lustre/obdecho/echo.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, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2010, 2015, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/obdecho/echo.c
  37  *
  38  * Author: Peter Braam <braam@clusterfs.com>
  39  * Author: Andreas Dilger <adilger@clusterfs.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_ECHO
  43
  44 #include <obd_support.h>
  45 #include <obd_class.h>
  46 #include <lustre_debug.h>
  47 #include <lustre_dlm.h>
  48 #include <lprocfs_status.h>
  49
  50 #include "echo_internal.h"
  51
  52 /* The echo objid needs to be below 2^32, because regular FID numbers are
  53  * limited to 2^32 objects in f_oid for the FID_SEQ_ECHO range. b=23335 */
  54 #define ECHO_INIT_OID        0x10000000ULL
  55 #define ECHO_HANDLE_MAGIC    0xabcd0123fedc9876ULL
  56
  57 #define ECHO_PERSISTENT_PAGES (ECHO_PERSISTENT_SIZE >> PAGE_SHIFT)
  58 static struct page *echo_persistent_pages[ECHO_PERSISTENT_PAGES];
  59
  60 enum {
  61         LPROC_ECHO_READ_BYTES = 1,
  62         LPROC_ECHO_WRITE_BYTES = 2,
  63         LPROC_ECHO_LAST = LPROC_ECHO_WRITE_BYTES +1
  64 };
  65
  66 static int echo_connect(const struct lu_env *env,
  67                         struct obd_export **exp, struct obd_device *obd,
  68                         struct obd_uuid *cluuid, struct obd_connect_data *data,
  69                         void *localdata)
  70 {
  71         struct lustre_handle conn = { 0 };
  72         int rc;
  73
  74         data->ocd_connect_flags &= ECHO_CONNECT_SUPPORTED;
  75
  76         if (data->ocd_connect_flags & OBD_CONNECT_FLAGS2)
  77                 data->ocd_connect_flags2 &= ECHO_CONNECT_SUPPORTED2;
  78
  79         rc = class_connect(&conn, obd, cluuid);
  80         if (rc) {
  81                 CERROR("can't connect %d\n", rc);
  82                 return rc;
  83         }
  84         *exp = class_conn2export(&conn);
  85
  86         return 0;
  87 }
  88
  89 static int echo_disconnect(struct obd_export *exp)
  90 {
  91         LASSERT (exp != NULL);
  92
  93         return server_disconnect_export(exp);
  94 }
  95
  96 static int echo_init_export(struct obd_export *exp)
  97 {
  98         return ldlm_init_export(exp);
  99 }
 100
 101 static int echo_destroy_export(struct obd_export *exp)
 102 {
 103         ENTRY;
 104
 105         target_destroy_export(exp);
 106         ldlm_destroy_export(exp);
 107
 108         RETURN(0);
 109 }
 110
 111 static u64 echo_next_id(struct obd_device *obddev)
 112 {
 113         u64 id;
 114
 115         spin_lock(&obddev->u.echo.eo_lock);
 116         id = ++obddev->u.echo.eo_lastino;
 117         spin_unlock(&obddev->u.echo.eo_lock);
 118
 119         return id;
 120 }
 121
 122 static int echo_create(const struct lu_env *env, struct obd_export *exp,
 123                        struct obdo *oa)
 124 {
 125         struct obd_device *obd = class_exp2obd(exp);
 126
 127         if (!obd) {
 128                 CERROR("invalid client cookie %#llx\n",
 129                        exp->exp_handle.h_cookie);
 130                 return -EINVAL;
 131         }
 132
 133         if (!(oa->o_mode & S_IFMT)) {
 134                 CERROR("echo obd: no type!\n");
 135                 return -ENOENT;
 136         }
 137
 138         if (!(oa->o_valid & OBD_MD_FLTYPE)) {
 139                 CERROR("invalid o_valid %#llx\n", oa->o_valid);
 140                 return -EINVAL;
 141         }
 142
 143         ostid_set_seq_echo(&oa->o_oi);
 144         ostid_set_id(&oa->o_oi, echo_next_id(obd));
 145         oa->o_valid = OBD_MD_FLID;
 146
 147         return 0;
 148 }
 149
 150 static int echo_destroy(const struct lu_env *env, struct obd_export *exp,
 151                         struct obdo *oa)
 152 {
 153         struct obd_device *obd = class_exp2obd(exp);
 154
 155         ENTRY;
 156         if (!obd) {
 157                 CERROR("invalid client cookie %#llx\n",
 158                        exp->exp_handle.h_cookie);
 159                 RETURN(-EINVAL);
 160         }
 161
 162         if (!(oa->o_valid & OBD_MD_FLID)) {
 163                 CERROR("obdo missing FLID valid flag: %#llx\n", oa->o_valid);
