fs/nfs/pagelist.c

   1 /*
   2  * linux/fs/nfs/pagelist.c
   3  *
   4  * A set of helper functions for managing NFS read and write requests.
   5  * The main purpose of these routines is to provide support for the
   6  * coalescing of several requests into a single RPC call.
   7  *
   8  * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
   9  *
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/file.h>
  14 #include <linux/sched.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/nfs.h>
  17 #include <linux/nfs3.h>
  18 #include <linux/nfs4.h>
  19 #include <linux/nfs_page.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_mount.h>
  22 #include <linux/export.h>
  23
  24 #include "internal.h"
  25 #include "pnfs.h"
  26
  27 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  28
  29 static struct kmem_cache *nfs_page_cachep;
  30 static const struct rpc_call_ops nfs_pgio_common_ops;
  31
  32 static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
  33 {
  34         p->npages = pagecount;
  35         if (pagecount <= ARRAY_SIZE(p->page_array))
  36                 p->pagevec = p->page_array;
  37         else {
  38                 p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
  39                 if (!p->pagevec)
  40                         p->npages = 0;
  41         }
  42         return p->pagevec != NULL;
  43 }
  44
  45 struct nfs_pgio_mirror *
  46 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
  47 {
  48         return nfs_pgio_has_mirroring(desc) ?
  49                 &desc->pg_mirrors[desc->pg_mirror_idx] :
  50                 &desc->pg_mirrors[0];
  51 }
  52 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
  53
  54 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  55                        struct nfs_pgio_header *hdr,
  56                        void (*release)(struct nfs_pgio_header *hdr))
  57 {
  58         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
  59
  60
  61         hdr->req = nfs_list_entry(mirror->pg_list.next);
  62         hdr->inode = desc->pg_inode;
  63         hdr->cred = hdr->req->wb_context->cred;
  64         hdr->io_start = req_offset(hdr->req);
  65         hdr->good_bytes = mirror->pg_count;
  66         hdr->dreq = desc->pg_dreq;
  67         hdr->layout_private = desc->pg_layout_private;
  68         hdr->release = release;
  69         hdr->completion_ops = desc->pg_completion_ops;
  70         if (hdr->completion_ops->init_hdr)
  71                 hdr->completion_ops->init_hdr(hdr);
  72
  73         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
  74 }
  75 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
  76
  77 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
  78 {
  79         spin_lock(&hdr->lock);
  80         if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags)
  81             || pos < hdr->io_start + hdr->good_bytes) {
  82                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
  83                 hdr->good_bytes = pos - hdr->io_start;
  84                 hdr->error = error;
  85         }
  86         spin_unlock(&hdr->lock);
  87 }
  88
  89 static inline struct nfs_page *
  90 nfs_page_alloc(void)
  91 {
  92         struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
  93         if (p)
  94                 INIT_LIST_HEAD(&p->wb_list);
  95         return p;
  96 }
  97
  98 static inline void
  99 nfs_page_free(struct nfs_page *p)
 100 {
 101         kmem_cache_free(nfs_page_cachep, p);
 102 }
 103
 104 /**
 105  * nfs_iocounter_wait - wait for i/o to complete
 106  * @l_ctx: nfs_lock_context with io_counter to use
 107  *
 108  * returns -ERESTARTSYS if interrupted by a fatal signal.
 109  * Otherwise returns 0 once the io_count hits 0.
 110  */
 111 int
 112 nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
 113 {
 114         return wait_on_atomic_t(&l_ctx->io_count, nfs_wait_atomic_killable,
 115                         TASK_KILLABLE);
 116 }
 117
 118 /*
 119  * nfs_page_group_lock - lock the head of the page group
 120  * @req - request in group that is to be locked
 121  * @nonblock - if true don't block waiting for lock
 122  *
 123  * this lock must be held if modifying the page group list
 124  *
 125  * return 0 on success, < 0 on error: -EDELAY if nonblocking or the
 126  * result from wait_on_bit_lock
 127  *
 128  * NOTE: calling with nonblock=false should always have set the
 129  *       lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
 130  *       with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
 131  */
 132 int
 133 nfs_page_group_lock(struct nfs_page *req, bool nonblock)
 134 {
 135         struct nfs_page *head = req->wb_head;
 136
 137         WARN_ON_ONCE(head != head->wb_head);
 138
 139         if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
 140                 return 0;
 141
 142         if (!nonblock)
 143                 return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
 144                                 TASK_UNINTERRUPTIBLE);
 145
 146         return -EAGAIN;
 147 }
 148
 149 /*
 150  * nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
 151  * @req - a request in the group
 152  *
 153  * This is a blocking call to wait for the group lock to be cleared.
