fs/nfs/pagelist.c

   1 /*
   2  * linux/fs/nfs/pagelist.c
   3  *
   4  * A set of helper functions for managing NFS read and write requests.
   5  * The main purpose of these routines is to provide support for the
   6  * coalescing of several requests into a single RPC call.
   7  *
   8  * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
   9  *
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/file.h>
  14 #include <linux/sched.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/nfs.h>
  17 #include <linux/nfs3.h>
  18 #include <linux/nfs4.h>
  19 #include <linux/nfs_page.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_mount.h>
  22 #include <linux/export.h>
  23
  24 #include "internal.h"
  25 #include "pnfs.h"
  26
  27 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  28
  29 static struct kmem_cache *nfs_page_cachep;
  30 static const struct rpc_call_ops nfs_pgio_common_ops;
  31
  32 static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount,
  33                                         gfp_t gfp_flags)
  34 {
  35         p->npages = pagecount;
  36         if (pagecount <= ARRAY_SIZE(p->page_array))
  37                 p->pagevec = p->page_array;
  38         else {
  39                 p->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
  40                 if (!p->pagevec)
  41                         p->npages = 0;
  42         }
  43         return p->pagevec != NULL;
  44 }
  45
  46 struct nfs_pgio_mirror *
  47 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
  48 {
  49         return nfs_pgio_has_mirroring(desc) ?
  50                 &desc->pg_mirrors[desc->pg_mirror_idx] :
  51                 &desc->pg_mirrors[0];
  52 }
  53 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
  54
  55 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  56                        struct nfs_pgio_header *hdr,
  57                        void (*release)(struct nfs_pgio_header *hdr))
  58 {
  59         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
  60
  61
  62         hdr->req = nfs_list_entry(mirror->pg_list.next);
  63         hdr->inode = desc->pg_inode;
  64         hdr->cred = hdr->req->wb_context->cred;
  65         hdr->io_start = req_offset(hdr->req);
  66         hdr->good_bytes = mirror->pg_count;
  67         hdr->dreq = desc->pg_dreq;
  68         hdr->layout_private = desc->pg_layout_private;
  69         hdr->release = release;
  70         hdr->completion_ops = desc->pg_completion_ops;
  71         if (hdr->completion_ops->init_hdr)
  72                 hdr->completion_ops->init_hdr(hdr);
  73
  74         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
  75 }
  76 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
  77
  78 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
  79 {
  80         spin_lock(&hdr->lock);
  81         if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags)
  82             || pos < hdr->io_start + hdr->good_bytes) {
  83                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
  84                 hdr->good_bytes = pos - hdr->io_start;
  85                 hdr->error = error;
  86         }
  87         spin_unlock(&hdr->lock);
  88 }
  89
  90 static inline struct nfs_page *
  91 nfs_page_alloc(void)
  92 {
  93         struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
  94         if (p)
  95                 INIT_LIST_HEAD(&p->wb_list);
  96         return p;
  97 }
  98
  99 static inline void
 100 nfs_page_free(struct nfs_page *p)
 101 {
 102         kmem_cache_free(nfs_page_cachep, p);
 103 }
 104
 105 /**
 106  * nfs_iocounter_wait - wait for i/o to complete
 107  * @l_ctx: nfs_lock_context with io_counter to use
 108  *
 109  * returns -ERESTARTSYS if interrupted by a fatal signal.
 110  * Otherwise returns 0 once the io_count hits 0.
 111  */
 112 int
 113 nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
 114 {
 115         return wait_on_atomic_t(&l_ctx->io_count, nfs_wait_atomic_killable,
 116                         TASK_KILLABLE);
 117 }
 118
 119 /*
 120  * nfs_page_group_lock - lock the head of the page group
 121  * @req - request in group that is to be locked
 122  * @nonblock - if true don't block waiting for lock
 123  *
 124  * this lock must be held if modifying the page group list
 125  *
 126  * return 0 on success, < 0 on error: -EDELAY if nonblocking or the
 127  * result from wait_on_bit_lock
 128  *
 129  * NOTE: calling with nonblock=false should always have set the
 130  *       lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
 131  *       with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
 132  */
 133 int
 134 nfs_page_group_lock(struct nfs_page *req, bool nonblock)
 135 {
 136         struct nfs_page *head = req->wb_head;
 137
 138         WARN_ON_ONCE(head != head->wb_head);
 139
 140         if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
 141                 return 0;
 142
 143         if (!nonblock)
 144                 return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
 145                                 TASK_UNINTERRUPTIBLE);
 146
 147         return -EAGAIN;
 148 }
 149
 150 /*
 151  * nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
 152  * @req - a request in the group
 153  *
 154  * This is a blocking call to wait for the group lock to be cleared.
