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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/module.h>
  37 #include <linux/list.h>
  38 #include <linux/inet.h>
  39 #include <linux/errno.h>
  40 #include <linux/delay.h>
  41 #include <linux/sched.h>
  42 #include <linux/kthread.h>
  43 #include <linux/sunrpc/xdr.h>
  44 #include <linux/sunrpc/svc.h>
  45 #include <linux/sunrpc/clnt.h>
  46 #include <linux/sunrpc/svcsock.h>
  47 #include <linux/nfsd/nfsd.h>
  48 #include <linux/nfsd/state.h>
  49 #include <linux/sunrpc/sched.h>
  50 #include <linux/nfs4.h>
  51 #include <linux/sunrpc/xprtsock.h>
  52
  53 #define NFSDDBG_FACILITY                NFSDDBG_PROC
  54
  55 #define NFSPROC4_CB_NULL 0
  56 #define NFSPROC4_CB_COMPOUND 1
  57 #define NFS4_STATEID_SIZE 16
  58
  59 /* Index of predefined Linux callback client operations */
  60
  61 enum {
  62         NFSPROC4_CLNT_CB_NULL = 0,
  63         NFSPROC4_CLNT_CB_RECALL,
  64         NFSPROC4_CLNT_CB_SEQUENCE,
  65 };
  66
  67 enum nfs_cb_opnum4 {
  68         OP_CB_RECALL            = 4,
  69         OP_CB_SEQUENCE          = 11,
  70 };
  71
  72 #define NFS4_MAXTAGLEN          20
  73
  74 #define NFS4_enc_cb_null_sz             0
  75 #define NFS4_dec_cb_null_sz             0
  76 #define cb_compound_enc_hdr_sz          4
  77 #define cb_compound_dec_hdr_sz          (3 + (NFS4_MAXTAGLEN >> 2))
  78 #define sessionid_sz                    (NFS4_MAX_SESSIONID_LEN >> 2)
  79 #define cb_sequence_enc_sz              (sessionid_sz + 4 +             \
  80                                         1 /* no referring calls list yet */)
  81 #define cb_sequence_dec_sz              (op_dec_sz + sessionid_sz + 4)
  82
  83 #define op_enc_sz                       1
  84 #define op_dec_sz                       2
  85 #define enc_nfs4_fh_sz                  (1 + (NFS4_FHSIZE >> 2))
  86 #define enc_stateid_sz                  (NFS4_STATEID_SIZE >> 2)
  87 #define NFS4_enc_cb_recall_sz           (cb_compound_enc_hdr_sz +       \
  88                                         cb_sequence_enc_sz +            \
  89                                         1 + enc_stateid_sz +            \
  90                                         enc_nfs4_fh_sz)
  91
  92 #define NFS4_dec_cb_recall_sz           (cb_compound_dec_hdr_sz  +      \
  93                                         cb_sequence_dec_sz +            \
  94                                         op_dec_sz)
  95
  96 struct nfs4_rpc_args {
  97         void                            *args_op;
  98         struct nfsd4_cb_sequence        args_seq;
  99 };
 100
 101 /*
 102 * Generic encode routines from fs/nfs/nfs4xdr.c
 103 */
 104 static inline __be32 *
 105 xdr_writemem(__be32 *p, const void *ptr, int nbytes)
 106 {
 107         int tmp = XDR_QUADLEN(nbytes);
 108         if (!tmp)
 109                 return p;
 110         p[tmp-1] = 0;
 111         memcpy(p, ptr, nbytes);
 112         return p + tmp;
 113 }
 114
 115 #define WRITE32(n)               *p++ = htonl(n)
 116 #define WRITEMEM(ptr,nbytes)     do {                           \
 117         p = xdr_writemem(p, ptr, nbytes);                       \
 118 } while (0)
 119 #define RESERVE_SPACE(nbytes)   do {                            \
 120         p = xdr_reserve_space(xdr, nbytes);                     \
 121         if (!p) dprintk("NFSD: RESERVE_SPACE(%d) failed in function %s\n", (int) (nbytes), __func__); \
 122         BUG_ON(!p);                                             \
 123 } while (0)
 124
 125 /*
 126  * Generic decode routines from fs/nfs/nfs4xdr.c
 127  */
 128 #define DECODE_TAIL                             \
 129         status = 0;                             \
