lustre/mdt/mdt_hsm_cdt_agent.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License version 2 for more details.  A copy is
  14  * included in the COPYING file that accompanied this code.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * (C) Copyright 2012 Commissariat a l'energie atomique et aux energies
  24  *     alternatives
  25  *
  26  */
  27 /*
  28  * lustre/mdt/mdt_hsm_cdt_agent.c
  29  *
  30  * Lustre HSM Coordinator
  31  *
  32  * Author: Jacques-Charles Lafoucriere <jacques-charles.lafoucriere@cea.fr>
  33  * Author: Aurelien Degremont <aurelien.degremont@cea.fr>
  34  */
  35
  36 #define DEBUG_SUBSYSTEM S_MDS
  37
  38 #include <obd.h>
  39 #include <obd_support.h>
  40 #include <lustre_export.h>
  41 #include <lustre/lustre_user.h>
  42 #include <lprocfs_status.h>
  43 #include <lustre_kernelcomm.h>
  44 #include "mdt_internal.h"
  45
  46 /*
  47  * Agent external API
  48  */
  49
  50 /*
  51  * find a hsm_agent by uuid
  52  * lock cdt_agent_lock needs to be held by caller
  53  * \param cdt [IN] coordinator
  54  * \param uuid [IN] agent UUID
  55  * \retval hsm_agent pointer or NULL if not found
  56  */
  57 static struct hsm_agent *mdt_hsm_agent_lookup(struct coordinator *cdt,
  58                                               const struct obd_uuid *uuid)
  59 {
  60         struct hsm_agent        *ha;
  61
  62         list_for_each_entry(ha, &cdt->cdt_agents, ha_list) {
  63                 if (obd_uuid_equals(&ha->ha_uuid, uuid))
  64                         return ha;
  65         }
  66         return NULL;
  67 }
  68
  69 /**
  70  * register a copy tool
  71  * \param mti [IN] MDT context
  72  * \param uuid [IN] client UUID to be registered
  73  * \param count [IN] number of archives agent serves
  74  * \param archive_id [IN] vector of archive number served by the copytool
  75  * \retval 0 success
  76  * \retval -ve failure
  77  */
  78 int mdt_hsm_agent_register(struct mdt_thread_info *mti,
  79                            const struct obd_uuid *uuid,
  80                            int nr_archives, __u32 *archive_id)
  81 {
  82         struct coordinator      *cdt = &mti->mti_mdt->mdt_coordinator;
  83         struct hsm_agent        *ha, *tmp;
  84         int                      rc;
  85         ENTRY;
  86
  87         /* no coordinator started, so we cannot serve requests */
  88         if (cdt->cdt_state == CDT_STOPPED) {
  89                 LCONSOLE_WARN("HSM coordinator thread is not running - "
  90                               "denying agent registration.\n");
  91                 RETURN(-ENXIO);
  92         }
  93
  94         OBD_ALLOC_PTR(ha);
  95         if (ha == NULL)
  96                 GOTO(out, rc = -ENOMEM);
  97
  98         ha->ha_uuid = *uuid;
  99         ha->ha_archive_cnt = nr_archives;
 100         if (ha->ha_archive_cnt != 0) {
 101                 int sz;
 102
 103                 sz = ha->ha_archive_cnt * sizeof(*ha->ha_archive_id);
 104                 OBD_ALLOC(ha->ha_archive_id, sz);
 105                 if (ha->ha_archive_id == NULL)
 106                         GOTO(out_free, rc = -ENOMEM);
 107                 memcpy(ha->ha_archive_id, archive_id, sz);
 108         }
 109         atomic_set(&ha->ha_requests, 0);
 110         atomic_set(&ha->ha_success, 0);
 111         atomic_set(&ha->ha_failure, 0);
 112
 113         down_write(&cdt->cdt_agent_lock);
 114         tmp = mdt_hsm_agent_lookup(cdt, uuid);
 115         if (tmp != NULL) {
 116                 LCONSOLE_WARN("HSM agent %s already registered\n",
 117                               obd_uuid2str(uuid));
 118                 up_write(&cdt->cdt_agent_lock);
 119                 GOTO(out_free, rc = -EEXIST);
 120         }
 121
 122         list_add_tail(&ha->ha_list, &cdt->cdt_agents);
 123
 124         if (ha->ha_archive_cnt == 0)
 125                 CDEBUG(D_HSM, "agent %s registered for all archives\n",
 126                        obd_uuid2str(&ha->ha_uuid));
 127         else
 128                 CDEBUG(D_HSM, "agent %s registered for %d archives\n",
 129                        obd_uuid2str(&ha->ha_uuid), ha->ha_archive_cnt);
 130
 131         up_write(&cdt->cdt_agent_lock);
 132         GOTO(out, rc = 0);
 133
 134 out_free:
 135
 136         if (ha != NULL && ha->ha_archive_id != NULL)
 137                 OBD_FREE(ha->ha_archive_id,
 138                          ha->ha_archive_cnt * sizeof(*ha->ha_archive_id));
 139         if (ha != NULL)
 140                 OBD_FREE_PTR(ha);
 141 out:
 142         return rc;
 143 }
 144
 145 /**
