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_var_event_killable(&l_ctx->io_count,
 102                                        !atomic_read(&l_ctx->io_count));
 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  *
 138  * this lock must be held when traversing or modifying the page
 139  * group list
 140  *
 141  * return 0 on success, < 0 on error
 142  */
 143 int
 144 nfs_page_group_lock(struct nfs_page *req)
 145 {
 146         struct nfs_page *head = req->wb_head;
 147
 148         WARN_ON_ONCE(head != head->wb_head);
 149
 150         if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
 151                 return 0;
 152
 153         set_bit(PG_CONTENDED1, &head->wb_flags);
 154         smp_mb__after_atomic();
 155         return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
 156                                 TASK_UNINTERRUPTIBLE);
 157 }
 158
 159 /*
 160  * nfs_page_group_unlock - unlock the head of the page group
 161  * @req - request in group that is to be unlocked
 162  */
 163 void
 164 nfs_page_group_unlock(struct nfs_page *req)
 165 {
 166         struct nfs_page *head = req->wb_head;
 167
 168         WARN_ON_ONCE(head != head->wb_head);
 169
 170         smp_mb__before_atomic();
 171         clear_bit(PG_HEADLOCK, &head->wb_flags);
 172         smp_mb__after_atomic();
 173         if (!test_bit(PG_CONTENDED1, &head->wb_flags))
 174                 return;
 175         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
 176 }
 177
 178 /*
 179  * nfs_page_group_sync_on_bit_locked
 180  *
 181  * must be called with page group lock held
 182  */
 183 static bool
 184 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 185 {
 186         struct nfs_page *head = req->wb_head;
 187         struct nfs_page *tmp;
 188
 189         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 190         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 191
 192         tmp = req->wb_this_page;
 193         while (tmp != req) {
 194                 if (!test_bit(bit, &tmp->wb_flags))
 195                         return false;
 196                 tmp = tmp->wb_this_page;
 197         }
 198
 199         /* true! reset all bits */
 200         tmp = req;
 201         do {
 202                 clear_bit(bit, &tmp->wb_flags);
 203                 tmp = tmp->wb_this_page;
 204         } while (tmp != req);
 205
 206         return true;
 207 }
 208
 209 /*
 210  * nfs_page_group_sync_on_bit - set bit on current request, but only
 211  *   return true if the bit is set for all requests in page group
 212  * @req - request in page group
 213  * @bit - PG_* bit that is used to sync page group
 214  */
 215 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 216 {
 217         bool ret;
 218
 219         nfs_page_group_lock(req);
 220         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 221         nfs_page_group_unlock(req);
 222
 223         return ret;
 224 }
 225
 226 /*
 227  * nfs_page_group_init - Initialize the page group linkage for @req
 228  * @req - a new nfs request
 229  * @prev - the previous request in page group, or NULL if @req is the first
 230  *         or only request in the group (the head).
 231  */
 232 static inline void
 233 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 234 {
 235         struct inode *inode;
 236         WARN_ON_ONCE(prev == req);
 237
 238         if (!prev) {
 239                 /* a head request */
 240                 req->wb_head = req;
 241                 req->wb_this_page = req;
 242         } else {
 243                 /* a subrequest */
 244                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 245                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 246                 req->wb_head = prev->wb_head;
 247                 req->wb_this_page = prev->wb_this_page;
 248                 prev->wb_this_page = req;
 249
 250                 /* All subrequests take a ref on the head request until
 251                  * nfs_page_group_destroy is called */
 252                 kref_get(&req->wb_head->wb_kref);
 253
 254                 /* grab extra ref and bump the request count if head request
 255                  * has extra ref from the write/commit path to handle handoff
 256                  * between write and commit lists. */
 257                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 258                         inode = page_file_mapping(req->wb_page)->host;
 259                         set_bit(PG_INODE_REF, &req->wb_flags);
 260                         kref_get(&req->wb_kref);
 261                         atomic_long_inc(&NFS_I(inode)->nrequests);
 262                 }
 263         }
 264 }
 265
 266 /*
 267  * nfs_page_group_destroy - sync the destruction of page groups
 268  * @req - request that no longer needs the page group
 269  *
 270  * releases the page group reference from each member once all
 271  * members have called this function.
 272  */
 273 static void
 274 nfs_page_group_destroy(struct kref *kref)
 275 {
 276         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 277         struct nfs_page *head = req->wb_head;
 278         struct nfs_page *tmp, *next;
 279
 280         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 281                 goto out;
 282
 283         tmp = req;
 284         do {
 285                 next = tmp->wb_this_page;
 286                 /* unlink and free */
 287                 tmp->wb_this_page = tmp;
 288                 tmp->wb_head = tmp;
 289                 nfs_free_request(tmp);
 290                 tmp = next;
 291         } while (tmp != req);
 292 out:
 293         /* subrequests must release the ref on the head request */
 294         if (head != req)
 295                 nfs_release_request(head);
 296 }
 297
 298 /**
 299  * nfs_create_request - Create an NFS read/write request.
