nfsd4: cl_count is unused
[safe/jmp/linux-2.6] / fs / nfsd / nfs4callback.c
1 /*
2  *  Copyright (c) 2001 The Regents of the University of Michigan.
3  *  All rights reserved.
4  *
5  *  Kendrick Smith <kmsmith@umich.edu>
6  *  Andy Adamson <andros@umich.edu>
7  *
8  *  Redistribution and use in source and binary forms, with or without
9  *  modification, are permitted provided that the following conditions
10  *  are met:
11  *
12  *  1. Redistributions of source code must retain the above copyright
13  *     notice, this list of conditions and the following disclaimer.
14  *  2. Redistributions in binary form must reproduce the above copyright
15  *     notice, this list of conditions and the following disclaimer in the
16  *     documentation and/or other materials provided with the distribution.
17  *  3. Neither the name of the University nor the names of its
18  *     contributors may be used to endorse or promote products derived
19  *     from this software without specific prior written permission.
20  *
21  *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
22  *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24  *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
28  *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
29  *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
30  *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33
34 #include <linux/sunrpc/clnt.h>
35 #include <linux/sunrpc/svc_xprt.h>
36 #include "nfsd.h"
37 #include "state.h"
38
39 #define NFSDDBG_FACILITY                NFSDDBG_PROC
40
41 #define NFSPROC4_CB_NULL 0
42 #define NFSPROC4_CB_COMPOUND 1
43 #define NFS4_STATEID_SIZE 16
44
45 /* Index of predefined Linux callback client operations */
46
47 enum {
48         NFSPROC4_CLNT_CB_NULL = 0,
49         NFSPROC4_CLNT_CB_RECALL,
50         NFSPROC4_CLNT_CB_SEQUENCE,
51 };
52
53 enum nfs_cb_opnum4 {
54         OP_CB_RECALL            = 4,
55         OP_CB_SEQUENCE          = 11,
56 };
57
58 #define NFS4_MAXTAGLEN          20
59
60 #define NFS4_enc_cb_null_sz             0
61 #define NFS4_dec_cb_null_sz             0
62 #define cb_compound_enc_hdr_sz          4
63 #define cb_compound_dec_hdr_sz          (3 + (NFS4_MAXTAGLEN >> 2))
64 #define sessionid_sz                    (NFS4_MAX_SESSIONID_LEN >> 2)
65 #define cb_sequence_enc_sz              (sessionid_sz + 4 +             \
66                                         1 /* no referring calls list yet */)
67 #define cb_sequence_dec_sz              (op_dec_sz + sessionid_sz + 4)
68
69 #define op_enc_sz                       1
70 #define op_dec_sz                       2
71 #define enc_nfs4_fh_sz                  (1 + (NFS4_FHSIZE >> 2))
72 #define enc_stateid_sz                  (NFS4_STATEID_SIZE >> 2)
73 #define NFS4_enc_cb_recall_sz           (cb_compound_enc_hdr_sz +       \
74                                         cb_sequence_enc_sz +            \
75                                         1 + enc_stateid_sz +            \
76                                         enc_nfs4_fh_sz)
77
78 #define NFS4_dec_cb_recall_sz           (cb_compound_dec_hdr_sz  +      \
79                                         cb_sequence_dec_sz +            \
80                                         op_dec_sz)
81
82 /*
83 * Generic encode routines from fs/nfs/nfs4xdr.c
84 */
85 static inline __be32 *
86 xdr_writemem(__be32 *p, const void *ptr, int nbytes)
87 {
88         int tmp = XDR_QUADLEN(nbytes);
89         if (!tmp)
90                 return p;
91         p[tmp-1] = 0;
92         memcpy(p, ptr, nbytes);
93         return p + tmp;
94 }
95
96 #define WRITE32(n)               *p++ = htonl(n)
97 #define WRITEMEM(ptr,nbytes)     do {                           \
98         p = xdr_writemem(p, ptr, nbytes);                       \
99 } while (0)
100 #define RESERVE_SPACE(nbytes)   do {                            \
101         p = xdr_reserve_space(xdr, nbytes);                     \