 155  */
 156 void
 157 nfs_page_group_lock_wait(struct nfs_page *req)
 158 {
 159         struct nfs_page *head = req->wb_head;
 160
 161         WARN_ON_ONCE(head != head->wb_head);
 162
 163         wait_on_bit(&head->wb_flags, PG_HEADLOCK,
 164                 TASK_UNINTERRUPTIBLE);
 165 }
 166
 167 /*
 168  * nfs_page_group_unlock - unlock the head of the page group
 169  * @req - request in group that is to be unlocked
 170  */
 171 void
 172 nfs_page_group_unlock(struct nfs_page *req)
 173 {
 174         struct nfs_page *head = req->wb_head;
 175
 176         WARN_ON_ONCE(head != head->wb_head);
 177
 178         smp_mb__before_atomic();
 179         clear_bit(PG_HEADLOCK, &head->wb_flags);
 180         smp_mb__after_atomic();
 181         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
 182 }
 183
 184 /*
 185  * nfs_page_group_sync_on_bit_locked
 186  *
 187  * must be called with page group lock held
 188  */
 189 static bool
 190 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 191 {
 192         struct nfs_page *head = req->wb_head;
 193         struct nfs_page *tmp;
 194
 195         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 196         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 197
 198         tmp = req->wb_this_page;
 199         while (tmp != req) {
 200                 if (!test_bit(bit, &tmp->wb_flags))
 201                         return false;
 202                 tmp = tmp->wb_this_page;
 203         }
 204
 205         /* true! reset all bits */
 206         tmp = req;
 207         do {
 208                 clear_bit(bit, &tmp->wb_flags);
 209                 tmp = tmp->wb_this_page;
 210         } while (tmp != req);
 211
 212         return true;
 213 }
 214
 215 /*
 216  * nfs_page_group_sync_on_bit - set bit on current request, but only
 217  *   return true if the bit is set for all requests in page group
 218  * @req - request in page group
 219  * @bit - PG_* bit that is used to sync page group
 220  */
 221 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 222 {
 223         bool ret;
 224
 225         nfs_page_group_lock(req, false);
 226         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 227         nfs_page_group_unlock(req);
 228
 229         return ret;
 230 }
 231
 232 /*
 233  * nfs_page_group_init - Initialize the page group linkage for @req
 234  * @req - a new nfs request
 235  * @prev - the previous request in page group, or NULL if @req is the first
 236  *         or only request in the group (the head).
 237  */
 238 static inline void
 239 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 240 {
 241         struct inode *inode;
 242         WARN_ON_ONCE(prev == req);
 243
 244         if (!prev) {
 245                 /* a head request */
 246                 req->wb_head = req;
 247                 req->wb_this_page = req;
 248         } else {
 249                 /* a subrequest */
 250                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 251                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 252                 req->wb_head = prev->wb_head;
 253                 req->wb_this_page = prev->wb_this_page;
 254                 prev->wb_this_page = req;
 255
 256                 /* All subrequests take a ref on the head request until
 257                  * nfs_page_group_destroy is called */
 258                 kref_get(&req->wb_head->wb_kref);
 259
 260                 /* grab extra ref and bump the request count if head request
 261                  * has extra ref from the write/commit path to handle handoff
 262                  * between write and commit lists. */
 263                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 264                         inode = page_file_mapping(req->wb_page)->host;
 265                         set_bit(PG_INODE_REF, &req->wb_flags);
 266                         kref_get(&req->wb_kref);
 267                         spin_lock(&inode->i_lock);
 268                         NFS_I(inode)->nrequests++;
 269                         spin_unlock(&inode->i_lock);
 270                 }
 271         }
 272 }
 273
 274 /*
 275  * nfs_page_group_destroy - sync the destruction of page groups
 276  * @req - request that no longer needs the page group
 277  *
 278  * releases the page group reference from each member once all
 279  * members have called this function.
 280  */
 281 static void
 282 nfs_page_group_destroy(struct kref *kref)
 283 {
 284         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 285         struct nfs_page *tmp, *next;
 286
 287         /* subrequests must release the ref on the head request */
 288         if (req->wb_head != req)
 289                 nfs_release_request(req->wb_head);
 290
 291         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 292                 return;
 293
 294         tmp = req;
 295         do {
 296                 next = tmp->wb_this_page;
 297                 /* unlink and free */
 298                 tmp->wb_this_page = tmp;
 299                 tmp->wb_head = tmp;
 300                 nfs_free_request(tmp);
 301                 tmp = next;
 302         } while (tmp != req);
 303 }
 304
 305 /**
 306  * nfs_create_request - Create an NFS read/write request.
 307  * @ctx: open context to use
 308  * @page: page to write
 309  * @last: last nfs request created for this page group or NULL if head
 310  * @offset: starting offset within the page for the write
 311  * @count: number of bytes to read/write
 312  *
 313  * The page must be locked by the caller. This makes sure we never
 314  * create two different requests for the same page.
 315  * User should ensure it is safe to sleep in this function.
