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         if (page) {
 345                 req->wb_index = page_index(page);
 346                 get_page(page);
 347         }
 348         req->wb_offset  = offset;
 349         req->wb_pgbase  = offset;
 350         req->wb_bytes   = count;
 351         req->wb_context = get_nfs_open_context(ctx);
 352         kref_init(&req->wb_kref);
 353         nfs_page_group_init(req, last);
 354         return req;
 355 }
 356
 357 /**
 358  * nfs_unlock_request - Unlock request and wake up sleepers.
 359  * @req:
 360  */
 361 void nfs_unlock_request(struct nfs_page *req)
 362 {
 363         if (!NFS_WBACK_BUSY(req)) {
 364                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 365                 BUG();
 366         }
 367         smp_mb__before_atomic();
 368         clear_bit(PG_BUSY, &req->wb_flags);
 369         smp_mb__after_atomic();
 370         wake_up_bit(&req->wb_flags, PG_BUSY);
 371 }
 372
 373 /**
 374  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 375  * @req:
 376  */
 377 void nfs_unlock_and_release_request(struct nfs_page *req)
 378 {
 379         nfs_unlock_request(req);
 380         nfs_release_request(req);
 381 }
 382
 383 /*
 384  * nfs_clear_request - Free up all resources allocated to the request
 385  * @req:
 386  *
 387  * Release page and open context resources associated with a read/write
 388  * request after it has completed.
 389  */
 390 static void nfs_clear_request(struct nfs_page *req)
 391 {
 392         struct page *page = req->wb_page;
 393         struct nfs_open_context *ctx = req->wb_context;
 394         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 395
 396         if (page != NULL) {
 397                 put_page(page);
 398                 req->wb_page = NULL;
 399         }
 400         if (l_ctx != NULL) {
 401                 if (atomic_dec_and_test(&l_ctx->io_count))
 402                         wake_up_atomic_t(&l_ctx->io_count);
 403                 nfs_put_lock_context(l_ctx);
 404                 req->wb_lock_context = NULL;
 405         }
 406         if (ctx != NULL) {
 407                 put_nfs_open_context(ctx);
 408                 req->wb_context = NULL;
 409         }
 410 }
 411
 412 /**
 413  * nfs_release_request - Release the count on an NFS read/write request
 414  * @req: request to release
 415  *
 416  * Note: Should never be called with the spinlock held!
 417  */
 418 void nfs_free_request(struct nfs_page *req)
 419 {
 420         WARN_ON_ONCE(req->wb_this_page != req);
 421
 422         /* extra debug: make sure no sync bits are still set */
 423         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 424         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 425         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 426         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 427         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 428
 429         /* Release struct file and open context */
 430         nfs_clear_request(req);
 431         nfs_page_free(req);
 432 }
 433
 434 void nfs_release_request(struct nfs_page *req)
 435 {
 436         kref_put(&req->wb_kref, nfs_page_group_destroy);
 437 }
 438
 439 /**
 440  * nfs_wait_on_request - Wait for a request to complete.
 441  * @req: request to wait upon.
 442  *
 443  * Interruptible by fatal signals only.
 444  * The user is responsible for holding a count on the request.
 445  */
 446 int
 447 nfs_wait_on_request(struct nfs_page *req)
 448 {
 449         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 450                               TASK_UNINTERRUPTIBLE);
 451 }
 452
 453 /*
 454  * nfs_generic_pg_test - determine if requests can be coalesced
 455  * @desc: pointer to descriptor
 456  * @prev: previous request in desc, or NULL
 457  * @req: this request
 458  *
 459  * Returns zero if @req can be coalesced into @desc, otherwise it returns
 460  * the size of the request.
 461  */
 462 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 463                            struct nfs_page *prev, struct nfs_page *req)
 464 {
 465         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 466
 467
 468         if (mirror->pg_count > mirror->pg_bsize) {
 469                 /* should never happen */
 470                 WARN_ON_ONCE(1);
 471                 return 0;
 472         }
 473
 474         /*
 475          * Limit the request size so that we can still allocate a page array
 476          * for it without upsetting the slab allocator.
