linux/fs/lockd/clntproc.c
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   1/*
   2 * linux/fs/lockd/clntproc.c
   3 *
   4 * RPC procedures for the client side NLM implementation
   5 *
   6 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   7 */
   8
   9#include <linux/module.h>
  10#include <linux/slab.h>
  11#include <linux/types.h>
  12#include <linux/errno.h>
  13#include <linux/fs.h>
  14#include <linux/nfs_fs.h>
  15#include <linux/utsname.h>
  16#include <linux/freezer.h>
  17#include <linux/sunrpc/clnt.h>
  18#include <linux/sunrpc/svc.h>
  19#include <linux/lockd/lockd.h>
  20
  21#define NLMDBG_FACILITY         NLMDBG_CLIENT
  22#define NLMCLNT_GRACE_WAIT      (5*HZ)
  23#define NLMCLNT_POLL_TIMEOUT    (30*HZ)
  24#define NLMCLNT_MAX_RETRIES     3
  25
  26static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  27static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  28static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  29static int      nlm_stat_to_errno(__be32 stat);
  30static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
  31static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
  32
  33static const struct rpc_call_ops nlmclnt_unlock_ops;
  34static const struct rpc_call_ops nlmclnt_cancel_ops;
  35
  36/*
  37 * Cookie counter for NLM requests
  38 */
  39static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
  40
  41void nlmclnt_next_cookie(struct nlm_cookie *c)
  42{
  43        u32     cookie = atomic_inc_return(&nlm_cookie);
  44
  45        memcpy(c->data, &cookie, 4);
  46        c->len=4;
  47}
  48
  49static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
  50{
  51        atomic_inc(&lockowner->count);
  52        return lockowner;
  53}
  54
  55static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
  56{
  57        if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  58                return;
  59        list_del(&lockowner->list);
  60        spin_unlock(&lockowner->host->h_lock);
  61        nlmclnt_release_host(lockowner->host);
  62        kfree(lockowner);
  63}
  64
  65static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  66{
  67        struct nlm_lockowner *lockowner;
  68        list_for_each_entry(lockowner, &host->h_lockowners, list) {
  69                if (lockowner->pid == pid)
  70                        return -EBUSY;
  71        }
  72        return 0;
  73}
  74
  75static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  76{
  77        uint32_t res;
  78        do {
  79                res = host->h_pidcount++;
  80        } while (nlm_pidbusy(host, res) < 0);
  81        return res;
  82}
  83
  84static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  85{
  86        struct nlm_lockowner *lockowner;
  87        list_for_each_entry(lockowner, &host->h_lockowners, list) {
  88                if (lockowner->owner != owner)
  89                        continue;
  90                return nlm_get_lockowner(lockowner);
  91        }
  92        return NULL;
  93}
  94
  95static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  96{
  97        struct nlm_lockowner *res, *new = NULL;
  98
  99        spin_lock(&host->h_lock);
 100        res = __nlm_find_lockowner(host, owner);
 101        if (res == NULL) {
 102                spin_unlock(&host->h_lock);
 103                new = kmalloc(sizeof(*new), GFP_KERNEL);
 104                spin_lock(&host->h_lock);
 105                res = __nlm_find_lockowner(host, owner);
 106                if (res == NULL && new != NULL) {
 107                        res = new;
 108                        atomic_set(&new->count, 1);
 109                        new->owner = owner;
 110                        new->pid = __nlm_alloc_pid(host);
 111                        new->host = nlm_get_host(host);
 112                        list_add(&new->list, &host->h_lockowners);
 113                        new = NULL;
 114                }
 115        }
 116        spin_unlock(&host->h_lock);
 117        kfree(new);
 118        return res;
 119}
 120
 121/*
 122 * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 123 */
 124static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 125{
 126        struct nlm_args *argp = &req->a_args;
 127        struct nlm_lock *lock = &argp->lock;
 128
 129        nlmclnt_next_cookie(&argp->cookie);
 130        memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode), sizeof(struct nfs_fh));
 131        lock->caller  = utsname()->nodename;
 132        lock->oh.data = req->a_owner;
 133        lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 134                                (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 135                                utsname()->nodename);
 136        lock->svid = fl->fl_u.nfs_fl.owner->pid;
 137        lock->fl.fl_start = fl->fl_start;
 138        lock->fl.fl_end = fl->fl_end;
 139        lock->fl.fl_type = fl->fl_type;
 140}
 141
 142static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 143{
 144        BUG_ON(req->a_args.lock.fl.fl_ops != NULL);
 145}
 146
 147/**
 148 * nlmclnt_proc - Perform a single client-side lock request
 149 * @host: address of a valid nlm_host context representing the NLM server
 150 * @cmd: fcntl-style file lock operation to perform
 151 * @fl: address of arguments for the lock operation
 152 *
 153 */
 154int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
 155{
 156        struct nlm_rqst         *call;
 157        int                     status;
 158
 159        call = nlm_alloc_call(host);
 160        if (call == NULL)
 161                return -ENOMEM;
 162
 163        nlmclnt_locks_init_private(fl, host);
 164        if (!fl->fl_u.nfs_fl.owner) {
 165                /* lockowner allocation has failed */
