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 <linux/sunrpc/xprt.h>
  36 #include <linux/sunrpc/svc_xprt.h>
  37 #include <linux/slab.h>
  38 #include "nfsd.h"
  39 #include "state.h"
  40 #include "netns.h"
  41 #include "xdr4cb.h"
  42 #include "xdr4.h"
  43
  44 #define NFSDDBG_FACILITY                NFSDDBG_PROC
  45
  46 static void nfsd4_mark_cb_fault(struct nfs4_client *, int reason);
  47
  48 #define NFSPROC4_CB_NULL 0
  49 #define NFSPROC4_CB_COMPOUND 1
  50
  51 /* Index of predefined Linux callback client operations */
  52
  53 struct nfs4_cb_compound_hdr {
  54         /* args */
  55         u32             ident;  /* minorversion 0 only */
  56         u32             nops;
  57         __be32          *nops_p;
  58         u32             minorversion;
  59         /* res */
  60         int             status;
  61 };
  62
  63 static __be32 *xdr_encode_empty_array(__be32 *p)
  64 {
  65         *p++ = xdr_zero;
  66         return p;
  67 }
  68
  69 /*
  70  * Encode/decode NFSv4 CB basic data types
  71  *
  72  * Basic NFSv4 callback data types are defined in section 15 of RFC
  73  * 3530: "Network File System (NFS) version 4 Protocol" and section
  74  * 20 of RFC 5661: "Network File System (NFS) Version 4 Minor Version
  75  * 1 Protocol"
  76  */
  77
  78 /*
  79  *      nfs_cb_opnum4
  80  *
  81  *      enum nfs_cb_opnum4 {
  82  *              OP_CB_GETATTR           = 3,
  83  *                ...
  84  *      };
  85  */
  86 enum nfs_cb_opnum4 {
  87         OP_CB_GETATTR                   = 3,
  88         OP_CB_RECALL                    = 4,
  89         OP_CB_LAYOUTRECALL              = 5,
  90         OP_CB_NOTIFY                    = 6,
  91         OP_CB_PUSH_DELEG                = 7,
  92         OP_CB_RECALL_ANY                = 8,
  93         OP_CB_RECALLABLE_OBJ_AVAIL      = 9,
  94         OP_CB_RECALL_SLOT               = 10,
  95         OP_CB_SEQUENCE                  = 11,
  96         OP_CB_WANTS_CANCELLED           = 12,
  97         OP_CB_NOTIFY_LOCK               = 13,
  98         OP_CB_NOTIFY_DEVICEID           = 14,
  99         OP_CB_OFFLOAD                   = 15,
 100         OP_CB_ILLEGAL                   = 10044
 101 };
 102
 103 static void encode_nfs_cb_opnum4(struct xdr_stream *xdr, enum nfs_cb_opnum4 op)
 104 {
 105         __be32 *p;
 106
 107         p = xdr_reserve_space(xdr, 4);
 108         *p = cpu_to_be32(op);
 109 }
 110
 111 /*
 112  * nfs_fh4
 113  *
 114  *      typedef opaque nfs_fh4<NFS4_FHSIZE>;
 115  */
 116 static void encode_nfs_fh4(struct xdr_stream *xdr, const struct knfsd_fh *fh)
 117 {
 118         u32 length = fh->fh_size;
 119         __be32 *p;
 120
 121         BUG_ON(length > NFS4_FHSIZE);
 122         p = xdr_reserve_space(xdr, 4 + length);
 123         xdr_encode_opaque(p, &fh->fh_base, length);
 124 }
 125
 126 /*
 127  * stateid4
 128  *
 129  *      struct stateid4 {
 130  *              uint32_t        seqid;
 131  *              opaque          other[12];
 132  *      };
 133  */
 134 static void encode_stateid4(struct xdr_stream *xdr, const stateid_t *sid)
 135 {
 136         __be32 *p;
 137
 138         p = xdr_reserve_space(xdr, NFS4_STATEID_SIZE);
 139         *p++ = cpu_to_be32(sid->si_generation);
 140         xdr_encode_opaque_fixed(p, &sid->si_opaque, NFS4_STATEID_OTHER_SIZE);
 141 }
 142
 143 /*
 144  * sessionid4
 145  *
 146  *      typedef opaque sessionid4[NFS4_SESSIONID_SIZE];
 147  */
 148 static void encode_sessionid4(struct xdr_stream *xdr,
 149                               const struct nfsd4_session *session)
 150 {
 151         __be32 *p;
 152
 153         p = xdr_reserve_space(xdr, NFS4_MAX_SESSIONID_LEN);
 154         xdr_encode_opaque_fixed(p, session->se_sessionid.data,
 155                                         NFS4_MAX_SESSIONID_LEN);
 156 }
 157
 158 /*
 159  * nfsstat4
 160  */
 161 static const struct {
 162         int stat;
 163         int errno;
 164 } nfs_cb_errtbl[] = {
 165         { NFS4_OK,              0               },
 166         { NFS4ERR_PERM,         -EPERM          },
 167         { NFS4ERR_NOENT,        -ENOENT         },
 168         { NFS4ERR_IO,           -EIO            },
 169         { NFS4ERR_NXIO,         -ENXIO          },
 170         { NFS4ERR_ACCESS,       -EACCES         },
 171         { NFS4ERR_EXIST,        -EEXIST         },
 172         { NFS4ERR_XDEV,         -EXDEV          },
 173         { NFS4ERR_NOTDIR,       -ENOTDIR        },
 174         { NFS4ERR_ISDIR,        -EISDIR         },
 175         { NFS4ERR_INVAL,        -EINVAL         },
 176         { NFS4ERR_FBIG,         -EFBIG          },
 177         { NFS4ERR_NOSPC,        -ENOSPC         },
 178         { NFS4ERR_ROFS,         -EROFS          },
 179         { NFS4ERR_MLINK,        -EMLINK         },
 180         { NFS4ERR_NAMETOOLONG,  -ENAMETOOLONG   },
 181         { NFS4ERR_NOTEMPTY,     -ENOTEMPTY      },
 182         { NFS4ERR_DQUOT,        -EDQUOT         },
 183         { NFS4ERR_STALE,        -ESTALE         },
 184         { NFS4ERR_BADHANDLE,    -EBADHANDLE     },
 185         { NFS4ERR_BAD_COOKIE,   -EBADCOOKIE     },
 186         { NFS4ERR_NOTSUPP,      -ENOTSUPP       },
 187         { NFS4ERR_TOOSMALL,     -ETOOSMALL      },
 188         { NFS4ERR_SERVERFAULT,  -ESERVERFAULT   },
 189         { NFS4ERR_BADTYPE,      -EBADTYPE       },
 190         { NFS4ERR_LOCKED,       -EAGAIN         },
 191         { NFS4ERR_RESOURCE,     -EREMOTEIO      },
 192         { NFS4ERR_SYMLINK,      -ELOOP          },
 193         { NFS4ERR_OP_ILLEGAL,   -EOPNOTSUPP     },
 194         { NFS4ERR_DEADLOCK,     -EDEADLK        },
 195         { -1,                   -EIO            }
 196 };
 197
 198 /*
 199  * If we cannot translate the error, the recovery routines should
 200  * handle it.
