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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2010, 2016, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * lustre/obdecho/echo.c
  33  *
  34  * Author: Peter Braam <braam@clusterfs.com>
  35  * Author: Andreas Dilger <adilger@clusterfs.com>
  36  */
  37
  38 #define DEBUG_SUBSYSTEM S_ECHO
  39
  40 #include <obd_support.h>
  41 #include <obd_class.h>
  42 #include <lustre_debug.h>
  43 #include <lustre_dlm.h>
  44 #include <lprocfs_status.h>
  45
  46 #include "echo_internal.h"
  47
  48 /* The echo objid needs to be below 2^32, because regular FID numbers are
  49  * limited to 2^32 objects in f_oid for the FID_SEQ_ECHO range. b=23335 */
  50 #define ECHO_INIT_OID        0x10000000ULL
  51 #define ECHO_HANDLE_MAGIC    0xabcd0123fedc9876ULL
  52
  53 #define ECHO_PERSISTENT_PAGES (ECHO_PERSISTENT_SIZE >> PAGE_SHIFT)
  54 static struct page *echo_persistent_pages[ECHO_PERSISTENT_PAGES];
  55
  56 enum {
  57         LPROC_ECHO_READ_BYTES = 1,
  58         LPROC_ECHO_WRITE_BYTES = 2,
  59         LPROC_ECHO_LAST = LPROC_ECHO_WRITE_BYTES +1
  60 };
  61
  62 static int echo_connect(const struct lu_env *env,
  63                         struct obd_export **exp, struct obd_device *obd,
  64                         struct obd_uuid *cluuid, struct obd_connect_data *data,
  65                         void *localdata)
  66 {
  67         struct lustre_handle conn = { 0 };
  68         int rc;
  69
  70         data->ocd_connect_flags &= ECHO_CONNECT_SUPPORTED;
  71
  72         if (data->ocd_connect_flags & OBD_CONNECT_FLAGS2)
  73                 data->ocd_connect_flags2 &= ECHO_CONNECT_SUPPORTED2;
  74
  75         rc = class_connect(&conn, obd, cluuid);
  76         if (rc) {
  77                 CERROR("can't connect %d\n", rc);
  78                 return rc;
  79         }
  80         *exp = class_conn2export(&conn);
  81
  82         return 0;
  83 }
  84
  85 static int echo_disconnect(struct obd_export *exp)
  86 {
  87         LASSERT (exp != NULL);
  88
  89         return server_disconnect_export(exp);
  90 }
  91
  92 static int echo_init_export(struct obd_export *exp)
  93 {
  94         return ldlm_init_export(exp);
  95 }
  96
  97 static int echo_destroy_export(struct obd_export *exp)
  98 {
  99         ENTRY;
 100
 101         target_destroy_export(exp);
 102         ldlm_destroy_export(exp);
 103
 104         RETURN(0);
 105 }
 106
 107 static u64 echo_next_id(struct obd_device *obddev)
 108 {
 109         u64 id;
 110
 111         spin_lock(&obddev->u.echo.eo_lock);
 112         id = ++obddev->u.echo.eo_lastino;
 113         spin_unlock(&obddev->u.echo.eo_lock);
 114
 115         return id;
 116 }
 117
 118 static int echo_create(const struct lu_env *env, struct obd_export *exp,
 119                        struct obdo *oa)
 120 {
 121         struct obd_device *obd = class_exp2obd(exp);
 122
 123         if (!obd) {
 124                 CERROR("invalid client cookie %#llx\n",
 125                        exp->exp_handle.h_cookie);
 126                 return -EINVAL;
 127         }
 128
 129         if (!(oa->o_mode & S_IFMT)) {
 130                 CERROR("echo obd: no type!\n");
 131                 return -ENOENT;
 132         }
 133
 134         if (!(oa->o_valid & OBD_MD_FLTYPE)) {
 135                 CERROR("invalid o_valid %#llx\n", oa->o_valid);
 136                 return -EINVAL;
 137         }
 138
 139         ostid_set_seq_echo(&oa->o_oi);
