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   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/slab.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 struct nfs4_rpc_args {
  83         void                            *args_op;
  84         struct nfsd4_cb_sequence        args_seq;
  85 };
  86
  87 /*
  88 * Generic encode routines from fs/nfs/nfs4xdr.c
  89 */
  90 static inline __be32 *
  91 xdr_writemem(__be32 *p, const void *ptr, int nbytes)
  92 {
  93         int tmp = XDR_QUADLEN(nbytes);
  94         if (!tmp)
  95                 return p;
  96         p[tmp-1] = 0;
  97         memcpy(p, ptr, nbytes);
  98         return p + tmp;
  99 }
 100
 101 #define WRITE32(n)               *p++ = htonl(n)
 102 #define WRITEMEM(ptr,nbytes)     do {                           \
 103         p = xdr_writemem(p, ptr, nbytes);                       \
 104 } while (0)
 105 #define RESERVE_SPACE(nbytes)   do {                            \
 106         p = xdr_reserve_space(xdr, nbytes);                     \
 107         if (!p) dprintk("NFSD: RESERVE_SPACE(%d) failed in function %s\n", (int) (nbytes), __func__); \
 108         BUG_ON(!p);                                             \
 109 } while (0)
 110
 111 /*
 112  * Generic decode routines from fs/nfs/nfs4xdr.c
 113  */
 114 #define DECODE_TAIL                             \
 115         status = 0;                             \
 116 out:                                            \
 117         return status;                          \
 118 xdr_error:                                      \
 119         dprintk("NFSD: xdr error! (%s:%d)\n", __FILE__, __LINE__); \
 120         status = -EIO;                          \
 121         goto out
 122
 123 #define READ32(x)         (x) = ntohl(*p++)
 124 #define READ64(x)         do {                  \
 125         (x) = (u64)ntohl(*p++) << 32;           \
 126         (x) |= ntohl(*p++);                     \
 127 } while (0)
 128 #define READTIME(x)       do {                  \
 129         p++;                                    \
 130         (x.tv_sec) = ntohl(*p++);               \
 131         (x.tv_nsec) = ntohl(*p++);              \
 132 } while (0)
 133 #define READ_BUF(nbytes)  do { \
 134         p = xdr_inline_decode(xdr, nbytes); \
 135         if (!p) { \
 136                 dprintk("NFSD: %s: reply buffer overflowed in line %d.\n", \
 137                         __func__, __LINE__); \
 138                 return -EIO; \
 139         } \
 140 } while (0)
 141
 142 struct nfs4_cb_compound_hdr {
 143         /* args */
 144         u32             ident;  /* minorversion 0 only */
 145         u32             nops;
 146         __be32          *nops_p;
 147         u32             minorversion;
 148         /* res */
 149         int             status;
 150         u32             taglen;
 151         char            *tag;
 152 };
 153
 154 static struct {
 155 int stat;
 156 int errno;
 157 } nfs_cb_errtbl[] = {
 158         { NFS4_OK,              0               },
 159         { NFS4ERR_PERM,         EPERM           },
 160         { NFS4ERR_NOENT,        ENOENT          },
 161         { NFS4ERR_IO,           EIO             },
 162         { NFS4ERR_NXIO,         ENXIO           },
 163         { NFS4ERR_ACCESS,       EACCES          },
 164         { NFS4ERR_EXIST,        EEXIST          },
 165         { NFS4ERR_XDEV,         EXDEV           },
 166         { NFS4ERR_NOTDIR,       ENOTDIR         },
 167         { NFS4ERR_ISDIR,        EISDIR          },
 168         { NFS4ERR_INVAL,        EINVAL          },
 169         { NFS4ERR_FBIG,         EFBIG           },
 170         { NFS4ERR_NOSPC,        ENOSPC          },
 171         { NFS4ERR_ROFS,         EROFS           },
 172         { NFS4ERR_MLINK,        EMLINK          },
 173         { NFS4ERR_NAMETOOLONG,  ENAMETOOLONG    },
 174         { NFS4ERR_NOTEMPTY,     ENOTEMPTY       },