 146  * register a copy tool
 147  * \param mti [IN] MDT context
 148  * \param uuid [IN] uuid to be registered
 149  * \param archive_mask [IN] bitmask of archive number served by the copytool
 150  * \retval 0 success
 151  * \retval -ve failure
 152  */
 153 int mdt_hsm_agent_register_mask(struct mdt_thread_info *mti,
 154                                 const struct obd_uuid *uuid, __u32 archive_mask)
 155 {
 156         int              rc, i, nr_archives = 0;
 157         __u32           *archive_id = NULL;
 158         ENTRY;
 159
 160         nr_archives = hweight32(archive_mask);
 161
 162         if (nr_archives != 0) {
 163                 OBD_ALLOC(archive_id, nr_archives * sizeof(*archive_id));
 164                 if (!archive_id)
 165                         RETURN(-ENOMEM);
 166
 167                 nr_archives = 0;
 168                 for (i = 0; i < sizeof(archive_mask) * 8; i++) {
 169                         if ((1 << i) & archive_mask) {
 170                                 archive_id[nr_archives] = i + 1;
 171                                 nr_archives++;
 172                         }
 173                 }
 174         }
 175
 176         rc = mdt_hsm_agent_register(mti, uuid, nr_archives, archive_id);
 177
 178         if (archive_id != NULL)
 179                 OBD_FREE(archive_id, nr_archives * sizeof(*archive_id));
 180
 181         RETURN(rc);
 182 }
 183
 184 /**
 185  * unregister a copy tool
 186  * \param mti [IN] MDT context
 187  * \param uuid [IN] uuid to be unregistered
 188  * \retval 0 success
 189  * \retval -ve failure
 190  */
 191 int mdt_hsm_agent_unregister(struct mdt_thread_info *mti,
 192                              const struct obd_uuid *uuid)
 193 {
 194         struct coordinator      *cdt = &mti->mti_mdt->mdt_coordinator;
 195         struct hsm_agent        *ha;
 196         int                      rc;
 197         ENTRY;
 198
 199         /* no coordinator started, so we cannot serve requests */
 200         if (cdt->cdt_state == CDT_STOPPED)
 201                 RETURN(-ENXIO);
 202
 203         down_write(&cdt->cdt_agent_lock);
 204
 205         ha = mdt_hsm_agent_lookup(cdt, uuid);
 206         if (ha != NULL)
 207                 list_del_init(&ha->ha_list);
 208
 209         up_write(&cdt->cdt_agent_lock);
 210
 211         if (ha == NULL)
 212                 GOTO(out, rc = -ENOENT);
 213
 214         if (ha->ha_archive_cnt != 0)
 215                 OBD_FREE(ha->ha_archive_id,
 216                          ha->ha_archive_cnt * sizeof(*ha->ha_archive_id));
 217         OBD_FREE_PTR(ha);
 218
 219         GOTO(out, rc = 0);
 220 out:
 221         CDEBUG(D_HSM, "agent %s unregistration: %d\n", obd_uuid2str(uuid), rc);
 222
 223         return rc;
 224 }
 225
 226 /**
 227  * update agent statistics
 228  * \param mdt [IN] MDT device
 229  * \param succ_rq [IN] number of success
 230  * \param fail_rq [IN] number of failure
 231  * \param new_rq [IN] number of new requests
 232  * \param uuid [IN] agent uuid
 233  * if all counters == 0, clear counters
 234  * \retval 0 success
 235  * \retval -ve failure
 236  */
 237 int mdt_hsm_agent_update_statistics(struct coordinator *cdt,
 238                                     int succ_rq, int fail_rq, int new_rq,
 239                                     const struct obd_uuid *uuid)
 240 {
 241         struct hsm_agent        *ha;
 242         int                      rc;
 243         ENTRY;
 244
 245         down_read(&cdt->cdt_agent_lock);
 246         list_for_each_entry(ha, &cdt->cdt_agents, ha_list) {
 247                 if (obd_uuid_equals(&ha->ha_uuid, uuid)) {
 248                         if (succ_rq == 0 && fail_rq == 0 && new_rq == 0) {
 249                                 atomic_set(&ha->ha_success, 0);
 250                                 atomic_set(&ha->ha_failure, 0);
 251                                 atomic_set(&ha->ha_requests, 0);
 252                         } else {
 253                                 atomic_add(succ_rq, &ha->ha_success);
 254                                 atomic_add(fail_rq, &ha->ha_failure);
 255                                 atomic_add(new_rq, &ha->ha_requests);
 256                                 atomic_sub(succ_rq, &ha->ha_requests);
 257                                 atomic_sub(fail_rq, &ha->ha_requests);
 258                         }
 259                         GOTO(out, rc = 0);
 260                 }
 261
 262         }
 263         rc = -ENOENT;
 264 out:
 265         up_read(&cdt->cdt_agent_lock);
 266         RETURN(rc);
 267 }
 268