102         if (!p) dprintk("NFSD: RESERVE_SPACE(%d) failed in function %s\n", (int) (nbytes), __func__); \
103         BUG_ON(!p);                                             \
104 } while (0)
105
106 /*
107  * Generic decode routines from fs/nfs/nfs4xdr.c
108  */
109 #define DECODE_TAIL                             \
110         status = 0;                             \
111 out:                                            \
112         return status;                          \
113 xdr_error:                                      \
114         dprintk("NFSD: xdr error! (%s:%d)\n", __FILE__, __LINE__); \
115         status = -EIO;                          \
116         goto out
117
118 #define READ32(x)         (x) = ntohl(*p++)
119 #define READ64(x)         do {                  \
120         (x) = (u64)ntohl(*p++) << 32;           \
121         (x) |= ntohl(*p++);                     \
122 } while (0)
123 #define READTIME(x)       do {                  \
124         p++;                                    \
125         (x.tv_sec) = ntohl(*p++);               \
126         (x.tv_nsec) = ntohl(*p++);              \
127 } while (0)
128 #define READ_BUF(nbytes)  do { \
129         p = xdr_inline_decode(xdr, nbytes); \
130         if (!p) { \
131                 dprintk("NFSD: %s: reply buffer overflowed in line %d.\n", \
132                         __func__, __LINE__); \
133                 return -EIO; \
134         } \
135 } while (0)
136
137 struct nfs4_cb_compound_hdr {
138         /* args */
139         u32             ident;  /* minorversion 0 only */
140         u32             nops;
141         __be32          *nops_p;
142         u32             minorversion;
143         /* res */
144         int             status;
145         u32             taglen;
146         char            *tag;
147 };
148
149 static struct {
150 int stat;
151 int errno;
152 } nfs_cb_errtbl[] = {
153         { NFS4_OK,              0               },
154         { NFS4ERR_PERM,         EPERM           },
155         { NFS4ERR_NOENT,        ENOENT          },
156         { NFS4ERR_IO,           EIO             },
157         { NFS4ERR_NXIO,         ENXIO           },
158         { NFS4ERR_ACCESS,       EACCES          },
159         { NFS4ERR_EXIST,        EEXIST          },
160         { NFS4ERR_XDEV,         EXDEV           },
161         { NFS4ERR_NOTDIR,       ENOTDIR         },
162         { NFS4ERR_ISDIR,        EISDIR          },
163         { NFS4ERR_INVAL,        EINVAL          },
164         { NFS4ERR_FBIG,         EFBIG           },
165         { NFS4ERR_NOSPC,        ENOSPC          },
166         { NFS4ERR_ROFS,         EROFS           },
167         { NFS4ERR_MLINK,        EMLINK          },
168         { NFS4ERR_NAMETOOLONG,  ENAMETOOLONG    },
169         { NFS4ERR_NOTEMPTY,     ENOTEMPTY       },
170         { NFS4ERR_DQUOT,        EDQUOT          },
171         { NFS4ERR_STALE,        ESTALE          },
172         { NFS4ERR_BADHANDLE,    EBADHANDLE      },
173         { NFS4ERR_BAD_COOKIE,   EBADCOOKIE      },
174         { NFS4ERR_NOTSUPP,      ENOTSUPP        },
175         { NFS4ERR_TOOSMALL,     ETOOSMALL       },
176         { NFS4ERR_SERVERFAULT,  ESERVERFAULT    },
177         { NFS4ERR_BADTYPE,      EBADTYPE        },
178         { NFS4ERR_LOCKED,       EAGAIN          },
179         { NFS4ERR_RESOURCE,     EREMOTEIO       },
180         { NFS4ERR_SYMLINK,      ELOOP           },
181         { NFS4ERR_OP_ILLEGAL,   EOPNOTSUPP      },
182         { NFS4ERR_DEADLOCK,     EDEADLK         },
183         { -1,                   EIO             }
184 };
185
186 static int
187 nfs_cb_stat_to_errno(int stat)
188 {
189         int i;
190         for (i = 0; nfs_cb_errtbl[i].stat != -1; i++) {
191                 if (nfs_cb_errtbl[i].stat == stat)
192                         return nfs_cb_errtbl[i].errno;
193         }
194         /* If we cannot translate the error, the recovery routines should
195         * handle it.
