fs/nfs/pagelist.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/pagelist.c
   4  *
   5  * A set of helper functions for managing NFS read and write requests.
   6  * The main purpose of these routines is to provide support for the
   7  * coalescing of several requests into a single RPC call.
   8  *
   9  * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
  10  *
  11  */
  12
  13 #include <linux/slab.h>
  14 #include <linux/file.h>
  15 #include <linux/sched.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/nfs.h>
  18 #include <linux/nfs3.h>
  19 #include <linux/nfs4.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_page.h>
  22 #include <linux/nfs_mount.h>
  23 #include <linux/export.h>
  24
  25 #include "internal.h"
  26 #include "pnfs.h"
  27
  28 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  29
  30 static struct kmem_cache *nfs_page_cachep;
  31 static const struct rpc_call_ops nfs_pgio_common_ops;
  32
  33 struct nfs_pgio_mirror *
  34 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
  35 {
  36         return nfs_pgio_has_mirroring(desc) ?
  37                 &desc->pg_mirrors[desc->pg_mirror_idx] :
  38                 &desc->pg_mirrors[0];
  39 }
  40 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
  41
  42 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  43                        struct nfs_pgio_header *hdr,
  44                        void (*release)(struct nfs_pgio_header *hdr))
  45 {
  46         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
  47
  48
  49         hdr->req = nfs_list_entry(mirror->pg_list.next);
  50         hdr->inode = desc->pg_inode;
  51         hdr->cred = nfs_req_openctx(hdr->req)->cred;
  52         hdr->io_start = req_offset(hdr->req);
  53         hdr->good_bytes = mirror->pg_count;
  54         hdr->io_completion = desc->pg_io_completion;
  55         hdr->dreq = desc->pg_dreq;
  56         hdr->release = release;
  57         hdr->completion_ops = desc->pg_completion_ops;
  58         if (hdr->completion_ops->init_hdr)
  59                 hdr->completion_ops->init_hdr(hdr);
  60
  61         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
  62 }
  63 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
  64
  65 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
  66 {
  67         unsigned int new = pos - hdr->io_start;
  68
  69         if (hdr->good_bytes > new) {
  70                 hdr->good_bytes = new;
  71                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
  72                 if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags))
  73                         hdr->error = error;
  74         }
  75 }
  76
  77 static inline struct nfs_page *
  78 nfs_page_alloc(void)
  79 {
  80         struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_KERNEL);
  81         if (p)
  82                 INIT_LIST_HEAD(&p->wb_list);
  83         return p;
  84 }
  85
  86 static inline void
  87 nfs_page_free(struct nfs_page *p)
  88 {
  89         kmem_cache_free(nfs_page_cachep, p);
  90 }
  91
  92 /**
  93  * nfs_iocounter_wait - wait for i/o to complete
  94  * @l_ctx: nfs_lock_context with io_counter to use
  95  *
  96  * returns -ERESTARTSYS if interrupted by a fatal signal.
  97  * Otherwise returns 0 once the io_count hits 0.
  98  */
  99 int
 100 nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
 101 {
 102         return wait_var_event_killable(&l_ctx->io_count,
 103                                        !atomic_read(&l_ctx->io_count));
 104 }
 105
 106 /**
 107  * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
 108  * to complete
 109  * @task: the rpc_task that should wait
 110  * @l_ctx: nfs_lock_context with io_counter to check
 111  *
 112  * Returns true if there is outstanding I/O to wait on and the
 113  * task has been put to sleep.
 114  */
 115 bool
 116 nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
 117 {
 118         struct inode *inode = d_inode(l_ctx->open_context->dentry);
 119         bool ret = false;
 120
 121         if (atomic_read(&l_ctx->io_count) > 0) {
 122                 rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
 123                 ret = true;
 124         }
 125
 126         if (atomic_read(&l_ctx->io_count) == 0) {
 127                 rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
 128                 ret = false;
 129         }
 130
 131         return ret;
 132 }
 133 EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
 134
 135 /*
 136  * nfs_page_set_headlock - set the request PG_HEADLOCK
 137  * @req: request that is to be locked
 138  *
 139  * this lock must be held when modifying req->wb_head
 140  *
 141  * return 0 on success, < 0 on error
 142  */
 143 int
 144 nfs_page_set_headlock(struct nfs_page *req)
 145 {
 146         if (!test_and_set_bit(PG_HEADLOCK, &req->wb_flags))
 147                 return 0;
 148
 149         set_bit(PG_CONTENDED1, &req->wb_flags);
 150         smp_mb__after_atomic();
 151         return wait_on_bit_lock(&req->wb_flags, PG_HEADLOCK,
 152                                 TASK_UNINTERRUPTIBLE);
 153 }
 154
 155 /*
 156  * nfs_page_clear_headlock - clear the request PG_HEADLOCK
 157  * @req: request that is to be locked
 158  */
 159 void
 160 nfs_page_clear_headlock(struct nfs_page *req)
 161 {
 162         smp_mb__before_atomic();
 163         clear_bit(PG_HEADLOCK, &req->wb_flags);
 164         smp_mb__after_atomic();
 165         if (!test_bit(PG_CONTENDED1, &req->wb_flags))
 166                 return;
 167         wake_up_bit(&req->wb_flags, PG_HEADLOCK);
 168 }
 169
 170 /*
 171  * nfs_page_group_lock - lock the head of the page group
 172  * @req: request in group that is to be locked
 173  *
 174  * this lock must be held when traversing or modifying the page
 175  * group list
 176  *
 177  * return 0 on success, < 0 on error
 178  */
 179 int
 180 nfs_page_group_lock(struct nfs_page *req)
 181 {
 182         int ret;
 183
 184         ret = nfs_page_set_headlock(req);
 185         if (ret || req->wb_head == req)
 186                 return ret;
