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   1 /*
   2  *  linux/fs/nfsd/nfs4callback.c
   3  *
   4  *  Copyright (c) 2001 The Regents of the University of Michigan.
   5  *  All rights reserved.
   6  *
   7  *  Kendrick Smith <kmsmith@umich.edu>
   8  *  Andy Adamson <andros@umich.edu>
   9  *
  10  *  Redistribution and use in source and binary forms, with or without
  11  *  modification, are permitted provided that the following conditions
  12  *  are met:
  13  *
  14  *  1. Redistributions of source code must retain the above copyright
  15  *     notice, this list of conditions and the following disclaimer.
  16  *  2. Redistributions in binary form must reproduce the above copyright
  17  *     notice, this list of conditions and the following disclaimer in the
  18  *     documentation and/or other materials provided with the distribution.
  19  *  3. Neither the name of the University nor the names of its
  20  *     contributors may be used to endorse or promote products derived
  21  *     from this software without specific prior written permission.
  22  *
  23  *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  24  *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  25  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  26  *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  28  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  29  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  30  *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  31  *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  32  *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  33  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include <linux/sunrpc/clnt.h>
  37 #include <linux/nfsd/nfsd.h>
  38 #include <linux/nfsd/state.h>
  39
  40 #define NFSDDBG_FACILITY                NFSDDBG_PROC
  41
  42 #define NFSPROC4_CB_NULL 0
  43 #define NFSPROC4_CB_COMPOUND 1
  44 #define NFS4_STATEID_SIZE 16
  45
  46 /* Index of predefined Linux callback client operations */
  47
  48 enum {
  49         NFSPROC4_CLNT_CB_NULL = 0,
  50         NFSPROC4_CLNT_CB_RECALL,
  51         NFSPROC4_CLNT_CB_SEQUENCE,
  52 };
  53
  54 enum nfs_cb_opnum4 {
  55         OP_CB_RECALL            = 4,
  56         OP_CB_SEQUENCE          = 11,
  57 };
  58
  59 #define NFS4_MAXTAGLEN          20
  60
  61 #define NFS4_enc_cb_null_sz             0
  62 #define NFS4_dec_cb_null_sz             0
  63 #define cb_compound_enc_hdr_sz          4
  64 #define cb_compound_dec_hdr_sz          (3 + (NFS4_MAXTAGLEN >> 2))
  65 #define sessionid_sz                    (NFS4_MAX_SESSIONID_LEN >> 2)
  66 #define cb_sequence_enc_sz              (sessionid_sz + 4 +             \
  67                                         1 /* no referring calls list yet */)
  68 #define cb_sequence_dec_sz              (op_dec_sz + sessionid_sz + 4)
  69
  70 #define op_enc_sz                       1
  71 #define op_dec_sz                       2
  72 #define enc_nfs4_fh_sz                  (1 + (NFS4_FHSIZE >> 2))
  73 #define enc_stateid_sz                  (NFS4_STATEID_SIZE >> 2)
  74 #define NFS4_enc_cb_recall_sz           (cb_compound_enc_hdr_sz +       \
  75                                         cb_sequence_enc_sz +            \
  76                                         1 + enc_stateid_sz +            \
  77                                         enc_nfs4_fh_sz)
  78
  79 #define NFS4_dec_cb_recall_sz           (cb_compound_dec_hdr_sz  +      \
  80                                         cb_sequence_dec_sz +            \
  81                                         op_dec_sz)
  82
  83 struct nfs4_rpc_args {
  84         void                            *args_op;
  85         struct nfsd4_cb_sequence        args_seq;
  86 };
  87
  88 /*
  89 * Generic encode routines from fs/nfs/nfs4xdr.c
  90 */
  91 static inline __be32 *
  92 xdr_writemem(__be32 *p, const void *ptr, int nbytes)
  93 {
  94         int tmp = XDR_QUADLEN(nbytes);
  95         if (!tmp)
  96                 return p;
  97         p[tmp-1] = 0;
  98         memcpy(p, ptr, nbytes);
  99         return p + tmp;
 100 }
 101
 102 #define WRITE32(n)               *p++ = htonl(n)
 103 #define WRITEMEM(ptr,nbytes)     do {                           \
