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.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) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2012, 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  * cl_device and cl_device_type implementation for VVP layer.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_LLITE
  43
  44 #include <obd.h>
  45 #include "llite_internal.h"
  46 #include "vvp_internal.h"
  47
  48 /*****************************************************************************
  49  *
  50  * Vvp device and device type functions.
  51  *
  52  */
  53
  54 /*
  55  * vvp_ prefix stands for "Vfs Vm Posix". It corresponds to historical
  56  * "llite_" (var. "ll_") prefix.
  57  */
  58
  59 static struct kmem_cache *ll_thread_kmem;
  60 struct kmem_cache *vvp_lock_kmem;
  61 struct kmem_cache *vvp_object_kmem;
  62 static struct kmem_cache *vvp_session_kmem;
  63 static struct kmem_cache *vvp_thread_kmem;
  64
  65 static struct lu_kmem_descr vvp_caches[] = {
  66         {
  67                 .ckd_cache = &ll_thread_kmem,
  68                 .ckd_name  = "ll_thread_kmem",
  69                 .ckd_size  = sizeof(struct ll_thread_info),
  70         },
  71         {
  72                 .ckd_cache = &vvp_lock_kmem,
  73                 .ckd_name  = "vvp_lock_kmem",
  74                 .ckd_size  = sizeof(struct vvp_lock),
  75         },
  76         {
  77                 .ckd_cache = &vvp_object_kmem,
  78                 .ckd_name  = "vvp_object_kmem",
  79                 .ckd_size  = sizeof(struct vvp_object),
  80         },
  81         {
  82                 .ckd_cache = &vvp_session_kmem,
  83                 .ckd_name  = "vvp_session_kmem",
  84                 .ckd_size  = sizeof (struct vvp_session)
  85         },
  86         {
  87                 .ckd_cache = &vvp_thread_kmem,
  88                 .ckd_name  = "vvp_thread_kmem",
  89                 .ckd_size  = sizeof(struct vvp_thread_info),
  90         },
  91         {
  92                 .ckd_cache = NULL
  93         }
  94 };
  95
  96 static void *ll_thread_key_init(const struct lu_context *ctx,
  97                                 struct lu_context_key *key)
  98 {
  99         struct ll_thread_info *lti;
 100
 101         OBD_SLAB_ALLOC_PTR_GFP(lti, ll_thread_kmem, GFP_NOFS);
 102         if (lti == NULL)
 103                 lti = ERR_PTR(-ENOMEM);
 104
 105         return lti;
 106 }
 107
 108 static void ll_thread_key_fini(const struct lu_context *ctx,
 109                                struct lu_context_key *key, void *data)
 110 {
 111         struct ll_thread_info *lti = data;
 112
 113         OBD_SLAB_FREE_PTR(lti, ll_thread_kmem);
 114 }
 115
 116 struct lu_context_key ll_thread_key = {
 117         .lct_tags = LCT_CL_THREAD,
 118         .lct_init = ll_thread_key_init,
 119         .lct_fini = ll_thread_key_fini,
 120 };
 121
 122 static void *vvp_session_key_init(const struct lu_context *ctx,
 123                                   struct lu_context_key *key)
 124 {
 125         struct vvp_session *session;
 126
 127         OBD_SLAB_ALLOC_PTR_GFP(session, vvp_session_kmem, GFP_NOFS);
 128         if (session == NULL)
 129                 session = ERR_PTR(-ENOMEM);
 130         return session;
 131 }
 132
 133 static void vvp_session_key_fini(const struct lu_context *ctx,
 134                                  struct lu_context_key *key, void *data)
 135 {
 136         struct vvp_session *session = data;
 137         OBD_SLAB_FREE_PTR(session, vvp_session_kmem);
 138 }
 139
 140 struct lu_context_key vvp_session_key = {
 141         .lct_tags = LCT_SESSION,
 142         .lct_init = vvp_session_key_init,
 143         .lct_fini = vvp_session_key_fini
 144 };
 145
 146 static void *vvp_thread_key_init(const struct lu_context *ctx,
 147                                  struct lu_context_key *key)
 148 {
