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 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->io_completion = desc->pg_io_completion;
  54         hdr->dreq = desc->pg_dreq;
  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                 set_bit(PG_CONTENDED1, &head->wb_flags);
 160                 smp_mb__after_atomic();
 161                 return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
 162                                 TASK_UNINTERRUPTIBLE);
 163         }
 164
 165         return -EAGAIN;
 166 }
 167
 168 /*
 169  * nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
 170  * @req - a request in the group
 171  *
 172  * This is a blocking call to wait for the group lock to be cleared.
 173  */
 174 void
 175 nfs_page_group_lock_wait(struct nfs_page *req)
 176 {
 177         struct nfs_page *head = req->wb_head;
 178
 179         WARN_ON_ONCE(head != head->wb_head);
 180
 181         if (!test_bit(PG_HEADLOCK, &head->wb_flags))
 182                 return;
 183         set_bit(PG_CONTENDED1, &head->wb_flags);
 184         smp_mb__after_atomic();
 185         wait_on_bit(&head->wb_flags, PG_HEADLOCK,
 186                 TASK_UNINTERRUPTIBLE);
 187 }
 188
 189 /*
 190  * nfs_page_group_unlock - unlock the head of the page group
 191  * @req - request in group that is to be unlocked
 192  */
 193 void
 194 nfs_page_group_unlock(struct nfs_page *req)
 195 {
 196         struct nfs_page *head = req->wb_head;
 197
 198         WARN_ON_ONCE(head != head->wb_head);
 199
 200         smp_mb__before_atomic();
 201         clear_bit(PG_HEADLOCK, &head->wb_flags);
 202         smp_mb__after_atomic();
 203         if (!test_bit(PG_CONTENDED1, &head->wb_flags))
 204                 return;
 205         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
 206 }
 207
 208 /*
 209  * nfs_page_group_sync_on_bit_locked
 210  *
 211  * must be called with page group lock held
 212  */
 213 static bool
 214 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 215 {
 216         struct nfs_page *head = req->wb_head;
 217         struct nfs_page *tmp;
 218
 219         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 220         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 221
 222         tmp = req->wb_this_page;
 223         while (tmp != req) {
 224                 if (!test_bit(bit, &tmp->wb_flags))
 225                         return false;
 226                 tmp = tmp->wb_this_page;
 227         }
 228
 229         /* true! reset all bits */
 230         tmp = req;
 231         do {
 232                 clear_bit(bit, &tmp->wb_flags);
 233                 tmp = tmp->wb_this_page;
 234         } while (tmp != req);
 235
 236         return true;
 237 }
 238
 239 /*
 240  * nfs_page_group_sync_on_bit - set bit on current request, but only
 241  *   return true if the bit is set for all requests in page group
 242  * @req - request in page group
 243  * @bit - PG_* bit that is used to sync page group
 244  */
 245 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 246 {
 247         bool ret;
 248
 249         nfs_page_group_lock(req, false);
 250         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 251         nfs_page_group_unlock(req);
 252
 253         return ret;
 254 }
 255
 256 /*
 257  * nfs_page_group_init - Initialize the page group linkage for @req
 258  * @req - a new nfs request
 259  * @prev - the previous request in page group, or NULL if @req is the first
 260  *         or only request in the group (the head).
 261  */
 262 static inline void
 263 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 264 {
 265         struct inode *inode;
 266         WARN_ON_ONCE(prev == req);
 267
 268         if (!prev) {
 269                 /* a head request */
 270                 req->wb_head = req;
 271                 req->wb_this_page = req;
 272         } else {
 273                 /* a subrequest */
 274                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 275                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 276                 req->wb_head = prev->wb_head;
 277                 req->wb_this_page = prev->wb_this_page;
 278                 prev->wb_this_page = req;
 279
 280                 /* All subrequests take a ref on the head request until
 281                  * nfs_page_group_destroy is called */
 282                 kref_get(&req->wb_head->wb_kref);
 283
 284                 /* grab extra ref and bump the request count if head request
 285                  * has extra ref from the write/commit path to handle handoff
 286                  * between write and commit lists. */
 287                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 288                         inode = page_file_mapping(req->wb_page)->host;
 289                         set_bit(PG_INODE_REF, &req->wb_flags);
 290                         kref_get(&req->wb_kref);
 291                         spin_lock(&inode->i_lock);
 292                         NFS_I(inode)->nrequests++;
 293                         spin_unlock(&inode->i_lock);
 294                 }
 295         }
 296 }
 297
 298 /*
 299  * nfs_page_group_destroy - sync the destruction of page groups
 300  * @req - request that no longer needs the page group
 301  *
 302  * releases the page group reference from each member once all
 303  * members have called this function.