196         * Note: remaining NFSv4 error codes have values > 10000, so should
197         * not conflict with native Linux error codes.
198         */
199         return stat;
200 }
201
202 /*
203  * XDR encode
204  */
205
206 static void
207 encode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr)
208 {
209         __be32 * p;
210
211         RESERVE_SPACE(16);
212         WRITE32(0);            /* tag length is always 0 */
213         WRITE32(hdr->minorversion);
214         WRITE32(hdr->ident);
215         hdr->nops_p = p;
216         WRITE32(hdr->nops);
217 }
218
219 static void encode_cb_nops(struct nfs4_cb_compound_hdr *hdr)
220 {
221         *hdr->nops_p = htonl(hdr->nops);
222 }
223
224 static void
225 encode_cb_recall(struct xdr_stream *xdr, struct nfs4_delegation *dp,
226                 struct nfs4_cb_compound_hdr *hdr)
227 {
228         __be32 *p;
229         int len = dp->dl_fh.fh_size;
230
231         RESERVE_SPACE(12+sizeof(dp->dl_stateid) + len);
232         WRITE32(OP_CB_RECALL);
233         WRITE32(dp->dl_stateid.si_generation);
234         WRITEMEM(&dp->dl_stateid.si_opaque, sizeof(stateid_opaque_t));
235         WRITE32(0); /* truncate optimization not implemented */
236         WRITE32(len);
237         WRITEMEM(&dp->dl_fh.fh_base, len);
238         hdr->nops++;
239 }
240
241 static void
242 encode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *args,
243                    struct nfs4_cb_compound_hdr *hdr)
244 {
245         __be32 *p;
246
247         if (hdr->minorversion == 0)
248                 return;
249
250         RESERVE_SPACE(1 + NFS4_MAX_SESSIONID_LEN + 20);
251
252         WRITE32(OP_CB_SEQUENCE);
253         WRITEMEM(args->cbs_clp->cl_sessionid.data, NFS4_MAX_SESSIONID_LEN);
254         WRITE32(args->cbs_clp->cl_cb_seq_nr);
255         WRITE32(0);             /* slotid, always 0 */
256         WRITE32(0);             /* highest slotid always 0 */
257         WRITE32(0);             /* cachethis always 0 */
258         WRITE32(0); /* FIXME: support referring_call_lists */
259         hdr->nops++;
260 }
261
262 static int
263 nfs4_xdr_enc_cb_null(struct rpc_rqst *req, __be32 *p)
264 {
265         struct xdr_stream xdrs, *xdr = &xdrs;
266
267         xdr_init_encode(&xdrs, &req->rq_snd_buf, p);
268         RESERVE_SPACE(0);
269         return 0;
270 }
271
272 static int
273 nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
274                 struct nfs4_rpc_args *rpc_args)
275 {
276         struct xdr_stream xdr;
277         struct nfs4_delegation *args = rpc_args->args_op;
278         struct nfs4_cb_compound_hdr hdr = {
279                 .ident = args->dl_ident,
280                 .minorversion = rpc_args->args_seq.cbs_minorversion,
281         };
282
283         xdr_init_encode(&xdr, &req->rq_snd_buf, p);
284         encode_cb_compound_hdr(&xdr, &hdr);
285         encode_cb_sequence(&xdr, &rpc_args->args_seq, &hdr);
286         encode_cb_recall(&xdr, args, &hdr);
287         encode_cb_nops(&hdr);
288         return 0;
289 }
290
291
292 static int
293 decode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr){
294         __be32 *p;
295
296         READ_BUF(8);
297         READ32(hdr->status);
298         READ32(hdr->taglen);
299         READ_BUF(hdr->taglen + 4);
300         hdr->tag = (char *)p;
301         p += XDR_QUADLEN(hdr->taglen);
302         READ32(hdr->nops);
303         return 0;
304 }
305
306 static int
307 decode_cb_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
308 {
309         __be32 *p;
310         u32 op;
311         int32_t nfserr;
312
313         READ_BUF(8);
314         READ32(op);
315         if (op != expected) {
316                 dprintk("NFSD: decode_cb_op_hdr: Callback server returned "
317                          " operation %d but we issued a request for %d\n",
318                          op, expected);
319                 return -EIO;
320         }
321         READ32(nfserr);
322         if (nfserr != NFS_OK)
323                 return -nfs_cb_stat_to_errno(nfserr);
324         return 0;
325 }
326
327 /*
328  * Our current back channel implmentation supports a single backchannel
329  * with a single slot.
