[PATCH v3 02/16] block: Allow inactivating already inactive nodes

[Kevin Wolf <kwolf@redhat.com>]

What we wanted to catch with the assertion is cases where the recursion
finds that a child was inactive before its parent. This should never
happen. But if the user tries to inactivate an image that is already
inactive, that's harmless and we don't want to fail the assertion.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/block.c b/block.c
index 9aad958269..9458c5e013 100644
--- a/block.c
+++ b/block.c
@@ -6959,7 +6959,8 @@ bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
     return false;
 }
 
-static int GRAPH_RDLOCK bdrv_inactivate_recurse(BlockDriverState *bs)
+static int GRAPH_RDLOCK
+bdrv_inactivate_recurse(BlockDriverState *bs, bool top_level)
 {
     BdrvChild *child, *parent;
     int ret;
@@ -6977,7 +6978,14 @@ static int GRAPH_RDLOCK bdrv_inactivate_recurse(BlockDriverState *bs)
         return 0;
     }
 
-    assert(!(bs->open_flags & BDRV_O_INACTIVE));
+    /*
+     * Inactivating an already inactive node on user request is harmless, but if
+     * a child is already inactive before its parent, that's bad.
+     */
+    if (bs->open_flags & BDRV_O_INACTIVE) {
+        assert(top_level);
+        return 0;
+    }
 
     /* Inactivate this node */
     if (bs->drv->bdrv_inactivate) {
@@ -7014,7 +7022,7 @@ static int GRAPH_RDLOCK bdrv_inactivate_recurse(BlockDriverState *bs)
 
     /* Recursively inactivate children */
     QLIST_FOREACH(child, &bs->children, next) {
-        ret = bdrv_inactivate_recurse(child->bs);
+        ret = bdrv_inactivate_recurse(child->bs, false);
         if (ret < 0) {
             return ret;
         }
@@ -7039,7 +7047,7 @@ int bdrv_inactivate_all(void)
         if (bdrv_has_bds_parent(bs, false)) {
             continue;
         }
-        ret = bdrv_inactivate_recurse(bs);
+        ret = bdrv_inactivate_recurse(bs, true);
         if (ret < 0) {
             bdrv_next_cleanup(&it);
             break;
-- 
2.48.1