 140         if (ostid_set_id(&oa->o_oi, echo_next_id(obd))) {
 141                 CERROR("Bad %llu to set " DOSTID "\n",
 142                        echo_next_id(obd), POSTID(&oa->o_oi));
 143                 return -EINVAL;
 144         }
 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         if (ostid_set_id(&oa->o_oi, id)) {
 197                 CERROR("Bad %llu to set " DOSTID "\n",
 198                        id, POSTID(&oa->o_oi));
 199                 RETURN(-EINVAL);
 200         }
 201
 202         RETURN(0);
 203 }
 204
 205 static int echo_setattr(const struct lu_env *env, struct obd_export *exp,
 206                         struct obdo *oa)
 207 {
 208         struct obd_device *obd = class_exp2obd(exp);
 209
 210         ENTRY;
 211         if (!obd) {
 212                 CERROR("invalid client cookie %#llx\n",
 213                        exp->exp_handle.h_cookie);
 214                 RETURN(-EINVAL);
 215         }
 216
 217         if (!(oa->o_valid & OBD_MD_FLID)) {
 218                 CERROR("obdo missing FLID valid flag: %#llx\n", oa->o_valid);
 219                 RETURN(-EINVAL);
 220         }
 221
 222         obd->u.echo.eo_oa = *oa;
 223
 224         RETURN(0);
 225 }
 226
 227 static void
 228 echo_page_debug_setup(struct page *page, int rw, u64 id,
 229                       __u64 offset, int len)
 230 {
 231         int   page_offset = offset & ~PAGE_MASK;
 232         char *addr        = ((char *)kmap(page)) + page_offset;
 233
 234         if (len % OBD_ECHO_BLOCK_SIZE != 0)
 235                 CERROR("Unexpected block size %d\n", len);
 236
 237         while (len > 0) {
 238                 if (rw & OBD_BRW_READ)
 239                         block_debug_setup(addr, OBD_ECHO_BLOCK_SIZE,
 240                                           offset, id);
 241                 else
 242                         block_debug_setup(addr, OBD_ECHO_BLOCK_SIZE,
 243                                           0xecc0ecc0ecc0ecc0ULL,
 244                                           0xecc0ecc0ecc0ecc0ULL);
 245
 246                 addr   += OBD_ECHO_BLOCK_SIZE;
 247                 offset += OBD_ECHO_BLOCK_SIZE;
 248                 len    -= OBD_ECHO_BLOCK_SIZE;
 249         }
 250
 251         kunmap(page);
 252 }
 253
 254 static int
 255 echo_page_debug_check(struct page *page, u64 id,
 256                       __u64 offset, int len)
 257 {
 258         int   page_offset = offset & ~PAGE_MASK;
 259         char *addr        = ((char *)kmap(page)) + page_offset;
 260         int   rc          = 0;
 261         int   rc2;
 262
 263         if (len % OBD_ECHO_BLOCK_SIZE != 0)
 264                 CERROR("Unexpected block size %d\n", len);
 265
 266         while (len > 0) {
 267                 rc2 = block_debug_check("echo", addr, OBD_ECHO_BLOCK_SIZE,
 268                                         offset, id);
 269
 270                 if (rc2 != 0 && rc == 0)
 271                         rc = rc2;
 272
 273                 addr   += OBD_ECHO_BLOCK_SIZE;
 274                 offset += OBD_ECHO_BLOCK_SIZE;
 275                 len    -= OBD_ECHO_BLOCK_SIZE;
 276         }
 277
 278         kunmap(page);
 279
 280         return rc;
 281 }
 282
 283 static int echo_map_nb_to_lb(struct obdo *oa, struct obd_ioobj *obj,
 284                              struct niobuf_remote *nb, int *pages,
 285                              struct niobuf_local *lb, int cmd, int *left)
 286 {
 287         gfp_t gfp_mask = (ostid_id(&obj->ioo_oid) & 1) ?
