fs/nfs/write.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/write.c
   4  *
   5  * Write file data over NFS.
   6  *
   7  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/slab.h>
  12 #include <linux/mm.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/file.h>
  15 #include <linux/writeback.h>
  16 #include <linux/swap.h>
  17 #include <linux/migrate.h>
  18
  19 #include <linux/sunrpc/clnt.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_mount.h>
  22 #include <linux/nfs_page.h>
  23 #include <linux/backing-dev.h>
  24 #include <linux/export.h>
  25 #include <linux/freezer.h>
  26 #include <linux/wait.h>
  27 #include <linux/iversion.h>
  28
  29 #include <linux/uaccess.h>
  30 #include <linux/sched/mm.h>
  31
  32 #include "delegation.h"
  33 #include "internal.h"
  34 #include "iostat.h"
  35 #include "nfs4_fs.h"
  36 #include "fscache.h"
  37 #include "pnfs.h"
  38
  39 #include "nfstrace.h"
  40
  41 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  42
  43 #define MIN_POOL_WRITE          (32)
  44 #define MIN_POOL_COMMIT         (4)
  45
  46 struct nfs_io_completion {
  47         void (*complete)(void *data);
  48         void *data;
  49         struct kref refcount;
  50 };
  51
  52 /*
  53  * Local function declarations
  54  */
  55 static void nfs_redirty_request(struct nfs_page *req);
  56 static const struct rpc_call_ops nfs_commit_ops;
  57 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  58 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  59 static const struct nfs_rw_ops nfs_rw_write_ops;
  60 static void nfs_inode_remove_request(struct nfs_page *req);
  61 static void nfs_clear_request_commit(struct nfs_page *req);
  62 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
  63                                       struct inode *inode);
  64 static struct nfs_page *
  65 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
  66                                                 struct page *page);
  67
  68 static struct kmem_cache *nfs_wdata_cachep;
  69 static mempool_t *nfs_wdata_mempool;
  70 static struct kmem_cache *nfs_cdata_cachep;
  71 static mempool_t *nfs_commit_mempool;
  72
  73 struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail)
  74 {
  75         struct nfs_commit_data *p;
  76
  77         if (never_fail)
  78                 p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
  79         else {
  80                 /* It is OK to do some reclaim, not no safe to wait
  81                  * for anything to be returned to the pool.
  82                  * mempool_alloc() cannot handle that particular combination,
  83                  * so we need two separate attempts.
  84                  */
  85                 p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
  86                 if (!p)
  87                         p = kmem_cache_alloc(nfs_cdata_cachep, GFP_NOIO |
  88                                              __GFP_NOWARN | __GFP_NORETRY);
  89                 if (!p)
  90                         return NULL;
  91         }
  92
  93         memset(p, 0, sizeof(*p));
  94         INIT_LIST_HEAD(&p->pages);
  95         return p;
  96 }
  97 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  98
  99 void nfs_commit_free(struct nfs_commit_data *p)
 100 {
 101         mempool_free(p, nfs_commit_mempool);
 102 }
 103 EXPORT_SYMBOL_GPL(nfs_commit_free);
 104
 105 static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 106 {
 107         struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_KERNEL);
 108
 109         memset(p, 0, sizeof(*p));
 110         p->rw_mode = FMODE_WRITE;
 111         return p;
 112 }
 113
 114 static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 115 {
 116         mempool_free(hdr, nfs_wdata_mempool);
 117 }
 118
 119 static struct nfs_io_completion *nfs_io_completion_alloc(gfp_t gfp_flags)
 120 {
 121         return kmalloc(sizeof(struct nfs_io_completion), gfp_flags);
 122 }
 123
 124 static void nfs_io_completion_init(struct nfs_io_completion *ioc,
 125                 void (*complete)(void *), void *data)
 126 {
 127         ioc->complete = complete;
 128         ioc->data = data;
 129         kref_init(&ioc->refcount);
 130 }
 131
 132 static void nfs_io_completion_release(struct kref *kref)
 133 {
 134         struct nfs_io_completion *ioc = container_of(kref,
 135                         struct nfs_io_completion, refcount);
 136         ioc->complete(ioc->data);
 137         kfree(ioc);
 138 }
 139
 140 static void nfs_io_completion_get(struct nfs_io_completion *ioc)
 141 {
 142         if (ioc != NULL)
 143                 kref_get(&ioc->refcount);
 144 }
 145
 146 static void nfs_io_completion_put(struct nfs_io_completion *ioc)
 147 {
 148         if (ioc != NULL)
 149                 kref_put(&ioc->refcount, nfs_io_completion_release);
 150 }
 151
 152 static struct nfs_page *
 153 nfs_page_private_request(struct page *page)
 154 {
 155         if (!PagePrivate(page))
 156                 return NULL;
 157         return (struct nfs_page *)page_private(page);
 158 }
 159
 160 /*
 161  * nfs_page_find_head_request_locked - find head request associated with @page
 162  *
 163  * must be called while holding the inode lock.
 164  *
 165  * returns matching head request with reference held, or NULL if not found.
 166  */
 167 static struct nfs_page *
 168 nfs_page_find_private_request(struct page *page)
 169 {
 170         struct address_space *mapping = page_file_mapping(page);
 171         struct nfs_page *req;
 172
 173         if (!PagePrivate(page))
 174                 return NULL;
 175         spin_lock(&mapping->private_lock);
 176         req = nfs_page_private_request(page);
 177         if (req) {
 178                 WARN_ON_ONCE(req->wb_head != req);
 179                 kref_get(&req->wb_kref);
 180         }
 181         spin_unlock(&mapping->private_lock);
 182         return req;
 183 }
 184
 185 static struct nfs_page *
 186 nfs_page_find_swap_request(struct page *page)
 187 {
 188         struct inode *inode = page_file_mapping(page)->host;
 189         struct nfs_inode *nfsi = NFS_I(inode);
 190         struct nfs_page *req = NULL;
 191         if (!PageSwapCache(page))
 192                 return NULL;
 193         mutex_lock(&nfsi->commit_mutex);
 194         if (PageSwapCache(page)) {
 195                 req = nfs_page_search_commits_for_head_request_locked(nfsi,
 196                         page);
 197                 if (req) {
 198                         WARN_ON_ONCE(req->wb_head != req);
 199                         kref_get(&req->wb_kref);
 200                 }
 201         }
 202         mutex_unlock(&nfsi->commit_mutex);
 203         return req;
 204 }
 205
 206 /*
 207  * nfs_page_find_head_request - find head request associated with @page
 208  *
 209  * returns matching head request with reference held, or NULL if not found.
 210  */
 211 static struct nfs_page *nfs_page_find_head_request(struct page *page)
 212 {
 213         struct nfs_page *req;
 214
 215         req = nfs_page_find_private_request(page);
 216         if (!req)
 217                 req = nfs_page_find_swap_request(page);
 218         return req;
 219 }
 220
 221 /* Adjust the file length if we're writing beyond the end */
 222 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 223 {
 224         struct inode *inode = page_file_mapping(page)->host;
 225         loff_t end, i_size;
 226         pgoff_t end_index;
 227
 228         spin_lock(&inode->i_lock);
 229         i_size = i_size_read(inode);
 230         end_index = (i_size - 1) >> PAGE_SHIFT;
 231         if (i_size > 0 && page_index(page) < end_index)
 232                 goto out;
 233         end = page_file_offset(page) + ((loff_t)offset+count);
 234         if (i_size >= end)
 235                 goto out;
 236         i_size_write(inode, end);
 237         NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
 238         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 239 out:
 240         spin_unlock(&inode->i_lock);
 241 }
 242
 243 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 244 static void nfs_set_pageerror(struct address_space *mapping)
 245 {
 246         struct inode *inode = mapping->host;
 247
 248         nfs_zap_mapping(mapping->host, mapping);
 249         /* Force file size revalidation */
 250         spin_lock(&inode->i_lock);
 251         NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED |
 252                                         NFS_INO_REVAL_PAGECACHE |
 253                                         NFS_INO_INVALID_SIZE;
 254         spin_unlock(&inode->i_lock);
 255 }
 256
 257 static void nfs_mapping_set_error(struct page *page, int error)
 258 {
 259         SetPageError(page);
 260         mapping_set_error(page_file_mapping(page), error);
 261 }
 262
 263 /*
 264  * nfs_page_group_search_locked
 265  * @head - head request of page group
 266  * @page_offset - offset into page
 267  *
 268  * Search page group with head @head to find a request that contains the
 269  * page offset @page_offset.
 270  *
 271  * Returns a pointer to the first matching nfs request, or NULL if no
 272  * match is found.