 477          */
 478         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 479                         sizeof(struct page *) > PAGE_SIZE)
 480                 return 0;
 481
 482         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 483 }
 484 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 485
 486 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 487 {
 488         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 489
 490         if (hdr) {
 491                 INIT_LIST_HEAD(&hdr->pages);
 492                 spin_lock_init(&hdr->lock);
 493                 hdr->rw_ops = ops;
 494         }
 495         return hdr;
 496 }
 497 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 498
 499 /*
 500  * nfs_pgio_header_free - Free a read or write header
 501  * @hdr: The header to free
 502  */
 503 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 504 {
 505         hdr->rw_ops->rw_free_header(hdr);
 506 }
 507 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 508
 509 /**
 510  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 511  *
 512  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 513  * be called again.
 514  *
 515  * @hdr: A header that has had nfs_generic_pgio called
 516  */
 517 void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 518 {
 519         if (hdr->args.context)
 520                 put_nfs_open_context(hdr->args.context);
 521         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 522                 kfree(hdr->page_array.pagevec);
 523 }
 524 EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
 525
 526 /**
 527  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 528  * @hdr: The pageio hdr
 529  * @count: Number of bytes to read
 530  * @offset: Initial offset
 531  * @how: How to commit data (writes only)
 532  * @cinfo: Commit information for the call (writes only)
 533  */
 534 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 535                               unsigned int count, unsigned int offset,
 536                               int how, struct nfs_commit_info *cinfo)
 537 {
 538         struct nfs_page *req = hdr->req;
 539
 540         /* Set up the RPC argument and reply structs
 541          * NB: take care not to mess about with hdr->commit et al. */
 542
 543         hdr->args.fh     = NFS_FH(hdr->inode);
 544         hdr->args.offset = req_offset(req) + offset;
 545         /* pnfs_set_layoutcommit needs this */
 546         hdr->mds_offset = hdr->args.offset;
 547         hdr->args.pgbase = req->wb_pgbase + offset;
 548         hdr->args.pages  = hdr->page_array.pagevec;
 549         hdr->args.count  = count;
 550         hdr->args.context = get_nfs_open_context(req->wb_context);
 551         hdr->args.lock_context = req->wb_lock_context;
 552         hdr->args.stable  = NFS_UNSTABLE;
 553         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 554         case 0:
 555                 break;
 556         case FLUSH_COND_STABLE:
 557                 if (nfs_reqs_to_commit(cinfo))
 558                         break;
 559         default:
 560                 hdr->args.stable = NFS_FILE_SYNC;
 561         }
 562
 563         hdr->res.fattr   = &hdr->fattr;
 564         hdr->res.count   = count;
 565         hdr->res.eof     = 0;
 566         hdr->res.verf    = &hdr->verf;
 567         nfs_fattr_init(&hdr->fattr);
 568 }
 569
 570 /**
 571  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 572  * @task: The current task
 573  * @calldata: pageio header to prepare
 574  */
 575 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 576 {
 577         struct nfs_pgio_header *hdr = calldata;
 578         int err;
 579         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 580         if (err)
 581                 rpc_exit(task, err);
 582 }
 583
 584 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 585                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
 586                       const struct rpc_call_ops *call_ops, int how, int flags)
 587 {
 588         struct rpc_task *task;
 589         struct rpc_message msg = {
 590                 .rpc_argp = &hdr->args,
 591                 .rpc_resp = &hdr->res,
 592                 .rpc_cred = cred,
 593         };
 594         struct rpc_task_setup task_setup_data = {
 595                 .rpc_client = clnt,
 596                 .task = &hdr->task,
 597                 .rpc_message = &msg,
 598                 .callback_ops = call_ops,
 599                 .callback_data = hdr,
 600                 .workqueue = nfsiod_workqueue,
 601                 .flags = RPC_TASK_ASYNC | flags,
 602         };
 603         int ret = 0;
 604
 605         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 606
 607         dprintk("NFS: initiated pgio call "
 608                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 609                 hdr->inode->i_sb->s_id,
 610                 (unsigned long long)NFS_FILEID(hdr->inode),
