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   1 /*
   2  * linux/fs/lockd/host.c
   3  *
   4  * Management for NLM peer hosts. The nlm_host struct is shared
   5  * between client and server implementation. The only reason to
   6  * do so is to reduce code bloat.
   7  *
   8  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/in.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/sunrpc/svc.h>
  17 #include <linux/lockd/lockd.h>
  18 #include <linux/lockd/sm_inter.h>
  19 #include <linux/mutex.h>
  20
  21
  22 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
  23 #define NLM_HOST_MAX            64
  24 #define NLM_HOST_NRHASH         32
  25 #define NLM_ADDRHASH(addr)      (ntohl(addr) & (NLM_HOST_NRHASH-1))
  26 #define NLM_HOST_REBIND         (60 * HZ)
  27 #define NLM_HOST_EXPIRE         ((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
  28 #define NLM_HOST_COLLECT        ((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
  29 #define NLM_HOST_ADDR(sv)       (&(sv)->s_nlmclnt->cl_xprt->addr)
  30
  31 static struct nlm_host *        nlm_hosts[NLM_HOST_NRHASH];
  32 static unsigned long            next_gc;
  33 static int                      nrhosts;
  34 static DEFINE_MUTEX(nlm_host_mutex);
  35
  36
  37 static void                     nlm_gc_hosts(void);
  38
  39 /*
  40  * Find an NLM server handle in the cache. If there is none, create it.
  41  */
  42 struct nlm_host *
  43 nlmclnt_lookup_host(struct sockaddr_in *sin, int proto, int version)
  44 {
  45         return nlm_lookup_host(0, sin, proto, version);
  46 }
  47
  48 /*
  49  * Find an NLM client handle in the cache. If there is none, create it.
  50  */
  51 struct nlm_host *
  52 nlmsvc_lookup_host(struct svc_rqst *rqstp)
  53 {
  54         return nlm_lookup_host(1, &rqstp->rq_addr,
  55                                rqstp->rq_prot, rqstp->rq_vers);
  56 }
  57
  58 /*
  59  * Common host lookup routine for server & client
  60  */
  61 struct nlm_host *
  62 nlm_lookup_host(int server, struct sockaddr_in *sin,
  63                                         int proto, int version)
  64 {
  65         struct nlm_host *host, **hp;
  66         u32             addr;
  67         int             hash;
  68
  69         dprintk("lockd: nlm_lookup_host(%08x, p=%d, v=%d)\n",
  70                         (unsigned)(sin? ntohl(sin->sin_addr.s_addr) : 0), proto, version);
  71
  72         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  73
  74         /* Lock hash table */
  75         mutex_lock(&nlm_host_mutex);
  76
  77         if (time_after_eq(jiffies, next_gc))
  78                 nlm_gc_hosts();
  79
  80         for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
  81                 if (host->h_proto != proto)
  82                         continue;
  83                 if (host->h_version != version)
  84                         continue;
  85                 if (host->h_server != server)
  86                         continue;
  87
  88                 if (nlm_cmp_addr(&host->h_addr, sin)) {
  89                         if (hp != nlm_hosts + hash) {
  90                                 *hp = host->h_next;
  91                                 host->h_next = nlm_hosts[hash];
  92                                 nlm_hosts[hash] = host;
  93                         }
  94                         nlm_get_host(host);
  95                         mutex_unlock(&nlm_host_mutex);
  96                         return host;
  97                 }
  98         }
  99
 100         /* Ooops, no host found, create it */
 101         dprintk("lockd: creating host entry\n");
 102
 103         if (!(host = (struct nlm_host *) kmalloc(sizeof(*host), GFP_KERNEL)))
 104                 goto nohost;
 105         memset(host, 0, sizeof(*host));
 106
 107         addr = sin->sin_addr.s_addr;
 108         sprintf(host->h_name, "%u.%u.%u.%u", NIPQUAD(addr));
 109
 110         host->h_addr       = *sin;
 111         host->h_addr.sin_port = 0;      /* ouch! */
 112         host->h_version    = version;
 113         host->h_proto      = proto;
 114         host->h_rpcclnt    = NULL;
 115         mutex_init(&host->h_mutex);
 116         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 117         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 118         atomic_set(&host->h_count, 1);
 119         init_waitqueue_head(&host->h_gracewait);
 120         init_rwsem(&host->h_rwsem);
 121         host->h_state      = 0;                 /* pseudo NSM state */
 122         host->h_nsmstate   = 0;                 /* real NSM state */
 123         host->h_server     = server;
 124         host->h_next       = nlm_hosts[hash];
 125         nlm_hosts[hash]    = host;
 126         INIT_LIST_HEAD(&host->h_lockowners);
 127         spin_lock_init(&host->h_lock);
 128         INIT_LIST_HEAD(&host->h_granted);
 129         INIT_LIST_HEAD(&host->h_reclaim);
 130
 131         if (++nrhosts > NLM_HOST_MAX)
 132                 next_gc = 0;
 133
 134 nohost:
 135         mutex_unlock(&nlm_host_mutex);
 136         return host;
 137 }
 138
 139 struct nlm_host *
 140 nlm_find_client(void)
 141 {
 142         /* find a nlm_host for a client for which h_killed == 0.