 273  *
 274  * Must be called with the page group lock held
 275  */
 276 static struct nfs_page *
 277 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
 278 {
 279         struct nfs_page *req;
 280
 281         req = head;
 282         do {
 283                 if (page_offset >= req->wb_pgbase &&
 284                     page_offset < (req->wb_pgbase + req->wb_bytes))
 285                         return req;
 286
 287                 req = req->wb_this_page;
 288         } while (req != head);
 289
 290         return NULL;
 291 }
 292
 293 /*
 294  * nfs_page_group_covers_page
 295  * @head - head request of page group
 296  *
 297  * Return true if the page group with head @head covers the whole page,
 298  * returns false otherwise
 299  */
 300 static bool nfs_page_group_covers_page(struct nfs_page *req)
 301 {
 302         struct nfs_page *tmp;
 303         unsigned int pos = 0;
 304         unsigned int len = nfs_page_length(req->wb_page);
 305
 306         nfs_page_group_lock(req);
 307
 308         for (;;) {
 309                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
 310                 if (!tmp)
 311                         break;
 312                 pos = tmp->wb_pgbase + tmp->wb_bytes;
 313         }
 314
 315         nfs_page_group_unlock(req);
 316         return pos >= len;
 317 }
 318
 319 /* We can set the PG_uptodate flag if we see that a write request
 320  * covers the full page.
 321  */
 322 static void nfs_mark_uptodate(struct nfs_page *req)
 323 {
 324         if (PageUptodate(req->wb_page))
 325                 return;
 326         if (!nfs_page_group_covers_page(req))
 327                 return;
 328         SetPageUptodate(req->wb_page);
 329 }
 330
 331 static int wb_priority(struct writeback_control *wbc)
 332 {
 333         int ret = 0;
 334
 335         if (wbc->sync_mode == WB_SYNC_ALL)
 336                 ret = FLUSH_COND_STABLE;
 337         return ret;
 338 }
 339
 340 /*
 341  * NFS congestion control
 342  */
 343
 344 int nfs_congestion_kb;
 345
 346 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 347 #define NFS_CONGESTION_OFF_THRESH       \
 348         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 349
 350 static void nfs_set_page_writeback(struct page *page)
 351 {
 352         struct inode *inode = page_file_mapping(page)->host;
 353         struct nfs_server *nfss = NFS_SERVER(inode);
 354         int ret = test_set_page_writeback(page);
 355
 356         WARN_ON_ONCE(ret != 0);
 357
 358         if (atomic_long_inc_return(&nfss->writeback) >
 359                         NFS_CONGESTION_ON_THRESH)
 360                 set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 361 }
 362
 363 static void nfs_end_page_writeback(struct nfs_page *req)
 364 {
 365         struct inode *inode = page_file_mapping(req->wb_page)->host;
 366         struct nfs_server *nfss = NFS_SERVER(inode);
 367         bool is_done;
 368
 369         is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
 370         nfs_unlock_request(req);
 371         if (!is_done)
 372                 return;
 373
 374         end_page_writeback(req->wb_page);
 375         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 376                 clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 377 }
 378
 379 /*
 380  * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
 381  *
 382  * this is a helper function for nfs_lock_and_join_requests
 383  *
 384  * @inode - inode associated with request page group, must be holding inode lock
 385  * @head  - head request of page group, must be holding head lock
 386  * @req   - request that couldn't lock and needs to wait on the req bit lock
 387  *
 388  * NOTE: this must be called holding page_group bit lock
 389  *       which will be released before returning.
 390  *
 391  * returns 0 on success, < 0 on error.
 392  */
 393 static void
 394 nfs_unroll_locks(struct inode *inode, struct nfs_page *head,
 395                           struct nfs_page *req)
 396 {
 397         struct nfs_page *tmp;
 398
 399         /* relinquish all the locks successfully grabbed this run */
 400         for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
 401                 if (!kref_read(&tmp->wb_kref))
 402                         continue;
 403                 nfs_unlock_and_release_request(tmp);
 404         }
 405 }
 406
 407 /*
 408  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
 409  *
 410  * @destroy_list - request list (using wb_this_page) terminated by @old_head
 411  * @old_head - the old head of the list
 412  *
 413  * All subrequests must be locked and removed from all lists, so at this point
 414  * they are only "active" in this function, and possibly in nfs_wait_on_request
 415  * with a reference held by some other context.
 416  */
 417 static void
 418 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 419                                  struct nfs_page *old_head,
 420                                  struct inode *inode)
 421 {
 422         while (destroy_list) {
 423                 struct nfs_page *subreq = destroy_list;
 424
 425                 destroy_list = (subreq->wb_this_page == old_head) ?
 426                                    NULL : subreq->wb_this_page;
 427
 428                 /* Note: lock subreq in order to change subreq->wb_head */
 429                 nfs_page_set_headlock(subreq);
 430                 WARN_ON_ONCE(old_head != subreq->wb_head);
 431
 432                 /* make sure old group is not used */
 433                 subreq->wb_this_page = subreq;
 434                 subreq->wb_head = subreq;
 435
 436                 clear_bit(PG_REMOVE, &subreq->wb_flags);
 437
 438                 /* Note: races with nfs_page_group_destroy() */
 439                 if (!kref_read(&subreq->wb_kref)) {
 440                         /* Check if we raced with nfs_page_group_destroy() */
 441                         if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags)) {
 442                                 nfs_page_clear_headlock(subreq);
 443                                 nfs_free_request(subreq);
 444                         } else
 445                                 nfs_page_clear_headlock(subreq);
 446                         continue;
 447                 }
 448                 nfs_page_clear_headlock(subreq);
 449
 450                 nfs_release_request(old_head);
 451
 452                 if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 453                         nfs_release_request(subreq);
 454                         atomic_long_dec(&NFS_I(inode)->nrequests);
 455                 }
 456
 457                 /* subreq is now totally disconnected from page group or any
 458                  * write / commit lists. last chance to wake any waiters */
 459                 nfs_unlock_and_release_request(subreq);
 460         }
 461 }
 462
 463 /*
 464  * nfs_lock_and_join_requests - join all subreqs to the head req and return
 465  *                              a locked reference, cancelling any pending
 466  *                              operations for this page.
 467  *
 468  * @page - the page used to lookup the "page group" of nfs_page structures
 469  *
 470  * This function joins all sub requests to the head request by first
 471  * locking all requests in the group, cancelling any pending operations
 472  * and finally updating the head request to cover the whole range covered by
 473  * the (former) group.  All subrequests are removed from any write or commit
 474  * lists, unlinked from the group and destroyed.
 475  *
 476  * Returns a locked, referenced pointer to the head request - which after
 477  * this call is guaranteed to be the only request associated with the page.
 478  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
 479  * error was encountered.
 480  */
 481 static struct nfs_page *
 482 nfs_lock_and_join_requests(struct page *page)
 483 {
 484         struct inode *inode = page_file_mapping(page)->host;
 485         struct nfs_page *head, *subreq;
 486         struct nfs_page *destroy_list = NULL;
 487         unsigned int total_bytes;
 488         int ret;
 489
 490 try_again:
 491         /*
 492          * A reference is taken only on the head request which acts as a
 493          * reference to the whole page group - the group will not be destroyed
 494          * until the head reference is released.
 495          */
 496         head = nfs_page_find_head_request(page);
 497         if (!head)
 498                 return NULL;
 499
 500         /* lock the page head first in order to avoid an ABBA inefficiency */
 501         if (!nfs_lock_request(head)) {
 502                 ret = nfs_wait_on_request(head);
 503                 nfs_release_request(head);
 504                 if (ret < 0)
 505                         return ERR_PTR(ret);
 506                 goto try_again;
 507         }
 508
 509         /* Ensure that nobody removed the request before we locked it */
 510         if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {
 511                 nfs_unlock_and_release_request(head);
 512                 goto try_again;
 513         }
 514
 515         ret = nfs_page_group_lock(head);
 516         if (ret < 0)
 517                 goto release_request;
 518
 519         /* lock each request in the page group */
 520         total_bytes = head->wb_bytes;
 521         for (subreq = head->wb_this_page; subreq != head;
 522                         subreq = subreq->wb_this_page) {
 523
 524                 if (!kref_get_unless_zero(&subreq->wb_kref)) {
 525                         if (subreq->wb_offset == head->wb_offset + total_bytes)
 526                                 total_bytes += subreq->wb_bytes;
 527                         continue;
 528                 }
 529
 530                 while (!nfs_lock_request(subreq)) {
 531                         /*
 532                          * Unlock page to allow nfs_page_group_sync_on_bit()
 533                          * to succeed
 534                          */
 535                         nfs_page_group_unlock(head);
 536                         ret = nfs_wait_on_request(subreq);
 537                         if (!ret)
 538                                 ret = nfs_page_group_lock(head);
 539                         if (ret < 0) {
 540                                 nfs_unroll_locks(inode, head, subreq);
 541                                 nfs_release_request(subreq);
 542                                 goto release_request;
 543                         }
 544                 }
 545                 /*
 546                  * Subrequests are always contiguous, non overlapping
 547                  * and in order - but may be repeated (mirrored writes).