 154  */
 155 void
 156 nfs_page_group_lock_wait(struct nfs_page *req)
 157 {
 158         struct nfs_page *head = req->wb_head;
 159
 160         WARN_ON_ONCE(head != head->wb_head);
 161
 162         wait_on_bit(&head->wb_flags, PG_HEADLOCK,
 163                 TASK_UNINTERRUPTIBLE);
 164 }
 165
 166 /*
 167  * nfs_page_group_unlock - unlock the head of the page group
 168  * @req - request in group that is to be unlocked
 169  */
 170 void
 171 nfs_page_group_unlock(struct nfs_page *req)
 172 {
 173         struct nfs_page *head = req->wb_head;
 174
 175         WARN_ON_ONCE(head != head->wb_head);
 176
 177         smp_mb__before_atomic();
 178         clear_bit(PG_HEADLOCK, &head->wb_flags);
 179         smp_mb__after_atomic();
 180         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
 181 }
 182
 183 /*
 184  * nfs_page_group_sync_on_bit_locked
 185  *
 186  * must be called with page group lock held
 187  */
 188 static bool
 189 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 190 {
 191         struct nfs_page *head = req->wb_head;
 192         struct nfs_page *tmp;
 193
 194         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 195         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 196
 197         tmp = req->wb_this_page;
 198         while (tmp != req) {
 199                 if (!test_bit(bit, &tmp->wb_flags))
 200                         return false;
 201                 tmp = tmp->wb_this_page;
 202         }
 203
 204         /* true! reset all bits */
 205         tmp = req;
 206         do {
 207                 clear_bit(bit, &tmp->wb_flags);
 208                 tmp = tmp->wb_this_page;
 209         } while (tmp != req);
 210
 211         return true;
 212 }
 213
 214 /*
 215  * nfs_page_group_sync_on_bit - set bit on current request, but only
 216  *   return true if the bit is set for all requests in page group
 217  * @req - request in page group
 218  * @bit - PG_* bit that is used to sync page group
 219  */
 220 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 221 {
 222         bool ret;
 223
 224         nfs_page_group_lock(req, false);
 225         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 226         nfs_page_group_unlock(req);
 227
 228         return ret;
 229 }
 230
 231 /*
 232  * nfs_page_group_init - Initialize the page group linkage for @req
 233  * @req - a new nfs request
 234  * @prev - the previous request in page group, or NULL if @req is the first
 235  *         or only request in the group (the head).
 236  */
 237 static inline void
 238 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 239 {
 240         struct inode *inode;
 241         WARN_ON_ONCE(prev == req);
 242
 243         if (!prev) {
 244                 /* a head request */
 245                 req->wb_head = req;
 246                 req->wb_this_page = req;
 247         } else {
 248                 /* a subrequest */
 249                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 250                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 251                 req->wb_head = prev->wb_head;
 252                 req->wb_this_page = prev->wb_this_page;
 253                 prev->wb_this_page = req;
 254
 255                 /* All subrequests take a ref on the head request until
 256                  * nfs_page_group_destroy is called */
 257                 kref_get(&req->wb_head->wb_kref);
 258
 259                 /* grab extra ref and bump the request count if head request
 260                  * has extra ref from the write/commit path to handle handoff
 261                  * between write and commit lists. */
 262                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 263                         inode = page_file_mapping(req->wb_page)->host;
 264                         set_bit(PG_INODE_REF, &req->wb_flags);
 265                         kref_get(&req->wb_kref);
 266                         spin_lock(&inode->i_lock);
 267                         NFS_I(inode)->nrequests++;
 268                         spin_unlock(&inode->i_lock);
 269                 }
 270         }
 271 }
 272
 273 /*
 274  * nfs_page_group_destroy - sync the destruction of page groups
 275  * @req - request that no longer needs the page group
 276  *
 277  * releases the page group reference from each member once all
 278  * members have called this function.
 279  */
 280 static void
 281 nfs_page_group_destroy(struct kref *kref)
 282 {
 283         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 284         struct nfs_page *tmp, *next;
 285
 286         /* subrequests must release the ref on the head request */
 287         if (req->wb_head != req)
 288                 nfs_release_request(req->wb_head);
 289
 290         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 291                 return;
 292
 293         tmp = req;
 294         do {
 295                 next = tmp->wb_this_page;
 296                 /* unlink and free */
 297                 tmp->wb_this_page = tmp;
 298                 tmp->wb_head = tmp;
 299                 nfs_free_request(tmp);
 300                 tmp = next;
 301         } while (tmp != req);
 302 }
 303
 304 /**
 305  * nfs_create_request - Create an NFS read/write request.
 306  * @ctx: open context to use
 307  * @page: page to write
 308  * @last: last nfs request created for this page group or NULL if head
 309  * @offset: starting offset within the page for the write
 310  * @count: number of bytes to read/write
 311  *
 312  * The page must be locked by the caller. This makes sure we never
 313  * create two different requests for the same page.
 314  * User should ensure it is safe to sleep in this function.