 166                nlmclnt_release_call(call);
 167                return -ENOMEM;
 168        }
 169        /* Set up the argument struct */
 170        nlmclnt_setlockargs(call, fl);
 171
 172        if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 173                if (fl->fl_type != F_UNLCK) {
 174                        call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 175                        status = nlmclnt_lock(call, fl);
 176                } else
 177                        status = nlmclnt_unlock(call, fl);
 178        } else if (IS_GETLK(cmd))
 179                status = nlmclnt_test(call, fl);
 180        else
 181                status = -EINVAL;
 182        fl->fl_ops->fl_release_private(fl);
 183        fl->fl_ops = NULL;
 184
 185        dprintk("lockd: clnt proc returns %d\n", status);
 186        return status;
 187}
 188EXPORT_SYMBOL_GPL(nlmclnt_proc);
 189
 190/*
 191 * Allocate an NLM RPC call struct
 192 */
 193struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 194{
 195        struct nlm_rqst *call;
 196
 197        for(;;) {
 198                call = kzalloc(sizeof(*call), GFP_KERNEL);
 199                if (call != NULL) {
 200                        atomic_set(&call->a_count, 1);
 201                        locks_init_lock(&call->a_args.lock.fl);
 202                        locks_init_lock(&call->a_res.lock.fl);
 203                        call->a_host = nlm_get_host(host);
 204                        return call;
 205                }
 206                if (signalled())
 207                        break;
 208                printk("nlm_alloc_call: failed, waiting for memory\n");
 209                schedule_timeout_interruptible(5*HZ);
 210        }
 211        return NULL;
 212}
 213
 214void nlmclnt_release_call(struct nlm_rqst *call)
 215{
 216        if (!atomic_dec_and_test(&call->a_count))
 217                return;
 218        nlmclnt_release_host(call->a_host);
 219        nlmclnt_release_lockargs(call);
 220        kfree(call);
 221}
 222
 223static void nlmclnt_rpc_release(void *data)
 224{
 225        nlmclnt_release_call(data);
 226}
 227
 228static int nlm_wait_on_grace(wait_queue_head_t *queue)
 229{
 230        DEFINE_WAIT(wait);
 231        int status = -EINTR;
 232
 233        prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 234        if (!signalled ()) {
 235                schedule_timeout(NLMCLNT_GRACE_WAIT);
 236                try_to_freeze();
 237                if (!signalled ())
 238                        status = 0;
 239        }
 240        finish_wait(queue, &wait);
 241        return status;
 242}
 243
 244/*
 245 * Generic NLM call
 246 */
 247static int
 248nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc)
 249{
 250        struct nlm_host *host = req->a_host;
 251        struct rpc_clnt *clnt;
 252        struct nlm_args *argp = &req->a_args;
 253        struct nlm_res  *resp = &req->a_res;
 254        struct rpc_message msg = {
 255                .rpc_argp       = argp,
 256                .rpc_resp       = resp,
 257                .rpc_cred       = cred,
 258        };
 259        int             status;
 260
 261        dprintk("lockd: call procedure %d on %s\n",
 262                        (int)proc, host->h_name);
 263
 264        do {
 265                if (host->h_reclaiming && !argp->reclaim)
 266                        goto in_grace_period;
 267
 268                /* If we have no RPC client yet, create one. */
 269                if ((clnt = nlm_bind_host(host)) == NULL)
 270                        return -ENOLCK;
 271                msg.rpc_proc = &clnt->cl_procinfo[proc];
 272
 273                /* Perform the RPC call. If an error occurs, try again */
 274                if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 275                        dprintk("lockd: rpc_call returned error %d\n", -status);
 276                        switch (status) {
 277                        case -EPROTONOSUPPORT:
 278                                status = -EINVAL;
 279                                break;
 280                        case -ECONNREFUSED:
 281                        case -ETIMEDOUT:
 282                        case -ENOTCONN:
 283                                nlm_rebind_host(host);
 284                                status = -EAGAIN;
 285                                break;
 286                        case -ERESTARTSYS:
 287                                return signalled () ? -EINTR : status;
 288                        default:
 289                                break;
 290                        }
 291                        break;
 292                } else
 293                if (resp->status == nlm_lck_denied_grace_period) {
 294                        dprintk("lockd: server in grace period\n");
 295                        if (argp->reclaim) {
 296                                printk(KERN_WARNING
 297                                     "lockd: spurious grace period reject?!\n");
 298                                return -ENOLCK;
 299                        }
 300                } else {
 301                        if (!argp->reclaim) {
 302                                /* We appear to be out of the grace period */
 303                                wake_up_all(&host->h_gracewait);
 304                        }
 305                        dprintk("lockd: server returns status %d\n",
 306                                ntohl(resp->status));
 307                        return 0;       /* Okay, call complete */
 308                }
 309
 310in_grace_period:
 311                /*
 312                 * The server has rebooted and appears to be in the grace
 313                 * period during which locks are only allowed to be
 314                 * reclaimed.
