Root/fs/lockd/clntproc.c

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    nlm_get_host(host);
160    call = nlm_alloc_call(host);
161    if (call == NULL)
162        return -ENOMEM;
163
164    nlmclnt_locks_init_private(fl, host);
165    /* Set up the argument struct */
166    nlmclnt_setlockargs(call, fl);
167
168    if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
169        if (fl->fl_type != F_UNLCK) {
170            call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
171            status = nlmclnt_lock(call, fl);
172        } else
173            status = nlmclnt_unlock(call, fl);
174    } else if (IS_GETLK(cmd))
175        status = nlmclnt_test(call, fl);
176    else
177        status = -EINVAL;
178    fl->fl_ops->fl_release_private(fl);
179    fl->fl_ops = NULL;
180
181    dprintk("lockd: clnt proc returns %d\n", status);
182    return status;
183}
184EXPORT_SYMBOL_GPL(nlmclnt_proc);
185
186/*
187 * Allocate an NLM RPC call struct
188 *
189 * Note: the caller must hold a reference to host. In case of failure,
190 * this reference will be released.
191 */
192struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
193{
194    struct nlm_rqst *call;
195
196    for(;;) {
197        call = kzalloc(sizeof(*call), GFP_KERNEL);
198        if (call != NULL) {
199            atomic_set(&call->a_count, 1);
200            locks_init_lock(&call->a_args.lock.fl);
201            locks_init_lock(&call->a_res.lock.fl);
202            call->a_host = host;
203            return call;
204        }
205        if (signalled())
206            break;
207        printk("nlm_alloc_call: failed, waiting for memory\n");
208        schedule_timeout_interruptible(5*HZ);
209    }
210    nlmclnt_release_host(host);
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", resp->status);
306            return 0; /* Okay, call complete */
307        }
308
309in_grace_period:
310        /*
311         * The server has rebooted and appears to be in the grace
312         * period during which locks are only allowed to be
313         * reclaimed.
314         * We can only back off and try again later.
315         */
316        status = nlm_wait_on_grace(&host->h_gracewait);
317    } while (status == 0);
318
319    return status;
320}
321
322/*
323 * Generic NLM call, async version.
324 */
325static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
326{
327    struct nlm_host *host = req->a_host;
328    struct rpc_clnt *clnt;
329    struct rpc_task_setup task_setup_data = {
330        .rpc_message = msg,
331        .callback_ops = tk_ops,
332        .callback_data = req,
333        .flags = RPC_TASK_ASYNC,
334    };
335
336    dprintk("lockd: call procedure %d on %s (async)\n",
337            (int)proc, host->h_name);
338
339    /* If we have no RPC client yet, create one. */
340    clnt = nlm_bind_host(host);
341    if (clnt == NULL)
342        goto out_err;
343    msg->rpc_proc = &clnt->cl_procinfo[proc];
344    task_setup_data.rpc_client = clnt;
345
346        /* bootstrap and kick off the async RPC call */
347    return rpc_run_task(&task_setup_data);
348out_err:
349    tk_ops->rpc_release(req);
350    return ERR_PTR(-ENOLCK);
351}
352
353static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
354{
355    struct rpc_task *task;
356
357    task = __nlm_async_call(req, proc, msg, tk_ops);
358    if (IS_ERR(task))
359        return PTR_ERR(task);
360    rpc_put_task(task);
361    return 0;
362}
363
364/*
365 * NLM asynchronous call.
366 */
367int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
368{
369    struct rpc_message msg = {
370        .rpc_argp = &req->a_args,
371        .rpc_resp = &req->a_res,
372    };
373    return nlm_do_async_call(req, proc, &msg, tk_ops);
374}
375
376int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
377{
378    struct rpc_message msg = {
379        .rpc_argp = &req->a_res,
380    };
381    return nlm_do_async_call(req, proc, &msg, tk_ops);
382}
383
384/*
385 * NLM client asynchronous call.
386 *
387 * Note that although the calls are asynchronous, and are therefore
388 * guaranteed to complete, we still always attempt to wait for
389 * completion in order to be able to correctly track the lock
390 * state.
