qemuCheckpointDiscardBitmaps: Reopen images for bitmap modifications

Qemu's bitmap APIs don't reopen the appropriate images read-write for
modification. It's libvirt's duty to reopen them via blockdev-reopen
if we wish to modify the bitmaps.

Use the new helpers to reopen the images for bitmap manipulation.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_checkpoint.c

@@ -300,6 +300,10 @@ qemuCheckpointDiscardBitmaps(virDomainObjPtr vm,
                                                false, false, false) < 0)
             goto relabel;
 
+        if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV_REOPEN) &&
+            qemuBlockReopenReadWrite(vm, src, QEMU_ASYNC_JOB_NONE) < 0)
+            goto relabel;
+
         relabelimages = g_slist_prepend(relabelimages, src);
     }
 
@@ -312,6 +316,9 @@ qemuCheckpointDiscardBitmaps(virDomainObjPtr vm,
     for (next = relabelimages; next; next = next->next) {
         virStorageSourcePtr src = next->data;
 
+        if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV_REOPEN))
+            ignore_value(qemuBlockReopenReadOnly(vm, src, QEMU_ASYNC_JOB_NONE));
+
         ignore_value(qemuDomainStorageSourceAccessAllow(driver, vm, src,
                                                         true, false, false));
     }