drivers/staging/lustre/lustre/llite/vvp_dev.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) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2012, 2015, 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  * cl_device and cl_device_type implementation for VVP layer.
  33  *
  34  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  35  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  36  */
  37
  38 #define DEBUG_SUBSYSTEM S_LLITE
  39
  40 #include "../include/obd.h"
  41 #include "llite_internal.h"
  42 #include "vvp_internal.h"
  43
  44 /*****************************************************************************
  45  *
  46  * Vvp device and device type functions.
  47  *
  48  */
  49
  50 /*
  51  * vvp_ prefix stands for "Vfs Vm Posix". It corresponds to historical
  52  * "llite_" (var. "ll_") prefix.
  53  */
  54
  55 static struct kmem_cache *ll_thread_kmem;
  56 struct kmem_cache *vvp_lock_kmem;
  57 struct kmem_cache *vvp_object_kmem;
  58 struct kmem_cache *vvp_req_kmem;
  59 static struct kmem_cache *vvp_session_kmem;
  60 static struct kmem_cache *vvp_thread_kmem;
  61
  62 static struct lu_kmem_descr vvp_caches[] = {
  63         {
  64                 .ckd_cache = &ll_thread_kmem,
  65                 .ckd_name  = "ll_thread_kmem",
  66                 .ckd_size  = sizeof(struct ll_thread_info),
  67         },
  68         {
  69                 .ckd_cache = &vvp_lock_kmem,
  70                 .ckd_name  = "vvp_lock_kmem",
  71                 .ckd_size  = sizeof(struct vvp_lock),
  72         },
  73         {
  74                 .ckd_cache = &vvp_object_kmem,
  75                 .ckd_name  = "vvp_object_kmem",
  76                 .ckd_size  = sizeof(struct vvp_object),
  77         },
  78         {
  79                 .ckd_cache = &vvp_req_kmem,
  80                 .ckd_name  = "vvp_req_kmem",
  81                 .ckd_size  = sizeof(struct vvp_req),
  82         },
  83         {
  84                 .ckd_cache = &vvp_session_kmem,
  85                 .ckd_name  = "vvp_session_kmem",
  86                 .ckd_size  = sizeof(struct vvp_session)
  87         },
  88         {
  89                 .ckd_cache = &vvp_thread_kmem,
  90                 .ckd_name  = "vvp_thread_kmem",
  91                 .ckd_size  = sizeof(struct vvp_thread_info),
  92         },
  93         {
  94                 .ckd_cache = NULL
  95         }
  96 };
  97
  98 static void *ll_thread_key_init(const struct lu_context *ctx,
  99                                 struct lu_context_key *key)
 100 {
 101         struct vvp_thread_info *info;
 102
 103         info = kmem_cache_zalloc(ll_thread_kmem, GFP_NOFS);
 104         if (!info)
 105                 info = ERR_PTR(-ENOMEM);
 106         return info;
 107 }
 108
 109 static void ll_thread_key_fini(const struct lu_context *ctx,
 110                                struct lu_context_key *key, void *data)
 111 {
 112         struct vvp_thread_info *info = data;
 113
 114         kmem_cache_free(ll_thread_kmem, info);
 115 }
 116
 117 struct lu_context_key ll_thread_key = {
 118         .lct_tags = LCT_CL_THREAD,
 119         .lct_init = ll_thread_key_init,
 120         .lct_fini = ll_thread_key_fini
 121 };
 122
 123 static void *vvp_session_key_init(const struct lu_context *ctx,
 124                                   struct lu_context_key *key)
 125 {
 126         struct vvp_session *session;
 127
 128         session = kmem_cache_zalloc(vvp_session_kmem, GFP_NOFS);
 129         if (!session)
 130                 session = ERR_PTR(-ENOMEM);
 131         return session;
 132 }
 133
 134 static void vvp_session_key_fini(const struct lu_context *ctx,
 135                                  struct lu_context_key *key, void *data)
 136 {
 137         struct vvp_session *session = data;
 138
 139         kmem_cache_free(vvp_session_kmem, session);
 140 }
 141
 142 struct lu_context_key vvp_session_key = {
 143         .lct_tags = LCT_SESSION,
 144         .lct_init = vvp_session_key_init,
 145         .lct_fini = vvp_session_key_fini
 146 };
 147
