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, 2014, 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 struct kmem_cache *vvp_req_kmem;
  63 static struct kmem_cache *vvp_session_kmem;
  64 static struct kmem_cache *vvp_thread_kmem;
  65
  66 static struct lu_kmem_descr vvp_caches[] = {
  67         {
  68                 .ckd_cache = &ll_thread_kmem,
  69                 .ckd_name  = "ll_thread_kmem",
  70                 .ckd_size  = sizeof(struct ll_thread_info),
  71         },
  72         {
  73                 .ckd_cache = &vvp_lock_kmem,
  74                 .ckd_name  = "vvp_lock_kmem",
  75                 .ckd_size  = sizeof(struct vvp_lock),
  76         },
  77         {
  78                 .ckd_cache = &vvp_object_kmem,
  79                 .ckd_name  = "vvp_object_kmem",
  80                 .ckd_size  = sizeof(struct vvp_object),
  81         },
  82         {
  83                 .ckd_cache = &vvp_req_kmem,
  84                 .ckd_name  = "vvp_req_kmem",
  85                 .ckd_size  = sizeof(struct vvp_req),
  86         },
  87         {
  88                 .ckd_cache = &vvp_session_kmem,
  89                 .ckd_name  = "vvp_session_kmem",
  90                 .ckd_size  = sizeof (struct vvp_session)
  91         },
  92         {
  93                 .ckd_cache = &vvp_thread_kmem,
  94                 .ckd_name  = "vvp_thread_kmem",
  95                 .ckd_size  = sizeof(struct vvp_thread_info),
  96         },
  97         {
  98                 .ckd_cache = NULL
  99         }
 100 };
 101
 102 static void *ll_thread_key_init(const struct lu_context *ctx,
 103                                 struct lu_context_key *key)
 104 {
 105         struct ll_thread_info *lti;
 106
 107         OBD_SLAB_ALLOC_PTR_GFP(lti, ll_thread_kmem, GFP_NOFS);
 108         if (lti == NULL)
 109                 lti = ERR_PTR(-ENOMEM);
 110
 111         return lti;
 112 }
 113
 114 static void ll_thread_key_fini(const struct lu_context *ctx,
 115                                struct lu_context_key *key, void *data)
 116 {
 117         struct ll_thread_info *lti = data;
 118
 119         OBD_SLAB_FREE_PTR(lti, ll_thread_kmem);
 120 }
 121
 122 struct lu_context_key ll_thread_key = {
 123         .lct_tags = LCT_CL_THREAD,
 124         .lct_init = ll_thread_key_init,
 125         .lct_fini = ll_thread_key_fini,
 126 };
 127
 128 static void *vvp_session_key_init(const struct lu_context *ctx,
 129                                   struct lu_context_key *key)
 130 {
 131         struct vvp_session *session;
 132
 133         OBD_SLAB_ALLOC_PTR_GFP(session, vvp_session_kmem, GFP_NOFS);
 134         if (session == NULL)
 135                 session = ERR_PTR(-ENOMEM);
 136         return session;
 137 }
 138
 139 static void vvp_session_key_fini(const struct lu_context *ctx,
 140                                  struct lu_context_key *key, void *data)
 141 {
 142         struct vvp_session *session = data;
 143         OBD_SLAB_FREE_PTR(session, vvp_session_kmem);
 144 }
 145
 146 struct lu_context_key vvp_session_key = {
 147         .lct_tags = LCT_SESSION,
 148         .lct_init = vvp_session_key_init,
 149         .lct_fini = vvp_session_key_fini
 150 };
 151
 152 static void *vvp_thread_key_init(const struct lu_context *ctx,
 153                                  struct lu_context_key *key)
 154 {
 155         struct vvp_thread_info *vti;
 156
 157         OBD_SLAB_ALLOC_PTR_GFP(vti, vvp_thread_kmem, GFP_NOFS);
 158         if (vti == NULL)
 159                 vti = ERR_PTR(-ENOMEM);
 160         return vti;
 161 }
 162
 163 static void vvp_thread_key_fini(const struct lu_context *ctx,
 164                                 struct lu_context_key *key, void *data)
 165 {
 166         struct vvp_thread_info *vti = data;