 187         return nfs_page_set_headlock(req->wb_head);
 188 }
 189
 190 /*
 191  * nfs_page_group_unlock - unlock the head of the page group
 192  * @req: request in group that is to be unlocked
 193  */
 194 void
 195 nfs_page_group_unlock(struct nfs_page *req)
 196 {
 197         if (req != req->wb_head)
 198                 nfs_page_clear_headlock(req->wb_head);
 199         nfs_page_clear_headlock(req);
 200 }
 201
 202 /*
 203  * nfs_page_group_sync_on_bit_locked
 204  *
 205  * must be called with page group lock held
 206  */
 207 static bool
 208 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 209 {
 210         struct nfs_page *head = req->wb_head;
 211         struct nfs_page *tmp;
 212
 213         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 214         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 215
 216         tmp = req->wb_this_page;
 217         while (tmp != req) {
 218                 if (!test_bit(bit, &tmp->wb_flags))
 219                         return false;
 220                 tmp = tmp->wb_this_page;
 221         }
 222
 223         /* true! reset all bits */
 224         tmp = req;
 225         do {
 226                 clear_bit(bit, &tmp->wb_flags);
 227                 tmp = tmp->wb_this_page;
 228         } while (tmp != req);
 229
 230         return true;
 231 }
 232
 233 /*
 234  * nfs_page_group_sync_on_bit - set bit on current request, but only
 235  *   return true if the bit is set for all requests in page group
 236  * @req - request in page group
 237  * @bit - PG_* bit that is used to sync page group
 238  */
 239 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 240 {
 241         bool ret;
 242
 243         nfs_page_group_lock(req);
 244         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 245         nfs_page_group_unlock(req);
 246
 247         return ret;
 248 }
 249
 250 /*
 251  * nfs_page_group_init - Initialize the page group linkage for @req
 252  * @req - a new nfs request
 253  * @prev - the previous request in page group, or NULL if @req is the first
 254  *         or only request in the group (the head).
 255  */
 256 static inline void
 257 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 258 {
 259         struct inode *inode;
 260         WARN_ON_ONCE(prev == req);
 261
 262         if (!prev) {
 263                 /* a head request */
 264                 req->wb_head = req;
 265                 req->wb_this_page = req;
 266         } else {
 267                 /* a subrequest */
 268                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 269                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 270                 req->wb_head = prev->wb_head;
 271                 req->wb_this_page = prev->wb_this_page;
 272                 prev->wb_this_page = req;
 273
 274                 /* All subrequests take a ref on the head request until
 275                  * nfs_page_group_destroy is called */
 276                 kref_get(&req->wb_head->wb_kref);
 277
 278                 /* grab extra ref and bump the request count if head request
 279                  * has extra ref from the write/commit path to handle handoff
 280                  * between write and commit lists. */
 281                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 282                         inode = page_file_mapping(req->wb_page)->host;
 283                         set_bit(PG_INODE_REF, &req->wb_flags);
 284                         kref_get(&req->wb_kref);
 285                         atomic_long_inc(&NFS_I(inode)->nrequests);
 286                 }
 287         }
 288 }
 289
 290 /*
 291  * nfs_page_group_destroy - sync the destruction of page groups
 292  * @req - request that no longer needs the page group
 293  *
 294  * releases the page group reference from each member once all
 295  * members have called this function.
 296  */
 297 static void
 298 nfs_page_group_destroy(struct kref *kref)
 299 {
 300         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 301         struct nfs_page *head = req->wb_head;
 302         struct nfs_page *tmp, *next;
 303
 304         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 305                 goto out;
 306
 307         tmp = req;
 308         do {
 309                 next = tmp->wb_this_page;
 310                 /* unlink and free */
 311                 tmp->wb_this_page = tmp;
 312                 tmp->wb_head = tmp;
 313                 nfs_free_request(tmp);
 314                 tmp = next;
 315         } while (tmp != req);
 316 out:
 317         /* subrequests must release the ref on the head request */
 318         if (head != req)
 319                 nfs_release_request(head);
 320 }
 321
 322 static struct nfs_page *
 323 __nfs_create_request(struct nfs_lock_context *l_ctx, struct page *page,
 324                    unsigned int pgbase, unsigned int offset,
 325                    unsigned int count)
 326 {
 327         struct nfs_page         *req;
 328         struct nfs_open_context *ctx = l_ctx->open_context;
 329
 330         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 331                 return ERR_PTR(-EBADF);
 332         /* try to allocate the request struct */
 333         req = nfs_page_alloc();
 334         if (req == NULL)
 335                 return ERR_PTR(-ENOMEM);
 336
 337         req->wb_lock_context = l_ctx;
 338         refcount_inc(&l_ctx->count);
 339         atomic_inc(&l_ctx->io_count);
 340
 341         /* Initialize the request struct. Initially, we assume a
 342          * long write-back delay. This will be adjusted in
 343          * update_nfs_request below if the region is not locked. */
 344         req->wb_page    = page;
 345         if (page) {
 346                 req->wb_index = page_index(page);
 347                 get_page(page);
 348         }
 349         req->wb_offset  = offset;
 350         req->wb_pgbase  = pgbase;
 351         req->wb_bytes   = count;
 352         kref_init(&req->wb_kref);
 353         req->wb_nio = 0;
 354         return req;
 355 }
 356
 357 /**
 358  * nfs_create_request - Create an NFS read/write request.