 300  * @ctx: open context to use
 301  * @page: page to write
 302  * @last: last nfs request created for this page group or NULL if head
 303  * @offset: starting offset within the page for the write
 304  * @count: number of bytes to read/write
 305  *
 306  * The page must be locked by the caller. This makes sure we never
 307  * create two different requests for the same page.
 308  * User should ensure it is safe to sleep in this function.
 309  */
 310 struct nfs_page *
 311 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 312                    struct nfs_page *last, unsigned int offset,
 313                    unsigned int count)
 314 {
 315         struct nfs_page         *req;
 316         struct nfs_lock_context *l_ctx;
 317
 318         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 319                 return ERR_PTR(-EBADF);
 320         /* try to allocate the request struct */
 321         req = nfs_page_alloc();
 322         if (req == NULL)
 323                 return ERR_PTR(-ENOMEM);
 324
 325         /* get lock context early so we can deal with alloc failures */
 326         l_ctx = nfs_get_lock_context(ctx);
 327         if (IS_ERR(l_ctx)) {
 328                 nfs_page_free(req);
 329                 return ERR_CAST(l_ctx);
 330         }
 331         req->wb_lock_context = l_ctx;
 332         atomic_inc(&l_ctx->io_count);
 333
 334         /* Initialize the request struct. Initially, we assume a
 335          * long write-back delay. This will be adjusted in
 336          * update_nfs_request below if the region is not locked. */
 337         req->wb_page    = page;
 338         if (page) {
 339                 req->wb_index = page_index(page);
 340                 get_page(page);
 341         }
 342         req->wb_offset  = offset;
 343         req->wb_pgbase  = offset;
 344         req->wb_bytes   = count;
 345         req->wb_context = get_nfs_open_context(ctx);
 346         kref_init(&req->wb_kref);
 347         nfs_page_group_init(req, last);
 348         return req;
 349 }
 350
 351 /**
 352  * nfs_unlock_request - Unlock request and wake up sleepers.
 353  * @req:
 354  */
 355 void nfs_unlock_request(struct nfs_page *req)
 356 {
 357         if (!NFS_WBACK_BUSY(req)) {
 358                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 359                 BUG();
 360         }
 361         smp_mb__before_atomic();
 362         clear_bit(PG_BUSY, &req->wb_flags);
 363         smp_mb__after_atomic();
 364         if (!test_bit(PG_CONTENDED2, &req->wb_flags))
 365                 return;
 366         wake_up_bit(&req->wb_flags, PG_BUSY);
 367 }
 368
 369 /**
 370  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 371  * @req:
 372  */
 373 void nfs_unlock_and_release_request(struct nfs_page *req)
 374 {
 375         nfs_unlock_request(req);
 376         nfs_release_request(req);
 377 }
 378
 379 /*
 380  * nfs_clear_request - Free up all resources allocated to the request
 381  * @req:
 382  *
 383  * Release page and open context resources associated with a read/write
 384  * request after it has completed.
 385  */
 386 static void nfs_clear_request(struct nfs_page *req)
 387 {
 388         struct page *page = req->wb_page;
 389         struct nfs_open_context *ctx = req->wb_context;
 390         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 391
 392         if (page != NULL) {
 393                 put_page(page);
 394                 req->wb_page = NULL;
 395         }
 396         if (l_ctx != NULL) {
 397                 if (atomic_dec_and_test(&l_ctx->io_count)) {
 398                         wake_up_var(&l_ctx->io_count);
 399                         if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
 400                                 rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
 401                 }
 402                 nfs_put_lock_context(l_ctx);
 403                 req->wb_lock_context = NULL;
 404         }
 405         if (ctx != NULL) {
 406                 put_nfs_open_context(ctx);
 407                 req->wb_context = NULL;
 408         }
 409 }
 410
 411 /**
 412  * nfs_release_request - Release the count on an NFS read/write request
 413  * @req: request to release
 414  *
 415  * Note: Should never be called with the spinlock held!
 416  */
 417 void nfs_free_request(struct nfs_page *req)
 418 {
 419         WARN_ON_ONCE(req->wb_this_page != req);
 420
 421         /* extra debug: make sure no sync bits are still set */
 422         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 423         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 424         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 425         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 426         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 427
 428         /* Release struct file and open context */
 429         nfs_clear_request(req);
 430         nfs_page_free(req);
 431 }
 432
 433 void nfs_release_request(struct nfs_page *req)
 434 {
 435         kref_put(&req->wb_kref, nfs_page_group_destroy);
 436 }
 437 EXPORT_SYMBOL_GPL(nfs_release_request);
 438
 439 /**
 440  * nfs_wait_on_request - Wait for a request to complete.
