host.c

Linux中关于远程文件锁定的支持的源代码

 * the source address.
 */
struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp,
				    const char *hostname,
				    const size_t hostname_len)
{
	struct sockaddr_in sin = {
		.sin_family	= AF_INET,
	};
	struct sockaddr_in6 sin6 = {
		.sin6_family	= AF_INET6,
	};
	struct nlm_lookup_host_info ni = {
		.server		= 1,
		.sap		= svc_addr(rqstp),
		.salen		= rqstp->rq_addrlen,
		.protocol	= rqstp->rq_prot,
		.version	= rqstp->rq_vers,
		.hostname	= hostname,
		.hostname_len	= hostname_len,
		.src_len	= rqstp->rq_addrlen,
	};

	dprintk("lockd: %s(host='%*s', vers=%u, proto=%s)\n", __func__,
			(int)hostname_len, hostname, rqstp->rq_vers,
			(rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp"));

	switch (ni.sap->sa_family) {
	case AF_INET:
		sin.sin_addr.s_addr = rqstp->rq_daddr.addr.s_addr;
		ni.src_sap = (struct sockaddr *)&sin;
		break;
	case AF_INET6:
		ipv6_addr_copy(&sin6.sin6_addr, &rqstp->rq_daddr.addr6);
		ni.src_sap = (struct sockaddr *)&sin6;
		break;
	default:
		return NULL;
	}

	return nlm_lookup_host(&ni);
}

/*
 * Create the NLM RPC client for an NLM peer
 */
struct rpc_clnt *
nlm_bind_host(struct nlm_host *host)
{
	struct rpc_clnt	*clnt;

	dprintk("lockd: nlm_bind_host %s (%s)\n",
			host->h_name, host->h_addrbuf);

	/* Lock host handle */
	mutex_lock(&host->h_mutex);

	/* If we've already created an RPC client, check whether
	 * RPC rebind is required
	 */
	if ((clnt = host->h_rpcclnt) != NULL) {
		if (time_after_eq(jiffies, host->h_nextrebind)) {
			rpc_force_rebind(clnt);
			host->h_nextrebind = jiffies + NLM_HOST_REBIND;
			dprintk("lockd: next rebind in %lu jiffies\n",
					host->h_nextrebind - jiffies);
		}
	} else {
		unsigned long increment = nlmsvc_timeout;
		struct rpc_timeout timeparms = {
			.to_initval	= increment,
			.to_increment	= increment,
			.to_maxval	= increment * 6UL,
			.to_retries	= 5U,
		};
		struct rpc_create_args args = {
			.protocol	= host->h_proto,
			.address	= nlm_addr(host),
			.addrsize	= host->h_addrlen,
			.saddress	= nlm_srcaddr(host),
			.timeout	= &timeparms,
			.servername	= host->h_name,
			.program	= &nlm_program,
			.version	= host->h_version,
			.authflavor	= RPC_AUTH_UNIX,
			.flags		= (RPC_CLNT_CREATE_NOPING |
					   RPC_CLNT_CREATE_AUTOBIND),
		};

		/*
		 * lockd retries server side blocks automatically so we want
		 * those to be soft RPC calls. Client side calls need to be
		 * hard RPC tasks.
		 */
		if (!host->h_server)
			args.flags |= RPC_CLNT_CREATE_HARDRTRY;
		if (host->h_noresvport)
			args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;

		clnt = rpc_create(&args);
		if (!IS_ERR(clnt))
			host->h_rpcclnt = clnt;
		else {
			printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
			clnt = NULL;
		}
	}

	mutex_unlock(&host->h_mutex);
	return clnt;
}

/*
 * Force a portmap lookup of the remote lockd port
 */
void
nlm_rebind_host(struct nlm_host *host)
{
	dprintk("lockd: rebind host %s\n", host->h_name);
	if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
		rpc_force_rebind(host->h_rpcclnt);
		host->h_nextrebind = jiffies + NLM_HOST_REBIND;
	}
}

/*
 * Increment NLM host count
 */
struct nlm_host * nlm_get_host(struct nlm_host *host)
{
	if (host) {
		dprintk("lockd: get host %s\n", host->h_name);
		atomic_inc(&host->h_count);
		host->h_expires = jiffies + NLM_HOST_EXPIRE;
	}
	return host;
}

