Merge master.kernel.org:/home/rmk/linux-2.6-arm

[deliverable/linux.git] / fs / lockd / host.c

/*
 * linux/fs/lockd/host.c
 *
 * Management for NLM peer hosts. The nlm_host struct is shared
 * between client and server implementation. The only reason to
 * do so is to reduce code bloat.
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/types.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/sm_inter.h>


#define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
#define NLM_HOST_MAX            64
#define NLM_HOST_NRHASH         32
#define NLM_ADDRHASH(addr)      (ntohl(addr) & (NLM_HOST_NRHASH-1))
#define NLM_HOST_REBIND         (60 * HZ)
#define NLM_HOST_EXPIRE         ((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
#define NLM_HOST_COLLECT        ((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
#define NLM_HOST_ADDR(sv)       (&(sv)->s_nlmclnt->cl_xprt->addr)

static struct nlm_host *        nlm_hosts[NLM_HOST_NRHASH];
static unsigned long            next_gc;
static int                      nrhosts;
static DECLARE_MUTEX(nlm_host_sema);


static void                     nlm_gc_hosts(void);

/*
 * Find an NLM server handle in the cache. If there is none, create it.
 */
struct nlm_host *
nlmclnt_lookup_host(struct sockaddr_in *sin, int proto, int version)
{
        return nlm_lookup_host(0, sin, proto, version);
}

/*
 * Find an NLM client handle in the cache. If there is none, create it.
 */
struct nlm_host *
nlmsvc_lookup_host(struct svc_rqst *rqstp)
{
        return nlm_lookup_host(1, &rqstp->rq_addr,
                               rqstp->rq_prot, rqstp->rq_vers);
}

/*
 * Common host lookup routine for server & client
 */
struct nlm_host *
nlm_lookup_host(int server, struct sockaddr_in *sin,
                                        int proto, int version)
{
        struct nlm_host *host, **hp;
        u32             addr;
        int             hash;

        dprintk("lockd: nlm_lookup_host(%08x, p=%d, v=%d)\n",
                        (unsigned)(sin? ntohl(sin->sin_addr.s_addr) : 0), proto, version);

        hash = NLM_ADDRHASH(sin->sin_addr.s_addr);

        /* Lock hash table */
        down(&nlm_host_sema);

        if (time_after_eq(jiffies, next_gc))
                nlm_gc_hosts();

        for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
                if (host->h_proto != proto)
                        continue;
                if (host->h_version != version)
                        continue;
                if (host->h_server != server)
                        continue;

                if (nlm_cmp_addr(&host->h_addr, sin)) {
                        if (hp != nlm_hosts + hash) {
                                *hp = host->h_next;
                                host->h_next = nlm_hosts[hash];
                                nlm_hosts[hash] = host;
                        }
                        nlm_get_host(host);
                        up(&nlm_host_sema);
                        return host;
                }
        }

        /* Ooops, no host found, create it */
        dprintk("lockd: creating host entry\n");

        if (!(host = (struct nlm_host *) kmalloc(sizeof(*host), GFP_KERNEL)))
                goto nohost;
        memset(host, 0, sizeof(*host));

        addr = sin->sin_addr.s_addr;
        sprintf(host->h_name, "%u.%u.%u.%u", NIPQUAD(addr));

        host->h_addr       = *sin;
        host->h_addr.sin_port = 0;      /* ouch! */
        host->h_version    = version;
        host->h_proto      = proto;
        host->h_rpcclnt    = NULL;
        init_MUTEX(&host->h_sema);
        host->h_nextrebind = jiffies + NLM_HOST_REBIND;
        host->h_expires    = jiffies + NLM_HOST_EXPIRE;
        atomic_set(&host->h_count, 1);
        init_waitqueue_head(&host->h_gracewait);
        host->h_state      = 0;                 /* pseudo NSM state */
        host->h_nsmstate   = 0;                 /* real NSM state */
        host->h_server     = server;
        host->h_next       = nlm_hosts[hash];
        nlm_hosts[hash]    = host;
        INIT_LIST_HEAD(&host->h_lockowners);
        spin_lock_init(&host->h_lock);

        if (++nrhosts > NLM_HOST_MAX)
                next_gc = 0;

nohost:
        up(&nlm_host_sema);
        return host;
}

struct nlm_host *
nlm_find_client(void)
{
        /* find a nlm_host for a client for which h_killed == 0.
         * and return it
         */
        int hash;
        down(&nlm_host_sema);
        for (hash = 0 ; hash < NLM_HOST_NRHASH; hash++) {
                struct nlm_host *host, **hp;
                for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
                        if (host->h_server &&
                            host->h_killed == 0) {
                                nlm_get_host(host);
                                up(&nlm_host_sema);
                                return host;
                        }
                }
        }
        up(&nlm_host_sema);
        return NULL;
}