 167         OBD_SLAB_FREE_PTR(vti, vvp_thread_kmem);
 168 }
 169
 170 struct lu_context_key vvp_thread_key = {
 171         .lct_tags = LCT_CL_THREAD,
 172         .lct_init = vvp_thread_key_init,
 173         .lct_fini = vvp_thread_key_fini,
 174 };
 175
 176 /* type constructor/destructor: vvp_type_{init,fini,start,stop}(). */
 177 LU_TYPE_INIT_FINI(vvp, &ll_thread_key, &vvp_session_key, &vvp_thread_key);
 178
 179 static const struct lu_device_operations vvp_lu_ops = {
 180         .ldo_object_alloc      = vvp_object_alloc
 181 };
 182
 183 static const struct cl_device_operations vvp_cl_ops = {
 184         .cdo_req_init = vvp_req_init,
 185 };
 186
 187 static struct lu_device *vvp_device_free(const struct lu_env *env,
 188                                          struct lu_device *d)
 189 {
 190         struct vvp_device *vdv  = lu2vvp_dev(d);
 191         struct cl_site    *site = lu2cl_site(d->ld_site);
 192         struct lu_device  *next = cl2lu_dev(vdv->vdv_next);
 193
 194         if (d->ld_site != NULL) {
 195                 cl_site_fini(site);
 196                 OBD_FREE_PTR(site);
 197         }
 198
 199         cl_device_fini(lu2cl_dev(d));
 200         OBD_FREE_PTR(vdv);
 201         return next;
 202 }
 203
 204 static struct lu_device *vvp_device_alloc(const struct lu_env *env,
 205                                           struct lu_device_type *t,
 206                                           struct lustre_cfg *cfg)
 207 {
 208         struct vvp_device *vdv;
 209         struct lu_device *lud;
 210         struct cl_site *site;
 211         int rc;
 212         ENTRY;
 213
 214         OBD_ALLOC_PTR(vdv);
 215         if (vdv == NULL)
 216                 RETURN(ERR_PTR(-ENOMEM));
 217
 218         lud = &vdv->vdv_cl.cd_lu_dev;
 219         cl_device_init(&vdv->vdv_cl, t);
 220         vvp2lu_dev(vdv)->ld_ops = &vvp_lu_ops;
 221         vdv->vdv_cl.cd_ops = &vvp_cl_ops;
 222
 223         OBD_ALLOC_PTR(site);
 224         if (site != NULL) {
 225                 rc = cl_site_init(site, &vdv->vdv_cl);
 226                 if (rc == 0)
 227                         rc = lu_site_init_finish(&site->cs_lu);
 228                 else {
 229                         LASSERT(lud->ld_site == NULL);
 230                         CERROR("Cannot init lu_site, rc %d.\n", rc);
 231                         OBD_FREE_PTR(site);
 232                 }
 233         } else
 234                 rc = -ENOMEM;
 235         if (rc != 0) {
 236                 vvp_device_free(env, lud);
 237                 lud = ERR_PTR(rc);
 238         }
 239         RETURN(lud);
 240 }
 241
 242 static int vvp_device_init(const struct lu_env *env, struct lu_device *d,
 243                            const char *name, struct lu_device *next)
 244 {
 245         struct vvp_device  *vdv;
 246         int rc;
 247         ENTRY;
 248
 249         vdv = lu2vvp_dev(d);
 250         vdv->vdv_next = lu2cl_dev(next);
 251
 252         LASSERT(d->ld_site != NULL && next->ld_type != NULL);
 253         next->ld_site = d->ld_site;
 254         rc = next->ld_type->ldt_ops->ldto_device_init(
 255                 env, next, next->ld_type->ldt_name, NULL);
 256         if (rc == 0) {
 257                 lu_device_get(next);
 258                 lu_ref_add(&next->ld_reference, "lu-stack", &lu_site_init);
 259         }
 260         RETURN(rc);
 261 }
 262
 263 static struct lu_device *vvp_device_fini(const struct lu_env *env,
 264                                          struct lu_device *d)
 265 {
 266         return cl2lu_dev(lu2vvp_dev(d)->vdv_next);
 267 }
 268
 269 static const struct lu_device_type_operations vvp_device_type_ops = {
 270         .ldto_init = vvp_type_init,
 271         .ldto_fini = vvp_type_fini,
 272
 273         .ldto_start = vvp_type_start,
 274         .ldto_stop  = vvp_type_stop,