 104         p = xdr_writemem(p, ptr, nbytes);                       \
 105 } while (0)
 106 #define RESERVE_SPACE(nbytes)   do {                            \
 107         p = xdr_reserve_space(xdr, nbytes);                     \
 108         if (!p) dprintk("NFSD: RESERVE_SPACE(%d) failed in function %s\n", (int) (nbytes), __func__); \
 109         BUG_ON(!p);                                             \
 110 } while (0)
 111
 112 /*
 113  * Generic decode routines from fs/nfs/nfs4xdr.c
 114  */
 115 #define DECODE_TAIL                             \
 116         status = 0;                             \
 117 out:                                            \
 118         return status;                          \
 119 xdr_error:                                      \
 120         dprintk("NFSD: xdr error! (%s:%d)\n", __FILE__, __LINE__); \
 121         status = -EIO;                          \
 122         goto out
 123
 124 #define READ32(x)         (x) = ntohl(*p++)
 125 #define READ64(x)         do {                  \
 126         (x) = (u64)ntohl(*p++) << 32;           \
 127         (x) |= ntohl(*p++);                     \
 128 } while (0)
 129 #define READTIME(x)       do {                  \
 130         p++;                                    \
 131         (x.tv_sec) = ntohl(*p++);               \
 132         (x.tv_nsec) = ntohl(*p++);              \
 133 } while (0)
 134 #define READ_BUF(nbytes)  do { \
 135         p = xdr_inline_decode(xdr, nbytes); \
 136         if (!p) { \
 137                 dprintk("NFSD: %s: reply buffer overflowed in line %d.\n", \
 138                         __func__, __LINE__); \
 139                 return -EIO; \
 140         } \
 141 } while (0)
 142
 143 struct nfs4_cb_compound_hdr {
 144         /* args */
 145         u32             ident;  /* minorversion 0 only */
 146         u32             nops;
 147         __be32          *nops_p;
 148         u32             minorversion;
 149         /* res */
 150         int             status;
 151         u32             taglen;
 152         char            *tag;
 153 };
 154
 155 static struct {
 156 int stat;
 157 int errno;
 158 } nfs_cb_errtbl[] = {
 159         { NFS4_OK,              0               },
 160         { NFS4ERR_PERM,         EPERM           },
 161         { NFS4ERR_NOENT,        ENOENT          },
 162         { NFS4ERR_IO,           EIO             },
 163         { NFS4ERR_NXIO,         ENXIO           },
 164         { NFS4ERR_ACCESS,       EACCES          },
 165         { NFS4ERR_EXIST,        EEXIST          },
 166         { NFS4ERR_XDEV,         EXDEV           },
 167         { NFS4ERR_NOTDIR,       ENOTDIR         },
 168         { NFS4ERR_ISDIR,        EISDIR          },
 169         { NFS4ERR_INVAL,        EINVAL          },
 170         { NFS4ERR_FBIG,         EFBIG           },
 171         { NFS4ERR_NOSPC,        ENOSPC          },
 172         { NFS4ERR_ROFS,         EROFS           },
 173         { NFS4ERR_MLINK,        EMLINK          },
 174         { NFS4ERR_NAMETOOLONG,  ENAMETOOLONG    },
 175         { NFS4ERR_NOTEMPTY,     ENOTEMPTY       },
 176         { NFS4ERR_DQUOT,        EDQUOT          },
 177         { NFS4ERR_STALE,        ESTALE          },
 178         { NFS4ERR_BADHANDLE,    EBADHANDLE      },
 179         { NFS4ERR_BAD_COOKIE,   EBADCOOKIE      },
 180         { NFS4ERR_NOTSUPP,      ENOTSUPP        },
 181         { NFS4ERR_TOOSMALL,     ETOOSMALL       },
 182         { NFS4ERR_SERVERFAULT,  ESERVERFAULT    },
 183         { NFS4ERR_BADTYPE,      EBADTYPE        },
 184         { NFS4ERR_LOCKED,       EAGAIN          },
 185         { NFS4ERR_RESOURCE,     EREMOTEIO       },
 186         { NFS4ERR_SYMLINK,      ELOOP           },
 187         { NFS4ERR_OP_ILLEGAL,   EOPNOTSUPP      },
 188         { NFS4ERR_DEADLOCK,     EDEADLK         },
 189         { -1,                   EIO             }
 190 };
 191
 192 static int
 193 nfs_cb_stat_to_errno(int stat)
 194 {
 195         int i;
 196         for (i = 0; nfs_cb_errtbl[i].stat != -1; i++) {
 197                 if (nfs_cb_errtbl[i].stat == stat)
 198                         return nfs_cb_errtbl[i].errno;
 199         }
 200         /* If we cannot translate the error, the recovery routines should
 201         * handle it.