 315  */
 316 struct nfs_page *
 317 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 318                    struct nfs_page *last, unsigned int offset,
 319                    unsigned int count)
 320 {
 321         struct nfs_page         *req;
 322         struct nfs_lock_context *l_ctx;
 323
 324         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 325                 return ERR_PTR(-EBADF);
 326         /* try to allocate the request struct */
 327         req = nfs_page_alloc();
 328         if (req == NULL)
 329                 return ERR_PTR(-ENOMEM);
 330
 331         /* get lock context early so we can deal with alloc failures */
 332         l_ctx = nfs_get_lock_context(ctx);
 333         if (IS_ERR(l_ctx)) {
 334                 nfs_page_free(req);
 335                 return ERR_CAST(l_ctx);
 336         }
 337         req->wb_lock_context = l_ctx;
 338         atomic_inc(&l_ctx->io_count);
 339
 340         /* Initialize the request struct. Initially, we assume a
 341          * long write-back delay. This will be adjusted in
 342          * update_nfs_request below if the region is not locked. */
 343         req->wb_page    = page;
 344         req->wb_index   = page_file_index(page);
 345         get_page(page);
 346         req->wb_offset  = offset;
 347         req->wb_pgbase  = offset;
 348         req->wb_bytes   = count;
 349         req->wb_context = get_nfs_open_context(ctx);
 350         kref_init(&req->wb_kref);
 351         nfs_page_group_init(req, last);
 352         return req;
 353 }
 354
 355 /**
 356  * nfs_unlock_request - Unlock request and wake up sleepers.
 357  * @req:
 358  */
 359 void nfs_unlock_request(struct nfs_page *req)
 360 {
 361         if (!NFS_WBACK_BUSY(req)) {
 362                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 363                 BUG();
 364         }
 365         smp_mb__before_atomic();
 366         clear_bit(PG_BUSY, &req->wb_flags);
 367         smp_mb__after_atomic();
 368         wake_up_bit(&req->wb_flags, PG_BUSY);
 369 }
 370
 371 /**
 372  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 373  * @req:
 374  */
 375 void nfs_unlock_and_release_request(struct nfs_page *req)
 376 {
 377         nfs_unlock_request(req);
 378         nfs_release_request(req);
 379 }
 380
 381 /*
 382  * nfs_clear_request - Free up all resources allocated to the request
 383  * @req:
 384  *
 385  * Release page and open context resources associated with a read/write
 386  * request after it has completed.
 387  */
 388 static void nfs_clear_request(struct nfs_page *req)
 389 {
 390         struct page *page = req->wb_page;
 391         struct nfs_open_context *ctx = req->wb_context;
 392         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 393
 394         if (page != NULL) {
 395                 put_page(page);
 396                 req->wb_page = NULL;
 397         }
 398         if (l_ctx != NULL) {
 399                 if (atomic_dec_and_test(&l_ctx->io_count))
 400                         wake_up_atomic_t(&l_ctx->io_count);
 401                 nfs_put_lock_context(l_ctx);
 402                 req->wb_lock_context = NULL;
 403         }
 404         if (ctx != NULL) {
 405                 put_nfs_open_context(ctx);
 406                 req->wb_context = NULL;
 407         }
 408 }
 409
 410 /**
 411  * nfs_release_request - Release the count on an NFS read/write request
 412  * @req: request to release
 413  *
 414  * Note: Should never be called with the spinlock held!
 415  */
 416 void nfs_free_request(struct nfs_page *req)
 417 {
 418         WARN_ON_ONCE(req->wb_this_page != req);
 419
 420         /* extra debug: make sure no sync bits are still set */
 421         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 422         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 423         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 424         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 425         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 426
 427         /* Release struct file and open context */
 428         nfs_clear_request(req);
 429         nfs_page_free(req);
 430 }
 431
 432 void nfs_release_request(struct nfs_page *req)
 433 {
 434         kref_put(&req->wb_kref, nfs_page_group_destroy);
 435 }
 436
 437 /**
 438  * nfs_wait_on_request - Wait for a request to complete.
 439  * @req: request to wait upon.
 440  *
 441  * Interruptible by fatal signals only.
 442  * The user is responsible for holding a count on the request.
 443  */
 444 int
 445 nfs_wait_on_request(struct nfs_page *req)
 446 {
 447         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 448                               TASK_UNINTERRUPTIBLE);
 449 }
 450
 451 /*
 452  * nfs_generic_pg_test - determine if requests can be coalesced
 453  * @desc: pointer to descriptor
 454  * @prev: previous request in desc, or NULL
 455  * @req: this request
 456  *
 457  * Returns zero if @req can be coalesced into @desc, otherwise it returns
 458  * the size of the request.
 459  */
 460 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 461                            struct nfs_page *prev, struct nfs_page *req)
 462 {
 463         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 464
 465
 466         if (mirror->pg_count > mirror->pg_bsize) {
 467                 /* should never happen */
 468                 WARN_ON_ONCE(1);
 469                 return 0;
 470         }
 471
 472         /*
 473          * Limit the request size so that we can still allocate a page array
 474          * for it without upsetting the slab allocator.
