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         nfs_zap_mapping(mapping->host, mapping);
 247 }
 248
 249 static void nfs_mapping_set_error(struct page *page, int error)
 250 {
 251         SetPageError(page);
 252         mapping_set_error(page_file_mapping(page), error);
 253 }
 254
 255 /*
 256  * nfs_page_group_search_locked
 257  * @head - head request of page group
 258  * @page_offset - offset into page
 259  *
 260  * Search page group with head @head to find a request that contains the
 261  * page offset @page_offset.
 262  *
 263  * Returns a pointer to the first matching nfs request, or NULL if no
 264  * match is found.
 265  *
 266  * Must be called with the page group lock held
 267  */
 268 static struct nfs_page *
 269 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
 270 {
 271         struct nfs_page *req;
 272
 273         req = head;
 274         do {
 275                 if (page_offset >= req->wb_pgbase &&
 276                     page_offset < (req->wb_pgbase + req->wb_bytes))
 277                         return req;
 278
 279                 req = req->wb_this_page;
 280         } while (req != head);
 281
 282         return NULL;
 283 }
 284
 285 /*
 286  * nfs_page_group_covers_page
 287  * @head - head request of page group
 288  *
 289  * Return true if the page group with head @head covers the whole page,
 290  * returns false otherwise
 291  */
 292 static bool nfs_page_group_covers_page(struct nfs_page *req)
 293 {
 294         struct nfs_page *tmp;
 295         unsigned int pos = 0;
 296         unsigned int len = nfs_page_length(req->wb_page);
 297
 298         nfs_page_group_lock(req);
 299
 300         for (;;) {
 301                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
 302                 if (!tmp)
 303                         break;
 304                 pos = tmp->wb_pgbase + tmp->wb_bytes;
 305         }
 306
 307         nfs_page_group_unlock(req);
 308         return pos >= len;
 309 }
 310
 311 /* We can set the PG_uptodate flag if we see that a write request
 312  * covers the full page.
 313  */
 314 static void nfs_mark_uptodate(struct nfs_page *req)
 315 {
 316         if (PageUptodate(req->wb_page))
 317                 return;
 318         if (!nfs_page_group_covers_page(req))
 319                 return;
 320         SetPageUptodate(req->wb_page);
 321 }
 322
 323 static int wb_priority(struct writeback_control *wbc)
 324 {
 325         int ret = 0;
 326
 327         if (wbc->sync_mode == WB_SYNC_ALL)
 328                 ret = FLUSH_COND_STABLE;
 329         return ret;
 330 }
 331
 332 /*
 333  * NFS congestion control
 334  */
 335
 336 int nfs_congestion_kb;
 337
 338 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 339 #define NFS_CONGESTION_OFF_THRESH       \
 340         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 341
 342 static void nfs_set_page_writeback(struct page *page)
 343 {
 344         struct inode *inode = page_file_mapping(page)->host;
 345         struct nfs_server *nfss = NFS_SERVER(inode);
 346         int ret = test_set_page_writeback(page);
 347
 348         WARN_ON_ONCE(ret != 0);
 349
 350         if (atomic_long_inc_return(&nfss->writeback) >
 351                         NFS_CONGESTION_ON_THRESH)
 352                 set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 353 }
 354
 355 static void nfs_end_page_writeback(struct nfs_page *req)
 356 {
 357         struct inode *inode = page_file_mapping(req->wb_page)->host;
 358         struct nfs_server *nfss = NFS_SERVER(inode);
 359         bool is_done;
 360
 361         is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
 362         nfs_unlock_request(req);
 363         if (!is_done)
 364                 return;
 365
 366         end_page_writeback(req->wb_page);
 367         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 368                 clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 369 }
 370
 371 /*
 372  * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
 373  *
 374  * this is a helper function for nfs_lock_and_join_requests
 375  *
 376  * @inode - inode associated with request page group, must be holding inode lock
 377  * @head  - head request of page group, must be holding head lock
 378  * @req   - request that couldn't lock and needs to wait on the req bit lock
 379  *
 380  * NOTE: this must be called holding page_group bit lock
 381  *       which will be released before returning.
 382  *
 383  * returns 0 on success, < 0 on error.
 384  */
 385 static void
 386 nfs_unroll_locks(struct inode *inode, struct nfs_page *head,
 387                           struct nfs_page *req)
 388 {
 389         struct nfs_page *tmp;
 390
 391         /* relinquish all the locks successfully grabbed this run */
 392         for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
 393                 if (!kref_read(&tmp->wb_kref))
 394                         continue;
 395                 nfs_unlock_and_release_request(tmp);
 396         }
 397 }
 398
 399 /*
 400  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
 401  *
 402  * @destroy_list - request list (using wb_this_page) terminated by @old_head
 403  * @old_head - the old head of the list
 404  *
 405  * All subrequests must be locked and removed from all lists, so at this point
 406  * they are only "active" in this function, and possibly in nfs_wait_on_request
 407  * with a reference held by some other context.
 408  */
 409 static void
 410 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 411                                  struct nfs_page *old_head,
 412                                  struct inode *inode)
 413 {
 414         while (destroy_list) {
 415                 struct nfs_page *subreq = destroy_list;
 416
 417                 destroy_list = (subreq->wb_this_page == old_head) ?
