Merge remote-tracking branch 'remotes/thibault/tags/samuel-thibault' into staging

[mirror_qemu.git] / block.c

diff --git a/block.c b/block.c
index ed9253c786ac238eacb23726002e6f51f9371668..16615bc876d0c2695a3de2c851575f0b19467f42 100644 (file)
--- a/block.c
+++ b/block.c
@@ -950,8 +950,9 @@ static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
     qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
     qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
 
-    /* Copy the read-only option from the parent */
+    /* Copy the read-only and discard options from the parent */
     qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
+    qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
 
     /* aio=native doesn't work for cache.direct=off, so disable it for the
      * temporary snapshot */
@@ -4218,14 +4219,15 @@ BlockDriverState *bdrv_find_base(BlockDriverState *bs)
 /*
  * Return true if at least one of the backing links between @bs and
  * @base is frozen. @errp is set if that's the case.
+ * @base must be reachable from @bs, or NULL.
  */
 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
                                   Error **errp)
 {
     BlockDriverState *i;
 
-    for (i = bs; i != base && i->backing; i = backing_bs(i)) {
-        if (i->backing->frozen) {
+    for (i = bs; i != base; i = backing_bs(i)) {
+        if (i->backing && i->backing->frozen) {
             error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
                        i->backing->name, i->node_name,
                        backing_bs(i)->node_name);
@@ -4240,6 +4242,7 @@ bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
  * Freeze all backing links between @bs and @base.
  * If any of the links is already frozen the operation is aborted and
  * none of the links are modified.
+ * @base must be reachable from @bs, or NULL.
  * Returns 0 on success. On failure returns < 0 and sets @errp.
  */
 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
@@ -4251,8 +4254,10 @@ int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
         return -EPERM;
     }
 
-    for (i = bs; i != base && i->backing; i = backing_bs(i)) {
-        i->backing->frozen = true;
+    for (i = bs; i != base; i = backing_bs(i)) {
+        if (i->backing) {
+            i->backing->frozen = true;
+        }
     }
 
     return 0;
@@ -4261,14 +4266,17 @@ int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
 /*
  * Unfreeze all backing links between @bs and @base. The caller must
  * ensure that all links are frozen before using this function.
+ * @base must be reachable from @bs, or NULL.
  */
 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
 {
     BlockDriverState *i;
 
-    for (i = bs; i != base && i->backing; i = backing_bs(i)) {
-        assert(i->backing->frozen);
-        i->backing->frozen = false;
+    for (i = bs; i != base; i = backing_bs(i)) {
+        if (i->backing) {
+            assert(i->backing->frozen);
+            i->backing->frozen = false;
+        }
     }
 }
 
@@ -4350,11 +4358,10 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
     QLIST_FOREACH_SAFE(c, &top->parents, next_parent, next) {
         /* Check whether we are allowed to switch c from top to base */
         GSList *ignore_children = g_slist_prepend(NULL, c);
-        bdrv_check_update_perm(base, NULL, c->perm, c->shared_perm,
-                               ignore_children, &local_err);
+        ret = bdrv_check_update_perm(base, NULL, c->perm, c->shared_perm,
+                                     ignore_children, &local_err);
         g_slist_free(ignore_children);
-        if (local_err) {
-            ret = -EPERM;
+        if (ret < 0) {
             error_report_err(local_err);
             goto exit;
         }