fs/nfs/pagelist.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/pagelist.c
   4  *
   5  * A set of helper functions for managing NFS read and write requests.
   6  * The main purpose of these routines is to provide support for the
   7  * coalescing of several requests into a single RPC call.
   8  *
   9  * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
  10  *
  11  */
  12
  13 #include <linux/slab.h>
  14 #include <linux/file.h>
  15 #include <linux/sched.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/nfs.h>
  18 #include <linux/nfs3.h>
  19 #include <linux/nfs4.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_page.h>
  22 #include <linux/nfs_mount.h>
  23 #include <linux/export.h>
  24
  25 #include "internal.h"
  26 #include "pnfs.h"
  27 #include "nfstrace.h"
  28
  29 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  30
  31 static struct kmem_cache *nfs_page_cachep;
  32 static const struct rpc_call_ops nfs_pgio_common_ops;
  33
  34 static struct nfs_pgio_mirror *
  35 nfs_pgio_get_mirror(struct nfs_pageio_descriptor *desc, u32 idx)
  36 {
  37         if (desc->pg_ops->pg_get_mirror)
  38                 return desc->pg_ops->pg_get_mirror(desc, idx);
  39         return &desc->pg_mirrors[0];
  40 }
  41
  42 struct nfs_pgio_mirror *
  43 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
  44 {
  45         return nfs_pgio_get_mirror(desc, desc->pg_mirror_idx);
  46 }
  47 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
  48
  49 static u32
  50 nfs_pgio_set_current_mirror(struct nfs_pageio_descriptor *desc, u32 idx)
  51 {
  52         if (desc->pg_ops->pg_set_mirror)
  53                 return desc->pg_ops->pg_set_mirror(desc, idx);
  54         return desc->pg_mirror_idx;
  55 }
  56
  57 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  58                        struct nfs_pgio_header *hdr,
  59                        void (*release)(struct nfs_pgio_header *hdr))
  60 {
  61         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
  62
  63
  64         hdr->req = nfs_list_entry(mirror->pg_list.next);
  65         hdr->inode = desc->pg_inode;
  66         hdr->cred = nfs_req_openctx(hdr->req)->cred;
  67         hdr->io_start = req_offset(hdr->req);
  68         hdr->good_bytes = mirror->pg_count;
  69         hdr->io_completion = desc->pg_io_completion;
  70         hdr->dreq = desc->pg_dreq;
  71         hdr->release = release;
  72         hdr->completion_ops = desc->pg_completion_ops;
  73         if (hdr->completion_ops->init_hdr)
  74                 hdr->completion_ops->init_hdr(hdr);
  75
  76         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
  77 }
  78 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
  79
  80 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
  81 {
  82         unsigned int new = pos - hdr->io_start;
  83
  84         trace_nfs_pgio_error(hdr, error, pos);
  85         if (hdr->good_bytes > new) {
  86                 hdr->good_bytes = new;
  87                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
  88                 if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags))
  89                         hdr->error = error;
  90         }
  91 }
  92
  93 static inline struct nfs_page *nfs_page_alloc(void)
  94 {
  95         struct nfs_page *p =
  96                 kmem_cache_zalloc(nfs_page_cachep, nfs_io_gfp_mask());
  97         if (p)
  98                 INIT_LIST_HEAD(&p->wb_list);
  99         return p;
 100 }
 101
 102 static inline void
 103 nfs_page_free(struct nfs_page *p)
 104 {
 105         kmem_cache_free(nfs_page_cachep, p);
 106 }
 107
 108 /**
 109  * nfs_iocounter_wait - wait for i/o to complete
 110  * @l_ctx: nfs_lock_context with io_counter to use
 111  *
 112  * returns -ERESTARTSYS if interrupted by a fatal signal.
 113  * Otherwise returns 0 once the io_count hits 0.
 114  */
 115 int
 116 nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
 117 {
 118         return wait_var_event_killable(&l_ctx->io_count,
 119                                        !atomic_read(&l_ctx->io_count));
 120 }
 121
 122 /**
 123  * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
 124  * to complete
 125  * @task: the rpc_task that should wait
 126  * @l_ctx: nfs_lock_context with io_counter to check
 127  *
 128  * Returns true if there is outstanding I/O to wait on and the
 129  * task has been put to sleep.
 130  */
 131 bool
 132 nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
 133 {
 134         struct inode *inode = d_inode(l_ctx->open_context->dentry);
 135         bool ret = false;
 136
 137         if (atomic_read(&l_ctx->io_count) > 0) {
 138                 rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
 139                 ret = true;
 140         }
 141
 142         if (atomic_read(&l_ctx->io_count) == 0) {
 143                 rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
 144                 ret = false;
 145         }
 146
 147         return ret;
 148 }
 149 EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
 150
 151 /*
 152  * nfs_page_lock_head_request - page lock the head of the page group
 153  * @req: any member of the page group
 154  */
 155 struct nfs_page *
 156 nfs_page_group_lock_head(struct nfs_page *req)
 157 {
 158         struct nfs_page *head = req->wb_head;
 159
 160         while (!nfs_lock_request(head)) {
 161                 int ret = nfs_wait_on_request(head);
 162                 if (ret < 0)
 163                         return ERR_PTR(ret);
 164         }
 165         if (head != req)
 166                 kref_get(&head->wb_kref);
 167         return head;
 168 }
 169
 170 /*
 171  * nfs_unroll_locks -  unlock all newly locked reqs and wait on @req
 172  * @head: head request of page group, must be holding head lock
 173  * @req: request that couldn't lock and needs to wait on the req bit lock
 174  *
 175  * This is a helper function for nfs_lock_and_join_requests
 176  * returns 0 on success, < 0 on error.