 164                 RETURN(-EINVAL);
 165         }
 166
 167         if (ostid_id(&oa->o_oi) > obd->u.echo.eo_lastino ||
 168             ostid_id(&oa->o_oi) < ECHO_INIT_OID) {
 169                 CERROR("bad destroy objid: "DOSTID"\n", POSTID(&oa->o_oi));
 170                 RETURN(-EINVAL);
 171         }
 172
 173         RETURN(0);
 174 }
 175
 176 static int echo_getattr(const struct lu_env *env, struct obd_export *exp,
 177                         struct obdo *oa)
 178 {
 179         struct obd_device *obd = class_exp2obd(exp);
 180         u64 id = ostid_id(&oa->o_oi);
 181
 182         ENTRY;
 183         if (!obd) {
 184                 CERROR("invalid client cookie %#llx\n",
 185                        exp->exp_handle.h_cookie);
 186                 RETURN(-EINVAL);
 187         }
 188
 189         if (!(oa->o_valid & OBD_MD_FLID)) {
 190                 CERROR("obdo missing FLID valid flag: %#llx\n", oa->o_valid);
 191                 RETURN(-EINVAL);
 192         }
 193
 194         obdo_cpy_md(oa, &obd->u.echo.eo_oa, oa->o_valid);
 195         ostid_set_seq_echo(&oa->o_oi);
 196         ostid_set_id(&oa->o_oi, id);
 197
 198         RETURN(0);
 199 }
 200
 201 static int echo_setattr(const struct lu_env *env, struct obd_export *exp,
 202                         struct obdo *oa)
 203 {
 204         struct obd_device *obd = class_exp2obd(exp);
 205
 206         ENTRY;
 207         if (!obd) {
 208                 CERROR("invalid client cookie %#llx\n",
 209                        exp->exp_handle.h_cookie);
 210                 RETURN(-EINVAL);
 211         }
 212
 213         if (!(oa->o_valid & OBD_MD_FLID)) {
 214                 CERROR("obdo missing FLID valid flag: %#llx\n", oa->o_valid);
 215                 RETURN(-EINVAL);
 216         }
 217
 218         obd->u.echo.eo_oa = *oa;
 219
 220         RETURN(0);
 221 }
 222
 223 static void
 224 echo_page_debug_setup(struct page *page, int rw, u64 id,
 225                       __u64 offset, int len)
 226 {
 227         int   page_offset = offset & ~PAGE_MASK;
 228         char *addr        = ((char *)kmap(page)) + page_offset;
 229
 230         if (len % OBD_ECHO_BLOCK_SIZE != 0)
 231                 CERROR("Unexpected block size %d\n", len);
 232
 233         while (len > 0) {
 234                 if (rw & OBD_BRW_READ)
 235                         block_debug_setup(addr, OBD_ECHO_BLOCK_SIZE,
 236                                           offset, id);
 237                 else
 238                         block_debug_setup(addr, OBD_ECHO_BLOCK_SIZE,
 239                                           0xecc0ecc0ecc0ecc0ULL,
 240                                           0xecc0ecc0ecc0ecc0ULL);
 241
 242                 addr   += OBD_ECHO_BLOCK_SIZE;
 243                 offset += OBD_ECHO_BLOCK_SIZE;
 244                 len    -= OBD_ECHO_BLOCK_SIZE;
 245         }
 246
 247         kunmap(page);
 248 }
 249
 250 static int
 251 echo_page_debug_check(struct page *page, u64 id,
 252                       __u64 offset, int len)
 253 {
 254         int   page_offset = offset & ~PAGE_MASK;
 255         char *addr        = ((char *)kmap(page)) + page_offset;
 256         int   rc          = 0;
 257         int   rc2;
 258
 259         if (len % OBD_ECHO_BLOCK_SIZE != 0)
 260                 CERROR("Unexpected block size %d\n", len);
 261
 262         while (len > 0) {
 263                 rc2 = block_debug_check("echo", addr, OBD_ECHO_BLOCK_SIZE,
 264                                         offset, id);
 265
 266                 if (rc2 != 0 && rc == 0)
 267                         rc = rc2;
 268
 269                 addr   += OBD_ECHO_BLOCK_SIZE;
 270                 offset += OBD_ECHO_BLOCK_SIZE;
 271                 len    -= OBD_ECHO_BLOCK_SIZE;
 272         }
 273
 274         kunmap(page);
 275
 276         return rc;
 277 }
 278
 279 static int echo_map_nb_to_lb(struct obdo *oa, struct obd_ioobj *obj,
 280                              struct niobuf_remote *nb, int *pages,
 281                              struct niobuf_local *lb, int cmd, int *left)
 282 {
 283         gfp_t gfp_mask = (ostid_id(&obj->ioo_oid) & 1) ?