 441  * @req: request to wait upon.
 442  *
 443  * Interruptible by fatal signals only.
 444  * The user is responsible for holding a count on the request.
 445  */
 446 int
 447 nfs_wait_on_request(struct nfs_page *req)
 448 {
 449         if (!test_bit(PG_BUSY, &req->wb_flags))
 450                 return 0;
 451         set_bit(PG_CONTENDED2, &req->wb_flags);
 452         smp_mb__after_atomic();
 453         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 454                               TASK_UNINTERRUPTIBLE);
 455 }
 456 EXPORT_SYMBOL_GPL(nfs_wait_on_request);
 457
 458 /*
 459  * nfs_generic_pg_test - determine if requests can be coalesced
 460  * @desc: pointer to descriptor
 461  * @prev: previous request in desc, or NULL
 462  * @req: this request
 463  *
 464  * Returns zero if @req can be coalesced into @desc, otherwise it returns
 465  * the size of the request.
 466  */
 467 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 468                            struct nfs_page *prev, struct nfs_page *req)
 469 {
 470         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 471
 472
 473         if (mirror->pg_count > mirror->pg_bsize) {
 474                 /* should never happen */
 475                 WARN_ON_ONCE(1);
 476                 return 0;
 477         }
 478
 479         /*
 480          * Limit the request size so that we can still allocate a page array
 481          * for it without upsetting the slab allocator.
 482          */
 483         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 484                         sizeof(struct page *) > PAGE_SIZE)
 485                 return 0;
 486
 487         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 488 }
 489 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 490
 491 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 492 {
 493         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 494
 495         if (hdr) {
 496                 INIT_LIST_HEAD(&hdr->pages);
 497                 spin_lock_init(&hdr->lock);
 498                 hdr->rw_ops = ops;
 499         }
 500         return hdr;
 501 }
 502 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 503
 504 /**
 505  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 506  *
 507  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 508  * be called again.
 509  *
 510  * @hdr: A header that has had nfs_generic_pgio called
 511  */
 512 static void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 513 {
 514         if (hdr->args.context)
 515                 put_nfs_open_context(hdr->args.context);
 516         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 517                 kfree(hdr->page_array.pagevec);
 518 }
 519
 520 /*
 521  * nfs_pgio_header_free - Free a read or write header
 522  * @hdr: The header to free
 523  */
 524 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 525 {
 526         nfs_pgio_data_destroy(hdr);
 527         hdr->rw_ops->rw_free_header(hdr);
 528 }
 529 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 530
 531 /**
 532  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 533  * @hdr: The pageio hdr
 534  * @count: Number of bytes to read
 535  * @offset: Initial offset
 536  * @how: How to commit data (writes only)
 537  * @cinfo: Commit information for the call (writes only)
 538  */
 539 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 540                               unsigned int count,
 541                               int how, struct nfs_commit_info *cinfo)
 542 {
 543         struct nfs_page *req = hdr->req;
 544
 545         /* Set up the RPC argument and reply structs
 546          * NB: take care not to mess about with hdr->commit et al. */
 547
 548         hdr->args.fh     = NFS_FH(hdr->inode);
 549         hdr->args.offset = req_offset(req);
 550         /* pnfs_set_layoutcommit needs this */
 551         hdr->mds_offset = hdr->args.offset;
 552         hdr->args.pgbase = req->wb_pgbase;
 553         hdr->args.pages  = hdr->page_array.pagevec;
 554         hdr->args.count  = count;
 555         hdr->args.context = get_nfs_open_context(req->wb_context);
 556         hdr->args.lock_context = req->wb_lock_context;
 557         hdr->args.stable  = NFS_UNSTABLE;
 558         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 559         case 0:
 560                 break;
 561         case FLUSH_COND_STABLE:
 562                 if (nfs_reqs_to_commit(cinfo))
 563                         break;
 564                 /* fall through */
 565         default:
 566                 hdr->args.stable = NFS_FILE_SYNC;
 567         }
 568
 569         hdr->res.fattr   = &hdr->fattr;
 570         hdr->res.count   = count;
 571         hdr->res.eof     = 0;
 572         hdr->res.verf    = &hdr->verf;
 573         nfs_fattr_init(&hdr->fattr);
 574 }
 575
 576 /**
 577  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 578  * @task: The current task
 579  * @calldata: pageio header to prepare
 580  */
 581 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 582 {
 583         struct nfs_pgio_header *hdr = calldata;
 584         int err;
