hw/9pfs: use migration blockers to prevent live migration when virtfs export path is mounted

Now when you try to migrate with VirtFS export path mounted, you get a proper QMP error:

(qemu) migrate tcp:localhost:4444
Migration is disabled when VirtFS export path '/tmp/' is mounted in the guest using mount_tag 'v_tmp'
(qemu)

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/qerror.c b/qerror.c
index fdf62b9e2..25bc91e58 100644
--- a/qerror.c
+++ b/qerror.c
@@ -235,6 +235,11 @@ static const QErrorStringTable qerror_table[] = {
                      "supported by this qemu version: %(feature)",
     },
     {
+        .error_fmt = QERR_VIRTFS_FEATURE_BLOCKS_MIGRATION,
+        .desc      = "Migration is disabled when VirtFS export path '%(path)' "
+                     "is mounted in the guest using mount_tag '%(tag)'",
+    },
+    {
         .error_fmt = QERR_VNC_SERVER_FAILED,
         .desc      = "Could not start VNC server on %(target)",
     },