fs/nfs/write.c

   1 /*
   2  * linux/fs/nfs/write.c
   3  *
   4  * Write file data over NFS.
   5  *
   6  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/slab.h>
  11 #include <linux/mm.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/file.h>
  14 #include <linux/writeback.h>
  15 #include <linux/swap.h>
  16 #include <linux/migrate.h>
  17
  18 #include <linux/sunrpc/clnt.h>
  19 #include <linux/nfs_fs.h>
  20 #include <linux/nfs_mount.h>
  21 #include <linux/nfs_page.h>
  22 #include <linux/backing-dev.h>
  23 #include <linux/export.h>
  24 #include <linux/freezer.h>
  25 #include <linux/wait.h>
  26 #include <linux/iversion.h>
  27
  28 #include <linux/uaccess.h>
  29
  30 #include "delegation.h"
  31 #include "internal.h"
  32 #include "iostat.h"
  33 #include "nfs4_fs.h"
  34 #include "fscache.h"
  35 #include "pnfs.h"
  36
  37 #include "nfstrace.h"
  38
  39 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  40
  41 #define MIN_POOL_WRITE          (32)
  42 #define MIN_POOL_COMMIT         (4)
  43
  44 struct nfs_io_completion {
  45         void (*complete)(void *data);
  46         void *data;
  47         struct kref refcount;
  48 };
  49
  50 /*
  51  * Local function declarations
  52  */
  53 static void nfs_redirty_request(struct nfs_page *req);
  54 static const struct rpc_call_ops nfs_commit_ops;
  55 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  56 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  57 static const struct nfs_rw_ops nfs_rw_write_ops;
  58 static void nfs_clear_request_commit(struct nfs_page *req);
  59 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
  60                                       struct inode *inode);
  61 static struct nfs_page *
  62 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
  63                                                 struct page *page);
  64
  65 static struct kmem_cache *nfs_wdata_cachep;
  66 static mempool_t *nfs_wdata_mempool;
  67 static struct kmem_cache *nfs_cdata_cachep;
  68 static mempool_t *nfs_commit_mempool;
  69
  70 struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail)
  71 {
  72         struct nfs_commit_data *p;
  73
  74         if (never_fail)
  75                 p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
  76         else {
  77                 /* It is OK to do some reclaim, not no safe to wait
  78                  * for anything to be returned to the pool.
  79                  * mempool_alloc() cannot handle that particular combination,
  80                  * so we need two separate attempts.
  81                  */
  82                 p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
  83                 if (!p)
  84                         p = kmem_cache_alloc(nfs_cdata_cachep, GFP_NOIO |
  85                                              __GFP_NOWARN | __GFP_NORETRY);
  86                 if (!p)
  87                         return NULL;
  88         }
  89
  90         memset(p, 0, sizeof(*p));
  91         INIT_LIST_HEAD(&p->pages);
  92         return p;
  93 }
  94 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  95
  96 void nfs_commit_free(struct nfs_commit_data *p)
  97 {
  98         mempool_free(p, nfs_commit_mempool);
  99 }
 100 EXPORT_SYMBOL_GPL(nfs_commit_free);
 101
 102 static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 103 {
 104         struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
 105
 106         memset(p, 0, sizeof(*p));
 107         p->rw_mode = FMODE_WRITE;
 108         return p;
 109 }
 110
 111 static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 112 {
 113         mempool_free(hdr, nfs_wdata_mempool);
 114 }
 115
 116 static struct nfs_io_completion *nfs_io_completion_alloc(gfp_t gfp_flags)
 117 {
 118         return kmalloc(sizeof(struct nfs_io_completion), gfp_flags);
 119 }
 120
 121 static void nfs_io_completion_init(struct nfs_io_completion *ioc,
 122                 void (*complete)(void *), void *data)
 123 {
 124         ioc->complete = complete;
 125         ioc->data = data;
 126         kref_init(&ioc->refcount);
 127 }
 128
 129 static void nfs_io_completion_release(struct kref *kref)
 130 {
 131         struct nfs_io_completion *ioc = container_of(kref,
 132                         struct nfs_io_completion, refcount);
 133         ioc->complete(ioc->data);
 134         kfree(ioc);
 135 }
 136
 137 static void nfs_io_completion_get(struct nfs_io_completion *ioc)
 138 {
 139         if (ioc != NULL)
 140                 kref_get(&ioc->refcount);
 141 }
 142
 143 static void nfs_io_completion_put(struct nfs_io_completion *ioc)
 144 {
 145         if (ioc != NULL)
 146                 kref_put(&ioc->refcount, nfs_io_completion_release);
 147 }
 148
 149 static struct nfs_page *
 150 nfs_page_private_request(struct page *page)
 151 {
 152         if (!PagePrivate(page))
 153                 return NULL;
 154         return (struct nfs_page *)page_private(page);
 155 }
 156
 157 /*
 158  * nfs_page_find_head_request_locked - find head request associated with @page
 159  *
 160  * must be called while holding the inode lock.
 161  *
 162  * returns matching head request with reference held, or NULL if not found.
 163  */
 164 static struct nfs_page *
 165 nfs_page_find_private_request(struct page *page)
 166 {
 167         struct address_space *mapping = page_file_mapping(page);
 168         struct nfs_page *req;
 169
 170         if (!PagePrivate(page))
 171                 return NULL;
 172         spin_lock(&mapping->private_lock);
 173         req = nfs_page_private_request(page);
 174         if (req) {
 175                 WARN_ON_ONCE(req->wb_head != req);
 176                 kref_get(&req->wb_kref);
 177         }
 178         spin_unlock(&mapping->private_lock);
 179         return req;
 180 }
 181
 182 static struct nfs_page *
 183 nfs_page_find_swap_request(struct page *page)
 184 {
 185         struct inode *inode = page_file_mapping(page)->host;
 186         struct nfs_inode *nfsi = NFS_I(inode);
 187         struct nfs_page *req = NULL;
 188         if (!PageSwapCache(page))
 189                 return NULL;
 190         mutex_lock(&nfsi->commit_mutex);
 191         if (PageSwapCache(page)) {
 192                 req = nfs_page_search_commits_for_head_request_locked(nfsi,
 193                         page);
 194                 if (req) {
 195                         WARN_ON_ONCE(req->wb_head != req);
 196                         kref_get(&req->wb_kref);
 197                 }
 198         }
 199         mutex_unlock(&nfsi->commit_mutex);
 200         return req;
 201 }
 202
 203 /*
 204  * nfs_page_find_head_request - find head request associated with @page
 205  *
 206  * returns matching head request with reference held, or NULL if not found.
 207  */
 208 static struct nfs_page *nfs_page_find_head_request(struct page *page)
 209 {
 210         struct nfs_page *req;
 211
 212         req = nfs_page_find_private_request(page);
 213         if (!req)
 214                 req = nfs_page_find_swap_request(page);
 215         return req;
 216 }
 217
 218 /* Adjust the file length if we're writing beyond the end */
 219 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 220 {
 221         struct inode *inode = page_file_mapping(page)->host;
 222         loff_t end, i_size;
 223         pgoff_t end_index;
 224
 225         spin_lock(&inode->i_lock);
 226         i_size = i_size_read(inode);
 227         end_index = (i_size - 1) >> PAGE_SHIFT;
 228         if (i_size > 0 && page_index(page) < end_index)
 229                 goto out;
 230         end = page_file_offset(page) + ((loff_t)offset+count);
 231         if (i_size >= end)
 232                 goto out;
 233         i_size_write(inode, end);
 234         NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
 235         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 236 out:
 237         spin_unlock(&inode->i_lock);
 238 }
 239
 240 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 241 static void nfs_set_pageerror(struct page *page)
 242 {
 243         nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
 244 }
 245
 246 /*
 247  * nfs_page_group_search_locked
 248  * @head - head request of page group
 249  * @page_offset - offset into page
 250  *
 251  * Search page group with head @head to find a request that contains the
 252  * page offset @page_offset.
 253  *
 254  * Returns a pointer to the first matching nfs request, or NULL if no
 255  * match is found.