 130 out:                                            \
 131         return status;                          \
 132 xdr_error:                                      \
 133         dprintk("NFSD: xdr error! (%s:%d)\n", __FILE__, __LINE__); \
 134         status = -EIO;                          \
 135         goto out
 136
 137 #define READ32(x)         (x) = ntohl(*p++)
 138 #define READ64(x)         do {                  \
 139         (x) = (u64)ntohl(*p++) << 32;           \
 140         (x) |= ntohl(*p++);                     \
 141 } while (0)
 142 #define READTIME(x)       do {                  \
 143         p++;                                    \
 144         (x.tv_sec) = ntohl(*p++);               \
 145         (x.tv_nsec) = ntohl(*p++);              \
 146 } while (0)
 147 #define READ_BUF(nbytes)  do { \
 148         p = xdr_inline_decode(xdr, nbytes); \
 149         if (!p) { \
 150                 dprintk("NFSD: %s: reply buffer overflowed in line %d.\n", \
 151                         __func__, __LINE__); \
 152                 return -EIO; \
 153         } \
 154 } while (0)
 155
 156 struct nfs4_cb_compound_hdr {
 157         /* args */
 158         u32             ident;  /* minorversion 0 only */
 159         u32             nops;
 160         __be32          *nops_p;
 161         u32             minorversion;
 162         /* res */
 163         int             status;
 164         u32             taglen;
 165         char            *tag;
 166 };
 167
 168 static struct {
 169 int stat;
 170 int errno;
 171 } nfs_cb_errtbl[] = {
 172         { NFS4_OK,              0               },
 173         { NFS4ERR_PERM,         EPERM           },
 174         { NFS4ERR_NOENT,        ENOENT          },
 175         { NFS4ERR_IO,           EIO             },
 176         { NFS4ERR_NXIO,         ENXIO           },
 177         { NFS4ERR_ACCESS,       EACCES          },
 178         { NFS4ERR_EXIST,        EEXIST          },
 179         { NFS4ERR_XDEV,         EXDEV           },
 180         { NFS4ERR_NOTDIR,       ENOTDIR         },
 181         { NFS4ERR_ISDIR,        EISDIR          },
 182         { NFS4ERR_INVAL,        EINVAL          },
 183         { NFS4ERR_FBIG,         EFBIG           },
 184         { NFS4ERR_NOSPC,        ENOSPC          },
 185         { NFS4ERR_ROFS,         EROFS           },
 186         { NFS4ERR_MLINK,        EMLINK          },
 187         { NFS4ERR_NAMETOOLONG,  ENAMETOOLONG    },
 188         { NFS4ERR_NOTEMPTY,     ENOTEMPTY       },
 189         { NFS4ERR_DQUOT,        EDQUOT          },
 190         { NFS4ERR_STALE,        ESTALE          },
 191         { NFS4ERR_BADHANDLE,    EBADHANDLE      },
 192         { NFS4ERR_BAD_COOKIE,   EBADCOOKIE      },
 193         { NFS4ERR_NOTSUPP,      ENOTSUPP        },
 194         { NFS4ERR_TOOSMALL,     ETOOSMALL       },
 195         { NFS4ERR_SERVERFAULT,  ESERVERFAULT    },
 196         { NFS4ERR_BADTYPE,      EBADTYPE        },
 197         { NFS4ERR_LOCKED,       EAGAIN          },
 198         { NFS4ERR_RESOURCE,     EREMOTEIO       },
 199         { NFS4ERR_SYMLINK,      ELOOP           },
 200         { NFS4ERR_OP_ILLEGAL,   EOPNOTSUPP      },
 201         { NFS4ERR_DEADLOCK,     EDEADLK         },
 202         { -1,                   EIO             }
 203 };
 204
 205 static int
 206 nfs_cb_stat_to_errno(int stat)
 207 {
 208         int i;
 209         for (i = 0; nfs_cb_errtbl[i].stat != -1; i++) {
 210                 if (nfs_cb_errtbl[i].stat == stat)
 211                         return nfs_cb_errtbl[i].errno;
 212         }
 213         /* If we cannot translate the error, the recovery routines should
 214         * handle it.