 175         { NFS4ERR_DQUOT,        EDQUOT          },
 176         { NFS4ERR_STALE,        ESTALE          },
 177         { NFS4ERR_BADHANDLE,    EBADHANDLE      },
 178         { NFS4ERR_BAD_COOKIE,   EBADCOOKIE      },
 179         { NFS4ERR_NOTSUPP,      ENOTSUPP        },
 180         { NFS4ERR_TOOSMALL,     ETOOSMALL       },
 181         { NFS4ERR_SERVERFAULT,  ESERVERFAULT    },
 182         { NFS4ERR_BADTYPE,      EBADTYPE        },
 183         { NFS4ERR_LOCKED,       EAGAIN          },
 184         { NFS4ERR_RESOURCE,     EREMOTEIO       },
 185         { NFS4ERR_SYMLINK,      ELOOP           },
 186         { NFS4ERR_OP_ILLEGAL,   EOPNOTSUPP      },
 187         { NFS4ERR_DEADLOCK,     EDEADLK         },
 188         { -1,                   EIO             }
 189 };
 190
 191 static int
 192 nfs_cb_stat_to_errno(int stat)
 193 {
 194         int i;
 195         for (i = 0; nfs_cb_errtbl[i].stat != -1; i++) {
 196                 if (nfs_cb_errtbl[i].stat == stat)
 197                         return nfs_cb_errtbl[i].errno;
 198         }
 199         /* If we cannot translate the error, the recovery routines should
 200         * handle it.
 201         * Note: remaining NFSv4 error codes have values > 10000, so should
 202         * not conflict with native Linux error codes.
 203         */
 204         return stat;
 205 }
 206
 207 /*
 208  * XDR encode
 209  */
 210
 211 static void
 212 encode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr)
 213 {
 214         __be32 * p;
 215
 216         RESERVE_SPACE(16);
 217         WRITE32(0);            /* tag length is always 0 */
 218         WRITE32(hdr->minorversion);
 219         WRITE32(hdr->ident);
 220         hdr->nops_p = p;
 221         WRITE32(hdr->nops);
 222 }
 223
 224 static void encode_cb_nops(struct nfs4_cb_compound_hdr *hdr)
 225 {
 226         *hdr->nops_p = htonl(hdr->nops);
 227 }
 228
 229 static void
 230 encode_cb_recall(struct xdr_stream *xdr, struct nfs4_delegation *dp,
 231                 struct nfs4_cb_compound_hdr *hdr)
 232 {
 233         __be32 *p;
 234         int len = dp->dl_fh.fh_size;
 235
 236         RESERVE_SPACE(12+sizeof(dp->dl_stateid) + len);
 237         WRITE32(OP_CB_RECALL);
 238         WRITE32(dp->dl_stateid.si_generation);
 239         WRITEMEM(&dp->dl_stateid.si_opaque, sizeof(stateid_opaque_t));
 240         WRITE32(0); /* truncate optimization not implemented */
 241         WRITE32(len);
 242         WRITEMEM(&dp->dl_fh.fh_base, len);
 243         hdr->nops++;
 244 }
 245
 246 static void
 247 encode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *args,
 248                    struct nfs4_cb_compound_hdr *hdr)
 249 {
 250         __be32 *p;
 251
 252         if (hdr->minorversion == 0)
 253                 return;
 254
 255         RESERVE_SPACE(1 + NFS4_MAX_SESSIONID_LEN + 20);
 256
 257         WRITE32(OP_CB_SEQUENCE);
 258         WRITEMEM(args->cbs_clp->cl_sessionid.data, NFS4_MAX_SESSIONID_LEN);
 259         WRITE32(args->cbs_clp->cl_cb_seq_nr);
 260         WRITE32(0);             /* slotid, always 0 */
 261         WRITE32(0);             /* highest slotid always 0 */
 262         WRITE32(0);             /* cachethis always 0 */
 263         WRITE32(0); /* FIXME: support referring_call_lists */
 264         hdr->nops++;
 265 }
 266
 267 static int
 268 nfs4_xdr_enc_cb_null(struct rpc_rqst *req, __be32 *p)
 269 {
 270         struct xdr_stream xdrs, *xdr = &xdrs;
 271
 272         xdr_init_encode(&xdrs, &req->rq_snd_buf, p);
 273         RESERVE_SPACE(0);
 274         return 0;
 275 }
 276
 277 static int
 278 nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
 279                 struct nfs4_rpc_args *rpc_args)
 280 {
 281         struct xdr_stream xdr;
 282         struct nfs4_delegation *args = rpc_args->args_op;
 283         struct nfs4_cb_compound_hdr hdr = {
 284                 .ident = args->dl_ident,
