lustre/mdt/mdt_mds.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  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2013, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  *
  31  * lustre/mdt/mdt_mds.c
  32  *
  33  * Lustre Metadata Service Layer
  34  *
  35  * Author: Di Wang <di.wang@whamcloud.com>
  36  **/
  37
  38 #define DEBUG_SUBSYSTEM S_MDS
  39
  40 #include <linux/module.h>
  41
  42 #include <obd_support.h>
  43 /* struct ptlrpc_request */
  44 #include <lustre_net.h>
  45 /* struct obd_export */
  46 #include <lustre_export.h>
  47 /* struct obd_device */
  48 #include <obd.h>
  49 /* lu2dt_dev() */
  50 #include <dt_object.h>
  51 #include <lustre_mds.h>
  52 #include "mdt_internal.h"
  53 #include <lustre_quota.h>
  54 #include <lustre_acl.h>
  55 #include <lustre_param.h>
  56
  57 struct mds_device {
  58         /* super-class */
  59         struct md_device           mds_md_dev;
  60         struct ptlrpc_service     *mds_regular_service;
  61         struct ptlrpc_service     *mds_readpage_service;
  62         struct ptlrpc_service     *mds_out_service;
  63         struct ptlrpc_service     *mds_setattr_service;
  64         struct ptlrpc_service     *mds_mdsc_service;
  65         struct ptlrpc_service     *mds_mdss_service;
  66         struct ptlrpc_service     *mds_fld_service;
  67 };
  68
  69 /*
  70  *  * Initialized in mdt_mod_init().
  71  *   */
  72 static unsigned long mdt_num_threads;
  73 CFS_MODULE_PARM(mdt_num_threads, "ul", ulong, 0444,
  74                 "number of MDS service threads to start "
  75                 "(deprecated in favor of mds_num_threads)");
  76
  77 static unsigned long mds_num_threads;
  78 CFS_MODULE_PARM(mds_num_threads, "ul", ulong, 0444,
  79                 "number of MDS service threads to start");
  80
  81 static char *mds_num_cpts;
  82 CFS_MODULE_PARM(mds_num_cpts, "c", charp, 0444,
  83                 "CPU partitions MDS threads should run on");
  84
  85 static unsigned long mds_rdpg_num_threads;
  86 CFS_MODULE_PARM(mds_rdpg_num_threads, "ul", ulong, 0444,
  87                 "number of MDS readpage service threads to start");
  88
  89 static char *mds_rdpg_num_cpts;
  90 CFS_MODULE_PARM(mds_rdpg_num_cpts, "c", charp, 0444,
  91                 "CPU partitions MDS readpage threads should run on");
  92
  93 /* NB: these two should be removed along with setattr service in the future */
  94 static unsigned long mds_attr_num_threads;
  95 CFS_MODULE_PARM(mds_attr_num_threads, "ul", ulong, 0444,
  96                 "number of MDS setattr service threads to start");
  97
  98 static char *mds_attr_num_cpts;
  99 CFS_MODULE_PARM(mds_attr_num_cpts, "c", charp, 0444,
 100                 "CPU partitions MDS setattr threads should run on");
 101
 102 /* device init/fini methods */
 103 static void mds_stop_ptlrpc_service(struct mds_device *m)
 104 {
 105         ENTRY;
 106         if (m->mds_regular_service != NULL) {
 107                 ptlrpc_unregister_service(m->mds_regular_service);
 108                 m->mds_regular_service = NULL;
 109         }
 110         if (m->mds_readpage_service != NULL) {
 111                 ptlrpc_unregister_service(m->mds_readpage_service);
 112                 m->mds_readpage_service = NULL;
 113         }
 114         if (m->mds_out_service != NULL) {
 115                 ptlrpc_unregister_service(m->mds_out_service);
 116                 m->mds_out_service = NULL;
 117         }
 118         if (m->mds_setattr_service != NULL) {