 548                  */
 549                 if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
 550                         /* keep track of how many bytes this group covers */
 551                         total_bytes += subreq->wb_bytes;
 552                 } else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
 553                             ((subreq->wb_offset + subreq->wb_bytes) >
 554                              (head->wb_offset + total_bytes)))) {
 555                         nfs_page_group_unlock(head);
 556                         nfs_unroll_locks(inode, head, subreq);
 557                         nfs_unlock_and_release_request(subreq);
 558                         ret = -EIO;
 559                         goto release_request;
 560                 }
 561         }
 562
 563         /* Now that all requests are locked, make sure they aren't on any list.
 564          * Commit list removal accounting is done after locks are dropped */
 565         subreq = head;
 566         do {
 567                 nfs_clear_request_commit(subreq);
 568                 subreq = subreq->wb_this_page;
 569         } while (subreq != head);
 570
 571         /* unlink subrequests from head, destroy them later */
 572         if (head->wb_this_page != head) {
 573                 /* destroy list will be terminated by head */
 574                 destroy_list = head->wb_this_page;
 575                 head->wb_this_page = head;
 576
 577                 /* change head request to cover whole range that
 578                  * the former page group covered */
 579                 head->wb_bytes = total_bytes;
 580         }
 581
 582         /* Postpone destruction of this request */
 583         if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) {
 584                 set_bit(PG_INODE_REF, &head->wb_flags);
 585                 kref_get(&head->wb_kref);
 586                 atomic_long_inc(&NFS_I(inode)->nrequests);
 587         }
 588
 589         nfs_page_group_unlock(head);
 590
 591         nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 592
 593         /* Did we lose a race with nfs_inode_remove_request()? */
 594         if (!(PagePrivate(page) || PageSwapCache(page))) {
 595                 nfs_unlock_and_release_request(head);
 596                 return NULL;
 597         }
 598
 599         /* still holds ref on head from nfs_page_find_head_request
 600          * and still has lock on head from lock loop */
 601         return head;
 602
 603 release_request:
 604         nfs_unlock_and_release_request(head);
 605         return ERR_PTR(ret);
 606 }
 607
 608 static void nfs_write_error(struct nfs_page *req, int error)
 609 {
 610         nfs_set_pageerror(page_file_mapping(req->wb_page));
 611         nfs_mapping_set_error(req->wb_page, error);
 612         nfs_inode_remove_request(req);
 613         nfs_end_page_writeback(req);
 614         nfs_release_request(req);
 615 }
 616
 617 /*
 618  * Find an associated nfs write request, and prepare to flush it out
 619  * May return an error if the user signalled nfs_wait_on_request().
 620  */
 621 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 622                                 struct page *page)
 623 {
 624         struct nfs_page *req;
 625         int ret = 0;
 626
 627         req = nfs_lock_and_join_requests(page);
 628         if (!req)
 629                 goto out;
 630         ret = PTR_ERR(req);
 631         if (IS_ERR(req))
 632                 goto out;
 633
 634         nfs_set_page_writeback(page);
 635         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 636
 637         /* If there is a fatal error that covers this write, just exit */
 638         ret = pgio->pg_error;
 639         if (nfs_error_is_fatal_on_server(ret))
 640                 goto out_launder;
 641
 642         ret = 0;
 643         if (!nfs_pageio_add_request(pgio, req)) {
 644                 ret = pgio->pg_error;
 645                 /*
 646                  * Remove the problematic req upon fatal errors on the server
 647                  */
 648                 if (nfs_error_is_fatal(ret)) {
 649                         if (nfs_error_is_fatal_on_server(ret))
 650                                 goto out_launder;
 651                 } else
 652                         ret = -EAGAIN;
 653                 nfs_redirty_request(req);
 654                 pgio->pg_error = 0;
 655         } else
 656                 nfs_add_stats(page_file_mapping(page)->host,
 657                                 NFSIOS_WRITEPAGES, 1);
 658 out:
 659         return ret;
 660 out_launder:
 661         nfs_write_error(req, ret);
 662         return 0;
 663 }
 664
 665 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
 666                             struct nfs_pageio_descriptor *pgio)
 667 {
 668         int ret;
 669
 670         nfs_pageio_cond_complete(pgio, page_index(page));
 671         ret = nfs_page_async_flush(pgio, page);
 672         if (ret == -EAGAIN) {
 673                 redirty_page_for_writepage(wbc, page);
 674                 ret = AOP_WRITEPAGE_ACTIVATE;
 675         }
 676         return ret;
 677 }
 678
 679 /*
 680  * Write an mmapped page to the server.
 681  */
 682 static int nfs_writepage_locked(struct page *page,
 683                                 struct writeback_control *wbc)
 684 {
 685         struct nfs_pageio_descriptor pgio;
 686         struct inode *inode = page_file_mapping(page)->host;
 687         int err;
 688
 689         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 690         nfs_pageio_init_write(&pgio, inode, 0,
 691                                 false, &nfs_async_write_completion_ops);
 692         err = nfs_do_writepage(page, wbc, &pgio);
 693         pgio.pg_error = 0;
 694         nfs_pageio_complete(&pgio);
 695         return err;
 696 }
 697
 698 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 699 {
 700         int ret;
 701
 702         ret = nfs_writepage_locked(page, wbc);
 703         if (ret != AOP_WRITEPAGE_ACTIVATE)
 704                 unlock_page(page);
 705         return ret;
 706 }
 707
 708 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 709 {
 710         int ret;
 711
 712         ret = nfs_do_writepage(page, wbc, data);
 713         if (ret != AOP_WRITEPAGE_ACTIVATE)
 714                 unlock_page(page);
 715         return ret;
 716 }
 717
 718 static void nfs_io_completion_commit(void *inode)
 719 {
 720         nfs_commit_inode(inode, 0);
 721 }
 722
 723 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 724 {
 725         struct inode *inode = mapping->host;
 726         struct nfs_pageio_descriptor pgio;
 727         struct nfs_io_completion *ioc;
 728         int err;
 729
 730         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 731
 732         ioc = nfs_io_completion_alloc(GFP_KERNEL);
 733         if (ioc)
 734                 nfs_io_completion_init(ioc, nfs_io_completion_commit, inode);
 735
 736         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc), false,
 737                                 &nfs_async_write_completion_ops);
 738         pgio.pg_io_completion = ioc;
 739         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 740         pgio.pg_error = 0;
 741         nfs_pageio_complete(&pgio);
 742         nfs_io_completion_put(ioc);
 743
 744         if (err < 0)
 745                 goto out_err;
 746         return 0;
 747 out_err:
 748         return err;
 749 }
 750
 751 /*
 752  * Insert a write request into an inode
 753  */
 754 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 755 {
 756         struct address_space *mapping = page_file_mapping(req->wb_page);
 757         struct nfs_inode *nfsi = NFS_I(inode);
 758
 759         WARN_ON_ONCE(req->wb_this_page != req);
 760
 761         /* Lock the request! */
 762         nfs_lock_request(req);
 763
 764         /*
 765          * Swap-space should not get truncated. Hence no need to plug the race
 766          * with invalidate/truncate.
 767          */
 768         spin_lock(&mapping->private_lock);
 769         if (!nfs_have_writebacks(inode) &&
 770             NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 771                 inode_inc_iversion_raw(inode);
 772         if (likely(!PageSwapCache(req->wb_page))) {
 773                 set_bit(PG_MAPPED, &req->wb_flags);
 774                 SetPagePrivate(req->wb_page);
 775                 set_page_private(req->wb_page, (unsigned long)req);
 776         }
 777         spin_unlock(&mapping->private_lock);
 778         atomic_long_inc(&nfsi->nrequests);
 779         /* this a head request for a page group - mark it as having an
 780          * extra reference so sub groups can follow suit.
 781          * This flag also informs pgio layer when to bump nrequests when
 782          * adding subrequests. */
 783         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 784         kref_get(&req->wb_kref);
 785 }
 786
 787 /*
 788  * Remove a write request from an inode
 789  */
 790 static void nfs_inode_remove_request(struct nfs_page *req)
 791 {
 792         struct address_space *mapping = page_file_mapping(req->wb_page);
 793         struct inode *inode = mapping->host;
 794         struct nfs_inode *nfsi = NFS_I(inode);
 795         struct nfs_page *head;
 796
 797         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
 798                 head = req->wb_head;
 799
 800                 spin_lock(&mapping->private_lock);
 801                 if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
 802                         set_page_private(head->wb_page, 0);
 803                         ClearPagePrivate(head->wb_page);
 804                         clear_bit(PG_MAPPED, &head->wb_flags);
 805                 }
 806                 spin_unlock(&mapping->private_lock);
 807         }
 808
 809         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags)) {
 810                 nfs_release_request(req);
 811                 atomic_long_dec(&nfsi->nrequests);
 812         }
 813 }
 814
 815 static void
 816 nfs_mark_request_dirty(struct nfs_page *req)
 817 {
 818         if (req->wb_page)
 819                 __set_page_dirty_nobuffers(req->wb_page);
 820 }
 821
 822 /*
 823  * nfs_page_search_commits_for_head_request_locked
 824  *
 825  * Search through commit lists on @inode for the head request for @page.