/*
 * Release NLM host after use
 */
void nlm_release_host(struct nlm_host *host)
{
	if (host != NULL) {
		dprintk("lockd: release host %s\n", host->h_name);
		BUG_ON(atomic_read(&host->h_count) < 0);
		if (atomic_dec_and_test(&host->h_count)) {
			BUG_ON(!list_empty(&host->h_lockowners));
			BUG_ON(!list_empty(&host->h_granted));
			BUG_ON(!list_empty(&host->h_reclaim));
		}
	}
}

/**
 * nlm_host_rebooted - Release all resources held by rebooted host
 * @info: pointer to decoded results of NLM_SM_NOTIFY call
 *
 * We were notified that the specified host has rebooted.  Release
 * all resources held by that peer.
 */
void nlm_host_rebooted(const struct nlm_reboot *info)
{
	struct hlist_head *chain;
	struct hlist_node *pos;
	struct nsm_handle *nsm;
	struct nlm_host	*host;

	nsm = nsm_reboot_lookup(info);
	if (unlikely(nsm == NULL))
		return;

	/* Mark all hosts tied to this NSM state as having rebooted.
	 * We run the loop repeatedly, because we drop the host table
	 * lock for this.
	 * To avoid processing a host several times, we match the nsmstate.
	 */
again:	mutex_lock(&nlm_host_mutex);
	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
		hlist_for_each_entry(host, pos, chain, h_hash) {
			if (host->h_nsmhandle == nsm
			 && host->h_nsmstate != info->state) {
				host->h_nsmstate = info->state;
				host->h_state++;

				nlm_get_host(host);
				mutex_unlock(&nlm_host_mutex);

				if (host->h_server) {
					/* We're server for this guy, just ditch
					 * all the locks he held. */
					nlmsvc_free_host_resources(host);
				} else {
					/* He's the server, initiate lock recovery. */
					nlmclnt_recovery(host);
				}

				nlm_release_host(host);
				goto again;
			}
		}
	}

	mutex_unlock(&nlm_host_mutex);
}

/*
 * Shut down the hosts module.
 * Note that this routine is called only at server shutdown time.
 */
void
nlm_shutdown_hosts(void)
{
	struct hlist_head *chain;
	struct hlist_node *pos;
	struct nlm_host	*host;

	dprintk("lockd: shutting down host module\n");
	mutex_lock(&nlm_host_mutex);

	/* First, make all hosts eligible for gc */
	dprintk("lockd: nuking all hosts...\n");
	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
		hlist_for_each_entry(host, pos, chain, h_hash) {
			host->h_expires = jiffies - 1;
			if (host->h_rpcclnt) {
				rpc_shutdown_client(host->h_rpcclnt);
				host->h_rpcclnt = NULL;
			}
		}
	}

	/* Then, perform a garbage collection pass */
	nlm_gc_hosts();
	mutex_unlock(&nlm_host_mutex);

	/* complain if any hosts are left */
	if (nrhosts) {
		printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
		dprintk("lockd: %d hosts left:\n", nrhosts);
		for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
			hlist_for_each_entry(host, pos, chain, h_hash) {
				dprintk("       %s (cnt %d use %d exp %ld)\n",
					host->h_name, atomic_read(&host->h_count),
					host->h_inuse, host->h_expires);
			}
		}
	}
}

/*
 * Garbage collect any unused NLM hosts.
 * This GC combines reference counting for async operations with
 * mark & sweep for resources held by remote clients.
 */
static void
nlm_gc_hosts(void)
{
	struct hlist_head *chain;
	struct hlist_node *pos, *next;
	struct nlm_host	*host;

	dprintk("lockd: host garbage collection\n");
	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
		hlist_for_each_entry(host, pos, chain, h_hash)
			host->h_inuse = 0;
	}

	/* Mark all hosts that hold locks, blocks or shares */
	nlmsvc_mark_resources();

	for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
		hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
			if (atomic_read(&host->h_count) || host->h_inuse
			 || time_before(jiffies, host->h_expires)) {
				dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
					host->h_name, atomic_read(&host->h_count),
					host->h_inuse, host->h_expires);
				continue;
			}
			dprintk("lockd: delete host %s\n", host->h_name);
			hlist_del_init(&host->h_hash);

			nlm_destroy_host(host);
			nrhosts--;
		}
	}

	next_gc = jiffies + NLM_HOST_COLLECT;
}