qcow2: Implement .bdrv_inactivate

The callback has to ensure that closing or flushing the image afterwards
wouldn't cause a write access to the image files. This means that just
the caches have to be written out, which is part of the existing
.bdrv_close implementation.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

block/qcow2.c

@@ -1686,31 +1686,41 @@ fail:
     return ret;
 }
 
-static void qcow2_close(BlockDriverState *bs)
+static int qcow2_inactivate(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
-    qemu_vfree(s->l1_table);
-    /* else pre-write overlap checks in cache_destroy may crash */
-    s->l1_table = NULL;
-
-    if (!(bs->open_flags & BDRV_O_INACTIVE)) {
-        int ret1, ret2;
+    int ret, result = 0;
 
-        ret1 = qcow2_cache_flush(bs, s->l2_table_cache);
-        ret2 = qcow2_cache_flush(bs, s->refcount_block_cache);
-
-        if (ret1) {
+    ret = qcow2_cache_flush(bs, s->l2_table_cache);
+    if (ret) {
+        result = ret;
         error_report("Failed to flush the L2 table cache: %s",
-                         strerror(-ret1));
+                     strerror(-ret));
     }
-        if (ret2) {
+
+    ret = qcow2_cache_flush(bs, s->refcount_block_cache);
+    if (ret) {
+        result = ret;
         error_report("Failed to flush the refcount block cache: %s",
-                         strerror(-ret2));
+                     strerror(-ret));
     }
 
-        if (!ret1 && !ret2) {
+    if (result == 0) {
         qcow2_mark_clean(bs);
     }
+
+    return result;
+}
+
+static void qcow2_close(BlockDriverState *bs)
+{
+    BDRVQcow2State *s = bs->opaque;
+    qemu_vfree(s->l1_table);
+    /* else pre-write overlap checks in cache_destroy may crash */
+    s->l1_table = NULL;
+
+    if (!(bs->open_flags & BDRV_O_INACTIVE)) {
+        qcow2_inactivate(bs);
     }
 
     cache_clean_timer_del(bs);
@@ -3340,6 +3350,7 @@ BlockDriver bdrv_qcow2 = {
 
     .bdrv_refresh_limits        = qcow2_refresh_limits,
     .bdrv_invalidate_cache      = qcow2_invalidate_cache,
+    .bdrv_inactivate            = qcow2_inactivate,
 
     .create_opts         = &qcow2_create_opts,
     .bdrv_check          = qcow2_check,