 177  */
 178 static void
 179 nfs_unroll_locks(struct nfs_page *head, struct nfs_page *req)
 180 {
 181         struct nfs_page *tmp;
 182
 183         /* relinquish all the locks successfully grabbed this run */
 184         for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
 185                 if (!kref_read(&tmp->wb_kref))
 186                         continue;
 187                 nfs_unlock_and_release_request(tmp);
 188         }
 189 }
 190
 191 /*
 192  * nfs_page_group_lock_subreq -  try to lock a subrequest
 193  * @head: head request of page group
 194  * @subreq: request to lock
 195  *
 196  * This is a helper function for nfs_lock_and_join_requests which
 197  * must be called with the head request and page group both locked.
 198  * On error, it returns with the page group unlocked.
 199  */
 200 static int
 201 nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq)
 202 {
 203         int ret;
 204
 205         if (!kref_get_unless_zero(&subreq->wb_kref))
 206                 return 0;
 207         while (!nfs_lock_request(subreq)) {
 208                 nfs_page_group_unlock(head);
 209                 ret = nfs_wait_on_request(subreq);
 210                 if (!ret)
 211                         ret = nfs_page_group_lock(head);
 212                 if (ret < 0) {
 213                         nfs_unroll_locks(head, subreq);
 214                         nfs_release_request(subreq);
 215                         return ret;
 216                 }
 217         }
 218         return 0;
 219 }
 220
 221 /*
 222  * nfs_page_group_lock_subrequests -  try to lock the subrequests
 223  * @head: head request of page group
 224  *
 225  * This is a helper function for nfs_lock_and_join_requests which
 226  * must be called with the head request locked.
 227  */
 228 int nfs_page_group_lock_subrequests(struct nfs_page *head)
 229 {
 230         struct nfs_page *subreq;
 231         int ret;
 232
 233         ret = nfs_page_group_lock(head);
 234         if (ret < 0)
 235                 return ret;
 236         /* lock each request in the page group */
 237         for (subreq = head->wb_this_page; subreq != head;
 238                         subreq = subreq->wb_this_page) {
 239                 ret = nfs_page_group_lock_subreq(head, subreq);
 240                 if (ret < 0)
 241                         return ret;
 242         }
 243         nfs_page_group_unlock(head);
 244         return 0;
 245 }
 246
 247 /*
 248  * nfs_page_set_headlock - set the request PG_HEADLOCK
 249  * @req: request that is to be locked
 250  *
 251  * this lock must be held when modifying req->wb_head
 252  *
 253  * return 0 on success, < 0 on error
 254  */
 255 int
 256 nfs_page_set_headlock(struct nfs_page *req)
 257 {
 258         if (!test_and_set_bit(PG_HEADLOCK, &req->wb_flags))
 259                 return 0;
 260
 261         set_bit(PG_CONTENDED1, &req->wb_flags);
 262         smp_mb__after_atomic();
 263         return wait_on_bit_lock(&req->wb_flags, PG_HEADLOCK,
 264                                 TASK_UNINTERRUPTIBLE);
 265 }
 266
 267 /*
 268  * nfs_page_clear_headlock - clear the request PG_HEADLOCK
 269  * @req: request that is to be locked
 270  */
 271 void
 272 nfs_page_clear_headlock(struct nfs_page *req)
 273 {
 274         clear_bit_unlock(PG_HEADLOCK, &req->wb_flags);
 275         smp_mb__after_atomic();
 276         if (!test_bit(PG_CONTENDED1, &req->wb_flags))
 277                 return;
 278         wake_up_bit(&req->wb_flags, PG_HEADLOCK);
 279 }
 280
 281 /*
 282  * nfs_page_group_lock - lock the head of the page group
 283  * @req: request in group that is to be locked
 284  *
 285  * this lock must be held when traversing or modifying the page
 286  * group list
 287  *
 288  * return 0 on success, < 0 on error
 289  */
 290 int
 291 nfs_page_group_lock(struct nfs_page *req)
 292 {
 293         int ret;
 294
 295         ret = nfs_page_set_headlock(req);
 296         if (ret || req->wb_head == req)
 297                 return ret;
 298         return nfs_page_set_headlock(req->wb_head);
 299 }
 300
 301 /*
 302  * nfs_page_group_unlock - unlock the head of the page group
 303  * @req: request in group that is to be unlocked
 304  */
 305 void
 306 nfs_page_group_unlock(struct nfs_page *req)
 307 {
 308         if (req != req->wb_head)
 309                 nfs_page_clear_headlock(req->wb_head);
 310         nfs_page_clear_headlock(req);
 311 }
 312
 313 /*
 314  * nfs_page_group_sync_on_bit_locked
 315  *
 316  * must be called with page group lock held
 317  */
 318 static bool
 319 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 320 {
 321         struct nfs_page *head = req->wb_head;
 322         struct nfs_page *tmp;
 323
 324         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 325         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 326
 327         tmp = req->wb_this_page;
 328         while (tmp != req) {
 329                 if (!test_bit(bit, &tmp->wb_flags))
 330                         return false;
 331                 tmp = tmp->wb_this_page;
 332         }
 333
 334         /* true! reset all bits */
 335         tmp = req;
 336         do {
 337                 clear_bit(bit, &tmp->wb_flags);
 338                 tmp = tmp->wb_this_page;
 339         } while (tmp != req);
 340
 341         return true;
 342 }
 343
 344 /*
 345  * nfs_page_group_sync_on_bit - set bit on current request, but only
 346  *   return true if the bit is set for all requests in page group
 347  * @req - request in page group
 348  * @bit - PG_* bit that is used to sync page group
 349  */
 350 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 351 {
 352         bool ret;
 353
 354         nfs_page_group_lock(req);
 355         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 356         nfs_page_group_unlock(req);
 357
 358         return ret;
 359 }
 360
 361 /*
 362  * nfs_page_group_init - Initialize the page group linkage for @req
 363  * @req - a new nfs request
 364  * @prev - the previous request in page group, or NULL if @req is the first
 365  *         or only request in the group (the head).