 284                         GFP_HIGHUSER : GFP_KERNEL;
 285         int ispersistent = ostid_id(&obj->ioo_oid) == ECHO_PERSISTENT_OBJID;
 286         int debug_setup = (!ispersistent &&
 287                            (oa->o_valid & OBD_MD_FLFLAGS) != 0 &&
 288                            (oa->o_flags & OBD_FL_DEBUG_CHECK) != 0);
 289         struct niobuf_local *res = lb;
 290         u64 offset = nb->rnb_offset;
 291         int len = nb->rnb_len;
 292
 293         while (len > 0) {
 294                 int plen = PAGE_SIZE - (offset & (PAGE_SIZE-1));
 295                 if (len < plen)
 296                         plen = len;
 297
 298                 /* check for local buf overflow */
 299                 if (*left == 0)
 300                         return -EINVAL;
 301
 302                 res->lnb_file_offset = offset;
 303                 res->lnb_len = plen;
 304                 LASSERT((res->lnb_file_offset & ~PAGE_MASK) +
 305                         res->lnb_len <= PAGE_SIZE);
 306
 307                 if (ispersistent &&
 308                     ((res->lnb_file_offset >> PAGE_SHIFT) <
 309                       ECHO_PERSISTENT_PAGES)) {
 310                         res->lnb_page =
 311                                 echo_persistent_pages[res->lnb_file_offset >>
 312                                                       PAGE_SHIFT];
 313                         /* Take extra ref so __free_pages() can be called OK */
 314                         get_page(res->lnb_page);
 315                 } else {
 316                         res->lnb_page = alloc_page(gfp_mask);
 317                         if (res->lnb_page == NULL) {
 318                                 CERROR("can't get page for id " DOSTID"\n",
 319                                        POSTID(&obj->ioo_oid));
 320                                 return -ENOMEM;
 321                         }
 322                 }
 323
 324                 CDEBUG(D_PAGE, "$$$$ get page %p @ %llu for %d\n",
 325                        res->lnb_page, res->lnb_file_offset, res->lnb_len);
 326
 327                 if (cmd & OBD_BRW_READ)
 328                         res->lnb_rc = res->lnb_len;
 329
 330                 if (debug_setup)
 331                         echo_page_debug_setup(res->lnb_page, cmd,
 332                                               ostid_id(&obj->ioo_oid),
 333                                               res->lnb_file_offset,
 334                                               res->lnb_len);
 335
 336                 offset += plen;
 337                 len -= plen;
 338                 res++;
 339
 340                 (*left)--;
 341                 (*pages)++;
 342         }
 343
 344         return 0;
 345 }
 346
 347 static int echo_finalize_lb(struct obdo *oa, struct obd_ioobj *obj,
 348                             struct niobuf_remote *rb, int *pgs,
 349                             struct niobuf_local *lb, int verify)
 350 {
 351         struct niobuf_local *res = lb;
 352         u64 start = rb->rnb_offset >> PAGE_SHIFT;
 353         u64 end   = (rb->rnb_offset + rb->rnb_len + PAGE_SIZE - 1) >>
 354                     PAGE_SHIFT;
 355         int     count  = (int)(end - start);
 356         int     rc     = 0;
 357         int     i;
 358
 359         for (i = 0; i < count; i++, (*pgs) ++, res++) {
 360                 struct page *page = res->lnb_page;
 361                 void       *addr;
 362
 363                 if (page == NULL) {