 256  *
 257  * Must be called with the page group lock held
 258  */
 259 static struct nfs_page *
 260 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
 261 {
 262         struct nfs_page *req;
 263
 264         req = head;
 265         do {
 266                 if (page_offset >= req->wb_pgbase &&
 267                     page_offset < (req->wb_pgbase + req->wb_bytes))
 268                         return req;
 269
 270                 req = req->wb_this_page;
 271         } while (req != head);
 272
 273         return NULL;
 274 }
 275
 276 /*
 277  * nfs_page_group_covers_page
 278  * @head - head request of page group
 279  *
 280  * Return true if the page group with head @head covers the whole page,
 281  * returns false otherwise
 282  */
 283 static bool nfs_page_group_covers_page(struct nfs_page *req)
 284 {
 285         struct nfs_page *tmp;
 286         unsigned int pos = 0;
 287         unsigned int len = nfs_page_length(req->wb_page);
 288
 289         nfs_page_group_lock(req);
 290
 291         for (;;) {
 292                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
 293                 if (!tmp)
 294                         break;
 295                 pos = tmp->wb_pgbase + tmp->wb_bytes;
 296         }
 297
 298         nfs_page_group_unlock(req);
 299         return pos >= len;
 300 }
 301
 302 /* We can set the PG_uptodate flag if we see that a write request
 303  * covers the full page.
 304  */
 305 static void nfs_mark_uptodate(struct nfs_page *req)
 306 {
 307         if (PageUptodate(req->wb_page))
 308                 return;
 309         if (!nfs_page_group_covers_page(req))
 310                 return;
 311         SetPageUptodate(req->wb_page);
 312 }
 313
 314 static int wb_priority(struct writeback_control *wbc)
 315 {
 316         int ret = 0;
 317
 318         if (wbc->sync_mode == WB_SYNC_ALL)
 319                 ret = FLUSH_COND_STABLE;
 320         return ret;
 321 }
 322
 323 /*
 324  * NFS congestion control
 325  */
 326
 327 int nfs_congestion_kb;
 328
 329 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 330 #define NFS_CONGESTION_OFF_THRESH       \
 331         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 332
 333 static void nfs_set_page_writeback(struct page *page)
 334 {
 335         struct inode *inode = page_file_mapping(page)->host;
 336         struct nfs_server *nfss = NFS_SERVER(inode);
 337         int ret = test_set_page_writeback(page);
 338
 339         WARN_ON_ONCE(ret != 0);
 340
 341         if (atomic_long_inc_return(&nfss->writeback) >
 342                         NFS_CONGESTION_ON_THRESH)
 343                 set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 344 }
 345
 346 static void nfs_end_page_writeback(struct nfs_page *req)
 347 {
 348         struct inode *inode = page_file_mapping(req->wb_page)->host;
 349         struct nfs_server *nfss = NFS_SERVER(inode);
 350         bool is_done;
 351
 352         is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
 353         nfs_unlock_request(req);
 354         if (!is_done)
 355                 return;
 356
 357         end_page_writeback(req->wb_page);
 358         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 359                 clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 360 }
 361
 362 /*
 363  * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
 364  *
 365  * this is a helper function for nfs_lock_and_join_requests
 366  *
 367  * @inode - inode associated with request page group, must be holding inode lock
 368  * @head  - head request of page group, must be holding head lock
 369  * @req   - request that couldn't lock and needs to wait on the req bit lock
 370  *
 371  * NOTE: this must be called holding page_group bit lock
 372  *       which will be released before returning.
 373  *
 374  * returns 0 on success, < 0 on error.
 375  */
 376 static void
 377 nfs_unroll_locks(struct inode *inode, struct nfs_page *head,
 378                           struct nfs_page *req)
 379 {
 380         struct nfs_page *tmp;
 381
 382         /* relinquish all the locks successfully grabbed this run */
 383         for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
 384                 if (!kref_read(&tmp->wb_kref))
 385                         continue;
 386                 nfs_unlock_and_release_request(tmp);
 387         }
 388 }
 389
 390 /*
 391  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
 392  *
 393  * @destroy_list - request list (using wb_this_page) terminated by @old_head
 394  * @old_head - the old head of the list
 395  *
 396  * All subrequests must be locked and removed from all lists, so at this point
 397  * they are only "active" in this function, and possibly in nfs_wait_on_request
 398  * with a reference held by some other context.
 399  */
 400 static void
 401 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 402                                  struct nfs_page *old_head,
 403                                  struct inode *inode)
 404 {
 405         while (destroy_list) {
 406                 struct nfs_page *subreq = destroy_list;
 407
 408                 destroy_list = (subreq->wb_this_page == old_head) ?
 409                                    NULL : subreq->wb_this_page;
 410
 411                 WARN_ON_ONCE(old_head != subreq->wb_head);
 412
 413                 /* make sure old group is not used */
 414                 subreq->wb_this_page = subreq;
 415
 416                 clear_bit(PG_REMOVE, &subreq->wb_flags);
 417
 418                 /* Note: races with nfs_page_group_destroy() */
 419                 if (!kref_read(&subreq->wb_kref)) {
 420                         /* Check if we raced with nfs_page_group_destroy() */
 421                         if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags))
 422                                 nfs_free_request(subreq);
 423                         continue;
 424                 }
 425
 426                 subreq->wb_head = subreq;
 427
 428                 if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 429                         nfs_release_request(subreq);
 430                         atomic_long_dec(&NFS_I(inode)->nrequests);
 431                 }
 432
 433                 /* subreq is now totally disconnected from page group or any
 434                  * write / commit lists. last chance to wake any waiters */
 435                 nfs_unlock_and_release_request(subreq);
 436         }
 437 }
 438
 439 /*
 440  * nfs_lock_and_join_requests - join all subreqs to the head req and return
 441  *                              a locked reference, cancelling any pending
 442  *                              operations for this page.
 443  *
 444  * @page - the page used to lookup the "page group" of nfs_page structures
 445  *
 446  * This function joins all sub requests to the head request by first
 447  * locking all requests in the group, cancelling any pending operations
 448  * and finally updating the head request to cover the whole range covered by
 449  * the (former) group.  All subrequests are removed from any write or commit
 450  * lists, unlinked from the group and destroyed.
 451  *
 452  * Returns a locked, referenced pointer to the head request - which after
 453  * this call is guaranteed to be the only request associated with the page.
 454  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
 455  * error was encountered.
 456  */
 457 static struct nfs_page *
 458 nfs_lock_and_join_requests(struct page *page)
 459 {
 460         struct inode *inode = page_file_mapping(page)->host;
 461         struct nfs_page *head, *subreq;
 462         struct nfs_page *destroy_list = NULL;
 463         unsigned int total_bytes;
 464         int ret;
 465
 466 try_again:
 467         /*
 468          * A reference is taken only on the head request which acts as a
 469          * reference to the whole page group - the group will not be destroyed
 470          * until the head reference is released.
 471          */
 472         head = nfs_page_find_head_request(page);
 473         if (!head)
 474                 return NULL;
 475
 476         /* lock the page head first in order to avoid an ABBA inefficiency */
 477         if (!nfs_lock_request(head)) {
 478                 ret = nfs_wait_on_request(head);
 479                 nfs_release_request(head);
 480                 if (ret < 0)
 481                         return ERR_PTR(ret);
 482                 goto try_again;
 483         }
 484
 485         /* Ensure that nobody removed the request before we locked it */
 486         if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {
 487                 nfs_unlock_and_release_request(head);
 488                 goto try_again;
 489         }
 490
 491         ret = nfs_page_group_lock(head);
 492         if (ret < 0)
 493                 goto release_request;
 494
 495         /* lock each request in the page group */
 496         total_bytes = head->wb_bytes;
 497         for (subreq = head->wb_this_page; subreq != head;
 498                         subreq = subreq->wb_this_page) {
 499
 500                 if (!kref_get_unless_zero(&subreq->wb_kref)) {
 501                         if (subreq->wb_offset == head->wb_offset + total_bytes)
 502                                 total_bytes += subreq->wb_bytes;
 503                         continue;
 504                 }
 505
 506                 while (!nfs_lock_request(subreq)) {
 507                         /*
 508                          * Unlock page to allow nfs_page_group_sync_on_bit()
 509                          * to succeed
 510                          */
 511                         nfs_page_group_unlock(head);
 512                         ret = nfs_wait_on_request(subreq);
 513                         if (!ret)
 514                                 ret = nfs_page_group_lock(head);
 515                         if (ret < 0) {
 516                                 nfs_unroll_locks(inode, head, subreq);
 517                                 nfs_release_request(subreq);
 518                                 goto release_request;
 519                         }
 520                 }
 521                 /*
 522                  * Subrequests are always contiguous, non overlapping
 523                  * and in order - but may be repeated (mirrored writes).
 524                  */
 525                 if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
 526                         /* keep track of how many bytes this group covers */
 527                         total_bytes += subreq->wb_bytes;
 528                 } else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
 529                             ((subreq->wb_offset + subreq->wb_bytes) >
 530                              (head->wb_offset + total_bytes)))) {
 531                         nfs_page_group_unlock(head);
 532                         nfs_unroll_locks(inode, head, subreq);
 533                         nfs_unlock_and_release_request(subreq);
 534                         ret = -EIO;
 535                         goto release_request;
 536                 }
 537         }
 538
 539         /* Now that all requests are locked, make sure they aren't on any list.
