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 <[email protected]>
   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 struct nfs_pgio_mirror *
  33 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
  34 {
  35         return nfs_pgio_has_mirroring(desc) ?
  36                 &desc->pg_mirrors[desc->pg_mirror_idx] :
  37                 &desc->pg_mirrors[0];
  38 }
  39 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
  40
  41 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  42                        struct nfs_pgio_header *hdr,
  43                        void (*release)(struct nfs_pgio_header *hdr))
  44 {
  45         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
  46
  47
  48         hdr->req = nfs_list_entry(mirror->pg_list.next);
  49         hdr->inode = desc->pg_inode;
  50         hdr->cred = hdr->req->wb_context->cred;
  51         hdr->io_start = req_offset(hdr->req);
  52         hdr->good_bytes = mirror->pg_count;
  53         hdr->dreq = desc->pg_dreq;
  54         hdr->layout_private = desc->pg_layout_private;
  55         hdr->release = release;
  56         hdr->completion_ops = desc->pg_completion_ops;
  57         if (hdr->completion_ops->init_hdr)
  58                 hdr->completion_ops->init_hdr(hdr);
  59
  60         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
  61 }
  62 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
  63
  64 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
  65 {
  66         spin_lock(&hdr->lock);
  67         if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags)
  68             || pos < hdr->io_start + hdr->good_bytes) {
  69                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
  70                 hdr->good_bytes = pos - hdr->io_start;
  71                 hdr->error = error;
  72         }
  73         spin_unlock(&hdr->lock);
  74 }
  75
  76 static inline struct nfs_page *
  77 nfs_page_alloc(void)
  78 {
  79         struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
  80         if (p)
  81                 INIT_LIST_HEAD(&p->wb_list);
  82         return p;
  83 }
  84
  85 static inline void
  86 nfs_page_free(struct nfs_page *p)
  87 {
  88         kmem_cache_free(nfs_page_cachep, p);
  89 }
  90
  91 /**
  92  * nfs_iocounter_wait - wait for i/o to complete
  93  * @l_ctx: nfs_lock_context with io_counter to use
  94  *
  95  * returns -ERESTARTSYS if interrupted by a fatal signal.
  96  * Otherwise returns 0 once the io_count hits 0.
  97  */
  98 int
  99 nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
 100 {
 101         return wait_on_atomic_t(&l_ctx->io_count, nfs_wait_atomic_killable,
 102                         TASK_KILLABLE);
 103 }
 104
 105 /**
 106  * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
 107  * to complete
 108  * @task: the rpc_task that should wait
 109  * @l_ctx: nfs_lock_context with io_counter to check
 110  *
 111  * Returns true if there is outstanding I/O to wait on and the
 112  * task has been put to sleep.
 113  */
 114 bool
 115 nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
 116 {
 117         struct inode *inode = d_inode(l_ctx->open_context->dentry);
 118         bool ret = false;
 119
 120         if (atomic_read(&l_ctx->io_count) > 0) {
 121                 rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
 122                 ret = true;
 123         }
 124
 125         if (atomic_read(&l_ctx->io_count) == 0) {
 126                 rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
 127                 ret = false;
 128         }
 129
 130         return ret;
 131 }
 132 EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
 133
 134 /*
 135  * nfs_page_group_lock - lock the head of the page group
 136  * @req - request in group that is to be locked
 137  * @nonblock - if true don't block waiting for lock
 138  *
 139  * this lock must be held if modifying the page group list
 140  *
 141  * return 0 on success, < 0 on error: -EDELAY if nonblocking or the
 142  * result from wait_on_bit_lock
 143  *
 144  * NOTE: calling with nonblock=false should always have set the
 145  *       lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
 146  *       with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
 147  */
 148 int
 149 nfs_page_group_lock(struct nfs_page *req, bool nonblock)
 150 {
 151         struct nfs_page *head = req->wb_head;
 152
 153         WARN_ON_ONCE(head != head->wb_head);
 154
 155         if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
 156                 return 0;
 157
 158         if (!nonblock)
 159                 return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
 160                                 TASK_UNINTERRUPTIBLE);
 161
 162         return -EAGAIN;
 163 }
 164
 165 /*
 166  * nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
 167  * @req - a request in the group
 168  *
 169  * This is a blocking call to wait for the group lock to be cleared.