 148 static void *vvp_thread_key_init(const struct lu_context *ctx,
 149                                  struct lu_context_key *key)
 150 {
 151         struct vvp_thread_info *vti;
 152
 153         vti = kmem_cache_zalloc(vvp_thread_kmem, GFP_NOFS);
 154         if (!vti)
 155                 vti = ERR_PTR(-ENOMEM);
 156         return vti;
 157 }
 158
 159 static void vvp_thread_key_fini(const struct lu_context *ctx,
 160                                 struct lu_context_key *key, void *data)
 161 {
 162         struct vvp_thread_info *vti = data;
 163
 164         kmem_cache_free(vvp_thread_kmem, vti);
 165 }
 166
 167 struct lu_context_key vvp_thread_key = {
 168         .lct_tags = LCT_CL_THREAD,
 169         .lct_init = vvp_thread_key_init,
 170         .lct_fini = vvp_thread_key_fini
 171 };
 172
 173 /* type constructor/destructor: vvp_type_{init,fini,start,stop}(). */
 174 LU_TYPE_INIT_FINI(vvp, &vvp_thread_key, &ll_thread_key, &vvp_session_key);
 175
 176 static const struct lu_device_operations vvp_lu_ops = {
 177         .ldo_object_alloc      = vvp_object_alloc
 178 };
 179
 180 static const struct cl_device_operations vvp_cl_ops = {
 181         .cdo_req_init = vvp_req_init
 182 };
 183
 184 static struct lu_device *vvp_device_free(const struct lu_env *env,
 185                                          struct lu_device *d)
 186 {
 187         struct vvp_device *vdv  = lu2vvp_dev(d);
 188         struct cl_site    *site = lu2cl_site(d->ld_site);
 189         struct lu_device  *next = cl2lu_dev(vdv->vdv_next);
 190
 191         if (d->ld_site) {
 192                 cl_site_fini(site);
 193                 kfree(site);
 194         }
 195         cl_device_fini(lu2cl_dev(d));
 196         kfree(vdv);
 197         return next;
 198 }
 199
 200 static struct lu_device *vvp_device_alloc(const struct lu_env *env,
 201                                           struct lu_device_type *t,
 202                                           struct lustre_cfg *cfg)
 203 {
 204         struct vvp_device *vdv;
 205         struct lu_device  *lud;
 206         struct cl_site    *site;
 207         int rc;
 208
 209         vdv = kzalloc(sizeof(*vdv), GFP_NOFS);
 210         if (!vdv)
 211                 return ERR_PTR(-ENOMEM);
 212
 213         lud = &vdv->vdv_cl.cd_lu_dev;
 214         cl_device_init(&vdv->vdv_cl, t);
 215         vvp2lu_dev(vdv)->ld_ops = &vvp_lu_ops;
 216         vdv->vdv_cl.cd_ops = &vvp_cl_ops;
 217
 218         site = kzalloc(sizeof(*site), GFP_NOFS);
 219         if (site) {
 220                 rc = cl_site_init(site, &vdv->vdv_cl);
 221                 if (rc == 0) {
 222                         rc = lu_site_init_finish(&site->cs_lu);
 223                 } else {
 224                         LASSERT(!lud->ld_site);
 225                         CERROR("Cannot init lu_site, rc %d.\n", rc);
 226                         kfree(site);
 227                 }
 228         } else {
 229                 rc = -ENOMEM;
 230         }
 231         if (rc != 0) {
 232                 vvp_device_free(env, lud);
 233                 lud = ERR_PTR(rc);
 234         }
 235         return lud;
 236 }
 237
 238 static int vvp_device_init(const struct lu_env *env, struct lu_device *d,
 239                            const char *name, struct lu_device *next)
 240 {
 241         struct vvp_device  *vdv;
 242         int rc;
 243
 244         vdv = lu2vvp_dev(d);
 245         vdv->vdv_next = lu2cl_dev(next);
 246
 247         LASSERT(d->ld_site && next->ld_type);
 248         next->ld_site = d->ld_site;
 249         rc = next->ld_type->ldt_ops->ldto_device_init(env, next,
 250                                                       next->ld_type->ldt_name,
 251                                                       NULL);
 252         if (rc == 0) {
 253                 lu_device_get(next);
 254                 lu_ref_add(&next->ld_reference, "lu-stack", &lu_site_init);
 255         }
 256         return rc;
 257 }
 258
 259 static struct lu_device *vvp_device_fini(const struct lu_env *env,
 260                                          struct lu_device *d)
