From: Kevin Wolf <kwolf@redhat.com>
Date: Mon, 14 Jul 2025 13:01:53 +0000 (+0200)
Subject: block: Allow bdrv_new() with and without graph lock
X-Git-Tag: v10.1.0-rc0~13^2~38
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=975d9ff32e37f67e82d0da546cfb567bdee9c6fb;p=thirdparty%2Fqemu.git

block: Allow bdrv_new() with and without graph lock

bdrv_new() calls bdrv_drained_begin(), which can poll and therefore
can't be called while holding the graph lock. One option to make sure
that this call is allowed would be marking bdrv_new() GRAPH_UNLOCKED.

However, this is actually an unnecessary restriction because we know
that we only just created the BlockDriverState and it isn't even part of
the graph yet. We can use bdrv_do_drained_begin_quiesce() instead to
avoid the polling, which means that bdrv_new() can now safely be called
from callers that hold the graph lock as well as from callers that
don't.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---

diff --git a/block.c b/block.c
index 932e599f45..fe5aa2e767 100644
--- a/block.c
+++ b/block.c
@@ -431,7 +431,7 @@ BlockDriverState *bdrv_new(void)
     bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1);
 
     for (i = 0; i < bdrv_drain_all_count; i++) {
-        bdrv_drained_begin(bs);
+        bdrv_do_drained_begin_quiesce(bs, NULL);
     }
 
     QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);