391 */
392static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
393{
394    struct rpc_message msg = {
395        .rpc_argp = &req->a_args,
396        .rpc_resp = &req->a_res,
397        .rpc_cred = cred,
398    };
399    struct rpc_task *task;
400    int err;
401
402    task = __nlm_async_call(req, proc, &msg, tk_ops);
403    if (IS_ERR(task))
404        return PTR_ERR(task);
405    err = rpc_wait_for_completion_task(task);
406    rpc_put_task(task);
407    return err;
408}
409
410/*
411 * TEST for the presence of a conflicting lock
412 */
413static int
414nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
415{
416    int status;
417
418    status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
419    if (status < 0)
420        goto out;
421
422    switch (req->a_res.status) {
423        case nlm_granted:
424            fl->fl_type = F_UNLCK;
425            break;
426        case nlm_lck_denied:
427            /*
428             * Report the conflicting lock back to the application.
429             */
430            fl->fl_start = req->a_res.lock.fl.fl_start;
431            fl->fl_end = req->a_res.lock.fl.fl_end;
432            fl->fl_type = req->a_res.lock.fl.fl_type;
433            fl->fl_pid = 0;
434            break;
435        default:
436            status = nlm_stat_to_errno(req->a_res.status);
437    }
438out:
439    nlmclnt_release_call(req);
440    return status;
441}
442
443static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
444{
445    spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
446    new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
447    new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
448    list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
449    spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
450}
451
452static void nlmclnt_locks_release_private(struct file_lock *fl)
453{
454    spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
455    list_del(&fl->fl_u.nfs_fl.list);
456    spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
457    nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
458}
459
460static const struct file_lock_operations nlmclnt_lock_ops = {
461    .fl_copy_lock = nlmclnt_locks_copy_lock,
462    .fl_release_private = nlmclnt_locks_release_private,
463};
464
465static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
466{
467    BUG_ON(fl->fl_ops != NULL);
468    fl->fl_u.nfs_fl.state = 0;
469    fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
470    INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
471    fl->fl_ops = &nlmclnt_lock_ops;
472}
473
474static int do_vfs_lock(struct file_lock *fl)
475{
476    int res = 0;
477    switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
478        case FL_POSIX:
479            res = posix_lock_file_wait(fl->fl_file, fl);
480            break;
481        case FL_FLOCK:
482            res = flock_lock_file_wait(fl->fl_file, fl);
483            break;
484        default:
485            BUG();
486    }
487    return res;
488}
489
490/*
491 * LOCK: Try to create a lock
492 *
493 * Programmer Harassment Alert
494 *
495 * When given a blocking lock request in a sync RPC call, the HPUX lockd
496 * will faithfully return LCK_BLOCKED but never cares to notify us when
497 * the lock could be granted. This way, our local process could hang
498 * around forever waiting for the callback.
499 *
500 * Solution A: Implement busy-waiting
501 * Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
502 *
503 * For now I am implementing solution A, because I hate the idea of
504 * re-implementing lockd for a third time in two months. The async
505 * calls shouldn't be too hard to do, however.
506 *
507 * This is one of the lovely things about standards in the NFS area:
508 * they're so soft and squishy you can't really blame HP for doing this.
509 */
510static int
511nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
512{
513    struct rpc_cred *cred = nfs_file_cred(fl->fl_file);
514    struct nlm_host *host = req->a_host;
515    struct nlm_res *resp = &req->a_res;
516    struct nlm_wait *block = NULL;
517    unsigned char fl_flags = fl->fl_flags;
518    unsigned char fl_type;
519    int status = -ENOLCK;
520
521    if (nsm_monitor(host) < 0)
522        goto out;
523    req->a_args.state = nsm_local_state;
524
525    fl->fl_flags |= FL_ACCESS;
526    status = do_vfs_lock(fl);
527    fl->fl_flags = fl_flags;
528    if (status < 0)
529        goto out;
530
531    block = nlmclnt_prepare_block(host, fl);
532again:
533    /*
534     * Initialise resp->status to a valid non-zero value,
535     * since 0 == nlm_lck_granted
536     */
537    resp->status = nlm_lck_blocked;
538    for(;;) {
539        /* Reboot protection */
540        fl->fl_u.nfs_fl.state = host->h_state;
541        status = nlmclnt_call(cred, req, NLMPROC_LOCK);
542        if (status < 0)
543            break;
544        /* Did a reclaimer thread notify us of a server reboot? */
545        if (resp->status == nlm_lck_denied_grace_period)
546            continue;
547        if (resp->status != nlm_lck_blocked)
548            break;
549        /* Wait on an NLM blocking lock */
550        status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
551        if (status < 0)
552            break;
553        if (resp->status != nlm_lck_blocked)
554            break;
555    }
556
557    /* if we were interrupted while blocking, then cancel the lock request
558     * and exit
559     */
560    if (resp->status == nlm_lck_blocked) {
561        if (!req->a_args.block)
562            goto out_unlock;
563        if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
564            goto out_unblock;
565    }
566
567    if (resp->status == nlm_granted) {
568        down_read(&host->h_rwsem);
569        /* Check whether or not the server has rebooted */
570        if (fl->fl_u.nfs_fl.state != host->h_state) {
571            up_read(&host->h_rwsem);
572            goto again;
573        }
574        /* Ensure the resulting lock will get added to granted list */
575        fl->fl_flags |= FL_SLEEP;
576        if (do_vfs_lock(fl) < 0)
577            printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
578        up_read(&host->h_rwsem);
579        fl->fl_flags = fl_flags;
580        status = 0;
581    }
582    if (status < 0)
583        goto out_unlock;
584    /*
585     * EAGAIN doesn't make sense for sleeping locks, and in some
586     * cases NLM_LCK_DENIED is returned for a permanent error. So
587     * turn it into an ENOLCK.