 540          * Commit list removal accounting is done after locks are dropped */
 541         subreq = head;
 542         do {
 543                 nfs_clear_request_commit(subreq);
 544                 subreq = subreq->wb_this_page;
 545         } while (subreq != head);
 546
 547         /* unlink subrequests from head, destroy them later */
 548         if (head->wb_this_page != head) {
 549                 /* destroy list will be terminated by head */
 550                 destroy_list = head->wb_this_page;
 551                 head->wb_this_page = head;
 552
 553                 /* change head request to cover whole range that
 554                  * the former page group covered */
 555                 head->wb_bytes = total_bytes;
 556         }
 557
 558         /* Postpone destruction of this request */
 559         if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) {
 560                 set_bit(PG_INODE_REF, &head->wb_flags);
 561                 kref_get(&head->wb_kref);
 562                 atomic_long_inc(&NFS_I(inode)->nrequests);
 563         }
 564
 565         nfs_page_group_unlock(head);
 566
 567         nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 568
 569         /* Did we lose a race with nfs_inode_remove_request()? */
 570         if (!(PagePrivate(page) || PageSwapCache(page))) {
 571                 nfs_unlock_and_release_request(head);
 572                 return NULL;
 573         }
 574
 575         /* still holds ref on head from nfs_page_find_head_request
 576          * and still has lock on head from lock loop */
 577         return head;
 578
 579 release_request:
 580         nfs_unlock_and_release_request(head);
 581         return ERR_PTR(ret);
 582 }
 583
 584 static void nfs_write_error_remove_page(struct nfs_page *req)
 585 {
 586         nfs_end_page_writeback(req);
 587         generic_error_remove_page(page_file_mapping(req->wb_page),
 588                                   req->wb_page);
 589         nfs_release_request(req);
 590 }
 591
 592 static bool
 593 nfs_error_is_fatal_on_server(int err)
 594 {
 595         switch (err) {
 596         case 0:
 597         case -ERESTARTSYS:
 598         case -EINTR:
 599                 return false;
 600         }
 601         return nfs_error_is_fatal(err);
 602 }
 603
 604 /*
 605  * Find an associated nfs write request, and prepare to flush it out
 606  * May return an error if the user signalled nfs_wait_on_request().
 607  */
 608 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 609                                 struct page *page)
 610 {
 611         struct nfs_page *req;
 612         int ret = 0;
 613
 614         req = nfs_lock_and_join_requests(page);
 615         if (!req)
 616                 goto out;
 617         ret = PTR_ERR(req);
 618         if (IS_ERR(req))
 619                 goto out;
 620
 621         nfs_set_page_writeback(page);
 622         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 623
 624         ret = 0;
 625         /* If there is a fatal error that covers this write, just exit */
 626         if (nfs_error_is_fatal_on_server(req->wb_context->error))
 627                 goto out_launder;
 628
 629         if (!nfs_pageio_add_request(pgio, req)) {
 630                 ret = pgio->pg_error;
 631                 /*
 632                  * Remove the problematic req upon fatal errors on the server
 633                  */
 634                 if (nfs_error_is_fatal(ret)) {
 635                         nfs_context_set_write_error(req->wb_context, ret);
 636                         if (nfs_error_is_fatal_on_server(ret))
 637                                 goto out_launder;
 638                 }
 639                 nfs_redirty_request(req);
 640                 ret = -EAGAIN;
 641         } else
 642                 nfs_add_stats(page_file_mapping(page)->host,
 643                                 NFSIOS_WRITEPAGES, 1);
 644 out:
 645         return ret;
 646 out_launder:
 647         nfs_write_error_remove_page(req);
 648         return ret;
 649 }
 650
 651 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
 652                             struct nfs_pageio_descriptor *pgio)
 653 {
 654         int ret;
 655
 656         nfs_pageio_cond_complete(pgio, page_index(page));
 657         ret = nfs_page_async_flush(pgio, page);
 658         if (ret == -EAGAIN) {
 659                 redirty_page_for_writepage(wbc, page);
 660                 ret = 0;
 661         }
 662         return ret;
 663 }
 664
 665 /*
 666  * Write an mmapped page to the server.
 667  */
 668 static int nfs_writepage_locked(struct page *page,
 669                                 struct writeback_control *wbc)
 670 {
 671         struct nfs_pageio_descriptor pgio;
 672         struct inode *inode = page_file_mapping(page)->host;
 673         int err;
 674
 675         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 676         nfs_pageio_init_write(&pgio, inode, 0,
 677                                 false, &nfs_async_write_completion_ops);
 678         err = nfs_do_writepage(page, wbc, &pgio);
 679         nfs_pageio_complete(&pgio);
 680         if (err < 0)
 681                 return err;
 682         if (pgio.pg_error < 0)
 683                 return pgio.pg_error;
 684         return 0;
 685 }
 686
 687 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 688 {
 689         int ret;
 690
 691         ret = nfs_writepage_locked(page, wbc);
 692         unlock_page(page);
 693         return ret;
 694 }
 695
 696 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 697 {
 698         int ret;
 699
 700         ret = nfs_do_writepage(page, wbc, data);
 701         unlock_page(page);
 702         return ret;
 703 }
 704
 705 static void nfs_io_completion_commit(void *inode)
 706 {
 707         nfs_commit_inode(inode, 0);
 708 }
 709
 710 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 711 {
 712         struct inode *inode = mapping->host;
 713         struct nfs_pageio_descriptor pgio;
 714         struct nfs_io_completion *ioc = nfs_io_completion_alloc(GFP_NOFS);
 715         int err;
 716
 717         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 718
 719         if (ioc)
 720                 nfs_io_completion_init(ioc, nfs_io_completion_commit, inode);
 721
 722         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc), false,
 723                                 &nfs_async_write_completion_ops);
 724         pgio.pg_io_completion = ioc;
 725         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 726         nfs_pageio_complete(&pgio);
 727         nfs_io_completion_put(ioc);
 728
 729         if (err < 0)
 730                 goto out_err;
 731         err = pgio.pg_error;
 732         if (err < 0)
 733                 goto out_err;
 734         return 0;
 735 out_err:
 736         return err;
 737 }
 738
 739 /*
 740  * Insert a write request into an inode
 741  */
 742 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 743 {
 744         struct address_space *mapping = page_file_mapping(req->wb_page);
 745         struct nfs_inode *nfsi = NFS_I(inode);
 746
 747         WARN_ON_ONCE(req->wb_this_page != req);
 748
 749         /* Lock the request! */
 750         nfs_lock_request(req);
 751
 752         /*
 753          * Swap-space should not get truncated. Hence no need to plug the race
 754          * with invalidate/truncate.
 755          */
 756         spin_lock(&mapping->private_lock);
 757         if (!nfs_have_writebacks(inode) &&
 758             NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 759                 inode_inc_iversion_raw(inode);
 760         if (likely(!PageSwapCache(req->wb_page))) {
 761                 set_bit(PG_MAPPED, &req->wb_flags);
 762                 SetPagePrivate(req->wb_page);
 763                 set_page_private(req->wb_page, (unsigned long)req);
 764         }
 765         spin_unlock(&mapping->private_lock);
 766         atomic_long_inc(&nfsi->nrequests);
 767         /* this a head request for a page group - mark it as having an
 768          * extra reference so sub groups can follow suit.
 769          * This flag also informs pgio layer when to bump nrequests when
 770          * adding subrequests. */
 771         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 772         kref_get(&req->wb_kref);
 773 }
 774
 775 /*
 776  * Remove a write request from an inode
 777  */
 778 static void nfs_inode_remove_request(struct nfs_page *req)
 779 {
 780         struct address_space *mapping = page_file_mapping(req->wb_page);
 781         struct inode *inode = mapping->host;
 782         struct nfs_inode *nfsi = NFS_I(inode);
 783         struct nfs_page *head;
 784
 785         atomic_long_dec(&nfsi->nrequests);
 786         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
 787                 head = req->wb_head;
 788
 789                 spin_lock(&mapping->private_lock);
 790                 if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
 791                         set_page_private(head->wb_page, 0);
 792                         ClearPagePrivate(head->wb_page);
 793                         clear_bit(PG_MAPPED, &head->wb_flags);
 794                 }
 795                 spin_unlock(&mapping->private_lock);
 796         }
 797
 798         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))
 799                 nfs_release_request(req);
 800 }
 801
 802 static void
 803 nfs_mark_request_dirty(struct nfs_page *req)
 804 {
 805         if (req->wb_page)
 806                 __set_page_dirty_nobuffers(req->wb_page);
 807 }
 808
 809 /*
 810  * nfs_page_search_commits_for_head_request_locked
 811  *
 812  * Search through commit lists on @inode for the head request for @page.