 366  */
 367 static inline void
 368 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 369 {
 370         struct inode *inode;
 371         WARN_ON_ONCE(prev == req);
 372
 373         if (!prev) {
 374                 /* a head request */
 375                 req->wb_head = req;
 376                 req->wb_this_page = req;
 377         } else {
 378                 /* a subrequest */
 379                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 380                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 381                 req->wb_head = prev->wb_head;
 382                 req->wb_this_page = prev->wb_this_page;
 383                 prev->wb_this_page = req;
 384
 385                 /* All subrequests take a ref on the head request until
 386                  * nfs_page_group_destroy is called */
 387                 kref_get(&req->wb_head->wb_kref);
 388
 389                 /* grab extra ref and bump the request count if head request
 390                  * has extra ref from the write/commit path to handle handoff
 391                  * between write and commit lists. */
 392                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 393                         inode = page_file_mapping(req->wb_page)->host;
 394                         set_bit(PG_INODE_REF, &req->wb_flags);
 395                         kref_get(&req->wb_kref);
 396                         atomic_long_inc(&NFS_I(inode)->nrequests);
 397                 }
 398         }
 399 }
 400
 401 /*
 402  * nfs_page_group_destroy - sync the destruction of page groups
 403  * @req - request that no longer needs the page group
 404  *
 405  * releases the page group reference from each member once all
 406  * members have called this function.
 407  */
 408 static void
 409 nfs_page_group_destroy(struct kref *kref)
 410 {
 411         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 412         struct nfs_page *head = req->wb_head;
 413         struct nfs_page *tmp, *next;
 414
 415         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 416                 goto out;
 417
 418         tmp = req;
 419         do {
 420                 next = tmp->wb_this_page;
 421                 /* unlink and free */
 422                 tmp->wb_this_page = tmp;
 423                 tmp->wb_head = tmp;
 424                 nfs_free_request(tmp);
 425                 tmp = next;
 426         } while (tmp != req);
 427 out:
 428         /* subrequests must release the ref on the head request */
 429         if (head != req)
 430                 nfs_release_request(head);
 431 }
 432
 433 static struct nfs_page *
 434 __nfs_create_request(struct nfs_lock_context *l_ctx, struct page *page,
 435                    unsigned int pgbase, unsigned int offset,
 436                    unsigned int count)
 437 {
 438         struct nfs_page         *req;
 439         struct nfs_open_context *ctx = l_ctx->open_context;
 440
 441         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 442                 return ERR_PTR(-EBADF);
 443         /* try to allocate the request struct */
 444         req = nfs_page_alloc();
 445         if (req == NULL)
 446                 return ERR_PTR(-ENOMEM);
 447
 448         req->wb_lock_context = l_ctx;
 449         refcount_inc(&l_ctx->count);
 450         atomic_inc(&l_ctx->io_count);
 451
 452         /* Initialize the request struct. Initially, we assume a
 453          * long write-back delay. This will be adjusted in
 454          * update_nfs_request below if the region is not locked. */
 455         req->wb_page    = page;
 456         if (page) {
 457                 req->wb_index = page_index(page);
 458                 get_page(page);
 459         }
 460         req->wb_offset  = offset;
 461         req->wb_pgbase  = pgbase;
 462         req->wb_bytes   = count;
 463         kref_init(&req->wb_kref);
 464         req->wb_nio = 0;
 465         return req;
 466 }
 467
 468 /**
 469  * nfs_create_request - Create an NFS read/write request.
 470  * @ctx: open context to use
 471  * @page: page to write
 472  * @offset: starting offset within the page for the write
 473  * @count: number of bytes to read/write
 474  *
 475  * The page must be locked by the caller. This makes sure we never
 476  * create two different requests for the same page.
 477  * User should ensure it is safe to sleep in this function.
 478  */
 479 struct nfs_page *
 480 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 481                    unsigned int offset, unsigned int count)
 482 {
 483         struct nfs_lock_context *l_ctx = nfs_get_lock_context(ctx);
 484         struct nfs_page *ret;
 485
 486         if (IS_ERR(l_ctx))
 487                 return ERR_CAST(l_ctx);
 488         ret = __nfs_create_request(l_ctx, page, offset, offset, count);
 489         if (!IS_ERR(ret))
 490                 nfs_page_group_init(ret, NULL);
 491         nfs_put_lock_context(l_ctx);
 492         return ret;
 493 }
 494
 495 static struct nfs_page *
 496 nfs_create_subreq(struct nfs_page *req,
 497                   unsigned int pgbase,
 498                   unsigned int offset,
 499                   unsigned int count)
 500 {
 501         struct nfs_page *last;
 502         struct nfs_page *ret;
 503
 504         ret = __nfs_create_request(req->wb_lock_context, req->wb_page,
 505                         pgbase, offset, count);
 506         if (!IS_ERR(ret)) {
 507                 /* find the last request */
 508                 for (last = req->wb_head;
 509                      last->wb_this_page != req->wb_head;
 510                      last = last->wb_this_page)
 511                         ;
 512
 513                 nfs_lock_request(ret);
 514                 ret->wb_index = req->wb_index;
 515                 nfs_page_group_init(ret, last);
 516                 ret->wb_nio = req->wb_nio;
 517         }
 518         return ret;
 519 }
 520
 521 /**
 522  * nfs_unlock_request - Unlock request and wake up sleepers.
 523  * @req: pointer to request
 524  */
 525 void nfs_unlock_request(struct nfs_page *req)
 526 {
 527         clear_bit_unlock(PG_BUSY, &req->wb_flags);
 528         smp_mb__after_atomic();
 529         if (!test_bit(PG_CONTENDED2, &req->wb_flags))
 530                 return;
 531         wake_up_bit(&req->wb_flags, PG_BUSY);
 532 }
 533
 534 /**
 535  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 536  * @req: pointer to request
 537  */
 538 void nfs_unlock_and_release_request(struct nfs_page *req)
 539 {
 540         nfs_unlock_request(req);
 541         nfs_release_request(req);
 542 }
 543
 544 /*
 545  * nfs_clear_request - Free up all resources allocated to the request
 546  * @req:
 547  *
 548  * Release page and open context resources associated with a read/write
 549  * request after it has completed.