 315                 * We can only back off and try again later.
 316                 */
 317                status = nlm_wait_on_grace(&host->h_gracewait);
 318        } while (status == 0);
 319
 320        return status;
 321}
 322
 323/*
 324 * Generic NLM call, async version.
 325 */
 326static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 327{
 328        struct nlm_host *host = req->a_host;
 329        struct rpc_clnt *clnt;
 330        struct rpc_task_setup task_setup_data = {
 331                .rpc_message = msg,
 332                .callback_ops = tk_ops,
 333                .callback_data = req,
 334                .flags = RPC_TASK_ASYNC,
 335        };
 336
 337        dprintk("lockd: call procedure %d on %s (async)\n",
 338                        (int)proc, host->h_name);
 339
 340        /* If we have no RPC client yet, create one. */
 341        clnt = nlm_bind_host(host);
 342        if (clnt == NULL)
 343                goto out_err;
 344        msg->rpc_proc = &clnt->cl_procinfo[proc];
 345        task_setup_data.rpc_client = clnt;
 346
 347        /* bootstrap and kick off the async RPC call */
 348        return rpc_run_task(&task_setup_data);
 349out_err:
 350        tk_ops->rpc_release(req);
 351        return ERR_PTR(-ENOLCK);
 352}
 353
 354static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 355{
 356        struct rpc_task *task;
 357
 358        task = __nlm_async_call(req, proc, msg, tk_ops);
 359        if (IS_ERR(task))
 360                return PTR_ERR(task);
 361        rpc_put_task(task);
 362        return 0;
 363}
 364
 365/*
 366 * NLM asynchronous call.
 367 */
 368int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 369{
 370        struct rpc_message msg = {
 371                .rpc_argp       = &req->a_args,
 372                .rpc_resp       = &req->a_res,
 373        };
 374        return nlm_do_async_call(req, proc, &msg, tk_ops);
 375}
 376
 377int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 378{
 379        struct rpc_message msg = {
 380                .rpc_argp       = &req->a_res,
 381        };
 382        return nlm_do_async_call(req, proc, &msg, tk_ops);
 383}
 384
 385/*
 386 * NLM client asynchronous call.
 387 *
 388 * Note that although the calls are asynchronous, and are therefore
 389 *      guaranteed to complete, we still always attempt to wait for
 390 *      completion in order to be able to correctly track the lock
 391 *      state.
 392 */
 393static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 394{
 395        struct rpc_message msg = {
 396                .rpc_argp       = &req->a_args,
 397                .rpc_resp       = &req->a_res,
 398                .rpc_cred       = cred,
 399        };
 400        struct rpc_task *task;
 401        int err;
 402
 403        task = __nlm_async_call(req, proc, &msg, tk_ops);
 404        if (IS_ERR(task))
 405                return PTR_ERR(task);
 406        err = rpc_wait_for_completion_task(task);
 407        rpc_put_task(task);
 408        return err;
 409}
 410
 411/*
 412 * TEST for the presence of a conflicting lock
 413 */
 414static int
 415nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 416{
 417        int     status;
 418
 419        status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 420        if (status < 0)
 421                goto out;
 422
 423        switch (req->a_res.status) {
 424                case nlm_granted:
 425                        fl->fl_type = F_UNLCK;
 426                        break;
 427                case nlm_lck_denied:
 428                        /*
 429                         * Report the conflicting lock back to the application.