 143          * and return it
 144          */
 145         int hash;
 146         mutex_lock(&nlm_host_mutex);
 147         for (hash = 0 ; hash < NLM_HOST_NRHASH; hash++) {
 148                 struct nlm_host *host, **hp;
 149                 for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
 150                         if (host->h_server &&
 151                             host->h_killed == 0) {
 152                                 nlm_get_host(host);
 153                                 mutex_unlock(&nlm_host_mutex);
 154                                 return host;
 155                         }
 156                 }
 157         }
 158         mutex_unlock(&nlm_host_mutex);
 159         return NULL;
 160 }
 161
 162
 163 /*
 164  * Create the NLM RPC client for an NLM peer
 165  */
 166 struct rpc_clnt *
 167 nlm_bind_host(struct nlm_host *host)
 168 {
 169         struct rpc_clnt *clnt;
 170         struct rpc_xprt *xprt;
 171
 172         dprintk("lockd: nlm_bind_host(%08x)\n",
 173                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 174
 175         /* Lock host handle */
 176         mutex_lock(&host->h_mutex);
 177
 178         /* If we've already created an RPC client, check whether
 179          * RPC rebind is required
 180          */
 181         if ((clnt = host->h_rpcclnt) != NULL) {
 182                 xprt = clnt->cl_xprt;
 183                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 184                         rpc_force_rebind(clnt);
 185                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 186                         dprintk("lockd: next rebind in %ld jiffies\n",
 187                                         host->h_nextrebind - jiffies);
 188                 }
 189         } else {
 190                 xprt = xprt_create_proto(host->h_proto, &host->h_addr, NULL);
 191                 if (IS_ERR(xprt))
 192                         goto forgetit;
 193
 194                 xprt_set_timeout(&xprt->timeout, 5, nlmsvc_timeout);
 195                 xprt->resvport = 1;     /* NLM requires a reserved port */
 196
 197                 /* Existing NLM servers accept AUTH_UNIX only */
 198                 clnt = rpc_new_client(xprt, host->h_name, &nlm_program,
 199                                         host->h_version, RPC_AUTH_UNIX);
 200                 if (IS_ERR(clnt))
 201                         goto forgetit;
 202                 clnt->cl_autobind = 1;  /* turn on pmap queries */
 203                 clnt->cl_softrtry = 1; /* All queries are soft */
 204
 205                 host->h_rpcclnt = clnt;
 206         }
 207
 208         mutex_unlock(&host->h_mutex);
 209         return clnt;
 210
 211 forgetit:
 212         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 213         mutex_unlock(&host->h_mutex);
 214         return NULL;
 215 }
 216
 217 /*
 218  * Force a portmap lookup of the remote lockd port
 219  */
 220 void
 221 nlm_rebind_host(struct nlm_host *host)
 222 {
 223         dprintk("lockd: rebind host %s\n", host->h_name);
 224         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 225                 rpc_force_rebind(host->h_rpcclnt);
 226                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 227         }
 228 }
 229
 230 /*
 231  * Increment NLM host count
 232  */
 233 struct nlm_host * nlm_get_host(struct nlm_host *host)
 234 {
 235         if (host) {
 236                 dprintk("lockd: get host %s\n", host->h_name);
 237                 atomic_inc(&host->h_count);
 238                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 239         }
 240         return host;
 241 }
 242
 243 /*
 244  * Release NLM host after use
 245  */
 246 void nlm_release_host(struct nlm_host *host)
 247 {
 248         if (host != NULL) {
 249                 dprintk("lockd: release host %s\n", host->h_name);
 250                 BUG_ON(atomic_read(&host->h_count) < 0);
 251                 if (atomic_dec_and_test(&host->h_count)) {
 252                         BUG_ON(!list_empty(&host->h_lockowners));
 253                         BUG_ON(!list_empty(&host->h_granted));
 254                         BUG_ON(!list_empty(&host->h_reclaim));
 255                 }
 256         }
 257 }
 258
 259 /*
 260  * Shut down the hosts module.