 288                         GFP_HIGHUSER : GFP_KERNEL;
 289         int ispersistent = ostid_id(&obj->ioo_oid) == ECHO_PERSISTENT_OBJID;
 290         int debug_setup = (!ispersistent &&
 291                            (oa->o_valid & OBD_MD_FLFLAGS) != 0 &&
 292                            (oa->o_flags & OBD_FL_DEBUG_CHECK) != 0);
 293         struct niobuf_local *res = lb;
 294         u64 offset = nb->rnb_offset;
 295         int len = nb->rnb_len;
 296
 297         while (len > 0) {
 298                 int plen = PAGE_SIZE - (offset & (PAGE_SIZE-1));
 299                 if (len < plen)
 300                         plen = len;
 301
 302                 /* check for local buf overflow */
 303                 if (*left == 0)
 304                         return -EINVAL;
 305
 306                 res->lnb_file_offset = offset;
 307                 res->lnb_len = plen;
 308                 LASSERT((res->lnb_file_offset & ~PAGE_MASK) +
 309                         res->lnb_len <= PAGE_SIZE);
 310
 311                 if (ispersistent &&
 312                     ((res->lnb_file_offset >> PAGE_SHIFT) <
 313                       ECHO_PERSISTENT_PAGES)) {
 314                         res->lnb_page =
 315                                 echo_persistent_pages[res->lnb_file_offset >>
 316                                                       PAGE_SHIFT];
 317                         /* Take extra ref so __free_pages() can be called OK */
 318                         get_page(res->lnb_page);
 319                 } else {
 320                         res->lnb_page = alloc_page(gfp_mask);
 321                         if (res->lnb_page == NULL) {
 322                                 CERROR("can't get page for id " DOSTID"\n",
 323                                        POSTID(&obj->ioo_oid));
 324                                 return -ENOMEM;
 325                         }
 326                 }
 327
 328                 CDEBUG(D_PAGE, "$$$$ get page %p @ %llu for %d\n",
 329                        res->lnb_page, res->lnb_file_offset, res->lnb_len);
 330
 331                 if (cmd & OBD_BRW_READ)
 332                         res->lnb_rc = res->lnb_len;
 333
 334                 if (debug_setup)
 335                         echo_page_debug_setup(res->lnb_page, cmd,
 336                                               ostid_id(&obj->ioo_oid),
 337                                               res->lnb_file_offset,
 338                                               res->lnb_len);
 339
 340                 offset += plen;
 341                 len -= plen;
 342                 res++;
 343
 344                 (*left)--;
 345                 (*pages)++;
 346         }
 347
 348         return 0;
 349 }
 350
 351 static int echo_finalize_lb(struct obdo *oa, struct obd_ioobj *obj,
 352                             struct niobuf_remote *rb, int *pgs,
 353                             struct niobuf_local *lb, int verify)
 354 {
 355         struct niobuf_local *res = lb;
 356         u64 start = rb->rnb_offset >> PAGE_SHIFT;
 357         u64 end   = (rb->rnb_offset + rb->rnb_len + PAGE_SIZE - 1) >>
 358                     PAGE_SHIFT;
 359         int     count  = (int)(end - start);
 360         int     rc     = 0;
 361         int     i;
 362
 363         for (i = 0; i < count; i++, (*pgs) ++, res++) {
 364                 struct page *page = res->lnb_page;
 365                 void       *addr;
 366
 367                 if (page == NULL) {