 202         * Note: remaining NFSv4 error codes have values > 10000, so should
 203         * not conflict with native Linux error codes.
 204         */
 205         return stat;
 206 }
 207
 208 /*
 209  * XDR encode
 210  */
 211
 212 static void
 213 encode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr)
 214 {
 215         __be32 * p;
 216
 217         RESERVE_SPACE(16);
 218         WRITE32(0);            /* tag length is always 0 */
 219         WRITE32(hdr->minorversion);
 220         WRITE32(hdr->ident);
 221         hdr->nops_p = p;
 222         WRITE32(hdr->nops);
 223 }
 224
 225 static void encode_cb_nops(struct nfs4_cb_compound_hdr *hdr)
 226 {
 227         *hdr->nops_p = htonl(hdr->nops);
 228 }
 229
 230 static void
 231 encode_cb_recall(struct xdr_stream *xdr, struct nfs4_delegation *dp,
 232                 struct nfs4_cb_compound_hdr *hdr)
 233 {
 234         __be32 *p;
 235         int len = dp->dl_fh.fh_size;
 236
 237         RESERVE_SPACE(12+sizeof(dp->dl_stateid) + len);
 238         WRITE32(OP_CB_RECALL);
 239         WRITE32(dp->dl_stateid.si_generation);
 240         WRITEMEM(&dp->dl_stateid.si_opaque, sizeof(stateid_opaque_t));
 241         WRITE32(0); /* truncate optimization not implemented */
 242         WRITE32(len);
 243         WRITEMEM(&dp->dl_fh.fh_base, len);
 244         hdr->nops++;
 245 }
 246
 247 static void
 248 encode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *args,
 249                    struct nfs4_cb_compound_hdr *hdr)
 250 {
 251         __be32 *p;
 252
 253         if (hdr->minorversion == 0)
 254                 return;
 255
 256         RESERVE_SPACE(1 + NFS4_MAX_SESSIONID_LEN + 20);
 257
 258         WRITE32(OP_CB_SEQUENCE);
 259         WRITEMEM(args->cbs_clp->cl_sessionid.data, NFS4_MAX_SESSIONID_LEN);
 260         WRITE32(args->cbs_clp->cl_cb_seq_nr);
 261         WRITE32(0);             /* slotid, always 0 */
 262         WRITE32(0);             /* highest slotid always 0 */
 263         WRITE32(0);             /* cachethis always 0 */
 264         WRITE32(0); /* FIXME: support referring_call_lists */
 265         hdr->nops++;
 266 }
 267
 268 static int
 269 nfs4_xdr_enc_cb_null(struct rpc_rqst *req, __be32 *p)
 270 {
 271         struct xdr_stream xdrs, *xdr = &xdrs;
 272
 273         xdr_init_encode(&xdrs, &req->rq_snd_buf, p);
 274         RESERVE_SPACE(0);
 275         return 0;
 276 }
 277
 278 static int
 279 nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
 280                 struct nfs4_rpc_args *rpc_args)
 281 {
 282         struct xdr_stream xdr;
 283         struct nfs4_delegation *args = rpc_args->args_op;
 284         struct nfs4_cb_compound_hdr hdr = {
 285                 .ident = args->dl_ident,
 286                 .minorversion = rpc_args->args_seq.cbs_minorversion,
 287         };
 288
 289         xdr_init_encode(&xdr, &req->rq_snd_buf, p);
 290         encode_cb_compound_hdr(&xdr, &hdr);
 291         encode_cb_sequence(&xdr, &rpc_args->args_seq, &hdr);
 292         encode_cb_recall(&xdr, args, &hdr);
 293         encode_cb_nops(&hdr);
 294         return 0;
 295 }
 296
 297
 298 static int
 299 decode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr){
 300         __be32 *p;
 301
 302         READ_BUF(8);
 303         READ32(hdr->status);
 304         READ32(hdr->taglen);
 305         READ_BUF(hdr->taglen + 4);
 306         hdr->tag = (char *)p;
 307         p += XDR_QUADLEN(hdr->taglen);
 308         READ32(hdr->nops);
 309         return 0;
 310 }
 311
 312 static int
 313 decode_cb_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