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

        dprintk("lockd: nlm_bind_host(%08x)\n",
                        (unsigned)ntohl(host->h_addr.sin_addr.s_addr));

        /* Lock host handle */
        down(&host->h_sema);

        /* If we've already created an RPC client, check whether
         * RPC rebind is required
         * Note: why keep rebinding if we're on a tcp connection?
         */
        if ((clnt = host->h_rpcclnt) != NULL) {
                xprt = clnt->cl_xprt;
                if (!xprt->stream && time_after_eq(jiffies, host->h_nextrebind)) {
                        clnt->cl_port = 0;
                        host->h_nextrebind = jiffies + NLM_HOST_REBIND;
                        dprintk("lockd: next rebind in %ld jiffies\n",
                                        host->h_nextrebind - jiffies);
                }
        } else {
                xprt = xprt_create_proto(host->h_proto, &host->h_addr, NULL);
                if (IS_ERR(xprt))
                        goto forgetit;

                xprt_set_timeout(&xprt->timeout, 5, nlmsvc_timeout);
                xprt->nocong = 1;       /* No congestion control for NLM */
                xprt->resvport = 1;     /* NLM requires a reserved port */

                /* Existing NLM servers accept AUTH_UNIX only */
                clnt = rpc_create_client(xprt, host->h_name, &nlm_program,
                                        host->h_version, RPC_AUTH_UNIX);
                if (IS_ERR(clnt))
                        goto forgetit;
                clnt->cl_autobind = 1;  /* turn on pmap queries */

                host->h_rpcclnt = clnt;
        }

        up(&host->h_sema);
        return clnt;

forgetit:
        printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
        up(&host->h_sema);
        return NULL;
}

/*
 * 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)) {
                host->h_rpcclnt->cl_port = 0;
                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);
                atomic_dec(&host->h_count);
                BUG_ON(atomic_read(&host->h_count) < 0);
        }
}

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

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

        /* First, make all hosts eligible for gc */
        dprintk("lockd: nuking all hosts...\n");
        for (i = 0; i < NLM_HOST_NRHASH; i++) {
                for (host = nlm_hosts[i]; host; host = host->h_next)
                        host->h_expires = jiffies - 1;
        }

        /* Then, perform a garbage collection pass */
        nlm_gc_hosts();
        up(&nlm_host_sema);

        /* 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 (i = 0; i < NLM_HOST_NRHASH; i++) {
                        for (host = nlm_hosts[i]; host; host = host->h_next) {
                                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 nlm_host **q, *host;
        struct rpc_clnt *clnt;
        int             i;

        dprintk("lockd: host garbage collection\n");
        for (i = 0; i < NLM_HOST_NRHASH; i++) {
                for (host = nlm_hosts[i]; host; host = host->h_next)
                        host->h_inuse = 0;
        }

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

        for (i = 0; i < NLM_HOST_NRHASH; i++) {
                q = &nlm_hosts[i];
                while ((host = *q) != NULL) {
                        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);
                                q = &host->h_next;
                                continue;
                        }
                        dprintk("lockd: delete host %s\n", host->h_name);
                        *q = host->h_next;
                        /* Don't unmonitor hosts that have been invalidated */
                        if (host->h_monitored && !host->h_killed)
                                nsm_unmonitor(host);
                        if ((clnt = host->h_rpcclnt) != NULL) {
                                if (atomic_read(&clnt->cl_users)) {
                                        printk(KERN_WARNING
                                                "lockd: active RPC handle\n");
                                        clnt->cl_dead = 1;
                                } else {
                                        rpc_destroy_client(host->h_rpcclnt);
                                }
                        }
                        BUG_ON(!list_empty(&host->h_lockowners));
                        kfree(host);
                        nrhosts--;
                }
        }

        next_gc = jiffies + NLM_HOST_COLLECT;
}