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linux-next/fs/nfs/nfs4renewd.c
Andy Adamson d1f456b0b9 NFSv4.1: Fix an NFSv4.1 state renewal regression 
Commit 2f60ea6b8c ("NFSv4: The NFSv4.0 client must send RENEW calls if it holds a delegation") set the NFS4_RENEW_TIMEOUT flag in nfs4_renew_state, and does
not put an nfs41_proc_async_sequence call, the NFSv4.1 lease renewal heartbeat
call, on the wire to renew the NFSv4.1 state if the flag was not set.

The NFS4_RENEW_TIMEOUT flag is set when "now" is after the last renewal
(cl_last_renewal) plus the lease time divided by 3. This is arbitrary and
sometimes does the following:

In normal operation, the only way a future state renewal call is put on the
wire is via a call to nfs4_schedule_state_renewal, which schedules a
nfs4_renew_state workqueue task. nfs4_renew_state determines if the
NFS4_RENEW_TIMEOUT should be set, and the calls nfs41_proc_async_sequence,
which only gets sent if the NFS4_RENEW_TIMEOUT flag is set.
Then the nfs41_proc_async_sequence rpc_release function schedules
another state remewal via nfs4_schedule_state_renewal.

Without this change we can get into a state where an application stops
accessing the NFSv4.1 share, state renewal calls stop due to the
NFS4_RENEW_TIMEOUT flag _not_ being set. The only way to recover
from this situation is with a clientid re-establishment, once the application
resumes and the server has timed out the lease and so returns
NFS4ERR_BAD_SESSION on the subsequent SEQUENCE operation.

An example application:
open, lock, write a file.

sleep for 6 * lease (could be less)

ulock, close.

In the above example with NFSv4.1 delegations enabled, without this change,
there are no OP_SEQUENCE state renewal calls during the sleep, and the
clientid is recovered due to lease expiration on the close.

This issue does not occur with NFSv4.1 delegations disabled, nor with
NFSv4.0, with or without delegations enabled.

Signed-off-by: Andy Adamson <andros@netapp.com>
Link: http://lkml.kernel.org/r/1411486536-23401-1-git-send-email-andros@netapp.com
Fixes: 2f60ea6b8c (NFSv4: The NFSv4.0 client must send RENEW calls...)
Cc: stable@vger.kernel.org # 3.2.x
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-09-30 17:18:42 -04:00

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/*
* 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);
struct rpc_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;
spin_lock(&clp->cl_lock);
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_locked(clp);
spin_unlock(&clp->cl_lock);
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_rpccred(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__);
spin_unlock(&clp->cl_lock);
}
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_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);
}
/*
* Local variables:
* c-basic-offset: 8
* End:
*/
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