 285                 .minorversion = rpc_args->args_seq.cbs_minorversion,
 286         };
 287
 288         xdr_init_encode(&xdr, &req->rq_snd_buf, p);
 289         encode_cb_compound_hdr(&xdr, &hdr);
 290         encode_cb_sequence(&xdr, &rpc_args->args_seq, &hdr);
 291         encode_cb_recall(&xdr, args, &hdr);
 292         encode_cb_nops(&hdr);
 293         return 0;
 294 }
 295
 296
 297 static int
 298 decode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr){
 299         __be32 *p;
 300
 301         READ_BUF(8);
 302         READ32(hdr->status);
 303         READ32(hdr->taglen);
 304         READ_BUF(hdr->taglen + 4);
 305         hdr->tag = (char *)p;
 306         p += XDR_QUADLEN(hdr->taglen);
 307         READ32(hdr->nops);
 308         return 0;
 309 }
 310
 311 static int
 312 decode_cb_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
 313 {
 314         __be32 *p;
 315         u32 op;
 316         int32_t nfserr;
 317
 318         READ_BUF(8);
 319         READ32(op);
 320         if (op != expected) {
 321                 dprintk("NFSD: decode_cb_op_hdr: Callback server returned "
 322                          " operation %d but we issued a request for %d\n",
 323                          op, expected);
 324                 return -EIO;
 325         }
 326         READ32(nfserr);
 327         if (nfserr != NFS_OK)
 328                 return -nfs_cb_stat_to_errno(nfserr);
 329         return 0;
 330 }
 331
 332 /*
 333  * Our current back channel implmentation supports a single backchannel
 334  * with a single slot.
 335  */
 336 static int
 337 decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *res,
 338                    struct rpc_rqst *rqstp)
 339 {
 340         struct nfs4_sessionid id;
 341         int status;
 342         u32 dummy;
 343         __be32 *p;
 344
 345         if (res->cbs_minorversion == 0)
 346                 return 0;
 347
 348         status = decode_cb_op_hdr(xdr, OP_CB_SEQUENCE);
 349         if (status)
 350                 return status;
 351
 352         /*
 353          * If the server returns different values for sessionID, slotID or
 354          * sequence number, the server is looney tunes.
 355          */
 356         status = -ESERVERFAULT;
 357
 358         READ_BUF(NFS4_MAX_SESSIONID_LEN + 16);
 359         memcpy(id.data, p, NFS4_MAX_SESSIONID_LEN);
 360         p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN);
 361         if (memcmp(id.data, res->cbs_clp->cl_sessionid.data,
 362                    NFS4_MAX_SESSIONID_LEN)) {
 363                 dprintk("%s Invalid session id\n", __func__);
 364                 goto out;
 365         }
 366         READ32(dummy);
 367         if (dummy != res->cbs_clp->cl_cb_seq_nr) {
 368                 dprintk("%s Invalid sequence number\n", __func__);
 369                 goto out;
 370         }
 371         READ32(dummy);  /* slotid must be 0 */
 372         if (dummy != 0) {
 373                 dprintk("%s Invalid slotid\n", __func__);
 374                 goto out;
 375         }
 376         /* FIXME: process highest slotid and target highest slotid */
 377         status = 0;
 378 out:
 379         return status;
 380 }
 381
 382
 383 static int
 384 nfs4_xdr_dec_cb_null(struct rpc_rqst *req, __be32 *p)
 385 {
 386         return 0;
 387 }
 388
 389 static int
 390 nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p,
 391                 struct nfsd4_cb_sequence *seq)
 392 {
 393         struct xdr_stream xdr;
 394         struct nfs4_cb_compound_hdr hdr;
 395         int status;
 396
 397         xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
 398         status = decode_cb_compound_hdr(&xdr, &hdr);
 399         if (status)
 400                 goto out;
 401         if (seq) {
 402                 status = decode_cb_sequence(&xdr, seq, rqstp);
 403                 if (status)