 430                         */
 431                        fl->fl_start = req->a_res.lock.fl.fl_start;
 432                        fl->fl_end = req->a_res.lock.fl.fl_end;
 433                        fl->fl_type = req->a_res.lock.fl.fl_type;
 434                        fl->fl_pid = 0;
 435                        break;
 436                default:
 437                        status = nlm_stat_to_errno(req->a_res.status);
 438        }
 439out:
 440        nlmclnt_release_call(req);
 441        return status;
 442}
 443
 444static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 445{
 446        spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 447        new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 448        new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
 449        list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 450        spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 451}
 452
 453static void nlmclnt_locks_release_private(struct file_lock *fl)
 454{
 455        spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 456        list_del(&fl->fl_u.nfs_fl.list);
 457        spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 458        nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 459}
 460
 461static const struct file_lock_operations nlmclnt_lock_ops = {
 462        .fl_copy_lock = nlmclnt_locks_copy_lock,
 463        .fl_release_private = nlmclnt_locks_release_private,
 464};
 465
 466static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 467{
 468        BUG_ON(fl->fl_ops != NULL);
 469        fl->fl_u.nfs_fl.state = 0;
 470        fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 471        INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 472        fl->fl_ops = &nlmclnt_lock_ops;
 473}
 474
 475static int do_vfs_lock(struct file_lock *fl)
 476{
 477        int res = 0;
 478        switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
 479                case FL_POSIX:
 480                        res = posix_lock_file_wait(fl->fl_file, fl);
 481                        break;
 482                case FL_FLOCK:
 483                        res = flock_lock_file_wait(fl->fl_file, fl);
 484                        break;
 485                default:
 486                        BUG();
 487        }
 488        return res;
 489}
 490
 491/*
 492 * LOCK: Try to create a lock
 493 *
 494 *                      Programmer Harassment Alert
 495 *
 496 * When given a blocking lock request in a sync RPC call, the HPUX lockd
 497 * will faithfully return LCK_BLOCKED but never cares to notify us when
 498 * the lock could be granted. This way, our local process could hang
 499 * around forever waiting for the callback.
 500 *
 501 *  Solution A: Implement busy-waiting
 502 *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 503 *
 504 * For now I am implementing solution A, because I hate the idea of
 505 * re-implementing lockd for a third time in two months. The async
 506 * calls shouldn't be too hard to do, however.
 507 *
 508 * This is one of the lovely things about standards in the NFS area:
 509 * they're so soft and squishy you can't really blame HP for doing this.
 510 */
 511static int
 512nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 513{
 514        struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
 515        struct nlm_host *host = req->a_host;
 516        struct nlm_res  *resp = &req->a_res;
 517        struct nlm_wait *block = NULL;
 518        unsigned char fl_flags = fl->fl_flags;
 519        unsigned char fl_type;
 520        int status = -ENOLCK;
 521
 522        if (nsm_monitor(host) < 0)
 523                goto out;
 524        req->a_args.state = nsm_local_state;
 525
 526        fl->fl_flags |= FL_ACCESS;
 527        status = do_vfs_lock(fl);
 528        fl->fl_flags = fl_flags;
 529        if (status < 0)
 530                goto out;
 531
 532        block = nlmclnt_prepare_block(host, fl);
 533again:
 534        /*
 535         * Initialise resp->status to a valid non-zero value,
 536         * since 0 == nlm_lck_granted
 537         */
 538        resp->status = nlm_lck_blocked;
 539        for(;;) {
 540                /* Reboot protection */
 541                fl->fl_u.nfs_fl.state = host->h_state;
 542                status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 543                if (status < 0)
 544                        break;
 545                /* Did a reclaimer thread notify us of a server reboot? */
 546                if (resp->status ==  nlm_lck_denied_grace_period)
 547                        continue;
 548                if (resp->status != nlm_lck_blocked)
 549                        break;
 550                /* Wait on an NLM blocking lock */
 551                status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 552                if (status < 0)
 553                        break;
 554                if (resp->status != nlm_lck_blocked)
 555                        break;
 556        }
 557
 558        /* if we were interrupted while blocking, then cancel the lock request
 559         * and exit
 560         */
 561        if (resp->status == nlm_lck_blocked) {
 562                if (!req->a_args.block)
 563                        goto out_unlock;
 564                if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 565                        goto out_unblock;
 566        }
 567
 568        if (resp->status == nlm_granted) {
 569                down_read(&host->h_rwsem);
 570                /* Check whether or not the server has rebooted */
 571                if (fl->fl_u.nfs_fl.state != host->h_state) {
 572                        up_read(&host->h_rwsem);
 573                        goto again;
 574                }
 575                /* Ensure the resulting lock will get added to granted list */
 576                fl->fl_flags |= FL_SLEEP;
 577                if (do_vfs_lock(fl) < 0)
 578                        printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 579                up_read(&host->h_rwsem);
 580                fl->fl_flags = fl_flags;
 581                status = 0;
 582        }
 583        if (status < 0)
 584                goto out_unlock;
 585        /*
 586         * EAGAIN doesn't make sense for sleeping locks, and in some
 587         * cases NLM_LCK_DENIED is returned for a permanent error.  So
 588         * turn it into an ENOLCK.