 316  */
 317 struct nfs_page *
 318 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 319                    struct nfs_page *last, unsigned int offset,
 320                    unsigned int count)
 321 {
 322         struct nfs_page         *req;
 323         struct nfs_lock_context *l_ctx;
 324
 325         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 326                 return ERR_PTR(-EBADF);
 327         /* try to allocate the request struct */
 328         req = nfs_page_alloc();
 329         if (req == NULL)
 330                 return ERR_PTR(-ENOMEM);
 331
 332         /* get lock context early so we can deal with alloc failures */
 333         l_ctx = nfs_get_lock_context(ctx);
 334         if (IS_ERR(l_ctx)) {
 335                 nfs_page_free(req);
 336                 return ERR_CAST(l_ctx);
 337         }
 338         req->wb_lock_context = l_ctx;
 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  = offset;
 351         req->wb_bytes   = count;
 352         req->wb_context = get_nfs_open_context(ctx);
 353         kref_init(&req->wb_kref);
 354         nfs_page_group_init(req, last);
 355         return req;
 356 }
 357
 358 /**
 359  * nfs_unlock_request - Unlock request and wake up sleepers.
 360  * @req:
 361  */
 362 void nfs_unlock_request(struct nfs_page *req)
 363 {
 364         if (!NFS_WBACK_BUSY(req)) {
 365                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 366                 BUG();
 367         }
 368         smp_mb__before_atomic();
 369         clear_bit(PG_BUSY, &req->wb_flags);
 370         smp_mb__after_atomic();
 371         wake_up_bit(&req->wb_flags, PG_BUSY);
 372 }
 373
 374 /**
 375  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 376  * @req:
 377  */
 378 void nfs_unlock_and_release_request(struct nfs_page *req)
 379 {
 380         nfs_unlock_request(req);
 381         nfs_release_request(req);
 382 }
 383
 384 /*
 385  * nfs_clear_request - Free up all resources allocated to the request
 386  * @req:
 387  *
 388  * Release page and open context resources associated with a read/write
 389  * request after it has completed.
 390  */
 391 static void nfs_clear_request(struct nfs_page *req)
 392 {
 393         struct page *page = req->wb_page;
 394         struct nfs_open_context *ctx = req->wb_context;
 395         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 396
 397         if (page != NULL) {
 398                 put_page(page);
 399                 req->wb_page = NULL;
 400         }
 401         if (l_ctx != NULL) {
 402                 if (atomic_dec_and_test(&l_ctx->io_count))
 403                         wake_up_atomic_t(&l_ctx->io_count);
 404                 nfs_put_lock_context(l_ctx);
 405                 req->wb_lock_context = NULL;
 406         }
 407         if (ctx != NULL) {
 408                 put_nfs_open_context(ctx);
 409                 req->wb_context = NULL;
 410         }
 411 }
 412
 413 /**
 414  * nfs_release_request - Release the count on an NFS read/write request
 415  * @req: request to release
 416  *
 417  * Note: Should never be called with the spinlock held!
 418  */
 419 void nfs_free_request(struct nfs_page *req)
 420 {
 421         WARN_ON_ONCE(req->wb_this_page != req);
 422
 423         /* extra debug: make sure no sync bits are still set */
 424         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 425         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 426         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 427         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 428         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 429
 430         /* Release struct file and open context */
 431         nfs_clear_request(req);
 432         nfs_page_free(req);
 433 }
 434
 435 void nfs_release_request(struct nfs_page *req)
 436 {
 437         kref_put(&req->wb_kref, nfs_page_group_destroy);
 438 }
 439
 440 /**
 441  * nfs_wait_on_request - Wait for a request to complete.
 442  * @req: request to wait upon.
 443  *
 444  * Interruptible by fatal signals only.
 445  * The user is responsible for holding a count on the request.
 446  */
 447 int
 448 nfs_wait_on_request(struct nfs_page *req)
 449 {
 450         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 451                               TASK_UNINTERRUPTIBLE);
 452 }
 453
 454 /*
 455  * nfs_generic_pg_test - determine if requests can be coalesced
 456  * @desc: pointer to descriptor
 457  * @prev: previous request in desc, or NULL
 458  * @req: this request
 459  *
 460  * Returns zero if @req can be coalesced into @desc, otherwise it returns
 461  * the size of the request.
 462  */
 463 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 464                            struct nfs_page *prev, struct nfs_page *req)
 465 {
 466         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 467
 468
 469         if (mirror->pg_count > mirror->pg_bsize) {
 470                 /* should never happen */
 471                 WARN_ON_ONCE(1);
 472                 return 0;
 473         }
 474
 475         /*
 476          * Limit the request size so that we can still allocate a page array
 477          * for it without upsetting the slab allocator.
 478          */
 479         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 480                         sizeof(struct page *) > PAGE_SIZE)
 481                 return 0;
 482
 483         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 484 }
 485 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 486
 487 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 488 {
 489         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 490
 491         if (hdr) {
 492                 INIT_LIST_HEAD(&hdr->pages);
 493                 spin_lock_init(&hdr->lock);
 494                 hdr->rw_ops = ops;
 495         }
 496         return hdr;
 497 }
 498 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 499
 500 /**
 501  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 502  *
 503  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 504  * be called again.
