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, 3 insertions, 0 deletions

diff --git a/qerror.h b/qerror.h
index 2d3d43b..6414cd9 100644
--- a/qerror.h
+++ b/qerror.h
@@ -192,6 +192,9 @@ QError *qobject_to_qerror(const QObject *obj);
 #define QERR_UNKNOWN_BLOCK_FORMAT_FEATURE \
     "{ 'class': 'UnknownBlockFormatFeature', 'data': { 'device': %s, 'format': %s, 'feature': %s } }"
 
+#define QERR_VIRTFS_FEATURE_BLOCKS_MIGRATION \
+    "{ 'class': 'VirtFSFeatureBlocksMigration', 'data': { 'path': %s, 'tag': %s } }"
+
 #define QERR_VNC_SERVER_FAILED \
     "{ 'class': 'VNCServerFailed', 'data': { 'target': %s } }"