 215         * Note: remaining NFSv4 error codes have values > 10000, so should
 216         * not conflict with native Linux error codes.
 217         */
 218         return stat;
 219 }
 220
 221 /*
 222  * XDR encode
 223  */
 224
 225 static void
 226 encode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr)
 227 {
 228         __be32 * p;
 229
 230         RESERVE_SPACE(16);
 231         WRITE32(0);            /* tag length is always 0 */
 232         WRITE32(hdr->minorversion);
 233         WRITE32(hdr->ident);
 234         hdr->nops_p = p;
 235         WRITE32(hdr->nops);
 236 }
 237
 238 static void encode_cb_nops(struct nfs4_cb_compound_hdr *hdr)
 239 {
 240         *hdr->nops_p = htonl(hdr->nops);
 241 }
 242
 243 static void
 244 encode_cb_recall(struct xdr_stream *xdr, struct nfs4_delegation *dp,
 245                 struct nfs4_cb_compound_hdr *hdr)
 246 {
 247         __be32 *p;
 248         int len = dp->dl_fh.fh_size;
 249
 250         RESERVE_SPACE(12+sizeof(dp->dl_stateid) + len);
 251         WRITE32(OP_CB_RECALL);
 252         WRITE32(dp->dl_stateid.si_generation);
 253         WRITEMEM(&dp->dl_stateid.si_opaque, sizeof(stateid_opaque_t));
 254         WRITE32(0); /* truncate optimization not implemented */
 255         WRITE32(len);
 256         WRITEMEM(&dp->dl_fh.fh_base, len);
 257         hdr->nops++;
 258 }
 259
 260 static void
 261 encode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *args,
 262                    struct nfs4_cb_compound_hdr *hdr)
 263 {
 264         __be32 *p;
 265
 266         if (hdr->minorversion == 0)
 267                 return;
 268
 269         RESERVE_SPACE(1 + NFS4_MAX_SESSIONID_LEN + 20);
 270
 271         WRITE32(OP_CB_SEQUENCE);
 272         WRITEMEM(args->cbs_clp->cl_sessionid.data, NFS4_MAX_SESSIONID_LEN);
 273         WRITE32(args->cbs_clp->cl_cb_seq_nr);
 274         WRITE32(0);             /* slotid, always 0 */
 275         WRITE32(0);             /* highest slotid always 0 */
 276         WRITE32(0);             /* cachethis always 0 */
 277         WRITE32(0); /* FIXME: support referring_call_lists */
 278         hdr->nops++;
 279 }
 280
 281 static int
 282 nfs4_xdr_enc_cb_null(struct rpc_rqst *req, __be32 *p)
 283 {
 284         struct xdr_stream xdrs, *xdr = &xdrs;
 285
 286         xdr_init_encode(&xdrs, &req->rq_snd_buf, p);
 287         RESERVE_SPACE(0);
 288         return 0;
 289 }
 290
 291 static int
 292 nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
 293                 struct nfs4_rpc_args *rpc_args)
 294 {
 295         struct xdr_stream xdr;
 296         struct nfs4_delegation *args = rpc_args->args_op;
 297         struct nfs4_cb_compound_hdr hdr = {
 298                 .ident = args->dl_ident,
 299                 .minorversion = rpc_args->args_seq.cbs_minorversion,
 300         };
 301
 302         xdr_init_encode(&xdr, &req->rq_snd_buf, p);
 303         encode_cb_compound_hdr(&xdr, &hdr);
 304         encode_cb_sequence(&xdr, &rpc_args->args_seq, &hdr);
 305         encode_cb_recall(&xdr, args, &hdr);
 306         encode_cb_nops(&hdr);
 307         return 0;
 308 }
 309
 310
 311 static int
 312 decode_cb_compound_hdr(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr){
 313         __be32 *p;
 314
 315         READ_BUF(8);
 316         READ32(hdr->status);
 317         READ32(hdr->taglen);
 318         READ_BUF(hdr->taglen + 4);
 319         hdr->tag = (char *)p;
 320         p += XDR_QUADLEN(hdr->taglen);
 321         READ32(hdr->nops);
 322         return 0;
 323 }
 324
 325 static int