 550  */
 551 static void nfs_clear_request(struct nfs_page *req)
 552 {
 553         struct page *page = req->wb_page;
 554         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 555         struct nfs_open_context *ctx;
 556
 557         if (page != NULL) {
 558                 put_page(page);
 559                 req->wb_page = NULL;
 560         }
 561         if (l_ctx != NULL) {
 562                 if (atomic_dec_and_test(&l_ctx->io_count)) {
 563                         wake_up_var(&l_ctx->io_count);
 564                         ctx = l_ctx->open_context;
 565                         if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
 566                                 rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
 567                 }
 568                 nfs_put_lock_context(l_ctx);
 569                 req->wb_lock_context = NULL;
 570         }
 571 }
 572
 573 /**
 574  * nfs_free_request - Release the count on an NFS read/write request
 575  * @req: request to release
 576  *
 577  * Note: Should never be called with the spinlock held!
 578  */
 579 void nfs_free_request(struct nfs_page *req)
 580 {
 581         WARN_ON_ONCE(req->wb_this_page != req);
 582
 583         /* extra debug: make sure no sync bits are still set */
 584         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 585         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 586         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 587         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 588         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 589
 590         /* Release struct file and open context */
 591         nfs_clear_request(req);
 592         nfs_page_free(req);
 593 }
 594
 595 void nfs_release_request(struct nfs_page *req)
 596 {
 597         kref_put(&req->wb_kref, nfs_page_group_destroy);
 598 }
 599 EXPORT_SYMBOL_GPL(nfs_release_request);
 600
 601 /**
 602  * nfs_wait_on_request - Wait for a request to complete.
 603  * @req: request to wait upon.
 604  *
 605  * Interruptible by fatal signals only.
 606  * The user is responsible for holding a count on the request.
 607  */
 608 int
 609 nfs_wait_on_request(struct nfs_page *req)
 610 {
 611         if (!test_bit(PG_BUSY, &req->wb_flags))
 612                 return 0;
 613         set_bit(PG_CONTENDED2, &req->wb_flags);
 614         smp_mb__after_atomic();
 615         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 616                               TASK_UNINTERRUPTIBLE);
 617 }
 618 EXPORT_SYMBOL_GPL(nfs_wait_on_request);
 619
 620 /*
 621  * nfs_generic_pg_test - determine if requests can be coalesced
 622  * @desc: pointer to descriptor
 623  * @prev: previous request in desc, or NULL
 624  * @req: this request
 625  *
 626  * Returns zero if @req cannot be coalesced into @desc, otherwise it returns
 627  * the size of the request.
 628  */
 629 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 630                            struct nfs_page *prev, struct nfs_page *req)
 631 {
 632         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 633
 634
 635         if (mirror->pg_count > mirror->pg_bsize) {
 636                 /* should never happen */
 637                 WARN_ON_ONCE(1);
 638                 return 0;
 639         }
 640
 641         /*
 642          * Limit the request size so that we can still allocate a page array
 643          * for it without upsetting the slab allocator.
 644          */
 645         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 646                         sizeof(struct page *) > PAGE_SIZE)
 647                 return 0;
 648
 649         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 650 }
 651 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 652
 653 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 654 {
 655         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 656
 657         if (hdr) {
 658                 INIT_LIST_HEAD(&hdr->pages);
 659                 hdr->rw_ops = ops;
 660         }
 661         return hdr;
 662 }
 663 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 664
 665 /**
 666  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 667  *
 668  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 669  * be called again.
 670  *
 671  * @hdr: A header that has had nfs_generic_pgio called
 672  */
 673 static void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 674 {
 675         if (hdr->args.context)
 676                 put_nfs_open_context(hdr->args.context);
 677         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 678                 kfree(hdr->page_array.pagevec);
 679 }
 680
 681 /*
 682  * nfs_pgio_header_free - Free a read or write header
 683  * @hdr: The header to free
 684  */
 685 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 686 {
 687         nfs_pgio_data_destroy(hdr);
 688         hdr->rw_ops->rw_free_header(hdr);
 689 }
 690 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 691
 692 /**
 693  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 694  * @hdr: The pageio hdr
 695  * @count: Number of bytes to read
 696  * @how: How to commit data (writes only)
 697  * @cinfo: Commit information for the call (writes only)
 698  */
 699 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 700                               unsigned int count,
 701                               int how, struct nfs_commit_info *cinfo)
 702 {
 703         struct nfs_page *req = hdr->req;
 704
 705         /* Set up the RPC argument and reply structs
 706          * NB: take care not to mess about with hdr->commit et al. */
 707
 708         hdr->args.fh     = NFS_FH(hdr->inode);
 709         hdr->args.offset = req_offset(req);
 710         /* pnfs_set_layoutcommit needs this */
 711         hdr->mds_offset = hdr->args.offset;
 712         hdr->args.pgbase = req->wb_pgbase;
 713         hdr->args.pages  = hdr->page_array.pagevec;
 714         hdr->args.count  = count;
 715         hdr->args.context = get_nfs_open_context(nfs_req_openctx(req));
 716         hdr->args.lock_context = req->wb_lock_context;