 585         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 586         if (err)
 587                 rpc_exit(task, err);
 588 }
 589
 590 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 591                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
 592                       const struct rpc_call_ops *call_ops, int how, int flags)
 593 {
 594         struct rpc_task *task;
 595         struct rpc_message msg = {
 596                 .rpc_argp = &hdr->args,
 597                 .rpc_resp = &hdr->res,
 598                 .rpc_cred = cred,
 599         };
 600         struct rpc_task_setup task_setup_data = {
 601                 .rpc_client = clnt,
 602                 .task = &hdr->task,
 603                 .rpc_message = &msg,
 604                 .callback_ops = call_ops,
 605                 .callback_data = hdr,
 606                 .workqueue = nfsiod_workqueue,
 607                 .flags = RPC_TASK_ASYNC | flags,
 608         };
 609         int ret = 0;
 610
 611         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 612
 613         dprintk("NFS: initiated pgio call "
 614                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 615                 hdr->inode->i_sb->s_id,
 616                 (unsigned long long)NFS_FILEID(hdr->inode),
 617                 hdr->args.count,
 618                 (unsigned long long)hdr->args.offset);
 619
 620         task = rpc_run_task(&task_setup_data);
 621         if (IS_ERR(task)) {
 622                 ret = PTR_ERR(task);
 623                 goto out;
 624         }
 625         if (how & FLUSH_SYNC) {
 626                 ret = rpc_wait_for_completion_task(task);
 627                 if (ret == 0)
 628                         ret = task->tk_status;
 629         }
 630         rpc_put_task(task);
 631 out:
 632         return ret;
 633 }
 634 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 635
 636 /**
 637  * nfs_pgio_error - Clean up from a pageio error
 638  * @desc: IO descriptor
 639  * @hdr: pageio header
 640  */
 641 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 642 {
 643         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 644         hdr->completion_ops->completion(hdr);
 645 }
 646
 647 /**
 648  * nfs_pgio_release - Release pageio data
 649  * @calldata: The pageio header to release
 650  */
 651 static void nfs_pgio_release(void *calldata)
 652 {
 653         struct nfs_pgio_header *hdr = calldata;
 654         hdr->completion_ops->completion(hdr);
 655 }
 656
 657 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 658                                    unsigned int bsize)
 659 {
 660         INIT_LIST_HEAD(&mirror->pg_list);
 661         mirror->pg_bytes_written = 0;
 662         mirror->pg_count = 0;
 663         mirror->pg_bsize = bsize;
 664         mirror->pg_base = 0;
 665         mirror->pg_recoalesce = 0;
 666 }
 667
 668 /**
 669  * nfs_pageio_init - initialise a page io descriptor
 670  * @desc: pointer to descriptor
 671  * @inode: pointer to inode
 672  * @pg_ops: pointer to pageio operations
 673  * @compl_ops: pointer to pageio completion operations
 674  * @rw_ops: pointer to nfs read/write operations
 675  * @bsize: io block size
 676  * @io_flags: extra parameters for the io function
 677  */
 678 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 679                      struct inode *inode,
 680                      const struct nfs_pageio_ops *pg_ops,
 681                      const struct nfs_pgio_completion_ops *compl_ops,
 682                      const struct nfs_rw_ops *rw_ops,
 683                      size_t bsize,
 684                      int io_flags)
 685 {
 686         desc->pg_moreio = 0;
 687         desc->pg_inode = inode;
 688         desc->pg_ops = pg_ops;
 689         desc->pg_completion_ops = compl_ops;
 690         desc->pg_rw_ops = rw_ops;
 691         desc->pg_ioflags = io_flags;
 692         desc->pg_error = 0;
 693         desc->pg_lseg = NULL;
 694         desc->pg_io_completion = NULL;
 695         desc->pg_dreq = NULL;
 696         desc->pg_bsize = bsize;
 697
 698         desc->pg_mirror_count = 1;
 699         desc->pg_mirror_idx = 0;
 700
 701         desc->pg_mirrors_dynamic = NULL;
 702         desc->pg_mirrors = desc->pg_mirrors_static;
 703         nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 704 }
 705
 706 /**
 707  * nfs_pgio_result - Basic pageio error handling
 708  * @task: The task that ran
 709  * @calldata: Pageio header to check
 710  */
 711 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 712 {
 713         struct nfs_pgio_header *hdr = calldata;
 714         struct inode *inode = hdr->inode;
 715
 716         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 717                 task->tk_pid, task->tk_status);
 718
 719         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 720                 return;
 721         if (task->tk_status < 0)
 722                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 723         else
 724                 hdr->rw_ops->rw_result(task, hdr);
 725 }
 726
 727 /*
 728  * Create an RPC task for the given read or write request and kick it.