 149         struct vvp_thread_info *vti;
 150
 151         OBD_SLAB_ALLOC_PTR_GFP(vti, vvp_thread_kmem, GFP_NOFS);
 152         if (vti == NULL)
 153                 vti = ERR_PTR(-ENOMEM);
 154         return vti;
 155 }
 156
 157 static void vvp_thread_key_fini(const struct lu_context *ctx,
 158                                 struct lu_context_key *key, void *data)
 159 {
 160         struct vvp_thread_info *vti = data;
 161         OBD_SLAB_FREE_PTR(vti, vvp_thread_kmem);
 162 }
 163
 164 struct lu_context_key vvp_thread_key = {
 165         .lct_tags = LCT_CL_THREAD,
 166         .lct_init = vvp_thread_key_init,
 167         .lct_fini = vvp_thread_key_fini,
 168 };
 169
 170 /* type constructor/destructor: vvp_type_{init,fini,start,stop}(). */
 171 LU_TYPE_INIT_FINI(vvp, &ll_thread_key, &vvp_session_key, &vvp_thread_key);
 172
 173 static const struct lu_device_operations vvp_lu_ops = {
 174         .ldo_object_alloc      = vvp_object_alloc
 175 };
 176
 177 static struct lu_device *vvp_device_free(const struct lu_env *env,
 178                                          struct lu_device *d)
 179 {
 180         struct vvp_device *vdv  = lu2vvp_dev(d);
 181         struct cl_site    *site = lu2cl_site(d->ld_site);
 182         struct lu_device  *next = cl2lu_dev(vdv->vdv_next);
 183
 184         if (d->ld_site != NULL) {
 185                 cl_site_fini(site);
 186                 OBD_FREE_PTR(site);
 187         }
 188
 189         cl_device_fini(lu2cl_dev(d));
 190         OBD_FREE_PTR(vdv);
 191         return next;
 192 }
 193
 194 static struct lu_device *vvp_device_alloc(const struct lu_env *env,
 195                                           struct lu_device_type *t,
 196                                           struct lustre_cfg *cfg)
 197 {
 198         struct vvp_device *vdv;
 199         struct lu_device *lud;
 200         struct cl_site *site;
 201         int rc;
 202         ENTRY;
 203
 204         OBD_ALLOC_PTR(vdv);
 205         if (vdv == NULL)
 206                 RETURN(ERR_PTR(-ENOMEM));
 207
 208         lud = &vdv->vdv_cl.cd_lu_dev;
 209         cl_device_init(&vdv->vdv_cl, t);
 210         vvp2lu_dev(vdv)->ld_ops = &vvp_lu_ops;
 211
 212         OBD_ALLOC_PTR(site);
 213         if (site != NULL) {
 214                 rc = cl_site_init(site, &vdv->vdv_cl);
 215                 if (rc == 0)
 216                         rc = lu_site_init_finish(&site->cs_lu);
 217                 else {
 218                         LASSERT(lud->ld_site == NULL);
 219                         CERROR("Cannot init lu_site, rc %d.\n", rc);
 220                         OBD_FREE_PTR(site);
 221                 }
 222         } else
 223                 rc = -ENOMEM;
 224         if (rc != 0) {
 225                 vvp_device_free(env, lud);
 226                 lud = ERR_PTR(rc);
 227         }
 228         RETURN(lud);
 229 }
 230
 231 static int vvp_device_init(const struct lu_env *env, struct lu_device *d,
 232                            const char *name, struct lu_device *next)
 233 {
 234         struct vvp_device  *vdv;
 235         int rc;
 236         ENTRY;
 237
 238         vdv = lu2vvp_dev(d);
 239         vdv->vdv_next = lu2cl_dev(next);
 240
 241         LASSERT(d->ld_site != NULL && next->ld_type != NULL);
 242         next->ld_site = d->ld_site;
 243         rc = next->ld_type->ldt_ops->ldto_device_init(
 244                 env, next, next->ld_type->ldt_name, NULL);
 245         if (rc == 0) {
 246                 lu_device_get(next);
 247                 lu_ref_add(&next->ld_reference, "lu-stack", &lu_site_init);
 248         }
 249         RETURN(rc);
 250 }
 251
 252 static struct lu_device *vvp_device_fini(const struct lu_env *env,
 253                                          struct lu_device *d)
 254 {
 255         return cl2lu_dev(lu2vvp_dev(d)->vdv_next);
 256 }
 257
 258 static const struct lu_device_type_operations vvp_device_type_ops = {