 404                         goto out;
 405         }
 406         status = decode_cb_op_hdr(&xdr, OP_CB_RECALL);
 407 out:
 408         return status;
 409 }
 410
 411 /*
 412  * RPC procedure tables
 413  */
 414 #define PROC(proc, call, argtype, restype)                              \
 415 [NFSPROC4_CLNT_##proc] = {                                              \
 416         .p_proc   = NFSPROC4_CB_##call,                                 \
 417         .p_encode = (kxdrproc_t) nfs4_xdr_##argtype,                    \
 418         .p_decode = (kxdrproc_t) nfs4_xdr_##restype,                    \
 419         .p_arglen = NFS4_##argtype##_sz,                                \
 420         .p_replen = NFS4_##restype##_sz,                                \
 421         .p_statidx = NFSPROC4_CB_##call,                                \
 422         .p_name   = #proc,                                              \
 423 }
 424
 425 static struct rpc_procinfo     nfs4_cb_procedures[] = {
 426     PROC(CB_NULL,      NULL,     enc_cb_null,     dec_cb_null),
 427     PROC(CB_RECALL,    COMPOUND,   enc_cb_recall,      dec_cb_recall),
 428 };
 429
 430 static struct rpc_version       nfs_cb_version4 = {
 431         .number                 = 1,
 432         .nrprocs                = ARRAY_SIZE(nfs4_cb_procedures),
 433         .procs                  = nfs4_cb_procedures
 434 };
 435
 436 static struct rpc_version *     nfs_cb_version[] = {
 437         NULL,
 438         &nfs_cb_version4,
 439 };
 440
 441 static struct rpc_program cb_program;
 442
 443 static struct rpc_stat cb_stats = {
 444                 .program        = &cb_program
 445 };
 446
 447 #define NFS4_CALLBACK 0x40000000
 448 static struct rpc_program cb_program = {
 449                 .name           = "nfs4_cb",
 450                 .number         = NFS4_CALLBACK,
 451                 .nrvers         = ARRAY_SIZE(nfs_cb_version),
 452                 .version        = nfs_cb_version,
 453                 .stats          = &cb_stats,
 454                 .pipe_dir_name  = "/nfsd4_cb",
 455 };
 456
 457 static int max_cb_time(void)
 458 {
 459         return max(NFSD_LEASE_TIME/10, (time_t)1) * HZ;
 460 }
 461
 462 /* Reference counting, callback cleanup, etc., all look racy as heck.
 463  * And why is cb_set an atomic? */
 464
 465 int setup_callback_client(struct nfs4_client *clp)
 466 {
 467         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 468         struct rpc_timeout      timeparms = {
 469                 .to_initval     = max_cb_time(),
 470                 .to_retries     = 0,
 471         };
 472         struct rpc_create_args args = {
 473                 .protocol       = XPRT_TRANSPORT_TCP,
 474                 .address        = (struct sockaddr *) &cb->cb_addr,
 475                 .addrsize       = cb->cb_addrlen,
 476                 .timeout        = &timeparms,
 477                 .program        = &cb_program,
 478                 .prognumber     = cb->cb_prog,
 479                 .version        = nfs_cb_version[1]->number,
 480                 .authflavor     = clp->cl_flavor,
 481                 .flags          = (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
 482                 .client_name    = clp->cl_principal,
 483         };
 484         struct rpc_clnt *client;
 485
 486         if (!clp->cl_principal && (clp->cl_flavor >= RPC_AUTH_GSS_KRB5))
 487                 return -EINVAL;
 488         if (cb->cb_minorversion) {
 489                 args.bc_xprt = clp->cl_cb_xprt;
 490                 args.protocol = XPRT_TRANSPORT_BC_TCP;
 491         }
 492         /* Create RPC client */
 493         client = rpc_create(&args);
 494         if (IS_ERR(client)) {
 495                 dprintk("NFSD: couldn't create callback client: %ld\n",
 496                         PTR_ERR(client));
 497                 return PTR_ERR(client);
 498         }