 201  *
 202  * Note: remaining NFSv4 error codes have values > 10000, so should
 203  * not conflict with native Linux error codes.
 204  */
 205 static int nfs_cb_stat_to_errno(int status)
 206 {
 207         int i;
 208
 209         for (i = 0; nfs_cb_errtbl[i].stat != -1; i++) {
 210                 if (nfs_cb_errtbl[i].stat == status)
 211                         return nfs_cb_errtbl[i].errno;
 212         }
 213
 214         dprintk("NFSD: Unrecognized NFS CB status value: %u\n", status);
 215         return -status;
 216 }
 217
 218 static int decode_cb_op_status(struct xdr_stream *xdr,
 219                                enum nfs_cb_opnum4 expected, int *status)
 220 {
 221         __be32 *p;
 222         u32 op;
 223
 224         p = xdr_inline_decode(xdr, 4 + 4);
 225         if (unlikely(p == NULL))
 226                 goto out_overflow;
 227         op = be32_to_cpup(p++);
 228         if (unlikely(op != expected))
 229                 goto out_unexpected;
 230         *status = nfs_cb_stat_to_errno(be32_to_cpup(p));
 231         return 0;
 232 out_overflow:
 233         return -EIO;
 234 out_unexpected:
 235         dprintk("NFSD: Callback server returned operation %d but "
 236                 "we issued a request for %d\n", op, expected);
 237         return -EIO;
 238 }
 239
 240 /*
 241  * CB_COMPOUND4args
 242  *
 243  *      struct CB_COMPOUND4args {
 244  *              utf8str_cs      tag;
 245  *              uint32_t        minorversion;
 246  *              uint32_t        callback_ident;
 247  *              nfs_cb_argop4   argarray<>;
 248  *      };
 249 */
 250 static void encode_cb_compound4args(struct xdr_stream *xdr,
 251                                     struct nfs4_cb_compound_hdr *hdr)
 252 {
 253         __be32 * p;
 254
 255         p = xdr_reserve_space(xdr, 4 + 4 + 4 + 4);
 256         p = xdr_encode_empty_array(p);          /* empty tag */
 257         *p++ = cpu_to_be32(hdr->minorversion);
 258         *p++ = cpu_to_be32(hdr->ident);
 259
 260         hdr->nops_p = p;
 261         *p = cpu_to_be32(hdr->nops);            /* argarray element count */
 262 }
 263
 264 /*
 265  * Update argarray element count
 266  */
 267 static void encode_cb_nops(struct nfs4_cb_compound_hdr *hdr)
 268 {
 269         BUG_ON(hdr->nops > NFS4_MAX_BACK_CHANNEL_OPS);
 270         *hdr->nops_p = cpu_to_be32(hdr->nops);
 271 }
 272
 273 /*
 274  * CB_COMPOUND4res
 275  *
 276  *      struct CB_COMPOUND4res {
 277  *              nfsstat4        status;
 278  *              utf8str_cs      tag;
 279  *              nfs_cb_resop4   resarray<>;
 280  *      };
 281  */
 282 static int decode_cb_compound4res(struct xdr_stream *xdr,
 283                                   struct nfs4_cb_compound_hdr *hdr)
 284 {
 285         u32 length;
 286         __be32 *p;
 287
 288         p = xdr_inline_decode(xdr, 4 + 4);
 289         if (unlikely(p == NULL))
 290                 goto out_overflow;
 291         hdr->status = be32_to_cpup(p++);
 292         /* Ignore the tag */
 293         length = be32_to_cpup(p++);
 294         p = xdr_inline_decode(xdr, length + 4);
 295         if (unlikely(p == NULL))
 296                 goto out_overflow;
 297         p += XDR_QUADLEN(length);
 298         hdr->nops = be32_to_cpup(p);
 299         return 0;
 300 out_overflow:
 301         return -EIO;
 302 }
 303
 304 /*
 305  * CB_RECALL4args
 306  *
 307  *      struct CB_RECALL4args {
 308  *              stateid4        stateid;
 309  *              bool            truncate;
 310  *              nfs_fh4         fh;
 311  *      };
 312  */
 313 static void encode_cb_recall4args(struct xdr_stream *xdr,
 314                                   const struct nfs4_delegation *dp,
 315                                   struct nfs4_cb_compound_hdr *hdr)
 316 {
 317         __be32 *p;
 318
 319         encode_nfs_cb_opnum4(xdr, OP_CB_RECALL);
 320         encode_stateid4(xdr, &dp->dl_stid.sc_stateid);
 321
 322         p = xdr_reserve_space(xdr, 4);
 323         *p++ = xdr_zero;                        /* truncate */
 324
 325         encode_nfs_fh4(xdr, &dp->dl_stid.sc_file->fi_fhandle);
 326
 327         hdr->nops++;
 328 }
 329
 330 /*
 331  * CB_SEQUENCE4args
 332  *
 333  *      struct CB_SEQUENCE4args {
 334  *              sessionid4              csa_sessionid;
 335  *              sequenceid4             csa_sequenceid;
 336  *              slotid4                 csa_slotid;
 337  *              slotid4                 csa_highest_slotid;
 338  *              bool                    csa_cachethis;
 339  *              referring_call_list4    csa_referring_call_lists<>;
 340  *      };
 341  */
 342 static void encode_cb_sequence4args(struct xdr_stream *xdr,
 343                                     const struct nfsd4_callback *cb,
 344                                     struct nfs4_cb_compound_hdr *hdr)
 345 {
 346         struct nfsd4_session *session = cb->cb_clp->cl_cb_session;
 347         __be32 *p;
 348
 349         if (hdr->minorversion == 0)
 350                 return;
 351
 352         encode_nfs_cb_opnum4(xdr, OP_CB_SEQUENCE);
 353         encode_sessionid4(xdr, session);
 354
 355         p = xdr_reserve_space(xdr, 4 + 4 + 4 + 4 + 4);
 356         *p++ = cpu_to_be32(session->se_cb_seq_nr);      /* csa_sequenceid */
 357         *p++ = xdr_zero;                        /* csa_slotid */
 358         *p++ = xdr_zero;                        /* csa_highest_slotid */
 359         *p++ = xdr_zero;                        /* csa_cachethis */
 360         xdr_encode_empty_array(p);              /* csa_referring_call_lists */
 361
 362         hdr->nops++;
 363 }
 364
 365 /*
 366  * CB_SEQUENCE4resok
 367  *
 368  *      struct CB_SEQUENCE4resok {
 369  *              sessionid4      csr_sessionid;
 370  *              sequenceid4     csr_sequenceid;
 371  *              slotid4         csr_slotid;
 372  *              slotid4         csr_highest_slotid;
 373  *              slotid4         csr_target_highest_slotid;
 374  *      };
 375  *
 376  *      union CB_SEQUENCE4res switch (nfsstat4 csr_status) {
 377  *      case NFS4_OK:
 378  *              CB_SEQUENCE4resok       csr_resok4;
 379  *      default:
 380  *              void;
 381  *      };
 382  *
 383  * Our current back channel implmentation supports a single backchannel
 384  * with a single slot.