 170  */
 171 void
 172 nfs_page_group_lock_wait(struct nfs_page *req)
 173 {
 174         struct nfs_page *head = req->wb_head;
 175
 176         WARN_ON_ONCE(head != head->wb_head);
 177
 178         wait_on_bit(&head->wb_flags, PG_HEADLOCK,
 179                 TASK_UNINTERRUPTIBLE);
 180 }
 181
 182 /*
 183  * nfs_page_group_unlock - unlock the head of the page group
 184  * @req - request in group that is to be unlocked
 185  */
 186 void
 187 nfs_page_group_unlock(struct nfs_page *req)
 188 {
 189         struct nfs_page *head = req->wb_head;
 190
 191         WARN_ON_ONCE(head != head->wb_head);
 192
 193         smp_mb__before_atomic();
 194         clear_bit(PG_HEADLOCK, &head->wb_flags);
 195         smp_mb__after_atomic();
 196         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
 197 }
 198
 199 /*
 200  * nfs_page_group_sync_on_bit_locked
 201  *
 202  * must be called with page group lock held
 203  */
 204 static bool
 205 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 206 {
 207         struct nfs_page *head = req->wb_head;
 208         struct nfs_page *tmp;
 209
 210         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 211         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 212
 213         tmp = req->wb_this_page;
 214         while (tmp != req) {
 215                 if (!test_bit(bit, &tmp->wb_flags))
 216                         return false;
 217                 tmp = tmp->wb_this_page;
 218         }
 219
 220         /* true! reset all bits */
 221         tmp = req;
 222         do {
 223                 clear_bit(bit, &tmp->wb_flags);
 224                 tmp = tmp->wb_this_page;
 225         } while (tmp != req);
 226
 227         return true;
 228 }
 229
 230 /*
 231  * nfs_page_group_sync_on_bit - set bit on current request, but only
 232  *   return true if the bit is set for all requests in page group
 233  * @req - request in page group
 234  * @bit - PG_* bit that is used to sync page group
 235  */
 236 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 237 {
 238         bool ret;
 239
 240         nfs_page_group_lock(req, false);
 241         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 242         nfs_page_group_unlock(req);
 243
 244         return ret;
 245 }
 246
 247 /*
 248  * nfs_page_group_init - Initialize the page group linkage for @req
 249  * @req - a new nfs request
 250  * @prev - the previous request in page group, or NULL if @req is the first
 251  *         or only request in the group (the head).
 252  */
 253 static inline void
 254 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 255 {
 256         struct inode *inode;
 257         WARN_ON_ONCE(prev == req);
 258
 259         if (!prev) {
 260                 /* a head request */
 261                 req->wb_head = req;
 262                 req->wb_this_page = req;
 263         } else {
 264                 /* a subrequest */
 265                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 266                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 267                 req->wb_head = prev->wb_head;
 268                 req->wb_this_page = prev->wb_this_page;
 269                 prev->wb_this_page = req;
 270
 271                 /* All subrequests take a ref on the head request until
 272                  * nfs_page_group_destroy is called */
 273                 kref_get(&req->wb_head->wb_kref);
 274
 275                 /* grab extra ref and bump the request count if head request
 276                  * has extra ref from the write/commit path to handle handoff
 277                  * between write and commit lists. */
 278                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 279                         inode = page_file_mapping(req->wb_page)->host;
 280                         set_bit(PG_INODE_REF, &req->wb_flags);
 281                         kref_get(&req->wb_kref);
 282                         spin_lock(&inode->i_lock);
 283                         NFS_I(inode)->nrequests++;
 284                         spin_unlock(&inode->i_lock);
 285                 }
 286         }
 287 }
 288
 289 /*
 290  * nfs_page_group_destroy - sync the destruction of page groups
 291  * @req - request that no longer needs the page group
 292  *
 293  * releases the page group reference from each member once all
 294  * members have called this function.
 295  */
 296 static void
 297 nfs_page_group_destroy(struct kref *kref)
 298 {
 299         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 300         struct nfs_page *tmp, *next;
 301
 302         /* subrequests must release the ref on the head request */
 303         if (req->wb_head != req)
 304                 nfs_release_request(req->wb_head);
 305
 306         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 307                 return;
 308
 309         tmp = req;
 310         do {
 311                 next = tmp->wb_this_page;
 312                 /* unlink and free */
 313                 tmp->wb_this_page = tmp;
 314                 tmp->wb_head = tmp;
 315                 nfs_free_request(tmp);
 316                 tmp = next;
 317         } while (tmp != req);
 318 }
 319
 320 /**
 321  * nfs_create_request - Create an NFS read/write request.
 322  * @ctx: open context to use
 323  * @page: page to write
 324  * @last: last nfs request created for this page group or NULL if head
 325  * @offset: starting offset within the page for the write
 326  * @count: number of bytes to read/write
 327  *
 328  * The page must be locked by the caller. This makes sure we never
 329  * create two different requests for the same page.
 330  * User should ensure it is safe to sleep in this function.
 331  */
 332 struct nfs_page *
 333 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 334                    struct nfs_page *last, unsigned int offset,
 335                    unsigned int count)
 336 {
 337         struct nfs_page         *req;
 338         struct nfs_lock_context *l_ctx;
 339
 340         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 341                 return ERR_PTR(-EBADF);
 342         /* try to allocate the request struct */
 343         req = nfs_page_alloc();
 344         if (req == NULL)
 345                 return ERR_PTR(-ENOMEM);
 346
 347         /* get lock context early so we can deal with alloc failures */
 348         l_ctx = nfs_get_lock_context(ctx);
 349         if (IS_ERR(l_ctx)) {
 350                 nfs_page_free(req);
 351                 return ERR_CAST(l_ctx);
 352         }
 353         req->wb_lock_context = l_ctx;
 354         atomic_inc(&l_ctx->io_count);
 355
 356         /* Initialize the request struct. Initially, we assume a
 357          * long write-back delay. This will be adjusted in
 358          * update_nfs_request below if the region is not locked. */
 359         req->wb_page    = page;
 360         if (page) {
 361                 req->wb_index = page_index(page);
 362                 get_page(page);
 363         }
 364         req->wb_offset  = offset;
 365         req->wb_pgbase  = offset;
 366         req->wb_bytes   = count;
 367         req->wb_context = get_nfs_open_context(ctx);
 368         kref_init(&req->wb_kref);
 369         nfs_page_group_init(req, last);
 370         return req;
 371 }
 372
 373 /**
 374  * nfs_unlock_request - Unlock request and wake up sleepers.