 368                         CERROR("null page objid %llu:%p, buf %d/%d\n",
 369                                ostid_id(&obj->ioo_oid), page, i,
 370                                obj->ioo_bufcnt);
 371                         return -EFAULT;
 372                 }
 373
 374                 addr = kmap(page);
 375
 376                 CDEBUG(D_PAGE, "$$$$ use page %p, addr %p@%llu\n",
 377                        res->lnb_page, addr, res->lnb_file_offset);
 378
 379                 if (verify) {
 380                         int vrc = echo_page_debug_check(page,
 381                                                         ostid_id(&obj->ioo_oid),
 382                                                         res->lnb_file_offset,
 383                                                         res->lnb_len);
 384                         /* check all the pages always */
 385                         if (vrc != 0 && rc == 0)
 386                                 rc = vrc;
 387                 }
 388
 389                 kunmap(page);
 390                 /* NB see comment above regarding persistent pages */
 391                 __free_page(page);
 392         }
 393
 394         return rc;
 395 }
 396
 397 static int echo_preprw(const struct lu_env *env, int cmd,
 398                        struct obd_export *export, struct obdo *oa,
 399                        int objcount, struct obd_ioobj *obj,
 400                        struct niobuf_remote *nb, int *pages,
 401                        struct niobuf_local *res)
 402 {
 403         struct obd_device *obd;
 404         int tot_bytes = 0;
 405         int rc = 0;
 406         int i, left;
 407         ENTRY;
 408
 409         obd = export->exp_obd;
 410         if (obd == NULL)
 411                 RETURN(-EINVAL);
 412
 413         /* Temp fix to stop falling foul of osc_announce_cached() */
 414         oa->o_valid &= ~(OBD_MD_FLBLOCKS | OBD_MD_FLGRANT);
 415
 416         memset(res, 0, sizeof(*res) * *pages);
 417
 418         CDEBUG(D_PAGE, "%s %d obdos with %d IOs\n",
 419                cmd == OBD_BRW_READ ? "reading" : "writing", objcount, *pages);
 420
 421         left = *pages;
 422         *pages = 0;
 423
 424         for (i = 0; i < objcount; i++, obj++) {
 425                 int j;
 426
 427                 for (j = 0 ; j < obj->ioo_bufcnt ; j++, nb++) {
 428
 429                         rc = echo_map_nb_to_lb(oa, obj, nb, pages,
 430                                                res + *pages, cmd, &left);
 431                         if (rc)
 432                                 GOTO(preprw_cleanup, rc);
 433
 434                         tot_bytes += nb->rnb_len;
 435                 }
 436         }
 437
 438         atomic_add(*pages, &obd->u.echo.eo_prep);
 439
 440         if (cmd & OBD_BRW_READ)
 441                 lprocfs_counter_add(obd->obd_stats, LPROC_ECHO_READ_BYTES,
 442                                     tot_bytes);
 443         else
 444                 lprocfs_counter_add(obd->obd_stats, LPROC_ECHO_WRITE_BYTES,
 445                                     tot_bytes);
 446
 447         CDEBUG(D_PAGE, "%d pages allocated after prep\n",
 448                atomic_read(&obd->u.echo.eo_prep));
 449
 450         RETURN(0);
 451
 452 preprw_cleanup:
 453         /* It is possible that we would rather handle errors by  allow
 454          * any already-set-up pages to complete, rather than tearing them
 455          * all down again.  I believe that this is what the in-kernel
 456          * prep/commit operations do.
