qemu-kvm/kvm-block-Allow-inactivating-already-inactive-nodes.patch

From 87507aae02f0b381c658a71777baad6fe3129485 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Tue, 4 Feb 2025 22:13:53 +0100
Subject: [PATCH 08/22] block: Allow inactivating already inactive nodes

RH-Author: Kevin Wolf <kwolf@redhat.com>
RH-MergeRequest: 340: QMP command for block device reactivation after migration
RH-Jira: RHEL-54670
RH-Acked-by: Eric Blake <eblake@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Commit: [8/22] 5247551bb2cc2ac51ce28f690f30b0f54c9abef5 (kmwolf/centos-qemu-kvm)

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>
Message-ID: <20250204211407.381505-3-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit a6490ec9d56b9e95a13918813585a3a9891710bc)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/block.c b/block.c
index c94d78eefd..a2aa454312 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;
-- 
2.39.3