fs/nfsd/nfs4callback.c

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