 589         */
 590        if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 591                status = -ENOLCK;
 592        else
 593                status = nlm_stat_to_errno(resp->status);
 594out_unblock:
 595        nlmclnt_finish_block(block);
 596out:
 597        nlmclnt_release_call(req);
 598        return status;
 599out_unlock:
 600        /* Fatal error: ensure that we remove the lock altogether */
 601        dprintk("lockd: lock attempt ended in fatal error.\n"
 602                "       Attempting to unlock.\n");
 603        nlmclnt_finish_block(block);
 604        fl_type = fl->fl_type;
 605        fl->fl_type = F_UNLCK;
 606        down_read(&host->h_rwsem);
 607        do_vfs_lock(fl);
 608        up_read(&host->h_rwsem);
 609        fl->fl_type = fl_type;
 610        fl->fl_flags = fl_flags;
 611        nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 612        return status;
 613}
 614
 615/*
 616 * RECLAIM: Try to reclaim a lock
 617 */
 618int
 619nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
 620{
 621        struct nlm_rqst reqst, *req;
 622        int             status;
 623
 624        req = &reqst;
 625        memset(req, 0, sizeof(*req));
 626        locks_init_lock(&req->a_args.lock.fl);
 627        locks_init_lock(&req->a_res.lock.fl);
 628        req->a_host  = host;
 629        req->a_flags = 0;
 630
 631        /* Set up the argument struct */
 632        nlmclnt_setlockargs(req, fl);
 633        req->a_args.reclaim = 1;
 634
 635        status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 636        if (status >= 0 && req->a_res.status == nlm_granted)
 637                return 0;
 638
 639        printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 640                                "(errno %d, status %d)\n", fl->fl_pid,
 641                                status, ntohl(req->a_res.status));
 642
 643        /*
 644         * FIXME: This is a serious failure. We can
 645         *
 646         *  a.  Ignore the problem
 647         *  b.  Send the owning process some signal (Linux doesn't have
 648         *      SIGLOST, though...)
 649         *  c.  Retry the operation
 650         *
 651         * Until someone comes up with a simple implementation
 652         * for b or c, I'll choose option a.
 653         */
 654
 655        return -ENOLCK;
 656}
 657
 658/*
 659 * UNLOCK: remove an existing lock
 660 */
 661static int
 662nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 663{
 664        struct nlm_host *host = req->a_host;
 665        struct nlm_res  *resp = &req->a_res;
 666        int status;
 667        unsigned char fl_flags = fl->fl_flags;
 668
 669        /*
 670         * Note: the server is supposed to either grant us the unlock
 671         * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 672         * case, we want to unlock.
 673         */
 674        fl->fl_flags |= FL_EXISTS;
 675        down_read(&host->h_rwsem);
 676        status = do_vfs_lock(fl);
 677        up_read(&host->h_rwsem);
 678        fl->fl_flags = fl_flags;
 679        if (status == -ENOENT) {
 680                status = 0;
 681                goto out;
 682        }
 683
 684        atomic_inc(&req->a_count);
 685        status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 686                        NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 687        if (status < 0)
 688                goto out;
 689
 690        if (resp->status == nlm_granted)
 691                goto out;
 692
 693        if (resp->status != nlm_lck_denied_nolocks)
 694                printk("lockd: unexpected unlock status: %d\n",
 695                        ntohl(resp->status));
 696        /* What to do now? I'm out of my depth... */
 697        status = -ENOLCK;
 698out:
 699        nlmclnt_release_call(req);
 700        return status;
 701}
 702
 703static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 704{
 705        struct nlm_rqst *req = data;
 706        u32 status = ntohl(req->a_res.status);
 707
 708        if (RPC_ASSASSINATED(task))
 709                goto die;
 710
 711        if (task->tk_status < 0) {
 712                dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 713                switch (task->tk_status) {
 714                case -EACCES:
 715                case -EIO:
 716                        goto die;
 717                default:
 718                        goto retry_rebind;
 719                }
 720        }
 721        if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 722                rpc_delay(task, NLMCLNT_GRACE_WAIT);
 723                goto retry_unlock;
 724        }
 725        if (status != NLM_LCK_GRANTED)
 726                printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 727die:
 728        return;
 729 retry_rebind:
 730        nlm_rebind_host(req->a_host);
 731 retry_unlock:
 732        rpc_restart_call(task);
 733}
 734
 735static const struct rpc_call_ops nlmclnt_unlock_ops = {
 736        .rpc_call_done = nlmclnt_unlock_callback,
 737        .rpc_release = nlmclnt_rpc_release,
 738};
 739
 740/*
 741 * Cancel a blocked lock request.