 729  * The page must have been locked by the caller.
 730  *
 731  * It may happen that the page we're passed is not marked dirty.
 732  * This is the case if nfs_updatepage detects a conflicting request
 733  * that has been written but not committed.
 734  */
 735 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 736                      struct nfs_pgio_header *hdr)
 737 {
 738         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 739
 740         struct nfs_page         *req;
 741         struct page             **pages,
 742                                 *last_page;
 743         struct list_head *head = &mirror->pg_list;
 744         struct nfs_commit_info cinfo;
 745         struct nfs_page_array *pg_array = &hdr->page_array;
 746         unsigned int pagecount, pageused;
 747         gfp_t gfp_flags = GFP_KERNEL;
 748
 749         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 750         pg_array->npages = pagecount;
 751
 752         if (pagecount <= ARRAY_SIZE(pg_array->page_array))
 753                 pg_array->pagevec = pg_array->page_array;
 754         else {
 755                 if (hdr->rw_mode == FMODE_WRITE)
 756                         gfp_flags = GFP_NOIO;
 757                 pg_array->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
 758                 if (!pg_array->pagevec) {
 759                         pg_array->npages = 0;
 760                         nfs_pgio_error(hdr);
 761                         desc->pg_error = -ENOMEM;
 762                         return desc->pg_error;
 763                 }
 764         }
 765
 766         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 767         pages = hdr->page_array.pagevec;
 768         last_page = NULL;
 769         pageused = 0;
 770         while (!list_empty(head)) {
 771                 req = nfs_list_entry(head->next);
 772                 nfs_list_remove_request(req);
 773                 nfs_list_add_request(req, &hdr->pages);
 774
 775                 if (!last_page || last_page != req->wb_page) {
 776                         pageused++;
 777                         if (pageused > pagecount)
 778                                 break;
 779                         *pages++ = last_page = req->wb_page;
 780                 }
 781         }
 782         if (WARN_ON_ONCE(pageused != pagecount)) {
 783                 nfs_pgio_error(hdr);
 784                 desc->pg_error = -EINVAL;
 785                 return desc->pg_error;
 786         }
 787
 788         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 789             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 790                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 791
 792         /* Set up the argument struct */
 793         nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
 794         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 795         return 0;
 796 }
 797 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 798
 799 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 800 {
 801         struct nfs_pgio_header *hdr;
 802         int ret;
 803
 804         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 805         if (!hdr) {
 806                 desc->pg_error = -ENOMEM;
 807                 return desc->pg_error;
 808         }
 809         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 810         ret = nfs_generic_pgio(desc, hdr);
 811         if (ret == 0)
 812                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 813                                         hdr,
 814                                         hdr->cred,
 815                                         NFS_PROTO(hdr->inode),
 816                                         desc->pg_rpc_callops,
 817                                         desc->pg_ioflags, 0);
 818         return ret;
 819 }
 820
 821 static struct nfs_pgio_mirror *
 822 nfs_pageio_alloc_mirrors(struct nfs_pageio_descriptor *desc,
 823                 unsigned int mirror_count)
 824 {
 825         struct nfs_pgio_mirror *ret;
 826         unsigned int i;
 827
 828         kfree(desc->pg_mirrors_dynamic);
 829         desc->pg_mirrors_dynamic = NULL;
 830         if (mirror_count == 1)
 831                 return desc->pg_mirrors_static;
 832         ret = kmalloc_array(mirror_count, sizeof(*ret), GFP_NOFS);
 833         if (ret != NULL) {
 834                 for (i = 0; i < mirror_count; i++)
 835                         nfs_pageio_mirror_init(&ret[i], desc->pg_bsize);
 836                 desc->pg_mirrors_dynamic = ret;
 837         }
 838         return ret;
 839 }
 840
 841 /*
 842  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 843  *                              by calling the pg_get_mirror_count op
 844  */
 845 static void nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 846                                        struct nfs_page *req)
 847 {
 848         unsigned int mirror_count = 1;
 849
 850         if (pgio->pg_ops->pg_get_mirror_count)
 851                 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 852         if (mirror_count == pgio->pg_mirror_count || pgio->pg_error < 0)
 853                 return;
 854
 855         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX) {
 856                 pgio->pg_error = -EINVAL;
 857                 return;
 858         }
 859
 860         pgio->pg_mirrors = nfs_pageio_alloc_mirrors(pgio, mirror_count);
 861         if (pgio->pg_mirrors == NULL) {
 862                 pgio->pg_error = -ENOMEM;
 863                 pgio->pg_mirrors = pgio->pg_mirrors_static;
 864                 mirror_count = 1;
 865         }
 866         pgio->pg_mirror_count = mirror_count;
 867 }
 868
 869 /*
 870  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
 871  */
 872 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
 873 {
 874         pgio->pg_mirror_count = 1;
 875         pgio->pg_mirror_idx = 0;
 876 }
 877
 878 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 879 {
 880         pgio->pg_mirror_count = 1;
 881         pgio->pg_mirror_idx = 0;
 882         pgio->pg_mirrors = pgio->pg_mirrors_static;
 883         kfree(pgio->pg_mirrors_dynamic);
 884         pgio->pg_mirrors_dynamic = NULL;
 885 }
 886
 887 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 888                 const struct nfs_lock_context *l2)
 889 {
 890         return l1->lockowner == l2->lockowner;
 891 }
 892
 893 /**
 894  * nfs_can_coalesce_requests - test two requests for compatibility
 895  * @prev: pointer to nfs_page
 896  * @req: pointer to nfs_page
 897  *
 898  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 899  * page data area they describe is contiguous, and that their RPC
 900  * credentials, NFSv4 open state, and lockowners are the same.