 717         hdr->args.stable  = NFS_UNSTABLE;
 718         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 719         case 0:
 720                 break;
 721         case FLUSH_COND_STABLE:
 722                 if (nfs_reqs_to_commit(cinfo))
 723                         break;
 724                 fallthrough;
 725         default:
 726                 hdr->args.stable = NFS_FILE_SYNC;
 727         }
 728
 729         hdr->res.fattr   = &hdr->fattr;
 730         hdr->res.count   = 0;
 731         hdr->res.eof     = 0;
 732         hdr->res.verf    = &hdr->verf;
 733         nfs_fattr_init(&hdr->fattr);
 734 }
 735
 736 /**
 737  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 738  * @task: The current task
 739  * @calldata: pageio header to prepare
 740  */
 741 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 742 {
 743         struct nfs_pgio_header *hdr = calldata;
 744         int err;
 745         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 746         if (err)
 747                 rpc_exit(task, err);
 748 }
 749
 750 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 751                       const struct cred *cred, const struct nfs_rpc_ops *rpc_ops,
 752                       const struct rpc_call_ops *call_ops, int how, int flags)
 753 {
 754         struct rpc_task *task;
 755         struct rpc_message msg = {
 756                 .rpc_argp = &hdr->args,
 757                 .rpc_resp = &hdr->res,
 758                 .rpc_cred = cred,
 759         };
 760         struct rpc_task_setup task_setup_data = {
 761                 .rpc_client = clnt,
 762                 .task = &hdr->task,
 763                 .rpc_message = &msg,
 764                 .callback_ops = call_ops,
 765                 .callback_data = hdr,
 766                 .workqueue = nfsiod_workqueue,
 767                 .flags = RPC_TASK_ASYNC | flags,
 768         };
 769
 770         if (nfs_server_capable(hdr->inode, NFS_CAP_MOVEABLE))
 771                 task_setup_data.flags |= RPC_TASK_MOVEABLE;
 772
 773         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 774
 775         dprintk("NFS: initiated pgio call "
 776                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 777                 hdr->inode->i_sb->s_id,
 778                 (unsigned long long)NFS_FILEID(hdr->inode),
 779                 hdr->args.count,
 780                 (unsigned long long)hdr->args.offset);
 781
 782         task = rpc_run_task(&task_setup_data);
 783         if (IS_ERR(task))
 784                 return PTR_ERR(task);
 785         rpc_put_task(task);
 786         return 0;
 787 }
 788 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 789
 790 /**
 791  * nfs_pgio_error - Clean up from a pageio error
 792  * @hdr: pageio header
 793  */
 794 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 795 {
 796         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 797         hdr->completion_ops->completion(hdr);
 798 }
 799
 800 /**
 801  * nfs_pgio_release - Release pageio data
 802  * @calldata: The pageio header to release
 803  */
 804 static void nfs_pgio_release(void *calldata)
 805 {
 806         struct nfs_pgio_header *hdr = calldata;
 807         hdr->completion_ops->completion(hdr);
 808 }
 809
 810 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 811                                    unsigned int bsize)
 812 {
 813         INIT_LIST_HEAD(&mirror->pg_list);
 814         mirror->pg_bytes_written = 0;
 815         mirror->pg_count = 0;
 816         mirror->pg_bsize = bsize;
 817         mirror->pg_base = 0;
 818         mirror->pg_recoalesce = 0;
 819 }
 820
 821 /**
 822  * nfs_pageio_init - initialise a page io descriptor
 823  * @desc: pointer to descriptor
 824  * @inode: pointer to inode
 825  * @pg_ops: pointer to pageio operations
 826  * @compl_ops: pointer to pageio completion operations
 827  * @rw_ops: pointer to nfs read/write operations
 828  * @bsize: io block size
 829  * @io_flags: extra parameters for the io function
 830  */
 831 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 832                      struct inode *inode,
 833                      const struct nfs_pageio_ops *pg_ops,
 834                      const struct nfs_pgio_completion_ops *compl_ops,
 835                      const struct nfs_rw_ops *rw_ops,
 836                      size_t bsize,
 837                      int io_flags)
 838 {
 839         desc->pg_moreio = 0;
 840         desc->pg_inode = inode;
 841         desc->pg_ops = pg_ops;
 842         desc->pg_completion_ops = compl_ops;
 843         desc->pg_rw_ops = rw_ops;
 844         desc->pg_ioflags = io_flags;
 845         desc->pg_error = 0;
 846         desc->pg_lseg = NULL;
 847         desc->pg_io_completion = NULL;
 848         desc->pg_dreq = NULL;
 849         desc->pg_bsize = bsize;
 850
 851         desc->pg_mirror_count = 1;
 852         desc->pg_mirror_idx = 0;
 853
 854         desc->pg_mirrors_dynamic = NULL;
 855         desc->pg_mirrors = desc->pg_mirrors_static;
 856         nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 857         desc->pg_maxretrans = 0;
 858 }
 859
 860 /**
 861  * nfs_pgio_result - Basic pageio error handling
 862  * @task: The task that ran
 863  * @calldata: Pageio header to check
 864  */
 865 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 866 {
 867         struct nfs_pgio_header *hdr = calldata;
 868         struct inode *inode = hdr->inode;
 869
 870         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 871                 return;
 872         if (task->tk_status < 0)
 873                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 874         else
 875                 hdr->rw_ops->rw_result(task, hdr);
 876 }
 877
 878 /*
 879  * Create an RPC task for the given read or write request and kick it.
 880  * The page must have been locked by the caller.
 881  *
 882  * It may happen that the page we're passed is not marked dirty.
 883  * This is the case if nfs_updatepage detects a conflicting request
 884  * that has been written but not committed.