 314 {
 315         __be32 *p;
 316         u32 op;
 317         int32_t nfserr;
 318
 319         READ_BUF(8);
 320         READ32(op);
 321         if (op != expected) {
 322                 dprintk("NFSD: decode_cb_op_hdr: Callback server returned "
 323                          " operation %d but we issued a request for %d\n",
 324                          op, expected);
 325                 return -EIO;
 326         }
 327         READ32(nfserr);
 328         if (nfserr != NFS_OK)
 329                 return -nfs_cb_stat_to_errno(nfserr);
 330         return 0;
 331 }
 332
 333 /*
 334  * Our current back channel implmentation supports a single backchannel
 335  * with a single slot.
 336  */
 337 static int
 338 decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *res,
 339                    struct rpc_rqst *rqstp)
 340 {
 341         struct nfs4_sessionid id;
 342         int status;
 343         u32 dummy;
 344         __be32 *p;
 345
 346         if (res->cbs_minorversion == 0)
 347                 return 0;
 348
 349         status = decode_cb_op_hdr(xdr, OP_CB_SEQUENCE);
 350         if (status)
 351                 return status;
 352
 353         /*
 354          * If the server returns different values for sessionID, slotID or
 355          * sequence number, the server is looney tunes.
 356          */
 357         status = -ESERVERFAULT;
 358
 359         READ_BUF(NFS4_MAX_SESSIONID_LEN + 16);
 360         memcpy(id.data, p, NFS4_MAX_SESSIONID_LEN);
 361         p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN);
 362         if (memcmp(id.data, res->cbs_clp->cl_sessionid.data,
 363                    NFS4_MAX_SESSIONID_LEN)) {
 364                 dprintk("%s Invalid session id\n", __func__);
 365                 goto out;
 366         }
 367         READ32(dummy);
 368         if (dummy != res->cbs_clp->cl_cb_seq_nr) {
 369                 dprintk("%s Invalid sequence number\n", __func__);
 370                 goto out;
 371         }
 372         READ32(dummy);  /* slotid must be 0 */
 373         if (dummy != 0) {
 374                 dprintk("%s Invalid slotid\n", __func__);
 375                 goto out;
 376         }
 377         /* FIXME: process highest slotid and target highest slotid */
 378         status = 0;
 379 out:
 380         return status;
 381 }
 382
 383
 384 static int
 385 nfs4_xdr_dec_cb_null(struct rpc_rqst *req, __be32 *p)
 386 {
 387         return 0;
 388 }
 389
 390 static int
 391 nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p,
 392                 struct nfsd4_cb_sequence *seq)
 393 {
 394         struct xdr_stream xdr;
 395         struct nfs4_cb_compound_hdr hdr;
 396         int status;
 397
 398         xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
 399         status = decode_cb_compound_hdr(&xdr, &hdr);
 400         if (status)
 401                 goto out;
 402         if (seq) {
 403                 status = decode_cb_sequence(&xdr, seq, rqstp);
 404                 if (status)
 405                         goto out;
 406         }
 407         status = decode_cb_op_hdr(&xdr, OP_CB_RECALL);
 408 out:
 409         return status;
 410 }
 411
 412 /*
 413  * RPC procedure tables
 414  */
 415 #define PROC(proc, call, argtype, restype)                              \
 416 [NFSPROC4_CLNT_##proc] = {                                              \
 417         .p_proc   = NFSPROC4_CB_##call,                                 \
 418         .p_encode = (kxdrproc_t) nfs4_xdr_##argtype,                    \