 269 /**
 270  * find the best agent
 271  * \param cdt [IN] coordinator
 272  * \param archive [IN] archive number
 273  * \param uuid [OUT] agent who can serve archive
 274  * \retval 0 success
 275  * \retval -ve failure
 276  */
 277 int mdt_hsm_find_best_agent(struct coordinator *cdt, __u32 archive,
 278                             struct obd_uuid *uuid)
 279 {
 280         int                      rc = -EAGAIN, i, load = -1;
 281         struct hsm_agent        *ha;
 282         ENTRY;
 283
 284         /* Choose an export to send a copytool req to */
 285         down_read(&cdt->cdt_agent_lock);
 286         list_for_each_entry(ha, &cdt->cdt_agents, ha_list) {
 287                 for (i = 0; (i < ha->ha_archive_cnt) &&
 288                               (ha->ha_archive_id[i] != archive); i++) {
 289                         /* nothing to do, just skip unmatching records */
 290                 }
 291
 292                 /* archive count == 0 means copy tool serves any backend */
 293                 if (ha->ha_archive_cnt != 0 && i == ha->ha_archive_cnt)
 294                         continue;
 295
 296                 if (load == -1 || load > atomic_read(&ha->ha_requests)) {
 297                         load = atomic_read(&ha->ha_requests);
 298                         *uuid = ha->ha_uuid;
 299                         rc = 0;
 300                 }
 301                 if (atomic_read(&ha->ha_requests) == 0)
 302                         break;
 303         }
 304         up_read(&cdt->cdt_agent_lock);
 305
 306         RETURN(rc);
 307 }
 308
 309 /**
 310  * send a compound request to the agent
 311  * \param mti [IN] context
 312  * \param hal [IN] request (can be a kuc payload)
 313  * \param purge [IN] purge mode (no record)
 314  * \retval 0 success
 315  * \retval -ve failure
 316  * This function supposes:
 317  *  - all actions are for the same archive number
 318  *  - in case of cancel, all cancel are for the same agent
 319  * This implies that request split has to be done
 320  *  before when building the hal
 321  */
 322 int mdt_hsm_agent_send(struct mdt_thread_info *mti,
 323                        struct hsm_action_list *hal, bool purge)
 324 {
 325         struct obd_export       *exp;
 326         struct mdt_device       *mdt = mti->mti_mdt;
 327         struct coordinator      *cdt = &mti->mti_mdt->mdt_coordinator;
 328         struct hsm_action_list  *buf = NULL;
 329         struct hsm_action_item  *hai;
 330         struct obd_uuid          uuid;
 331         int                      len, i, rc = 0;
 332         bool                     fail_request;
 333         bool                     is_registered = false;
 334         ENTRY;
 335
 336         rc = mdt_hsm_find_best_agent(cdt, hal->hal_archive_id, &uuid);
 337         if (rc) {
 338                 CERROR("%s: Cannot find agent for archive %d: rc = %d\n",
 339                        mdt_obd_name(mdt), hal->hal_archive_id, rc);
 340                 RETURN(rc);
 341         }
 342
 343         CDEBUG(D_HSM, "Agent %s selected for archive %d\n", obd_uuid2str(&uuid),
 344                hal->hal_archive_id);
 345
 346         len = hal_size(hal);
 347         buf = kuc_alloc(len, KUC_TRANSPORT_HSM, HMT_ACTION_LIST);
 348         if (IS_ERR(buf))
 349                 RETURN(PTR_ERR(buf));
 350         memcpy(buf, hal, len);
 351
 352         /* Check if request is still valid (cf file hsm flags) */
 353         fail_request = false;
 354         hai = hai_first(hal);
 355         for (i = 0; i < hal->hal_count; i++, hai = hai_next(hai)) {
 356                 if (hai->hai_action != HSMA_CANCEL) {
 357                         struct mdt_object *obj;
 358                         struct md_hsm hsm;
 359
 360                         obj = mdt_hsm_get_md_hsm(mti, &hai->hai_fid, &hsm);
 361                         if (!IS_ERR(obj) && obj != NULL) {
 362                                 mdt_object_put(mti->mti_env, obj);
 363                         } else {
 364                                 if (hai->hai_action == HSMA_REMOVE)
 365                                         continue;
 366
 367                                 if (obj == NULL) {
 368                                         fail_request = true;
 369                                         rc = mdt_agent_record_update(
 370                                                              mti->mti_env, mdt,
 371                                                              &hai->hai_cookie,
 372                                                              1, ARS_FAILED);