 259         .ldto_init = vvp_type_init,
 260         .ldto_fini = vvp_type_fini,
 261
 262         .ldto_start = vvp_type_start,
 263         .ldto_stop  = vvp_type_stop,
 264
 265         .ldto_device_alloc      = vvp_device_alloc,
 266         .ldto_device_free       = vvp_device_free,
 267         .ldto_device_init       = vvp_device_init,
 268         .ldto_device_fini       = vvp_device_fini,
 269 };
 270
 271 struct lu_device_type vvp_device_type = {
 272         .ldt_tags     = LU_DEVICE_CL,
 273         .ldt_name     = LUSTRE_VVP_NAME,
 274         .ldt_ops      = &vvp_device_type_ops,
 275         .ldt_ctx_tags = LCT_CL_THREAD
 276 };
 277
 278 /**
 279  * A mutex serializing calls to vvp_inode_fini() under extreme memory
 280  * pressure, when environments cannot be allocated.
 281  */
 282 int vvp_global_init(void)
 283 {
 284         int rc;
 285
 286         rc = lu_kmem_init(vvp_caches);
 287         if (rc != 0)
 288                 return rc;
 289
 290         rc = lu_device_type_init(&vvp_device_type);
 291         if (rc != 0)
 292                 goto out_kmem;
 293
 294         return 0;
 295
 296 out_kmem:
 297         lu_kmem_fini(vvp_caches);
 298
 299         return rc;
 300 }
 301
 302 void vvp_global_fini(void)
 303 {
 304         lu_device_type_fini(&vvp_device_type);
 305         lu_kmem_fini(vvp_caches);
 306 }
 307
 308 /*****************************************************************************
 309  *
 310  * mirror obd-devices into cl devices.
 311  *
 312  */
 313
 314 int cl_sb_init(struct super_block *sb)
 315 {
 316         struct ll_sb_info *sbi;
 317         struct cl_device  *cl;
 318         struct lu_env     *env;
 319         int rc = 0;
 320         __u16 refcheck;
 321
 322         sbi  = ll_s2sbi(sb);
 323         env = cl_env_get(&refcheck);
 324         if (!IS_ERR(env)) {
 325                 cl = cl_type_setup(env, NULL, &vvp_device_type,
 326                                    sbi->ll_dt_exp->exp_obd->obd_lu_dev);
 327                 if (!IS_ERR(cl)) {
 328                         sbi->ll_cl = cl;
 329                         sbi->ll_site = cl2lu_dev(cl)->ld_site;
 330                 }
 331                 cl_env_put(env, &refcheck);
 332         } else
 333                 rc = PTR_ERR(env);
 334         RETURN(rc);
 335 }
 336
 337 int cl_sb_fini(struct super_block *sb)
 338 {
 339         struct ll_sb_info *sbi;
 340         struct lu_env     *env;
 341         struct cl_device  *cld;
 342         __u16              refcheck;
 343         int                result;
 344
 345         ENTRY;
 346         sbi = ll_s2sbi(sb);
 347         env = cl_env_get(&refcheck);
 348         if (!IS_ERR(env)) {
 349                 cld = sbi->ll_cl;
 350
 351                 if (cld != NULL) {
 352                         cl_stack_fini(env, cld);
 353                         sbi->ll_cl = NULL;
 354                         sbi->ll_site = NULL;
 355                 }
 356                 cl_env_put(env, &refcheck);
 357                 result = 0;
 358         } else {
 359                 CERROR("Cannot cleanup cl-stack due to memory shortage.\n");
 360                 result = PTR_ERR(env);
 361         }
 362
 363         RETURN(result);
 364 }
 365
 366 /****************************************************************************
 367  *
 368  * /proc/fs/lustre/llite/$MNT/dump_page_cache
 369  *
 370  ****************************************************************************/
 371
 372 /*
 373  * To represent contents of a page cache as a byte stream, following
 374  * information if encoded in 64bit offset:
 375  *
 376  *       - file hash bucket in lu_site::ls_hash[]       28bits
 377  *
 378  *       - how far file is from bucket head              4bits
 379  *
 380  *       - page index                                   32bits
 381  *
 382  * First two data identify a file in the cache uniquely.