 375  * @req:
 376  */
 377 void nfs_unlock_request(struct nfs_page *req)
 378 {
 379         if (!NFS_WBACK_BUSY(req)) {
 380                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 381                 BUG();
 382         }
 383         smp_mb__before_atomic();
 384         clear_bit(PG_BUSY, &req->wb_flags);
 385         smp_mb__after_atomic();
 386         wake_up_bit(&req->wb_flags, PG_BUSY);
 387 }
 388
 389 /**
 390  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 391  * @req:
 392  */
 393 void nfs_unlock_and_release_request(struct nfs_page *req)
 394 {
 395         nfs_unlock_request(req);
 396         nfs_release_request(req);
 397 }
 398
 399 /*
 400  * nfs_clear_request - Free up all resources allocated to the request
 401  * @req:
 402  *
 403  * Release page and open context resources associated with a read/write
 404  * request after it has completed.
 405  */
 406 static void nfs_clear_request(struct nfs_page *req)
 407 {
 408         struct page *page = req->wb_page;
 409         struct nfs_open_context *ctx = req->wb_context;
 410         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 411
 412         if (page != NULL) {
 413                 put_page(page);
 414                 req->wb_page = NULL;
 415         }
 416         if (l_ctx != NULL) {
 417                 if (atomic_dec_and_test(&l_ctx->io_count)) {
 418                         wake_up_atomic_t(&l_ctx->io_count);
 419                         if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
 420                                 rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
 421                 }
 422                 nfs_put_lock_context(l_ctx);
 423                 req->wb_lock_context = NULL;
 424         }
 425         if (ctx != NULL) {
 426                 put_nfs_open_context(ctx);
 427                 req->wb_context = NULL;
 428         }
 429 }
 430
 431 /**
 432  * nfs_release_request - Release the count on an NFS read/write request
 433  * @req: request to release
 434  *
 435  * Note: Should never be called with the spinlock held!
 436  */
 437 void nfs_free_request(struct nfs_page *req)
 438 {
 439         WARN_ON_ONCE(req->wb_this_page != req);
 440
 441         /* extra debug: make sure no sync bits are still set */
 442         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 443         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 444         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 445         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 446         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 447
 448         /* Release struct file and open context */
 449         nfs_clear_request(req);
 450         nfs_page_free(req);
 451 }
 452
 453 void nfs_release_request(struct nfs_page *req)
 454 {
 455         kref_put(&req->wb_kref, nfs_page_group_destroy);
 456 }
 457
 458 /**
 459  * nfs_wait_on_request - Wait for a request to complete.
 460  * @req: request to wait upon.
 461  *
 462  * Interruptible by fatal signals only.
 463  * The user is responsible for holding a count on the request.
 464  */
 465 int
 466 nfs_wait_on_request(struct nfs_page *req)
 467 {
 468         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 469                               TASK_UNINTERRUPTIBLE);
 470 }
 471
 472 /*
 473  * nfs_generic_pg_test - determine if requests can be coalesced
 474  * @desc: pointer to descriptor
 475  * @prev: previous request in desc, or NULL
 476  * @req: this request
 477  *
 478  * Returns zero if @req can be coalesced into @desc, otherwise it returns
 479  * the size of the request.
 480  */
 481 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 482                            struct nfs_page *prev, struct nfs_page *req)
 483 {
 484         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 485
 486
 487         if (mirror->pg_count > mirror->pg_bsize) {
 488                 /* should never happen */
 489                 WARN_ON_ONCE(1);
 490                 return 0;
 491         }
 492
 493         /*
 494          * Limit the request size so that we can still allocate a page array
 495          * for it without upsetting the slab allocator.
 496          */
 497         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 498                         sizeof(struct page *) > PAGE_SIZE)
 499                 return 0;
 500
 501         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 502 }
 503 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 504
 505 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 506 {
 507         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 508
 509         if (hdr) {
 510                 INIT_LIST_HEAD(&hdr->pages);
 511                 spin_lock_init(&hdr->lock);
 512                 hdr->rw_ops = ops;
 513         }
 514         return hdr;
 515 }
 516 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 517
 518 /*
 519  * nfs_pgio_header_free - Free a read or write header
 520  * @hdr: The header to free
 521  */
 522 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 523 {
 524         hdr->rw_ops->rw_free_header(hdr);
 525 }
 526 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 527
 528 /**
 529  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 530  *
 531  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 532  * be called again.