 373                                         if (rc) {
 374                                                 CERROR(
 375                                               "%s: mdt_agent_record_update() "
 376                                               "failed, cannot update "
 377                                               "status to %s for cookie "
 378                                               LPX64": rc = %d\n",
 379                                               mdt_obd_name(mdt),
 380                                               agent_req_status2name(ARS_FAILED),
 381                                               hai->hai_cookie, rc);
 382                                                 GOTO(out_buf, rc);
 383                                         }
 384                                         continue;
 385                                 }
 386                                 GOTO(out_buf, rc = PTR_ERR(obj));
 387                         }
 388
 389                         if (!mdt_hsm_is_action_compat(hai, hal->hal_archive_id,
 390                                                       hal->hal_flags, &hsm)) {
 391                                 /* incompatible request, we abort the request */
 392                                 /* next time coordinator will wake up, it will
 393                                  * make the same compound with valid only
 394                                  * records */
 395                                 fail_request = true;
 396                                 rc = mdt_agent_record_update(mti->mti_env, mdt,
 397                                                              &hai->hai_cookie,
 398                                                              1, ARS_FAILED);
 399                                 if (rc) {
 400                                         CERROR("%s: mdt_agent_record_update() "
 401                                               "failed, cannot update "
 402                                               "status to %s for cookie "
 403                                               LPX64": rc = %d\n",
 404                                               mdt_obd_name(mdt),
 405                                               agent_req_status2name(ARS_FAILED),
 406                                               hai->hai_cookie, rc);
 407                                         GOTO(out_buf, rc);
 408                                 }
 409
 410                                 /* if restore and record status updated, give
 411                                  * back granted layout lock */
 412                                 if (hai->hai_action == HSMA_RESTORE) {
 413                                         struct cdt_restore_handle *crh = NULL;
 414                                         struct mdt_object *obj = NULL;
 415
 416                                         mutex_lock(&cdt->cdt_restore_lock);
 417                                         crh = mdt_hsm_restore_hdl_find(cdt,
 418                                                                 &hai->hai_fid);
 419                                         if (crh != NULL)
 420                                                 list_del(&crh->crh_list);
 421                                         mutex_unlock(&cdt->cdt_restore_lock);
 422                                         obj = mdt_object_find(mti->mti_env,
 423                                                               mti->mti_mdt,
 424                                                               &hai->hai_fid);
 425                                         if (!IS_ERR(obj) && crh != NULL)
 426                                                 mdt_object_unlock(mti, obj,
 427                                                                   &crh->crh_lh,
 428                                                                   1);
 429                                         if (crh != NULL)
 430                                                 OBD_SLAB_FREE_PTR(crh,
 431                                                         mdt_hsm_cdt_kmem);
 432                                         if (!IS_ERR(obj))
 433                                                 mdt_object_put(mti->mti_env,
 434                                                                obj);
 435                                 }
 436                         }
 437                 }
 438         }
 439
 440         /* we found incompatible requests, so the compound cannot be send
 441          * as is. Bad records have been invalidated in llog.