 304  */
 305 static void
 306 nfs_page_group_destroy(struct kref *kref)
 307 {
 308         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 309         struct nfs_page *tmp, *next;
 310
 311         /* subrequests must release the ref on the head request */
 312         if (req->wb_head != req)
 313                 nfs_release_request(req->wb_head);
 314
 315         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 316                 return;
 317
 318         tmp = req;
 319         do {
 320                 next = tmp->wb_this_page;
 321                 /* unlink and free */
 322                 tmp->wb_this_page = tmp;
 323                 tmp->wb_head = tmp;
 324                 nfs_free_request(tmp);
 325                 tmp = next;
 326         } while (tmp != req);
 327 }
 328
 329 /**
 330  * nfs_create_request - Create an NFS read/write request.
 331  * @ctx: open context to use
 332  * @page: page to write
 333  * @last: last nfs request created for this page group or NULL if head
 334  * @offset: starting offset within the page for the write
 335  * @count: number of bytes to read/write
 336  *
 337  * The page must be locked by the caller. This makes sure we never
 338  * create two different requests for the same page.
 339  * User should ensure it is safe to sleep in this function.
 340  */
 341 struct nfs_page *
 342 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 343                    struct nfs_page *last, unsigned int offset,
 344                    unsigned int count)
 345 {
 346         struct nfs_page         *req;
 347         struct nfs_lock_context *l_ctx;
 348
 349         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 350                 return ERR_PTR(-EBADF);
 351         /* try to allocate the request struct */
 352         req = nfs_page_alloc();
 353         if (req == NULL)
 354                 return ERR_PTR(-ENOMEM);
 355
 356         /* get lock context early so we can deal with alloc failures */
 357         l_ctx = nfs_get_lock_context(ctx);
 358         if (IS_ERR(l_ctx)) {
 359                 nfs_page_free(req);
 360                 return ERR_CAST(l_ctx);
 361         }
 362         req->wb_lock_context = l_ctx;
 363         atomic_inc(&l_ctx->io_count);
 364
 365         /* Initialize the request struct. Initially, we assume a
 366          * long write-back delay. This will be adjusted in
 367          * update_nfs_request below if the region is not locked. */
 368         req->wb_page    = page;
 369         if (page) {
 370                 req->wb_index = page_index(page);
 371                 get_page(page);
 372         }
 373         req->wb_offset  = offset;
 374         req->wb_pgbase  = offset;
 375         req->wb_bytes   = count;
 376         req->wb_context = get_nfs_open_context(ctx);
 377         kref_init(&req->wb_kref);
 378         nfs_page_group_init(req, last);
 379         return req;
 380 }
 381
 382 /**
 383  * nfs_unlock_request - Unlock request and wake up sleepers.
 384  * @req:
 385  */
 386 void nfs_unlock_request(struct nfs_page *req)
 387 {
 388         if (!NFS_WBACK_BUSY(req)) {
 389                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 390                 BUG();
 391         }
 392         smp_mb__before_atomic();
 393         clear_bit(PG_BUSY, &req->wb_flags);
 394         smp_mb__after_atomic();
 395         if (!test_bit(PG_CONTENDED2, &req->wb_flags))
 396                 return;
 397         wake_up_bit(&req->wb_flags, PG_BUSY);
 398 }
 399
 400 /**
 401  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 402  * @req:
 403  */
 404 void nfs_unlock_and_release_request(struct nfs_page *req)
 405 {
 406         nfs_unlock_request(req);
 407         nfs_release_request(req);
 408 }
 409
 410 /*
 411  * nfs_clear_request - Free up all resources allocated to the request
 412  * @req:
 413  *
 414  * Release page and open context resources associated with a read/write
 415  * request after it has completed.
 416  */
 417 static void nfs_clear_request(struct nfs_page *req)
 418 {
 419         struct page *page = req->wb_page;
 420         struct nfs_open_context *ctx = req->wb_context;
 421         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 422
 423         if (page != NULL) {
 424                 put_page(page);
 425                 req->wb_page = NULL;
 426         }
 427         if (l_ctx != NULL) {
 428                 if (atomic_dec_and_test(&l_ctx->io_count)) {
 429                         wake_up_atomic_t(&l_ctx->io_count);
 430                         if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
 431                                 rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
 432                 }
 433                 nfs_put_lock_context(l_ctx);
 434                 req->wb_lock_context = NULL;
 435         }
 436         if (ctx != NULL) {
 437                 put_nfs_open_context(ctx);
 438                 req->wb_context = NULL;
 439         }
 440 }
 441
 442 /**
 443  * nfs_release_request - Release the count on an NFS read/write request
 444  * @req: request to release
 445  *
 446  * Note: Should never be called with the spinlock held!