 611                 hdr->args.count,
 612                 (unsigned long long)hdr->args.offset);
 613
 614         task = rpc_run_task(&task_setup_data);
 615         if (IS_ERR(task)) {
 616                 ret = PTR_ERR(task);
 617                 goto out;
 618         }
 619         if (how & FLUSH_SYNC) {
 620                 ret = rpc_wait_for_completion_task(task);
 621                 if (ret == 0)
 622                         ret = task->tk_status;
 623         }
 624         rpc_put_task(task);
 625 out:
 626         return ret;
 627 }
 628 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 629
 630 /**
 631  * nfs_pgio_error - Clean up from a pageio error
 632  * @desc: IO descriptor
 633  * @hdr: pageio header
 634  */
 635 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 636 {
 637         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 638         nfs_pgio_data_destroy(hdr);
 639         hdr->completion_ops->completion(hdr);
 640 }
 641
 642 /**
 643  * nfs_pgio_release - Release pageio data
 644  * @calldata: The pageio header to release
 645  */
 646 static void nfs_pgio_release(void *calldata)
 647 {
 648         struct nfs_pgio_header *hdr = calldata;
 649         nfs_pgio_data_destroy(hdr);
 650         hdr->completion_ops->completion(hdr);
 651 }
 652
 653 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 654                                    unsigned int bsize)
 655 {
 656         INIT_LIST_HEAD(&mirror->pg_list);
 657         mirror->pg_bytes_written = 0;
 658         mirror->pg_count = 0;
 659         mirror->pg_bsize = bsize;
 660         mirror->pg_base = 0;
 661         mirror->pg_recoalesce = 0;
 662 }
 663
 664 /**
 665  * nfs_pageio_init - initialise a page io descriptor
 666  * @desc: pointer to descriptor
 667  * @inode: pointer to inode
 668  * @pg_ops: pointer to pageio operations
 669  * @compl_ops: pointer to pageio completion operations
 670  * @rw_ops: pointer to nfs read/write operations
 671  * @bsize: io block size
 672  * @io_flags: extra parameters for the io function
 673  */
 674 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 675                      struct inode *inode,
 676                      const struct nfs_pageio_ops *pg_ops,
 677                      const struct nfs_pgio_completion_ops *compl_ops,
 678                      const struct nfs_rw_ops *rw_ops,
 679                      size_t bsize,
 680                      int io_flags)
 681 {
 682         struct nfs_pgio_mirror *new;
 683         int i;
 684
 685         desc->pg_moreio = 0;
 686         desc->pg_inode = inode;
 687         desc->pg_ops = pg_ops;
 688         desc->pg_completion_ops = compl_ops;
 689         desc->pg_rw_ops = rw_ops;
 690         desc->pg_ioflags = io_flags;
 691         desc->pg_error = 0;
 692         desc->pg_lseg = NULL;
 693         desc->pg_dreq = NULL;
 694         desc->pg_layout_private = NULL;
 695         desc->pg_bsize = bsize;
 696
 697         desc->pg_mirror_count = 1;
 698         desc->pg_mirror_idx = 0;
 699
 700         if (pg_ops->pg_get_mirror_count) {
 701                 /* until we have a request, we don't have an lseg and no
 702                  * idea how many mirrors there will be */
 703                 new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
 704                               sizeof(struct nfs_pgio_mirror), GFP_KERNEL);
 705                 desc->pg_mirrors_dynamic = new;
 706                 desc->pg_mirrors = new;
 707
 708                 for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
 709                         nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
 710         } else {
 711                 desc->pg_mirrors_dynamic = NULL;
 712                 desc->pg_mirrors = desc->pg_mirrors_static;
 713                 nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 714         }
 715 }
 716 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 717
 718 /**
 719  * nfs_pgio_result - Basic pageio error handling
 720  * @task: The task that ran
 721  * @calldata: Pageio header to check
 722  */
 723 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 724 {
 725         struct nfs_pgio_header *hdr = calldata;
 726         struct inode *inode = hdr->inode;
 727
 728         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 729                 task->tk_pid, task->tk_status);
 730
 731         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 732                 return;
 733         if (task->tk_status < 0)
 734                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 735         else
 736                 hdr->rw_ops->rw_result(task, hdr);
 737 }
 738
 739 /*
 740  * Create an RPC task for the given read or write request and kick it.
 741  * The page must have been locked by the caller.
 742  *
 743  * It may happen that the page we're passed is not marked dirty.
 744  * This is the case if nfs_updatepage detects a conflicting request
 745  * that has been written but not committed.