 419         .p_decode = (kxdrproc_t) nfs4_xdr_##restype,                    \
 420         .p_arglen = NFS4_##argtype##_sz,                                \
 421         .p_replen = NFS4_##restype##_sz,                                \
 422         .p_statidx = NFSPROC4_CB_##call,                                \
 423         .p_name   = #proc,                                              \
 424 }
 425
 426 static struct rpc_procinfo     nfs4_cb_procedures[] = {
 427     PROC(CB_NULL,      NULL,     enc_cb_null,     dec_cb_null),
 428     PROC(CB_RECALL,    COMPOUND,   enc_cb_recall,      dec_cb_recall),
 429 };
 430
 431 static struct rpc_version       nfs_cb_version4 = {
 432         .number                 = 1,
 433         .nrprocs                = ARRAY_SIZE(nfs4_cb_procedures),
 434         .procs                  = nfs4_cb_procedures
 435 };
 436
 437 static struct rpc_version *     nfs_cb_version[] = {
 438         NULL,
 439         &nfs_cb_version4,
 440 };
 441
 442 static struct rpc_program cb_program;
 443
 444 static struct rpc_stat cb_stats = {
 445                 .program        = &cb_program
 446 };
 447
 448 #define NFS4_CALLBACK 0x40000000
 449 static struct rpc_program cb_program = {
 450                 .name           = "nfs4_cb",
 451                 .number         = NFS4_CALLBACK,
 452                 .nrvers         = ARRAY_SIZE(nfs_cb_version),
 453                 .version        = nfs_cb_version,
 454                 .stats          = &cb_stats,
 455                 .pipe_dir_name  = "/nfsd4_cb",
 456 };
 457
 458 static int max_cb_time(void)
 459 {
 460         return max(NFSD_LEASE_TIME/10, (time_t)1) * HZ;
 461 }
 462
 463 /* Reference counting, callback cleanup, etc., all look racy as heck.
 464  * And why is cb_set an atomic? */
 465
 466 int setup_callback_client(struct nfs4_client *clp)
 467 {
 468         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 469         struct rpc_timeout      timeparms = {
 470                 .to_initval     = max_cb_time(),
 471                 .to_retries     = 0,
 472         };
 473         struct rpc_create_args args = {
 474                 .protocol       = XPRT_TRANSPORT_TCP,
 475                 .address        = (struct sockaddr *) &cb->cb_addr,
 476                 .addrsize       = cb->cb_addrlen,
 477                 .timeout        = &timeparms,
 478                 .program        = &cb_program,
 479                 .prognumber     = cb->cb_prog,
 480                 .version        = nfs_cb_version[1]->number,
 481                 .authflavor     = clp->cl_flavor,
 482                 .flags          = (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
 483                 .client_name    = clp->cl_principal,
 484         };
 485         struct rpc_clnt *client;
 486
 487         if (!clp->cl_principal && (clp->cl_flavor >= RPC_AUTH_GSS_KRB5))
 488                 return -EINVAL;
 489         if (cb->cb_minorversion) {
 490                 args.bc_xprt = clp->cl_cb_xprt;
 491                 args.protocol = XPRT_TRANSPORT_BC_TCP;
 492         }
 493         /* Create RPC client */
 494         client = rpc_create(&args);
 495         if (IS_ERR(client)) {
 496                 dprintk("NFSD: couldn't create callback client: %ld\n",
 497                         PTR_ERR(client));
 498                 return PTR_ERR(client);
 499         }
 500         cb->cb_client = client;
 501         return 0;
 502
 503 }
 504
 505 static void warn_no_callback_path(struct nfs4_client *clp, int reason)
 506 {
 507         dprintk("NFSD: warning: no callback path to client %.*s: error %d\n",