588     */
589    if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
590        status = -ENOLCK;
591    else
592        status = nlm_stat_to_errno(resp->status);
593out_unblock:
594    nlmclnt_finish_block(block);
595out:
596    nlmclnt_release_call(req);
597    return status;
598out_unlock:
599    /* Fatal error: ensure that we remove the lock altogether */
600    dprintk("lockd: lock attempt ended in fatal error.\n"
601        " Attempting to unlock.\n");
602    nlmclnt_finish_block(block);
603    fl_type = fl->fl_type;
604    fl->fl_type = F_UNLCK;
605    down_read(&host->h_rwsem);
606    do_vfs_lock(fl);
607    up_read(&host->h_rwsem);
608    fl->fl_type = fl_type;
609    fl->fl_flags = fl_flags;
610    nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
611    return status;
612}
613
614/*
615 * RECLAIM: Try to reclaim a lock
616 */
617int
618nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
619{
620    struct nlm_rqst reqst, *req;
621    int status;
622
623    req = &reqst;
624    memset(req, 0, sizeof(*req));
625    locks_init_lock(&req->a_args.lock.fl);
626    locks_init_lock(&req->a_res.lock.fl);
627    req->a_host = host;
628    req->a_flags = 0;
629
630    /* Set up the argument struct */
631    nlmclnt_setlockargs(req, fl);
632    req->a_args.reclaim = 1;
633
634    status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
635    if (status >= 0 && req->a_res.status == nlm_granted)
636        return 0;
637
638    printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
639                "(errno %d, status %d)\n", fl->fl_pid,
640                status, ntohl(req->a_res.status));
641
642    /*
643     * FIXME: This is a serious failure. We can
644     *
645     * a. Ignore the problem
646     * b. Send the owning process some signal (Linux doesn't have
647     * SIGLOST, though...)
648     * c. Retry the operation
649     *
650     * Until someone comes up with a simple implementation
651     * for b or c, I'll choose option a.
652     */
653
654    return -ENOLCK;
655}
656
657/*
658 * UNLOCK: remove an existing lock
659 */
660static int
661nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
662{
663    struct nlm_host *host = req->a_host;
664    struct nlm_res *resp = &req->a_res;
665    int status;
666    unsigned char fl_flags = fl->fl_flags;
667
668    /*
669     * Note: the server is supposed to either grant us the unlock
670     * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
671     * case, we want to unlock.