 813  * Must be called while holding the inode (which is cinfo) lock.
 814  *
 815  * Returns the head request if found, or NULL if not found.
 816  */
 817 static struct nfs_page *
 818 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 819                                                 struct page *page)
 820 {
 821         struct nfs_page *freq, *t;
 822         struct nfs_commit_info cinfo;
 823         struct inode *inode = &nfsi->vfs_inode;
 824
 825         nfs_init_cinfo_from_inode(&cinfo, inode);
 826
 827         /* search through pnfs commit lists */
 828         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
 829         if (freq)
 830                 return freq->wb_head;
 831
 832         /* Linearly search the commit list for the correct request */
 833         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
 834                 if (freq->wb_page == page)
 835                         return freq->wb_head;
 836         }
 837
 838         return NULL;
 839 }
 840
 841 /**
 842  * nfs_request_add_commit_list_locked - add request to a commit list
 843  * @req: pointer to a struct nfs_page
 844  * @dst: commit list head
 845  * @cinfo: holds list lock and accounting info
 846  *
 847  * This sets the PG_CLEAN bit, updates the cinfo count of
 848  * number of outstanding requests requiring a commit as well as
 849  * the MM page stats.
 850  *
 851  * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
 852  * nfs_page lock.
 853  */
 854 void
 855 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
 856                             struct nfs_commit_info *cinfo)
 857 {
 858         set_bit(PG_CLEAN, &req->wb_flags);
 859         nfs_list_add_request(req, dst);
 860         atomic_long_inc(&cinfo->mds->ncommit);
 861 }
 862 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 863
 864 /**
 865  * nfs_request_add_commit_list - add request to a commit list
 866  * @req: pointer to a struct nfs_page
 867  * @dst: commit list head
 868  * @cinfo: holds list lock and accounting info
 869  *
 870  * This sets the PG_CLEAN bit, updates the cinfo count of
 871  * number of outstanding requests requiring a commit as well as
 872  * the MM page stats.
 873  *
 874  * The caller must _not_ hold the cinfo->lock, but must be
 875  * holding the nfs_page lock.
 876  */
 877 void
 878 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 879 {
 880         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 881         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
 882         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 883         if (req->wb_page)
 884                 nfs_mark_page_unstable(req->wb_page, cinfo);
 885 }
 886 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 887
 888 /**
 889  * nfs_request_remove_commit_list - Remove request from a commit list
 890  * @req: pointer to a nfs_page
 891  * @cinfo: holds list lock and accounting info
 892  *
 893  * This clears the PG_CLEAN bit, and updates the cinfo's count of
 894  * number of outstanding requests requiring a commit
 895  * It does not update the MM page stats.
 896  *
 897  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 898  */
 899 void
 900 nfs_request_remove_commit_list(struct nfs_page *req,
 901                                struct nfs_commit_info *cinfo)
 902 {
 903         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 904                 return;
 905         nfs_list_remove_request(req);
 906         atomic_long_dec(&cinfo->mds->ncommit);
 907 }
 908 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 909
 910 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 911                                       struct inode *inode)
 912 {
 913         cinfo->inode = inode;
 914         cinfo->mds = &NFS_I(inode)->commit_info;
 915         cinfo->ds = pnfs_get_ds_info(inode);
 916         cinfo->dreq = NULL;
 917         cinfo->completion_ops = &nfs_commit_completion_ops;
 918 }
 919
 920 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 921                     struct inode *inode,
 922                     struct nfs_direct_req *dreq)
 923 {
 924         if (dreq)
 925                 nfs_init_cinfo_from_dreq(cinfo, dreq);
 926         else
 927                 nfs_init_cinfo_from_inode(cinfo, inode);
 928 }
 929 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 930
 931 /*
 932  * Add a request to the inode's commit list.
 933  */
 934 void
 935 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 936                         struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 937 {
 938         if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 939                 return;
 940         nfs_request_add_commit_list(req, cinfo);
 941 }
 942
 943 static void
 944 nfs_clear_page_commit(struct page *page)
 945 {
 946         dec_node_page_state(page, NR_UNSTABLE_NFS);
 947         dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
 948                     WB_RECLAIMABLE);
 949 }
 950
 951 /* Called holding the request lock on @req */
 952 static void
 953 nfs_clear_request_commit(struct nfs_page *req)
 954 {
 955         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 956                 struct inode *inode = d_inode(req->wb_context->dentry);
 957                 struct nfs_commit_info cinfo;
 958
 959                 nfs_init_cinfo_from_inode(&cinfo, inode);
 960                 mutex_lock(&NFS_I(inode)->commit_mutex);
 961                 if (!pnfs_clear_request_commit(req, &cinfo)) {
 962                         nfs_request_remove_commit_list(req, &cinfo);
 963                 }
 964                 mutex_unlock(&NFS_I(inode)->commit_mutex);
 965                 nfs_clear_page_commit(req->wb_page);
 966         }
 967 }
 968
 969 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 970 {
 971         if (hdr->verf.committed == NFS_DATA_SYNC)
 972                 return hdr->lseg == NULL;
 973         return hdr->verf.committed != NFS_FILE_SYNC;
 974 }
 975
 976 static void nfs_async_write_init(struct nfs_pgio_header *hdr)
 977 {
 978         nfs_io_completion_get(hdr->io_completion);
 979 }
 980
 981 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 982 {
 983         struct nfs_commit_info cinfo;
 984         unsigned long bytes = 0;
 985
 986         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 987                 goto out;
 988         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
 989         while (!list_empty(&hdr->pages)) {
 990                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 991
 992                 bytes += req->wb_bytes;
 993                 nfs_list_remove_request(req);
 994                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
 995                     (hdr->good_bytes < bytes)) {
 996                         nfs_set_pageerror(req->wb_page);
 997                         nfs_context_set_write_error(req->wb_context, hdr->error);
 998                         goto remove_req;
 999                 }
1000                 if (nfs_write_need_commit(hdr)) {
1001                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1002                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1003                                 hdr->pgio_mirror_idx);
1004                         goto next;
1005                 }
1006 remove_req:
1007                 nfs_inode_remove_request(req);
1008 next:
1009                 nfs_end_page_writeback(req);
1010                 nfs_release_request(req);
1011         }
1012 out:
1013         nfs_io_completion_put(hdr->io_completion);
1014         hdr->release(hdr);
1015 }
1016
1017 unsigned long
1018 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1019 {
1020         return atomic_long_read(&cinfo->mds->ncommit);
1021 }
1022
1023 /* NFS_I(cinfo->inode)->commit_mutex held by caller */
1024 int
1025 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1026                      struct nfs_commit_info *cinfo, int max)
1027 {
1028         struct nfs_page *req, *tmp;
1029         int ret = 0;
1030
1031 restart:
1032         list_for_each_entry_safe(req, tmp, src, wb_list) {
1033                 kref_get(&req->wb_kref);
1034                 if (!nfs_lock_request(req)) {
1035                         int status;
1036
1037                         /* Prevent deadlock with nfs_lock_and_join_requests */
1038                         if (!list_empty(dst)) {
1039                                 nfs_release_request(req);
1040                                 continue;
1041                         }
1042                         /* Ensure we make progress to prevent livelock */
1043                         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1044                         status = nfs_wait_on_request(req);
1045                         nfs_release_request(req);
1046                         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1047                         if (status < 0)
1048                                 break;
1049                         goto restart;
1050                 }
1051                 nfs_request_remove_commit_list(req, cinfo);
1052                 clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1053                 nfs_list_add_request(req, dst);
1054                 ret++;
1055                 if ((ret == max) && !cinfo->dreq)
1056                         break;
1057                 cond_resched();
1058         }
1059         return ret;
1060 }
1061 EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1062
1063 /*
1064  * nfs_scan_commit - Scan an inode for commit requests
1065  * @inode: NFS inode to scan
1066  * @dst: mds destination list
1067  * @cinfo: mds and ds lists of reqs ready to commit
1068  *
1069  * Moves requests from the inode's 'commit' request list.
1070  * The requests are *not* checked to ensure that they form a contiguous set.
1071  */
1072 int
1073 nfs_scan_commit(struct inode *inode, struct list_head *dst,
1074                 struct nfs_commit_info *cinfo)
1075 {
1076         int ret = 0;
1077
1078         if (!atomic_long_read(&cinfo->mds->ncommit))
1079                 return 0;
1080         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1081         if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1082                 const int max = INT_MAX;
1083
1084                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1085                                            cinfo, max);
1086                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1087         }
1088         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1089         return ret;
1090 }
1091
1092 /*
1093  * Search for an existing write request, and attempt to update
1094  * it to reflect a new dirty region on a given page.