 447  */
 448 void nfs_free_request(struct nfs_page *req)
 449 {
 450         WARN_ON_ONCE(req->wb_this_page != req);
 451
 452         /* extra debug: make sure no sync bits are still set */
 453         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 454         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 455         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 456         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 457         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 458
 459         /* Release struct file and open context */
 460         nfs_clear_request(req);
 461         nfs_page_free(req);
 462 }
 463
 464 void nfs_release_request(struct nfs_page *req)
 465 {
 466         kref_put(&req->wb_kref, nfs_page_group_destroy);
 467 }
 468
 469 /**
 470  * nfs_wait_on_request - Wait for a request to complete.
 471  * @req: request to wait upon.
 472  *
 473  * Interruptible by fatal signals only.
 474  * The user is responsible for holding a count on the request.
 475  */
 476 int
 477 nfs_wait_on_request(struct nfs_page *req)
 478 {
 479         if (!test_bit(PG_BUSY, &req->wb_flags))
 480                 return 0;
 481         set_bit(PG_CONTENDED2, &req->wb_flags);
 482         smp_mb__after_atomic();
 483         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 484                               TASK_UNINTERRUPTIBLE);
 485 }
 486
 487 /*
 488  * nfs_generic_pg_test - determine if requests can be coalesced
 489  * @desc: pointer to descriptor
 490  * @prev: previous request in desc, or NULL
 491  * @req: this request
 492  *
 493  * Returns zero if @req can be coalesced into @desc, otherwise it returns
 494  * the size of the request.
 495  */
 496 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 497                            struct nfs_page *prev, struct nfs_page *req)
 498 {
 499         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 500
 501
 502         if (mirror->pg_count > mirror->pg_bsize) {
 503                 /* should never happen */
 504                 WARN_ON_ONCE(1);
 505                 return 0;
 506         }
 507
 508         /*
 509          * Limit the request size so that we can still allocate a page array
 510          * for it without upsetting the slab allocator.
 511          */
 512         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 513                         sizeof(struct page *) > PAGE_SIZE)
 514                 return 0;
 515
 516         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 517 }
 518 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 519
 520 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 521 {
 522         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 523
 524         if (hdr) {
 525                 INIT_LIST_HEAD(&hdr->pages);
 526                 spin_lock_init(&hdr->lock);
 527                 hdr->rw_ops = ops;
 528         }
 529         return hdr;
 530 }
 531 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 532
 533 /*
 534  * nfs_pgio_header_free - Free a read or write header
 535  * @hdr: The header to free
 536  */
 537 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 538 {
 539         hdr->rw_ops->rw_free_header(hdr);
 540 }
 541 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 542
 543 /**
 544  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 545  *
 546  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 547  * be called again.
 548  *
 549  * @hdr: A header that has had nfs_generic_pgio called
 550  */
 551 void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 552 {
 553         if (hdr->args.context)
 554                 put_nfs_open_context(hdr->args.context);
 555         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 556                 kfree(hdr->page_array.pagevec);
 557 }
 558 EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
 559
 560 /**
 561  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 562  * @hdr: The pageio hdr
 563  * @count: Number of bytes to read
 564  * @offset: Initial offset
 565  * @how: How to commit data (writes only)
 566  * @cinfo: Commit information for the call (writes only)
 567  */
 568 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 569                               unsigned int count, unsigned int offset,
 570                               int how, struct nfs_commit_info *cinfo)
 571 {
 572         struct nfs_page *req = hdr->req;
 573
 574         /* Set up the RPC argument and reply structs
 575          * NB: take care not to mess about with hdr->commit et al. */
 576
 577         hdr->args.fh     = NFS_FH(hdr->inode);
 578         hdr->args.offset = req_offset(req) + offset;
 579         /* pnfs_set_layoutcommit needs this */
 580         hdr->mds_offset = hdr->args.offset;
 581         hdr->args.pgbase = req->wb_pgbase + offset;
 582         hdr->args.pages  = hdr->page_array.pagevec;
 583         hdr->args.count  = count;
 584         hdr->args.context = get_nfs_open_context(req->wb_context);
 585         hdr->args.lock_context = req->wb_lock_context;
 586         hdr->args.stable  = NFS_UNSTABLE;
 587         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 588         case 0:
 589                 break;
 590         case FLUSH_COND_STABLE:
 591                 if (nfs_reqs_to_commit(cinfo))
 592                         break;
 593         default:
 594                 hdr->args.stable = NFS_FILE_SYNC;
 595         }
 596
 597         hdr->res.fattr   = &hdr->fattr;
 598         hdr->res.count   = count;
 599         hdr->res.eof     = 0;
 600         hdr->res.verf    = &hdr->verf;
 601         nfs_fattr_init(&hdr->fattr);
 602 }
 603
 604 /**
 605  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 606  * @task: The current task
 607  * @calldata: pageio header to prepare
 608  */
 609 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 610 {
 611         struct nfs_pgio_header *hdr = calldata;
 612         int err;
 613         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 614         if (err)