 359  * @ctx: open context to use
 360  * @page: page to write
 361  * @offset: starting offset within the page for the write
 362  * @count: number of bytes to read/write
 363  *
 364  * The page must be locked by the caller. This makes sure we never
 365  * create two different requests for the same page.
 366  * User should ensure it is safe to sleep in this function.
 367  */
 368 struct nfs_page *
 369 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 370                    unsigned int offset, unsigned int count)
 371 {
 372         struct nfs_lock_context *l_ctx = nfs_get_lock_context(ctx);
 373         struct nfs_page *ret;
 374
 375         if (IS_ERR(l_ctx))
 376                 return ERR_CAST(l_ctx);
 377         ret = __nfs_create_request(l_ctx, page, offset, offset, count);
 378         if (!IS_ERR(ret))
 379                 nfs_page_group_init(ret, NULL);
 380         nfs_put_lock_context(l_ctx);
 381         return ret;
 382 }
 383
 384 static struct nfs_page *
 385 nfs_create_subreq(struct nfs_page *req, struct nfs_page *last,
 386                   unsigned int pgbase, unsigned int offset,
 387                   unsigned int count)
 388 {
 389         struct nfs_page *ret;
 390
 391         ret = __nfs_create_request(req->wb_lock_context, req->wb_page,
 392                         pgbase, offset, count);
 393         if (!IS_ERR(ret)) {
 394                 nfs_lock_request(ret);
 395                 ret->wb_index = req->wb_index;
 396                 nfs_page_group_init(ret, last);
 397                 ret->wb_nio = req->wb_nio;
 398         }
 399         return ret;
 400 }
 401
 402 /**
 403  * nfs_unlock_request - Unlock request and wake up sleepers.
 404  * @req: pointer to request
 405  */
 406 void nfs_unlock_request(struct nfs_page *req)
 407 {
 408         if (!NFS_WBACK_BUSY(req)) {
 409                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 410                 BUG();
 411         }
 412         smp_mb__before_atomic();
 413         clear_bit(PG_BUSY, &req->wb_flags);
 414         smp_mb__after_atomic();
 415         if (!test_bit(PG_CONTENDED2, &req->wb_flags))
 416                 return;
 417         wake_up_bit(&req->wb_flags, PG_BUSY);
 418 }
 419
 420 /**
 421  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 422  * @req: pointer to request
 423  */
 424 void nfs_unlock_and_release_request(struct nfs_page *req)
 425 {
 426         nfs_unlock_request(req);
 427         nfs_release_request(req);
 428 }
 429
 430 /*
 431  * nfs_clear_request - Free up all resources allocated to the request
 432  * @req:
 433  *
 434  * Release page and open context resources associated with a read/write
 435  * request after it has completed.
 436  */
 437 static void nfs_clear_request(struct nfs_page *req)
 438 {
 439         struct page *page = req->wb_page;
 440         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 441         struct nfs_open_context *ctx;
 442
 443         if (page != NULL) {
 444                 put_page(page);
 445                 req->wb_page = NULL;
 446         }
 447         if (l_ctx != NULL) {
 448                 if (atomic_dec_and_test(&l_ctx->io_count)) {
 449                         wake_up_var(&l_ctx->io_count);
 450                         ctx = l_ctx->open_context;
 451                         if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
 452                                 rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
 453                 }
 454                 nfs_put_lock_context(l_ctx);
 455                 req->wb_lock_context = NULL;
 456         }
 457 }
 458
 459 /**
 460  * nfs_release_request - Release the count on an NFS read/write request
 461  * @req: request to release
 462  *
 463  * Note: Should never be called with the spinlock held!
 464  */
 465 void nfs_free_request(struct nfs_page *req)
 466 {
 467         WARN_ON_ONCE(req->wb_this_page != req);
 468
 469         /* extra debug: make sure no sync bits are still set */
 470         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 471         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 472         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 473         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 474         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 475
 476         /* Release struct file and open context */
 477         nfs_clear_request(req);
 478         nfs_page_free(req);
 479 }
 480
 481 void nfs_release_request(struct nfs_page *req)
 482 {
 483         kref_put(&req->wb_kref, nfs_page_group_destroy);
 484 }
 485 EXPORT_SYMBOL_GPL(nfs_release_request);
 486
 487 /**
 488  * nfs_wait_on_request - Wait for a request to complete.
 489  * @req: request to wait upon.
 490  *
 491  * Interruptible by fatal signals only.
 492  * The user is responsible for holding a count on the request.
 493  */
 494 int
 495 nfs_wait_on_request(struct nfs_page *req)
 496 {
 497         if (!test_bit(PG_BUSY, &req->wb_flags))
 498                 return 0;
 499         set_bit(PG_CONTENDED2, &req->wb_flags);
 500         smp_mb__after_atomic();
 501         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 502                               TASK_UNINTERRUPTIBLE);
 503 }
 504 EXPORT_SYMBOL_GPL(nfs_wait_on_request);
 505
 506 /*
 507  * nfs_generic_pg_test - determine if requests can be coalesced
 508  * @desc: pointer to descriptor
 509  * @prev: previous request in desc, or NULL
 510  * @req: this request
 511  *
 512  * Returns zero if @req cannot be coalesced into @desc, otherwise it returns
 513  * the size of the request.