672     */
673    fl->fl_flags |= FL_EXISTS;
674    down_read(&host->h_rwsem);
675    status = do_vfs_lock(fl);
676    up_read(&host->h_rwsem);
677    fl->fl_flags = fl_flags;
678    if (status == -ENOENT) {
679        status = 0;
680        goto out;
681    }
682
683    atomic_inc(&req->a_count);
684    status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
685            NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
686    if (status < 0)
687        goto out;
688
689    if (resp->status == nlm_granted)
690        goto out;
691
692    if (resp->status != nlm_lck_denied_nolocks)
693        printk("lockd: unexpected unlock status: %d\n", resp->status);
694    /* What to do now? I'm out of my depth... */
695    status = -ENOLCK;
696out:
697    nlmclnt_release_call(req);
698    return status;
699}
700
701static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
702{
703    struct nlm_rqst *req = data;
704    u32 status = ntohl(req->a_res.status);
705
706    if (RPC_ASSASSINATED(task))
707        goto die;
708
709    if (task->tk_status < 0) {
710        dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
711        switch (task->tk_status) {
712        case -EACCES:
713        case -EIO:
714            goto die;
715        default:
716            goto retry_rebind;
717        }
718    }
719    if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
720        rpc_delay(task, NLMCLNT_GRACE_WAIT);
721        goto retry_unlock;
722    }
723    if (status != NLM_LCK_GRANTED)
724        printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
725die:
726    return;
727 retry_rebind:
728    nlm_rebind_host(req->a_host);
729 retry_unlock:
730    rpc_restart_call(task);
731}
732
733static const struct rpc_call_ops nlmclnt_unlock_ops = {
734    .rpc_call_done = nlmclnt_unlock_callback,
735    .rpc_release = nlmclnt_rpc_release,
736};
737
738/*
739 * Cancel a blocked lock request.
740 * We always use an async RPC call for this in order not to hang a
741 * process that has been Ctrl-C'ed.
742 */
743static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
744{
745    struct nlm_rqst *req;
746    int status;
747
748    dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
749        " Attempting to cancel lock.\n");
750
751    req = nlm_alloc_call(nlm_get_host(host));
752    if (!req)
753        return -ENOMEM;
754    req->a_flags = RPC_TASK_ASYNC;
755
756    nlmclnt_setlockargs(req, fl);
757    req->a_args.block = block;
758
759    atomic_inc(&req->a_count);
760    status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
761            NLMPROC_CANCEL, &nlmclnt_cancel_ops);
762    if (status == 0 && req->a_res.status == nlm_lck_denied)
763        status = -ENOLCK;
764    nlmclnt_release_call(req);
765    return status;
766}
767
768static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
769{
770    struct nlm_rqst *req = data;
771    u32 status = ntohl(req->a_res.status);
772
773    if (RPC_ASSASSINATED(task))
774        goto die;
775
776    if (task->tk_status < 0) {
777        dprintk("lockd: CANCEL call error %d, retrying.\n",
778                    task->tk_status);
779        goto retry_cancel;
780    }
781
782    dprintk("lockd: cancel status %u (task %u)\n",
783            status, task->tk_pid);
784
785    switch (status) {
786    case NLM_LCK_GRANTED:
787    case NLM_LCK_DENIED_GRACE_PERIOD:
788    case NLM_LCK_DENIED:
789        /* Everything's good */
790        break;
791    case NLM_LCK_DENIED_NOLOCKS:
792        dprintk("lockd: CANCEL failed (server has no locks)\n");
793        goto retry_cancel;
794    default:
795        printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
796            status);
797    }
798
799die:
800    return;
801
802retry_cancel:
803    /* Don't ever retry more than 3 times */
804    if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
805        goto die;
806    nlm_rebind_host(req->a_host);
807    rpc_restart_call(task);
808    rpc_delay(task, 30 * HZ);
809}
810
811static const struct rpc_call_ops nlmclnt_cancel_ops = {
812    .rpc_call_done = nlmclnt_cancel_callback,
813    .rpc_release = nlmclnt_rpc_release,
814};
815
816/*
817 * Convert an NLM status code to a generic kernel errno
818 */
819static int
820nlm_stat_to_errno(__be32 status)
821{
822    switch(ntohl(status)) {
823    case NLM_LCK_GRANTED:
824        return 0;
825    case NLM_LCK_DENIED:
826        return -EAGAIN;
827    case NLM_LCK_DENIED_NOLOCKS:
828    case NLM_LCK_DENIED_GRACE_PERIOD:
829        return -ENOLCK;
830    case NLM_LCK_BLOCKED:
831        printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
832        return -ENOLCK;
833#ifdef CONFIG_LOCKD_V4
834    case NLM_DEADLCK:
835        return -EDEADLK;
836    case NLM_ROFS:
837        return -EROFS;
838    case NLM_STALE_FH:
839        return -ESTALE;
840    case NLM_FBIG:
841        return -EOVERFLOW;
842    case NLM_FAILED:
843        return -ENOLCK;
844#endif
845    }
846    printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
847    return -ENOLCK;
848}
849

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