 275
 276         .ldto_device_alloc      = vvp_device_alloc,
 277         .ldto_device_free       = vvp_device_free,
 278         .ldto_device_init       = vvp_device_init,
 279         .ldto_device_fini       = vvp_device_fini,
 280 };
 281
 282 struct lu_device_type vvp_device_type = {
 283         .ldt_tags     = LU_DEVICE_CL,
 284         .ldt_name     = LUSTRE_VVP_NAME,
 285         .ldt_ops      = &vvp_device_type_ops,
 286         .ldt_ctx_tags = LCT_CL_THREAD
 287 };
 288
 289 /**
 290  * A mutex serializing calls to vvp_inode_fini() under extreme memory
 291  * pressure, when environments cannot be allocated.
 292  */
 293 int vvp_global_init(void)
 294 {
 295         int rc;
 296
 297         rc = lu_kmem_init(vvp_caches);
 298         if (rc != 0)
 299                 return rc;
 300
 301         rc = lu_device_type_init(&vvp_device_type);
 302         if (rc != 0)
 303                 goto out_kmem;
 304
 305         return 0;
 306
 307 out_kmem:
 308         lu_kmem_fini(vvp_caches);
 309
 310         return rc;
 311 }
 312
 313 void vvp_global_fini(void)
 314 {
 315         lu_device_type_fini(&vvp_device_type);
 316         lu_kmem_fini(vvp_caches);
 317 }
 318
 319 /*****************************************************************************
 320  *
 321  * mirror obd-devices into cl devices.
 322  *
 323  */
 324
 325 int cl_sb_init(struct super_block *sb)
 326 {
 327         struct ll_sb_info *sbi;
 328         struct cl_device  *cl;
 329         struct lu_env     *env;
 330         int rc = 0;
 331         int refcheck;
 332
 333         sbi  = ll_s2sbi(sb);
 334         env = cl_env_get(&refcheck);
 335         if (!IS_ERR(env)) {
 336                 cl = cl_type_setup(env, NULL, &vvp_device_type,
 337                                    sbi->ll_dt_exp->exp_obd->obd_lu_dev);
 338                 if (!IS_ERR(cl)) {
 339                         cl2vvp_dev(cl)->vdv_sb = sb;
 340                         sbi->ll_cl = cl;
 341                         sbi->ll_site = cl2lu_dev(cl)->ld_site;
 342                 }
 343                 cl_env_put(env, &refcheck);
 344         } else
 345                 rc = PTR_ERR(env);
 346         RETURN(rc);
 347 }
 348
 349 int cl_sb_fini(struct super_block *sb)
 350 {
 351         struct ll_sb_info *sbi;
 352         struct lu_env     *env;
 353         struct cl_device  *cld;
 354         int                refcheck;
 355         int                result;
 356
 357         ENTRY;
 358         sbi = ll_s2sbi(sb);
 359         env = cl_env_get(&refcheck);
 360         if (!IS_ERR(env)) {
 361                 cld = sbi->ll_cl;
 362
 363                 if (cld != NULL) {
 364                         cl_stack_fini(env, cld);
 365                         sbi->ll_cl = NULL;
 366                         sbi->ll_site = NULL;
 367                 }
 368                 cl_env_put(env, &refcheck);
 369                 result = 0;
 370         } else {
 371                 CERROR("Cannot cleanup cl-stack due to memory shortage.\n");
 372                 result = PTR_ERR(env);
 373         }
 374
 375         RETURN(result);
 376 }
 377
 378 /****************************************************************************
 379  *
 380  * /proc/fs/lustre/llite/$MNT/dump_page_cache
 381  *
 382  ****************************************************************************/
 383
 384 /*
 385  * To represent contents of a page cache as a byte stream, following
 386  * information if encoded in 64bit offset:
 387  *
 388  *       - file hash bucket in lu_site::ls_hash[]       28bits
 389  *
 390  *       - how far file is from bucket head              4bits
 391  *
 392  *       - page index                                   32bits
 393  *
 394  * First two data identify a file in the cache uniquely.