 475          */
 476         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 477                         sizeof(struct page *) > PAGE_SIZE)
 478                 return 0;
 479
 480         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 481 }
 482 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 483
 484 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 485 {
 486         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 487
 488         if (hdr) {
 489                 INIT_LIST_HEAD(&hdr->pages);
 490                 spin_lock_init(&hdr->lock);
 491                 hdr->rw_ops = ops;
 492         }
 493         return hdr;
 494 }
 495 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 496
 497 /*
 498  * nfs_pgio_header_free - Free a read or write header
 499  * @hdr: The header to free
 500  */
 501 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 502 {
 503         hdr->rw_ops->rw_free_header(hdr);
 504 }
 505 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 506
 507 /**
 508  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 509  *
 510  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 511  * be called again.
 512  *
 513  * @hdr: A header that has had nfs_generic_pgio called
 514  */
 515 void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 516 {
 517         if (hdr->args.context)
 518                 put_nfs_open_context(hdr->args.context);
 519         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 520                 kfree(hdr->page_array.pagevec);
 521 }
 522 EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
 523
 524 /**
 525  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 526  * @hdr: The pageio hdr
 527  * @count: Number of bytes to read
 528  * @offset: Initial offset
 529  * @how: How to commit data (writes only)
 530  * @cinfo: Commit information for the call (writes only)
 531  */
 532 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 533                               unsigned int count, unsigned int offset,
 534                               int how, struct nfs_commit_info *cinfo)
 535 {
 536         struct nfs_page *req = hdr->req;
 537
 538         /* Set up the RPC argument and reply structs
 539          * NB: take care not to mess about with hdr->commit et al. */
 540
 541         hdr->args.fh     = NFS_FH(hdr->inode);
 542         hdr->args.offset = req_offset(req) + offset;
 543         /* pnfs_set_layoutcommit needs this */
 544         hdr->mds_offset = hdr->args.offset;
 545         hdr->args.pgbase = req->wb_pgbase + offset;
 546         hdr->args.pages  = hdr->page_array.pagevec;
 547         hdr->args.count  = count;
 548         hdr->args.context = get_nfs_open_context(req->wb_context);
 549         hdr->args.lock_context = req->wb_lock_context;
 550         hdr->args.stable  = NFS_UNSTABLE;
 551         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 552         case 0:
 553                 break;
 554         case FLUSH_COND_STABLE:
 555                 if (nfs_reqs_to_commit(cinfo))
 556                         break;
 557         default:
 558                 hdr->args.stable = NFS_FILE_SYNC;
 559         }
 560
 561         hdr->res.fattr   = &hdr->fattr;
 562         hdr->res.count   = count;
 563         hdr->res.eof     = 0;
 564         hdr->res.verf    = &hdr->verf;
 565         nfs_fattr_init(&hdr->fattr);
 566 }
 567
 568 /**
 569  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 570  * @task: The current task
 571  * @calldata: pageio header to prepare
 572  */
 573 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 574 {
 575         struct nfs_pgio_header *hdr = calldata;
 576         int err;
 577         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 578         if (err)
 579                 rpc_exit(task, err);
 580 }
 581
 582 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 583                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
 584                       const struct rpc_call_ops *call_ops, int how, int flags)
 585 {
 586         struct rpc_task *task;
 587         struct rpc_message msg = {
 588                 .rpc_argp = &hdr->args,
 589                 .rpc_resp = &hdr->res,
 590                 .rpc_cred = cred,
 591         };
 592         struct rpc_task_setup task_setup_data = {
 593                 .rpc_client = clnt,
 594                 .task = &hdr->task,
 595                 .rpc_message = &msg,
 596                 .callback_ops = call_ops,
 597                 .callback_data = hdr,
 598                 .workqueue = nfsiod_workqueue,
 599                 .flags = RPC_TASK_ASYNC | flags,
 600         };
 601         int ret = 0;
 602
 603         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 604
 605         dprintk("NFS: initiated pgio call "
 606                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 607                 hdr->inode->i_sb->s_id,
 608                 (unsigned long long)NFS_FILEID(hdr->inode),
 609                 hdr->args.count,
 610                 (unsigned long long)hdr->args.offset);
 611
 612         task = rpc_run_task(&task_setup_data);
 613         if (IS_ERR(task)) {
 614                 ret = PTR_ERR(task);
 615                 goto out;
 616         }
 617         if (how & FLUSH_SYNC) {
 618                 ret = rpc_wait_for_completion_task(task);
 619                 if (ret == 0)
 620                         ret = task->tk_status;
 621         }
 622         rpc_put_task(task);
 623 out:
 624         return ret;
 625 }
 626 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 627
 628 /**
 629  * nfs_pgio_error - Clean up from a pageio error
 630  * @desc: IO descriptor
 631  * @hdr: pageio header
 632  */
 633 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 634 {
 635         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 636         nfs_pgio_data_destroy(hdr);
 637         hdr->completion_ops->completion(hdr);
 638 }
 639
 640 /**
 641  * nfs_pgio_release - Release pageio data
 642  * @calldata: The pageio header to release
 643  */
 644 static void nfs_pgio_release(void *calldata)
 645 {
 646         struct nfs_pgio_header *hdr = calldata;
 647         nfs_pgio_data_destroy(hdr);
 648         hdr->completion_ops->completion(hdr);
 649 }
 650