 901  *
 902  * Return 'true' if this is the case, else return 'false'.
 903  */
 904 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 905                                       struct nfs_page *req,
 906                                       struct nfs_pageio_descriptor *pgio)
 907 {
 908         size_t size;
 909         struct file_lock_context *flctx;
 910
 911         if (prev) {
 912                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 913                         return false;
 914                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
 915                 if (flctx != NULL &&
 916                     !(list_empty_careful(&flctx->flc_posix) &&
 917                       list_empty_careful(&flctx->flc_flock)) &&
 918                     !nfs_match_lock_context(req->wb_lock_context,
 919                                             prev->wb_lock_context))
 920                         return false;
 921                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 922                         return false;
 923                 if (req->wb_page == prev->wb_page) {
 924                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 925                                 return false;
 926                 } else {
 927                         if (req->wb_pgbase != 0 ||
 928                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 929                                 return false;
 930                 }
 931         }
 932         size = pgio->pg_ops->pg_test(pgio, prev, req);
 933         WARN_ON_ONCE(size > req->wb_bytes);
 934         if (size && size < req->wb_bytes)
 935                 req->wb_bytes = size;
 936         return size > 0;
 937 }
 938
 939 /**
 940  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 941  * @desc: destination io descriptor
 942  * @req: request
 943  *
 944  * Returns true if the request 'req' was successfully coalesced into the
 945  * existing list of pages 'desc'.
 946  */
 947 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 948                                      struct nfs_page *req)
 949 {
 950         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 951
 952         struct nfs_page *prev = NULL;
 953
 954         if (mirror->pg_count != 0) {
 955                 prev = nfs_list_entry(mirror->pg_list.prev);
 956         } else {
 957                 if (desc->pg_ops->pg_init)
 958                         desc->pg_ops->pg_init(desc, req);
 959                 if (desc->pg_error < 0)
 960                         return 0;
 961                 mirror->pg_base = req->wb_pgbase;
 962         }
 963         if (!nfs_can_coalesce_requests(prev, req, desc))
 964                 return 0;
 965         nfs_list_remove_request(req);
 966         nfs_list_add_request(req, &mirror->pg_list);
 967         mirror->pg_count += req->wb_bytes;
 968         return 1;
 969 }
 970
 971 /*
 972  * Helper for nfs_pageio_add_request and nfs_pageio_complete
 973  */
 974 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 975 {
 976         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 977
 978
 979         if (!list_empty(&mirror->pg_list)) {
 980                 int error = desc->pg_ops->pg_doio(desc);
 981                 if (error < 0)
 982                         desc->pg_error = error;
 983                 else
 984                         mirror->pg_bytes_written += mirror->pg_count;
 985         }
 986         if (list_empty(&mirror->pg_list)) {
 987                 mirror->pg_count = 0;
 988                 mirror->pg_base = 0;
 989         }
 990 }
 991
 992 /**
 993  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
 994  * @desc: destination io descriptor
 995  * @req: request
 996  *
 997  * This may split a request into subrequests which are all part of the
 998  * same page group.
 999  *
1000  * Returns true if the request 'req' was successfully coalesced into the
1001  * existing list of pages 'desc'.