 826  * Must be called while holding the inode (which is cinfo) lock.
 827  *
 828  * Returns the head request if found, or NULL if not found.
 829  */
 830 static struct nfs_page *
 831 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 832                                                 struct page *page)
 833 {
 834         struct nfs_page *freq, *t;
 835         struct nfs_commit_info cinfo;
 836         struct inode *inode = &nfsi->vfs_inode;
 837
 838         nfs_init_cinfo_from_inode(&cinfo, inode);
 839
 840         /* search through pnfs commit lists */
 841         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
 842         if (freq)
 843                 return freq->wb_head;
 844
 845         /* Linearly search the commit list for the correct request */
 846         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
 847                 if (freq->wb_page == page)
 848                         return freq->wb_head;
 849         }
 850
 851         return NULL;
 852 }
 853
 854 /**
 855  * nfs_request_add_commit_list_locked - add request to a commit list
 856  * @req: pointer to a struct nfs_page
 857  * @dst: commit list head
 858  * @cinfo: holds list lock and accounting info
 859  *
 860  * This sets the PG_CLEAN bit, updates the cinfo count of
 861  * number of outstanding requests requiring a commit as well as
 862  * the MM page stats.
 863  *
 864  * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
 865  * nfs_page lock.
 866  */
 867 void
 868 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
 869                             struct nfs_commit_info *cinfo)
 870 {
 871         set_bit(PG_CLEAN, &req->wb_flags);
 872         nfs_list_add_request(req, dst);
 873         atomic_long_inc(&cinfo->mds->ncommit);
 874 }
 875 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 876
 877 /**
 878  * nfs_request_add_commit_list - add request to a commit list
 879  * @req: pointer to a struct nfs_page
 880  * @cinfo: holds list lock and accounting info
 881  *
 882  * This sets the PG_CLEAN bit, updates the cinfo count of
 883  * number of outstanding requests requiring a commit as well as
 884  * the MM page stats.
 885  *
 886  * The caller must _not_ hold the cinfo->lock, but must be
 887  * holding the nfs_page lock.
 888  */
 889 void
 890 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 891 {
 892         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 893         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
 894         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 895         if (req->wb_page)
 896                 nfs_mark_page_unstable(req->wb_page, cinfo);
 897 }
 898 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 899
 900 /**
 901  * nfs_request_remove_commit_list - Remove request from a commit list
 902  * @req: pointer to a nfs_page
 903  * @cinfo: holds list lock and accounting info
 904  *
 905  * This clears the PG_CLEAN bit, and updates the cinfo's count of
 906  * number of outstanding requests requiring a commit
 907  * It does not update the MM page stats.
 908  *
 909  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 910  */
 911 void
 912 nfs_request_remove_commit_list(struct nfs_page *req,
 913                                struct nfs_commit_info *cinfo)
 914 {
 915         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 916                 return;
 917         nfs_list_remove_request(req);
 918         atomic_long_dec(&cinfo->mds->ncommit);
 919 }
 920 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 921
 922 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 923                                       struct inode *inode)
 924 {
 925         cinfo->inode = inode;
 926         cinfo->mds = &NFS_I(inode)->commit_info;
 927         cinfo->ds = pnfs_get_ds_info(inode);
 928         cinfo->dreq = NULL;
 929         cinfo->completion_ops = &nfs_commit_completion_ops;
 930 }
 931
 932 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 933                     struct inode *inode,
 934                     struct nfs_direct_req *dreq)
 935 {
 936         if (dreq)
 937                 nfs_init_cinfo_from_dreq(cinfo, dreq);
 938         else
 939                 nfs_init_cinfo_from_inode(cinfo, inode);
 940 }
 941 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 942
 943 /*
 944  * Add a request to the inode's commit list.
 945  */
 946 void
 947 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 948                         struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 949 {
 950         if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 951                 return;
 952         nfs_request_add_commit_list(req, cinfo);
 953 }
 954
 955 static void
 956 nfs_clear_page_commit(struct page *page)
 957 {
 958         dec_node_page_state(page, NR_UNSTABLE_NFS);
 959         dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
 960                     WB_RECLAIMABLE);
 961 }
 962
 963 /* Called holding the request lock on @req */
 964 static void
 965 nfs_clear_request_commit(struct nfs_page *req)
 966 {
 967         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 968                 struct nfs_open_context *ctx = nfs_req_openctx(req);
 969                 struct inode *inode = d_inode(ctx->dentry);
 970                 struct nfs_commit_info cinfo;
 971
 972                 nfs_init_cinfo_from_inode(&cinfo, inode);
 973                 mutex_lock(&NFS_I(inode)->commit_mutex);
 974                 if (!pnfs_clear_request_commit(req, &cinfo)) {
 975                         nfs_request_remove_commit_list(req, &cinfo);
 976                 }
 977                 mutex_unlock(&NFS_I(inode)->commit_mutex);
 978                 nfs_clear_page_commit(req->wb_page);
 979         }
 980 }
 981
 982 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 983 {
 984         if (hdr->verf.committed == NFS_DATA_SYNC)
 985                 return hdr->lseg == NULL;
 986         return hdr->verf.committed != NFS_FILE_SYNC;
 987 }
 988
 989 static void nfs_async_write_init(struct nfs_pgio_header *hdr)
 990 {
 991         nfs_io_completion_get(hdr->io_completion);
 992 }
 993
 994 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 995 {
 996         struct nfs_commit_info cinfo;
 997         unsigned long bytes = 0;
 998
 999         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
1000                 goto out;
1001         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
1002         while (!list_empty(&hdr->pages)) {
1003                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1004
1005                 bytes += req->wb_bytes;
1006                 nfs_list_remove_request(req);
1007                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
1008                     (hdr->good_bytes < bytes)) {
1009                         nfs_set_pageerror(page_file_mapping(req->wb_page));
1010                         nfs_mapping_set_error(req->wb_page, hdr->error);
1011                         goto remove_req;
1012                 }
1013                 if (nfs_write_need_commit(hdr)) {
1014                         /* Reset wb_nio, since the write was successful. */
1015                         req->wb_nio = 0;
1016                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1017                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1018                                 hdr->pgio_mirror_idx);
1019                         goto next;
1020                 }
1021 remove_req:
1022                 nfs_inode_remove_request(req);
1023 next:
1024                 nfs_end_page_writeback(req);
1025                 nfs_release_request(req);
1026         }
1027 out:
1028         nfs_io_completion_put(hdr->io_completion);
1029         hdr->release(hdr);
1030 }
1031
1032 unsigned long
1033 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1034 {
1035         return atomic_long_read(&cinfo->mds->ncommit);
1036 }
1037
1038 /* NFS_I(cinfo->inode)->commit_mutex held by caller */
1039 int
1040 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1041                      struct nfs_commit_info *cinfo, int max)
1042 {
1043         struct nfs_page *req, *tmp;
1044         int ret = 0;
1045
1046         list_for_each_entry_safe(req, tmp, src, wb_list) {
1047                 kref_get(&req->wb_kref);
1048                 if (!nfs_lock_request(req)) {
1049                         nfs_release_request(req);
1050                         continue;
1051                 }
1052                 nfs_request_remove_commit_list(req, cinfo);
1053                 clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1054                 nfs_list_add_request(req, dst);
1055                 ret++;
1056                 if ((ret == max) && !cinfo->dreq)
1057                         break;
1058                 cond_resched();
1059         }
1060         return ret;
1061 }
1062 EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1063
1064 /*
1065  * nfs_scan_commit - Scan an inode for commit requests
1066  * @inode: NFS inode to scan
1067  * @dst: mds destination list
1068  * @cinfo: mds and ds lists of reqs ready to commit
1069  *
1070  * Moves requests from the inode's 'commit' request list.
1071  * The requests are *not* checked to ensure that they form a contiguous set.
1072  */
1073 int
1074 nfs_scan_commit(struct inode *inode, struct list_head *dst,
1075                 struct nfs_commit_info *cinfo)
1076 {
1077         int ret = 0;
1078
1079         if (!atomic_long_read(&cinfo->mds->ncommit))
1080                 return 0;
1081         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1082         if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1083                 const int max = INT_MAX;
1084
1085                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1086                                            cinfo, max);
1087                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1088         }
1089         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1090         return ret;
1091 }
1092
1093 /*
1094  * Search for an existing write request, and attempt to update
1095  * it to reflect a new dirty region on a given page.
1096  *
1097  * If the attempt fails, then the existing request is flushed out
1098  * to disk.