 499         cb->cb_client = client;
 500         return 0;
 501
 502 }
 503
 504 static void warn_no_callback_path(struct nfs4_client *clp, int reason)
 505 {
 506         dprintk("NFSD: warning: no callback path to client %.*s: error %d\n",
 507                 (int)clp->cl_name.len, clp->cl_name.data, reason);
 508 }
 509
 510 static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 511 {
 512         struct nfs4_client *clp = calldata;
 513
 514         if (task->tk_status)
 515                 warn_no_callback_path(clp, task->tk_status);
 516         else
 517                 atomic_set(&clp->cl_cb_conn.cb_set, 1);
 518         put_nfs4_client(clp);
 519 }
 520
 521 static const struct rpc_call_ops nfsd4_cb_probe_ops = {
 522         .rpc_call_done = nfsd4_cb_probe_done,
 523 };
 524
 525 static struct rpc_cred *callback_cred;
 526
 527 int set_callback_cred(void)
 528 {
 529         if (callback_cred)
 530                 return 0;
 531         callback_cred = rpc_lookup_machine_cred();
 532         if (!callback_cred)
 533                 return -ENOMEM;
 534         return 0;
 535 }
 536
 537
 538 void do_probe_callback(struct nfs4_client *clp)
 539 {
 540         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 541         struct rpc_message msg = {
 542                 .rpc_proc       = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL],
 543                 .rpc_argp       = clp,
 544                 .rpc_cred       = callback_cred
 545         };
 546         int status;
 547
 548         status = rpc_call_async(cb->cb_client, &msg,
 549                                 RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
 550                                 &nfsd4_cb_probe_ops, (void *)clp);
 551         if (status) {
 552                 warn_no_callback_path(clp, status);
 553                 put_nfs4_client(clp);
 554         }
 555 }
 556
 557 /*
 558  * Set up the callback client and put a NFSPROC4_CB_NULL on the wire...
 559  */
 560 void
 561 nfsd4_probe_callback(struct nfs4_client *clp)
 562 {
 563         int status;
 564
 565         BUG_ON(atomic_read(&clp->cl_cb_conn.cb_set));
 566
 567         status = setup_callback_client(clp);
 568         if (status) {
 569                 warn_no_callback_path(clp, status);
 570                 return;
 571         }
 572
 573         /* the task holds a reference to the nfs4_client struct */
 574         atomic_inc(&clp->cl_count);
 575
 576         do_probe_callback(clp);
 577 }
 578
 579 /*
 580  * There's currently a single callback channel slot.
 581  * If the slot is available, then mark it busy.  Otherwise, set the
 582  * thread for sleeping on the callback RPC wait queue.
 583  */
 584 static int nfsd41_cb_setup_sequence(struct nfs4_client *clp,
 585                 struct rpc_task *task)
 586 {
 587         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
 588         u32 *ptr = (u32 *)clp->cl_sessionid.data;
 589         int status = 0;
 590
 591         dprintk("%s: %u:%u:%u:%u\n", __func__,
 592                 ptr[0], ptr[1], ptr[2], ptr[3]);
 593
 594         if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
 595                 rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
 596                 dprintk("%s slot is busy\n", __func__);
 597                 status = -EAGAIN;
 598                 goto out;
 599         }
 600
 601         /*
 602          * We'll need the clp during XDR encoding and decoding,
 603          * and the sequence during decoding to verify the reply
 604          */
 605         args->args_seq.cbs_clp = clp;
 606         task->tk_msg.rpc_resp = &args->args_seq;
 607
 608 out:
 609         dprintk("%s status=%d\n", __func__, status);
 610         return status;
 611 }
 612
 613 /*
 614  * TODO: cb_sequence should support referring call lists, cachethis, multiple
 615  * slots, and mark callback channel down on communication errors.