 364                         CERROR("null page objid %llu:%p, buf %d/%d\n",
 365                                ostid_id(&obj->ioo_oid), page, i,
 366                                obj->ioo_bufcnt);
 367                         return -EFAULT;
 368                 }
 369
 370                 addr = kmap(page);
 371
 372                 CDEBUG(D_PAGE, "$$$$ use page %p, addr %p@%llu\n",
 373                        res->lnb_page, addr, res->lnb_file_offset);
 374
 375                 if (verify) {
 376                         int vrc = echo_page_debug_check(page,
 377                                                         ostid_id(&obj->ioo_oid),
 378                                                         res->lnb_file_offset,
 379                                                         res->lnb_len);
 380                         /* check all the pages always */
 381                         if (vrc != 0 && rc == 0)
 382                                 rc = vrc;
 383                 }
 384
 385                 kunmap(page);
 386                 /* NB see comment above regarding persistent pages */
 387                 __free_page(page);
 388         }
 389
 390         return rc;
 391 }
 392
 393 static int echo_preprw(const struct lu_env *env, int cmd,
 394                        struct obd_export *export, struct obdo *oa,
 395                        int objcount, struct obd_ioobj *obj,
 396                        struct niobuf_remote *nb, int *pages,
 397                        struct niobuf_local *res)
 398 {
 399         struct obd_device *obd;
 400         int tot_bytes = 0;
 401         int rc = 0;
 402         int i, left;
 403         ENTRY;
 404
 405         obd = export->exp_obd;
 406         if (obd == NULL)
 407                 RETURN(-EINVAL);
 408
 409         /* Temp fix to stop falling foul of osc_announce_cached() */
 410         oa->o_valid &= ~(OBD_MD_FLBLOCKS | OBD_MD_FLGRANT);
 411
 412         memset(res, 0, sizeof(*res) * *pages);
 413
 414         CDEBUG(D_PAGE, "%s %d obdos with %d IOs\n",
 415                cmd == OBD_BRW_READ ? "reading" : "writing", objcount, *pages);
 416
 417         left = *pages;
 418         *pages = 0;
 419
 420         for (i = 0; i < objcount; i++, obj++) {
 421                 int j;
 422
 423                 for (j = 0 ; j < obj->ioo_bufcnt ; j++, nb++) {
 424
 425                         rc = echo_map_nb_to_lb(oa, obj, nb, pages,
 426                                                res + *pages, cmd, &left);
 427                         if (rc)
 428                                 GOTO(preprw_cleanup, rc);
 429
 430                         tot_bytes += nb->rnb_len;
 431                 }
 432         }
 433
 434         atomic_add(*pages, &obd->u.echo.eo_prep);
 435
 436         if (cmd & OBD_BRW_READ)
 437                 lprocfs_counter_add(obd->obd_stats, LPROC_ECHO_READ_BYTES,
 438                                     tot_bytes);
 439         else
 440                 lprocfs_counter_add(obd->obd_stats, LPROC_ECHO_WRITE_BYTES,
 441                                     tot_bytes);
 442
 443         CDEBUG(D_PAGE, "%d pages allocated after prep\n",
 444                atomic_read(&obd->u.echo.eo_prep));
 445
 446         RETURN(0);
 447
 448 preprw_cleanup:
 449         /* It is possible that we would rather handle errors by  allow
 450          * any already-set-up pages to complete, rather than tearing them
 451          * all down again.  I believe that this is what the in-kernel
 452          * prep/commit operations do.