1002  */
1003 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1004                            struct nfs_page *req)
1005 {
1006         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1007
1008         struct nfs_page *subreq;
1009         unsigned int bytes_left = 0;
1010         unsigned int offset, pgbase;
1011
1012         nfs_page_group_lock(req);
1013
1014         subreq = req;
1015         bytes_left = subreq->wb_bytes;
1016         offset = subreq->wb_offset;
1017         pgbase = subreq->wb_pgbase;
1018
1019         do {
1020                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1021                         /* make sure pg_test call(s) did nothing */
1022                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1023                         WARN_ON_ONCE(subreq->wb_offset != offset);
1024                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1025
1026                         nfs_page_group_unlock(req);
1027                         desc->pg_moreio = 1;
1028                         nfs_pageio_doio(desc);
1029                         if (desc->pg_error < 0)
1030                                 return 0;
1031                         if (mirror->pg_recoalesce)
1032                                 return 0;
1033                         /* retry add_request for this subreq */
1034                         nfs_page_group_lock(req);
1035                         continue;
1036                 }
1037
1038                 /* check for buggy pg_test call(s) */
1039                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1040                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1041                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1042
1043                 bytes_left -= subreq->wb_bytes;
1044                 offset += subreq->wb_bytes;
1045                 pgbase += subreq->wb_bytes;
1046
1047                 if (bytes_left) {
1048                         subreq = nfs_create_request(req->wb_context,
1049                                         req->wb_page,
1050                                         subreq, pgbase, bytes_left);
1051                         if (IS_ERR(subreq))
1052                                 goto err_ptr;
1053                         nfs_lock_request(subreq);
1054                         subreq->wb_offset  = offset;
1055                         subreq->wb_index = req->wb_index;
1056                 }
1057         } while (bytes_left > 0);
1058
1059         nfs_page_group_unlock(req);
1060         return 1;
1061 err_ptr:
1062         desc->pg_error = PTR_ERR(subreq);
1063         nfs_page_group_unlock(req);
1064         return 0;
1065 }
1066
1067 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1068 {
1069         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1070         LIST_HEAD(head);
1071
1072         do {
1073                 list_splice_init(&mirror->pg_list, &head);
1074                 mirror->pg_bytes_written -= mirror->pg_count;
1075                 mirror->pg_count = 0;
1076                 mirror->pg_base = 0;
1077                 mirror->pg_recoalesce = 0;
1078
1079                 while (!list_empty(&head)) {
1080                         struct nfs_page *req;
1081
1082                         req = list_first_entry(&head, struct nfs_page, wb_list);
1083                         nfs_list_remove_request(req);
1084                         if (__nfs_pageio_add_request(desc, req))
1085                                 continue;
1086                         if (desc->pg_error < 0) {
1087                                 list_splice_tail(&head, &mirror->pg_list);
1088                                 mirror->pg_recoalesce = 1;
1089                                 return 0;
1090                         }
1091                         break;
1092                 }
1093         } while (mirror->pg_recoalesce);
1094         return 1;
1095 }
1096
1097 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1098                 struct nfs_page *req)
1099 {
1100         int ret;
1101
1102         do {
1103                 ret = __nfs_pageio_add_request(desc, req);
1104                 if (ret)
1105                         break;
1106                 if (desc->pg_error < 0)
1107                         break;
1108                 ret = nfs_do_recoalesce(desc);
1109         } while (ret);
1110
1111         return ret;
1112 }
1113
1114 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1115                            struct nfs_page *req)
1116 {
1117         u32 midx;
1118         unsigned int pgbase, offset, bytes;
1119         struct nfs_page *dupreq, *lastreq;
1120
1121         pgbase = req->wb_pgbase;
1122         offset = req->wb_offset;
1123         bytes = req->wb_bytes;
1124
1125         nfs_pageio_setup_mirroring(desc, req);
1126         if (desc->pg_error < 0)
1127                 goto out_failed;
1128
1129         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1130                 if (midx) {
1131                         nfs_page_group_lock(req);
1132
1133                         /* find the last request */
1134                         for (lastreq = req->wb_head;
1135                              lastreq->wb_this_page != req->wb_head;
1136                              lastreq = lastreq->wb_this_page)
1137                                 ;
1138
1139                         dupreq = nfs_create_request(req->wb_context,
1140                                         req->wb_page, lastreq, pgbase, bytes);
1141
1142                         if (IS_ERR(dupreq)) {
1143                                 nfs_page_group_unlock(req);
1144                                 desc->pg_error = PTR_ERR(dupreq);
1145                                 goto out_failed;
1146                         }
1147
1148                         nfs_lock_request(dupreq);
1149                         nfs_page_group_unlock(req);
1150                         dupreq->wb_offset = offset;
1151                         dupreq->wb_index = req->wb_index;
1152                 } else
1153                         dupreq = req;
1154
1155                 if (nfs_pgio_has_mirroring(desc))
1156                         desc->pg_mirror_idx = midx;
1157                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1158                         goto out_failed;
1159         }
1160
1161         return 1;
1162
1163 out_failed:
1164         /*
1165          * We might have failed before sending any reqs over wire.
1166          * Clean up rest of the reqs in mirror pg_list.