 533  *
 534  * @hdr: A header that has had nfs_generic_pgio called
 535  */
 536 void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 537 {
 538         if (hdr->args.context)
 539                 put_nfs_open_context(hdr->args.context);
 540         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 541                 kfree(hdr->page_array.pagevec);
 542 }
 543 EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
 544
 545 /**
 546  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 547  * @hdr: The pageio hdr
 548  * @count: Number of bytes to read
 549  * @offset: Initial offset
 550  * @how: How to commit data (writes only)
 551  * @cinfo: Commit information for the call (writes only)
 552  */
 553 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 554                               unsigned int count, unsigned int offset,
 555                               int how, struct nfs_commit_info *cinfo)
 556 {
 557         struct nfs_page *req = hdr->req;
 558
 559         /* Set up the RPC argument and reply structs
 560          * NB: take care not to mess about with hdr->commit et al. */
 561
 562         hdr->args.fh     = NFS_FH(hdr->inode);
 563         hdr->args.offset = req_offset(req) + offset;
 564         /* pnfs_set_layoutcommit needs this */
 565         hdr->mds_offset = hdr->args.offset;
 566         hdr->args.pgbase = req->wb_pgbase + offset;
 567         hdr->args.pages  = hdr->page_array.pagevec;
 568         hdr->args.count  = count;
 569         hdr->args.context = get_nfs_open_context(req->wb_context);
 570         hdr->args.lock_context = req->wb_lock_context;
 571         hdr->args.stable  = NFS_UNSTABLE;
 572         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 573         case 0:
 574                 break;
 575         case FLUSH_COND_STABLE:
 576                 if (nfs_reqs_to_commit(cinfo))
 577                         break;
 578         default:
 579                 hdr->args.stable = NFS_FILE_SYNC;
 580         }
 581
 582         hdr->res.fattr   = &hdr->fattr;
 583         hdr->res.count   = count;
 584         hdr->res.eof     = 0;
 585         hdr->res.verf    = &hdr->verf;
 586         nfs_fattr_init(&hdr->fattr);
 587 }
 588
 589 /**
 590  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 591  * @task: The current task
 592  * @calldata: pageio header to prepare
 593  */
 594 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 595 {
 596         struct nfs_pgio_header *hdr = calldata;
 597         int err;
 598         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 599         if (err)
 600                 rpc_exit(task, err);
 601 }
 602
 603 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 604                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
 605                       const struct rpc_call_ops *call_ops, int how, int flags)
 606 {
 607         struct rpc_task *task;
 608         struct rpc_message msg = {
 609                 .rpc_argp = &hdr->args,
 610                 .rpc_resp = &hdr->res,
 611                 .rpc_cred = cred,
 612         };
 613         struct rpc_task_setup task_setup_data = {
 614                 .rpc_client = clnt,
 615                 .task = &hdr->task,
 616                 .rpc_message = &msg,
 617                 .callback_ops = call_ops,
 618                 .callback_data = hdr,
 619                 .workqueue = nfsiod_workqueue,
 620                 .flags = RPC_TASK_ASYNC | flags,
 621         };
 622         int ret = 0;
 623
 624         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 625
 626         dprintk("NFS: initiated pgio call "
 627                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 628                 hdr->inode->i_sb->s_id,
 629                 (unsigned long long)NFS_FILEID(hdr->inode),
 630                 hdr->args.count,
 631                 (unsigned long long)hdr->args.offset);
 632
 633         task = rpc_run_task(&task_setup_data);
 634         if (IS_ERR(task)) {
 635                 ret = PTR_ERR(task);
 636                 goto out;
 637         }
 638         if (how & FLUSH_SYNC) {
 639                 ret = rpc_wait_for_completion_task(task);
 640                 if (ret == 0)
 641                         ret = task->tk_status;
 642         }
 643         rpc_put_task(task);
 644 out:
 645         return ret;
 646 }
 647 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 648
 649 /**
 650  * nfs_pgio_error - Clean up from a pageio error
 651  * @desc: IO descriptor
 652  * @hdr: pageio header
 653  */
 654 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 655 {
 656         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 657         nfs_pgio_data_destroy(hdr);
 658         hdr->completion_ops->completion(hdr);
 659 }
 660
 661 /**
 662  * nfs_pgio_release - Release pageio data
 663  * @calldata: The pageio header to release
 664  */
 665 static void nfs_pgio_release(void *calldata)
 666 {
 667         struct nfs_pgio_header *hdr = calldata;
 668         nfs_pgio_data_destroy(hdr);
 669         hdr->completion_ops->completion(hdr);
 670 }
 671
 672 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 673                                    unsigned int bsize)
 674 {
 675         INIT_LIST_HEAD(&mirror->pg_list);
 676         mirror->pg_bytes_written = 0;
 677         mirror->pg_count = 0;
 678         mirror->pg_bsize = bsize;
 679         mirror->pg_base = 0;
 680         mirror->pg_recoalesce = 0;
 681 }
 682
 683 /**
 684  * nfs_pageio_init - initialise a page io descriptor
 685  * @desc: pointer to descriptor
 686  * @inode: pointer to inode
 687  * @pg_ops: pointer to pageio operations
 688  * @compl_ops: pointer to pageio completion operations
 689  * @rw_ops: pointer to nfs read/write operations
 690  * @bsize: io block size
 691  * @io_flags: extra parameters for the io function
 692  */
 693 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 694                      struct inode *inode,
 695                      const struct nfs_pageio_ops *pg_ops,