 383  */
 384
 385 #define PGC_OBJ_SHIFT (32 + 4)
 386 #define PGC_DEPTH_SHIFT (32)
 387
 388 struct vvp_pgcache_id {
 389         unsigned                 vpi_bucket;
 390         unsigned                 vpi_depth;
 391         uint32_t                 vpi_index;
 392
 393         unsigned                 vpi_curdep;
 394         struct lu_object_header *vpi_obj;
 395 };
 396
 397 static void vvp_pgcache_id_unpack(loff_t pos, struct vvp_pgcache_id *id)
 398 {
 399         CLASSERT(sizeof(pos) == sizeof(__u64));
 400
 401         id->vpi_index  = pos & 0xffffffff;
 402         id->vpi_depth  = (pos >> PGC_DEPTH_SHIFT) & 0xf;
 403         id->vpi_bucket = ((unsigned long long)pos >> PGC_OBJ_SHIFT);
 404 }
 405
 406 static loff_t vvp_pgcache_id_pack(struct vvp_pgcache_id *id)
 407 {
 408         return
 409                 ((__u64)id->vpi_index) |
 410                 ((__u64)id->vpi_depth  << PGC_DEPTH_SHIFT) |
 411                 ((__u64)id->vpi_bucket << PGC_OBJ_SHIFT);
 412 }
 413
 414 static int vvp_pgcache_obj_get(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 415                                struct hlist_node *hnode, void *data)
 416 {
 417         struct vvp_pgcache_id   *id  = data;
 418         struct lu_object_header *hdr = cfs_hash_object(hs, hnode);
 419
 420         if (id->vpi_curdep-- > 0)
 421                 return 0; /* continue */
 422
 423         if (lu_object_is_dying(hdr))
 424                 return 1;
 425
 426         cfs_hash_get(hs, hnode);
 427         id->vpi_obj = hdr;
 428         return 1;
 429 }
 430
 431 static struct cl_object *vvp_pgcache_obj(const struct lu_env *env,
 432                                          struct lu_device *dev,
 433                                          struct vvp_pgcache_id *id)
 434 {
 435         LASSERT(lu_device_is_cl(dev));
 436
 437         id->vpi_depth &= 0xf;
 438         id->vpi_obj    = NULL;
 439         id->vpi_curdep = id->vpi_depth;
 440
 441         cfs_hash_hlist_for_each(dev->ld_site->ls_obj_hash, id->vpi_bucket,
 442                                 vvp_pgcache_obj_get, id);
 443         if (id->vpi_obj != NULL) {
 444                 struct lu_object *lu_obj;
 445
 446                 lu_obj = lu_object_locate(id->vpi_obj, dev->ld_type);
 447                 if (lu_obj != NULL) {
 448                         lu_object_ref_add(lu_obj, "dump", current);
 449                         return lu2cl(lu_obj);
 450                 }
 451                 lu_object_put(env, lu_object_top(id->vpi_obj));
 452
 453         } else if (id->vpi_curdep > 0) {
 454                 id->vpi_depth = 0xf;
 455         }
 456         return NULL;
 457 }
 458
 459 static loff_t vvp_pgcache_find(const struct lu_env *env,
 460                                struct lu_device *dev, loff_t pos)
 461 {
 462         struct cl_object     *clob;
 463         struct lu_site       *site;
 464         struct vvp_pgcache_id id;
 465
 466         site = dev->ld_site;
 467         vvp_pgcache_id_unpack(pos, &id);
 468
 469         while (1) {
 470                 if (id.vpi_bucket >= CFS_HASH_NHLIST(site->ls_obj_hash))
 471                         return ~0ULL;
 472                 clob = vvp_pgcache_obj(env, dev, &id);
 473                 if (clob != NULL) {
 474                         struct inode *inode = vvp_object_inode(clob);
 475                         struct page *vmpage;
 476                         int nr;
 477
 478                         nr = find_get_pages_contig(inode->i_mapping,
 479                                                    id.vpi_index, 1, &vmpage);
 480                         if (nr > 0) {
 481                                 id.vpi_index = vmpage->index;