 395  */
 396
 397 #define PGC_OBJ_SHIFT (32 + 4)
 398 #define PGC_DEPTH_SHIFT (32)
 399
 400 struct vvp_pgcache_id {
 401         unsigned                 vpi_bucket;
 402         unsigned                 vpi_depth;
 403         uint32_t                 vpi_index;
 404
 405         unsigned                 vpi_curdep;
 406         struct lu_object_header *vpi_obj;
 407 };
 408
 409 static void vvp_pgcache_id_unpack(loff_t pos, struct vvp_pgcache_id *id)
 410 {
 411         CLASSERT(sizeof(pos) == sizeof(__u64));
 412
 413         id->vpi_index  = pos & 0xffffffff;
 414         id->vpi_depth  = (pos >> PGC_DEPTH_SHIFT) & 0xf;
 415         id->vpi_bucket = ((unsigned long long)pos >> PGC_OBJ_SHIFT);
 416 }
 417
 418 static loff_t vvp_pgcache_id_pack(struct vvp_pgcache_id *id)
 419 {
 420         return
 421                 ((__u64)id->vpi_index) |
 422                 ((__u64)id->vpi_depth  << PGC_DEPTH_SHIFT) |
 423                 ((__u64)id->vpi_bucket << PGC_OBJ_SHIFT);
 424 }
 425
 426 static int vvp_pgcache_obj_get(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 427                                struct hlist_node *hnode, void *data)
 428 {
 429         struct vvp_pgcache_id   *id  = data;
 430         struct lu_object_header *hdr = cfs_hash_object(hs, hnode);
 431
 432         if (id->vpi_curdep-- > 0)
 433                 return 0; /* continue */
 434
 435         if (lu_object_is_dying(hdr))
 436                 return 1;
 437
 438         cfs_hash_get(hs, hnode);
 439         id->vpi_obj = hdr;
 440         return 1;
 441 }
 442
 443 static struct cl_object *vvp_pgcache_obj(const struct lu_env *env,
 444                                          struct lu_device *dev,
 445                                          struct vvp_pgcache_id *id)
 446 {
 447         LASSERT(lu_device_is_cl(dev));
 448
 449         id->vpi_depth &= 0xf;
 450         id->vpi_obj    = NULL;
 451         id->vpi_curdep = id->vpi_depth;
 452
 453         cfs_hash_hlist_for_each(dev->ld_site->ls_obj_hash, id->vpi_bucket,
 454                                 vvp_pgcache_obj_get, id);
 455         if (id->vpi_obj != NULL) {
 456                 struct lu_object *lu_obj;
 457
 458                 lu_obj = lu_object_locate(id->vpi_obj, dev->ld_type);
 459                 if (lu_obj != NULL) {
 460                         lu_object_ref_add(lu_obj, "dump", current);
 461                         return lu2cl(lu_obj);
 462                 }
 463                 lu_object_put(env, lu_object_top(id->vpi_obj));
 464
 465         } else if (id->vpi_curdep > 0) {
 466                 id->vpi_depth = 0xf;
 467         }
 468         return NULL;
 469 }
 470
 471 static loff_t vvp_pgcache_find(const struct lu_env *env,
 472                                struct lu_device *dev, loff_t pos)
 473 {
 474         struct cl_object     *clob;
 475         struct lu_site       *site;
 476         struct vvp_pgcache_id id;
 477
 478         site = dev->ld_site;
 479         vvp_pgcache_id_unpack(pos, &id);
 480
 481         while (1) {
 482                 if (id.vpi_bucket >= CFS_HASH_NHLIST(site->ls_obj_hash))
 483                         return ~0ULL;
 484                 clob = vvp_pgcache_obj(env, dev, &id);
 485                 if (clob != NULL) {
 486                         struct inode *inode = vvp_object_inode(clob);
 487                         struct page *vmpage;
 488                         int nr;
 489
 490                         nr = find_get_pages_contig(inode->i_mapping,
 491                                                    id.vpi_index, 1, &vmpage);
 492                         if (nr > 0) {
 493                                 id.vpi_index = vmpage->index;