1099  */
1100 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1101                 struct page *page,
1102                 unsigned int offset,
1103                 unsigned int bytes)
1104 {
1105         struct nfs_page *req;
1106         unsigned int rqend;
1107         unsigned int end;
1108         int error;
1109
1110         end = offset + bytes;
1111
1112         req = nfs_lock_and_join_requests(page);
1113         if (IS_ERR_OR_NULL(req))
1114                 return req;
1115
1116         rqend = req->wb_offset + req->wb_bytes;
1117         /*
1118          * Tell the caller to flush out the request if
1119          * the offsets are non-contiguous.
1120          * Note: nfs_flush_incompatible() will already
1121          * have flushed out requests having wrong owners.
1122          */
1123         if (offset > rqend || end < req->wb_offset)
1124                 goto out_flushme;
1125
1126         /* Okay, the request matches. Update the region */
1127         if (offset < req->wb_offset) {
1128                 req->wb_offset = offset;
1129                 req->wb_pgbase = offset;
1130         }
1131         if (end > rqend)
1132                 req->wb_bytes = end - req->wb_offset;
1133         else
1134                 req->wb_bytes = rqend - req->wb_offset;
1135         req->wb_nio = 0;
1136         return req;
1137 out_flushme:
1138         /*
1139          * Note: we mark the request dirty here because
1140          * nfs_lock_and_join_requests() cannot preserve
1141          * commit flags, so we have to replay the write.
1142          */
1143         nfs_mark_request_dirty(req);
1144         nfs_unlock_and_release_request(req);
1145         error = nfs_wb_page(inode, page);
1146         return (error < 0) ? ERR_PTR(error) : NULL;
1147 }
1148
1149 /*
1150  * Try to update an existing write request, or create one if there is none.
1151  *
1152  * Note: Should always be called with the Page Lock held to prevent races
1153  * if we have to add a new request. Also assumes that the caller has
1154  * already called nfs_flush_incompatible() if necessary.
1155  */
1156 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1157                 struct page *page, unsigned int offset, unsigned int bytes)
1158 {
1159         struct inode *inode = page_file_mapping(page)->host;
1160         struct nfs_page *req;
1161
1162         req = nfs_try_to_update_request(inode, page, offset, bytes);
1163         if (req != NULL)
1164                 goto out;
1165         req = nfs_create_request(ctx, page, offset, bytes);
1166         if (IS_ERR(req))
1167                 goto out;
1168         nfs_inode_add_request(inode, req);
1169 out:
1170         return req;
1171 }
1172
1173 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1174                 unsigned int offset, unsigned int count)
1175 {
1176         struct nfs_page *req;
1177
1178         req = nfs_setup_write_request(ctx, page, offset, count);
1179         if (IS_ERR(req))
1180                 return PTR_ERR(req);
1181         /* Update file length */
1182         nfs_grow_file(page, offset, count);
1183         nfs_mark_uptodate(req);
1184         nfs_mark_request_dirty(req);
1185         nfs_unlock_and_release_request(req);
1186         return 0;
1187 }
1188
1189 int nfs_flush_incompatible(struct file *file, struct page *page)
1190 {
1191         struct nfs_open_context *ctx = nfs_file_open_context(file);
1192         struct nfs_lock_context *l_ctx;
1193         struct file_lock_context *flctx = file_inode(file)->i_flctx;
1194         struct nfs_page *req;
1195         int do_flush, status;
1196         /*
1197          * Look for a request corresponding to this page. If there
1198          * is one, and it belongs to another file, we flush it out
1199          * before we try to copy anything into the page. Do this
1200          * due to the lack of an ACCESS-type call in NFSv2.
1201          * Also do the same if we find a request from an existing
1202          * dropped page.
1203          */
1204         do {
1205                 req = nfs_page_find_head_request(page);
1206                 if (req == NULL)
1207                         return 0;
1208                 l_ctx = req->wb_lock_context;
1209                 do_flush = req->wb_page != page ||
1210                         !nfs_match_open_context(nfs_req_openctx(req), ctx);
1211                 if (l_ctx && flctx &&
1212                     !(list_empty_careful(&flctx->flc_posix) &&
1213                       list_empty_careful(&flctx->flc_flock))) {
1214                         do_flush |= l_ctx->lockowner != current->files;
1215                 }
1216                 nfs_release_request(req);
1217                 if (!do_flush)
1218                         return 0;
1219                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1220         } while (status == 0);
1221         return status;
1222 }
1223
1224 /*
1225  * Avoid buffered writes when a open context credential's key would
1226  * expire soon.
1227  *
1228  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1229  *
1230  * Return 0 and set a credential flag which triggers the inode to flush
1231  * and performs  NFS_FILE_SYNC writes if the key will expired within
1232  * RPC_KEY_EXPIRE_TIMEO.
1233  */
1234 int
1235 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1236 {
1237         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1238
1239         if (nfs_ctx_key_to_expire(ctx, inode) &&
1240             !ctx->ll_cred)
1241                 /* Already expired! */
1242                 return -EACCES;
1243         return 0;
1244 }
1245
1246 /*
1247  * Test if the open context credential key is marked to expire soon.
1248  */
1249 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1250 {
1251         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1252         struct rpc_cred *cred = ctx->ll_cred;
1253         struct auth_cred acred = {
1254                 .cred = ctx->cred,
1255         };
1256
1257         if (cred && !cred->cr_ops->crmatch(&acred, cred, 0)) {
1258                 put_rpccred(cred);
1259                 ctx->ll_cred = NULL;
1260                 cred = NULL;
1261         }
1262         if (!cred)
1263                 cred = auth->au_ops->lookup_cred(auth, &acred, 0);
1264         if (!cred || IS_ERR(cred))
1265                 return true;
1266         ctx->ll_cred = cred;
1267         return !!(cred->cr_ops->crkey_timeout &&
1268                   cred->cr_ops->crkey_timeout(cred));
1269 }
1270
1271 /*
1272  * If the page cache is marked as unsafe or invalid, then we can't rely on
1273  * the PageUptodate() flag. In this case, we will need to turn off
1274  * write optimisations that depend on the page contents being correct.
1275  */
1276 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
1277 {
1278         struct nfs_inode *nfsi = NFS_I(inode);
1279
1280         if (nfs_have_delegated_attributes(inode))
1281                 goto out;
1282         if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
1283                 return false;
1284         smp_rmb();
1285         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
1286                 return false;
1287 out:
1288         if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
1289                 return false;
1290         return PageUptodate(page) != 0;
1291 }
1292
1293 static bool
1294 is_whole_file_wrlock(struct file_lock *fl)
1295 {
1296         return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1297                         fl->fl_type == F_WRLCK;
1298 }
1299
1300 /* If we know the page is up to date, and we're not using byte range locks (or
1301  * if we have the whole file locked for writing), it may be more efficient to
1302  * extend the write to cover the entire page in order to avoid fragmentation
1303  * inefficiencies.
1304  *
1305  * If the file is opened for synchronous writes then we can just skip the rest
1306  * of the checks.
1307  */
1308 static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
1309 {
1310         int ret;
1311         struct file_lock_context *flctx = inode->i_flctx;
1312         struct file_lock *fl;
1313
1314         if (file->f_flags & O_DSYNC)
1315                 return 0;
1316         if (!nfs_write_pageuptodate(page, inode))
1317                 return 0;
1318         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1319                 return 1;
1320         if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1321                        list_empty_careful(&flctx->flc_posix)))
1322                 return 1;
1323
1324         /* Check to see if there are whole file write locks */
1325         ret = 0;
1326         spin_lock(&flctx->flc_lock);
1327         if (!list_empty(&flctx->flc_posix)) {
1328                 fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1329                                         fl_list);
1330                 if (is_whole_file_wrlock(fl))
1331                         ret = 1;
1332         } else if (!list_empty(&flctx->flc_flock)) {
1333                 fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1334                                         fl_list);
1335                 if (fl->fl_type == F_WRLCK)
1336                         ret = 1;
1337         }
1338         spin_unlock(&flctx->flc_lock);
1339         return ret;
1340 }
1341
1342 /*
1343  * Update and possibly write a cached page of an NFS file.
1344  *
1345  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1346  * things with a page scheduled for an RPC call (e.g. invalidate it).