 457          */
 458         CERROR("cleaning up %u pages (%d obdos)\n", *pages, objcount);
 459         for (i = 0; i < *pages; i++) {
 460                 kunmap(res[i].lnb_page);
 461                 /* NB if this is a persistent page, __free_page() will just
 462                  * lose the extra ref gained above */
 463                 __free_page(res[i].lnb_page);
 464                 res[i].lnb_page = NULL;
 465                 atomic_dec(&obd->u.echo.eo_prep);
 466         }
 467
 468         return rc;
 469 }
 470
 471 static int echo_commitrw(const struct lu_env *env, int cmd,
 472                          struct obd_export *export, struct obdo *oa,
 473                          int objcount, struct obd_ioobj *obj,
 474                          struct niobuf_remote *rb, int niocount,
 475                          struct niobuf_local *res, int rc)
 476 {
 477         struct obd_device *obd;
 478         int pgs = 0;
 479         int i;
 480         ENTRY;
 481
 482         obd = export->exp_obd;
 483         if (obd == NULL)
 484                 RETURN(-EINVAL);
 485
 486         if (rc)
 487                 GOTO(commitrw_cleanup, rc);
 488
 489         if ((cmd & OBD_BRW_RWMASK) == OBD_BRW_READ) {
 490                 CDEBUG(D_PAGE, "reading %d obdos with %d IOs\n",
 491                        objcount, niocount);
 492         } else {
 493                 CDEBUG(D_PAGE, "writing %d obdos with %d IOs\n",
 494                        objcount, niocount);
 495         }
 496
 497         if (niocount && res == NULL) {
 498                 CERROR("NULL res niobuf with niocount %d\n", niocount);
 499                 RETURN(-EINVAL);
 500         }
 501
 502         for (i = 0; i < objcount; i++, obj++) {
 503                 int verify = (rc == 0 &&
 504                              ostid_id(&obj->ioo_oid) != ECHO_PERSISTENT_OBJID &&
 505                               (oa->o_valid & OBD_MD_FLFLAGS) != 0 &&
 506                               (oa->o_flags & OBD_FL_DEBUG_CHECK) != 0);
 507                 int j;
 508
 509                 for (j = 0 ; j < obj->ioo_bufcnt ; j++, rb++) {
 510                         int vrc = echo_finalize_lb(oa, obj, rb, &pgs, &res[pgs],
 511                                                    verify);
 512                         if (vrc == 0)
 513                                 continue;
 514
 515                         if (vrc == -EFAULT)
 516                                 GOTO(commitrw_cleanup, rc = vrc);
 517
 518                         if (rc == 0)
 519                                 rc = vrc;
 520                 }
 521
 522         }
 523
 524         atomic_sub(pgs, &obd->u.echo.eo_prep);
 525
 526         CDEBUG(D_PAGE, "%d pages remain after commit\n",
 527                atomic_read(&obd->u.echo.eo_prep));
 528         RETURN(rc);
 529
 530 commitrw_cleanup:
 531         atomic_sub(pgs, &obd->u.echo.eo_prep);
 532
 533         CERROR("cleaning up %d pages (%d obdos)\n",
 534                niocount - pgs - 1, objcount);
 535
 536         while (pgs < niocount) {
 537                 struct page *page = res[pgs++].lnb_page;
 538
 539                 if (page == NULL)
 540                         continue;
 541
 542                 /* NB see comment above regarding persistent pages */
 543                 __free_page(page);
 544                 atomic_dec(&obd->u.echo.eo_prep);
 545         }
 546         return rc;
 547 }
 548
 549 static int echo_setup(struct obd_device *obd, struct lustre_cfg *lcfg)
 550 {
 551         int                     rc;
 552         __u64                   lock_flags = 0;
 553         struct ldlm_res_id      res_id = {.name = {1}};
 554         char                    ns_name[48];
 555         ENTRY;
 556
 557         obd->u.echo.eo_obt.obt_magic = OBT_MAGIC;
 558         spin_lock_init(&obd->u.echo.eo_lock);
 559         obd->u.echo.eo_lastino = ECHO_INIT_OID;
 560
 561         sprintf(ns_name, "echotgt-%s", obd->obd_uuid.uuid);
 562         obd->obd_namespace = ldlm_namespace_new(obd, ns_name,