 326 decode_cb_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
 327 {
 328         __be32 *p;
 329         u32 op;
 330         int32_t nfserr;
 331
 332         READ_BUF(8);
 333         READ32(op);
 334         if (op != expected) {
 335                 dprintk("NFSD: decode_cb_op_hdr: Callback server returned "
 336                          " operation %d but we issued a request for %d\n",
 337                          op, expected);
 338                 return -EIO;
 339         }
 340         READ32(nfserr);
 341         if (nfserr != NFS_OK)
 342                 return -nfs_cb_stat_to_errno(nfserr);
 343         return 0;
 344 }
 345
 346 /*
 347  * Our current back channel implmentation supports a single backchannel
 348  * with a single slot.
 349  */
 350 static int
 351 decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *res,
 352                    struct rpc_rqst *rqstp)
 353 {
 354         struct nfs4_sessionid id;
 355         int status;
 356         u32 dummy;
 357         __be32 *p;
 358
 359         if (res->cbs_minorversion == 0)
 360                 return 0;
 361
 362         status = decode_cb_op_hdr(xdr, OP_CB_SEQUENCE);
 363         if (status)
 364                 return status;
 365
 366         /*
 367          * If the server returns different values for sessionID, slotID or
 368          * sequence number, the server is looney tunes.
 369          */
 370         status = -ESERVERFAULT;
 371
 372         READ_BUF(NFS4_MAX_SESSIONID_LEN + 16);
 373         memcpy(id.data, p, NFS4_MAX_SESSIONID_LEN);
 374         p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN);
 375         if (memcmp(id.data, res->cbs_clp->cl_sessionid.data,
 376                    NFS4_MAX_SESSIONID_LEN)) {
 377                 dprintk("%s Invalid session id\n", __func__);
 378                 goto out;
 379         }
 380         READ32(dummy);
 381         if (dummy != res->cbs_clp->cl_cb_seq_nr) {
 382                 dprintk("%s Invalid sequence number\n", __func__);
 383                 goto out;
 384         }
 385         READ32(dummy);  /* slotid must be 0 */
 386         if (dummy != 0) {
 387                 dprintk("%s Invalid slotid\n", __func__);
 388                 goto out;
 389         }
 390         /* FIXME: process highest slotid and target highest slotid */
 391         status = 0;
 392 out:
 393         return status;
 394 }
 395
 396
 397 static int
 398 nfs4_xdr_dec_cb_null(struct rpc_rqst *req, __be32 *p)
 399 {
 400         return 0;
 401 }
 402
 403 static int
 404 nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p,
 405                 struct nfsd4_cb_sequence *seq)
 406 {
 407         struct xdr_stream xdr;
 408         struct nfs4_cb_compound_hdr hdr;
 409         int status;
 410
 411         xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
 412         status = decode_cb_compound_hdr(&xdr, &hdr);
 413         if (status)
 414                 goto out;
 415         if (seq) {
 416                 status = decode_cb_sequence(&xdr, seq, rqstp);
 417                 if (status)
 418                         goto out;
 419         }
 420         status = decode_cb_op_hdr(&xdr, OP_CB_RECALL);
 421 out:
 422         return status;
 423 }
 424
 425 /*
 426  * RPC procedure tables
 427  */
 428 #define PROC(proc, call, argtype, restype)                              \
 429 [NFSPROC4_CLNT_##proc] = {                                              \
 430         .p_proc   = NFSPROC4_CB_##call,                                 \
 431         .p_encode = (kxdrproc_t) nfs4_xdr_##argtype,                    \