 261 {
 262         return cl2lu_dev(lu2vvp_dev(d)->vdv_next);
 263 }
 264
 265 static const struct lu_device_type_operations vvp_device_type_ops = {
 266         .ldto_init = vvp_type_init,
 267         .ldto_fini = vvp_type_fini,
 268
 269         .ldto_start = vvp_type_start,
 270         .ldto_stop  = vvp_type_stop,
 271
 272         .ldto_device_alloc = vvp_device_alloc,
 273         .ldto_device_free       = vvp_device_free,
 274         .ldto_device_init       = vvp_device_init,
 275         .ldto_device_fini       = vvp_device_fini,
 276 };
 277
 278 struct lu_device_type vvp_device_type = {
 279         .ldt_tags     = LU_DEVICE_CL,
 280         .ldt_name     = LUSTRE_VVP_NAME,
 281         .ldt_ops      = &vvp_device_type_ops,
 282         .ldt_ctx_tags = LCT_CL_THREAD
 283 };
 284
 285 /**
 286  * A mutex serializing calls to vvp_inode_fini() under extreme memory
 287  * pressure, when environments cannot be allocated.
 288  */
 289 int vvp_global_init(void)
 290 {
 291         int rc;
 292
 293         rc = lu_kmem_init(vvp_caches);
 294         if (rc != 0)
 295                 return rc;
 296
 297         rc = lu_device_type_init(&vvp_device_type);
 298         if (rc != 0)
 299                 goto out_kmem;
 300
 301         return 0;
 302
 303 out_kmem:
 304         lu_kmem_fini(vvp_caches);
 305
 306         return rc;
 307 }
 308
 309 void vvp_global_fini(void)
 310 {
 311         lu_device_type_fini(&vvp_device_type);
 312         lu_kmem_fini(vvp_caches);
 313 }
 314
 315 /*****************************************************************************
 316  *
 317  * mirror obd-devices into cl devices.
 318  *
 319  */
 320
 321 int cl_sb_init(struct super_block *sb)
 322 {
 323         struct ll_sb_info *sbi;
 324         struct cl_device  *cl;
 325         struct lu_env     *env;
 326         int rc = 0;
 327         int refcheck;
 328
 329         sbi  = ll_s2sbi(sb);
 330         env = cl_env_get(&refcheck);
 331         if (!IS_ERR(env)) {
 332                 cl = cl_type_setup(env, NULL, &vvp_device_type,
 333                                    sbi->ll_dt_exp->exp_obd->obd_lu_dev);
 334                 if (!IS_ERR(cl)) {
 335                         cl2vvp_dev(cl)->vdv_sb = sb;
 336                         sbi->ll_cl = cl;
 337                         sbi->ll_site = cl2lu_dev(cl)->ld_site;
 338                 }
 339                 cl_env_put(env, &refcheck);
 340         } else {
 341                 rc = PTR_ERR(env);
 342         }
 343         return rc;
 344 }
 345
 346 int cl_sb_fini(struct super_block *sb)
 347 {
 348         struct ll_sb_info *sbi;
 349         struct lu_env     *env;
 350         struct cl_device  *cld;
 351         int             refcheck;
 352         int             result;
 353
 354         sbi = ll_s2sbi(sb);
 355         env = cl_env_get(&refcheck);
 356         if (!IS_ERR(env)) {
 357                 cld = sbi->ll_cl;
 358
 359                 if (cld) {
 360                         cl_stack_fini(env, cld);
 361                         sbi->ll_cl = NULL;
 362                         sbi->ll_site = NULL;
 363                 }
 364                 cl_env_put(env, &refcheck);
 365                 result = 0;
 366         } else {
 367                 CERROR("Cannot cleanup cl-stack due to memory shortage.\n");
 368                 result = PTR_ERR(env);
 369         }
 370         return result;
 371 }
 372
 373 /****************************************************************************
 374  *
 375  * debugfs/lustre/llite/$MNT/dump_page_cache
 376  *
 377  ****************************************************************************/
 378
 379 /*
 380  * To represent contents of a page cache as a byte stream, following
 381  * information if encoded in 64bit offset:
 382  *
 383  *       - file hash bucket in lu_site::ls_hash[]       28bits
 384  *
 385  *       - how far file is from bucket head           4bits
 386  *
 387  *       - page index                              32bits
 388  *
 389  * First two data identify a file in the cache uniquely.
