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/*

 * 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/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>

#include <linux/mutex.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)

static struct hlist_head        nlm_hosts[NLM_HOST_NRHASH];

static unsigned long            next_gc;

static int                      nrhosts;

static DEFINE_MUTEX(nlm_host_mutex);

static void                     nlm_gc_hosts(void);

static struct nsm_handle *      __nsm_find(const struct sockaddr_in *,

                                        const char *, int, int);

static struct nsm_handle *      nsm_find(const struct sockaddr_in *sin,

                                         const char *hostname,

                                         int hostname_len);

/*

 * Common host lookup routine for server & client

 */

static struct nlm_host *

nlm_lookup_host(int server, const struct sockaddr_in *sin,

                int proto, int version, const char *hostname,

                int hostname_len, const struct sockaddr_in *ssin)

{

        struct hlist_head *chain;

        struct hlist_node *pos;

        struct nlm_host *host;

        struct nsm_handle *nsm = NULL;

        int             hash;

        dprintk("lockd: nlm_lookup_host("NIPQUAD_FMT"->"NIPQUAD_FMT

                        ", p=%d, v=%d, my role=%s, name=%.*s)\n",

                        NIPQUAD(ssin->sin_addr.s_addr),

                        NIPQUAD(sin->sin_addr.s_addr), proto, version,

                        server? "server" : "client",

                        hostname_len,

                        hostname? hostname : "<none>");

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

        /* Lock hash table */

        mutex_lock(&nlm_host_mutex);

        if (time_after_eq(jiffies, next_gc))

                nlm_gc_hosts();

        /* We may keep several nlm_host objects for a peer, because each

         * nlm_host is identified by

         * (address, protocol, version, server/client)

         * We could probably simplify this a little by putting all those

         * different NLM rpc_clients into one single nlm_host object.

         * This would allow us to have one nlm_host per address.

         */

        chain = &nlm_hosts[hash];

        hlist_for_each_entry(host, pos, chain, h_hash) {

                if (!nlm_cmp_addr(&host->h_addr, sin))

                        continue;

                /* See if we have an NSM handle for this client */

                if (!nsm)

                        nsm = host->h_nsmhandle;

                if (host->h_proto != proto)

                        continue;

                if (host->h_version != version)

                        continue;

                if (host->h_server != server)

                        continue;

                if (!nlm_cmp_addr(&host->h_saddr, ssin))

                        continue;

                /* Move to head of hash chain. */

                hlist_del(&host->h_hash);

                hlist_add_head(&host->h_hash, chain);

                nlm_get_host(host);

                goto out;

        }

        if (nsm)

                atomic_inc(&nsm->sm_count);

        host = NULL;

        /* Sadly, the host isn't in our hash table yet. See if

         * we have an NSM handle for it. If not, create one.

         */

        if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))

                goto out;

        host = kzalloc(sizeof(*host), GFP_KERNEL);

        if (!host) {

                nsm_release(nsm);

                goto out;

        }

        host->h_name       = nsm->sm_name;

        host->h_addr       = *sin;

        host->h_addr.sin_port = 0;       /* ouch! */

        host->h_saddr      = *ssin;

        host->h_version    = version;

        host->h_proto      = proto;

        host->h_rpcclnt    = NULL;

        mutex_init(&host->h_mutex);

        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);

        init_rwsem(&host->h_rwsem);

        host->h_state      = 0;                  /* pseudo NSM state */

        host->h_nsmstate   = 0;                  /* real NSM state */

        host->h_nsmhandle  = nsm;

        host->h_server     = server;

        hlist_add_head(&host->h_hash, chain);

        INIT_LIST_HEAD(&host->h_lockowners);

        spin_lock_init(&host->h_lock);

        INIT_LIST_HEAD(&host->h_granted);

        INIT_LIST_HEAD(&host->h_reclaim);

        if (++nrhosts > NLM_HOST_MAX)

                next_gc = 0;

out:

        mutex_unlock(&nlm_host_mutex);

        return host;

}

/*

 * Destroy a host

 */

static void

nlm_destroy_host(struct nlm_host *host)

{

        struct rpc_clnt *clnt;

        BUG_ON(!list_empty(&host->h_lockowners));

        BUG_ON(atomic_read(&host->h_count));

        /*

         * Release NSM handle and unmonitor host.

         */

        nsm_unmonitor(host);

        clnt = host->h_rpcclnt;

        if (clnt != NULL)

                rpc_shutdown_client(clnt);

        kfree(host);

}

/*

 * Find an NLM server handle in the cache. If there is none, create it.