 508                 (int)clp->cl_name.len, clp->cl_name.data, reason);
 509 }
 510
 511 static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 512 {
 513         struct nfs4_client *clp = calldata;
 514
 515         if (task->tk_status)
 516                 warn_no_callback_path(clp, task->tk_status);
 517         else
 518                 atomic_set(&clp->cl_cb_conn.cb_set, 1);
 519         put_nfs4_client(clp);
 520 }
 521
 522 static const struct rpc_call_ops nfsd4_cb_probe_ops = {
 523         .rpc_call_done = nfsd4_cb_probe_done,
 524 };
 525
 526 static struct rpc_cred *callback_cred;
 527
 528 int set_callback_cred(void)
 529 {
 530         callback_cred = rpc_lookup_machine_cred();
 531         if (!callback_cred)
 532                 return -ENOMEM;
 533         return 0;
 534 }
 535
 536
 537 void do_probe_callback(struct nfs4_client *clp)
 538 {
 539         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 540         struct rpc_message msg = {
 541                 .rpc_proc       = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL],
 542                 .rpc_argp       = clp,
 543                 .rpc_cred       = callback_cred
 544         };
 545         int status;
 546
 547         status = rpc_call_async(cb->cb_client, &msg, RPC_TASK_SOFT,
 548                                 &nfsd4_cb_probe_ops, (void *)clp);
 549         if (status) {
 550                 warn_no_callback_path(clp, status);
 551                 put_nfs4_client(clp);
 552         }
 553 }
 554
 555 /*
 556  * Set up the callback client and put a NFSPROC4_CB_NULL on the wire...
 557  */
 558 void
 559 nfsd4_probe_callback(struct nfs4_client *clp)
 560 {
 561         int status;
 562
 563         BUG_ON(atomic_read(&clp->cl_cb_conn.cb_set));
 564
 565         status = setup_callback_client(clp);
 566         if (status) {
 567                 warn_no_callback_path(clp, status);
 568                 return;
 569         }
 570
 571         /* the task holds a reference to the nfs4_client struct */
 572         atomic_inc(&clp->cl_count);
 573
 574         do_probe_callback(clp);
 575 }
 576
 577 /*
 578  * There's currently a single callback channel slot.
 579  * If the slot is available, then mark it busy.  Otherwise, set the
 580  * thread for sleeping on the callback RPC wait queue.
 581  */
 582 static int nfsd41_cb_setup_sequence(struct nfs4_client *clp,
 583                 struct rpc_task *task)
 584 {
 585         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
 586         u32 *ptr = (u32 *)clp->cl_sessionid.data;
 587         int status = 0;
 588
 589         dprintk("%s: %u:%u:%u:%u\n", __func__,
 590                 ptr[0], ptr[1], ptr[2], ptr[3]);
 591
 592         if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
 593                 rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
 594                 dprintk("%s slot is busy\n", __func__);
 595                 status = -EAGAIN;
 596                 goto out;
 597         }
 598
 599         /*
 600          * We'll need the clp during XDR encoding and decoding,
 601          * and the sequence during decoding to verify the reply
 602          */
 603         args->args_seq.cbs_clp = clp;
 604         task->tk_msg.rpc_resp = &args->args_seq;
 605
 606 out:
 607         dprintk("%s status=%d\n", __func__, status);
 608         return status;
 609 }
 610
 611 /*
 612  * TODO: cb_sequence should support referring call lists, cachethis, multiple
 613  * slots, and mark callback channel down on communication errors.