 746  */
 747 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 748                      struct nfs_pgio_header *hdr)
 749 {
 750         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 751
 752         struct nfs_page         *req;
 753         struct page             **pages,
 754                                 *last_page;
 755         struct list_head *head = &mirror->pg_list;
 756         struct nfs_commit_info cinfo;
 757         unsigned int pagecount, pageused;
 758
 759         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 760         if (!nfs_pgarray_set(&hdr->page_array, pagecount)) {
 761                 nfs_pgio_error(hdr);
 762                 desc->pg_error = -ENOMEM;
 763                 return desc->pg_error;
 764         }
 765
 766         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 767         pages = hdr->page_array.pagevec;
 768         last_page = NULL;
 769         pageused = 0;
 770         while (!list_empty(head)) {
 771                 req = nfs_list_entry(head->next);
 772                 nfs_list_remove_request(req);
 773                 nfs_list_add_request(req, &hdr->pages);
 774
 775                 if (!last_page || last_page != req->wb_page) {
 776                         pageused++;
 777                         if (pageused > pagecount)
 778                                 break;
 779                         *pages++ = last_page = req->wb_page;
 780                 }
 781         }
 782         if (WARN_ON_ONCE(pageused != pagecount)) {
 783                 nfs_pgio_error(hdr);
 784                 desc->pg_error = -EINVAL;
 785                 return desc->pg_error;
 786         }
 787
 788         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 789             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 790                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 791
 792         /* Set up the argument struct */
 793         nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
 794         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 795         return 0;
 796 }
 797 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 798
 799 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 800 {
 801         struct nfs_pgio_header *hdr;
 802         int ret;
 803
 804         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 805         if (!hdr) {
 806                 desc->pg_error = -ENOMEM;
 807                 return desc->pg_error;
 808         }
 809         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 810         ret = nfs_generic_pgio(desc, hdr);
 811         if (ret == 0)
 812                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 813                                         hdr,
 814                                         hdr->cred,
 815                                         NFS_PROTO(hdr->inode),
 816                                         desc->pg_rpc_callops,
 817                                         desc->pg_ioflags, 0);
 818         return ret;
 819 }
 820
 821 /*
 822  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 823  *                              by calling the pg_get_mirror_count op
 824  */
 825 static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 826                                        struct nfs_page *req)
 827 {
 828         int mirror_count = 1;
 829
 830         if (!pgio->pg_ops->pg_get_mirror_count)
 831                 return 0;
 832
 833         mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 834
 835         if (pgio->pg_error < 0)
 836                 return pgio->pg_error;
 837
 838         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
 839                 return -EINVAL;
 840
 841         if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
 842                 return -EINVAL;
 843
 844         pgio->pg_mirror_count = mirror_count;
 845
 846         return 0;
 847 }
 848
 849 /*
 850  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
 851  */
 852 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
 853 {
 854         pgio->pg_mirror_count = 1;
 855         pgio->pg_mirror_idx = 0;
 856 }
 857
 858 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 859 {
 860         pgio->pg_mirror_count = 1;
 861         pgio->pg_mirror_idx = 0;
 862         pgio->pg_mirrors = pgio->pg_mirrors_static;
 863         kfree(pgio->pg_mirrors_dynamic);
 864         pgio->pg_mirrors_dynamic = NULL;
 865 }
 866
 867 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 868                 const struct nfs_lock_context *l2)
 869 {
 870         return l1->lockowner == l2->lockowner;
 871 }
 872
 873 /**
 874  * nfs_can_coalesce_requests - test two requests for compatibility
 875  * @prev: pointer to nfs_page
 876  * @req: pointer to nfs_page
 877  *
 878  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 879  * page data area they describe is contiguous, and that their RPC
 880  * credentials, NFSv4 open state, and lockowners are the same.
 881  *
 882  * Return 'true' if this is the case, else return 'false'.