 514  */
 515 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 516                            struct nfs_page *prev, struct nfs_page *req)
 517 {
 518         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 519
 520
 521         if (mirror->pg_count > mirror->pg_bsize) {
 522                 /* should never happen */
 523                 WARN_ON_ONCE(1);
 524                 return 0;
 525         }
 526
 527         /*
 528          * Limit the request size so that we can still allocate a page array
 529          * for it without upsetting the slab allocator.
 530          */
 531         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 532                         sizeof(struct page *) > PAGE_SIZE)
 533                 return 0;
 534
 535         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 536 }
 537 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 538
 539 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 540 {
 541         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 542
 543         if (hdr) {
 544                 INIT_LIST_HEAD(&hdr->pages);
 545                 hdr->rw_ops = ops;
 546         }
 547         return hdr;
 548 }
 549 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 550
 551 /**
 552  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 553  *
 554  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 555  * be called again.
 556  *
 557  * @hdr: A header that has had nfs_generic_pgio called
 558  */
 559 static void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 560 {
 561         if (hdr->args.context)
 562                 put_nfs_open_context(hdr->args.context);
 563         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 564                 kfree(hdr->page_array.pagevec);
 565 }
 566
 567 /*
 568  * nfs_pgio_header_free - Free a read or write header
 569  * @hdr: The header to free
 570  */
 571 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 572 {
 573         nfs_pgio_data_destroy(hdr);
 574         hdr->rw_ops->rw_free_header(hdr);
 575 }
 576 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 577
 578 /**
 579  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 580  * @hdr: The pageio hdr
 581  * @count: Number of bytes to read
 582  * @how: How to commit data (writes only)
 583  * @cinfo: Commit information for the call (writes only)
 584  */
 585 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 586                               unsigned int count,
 587                               int how, struct nfs_commit_info *cinfo)
 588 {
 589         struct nfs_page *req = hdr->req;
 590
 591         /* Set up the RPC argument and reply structs
 592          * NB: take care not to mess about with hdr->commit et al. */
 593
 594         hdr->args.fh     = NFS_FH(hdr->inode);
 595         hdr->args.offset = req_offset(req);
 596         /* pnfs_set_layoutcommit needs this */
 597         hdr->mds_offset = hdr->args.offset;
 598         hdr->args.pgbase = req->wb_pgbase;
 599         hdr->args.pages  = hdr->page_array.pagevec;
 600         hdr->args.count  = count;
 601         hdr->args.context = get_nfs_open_context(nfs_req_openctx(req));
 602         hdr->args.lock_context = req->wb_lock_context;
 603         hdr->args.stable  = NFS_UNSTABLE;
 604         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 605         case 0:
 606                 break;
 607         case FLUSH_COND_STABLE:
 608                 if (nfs_reqs_to_commit(cinfo))
 609                         break;
 610                 /* fall through */
 611         default:
 612                 hdr->args.stable = NFS_FILE_SYNC;
 613         }
 614
 615         hdr->res.fattr   = &hdr->fattr;
 616         hdr->res.count   = 0;
 617         hdr->res.eof     = 0;
 618         hdr->res.verf    = &hdr->verf;
 619         nfs_fattr_init(&hdr->fattr);
 620 }
 621
 622 /**
 623  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 624  * @task: The current task
 625  * @calldata: pageio header to prepare
 626  */
 627 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 628 {
 629         struct nfs_pgio_header *hdr = calldata;
 630         int err;
 631         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 632         if (err)
 633                 rpc_exit(task, err);
 634 }
 635
 636 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 637                       const struct cred *cred, const struct nfs_rpc_ops *rpc_ops,
 638                       const struct rpc_call_ops *call_ops, int how, int flags)
 639 {
 640         struct rpc_task *task;
 641         struct rpc_message msg = {
 642                 .rpc_argp = &hdr->args,
 643                 .rpc_resp = &hdr->res,
 644                 .rpc_cred = cred,
 645         };
 646         struct rpc_task_setup task_setup_data = {
 647                 .rpc_client = clnt,
 648                 .task = &hdr->task,
 649                 .rpc_message = &msg,
 650                 .callback_ops = call_ops,
 651                 .callback_data = hdr,
 652                 .workqueue = nfsiod_workqueue,
 653                 .flags = RPC_TASK_ASYNC | flags,
 654         };
 655         int ret = 0;
 656
 657         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 658
 659         dprintk("NFS: initiated pgio call "
 660                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 661                 hdr->inode->i_sb->s_id,
 662                 (unsigned long long)NFS_FILEID(hdr->inode),
 663                 hdr->args.count,
 664                 (unsigned long long)hdr->args.offset);
 665
 666         task = rpc_run_task(&task_setup_data);
 667         if (IS_ERR(task)) {
 668                 ret = PTR_ERR(task);
 669                 goto out;
 670         }
 671         if (how & FLUSH_SYNC) {
 672                 ret = rpc_wait_for_completion_task(task);
 673                 if (ret == 0)
 674                         ret = task->tk_status;
 675         }
 676         rpc_put_task(task);
 677 out:
 678         return ret;
 679 }
 680 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 681
 682 /**
 683  * nfs_pgio_error - Clean up from a pageio error
 684  * @hdr: pageio header
 685  */
 686 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 687 {
 688         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 689         hdr->completion_ops->completion(hdr);
 690 }
 691
 692 /**
 693  * nfs_pgio_release - Release pageio data
 694  * @calldata: The pageio header to release
 695  */
 696 static void nfs_pgio_release(void *calldata)
 697 {
 698         struct nfs_pgio_header *hdr = calldata;
 699         hdr->completion_ops->completion(hdr);
 700 }
 701
 702 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 703                                    unsigned int bsize)