1167          */
1168         if (desc->pg_error) {
1169                 struct nfs_pgio_mirror *mirror;
1170                 void (*func)(struct list_head *);
1171
1172                 /* remember fatal errors */
1173                 if (nfs_error_is_fatal(desc->pg_error))
1174                         nfs_context_set_write_error(req->wb_context,
1175                                                     desc->pg_error);
1176
1177                 func = desc->pg_completion_ops->error_cleanup;
1178                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1179                         mirror = &desc->pg_mirrors[midx];
1180                         func(&mirror->pg_list);
1181                 }
1182         }
1183         return 0;
1184 }
1185
1186 /*
1187  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1188  *                              nfs_pageio_descriptor
1189  * @desc: pointer to io descriptor
1190  * @mirror_idx: pointer to mirror index
1191  */
1192 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1193                                        u32 mirror_idx)
1194 {
1195         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1196         u32 restore_idx = desc->pg_mirror_idx;
1197
1198         if (nfs_pgio_has_mirroring(desc))
1199                 desc->pg_mirror_idx = mirror_idx;
1200         for (;;) {
1201                 nfs_pageio_doio(desc);
1202                 if (!mirror->pg_recoalesce)
1203                         break;
1204                 if (!nfs_do_recoalesce(desc))
1205                         break;
1206         }
1207         desc->pg_mirror_idx = restore_idx;
1208 }
1209
1210 /*
1211  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1212  * @hdr - the pgio header to move request from
1213  * @desc - the pageio descriptor to add requests to
1214  *
1215  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1216  * to send them.
1217  *
1218  * Returns 0 on success and < 0 on error.
1219  */
1220 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1221                       struct nfs_pgio_header *hdr)
1222 {
1223         LIST_HEAD(failed);
1224
1225         desc->pg_io_completion = hdr->io_completion;
1226         desc->pg_dreq = hdr->dreq;
1227         while (!list_empty(&hdr->pages)) {
1228                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1229
1230                 nfs_list_remove_request(req);
1231                 if (!nfs_pageio_add_request(desc, req))
1232                         nfs_list_add_request(req, &failed);
1233         }
1234         nfs_pageio_complete(desc);
1235         if (!list_empty(&failed)) {
1236                 list_move(&failed, &hdr->pages);
1237                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1238         }
1239         return 0;
1240 }
1241 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1242
1243 /**
1244  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1245  * @desc: pointer to io descriptor
1246  */
1247 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1248 {
1249         u32 midx;
1250
1251         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1252                 nfs_pageio_complete_mirror(desc, midx);
1253
1254         if (desc->pg_ops->pg_cleanup)
1255                 desc->pg_ops->pg_cleanup(desc);
1256         nfs_pageio_cleanup_mirroring(desc);
1257 }
1258
1259 /**
1260  * nfs_pageio_cond_complete - Conditional I/O completion
1261  * @desc: pointer to io descriptor
1262  * @index: page index
1263  *
1264  * It is important to ensure that processes don't try to take locks
1265  * on non-contiguous ranges of pages as that might deadlock. This
1266  * function should be called before attempting to wait on a locked
1267  * nfs_page. It will complete the I/O if the page index 'index'
1268  * is not contiguous with the existing list of pages in 'desc'.
1269  */
1270 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1271 {
1272         struct nfs_pgio_mirror *mirror;
1273         struct nfs_page *prev;
1274         u32 midx;
1275
1276         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1277                 mirror = &desc->pg_mirrors[midx];
1278                 if (!list_empty(&mirror->pg_list)) {
1279                         prev = nfs_list_entry(mirror->pg_list.prev);
1280                         if (index != prev->wb_index + 1) {
1281                                 nfs_pageio_complete(desc);
1282                                 break;
1283                         }
1284                 }
1285         }
1286 }
1287
1288 int __init nfs_init_nfspagecache(void)
1289 {
1290         nfs_page_cachep = kmem_cache_create("nfs_page",
1291                                             sizeof(struct nfs_page),
1292                                             0, SLAB_HWCACHE_ALIGN,
1293                                             NULL);
1294         if (nfs_page_cachep == NULL)
1295                 return -ENOMEM;
1296
1297         return 0;
1298 }
1299
1300 void nfs_destroy_nfspagecache(void)
1301 {
1302         kmem_cache_destroy(nfs_page_cachep);
1303 }
1304
1305 static const struct rpc_call_ops nfs_pgio_common_ops = {
1306         .rpc_call_prepare = nfs_pgio_prepare,
1307         .rpc_call_done = nfs_pgio_result,
1308         .rpc_release = nfs_pgio_release,
1309 };
1310
1311 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1312         .pg_test = nfs_generic_pg_test,
1313         .pg_doio = nfs_generic_pg_pgios,
1314 };