 261  * Note that this routine is called only at server shutdown time.
 262  */
 263 void
 264 nlm_shutdown_hosts(void)
 265 {
 266         struct nlm_host *host;
 267         int             i;
 268
 269         dprintk("lockd: shutting down host module\n");
 270         mutex_lock(&nlm_host_mutex);
 271
 272         /* First, make all hosts eligible for gc */
 273         dprintk("lockd: nuking all hosts...\n");
 274         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 275                 for (host = nlm_hosts[i]; host; host = host->h_next)
 276                         host->h_expires = jiffies - 1;
 277         }
 278
 279         /* Then, perform a garbage collection pass */
 280         nlm_gc_hosts();
 281         mutex_unlock(&nlm_host_mutex);
 282
 283         /* complain if any hosts are left */
 284         if (nrhosts) {
 285                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 286                 dprintk("lockd: %d hosts left:\n", nrhosts);
 287                 for (i = 0; i < NLM_HOST_NRHASH; i++) {
 288                         for (host = nlm_hosts[i]; host; host = host->h_next) {
 289                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 290                                         host->h_name, atomic_read(&host->h_count),
 291                                         host->h_inuse, host->h_expires);
 292                         }
 293                 }
 294         }
 295 }
 296
 297 /*
 298  * Garbage collect any unused NLM hosts.
 299  * This GC combines reference counting for async operations with
 300  * mark & sweep for resources held by remote clients.
 301  */
 302 static void
 303 nlm_gc_hosts(void)
 304 {
 305         struct nlm_host **q, *host;
 306         struct rpc_clnt *clnt;
 307         int             i;
 308
 309         dprintk("lockd: host garbage collection\n");
 310         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 311                 for (host = nlm_hosts[i]; host; host = host->h_next)
 312                         host->h_inuse = 0;
 313         }
 314
 315         /* Mark all hosts that hold locks, blocks or shares */
 316         nlmsvc_mark_resources();
 317
 318         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 319                 q = &nlm_hosts[i];
 320                 while ((host = *q) != NULL) {
 321                         if (atomic_read(&host->h_count) || host->h_inuse
 322                          || time_before(jiffies, host->h_expires)) {
 323                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 324                                         host->h_name, atomic_read(&host->h_count),
 325                                         host->h_inuse, host->h_expires);
 326                                 q = &host->h_next;
 327                                 continue;
 328                         }
 329                         dprintk("lockd: delete host %s\n", host->h_name);
 330                         *q = host->h_next;
 331                         /* Don't unmonitor hosts that have been invalidated */
 332                         if (host->h_monitored && !host->h_killed)
 333                                 nsm_unmonitor(host);
 334                         if ((clnt = host->h_rpcclnt) != NULL) {
 335                                 if (atomic_read(&clnt->cl_users)) {
 336                                         printk(KERN_WARNING
 337                                                 "lockd: active RPC handle\n");
 338                                         clnt->cl_dead = 1;
 339                                 } else {
 340                                         rpc_destroy_client(host->h_rpcclnt);
 341                                 }
 342                         }
 343                         kfree(host);
 344                         nrhosts--;
 345                 }
 346         }
 347
 348         next_gc = jiffies + NLM_HOST_COLLECT;
 349 }
 350