 704 {
 705         INIT_LIST_HEAD(&mirror->pg_list);
 706         mirror->pg_bytes_written = 0;
 707         mirror->pg_count = 0;
 708         mirror->pg_bsize = bsize;
 709         mirror->pg_base = 0;
 710         mirror->pg_recoalesce = 0;
 711 }
 712
 713 /**
 714  * nfs_pageio_init - initialise a page io descriptor
 715  * @desc: pointer to descriptor
 716  * @inode: pointer to inode
 717  * @pg_ops: pointer to pageio operations
 718  * @compl_ops: pointer to pageio completion operations
 719  * @rw_ops: pointer to nfs read/write operations
 720  * @bsize: io block size
 721  * @io_flags: extra parameters for the io function
 722  */
 723 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 724                      struct inode *inode,
 725                      const struct nfs_pageio_ops *pg_ops,
 726                      const struct nfs_pgio_completion_ops *compl_ops,
 727                      const struct nfs_rw_ops *rw_ops,
 728                      size_t bsize,
 729                      int io_flags)
 730 {
 731         desc->pg_moreio = 0;
 732         desc->pg_inode = inode;
 733         desc->pg_ops = pg_ops;
 734         desc->pg_completion_ops = compl_ops;
 735         desc->pg_rw_ops = rw_ops;
 736         desc->pg_ioflags = io_flags;
 737         desc->pg_error = 0;
 738         desc->pg_lseg = NULL;
 739         desc->pg_io_completion = NULL;
 740         desc->pg_dreq = NULL;
 741         desc->pg_bsize = bsize;
 742
 743         desc->pg_mirror_count = 1;
 744         desc->pg_mirror_idx = 0;
 745
 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         desc->pg_maxretrans = 0;
 750 }
 751
 752 /**
 753  * nfs_pgio_result - Basic pageio error handling
 754  * @task: The task that ran
 755  * @calldata: Pageio header to check
 756  */
 757 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 758 {
 759         struct nfs_pgio_header *hdr = calldata;
 760         struct inode *inode = hdr->inode;
 761
 762         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 763                 task->tk_pid, task->tk_status);
 764
 765         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 766                 return;
 767         if (task->tk_status < 0)
 768                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 769         else
 770                 hdr->rw_ops->rw_result(task, hdr);
 771 }
 772
 773 /*
 774  * Create an RPC task for the given read or write request and kick it.
 775  * The page must have been locked by the caller.
 776  *
 777  * It may happen that the page we're passed is not marked dirty.
 778  * This is the case if nfs_updatepage detects a conflicting request
 779  * that has been written but not committed.
 780  */
 781 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 782                      struct nfs_pgio_header *hdr)
 783 {
 784         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 785
 786         struct nfs_page         *req;
 787         struct page             **pages,
 788                                 *last_page;
 789         struct list_head *head = &mirror->pg_list;
 790         struct nfs_commit_info cinfo;
 791         struct nfs_page_array *pg_array = &hdr->page_array;
 792         unsigned int pagecount, pageused;
 793         gfp_t gfp_flags = GFP_KERNEL;
 794
 795         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 796         pg_array->npages = pagecount;
 797
 798         if (pagecount <= ARRAY_SIZE(pg_array->page_array))
 799                 pg_array->pagevec = pg_array->page_array;
 800         else {
 801                 pg_array->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
 802                 if (!pg_array->pagevec) {
 803                         pg_array->npages = 0;
 804                         nfs_pgio_error(hdr);
 805                         desc->pg_error = -ENOMEM;
 806                         return desc->pg_error;
 807                 }
 808         }
 809
 810         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 811         pages = hdr->page_array.pagevec;
 812         last_page = NULL;
 813         pageused = 0;
 814         while (!list_empty(head)) {
 815                 req = nfs_list_entry(head->next);
 816                 nfs_list_move_request(req, &hdr->pages);
 817
 818                 if (!last_page || last_page != req->wb_page) {
 819                         pageused++;
 820                         if (pageused > pagecount)
 821                                 break;
 822                         *pages++ = last_page = req->wb_page;
 823                 }
 824         }
 825         if (WARN_ON_ONCE(pageused != pagecount)) {
 826                 nfs_pgio_error(hdr);
 827                 desc->pg_error = -EINVAL;
 828                 return desc->pg_error;
 829         }
 830
 831         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 832             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 833                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 834
 835         /* Set up the argument struct */
 836         nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
 837         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 838         return 0;
 839 }
 840 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 841
 842 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 843 {
 844         struct nfs_pgio_header *hdr;
 845         int ret;
 846
 847         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 848         if (!hdr) {
 849                 desc->pg_error = -ENOMEM;
 850                 return desc->pg_error;
 851         }
 852         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 853         ret = nfs_generic_pgio(desc, hdr);
 854         if (ret == 0)
 855                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 856                                         hdr,
 857                                         hdr->cred,
 858                                         NFS_PROTO(hdr->inode),
 859                                         desc->pg_rpc_callops,
 860                                         desc->pg_ioflags, 0);
 861         return ret;
 862 }
 863
 864 static struct nfs_pgio_mirror *
 865 nfs_pageio_alloc_mirrors(struct nfs_pageio_descriptor *desc,
 866                 unsigned int mirror_count)
 867 {
 868         struct nfs_pgio_mirror *ret;
 869         unsigned int i;
 870
 871         kfree(desc->pg_mirrors_dynamic);
 872         desc->pg_mirrors_dynamic = NULL;
 873         if (mirror_count == 1)
 874                 return desc->pg_mirrors_static;
 875         ret = kmalloc_array(mirror_count, sizeof(*ret), GFP_KERNEL);
 876         if (ret != NULL) {
 877                 for (i = 0; i < mirror_count; i++)