 385  */
 386 static int decode_cb_sequence4resok(struct xdr_stream *xdr,
 387                                     struct nfsd4_callback *cb)
 388 {
 389         struct nfsd4_session *session = cb->cb_clp->cl_cb_session;
 390         int status = -ESERVERFAULT;
 391         __be32 *p;
 392         u32 dummy;
 393
 394         /*
 395          * If the server returns different values for sessionID, slotID or
 396          * sequence number, the server is looney tunes.
 397          */
 398         p = xdr_inline_decode(xdr, NFS4_MAX_SESSIONID_LEN + 4 + 4 + 4 + 4);
 399         if (unlikely(p == NULL))
 400                 goto out_overflow;
 401
 402         if (memcmp(p, session->se_sessionid.data, NFS4_MAX_SESSIONID_LEN)) {
 403                 dprintk("NFS: %s Invalid session id\n", __func__);
 404                 goto out;
 405         }
 406         p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN);
 407
 408         dummy = be32_to_cpup(p++);
 409         if (dummy != session->se_cb_seq_nr) {
 410                 dprintk("NFS: %s Invalid sequence number\n", __func__);
 411                 goto out;
 412         }
 413
 414         dummy = be32_to_cpup(p++);
 415         if (dummy != 0) {
 416                 dprintk("NFS: %s Invalid slotid\n", __func__);
 417                 goto out;
 418         }
 419
 420         /*
 421          * FIXME: process highest slotid and target highest slotid
 422          */
 423         status = 0;
 424 out:
 425         cb->cb_seq_status = status;
 426         return status;
 427 out_overflow:
 428         status = -EIO;
 429         goto out;
 430 }
 431
 432 static int decode_cb_sequence4res(struct xdr_stream *xdr,
 433                                   struct nfsd4_callback *cb)
 434 {
 435         int status;
 436
 437         if (cb->cb_clp->cl_minorversion == 0)
 438                 return 0;
 439
 440         status = decode_cb_op_status(xdr, OP_CB_SEQUENCE, &cb->cb_seq_status);
 441         if (unlikely(status || cb->cb_seq_status))
 442                 return status;
 443
 444         return decode_cb_sequence4resok(xdr, cb);
 445 }
 446
 447 /*
 448  * NFSv4.0 and NFSv4.1 XDR encode functions
 449  *
 450  * NFSv4.0 callback argument types are defined in section 15 of RFC
 451  * 3530: "Network File System (NFS) version 4 Protocol" and section 20
 452  * of RFC 5661:  "Network File System (NFS) Version 4 Minor Version 1
 453  * Protocol".
 454  */
 455
 456 /*
 457  * NB: Without this zero space reservation, callbacks over krb5p fail
 458  */
 459 static void nfs4_xdr_enc_cb_null(struct rpc_rqst *req, struct xdr_stream *xdr,
 460                                  const void *__unused)
 461 {
 462         xdr_reserve_space(xdr, 0);
 463 }
 464
 465 /*
 466  * 20.2. Operation 4: CB_RECALL - Recall a Delegation
 467  */
 468 static void nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, struct xdr_stream *xdr,
 469                                    const void *data)
 470 {
 471         const struct nfsd4_callback *cb = data;
 472         const struct nfs4_delegation *dp = cb_to_delegation(cb);
 473         struct nfs4_cb_compound_hdr hdr = {
 474                 .ident = cb->cb_clp->cl_cb_ident,
 475                 .minorversion = cb->cb_clp->cl_minorversion,
 476         };
 477
 478         encode_cb_compound4args(xdr, &hdr);
 479         encode_cb_sequence4args(xdr, cb, &hdr);
 480         encode_cb_recall4args(xdr, dp, &hdr);
 481         encode_cb_nops(&hdr);
 482 }
 483
 484
 485 /*
 486  * NFSv4.0 and NFSv4.1 XDR decode functions
 487  *
 488  * NFSv4.0 callback result types are defined in section 15 of RFC
 489  * 3530: "Network File System (NFS) version 4 Protocol" and section 20
 490  * of RFC 5661:  "Network File System (NFS) Version 4 Minor Version 1
 491  * Protocol".