 390  */
 391
 392 #define PGC_OBJ_SHIFT (32 + 4)
 393 #define PGC_DEPTH_SHIFT (32)
 394
 395 struct vvp_pgcache_id {
 396         unsigned                 vpi_bucket;
 397         unsigned                 vpi_depth;
 398         uint32_t                 vpi_index;
 399
 400         unsigned                 vpi_curdep;
 401         struct lu_object_header *vpi_obj;
 402 };
 403
 404 static void vvp_pgcache_id_unpack(loff_t pos, struct vvp_pgcache_id *id)
 405 {
 406         CLASSERT(sizeof(pos) == sizeof(__u64));
 407
 408         id->vpi_index  = pos & 0xffffffff;
 409         id->vpi_depth  = (pos >> PGC_DEPTH_SHIFT) & 0xf;
 410         id->vpi_bucket = (unsigned long long)pos >> PGC_OBJ_SHIFT;
 411 }
 412
 413 static loff_t vvp_pgcache_id_pack(struct vvp_pgcache_id *id)
 414 {
 415         return
 416                 ((__u64)id->vpi_index) |
 417                 ((__u64)id->vpi_depth  << PGC_DEPTH_SHIFT) |
 418                 ((__u64)id->vpi_bucket << PGC_OBJ_SHIFT);
 419 }
 420
 421 static int vvp_pgcache_obj_get(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 422                                struct hlist_node *hnode, void *data)
 423 {
 424         struct vvp_pgcache_id   *id  = data;
 425         struct lu_object_header *hdr = cfs_hash_object(hs, hnode);
 426
 427         if (id->vpi_curdep-- > 0)
 428                 return 0; /* continue */
 429
 430         if (lu_object_is_dying(hdr))
 431                 return 1;
 432
 433         cfs_hash_get(hs, hnode);
 434         id->vpi_obj = hdr;
 435         return 1;
 436 }
 437
 438 static struct cl_object *vvp_pgcache_obj(const struct lu_env *env,
 439                                          struct lu_device *dev,
 440                                          struct vvp_pgcache_id *id)
 441 {
 442         LASSERT(lu_device_is_cl(dev));
 443
 444         id->vpi_depth &= 0xf;
 445         id->vpi_obj    = NULL;
 446         id->vpi_curdep = id->vpi_depth;
 447
 448         cfs_hash_hlist_for_each(dev->ld_site->ls_obj_hash, id->vpi_bucket,
 449                                 vvp_pgcache_obj_get, id);
 450         if (id->vpi_obj) {
 451                 struct lu_object *lu_obj;
 452
 453                 lu_obj = lu_object_locate(id->vpi_obj, dev->ld_type);
 454                 if (lu_obj) {
 455                         lu_object_ref_add(lu_obj, "dump", current);
 456                         return lu2cl(lu_obj);
 457                 }
 458                 lu_object_put(env, lu_object_top(id->vpi_obj));
 459
 460         } else if (id->vpi_curdep > 0) {
 461                 id->vpi_depth = 0xf;
 462         }
 463         return NULL;
 464 }
 465
 466 static loff_t vvp_pgcache_find(const struct lu_env *env,
 467                                struct lu_device *dev, loff_t pos)
 468 {
 469         struct cl_object     *clob;
 470         struct lu_site       *site;
 471         struct vvp_pgcache_id id;
 472
 473         site = dev->ld_site;
 474         vvp_pgcache_id_unpack(pos, &id);
 475
 476         while (1) {
 477                 if (id.vpi_bucket >= CFS_HASH_NHLIST(site->ls_obj_hash))
 478                         return ~0ULL;
 479                 clob = vvp_pgcache_obj(env, dev, &id);
 480                 if (clob) {
 481                         struct inode *inode = vvp_object_inode(clob);
 482                         struct page *vmpage;
 483                         int nr;
 484
 485                         nr = find_get_pages_contig(inode->i_mapping,
 486                                                    id.vpi_index, 1, &vmpage);
 487                         if (nr > 0) {
 488                                 id.vpi_index = vmpage->index;