 119                 ptlrpc_unregister_service(m->mds_setattr_service);
 120                 m->mds_setattr_service = NULL;
 121         }
 122         if (m->mds_mdsc_service != NULL) {
 123                 ptlrpc_unregister_service(m->mds_mdsc_service);
 124                 m->mds_mdsc_service = NULL;
 125         }
 126         if (m->mds_mdss_service != NULL) {
 127                 ptlrpc_unregister_service(m->mds_mdss_service);
 128                 m->mds_mdss_service = NULL;
 129         }
 130         if (m->mds_fld_service != NULL) {
 131                 ptlrpc_unregister_service(m->mds_fld_service);
 132                 m->mds_fld_service = NULL;
 133         }
 134         EXIT;
 135 }
 136
 137 static int mds_start_ptlrpc_service(struct mds_device *m)
 138 {
 139         static struct ptlrpc_service_conf conf;
 140         struct obd_device *obd = m->mds_md_dev.md_lu_dev.ld_obd;
 141         struct proc_dir_entry *procfs_entry;
 142         int rc = 0;
 143         ENTRY;
 144
 145         procfs_entry = obd->obd_proc_entry;
 146         LASSERT(procfs_entry != NULL);
 147
 148         conf = (typeof(conf)) {
 149                 .psc_name               = LUSTRE_MDT_NAME,
 150                 .psc_watchdog_factor    = MDT_SERVICE_WATCHDOG_FACTOR,
 151                 .psc_buf                = {
 152                         .bc_nbufs               = MDS_NBUFS,
 153                         .bc_buf_size            = MDS_REG_BUFSIZE,
 154                         .bc_req_max_size        = MDS_REG_MAXREQSIZE,
 155                         .bc_rep_max_size        = MDS_REG_MAXREPSIZE,
 156                         .bc_req_portal          = MDS_REQUEST_PORTAL,
 157                         .bc_rep_portal          = MDC_REPLY_PORTAL,
 158                 },
 159                 /*
 160                  * We'd like to have a mechanism to set this on a per-device
 161                  * basis, but alas...
 162                  */
 163                 .psc_thr                = {
 164                         .tc_thr_name            = LUSTRE_MDT_NAME,
 165                         .tc_thr_factor          = MDS_THR_FACTOR,
 166                         .tc_nthrs_init          = MDS_NTHRS_INIT,
 167                         .tc_nthrs_base          = MDS_NTHRS_BASE,
 168                         .tc_nthrs_max           = MDS_NTHRS_MAX,
 169                         .tc_nthrs_user          = mds_num_threads,
 170                         .tc_cpu_affinity        = 1,
 171                         .tc_ctx_tags            = LCT_MD_THREAD,
 172                 },
 173                 .psc_cpt                = {
 174                         .cc_pattern             = mds_num_cpts,
 175                 },
 176                 .psc_ops                = {
 177                         .so_req_handler         = tgt_request_handle,
 178                         .so_req_printer         = target_print_req,
 179                         .so_hpreq_handler       = ptlrpc_hpreq_handler,
 180                 },
 181         };
 182         m->mds_regular_service = ptlrpc_register_service(&conf, procfs_entry);
 183         if (IS_ERR(m->mds_regular_service)) {
 184                 rc = PTR_ERR(m->mds_regular_service);
 185                 CERROR("failed to start regular mdt service: %d\n", rc);
 186                 m->mds_regular_service = NULL;
 187
 188                 RETURN(rc);
 189         }
 190
 191         /*
 192          * readpage service configuration. Parameters have to be adjusted,
 193          * ideally.
