linux-stable/fs/nfs/nfs4renewd.c
Robert Milkowski 7dc2993a9e NFSv4.0: nfs4_do_fsinfo() should not do implicit lease renewals
Currently, each time nfs4_do_fsinfo() is called it will do an implicit
NFS4 lease renewal, which is not compliant with the NFS4 specification.
This can result in a lease being expired by an NFS server.

Commit 83ca7f5ab3 ("NFS: Avoid PUTROOTFH when managing leases")
introduced implicit client lease renewal in nfs4_do_fsinfo(),
which can result in the NFSv4.0 lease to expire on a server side,
and servers returning NFS4ERR_EXPIRED or NFS4ERR_STALE_CLIENTID.

This can easily be reproduced by frequently unmounting a sub-mount,
then stat'ing it to get it mounted again, which will delay or even
completely prevent client from sending RENEW operations if no other
NFS operations are issued. Eventually nfs server will expire client's
lease and return an error on file access or next RENEW.

This can also happen when a sub-mount is automatically unmounted
due to inactivity (after nfs_mountpoint_expiry_timeout), then it is
mounted again via stat(). This can result in a short window during
which client's lease will expire on a server but not on a client.
This specific case was observed on production systems.

This patch removes the implicit lease renewal from nfs4_do_fsinfo().

Fixes: 83ca7f5ab3 ("NFS: Avoid PUTROOTFH when managing leases")
Signed-off-by: Robert Milkowski <rmilkowski@gmail.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-02-04 12:27:55 -05:00

157 lines
4.5 KiB
C

/*
* 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_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);
}
/**
* nfs4_set_lease_period - Sets the lease period on a nfs_client
*
* @clp: pointer to nfs_client
* @lease: new value for lease period
*/
void nfs4_set_lease_period(struct nfs_client *clp,
unsigned long lease)
{
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);
}
/*
* Local variables:
* c-basic-offset: 8
* End:
*/