 482                                 /* Cant support over 16T file */
 483                                 nr = !(vmpage->index > 0xffffffff);
 484                                 put_page(vmpage);
 485                         }
 486
 487                         lu_object_ref_del(&clob->co_lu, "dump", current);
 488                         cl_object_put(env, clob);
 489                         if (nr > 0)
 490                                 return vvp_pgcache_id_pack(&id);
 491                 }
 492                 /* to the next object. */
 493                 ++id.vpi_depth;
 494                 id.vpi_depth &= 0xf;
 495                 if (id.vpi_depth == 0 && ++id.vpi_bucket == 0)
 496                         return ~0ULL;
 497                 id.vpi_index = 0;
 498         }
 499 }
 500
 501 #define seq_page_flag(seq, page, flag, has_flags) do {                  \
 502         if (test_bit(PG_##flag, &(page)->flags)) {                  \
 503                 seq_printf(seq, "%s"#flag, has_flags ? "|" : "");       \
 504                 has_flags = 1;                                          \
 505         }                                                               \
 506 } while(0)
 507
 508 static void vvp_pgcache_page_show(const struct lu_env *env,
 509                                   struct seq_file *seq, struct cl_page *page)
 510 {
 511         struct vvp_page *vpg;
 512         struct page      *vmpage;
 513         int              has_flags;
 514
 515         vpg = cl2vvp_page(cl_page_at(page, &vvp_device_type));
 516         vmpage = vpg->vpg_page;
 517         seq_printf(seq, " %5i | %p %p %s %s %s | %p "DFID"(%p) %lu %u [",
 518                    0 /* gen */,
 519                    vpg, page,
 520                    "none",
 521                    vpg->vpg_defer_uptodate ? "du" : "- ",
 522                    PageWriteback(vmpage) ? "wb" : "-",
 523                    vmpage,
 524                    PFID(ll_inode2fid(vmpage->mapping->host)),
 525                    vmpage->mapping->host, vmpage->index,
 526                    page_count(vmpage));
 527         has_flags = 0;
 528         seq_page_flag(seq, vmpage, locked, has_flags);
 529         seq_page_flag(seq, vmpage, error, has_flags);
 530         seq_page_flag(seq, vmpage, referenced, has_flags);
 531         seq_page_flag(seq, vmpage, uptodate, has_flags);
 532         seq_page_flag(seq, vmpage, dirty, has_flags);
 533         seq_page_flag(seq, vmpage, writeback, has_flags);
 534         seq_printf(seq, "%s]\n", has_flags ? "" : "-");
 535 }
 536
 537 static int vvp_pgcache_show(struct seq_file *f, void *v)
 538 {
 539         loff_t                   pos;
 540         struct ll_sb_info       *sbi;
 541         struct cl_object        *clob;
 542         struct lu_env           *env;
 543         struct vvp_pgcache_id    id;
 544         __u16                    refcheck;
 545         int                      result;
 546
 547         env = cl_env_get(&refcheck);
 548         if (!IS_ERR(env)) {
 549                 pos = *(loff_t *) v;
 550                 vvp_pgcache_id_unpack(pos, &id);
 551                 sbi = f->private;
 552                 clob = vvp_pgcache_obj(env, &sbi->ll_cl->cd_lu_dev, &id);
 553                 if (clob != NULL) {
 554                         struct inode *inode = vvp_object_inode(clob);
 555                         struct cl_page *page = NULL;
 556                         struct page *vmpage;
 557
 558                         result = find_get_pages_contig(inode->i_mapping,
 559                                                       id.vpi_index, 1, &vmpage);
 560                         if (result > 0) {
