NFSv4: Ensure that nfs4_do_close() doesn't race with umount

nfs4_do_close() does not currently have any way to ensure that the user
won't attempt to unmount the partition while the asynchronous RPC call
is completing. This again may cause Oopses in nfs_update_inode().

Add a vfsmount argument to nfs4_close_state to ensure that the partition
remains mounted while we're closing the file.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 8ed79d5..a85138e 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -341,7 +341,7 @@
 /*
  * Close the current file.
  */
-void nfs4_close_state(struct nfs4_state *state, mode_t mode)
+void nfs4_close_state(struct path *path, struct nfs4_state *state, mode_t mode)
 {
 	struct inode *inode = state->inode;
 	struct nfs4_state_owner *owner = state->owner;
@@ -375,7 +375,7 @@
 	spin_unlock(&inode->i_lock);
 	spin_unlock(&owner->so_lock);
 
-	if (oldstate != newstate && nfs4_do_close(inode, state) == 0)
+	if (oldstate != newstate && nfs4_do_close(path, state) == 0)
 		return;
 	nfs4_put_open_state(state);
 	nfs4_put_state_owner(owner);