 615                 rpc_exit(task, err);
 616 }
 617
 618 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 619                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
 620                       const struct rpc_call_ops *call_ops, int how, int flags)
 621 {
 622         struct rpc_task *task;
 623         struct rpc_message msg = {
 624                 .rpc_argp = &hdr->args,
 625                 .rpc_resp = &hdr->res,
 626                 .rpc_cred = cred,
 627         };
 628         struct rpc_task_setup task_setup_data = {
 629                 .rpc_client = clnt,
 630                 .task = &hdr->task,
 631                 .rpc_message = &msg,
 632                 .callback_ops = call_ops,
 633                 .callback_data = hdr,
 634                 .workqueue = nfsiod_workqueue,
 635                 .flags = RPC_TASK_ASYNC | flags,
 636         };
 637         int ret = 0;
 638
 639         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 640
 641         dprintk("NFS: initiated pgio call "
 642                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 643                 hdr->inode->i_sb->s_id,
 644                 (unsigned long long)NFS_FILEID(hdr->inode),
 645                 hdr->args.count,
 646                 (unsigned long long)hdr->args.offset);
 647
 648         task = rpc_run_task(&task_setup_data);
 649         if (IS_ERR(task)) {
 650                 ret = PTR_ERR(task);
 651                 goto out;
 652         }
 653         if (how & FLUSH_SYNC) {
 654                 ret = rpc_wait_for_completion_task(task);
 655                 if (ret == 0)
 656                         ret = task->tk_status;
 657         }
 658         rpc_put_task(task);
 659 out:
 660         return ret;
 661 }
 662 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 663
 664 /**
 665  * nfs_pgio_error - Clean up from a pageio error
 666  * @desc: IO descriptor
 667  * @hdr: pageio header
 668  */
 669 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 670 {
 671         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 672         nfs_pgio_data_destroy(hdr);
 673         hdr->completion_ops->completion(hdr);
 674 }
 675
 676 /**
 677  * nfs_pgio_release - Release pageio data
 678  * @calldata: The pageio header to release
 679  */
 680 static void nfs_pgio_release(void *calldata)
 681 {
 682         struct nfs_pgio_header *hdr = calldata;
 683         nfs_pgio_data_destroy(hdr);
 684         hdr->completion_ops->completion(hdr);
 685 }
 686
 687 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 688                                    unsigned int bsize)
 689 {
 690         INIT_LIST_HEAD(&mirror->pg_list);
 691         mirror->pg_bytes_written = 0;
 692         mirror->pg_count = 0;
 693         mirror->pg_bsize = bsize;
 694         mirror->pg_base = 0;
 695         mirror->pg_recoalesce = 0;
 696 }
 697
 698 /**
 699  * nfs_pageio_init - initialise a page io descriptor
 700  * @desc: pointer to descriptor
 701  * @inode: pointer to inode
 702  * @pg_ops: pointer to pageio operations
 703  * @compl_ops: pointer to pageio completion operations
 704  * @rw_ops: pointer to nfs read/write operations
 705  * @bsize: io block size
 706  * @io_flags: extra parameters for the io function
 707  */
 708 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 709                      struct inode *inode,
 710                      const struct nfs_pageio_ops *pg_ops,
 711                      const struct nfs_pgio_completion_ops *compl_ops,
 712                      const struct nfs_rw_ops *rw_ops,
 713                      size_t bsize,
 714                      int io_flags,
 715                      gfp_t gfp_flags)
 716 {
 717         struct nfs_pgio_mirror *new;
 718         int i;
 719
 720         desc->pg_moreio = 0;
 721         desc->pg_inode = inode;
 722         desc->pg_ops = pg_ops;
 723         desc->pg_completion_ops = compl_ops;
 724         desc->pg_rw_ops = rw_ops;
 725         desc->pg_ioflags = io_flags;
 726         desc->pg_error = 0;
 727         desc->pg_lseg = NULL;
 728         desc->pg_io_completion = NULL;
 729         desc->pg_dreq = NULL;
 730         desc->pg_bsize = bsize;
 731
 732         desc->pg_mirror_count = 1;
 733         desc->pg_mirror_idx = 0;
 734
 735         if (pg_ops->pg_get_mirror_count) {
 736                 /* until we have a request, we don't have an lseg and no
 737                  * idea how many mirrors there will be */
 738                 new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
 739                               sizeof(struct nfs_pgio_mirror), gfp_flags);
 740                 desc->pg_mirrors_dynamic = new;
 741                 desc->pg_mirrors = new;
 742
 743                 for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
 744                         nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
 745         } else {
 746                 desc->pg_mirrors_dynamic = NULL;
 747                 desc->pg_mirrors = desc->pg_mirrors_static;
 748                 nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 749         }
 750 }
 751 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 752
 753 /**
 754  * nfs_pgio_result - Basic pageio error handling
 755  * @task: The task that ran
 756  * @calldata: Pageio header to check
 757  */
 758 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 759 {
 760         struct nfs_pgio_header *hdr = calldata;
 761         struct inode *inode = hdr->inode;
 762
 763         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 764                 task->tk_pid, task->tk_status);
 765
 766         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 767                 return;
 768         if (task->tk_status < 0)
 769                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 770         else
 771                 hdr->rw_ops->rw_result(task, hdr);
 772 }
 773
 774 /*
 775  * Create an RPC task for the given read or write request and kick it.
