9pfs: clear migration blocker at session reset

The migration blocker survives a device reset: if the guest mounts a 9p
share and then gets rebooted with system_reset, it will be unmigratable
until it remounts and umounts the 9p share again.

This happens because the migration blocker is supposed to be cleared when
we put the last reference on the root fid, but virtfs_reset() wrongly calls
free_fid() instead of put_fid().

This patch fixes virtfs_reset() so that it honor the way fids are supposed
to be manipulated: first get a reference and later put it back when you're
done.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Li Qiang <liqiang6-s@360.cn>

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index ef47a0a5ad6f64f5f08f85b6cb131ccbe3971b0a..c80ba67389ce29033c01f26dd1668f235bb46e78 100644 (file)
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -539,14 +539,15 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu)
 
     /* Free all fids */
     while (s->fid_list) {
+        /* Get fid */
         fidp = s->fid_list;
+        fidp->ref++;
+
+        /* Clunk fid */
         s->fid_list = fidp->next;
+        fidp->clunked = 1;
 
-        if (fidp->ref) {
-            fidp->clunked = 1;
-        } else {
-            free_fid(pdu, fidp);
-        }
+        put_fid(pdu, fidp);
     }
 }