 494                                 /* Cant support over 16T file */
 495                                 nr = !(vmpage->index > 0xffffffff);
 496                                 page_cache_release(vmpage);
 497                         }
 498
 499                         lu_object_ref_del(&clob->co_lu, "dump", current);
 500                         cl_object_put(env, clob);
 501                         if (nr > 0)
 502                                 return vvp_pgcache_id_pack(&id);
 503                 }
 504                 /* to the next object. */
 505                 ++id.vpi_depth;
 506                 id.vpi_depth &= 0xf;
 507                 if (id.vpi_depth == 0 && ++id.vpi_bucket == 0)
 508                         return ~0ULL;
 509                 id.vpi_index = 0;
 510         }
 511 }
 512
 513 #define seq_page_flag(seq, page, flag, has_flags) do {                  \
 514         if (test_bit(PG_##flag, &(page)->flags)) {                  \
 515                 seq_printf(seq, "%s"#flag, has_flags ? "|" : "");       \
 516                 has_flags = 1;                                          \
 517         }                                                               \
 518 } while(0)
 519
 520 static void vvp_pgcache_page_show(const struct lu_env *env,
 521                                   struct seq_file *seq, struct cl_page *page)
 522 {
 523         struct vvp_page *vpg;
 524         struct page      *vmpage;
 525         int              has_flags;
 526
 527         vpg = cl2vvp_page(cl_page_at(page, &vvp_device_type));
 528         vmpage = vpg->vpg_page;
 529         seq_printf(seq, " %5i | %p %p %s %s %s | %p "DFID"(%p) %lu %u [",
 530                    0 /* gen */,
 531                    vpg, page,
 532                    "none",
 533                    vpg->vpg_defer_uptodate ? "du" : "- ",
 534                    PageWriteback(vmpage) ? "wb" : "-",
 535                    vmpage,
 536                    PFID(ll_inode2fid(vmpage->mapping->host)),
 537                    vmpage->mapping->host, vmpage->index,
 538                    page_count(vmpage));
 539         has_flags = 0;
 540         seq_page_flag(seq, vmpage, locked, has_flags);
 541         seq_page_flag(seq, vmpage, error, has_flags);
 542         seq_page_flag(seq, vmpage, referenced, has_flags);
 543         seq_page_flag(seq, vmpage, uptodate, has_flags);
 544         seq_page_flag(seq, vmpage, dirty, has_flags);
 545         seq_page_flag(seq, vmpage, writeback, has_flags);
 546         seq_printf(seq, "%s]\n", has_flags ? "" : "-");
 547 }
 548
 549 static int vvp_pgcache_show(struct seq_file *f, void *v)
 550 {
 551         loff_t                   pos;
 552         struct ll_sb_info       *sbi;
 553         struct cl_object        *clob;
 554         struct lu_env           *env;
 555         struct vvp_pgcache_id    id;
 556         int                      refcheck;
 557         int                      result;
 558
 559         env = cl_env_get(&refcheck);
 560         if (!IS_ERR(env)) {
 561                 pos = *(loff_t *) v;
 562                 vvp_pgcache_id_unpack(pos, &id);
 563                 sbi = f->private;
 564                 clob = vvp_pgcache_obj(env, &sbi->ll_cl->cd_lu_dev, &id);
 565                 if (clob != NULL) {
 566                         struct inode *inode = vvp_object_inode(clob);
 567                         struct cl_page *page = NULL;
 568                         struct page *vmpage;
 569
 570                         result = find_get_pages_contig(inode->i_mapping,
 571                                                       id.vpi_index, 1, &vmpage);
 572                         if (result > 0) {