1095  *
1096  * If the attempt fails, then the existing request is flushed out
1097  * to disk.
1098  */
1099 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1100                 struct page *page,
1101                 unsigned int offset,
1102                 unsigned int bytes)
1103 {
1104         struct nfs_page *req;
1105         unsigned int rqend;
1106         unsigned int end;
1107         int error;
1108
1109         end = offset + bytes;
1110
1111         req = nfs_lock_and_join_requests(page);
1112         if (IS_ERR_OR_NULL(req))
1113                 return req;
1114
1115         rqend = req->wb_offset + req->wb_bytes;
1116         /*
1117          * Tell the caller to flush out the request if
1118          * the offsets are non-contiguous.
1119          * Note: nfs_flush_incompatible() will already
1120          * have flushed out requests having wrong owners.
1121          */
1122         if (offset > rqend || end < req->wb_offset)
1123                 goto out_flushme;
1124
1125         /* Okay, the request matches. Update the region */
1126         if (offset < req->wb_offset) {
1127                 req->wb_offset = offset;
1128                 req->wb_pgbase = offset;
1129         }
1130         if (end > rqend)
1131                 req->wb_bytes = end - req->wb_offset;
1132         else
1133                 req->wb_bytes = rqend - req->wb_offset;
1134         return req;
1135 out_flushme:
1136         /*
1137          * Note: we mark the request dirty here because
1138          * nfs_lock_and_join_requests() cannot preserve
1139          * commit flags, so we have to replay the write.
1140          */
1141         nfs_mark_request_dirty(req);
1142         nfs_unlock_and_release_request(req);
1143         error = nfs_wb_page(inode, page);
1144         return (error < 0) ? ERR_PTR(error) : NULL;
1145 }
1146
1147 /*
1148  * Try to update an existing write request, or create one if there is none.
1149  *
1150  * Note: Should always be called with the Page Lock held to prevent races
1151  * if we have to add a new request. Also assumes that the caller has
1152  * already called nfs_flush_incompatible() if necessary.
1153  */
1154 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1155                 struct page *page, unsigned int offset, unsigned int bytes)
1156 {
1157         struct inode *inode = page_file_mapping(page)->host;
1158         struct nfs_page *req;
1159
1160         req = nfs_try_to_update_request(inode, page, offset, bytes);
1161         if (req != NULL)
1162                 goto out;
1163         req = nfs_create_request(ctx, page, NULL, offset, bytes);
1164         if (IS_ERR(req))
1165                 goto out;
1166         nfs_inode_add_request(inode, req);
1167 out:
1168         return req;
1169 }
1170
1171 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1172                 unsigned int offset, unsigned int count)
1173 {
1174         struct nfs_page *req;
1175
1176         req = nfs_setup_write_request(ctx, page, offset, count);
1177         if (IS_ERR(req))
1178                 return PTR_ERR(req);
1179         /* Update file length */
1180         nfs_grow_file(page, offset, count);
1181         nfs_mark_uptodate(req);
1182         nfs_mark_request_dirty(req);
1183         nfs_unlock_and_release_request(req);
1184         return 0;
1185 }
1186
1187 int nfs_flush_incompatible(struct file *file, struct page *page)
1188 {
1189         struct nfs_open_context *ctx = nfs_file_open_context(file);
1190         struct nfs_lock_context *l_ctx;
1191         struct file_lock_context *flctx = file_inode(file)->i_flctx;
1192         struct nfs_page *req;
1193         int do_flush, status;
1194         /*
1195          * Look for a request corresponding to this page. If there
1196          * is one, and it belongs to another file, we flush it out
1197          * before we try to copy anything into the page. Do this
1198          * due to the lack of an ACCESS-type call in NFSv2.
1199          * Also do the same if we find a request from an existing
1200          * dropped page.
1201          */
1202         do {
1203                 req = nfs_page_find_head_request(page);
1204                 if (req == NULL)
1205                         return 0;
1206                 l_ctx = req->wb_lock_context;
1207                 do_flush = req->wb_page != page ||
1208                         !nfs_match_open_context(req->wb_context, ctx);
1209                 if (l_ctx && flctx &&
1210                     !(list_empty_careful(&flctx->flc_posix) &&
1211                       list_empty_careful(&flctx->flc_flock))) {
1212                         do_flush |= l_ctx->lockowner != current->files;
1213                 }
1214                 nfs_release_request(req);
1215                 if (!do_flush)
1216                         return 0;
1217                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1218         } while (status == 0);
1219         return status;
1220 }
1221
1222 /*
1223  * Avoid buffered writes when a open context credential's key would
1224  * expire soon.
1225  *
1226  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1227  *
1228  * Return 0 and set a credential flag which triggers the inode to flush
1229  * and performs  NFS_FILE_SYNC writes if the key will expired within
1230  * RPC_KEY_EXPIRE_TIMEO.
1231  */
1232 int
1233 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1234 {
1235         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1236         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1237
1238         return rpcauth_key_timeout_notify(auth, ctx->cred);
1239 }
1240
1241 /*
1242  * Test if the open context credential key is marked to expire soon.
1243  */
1244 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1245 {
1246         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1247
1248         return rpcauth_cred_key_to_expire(auth, ctx->cred);
1249 }
1250
1251 /*
1252  * If the page cache is marked as unsafe or invalid, then we can't rely on
1253  * the PageUptodate() flag. In this case, we will need to turn off
1254  * write optimisations that depend on the page contents being correct.
1255  */
1256 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
1257 {
1258         struct nfs_inode *nfsi = NFS_I(inode);
1259
1260         if (nfs_have_delegated_attributes(inode))
1261                 goto out;
1262         if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
1263                 return false;
1264         smp_rmb();
1265         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
1266                 return false;
1267 out:
1268         if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
1269                 return false;
1270         return PageUptodate(page) != 0;
1271 }
1272
1273 static bool
1274 is_whole_file_wrlock(struct file_lock *fl)
1275 {
1276         return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1277                         fl->fl_type == F_WRLCK;
1278 }
1279
1280 /* If we know the page is up to date, and we're not using byte range locks (or
1281  * if we have the whole file locked for writing), it may be more efficient to
1282  * extend the write to cover the entire page in order to avoid fragmentation
1283  * inefficiencies.
1284  *
1285  * If the file is opened for synchronous writes then we can just skip the rest
1286  * of the checks.
1287  */
1288 static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
1289 {
1290         int ret;
1291         struct file_lock_context *flctx = inode->i_flctx;
1292         struct file_lock *fl;
1293
1294         if (file->f_flags & O_DSYNC)
1295                 return 0;
1296         if (!nfs_write_pageuptodate(page, inode))
1297                 return 0;
1298         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1299                 return 1;
1300         if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1301                        list_empty_careful(&flctx->flc_posix)))
1302                 return 1;
1303
1304         /* Check to see if there are whole file write locks */
1305         ret = 0;
1306         spin_lock(&flctx->flc_lock);
1307         if (!list_empty(&flctx->flc_posix)) {
1308                 fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1309                                         fl_list);
1310                 if (is_whole_file_wrlock(fl))
1311                         ret = 1;
1312         } else if (!list_empty(&flctx->flc_flock)) {
1313                 fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1314                                         fl_list);
1315                 if (fl->fl_type == F_WRLCK)
1316                         ret = 1;
1317         }
1318         spin_unlock(&flctx->flc_lock);
1319         return ret;
1320 }
1321
1322 /*
1323  * Update and possibly write a cached page of an NFS file.
1324  *
1325  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1326  * things with a page scheduled for an RPC call (e.g. invalidate it).
1327  */
1328 int nfs_updatepage(struct file *file, struct page *page,
1329                 unsigned int offset, unsigned int count)
1330 {
1331         struct nfs_open_context *ctx = nfs_file_open_context(file);
1332         struct inode    *inode = page_file_mapping(page)->host;
1333         int             status = 0;
1334
1335         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1336
1337         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1338                 file, count, (long long)(page_file_offset(page) + offset));
1339
1340         if (!count)
1341                 goto out;
1342
1343         if (nfs_can_extend_write(file, page, inode)) {
1344                 count = max(count + offset, nfs_page_length(page));
1345                 offset = 0;
1346         }
1347
1348         status = nfs_writepage_setup(ctx, page, offset, count);
1349         if (status < 0)
1350                 nfs_set_pageerror(page);
1351         else
1352                 __set_page_dirty_nobuffers(page);
1353 out:
1354         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1355                         status, (long long)i_size_read(inode));
1356         return status;
1357 }
1358
1359 static int flush_task_priority(int how)
1360 {
1361         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1362                 case FLUSH_HIGHPRI:
1363                         return RPC_PRIORITY_HIGH;
1364                 case FLUSH_LOWPRI:
1365                         return RPC_PRIORITY_LOW;
1366         }
1367         return RPC_PRIORITY_NORMAL;
1368 }
1369
1370 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1371                                struct rpc_message *msg,
1372                                const struct nfs_rpc_ops *rpc_ops,
1373                                struct rpc_task_setup *task_setup_data, int how)
1374 {
1375         int priority = flush_task_priority(how);
1376
1377         task_setup_data->priority = priority;
1378         rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1379         trace_nfs_initiate_write(hdr->inode, hdr->io_start, hdr->good_bytes,
1380                                  hdr->args.stable);
1381 }
1382
1383 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1384  * call this on each, which will prepare them to be retried on next
1385  * writeback using standard nfs.
