NFS: Stop sillyname renames and unmounts from racing

Added an active/deactive mechanism to the nfs_server structure
allowing async operations to hold off umount until the
operations are done.

Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 431981d..8e5428e 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -14,6 +14,8 @@
 #include <linux/sched.h>
 #include <linux/wait.h>
 
+#include "internal.h"
+
 struct nfs_unlinkdata {
 	struct hlist_node list;
 	struct nfs_removeargs args;
@@ -113,6 +115,7 @@
 	struct nfs_unlinkdata	*data = calldata;
 
 	nfs_dec_sillycount(data->dir);
+	nfs_sb_deactive(NFS_SERVER(data->dir));
 	nfs_free_unlinkdata(data);
 }
 
@@ -153,6 +156,7 @@
 		nfs_dec_sillycount(dir);
 		return 0;
 	}
+	nfs_sb_active(NFS_SERVER(dir));
 	data->args.fh = NFS_FH(dir);
 	nfs_fattr_init(&data->res.dir_attr);