 194          */
 195         memset(&conf, 0, sizeof(conf));
 196         conf = (typeof(conf)) {
 197                 .psc_name               = LUSTRE_MDT_NAME "_readpage",
 198                 .psc_watchdog_factor    = MDT_SERVICE_WATCHDOG_FACTOR,
 199                 .psc_buf                = {
 200                         .bc_nbufs               = MDS_NBUFS,
 201                         .bc_buf_size            = MDS_BUFSIZE,
 202                         .bc_req_max_size        = MDS_MAXREQSIZE,
 203                         .bc_rep_max_size        = MDS_MAXREPSIZE,
 204                         .bc_req_portal          = MDS_READPAGE_PORTAL,
 205                         .bc_rep_portal          = MDC_REPLY_PORTAL,
 206                 },
 207                 .psc_thr                = {
 208                         .tc_thr_name            = LUSTRE_MDT_NAME "_rdpg",
 209                         .tc_thr_factor          = MDS_RDPG_THR_FACTOR,
 210                         .tc_nthrs_init          = MDS_RDPG_NTHRS_INIT,
 211                         .tc_nthrs_base          = MDS_RDPG_NTHRS_BASE,
 212                         .tc_nthrs_max           = MDS_RDPG_NTHRS_MAX,
 213                         .tc_nthrs_user          = mds_rdpg_num_threads,
 214                         .tc_cpu_affinity        = 1,
 215                         .tc_ctx_tags            = LCT_MD_THREAD,
 216                 },
 217                 .psc_cpt                = {
 218                         .cc_pattern             = mds_rdpg_num_cpts,
 219                 },
 220                 .psc_ops                = {
 221                         .so_req_handler         = tgt_request_handle,
 222                         .so_req_printer         = target_print_req,
 223                 },
 224         };
 225         m->mds_readpage_service = ptlrpc_register_service(&conf, procfs_entry);
 226         if (IS_ERR(m->mds_readpage_service)) {
 227                 rc = PTR_ERR(m->mds_readpage_service);
 228                 CERROR("failed to start readpage service: %d\n", rc);
 229                 m->mds_readpage_service = NULL;
 230
 231                 GOTO(err_mds_svc, rc);
 232         }
 233
 234         /*
 235          * setattr service configuration.
 236          *
 237          * XXX To keep the compatibility with old client(< 2.2), we need to
 238          * preserve this portal for a certain time, it should be removed
 239          * eventually. LU-617.
 240          */
 241         memset(&conf, 0, sizeof(conf));
 242         conf = (typeof(conf)) {
 243                 .psc_name               = LUSTRE_MDT_NAME "_setattr",
 244                 .psc_watchdog_factor    = MDT_SERVICE_WATCHDOG_FACTOR,
 245                 .psc_buf                = {
 246                         .bc_nbufs               = MDS_NBUFS,
 247                         .bc_buf_size            = MDS_BUFSIZE,
 248                         .bc_req_max_size        = MDS_MAXREQSIZE,
 249                         .bc_rep_max_size        = MDS_LOV_MAXREPSIZE,
 250                         .bc_req_portal          = MDS_SETATTR_PORTAL,
 251                         .bc_rep_portal          = MDC_REPLY_PORTAL,
 252                 },
 253                 .psc_thr                = {
 254                         .tc_thr_name            = LUSTRE_MDT_NAME "_attr",
 255                         .tc_thr_factor          = MDS_SETA_THR_FACTOR,
 256                         .tc_nthrs_init          = MDS_SETA_NTHRS_INIT,
 257                         .tc_nthrs_base          = MDS_SETA_NTHRS_BASE,
 258                         .tc_nthrs_max           = MDS_SETA_NTHRS_MAX,
 259                         .tc_nthrs_user          = mds_attr_num_threads,
 260                         .tc_cpu_affinity        = 1,
 261                         .tc_ctx_tags            = LCT_MD_THREAD,
 262                 },
 263                 .psc_cpt                = {
 264                         .cc_pattern             = mds_attr_num_cpts,
 265                 },
 266                 .psc_ops                = {
 267                         .so_req_handler         = tgt_request_handle,
 268                         .so_req_printer         = target_print_req,
 269                         .so_hpreq_handler       = NULL,
 270                 },
 271         };
 272         m->mds_setattr_service = ptlrpc_register_service(&conf, procfs_entry);
 273         if (IS_ERR(m->mds_setattr_service)) {
 274                 rc = PTR_ERR(m->mds_setattr_service);
 275                 CERROR("failed to start setattr service: %d\n", rc);
 276                 m->mds_setattr_service = NULL;
 277
 278                 GOTO(err_mds_svc, rc);
 279         }
 280
 281         /* Object update service */
 282         conf = (typeof(conf)) {
 283                 .psc_name               = LUSTRE_MDT_NAME "_out",
 284                 .psc_watchdog_factor    = MDT_SERVICE_WATCHDOG_FACTOR,
 285                 .psc_buf                = {
 286                         .bc_nbufs               = MDS_NBUFS,
 287                         .bc_buf_size            = OUT_BUFSIZE,
 288                         .bc_req_max_size        = OUT_MAXREQSIZE,
 289                         .bc_rep_max_size        = OUT_MAXREPSIZE,
 290                         .bc_req_portal          = OUT_PORTAL,
 291                         .bc_rep_portal          = OSC_REPLY_PORTAL,
 292                 },
 293                 /*
 294                  * We'd like to have a mechanism to set this on a per-device
 295                  * basis, but alas...