 883  */
 884 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 885                                       struct nfs_page *req,
 886                                       struct nfs_pageio_descriptor *pgio)
 887 {
 888         size_t size;
 889         struct file_lock_context *flctx;
 890
 891         if (prev) {
 892                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 893                         return false;
 894                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
 895                 if (flctx != NULL &&
 896                     !(list_empty_careful(&flctx->flc_posix) &&
 897                       list_empty_careful(&flctx->flc_flock)) &&
 898                     !nfs_match_lock_context(req->wb_lock_context,
 899                                             prev->wb_lock_context))
 900                         return false;
 901                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 902                         return false;
 903                 if (req->wb_page == prev->wb_page) {
 904                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 905                                 return false;
 906                 } else {
 907                         if (req->wb_pgbase != 0 ||
 908                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 909                                 return false;
 910                 }
 911         }
 912         size = pgio->pg_ops->pg_test(pgio, prev, req);
 913         WARN_ON_ONCE(size > req->wb_bytes);
 914         if (size && size < req->wb_bytes)
 915                 req->wb_bytes = size;
 916         return size > 0;
 917 }
 918
 919 /**
 920  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 921  * @desc: destination io descriptor
 922  * @req: request
 923  *
 924  * Returns true if the request 'req' was successfully coalesced into the
 925  * existing list of pages 'desc'.
 926  */
 927 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 928                                      struct nfs_page *req)
 929 {
 930         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 931
 932         struct nfs_page *prev = NULL;
 933
 934         if (mirror->pg_count != 0) {
 935                 prev = nfs_list_entry(mirror->pg_list.prev);
 936         } else {
 937                 if (desc->pg_ops->pg_init)
 938                         desc->pg_ops->pg_init(desc, req);
 939                 if (desc->pg_error < 0)
 940                         return 0;
 941                 mirror->pg_base = req->wb_pgbase;
 942         }
 943         if (!nfs_can_coalesce_requests(prev, req, desc))
 944                 return 0;
 945         nfs_list_remove_request(req);
 946         nfs_list_add_request(req, &mirror->pg_list);
 947         mirror->pg_count += req->wb_bytes;
 948         return 1;
 949 }
 950
 951 /*
 952  * Helper for nfs_pageio_add_request and nfs_pageio_complete
 953  */
 954 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 955 {
 956         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 957
 958
 959         if (!list_empty(&mirror->pg_list)) {
 960                 int error = desc->pg_ops->pg_doio(desc);
 961                 if (error < 0)
 962                         desc->pg_error = error;
 963                 else
 964                         mirror->pg_bytes_written += mirror->pg_count;
 965         }
 966         if (list_empty(&mirror->pg_list)) {
 967                 mirror->pg_count = 0;
 968                 mirror->pg_base = 0;
 969         }
 970 }
 971
 972 /**
 973  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
 974  * @desc: destination io descriptor
 975  * @req: request
 976  *
 977  * This may split a request into subrequests which are all part of the
 978  * same page group.
 979  *
 980  * Returns true if the request 'req' was successfully coalesced into the
 981  * existing list of pages 'desc'.
 982  */
 983 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 984                            struct nfs_page *req)
 985 {
 986         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 987
 988         struct nfs_page *subreq;
 989         unsigned int bytes_left = 0;
 990         unsigned int offset, pgbase;
 991
 992         nfs_page_group_lock(req, false);
 993
 994         subreq = req;
 995         bytes_left = subreq->wb_bytes;
 996         offset = subreq->wb_offset;
 997         pgbase = subreq->wb_pgbase;
 998
 999         do {
1000                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1001                         /* make sure pg_test call(s) did nothing */
1002                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1003                         WARN_ON_ONCE(subreq->wb_offset != offset);
1004                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1005
1006                         nfs_page_group_unlock(req);
1007                         desc->pg_moreio = 1;
1008                         nfs_pageio_doio(desc);
1009                         if (desc->pg_error < 0)
1010                                 return 0;
1011                         if (mirror->pg_recoalesce)
1012                                 return 0;
1013                         /* retry add_request for this subreq */
