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                         dprintk("lockd: xprt_create_proto failed: %ld\n", PTR_ERR(xprt));
 190                         goto forgetit;
 191                 }
 192                 xprt_set_timeout(&xprt->timeout, 5, nlmsvc_timeout);
 193
 194                 /* Existing NLM servers accept AUTH_UNIX only */
 195                 clnt = rpc_create_client(xprt, host->h_name, &nlm_program,
 196                                         host->h_version, RPC_AUTH_UNIX);
 197                 if (IS_ERR(clnt)) {
 198                         xprt_destroy(xprt);
 199                         dprintk("lockd: rpc_create_client failed: %ld\n", PTR_ERR(clnt));
 200                         goto forgetit;
 201                 }
 202                 clnt->cl_autobind = 1;  /* turn on pmap queries */
 203                 xprt->nocong = 1;       /* No congestion control for NLM */
 204                 xprt->resvport = 1;     /* NLM requires a reserved port */
 205
 206                 host->h_rpcclnt = clnt;
 207         }
 208
 209         up(&host->h_sema);
 210         return clnt;
 211
 212 forgetit:
 213         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
 214         up(&host->h_sema);
 215         return NULL;
 216 }
 217
 218 /*
 219  * Force a portmap lookup of the remote lockd port
 220  */
 221 void
 222 nlm_rebind_host(struct nlm_host *host)
 223 {
 224         dprintk("lockd: rebind host %s\n", host->h_name);
 225         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
 226                 host->h_rpcclnt->cl_port = 0;
 227                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
 228         }
 229 }
 230
 231 /*
 232  * Increment NLM host count
 233  */
 234 struct nlm_host * nlm_get_host(struct nlm_host *host)
 235 {
 236         if (host) {
 237                 dprintk("lockd: get host %s\n", host->h_name);
 238                 atomic_inc(&host->h_count);
 239                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
 240         }
 241         return host;
 242 }
 243
 244 /*
 245  * Release NLM host after use
 246  */
 247 void nlm_release_host(struct nlm_host *host)
 248 {
 249         if (host != NULL) {
 250                 dprintk("lockd: release host %s\n", host->h_name);
 251                 atomic_dec(&host->h_count);
 252                 BUG_ON(atomic_read(&host->h_count) < 0);
 253         }
 254 }
 255
 256 /*
 257  * Shut down the hosts module.
 258  * Note that this routine is called only at server shutdown time.
 259  */
 260 void
 261 nlm_shutdown_hosts(void)
 262 {
 263         struct nlm_host *host;
 264         int             i;
 265
 266         dprintk("lockd: shutting down host module\n");
 267         down(&nlm_host_sema);
 268
 269         /* First, make all hosts eligible for gc */
 270         dprintk("lockd: nuking all hosts...\n");
 271         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 272                 for (host = nlm_hosts[i]; host; host = host->h_next)
 273                         host->h_expires = jiffies - 1;
 274         }
 275
 276         /* Then, perform a garbage collection pass */
 277         nlm_gc_hosts();
 278         up(&nlm_host_sema);
 279
 280         /* complain if any hosts are left */
 281         if (nrhosts) {
 282                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
 283                 dprintk("lockd: %d hosts left:\n", nrhosts);
 284                 for (i = 0; i < NLM_HOST_NRHASH; i++) {
 285                         for (host = nlm_hosts[i]; host; host = host->h_next) {
 286                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
 287                                         host->h_name, atomic_read(&host->h_count),
 288                                         host->h_inuse, host->h_expires);
 289                         }
 290                 }
 291         }
 292 }
 293
 294 /*
 295  * Garbage collect any unused NLM hosts.
 296  * This GC combines reference counting for async operations with
 297  * mark & sweep for resources held by remote clients.
 298  */
 299 static void
 300 nlm_gc_hosts(void)
 301 {
 302         struct nlm_host **q, *host;
 303         struct rpc_clnt *clnt;
 304         int             i;
 305
 306         dprintk("lockd: host garbage collection\n");
 307         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 308                 for (host = nlm_hosts[i]; host; host = host->h_next)
 309                         host->h_inuse = 0;
 310         }
 311
 312         /* Mark all hosts that hold locks, blocks or shares */
 313         nlmsvc_mark_resources();
 314
 315         for (i = 0; i < NLM_HOST_NRHASH; i++) {
 316                 q = &nlm_hosts[i];
 317                 while ((host = *q) != NULL) {
 318                         if (atomic_read(&host->h_count) || host->h_inuse
 319                          || time_before(jiffies, host->h_expires)) {
 320                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
 321                                         host->h_name, atomic_read(&host->h_count),
 322                                         host->h_inuse, host->h_expires);
 323                                 q = &host->h_next;
 324                                 continue;
 325                         }
 326                         dprintk("lockd: delete host %s\n", host->h_name);
 327                         *q = host->h_next;
 328                         /* Don't unmonitor hosts that have been invalidated */
 329                         if (host->h_monitored && !host->h_killed)
 330                                 nsm_unmonitor(host);
 331                         if ((clnt = host->h_rpcclnt) != NULL) {
 332                                 if (atomic_read(&clnt->cl_users)) {
 333                                         printk(KERN_WARNING
 334                                                 "lockd: active RPC handle\n");
 335                                         clnt->cl_dead = 1;
 336                                 } else {
 337                                         rpc_destroy_client(host->h_rpcclnt);
 338                                 }
 339                         }
 340                         BUG_ON(!list_empty(&host->h_lockowners));
 341                         kfree(host);
 342                         nrhosts--;
 343                 }
 344         }
 345
 346         next_gc = jiffies + NLM_HOST_COLLECT;
 347 }
 348