 453          */
 454         CERROR("cleaning up %u pages (%d obdos)\n", *pages, objcount);
 455         for (i = 0; i < *pages; i++) {
 456                 kunmap(res[i].lnb_page);
 457                 /* NB if this is a persistent page, __free_page() will just
 458                  * lose the extra ref gained above */
 459                 __free_page(res[i].lnb_page);
 460                 res[i].lnb_page = NULL;
 461                 atomic_dec(&obd->u.echo.eo_prep);
 462         }
 463
 464         return rc;
 465 }
 466
 467 static int echo_commitrw(const struct lu_env *env, int cmd,
 468                          struct obd_export *export, struct obdo *oa,
 469                          int objcount, struct obd_ioobj *obj,
 470                          struct niobuf_remote *rb, int niocount,
 471                          struct niobuf_local *res, int rc)
 472 {
 473         struct obd_device *obd;
 474         int pgs = 0;
 475         int i;
 476         ENTRY;
 477
 478         obd = export->exp_obd;
 479         if (obd == NULL)
 480                 RETURN(-EINVAL);
 481
 482         if (rc)
 483                 GOTO(commitrw_cleanup, rc);
 484
 485         if ((cmd & OBD_BRW_RWMASK) == OBD_BRW_READ) {
 486                 CDEBUG(D_PAGE, "reading %d obdos with %d IOs\n",
 487                        objcount, niocount);
 488         } else {
 489                 CDEBUG(D_PAGE, "writing %d obdos with %d IOs\n",
 490                        objcount, niocount);
 491         }
 492
 493         if (niocount && res == NULL) {
 494                 CERROR("NULL res niobuf with niocount %d\n", niocount);
 495                 RETURN(-EINVAL);
 496         }
 497
 498         for (i = 0; i < objcount; i++, obj++) {
 499                 int verify = (rc == 0 &&
 500                              ostid_id(&obj->ioo_oid) != ECHO_PERSISTENT_OBJID &&
 501                               (oa->o_valid & OBD_MD_FLFLAGS) != 0 &&
 502                               (oa->o_flags & OBD_FL_DEBUG_CHECK) != 0);
 503                 int j;
 504
 505                 for (j = 0 ; j < obj->ioo_bufcnt ; j++, rb++) {
 506                         int vrc = echo_finalize_lb(oa, obj, rb, &pgs, &res[pgs],
 507                                                    verify);
 508                         if (vrc == 0)
 509                                 continue;
 510
 511                         if (vrc == -EFAULT)
 512                                 GOTO(commitrw_cleanup, rc = vrc);
 513
 514                         if (rc == 0)
 515                                 rc = vrc;
 516                 }
 517
 518         }
 519
 520         atomic_sub(pgs, &obd->u.echo.eo_prep);
 521
 522         CDEBUG(D_PAGE, "%d pages remain after commit\n",
 523                atomic_read(&obd->u.echo.eo_prep));
 524         RETURN(rc);
 525
 526 commitrw_cleanup:
 527         atomic_sub(pgs, &obd->u.echo.eo_prep);
 528
 529         CERROR("cleaning up %d pages (%d obdos)\n",
 530                niocount - pgs - 1, objcount);
 531
 532         while (pgs < niocount) {
 533                 struct page *page = res[pgs++].lnb_page;
 534
 535                 if (page == NULL)
 536                         continue;
 537
 538                 /* NB see comment above regarding persistent pages */
 539                 __free_page(page);
 540                 atomic_dec(&obd->u.echo.eo_prep);
 541         }
 542         return rc;
 543 }
 544
 545 LPROC_SEQ_FOPS_RO_TYPE(echo, uuid);
 546 static struct lprocfs_vars lprocfs_echo_obd_vars[] = {
 547         { .name =       "uuid",
 548           .fops =       &echo_uuid_fops         },
 549         { NULL }
 550 };
 551
 552 static int echo_setup(struct obd_device *obd, struct lustre_cfg *lcfg)
 553 {
 554         int                     rc;
 555         __u64                   lock_flags = 0;
 556         struct ldlm_res_id      res_id = {.name = {1}};
 557         char                    ns_name[48];
 558         ENTRY;
 559
 560         obd->u.echo.eo_obt.obt_magic = OBT_MAGIC;
 561         spin_lock_init(&obd->u.echo.eo_lock);
 562         obd->u.echo.eo_lastino = ECHO_INIT_OID;
 563
 564         sprintf(ns_name, "echotgt-%s", obd->obd_uuid.uuid);