330  */
331 static int
332 decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *res,
333                    struct rpc_rqst *rqstp)
334 {
335         struct nfs4_sessionid id;
336         int status;
337         u32 dummy;
338         __be32 *p;
339
340         if (res->cbs_minorversion == 0)
341                 return 0;
342
343         status = decode_cb_op_hdr(xdr, OP_CB_SEQUENCE);
344         if (status)
345                 return status;
346
347         /*
348          * If the server returns different values for sessionID, slotID or
349          * sequence number, the server is looney tunes.
350          */
351         status = -ESERVERFAULT;
352
353         READ_BUF(NFS4_MAX_SESSIONID_LEN + 16);
354         memcpy(id.data, p, NFS4_MAX_SESSIONID_LEN);
355         p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN);
356         if (memcmp(id.data, res->cbs_clp->cl_sessionid.data,
357                    NFS4_MAX_SESSIONID_LEN)) {
358                 dprintk("%s Invalid session id\n", __func__);
359                 goto out;
360         }
361         READ32(dummy);
362         if (dummy != res->cbs_clp->cl_cb_seq_nr) {
363                 dprintk("%s Invalid sequence number\n", __func__);
364                 goto out;
365         }
366         READ32(dummy);  /* slotid must be 0 */
367         if (dummy != 0) {
368                 dprintk("%s Invalid slotid\n", __func__);
369                 goto out;
370         }
371         /* FIXME: process highest slotid and target highest slotid */
372         status = 0;
373 out:
374         return status;
375 }
376
377
378 static int
379 nfs4_xdr_dec_cb_null(struct rpc_rqst *req, __be32 *p)
380 {
381         return 0;
382 }
383
384 static int
385 nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p,
386                 struct nfsd4_cb_sequence *seq)
387 {
388         struct xdr_stream xdr;
389         struct nfs4_cb_compound_hdr hdr;
390         int status;
391
392         xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
393         status = decode_cb_compound_hdr(&xdr, &hdr);
394         if (status)
395                 goto out;
396         if (seq) {
397                 status = decode_cb_sequence(&xdr, seq, rqstp);
398                 if (status)
399                         goto out;
400         }
401         status = decode_cb_op_hdr(&xdr, OP_CB_RECALL);
402 out:
403         return status;
404 }
405
406 /*
407  * RPC procedure tables
408  */
409 #define PROC(proc, call, argtype, restype)                              \
410 [NFSPROC4_CLNT_##proc] = {                                              \
411         .p_proc   = NFSPROC4_CB_##call,                                 \
412         .p_encode = (kxdrproc_t) nfs4_xdr_##argtype,                    \
413         .p_decode = (kxdrproc_t) nfs4_xdr_##restype,                    \
414         .p_arglen = NFS4_##argtype##_sz,                                \
415         .p_replen = NFS4_##restype##_sz,                                \
416         .p_statidx = NFSPROC4_CB_##call,                                \
417         .p_name   = #proc,                                              \
418 }
419
420 static struct rpc_procinfo     nfs4_cb_procedures[] = {
421     PROC(CB_NULL,      NULL,     enc_cb_null,     dec_cb_null),
422     PROC(CB_RECALL,    COMPOUND,   enc_cb_recall,      dec_cb_recall),
423 };
424
425 static struct rpc_version       nfs_cb_version4 = {
426         .number                 = 1,
427         .nrprocs                = ARRAY_SIZE(nfs4_cb_procedures),
428         .procs                  = nfs4_cb_procedures
429 };
430
431 static struct rpc_version *     nfs_cb_version[] = {
432         NULL,
433         &nfs_cb_version4,
434 };
435
436 static struct rpc_program cb_program;
437
438 static struct rpc_stat cb_stats = {
439                 .program        = &cb_program
440 };
441
442 #define NFS4_CALLBACK 0x40000000
443 static struct rpc_program cb_program = {