 296                  */
 297                 .psc_thr                = {
 298                         .tc_thr_name            = LUSTRE_MDT_NAME "_out",
 299                         .tc_thr_factor          = MDS_THR_FACTOR,
 300                         .tc_nthrs_init          = MDS_NTHRS_INIT,
 301                         .tc_nthrs_base          = MDS_NTHRS_BASE,
 302                         .tc_nthrs_max           = MDS_NTHRS_MAX,
 303                         .tc_nthrs_user          = mds_num_threads,
 304                         .tc_cpu_affinity        = 1,
 305                         .tc_ctx_tags            = LCT_MD_THREAD |
 306                                                   LCT_DT_THREAD,
 307                 },
 308                 .psc_cpt                = {
 309                         .cc_pattern             = mds_num_cpts,
 310                 },
 311                 .psc_ops                = {
 312                         .so_req_handler         = tgt_request_handle,
 313                         .so_req_printer         = target_print_req,
 314                         .so_hpreq_handler       = NULL,
 315                 },
 316         };
 317         m->mds_out_service = ptlrpc_register_service(&conf, procfs_entry);
 318         if (IS_ERR(m->mds_out_service)) {
 319                 rc = PTR_ERR(m->mds_out_service);
 320                 CERROR("failed to start out service: %d\n", rc);
 321                 m->mds_out_service = NULL;
 322                 GOTO(err_mds_svc, rc);
 323         }
 324
 325         /*
 326          * sequence controller service configuration
 327          */
 328         memset(&conf, 0, sizeof(conf));
 329         conf = (typeof(conf)) {
 330                 .psc_name               = LUSTRE_MDT_NAME "_seqs",
 331                 .psc_watchdog_factor    = MDT_SERVICE_WATCHDOG_FACTOR,
 332                 .psc_buf                = {
 333                         .bc_nbufs               = MDS_NBUFS,
 334                         .bc_buf_size            = SEQ_BUFSIZE,
 335                         .bc_req_max_size        = SEQ_MAXREQSIZE,
 336                         .bc_rep_max_size        = SEQ_MAXREPSIZE,
 337                         .bc_req_portal          = SEQ_CONTROLLER_PORTAL,
 338                         .bc_rep_portal          = MDC_REPLY_PORTAL,
 339                 },
 340                 .psc_thr                = {
 341                         .tc_thr_name            = LUSTRE_MDT_NAME "_seqs",
 342                         .tc_nthrs_init          = MDS_OTHR_NTHRS_INIT,
 343                         .tc_nthrs_max           = MDS_OTHR_NTHRS_MAX,
 344                         .tc_ctx_tags            = LCT_MD_THREAD,
 345                 },
 346                 .psc_ops                = {
 347                         .so_req_handler         = tgt_request_handle,
 348                         .so_req_printer         = target_print_req,
 349                         .so_hpreq_handler       = NULL,
 350                 },
 351         };
 352         m->mds_mdsc_service = ptlrpc_register_service(&conf, procfs_entry);
 353         if (IS_ERR(m->mds_mdsc_service)) {
 354                 rc = PTR_ERR(m->mds_mdsc_service);
 355                 CERROR("failed to start seq controller service: %d\n", rc);
 356                 m->mds_mdsc_service = NULL;
 357
 358                 GOTO(err_mds_svc, rc);
 359         }
 360
 361         /*
 362          * metadata sequence server service configuration
 363          */
 364         memset(&conf, 0, sizeof(conf));
 365         conf = (typeof(conf)) {
 366                 .psc_name               = LUSTRE_MDT_NAME "_seqm",
 367                 .psc_watchdog_factor    = MDT_SERVICE_WATCHDOG_FACTOR,
