From: Fam Zheng <famz@redhat.com>
Date: Mon, 23 May 2016 02:19:36 +0000 (+0800)
Subject: blockdev-backup: Don't move target AioContext if it's attached
X-Git-Tag: qemu-xen-4.8.0-rc1~228^2~9
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=efd7556708bdfb61dab259e08bd71fbe5680ddcd;p=qemu-xen.git

blockdev-backup: Don't move target AioContext if it's attached

If the BDS is attached, it will want to stay on the AioContext where its
BlockBackend is. Don't call bdrv_set_aio_context in this case.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1463969978-24970-3-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---

diff --git a/blockdev.c b/blockdev.c
index ea7f3974e2..6ccb8e1f84 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3371,7 +3371,17 @@ void do_blockdev_backup(const char *device, const char *target,
         goto out;
     }
 
-    bdrv_set_aio_context(target_bs, aio_context);
+    if (bdrv_get_aio_context(target_bs) != aio_context) {
+        if (!bdrv_has_blk(target_bs)) {
+            /* The target BDS is not attached, we can safely move it to another
+             * AioContext. */
+            bdrv_set_aio_context(target_bs, aio_context);
+        } else {
+            error_setg(errp, "Target is attached to a different thread from "
+                             "source.");
+            goto out;
+        }
+    }
     backup_start(bs, target_bs, speed, sync, NULL, on_source_error,
                  on_target_error, block_job_cb, bs, txn, &local_err);
     if (local_err != NULL) {