 776  * The page must have been locked by the caller.
 777  *
 778  * It may happen that the page we're passed is not marked dirty.
 779  * This is the case if nfs_updatepage detects a conflicting request
 780  * that has been written but not committed.
 781  */
 782 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 783                      struct nfs_pgio_header *hdr)
 784 {
 785         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 786
 787         struct nfs_page         *req;
 788         struct page             **pages,
 789                                 *last_page;
 790         struct list_head *head = &mirror->pg_list;
 791         struct nfs_commit_info cinfo;
 792         struct nfs_page_array *pg_array = &hdr->page_array;
 793         unsigned int pagecount, pageused;
 794         gfp_t gfp_flags = GFP_KERNEL;
 795
 796         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 797         pg_array->npages = pagecount;
 798
 799         if (pagecount <= ARRAY_SIZE(pg_array->page_array))
 800                 pg_array->pagevec = pg_array->page_array;
 801         else {
 802                 if (hdr->rw_mode == FMODE_WRITE)
 803                         gfp_flags = GFP_NOIO;
 804                 pg_array->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
 805                 if (!pg_array->pagevec) {
 806                         pg_array->npages = 0;
 807                         nfs_pgio_error(hdr);
 808                         desc->pg_error = -ENOMEM;
 809                         return desc->pg_error;
 810                 }
 811         }
 812
 813         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 814         pages = hdr->page_array.pagevec;
 815         last_page = NULL;
 816         pageused = 0;
 817         while (!list_empty(head)) {
 818                 req = nfs_list_entry(head->next);
 819                 nfs_list_remove_request(req);
 820                 nfs_list_add_request(req, &hdr->pages);
 821
 822                 if (!last_page || last_page != req->wb_page) {
 823                         pageused++;
 824                         if (pageused > pagecount)
 825                                 break;
 826                         *pages++ = last_page = req->wb_page;
 827                 }
 828         }
 829         if (WARN_ON_ONCE(pageused != pagecount)) {
 830                 nfs_pgio_error(hdr);
 831                 desc->pg_error = -EINVAL;
 832                 return desc->pg_error;
 833         }
 834
 835         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 836             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 837                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 838
 839         /* Set up the argument struct */
 840         nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
 841         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 842         return 0;
 843 }
 844 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 845
 846 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 847 {
 848         struct nfs_pgio_header *hdr;
 849         int ret;
 850
 851         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 852         if (!hdr) {
 853                 desc->pg_error = -ENOMEM;
 854                 return desc->pg_error;
 855         }
 856         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 857         ret = nfs_generic_pgio(desc, hdr);
 858         if (ret == 0)
 859                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 860                                         hdr,
 861                                         hdr->cred,
 862                                         NFS_PROTO(hdr->inode),
 863                                         desc->pg_rpc_callops,
 864                                         desc->pg_ioflags, 0);
 865         return ret;
 866 }
 867
 868 /*
 869  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 870  *                              by calling the pg_get_mirror_count op
 871  */
 872 static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 873                                        struct nfs_page *req)
 874 {
 875         int mirror_count = 1;
 876
 877         if (!pgio->pg_ops->pg_get_mirror_count)
 878                 return 0;
 879
 880         mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 881
 882         if (pgio->pg_error < 0)
 883                 return pgio->pg_error;
 884
 885         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
 886                 return -EINVAL;
 887
 888         if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
 889                 return -EINVAL;
 890
 891         pgio->pg_mirror_count = mirror_count;
 892
 893         return 0;
 894 }
 895
 896 /*
 897  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
 898  */
 899 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
 900 {
 901         pgio->pg_mirror_count = 1;
 902         pgio->pg_mirror_idx = 0;
 903 }
 904
 905 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 906 {
 907         pgio->pg_mirror_count = 1;
 908         pgio->pg_mirror_idx = 0;
 909         pgio->pg_mirrors = pgio->pg_mirrors_static;
 910         kfree(pgio->pg_mirrors_dynamic);
 911         pgio->pg_mirrors_dynamic = NULL;
 912 }
 913
 914 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 915                 const struct nfs_lock_context *l2)
 916 {
 917         return l1->lockowner == l2->lockowner;
 918 }
 919
 920 /**
 921  * nfs_can_coalesce_requests - test two requests for compatibility
 922  * @prev: pointer to nfs_page
 923  * @req: pointer to nfs_page
 924  *
 925  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 926  * page data area they describe is contiguous, and that their RPC
 927  * credentials, NFSv4 open state, and lockowners are the same.