 616  */
 617 static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
 618 {
 619         struct nfs4_delegation *dp = calldata;
 620         struct nfs4_client *clp = dp->dl_client;
 621         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
 622         u32 minorversion = clp->cl_cb_conn.cb_minorversion;
 623         int status = 0;
 624
 625         args->args_seq.cbs_minorversion = minorversion;
 626         if (minorversion) {
 627                 status = nfsd41_cb_setup_sequence(clp, task);
 628                 if (status) {
 629                         if (status != -EAGAIN) {
 630                                 /* terminate rpc task */
 631                                 task->tk_status = status;
 632                                 task->tk_action = NULL;
 633                         }
 634                         return;
 635                 }
 636         }
 637         rpc_call_start(task);
 638 }
 639
 640 static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
 641 {
 642         struct nfs4_delegation *dp = calldata;
 643         struct nfs4_client *clp = dp->dl_client;
 644
 645         dprintk("%s: minorversion=%d\n", __func__,
 646                 clp->cl_cb_conn.cb_minorversion);
 647
 648         if (clp->cl_cb_conn.cb_minorversion) {
 649                 /* No need for lock, access serialized in nfsd4_cb_prepare */
 650                 ++clp->cl_cb_seq_nr;
 651                 clear_bit(0, &clp->cl_cb_slot_busy);
 652                 rpc_wake_up_next(&clp->cl_cb_waitq);
 653                 dprintk("%s: freed slot, new seqid=%d\n", __func__,
 654                         clp->cl_cb_seq_nr);
 655
 656                 /* We're done looking into the sequence information */
 657                 task->tk_msg.rpc_resp = NULL;
 658         }
 659 }
 660
 661 static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
 662 {
 663         struct nfs4_delegation *dp = calldata;
 664         struct nfs4_client *clp = dp->dl_client;
 665
 666         nfsd4_cb_done(task, calldata);
 667
 668         switch (task->tk_status) {
 669         case -EIO:
 670                 /* Network partition? */
 671                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
 672                 warn_no_callback_path(clp, task->tk_status);
 673         case -EBADHANDLE:
 674         case -NFS4ERR_BAD_STATEID:
 675                 /* Race: client probably got cb_recall
 676                  * before open reply granting delegation */
 677                 break;
 678         default:
 679                 /* success, or error we can't handle */
 680                 goto done;
 681         }
 682         if (dp->dl_retries--) {
 683                 rpc_delay(task, 2*HZ);
 684                 task->tk_status = 0;
 685                 rpc_restart_call(task);
 686                 return;
 687         } else {
 688                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
 689                 warn_no_callback_path(clp, task->tk_status);
 690         }
 691 done:
 692         kfree(task->tk_msg.rpc_argp);
 693 }
 694
 695 static void nfsd4_cb_recall_release(void *calldata)
 696 {
 697         struct nfs4_delegation *dp = calldata;
 698         struct nfs4_client *clp = dp->dl_client;
 699
 700         nfs4_put_delegation(dp);
 701         put_nfs4_client(clp);
 702 }
 703
 704 static const struct rpc_call_ops nfsd4_cb_recall_ops = {
 705         .rpc_call_prepare = nfsd4_cb_prepare,
 706         .rpc_call_done = nfsd4_cb_recall_done,
 707         .rpc_release = nfsd4_cb_recall_release,
 708 };
 709
 710 /*
 711  * called with dp->dl_count inc'ed.
 712  */
 713 void
 714 nfsd4_cb_recall(struct nfs4_delegation *dp)
 715 {
 716         struct nfs4_client *clp = dp->dl_client;
 717         struct rpc_clnt *clnt = clp->cl_cb_conn.cb_client;
 718         struct nfs4_rpc_args *args;
 719         struct rpc_message msg = {
 720                 .rpc_proc = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_RECALL],
 721                 .rpc_cred = callback_cred
 722         };
 723         int status = -ENOMEM;
 724
 725         args = kzalloc(sizeof(*args), GFP_KERNEL);
 726         if (!args)
 727                 goto out;
 728         args->args_op = dp;
 729         msg.rpc_argp = args;
 730         dp->dl_retries = 1;
 731         status = rpc_call_async(clnt, &msg, RPC_TASK_SOFT,
 732                                 &nfsd4_cb_recall_ops, dp);
 733 out:
 734         if (status) {
 735                 kfree(args);
 736                 put_nfs4_client(clp);
 737                 nfs4_put_delegation(dp);
 738         }
 739 }