 505  *
 506  * @hdr: A header that has had nfs_generic_pgio called
 507  */
 508 static void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 509 {
 510         if (hdr->args.context)
 511                 put_nfs_open_context(hdr->args.context);
 512         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 513                 kfree(hdr->page_array.pagevec);
 514 }
 515
 516 /*
 517  * nfs_pgio_header_free - Free a read or write header
 518  * @hdr: The header to free
 519  */
 520 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 521 {
 522         nfs_pgio_data_destroy(hdr);
 523         hdr->rw_ops->rw_free_header(hdr);
 524 }
 525 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 526
 527 /**
 528  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 529  * @hdr: The pageio hdr
 530  * @count: Number of bytes to read
 531  * @offset: Initial offset
 532  * @how: How to commit data (writes only)
 533  * @cinfo: Commit information for the call (writes only)
 534  */
 535 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 536                               unsigned int count, unsigned int offset,
 537                               int how, struct nfs_commit_info *cinfo)
 538 {
 539         struct nfs_page *req = hdr->req;
 540
 541         /* Set up the RPC argument and reply structs
 542          * NB: take care not to mess about with hdr->commit et al. */
 543
 544         hdr->args.fh     = NFS_FH(hdr->inode);
 545         hdr->args.offset = req_offset(req) + offset;
 546         /* pnfs_set_layoutcommit needs this */
 547         hdr->mds_offset = hdr->args.offset;
 548         hdr->args.pgbase = req->wb_pgbase + offset;
 549         hdr->args.pages  = hdr->page_array.pagevec;
 550         hdr->args.count  = count;
 551         hdr->args.context = get_nfs_open_context(req->wb_context);
 552         hdr->args.lock_context = req->wb_lock_context;
 553         hdr->args.stable  = NFS_UNSTABLE;
 554         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 555         case 0:
 556                 break;
 557         case FLUSH_COND_STABLE:
 558                 if (nfs_reqs_to_commit(cinfo))
 559                         break;
 560         default:
 561                 hdr->args.stable = NFS_FILE_SYNC;
 562         }
 563
 564         hdr->res.fattr   = &hdr->fattr;
 565         hdr->res.count   = 0;
 566         hdr->res.eof     = 0;
 567         hdr->res.verf    = &hdr->verf;
 568         nfs_fattr_init(&hdr->fattr);
 569 }
 570
 571 /**
 572  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 573  * @task: The current task
 574  * @calldata: pageio header to prepare
 575  */
 576 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 577 {
 578         struct nfs_pgio_header *hdr = calldata;
 579         int err;
 580         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 581         if (err)
 582                 rpc_exit(task, err);
 583 }
 584
 585 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 586                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
 587                       const struct rpc_call_ops *call_ops, int how, int flags)
 588 {
 589         struct rpc_task *task;
 590         struct rpc_message msg = {
 591                 .rpc_argp = &hdr->args,
 592                 .rpc_resp = &hdr->res,
 593                 .rpc_cred = cred,
 594         };
 595         struct rpc_task_setup task_setup_data = {
 596                 .rpc_client = clnt,
 597                 .task = &hdr->task,
 598                 .rpc_message = &msg,
 599                 .callback_ops = call_ops,
 600                 .callback_data = hdr,
 601                 .workqueue = nfsiod_workqueue,
 602                 .flags = RPC_TASK_ASYNC | flags,
 603         };
 604         int ret = 0;
 605
 606         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 607
 608         dprintk("NFS: initiated pgio call "
 609                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 610                 hdr->inode->i_sb->s_id,
 611                 (unsigned long long)NFS_FILEID(hdr->inode),
 612                 hdr->args.count,
 613                 (unsigned long long)hdr->args.offset);
 614
 615         task = rpc_run_task(&task_setup_data);
 616         if (IS_ERR(task)) {
 617                 ret = PTR_ERR(task);
 618                 goto out;
 619         }
 620         if (how & FLUSH_SYNC) {
 621                 ret = rpc_wait_for_completion_task(task);
 622                 if (ret == 0)
 623                         ret = task->tk_status;
 624         }
 625         rpc_put_task(task);
 626 out:
 627         return ret;
 628 }
 629 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 630
 631 /**
 632  * nfs_pgio_error - Clean up from a pageio error
 633  * @desc: IO descriptor
 634  * @hdr: pageio header
 635  */
 636 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 637 {
 638         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 639         hdr->completion_ops->completion(hdr);
 640 }
 641
 642 /**
 643  * nfs_pgio_release - Release pageio data
 644  * @calldata: The pageio header to release
 645  */
 646 static void nfs_pgio_release(void *calldata)
 647 {
 648         struct nfs_pgio_header *hdr = calldata;
 649         hdr->completion_ops->completion(hdr);
 650 }
 651
 652 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 653                                    unsigned int bsize)
 654 {
 655         INIT_LIST_HEAD(&mirror->pg_list);
 656         mirror->pg_bytes_written = 0;
 657         mirror->pg_count = 0;
 658         mirror->pg_bsize = bsize;
 659         mirror->pg_base = 0;
 660         mirror->pg_recoalesce = 0;
 661 }
 662
 663 /**
 664  * nfs_pageio_init - initialise a page io descriptor
 665  * @desc: pointer to descriptor
 666  * @inode: pointer to inode
 667  * @pg_ops: pointer to pageio operations
 668  * @compl_ops: pointer to pageio completion operations
 669  * @rw_ops: pointer to nfs read/write operations
 670  * @bsize: io block size
 671  * @io_flags: extra parameters for the io function
 672  */
 673 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 674                      struct inode *inode,
 675                      const struct nfs_pageio_ops *pg_ops,
 676                      const struct nfs_pgio_completion_ops *compl_ops,
 677                      const struct nfs_rw_ops *rw_ops,
 678                      size_t bsize,
 679                      int io_flags)
 680 {
 681         struct nfs_pgio_mirror *new;
 682         int i;
 683         gfp_t gfp_flags = GFP_KERNEL;
 684
 685         desc->pg_moreio = 0;
 686         desc->pg_inode = inode;
 687         desc->pg_ops = pg_ops;
 688         desc->pg_completion_ops = compl_ops;
 689         desc->pg_rw_ops = rw_ops;
 690         desc->pg_ioflags = io_flags;
 691         desc->pg_error = 0;
 692         desc->pg_lseg = NULL;
 693         desc->pg_dreq = NULL;
 694         desc->pg_layout_private = NULL;
 695         desc->pg_bsize = bsize;
 696
 697         desc->pg_mirror_count = 1;
 698         desc->pg_mirror_idx = 0;
 699