 492  */
 493
 494 static int nfs4_xdr_dec_cb_null(struct rpc_rqst *req, struct xdr_stream *xdr,
 495                                 void *__unused)
 496 {
 497         return 0;
 498 }
 499
 500 /*
 501  * 20.2. Operation 4: CB_RECALL - Recall a Delegation
 502  */
 503 static int nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp,
 504                                   struct xdr_stream *xdr,
 505                                   void *data)
 506 {
 507         struct nfsd4_callback *cb = data;
 508         struct nfs4_cb_compound_hdr hdr;
 509         int status;
 510
 511         status = decode_cb_compound4res(xdr, &hdr);
 512         if (unlikely(status))
 513                 return status;
 514
 515         if (cb != NULL) {
 516                 status = decode_cb_sequence4res(xdr, cb);
 517                 if (unlikely(status || cb->cb_seq_status))
 518                         return status;
 519         }
 520
 521         return decode_cb_op_status(xdr, OP_CB_RECALL, &cb->cb_status);
 522 }
 523
 524 #ifdef CONFIG_NFSD_PNFS
 525 /*
 526  * CB_LAYOUTRECALL4args
 527  *
 528  *      struct layoutrecall_file4 {
 529  *              nfs_fh4         lor_fh;
 530  *              offset4         lor_offset;
 531  *              length4         lor_length;
 532  *              stateid4        lor_stateid;
 533  *      };
 534  *
 535  *      union layoutrecall4 switch(layoutrecall_type4 lor_recalltype) {
 536  *      case LAYOUTRECALL4_FILE:
 537  *              layoutrecall_file4 lor_layout;
 538  *      case LAYOUTRECALL4_FSID:
 539  *              fsid4              lor_fsid;
 540  *      case LAYOUTRECALL4_ALL:
 541  *              void;
 542  *      };
 543  *
 544  *      struct CB_LAYOUTRECALL4args {
 545  *              layouttype4             clora_type;
 546  *              layoutiomode4           clora_iomode;
 547  *              bool                    clora_changed;
 548  *              layoutrecall4           clora_recall;
 549  *      };
 550  */
 551 static void encode_cb_layout4args(struct xdr_stream *xdr,
 552                                   const struct nfs4_layout_stateid *ls,
 553                                   struct nfs4_cb_compound_hdr *hdr)
 554 {
 555         __be32 *p;
 556
 557         BUG_ON(hdr->minorversion == 0);
 558
 559         p = xdr_reserve_space(xdr, 5 * 4);
 560         *p++ = cpu_to_be32(OP_CB_LAYOUTRECALL);
 561         *p++ = cpu_to_be32(ls->ls_layout_type);
 562         *p++ = cpu_to_be32(IOMODE_ANY);
 563         *p++ = cpu_to_be32(1);
 564         *p = cpu_to_be32(RETURN_FILE);
 565
 566         encode_nfs_fh4(xdr, &ls->ls_stid.sc_file->fi_fhandle);
 567
 568         p = xdr_reserve_space(xdr, 2 * 8);
 569         p = xdr_encode_hyper(p, 0);
 570         xdr_encode_hyper(p, NFS4_MAX_UINT64);
 571
 572         encode_stateid4(xdr, &ls->ls_recall_sid);
 573
 574         hdr->nops++;
 575 }
 576
 577 static void nfs4_xdr_enc_cb_layout(struct rpc_rqst *req,
 578                                    struct xdr_stream *xdr,
 579                                    const void *data)
 580 {
 581         const struct nfsd4_callback *cb = data;
 582         const struct nfs4_layout_stateid *ls =
 583                 container_of(cb, struct nfs4_layout_stateid, ls_recall);
 584         struct nfs4_cb_compound_hdr hdr = {
 585                 .ident = 0,
 586                 .minorversion = cb->cb_clp->cl_minorversion,
 587         };
 588
 589         encode_cb_compound4args(xdr, &hdr);
 590         encode_cb_sequence4args(xdr, cb, &hdr);
 591         encode_cb_layout4args(xdr, ls, &hdr);
 592         encode_cb_nops(&hdr);
 593 }
 594
 595 static int nfs4_xdr_dec_cb_layout(struct rpc_rqst *rqstp,
 596                                   struct xdr_stream *xdr,
 597                                   void *data)
 598 {
 599         struct nfsd4_callback *cb = data;
 600         struct nfs4_cb_compound_hdr hdr;
 601         int status;
 602
 603         status = decode_cb_compound4res(xdr, &hdr);
 604         if (unlikely(status))
 605                 return status;
 606
 607         if (cb) {
 608                 status = decode_cb_sequence4res(xdr, cb);
 609                 if (unlikely(status || cb->cb_seq_status))
 610                         return status;
 611         }
 612         return decode_cb_op_status(xdr, OP_CB_LAYOUTRECALL, &cb->cb_status);
 613 }
 614 #endif /* CONFIG_NFSD_PNFS */
 615
 616 static void encode_stateowner(struct xdr_stream *xdr, struct nfs4_stateowner *so)
 617 {
 618         __be32  *p;
 619
 620         p = xdr_reserve_space(xdr, 8 + 4 + so->so_owner.len);
 621         p = xdr_encode_opaque_fixed(p, &so->so_client->cl_clientid, 8);
 622         xdr_encode_opaque(p, so->so_owner.data, so->so_owner.len);
 623 }
 624
 625 static void nfs4_xdr_enc_cb_notify_lock(struct rpc_rqst *req,
 626                                         struct xdr_stream *xdr,
 627                                         const void *data)
 628 {
 629         const struct nfsd4_callback *cb = data;
 630         const struct nfsd4_blocked_lock *nbl =
 631                 container_of(cb, struct nfsd4_blocked_lock, nbl_cb);
 632         struct nfs4_lockowner *lo = (struct nfs4_lockowner *)nbl->nbl_lock.fl_owner;
 633         struct nfs4_cb_compound_hdr hdr = {
 634                 .ident = 0,
 635                 .minorversion = cb->cb_clp->cl_minorversion,
 636         };
 637
 638         __be32 *p;
 639
 640         BUG_ON(hdr.minorversion == 0);
 641
 642         encode_cb_compound4args(xdr, &hdr);
 643         encode_cb_sequence4args(xdr, cb, &hdr);
 644
 645         p = xdr_reserve_space(xdr, 4);
 646         *p = cpu_to_be32(OP_CB_NOTIFY_LOCK);
 647         encode_nfs_fh4(xdr, &nbl->nbl_fh);
 648         encode_stateowner(xdr, &lo->lo_owner);
 649         hdr.nops++;
 650
 651         encode_cb_nops(&hdr);
 652 }
 653
 654 static int nfs4_xdr_dec_cb_notify_lock(struct rpc_rqst *rqstp,
 655                                         struct xdr_stream *xdr,
 656                                         void *data)