 432         .p_decode = (kxdrproc_t) nfs4_xdr_##restype,                    \
 433         .p_arglen = NFS4_##argtype##_sz,                                \
 434         .p_replen = NFS4_##restype##_sz,                                \
 435         .p_statidx = NFSPROC4_CB_##call,                                \
 436         .p_name   = #proc,                                              \
 437 }
 438
 439 static struct rpc_procinfo     nfs4_cb_procedures[] = {
 440     PROC(CB_NULL,      NULL,     enc_cb_null,     dec_cb_null),
 441     PROC(CB_RECALL,    COMPOUND,   enc_cb_recall,      dec_cb_recall),
 442 };
 443
 444 static struct rpc_version       nfs_cb_version4 = {
 445         .number                 = 1,
 446         .nrprocs                = ARRAY_SIZE(nfs4_cb_procedures),
 447         .procs                  = nfs4_cb_procedures
 448 };
 449
 450 static struct rpc_version *     nfs_cb_version[] = {
 451         NULL,
 452         &nfs_cb_version4,
 453 };
 454
 455 static struct rpc_program cb_program;
 456
 457 static struct rpc_stat cb_stats = {
 458                 .program        = &cb_program
 459 };
 460
 461 #define NFS4_CALLBACK 0x40000000
 462 static struct rpc_program cb_program = {
 463                 .name           = "nfs4_cb",
 464                 .number         = NFS4_CALLBACK,
 465                 .nrvers         = ARRAY_SIZE(nfs_cb_version),
 466                 .version        = nfs_cb_version,
 467                 .stats          = &cb_stats,
 468                 .pipe_dir_name  = "/nfsd4_cb",
 469 };
 470
 471 static int max_cb_time(void)
 472 {
 473         return max(NFSD_LEASE_TIME/10, (time_t)1) * HZ;
 474 }
 475
 476 /* Reference counting, callback cleanup, etc., all look racy as heck.
 477  * And why is cb_set an atomic? */
 478
 479 int setup_callback_client(struct nfs4_client *clp)
 480 {
 481         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 482         struct rpc_timeout      timeparms = {
 483                 .to_initval     = max_cb_time(),
 484                 .to_retries     = 0,
 485         };
 486         struct rpc_create_args args = {
 487                 .protocol       = XPRT_TRANSPORT_TCP,
 488                 .address        = (struct sockaddr *) &cb->cb_addr,
 489                 .addrsize       = cb->cb_addrlen,
 490                 .timeout        = &timeparms,
 491                 .program        = &cb_program,
 492                 .prognumber     = cb->cb_prog,
 493                 .version        = nfs_cb_version[1]->number,
 494                 .authflavor     = clp->cl_flavor,
 495                 .flags          = (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
 496                 .client_name    = clp->cl_principal,
 497         };
 498         struct rpc_clnt *client;
 499
 500         if (!clp->cl_principal && (clp->cl_flavor >= RPC_AUTH_GSS_KRB5))
 501                 return -EINVAL;
 502         if (cb->cb_minorversion) {
 503                 args.bc_xprt = clp->cl_cb_xprt;
 504                 args.protocol = XPRT_TRANSPORT_BC_TCP;
 505         }
 506         /* Create RPC client */
 507         client = rpc_create(&args);
 508         if (IS_ERR(client)) {
 509                 dprintk("NFSD: couldn't create callback client: %ld\n",
 510                         PTR_ERR(client));
 511                 return PTR_ERR(client);
 512         }
 513         cb->cb_client = client;
 514         return 0;
 515
 516 }
 517
 518 static void warn_no_callback_path(struct nfs4_client *clp, int reason)
 519 {
 520         dprintk("NFSD: warning: no callback path to client %.*s: error %d\n",
