65f27f3844
Pass the work_struct pointer to the work function rather than context data. The work function can use container_of() to work out the data. For the cases where the container of the work_struct may go away the moment the pending bit is cleared, it is made possible to defer the release of the structure by deferring the clearing of the pending bit. To make this work, an extra flag is introduced into the management side of the work_struct. This governs auto-release of the structure upon execution. Ordinarily, the work queue executor would release the work_struct for further scheduling or deallocation by clearing the pending bit prior to jumping to the work function. This means that, unless the driver makes some guarantee itself that the work_struct won't go away, the work function may not access anything else in the work_struct or its container lest they be deallocated.. This is a problem if the auxiliary data is taken away (as done by the last patch). However, if the pending bit is *not* cleared before jumping to the work function, then the work function *may* access the work_struct and its container with no problems. But then the work function must itself release the work_struct by calling work_release(). In most cases, automatic release is fine, so this is the default. Special initiators exist for the non-auto-release case (ending in _NAR). Signed-Off-By: David Howells <dhowells@redhat.com>
148 lines
4.8 KiB
C
148 lines
4.8 KiB
C
/*
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* fs/nfs/nfs4renewd.c
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*
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* Copyright (c) 2002 The Regents of the University of Michigan.
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* All rights reserved.
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*
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* Kendrick Smith <kmsmith@umich.edu>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Implementation of the NFSv4 "renew daemon", which wakes up periodically to
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* send a RENEW, to keep state alive on the server. The daemon is implemented
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* as an rpc_task, not a real kernel thread, so it always runs in rpciod's
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* context. There is one renewd per nfs_server.
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*
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* TODO: If the send queue gets backlogged (e.g., if the server goes down),
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* we will keep filling the queue with periodic RENEW requests. We need a
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* mechanism for ensuring that if renewd successfully sends off a request,
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* then it only wakes up when the request is finished. Maybe use the
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* child task framework of the RPC layer?
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*/
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#include <linux/sched.h>
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#include <linux/smp_lock.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/sunrpc/sched.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/nfs.h>
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#include <linux/nfs4.h>
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#include <linux/nfs_fs.h>
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#include "nfs4_fs.h"
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#include "delegation.h"
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#define NFSDBG_FACILITY NFSDBG_PROC
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void
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nfs4_renew_state(struct work_struct *work)
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{
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struct nfs_client *clp =
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container_of(work, struct nfs_client, cl_renewd.work);
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struct rpc_cred *cred;
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long lease, timeout;
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unsigned long last, now;
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down_read(&clp->cl_sem);
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dprintk("%s: start\n", __FUNCTION__);
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/* Are there any active superblocks? */
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if (list_empty(&clp->cl_superblocks))
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goto out;
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spin_lock(&clp->cl_lock);
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lease = clp->cl_lease_time;
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last = clp->cl_last_renewal;
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now = jiffies;
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timeout = (2 * lease) / 3 + (long)last - (long)now;
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/* Are we close to a lease timeout? */
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if (time_after(now, last + lease/3)) {
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cred = nfs4_get_renew_cred(clp);
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if (cred == NULL) {
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set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
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spin_unlock(&clp->cl_lock);
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nfs_expire_all_delegations(clp);
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goto out;
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}
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spin_unlock(&clp->cl_lock);
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/* Queue an asynchronous RENEW. */
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nfs4_proc_async_renew(clp, cred);
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put_rpccred(cred);
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timeout = (2 * lease) / 3;
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spin_lock(&clp->cl_lock);
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} else
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dprintk("%s: failed to call renewd. Reason: lease not expired \n",
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__FUNCTION__);
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if (timeout < 5 * HZ) /* safeguard */
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timeout = 5 * HZ;
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dprintk("%s: requeueing work. Lease period = %ld\n",
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__FUNCTION__, (timeout + HZ - 1) / HZ);
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cancel_delayed_work(&clp->cl_renewd);
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schedule_delayed_work(&clp->cl_renewd, timeout);
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spin_unlock(&clp->cl_lock);
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out:
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up_read(&clp->cl_sem);
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dprintk("%s: done\n", __FUNCTION__);
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}
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/* Must be called with clp->cl_sem locked for writes */
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void
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nfs4_schedule_state_renewal(struct nfs_client *clp)
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{
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long timeout;
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spin_lock(&clp->cl_lock);
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timeout = (2 * clp->cl_lease_time) / 3 + (long)clp->cl_last_renewal
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- (long)jiffies;
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if (timeout < 5 * HZ)
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timeout = 5 * HZ;
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dprintk("%s: requeueing work. Lease period = %ld\n",
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__FUNCTION__, (timeout + HZ - 1) / HZ);
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cancel_delayed_work(&clp->cl_renewd);
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schedule_delayed_work(&clp->cl_renewd, timeout);
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set_bit(NFS_CS_RENEWD, &clp->cl_res_state);
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spin_unlock(&clp->cl_lock);
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}
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void
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nfs4_renewd_prepare_shutdown(struct nfs_server *server)
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{
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flush_scheduled_work();
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}
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void
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nfs4_kill_renewd(struct nfs_client *clp)
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{
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down_read(&clp->cl_sem);
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cancel_delayed_work(&clp->cl_renewd);
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up_read(&clp->cl_sem);
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flush_scheduled_work();
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}
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/*
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* Local variables:
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* c-basic-offset: 8
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* End:
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*/
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