fs/lockd/host.c

   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
  20
  21 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
  22 #define NLM_HOST_MAX            64
  23 #define NLM_HOST_NRHASH         32
  24 #define NLM_ADDRHASH(addr)      (ntohl(addr) & (NLM_HOST_NRHASH-1))
  25 #define NLM_HOST_REBIND         (60 * HZ)
  26 #define NLM_HOST_EXPIRE         ((nrhosts > NLM_HOST_MAX)? 300 * HZ : 120 * HZ)
  27 #define NLM_HOST_COLLECT        ((nrhosts > NLM_HOST_MAX)? 120 * HZ :  60 * HZ)
  28 #define NLM_HOST_ADDR(sv)       (&(sv)->s_nlmclnt->cl_xprt->addr)
  29
  30 static struct nlm_host *        nlm_hosts[NLM_HOST_NRHASH];
  31 static unsigned long            next_gc;
  32 static int                      nrhosts;
  33 static DECLARE_MUTEX(nlm_host_sema);
  34
  35
  36 static void                     nlm_gc_hosts(void);
  37
  38 /*
  39  * Find an NLM server handle in the cache. If there is none, create it.
  40  */
  41 struct nlm_host *
  42 nlmclnt_lookup_host(struct sockaddr_in *sin, int proto, int version)
  43 {
  44         return nlm_lookup_host(0, sin, proto, version);
  45 }
  46
  47 /*
  48  * Find an NLM client handle in the cache. If there is none, create it.
  49  */
  50 struct nlm_host *
  51 nlmsvc_lookup_host(struct svc_rqst *rqstp)
  52 {
  53         return nlm_lookup_host(1, &rqstp->rq_addr,
  54                                rqstp->rq_prot, rqstp->rq_vers);
  55 }
  56
  57 /*
  58  * Common host lookup routine for server & client
  59  */
  60 struct nlm_host *
  61 nlm_lookup_host(int server, struct sockaddr_in *sin,
  62                                         int proto, int version)
  63 {
  64         struct nlm_host *host, **hp;
  65         u32             addr;
  66         int             hash;
  67
  68         dprintk("lockd: nlm_lookup_host(%08x, p=%d, v=%d)\n",
  69                         (unsigned)(sin? ntohl(sin->sin_addr.s_addr) : 0), proto, version);
  70
  71         hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
  72
  73         /* Lock hash table */
  74         down(&nlm_host_sema);
  75
  76         if (time_after_eq(jiffies, next_gc))
  77                 nlm_gc_hosts();
  78
  79         for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
  80                 if (host->h_proto != proto)
  81                         continue;
  82                 if (host->h_version != version)
  83                         continue;
  84                 if (host->h_server != server)
  85                         continue;
  86
  87                 if (nlm_cmp_addr(&host->h_addr, sin)) {
  88                         if (hp != nlm_hosts + hash) {
  89                                 *hp = host->h_next;
  90                                 host->h_next = nlm_hosts[hash];
  91                                 nlm_hosts[hash] = host;
  92                         }
  93                         nlm_get_host(host);
  94                         up(&nlm_host_sema);
  95                         return host;
  96                 }
  97         }
  98
  99         /* Ooops, no host found, create it */
 100         dprintk("lockd: creating host entry\n");
 101
 102         if (!(host = (struct nlm_host *) kmalloc(sizeof(*host), GFP_KERNEL)))
 103                 goto nohost;
 104         memset(host, 0, sizeof(*host));
 105
 106         addr = sin->sin_addr.s_addr;
 107         sprintf(host->h_name, "%u.%u.%u.%u", NIPQUAD(addr));
 108
 109         host->h_addr       = *sin;
 110         host->h_addr.sin_port = 0;      /* ouch! */
 111         host->h_version    = version;
 112         host->h_proto      = proto;
 113         host->h_rpcclnt    = NULL;
 114         init_MUTEX(&host->h_sema);
 115         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 116         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
 117         atomic_set(&host->h_count, 1);
 118         init_waitqueue_head(&host->h_gracewait);
 119         host->h_state      = 0;                 /* pseudo NSM state */
 120         host->h_nsmstate   = 0;                 /* real NSM state */
 121         host->h_server     = server;
 122         host->h_next       = nlm_hosts[hash];
 123         nlm_hosts[hash]    = host;
 124         INIT_LIST_HEAD(&host->h_lockowners);
 125         spin_lock_init(&host->h_lock);
 126
 127         if (++nrhosts > NLM_HOST_MAX)
 128                 next_gc = 0;
 129
 130 nohost:
 131         up(&nlm_host_sema);
 132         return host;
 133 }
 134
 135 struct nlm_host *
 136 nlm_find_client(void)
 137 {
 138         /* find a nlm_host for a client for which h_killed == 0.
 139          * and return it
 140          */
 141         int hash;
 142         down(&nlm_host_sema);
 143         for (hash = 0 ; hash < NLM_HOST_NRHASH; hash++) {
 144                 struct nlm_host *host, **hp;
 145                 for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
 146                         if (host->h_server &&
 147                             host->h_killed == 0) {
 148                                 nlm_get_host(host);
 149                                 up(&nlm_host_sema);
 150                                 return host;
 151                         }
 152                 }
 153         }
 154         up(&nlm_host_sema);
 155         return NULL;
 156 }
 157
 158
 159 /*
 160  * Create the NLM RPC client for an NLM peer
 161  */
 162 struct rpc_clnt *
 163 nlm_bind_host(struct nlm_host *host)
 164 {
 165         struct rpc_clnt *clnt;
 166         struct rpc_xprt *xprt;
 167
 168         dprintk("lockd: nlm_bind_host(%08x)\n",
 169                         (unsigned)ntohl(host->h_addr.sin_addr.s_addr));
 170
 171         /* Lock host handle */
 172         down(&host->h_sema);
 173
 174         /* If we've already created an RPC client, check whether
 175          * RPC rebind is required
 176          * Note: why keep rebinding if we're on a tcp connection?