 563                                                 LDLM_NAMESPACE_SERVER,
 564                                                 LDLM_NAMESPACE_MODEST,
 565                                                 LDLM_NS_TYPE_OST);
 566         if (obd->obd_namespace == NULL) {
 567                 LBUG();
 568                 RETURN(-ENOMEM);
 569         }
 570
 571         rc = ldlm_cli_enqueue_local(obd->obd_namespace, &res_id, LDLM_PLAIN,
 572                                     NULL, LCK_NL, &lock_flags, NULL,
 573                                     ldlm_completion_ast, NULL, NULL, 0,
 574                                     LVB_T_NONE, NULL, &obd->u.echo.eo_nl_lock);
 575         LASSERT (rc == ELDLM_OK);
 576
 577         if (!lprocfs_obd_setup(obd, true) &&
 578             lprocfs_alloc_obd_stats(obd, LPROC_ECHO_LAST) == 0) {
 579                 lprocfs_counter_init(obd->obd_stats, LPROC_ECHO_READ_BYTES,
 580                                      LPROCFS_CNTR_AVGMINMAX,
 581                                      "read_bytes", "bytes");
 582                 lprocfs_counter_init(obd->obd_stats, LPROC_ECHO_WRITE_BYTES,
 583                                      LPROCFS_CNTR_AVGMINMAX,
 584                                      "write_bytes", "bytes");
 585         }
 586
 587         ptlrpc_init_client(LDLM_CB_REQUEST_PORTAL, LDLM_CB_REPLY_PORTAL,
 588                            "echo_ldlm_cb_client", &obd->obd_ldlm_client);
 589         RETURN(0);
 590 }
 591
 592 static int echo_cleanup(struct obd_device *obd)
 593 {
 594         int leaked;
 595         ENTRY;
 596
 597         lprocfs_obd_cleanup(obd);
 598         lprocfs_free_obd_stats(obd);
 599
 600         ldlm_lock_decref(&obd->u.echo.eo_nl_lock, LCK_NL);
 601
 602         /* XXX Bug 3413; wait for a bit to ensure the BL callback has
 603          * happened before calling ldlm_namespace_free() */
 604         set_current_state(TASK_UNINTERRUPTIBLE);
 605         schedule_timeout(cfs_time_seconds(1));
 606
 607         ldlm_namespace_free(obd->obd_namespace, NULL, obd->obd_force);
 608         obd->obd_namespace = NULL;
 609
 610         leaked = atomic_read(&obd->u.echo.eo_prep);
 611         if (leaked != 0)
 612                 CERROR("%d prep/commitrw pages leaked\n", leaked);
 613
 614         RETURN(0);
 615 }
 616
 617 struct obd_ops echo_obd_ops = {
 618         .o_owner           = THIS_MODULE,
 619         .o_connect         = echo_connect,
 620         .o_disconnect      = echo_disconnect,
 621         .o_init_export     = echo_init_export,
 622         .o_destroy_export  = echo_destroy_export,
 623         .o_create          = echo_create,
 624         .o_destroy         = echo_destroy,
 625         .o_getattr         = echo_getattr,
 626         .o_setattr         = echo_setattr,
 627         .o_preprw          = echo_preprw,
 628         .o_commitrw        = echo_commitrw,
 629         .o_setup           = echo_setup,
 630         .o_cleanup         = echo_cleanup
 631 };
 632
 633 void echo_persistent_pages_fini(void)
 634 {
 635         int i;
 636
 637         for (i = 0; i < ECHO_PERSISTENT_PAGES; i++)
 638                 if (echo_persistent_pages[i] != NULL) {
 639                         __free_page(echo_persistent_pages[i]);
 640                         echo_persistent_pages[i] = NULL;
 641                 }
 642 }
 643
 644 int echo_persistent_pages_init(void)
 645 {
 646         struct page *pg;
 647         int          i;
 648
 649         for (i = 0; i < ECHO_PERSISTENT_PAGES; i++) {
 650                 gfp_t gfp_mask = (i < ECHO_PERSISTENT_PAGES/2) ?
 651                         GFP_KERNEL : GFP_HIGHUSER;
 652
 653                 pg = alloc_page(gfp_mask);
 654                 if (pg == NULL) {
 655                         echo_persistent_pages_fini();
 656                         return -ENOMEM;
 657                 }
 658
 659                 memset(kmap(pg), 0, PAGE_SIZE);
 660                 kunmap(pg);
 661
 662                 echo_persistent_pages[i] = pg;
 663         }
 664
 665         return 0;
 666 }