 928  *
 929  * Return 'true' if this is the case, else return 'false'.
 930  */
 931 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 932                                       struct nfs_page *req,
 933                                       struct nfs_pageio_descriptor *pgio)
 934 {
 935         size_t size;
 936         struct file_lock_context *flctx;
 937
 938         if (prev) {
 939                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 940                         return false;
 941                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
 942                 if (flctx != NULL &&
 943                     !(list_empty_careful(&flctx->flc_posix) &&
 944                       list_empty_careful(&flctx->flc_flock)) &&
 945                     !nfs_match_lock_context(req->wb_lock_context,
 946                                             prev->wb_lock_context))
 947                         return false;
 948                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 949                         return false;
 950                 if (req->wb_page == prev->wb_page) {
 951                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 952                                 return false;
 953                 } else {
 954                         if (req->wb_pgbase != 0 ||
 955                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 956                                 return false;
 957                 }
 958         }
 959         size = pgio->pg_ops->pg_test(pgio, prev, req);
 960         WARN_ON_ONCE(size > req->wb_bytes);
 961         if (size && size < req->wb_bytes)
 962                 req->wb_bytes = size;
 963         return size > 0;
 964 }
 965
 966 /**
 967  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 968  * @desc: destination io descriptor
 969  * @req: request
 970  *
 971  * Returns true if the request 'req' was successfully coalesced into the
 972  * existing list of pages 'desc'.
 973  */
 974 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 975                                      struct nfs_page *req)
 976 {
 977         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 978
 979         struct nfs_page *prev = NULL;
 980
 981         if (mirror->pg_count != 0) {
 982                 prev = nfs_list_entry(mirror->pg_list.prev);
 983         } else {
 984                 if (desc->pg_ops->pg_init)
 985                         desc->pg_ops->pg_init(desc, req);
 986                 if (desc->pg_error < 0)
 987                         return 0;
 988                 mirror->pg_base = req->wb_pgbase;
 989         }
 990         if (!nfs_can_coalesce_requests(prev, req, desc))
 991                 return 0;
 992         nfs_list_remove_request(req);
 993         nfs_list_add_request(req, &mirror->pg_list);
 994         mirror->pg_count += req->wb_bytes;
 995         return 1;
 996 }
 997
 998 /*
 999  * Helper for nfs_pageio_add_request and nfs_pageio_complete
1000  */
1001 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
1002 {
1003         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1004
1005
1006         if (!list_empty(&mirror->pg_list)) {
1007                 int error = desc->pg_ops->pg_doio(desc);
1008                 if (error < 0)
1009                         desc->pg_error = error;
1010                 else
1011                         mirror->pg_bytes_written += mirror->pg_count;
1012         }
1013         if (list_empty(&mirror->pg_list)) {
1014                 mirror->pg_count = 0;
1015                 mirror->pg_base = 0;
1016         }
1017 }
1018
1019 /**
1020  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
1021  * @desc: destination io descriptor
1022  * @req: request
1023  *
1024  * This may split a request into subrequests which are all part of the
1025  * same page group.
1026  *
1027  * Returns true if the request 'req' was successfully coalesced into the
1028  * existing list of pages 'desc'.