 878                         nfs_pageio_mirror_init(&ret[i], desc->pg_bsize);
 879                 desc->pg_mirrors_dynamic = ret;
 880         }
 881         return ret;
 882 }
 883
 884 /*
 885  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 886  *                              by calling the pg_get_mirror_count op
 887  */
 888 static void nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 889                                        struct nfs_page *req)
 890 {
 891         unsigned int mirror_count = 1;
 892
 893         if (pgio->pg_ops->pg_get_mirror_count)
 894                 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 895         if (mirror_count == pgio->pg_mirror_count || pgio->pg_error < 0)
 896                 return;
 897
 898         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX) {
 899                 pgio->pg_error = -EINVAL;
 900                 return;
 901         }
 902
 903         pgio->pg_mirrors = nfs_pageio_alloc_mirrors(pgio, mirror_count);
 904         if (pgio->pg_mirrors == NULL) {
 905                 pgio->pg_error = -ENOMEM;
 906                 pgio->pg_mirrors = pgio->pg_mirrors_static;
 907                 mirror_count = 1;
 908         }
 909         pgio->pg_mirror_count = mirror_count;
 910 }
 911
 912 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 913 {
 914         pgio->pg_mirror_count = 1;
 915         pgio->pg_mirror_idx = 0;
 916         pgio->pg_mirrors = pgio->pg_mirrors_static;
 917         kfree(pgio->pg_mirrors_dynamic);
 918         pgio->pg_mirrors_dynamic = NULL;
 919 }
 920
 921 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 922                 const struct nfs_lock_context *l2)
 923 {
 924         return l1->lockowner == l2->lockowner;
 925 }
 926
 927 /**
 928  * nfs_can_coalesce_requests - test two requests for compatibility
 929  * @prev: pointer to nfs_page
 930  * @req: pointer to nfs_page
 931  * @pgio: pointer to nfs_pagio_descriptor
 932  *
 933  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 934  * page data area they describe is contiguous, and that their RPC
 935  * credentials, NFSv4 open state, and lockowners are the same.
 936  *
 937  * Return 'true' if this is the case, else return 'false'.
 938  */
 939 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 940                                       struct nfs_page *req,
 941                                       struct nfs_pageio_descriptor *pgio)
 942 {
 943         size_t size;
 944         struct file_lock_context *flctx;
 945
 946         if (prev) {
 947                 if (!nfs_match_open_context(nfs_req_openctx(req), nfs_req_openctx(prev)))
 948                         return false;
 949                 flctx = d_inode(nfs_req_openctx(req)->dentry)->i_flctx;
 950                 if (flctx != NULL &&
 951                     !(list_empty_careful(&flctx->flc_posix) &&
 952                       list_empty_careful(&flctx->flc_flock)) &&
 953                     !nfs_match_lock_context(req->wb_lock_context,
 954                                             prev->wb_lock_context))
 955                         return false;
 956                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 957                         return false;
 958                 if (req->wb_page == prev->wb_page) {
 959                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 960                                 return false;
 961                 } else {
 962                         if (req->wb_pgbase != 0 ||
 963                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 964                                 return false;
 965                 }
 966         }
 967         size = pgio->pg_ops->pg_test(pgio, prev, req);
 968         WARN_ON_ONCE(size > req->wb_bytes);
 969         if (size && size < req->wb_bytes)
 970                 req->wb_bytes = size;
 971         return size > 0;
 972 }
 973
 974 /**
 975  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 976  * @desc: destination io descriptor
 977  * @req: request
 978  *
 979  * Returns true if the request 'req' was successfully coalesced into the
 980  * existing list of pages 'desc'.
 981  */
 982 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 983                                      struct nfs_page *req)
 984 {
 985         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 986
 987         struct nfs_page *prev = NULL;
 988
 989         if (list_empty(&mirror->pg_list)) {
 990                 if (desc->pg_ops->pg_init)
 991                         desc->pg_ops->pg_init(desc, req);
 992                 if (desc->pg_error < 0)
 993                         return 0;
 994                 mirror->pg_base = req->wb_pgbase;
 995                 mirror->pg_count = 0;
 996                 mirror->pg_recoalesce = 0;
 997         } else
 998                 prev = nfs_list_entry(mirror->pg_list.prev);
 999
1000         if (desc->pg_maxretrans && req->wb_nio > desc->pg_maxretrans) {
1001                 if (NFS_SERVER(desc->pg_inode)->flags & NFS_MOUNT_SOFTERR)
1002                         desc->pg_error = -ETIMEDOUT;
1003                 else
1004                         desc->pg_error = -EIO;
1005                 return 0;
1006         }
1007
1008         if (!nfs_can_coalesce_requests(prev, req, desc))
1009                 return 0;
1010         nfs_list_move_request(req, &mirror->pg_list);
1011         mirror->pg_count += req->wb_bytes;
1012         return 1;
1013 }
1014
1015 /*
1016  * Helper for nfs_pageio_add_request and nfs_pageio_complete
1017  */
1018 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
1019 {
1020         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1021
1022         if (!list_empty(&mirror->pg_list)) {
1023                 int error = desc->pg_ops->pg_doio(desc);
1024                 if (error < 0)
1025                         desc->pg_error = error;
1026                 if (list_empty(&mirror->pg_list)) {
1027                         mirror->pg_bytes_written += mirror->pg_count;
1028                         mirror->pg_count = 0;
1029                         mirror->pg_base = 0;
1030                         mirror->pg_recoalesce = 0;
1031                 }
1032         }
1033 }
1034
1035 static void
1036 nfs_pageio_cleanup_request(struct nfs_pageio_descriptor *desc,
1037                 struct nfs_page *req)
1038 {
1039         LIST_HEAD(head);
1040
1041         nfs_list_move_request(req, &head);
1042         desc->pg_completion_ops->error_cleanup(&head, desc->pg_error);
1043 }
1044
1045 /**
1046  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
1047  * @desc: destination io descriptor
1048  * @req: request
1049  *
1050  * This may split a request into subrequests which are all part of the
1051  * same page group.