1014                         nfs_page_group_lock(req, false);
1015                         continue;
1016                 }
1017
1018                 /* check for buggy pg_test call(s) */
1019                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1020                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1021                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1022
1023                 bytes_left -= subreq->wb_bytes;
1024                 offset += subreq->wb_bytes;
1025                 pgbase += subreq->wb_bytes;
1026
1027                 if (bytes_left) {
1028                         subreq = nfs_create_request(req->wb_context,
1029                                         req->wb_page,
1030                                         subreq, pgbase, bytes_left);
1031                         if (IS_ERR(subreq))
1032                                 goto err_ptr;
1033                         nfs_lock_request(subreq);
1034                         subreq->wb_offset  = offset;
1035                         subreq->wb_index = req->wb_index;
1036                 }
1037         } while (bytes_left > 0);
1038
1039         nfs_page_group_unlock(req);
1040         return 1;
1041 err_ptr:
1042         desc->pg_error = PTR_ERR(subreq);
1043         nfs_page_group_unlock(req);
1044         return 0;
1045 }
1046
1047 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1048 {
1049         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1050         LIST_HEAD(head);
1051
1052         do {
1053                 list_splice_init(&mirror->pg_list, &head);
1054                 mirror->pg_bytes_written -= mirror->pg_count;
1055                 mirror->pg_count = 0;
1056                 mirror->pg_base = 0;
1057                 mirror->pg_recoalesce = 0;
1058
1059                 while (!list_empty(&head)) {
1060                         struct nfs_page *req;
1061
1062                         req = list_first_entry(&head, struct nfs_page, wb_list);
1063                         nfs_list_remove_request(req);
1064                         if (__nfs_pageio_add_request(desc, req))
1065                                 continue;
1066                         if (desc->pg_error < 0) {
1067                                 list_splice_tail(&head, &mirror->pg_list);
1068                                 mirror->pg_recoalesce = 1;
1069                                 return 0;
1070                         }
1071                         break;
1072                 }
1073         } while (mirror->pg_recoalesce);
1074         return 1;
1075 }
1076
1077 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1078                 struct nfs_page *req)
1079 {
1080         int ret;
1081
1082         do {
1083                 ret = __nfs_pageio_add_request(desc, req);
1084                 if (ret)
1085                         break;
1086                 if (desc->pg_error < 0)
1087                         break;
1088                 ret = nfs_do_recoalesce(desc);
1089         } while (ret);
1090
1091         return ret;
1092 }
1093
1094 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1095                            struct nfs_page *req)
1096 {
1097         u32 midx;
1098         unsigned int pgbase, offset, bytes;
1099         struct nfs_page *dupreq, *lastreq;
1100
1101         pgbase = req->wb_pgbase;
1102         offset = req->wb_offset;
1103         bytes = req->wb_bytes;
1104
1105         nfs_pageio_setup_mirroring(desc, req);
1106         if (desc->pg_error < 0)
1107                 goto out_failed;
1108
1109         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1110                 if (midx) {
1111                         nfs_page_group_lock(req, false);
1112
1113                         /* find the last request */
1114                         for (lastreq = req->wb_head;
1115                              lastreq->wb_this_page != req->wb_head;
1116                              lastreq = lastreq->wb_this_page)
1117                                 ;
1118
1119                         dupreq = nfs_create_request(req->wb_context,
1120                                         req->wb_page, lastreq, pgbase, bytes);
1121
1122                         if (IS_ERR(dupreq)) {
1123                                 nfs_page_group_unlock(req);
1124                                 desc->pg_error = PTR_ERR(dupreq);
1125                                 goto out_failed;
1126                         }
1127
1128                         nfs_lock_request(dupreq);
1129                         nfs_page_group_unlock(req);
1130                         dupreq->wb_offset = offset;
1131                         dupreq->wb_index = req->wb_index;
1132                 } else
1133                         dupreq = req;
1134
1135                 if (nfs_pgio_has_mirroring(desc))
1136                         desc->pg_mirror_idx = midx;
1137                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1138                         goto out_failed;
1139         }
1140
1141         return 1;
1142
1143 out_failed:
1144         /*
1145          * We might have failed before sending any reqs over wire.
1146          * Clean up rest of the reqs in mirror pg_list.