 700         if (pg_ops->pg_get_mirror_count) {
 701                 /* until we have a request, we don't have an lseg and no
 702                  * idea how many mirrors there will be */
 703                 if (desc->pg_rw_ops->rw_mode == FMODE_WRITE)
 704                         gfp_flags = GFP_NOIO;
 705                 new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
 706                               sizeof(struct nfs_pgio_mirror), gfp_flags);
 707                 desc->pg_mirrors_dynamic = new;
 708                 desc->pg_mirrors = new;
 709
 710                 for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
 711                         nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
 712         } else {
 713                 desc->pg_mirrors_dynamic = NULL;
 714                 desc->pg_mirrors = desc->pg_mirrors_static;
 715                 nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 716         }
 717 }
 718 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 719
 720 /**
 721  * nfs_pgio_result - Basic pageio error handling
 722  * @task: The task that ran
 723  * @calldata: Pageio header to check
 724  */
 725 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 726 {
 727         struct nfs_pgio_header *hdr = calldata;
 728         struct inode *inode = hdr->inode;
 729
 730         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 731                 task->tk_pid, task->tk_status);
 732
 733         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 734                 return;
 735         if (task->tk_status < 0)
 736                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 737         else
 738                 hdr->rw_ops->rw_result(task, hdr);
 739 }
 740
 741 /*
 742  * Create an RPC task for the given read or write request and kick it.
 743  * The page must have been locked by the caller.
 744  *
 745  * It may happen that the page we're passed is not marked dirty.
 746  * This is the case if nfs_updatepage detects a conflicting request
 747  * that has been written but not committed.
 748  */
 749 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 750                      struct nfs_pgio_header *hdr)
 751 {
 752         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 753
 754         struct nfs_page         *req;
 755         struct page             **pages,
 756                                 *last_page;
 757         struct list_head *head = &mirror->pg_list;
 758         struct nfs_commit_info cinfo;
 759         unsigned int pagecount, pageused;
 760         gfp_t gfp_flags = GFP_KERNEL;
 761
 762         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 763         if (desc->pg_rw_ops->rw_mode == FMODE_WRITE)
 764                 gfp_flags = GFP_NOIO;
 765         if (!nfs_pgarray_set(&hdr->page_array, pagecount, gfp_flags)) {
 766                 nfs_pgio_error(hdr);
 767                 desc->pg_error = -ENOMEM;
 768                 return desc->pg_error;
 769         }
 770
 771         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 772         pages = hdr->page_array.pagevec;
 773         last_page = NULL;
 774         pageused = 0;
 775         while (!list_empty(head)) {
 776                 req = nfs_list_entry(head->next);
 777                 nfs_list_remove_request(req);
 778                 nfs_list_add_request(req, &hdr->pages);
 779
 780                 if (!last_page || last_page != req->wb_page) {
 781                         pageused++;
 782                         if (pageused > pagecount)
 783                                 break;
 784                         *pages++ = last_page = req->wb_page;
 785                 }
 786         }
 787         if (WARN_ON_ONCE(pageused != pagecount)) {
 788                 nfs_pgio_error(hdr);
 789                 desc->pg_error = -EINVAL;
 790                 return desc->pg_error;
 791         }
 792
 793         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 794             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 795                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 796
 797         /* Set up the argument struct */
 798         nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
 799         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 800         return 0;
 801 }
 802 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 803
 804 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 805 {
 806         struct nfs_pgio_header *hdr;
 807         int ret;
 808
 809         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 810         if (!hdr) {
 811                 desc->pg_error = -ENOMEM;
 812                 return desc->pg_error;
 813         }
 814         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 815         ret = nfs_generic_pgio(desc, hdr);
 816         if (ret == 0)
 817                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 818                                         hdr,
 819                                         hdr->cred,
 820                                         NFS_PROTO(hdr->inode),
 821                                         desc->pg_rpc_callops,
 822                                         desc->pg_ioflags, 0);
 823         return ret;
 824 }
 825
 826 /*
 827  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 828  *                              by calling the pg_get_mirror_count op
 829  */
 830 static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 831                                        struct nfs_page *req)
 832 {
 833         int mirror_count = 1;
 834
 835         if (!pgio->pg_ops->pg_get_mirror_count)
 836                 return 0;
 837
 838         mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 839
 840         if (pgio->pg_error < 0)
 841                 return pgio->pg_error;
 842
 843         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
 844                 return -EINVAL;
 845
 846         if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
 847                 return -EINVAL;
 848
 849         pgio->pg_mirror_count = mirror_count;
 850
 851         return 0;
 852 }
 853
 854 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 855 {
 856         pgio->pg_mirror_count = 1;
 857         pgio->pg_mirror_idx = 0;
 858         pgio->pg_mirrors = pgio->pg_mirrors_static;
 859         kfree(pgio->pg_mirrors_dynamic);
 860         pgio->pg_mirrors_dynamic = NULL;
 861 }
 862
 863 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 864                 const struct nfs_lock_context *l2)
 865 {
 866         return l1->lockowner.l_owner == l2->lockowner.l_owner
 867                 && l1->lockowner.l_pid == l2->lockowner.l_pid;
 868 }
 869
 870 /**
 871  * nfs_can_coalesce_requests - test two requests for compatibility
 872  * @prev: pointer to nfs_page
 873  * @req: pointer to nfs_page
 874  *
 875  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 876  * page data area they describe is contiguous, and that their RPC
 877  * credentials, NFSv4 open state, and lockowners are the same.
