[PATCH v3 11/15] qemu: block: Properly format storage slice into backing store strings

[Peter Krempa <pkrempa@xxxxxxxxxx>]

When creating overlay images e.g. for snapshots or when merging
snapshots we often specify the backing store string to use. Make the
formatter aware of backing chain entries which have a <slice>
configured so that we record it properly. Otherwise such images
would not work without the XML (when detecting the backing chain).

Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
 src/qemu/qemu_block.c | 80 ++++++++++++++++++++++++++-----------------
 1 file changed, 49 insertions(+), 31 deletions(-)

diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
index b23a4baae6..8b94365c68 100644
--- a/src/qemu/qemu_block.c
+++ b/src/qemu/qemu_block.c
@@ -1930,44 +1930,48 @@ qemuBlockGetBackingStoreString(virStorageSourcePtr src)
 {
     int actualType = virStorageSourceGetActualType(src);
     g_autoptr(virJSONValue) backingProps = NULL;
+    g_autoptr(virJSONValue) sliceProps = NULL;
+    virJSONValuePtr props = NULL;
     g_autoptr(virURI) uri = NULL;
     g_autofree char *backingJSON = NULL;
     char *ret = NULL;

-    if (virStorageSourceIsLocalStorage(src)) {
-        ret = g_strdup(src->path);
-        return ret;
-    }
+    if (!src->sliceStorage) {
+        if (virStorageSourceIsLocalStorage(src)) {
+            ret = g_strdup(src->path);
+            return ret;
+        }

-    /* generate simplified URIs for the easy cases */
-    if (actualType == VIR_STORAGE_TYPE_NETWORK &&
-        src->nhosts == 1 &&
-        src->hosts->transport == VIR_STORAGE_NET_HOST_TRANS_TCP) {
+        /* generate simplified URIs for the easy cases */
+        if (actualType == VIR_STORAGE_TYPE_NETWORK &&
+            src->nhosts == 1 &&
+            src->hosts->transport == VIR_STORAGE_NET_HOST_TRANS_TCP) {
+
+            switch ((virStorageNetProtocol) src->protocol) {
+            case VIR_STORAGE_NET_PROTOCOL_NBD:
+            case VIR_STORAGE_NET_PROTOCOL_HTTP:
+            case VIR_STORAGE_NET_PROTOCOL_HTTPS:
+            case VIR_STORAGE_NET_PROTOCOL_FTP:
+            case VIR_STORAGE_NET_PROTOCOL_FTPS:
+            case VIR_STORAGE_NET_PROTOCOL_TFTP:
+            case VIR_STORAGE_NET_PROTOCOL_ISCSI:
+            case VIR_STORAGE_NET_PROTOCOL_GLUSTER:
+                if (!(uri = qemuBlockStorageSourceGetURI(src)))
+                    return NULL;

-        switch ((virStorageNetProtocol) src->protocol) {
-        case VIR_STORAGE_NET_PROTOCOL_NBD:
-        case VIR_STORAGE_NET_PROTOCOL_HTTP:
-        case VIR_STORAGE_NET_PROTOCOL_HTTPS:
-        case VIR_STORAGE_NET_PROTOCOL_FTP:
-        case VIR_STORAGE_NET_PROTOCOL_FTPS:
-        case VIR_STORAGE_NET_PROTOCOL_TFTP:
-        case VIR_STORAGE_NET_PROTOCOL_ISCSI:
-        case VIR_STORAGE_NET_PROTOCOL_GLUSTER:
-            if (!(uri = qemuBlockStorageSourceGetURI(src)))
-                return NULL;
+                if (!(ret = virURIFormat(uri)))
+                    return NULL;

-            if (!(ret = virURIFormat(uri)))
-                return NULL;
+                return ret;

-            return ret;
-
-        case VIR_STORAGE_NET_PROTOCOL_SHEEPDOG:
-        case VIR_STORAGE_NET_PROTOCOL_RBD:
-        case VIR_STORAGE_NET_PROTOCOL_VXHS:
-        case VIR_STORAGE_NET_PROTOCOL_SSH:
-        case VIR_STORAGE_NET_PROTOCOL_LAST:
-        case VIR_STORAGE_NET_PROTOCOL_NONE:
-            break;
+            case VIR_STORAGE_NET_PROTOCOL_SHEEPDOG:
+            case VIR_STORAGE_NET_PROTOCOL_RBD:
+            case VIR_STORAGE_NET_PROTOCOL_VXHS:
+            case VIR_STORAGE_NET_PROTOCOL_SSH:
+            case VIR_STORAGE_NET_PROTOCOL_LAST:
+            case VIR_STORAGE_NET_PROTOCOL_NONE:
+                break;
+            }
         }
     }

@@ -1975,7 +1979,21 @@ qemuBlockGetBackingStoreString(virStorageSourcePtr src)
     if (!(backingProps = qemuBlockStorageSourceGetBackendProps(src, false, true, false)))
         return NULL;

-    if (!(backingJSON = virJSONValueToString(backingProps, false)))
+    props = backingProps;
+
+    if (src->sliceStorage) {
+        if (virJSONValueObjectCreate(&sliceProps,
+                                     "s:driver", "raw",
+                                     "U:offset", src->sliceStorage->offset,
+                                     "U:size", src->sliceStorage->size,
+                                     "a:file", &backingProps,
+                                     NULL) < 0)
+            return NULL;
+
+        props = sliceProps;
+    }
+
+    if (!(backingJSON = virJSONValueToString(props, false)))
         return NULL;

     ret = g_strdup_printf("json:%s", backingJSON);
-- 
2.24.1