 742 * We always use an async RPC call for this in order not to hang a
 743 * process that has been Ctrl-C'ed.
 744 */
 745static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 746{
 747        struct nlm_rqst *req;
 748        int status;
 749
 750        dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 751                "       Attempting to cancel lock.\n");
 752
 753        req = nlm_alloc_call(host);
 754        if (!req)
 755                return -ENOMEM;
 756        req->a_flags = RPC_TASK_ASYNC;
 757
 758        nlmclnt_setlockargs(req, fl);
 759        req->a_args.block = block;
 760
 761        atomic_inc(&req->a_count);
 762        status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 763                        NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 764        if (status == 0 && req->a_res.status == nlm_lck_denied)
 765                status = -ENOLCK;
 766        nlmclnt_release_call(req);
 767        return status;
 768}
 769
 770static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 771{
 772        struct nlm_rqst *req = data;
 773        u32 status = ntohl(req->a_res.status);
 774
 775        if (RPC_ASSASSINATED(task))
 776                goto die;
 777
 778        if (task->tk_status < 0) {
 779                dprintk("lockd: CANCEL call error %d, retrying.\n",
 780                                        task->tk_status);
 781                goto retry_cancel;
 782        }
 783
 784        dprintk("lockd: cancel status %u (task %u)\n",
 785                        status, task->tk_pid);
 786
 787        switch (status) {
 788        case NLM_LCK_GRANTED:
 789        case NLM_LCK_DENIED_GRACE_PERIOD:
 790        case NLM_LCK_DENIED:
 791                /* Everything's good */
 792                break;
 793        case NLM_LCK_DENIED_NOLOCKS:
 794                dprintk("lockd: CANCEL failed (server has no locks)\n");
 795                goto retry_cancel;
 796        default:
 797                printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 798                        status);
 799        }
 800
 801die:
 802        return;
 803
 804retry_cancel:
 805        /* Don't ever retry more than 3 times */
 806        if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 807                goto die;
 808        nlm_rebind_host(req->a_host);
 809        rpc_restart_call(task);
 810        rpc_delay(task, 30 * HZ);
 811}
 812
 813static const struct rpc_call_ops nlmclnt_cancel_ops = {
 814        .rpc_call_done = nlmclnt_cancel_callback,
 815        .rpc_release = nlmclnt_rpc_release,
 816};
 817
 818/*
 819 * Convert an NLM status code to a generic kernel errno
 820 */
 821static int
 822nlm_stat_to_errno(__be32 status)
 823{
 824        switch(ntohl(status)) {
 825        case NLM_LCK_GRANTED:
 826                return 0;
 827        case NLM_LCK_DENIED:
 828                return -EAGAIN;
 829        case NLM_LCK_DENIED_NOLOCKS:
 830        case NLM_LCK_DENIED_GRACE_PERIOD:
 831                return -ENOLCK;
 832        case NLM_LCK_BLOCKED:
 833                printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 834                return -ENOLCK;
 835#ifdef CONFIG_LOCKD_V4
 836        case NLM_DEADLCK:
 837                return -EDEADLK;
 838        case NLM_ROFS:
 839                return -EROFS;
 840        case NLM_STALE_FH:
 841                return -ESTALE;
 842        case NLM_FBIG:
 843                return -EOVERFLOW;
 844        case NLM_FAILED:
 845                return -ENOLCK;
 846#endif
 847        }
 848        printk(KERN_NOTICE "lockd: unexpected server status %d\n",
 849                 ntohl(status));
 850        return -ENOLCK;
 851}
 852
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