1052  *
1053  * Returns true if the request 'req' was successfully coalesced into the
1054  * existing list of pages 'desc'.
1055  */
1056 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1057                            struct nfs_page *req)
1058 {
1059         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1060
1061         struct nfs_page *subreq;
1062         unsigned int bytes_left = 0;
1063         unsigned int offset, pgbase;
1064
1065         nfs_page_group_lock(req);
1066
1067         subreq = req;
1068         bytes_left = subreq->wb_bytes;
1069         offset = subreq->wb_offset;
1070         pgbase = subreq->wb_pgbase;
1071
1072         do {
1073                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1074                         /* make sure pg_test call(s) did nothing */
1075                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1076                         WARN_ON_ONCE(subreq->wb_offset != offset);
1077                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1078
1079                         nfs_page_group_unlock(req);
1080                         desc->pg_moreio = 1;
1081                         nfs_pageio_doio(desc);
1082                         if (desc->pg_error < 0 || mirror->pg_recoalesce)
1083                                 goto out_cleanup_subreq;
1084                         /* retry add_request for this subreq */
1085                         nfs_page_group_lock(req);
1086                         continue;
1087                 }
1088
1089                 /* check for buggy pg_test call(s) */
1090                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1091                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1092                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1093
1094                 bytes_left -= subreq->wb_bytes;
1095                 offset += subreq->wb_bytes;
1096                 pgbase += subreq->wb_bytes;
1097
1098                 if (bytes_left) {
1099                         subreq = nfs_create_subreq(req, subreq, pgbase,
1100                                         offset, bytes_left);
1101                         if (IS_ERR(subreq))
1102                                 goto err_ptr;
1103                 }
1104         } while (bytes_left > 0);
1105
1106         nfs_page_group_unlock(req);
1107         return 1;
1108 err_ptr:
1109         desc->pg_error = PTR_ERR(subreq);
1110         nfs_page_group_unlock(req);
1111         return 0;
1112 out_cleanup_subreq:
1113         if (req != subreq)
1114                 nfs_pageio_cleanup_request(desc, subreq);
1115         return 0;
1116 }
1117
1118 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1119 {
1120         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1121         LIST_HEAD(head);
1122
1123         do {
1124                 list_splice_init(&mirror->pg_list, &head);
1125                 mirror->pg_count = 0;
1126                 mirror->pg_base = 0;
1127                 mirror->pg_recoalesce = 0;
1128
1129                 while (!list_empty(&head)) {
1130                         struct nfs_page *req;
1131
1132                         req = list_first_entry(&head, struct nfs_page, wb_list);
1133                         if (__nfs_pageio_add_request(desc, req))
1134                                 continue;
1135                         if (desc->pg_error < 0) {
1136                                 list_splice_tail(&head, &mirror->pg_list);
1137                                 mirror->pg_recoalesce = 1;
1138                                 return 0;
1139                         }
1140                         break;
1141                 }
1142         } while (mirror->pg_recoalesce);
1143         return 1;
1144 }
1145
1146 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1147                 struct nfs_page *req)
1148 {
1149         int ret;
1150
1151         do {
1152                 ret = __nfs_pageio_add_request(desc, req);
1153                 if (ret)
1154                         break;
1155                 if (desc->pg_error < 0)
1156                         break;
1157                 ret = nfs_do_recoalesce(desc);
1158         } while (ret);
1159
1160         return ret;
1161 }
1162
1163 static void nfs_pageio_error_cleanup(struct nfs_pageio_descriptor *desc)
1164 {
1165         u32 midx;
1166         struct nfs_pgio_mirror *mirror;
1167
1168         if (!desc->pg_error)
1169                 return;
1170
1171         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1172                 mirror = &desc->pg_mirrors[midx];
1173                 desc->pg_completion_ops->error_cleanup(&mirror->pg_list,
1174                                 desc->pg_error);
1175         }
1176 }
1177
1178 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1179                            struct nfs_page *req)
1180 {
1181         u32 midx;
1182         unsigned int pgbase, offset, bytes;
1183         struct nfs_page *dupreq, *lastreq;
1184
1185         pgbase = req->wb_pgbase;
1186         offset = req->wb_offset;
1187         bytes = req->wb_bytes;
1188
1189         nfs_pageio_setup_mirroring(desc, req);
1190         if (desc->pg_error < 0)
1191                 goto out_failed;
1192
1193         /* Create the mirror instances first, and fire them off */
1194         for (midx = 1; midx < desc->pg_mirror_count; midx++) {
1195                 nfs_page_group_lock(req);
1196
1197                 /* find the last request */
1198                 for (lastreq = req->wb_head;
1199                      lastreq->wb_this_page != req->wb_head;
1200                      lastreq = lastreq->wb_this_page)
1201                         ;
1202
1203                 dupreq = nfs_create_subreq(req, lastreq,
1204                                 pgbase, offset, bytes);
1205