 651 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 652                                    unsigned int bsize)
 653 {
 654         INIT_LIST_HEAD(&mirror->pg_list);
 655         mirror->pg_bytes_written = 0;
 656         mirror->pg_count = 0;
 657         mirror->pg_bsize = bsize;
 658         mirror->pg_base = 0;
 659         mirror->pg_recoalesce = 0;
 660 }
 661
 662 /**
 663  * nfs_pageio_init - initialise a page io descriptor
 664  * @desc: pointer to descriptor
 665  * @inode: pointer to inode
 666  * @pg_ops: pointer to pageio operations
 667  * @compl_ops: pointer to pageio completion operations
 668  * @rw_ops: pointer to nfs read/write operations
 669  * @bsize: io block size
 670  * @io_flags: extra parameters for the io function
 671  */
 672 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 673                      struct inode *inode,
 674                      const struct nfs_pageio_ops *pg_ops,
 675                      const struct nfs_pgio_completion_ops *compl_ops,
 676                      const struct nfs_rw_ops *rw_ops,
 677                      size_t bsize,
 678                      int io_flags)
 679 {
 680         struct nfs_pgio_mirror *new;
 681         int i;
 682
 683         desc->pg_moreio = 0;
 684         desc->pg_inode = inode;
 685         desc->pg_ops = pg_ops;
 686         desc->pg_completion_ops = compl_ops;
 687         desc->pg_rw_ops = rw_ops;
 688         desc->pg_ioflags = io_flags;
 689         desc->pg_error = 0;
 690         desc->pg_lseg = NULL;
 691         desc->pg_dreq = NULL;
 692         desc->pg_layout_private = NULL;
 693         desc->pg_bsize = bsize;
 694
 695         desc->pg_mirror_count = 1;
 696         desc->pg_mirror_idx = 0;
 697
 698         if (pg_ops->pg_get_mirror_count) {
 699                 /* until we have a request, we don't have an lseg and no
 700                  * idea how many mirrors there will be */
 701                 new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
 702                               sizeof(struct nfs_pgio_mirror), GFP_KERNEL);
 703                 desc->pg_mirrors_dynamic = new;
 704                 desc->pg_mirrors = new;
 705
 706                 for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
 707                         nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
 708         } else {
 709                 desc->pg_mirrors_dynamic = NULL;
 710                 desc->pg_mirrors = desc->pg_mirrors_static;
 711                 nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 712         }
 713 }
 714 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 715
 716 /**
 717  * nfs_pgio_result - Basic pageio error handling
 718  * @task: The task that ran
 719  * @calldata: Pageio header to check
 720  */
 721 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 722 {
 723         struct nfs_pgio_header *hdr = calldata;
 724         struct inode *inode = hdr->inode;
 725
 726         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 727                 task->tk_pid, task->tk_status);
 728
 729         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 730                 return;
 731         if (task->tk_status < 0)
 732                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 733         else
 734                 hdr->rw_ops->rw_result(task, hdr);
 735 }
 736
 737 /*
 738  * Create an RPC task for the given read or write request and kick it.
 739  * The page must have been locked by the caller.
 740  *
 741  * It may happen that the page we're passed is not marked dirty.
 742  * This is the case if nfs_updatepage detects a conflicting request
 743  * that has been written but not committed.
 744  */
 745 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 746                      struct nfs_pgio_header *hdr)
 747 {
 748         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 749
 750         struct nfs_page         *req;
 751         struct page             **pages,
 752                                 *last_page;
 753         struct list_head *head = &mirror->pg_list;
 754         struct nfs_commit_info cinfo;
 755         unsigned int pagecount, pageused;
 756
 757         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 758         if (!nfs_pgarray_set(&hdr->page_array, pagecount)) {
 759                 nfs_pgio_error(hdr);
 760                 desc->pg_error = -ENOMEM;
 761                 return desc->pg_error;
 762         }
 763
 764         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 765         pages = hdr->page_array.pagevec;
 766         last_page = NULL;
 767         pageused = 0;
 768         while (!list_empty(head)) {
 769                 req = nfs_list_entry(head->next);
 770                 nfs_list_remove_request(req);
 771                 nfs_list_add_request(req, &hdr->pages);
 772
 773                 if (!last_page || last_page != req->wb_page) {
 774                         pageused++;
 775                         if (pageused > pagecount)
 776                                 break;
 777                         *pages++ = last_page = req->wb_page;
 778                 }
 779         }
 780         if (WARN_ON_ONCE(pageused != pagecount)) {
 781                 nfs_pgio_error(hdr);
 782                 desc->pg_error = -EINVAL;
 783                 return desc->pg_error;
 784         }
 785
 786         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 787             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 788                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 789
 790         /* Set up the argument struct */
 791         nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
 792         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 793         return 0;
 794 }
 795 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 796
 797 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 798 {
 799         struct nfs_pgio_header *hdr;
 800         int ret;
 801
 802         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 803         if (!hdr) {
 804                 desc->pg_error = -ENOMEM;
 805                 return desc->pg_error;
 806         }
 807         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 808         ret = nfs_generic_pgio(desc, hdr);
 809         if (ret == 0)