 489                                 /* Cant support over 16T file */
 490                                 nr = !(vmpage->index > 0xffffffff);
 491                                 put_page(vmpage);
 492                         }
 493
 494                         lu_object_ref_del(&clob->co_lu, "dump", current);
 495                         cl_object_put(env, clob);
 496                         if (nr > 0)
 497                                 return vvp_pgcache_id_pack(&id);
 498                 }
 499                 /* to the next object. */
 500                 ++id.vpi_depth;
 501                 id.vpi_depth &= 0xf;
 502                 if (id.vpi_depth == 0 && ++id.vpi_bucket == 0)
 503                         return ~0ULL;
 504                 id.vpi_index = 0;
 505         }
 506 }
 507
 508 #define seq_page_flag(seq, page, flag, has_flags) do {            \
 509         if (test_bit(PG_##flag, &(page)->flags)) {                \
 510                 seq_printf(seq, "%s"#flag, has_flags ? "|" : "");       \
 511                 has_flags = 1;                                    \
 512         }                                                              \
 513 } while (0)
 514
 515 static void vvp_pgcache_page_show(const struct lu_env *env,
 516                                   struct seq_file *seq, struct cl_page *page)
 517 {
 518         struct vvp_page *vpg;
 519         struct page      *vmpage;
 520         int           has_flags;
 521
 522         vpg = cl2vvp_page(cl_page_at(page, &vvp_device_type));
 523         vmpage = vpg->vpg_page;
 524         seq_printf(seq, " %5i | %p %p %s %s %s %s | %p "DFID"(%p) %lu %u [",
 525                    0 /* gen */,
 526                    vpg, page,
 527                    "none",
 528                    vpg->vpg_write_queued ? "wq" : "- ",
 529                    vpg->vpg_defer_uptodate ? "du" : "- ",
 530                    PageWriteback(vmpage) ? "wb" : "-",
 531                    vmpage, PFID(ll_inode2fid(vmpage->mapping->host)),
 532                    vmpage->mapping->host, vmpage->index,
 533                    page_count(vmpage));
 534         has_flags = 0;
 535         seq_page_flag(seq, vmpage, locked, has_flags);
 536         seq_page_flag(seq, vmpage, error, has_flags);
 537         seq_page_flag(seq, vmpage, referenced, has_flags);
 538         seq_page_flag(seq, vmpage, uptodate, has_flags);
 539         seq_page_flag(seq, vmpage, dirty, has_flags);
 540         seq_page_flag(seq, vmpage, writeback, has_flags);
 541         seq_printf(seq, "%s]\n", has_flags ? "" : "-");
 542 }
 543
 544 static int vvp_pgcache_show(struct seq_file *f, void *v)
 545 {
 546         loff_t             pos;
 547         struct ll_sb_info       *sbi;
 548         struct cl_object        *clob;
 549         struct lu_env      *env;
 550         struct vvp_pgcache_id    id;
 551         int                   refcheck;
 552         int                   result;
 553
 554         env = cl_env_get(&refcheck);
 555         if (!IS_ERR(env)) {
 556                 pos = *(loff_t *)v;
 557                 vvp_pgcache_id_unpack(pos, &id);
 558                 sbi = f->private;
 559                 clob = vvp_pgcache_obj(env, &sbi->ll_cl->cd_lu_dev, &id);
 560                 if (clob) {
 561                         struct inode *inode = vvp_object_inode(clob);
 562                         struct cl_page *page = NULL;
 563                         struct page *vmpage;
 564
 565                         result = find_get_pages_contig(inode->i_mapping,
 566                                                        id.vpi_index, 1,
 567                                                        &vmpage);