 885  */
 886 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 887                      struct nfs_pgio_header *hdr)
 888 {
 889         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 890
 891         struct nfs_page         *req;
 892         struct page             **pages,
 893                                 *last_page;
 894         struct list_head *head = &mirror->pg_list;
 895         struct nfs_commit_info cinfo;
 896         struct nfs_page_array *pg_array = &hdr->page_array;
 897         unsigned int pagecount, pageused;
 898         gfp_t gfp_flags = nfs_io_gfp_mask();
 899
 900         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 901         pg_array->npages = pagecount;
 902
 903         if (pagecount <= ARRAY_SIZE(pg_array->page_array))
 904                 pg_array->pagevec = pg_array->page_array;
 905         else {
 906                 pg_array->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
 907                 if (!pg_array->pagevec) {
 908                         pg_array->npages = 0;
 909                         nfs_pgio_error(hdr);
 910                         desc->pg_error = -ENOMEM;
 911                         return desc->pg_error;
 912                 }
 913         }
 914
 915         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 916         pages = hdr->page_array.pagevec;
 917         last_page = NULL;
 918         pageused = 0;
 919         while (!list_empty(head)) {
 920                 req = nfs_list_entry(head->next);
 921                 nfs_list_move_request(req, &hdr->pages);
 922
 923                 if (!last_page || last_page != req->wb_page) {
 924                         pageused++;
 925                         if (pageused > pagecount)
 926                                 break;
 927                         *pages++ = last_page = req->wb_page;
 928                 }
 929         }
 930         if (WARN_ON_ONCE(pageused != pagecount)) {
 931                 nfs_pgio_error(hdr);
 932                 desc->pg_error = -EINVAL;
 933                 return desc->pg_error;
 934         }
 935
 936         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 937             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 938                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 939
 940         /* Set up the argument struct */
 941         nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
 942         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 943         return 0;
 944 }
 945 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 946
 947 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 948 {
 949         struct nfs_pgio_header *hdr;
 950         int ret;
 951         unsigned short task_flags = 0;
 952
 953         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 954         if (!hdr) {
 955                 desc->pg_error = -ENOMEM;
 956                 return desc->pg_error;
 957         }
 958         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 959         ret = nfs_generic_pgio(desc, hdr);
 960         if (ret == 0) {
 961                 if (NFS_SERVER(hdr->inode)->nfs_client->cl_minorversion)
 962                         task_flags = RPC_TASK_MOVEABLE;
 963                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 964                                         hdr,
 965                                         hdr->cred,
 966                                         NFS_PROTO(hdr->inode),
 967                                         desc->pg_rpc_callops,
 968                                         desc->pg_ioflags,
 969                                         RPC_TASK_CRED_NOREF | task_flags);
 970         }
 971         return ret;
 972 }
 973
 974 static struct nfs_pgio_mirror *
 975 nfs_pageio_alloc_mirrors(struct nfs_pageio_descriptor *desc,
 976                 unsigned int mirror_count)
 977 {
 978         struct nfs_pgio_mirror *ret;
 979         unsigned int i;
 980
 981         kfree(desc->pg_mirrors_dynamic);
 982         desc->pg_mirrors_dynamic = NULL;
 983         if (mirror_count == 1)
 984                 return desc->pg_mirrors_static;
 985         ret = kmalloc_array(mirror_count, sizeof(*ret), nfs_io_gfp_mask());
 986         if (ret != NULL) {
 987                 for (i = 0; i < mirror_count; i++)
 988                         nfs_pageio_mirror_init(&ret[i], desc->pg_bsize);
 989                 desc->pg_mirrors_dynamic = ret;
 990         }
 991         return ret;
 992 }
 993
 994 /*
 995  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 996  *                              by calling the pg_get_mirror_count op
 997  */
 998 static void nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 999                                        struct nfs_page *req)
1000 {
1001         unsigned int mirror_count = 1;
1002
1003         if (pgio->pg_ops->pg_get_mirror_count)
1004                 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
1005         if (mirror_count == pgio->pg_mirror_count || pgio->pg_error < 0)
1006                 return;
1007
1008         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX) {
1009                 pgio->pg_error = -EINVAL;
1010                 return;
1011         }
1012
1013         pgio->pg_mirrors = nfs_pageio_alloc_mirrors(pgio, mirror_count);
1014         if (pgio->pg_mirrors == NULL) {
1015                 pgio->pg_error = -ENOMEM;
1016                 pgio->pg_mirrors = pgio->pg_mirrors_static;
1017                 mirror_count = 1;
1018         }
1019         pgio->pg_mirror_count = mirror_count;
1020 }
1021
1022 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
1023 {
1024         pgio->pg_mirror_count = 1;
1025         pgio->pg_mirror_idx = 0;
1026         pgio->pg_mirrors = pgio->pg_mirrors_static;
1027         kfree(pgio->pg_mirrors_dynamic);
1028         pgio->pg_mirrors_dynamic = NULL;
1029 }
1030
1031 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
1032                 const struct nfs_lock_context *l2)
1033 {
1034         return l1->lockowner == l2->lockowner;
1035 }
1036
1037 /**
1038  * nfs_coalesce_size - test two requests for compatibility
1039  * @prev: pointer to nfs_page
1040  * @req: pointer to nfs_page
1041  * @pgio: pointer to nfs_pagio_descriptor
1042  *
1043  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
1044  * page data area they describe is contiguous, and that their RPC
1045  * credentials, NFSv4 open state, and lockowners are the same.
1046  *
1047  * Returns size of the request that can be coalesced
1048  */
1049 static unsigned int nfs_coalesce_size(struct nfs_page *prev,
1050                                       struct nfs_page *req,
1051                                       struct nfs_pageio_descriptor *pgio)
1052 {
1053         struct file_lock_context *flctx;
1054
1055         if (prev) {
1056                 if (!nfs_match_open_context(nfs_req_openctx(req), nfs_req_openctx(prev)))
1057                         return 0;
1058                 flctx = d_inode(nfs_req_openctx(req)->dentry)->i_flctx;
1059                 if (flctx != NULL &&
1060                     !(list_empty_careful(&flctx->flc_posix) &&
1061                       list_empty_careful(&flctx->flc_flock)) &&
1062                     !nfs_match_lock_context(req->wb_lock_context,
1063                                             prev->wb_lock_context))
1064                         return 0;
1065                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
1066                         return 0;
1067                 if (req->wb_page == prev->wb_page) {
1068                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
1069                                 return 0;
1070                 } else {
1071                         if (req->wb_pgbase != 0 ||
1072                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
1073                                 return 0;
1074                 }
1075         }
1076         return pgio->pg_ops->pg_test(pgio, prev, req);
1077 }
1078
1079 /**
1080  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
1081  * @desc: destination io descriptor
1082  * @req: request
1083  *
1084  * If the request 'req' was successfully coalesced into the existing list
1085  * of pages 'desc', it returns the size of req.