 368                 .psc_buf                = {
 369                         .bc_nbufs               = MDS_NBUFS,
 370                         .bc_buf_size            = SEQ_BUFSIZE,
 371                         .bc_req_max_size        = SEQ_MAXREQSIZE,
 372                         .bc_rep_max_size        = SEQ_MAXREPSIZE,
 373                         .bc_req_portal          = SEQ_METADATA_PORTAL,
 374                         .bc_rep_portal          = MDC_REPLY_PORTAL,
 375                 },
 376                 .psc_thr                = {
 377                         .tc_thr_name            = LUSTRE_MDT_NAME "_seqm",
 378                         .tc_nthrs_init          = MDS_OTHR_NTHRS_INIT,
 379                         .tc_nthrs_max           = MDS_OTHR_NTHRS_MAX,
 380                         .tc_ctx_tags            = LCT_MD_THREAD | LCT_DT_THREAD
 381                 },
 382                 .psc_ops                = {
 383                         .so_req_handler         = tgt_request_handle,
 384                         .so_req_printer         = target_print_req,
 385                         .so_hpreq_handler       = NULL,
 386                 },
 387         };
 388         m->mds_mdss_service = ptlrpc_register_service(&conf, procfs_entry);
 389         if (IS_ERR(m->mds_mdss_service)) {
 390                 rc = PTR_ERR(m->mds_mdss_service);
 391                 CERROR("failed to start metadata seq server service: %d\n", rc);
 392                 m->mds_mdss_service = NULL;
 393
 394                 GOTO(err_mds_svc, rc);
 395         }
 396
 397         /* FLD service start */
 398         memset(&conf, 0, sizeof(conf));
 399         conf = (typeof(conf)) {
 400                 .psc_name            = LUSTRE_MDT_NAME "_fld",
 401                 .psc_watchdog_factor = MDT_SERVICE_WATCHDOG_FACTOR,
 402                 .psc_buf                = {
 403                         .bc_nbufs               = MDS_NBUFS,
 404                         .bc_buf_size            = FLD_BUFSIZE,
 405                         .bc_req_max_size        = FLD_MAXREQSIZE,
 406                         .bc_rep_max_size        = FLD_MAXREPSIZE,
 407                         .bc_req_portal          = FLD_REQUEST_PORTAL,
 408                         .bc_rep_portal          = MDC_REPLY_PORTAL,
 409                 },
 410                 .psc_thr                = {
 411                         .tc_thr_name            = LUSTRE_MDT_NAME "_fld",
 412                         .tc_nthrs_init          = MDS_OTHR_NTHRS_INIT,
 413                         .tc_nthrs_max           = MDS_OTHR_NTHRS_MAX,
 414                         .tc_ctx_tags            = LCT_DT_THREAD | LCT_MD_THREAD,
 415                 },
 416                 .psc_ops                = {
 417                         .so_req_handler         = tgt_request_handle,
 418                         .so_req_printer         = target_print_req,
 419                         .so_hpreq_handler       = NULL,
 420                 },
 421         };
 422         m->mds_fld_service = ptlrpc_register_service(&conf, procfs_entry);
 423         if (IS_ERR(m->mds_fld_service)) {
 424                 rc = PTR_ERR(m->mds_fld_service);
 425                 CERROR("failed to start fld service: %d\n", rc);
 426                 m->mds_fld_service = NULL;
 427
 428                 GOTO(err_mds_svc, rc);
 429         }
 430
 431         EXIT;
 432 err_mds_svc:
 433         if (rc)
 434                 mds_stop_ptlrpc_service(m);
 435
 436         return rc;
 437 }
 438
 439 static inline struct mds_device *mds_dev(struct lu_device *d)
 440 {
 441         return container_of0(d, struct mds_device, mds_md_dev.md_lu_dev);
 442 }
 443
 444 static struct lu_device *mds_device_fini(const struct lu_env *env,