 568                         if (result > 0) {
 569                                 lock_page(vmpage);
 570                                 page = cl_vmpage_page(vmpage, clob);
 571                                 unlock_page(vmpage);
 572                                 put_page(vmpage);
 573                         }
 574
 575                         seq_printf(f, "%8x@" DFID ": ", id.vpi_index,
 576                                    PFID(lu_object_fid(&clob->co_lu)));
 577                         if (page) {
 578                                 vvp_pgcache_page_show(env, f, page);
 579                                 cl_page_put(env, page);
 580                         } else {
 581                                 seq_puts(f, "missing\n");
 582                         }
 583                         lu_object_ref_del(&clob->co_lu, "dump", current);
 584                         cl_object_put(env, clob);
 585                 } else {
 586                         seq_printf(f, "%llx missing\n", pos);
 587                 }
 588                 cl_env_put(env, &refcheck);
 589                 result = 0;
 590         } else {
 591                 result = PTR_ERR(env);
 592         }
 593         return result;
 594 }
 595
 596 static void *vvp_pgcache_start(struct seq_file *f, loff_t *pos)
 597 {
 598         struct ll_sb_info *sbi;
 599         struct lu_env     *env;
 600         int             refcheck;
 601
 602         sbi = f->private;
 603
 604         env = cl_env_get(&refcheck);
 605         if (!IS_ERR(env)) {
 606                 sbi = f->private;
 607                 if (sbi->ll_site->ls_obj_hash->hs_cur_bits > 64 - PGC_OBJ_SHIFT)
 608                         pos = ERR_PTR(-EFBIG);
 609                 else {
 610                         *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev,
 611                                                 *pos);
 612                         if (*pos == ~0ULL)
 613                                 pos = NULL;
 614                 }
 615                 cl_env_put(env, &refcheck);
 616         }
 617         return pos;
 618 }
 619
 620 static void *vvp_pgcache_next(struct seq_file *f, void *v, loff_t *pos)
 621 {
 622         struct ll_sb_info *sbi;
 623         struct lu_env     *env;
 624         int             refcheck;
 625
 626         env = cl_env_get(&refcheck);
 627         if (!IS_ERR(env)) {
 628                 sbi = f->private;
 629                 *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev, *pos + 1);
 630                 if (*pos == ~0ULL)
 631                         pos = NULL;
 632                 cl_env_put(env, &refcheck);
 633         }
 634         return pos;
 635 }
 636
 637 static void vvp_pgcache_stop(struct seq_file *f, void *v)
 638 {
 639         /* Nothing to do */
 640 }
 641
 642 static const struct seq_operations vvp_pgcache_ops = {
 643         .start = vvp_pgcache_start,
 644         .next  = vvp_pgcache_next,
 645         .stop  = vvp_pgcache_stop,
 646         .show  = vvp_pgcache_show
 647 };
 648
 649 static int vvp_dump_pgcache_seq_open(struct inode *inode, struct file *filp)
 650 {
 651         struct seq_file *seq;
 652         int rc;
 653
 654         rc = seq_open(filp, &vvp_pgcache_ops);
 655         if (rc)
 656                 return rc;
 657
 658         seq = filp->private_data;
 659         seq->private = inode->i_private;
 660
 661         return 0;
 662 }
 663
 664 const struct file_operations vvp_dump_pgcache_file_ops = {
 665         .owner   = THIS_MODULE,
 666         .open    = vvp_dump_pgcache_seq_open,
 667         .read    = seq_read,
 668         .llseek  = seq_lseek,
 669         .release = seq_release,
 670 };