 573                                 lock_page(vmpage);
 574                                 page = cl_vmpage_page(vmpage, clob);
 575                                 unlock_page(vmpage);
 576
 577                                 page_cache_release(vmpage);
 578                         }
 579
 580                         seq_printf(f, "%8x@"DFID": ", id.vpi_index,
 581                                    PFID(lu_object_fid(&clob->co_lu)));
 582                         if (page != NULL) {
 583                                 vvp_pgcache_page_show(env, f, page);
 584                                 cl_page_put(env, page);
 585                         } else
 586                                 seq_puts(f, "missing\n");
 587                         lu_object_ref_del(&clob->co_lu, "dump", current);
 588                         cl_object_put(env, clob);
 589                 } else
 590                         seq_printf(f, "%llx missing\n", pos);
 591                 cl_env_put(env, &refcheck);
 592                 result = 0;
 593         } else
 594                 result = PTR_ERR(env);
 595         return result;
 596 }
 597
 598 static void *vvp_pgcache_start(struct seq_file *f, loff_t *pos)
 599 {
 600         struct ll_sb_info *sbi;
 601         struct lu_env     *env;
 602         int                refcheck;
 603
 604         sbi = f->private;
 605
 606         env = cl_env_get(&refcheck);
 607         if (!IS_ERR(env)) {
 608                 sbi = f->private;
 609                 if (sbi->ll_site->ls_obj_hash->hs_cur_bits > 64 - PGC_OBJ_SHIFT)
 610                         pos = ERR_PTR(-EFBIG);
 611                 else {
 612                         *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev,
 613                                                 *pos);
 614                         if (*pos == ~0ULL)
 615                                 pos = NULL;
 616                 }
 617                 cl_env_put(env, &refcheck);
 618         }
 619         return pos;
 620 }
 621
 622 static void *vvp_pgcache_next(struct seq_file *f, void *v, loff_t *pos)
 623 {
 624         struct ll_sb_info *sbi;
 625         struct lu_env     *env;
 626         int                refcheck;
 627
 628         env = cl_env_get(&refcheck);
 629         if (!IS_ERR(env)) {
 630                 sbi = f->private;
 631                 *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev, *pos + 1);
 632                 if (*pos == ~0ULL)
 633                         pos = NULL;
 634                 cl_env_put(env, &refcheck);
 635         }
 636         return pos;
 637 }
 638
 639 static void vvp_pgcache_stop(struct seq_file *f, void *v)
 640 {
 641         /* Nothing to do */
 642 }
 643
 644 static struct seq_operations vvp_pgcache_ops = {
 645         .start = vvp_pgcache_start,
 646         .next  = vvp_pgcache_next,
 647         .stop  = vvp_pgcache_stop,
 648         .show  = vvp_pgcache_show
 649 };
 650
 651 static int vvp_dump_pgcache_seq_open(struct inode *inode, struct file *filp)
 652 {
 653         struct ll_sb_info       *sbi = PDE_DATA(inode);
 654         struct seq_file         *seq;
 655         int                     result;
 656
 657         result = seq_open(filp, &vvp_pgcache_ops);
 658         if (result == 0) {
 659                 seq = filp->private_data;
 660                 seq->private = sbi;
 661         }
 662         return result;
 663 }
 664
 665 const struct file_operations vvp_dump_pgcache_file_ops = {
 666         .owner   = THIS_MODULE,
 667         .open    = vvp_dump_pgcache_seq_open,
 668         .read    = seq_read,
 669         .llseek  = seq_lseek,
 670         .release = seq_release,
 671 };