 177          */
 178         if ((clnt = host->h_rpcclnt) != NULL) {
 179                 xprt = clnt->cl_xprt;
 180                 if (!xprt->stream && time_after_eq(jiffies, host->h_nextrebind)) {
 181                         clnt->cl_port = 0;
 182                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 183                         dprintk("lockd: next rebind in %ld jiffies\n",
 184                                         host->h_nextrebind - jiffies);
 185                 }
 186         } else {
 187                 xprt = xprt_create_proto(host->h_proto, &host->h_addr, NULL);
 188                 if (IS_ERR(xprt))
 189                         goto forgetit;
 190
 191                 xprt_set_timeout(&xprt->timeout, 5, nlmsvc_timeout);
 192
 193                 /* Existing NLM servers accept AUTH_UNIX only */
 194                 clnt = rpc_create_client(xprt, host->h_name, &nlm_program,
 195                                         host->h_version, RPC_AUTH_UNIX);
 196                 if (IS_ERR(clnt)) {
 197                         xprt_destroy(xprt);
 198                         goto forgetit;
 199                 }
 200                 clnt->cl_autobind = 1;  /* turn on pmap queries */
 201                 xprt->nocong = 1;       /* No congestion control for NLM */
 202                 xprt->resvport = 1;     /* NLM requires a reserved port */
 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                 host->h_rpcclnt->cl_port = 0;
 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                 atomic_dec(&host->h_count);
 250                 BUG_ON(atomic_read(&host->h_count) < 0);
 251         }
 252 }
 253
 254 /*
 255  * Shut down the hosts module.
 256  * Note that this routine is called only at server shutdown time.
 257  */
 258 void
 259 nlm_shutdown_hosts(void)
 260 {
 261         struct nlm_host *host;
 262         int             i;
 263
 264         dprintk("lockd: shutting down host module\n");
 265         down(&nlm_host_sema);
 266
 267         /* First, make all hosts eligible for gc */
 268         dprintk("lockd: nuking all hosts...\n");
 269         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 270                 for (host = nlm_hosts[i]; host; host = host->h_next)
 271                         host->h_expires = jiffies - 1;
 272         }
 273
 274         /* Then, perform a garbage collection pass */
 275         nlm_gc_hosts();
 276         up(&nlm_host_sema);
 277
 278         /* complain if any hosts are left */
 279         if (nrhosts) {
 280                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 281                 dprintk("lockd: %d hosts left:\n", nrhosts);
 282                 for (i = 0; i < NLM_HOST_NRHASH; i++) {
 283                         for (host = nlm_hosts[i]; host; host = host->h_next) {
 284                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 285                                         host->h_name, atomic_read(&host->h_count),
 286                                         host->h_inuse, host->h_expires);
 287                         }
 288                 }
 289         }
 290 }
 291
 292 /*
 293  * Garbage collect any unused NLM hosts.
 294  * This GC combines reference counting for async operations with
 295  * mark & sweep for resources held by remote clients.
 296  */
 297 static void
 298 nlm_gc_hosts(void)
 299 {
 300         struct nlm_host **q, *host;
 301         struct rpc_clnt *clnt;
 302         int             i;
 303
 304         dprintk("lockd: host garbage collection\n");
 305         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 306                 for (host = nlm_hosts[i]; host; host = host->h_next)
 307                         host->h_inuse = 0;
 308         }
 309
 310         /* Mark all hosts that hold locks, blocks or shares */
 311         nlmsvc_mark_resources();
 312
 313         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 314                 q = &nlm_hosts[i];
 315                 while ((host = *q) != NULL) {
 316                         if (atomic_read(&host->h_count) || host->h_inuse
 317                          || time_before(jiffies, host->h_expires)) {
 318                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 319                                         host->h_name, atomic_read(&host->h_count),
 320                                         host->h_inuse, host->h_expires);
 321                                 q = &host->h_next;
 322                                 continue;
 323                         }
 324                         dprintk("lockd: delete host %s\n", host->h_name);
 325                         *q = host->h_next;
 326                         /* Don't unmonitor hosts that have been invalidated */
 327                         if (host->h_monitored && !host->h_killed)
 328                                 nsm_unmonitor(host);
 329                         if ((clnt = host->h_rpcclnt) != NULL) {
 330                                 if (atomic_read(&clnt->cl_users)) {
 331                                         printk(KERN_WARNING
 332                                                 "lockd: active RPC handle\n");
 333                                         clnt->cl_dead = 1;
 334                                 } else {
 335                                         rpc_destroy_client(host->h_rpcclnt);
 336                                 }
 337                         }
 338                         BUG_ON(!list_empty(&host->h_lockowners));
 339                         kfree(host);
 340                         nrhosts--;
 341                 }
 342         }
 343
 344         next_gc = jiffies + NLM_HOST_COLLECT;
 345 }
 346