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