 614  */
 615 static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
 616 {
 617         struct nfs4_delegation *dp = calldata;
 618         struct nfs4_client *clp = dp->dl_client;
 619         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
 620         u32 minorversion = clp->cl_cb_conn.cb_minorversion;
 621         int status = 0;
 622
 623         args->args_seq.cbs_minorversion = minorversion;
 624         if (minorversion) {
 625                 status = nfsd41_cb_setup_sequence(clp, task);
 626                 if (status) {
 627                         if (status != -EAGAIN) {
 628                                 /* terminate rpc task */
 629                                 task->tk_status = status;
 630                                 task->tk_action = NULL;
 631                         }
 632                         return;
 633                 }
 634         }
 635         rpc_call_start(task);
 636 }
 637
 638 static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
 639 {
 640         struct nfs4_delegation *dp = calldata;
 641         struct nfs4_client *clp = dp->dl_client;
 642
 643         dprintk("%s: minorversion=%d\n", __func__,
 644                 clp->cl_cb_conn.cb_minorversion);
 645
 646         if (clp->cl_cb_conn.cb_minorversion) {
 647                 /* No need for lock, access serialized in nfsd4_cb_prepare */
 648                 ++clp->cl_cb_seq_nr;
 649                 clear_bit(0, &clp->cl_cb_slot_busy);
 650                 rpc_wake_up_next(&clp->cl_cb_waitq);
 651                 dprintk("%s: freed slot, new seqid=%d\n", __func__,
 652                         clp->cl_cb_seq_nr);
 653
 654                 /* We're done looking into the sequence information */
 655                 task->tk_msg.rpc_resp = NULL;
 656         }
 657 }
 658
 659 static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
 660 {
 661         struct nfs4_delegation *dp = calldata;
 662         struct nfs4_client *clp = dp->dl_client;
 663
 664         nfsd4_cb_done(task, calldata);
 665
 666         switch (task->tk_status) {
 667         case -EIO:
 668                 /* Network partition? */
 669                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
 670                 warn_no_callback_path(clp, task->tk_status);
 671         case -EBADHANDLE:
 672         case -NFS4ERR_BAD_STATEID:
 673                 /* Race: client probably got cb_recall
 674                  * before open reply granting delegation */
 675                 break;
 676         default:
 677                 /* success, or error we can't handle */
 678                 goto done;
 679         }
 680         if (dp->dl_retries--) {
 681                 rpc_delay(task, 2*HZ);
 682                 task->tk_status = 0;
 683                 rpc_restart_call(task);
 684                 return;
 685         } else {
 686                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
 687                 warn_no_callback_path(clp, task->tk_status);
 688         }
 689 done:
 690         kfree(task->tk_msg.rpc_argp);
 691 }
 692
 693 static void nfsd4_cb_recall_release(void *calldata)
 694 {
 695         struct nfs4_delegation *dp = calldata;
 696         struct nfs4_client *clp = dp->dl_client;
 697
 698         nfs4_put_delegation(dp);
 699         put_nfs4_client(clp);
 700 }
 701
 702 static const struct rpc_call_ops nfsd4_cb_recall_ops = {
 703         .rpc_call_prepare = nfsd4_cb_prepare,
 704         .rpc_call_done = nfsd4_cb_recall_done,
 705         .rpc_release = nfsd4_cb_recall_release,
 706 };
 707
 708 /*
 709  * called with dp->dl_count inc'ed.
 710  */
 711 void
 712 nfsd4_cb_recall(struct nfs4_delegation *dp)
 713 {
 714         struct nfs4_client *clp = dp->dl_client;
 715         struct rpc_clnt *clnt = clp->cl_cb_conn.cb_client;
 716         struct nfs4_rpc_args *args;
 717         struct rpc_message msg = {
 718                 .rpc_proc = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_RECALL],
 719                 .rpc_cred = callback_cred
 720         };
 721         int status = -ENOMEM;
 722
 723         args = kzalloc(sizeof(*args), GFP_KERNEL);
 724         if (!args)
 725                 goto out;
 726         args->args_op = dp;
 727         msg.rpc_argp = args;
 728         dp->dl_retries = 1;
 729         status = rpc_call_async(clnt, &msg, RPC_TASK_SOFT,
 730                                 &nfsd4_cb_recall_ops, dp);
 731 out:
 732         if (status) {
 733                 kfree(args);
 734                 put_nfs4_client(clp);
 735                 nfs4_put_delegation(dp);
 736         }
 737 }