 521                 (int)clp->cl_name.len, clp->cl_name.data, reason);
 522 }
 523
 524 static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 525 {
 526         struct nfs4_client *clp = calldata;
 527
 528         if (task->tk_status)
 529                 warn_no_callback_path(clp, task->tk_status);
 530         else
 531                 atomic_set(&clp->cl_cb_conn.cb_set, 1);
 532         put_nfs4_client(clp);
 533 }
 534
 535 static const struct rpc_call_ops nfsd4_cb_probe_ops = {
 536         .rpc_call_done = nfsd4_cb_probe_done,
 537 };
 538
 539 static struct rpc_cred *callback_cred;
 540
 541 int set_callback_cred(void)
 542 {
 543         callback_cred = rpc_lookup_machine_cred();
 544         if (!callback_cred)
 545                 return -ENOMEM;
 546         return 0;
 547 }
 548
 549
 550 void do_probe_callback(struct nfs4_client *clp)
 551 {
 552         struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 553         struct rpc_message msg = {
 554                 .rpc_proc       = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL],
 555                 .rpc_argp       = clp,
 556                 .rpc_cred       = callback_cred
 557         };
 558         int status;
 559
 560         status = rpc_call_async(cb->cb_client, &msg, RPC_TASK_SOFT,
 561                                 &nfsd4_cb_probe_ops, (void *)clp);
 562         if (status) {
 563                 warn_no_callback_path(clp, status);
 564                 put_nfs4_client(clp);
 565         }
 566 }
 567
 568 /*
 569  * Set up the callback client and put a NFSPROC4_CB_NULL on the wire...
 570  */
 571 void
 572 nfsd4_probe_callback(struct nfs4_client *clp)
 573 {
 574         int status;
 575
 576         BUG_ON(atomic_read(&clp->cl_cb_conn.cb_set));
 577
 578         status = setup_callback_client(clp);
 579         if (status) {
 580                 warn_no_callback_path(clp, status);
 581                 return;
 582         }
 583
 584         /* the task holds a reference to the nfs4_client struct */
 585         atomic_inc(&clp->cl_count);
 586
 587         do_probe_callback(clp);
 588 }
 589
 590 /*
 591  * There's currently a single callback channel slot.
 592  * If the slot is available, then mark it busy.  Otherwise, set the
 593  * thread for sleeping on the callback RPC wait queue.
 594  */
 595 static int nfsd41_cb_setup_sequence(struct nfs4_client *clp,
 596                 struct rpc_task *task)
 597 {
 598         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
 599         u32 *ptr = (u32 *)clp->cl_sessionid.data;
 600         int status = 0;
 601
 602         dprintk("%s: %u:%u:%u:%u\n", __func__,
 603                 ptr[0], ptr[1], ptr[2], ptr[3]);
 604
 605         if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
 606                 rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
 607                 dprintk("%s slot is busy\n", __func__);
 608                 status = -EAGAIN;
 609                 goto out;
 610         }
 611
 612         /*
 613          * We'll need the clp during XDR encoding and decoding,
 614          * and the sequence during decoding to verify the reply
 615          */
 616         args->args_seq.cbs_clp = clp;
 617         task->tk_msg.rpc_resp = &args->args_seq;
 618
 619 out:
 620         dprintk("%s status=%d\n", __func__, status);
 621         return status;
 622 }
 623
 624 /*
 625  * TODO: cb_sequence should support referring call lists, cachethis, multiple
 626  * slots, and mark callback channel down on communication errors.