 878  *
 879  * Return 'true' if this is the case, else return 'false'.
 880  */
 881 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 882                                       struct nfs_page *req,
 883                                       struct nfs_pageio_descriptor *pgio)
 884 {
 885         size_t size;
 886         struct file_lock_context *flctx;
 887
 888         if (prev) {
 889                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 890                         return false;
 891                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
 892                 if (flctx != NULL &&
 893                     !(list_empty_careful(&flctx->flc_posix) &&
 894                       list_empty_careful(&flctx->flc_flock)) &&
 895                     !nfs_match_lock_context(req->wb_lock_context,
 896                                             prev->wb_lock_context))
 897                         return false;
 898                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 899                         return false;
 900                 if (req->wb_page == prev->wb_page) {
 901                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 902                                 return false;
 903                 } else {
 904                         if (req->wb_pgbase != 0 ||
 905                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 906                                 return false;
 907                 }
 908         }
 909         size = pgio->pg_ops->pg_test(pgio, prev, req);
 910         WARN_ON_ONCE(size > req->wb_bytes);
 911         if (size && size < req->wb_bytes)
 912                 req->wb_bytes = size;
 913         return size > 0;
 914 }
 915
 916 /**
 917  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 918  * @desc: destination io descriptor
 919  * @req: request
 920  *
 921  * Returns true if the request 'req' was successfully coalesced into the
 922  * existing list of pages 'desc'.
 923  */
 924 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 925                                      struct nfs_page *req)
 926 {
 927         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 928
 929         struct nfs_page *prev = NULL;
 930
 931         if (mirror->pg_count != 0) {
 932                 prev = nfs_list_entry(mirror->pg_list.prev);
 933         } else {
 934                 if (desc->pg_ops->pg_init)
 935                         desc->pg_ops->pg_init(desc, req);
 936                 if (desc->pg_error < 0)
 937                         return 0;
 938                 mirror->pg_base = req->wb_pgbase;
 939         }
 940         if (!nfs_can_coalesce_requests(prev, req, desc))
 941                 return 0;
 942         nfs_list_remove_request(req);
 943         nfs_list_add_request(req, &mirror->pg_list);
 944         mirror->pg_count += req->wb_bytes;
 945         return 1;
 946 }
 947
 948 /*
 949  * Helper for nfs_pageio_add_request and nfs_pageio_complete
 950  */
 951 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 952 {
 953         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 954
 955         if (!list_empty(&mirror->pg_list)) {
 956                 int error = desc->pg_ops->pg_doio(desc);
 957                 if (error < 0)
 958                         desc->pg_error = error;
 959                 if (list_empty(&mirror->pg_list)) {
 960                         mirror->pg_bytes_written += mirror->pg_count;
 961                         mirror->pg_count = 0;
 962                         mirror->pg_base = 0;
 963                         mirror->pg_recoalesce = 0;
 964                 }
 965         }
 966 }
 967
 968 static void
 969 nfs_pageio_cleanup_request(struct nfs_pageio_descriptor *desc,
 970                 struct nfs_page *req)
 971 {
 972         LIST_HEAD(head);
 973
 974         nfs_list_remove_request(req);
 975         nfs_list_add_request(req, &head);
 976         desc->pg_completion_ops->error_cleanup(&head);
 977 }
 978
 979 /**
 980  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
 981  * @desc: destination io descriptor
 982  * @req: request
 983  *
 984  * This may split a request into subrequests which are all part of the
 985  * same page group.
 986  *
 987  * Returns true if the request 'req' was successfully coalesced into the
 988  * existing list of pages 'desc'.