 696                      const struct nfs_pgio_completion_ops *compl_ops,
 697                      const struct nfs_rw_ops *rw_ops,
 698                      size_t bsize,
 699                      int io_flags,
 700                      gfp_t gfp_flags)
 701 {
 702         struct nfs_pgio_mirror *new;
 703         int i;
 704
 705         desc->pg_moreio = 0;
 706         desc->pg_inode = inode;
 707         desc->pg_ops = pg_ops;
 708         desc->pg_completion_ops = compl_ops;
 709         desc->pg_rw_ops = rw_ops;
 710         desc->pg_ioflags = io_flags;
 711         desc->pg_error = 0;
 712         desc->pg_lseg = NULL;
 713         desc->pg_dreq = NULL;
 714         desc->pg_layout_private = NULL;
 715         desc->pg_bsize = bsize;
 716
 717         desc->pg_mirror_count = 1;
 718         desc->pg_mirror_idx = 0;
 719
 720         if (pg_ops->pg_get_mirror_count) {
 721                 /* until we have a request, we don't have an lseg and no
 722                  * idea how many mirrors there will be */
 723                 new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
 724                               sizeof(struct nfs_pgio_mirror), gfp_flags);
 725                 desc->pg_mirrors_dynamic = new;
 726                 desc->pg_mirrors = new;
 727
 728                 for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
 729                         nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
 730         } else {
 731                 desc->pg_mirrors_dynamic = NULL;
 732                 desc->pg_mirrors = desc->pg_mirrors_static;
 733                 nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 734         }
 735 }
 736 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 737
 738 /**
 739  * nfs_pgio_result - Basic pageio error handling
 740  * @task: The task that ran
 741  * @calldata: Pageio header to check
 742  */
 743 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 744 {
 745         struct nfs_pgio_header *hdr = calldata;
 746         struct inode *inode = hdr->inode;
 747
 748         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 749                 task->tk_pid, task->tk_status);
 750
 751         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 752                 return;
 753         if (task->tk_status < 0)
 754                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 755         else
 756                 hdr->rw_ops->rw_result(task, hdr);
 757 }
 758
 759 /*
 760  * Create an RPC task for the given read or write request and kick it.
 761  * The page must have been locked by the caller.
 762  *
 763  * It may happen that the page we're passed is not marked dirty.
 764  * This is the case if nfs_updatepage detects a conflicting request
 765  * that has been written but not committed.
 766  */
 767 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 768                      struct nfs_pgio_header *hdr)
 769 {
 770         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 771
 772         struct nfs_page         *req;
 773         struct page             **pages,
 774                                 *last_page;
 775         struct list_head *head = &mirror->pg_list;
 776         struct nfs_commit_info cinfo;
 777         struct nfs_page_array *pg_array = &hdr->page_array;
 778         unsigned int pagecount, pageused;
 779         gfp_t gfp_flags = GFP_KERNEL;
 780
 781         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 782
 783         if (pagecount <= ARRAY_SIZE(pg_array->page_array))
 784                 pg_array->pagevec = pg_array->page_array;
 785         else {
 786                 if (hdr->rw_mode == FMODE_WRITE)
 787                         gfp_flags = GFP_NOIO;
 788                 pg_array->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
 789                 if (!pg_array->pagevec) {
 790                         pg_array->npages = 0;
 791                         nfs_pgio_error(hdr);
 792                         desc->pg_error = -ENOMEM;
 793                         return desc->pg_error;
 794                 }
 795         }
 796
 797         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 798         pages = hdr->page_array.pagevec;
 799         last_page = NULL;
 800         pageused = 0;
 801         while (!list_empty(head)) {
 802                 req = nfs_list_entry(head->next);
 803                 nfs_list_remove_request(req);
 804                 nfs_list_add_request(req, &hdr->pages);
 805
 806                 if (!last_page || last_page != req->wb_page) {
 807                         pageused++;
 808                         if (pageused > pagecount)
 809                                 break;
 810                         *pages++ = last_page = req->wb_page;
 811                 }
 812         }
 813         if (WARN_ON_ONCE(pageused != pagecount)) {
 814                 nfs_pgio_error(hdr);
 815                 desc->pg_error = -EINVAL;
 816                 return desc->pg_error;
 817         }
 818
 819         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 820             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 821                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 822
 823         /* Set up the argument struct */
 824         nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
 825         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 826         return 0;
 827 }
 828 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 829
 830 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 831 {
 832         struct nfs_pgio_header *hdr;
 833         int ret;
 834
 835         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 836         if (!hdr) {
 837                 desc->pg_error = -ENOMEM;
 838                 return desc->pg_error;
 839         }
 840         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 841         ret = nfs_generic_pgio(desc, hdr);
 842         if (ret == 0)
 843                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 844                                         hdr,