444                 .name           = "nfs4_cb",
445                 .number         = NFS4_CALLBACK,
446                 .nrvers         = ARRAY_SIZE(nfs_cb_version),
447                 .version        = nfs_cb_version,
448                 .stats          = &cb_stats,
449                 .pipe_dir_name  = "/nfsd4_cb",
450 };
451
452 static int max_cb_time(void)
453 {
454         return max(nfsd4_lease/10, (time_t)1) * HZ;
455 }
456
457 /* Reference counting, callback cleanup, etc., all look racy as heck.
458  * And why is cb_set an atomic? */
459
460 int setup_callback_client(struct nfs4_client *clp)
461 {
462         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
463         struct rpc_timeout      timeparms = {
464                 .to_initval     = max_cb_time(),
465                 .to_retries     = 0,
466         };
467         struct rpc_create_args args = {
468                 .protocol       = XPRT_TRANSPORT_TCP,
469                 .address        = (struct sockaddr *) &cb->cb_addr,
470                 .addrsize       = cb->cb_addrlen,
471                 .timeout        = &timeparms,
472                 .program        = &cb_program,
473                 .prognumber     = cb->cb_prog,
474                 .version        = nfs_cb_version[1]->number,
475                 .authflavor     = clp->cl_flavor,
476                 .flags          = (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
477                 .client_name    = clp->cl_principal,
478         };
479         struct rpc_clnt *client;
480
481         if (!clp->cl_principal && (clp->cl_flavor >= RPC_AUTH_GSS_KRB5))
482                 return -EINVAL;
483         if (cb->cb_minorversion) {
484                 args.bc_xprt = clp->cl_cb_xprt;
485                 args.protocol = XPRT_TRANSPORT_BC_TCP;
486         }
487         /* Create RPC client */
488         client = rpc_create(&args);
489         if (IS_ERR(client)) {
490                 dprintk("NFSD: couldn't create callback client: %ld\n",
491                         PTR_ERR(client));
492                 return PTR_ERR(client);
493         }
494         cb->cb_client = client;
495         return 0;
496
497 }
498
499 static void warn_no_callback_path(struct nfs4_client *clp, int reason)
500 {
501         dprintk("NFSD: warning: no callback path to client %.*s: error %d\n",
502                 (int)clp->cl_name.len, clp->cl_name.data, reason);
503 }
504
505 static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
506 {
507         struct nfs4_client *clp = calldata;
508
509         if (task->tk_status)
510                 warn_no_callback_path(clp, task->tk_status);
511         else
512                 atomic_set(&clp->cl_cb_conn.cb_set, 1);
513 }
514
515 static const struct rpc_call_ops nfsd4_cb_probe_ops = {
516         .rpc_call_done = nfsd4_cb_probe_done,
517 };
518
519 static struct rpc_cred *callback_cred;
520
521 int set_callback_cred(void)
522 {
523         if (callback_cred)
524                 return 0;
525         callback_cred = rpc_lookup_machine_cred();
526         if (!callback_cred)
527                 return -ENOMEM;
528         return 0;
529 }
530
531
532 void do_probe_callback(struct nfs4_client *clp)
533 {
534         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
535         struct rpc_message msg = {
536                 .rpc_proc       = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL],
537                 .rpc_argp       = clp,
538                 .rpc_cred       = callback_cred
539         };
540         int status;
541
542         status = rpc_call_async(cb->cb_client, &msg,
543                                 RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
544                                 &nfsd4_cb_probe_ops, (void *)clp);
545         if (status)
546                 warn_no_callback_path(clp, status);
547 }
548
549 /*
550  * Set up the callback client and put a NFSPROC4_CB_NULL on the wire...