 989  */
 990 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 991                            struct nfs_page *req)
 992 {
 993         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 994
 995         struct nfs_page *subreq;
 996         unsigned int bytes_left = 0;
 997         unsigned int offset, pgbase;
 998
 999         nfs_page_group_lock(req, false);
1000
1001         subreq = req;
1002         bytes_left = subreq->wb_bytes;
1003         offset = subreq->wb_offset;
1004         pgbase = subreq->wb_pgbase;
1005
1006         do {
1007                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1008                         /* make sure pg_test call(s) did nothing */
1009                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1010                         WARN_ON_ONCE(subreq->wb_offset != offset);
1011                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1012
1013                         nfs_page_group_unlock(req);
1014                         desc->pg_moreio = 1;
1015                         nfs_pageio_doio(desc);
1016                         if (desc->pg_error < 0 || mirror->pg_recoalesce)
1017                                 goto out_cleanup_subreq;
1018                         /* retry add_request for this subreq */
1019                         nfs_page_group_lock(req, false);
1020                         continue;
1021                 }
1022
1023                 /* check for buggy pg_test call(s) */
1024                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1025                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1026                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1027
1028                 bytes_left -= subreq->wb_bytes;
1029                 offset += subreq->wb_bytes;
1030                 pgbase += subreq->wb_bytes;
1031
1032                 if (bytes_left) {
1033                         subreq = nfs_create_request(req->wb_context,
1034                                         req->wb_page,
1035                                         subreq, pgbase, bytes_left);
1036                         if (IS_ERR(subreq))
1037                                 goto err_ptr;
1038                         nfs_lock_request(subreq);
1039                         subreq->wb_offset  = offset;
1040                         subreq->wb_index = req->wb_index;
1041                 }
1042         } while (bytes_left > 0);
1043
1044         nfs_page_group_unlock(req);
1045         return 1;
1046 err_ptr:
1047         desc->pg_error = PTR_ERR(subreq);
1048         nfs_page_group_unlock(req);
1049         return 0;
1050 out_cleanup_subreq:
1051         if (req != subreq)
1052                 nfs_pageio_cleanup_request(desc, subreq);
1053         return 0;
1054 }
1055
1056 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1057 {
1058         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1059         LIST_HEAD(head);
1060
1061         do {
1062                 list_splice_init(&mirror->pg_list, &head);
1063                 mirror->pg_count = 0;
1064                 mirror->pg_base = 0;
1065                 mirror->pg_recoalesce = 0;
1066
1067                 while (!list_empty(&head)) {
1068                         struct nfs_page *req;
1069
1070                         req = list_first_entry(&head, struct nfs_page, wb_list);
1071                         if (__nfs_pageio_add_request(desc, req))
1072                                 continue;
1073                         if (desc->pg_error < 0) {
1074                                 list_splice_tail(&head, &mirror->pg_list);
1075                                 mirror->pg_recoalesce = 1;
1076                                 return 0;
1077                         }
1078                         break;
1079                 }
1080         } while (mirror->pg_recoalesce);
1081         return 1;
1082 }
1083
1084 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1085                 struct nfs_page *req)
1086 {
1087         int ret;
1088
1089         do {
1090                 ret = __nfs_pageio_add_request(desc, req);
1091                 if (ret)
1092                         break;
1093                 if (desc->pg_error < 0)
1094                         break;
1095                 ret = nfs_do_recoalesce(desc);
1096         } while (ret);
1097
1098         return ret;
1099 }
1100
1101 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1102                            struct nfs_page *req)
1103 {
1104         u32 midx;
1105         unsigned int pgbase, offset, bytes;
1106         struct nfs_page *dupreq, *lastreq;
1107
1108         pgbase = req->wb_pgbase;
1109         offset = req->wb_offset;
1110         bytes = req->wb_bytes;
1111
1112         nfs_pageio_setup_mirroring(desc, req);
1113         if (desc->pg_error < 0)
1114                 goto out_failed;
1115
1116         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1117                 if (midx) {
1118                         nfs_page_group_lock(req, false);
1119
1120                         /* find the last request */
1121                         for (lastreq = req->wb_head;
1122                              lastreq->wb_this_page != req->wb_head;
1123                              lastreq = lastreq->wb_this_page)
1124                                 ;
1125
1126                         dupreq = nfs_create_request(req->wb_context,
1127                                         req->wb_page, lastreq, pgbase, bytes);
1128
1129                         if (IS_ERR(dupreq)) {
1130                                 nfs_page_group_unlock(req);
1131                                 desc->pg_error = PTR_ERR(dupreq);
1132                                 goto out_failed;
1133                         }
1134
1135                         nfs_lock_request(dupreq);
1136                         nfs_page_group_unlock(req);
1137                         dupreq->wb_offset = offset;
1138                         dupreq->wb_index = req->wb_index;
1139                 } else
1140                         dupreq = req;
1141
1142                 if (nfs_pgio_has_mirroring(desc))
1143                         desc->pg_mirror_idx = midx;
1144                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1145                         goto out_cleanup_subreq;
1146         }
1147
1148         return 1;
1149
1150 out_cleanup_subreq:
1151         if (req != dupreq)
1152                 nfs_pageio_cleanup_request(desc, dupreq);
1153 out_failed:
1154         /*
1155          * We might have failed before sending any reqs over wire.