 657 {
 658         struct nfsd4_callback *cb = data;
 659         struct nfs4_cb_compound_hdr hdr;
 660         int status;
 661
 662         status = decode_cb_compound4res(xdr, &hdr);
 663         if (unlikely(status))
 664                 return status;
 665
 666         if (cb) {
 667                 status = decode_cb_sequence4res(xdr, cb);
 668                 if (unlikely(status || cb->cb_seq_status))
 669                         return status;
 670         }
 671         return decode_cb_op_status(xdr, OP_CB_NOTIFY_LOCK, &cb->cb_status);
 672 }
 673
 674 /*
 675  * struct write_response4 {
 676  *      stateid4        wr_callback_id<1>;
 677  *      length4         wr_count;
 678  *      stable_how4     wr_committed;
 679  *      verifier4       wr_writeverf;
 680  * };
 681  * union offload_info4 switch (nfsstat4 coa_status) {
 682  *      case NFS4_OK:
 683  *              write_response4 coa_resok4;
 684  *      default:
 685  *      length4         coa_bytes_copied;
 686  * };
 687  * struct CB_OFFLOAD4args {
 688  *      nfs_fh4         coa_fh;
 689  *      stateid4        coa_stateid;
 690  *      offload_info4   coa_offload_info;
 691  * };
 692  */
 693 static void encode_offload_info4(struct xdr_stream *xdr,
 694                                  __be32 nfserr,
 695                                  const struct nfsd4_copy *cp)
 696 {
 697         __be32 *p;
 698
 699         p = xdr_reserve_space(xdr, 4);
 700         *p++ = nfserr;
 701         if (!nfserr) {
 702                 p = xdr_reserve_space(xdr, 4 + 8 + 4 + NFS4_VERIFIER_SIZE);
 703                 p = xdr_encode_empty_array(p);
 704                 p = xdr_encode_hyper(p, cp->cp_res.wr_bytes_written);
 705                 *p++ = cpu_to_be32(cp->cp_res.wr_stable_how);
 706                 p = xdr_encode_opaque_fixed(p, cp->cp_res.wr_verifier.data,
 707                                             NFS4_VERIFIER_SIZE);
 708         } else {
 709                 p = xdr_reserve_space(xdr, 8);
 710                 /* We always return success if bytes were written */
 711                 p = xdr_encode_hyper(p, 0);
 712         }
 713 }
 714
 715 static void encode_cb_offload4args(struct xdr_stream *xdr,
 716                                    __be32 nfserr,
 717                                    const struct knfsd_fh *fh,
 718                                    const struct nfsd4_copy *cp,
 719                                    struct nfs4_cb_compound_hdr *hdr)
 720 {
 721         __be32 *p;
 722
 723         p = xdr_reserve_space(xdr, 4);
 724         *p++ = cpu_to_be32(OP_CB_OFFLOAD);
 725         encode_nfs_fh4(xdr, fh);
 726         encode_stateid4(xdr, &cp->cp_res.cb_stateid);
 727         encode_offload_info4(xdr, nfserr, cp);
 728
 729         hdr->nops++;
 730 }
 731
 732 static void nfs4_xdr_enc_cb_offload(struct rpc_rqst *req,
 733                                     struct xdr_stream *xdr,
 734                                     const void *data)
 735 {
 736         const struct nfsd4_callback *cb = data;
 737         const struct nfsd4_copy *cp =
 738                 container_of(cb, struct nfsd4_copy, cp_cb);
 739         struct nfs4_cb_compound_hdr hdr = {
 740                 .ident = 0,
 741                 .minorversion = cb->cb_clp->cl_minorversion,
 742         };
 743
 744         encode_cb_compound4args(xdr, &hdr);
 745         encode_cb_sequence4args(xdr, cb, &hdr);
 746         encode_cb_offload4args(xdr, cp->nfserr, &cp->fh, cp, &hdr);
 747         encode_cb_nops(&hdr);
 748 }
 749
 750 static int nfs4_xdr_dec_cb_offload(struct rpc_rqst *rqstp,
 751                                    struct xdr_stream *xdr,
 752                                    void *data)
 753 {
 754         struct nfsd4_callback *cb = data;
 755         struct nfs4_cb_compound_hdr hdr;
 756         int status;
 757
 758         status = decode_cb_compound4res(xdr, &hdr);
 759         if (unlikely(status))
 760                 return status;
 761
 762         if (cb) {
 763                 status = decode_cb_sequence4res(xdr, cb);
 764                 if (unlikely(status || cb->cb_seq_status))
 765                         return status;
 766         }
 767         return decode_cb_op_status(xdr, OP_CB_OFFLOAD, &cb->cb_status);
 768 }
 769 /*
 770  * RPC procedure tables
 771  */
 772 #define PROC(proc, call, argtype, restype)                              \
 773 [NFSPROC4_CLNT_##proc] = {                                              \
 774         .p_proc    = NFSPROC4_CB_##call,                                \
 775         .p_encode  = nfs4_xdr_enc_##argtype,            \
 776         .p_decode  = nfs4_xdr_dec_##restype,                            \
 777         .p_arglen  = NFS4_enc_##argtype##_sz,                           \
 778         .p_replen  = NFS4_dec_##restype##_sz,                           \
 779         .p_statidx = NFSPROC4_CB_##call,                                \
 780         .p_name    = #proc,                                             \
 781 }
 782
 783 static const struct rpc_procinfo nfs4_cb_procedures[] = {
 784         PROC(CB_NULL,   NULL,           cb_null,        cb_null),
 785         PROC(CB_RECALL, COMPOUND,       cb_recall,      cb_recall),
 786 #ifdef CONFIG_NFSD_PNFS
 787         PROC(CB_LAYOUT, COMPOUND,       cb_layout,      cb_layout),
 788 #endif
 789         PROC(CB_NOTIFY_LOCK,    COMPOUND,       cb_notify_lock, cb_notify_lock),
 790         PROC(CB_OFFLOAD,        COMPOUND,       cb_offload,     cb_offload),
 791 };
 792
 793 static unsigned int nfs4_cb_counts[ARRAY_SIZE(nfs4_cb_procedures)];
 794 static const struct rpc_version nfs_cb_version4 = {
 795 /*
 796  * Note on the callback rpc program version number: despite language in rfc
 797  * 5661 section 18.36.3 requiring servers to use 4 in this field, the
 798  * official xdr descriptions for both 4.0 and 4.1 specify version 1, and
 799  * in practice that appears to be what implementations use.  The section
 800  * 18.36.3 language is expected to be fixed in an erratum.