1086  */
1087 static unsigned int
1088 nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
1089                 struct nfs_page *req)
1090 {
1091         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1092         struct nfs_page *prev = NULL;
1093         unsigned int size;
1094
1095         if (list_empty(&mirror->pg_list)) {
1096                 if (desc->pg_ops->pg_init)
1097                         desc->pg_ops->pg_init(desc, req);
1098                 if (desc->pg_error < 0)
1099                         return 0;
1100                 mirror->pg_base = req->wb_pgbase;
1101                 mirror->pg_count = 0;
1102                 mirror->pg_recoalesce = 0;
1103         } else
1104                 prev = nfs_list_entry(mirror->pg_list.prev);
1105
1106         if (desc->pg_maxretrans && req->wb_nio > desc->pg_maxretrans) {
1107                 if (NFS_SERVER(desc->pg_inode)->flags & NFS_MOUNT_SOFTERR)
1108                         desc->pg_error = -ETIMEDOUT;
1109                 else
1110                         desc->pg_error = -EIO;
1111                 return 0;
1112         }
1113
1114         size = nfs_coalesce_size(prev, req, desc);
1115         if (size < req->wb_bytes)
1116                 return size;
1117         nfs_list_move_request(req, &mirror->pg_list);
1118         mirror->pg_count += req->wb_bytes;
1119         return req->wb_bytes;
1120 }
1121
1122 /*
1123  * Helper for nfs_pageio_add_request and nfs_pageio_complete
1124  */
1125 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
1126 {
1127         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1128
1129         if (!list_empty(&mirror->pg_list)) {
1130                 int error = desc->pg_ops->pg_doio(desc);
1131                 if (error < 0)
1132                         desc->pg_error = error;
1133                 if (list_empty(&mirror->pg_list))
1134                         mirror->pg_bytes_written += mirror->pg_count;
1135         }
1136 }
1137
1138 static void
1139 nfs_pageio_cleanup_request(struct nfs_pageio_descriptor *desc,
1140                 struct nfs_page *req)
1141 {
1142         LIST_HEAD(head);
1143
1144         nfs_list_move_request(req, &head);
1145         desc->pg_completion_ops->error_cleanup(&head, desc->pg_error);
1146 }
1147
1148 /**
1149  * __nfs_pageio_add_request - Attempt to coalesce a request into a page list.
1150  * @desc: destination io descriptor
1151  * @req: request
1152  *
1153  * This may split a request into subrequests which are all part of the
1154  * same page group. If so, it will submit @req as the last one, to ensure
1155  * the pointer to @req is still valid in case of failure.
1156  *
1157  * Returns true if the request 'req' was successfully coalesced into the
1158  * existing list of pages 'desc'.
1159  */
1160 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1161                            struct nfs_page *req)
1162 {
1163         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1164         struct nfs_page *subreq;
1165         unsigned int size, subreq_size;
1166
1167         nfs_page_group_lock(req);
1168
1169         subreq = req;
1170         subreq_size = subreq->wb_bytes;
1171         for(;;) {
1172                 size = nfs_pageio_do_add_request(desc, subreq);
1173                 if (size == subreq_size) {
1174                         /* We successfully submitted a request */
1175                         if (subreq == req)
1176                                 break;
1177                         req->wb_pgbase += size;
1178                         req->wb_bytes -= size;
1179                         req->wb_offset += size;
1180                         subreq_size = req->wb_bytes;
1181                         subreq = req;
1182                         continue;
1183                 }
1184                 if (WARN_ON_ONCE(subreq != req)) {
1185                         nfs_page_group_unlock(req);
1186                         nfs_pageio_cleanup_request(desc, subreq);
1187                         subreq = req;
1188                         subreq_size = req->wb_bytes;
1189                         nfs_page_group_lock(req);
1190                 }
1191                 if (!size) {
1192                         /* Can't coalesce any more, so do I/O */
1193                         nfs_page_group_unlock(req);
1194                         desc->pg_moreio = 1;
1195                         nfs_pageio_doio(desc);
1196                         if (desc->pg_error < 0 || mirror->pg_recoalesce)
1197                                 return 0;
1198                         /* retry add_request for this subreq */
1199                         nfs_page_group_lock(req);
1200                         continue;
1201                 }
1202                 subreq = nfs_create_subreq(req, req->wb_pgbase,
1203                                 req->wb_offset, size);
1204                 if (IS_ERR(subreq))
1205                         goto err_ptr;
1206                 subreq_size = size;
1207         }
1208
1209         nfs_page_group_unlock(req);
1210         return 1;
1211 err_ptr:
1212         desc->pg_error = PTR_ERR(subreq);
1213         nfs_page_group_unlock(req);
1214         return 0;
1215 }
1216
1217 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1218 {
1219         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1220         LIST_HEAD(head);
1221
1222         do {
1223                 list_splice_init(&mirror->pg_list, &head);
1224                 mirror->pg_recoalesce = 0;
1225
1226                 while (!list_empty(&head)) {
1227                         struct nfs_page *req;
1228
1229                         req = list_first_entry(&head, struct nfs_page, wb_list);
1230                         if (__nfs_pageio_add_request(desc, req))
1231                                 continue;
1232                         if (desc->pg_error < 0) {
1233                                 list_splice_tail(&head, &mirror->pg_list);
1234                                 mirror->pg_recoalesce = 1;
1235                                 return 0;
1236                         }
1237                         break;
1238                 }
1239         } while (mirror->pg_recoalesce);
1240         return 1;
1241 }
1242
1243 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1244                 struct nfs_page *req)
1245 {
1246         int ret;
1247
1248         do {
1249                 ret = __nfs_pageio_add_request(desc, req);
1250                 if (ret)
1251                         break;
1252                 if (desc->pg_error < 0)
1253                         break;
1254                 ret = nfs_do_recoalesce(desc);
1255         } while (ret);
1256
1257         return ret;
1258 }
1259
1260 static void nfs_pageio_error_cleanup(struct nfs_pageio_descriptor *desc)
1261 {
1262         u32 midx;
1263         struct nfs_pgio_mirror *mirror;
1264
1265         if (!desc->pg_error)
1266                 return;
1267