 561                                 lock_page(vmpage);
 562                                 page = cl_vmpage_page(vmpage, clob);
 563                                 unlock_page(vmpage);
 564
 565                                 put_page(vmpage);
 566                         }
 567
 568                         seq_printf(f, "%8x@"DFID": ", id.vpi_index,
 569                                    PFID(lu_object_fid(&clob->co_lu)));
 570                         if (page != NULL) {
 571                                 vvp_pgcache_page_show(env, f, page);
 572                                 cl_page_put(env, page);
 573                         } else
 574                                 seq_puts(f, "missing\n");
 575                         lu_object_ref_del(&clob->co_lu, "dump", current);
 576                         cl_object_put(env, clob);
 577                 } else
 578                         seq_printf(f, "%llx missing\n", pos);
 579                 cl_env_put(env, &refcheck);
 580                 result = 0;
 581         } else
 582                 result = PTR_ERR(env);
 583         return result;
 584 }
 585
 586 static void *vvp_pgcache_start(struct seq_file *f, loff_t *pos)
 587 {
 588         struct ll_sb_info *sbi;
 589         struct lu_env     *env;
 590         __u16              refcheck;
 591
 592         sbi = f->private;
 593
 594         env = cl_env_get(&refcheck);
 595         if (!IS_ERR(env)) {
 596                 sbi = f->private;
 597                 if (sbi->ll_site->ls_obj_hash->hs_cur_bits > 64 - PGC_OBJ_SHIFT)
 598                         pos = ERR_PTR(-EFBIG);
 599                 else {
 600                         *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev,
 601                                                 *pos);
 602                         if (*pos == ~0ULL)
 603                                 pos = NULL;
 604                 }
 605                 cl_env_put(env, &refcheck);
 606         }
 607         return pos;
 608 }
 609
 610 static void *vvp_pgcache_next(struct seq_file *f, void *v, loff_t *pos)
 611 {
 612         struct ll_sb_info *sbi;
 613         struct lu_env     *env;
 614         __u16              refcheck;
 615
 616         env = cl_env_get(&refcheck);
 617         if (!IS_ERR(env)) {
 618                 sbi = f->private;
 619                 *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev, *pos + 1);
 620                 if (*pos == ~0ULL)
 621                         pos = NULL;
 622                 cl_env_put(env, &refcheck);
 623         }
 624         return pos;
 625 }
 626
 627 static void vvp_pgcache_stop(struct seq_file *f, void *v)
 628 {
 629         /* Nothing to do */
 630 }
 631
 632 static struct seq_operations vvp_pgcache_ops = {
 633         .start = vvp_pgcache_start,
 634         .next  = vvp_pgcache_next,
 635         .stop  = vvp_pgcache_stop,
 636         .show  = vvp_pgcache_show
 637 };
 638
 639 static int vvp_dump_pgcache_seq_open(struct inode *inode, struct file *filp)
 640 {
 641         struct ll_sb_info       *sbi = PDE_DATA(inode);
 642         struct seq_file         *seq;
 643         int                     result;
 644
 645         result = seq_open(filp, &vvp_pgcache_ops);
 646         if (result == 0) {
 647                 seq = filp->private_data;
 648                 seq->private = sbi;
 649         }
 650         return result;
 651 }
 652
 653 const struct file_operations vvp_dump_pgcache_file_ops = {
 654         .owner   = THIS_MODULE,
 655         .open    = vvp_dump_pgcache_seq_open,
 656         .read    = seq_read,
 657         .llseek  = seq_lseek,
 658         .release = seq_release,
 659 };