 810                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 811                                         hdr,
 812                                         hdr->cred,
 813                                         NFS_PROTO(hdr->inode),
 814                                         desc->pg_rpc_callops,
 815                                         desc->pg_ioflags, 0);
 816         return ret;
 817 }
 818
 819 /*
 820  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 821  *                              by calling the pg_get_mirror_count op
 822  */
 823 static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 824                                        struct nfs_page *req)
 825 {
 826         int mirror_count = 1;
 827
 828         if (!pgio->pg_ops->pg_get_mirror_count)
 829                 return 0;
 830
 831         mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 832
 833         if (pgio->pg_error < 0)
 834                 return pgio->pg_error;
 835
 836         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
 837                 return -EINVAL;
 838
 839         if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
 840                 return -EINVAL;
 841
 842         pgio->pg_mirror_count = mirror_count;
 843
 844         return 0;
 845 }
 846
 847 /*
 848  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
 849  */
 850 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
 851 {
 852         pgio->pg_mirror_count = 1;
 853         pgio->pg_mirror_idx = 0;
 854 }
 855
 856 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 857 {
 858         pgio->pg_mirror_count = 1;
 859         pgio->pg_mirror_idx = 0;
 860         pgio->pg_mirrors = pgio->pg_mirrors_static;
 861         kfree(pgio->pg_mirrors_dynamic);
 862         pgio->pg_mirrors_dynamic = NULL;
 863 }
 864
 865 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 866                 const struct nfs_lock_context *l2)
 867 {
 868         return l1->lockowner.l_owner == l2->lockowner.l_owner
 869                 && l1->lockowner.l_pid == l2->lockowner.l_pid;
 870 }
 871
 872 /**
 873  * nfs_can_coalesce_requests - test two requests for compatibility
 874  * @prev: pointer to nfs_page
 875  * @req: pointer to nfs_page
 876  *
 877  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 878  * page data area they describe is contiguous, and that their RPC
 879  * credentials, NFSv4 open state, and lockowners are the same.
 880  *
 881  * Return 'true' if this is the case, else return 'false'.
 882  */
 883 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 884                                       struct nfs_page *req,
 885                                       struct nfs_pageio_descriptor *pgio)
 886 {
 887         size_t size;
 888         struct file_lock_context *flctx;
 889
 890         if (prev) {
 891                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 892                         return false;
 893                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
 894                 if (flctx != NULL &&
 895                     !(list_empty_careful(&flctx->flc_posix) &&
 896                       list_empty_careful(&flctx->flc_flock)) &&
 897                     !nfs_match_lock_context(req->wb_lock_context,
 898                                             prev->wb_lock_context))
 899                         return false;
 900                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 901                         return false;
 902                 if (req->wb_page == prev->wb_page) {
 903                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 904                                 return false;
 905                 } else {
 906                         if (req->wb_pgbase != 0 ||
 907                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 908                                 return false;
 909                 }
 910         }
 911         size = pgio->pg_ops->pg_test(pgio, prev, req);
 912         WARN_ON_ONCE(size > req->wb_bytes);
 913         if (size && size < req->wb_bytes)
 914                 req->wb_bytes = size;
 915         return size > 0;
 916 }
 917
 918 /**
 919  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 920  * @desc: destination io descriptor
 921  * @req: request
 922  *
 923  * Returns true if the request 'req' was successfully coalesced into the
 924  * existing list of pages 'desc'.
 925  */
 926 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 927                                      struct nfs_page *req)
 928 {
 929         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 930
 931         struct nfs_page *prev = NULL;
 932
 933         if (mirror->pg_count != 0) {
 934                 prev = nfs_list_entry(mirror->pg_list.prev);
 935         } else {
 936                 if (desc->pg_ops->pg_init)
 937                         desc->pg_ops->pg_init(desc, req);
 938                 if (desc->pg_error < 0)
 939                         return 0;
 940                 mirror->pg_base = req->wb_pgbase;
 941         }
 942         if (!nfs_can_coalesce_requests(prev, req, desc))
 943                 return 0;
 944         nfs_list_remove_request(req);
 945         nfs_list_add_request(req, &mirror->pg_list);
 946         mirror->pg_count += req->wb_bytes;
 947         return 1;
 948 }
 949
 950 /*
 951  * Helper for nfs_pageio_add_request and nfs_pageio_complete
 952  */
 953 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 954 {
 955         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 956
 957
 958         if (!list_empty(&mirror->pg_list)) {
 959                 int error = desc->pg_ops->pg_doio(desc);
 960                 if (error < 0)
 961                         desc->pg_error = error;
 962                 else
 963                         mirror->pg_bytes_written += mirror->pg_count;
 964         }
 965         if (list_empty(&mirror->pg_list)) {
 966                 mirror->pg_count = 0;
 967                 mirror->pg_base = 0;
 968         }
 969 }
 970
 971 /**
 972  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
 973  * @desc: destination io descriptor
 974  * @req: request
 975  *
 976  * This may split a request into subrequests which are all part of the
 977  * same page group.