 445                                          struct lu_device *d)
 446 {
 447         struct mds_device *m = mds_dev(d);
 448         struct obd_device *obd = d->ld_obd;
 449         ENTRY;
 450
 451         mds_stop_ptlrpc_service(m);
 452         lprocfs_obd_cleanup(obd);
 453         RETURN(NULL);
 454 }
 455
 456 static struct lu_device *mds_device_free(const struct lu_env *env,
 457                                          struct lu_device *d)
 458 {
 459         struct mds_device *m = mds_dev(d);
 460         ENTRY;
 461
 462         md_device_fini(&m->mds_md_dev);
 463         OBD_FREE_PTR(m);
 464         RETURN(NULL);
 465 }
 466
 467 LPROC_SEQ_FOPS_RO_TYPE(mds, uuid);
 468
 469 static struct lprocfs_vars lprocfs_mds_obd_vars[] = {
 470         { "uuid",       &mds_uuid_fops  },
 471         { NULL }
 472 };
 473
 474 static struct lu_device *mds_device_alloc(const struct lu_env *env,
 475                                           struct lu_device_type *t,
 476                                           struct lustre_cfg *cfg)
 477 {
 478         struct mds_device        *m;
 479         struct obd_device        *obd;
 480         struct lu_device          *l;
 481         int rc;
 482
 483         OBD_ALLOC_PTR(m);
 484         if (m == NULL)
 485                 return ERR_PTR(-ENOMEM);
 486
 487         md_device_init(&m->mds_md_dev, t);
 488         l = &m->mds_md_dev.md_lu_dev;
 489
 490         obd = class_name2obd(lustre_cfg_string(cfg, 0));
 491         LASSERT(obd != NULL);
 492
 493         l->ld_obd = obd;
 494         /* set this lu_device to obd, because error handling need it */
 495         obd->obd_lu_dev = l;
 496
 497         obd->obd_vars = lprocfs_mds_obd_vars;
 498         rc = lprocfs_obd_setup(obd);
 499         if (rc != 0) {
 500                 mds_device_free(env, l);
 501                 l = ERR_PTR(rc);
 502                 return l;
 503         }
 504
 505         rc = mds_start_ptlrpc_service(m);
 506
 507         if (rc != 0) {
 508                 mds_device_free(env, l);
 509                 l = ERR_PTR(rc);
 510                 return l;
 511         }
 512         return l;
 513 }
 514
 515 /* type constructor/destructor: mdt_type_init, mdt_type_fini */
 516 LU_TYPE_INIT_FINI(mds, &mdt_thread_key);
 517
 518 static struct lu_device_type_operations mds_device_type_ops = {
 519         .ldto_init = mds_type_init,
 520         .ldto_fini = mds_type_fini,
 521
 522         .ldto_start = mds_type_start,
 523         .ldto_stop  = mds_type_stop,
 524
 525         .ldto_device_alloc = mds_device_alloc,
 526         .ldto_device_free  = mds_device_free,
 527         .ldto_device_fini  = mds_device_fini
 528 };
 529
 530 static struct lu_device_type mds_device_type = {
 531         .ldt_tags     = LU_DEVICE_MD,
 532         .ldt_name     = LUSTRE_MDS_NAME,
 533         .ldt_ops      = &mds_device_type_ops,
 534         .ldt_ctx_tags = LCT_MD_THREAD
 535 };
 536
 537 static struct obd_ops mds_obd_device_ops = {
 538         .o_owner           = THIS_MODULE,
 539 };
 540
 541 int mds_mod_init(void)
 542 {
 543         if (mdt_num_threads != 0 && mds_num_threads == 0) {
 544                 LCONSOLE_INFO("mdt_num_threads module parameter is deprecated, "
 545                               "use mds_num_threads instead or unset both for "
 546                               "dynamic thread startup\n");
 547                 mds_num_threads = mdt_num_threads;
 548         }
 549
 550         return class_register_type(&mds_obd_device_ops, NULL, true, NULL,
 551                                    LUSTRE_MDS_NAME, &mds_device_type);
 552 }
 553
 554 void mds_mod_exit(void)
 555 {
 556         class_unregister_type(LUSTRE_MDS_NAME);
 557 }