 845                                         hdr->cred,
 846                                         NFS_PROTO(hdr->inode),
 847                                         desc->pg_rpc_callops,
 848                                         desc->pg_ioflags, 0);
 849         return ret;
 850 }
 851
 852 /*
 853  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 854  *                              by calling the pg_get_mirror_count op
 855  */
 856 static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 857                                        struct nfs_page *req)
 858 {
 859         int mirror_count = 1;
 860
 861         if (!pgio->pg_ops->pg_get_mirror_count)
 862                 return 0;
 863
 864         mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 865
 866         if (pgio->pg_error < 0)
 867                 return pgio->pg_error;
 868
 869         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
 870                 return -EINVAL;
 871
 872         if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
 873                 return -EINVAL;
 874
 875         pgio->pg_mirror_count = mirror_count;
 876
 877         return 0;
 878 }
 879
 880 /*
 881  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
 882  */
 883 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
 884 {
 885         pgio->pg_mirror_count = 1;
 886         pgio->pg_mirror_idx = 0;
 887 }
 888
 889 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 890 {
 891         pgio->pg_mirror_count = 1;
 892         pgio->pg_mirror_idx = 0;
 893         pgio->pg_mirrors = pgio->pg_mirrors_static;
 894         kfree(pgio->pg_mirrors_dynamic);
 895         pgio->pg_mirrors_dynamic = NULL;
 896 }
 897
 898 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 899                 const struct nfs_lock_context *l2)
 900 {
 901         return l1->lockowner == l2->lockowner;
 902 }
 903
 904 /**
 905  * nfs_can_coalesce_requests - test two requests for compatibility
 906  * @prev: pointer to nfs_page
 907  * @req: pointer to nfs_page
 908  *
 909  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 910  * page data area they describe is contiguous, and that their RPC
 911  * credentials, NFSv4 open state, and lockowners are the same.
 912  *
 913  * Return 'true' if this is the case, else return 'false'.
 914  */
 915 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 916                                       struct nfs_page *req,
 917                                       struct nfs_pageio_descriptor *pgio)
 918 {
 919         size_t size;
 920         struct file_lock_context *flctx;
 921
 922         if (prev) {
 923                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 924                         return false;
 925                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
 926                 if (flctx != NULL &&
 927                     !(list_empty_careful(&flctx->flc_posix) &&
 928                       list_empty_careful(&flctx->flc_flock)) &&
 929                     !nfs_match_lock_context(req->wb_lock_context,
 930                                             prev->wb_lock_context))
 931                         return false;
 932                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 933                         return false;
 934                 if (req->wb_page == prev->wb_page) {
 935                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 936                                 return false;
 937                 } else {
 938                         if (req->wb_pgbase != 0 ||
 939                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 940                                 return false;
 941                 }
 942         }
 943         size = pgio->pg_ops->pg_test(pgio, prev, req);
 944         WARN_ON_ONCE(size > req->wb_bytes);
 945         if (size && size < req->wb_bytes)
 946                 req->wb_bytes = size;
 947         return size > 0;
 948 }
 949
 950 /**
 951  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 952  * @desc: destination io descriptor
 953  * @req: request
 954  *
 955  * Returns true if the request 'req' was successfully coalesced into the
 956  * existing list of pages 'desc'.
 957  */
 958 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 959                                      struct nfs_page *req)
 960 {
 961         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 962
 963         struct nfs_page *prev = NULL;
 964
 965         if (mirror->pg_count != 0) {
 966                 prev = nfs_list_entry(mirror->pg_list.prev);
 967         } else {
 968                 if (desc->pg_ops->pg_init)
 969                         desc->pg_ops->pg_init(desc, req);
 970                 if (desc->pg_error < 0)
 971                         return 0;
 972                 mirror->pg_base = req->wb_pgbase;
 973         }
 974         if (!nfs_can_coalesce_requests(prev, req, desc))
 975                 return 0;
 976         nfs_list_remove_request(req);
 977         nfs_list_add_request(req, &mirror->pg_list);
 978         mirror->pg_count += req->wb_bytes;
 979         return 1;
 980 }
 981
 982 /*
 983  * Helper for nfs_pageio_add_request and nfs_pageio_complete
 984  */
 985 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 986 {
 987         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 988
 989
 990         if (!list_empty(&mirror->pg_list)) {
 991                 int error = desc->pg_ops->pg_doio(desc);
 992                 if (error < 0)
 993                         desc->pg_error = error;
 994                 else
 995                         mirror->pg_bytes_written += mirror->pg_count;
 996         }
 997         if (list_empty(&mirror->pg_list)) {
 998                 mirror->pg_count = 0;
 999                 mirror->pg_base = 0;
1000         }
1001 }
1002
1003 /**
1004  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
1005  * @desc: destination io descriptor
1006  * @req: request
1007  *
1008  * This may split a request into subrequests which are all part of the
1009  * same page group.
