hw/9pfs: Add fs driver specific details to fscontext

Add a new context flag PATHNAME_FSCONTEXT and indicate whether
the fs driver track fid using path names. Also add a private
pointer that help us to track fs driver specific values in there

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
index 8c7c3f0..80147d4 100644
--- a/hw/9pfs/virtio-9p.h
+++ b/hw/9pfs/virtio-9p.h
@@ -388,6 +388,27 @@
     return pdu_packunpack(dst, sg, sg_count, offset, size, 0);
 }
 
+static inline void v9fs_path_write_lock(V9fsState *s)
+{
+    if (s->ctx.flags & PATHNAME_FSCONTEXT) {
+        qemu_co_rwlock_wrlock(&s->rename_lock);
+    }
+}
+
+static inline void v9fs_path_read_lock(V9fsState *s)
+{
+    if (s->ctx.flags & PATHNAME_FSCONTEXT) {
+        qemu_co_rwlock_rdlock(&s->rename_lock);
+    }
+}
+
+static inline void v9fs_path_unlock(V9fsState *s)
+{
+    if (s->ctx.flags & PATHNAME_FSCONTEXT) {
+        qemu_co_rwlock_unlock(&s->rename_lock);
+    }
+}
+
 extern void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq);
 extern void virtio_9p_set_fd_limit(void);
 extern void v9fs_reclaim_fd(V9fsState *s);