1347  */
1348 int nfs_updatepage(struct file *file, struct page *page,
1349                 unsigned int offset, unsigned int count)
1350 {
1351         struct nfs_open_context *ctx = nfs_file_open_context(file);
1352         struct address_space *mapping = page_file_mapping(page);
1353         struct inode    *inode = mapping->host;
1354         int             status = 0;
1355
1356         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1357
1358         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1359                 file, count, (long long)(page_file_offset(page) + offset));
1360
1361         if (!count)
1362                 goto out;
1363
1364         if (nfs_can_extend_write(file, page, inode)) {
1365                 count = max(count + offset, nfs_page_length(page));
1366                 offset = 0;
1367         }
1368
1369         status = nfs_writepage_setup(ctx, page, offset, count);
1370         if (status < 0)
1371                 nfs_set_pageerror(mapping);
1372         else
1373                 __set_page_dirty_nobuffers(page);
1374 out:
1375         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1376                         status, (long long)i_size_read(inode));
1377         return status;
1378 }
1379
1380 static int flush_task_priority(int how)
1381 {
1382         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1383                 case FLUSH_HIGHPRI:
1384                         return RPC_PRIORITY_HIGH;
1385                 case FLUSH_LOWPRI:
1386                         return RPC_PRIORITY_LOW;
1387         }
1388         return RPC_PRIORITY_NORMAL;
1389 }
1390
1391 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1392                                struct rpc_message *msg,
1393                                const struct nfs_rpc_ops *rpc_ops,
1394                                struct rpc_task_setup *task_setup_data, int how)
1395 {
1396         int priority = flush_task_priority(how);
1397
1398         task_setup_data->priority = priority;
1399         rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1400         trace_nfs_initiate_write(hdr->inode, hdr->io_start, hdr->good_bytes,
1401                                  hdr->args.stable);
1402 }
1403
1404 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1405  * call this on each, which will prepare them to be retried on next
1406  * writeback using standard nfs.
1407  */
1408 static void nfs_redirty_request(struct nfs_page *req)
1409 {
1410         /* Bump the transmission count */
1411         req->wb_nio++;
1412         nfs_mark_request_dirty(req);
1413         set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1414         nfs_end_page_writeback(req);
1415         nfs_release_request(req);
1416 }
1417
1418 static void nfs_async_write_error(struct list_head *head, int error)
1419 {
1420         struct nfs_page *req;
1421
1422         while (!list_empty(head)) {
1423                 req = nfs_list_entry(head->next);
1424                 nfs_list_remove_request(req);
1425                 if (nfs_error_is_fatal_on_server(error))
1426                         nfs_write_error(req, error);
1427                 else
1428                         nfs_redirty_request(req);
1429         }
1430 }
1431
1432 static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1433 {
1434         nfs_async_write_error(&hdr->pages, 0);
1435         filemap_fdatawrite_range(hdr->inode->i_mapping, hdr->args.offset,
1436                         hdr->args.offset + hdr->args.count - 1);
1437 }
1438
1439 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1440         .init_hdr = nfs_async_write_init,
1441         .error_cleanup = nfs_async_write_error,
1442         .completion = nfs_write_completion,
1443         .reschedule_io = nfs_async_write_reschedule_io,
1444 };
1445
1446 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1447                                struct inode *inode, int ioflags, bool force_mds,
1448                                const struct nfs_pgio_completion_ops *compl_ops)
1449 {
1450         struct nfs_server *server = NFS_SERVER(inode);
1451         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1452
1453 #ifdef CONFIG_NFS_V4_1
1454         if (server->pnfs_curr_ld && !force_mds)
1455                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1456 #endif
1457         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1458                         server->wsize, ioflags);
1459 }
1460 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1461
1462 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1463 {
1464         struct nfs_pgio_mirror *mirror;
1465
1466         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1467                 pgio->pg_ops->pg_cleanup(pgio);
1468
1469         pgio->pg_ops = &nfs_pgio_rw_ops;
1470
1471         nfs_pageio_stop_mirroring(pgio);
1472
1473         mirror = &pgio->pg_mirrors[0];
1474         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1475 }
1476 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1477
1478
1479 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1480 {
1481         struct nfs_commit_data *data = calldata;
1482
1483         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1484 }
1485
1486 /*
1487  * Special version of should_remove_suid() that ignores capabilities.
1488  */
1489 static int nfs_should_remove_suid(const struct inode *inode)
1490 {
1491         umode_t mode = inode->i_mode;
1492         int kill = 0;
1493
1494         /* suid always must be killed */
1495         if (unlikely(mode & S_ISUID))
1496                 kill = ATTR_KILL_SUID;
1497
1498         /*
1499          * sgid without any exec bits is just a mandatory locking mark; leave
1500          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1501          */
1502         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1503                 kill |= ATTR_KILL_SGID;
1504
1505         if (unlikely(kill && S_ISREG(mode)))
1506                 return kill;
1507
1508         return 0;
1509 }
1510
1511 static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1512                 struct nfs_fattr *fattr)
1513 {
1514         struct nfs_pgio_args *argp = &hdr->args;
1515         struct nfs_pgio_res *resp = &hdr->res;
1516         u64 size = argp->offset + resp->count;
1517
1518         if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1519                 fattr->size = size;
1520         if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1521                 fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1522                 return;
1523         }
1524         if (size != fattr->size)
1525                 return;
1526         /* Set attribute barrier */
1527         nfs_fattr_set_barrier(fattr);
1528         /* ...and update size */
1529         fattr->valid |= NFS_ATTR_FATTR_SIZE;
1530 }
1531
1532 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1533 {
1534         struct nfs_fattr *fattr = &hdr->fattr;
1535         struct inode *inode = hdr->inode;
1536
1537         spin_lock(&inode->i_lock);
1538         nfs_writeback_check_extend(hdr, fattr);
1539         nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1540         spin_unlock(&inode->i_lock);
1541 }
1542 EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1543
1544 /*
1545  * This function is called when the WRITE call is complete.
1546  */
1547 static int nfs_writeback_done(struct rpc_task *task,
1548                               struct nfs_pgio_header *hdr,
1549                               struct inode *inode)
1550 {
1551         int status;
1552
1553         /*
1554          * ->write_done will attempt to use post-op attributes to detect
1555          * conflicting writes by other clients.  A strict interpretation
1556          * of close-to-open would allow us to continue caching even if
1557          * another writer had changed the file, but some applications
1558          * depend on tighter cache coherency when writing.
1559          */
1560         status = NFS_PROTO(inode)->write_done(task, hdr);
1561         if (status != 0)
1562                 return status;
1563
1564         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1565         trace_nfs_writeback_done(inode, task->tk_status,
1566                                  hdr->args.offset, hdr->res.verf);
1567
1568         if (hdr->res.verf->committed < hdr->args.stable &&
1569             task->tk_status >= 0) {
1570                 /* We tried a write call, but the server did not
1571                  * commit data to stable storage even though we
1572                  * requested it.
1573                  * Note: There is a known bug in Tru64 < 5.0 in which
1574                  *       the server reports NFS_DATA_SYNC, but performs
1575                  *       NFS_FILE_SYNC. We therefore implement this checking
1576                  *       as a dprintk() in order to avoid filling syslog.
1577                  */
1578                 static unsigned long    complain;
1579
1580                 /* Note this will print the MDS for a DS write */
1581                 if (time_before(complain, jiffies)) {
1582                         dprintk("NFS:       faulty NFS server %s:"
1583                                 " (committed = %d) != (stable = %d)\n",
1584                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1585                                 hdr->res.verf->committed, hdr->args.stable);
1586                         complain = jiffies + 300 * HZ;
1587                 }
1588         }
1589
1590         /* Deal with the suid/sgid bit corner case */
1591         if (nfs_should_remove_suid(inode)) {
1592                 spin_lock(&inode->i_lock);
1593                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_OTHER;
1594                 spin_unlock(&inode->i_lock);
1595         }
1596         return 0;
1597 }
1598
1599 /*
1600  * This function is called when the WRITE call is complete.
1601  */
1602 static void nfs_writeback_result(struct rpc_task *task,
1603                                  struct nfs_pgio_header *hdr)
1604 {
1605         struct nfs_pgio_args    *argp = &hdr->args;
1606         struct nfs_pgio_res     *resp = &hdr->res;
1607
1608         if (resp->count < argp->count) {
1609                 static unsigned long    complain;
1610
1611                 /* This a short write! */
1612                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1613
1614                 /* Has the server at least made some progress? */
1615                 if (resp->count == 0) {
1616                         if (time_before(complain, jiffies)) {
1617                                 printk(KERN_WARNING
1618                                        "NFS: Server wrote zero bytes, expected %u.\n",
1619                                        argp->count);
1620                                 complain = jiffies + 300 * HZ;
1621                         }
1622                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1623                         task->tk_status = -EIO;
1624                         return;
1625                 }
1626
1627                 /* For non rpc-based layout drivers, retry-through-MDS */
1628                 if (!task->tk_ops) {
1629                         hdr->pnfs_error = -EAGAIN;
1630                         return;
1631                 }
1632
1633                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1634                 if (resp->verf->committed != NFS_UNSTABLE) {
1635                         /* Resend from where the server left off */
1636                         hdr->mds_offset += resp->count;
1637                         argp->offset += resp->count;
1638                         argp->pgbase += resp->count;
1639                         argp->count -= resp->count;
1640                 } else {
1641                         /* Resend as a stable write in order to avoid
1642                          * headaches in the case of a server crash.