1010  *
1011  * Returns true if the request 'req' was successfully coalesced into the
1012  * existing list of pages 'desc'.
1013  */
1014 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1015                            struct nfs_page *req)
1016 {
1017         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1018
1019         struct nfs_page *subreq;
1020         unsigned int bytes_left = 0;
1021         unsigned int offset, pgbase;
1022
1023         nfs_page_group_lock(req, false);
1024
1025         subreq = req;
1026         bytes_left = subreq->wb_bytes;
1027         offset = subreq->wb_offset;
1028         pgbase = subreq->wb_pgbase;
1029
1030         do {
1031                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1032                         /* make sure pg_test call(s) did nothing */
1033                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1034                         WARN_ON_ONCE(subreq->wb_offset != offset);
1035                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1036
1037                         nfs_page_group_unlock(req);
1038                         desc->pg_moreio = 1;
1039                         nfs_pageio_doio(desc);
1040                         if (desc->pg_error < 0)
1041                                 return 0;
1042                         if (mirror->pg_recoalesce)
1043                                 return 0;
1044                         /* retry add_request for this subreq */
1045                         nfs_page_group_lock(req, false);
1046                         continue;
1047                 }
1048
1049                 /* check for buggy pg_test call(s) */
1050                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1051                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1052                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1053
1054                 bytes_left -= subreq->wb_bytes;
1055                 offset += subreq->wb_bytes;
1056                 pgbase += subreq->wb_bytes;
1057
1058                 if (bytes_left) {
1059                         subreq = nfs_create_request(req->wb_context,
1060                                         req->wb_page,
1061                                         subreq, pgbase, bytes_left);
1062                         if (IS_ERR(subreq))
1063                                 goto err_ptr;
1064                         nfs_lock_request(subreq);
1065                         subreq->wb_offset  = offset;
1066                         subreq->wb_index = req->wb_index;
1067                 }
1068         } while (bytes_left > 0);
1069
1070         nfs_page_group_unlock(req);
1071         return 1;
1072 err_ptr:
1073         desc->pg_error = PTR_ERR(subreq);
1074         nfs_page_group_unlock(req);
1075         return 0;
1076 }
1077
1078 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1079 {
1080         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1081         LIST_HEAD(head);
1082
1083         do {
1084                 list_splice_init(&mirror->pg_list, &head);
1085                 mirror->pg_bytes_written -= mirror->pg_count;
1086                 mirror->pg_count = 0;
1087                 mirror->pg_base = 0;
1088                 mirror->pg_recoalesce = 0;
1089
1090                 while (!list_empty(&head)) {
1091                         struct nfs_page *req;
1092
1093                         req = list_first_entry(&head, struct nfs_page, wb_list);
1094                         nfs_list_remove_request(req);
1095                         if (__nfs_pageio_add_request(desc, req))
1096                                 continue;
1097                         if (desc->pg_error < 0) {
1098                                 list_splice_tail(&head, &mirror->pg_list);
1099                                 mirror->pg_recoalesce = 1;
1100                                 return 0;
1101                         }
1102                         break;
1103                 }
1104         } while (mirror->pg_recoalesce);
1105         return 1;
1106 }
1107
1108 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1109                 struct nfs_page *req)
1110 {
1111         int ret;
1112
1113         do {
1114                 ret = __nfs_pageio_add_request(desc, req);
1115                 if (ret)
1116                         break;
1117                 if (desc->pg_error < 0)
1118                         break;
1119                 ret = nfs_do_recoalesce(desc);
1120         } while (ret);
1121
1122         return ret;
1123 }
1124
1125 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1126                            struct nfs_page *req)
1127 {
1128         u32 midx;
1129         unsigned int pgbase, offset, bytes;
1130         struct nfs_page *dupreq, *lastreq;
1131
1132         pgbase = req->wb_pgbase;
1133         offset = req->wb_offset;
1134         bytes = req->wb_bytes;
1135
1136         nfs_pageio_setup_mirroring(desc, req);
1137         if (desc->pg_error < 0)
1138                 goto out_failed;
1139
1140         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1141                 if (midx) {
1142                         nfs_page_group_lock(req, false);
1143
1144                         /* find the last request */
1145                         for (lastreq = req->wb_head;
1146                              lastreq->wb_this_page != req->wb_head;
1147                              lastreq = lastreq->wb_this_page)
1148                                 ;
1149
1150                         dupreq = nfs_create_request(req->wb_context,
1151                                         req->wb_page, lastreq, pgbase, bytes);
1152
1153                         if (IS_ERR(dupreq)) {
1154                                 nfs_page_group_unlock(req);
1155                                 desc->pg_error = PTR_ERR(dupreq);
1156                                 goto out_failed;
1157                         }
1158
1159                         nfs_lock_request(dupreq);
1160                         nfs_page_group_unlock(req);
1161                         dupreq->wb_offset = offset;
1162                         dupreq->wb_index = req->wb_index;
1163                 } else
1164                         dupreq = req;
1165
1166                 if (nfs_pgio_has_mirroring(desc))
1167                         desc->pg_mirror_idx = midx;
1168                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1169                         goto out_failed;
1170         }
1171
1172         return 1;
1173
1174 out_failed:
1175         /*
1176          * We might have failed before sending any reqs over wire.