 627  */
 628 static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
 629 {
 630         struct nfs4_delegation *dp = calldata;
 631         struct nfs4_client *clp = dp->dl_client;
 632         struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
 633         u32 minorversion = clp->cl_cb_conn.cb_minorversion;
 634         int status = 0;
 635
 636         args->args_seq.cbs_minorversion = minorversion;
 637         if (minorversion) {
 638                 status = nfsd41_cb_setup_sequence(clp, task);
 639                 if (status) {
 640                         if (status != -EAGAIN) {
 641                                 /* terminate rpc task */
 642                                 task->tk_status = status;
 643                                 task->tk_action = NULL;
 644                         }
 645                         return;
 646                 }
 647         }
 648         rpc_call_start(task);
 649 }
 650
 651 static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
 652 {
 653         struct nfs4_delegation *dp = calldata;
 654         struct nfs4_client *clp = dp->dl_client;
 655
 656         dprintk("%s: minorversion=%d\n", __func__,
 657                 clp->cl_cb_conn.cb_minorversion);
 658
 659         if (clp->cl_cb_conn.cb_minorversion) {
 660                 /* No need for lock, access serialized in nfsd4_cb_prepare */
 661                 ++clp->cl_cb_seq_nr;
 662                 clear_bit(0, &clp->cl_cb_slot_busy);
 663                 rpc_wake_up_next(&clp->cl_cb_waitq);
 664                 dprintk("%s: freed slot, new seqid=%d\n", __func__,
 665                         clp->cl_cb_seq_nr);
 666
 667                 /* We're done looking into the sequence information */
 668                 task->tk_msg.rpc_resp = NULL;
 669         }
 670 }
 671
 672 static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
 673 {
 674         struct nfs4_delegation *dp = calldata;
 675         struct nfs4_client *clp = dp->dl_client;
 676
 677         nfsd4_cb_done(task, calldata);
 678
 679         switch (task->tk_status) {
 680         case -EIO:
 681                 /* Network partition? */
 682                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
 683                 warn_no_callback_path(clp, task->tk_status);
 684         case -EBADHANDLE:
 685         case -NFS4ERR_BAD_STATEID:
 686                 /* Race: client probably got cb_recall
 687                  * before open reply granting delegation */
 688                 break;
 689         default:
 690                 /* success, or error we can't handle */
 691                 goto done;
 692         }
 693         if (dp->dl_retries--) {
 694                 rpc_delay(task, 2*HZ);
 695                 task->tk_status = 0;
 696                 rpc_restart_call(task);
 697                 return;
 698         } else {
 699                 atomic_set(&clp->cl_cb_conn.cb_set, 0);
 700                 warn_no_callback_path(clp, task->tk_status);
 701         }
 702 done:
 703         kfree(task->tk_msg.rpc_argp);
 704 }
 705
 706 static void nfsd4_cb_recall_release(void *calldata)
 707 {
 708         struct nfs4_delegation *dp = calldata;
 709         struct nfs4_client *clp = dp->dl_client;
 710
 711         nfs4_put_delegation(dp);
 712         put_nfs4_client(clp);
 713 }
 714
 715 static const struct rpc_call_ops nfsd4_cb_recall_ops = {
 716         .rpc_call_prepare = nfsd4_cb_prepare,
 717         .rpc_call_done = nfsd4_cb_recall_done,
 718         .rpc_release = nfsd4_cb_recall_release,
 719 };
 720
 721 /*
 722  * called with dp->dl_count inc'ed.
 723  */
 724 void
 725 nfsd4_cb_recall(struct nfs4_delegation *dp)
 726 {
 727         struct nfs4_client *clp = dp->dl_client;
 728         struct rpc_clnt *clnt = clp->cl_cb_conn.cb_client;
 729         struct nfs4_rpc_args *args;
 730         struct rpc_message msg = {
 731                 .rpc_proc = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_RECALL],
 732                 .rpc_cred = callback_cred
 733         };
 734         int status = -ENOMEM;
 735
 736         args = kzalloc(sizeof(*args), GFP_KERNEL);
 737         if (!args)
 738                 goto out;
 739         args->args_op = dp;
 740         msg.rpc_argp = args;
 741         dp->dl_retries = 1;
 742         status = rpc_call_async(clnt, &msg, RPC_TASK_SOFT,
 743                                 &nfsd4_cb_recall_ops, dp);
 744 out:
 745         if (status) {
 746                 kfree(args);
 747                 put_nfs4_client(clp);
 748                 nfs4_put_delegation(dp);
 749         }
 750 }