 978  *
 979  * Returns true if the request 'req' was successfully coalesced into the
 980  * existing list of pages 'desc'.
 981  */
 982 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 983                            struct nfs_page *req)
 984 {
 985         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 986
 987         struct nfs_page *subreq;
 988         unsigned int bytes_left = 0;
 989         unsigned int offset, pgbase;
 990
 991         nfs_page_group_lock(req, false);
 992
 993         subreq = req;
 994         bytes_left = subreq->wb_bytes;
 995         offset = subreq->wb_offset;
 996         pgbase = subreq->wb_pgbase;
 997
 998         do {
 999                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1000                         /* make sure pg_test call(s) did nothing */
1001                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1002                         WARN_ON_ONCE(subreq->wb_offset != offset);
1003                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1004
1005                         nfs_page_group_unlock(req);
1006                         desc->pg_moreio = 1;
1007                         nfs_pageio_doio(desc);
1008                         if (desc->pg_error < 0)
1009                                 return 0;
1010                         if (mirror->pg_recoalesce)
1011                                 return 0;
1012                         /* retry add_request for this subreq */
1013                         nfs_page_group_lock(req, false);
1014                         continue;
1015                 }
1016
1017                 /* check for buggy pg_test call(s) */
1018                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1019                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1020                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1021
1022                 bytes_left -= subreq->wb_bytes;
1023                 offset += subreq->wb_bytes;
1024                 pgbase += subreq->wb_bytes;
1025
1026                 if (bytes_left) {
1027                         subreq = nfs_create_request(req->wb_context,
1028                                         req->wb_page,
1029                                         subreq, pgbase, bytes_left);
1030                         if (IS_ERR(subreq))
1031                                 goto err_ptr;
1032                         nfs_lock_request(subreq);
1033                         subreq->wb_offset  = offset;
1034                         subreq->wb_index = req->wb_index;
1035                 }
1036         } while (bytes_left > 0);
1037
1038         nfs_page_group_unlock(req);
1039         return 1;
1040 err_ptr:
1041         desc->pg_error = PTR_ERR(subreq);
1042         nfs_page_group_unlock(req);
1043         return 0;
1044 }
1045
1046 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1047 {
1048         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1049         LIST_HEAD(head);
1050
1051         do {
1052                 list_splice_init(&mirror->pg_list, &head);
1053                 mirror->pg_bytes_written -= mirror->pg_count;
1054                 mirror->pg_count = 0;
1055                 mirror->pg_base = 0;
1056                 mirror->pg_recoalesce = 0;
1057
1058                 while (!list_empty(&head)) {
1059                         struct nfs_page *req;
1060
1061                         req = list_first_entry(&head, struct nfs_page, wb_list);
1062                         nfs_list_remove_request(req);
1063                         if (__nfs_pageio_add_request(desc, req))
1064                                 continue;
1065                         if (desc->pg_error < 0) {
1066                                 list_splice_tail(&head, &mirror->pg_list);
1067                                 mirror->pg_recoalesce = 1;
1068                                 return 0;
1069                         }
1070                         break;
1071                 }
1072         } while (mirror->pg_recoalesce);
1073         return 1;
1074 }
1075
1076 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1077                 struct nfs_page *req)
1078 {
1079         int ret;
1080
1081         do {
1082                 ret = __nfs_pageio_add_request(desc, req);
1083                 if (ret)
1084                         break;
1085                 if (desc->pg_error < 0)
1086                         break;
1087                 ret = nfs_do_recoalesce(desc);
1088         } while (ret);
1089
1090         return ret;
1091 }
1092
1093 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1094                            struct nfs_page *req)
1095 {
1096         u32 midx;
1097         unsigned int pgbase, offset, bytes;
1098         struct nfs_page *dupreq, *lastreq;
1099
1100         pgbase = req->wb_pgbase;
1101         offset = req->wb_offset;
1102         bytes = req->wb_bytes;
1103
1104         nfs_pageio_setup_mirroring(desc, req);
1105         if (desc->pg_error < 0)
1106                 goto out_failed;
1107
1108         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1109                 if (midx) {
1110                         nfs_page_group_lock(req, false);
1111
1112                         /* find the last request */
1113                         for (lastreq = req->wb_head;
1114                              lastreq->wb_this_page != req->wb_head;
1115                              lastreq = lastreq->wb_this_page)
1116                                 ;
1117
1118                         dupreq = nfs_create_request(req->wb_context,
1119                                         req->wb_page, lastreq, pgbase, bytes);
1120
1121                         if (IS_ERR(dupreq)) {
1122                                 nfs_page_group_unlock(req);
1123                                 desc->pg_error = PTR_ERR(dupreq);
1124                                 goto out_failed;
1125                         }
1126
1127                         nfs_lock_request(dupreq);
1128                         nfs_page_group_unlock(req);
1129                         dupreq->wb_offset = offset;
1130                         dupreq->wb_index = req->wb_index;
1131                 } else
1132                         dupreq = req;
1133
1134                 if (nfs_pgio_has_mirroring(desc))
1135                         desc->pg_mirror_idx = midx;
1136                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1137                         goto out_failed;
1138         }
1139
1140         return 1;
1141
1142 out_failed:
1143         /*
1144          * We might have failed before sending any reqs over wire.