 801  */
 802         .number                 = 1,
 803         .nrprocs                = ARRAY_SIZE(nfs4_cb_procedures),
 804         .procs                  = nfs4_cb_procedures,
 805         .counts                 = nfs4_cb_counts,
 806 };
 807
 808 static const struct rpc_version *nfs_cb_version[2] = {
 809         [1] = &nfs_cb_version4,
 810 };
 811
 812 static const struct rpc_program cb_program;
 813
 814 static struct rpc_stat cb_stats = {
 815         .program                = &cb_program
 816 };
 817
 818 #define NFS4_CALLBACK 0x40000000
 819 static const struct rpc_program cb_program = {
 820         .name                   = "nfs4_cb",
 821         .number                 = NFS4_CALLBACK,
 822         .nrvers                 = ARRAY_SIZE(nfs_cb_version),
 823         .version                = nfs_cb_version,
 824         .stats                  = &cb_stats,
 825         .pipe_dir_name          = "nfsd4_cb",
 826 };
 827
 828 static int max_cb_time(struct net *net)
 829 {
 830         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 831         return max(nn->nfsd4_lease/10, (time_t)1) * HZ;
 832 }
 833
 834 static const struct cred *get_backchannel_cred(struct nfs4_client *clp, struct rpc_clnt *client, struct nfsd4_session *ses)
 835 {
 836         if (clp->cl_minorversion == 0) {
 837                 client->cl_principal = clp->cl_cred.cr_targ_princ ?
 838                         clp->cl_cred.cr_targ_princ : "nfs";
 839
 840                 return get_cred(rpc_machine_cred());
 841         } else {
 842                 struct cred *kcred;
 843
 844                 kcred = prepare_kernel_cred(NULL);
 845                 if (!kcred)
 846                         return NULL;
 847
 848                 kcred->uid = ses->se_cb_sec.uid;
 849                 kcred->gid = ses->se_cb_sec.gid;
 850                 return kcred;
 851         }
 852 }
 853
 854 static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn, struct nfsd4_session *ses)
 855 {
 856         int maxtime = max_cb_time(clp->net);
 857         struct rpc_timeout      timeparms = {
 858                 .to_initval     = maxtime,
 859                 .to_retries     = 0,
 860                 .to_maxval      = maxtime,
 861         };
 862         struct rpc_create_args args = {
 863                 .net            = clp->net,
 864                 .address        = (struct sockaddr *) &conn->cb_addr,
 865                 .addrsize       = conn->cb_addrlen,
 866                 .saddress       = (struct sockaddr *) &conn->cb_saddr,
 867                 .timeout        = &timeparms,
 868                 .program        = &cb_program,
 869                 .version        = 1,
 870                 .flags          = (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
 871         };
 872         struct rpc_clnt *client;
 873         const struct cred *cred;
 874
 875         if (clp->cl_minorversion == 0) {
 876                 if (!clp->cl_cred.cr_principal &&
 877                                 (clp->cl_cred.cr_flavor >= RPC_AUTH_GSS_KRB5))
 878                         return -EINVAL;
 879                 args.client_name = clp->cl_cred.cr_principal;
 880                 args.prognumber = conn->cb_prog;
 881                 args.protocol = XPRT_TRANSPORT_TCP;
 882                 args.authflavor = clp->cl_cred.cr_flavor;
 883                 clp->cl_cb_ident = conn->cb_ident;
 884         } else {
 885                 if (!conn->cb_xprt)
 886                         return -EINVAL;
 887                 clp->cl_cb_conn.cb_xprt = conn->cb_xprt;
 888                 clp->cl_cb_session = ses;
 889                 args.bc_xprt = conn->cb_xprt;
 890                 args.prognumber = clp->cl_cb_session->se_cb_prog;
 891                 args.protocol = conn->cb_xprt->xpt_class->xcl_ident |
 892                                 XPRT_TRANSPORT_BC;
 893                 args.authflavor = ses->se_cb_sec.flavor;
 894         }
 895         /* Create RPC client */
 896         client = rpc_create(&args);
 897         if (IS_ERR(client)) {
 898                 dprintk("NFSD: couldn't create callback client: %ld\n",
 899                         PTR_ERR(client));
 900                 return PTR_ERR(client);
 901         }
 902         cred = get_backchannel_cred(clp, client, ses);
 903         if (!cred) {
 904                 rpc_shutdown_client(client);
 905                 return -ENOMEM;
 906         }
 907         clp->cl_cb_client = client;
 908         clp->cl_cb_cred = cred;
 909         return 0;
 910 }
 911
 912 static void warn_no_callback_path(struct nfs4_client *clp, int reason)
 913 {
 914         dprintk("NFSD: warning: no callback path to client %.*s: error %d\n",
 915                 (int)clp->cl_name.len, clp->cl_name.data, reason);
 916 }
 917
 918 static void nfsd4_mark_cb_down(struct nfs4_client *clp, int reason)
 919 {
 920         if (test_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags))
 921                 return;
 922         clp->cl_cb_state = NFSD4_CB_DOWN;
 923         warn_no_callback_path(clp, reason);
 924 }
 925
 926 static void nfsd4_mark_cb_fault(struct nfs4_client *clp, int reason)
 927 {
 928         if (test_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags))
 929                 return;
 930         clp->cl_cb_state = NFSD4_CB_FAULT;
 931         warn_no_callback_path(clp, reason);
 932 }
 933
 934 static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 935 {
 936         struct nfs4_client *clp = container_of(calldata, struct nfs4_client, cl_cb_null);
 937
 938         if (task->tk_status)
 939                 nfsd4_mark_cb_down(clp, task->tk_status);
 940         else
 941                 clp->cl_cb_state = NFSD4_CB_UP;
 942 }
 943
 944 static const struct rpc_call_ops nfsd4_cb_probe_ops = {
 945         /* XXX: release method to ensure we set the cb channel down if
 946          * necessary on early failure? */
 947         .rpc_call_done = nfsd4_cb_probe_done,
 948 };
 949
 950 static struct workqueue_struct *callback_wq;
 951
 952 /*
 953  * Poke the callback thread to process any updates to the callback
 954  * parameters, and send a null probe.