1643                          */
1644                         argp->stable = NFS_FILE_SYNC;
1645                 }
1646                 rpc_restart_call_prepare(task);
1647         }
1648 }
1649
1650 static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1651 {
1652         return wait_var_event_killable(&cinfo->rpcs_out,
1653                                        !atomic_read(&cinfo->rpcs_out));
1654 }
1655
1656 static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1657 {
1658         atomic_inc(&cinfo->rpcs_out);
1659 }
1660
1661 static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1662 {
1663         if (atomic_dec_and_test(&cinfo->rpcs_out))
1664                 wake_up_var(&cinfo->rpcs_out);
1665 }
1666
1667 void nfs_commitdata_release(struct nfs_commit_data *data)
1668 {
1669         put_nfs_open_context(data->context);
1670         nfs_commit_free(data);
1671 }
1672 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1673
1674 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1675                         const struct nfs_rpc_ops *nfs_ops,
1676                         const struct rpc_call_ops *call_ops,
1677                         int how, int flags)
1678 {
1679         struct rpc_task *task;
1680         int priority = flush_task_priority(how);
1681         struct rpc_message msg = {
1682                 .rpc_argp = &data->args,
1683                 .rpc_resp = &data->res,
1684                 .rpc_cred = data->cred,
1685         };
1686         struct rpc_task_setup task_setup_data = {
1687                 .task = &data->task,
1688                 .rpc_client = clnt,
1689                 .rpc_message = &msg,
1690                 .callback_ops = call_ops,
1691                 .callback_data = data,
1692                 .workqueue = nfsiod_workqueue,
1693                 .flags = RPC_TASK_ASYNC | flags,
1694                 .priority = priority,
1695         };
1696         /* Set up the initial task struct.  */
1697         nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1698         trace_nfs_initiate_commit(data);
1699
1700         dprintk("NFS: initiated commit call\n");
1701
1702         task = rpc_run_task(&task_setup_data);
1703         if (IS_ERR(task))
1704                 return PTR_ERR(task);
1705         if (how & FLUSH_SYNC)
1706                 rpc_wait_for_completion_task(task);
1707         rpc_put_task(task);
1708         return 0;
1709 }
1710 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1711
1712 static loff_t nfs_get_lwb(struct list_head *head)
1713 {
1714         loff_t lwb = 0;
1715         struct nfs_page *req;
1716
1717         list_for_each_entry(req, head, wb_list)
1718                 if (lwb < (req_offset(req) + req->wb_bytes))
1719                         lwb = req_offset(req) + req->wb_bytes;
1720
1721         return lwb;
1722 }
1723
1724 /*
1725  * Set up the argument/result storage required for the RPC call.
1726  */
1727 void nfs_init_commit(struct nfs_commit_data *data,
1728                      struct list_head *head,
1729                      struct pnfs_layout_segment *lseg,
1730                      struct nfs_commit_info *cinfo)
1731 {
1732         struct nfs_page *first = nfs_list_entry(head->next);
1733         struct nfs_open_context *ctx = nfs_req_openctx(first);
1734         struct inode *inode = d_inode(ctx->dentry);
1735
1736         /* Set up the RPC argument and reply structs
1737          * NB: take care not to mess about with data->commit et al. */
1738
1739         list_splice_init(head, &data->pages);
1740
1741         data->inode       = inode;
1742         data->cred        = ctx->cred;
1743         data->lseg        = lseg; /* reference transferred */
1744         /* only set lwb for pnfs commit */
1745         if (lseg)
1746                 data->lwb = nfs_get_lwb(&data->pages);
1747         data->mds_ops     = &nfs_commit_ops;
1748         data->completion_ops = cinfo->completion_ops;
1749         data->dreq        = cinfo->dreq;
1750
1751         data->args.fh     = NFS_FH(data->inode);
1752         /* Note: we always request a commit of the entire inode */
1753         data->args.offset = 0;
1754         data->args.count  = 0;
1755         data->context     = get_nfs_open_context(ctx);
1756         data->res.fattr   = &data->fattr;
1757         data->res.verf    = &data->verf;
1758         nfs_fattr_init(&data->fattr);
1759 }
1760 EXPORT_SYMBOL_GPL(nfs_init_commit);
1761
1762 void nfs_retry_commit(struct list_head *page_list,
1763                       struct pnfs_layout_segment *lseg,
1764                       struct nfs_commit_info *cinfo,
1765                       u32 ds_commit_idx)
1766 {
1767         struct nfs_page *req;
1768
1769         while (!list_empty(page_list)) {
1770                 req = nfs_list_entry(page_list->next);
1771                 nfs_list_remove_request(req);
1772                 nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1773                 if (!cinfo->dreq)
1774                         nfs_clear_page_commit(req->wb_page);
1775                 nfs_unlock_and_release_request(req);
1776         }
1777 }
1778 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1779
1780 static void
1781 nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1782                 struct nfs_page *req)
1783 {
1784         __set_page_dirty_nobuffers(req->wb_page);
1785 }
1786
1787 /*
1788  * Commit dirty pages
1789  */
1790 static int
1791 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1792                 struct nfs_commit_info *cinfo)
1793 {
1794         struct nfs_commit_data  *data;
1795
1796         /* another commit raced with us */
1797         if (list_empty(head))
1798                 return 0;
1799
1800         data = nfs_commitdata_alloc(true);
1801
1802         /* Set up the argument struct */
1803         nfs_init_commit(data, head, NULL, cinfo);
1804         atomic_inc(&cinfo->mds->rpcs_out);
1805         return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1806                                    data->mds_ops, how, 0);
1807 }
1808
1809 /*
1810  * COMMIT call returned
1811  */
1812 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1813 {
1814         struct nfs_commit_data  *data = calldata;
1815
1816         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1817                                 task->tk_pid, task->tk_status);
1818
1819         /* Call the NFS version-specific code */
1820         NFS_PROTO(data->inode)->commit_done(task, data);
1821         trace_nfs_commit_done(data);
1822 }
1823
1824 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1825 {
1826         const struct nfs_writeverf *verf = data->res.verf;
1827         struct nfs_page *req;
1828         int status = data->task.tk_status;
1829         struct nfs_commit_info cinfo;
1830         struct nfs_server *nfss;
1831
1832         while (!list_empty(&data->pages)) {
1833                 req = nfs_list_entry(data->pages.next);
1834                 nfs_list_remove_request(req);
1835                 if (req->wb_page)
1836                         nfs_clear_page_commit(req->wb_page);
1837
1838                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1839                         nfs_req_openctx(req)->dentry->d_sb->s_id,
1840                         (unsigned long long)NFS_FILEID(d_inode(nfs_req_openctx(req)->dentry)),
1841                         req->wb_bytes,
1842                         (long long)req_offset(req));
1843                 if (status < 0) {
1844                         if (req->wb_page) {
1845                                 nfs_mapping_set_error(req->wb_page, status);
1846                                 nfs_inode_remove_request(req);
1847                         }
1848                         dprintk_cont(", error = %d\n", status);
1849                         goto next;
1850                 }
1851
1852                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1853                  * returned by the server against all stored verfs. */
1854                 if (verf->committed > NFS_UNSTABLE &&
1855                     !nfs_write_verifier_cmp(&req->wb_verf, &verf->verifier)) {
1856                         /* We have a match */
1857                         if (req->wb_page)
1858                                 nfs_inode_remove_request(req);
1859                         dprintk_cont(" OK\n");
1860                         goto next;
1861                 }
1862                 /* We have a mismatch. Write the page again */
1863                 dprintk_cont(" mismatch\n");
1864                 nfs_mark_request_dirty(req);
1865                 set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1866         next:
1867                 nfs_unlock_and_release_request(req);
1868                 /* Latency breaker */
1869                 cond_resched();
1870         }
1871         nfss = NFS_SERVER(data->inode);
1872         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1873                 clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
1874
1875         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1876         nfs_commit_end(cinfo.mds);
1877 }
1878
1879 static void nfs_commit_release(void *calldata)
1880 {
1881         struct nfs_commit_data *data = calldata;
1882
1883         data->completion_ops->completion(data);
1884         nfs_commitdata_release(calldata);
1885 }
1886
1887 static const struct rpc_call_ops nfs_commit_ops = {
1888         .rpc_call_prepare = nfs_commit_prepare,
1889         .rpc_call_done = nfs_commit_done,
1890         .rpc_release = nfs_commit_release,
1891 };
1892
1893 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1894         .completion = nfs_commit_release_pages,
1895         .resched_write = nfs_commit_resched_write,
1896 };
1897
1898 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1899                             int how, struct nfs_commit_info *cinfo)
1900 {
1901         int status;
1902
1903         status = pnfs_commit_list(inode, head, how, cinfo);
1904         if (status == PNFS_NOT_ATTEMPTED)
1905                 status = nfs_commit_list(inode, head, how, cinfo);
1906         return status;
1907 }
1908
1909 static int __nfs_commit_inode(struct inode *inode, int how,
1910                 struct writeback_control *wbc)
1911 {
1912         LIST_HEAD(head);
1913         struct nfs_commit_info cinfo;
1914         int may_wait = how & FLUSH_SYNC;
1915         int ret, nscan;
1916
1917         how &= ~FLUSH_SYNC;
1918         nfs_init_cinfo_from_inode(&cinfo, inode);
1919         nfs_commit_begin(cinfo.mds);
1920         for (;;) {
1921                 ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1922                 if (ret <= 0)
1923                         break;
1924                 ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1925                 if (ret < 0)
1926                         break;
1927                 ret = 0;
1928                 if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1929                         if (nscan < wbc->nr_to_write)
1930                                 wbc->nr_to_write -= nscan;
1931                         else
1932                                 wbc->nr_to_write = 0;
1933                 }
1934                 if (nscan < INT_MAX)
1935                         break;
1936                 cond_resched();
1937         }
1938         nfs_commit_end(cinfo.mds);
1939         if (ret || !may_wait)
1940                 return ret;
1941         return wait_on_commit(cinfo.mds);
1942 }
1943
1944 int nfs_commit_inode(struct inode *inode, int how)
1945 {
1946         return __nfs_commit_inode(inode, how, NULL);
1947 }
1948 EXPORT_SYMBOL_GPL(nfs_commit_inode);
1949
1950 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1951 {
1952         struct nfs_inode *nfsi = NFS_I(inode);
1953         int flags = FLUSH_SYNC;
1954         int ret = 0;
1955
1956         if (wbc->sync_mode == WB_SYNC_NONE) {
1957                 /* no commits means nothing needs to be done */
1958                 if (!atomic_long_read(&nfsi->commit_info.ncommit))
1959                         goto check_requests_outstanding;
1960
1961                 /* Don't commit yet if this is a non-blocking flush and there
1962                  * are a lot of outstanding writes for this mapping.