 442          * Valid one will be reschedule next time coordinator will wake up
 443          * So no need the rebuild a full valid compound request now
 444          */
 445         if (fail_request)
 446                 GOTO(out_buf, rc = 0);
 447
 448         /* Cancel memory registration is useless for purge
 449          * non registration avoid a deadlock :
 450          * in case of failure we have to take the write lock
 451          * to remove entry which conflict with the read loack needed
 452          * by purge
 453          */
 454         if (!purge) {
 455                 /* set is_registered even if failure because we may have
 456                  * partial work done */
 457                 is_registered = true;
 458                 rc = mdt_hsm_add_hal(mti, hal, &uuid);
 459                 if (rc)
 460                         GOTO(out_buf, rc);
 461         }
 462
 463         /* Uses the ldlm reverse import; this rpc will be seen by
 464          *  the ldlm_callback_handler. Note this sends a request RPC
 465          * from a server (MDT) to a client (MDC), backwards of normal comms.
 466          */
 467         exp = cfs_hash_lookup(mdt2obd_dev(mdt)->obd_uuid_hash, &uuid);
 468         if (exp == NULL || exp->exp_disconnected) {
 469                 /* This should clean up agents on evicted exports */
 470                 rc = -ENOENT;
 471                 CERROR("%s: agent uuid (%s) not found, unregistering:"
 472                        " rc = %d\n",
 473                        mdt_obd_name(mdt), obd_uuid2str(&uuid), rc);
 474                 mdt_hsm_agent_unregister(mti, &uuid);
 475                 GOTO(out, rc);
 476         }
 477
 478         /* send request to agent */
 479         rc = do_set_info_async(exp->exp_imp_reverse, LDLM_SET_INFO,
 480                                LUSTRE_OBD_VERSION,
 481                                sizeof(KEY_HSM_COPYTOOL_SEND),
 482                                KEY_HSM_COPYTOOL_SEND,
 483                                kuc_len(len), kuc_ptr(buf), NULL);
 484
 485         if (rc)
 486                 CERROR("%s: cannot send request to agent '%s': rc = %d\n",
 487                        mdt_obd_name(mdt), obd_uuid2str(&uuid), rc);
 488
 489         class_export_put(exp);
 490
 491         if (rc == -EPIPE) {
 492                 CDEBUG(D_HSM, "Lost connection to agent '%s', unregistering\n",
 493                        obd_uuid2str(&uuid));
 494                 mdt_hsm_agent_unregister(mti, &uuid);
 495         }
 496
 497 out:
 498         if (rc != 0 && is_registered) {
 499                 /* in case of error, we have to unregister requests */
 500                 hai = hai_first(hal);
 501                 for (i = 0; i < hal->hal_count; i++, hai = hai_next(hai)) {
 502                         if (hai->hai_action == HSMA_CANCEL)
 503                                 continue;
 504                         mdt_cdt_remove_request(cdt, hai->hai_cookie);
 505                 }
 506         }
 507
 508 out_buf:
 509         kuc_free(buf, len);
 510
 511         RETURN(rc);
 512 }
 513
 514 /**
 515  * update status of a request
 516  * \param mti [IN]
 517  * \param pgs [IN] progress of the copy tool
 518  * \retval 0 success
 519  * \retval -ve failure
 520  */
 521 int mdt_hsm_coordinator_update(struct mdt_thread_info *mti,
 522                                struct hsm_progress_kernel *pgs)
 523 {
 524         int      rc;
 525
 526         ENTRY;
 527         /* ask to coordinator to update request state and
 528          * to record on disk the result */
 529         rc = mdt_hsm_update_request_state(mti, pgs, 1);
 530         RETURN(rc);
 531 }
 532
 533 /**
 534  * seq_file method called to start access to /proc file
 535  */
 536 static void *mdt_hsm_agent_proc_start(struct seq_file *s, loff_t *off)
 537 {
 538         struct mdt_device       *mdt = s->private;
