NFSv4: Convert open state lookup to use RCU

	atomic_t count;

	wait_queue_head_t waitq;

	struct rcu_head rcu_head;

};

	struct nfs_inode *nfsi = NFS_I(inode);

	struct nfs4_state *state;

	list_for_each_entry(state, &nfsi->open_states, inode_states) {

	list_for_each_entry_rcu(state, &nfsi->open_states, inode_states) {

		if (state->owner != owner)

			continue;

		if (!nfs4_valid_open_stateid(state))

static void

nfs4_free_open_state(struct nfs4_state *state)

{

	kfree(state);

	kfree_rcu(state, rcu_head);

}

struct nfs4_state *

	struct nfs4_state *state, *new;

	struct nfs_inode *nfsi = NFS_I(inode);

	spin_lock(&inode->i_lock);

	rcu_read_lock();

	state = __nfs4_find_state_byowner(inode, owner);

	spin_unlock(&inode->i_lock);

	rcu_read_unlock();

	if (state)

		goto out;

	new = nfs4_alloc_open_state();

		state = new;

		state->owner = owner;

		atomic_inc(&owner->so_count);

		list_add(&state->inode_states, &nfsi->open_states);

		list_add_rcu(&state->inode_states, &nfsi->open_states);

		ihold(inode);

		state->inode = inode;

		spin_unlock(&inode->i_lock);

	if (!atomic_dec_and_lock(&state->count, &owner->so_lock))

		return;

	spin_lock(&inode->i_lock);

	list_del(&state->inode_states);

	list_del_rcu(&state->inode_states);

	list_del(&state->open_states);

	spin_unlock(&inode->i_lock);

	spin_unlock(&owner->so_lock);