551  */
552 void
553 nfsd4_probe_callback(struct nfs4_client *clp)
554 {
555         int status;
556
557         BUG_ON(atomic_read(&clp->cl_cb_conn.cb_set));
558
559         status = setup_callback_client(clp);
560         if (status) {
561                 warn_no_callback_path(clp, status);
562                 return;
563         }
564         do_probe_callback(clp);
565 }
566
567 /*
568  * There's currently a single callback channel slot.
569  * If the slot is available, then mark it busy.  Otherwise, set the
570  * thread for sleeping on the callback RPC wait queue.
571  */
572 static int nfsd41_cb_setup_sequence(struct nfs4_client *clp,
573                 struct rpc_task *task)
574 {
575         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
576         u32 *ptr = (u32 *)clp->cl_sessionid.data;
577         int status = 0;
578
579         dprintk("%s: %u:%u:%u:%u\n", __func__,
580                 ptr[0], ptr[1], ptr[2], ptr[3]);
581
582         if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
583                 rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
584                 dprintk("%s slot is busy\n", __func__);
585                 status = -EAGAIN;
586                 goto out;
587         }
588
589         /*
590          * We'll need the clp during XDR encoding and decoding,
591          * and the sequence during decoding to verify the reply
592          */
593         args->args_seq.cbs_clp = clp;
594         task->tk_msg.rpc_resp = &args->args_seq;
595
596 out:
597         dprintk("%s status=%d\n", __func__, status);
598         return status;
599 }
600
601 /*
602  * TODO: cb_sequence should support referring call lists, cachethis, multiple
603  * slots, and mark callback channel down on communication errors.
604  */
605 static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
606 {
607         struct nfs4_delegation *dp = calldata;
608         struct nfs4_client *clp = dp->dl_client;
609         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
610         u32 minorversion = clp->cl_cb_conn.cb_minorversion;
611         int status = 0;
612
613         args->args_seq.cbs_minorversion = minorversion;
614         if (minorversion) {
615                 status = nfsd41_cb_setup_sequence(clp, task);
616                 if (status) {
617                         if (status != -EAGAIN) {
618                                 /* terminate rpc task */
619                                 task->tk_status = status;
620                                 task->tk_action = NULL;
621                         }
622                         return;
623                 }
624         }
625         rpc_call_start(task);
626 }
627
628 static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
629 {
630         struct nfs4_delegation *dp = calldata;
631         struct nfs4_client *clp = dp->dl_client;
632
633         dprintk("%s: minorversion=%d\n", __func__,
634                 clp->cl_cb_conn.cb_minorversion);
635
636         if (clp->cl_cb_conn.cb_minorversion) {
637                 /* No need for lock, access serialized in nfsd4_cb_prepare */
638                 ++clp->cl_cb_seq_nr;
639                 clear_bit(0, &clp->cl_cb_slot_busy);
640                 rpc_wake_up_next(&clp->cl_cb_waitq);
641                 dprintk("%s: freed slot, new seqid=%d\n", __func__,
642                         clp->cl_cb_seq_nr);
643
644                 /* We're done looking into the sequence information */
645                 task->tk_msg.rpc_resp = NULL;
646         }
647 }
648
649 static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
650 {
651         struct nfs4_delegation *dp = calldata;
652         struct nfs4_client *clp = dp->dl_client;
653