1206                 nfs_page_group_unlock(req);
1207                 if (IS_ERR(dupreq)) {
1208                         desc->pg_error = PTR_ERR(dupreq);
1209                         goto out_failed;
1210                 }
1211
1212                 desc->pg_mirror_idx = midx;
1213                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1214                         goto out_cleanup_subreq;
1215         }
1216
1217         desc->pg_mirror_idx = 0;
1218         if (!nfs_pageio_add_request_mirror(desc, req))
1219                 goto out_failed;
1220
1221         return 1;
1222
1223 out_cleanup_subreq:
1224         nfs_pageio_cleanup_request(desc, dupreq);
1225 out_failed:
1226         nfs_pageio_error_cleanup(desc);
1227         return 0;
1228 }
1229
1230 /*
1231  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1232  *                              nfs_pageio_descriptor
1233  * @desc: pointer to io descriptor
1234  * @mirror_idx: pointer to mirror index
1235  */
1236 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1237                                        u32 mirror_idx)
1238 {
1239         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1240         u32 restore_idx = desc->pg_mirror_idx;
1241
1242         if (nfs_pgio_has_mirroring(desc))
1243                 desc->pg_mirror_idx = mirror_idx;
1244         for (;;) {
1245                 nfs_pageio_doio(desc);
1246                 if (desc->pg_error < 0 || !mirror->pg_recoalesce)
1247                         break;
1248                 if (!nfs_do_recoalesce(desc))
1249                         break;
1250         }
1251         desc->pg_mirror_idx = restore_idx;
1252 }
1253
1254 /*
1255  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1256  * @hdr - the pgio header to move request from
1257  * @desc - the pageio descriptor to add requests to
1258  *
1259  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1260  * to send them.
1261  *
1262  * Returns 0 on success and < 0 on error.
1263  */
1264 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1265                       struct nfs_pgio_header *hdr)
1266 {
1267         LIST_HEAD(pages);
1268
1269         desc->pg_io_completion = hdr->io_completion;
1270         desc->pg_dreq = hdr->dreq;
1271         list_splice_init(&hdr->pages, &pages);
1272         while (!list_empty(&pages)) {
1273                 struct nfs_page *req = nfs_list_entry(pages.next);
1274
1275                 if (!nfs_pageio_add_request(desc, req))
1276                         break;
1277         }
1278         nfs_pageio_complete(desc);
1279         if (!list_empty(&pages)) {
1280                 int err = desc->pg_error < 0 ? desc->pg_error : -EIO;
1281                 hdr->completion_ops->error_cleanup(&pages, err);
1282                 nfs_set_pgio_error(hdr, err, hdr->io_start);
1283                 return err;
1284         }
1285         return 0;
1286 }
1287 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1288
1289 /**
1290  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1291  * @desc: pointer to io descriptor
1292  */
1293 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1294 {
1295         u32 midx;
1296
1297         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1298                 nfs_pageio_complete_mirror(desc, midx);
1299
1300         if (desc->pg_error < 0)
1301                 nfs_pageio_error_cleanup(desc);
1302         if (desc->pg_ops->pg_cleanup)
1303                 desc->pg_ops->pg_cleanup(desc);
1304         nfs_pageio_cleanup_mirroring(desc);
1305 }
1306
1307 /**
1308  * nfs_pageio_cond_complete - Conditional I/O completion
1309  * @desc: pointer to io descriptor
1310  * @index: page index
1311  *
1312  * It is important to ensure that processes don't try to take locks
1313  * on non-contiguous ranges of pages as that might deadlock. This
1314  * function should be called before attempting to wait on a locked
1315  * nfs_page. It will complete the I/O if the page index 'index'
1316  * is not contiguous with the existing list of pages in 'desc'.
1317  */
1318 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1319 {
1320         struct nfs_pgio_mirror *mirror;
1321         struct nfs_page *prev;
1322         u32 midx;
1323
1324         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1325                 mirror = &desc->pg_mirrors[midx];
1326                 if (!list_empty(&mirror->pg_list)) {
1327                         prev = nfs_list_entry(mirror->pg_list.prev);
1328                         if (index != prev->wb_index + 1) {
1329                                 nfs_pageio_complete(desc);
1330                                 break;
1331                         }
1332                 }
1333         }
1334 }
1335
1336 /*
1337  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
1338  */
1339 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
1340 {
1341         nfs_pageio_complete(pgio);
1342 }
1343
1344 int __init nfs_init_nfspagecache(void)
1345 {
1346         nfs_page_cachep = kmem_cache_create("nfs_page",
1347                                             sizeof(struct nfs_page),
1348                                             0, SLAB_HWCACHE_ALIGN,
1349                                             NULL);
1350         if (nfs_page_cachep == NULL)
1351                 return -ENOMEM;
1352
1353         return 0;
1354 }
1355
1356 void nfs_destroy_nfspagecache(void)
1357 {
1358         kmem_cache_destroy(nfs_page_cachep);
1359 }
1360
1361 static const struct rpc_call_ops nfs_pgio_common_ops = {
1362         .rpc_call_prepare = nfs_pgio_prepare,
1363         .rpc_call_done = nfs_pgio_result,
1364         .rpc_release = nfs_pgio_release,
1365 };
1366
1367 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1368         .pg_test = nfs_generic_pg_test,
1369         .pg_doio = nfs_generic_pg_pgios,
1370 };