(err,
+                                     _("missing existing file for disk %s: %s"),
+                                     snapdisk->name, snapdisk->src->path);
+                return -1;
+            }
+        } else if (!S_ISBLK(st.st_mode) && st.st_size && !reuse) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("external snapshot file for disk %s already "
+                             "exists and is not a block device: %s"),
+                           snapdisk->name, snapdisk->src->path);
             return -1;
         }
-    } else if (!S_ISBLK(st.st_mode) && st.st_size && !reuse) {
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       _("external snapshot file for disk %s already "
-                         "exists and is not a block device: %s"),
-                       snapdisk->name, snapdisk->src->path);
-        return -1;
     }

     return 0;
-- 
2.21.0