654         nfsd4_cb_done(task, calldata);
655
656         switch (task->tk_status) {
657         case -EIO:
658                 /* Network partition? */
659                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
660                 warn_no_callback_path(clp, task->tk_status);
661         case -EBADHANDLE:
662         case -NFS4ERR_BAD_STATEID:
663                 /* Race: client probably got cb_recall
664                  * before open reply granting delegation */
665                 break;
666         default:
667                 /* success, or error we can't handle */
668                 return;
669         }
670         if (dp->dl_retries--) {
671                 rpc_delay(task, 2*HZ);
672                 task->tk_status = 0;
673                 rpc_restart_call(task);
674                 return;
675         } else {
676                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
677                 warn_no_callback_path(clp, task->tk_status);
678         }
679 }
680
681 static void nfsd4_cb_recall_release(void *calldata)
682 {
683         struct nfs4_delegation *dp = calldata;
684
685         nfs4_put_delegation(dp);
686 }
687
688 static const struct rpc_call_ops nfsd4_cb_recall_ops = {
689         .rpc_call_prepare = nfsd4_cb_prepare,
690         .rpc_call_done = nfsd4_cb_recall_done,
691         .rpc_release = nfsd4_cb_recall_release,
692 };
693
694 static struct workqueue_struct *callback_wq;
695
696 int nfsd4_create_callback_queue(void)
697 {
698         callback_wq = create_singlethread_workqueue("nfsd4_callbacks");
699         if (!callback_wq)
700                 return -ENOMEM;
701         return 0;
702 }
703
704 void nfsd4_destroy_callback_queue(void)
705 {
706         destroy_workqueue(callback_wq);
707 }
708
709 void nfsd4_set_callback_client(struct nfs4_client *clp, struct rpc_clnt
710 *new)
711 {
712         struct rpc_clnt *old = clp->cl_cb_conn.cb_client;
713
714         clp->cl_cb_conn.cb_client = new;
715         /*
716          * After this, any work that saw the old value of cb_client will
717          * be gone:
718          */
719         flush_workqueue(callback_wq);
720         /* So we can safely shut it down: */
721         if (old)
722                 rpc_shutdown_client(old);
723 }
724
725 /*
726  * called with dp->dl_count inc'ed.
727  */
728 static void _nfsd4_cb_recall(struct nfs4_delegation *dp)
729 {
730         struct nfs4_client *clp = dp->dl_client;
731         struct rpc_clnt *clnt = clp->cl_cb_conn.cb_client;
732         struct nfs4_rpc_args *args = &dp->dl_recall.cb_args;
733         struct rpc_message msg = {
734                 .rpc_proc = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_RECALL],
735                 .rpc_cred = callback_cred
736         };
737         int status;
738
739         if (clnt == NULL)
740                 return; /* Client is shutting down; give up. */
741
742         args->args_op = dp;
743         msg.rpc_argp = args;
744         dp->dl_retries = 1;
745         status = rpc_call_async(clnt, &msg, RPC_TASK_SOFT,
746                                 &nfsd4_cb_recall_ops, dp);
747         if (status)
748                 nfs4_put_delegation(dp);
749 }
750
751 void nfsd4_do_callback_rpc(struct work_struct *w)
752 {
753         /* XXX: for now, just send off delegation recall. */
754         /* In future, generalize to handle any sort of callback. */
755         struct nfsd4_callback *c = container_of(w, struct nfsd4_callback, cb_work);
756         struct nfs4_delegation *dp = container_of(c, struct nfs4_delegation, dl_recall);
757
758         _nfsd4_cb_recall(dp);
759 }
760
761
762 void nfsd4_cb_recall(struct nfs4_delegation *dp)
763 {
764         queue_work(callback_wq, &dp->dl_recall.cb_work);
765 }