1268         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1269                 mirror = nfs_pgio_get_mirror(desc, midx);
1270                 desc->pg_completion_ops->error_cleanup(&mirror->pg_list,
1271                                 desc->pg_error);
1272         }
1273 }
1274
1275 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1276                            struct nfs_page *req)
1277 {
1278         u32 midx;
1279         unsigned int pgbase, offset, bytes;
1280         struct nfs_page *dupreq;
1281
1282         pgbase = req->wb_pgbase;
1283         offset = req->wb_offset;
1284         bytes = req->wb_bytes;
1285
1286         nfs_pageio_setup_mirroring(desc, req);
1287         if (desc->pg_error < 0)
1288                 goto out_failed;
1289
1290         /* Create the mirror instances first, and fire them off */
1291         for (midx = 1; midx < desc->pg_mirror_count; midx++) {
1292                 nfs_page_group_lock(req);
1293
1294                 dupreq = nfs_create_subreq(req,
1295                                 pgbase, offset, bytes);
1296
1297                 nfs_page_group_unlock(req);
1298                 if (IS_ERR(dupreq)) {
1299                         desc->pg_error = PTR_ERR(dupreq);
1300                         goto out_failed;
1301                 }
1302
1303                 nfs_pgio_set_current_mirror(desc, midx);
1304                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1305                         goto out_cleanup_subreq;
1306         }
1307
1308         nfs_pgio_set_current_mirror(desc, 0);
1309         if (!nfs_pageio_add_request_mirror(desc, req))
1310                 goto out_failed;
1311
1312         return 1;
1313
1314 out_cleanup_subreq:
1315         nfs_pageio_cleanup_request(desc, dupreq);
1316 out_failed:
1317         nfs_pageio_error_cleanup(desc);
1318         return 0;
1319 }
1320
1321 /*
1322  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1323  *                              nfs_pageio_descriptor
1324  * @desc: pointer to io descriptor
1325  * @mirror_idx: pointer to mirror index
1326  */
1327 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1328                                        u32 mirror_idx)
1329 {
1330         struct nfs_pgio_mirror *mirror;
1331         u32 restore_idx;
1332
1333         restore_idx = nfs_pgio_set_current_mirror(desc, mirror_idx);
1334         mirror = nfs_pgio_current_mirror(desc);
1335
1336         for (;;) {
1337                 nfs_pageio_doio(desc);
1338                 if (desc->pg_error < 0 || !mirror->pg_recoalesce)
1339                         break;
1340                 if (!nfs_do_recoalesce(desc))
1341                         break;
1342         }
1343         nfs_pgio_set_current_mirror(desc, restore_idx);
1344 }
1345
1346 /*
1347  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1348  * @hdr - the pgio header to move request from
1349  * @desc - the pageio descriptor to add requests to
1350  *
1351  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1352  * to send them.
1353  *
1354  * Returns 0 on success and < 0 on error.
1355  */
1356 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1357                       struct nfs_pgio_header *hdr)
1358 {
1359         LIST_HEAD(pages);
1360
1361         desc->pg_io_completion = hdr->io_completion;
1362         desc->pg_dreq = hdr->dreq;
1363         list_splice_init(&hdr->pages, &pages);
1364         while (!list_empty(&pages)) {
1365                 struct nfs_page *req = nfs_list_entry(pages.next);
1366
1367                 if (!nfs_pageio_add_request(desc, req))
1368                         break;
1369         }
1370         nfs_pageio_complete(desc);
1371         if (!list_empty(&pages)) {
1372                 int err = desc->pg_error < 0 ? desc->pg_error : -EIO;
1373                 hdr->completion_ops->error_cleanup(&pages, err);
1374                 nfs_set_pgio_error(hdr, err, hdr->io_start);
1375                 return err;
1376         }
1377         return 0;
1378 }
1379 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1380
1381 /**
1382  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1383  * @desc: pointer to io descriptor
1384  */
1385 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1386 {
1387         u32 midx;
1388
1389         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1390                 nfs_pageio_complete_mirror(desc, midx);
1391
1392         if (desc->pg_error < 0)
1393                 nfs_pageio_error_cleanup(desc);
1394         if (desc->pg_ops->pg_cleanup)
1395                 desc->pg_ops->pg_cleanup(desc);
1396         nfs_pageio_cleanup_mirroring(desc);
1397 }
1398
1399 /**
1400  * nfs_pageio_cond_complete - Conditional I/O completion
1401  * @desc: pointer to io descriptor
1402  * @index: page index
1403  *
1404  * It is important to ensure that processes don't try to take locks
1405  * on non-contiguous ranges of pages as that might deadlock. This
1406  * function should be called before attempting to wait on a locked
1407  * nfs_page. It will complete the I/O if the page index 'index'
1408  * is not contiguous with the existing list of pages in 'desc'.
1409  */
1410 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1411 {
1412         struct nfs_pgio_mirror *mirror;
1413         struct nfs_page *prev;
1414         u32 midx;
1415
1416         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1417                 mirror = nfs_pgio_get_mirror(desc, midx);
1418                 if (!list_empty(&mirror->pg_list)) {
1419                         prev = nfs_list_entry(mirror->pg_list.prev);
1420                         if (index != prev->wb_index + 1) {
1421                                 nfs_pageio_complete(desc);
1422                                 break;
1423                         }
1424                 }
1425         }
1426 }
1427
1428 /*
1429  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
1430  */
1431 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
1432 {
1433         nfs_pageio_complete(pgio);
1434 }
1435
1436 int __init nfs_init_nfspagecache(void)
1437 {
1438         nfs_page_cachep = kmem_cache_create("nfs_page",
1439                                             sizeof(struct nfs_page),
1440                                             0, SLAB_HWCACHE_ALIGN,
1441                                             NULL);
1442         if (nfs_page_cachep == NULL)
1443                 return -ENOMEM;
1444
1445         return 0;
1446 }
1447
1448 void nfs_destroy_nfspagecache(void)
1449 {
1450         kmem_cache_destroy(nfs_page_cachep);
1451 }
1452
1453 static const struct rpc_call_ops nfs_pgio_common_ops = {
1454         .rpc_call_prepare = nfs_pgio_prepare,
1455         .rpc_call_done = nfs_pgio_result,
1456         .rpc_release = nfs_pgio_release,
1457 };
1458
1459 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1460         .pg_test = nfs_generic_pg_test,
1461         .pg_doio = nfs_generic_pg_pgios,
1462 };