 539         struct coordinator      *cdt = &mdt->mdt_coordinator;
 540         struct list_head        *pos;
 541         loff_t                   i;
 542         ENTRY;
 543
 544         down_read(&cdt->cdt_agent_lock);
 545
 546         if (list_empty(&cdt->cdt_agents))
 547                 RETURN(NULL);
 548
 549         if (*off == 0)
 550                 RETURN(SEQ_START_TOKEN);
 551
 552         i = 0;
 553         list_for_each(pos, &cdt->cdt_agents) {
 554                 i++;
 555                 if (i >= *off)
 556                         RETURN(pos);
 557         }
 558
 559         RETURN(NULL);
 560 }
 561
 562 /**
 563  * seq_file method called to get next item
 564  * just returns NULL at eof
 565  */
 566 static void *mdt_hsm_agent_proc_next(struct seq_file *s, void *v, loff_t *p)
 567 {
 568         struct mdt_device       *mdt = s->private;
 569         struct coordinator      *cdt = &mdt->mdt_coordinator;
 570         struct list_head        *pos = v;
 571         ENTRY;
 572
 573         if (pos == SEQ_START_TOKEN)
 574                 pos = cdt->cdt_agents.next;
 575         else
 576                 pos = pos->next;
 577
 578         (*p)++;
 579         if (pos != &cdt->cdt_agents)
 580                 RETURN(pos);
 581
 582         RETURN(NULL);
 583 }
 584
 585 /**
 586  */
 587 static int mdt_hsm_agent_proc_show(struct seq_file *s, void *v)
 588 {
 589         struct list_head        *pos = v;
 590         struct hsm_agent        *ha;
 591         int                      i;
 592         ENTRY;
 593
 594         if (pos == SEQ_START_TOKEN)
 595                 RETURN(0);
 596
 597         ha = list_entry(pos, struct hsm_agent, ha_list);
 598         seq_printf(s, "uuid=%s archive_id=", ha->ha_uuid.uuid);
 599         if (ha->ha_archive_cnt == 0) {
 600                 seq_printf(s, "ANY");
 601         } else {
 602                 seq_printf(s, "%d", ha->ha_archive_id[0]);
 603                 for (i = 1; i < ha->ha_archive_cnt; i++)
 604                         seq_printf(s, ",%d", ha->ha_archive_id[i]);
 605         }
 606
 607         seq_printf(s, " requests=[current:%d ok:%d errors:%d]\n",
 608                    atomic_read(&ha->ha_requests),
 609                    atomic_read(&ha->ha_success),
 610                    atomic_read(&ha->ha_failure));
 611         RETURN(0);
 612 }
 613
 614 /**
 615  * seq_file method called to stop access to /proc file
 616  */
 617 static void mdt_hsm_agent_proc_stop(struct seq_file *s, void *v)
 618 {
 619         struct mdt_device       *mdt = s->private;
 620         struct coordinator      *cdt = &mdt->mdt_coordinator;
 621
 622         up_read(&cdt->cdt_agent_lock);
 623 }
 624
 625 /* hsm agent list proc functions */
 626 static const struct seq_operations mdt_hsm_agent_proc_ops = {
 627         .start  = mdt_hsm_agent_proc_start,
 628         .next   = mdt_hsm_agent_proc_next,
 629         .show   = mdt_hsm_agent_proc_show,
 630         .stop   = mdt_hsm_agent_proc_stop,
 631 };
 632
 633 /**
 634  * public function called at open of /proc file to get
 635  * list of agents
 636  */
 637 static int lprocfs_open_hsm_agent(struct inode *inode, struct file *file)
 638 {
 639         struct seq_file *s;
 640         int              rc;
 641         ENTRY;
 642
 643         rc = seq_open(file, &mdt_hsm_agent_proc_ops);
 644         if (rc)
 645                 RETURN(rc);
 646
 647         s = file->private_data;
 648         s->private = PDE_DATA(inode);
 649
 650         RETURN(rc);
 651 }
 652
 653 /* methods to access hsm agent list */
 654 const struct file_operations mdt_hsm_agent_fops = {
 655         .owner          = THIS_MODULE,
 656         .open           = lprocfs_open_hsm_agent,
 657         .read           = seq_read,
 658         .llseek         = seq_lseek,
 659         .release        = lprocfs_seq_release,
 660 };
 661