 565         obd->obd_namespace = ldlm_namespace_new(obd, ns_name,
 566                                                 LDLM_NAMESPACE_SERVER,
 567                                                 LDLM_NAMESPACE_MODEST,
 568                                                 LDLM_NS_TYPE_OST);
 569         if (obd->obd_namespace == NULL) {
 570                 LBUG();
 571                 RETURN(-ENOMEM);
 572         }
 573
 574         rc = ldlm_cli_enqueue_local(obd->obd_namespace, &res_id, LDLM_PLAIN,
 575                                     NULL, LCK_NL, &lock_flags, NULL,
 576                                     ldlm_completion_ast, NULL, NULL, 0,
 577                                     LVB_T_NONE, NULL, &obd->u.echo.eo_nl_lock);
 578         LASSERT (rc == ELDLM_OK);
 579
 580         obd->obd_vars = lprocfs_echo_obd_vars;
 581         if (lprocfs_obd_setup(obd) == 0 &&
 582             lprocfs_alloc_obd_stats(obd, LPROC_ECHO_LAST) == 0) {
 583                 lprocfs_counter_init(obd->obd_stats, LPROC_ECHO_READ_BYTES,
 584                                      LPROCFS_CNTR_AVGMINMAX,
 585                                      "read_bytes", "bytes");
 586                 lprocfs_counter_init(obd->obd_stats, LPROC_ECHO_WRITE_BYTES,
 587                                      LPROCFS_CNTR_AVGMINMAX,
 588                                      "write_bytes", "bytes");
 589         }
 590
 591         ptlrpc_init_client(LDLM_CB_REQUEST_PORTAL, LDLM_CB_REPLY_PORTAL,
 592                            "echo_ldlm_cb_client", &obd->obd_ldlm_client);
 593         RETURN(0);
 594 }
 595
 596 static int echo_cleanup(struct obd_device *obd)
 597 {
 598         int leaked;
 599         ENTRY;
 600
 601         lprocfs_obd_cleanup(obd);
 602         lprocfs_free_obd_stats(obd);
 603
 604         ldlm_lock_decref(&obd->u.echo.eo_nl_lock, LCK_NL);
 605
 606         /* XXX Bug 3413; wait for a bit to ensure the BL callback has
 607          * happened before calling ldlm_namespace_free() */
 608         set_current_state(TASK_UNINTERRUPTIBLE);
 609         schedule_timeout(cfs_time_seconds(1));
 610
 611         ldlm_namespace_free(obd->obd_namespace, NULL, obd->obd_force);
 612         obd->obd_namespace = NULL;
 613
 614         leaked = atomic_read(&obd->u.echo.eo_prep);
 615         if (leaked != 0)
 616                 CERROR("%d prep/commitrw pages leaked\n", leaked);
 617
 618         RETURN(0);
 619 }
 620
 621 struct obd_ops echo_obd_ops = {
 622         .o_owner           = THIS_MODULE,
 623         .o_connect         = echo_connect,
 624         .o_disconnect      = echo_disconnect,
 625         .o_init_export     = echo_init_export,
 626         .o_destroy_export  = echo_destroy_export,
 627         .o_create          = echo_create,
 628         .o_destroy         = echo_destroy,
 629         .o_getattr         = echo_getattr,
 630         .o_setattr         = echo_setattr,
 631         .o_preprw          = echo_preprw,
 632         .o_commitrw        = echo_commitrw,
 633         .o_setup           = echo_setup,
 634         .o_cleanup         = echo_cleanup
 635 };
 636
 637 void echo_persistent_pages_fini(void)
 638 {
 639         int i;
 640
 641         for (i = 0; i < ECHO_PERSISTENT_PAGES; i++)
 642                 if (echo_persistent_pages[i] != NULL) {
 643                         __free_page(echo_persistent_pages[i]);
 644                         echo_persistent_pages[i] = NULL;
 645                 }
 646 }
 647
 648 int echo_persistent_pages_init(void)
 649 {
 650         struct page *pg;
 651         int          i;
 652
 653         for (i = 0; i < ECHO_PERSISTENT_PAGES; i++) {
 654                 gfp_t gfp_mask = (i < ECHO_PERSISTENT_PAGES/2) ?
 655                         GFP_KERNEL : GFP_HIGHUSER;
 656
 657                 pg = alloc_page(gfp_mask);
 658                 if (pg == NULL) {
 659                         echo_persistent_pages_fini();
 660                         return -ENOMEM;
 661                 }
 662
 663                 memset(kmap(pg), 0, PAGE_SIZE);
 664                 kunmap(pg);
 665
 666                 echo_persistent_pages[i] = pg;
 667         }
 668
 669         return 0;
 670 }