1386  */
1387 static void nfs_redirty_request(struct nfs_page *req)
1388 {
1389         nfs_mark_request_dirty(req);
1390         set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1391         nfs_end_page_writeback(req);
1392         nfs_release_request(req);
1393 }
1394
1395 static void nfs_async_write_error(struct list_head *head)
1396 {
1397         struct nfs_page *req;
1398
1399         while (!list_empty(head)) {
1400                 req = nfs_list_entry(head->next);
1401                 nfs_list_remove_request(req);
1402                 nfs_redirty_request(req);
1403         }
1404 }
1405
1406 static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1407 {
1408         nfs_async_write_error(&hdr->pages);
1409         filemap_fdatawrite_range(hdr->inode->i_mapping, hdr->args.offset,
1410                         hdr->args.offset + hdr->args.count - 1);
1411 }
1412
1413 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1414         .init_hdr = nfs_async_write_init,
1415         .error_cleanup = nfs_async_write_error,
1416         .completion = nfs_write_completion,
1417         .reschedule_io = nfs_async_write_reschedule_io,
1418 };
1419
1420 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1421                                struct inode *inode, int ioflags, bool force_mds,
1422                                const struct nfs_pgio_completion_ops *compl_ops)
1423 {
1424         struct nfs_server *server = NFS_SERVER(inode);
1425         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1426
1427 #ifdef CONFIG_NFS_V4_1
1428         if (server->pnfs_curr_ld && !force_mds)
1429                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1430 #endif
1431         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1432                         server->wsize, ioflags);
1433 }
1434 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1435
1436 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1437 {
1438         struct nfs_pgio_mirror *mirror;
1439
1440         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1441                 pgio->pg_ops->pg_cleanup(pgio);
1442
1443         pgio->pg_ops = &nfs_pgio_rw_ops;
1444
1445         nfs_pageio_stop_mirroring(pgio);
1446
1447         mirror = &pgio->pg_mirrors[0];
1448         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1449 }
1450 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1451
1452
1453 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1454 {
1455         struct nfs_commit_data *data = calldata;
1456
1457         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1458 }
1459
1460 /*
1461  * Special version of should_remove_suid() that ignores capabilities.
1462  */
1463 static int nfs_should_remove_suid(const struct inode *inode)
1464 {
1465         umode_t mode = inode->i_mode;
1466         int kill = 0;
1467
1468         /* suid always must be killed */
1469         if (unlikely(mode & S_ISUID))
1470                 kill = ATTR_KILL_SUID;
1471
1472         /*
1473          * sgid without any exec bits is just a mandatory locking mark; leave
1474          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1475          */
1476         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1477                 kill |= ATTR_KILL_SGID;
1478
1479         if (unlikely(kill && S_ISREG(mode)))
1480                 return kill;
1481
1482         return 0;
1483 }
1484
1485 static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1486                 struct nfs_fattr *fattr)
1487 {
1488         struct nfs_pgio_args *argp = &hdr->args;
1489         struct nfs_pgio_res *resp = &hdr->res;
1490         u64 size = argp->offset + resp->count;
1491
1492         if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1493                 fattr->size = size;
1494         if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1495                 fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1496                 return;
1497         }
1498         if (size != fattr->size)
1499                 return;
1500         /* Set attribute barrier */
1501         nfs_fattr_set_barrier(fattr);
1502         /* ...and update size */
1503         fattr->valid |= NFS_ATTR_FATTR_SIZE;
1504 }
1505
1506 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1507 {
1508         struct nfs_fattr *fattr = &hdr->fattr;
1509         struct inode *inode = hdr->inode;
1510
1511         spin_lock(&inode->i_lock);
1512         nfs_writeback_check_extend(hdr, fattr);
1513         nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1514         spin_unlock(&inode->i_lock);
1515 }
1516 EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1517
1518 /*
1519  * This function is called when the WRITE call is complete.
1520  */
1521 static int nfs_writeback_done(struct rpc_task *task,
1522                               struct nfs_pgio_header *hdr,
1523                               struct inode *inode)
1524 {
1525         int status;
1526
1527         /*
1528          * ->write_done will attempt to use post-op attributes to detect
1529          * conflicting writes by other clients.  A strict interpretation
1530          * of close-to-open would allow us to continue caching even if
1531          * another writer had changed the file, but some applications
1532          * depend on tighter cache coherency when writing.
1533          */
1534         status = NFS_PROTO(inode)->write_done(task, hdr);
1535         if (status != 0)
1536                 return status;
1537
1538         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1539         trace_nfs_writeback_done(inode, task->tk_status,
1540                                  hdr->args.offset, hdr->res.verf);
1541
1542         if (hdr->res.verf->committed < hdr->args.stable &&
1543             task->tk_status >= 0) {
1544                 /* We tried a write call, but the server did not
1545                  * commit data to stable storage even though we
1546                  * requested it.
1547                  * Note: There is a known bug in Tru64 < 5.0 in which
1548                  *       the server reports NFS_DATA_SYNC, but performs
1549                  *       NFS_FILE_SYNC. We therefore implement this checking
1550                  *       as a dprintk() in order to avoid filling syslog.
1551                  */
1552                 static unsigned long    complain;
1553
1554                 /* Note this will print the MDS for a DS write */
1555                 if (time_before(complain, jiffies)) {
1556                         dprintk("NFS:       faulty NFS server %s:"
1557                                 " (committed = %d) != (stable = %d)\n",
1558                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1559                                 hdr->res.verf->committed, hdr->args.stable);
1560                         complain = jiffies + 300 * HZ;
1561                 }
1562         }
1563
1564         /* Deal with the suid/sgid bit corner case */
1565         if (nfs_should_remove_suid(inode)) {
1566                 spin_lock(&inode->i_lock);
1567                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_OTHER;
1568                 spin_unlock(&inode->i_lock);
1569         }
1570         return 0;
1571 }
1572
1573 /*
1574  * This function is called when the WRITE call is complete.
1575  */
1576 static void nfs_writeback_result(struct rpc_task *task,
1577                                  struct nfs_pgio_header *hdr)
1578 {
1579         struct nfs_pgio_args    *argp = &hdr->args;
1580         struct nfs_pgio_res     *resp = &hdr->res;
1581
1582         if (resp->count < argp->count) {
1583                 static unsigned long    complain;
1584
1585                 /* This a short write! */
1586                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1587
1588                 /* Has the server at least made some progress? */
1589                 if (resp->count == 0) {
1590                         if (time_before(complain, jiffies)) {
1591                                 printk(KERN_WARNING
1592                                        "NFS: Server wrote zero bytes, expected %u.\n",
1593                                        argp->count);
1594                                 complain = jiffies + 300 * HZ;
1595                         }
1596                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1597                         task->tk_status = -EIO;
1598                         return;
1599                 }
1600
1601                 /* For non rpc-based layout drivers, retry-through-MDS */
1602                 if (!task->tk_ops) {
1603                         hdr->pnfs_error = -EAGAIN;
1604                         return;
1605                 }
1606
1607                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1608                 if (resp->verf->committed != NFS_UNSTABLE) {
1609                         /* Resend from where the server left off */
1610                         hdr->mds_offset += resp->count;
1611                         argp->offset += resp->count;
1612                         argp->pgbase += resp->count;
1613                         argp->count -= resp->count;
1614                 } else {
1615                         /* Resend as a stable write in order to avoid
1616                          * headaches in the case of a server crash.
