/*
 *  fs/nfs/nfs4renewd.c
 *
 *  Copyright (c) 2002 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Kendrick Smith <kmsmith@umich.edu>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Implementation of the NFSv4 "renew daemon", which wakes up periodically to
 * send a RENEW, to keep state alive on the server.  The daemon is implemented
 * as an rpc_task, not a real kernel thread, so it always runs in rpciod's
 * context.  There is one renewd per nfs_server.
 *
 */

#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/clnt.h>

#include <linux/nfs.h>
#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include "nfs4_fs.h"
#include "delegation.h"

#define NFSDBG_FACILITY         NFSDBG_STATE

void
nfs4_renew_state(struct work_struct *work)
{
        const struct nfs4_state_maintenance_ops *ops;
        struct nfs_client *clp =
                container_of(work, struct nfs_client, cl_renewd.work);
        const struct cred *cred;
        long lease;
        unsigned long last, now;
        unsigned renew_flags = 0;

        ops = clp->cl_mvops->state_renewal_ops;
        dprintk("%s: start\n", __func__);

        if (test_bit(NFS_CS_STOP_RENEW, &clp->cl_res_state))
                goto out;

        lease = clp->cl_lease_time;
        last = clp->cl_last_renewal;
        now = jiffies;
        /* Are we close to a lease timeout? */
        if (time_after(now, last + lease/3))
                renew_flags |= NFS4_RENEW_TIMEOUT;
        if (nfs_delegations_present(clp))
                renew_flags |= NFS4_RENEW_DELEGATION_CB;

        if (renew_flags != 0) {
                cred = ops->get_state_renewal_cred(clp);
                if (cred == NULL) {
                        if (!(renew_flags & NFS4_RENEW_DELEGATION_CB)) {
                                set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
                                goto out;
                        }
                        nfs_expire_all_delegations(clp);
                } else {
                        int ret;

                        /* Queue an asynchronous RENEW. */
                        ret = ops->sched_state_renewal(clp, cred, renew_flags);
                        put_cred(cred);
                        switch (ret) {
                        default:
                                goto out_exp;
                        case -EAGAIN:
                        case -ENOMEM:
                                break;
                        }
                }
        } else {
                dprintk("%s: failed to call renewd. Reason: lease not expired \n",
                                __func__);
        }
        nfs4_schedule_state_renewal(clp);
out_exp:
        nfs_expire_unreferenced_delegations(clp);
out:
        dprintk("%s: done\n", __func__);
}

void
nfs4_schedule_state_renewal(struct nfs_client *clp)
{
        long timeout;

        spin_lock(&clp->cl_lock);
        timeout = (2 * clp->cl_lease_time) / 3 + (long)clp->cl_last_renewal
                - (long)jiffies;
        if (timeout < 5 * HZ)
                timeout = 5 * HZ;
        dprintk("%s: requeueing work. Lease period = %ld\n",
                        __func__, (timeout + HZ - 1) / HZ);
        mod_delayed_work(system_percpu_wq, &clp->cl_renewd, timeout);
        set_bit(NFS_CS_RENEWD, &clp->cl_res_state);
        spin_unlock(&clp->cl_lock);
}

void
nfs4_kill_renewd(struct nfs_client *clp)
{
        cancel_delayed_work_sync(&clp->cl_renewd);
}

#define MAX_LEASE_PERIOD (60 * 60)      /* 1 hour */

/**
 * nfs4_set_lease_period - Sets the lease period on a nfs_client
 *
 * @clp: pointer to nfs_client
 * @period: new value for lease period (in seconds)
 */
void nfs4_set_lease_period(struct nfs_client *clp, u32 period)
{
        unsigned long lease;

        /* Limit the lease period */
        if (period < MAX_LEASE_PERIOD)
                lease = period * HZ;
        else
                lease = MAX_LEASE_PERIOD * HZ;

        spin_lock(&clp->cl_lock);
        clp->cl_lease_time = lease;
        spin_unlock(&clp->cl_lock);

        /* Cap maximum reconnect timeout at 1/2 lease period */
        rpc_set_connect_timeout(clp->cl_rpcclient, lease, lease >> 1);
}