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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         init_MUTEX(&host->h_sema);
 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         host->h_state      = 0;                 /* pseudo NSM state */
 121         host->h_nsmstate   = 0;                 /* real NSM state */
 122         host->h_server     = server;
 123         host->h_next       = nlm_hosts[hash];
 124         nlm_hosts[hash]    = host;
 125         INIT_LIST_HEAD(&host->h_lockowners);
 126         spin_lock_init(&host->h_lock);
 127         INIT_LIST_HEAD(&host->h_granted);
 128         INIT_LIST_HEAD(&host->h_reclaim);
 129
 130         if (++nrhosts > NLM_HOST_MAX)
 131                 next_gc = 0;
 132
 133 nohost:
 134         mutex_unlock(&nlm_host_mutex);
 135         return host;
 136 }
 137
 138 struct nlm_host *
 139 nlm_find_client(void)
 140 {
 141         /* find a nlm_host for a client for which h_killed == 0.
 142          * and return it
 143          */
 144         int hash;
 145         mutex_lock(&nlm_host_mutex);
 146         for (hash = 0 ; hash < NLM_HOST_NRHASH; hash++) {
 147                 struct nlm_host *host, **hp;
 148                 for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
 149                         if (host->h_server &&
 150                             host->h_killed == 0) {
 151                                 nlm_get_host(host);
 152                                 mutex_unlock(&nlm_host_mutex);
 153                                 return host;
 154                         }
 155                 }
 156         }
 157         mutex_unlock(&nlm_host_mutex);
 158         return NULL;
 159 }
 160
 161
 162 /*
 163  * Create the NLM RPC client for an NLM peer
 164  */
 165 struct rpc_clnt *
 166 nlm_bind_host(struct nlm_host *host)
 167 {
 168         struct rpc_clnt *clnt;
 169         struct rpc_xprt *xprt;
 170
 171         dprintk("lockd: nlm_bind_host(%08x)\n",
 172                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 173
 174         /* Lock host handle */
 175         down(&host->h_sema);
 176
 177         /* If we've already created an RPC client, check whether
 178          * RPC rebind is required
 179          */
 180         if ((clnt = host->h_rpcclnt) != NULL) {
 181                 xprt = clnt->cl_xprt;
 182                 if (time_after_eq(jiffies, host->h_nextrebind)) {
 183                         rpc_force_rebind(clnt);
 184                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 185                         dprintk("lockd: next rebind in %ld jiffies\n",
 186                                         host->h_nextrebind - jiffies);
 187                 }
 188         } else {
 189                 xprt = xprt_create_proto(host->h_proto, &host->h_addr, NULL);
 190                 if (IS_ERR(xprt))
 191                         goto forgetit;
 192
 193                 xprt_set_timeout(&xprt->timeout, 5, nlmsvc_timeout);
 194                 xprt->resvport = 1;     /* NLM requires a reserved port */
 195
 196                 /* Existing NLM servers accept AUTH_UNIX only */
 197                 clnt = rpc_new_client(xprt, host->h_name, &nlm_program,
 198                                         host->h_version, RPC_AUTH_UNIX);
 199                 if (IS_ERR(clnt))
 200                         goto forgetit;
 201                 clnt->cl_autobind = 1;  /* turn on pmap queries */
 202                 clnt->cl_softrtry = 1; /* All queries are soft */
 203
 204                 host->h_rpcclnt = clnt;
 205         }
 206
 207         up(&host->h_sema);
 208         return clnt;
 209
 210 forgetit:
 211         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 212         up(&host->h_sema);
 213         return NULL;
 214 }
 215
 216 /*
 217  * Force a portmap lookup of the remote lockd port
 218  */
 219 void
 220 nlm_rebind_host(struct nlm_host *host)
 221 {
 222         dprintk("lockd: rebind host %s\n", host->h_name);
 223         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 224                 rpc_force_rebind(host->h_rpcclnt);
 225                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 226         }
 227 }
 228
 229 /*
 230  * Increment NLM host count
 231  */
 232 struct nlm_host * nlm_get_host(struct nlm_host *host)
 233 {
 234         if (host) {
 235                 dprintk("lockd: get host %s\n", host->h_name);
 236                 atomic_inc(&host->h_count);
 237                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 238         }
 239         return host;
 240 }
 241
 242 /*
 243  * Release NLM host after use
 244  */
 245 void nlm_release_host(struct nlm_host *host)
 246 {
 247         if (host != NULL) {
 248                 dprintk("lockd: release host %s\n", host->h_name);
 249                 BUG_ON(atomic_read(&host->h_count) < 0);
 250                 if (atomic_dec_and_test(&host->h_count)) {
 251                         BUG_ON(!list_empty(&host->h_lockowners));
 252                         BUG_ON(!list_empty(&host->h_granted));
 253                         BUG_ON(!list_empty(&host->h_reclaim));
 254                 }
 255         }
 256 }
 257
 258 /*
 259  * Shut down the hosts module.