1029  */
1030 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1031                            struct nfs_page *req)
1032 {
1033         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1034
1035         struct nfs_page *subreq;
1036         unsigned int bytes_left = 0;
1037         unsigned int offset, pgbase;
1038
1039         nfs_page_group_lock(req, false);
1040
1041         subreq = req;
1042         bytes_left = subreq->wb_bytes;
1043         offset = subreq->wb_offset;
1044         pgbase = subreq->wb_pgbase;
1045
1046         do {
1047                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1048                         /* make sure pg_test call(s) did nothing */
1049                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1050                         WARN_ON_ONCE(subreq->wb_offset != offset);
1051                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1052
1053                         nfs_page_group_unlock(req);
1054                         desc->pg_moreio = 1;
1055                         nfs_pageio_doio(desc);
1056                         if (desc->pg_error < 0)
1057                                 return 0;
1058                         if (mirror->pg_recoalesce)
1059                                 return 0;
1060                         /* retry add_request for this subreq */
1061                         nfs_page_group_lock(req, false);
1062                         continue;
1063                 }
1064
1065                 /* check for buggy pg_test call(s) */
1066                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1067                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1068                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1069
1070                 bytes_left -= subreq->wb_bytes;
1071                 offset += subreq->wb_bytes;
1072                 pgbase += subreq->wb_bytes;
1073
1074                 if (bytes_left) {
1075                         subreq = nfs_create_request(req->wb_context,
1076                                         req->wb_page,
1077                                         subreq, pgbase, bytes_left);
1078                         if (IS_ERR(subreq))
1079                                 goto err_ptr;
1080                         nfs_lock_request(subreq);
1081                         subreq->wb_offset  = offset;
1082                         subreq->wb_index = req->wb_index;
1083                 }
1084         } while (bytes_left > 0);
1085
1086         nfs_page_group_unlock(req);
1087         return 1;
1088 err_ptr:
1089         desc->pg_error = PTR_ERR(subreq);
1090         nfs_page_group_unlock(req);
1091         return 0;
1092 }
1093
1094 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1095 {
1096         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1097         LIST_HEAD(head);
1098
1099         do {
1100                 list_splice_init(&mirror->pg_list, &head);
1101                 mirror->pg_bytes_written -= mirror->pg_count;
1102                 mirror->pg_count = 0;
1103                 mirror->pg_base = 0;
1104                 mirror->pg_recoalesce = 0;
1105
1106                 while (!list_empty(&head)) {
1107                         struct nfs_page *req;
1108
1109                         req = list_first_entry(&head, struct nfs_page, wb_list);
1110                         nfs_list_remove_request(req);
1111                         if (__nfs_pageio_add_request(desc, req))
1112                                 continue;
1113                         if (desc->pg_error < 0) {
1114                                 list_splice_tail(&head, &mirror->pg_list);
1115                                 mirror->pg_recoalesce = 1;
1116                                 return 0;
1117                         }
1118                         break;
1119                 }
1120         } while (mirror->pg_recoalesce);
1121         return 1;
1122 }
1123
1124 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1125                 struct nfs_page *req)
1126 {
1127         int ret;
1128
1129         do {
1130                 ret = __nfs_pageio_add_request(desc, req);
1131                 if (ret)
1132                         break;
1133                 if (desc->pg_error < 0)
1134                         break;
1135                 ret = nfs_do_recoalesce(desc);
1136         } while (ret);
1137
1138         return ret;
1139 }
1140
1141 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1142                            struct nfs_page *req)
1143 {
1144         u32 midx;
1145         unsigned int pgbase, offset, bytes;
1146         struct nfs_page *dupreq, *lastreq;
1147
1148         pgbase = req->wb_pgbase;
1149         offset = req->wb_offset;
1150         bytes = req->wb_bytes;
1151
1152         nfs_pageio_setup_mirroring(desc, req);
1153         if (desc->pg_error < 0)
1154                 goto out_failed;
1155
1156         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1157                 if (midx) {
1158                         nfs_page_group_lock(req, false);
1159
1160                         /* find the last request */
1161                         for (lastreq = req->wb_head;
1162                              lastreq->wb_this_page != req->wb_head;
1163                              lastreq = lastreq->wb_this_page)
1164                                 ;
1165
1166                         dupreq = nfs_create_request(req->wb_context,
1167                                         req->wb_page, lastreq, pgbase, bytes);
1168
1169                         if (IS_ERR(dupreq)) {
1170                                 nfs_page_group_unlock(req);
1171                                 desc->pg_error = PTR_ERR(dupreq);
1172                                 goto out_failed;
1173                         }
1174
1175                         nfs_lock_request(dupreq);
1176                         nfs_page_group_unlock(req);
1177                         dupreq->wb_offset = offset;
1178                         dupreq->wb_index = req->wb_index;
1179                 } else
1180                         dupreq = req;
1181
1182                 if (nfs_pgio_has_mirroring(desc))
1183                         desc->pg_mirror_idx = midx;
1184                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1185                         goto out_failed;
1186         }
1187
1188         return 1;
1189
1190 out_failed:
1191         /*
1192          * We might have failed before sending any reqs over wire.
1193          * Clean up rest of the reqs in mirror pg_list.
