From 5030396f715194896347881daf1fb2a27effd12e Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Fri, 21 Mar 2025 20:47:17 +0300
Subject: [PATCH] Clear QEMU eventfd handler on vitastor block driver
 destruction

---
 src/client/qemu_driver.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/client/qemu_driver.c b/src/client/qemu_driver.c
index 4c5f3633..f9ddbba2 100644
--- a/src/client/qemu_driver.c
+++ b/src/client/qemu_driver.c
@@ -568,6 +568,22 @@ static int vitastor_file_open(BlockDriverState *bs, QDict *options, int flags, E
 static void vitastor_close(BlockDriverState *bs)
 {
     VitastorClient *client = bs->opaque;
+    if (client->uring_eventfd >= 0)
+    {
+        // clear the eventfd handler
+        universal_aio_set_fd_handler(client->ctx, client->uring_eventfd, NULL, NULL, NULL);
+        int wait_bh = 0;
+        qemu_mutex_lock(&client->mutex);
+        // clear uring_eventfd itself to prevent future scheduling of new B/H
+        client->uring_eventfd = -1;
+        wait_bh = client->bh_uring_scheduled;
+        qemu_mutex_unlock(&client->mutex);
+        if (wait_bh)
+        {
+            // wait until existing scheduled B/H is ran
+            BDRV_POLL_WHILE(bs, client->bh_uring_scheduled);
+        }
+    }
     vitastor_c_destroy(client->proxy);
     if (client->fds)
     {