1963                  */
1964                 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1965                         goto out_mark_dirty;
1966
1967                 /* don't wait for the COMMIT response */
1968                 flags = 0;
1969         }
1970
1971         ret = __nfs_commit_inode(inode, flags, wbc);
1972         if (!ret) {
1973                 if (flags & FLUSH_SYNC)
1974                         return 0;
1975         } else if (atomic_long_read(&nfsi->commit_info.ncommit))
1976                 goto out_mark_dirty;
1977
1978 check_requests_outstanding:
1979         if (!atomic_read(&nfsi->commit_info.rpcs_out))
1980                 return ret;
1981 out_mark_dirty:
1982         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1983         return ret;
1984 }
1985 EXPORT_SYMBOL_GPL(nfs_write_inode);
1986
1987 /*
1988  * Wrapper for filemap_write_and_wait_range()
1989  *
1990  * Needed for pNFS in order to ensure data becomes visible to the
1991  * client.
1992  */
1993 int nfs_filemap_write_and_wait_range(struct address_space *mapping,
1994                 loff_t lstart, loff_t lend)
1995 {
1996         int ret;
1997
1998         ret = filemap_write_and_wait_range(mapping, lstart, lend);
1999         if (ret == 0)
2000                 ret = pnfs_sync_inode(mapping->host, true);
2001         return ret;
2002 }
2003 EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
2004
2005 /*
2006  * flush the inode to disk.
2007  */
2008 int nfs_wb_all(struct inode *inode)
2009 {
2010         int ret;
2011
2012         trace_nfs_writeback_inode_enter(inode);
2013
2014         ret = filemap_write_and_wait(inode->i_mapping);
2015         if (ret)
2016                 goto out;
2017         ret = nfs_commit_inode(inode, FLUSH_SYNC);
2018         if (ret < 0)
2019                 goto out;
2020         pnfs_sync_inode(inode, true);
2021         ret = 0;
2022
2023 out:
2024         trace_nfs_writeback_inode_exit(inode, ret);
2025         return ret;
2026 }
2027 EXPORT_SYMBOL_GPL(nfs_wb_all);
2028
2029 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
2030 {
2031         struct nfs_page *req;
2032         int ret = 0;
2033
2034         wait_on_page_writeback(page);
2035
2036         /* blocking call to cancel all requests and join to a single (head)
2037          * request */
2038         req = nfs_lock_and_join_requests(page);
2039
2040         if (IS_ERR(req)) {
2041                 ret = PTR_ERR(req);
2042         } else if (req) {
2043                 /* all requests from this page have been cancelled by
2044                  * nfs_lock_and_join_requests, so just remove the head
2045                  * request from the inode / page_private pointer and
2046                  * release it */
2047                 nfs_inode_remove_request(req);
2048                 nfs_unlock_and_release_request(req);
2049         }
2050
2051         return ret;
2052 }
2053
2054 /*
2055  * Write back all requests on one page - we do this before reading it.
2056  */
2057 int nfs_wb_page(struct inode *inode, struct page *page)
2058 {
2059         loff_t range_start = page_file_offset(page);
2060         loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2061         struct writeback_control wbc = {
2062                 .sync_mode = WB_SYNC_ALL,
2063                 .nr_to_write = 0,
2064                 .range_start = range_start,
2065                 .range_end = range_end,
2066         };
2067         int ret;
2068
2069         trace_nfs_writeback_page_enter(inode);
2070
2071         for (;;) {
2072                 wait_on_page_writeback(page);
2073                 if (clear_page_dirty_for_io(page)) {
2074                         ret = nfs_writepage_locked(page, &wbc);
2075                         if (ret < 0)
2076                                 goto out_error;
2077                         continue;
2078                 }
2079                 ret = 0;
2080                 if (!PagePrivate(page))
2081                         break;
2082                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
2083                 if (ret < 0)
2084                         goto out_error;
2085         }
2086 out_error:
2087         trace_nfs_writeback_page_exit(inode, ret);
2088         return ret;
2089 }
2090
2091 #ifdef CONFIG_MIGRATION
2092 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
2093                 struct page *page, enum migrate_mode mode)
2094 {
2095         /*
2096          * If PagePrivate is set, then the page is currently associated with
2097          * an in-progress read or write request. Don't try to migrate it.
2098          *
2099          * FIXME: we could do this in principle, but we'll need a way to ensure
2100          *        that we can safely release the inode reference while holding
2101          *        the page lock.
2102          */
2103         if (PagePrivate(page))
2104                 return -EBUSY;
2105
2106         if (!nfs_fscache_release_page(page, GFP_KERNEL))
2107                 return -EBUSY;
2108
2109         return migrate_page(mapping, newpage, page, mode);
2110 }
2111 #endif
2112
2113 int __init nfs_init_writepagecache(void)
2114 {
2115         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2116                                              sizeof(struct nfs_pgio_header),
2117                                              0, SLAB_HWCACHE_ALIGN,
2118                                              NULL);
2119         if (nfs_wdata_cachep == NULL)
2120                 return -ENOMEM;
2121
2122         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2123                                                      nfs_wdata_cachep);
2124         if (nfs_wdata_mempool == NULL)
2125                 goto out_destroy_write_cache;
2126
2127         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2128                                              sizeof(struct nfs_commit_data),
2129                                              0, SLAB_HWCACHE_ALIGN,
2130                                              NULL);
2131         if (nfs_cdata_cachep == NULL)
2132                 goto out_destroy_write_mempool;
2133
2134         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2135                                                       nfs_cdata_cachep);
2136         if (nfs_commit_mempool == NULL)
2137                 goto out_destroy_commit_cache;
2138
2139         /*
2140          * NFS congestion size, scale with available memory.
2141          *
2142          *  64MB:    8192k
2143          * 128MB:   11585k
2144          * 256MB:   16384k
2145          * 512MB:   23170k
2146          *   1GB:   32768k
2147          *   2GB:   46340k
2148          *   4GB:   65536k
2149          *   8GB:   92681k
2150          *  16GB:  131072k
2151          *
2152          * This allows larger machines to have larger/more transfers.
2153          * Limit the default to 256M
2154          */
2155         nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2156         if (nfs_congestion_kb > 256*1024)
2157                 nfs_congestion_kb = 256*1024;
2158
2159         return 0;
2160
2161 out_destroy_commit_cache:
2162         kmem_cache_destroy(nfs_cdata_cachep);
2163 out_destroy_write_mempool:
2164         mempool_destroy(nfs_wdata_mempool);
2165 out_destroy_write_cache:
2166         kmem_cache_destroy(nfs_wdata_cachep);
2167         return -ENOMEM;
2168 }
2169
2170 void nfs_destroy_writepagecache(void)
2171 {
2172         mempool_destroy(nfs_commit_mempool);
2173         kmem_cache_destroy(nfs_cdata_cachep);
2174         mempool_destroy(nfs_wdata_mempool);
2175         kmem_cache_destroy(nfs_wdata_cachep);
2176 }
2177
2178 static const struct nfs_rw_ops nfs_rw_write_ops = {
2179         .rw_alloc_header        = nfs_writehdr_alloc,
2180         .rw_free_header         = nfs_writehdr_free,
2181         .rw_done                = nfs_writeback_done,
2182         .rw_result              = nfs_writeback_result,
2183         .rw_initiate            = nfs_initiate_write,
2184 };