1617                          */
1618                         argp->stable = NFS_FILE_SYNC;
1619                 }
1620                 rpc_restart_call_prepare(task);
1621         }
1622 }
1623
1624 static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1625 {
1626         return wait_var_event_killable(&cinfo->rpcs_out,
1627                                        !atomic_read(&cinfo->rpcs_out));
1628 }
1629
1630 static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1631 {
1632         atomic_inc(&cinfo->rpcs_out);
1633 }
1634
1635 static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1636 {
1637         if (atomic_dec_and_test(&cinfo->rpcs_out))
1638                 wake_up_var(&cinfo->rpcs_out);
1639 }
1640
1641 void nfs_commitdata_release(struct nfs_commit_data *data)
1642 {
1643         put_nfs_open_context(data->context);
1644         nfs_commit_free(data);
1645 }
1646 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1647
1648 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1649                         const struct nfs_rpc_ops *nfs_ops,
1650                         const struct rpc_call_ops *call_ops,
1651                         int how, int flags)
1652 {
1653         struct rpc_task *task;
1654         int priority = flush_task_priority(how);
1655         struct rpc_message msg = {
1656                 .rpc_argp = &data->args,
1657                 .rpc_resp = &data->res,
1658                 .rpc_cred = data->cred,
1659         };
1660         struct rpc_task_setup task_setup_data = {
1661                 .task = &data->task,
1662                 .rpc_client = clnt,
1663                 .rpc_message = &msg,
1664                 .callback_ops = call_ops,
1665                 .callback_data = data,
1666                 .workqueue = nfsiod_workqueue,
1667                 .flags = RPC_TASK_ASYNC | flags,
1668                 .priority = priority,
1669         };
1670         /* Set up the initial task struct.  */
1671         nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1672         trace_nfs_initiate_commit(data);
1673
1674         dprintk("NFS: initiated commit call\n");
1675
1676         task = rpc_run_task(&task_setup_data);
1677         if (IS_ERR(task))
1678                 return PTR_ERR(task);
1679         if (how & FLUSH_SYNC)
1680                 rpc_wait_for_completion_task(task);
1681         rpc_put_task(task);
1682         return 0;
1683 }
1684 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1685
1686 static loff_t nfs_get_lwb(struct list_head *head)
1687 {
1688         loff_t lwb = 0;
1689         struct nfs_page *req;
1690
1691         list_for_each_entry(req, head, wb_list)
1692                 if (lwb < (req_offset(req) + req->wb_bytes))
1693                         lwb = req_offset(req) + req->wb_bytes;
1694
1695         return lwb;
1696 }
1697
1698 /*
1699  * Set up the argument/result storage required for the RPC call.
1700  */
1701 void nfs_init_commit(struct nfs_commit_data *data,
1702                      struct list_head *head,
1703                      struct pnfs_layout_segment *lseg,
1704                      struct nfs_commit_info *cinfo)
1705 {
1706         struct nfs_page *first = nfs_list_entry(head->next);
1707         struct inode *inode = d_inode(first->wb_context->dentry);
1708
1709         /* Set up the RPC argument and reply structs
1710          * NB: take care not to mess about with data->commit et al. */
1711
1712         list_splice_init(head, &data->pages);
1713
1714         data->inode       = inode;
1715         data->cred        = first->wb_context->cred;
1716         data->lseg        = lseg; /* reference transferred */
1717         /* only set lwb for pnfs commit */
1718         if (lseg)
1719                 data->lwb = nfs_get_lwb(&data->pages);
1720         data->mds_ops     = &nfs_commit_ops;
1721         data->completion_ops = cinfo->completion_ops;
1722         data->dreq        = cinfo->dreq;
1723
1724         data->args.fh     = NFS_FH(data->inode);
1725         /* Note: we always request a commit of the entire inode */
1726         data->args.offset = 0;
1727         data->args.count  = 0;
1728         data->context     = get_nfs_open_context(first->wb_context);
1729         data->res.fattr   = &data->fattr;
1730         data->res.verf    = &data->verf;
1731         nfs_fattr_init(&data->fattr);
1732 }
1733 EXPORT_SYMBOL_GPL(nfs_init_commit);
1734
1735 void nfs_retry_commit(struct list_head *page_list,
1736                       struct pnfs_layout_segment *lseg,
1737                       struct nfs_commit_info *cinfo,
1738                       u32 ds_commit_idx)
1739 {
1740         struct nfs_page *req;
1741
1742         while (!list_empty(page_list)) {
1743                 req = nfs_list_entry(page_list->next);
1744                 nfs_list_remove_request(req);
1745                 nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1746                 if (!cinfo->dreq)
1747                         nfs_clear_page_commit(req->wb_page);
1748                 nfs_unlock_and_release_request(req);
1749         }
1750 }
1751 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1752
1753 static void
1754 nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1755                 struct nfs_page *req)
1756 {
1757         __set_page_dirty_nobuffers(req->wb_page);
1758 }
1759
1760 /*
1761  * Commit dirty pages
1762  */
1763 static int
1764 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1765                 struct nfs_commit_info *cinfo)
1766 {
1767         struct nfs_commit_data  *data;
1768
1769         /* another commit raced with us */
1770         if (list_empty(head))
1771                 return 0;
1772
1773         data = nfs_commitdata_alloc(true);
1774
1775         /* Set up the argument struct */
1776         nfs_init_commit(data, head, NULL, cinfo);
1777         atomic_inc(&cinfo->mds->rpcs_out);
1778         return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1779                                    data->mds_ops, how, 0);
1780 }
1781
1782 /*
1783  * COMMIT call returned
1784  */
1785 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1786 {
1787         struct nfs_commit_data  *data = calldata;
1788
1789         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1790                                 task->tk_pid, task->tk_status);
1791
1792         /* Call the NFS version-specific code */
1793         NFS_PROTO(data->inode)->commit_done(task, data);
1794         trace_nfs_commit_done(data);
1795 }
1796
1797 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1798 {
1799         struct nfs_page *req;
1800         int status = data->task.tk_status;
1801         struct nfs_commit_info cinfo;
1802         struct nfs_server *nfss;
1803
1804         while (!list_empty(&data->pages)) {
1805                 req = nfs_list_entry(data->pages.next);
1806                 nfs_list_remove_request(req);
1807                 if (req->wb_page)
1808                         nfs_clear_page_commit(req->wb_page);
1809
1810                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1811                         req->wb_context->dentry->d_sb->s_id,
1812                         (unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)),
1813                         req->wb_bytes,
1814                         (long long)req_offset(req));
1815                 if (status < 0) {
1816                         nfs_context_set_write_error(req->wb_context, status);
1817                         if (req->wb_page)
1818                                 nfs_inode_remove_request(req);
1819                         dprintk_cont(", error = %d\n", status);
1820                         goto next;
1821                 }
1822
1823                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1824                  * returned by the server against all stored verfs. */
1825                 if (!nfs_write_verifier_cmp(&req->wb_verf, &data->verf.verifier)) {
1826                         /* We have a match */
1827                         if (req->wb_page)
1828                                 nfs_inode_remove_request(req);
1829                         dprintk_cont(" OK\n");
1830                         goto next;
1831                 }
1832                 /* We have a mismatch. Write the page again */
1833                 dprintk_cont(" mismatch\n");
1834                 nfs_mark_request_dirty(req);
1835                 set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1836         next:
1837                 nfs_unlock_and_release_request(req);
1838                 /* Latency breaker */
1839                 cond_resched();
1840         }
1841         nfss = NFS_SERVER(data->inode);
1842         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1843                 clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
1844
1845         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1846         nfs_commit_end(cinfo.mds);
1847 }
1848
1849 static void nfs_commit_release(void *calldata)
1850 {
1851         struct nfs_commit_data *data = calldata;
1852
1853         data->completion_ops->completion(data);
1854         nfs_commitdata_release(calldata);
1855 }
1856
1857 static const struct rpc_call_ops nfs_commit_ops = {
1858         .rpc_call_prepare = nfs_commit_prepare,
1859         .rpc_call_done = nfs_commit_done,
1860         .rpc_release = nfs_commit_release,
1861 };
1862
1863 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1864         .completion = nfs_commit_release_pages,
1865         .resched_write = nfs_commit_resched_write,
1866 };
1867
1868 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1869                             int how, struct nfs_commit_info *cinfo)
1870 {
1871         int status;
1872
1873         status = pnfs_commit_list(inode, head, how, cinfo);
1874         if (status == PNFS_NOT_ATTEMPTED)
1875                 status = nfs_commit_list(inode, head, how, cinfo);
1876         return status;
1877 }
1878
1879 static int __nfs_commit_inode(struct inode *inode, int how,
1880                 struct writeback_control *wbc)
1881 {
1882         LIST_HEAD(head);
1883         struct nfs_commit_info cinfo;
1884         int may_wait = how & FLUSH_SYNC;
1885         int ret, nscan;
1886
1887         nfs_init_cinfo_from_inode(&cinfo, inode);
1888         nfs_commit_begin(cinfo.mds);
1889         for (;;) {
1890                 ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1891                 if (ret <= 0)
1892                         break;
1893                 ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1894                 if (ret < 0)
1895                         break;
1896                 ret = 0;
1897                 if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1898                         if (nscan < wbc->nr_to_write)
1899                                 wbc->nr_to_write -= nscan;
1900                         else
1901                                 wbc->nr_to_write = 0;
1902                 }
1903                 if (nscan < INT_MAX)
1904                         break;
1905                 cond_resched();
1906         }
1907         nfs_commit_end(cinfo.mds);
1908         if (ret || !may_wait)
1909                 return ret;
1910         return wait_on_commit(cinfo.mds);
1911 }
1912
1913 int nfs_commit_inode(struct inode *inode, int how)
1914 {
1915         return __nfs_commit_inode(inode, how, NULL);
1916 }
1917 EXPORT_SYMBOL_GPL(nfs_commit_inode);
1918
1919 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1920 {
1921         struct nfs_inode *nfsi = NFS_I(inode);
1922         int flags = FLUSH_SYNC;
1923         int ret = 0;
1924
1925         if (wbc->sync_mode == WB_SYNC_NONE) {
1926                 /* no commits means nothing needs to be done */
1927                 if (!atomic_long_read(&nfsi->commit_info.ncommit))
1928                         goto check_requests_outstanding;
1929
1930                 /* Don't commit yet if this is a non-blocking flush and there
1931                  * are a lot of outstanding writes for this mapping.