 */

struct nlm_host *

nlmclnt_lookup_host(const struct sockaddr_in *sin, int proto, int version,

                        const char *hostname, int hostname_len)

{

        struct sockaddr_in ssin = {0};

        return nlm_lookup_host(0, sin, proto, version,

                               hostname, hostname_len, &ssin);

}

/*

 * Find an NLM client handle in the cache. If there is none, create it.

 */

struct nlm_host *

nlmsvc_lookup_host(struct svc_rqst *rqstp,

                        const char *hostname, int hostname_len)

{

        struct sockaddr_in ssin = {0};

        ssin.sin_addr = rqstp->rq_daddr.addr;

        return nlm_lookup_host(1, svc_addr_in(rqstp),

                               rqstp->rq_prot, rqstp->rq_vers,

                               hostname, hostname_len, &ssin);

}

/*

 * 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("NIPQUAD_FMT"->"NIPQUAD_FMT")\n",

                        NIPQUAD(host->h_saddr.sin_addr),

                        NIPQUAD(host->h_addr.sin_addr));

        /* 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 %ld 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        = (struct sockaddr *)&host->h_addr,

                        .addrsize       = sizeof(host->h_addr),

                        .saddress       = (struct sockaddr *)&host->h_saddr,

                        .timeout        = &timeparms,

                        .servername     = host->h_name,

                        .program        = &nlm_program,

                        .version        = host->h_version,

                        .authflavor     = RPC_AUTH_UNIX,

                        .flags          = (RPC_CLNT_CREATE_HARDRTRY |

                                           RPC_CLNT_CREATE_AUTOBIND),

                };

                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));

                }

        }

}

/*

 * We were notified that the host indicated by address &sin

 * has rebooted.

 * Release all resources held by that peer.

 */

void nlm_host_rebooted(const struct sockaddr_in *sin,

                                const char *hostname, int hostname_len,

                                u32 new_state)

{

        struct hlist_head *chain;

        struct hlist_node *pos;

        struct nsm_handle *nsm;

        struct nlm_host *host;

        dprintk("lockd: nlm_host_rebooted(%s, %u.%u.%u.%u)\n",

                        hostname, NIPQUAD(sin->sin_addr));

        /* Find the NSM handle for this peer */

        if (!(nsm = __nsm_find(sin, hostname, hostname_len, 0)))

                return;

        /* When reclaiming locks on this peer, make sure that

         * we set up a new notification */

        nsm->sm_monitored = 0;

        /* 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 != new_state) {

                                host->h_nsmstate = new_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;

        }

        /* 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;

}

/*

 * Manage NSM handles

 */

static LIST_HEAD(nsm_handles);

static DEFINE_MUTEX(nsm_mutex);

static struct nsm_handle *

__nsm_find(const struct sockaddr_in *sin,

                const char *hostname, int hostname_len,

                int create)

{

        struct nsm_handle *nsm = NULL;

        struct list_head *pos;

        if (!sin)

                return NULL;

        if (hostname && memchr(hostname, '/', hostname_len) != NULL) {

                if (printk_ratelimit()) {

                        printk(KERN_WARNING "Invalid hostname \"%.*s\" "

                                            "in NFS lock request\n",

                                hostname_len, hostname);

                }

                return NULL;

        }

        mutex_lock(&nsm_mutex);

        list_for_each(pos, &nsm_handles) {

                nsm = list_entry(pos, struct nsm_handle, sm_link);

                if (hostname && nsm_use_hostnames) {

                        if (strlen(nsm->sm_name) != hostname_len

                         || memcmp(nsm->sm_name, hostname, hostname_len))

                                continue;

                } else if (!nlm_cmp_addr(&nsm->sm_addr, sin))

                        continue;

                atomic_inc(&nsm->sm_count);

                goto out;

        }

        if (!create) {

                nsm = NULL;

                goto out;

        }

        nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);

        if (nsm != NULL) {

                nsm->sm_addr = *sin;

                nsm->sm_name = (char *) (nsm + 1);

                memcpy(nsm->sm_name, hostname, hostname_len);

                nsm->sm_name[hostname_len] = '\0';

                atomic_set(&nsm->sm_count, 1);

                list_add(&nsm->sm_link, &nsm_handles);

        }

out:

        mutex_unlock(&nsm_mutex);

        return nsm;

}

static struct nsm_handle *

nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)

{

        return __nsm_find(sin, hostname, hostname_len, 1);

}

/*

 * Release an NSM handle

 */

void

nsm_release(struct nsm_handle *nsm)

{

        if (!nsm)

                return;

        if (atomic_dec_and_test(&nsm->sm_count)) {

                mutex_lock(&nsm_mutex);

                if (atomic_read(&nsm->sm_count) == 0) {

                        list_del(&nsm->sm_link);

                        kfree(nsm);

                }

                mutex_unlock(&nsm_mutex);

        }

}