1177          * Clean up rest of the reqs in mirror pg_list.
1178          */
1179         if (desc->pg_error) {
1180                 struct nfs_pgio_mirror *mirror;
1181                 void (*func)(struct list_head *);
1182
1183                 /* remember fatal errors */
1184                 if (nfs_error_is_fatal(desc->pg_error))
1185                         mapping_set_error(desc->pg_inode->i_mapping,
1186                                           desc->pg_error);
1187
1188                 func = desc->pg_completion_ops->error_cleanup;
1189                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1190                         mirror = &desc->pg_mirrors[midx];
1191                         func(&mirror->pg_list);
1192                 }
1193         }
1194         return 0;
1195 }
1196
1197 /*
1198  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1199  *                              nfs_pageio_descriptor
1200  * @desc: pointer to io descriptor
1201  * @mirror_idx: pointer to mirror index
1202  */
1203 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1204                                        u32 mirror_idx)
1205 {
1206         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1207         u32 restore_idx = desc->pg_mirror_idx;
1208
1209         if (nfs_pgio_has_mirroring(desc))
1210                 desc->pg_mirror_idx = mirror_idx;
1211         for (;;) {
1212                 nfs_pageio_doio(desc);
1213                 if (!mirror->pg_recoalesce)
1214                         break;
1215                 if (!nfs_do_recoalesce(desc))
1216                         break;
1217         }
1218         desc->pg_mirror_idx = restore_idx;
1219 }
1220
1221 /*
1222  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1223  * @hdr - the pgio header to move request from
1224  * @desc - the pageio descriptor to add requests to
1225  *
1226  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1227  * to send them.
1228  *
1229  * Returns 0 on success and < 0 on error.
1230  */
1231 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1232                       struct nfs_pgio_header *hdr)
1233 {
1234         LIST_HEAD(failed);
1235
1236         desc->pg_dreq = hdr->dreq;
1237         while (!list_empty(&hdr->pages)) {
1238                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1239
1240                 nfs_list_remove_request(req);
1241                 if (!nfs_pageio_add_request(desc, req))
1242                         nfs_list_add_request(req, &failed);
1243         }
1244         nfs_pageio_complete(desc);
1245         if (!list_empty(&failed)) {
1246                 list_move(&failed, &hdr->pages);
1247                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1248         }
1249         return 0;
1250 }
1251 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1252
1253 /**
1254  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1255  * @desc: pointer to io descriptor
1256  */
1257 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1258 {
1259         u32 midx;
1260
1261         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1262                 nfs_pageio_complete_mirror(desc, midx);
1263
1264         if (desc->pg_ops->pg_cleanup)
1265                 desc->pg_ops->pg_cleanup(desc);
1266         nfs_pageio_cleanup_mirroring(desc);
1267 }
1268
1269 /**
1270  * nfs_pageio_cond_complete - Conditional I/O completion
1271  * @desc: pointer to io descriptor
1272  * @index: page index
1273  *
1274  * It is important to ensure that processes don't try to take locks
1275  * on non-contiguous ranges of pages as that might deadlock. This
1276  * function should be called before attempting to wait on a locked
1277  * nfs_page. It will complete the I/O if the page index 'index'
1278  * is not contiguous with the existing list of pages in 'desc'.
1279  */
1280 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1281 {
1282         struct nfs_pgio_mirror *mirror;
1283         struct nfs_page *prev;
1284         u32 midx;
1285
1286         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1287                 mirror = &desc->pg_mirrors[midx];
1288                 if (!list_empty(&mirror->pg_list)) {
1289                         prev = nfs_list_entry(mirror->pg_list.prev);
1290                         if (index != prev->wb_index + 1) {
1291                                 nfs_pageio_complete(desc);
1292                                 break;
1293                         }
1294                 }
1295         }
1296 }
1297
1298 int __init nfs_init_nfspagecache(void)
1299 {
1300         nfs_page_cachep = kmem_cache_create("nfs_page",
1301                                             sizeof(struct nfs_page),
1302                                             0, SLAB_HWCACHE_ALIGN,
1303                                             NULL);
1304         if (nfs_page_cachep == NULL)
1305                 return -ENOMEM;
1306
1307         return 0;
1308 }
1309
1310 void nfs_destroy_nfspagecache(void)
1311 {
1312         kmem_cache_destroy(nfs_page_cachep);
1313 }
1314
1315 static const struct rpc_call_ops nfs_pgio_common_ops = {
1316         .rpc_call_prepare = nfs_pgio_prepare,
1317         .rpc_call_done = nfs_pgio_result,
1318         .rpc_release = nfs_pgio_release,
1319 };
1320
1321 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1322         .pg_test = nfs_generic_pg_test,
1323         .pg_doio = nfs_generic_pg_pgios,
1324 };