1194          */
1195         if (desc->pg_error) {
1196                 struct nfs_pgio_mirror *mirror;
1197                 void (*func)(struct list_head *);
1198
1199                 /* remember fatal errors */
1200                 if (nfs_error_is_fatal(desc->pg_error))
1201                         mapping_set_error(desc->pg_inode->i_mapping,
1202                                           desc->pg_error);
1203
1204                 func = desc->pg_completion_ops->error_cleanup;
1205                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1206                         mirror = &desc->pg_mirrors[midx];
1207                         func(&mirror->pg_list);
1208                 }
1209         }
1210         return 0;
1211 }
1212
1213 /*
1214  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1215  *                              nfs_pageio_descriptor
1216  * @desc: pointer to io descriptor
1217  * @mirror_idx: pointer to mirror index
1218  */
1219 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1220                                        u32 mirror_idx)
1221 {
1222         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1223         u32 restore_idx = desc->pg_mirror_idx;
1224
1225         if (nfs_pgio_has_mirroring(desc))
1226                 desc->pg_mirror_idx = mirror_idx;
1227         for (;;) {
1228                 nfs_pageio_doio(desc);
1229                 if (!mirror->pg_recoalesce)
1230                         break;
1231                 if (!nfs_do_recoalesce(desc))
1232                         break;
1233         }
1234         desc->pg_mirror_idx = restore_idx;
1235 }
1236
1237 /*
1238  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1239  * @hdr - the pgio header to move request from
1240  * @desc - the pageio descriptor to add requests to
1241  *
1242  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1243  * to send them.
1244  *
1245  * Returns 0 on success and < 0 on error.
1246  */
1247 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1248                       struct nfs_pgio_header *hdr)
1249 {
1250         LIST_HEAD(failed);
1251
1252         desc->pg_io_completion = hdr->io_completion;
1253         desc->pg_dreq = hdr->dreq;
1254         while (!list_empty(&hdr->pages)) {
1255                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1256
1257                 nfs_list_remove_request(req);
1258                 if (!nfs_pageio_add_request(desc, req))
1259                         nfs_list_add_request(req, &failed);
1260         }
1261         nfs_pageio_complete(desc);
1262         if (!list_empty(&failed)) {
1263                 list_move(&failed, &hdr->pages);
1264                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1265         }
1266         return 0;
1267 }
1268 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1269
1270 /**
1271  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1272  * @desc: pointer to io descriptor
1273  */
1274 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1275 {
1276         u32 midx;
1277
1278         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1279                 nfs_pageio_complete_mirror(desc, midx);
1280
1281         if (desc->pg_ops->pg_cleanup)
1282                 desc->pg_ops->pg_cleanup(desc);
1283         nfs_pageio_cleanup_mirroring(desc);
1284 }
1285
1286 /**
1287  * nfs_pageio_cond_complete - Conditional I/O completion
1288  * @desc: pointer to io descriptor
1289  * @index: page index
1290  *
1291  * It is important to ensure that processes don't try to take locks
1292  * on non-contiguous ranges of pages as that might deadlock. This
1293  * function should be called before attempting to wait on a locked
1294  * nfs_page. It will complete the I/O if the page index 'index'
1295  * is not contiguous with the existing list of pages in 'desc'.
1296  */
1297 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1298 {
1299         struct nfs_pgio_mirror *mirror;
1300         struct nfs_page *prev;
1301         u32 midx;
1302
1303         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1304                 mirror = &desc->pg_mirrors[midx];
1305                 if (!list_empty(&mirror->pg_list)) {
1306                         prev = nfs_list_entry(mirror->pg_list.prev);
1307                         if (index != prev->wb_index + 1) {
1308                                 nfs_pageio_complete(desc);
1309                                 break;
1310                         }
1311                 }
1312         }
1313 }
1314
1315 int __init nfs_init_nfspagecache(void)
1316 {
1317         nfs_page_cachep = kmem_cache_create("nfs_page",
1318                                             sizeof(struct nfs_page),
1319                                             0, SLAB_HWCACHE_ALIGN,
1320                                             NULL);
1321         if (nfs_page_cachep == NULL)
1322                 return -ENOMEM;
1323
1324         return 0;
1325 }
1326
1327 void nfs_destroy_nfspagecache(void)
1328 {
1329         kmem_cache_destroy(nfs_page_cachep);
1330 }
1331
1332 static const struct rpc_call_ops nfs_pgio_common_ops = {
1333         .rpc_call_prepare = nfs_pgio_prepare,
1334         .rpc_call_done = nfs_pgio_result,
1335         .rpc_release = nfs_pgio_release,
1336 };
1337
1338 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1339         .pg_test = nfs_generic_pg_test,
1340         .pg_doio = nfs_generic_pg_pgios,
1341 };