 955  */
 956 void nfsd4_probe_callback(struct nfs4_client *clp)
 957 {
 958         clp->cl_cb_state = NFSD4_CB_UNKNOWN;
 959         set_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags);
 960         nfsd4_run_cb(&clp->cl_cb_null);
 961 }
 962
 963 void nfsd4_probe_callback_sync(struct nfs4_client *clp)
 964 {
 965         nfsd4_probe_callback(clp);
 966         flush_workqueue(callback_wq);
 967 }
 968
 969 void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
 970 {
 971         clp->cl_cb_state = NFSD4_CB_UNKNOWN;
 972         spin_lock(&clp->cl_lock);
 973         memcpy(&clp->cl_cb_conn, conn, sizeof(struct nfs4_cb_conn));
 974         spin_unlock(&clp->cl_lock);
 975 }
 976
 977 /*
 978  * There's currently a single callback channel slot.
 979  * If the slot is available, then mark it busy.  Otherwise, set the
 980  * thread for sleeping on the callback RPC wait queue.
 981  */
 982 static bool nfsd41_cb_get_slot(struct nfs4_client *clp, struct rpc_task *task)
 983 {
 984         if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
 985                 rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
 986                 /* Race breaker */
 987                 if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
 988                         dprintk("%s slot is busy\n", __func__);
 989                         return false;
 990                 }
 991                 rpc_wake_up_queued_task(&clp->cl_cb_waitq, task);
 992         }
 993         return true;
 994 }
 995
 996 /*
 997  * TODO: cb_sequence should support referring call lists, cachethis, multiple
 998  * slots, and mark callback channel down on communication errors.
 999  */
1000 static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
1001 {
1002         struct nfsd4_callback *cb = calldata;
1003         struct nfs4_client *clp = cb->cb_clp;
1004         u32 minorversion = clp->cl_minorversion;
1005
1006         /*
1007          * cb_seq_status is only set in decode_cb_sequence4res,
1008          * and so will remain 1 if an rpc level failure occurs.
1009          */
1010         cb->cb_seq_status = 1;
1011         cb->cb_status = 0;
1012         if (minorversion) {
1013                 if (!cb->cb_holds_slot && !nfsd41_cb_get_slot(clp, task))
1014                         return;
1015                 cb->cb_holds_slot = true;
1016         }
1017         rpc_call_start(task);
1018 }
1019
1020 static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback *cb)
1021 {
1022         struct nfs4_client *clp = cb->cb_clp;
1023         struct nfsd4_session *session = clp->cl_cb_session;
1024         bool ret = true;
1025
1026         if (!clp->cl_minorversion) {
1027                 /*
1028                  * If the backchannel connection was shut down while this
1029                  * task was queued, we need to resubmit it after setting up
1030                  * a new backchannel connection.
1031                  *
1032                  * Note that if we lost our callback connection permanently
1033                  * the submission code will error out, so we don't need to
1034                  * handle that case here.
1035                  */
1036                 if (task->tk_flags & RPC_TASK_KILLED)
1037                         goto need_restart;
1038
1039                 return true;
1040         }
1041
1042         if (!cb->cb_holds_slot)
1043                 goto need_restart;
1044
1045         switch (cb->cb_seq_status) {
1046         case 0:
1047                 /*
1048                  * No need for lock, access serialized in nfsd4_cb_prepare
1049                  *
1050                  * RFC5661 20.9.3
1051                  * If CB_SEQUENCE returns an error, then the state of the slot
1052                  * (sequence ID, cached reply) MUST NOT change.
1053                  */
1054                 ++session->se_cb_seq_nr;
1055                 break;
1056         case -ESERVERFAULT:
1057                 ++session->se_cb_seq_nr;
1058                 /* Fall through */
1059         case 1:
1060         case -NFS4ERR_BADSESSION:
1061                 nfsd4_mark_cb_fault(cb->cb_clp, cb->cb_seq_status);
1062                 ret = false;
1063                 break;
1064         case -NFS4ERR_DELAY:
1065                 if (!rpc_restart_call(task))
1066                         goto out;
1067
1068                 rpc_delay(task, 2 * HZ);
1069                 return false;
1070         case -NFS4ERR_BADSLOT:
1071                 goto retry_nowait;
1072         case -NFS4ERR_SEQ_MISORDERED:
1073                 if (session->se_cb_seq_nr != 1) {
1074                         session->se_cb_seq_nr = 1;
1075                         goto retry_nowait;
1076                 }
1077                 break;
1078         default:
1079                 dprintk("%s: unprocessed error %d\n", __func__,
1080                         cb->cb_seq_status);
1081         }
1082
1083         cb->cb_holds_slot = false;
1084         clear_bit(0, &clp->cl_cb_slot_busy);
1085         rpc_wake_up_next(&clp->cl_cb_waitq);
1086         dprintk("%s: freed slot, new seqid=%d\n", __func__,
1087                 clp->cl_cb_session->se_cb_seq_nr);
1088
1089         if (task->tk_flags & RPC_TASK_KILLED)
1090                 goto need_restart;
1091 out:
1092         return ret;
1093 retry_nowait:
1094         if (rpc_restart_call_prepare(task))
1095                 ret = false;
1096         goto out;
1097 need_restart:
1098         task->tk_status = 0;
1099         cb->cb_need_restart = true;
1100         return false;
1101 }
1102
1103 static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
1104 {
1105         struct nfsd4_callback *cb = calldata;
1106         struct nfs4_client *clp = cb->cb_clp;
1107
1108         dprintk("%s: minorversion=%d\n", __func__,
1109                 clp->cl_minorversion);
1110
1111         if (!nfsd4_cb_sequence_done(task, cb))
1112                 return;
1113
1114         if (cb->cb_status) {
1115                 WARN_ON_ONCE(task->tk_status);
1116                 task->tk_status = cb->cb_status;
1117         }
1118
1119         switch (cb->cb_ops->done(cb, task)) {
1120         case 0:
1121                 task->tk_status = 0;
1122                 rpc_restart_call_prepare(task);
1123                 return;
1124         case 1:
1125                 break;
1126         case -1:
1127                 /* Network partition? */
1128                 nfsd4_mark_cb_down(clp, task->tk_status);
1129                 break;
1130         default:
1131                 BUG();
1132         }
1133 }
1134
1135 static void nfsd4_cb_release(void *calldata)
1136 {
1137         struct nfsd4_callback *cb = calldata;
1138
1139         if (cb->cb_need_restart)
1140                 nfsd4_run_cb(cb);
1141         else
1142                 cb->cb_ops->release(cb);
1143
1144 }
1145
1146 static const struct rpc_call_ops nfsd4_cb_ops = {
1147         .rpc_call_prepare = nfsd4_cb_prepare,
1148         .rpc_call_done = nfsd4_cb_done,
1149         .rpc_release = nfsd4_cb_release,
1150 };
1151
1152 int nfsd4_create_callback_queue(void)
1153 {
1154         callback_wq = alloc_ordered_workqueue("nfsd4_callbacks", 0);
1155         if (!callback_wq)
1156                 return -ENOMEM;
1157         return 0;
1158 }
1159
1160 void nfsd4_destroy_callback_queue(void)
1161 {
1162         destroy_workqueue(callback_wq);
1163 }
1164
1165 /* must be called under the state lock */
1166 void nfsd4_shutdown_callback(struct nfs4_client *clp)
1167 {
1168         set_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags);
1169         /*
1170          * Note this won't actually result in a null callback;
1171          * instead, nfsd4_run_cb_null() will detect the killed
1172          * client, destroy the rpc client, and stop:
1173          */
1174         nfsd4_run_cb(&clp->cl_cb_null);
1175         flush_workqueue(callback_wq);
1176 }
1177
1178 /* requires cl_lock: */
1179 static struct nfsd4_conn * __nfsd4_find_backchannel(struct nfs4_client *clp)
1180 {
1181         struct nfsd4_session *s;
1182         struct nfsd4_conn *c;
1183
1184         list_for_each_entry(s, &clp->cl_sessions, se_perclnt) {
1185                 list_for_each_entry(c, &s->se_conns, cn_persession) {
1186                         if (c->cn_flags & NFS4_CDFC4_BACK)
1187                                 return c;
1188                 }
1189         }
1190         return NULL;
1191 }
1192
1193 static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
1194 {
1195         struct nfs4_cb_conn conn;
1196         struct nfs4_client *clp = cb->cb_clp;
1197         struct nfsd4_session *ses = NULL;
1198         struct nfsd4_conn *c;
1199         int err;
1200
1201         /*
1202          * This is either an update, or the client dying; in either case,
1203          * kill the old client:
1204          */
1205         if (clp->cl_cb_client) {
1206                 rpc_shutdown_client(clp->cl_cb_client);
1207                 clp->cl_cb_client = NULL;
1208                 put_cred(clp->cl_cb_cred);
1209                 clp->cl_cb_cred = NULL;
1210         }
1211         if (clp->cl_cb_conn.cb_xprt) {
1212                 svc_xprt_put(clp->cl_cb_conn.cb_xprt);
1213                 clp->cl_cb_conn.cb_xprt = NULL;
1214         }
1215         if (test_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags))
1216                 return;
1217         spin_lock(&clp->cl_lock);
1218         /*
1219          * Only serialized callback code is allowed to clear these
1220          * flags; main nfsd code can only set them:
1221          */
1222         BUG_ON(!(clp->cl_flags & NFSD4_CLIENT_CB_FLAG_MASK));
1223         clear_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags);
1224         memcpy(&conn, &cb->cb_clp->cl_cb_conn, sizeof(struct nfs4_cb_conn));
1225         c = __nfsd4_find_backchannel(clp);
1226         if (c) {
1227                 svc_xprt_get(c->cn_xprt);
1228                 conn.cb_xprt = c->cn_xprt;
1229                 ses = c->cn_session;
1230         }
1231         spin_unlock(&clp->cl_lock);
1232
1233         err = setup_callback_client(clp, &conn, ses);
1234         if (err) {
1235                 nfsd4_mark_cb_down(clp, err);
1236                 return;
1237         }
1238 }
1239
1240 static void
1241 nfsd4_run_cb_work(struct work_struct *work)
1242 {
1243         struct nfsd4_callback *cb =
1244                 container_of(work, struct nfsd4_callback, cb_work);
1245         struct nfs4_client *clp = cb->cb_clp;
1246         struct rpc_clnt *clnt;
1247
1248         if (cb->cb_need_restart) {
1249                 cb->cb_need_restart = false;
1250         } else {
1251                 if (cb->cb_ops && cb->cb_ops->prepare)
1252                         cb->cb_ops->prepare(cb);
1253         }
1254
1255         if (clp->cl_flags & NFSD4_CLIENT_CB_FLAG_MASK)
1256                 nfsd4_process_cb_update(cb);
1257
1258         clnt = clp->cl_cb_client;
1259         if (!clnt) {
1260                 /* Callback channel broken, or client killed; give up: */
1261                 if (cb->cb_ops && cb->cb_ops->release)
1262                         cb->cb_ops->release(cb);
1263                 return;
1264         }
1265
1266         /*
1267          * Don't send probe messages for 4.1 or later.
1268          */
1269         if (!cb->cb_ops && clp->cl_minorversion) {
1270                 clp->cl_cb_state = NFSD4_CB_UP;
1271                 return;
1272         }
1273
1274         cb->cb_msg.rpc_cred = clp->cl_cb_cred;
1275         rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
1276                         cb->cb_ops ? &nfsd4_cb_ops : &nfsd4_cb_probe_ops, cb);
1277 }
1278
1279 void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
1280                 const struct nfsd4_callback_ops *ops, enum nfsd4_cb_op op)
1281 {
1282         cb->cb_clp = clp;
1283         cb->cb_msg.rpc_proc = &nfs4_cb_procedures[op];
1284         cb->cb_msg.rpc_argp = cb;
1285         cb->cb_msg.rpc_resp = cb;
1286         cb->cb_ops = ops;
1287         INIT_WORK(&cb->cb_work, nfsd4_run_cb_work);
1288         cb->cb_seq_status = 1;
1289         cb->cb_status = 0;
1290         cb->cb_need_restart = false;
1291         cb->cb_holds_slot = false;
1292 }
1293
1294 void nfsd4_run_cb(struct nfsd4_callback *cb)
1295 {
1296         queue_work(callback_wq, &cb->cb_work);
1297 }