1156          * Clean up rest of the reqs in mirror pg_list.
1157          */
1158         if (desc->pg_error) {
1159                 struct nfs_pgio_mirror *mirror;
1160                 void (*func)(struct list_head *);
1161
1162                 /* remember fatal errors */
1163                 if (nfs_error_is_fatal(desc->pg_error))
1164                         mapping_set_error(desc->pg_inode->i_mapping,
1165                                           desc->pg_error);
1166
1167                 func = desc->pg_completion_ops->error_cleanup;
1168                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1169                         mirror = &desc->pg_mirrors[midx];
1170                         func(&mirror->pg_list);
1171                 }
1172         }
1173         return 0;
1174 }
1175
1176 /*
1177  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1178  *                              nfs_pageio_descriptor
1179  * @desc: pointer to io descriptor
1180  * @mirror_idx: pointer to mirror index
1181  */
1182 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1183                                        u32 mirror_idx)
1184 {
1185         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1186         u32 restore_idx = desc->pg_mirror_idx;
1187
1188         if (nfs_pgio_has_mirroring(desc))
1189                 desc->pg_mirror_idx = mirror_idx;
1190         for (;;) {
1191                 nfs_pageio_doio(desc);
1192                 if (desc->pg_error < 0 || !mirror->pg_recoalesce)
1193                         break;
1194                 if (!nfs_do_recoalesce(desc))
1195                         break;
1196         }
1197         desc->pg_mirror_idx = restore_idx;
1198 }
1199
1200 /*
1201  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1202  * @hdr - the pgio header to move request from
1203  * @desc - the pageio descriptor to add requests to
1204  *
1205  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1206  * to send them.
1207  *
1208  * Returns 0 on success and < 0 on error.
1209  */
1210 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1211                       struct nfs_pgio_header *hdr)
1212 {
1213         LIST_HEAD(failed);
1214
1215         desc->pg_dreq = hdr->dreq;
1216         while (!list_empty(&hdr->pages)) {
1217                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1218
1219                 nfs_list_remove_request(req);
1220                 if (!nfs_pageio_add_request(desc, req))
1221                         nfs_list_add_request(req, &failed);
1222         }
1223         nfs_pageio_complete(desc);
1224         if (!list_empty(&failed)) {
1225                 list_move(&failed, &hdr->pages);
1226                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1227         }
1228         return 0;
1229 }
1230 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1231
1232 /**
1233  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1234  * @desc: pointer to io descriptor
1235  */
1236 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1237 {
1238         u32 midx;
1239
1240         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1241                 nfs_pageio_complete_mirror(desc, midx);
1242
1243         if (desc->pg_ops->pg_cleanup)
1244                 desc->pg_ops->pg_cleanup(desc);
1245         nfs_pageio_cleanup_mirroring(desc);
1246 }
1247
1248 /**
1249  * nfs_pageio_cond_complete - Conditional I/O completion
1250  * @desc: pointer to io descriptor
1251  * @index: page index
1252  *
1253  * It is important to ensure that processes don't try to take locks
1254  * on non-contiguous ranges of pages as that might deadlock. This
1255  * function should be called before attempting to wait on a locked
1256  * nfs_page. It will complete the I/O if the page index 'index'
1257  * is not contiguous with the existing list of pages in 'desc'.
1258  */
1259 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1260 {
1261         struct nfs_pgio_mirror *mirror;
1262         struct nfs_page *prev;
1263         u32 midx;
1264
1265         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1266                 mirror = &desc->pg_mirrors[midx];
1267                 if (!list_empty(&mirror->pg_list)) {
1268                         prev = nfs_list_entry(mirror->pg_list.prev);
1269                         if (index != prev->wb_index + 1) {
1270                                 nfs_pageio_complete(desc);
1271                                 break;
1272                         }
1273                 }
1274         }
1275 }
1276
1277 /*
1278  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
1279  */
1280 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
1281 {
1282         nfs_pageio_complete(pgio);
1283 }
1284
1285 int __init nfs_init_nfspagecache(void)
1286 {
1287         nfs_page_cachep = kmem_cache_create("nfs_page",
1288                                             sizeof(struct nfs_page),
1289                                             0, SLAB_HWCACHE_ALIGN,
1290                                             NULL);
1291         if (nfs_page_cachep == NULL)
1292                 return -ENOMEM;
1293
1294         return 0;
1295 }
1296
1297 void nfs_destroy_nfspagecache(void)
1298 {
1299         kmem_cache_destroy(nfs_page_cachep);
1300 }
1301
1302 static const struct rpc_call_ops nfs_pgio_common_ops = {
1303         .rpc_call_prepare = nfs_pgio_prepare,
1304         .rpc_call_done = nfs_pgio_result,
1305         .rpc_release = nfs_pgio_release,
1306 };
1307
1308 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1309         .pg_test = nfs_generic_pg_test,
1310         .pg_doio = nfs_generic_pg_pgios,
1311 };