1145          * Clean up rest of the reqs in mirror pg_list.
1146          */
1147         if (desc->pg_error) {
1148                 struct nfs_pgio_mirror *mirror;
1149                 void (*func)(struct list_head *);
1150
1151                 /* remember fatal errors */
1152                 if (nfs_error_is_fatal(desc->pg_error))
1153                         mapping_set_error(desc->pg_inode->i_mapping,
1154                                           desc->pg_error);
1155
1156                 func = desc->pg_completion_ops->error_cleanup;
1157                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1158                         mirror = &desc->pg_mirrors[midx];
1159                         func(&mirror->pg_list);
1160                 }
1161         }
1162         return 0;
1163 }
1164
1165 /*
1166  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1167  *                              nfs_pageio_descriptor
1168  * @desc: pointer to io descriptor
1169  * @mirror_idx: pointer to mirror index
1170  */
1171 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1172                                        u32 mirror_idx)
1173 {
1174         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1175         u32 restore_idx = desc->pg_mirror_idx;
1176
1177         if (nfs_pgio_has_mirroring(desc))
1178                 desc->pg_mirror_idx = mirror_idx;
1179         for (;;) {
1180                 nfs_pageio_doio(desc);
1181                 if (!mirror->pg_recoalesce)
1182                         break;
1183                 if (!nfs_do_recoalesce(desc))
1184                         break;
1185         }
1186         desc->pg_mirror_idx = restore_idx;
1187 }
1188
1189 /*
1190  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1191  * @hdr - the pgio header to move request from
1192  * @desc - the pageio descriptor to add requests to
1193  *
1194  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1195  * to send them.
1196  *
1197  * Returns 0 on success and < 0 on error.
1198  */
1199 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1200                       struct nfs_pgio_header *hdr)
1201 {
1202         LIST_HEAD(failed);
1203
1204         desc->pg_dreq = hdr->dreq;
1205         while (!list_empty(&hdr->pages)) {
1206                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1207
1208                 nfs_list_remove_request(req);
1209                 if (!nfs_pageio_add_request(desc, req))
1210                         nfs_list_add_request(req, &failed);
1211         }
1212         nfs_pageio_complete(desc);
1213         if (!list_empty(&failed)) {
1214                 list_move(&failed, &hdr->pages);
1215                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1216         }
1217         return 0;
1218 }
1219 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1220
1221 /**
1222  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1223  * @desc: pointer to io descriptor
1224  */
1225 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1226 {
1227         u32 midx;
1228
1229         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1230                 nfs_pageio_complete_mirror(desc, midx);
1231
1232         if (desc->pg_ops->pg_cleanup)
1233                 desc->pg_ops->pg_cleanup(desc);
1234         nfs_pageio_cleanup_mirroring(desc);
1235 }
1236
1237 /**
1238  * nfs_pageio_cond_complete - Conditional I/O completion
1239  * @desc: pointer to io descriptor
1240  * @index: page index
1241  *
1242  * It is important to ensure that processes don't try to take locks
1243  * on non-contiguous ranges of pages as that might deadlock. This
1244  * function should be called before attempting to wait on a locked
1245  * nfs_page. It will complete the I/O if the page index 'index'
1246  * is not contiguous with the existing list of pages in 'desc'.
1247  */
1248 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1249 {
1250         struct nfs_pgio_mirror *mirror;
1251         struct nfs_page *prev;
1252         u32 midx;
1253
1254         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1255                 mirror = &desc->pg_mirrors[midx];
1256                 if (!list_empty(&mirror->pg_list)) {
1257                         prev = nfs_list_entry(mirror->pg_list.prev);
1258                         if (index != prev->wb_index + 1)
1259                                 nfs_pageio_complete_mirror(desc, midx);
1260                 }
1261         }
1262 }
1263
1264 int __init nfs_init_nfspagecache(void)
1265 {
1266         nfs_page_cachep = kmem_cache_create("nfs_page",
1267                                             sizeof(struct nfs_page),
1268                                             0, SLAB_HWCACHE_ALIGN,
1269                                             NULL);
1270         if (nfs_page_cachep == NULL)
1271                 return -ENOMEM;
1272
1273         return 0;
1274 }
1275
1276 void nfs_destroy_nfspagecache(void)
1277 {
1278         kmem_cache_destroy(nfs_page_cachep);
1279 }
1280
1281 static const struct rpc_call_ops nfs_pgio_common_ops = {
1282         .rpc_call_prepare = nfs_pgio_prepare,
1283         .rpc_call_done = nfs_pgio_result,
1284         .rpc_release = nfs_pgio_release,
1285 };
1286
1287 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1288         .pg_test = nfs_generic_pg_test,
1289         .pg_doio = nfs_generic_pg_pgios,
1290 };