1147          */
1148         if (desc->pg_error) {
1149                 struct nfs_pgio_mirror *mirror;
1150                 void (*func)(struct list_head *);
1151
1152                 /* remember fatal errors */
1153                 if (nfs_error_is_fatal(desc->pg_error))
1154                         mapping_set_error(desc->pg_inode->i_mapping,
1155                                           desc->pg_error);
1156
1157                 func = desc->pg_completion_ops->error_cleanup;
1158                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1159                         mirror = &desc->pg_mirrors[midx];
1160                         func(&mirror->pg_list);
1161                 }
1162         }
1163         return 0;
1164 }
1165
1166 /*
1167  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1168  *                              nfs_pageio_descriptor
1169  * @desc: pointer to io descriptor
1170  * @mirror_idx: pointer to mirror index
1171  */
1172 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1173                                        u32 mirror_idx)
1174 {
1175         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1176         u32 restore_idx = desc->pg_mirror_idx;
1177
1178         if (nfs_pgio_has_mirroring(desc))
1179                 desc->pg_mirror_idx = mirror_idx;
1180         for (;;) {
1181                 nfs_pageio_doio(desc);
1182                 if (!mirror->pg_recoalesce)
1183                         break;
1184                 if (!nfs_do_recoalesce(desc))
1185                         break;
1186         }
1187         desc->pg_mirror_idx = restore_idx;
1188 }
1189
1190 /*
1191  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1192  * @hdr - the pgio header to move request from
1193  * @desc - the pageio descriptor to add requests to
1194  *
1195  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1196  * to send them.
1197  *
1198  * Returns 0 on success and < 0 on error.
1199  */
1200 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1201                       struct nfs_pgio_header *hdr)
1202 {
1203         LIST_HEAD(failed);
1204
1205         desc->pg_dreq = hdr->dreq;
1206         while (!list_empty(&hdr->pages)) {
1207                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1208
1209                 nfs_list_remove_request(req);
1210                 if (!nfs_pageio_add_request(desc, req))
1211                         nfs_list_add_request(req, &failed);
1212         }
1213         nfs_pageio_complete(desc);
1214         if (!list_empty(&failed)) {
1215                 list_move(&failed, &hdr->pages);
1216                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1217         }
1218         return 0;
1219 }
1220 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1221
1222 /**
1223  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1224  * @desc: pointer to io descriptor
1225  */
1226 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1227 {
1228         u32 midx;
1229
1230         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1231                 nfs_pageio_complete_mirror(desc, midx);
1232
1233         if (desc->pg_ops->pg_cleanup)
1234                 desc->pg_ops->pg_cleanup(desc);
1235         nfs_pageio_cleanup_mirroring(desc);
1236 }
1237
1238 /**
1239  * nfs_pageio_cond_complete - Conditional I/O completion
1240  * @desc: pointer to io descriptor
1241  * @index: page index
1242  *
1243  * It is important to ensure that processes don't try to take locks
1244  * on non-contiguous ranges of pages as that might deadlock. This
1245  * function should be called before attempting to wait on a locked
1246  * nfs_page. It will complete the I/O if the page index 'index'
1247  * is not contiguous with the existing list of pages in 'desc'.
1248  */
1249 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1250 {
1251         struct nfs_pgio_mirror *mirror;
1252         struct nfs_page *prev;
1253         u32 midx;
1254
1255         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1256                 mirror = &desc->pg_mirrors[midx];
1257                 if (!list_empty(&mirror->pg_list)) {
1258                         prev = nfs_list_entry(mirror->pg_list.prev);
1259                         if (index != prev->wb_index + 1) {
1260                                 nfs_pageio_complete(desc);
1261                                 break;
1262                         }
1263                 }
1264         }
1265 }
1266
1267 int __init nfs_init_nfspagecache(void)
1268 {
1269         nfs_page_cachep = kmem_cache_create("nfs_page",
1270                                             sizeof(struct nfs_page),
1271                                             0, SLAB_HWCACHE_ALIGN,
1272                                             NULL);
1273         if (nfs_page_cachep == NULL)
1274                 return -ENOMEM;
1275
1276         return 0;
1277 }
1278
1279 void nfs_destroy_nfspagecache(void)
1280 {
1281         kmem_cache_destroy(nfs_page_cachep);
1282 }
1283
1284 static const struct rpc_call_ops nfs_pgio_common_ops = {
1285         .rpc_call_prepare = nfs_pgio_prepare,
1286         .rpc_call_done = nfs_pgio_result,
1287         .rpc_release = nfs_pgio_release,
1288 };
1289
1290 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1291         .pg_test = nfs_generic_pg_test,
1292         .pg_doio = nfs_generic_pg_pgios,
1293 };