1932                  */
1933                 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1934                         goto out_mark_dirty;
1935
1936                 /* don't wait for the COMMIT response */
1937                 flags = 0;
1938         }
1939
1940         ret = __nfs_commit_inode(inode, flags, wbc);
1941         if (!ret) {
1942                 if (flags & FLUSH_SYNC)
1943                         return 0;
1944         } else if (atomic_long_read(&nfsi->commit_info.ncommit))
1945                 goto out_mark_dirty;
1946
1947 check_requests_outstanding:
1948         if (!atomic_read(&nfsi->commit_info.rpcs_out))
1949                 return ret;
1950 out_mark_dirty:
1951         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1952         return ret;
1953 }
1954 EXPORT_SYMBOL_GPL(nfs_write_inode);
1955
1956 /*
1957  * Wrapper for filemap_write_and_wait_range()
1958  *
1959  * Needed for pNFS in order to ensure data becomes visible to the
1960  * client.
1961  */
1962 int nfs_filemap_write_and_wait_range(struct address_space *mapping,
1963                 loff_t lstart, loff_t lend)
1964 {
1965         int ret;
1966
1967         ret = filemap_write_and_wait_range(mapping, lstart, lend);
1968         if (ret == 0)
1969                 ret = pnfs_sync_inode(mapping->host, true);
1970         return ret;
1971 }
1972 EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
1973
1974 /*
1975  * flush the inode to disk.
1976  */
1977 int nfs_wb_all(struct inode *inode)
1978 {
1979         int ret;
1980
1981         trace_nfs_writeback_inode_enter(inode);
1982
1983         ret = filemap_write_and_wait(inode->i_mapping);
1984         if (ret)
1985                 goto out;
1986         ret = nfs_commit_inode(inode, FLUSH_SYNC);
1987         if (ret < 0)
1988                 goto out;
1989         pnfs_sync_inode(inode, true);
1990         ret = 0;
1991
1992 out:
1993         trace_nfs_writeback_inode_exit(inode, ret);
1994         return ret;
1995 }
1996 EXPORT_SYMBOL_GPL(nfs_wb_all);
1997
1998 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1999 {
2000         struct nfs_page *req;
2001         int ret = 0;
2002
2003         wait_on_page_writeback(page);
2004
2005         /* blocking call to cancel all requests and join to a single (head)
2006          * request */
2007         req = nfs_lock_and_join_requests(page);
2008
2009         if (IS_ERR(req)) {
2010                 ret = PTR_ERR(req);
2011         } else if (req) {
2012                 /* all requests from this page have been cancelled by
2013                  * nfs_lock_and_join_requests, so just remove the head
2014                  * request from the inode / page_private pointer and
2015                  * release it */
2016                 nfs_inode_remove_request(req);
2017                 nfs_unlock_and_release_request(req);
2018         }
2019
2020         return ret;
2021 }
2022
2023 /*
2024  * Write back all requests on one page - we do this before reading it.
2025  */
2026 int nfs_wb_page(struct inode *inode, struct page *page)
2027 {
2028         loff_t range_start = page_file_offset(page);
2029         loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2030         struct writeback_control wbc = {
2031                 .sync_mode = WB_SYNC_ALL,
2032                 .nr_to_write = 0,
2033                 .range_start = range_start,
2034                 .range_end = range_end,
2035         };
2036         int ret;
2037
2038         trace_nfs_writeback_page_enter(inode);
2039
2040         for (;;) {
2041                 wait_on_page_writeback(page);
2042                 if (clear_page_dirty_for_io(page)) {
2043                         ret = nfs_writepage_locked(page, &wbc);
2044                         if (ret < 0)
2045                                 goto out_error;
2046                         continue;
2047                 }
2048                 ret = 0;
2049                 if (!PagePrivate(page))
2050                         break;
2051                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
2052                 if (ret < 0)
2053                         goto out_error;
2054         }
2055 out_error:
2056         trace_nfs_writeback_page_exit(inode, ret);
2057         return ret;
2058 }
2059
2060 #ifdef CONFIG_MIGRATION
2061 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
2062                 struct page *page, enum migrate_mode mode)
2063 {
2064         /*
2065          * If PagePrivate is set, then the page is currently associated with
2066          * an in-progress read or write request. Don't try to migrate it.
2067          *
2068          * FIXME: we could do this in principle, but we'll need a way to ensure
2069          *        that we can safely release the inode reference while holding
2070          *        the page lock.
2071          */
2072         if (PagePrivate(page))
2073                 return -EBUSY;
2074
2075         if (!nfs_fscache_release_page(page, GFP_KERNEL))
2076                 return -EBUSY;
2077
2078         return migrate_page(mapping, newpage, page, mode);
2079 }
2080 #endif
2081
2082 int __init nfs_init_writepagecache(void)
2083 {
2084         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2085                                              sizeof(struct nfs_pgio_header),
2086                                              0, SLAB_HWCACHE_ALIGN,
2087                                              NULL);
2088         if (nfs_wdata_cachep == NULL)
2089                 return -ENOMEM;
2090
2091         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2092                                                      nfs_wdata_cachep);
2093         if (nfs_wdata_mempool == NULL)
2094                 goto out_destroy_write_cache;
2095
2096         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2097                                              sizeof(struct nfs_commit_data),
2098                                              0, SLAB_HWCACHE_ALIGN,
2099                                              NULL);
2100         if (nfs_cdata_cachep == NULL)
2101                 goto out_destroy_write_mempool;
2102
2103         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2104                                                       nfs_cdata_cachep);
2105         if (nfs_commit_mempool == NULL)
2106                 goto out_destroy_commit_cache;
2107
2108         /*
2109          * NFS congestion size, scale with available memory.
2110          *
2111          *  64MB:    8192k
2112          * 128MB:   11585k
2113          * 256MB:   16384k
2114          * 512MB:   23170k
2115          *   1GB:   32768k
2116          *   2GB:   46340k
2117          *   4GB:   65536k
2118          *   8GB:   92681k
2119          *  16GB:  131072k
2120          *
2121          * This allows larger machines to have larger/more transfers.
2122          * Limit the default to 256M
2123          */
2124         nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2125         if (nfs_congestion_kb > 256*1024)
2126                 nfs_congestion_kb = 256*1024;
2127
2128         return 0;
2129
2130 out_destroy_commit_cache:
2131         kmem_cache_destroy(nfs_cdata_cachep);
2132 out_destroy_write_mempool:
2133         mempool_destroy(nfs_wdata_mempool);
2134 out_destroy_write_cache:
2135         kmem_cache_destroy(nfs_wdata_cachep);
2136         return -ENOMEM;
2137 }
2138
2139 void nfs_destroy_writepagecache(void)
2140 {
2141         mempool_destroy(nfs_commit_mempool);
2142         kmem_cache_destroy(nfs_cdata_cachep);
2143         mempool_destroy(nfs_wdata_mempool);
2144         kmem_cache_destroy(nfs_wdata_cachep);
2145 }
2146
2147 static const struct nfs_rw_ops nfs_rw_write_ops = {
2148         .rw_alloc_header        = nfs_writehdr_alloc,
2149         .rw_free_header         = nfs_writehdr_free,
2150         .rw_done                = nfs_writeback_done,
2151         .rw_result              = nfs_writeback_result,
2152         .rw_initiate            = nfs_initiate_write,
2153 };