 260  * Note that this routine is called only at server shutdown time.
 261  */
 262 void
 263 nlm_shutdown_hosts(void)
 264 {
 265         struct nlm_host *host;
 266         int             i;
 267
 268         dprintk("lockd: shutting down host module\n");
 269         mutex_lock(&nlm_host_mutex);
 270
 271         /* First, make all hosts eligible for gc */
 272         dprintk("lockd: nuking all hosts...\n");
 273         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 274                 for (host = nlm_hosts[i]; host; host = host->h_next)
 275                         host->h_expires = jiffies - 1;
 276         }
 277
 278         /* Then, perform a garbage collection pass */
 279         nlm_gc_hosts();
 280         mutex_unlock(&nlm_host_mutex);
 281
 282         /* complain if any hosts are left */
 283         if (nrhosts) {
 284                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 285                 dprintk("lockd: %d hosts left:\n", nrhosts);
 286                 for (i = 0; i < NLM_HOST_NRHASH; i++) {
 287                         for (host = nlm_hosts[i]; host; host = host->h_next) {
 288                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 289                                         host->h_name, atomic_read(&host->h_count),
 290                                         host->h_inuse, host->h_expires);
 291                         }
 292                 }
 293         }
 294 }
 295
 296 /*
 297  * Garbage collect any unused NLM hosts.
 298  * This GC combines reference counting for async operations with
 299  * mark & sweep for resources held by remote clients.
 300  */
 301 static void
 302 nlm_gc_hosts(void)
 303 {
 304         struct nlm_host **q, *host;
 305         struct rpc_clnt *clnt;
 306         int             i;
 307
 308         dprintk("lockd: host garbage collection\n");
 309         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 310                 for (host = nlm_hosts[i]; host; host = host->h_next)
 311                         host->h_inuse = 0;
 312         }
 313
 314         /* Mark all hosts that hold locks, blocks or shares */
 315         nlmsvc_mark_resources();
 316
 317         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 318                 q = &nlm_hosts[i];
 319                 while ((host = *q) != NULL) {
 320                         if (atomic_read(&host->h_count) || host->h_inuse
 321                          || time_before(jiffies, host->h_expires)) {
 322                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 323                                         host->h_name, atomic_read(&host->h_count),
 324                                         host->h_inuse, host->h_expires);
 325                                 q = &host->h_next;
 326                                 continue;
 327                         }
 328                         dprintk("lockd: delete host %s\n", host->h_name);
 329                         *q = host->h_next;
 330                         /* Don't unmonitor hosts that have been invalidated */
 331                         if (host->h_monitored && !host->h_killed)
 332                                 nsm_unmonitor(host);
 333                         if ((clnt = host->h_rpcclnt) != NULL) {
 334                                 if (atomic_read(&clnt->cl_users)) {
 335                                         printk(KERN_WARNING
 336                                                 "lockd: active RPC handle\n");
 337                                         clnt->cl_dead = 1;
 338                                 } else {
 339                                         rpc_destroy_client(host->h_rpcclnt);
 340                                 }
 341                         }
 342                         kfree(host);
 343                         nrhosts--;
 344                 }
 345         }
 346
 347         next_gc = jiffies + NLM_HOST_COLLECT;
 348 }
 349