 418                                    NULL : subreq->wb_this_page;
 419
 420                 WARN_ON_ONCE(old_head != subreq->wb_head);
 421
 422                 /* make sure old group is not used */
 423                 subreq->wb_this_page = subreq;
 424
 425                 clear_bit(PG_REMOVE, &subreq->wb_flags);
 426
 427                 /* Note: races with nfs_page_group_destroy() */
 428                 if (!kref_read(&subreq->wb_kref)) {
 429                         /* Check if we raced with nfs_page_group_destroy() */
 430                         if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags))
 431                                 nfs_free_request(subreq);
 432                         continue;
 433                 }
 434
 435                 subreq->wb_head = subreq;
 436
 437                 if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 438                         nfs_release_request(subreq);
 439                         atomic_long_dec(&NFS_I(inode)->nrequests);
 440                 }
 441
 442                 /* subreq is now totally disconnected from page group or any
 443                  * write / commit lists. last chance to wake any waiters */
 444                 nfs_unlock_and_release_request(subreq);
 445         }
 446 }
 447
 448 /*
 449  * nfs_lock_and_join_requests - join all subreqs to the head req and return
 450  *                              a locked reference, cancelling any pending
 451  *                              operations for this page.
 452  *
 453  * @page - the page used to lookup the "page group" of nfs_page structures
 454  *
 455  * This function joins all sub requests to the head request by first
 456  * locking all requests in the group, cancelling any pending operations
 457  * and finally updating the head request to cover the whole range covered by
 458  * the (former) group.  All subrequests are removed from any write or commit
 459  * lists, unlinked from the group and destroyed.
 460  *
 461  * Returns a locked, referenced pointer to the head request - which after
 462  * this call is guaranteed to be the only request associated with the page.
 463  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
 464  * error was encountered.
 465  */
 466 static struct nfs_page *
 467 nfs_lock_and_join_requests(struct page *page)
 468 {
 469         struct inode *inode = page_file_mapping(page)->host;
 470         struct nfs_page *head, *subreq;
 471         struct nfs_page *destroy_list = NULL;
 472         unsigned int total_bytes;
 473         int ret;
 474
 475 try_again:
 476         /*
 477          * A reference is taken only on the head request which acts as a
 478          * reference to the whole page group - the group will not be destroyed
 479          * until the head reference is released.
 480          */
 481         head = nfs_page_find_head_request(page);
 482         if (!head)
 483                 return NULL;
 484
 485         /* lock the page head first in order to avoid an ABBA inefficiency */
 486         if (!nfs_lock_request(head)) {
 487                 ret = nfs_wait_on_request(head);
 488                 nfs_release_request(head);
 489                 if (ret < 0)
 490                         return ERR_PTR(ret);
 491                 goto try_again;
 492         }
 493
 494         /* Ensure that nobody removed the request before we locked it */
 495         if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {
 496                 nfs_unlock_and_release_request(head);
 497                 goto try_again;
 498         }
 499
 500         ret = nfs_page_group_lock(head);
 501         if (ret < 0)
 502                 goto release_request;
 503
 504         /* lock each request in the page group */
 505         total_bytes = head->wb_bytes;
 506         for (subreq = head->wb_this_page; subreq != head;
 507                         subreq = subreq->wb_this_page) {
 508
 509                 if (!kref_get_unless_zero(&subreq->wb_kref)) {
 510                         if (subreq->wb_offset == head->wb_offset + total_bytes)
 511                                 total_bytes += subreq->wb_bytes;
 512                         continue;
 513                 }
 514
 515                 while (!nfs_lock_request(subreq)) {
 516                         /*
 517                          * Unlock page to allow nfs_page_group_sync_on_bit()
 518                          * to succeed
 519                          */
 520                         nfs_page_group_unlock(head);
 521                         ret = nfs_wait_on_request(subreq);
 522                         if (!ret)
 523                                 ret = nfs_page_group_lock(head);
 524                         if (ret < 0) {
 525                                 nfs_unroll_locks(inode, head, subreq);
 526                                 nfs_release_request(subreq);
 527                                 goto release_request;
 528                         }
 529                 }
 530                 /*
 531                  * Subrequests are always contiguous, non overlapping
 532                  * and in order - but may be repeated (mirrored writes).
 533                  */
 534                 if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
 535                         /* keep track of how many bytes this group covers */
 536                         total_bytes += subreq->wb_bytes;
 537                 } else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
 538                             ((subreq->wb_offset + subreq->wb_bytes) >
 539                              (head->wb_offset + total_bytes)))) {
 540                         nfs_page_group_unlock(head);
 541                         nfs_unroll_locks(inode, head, subreq);
 542                         nfs_unlock_and_release_request(subreq);
 543                         ret = -EIO;
 544                         goto release_request;
 545                 }
 546         }
 547
 548         /* Now that all requests are locked, make sure they aren't on any list.
 549          * Commit list removal accounting is done after locks are dropped */
 550         subreq = head;
 551         do {
 552                 nfs_clear_request_commit(subreq);
 553                 subreq = subreq->wb_this_page;
 554         } while (subreq != head);
 555
 556         /* unlink subrequests from head, destroy them later */
 557         if (head->wb_this_page != head) {
 558                 /* destroy list will be terminated by head */
 559                 destroy_list = head->wb_this_page;
 560                 head->wb_this_page = head;
 561
 562                 /* change head request to cover whole range that
 563                  * the former page group covered */
 564                 head->wb_bytes = total_bytes;
 565         }
 566
 567         /* Postpone destruction of this request */
 568         if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) {
 569                 set_bit(PG_INODE_REF, &head->wb_flags);
 570                 kref_get(&head->wb_kref);
 571                 atomic_long_inc(&NFS_I(inode)->nrequests);
 572         }
 573
 574         nfs_page_group_unlock(head);
 575
 576         nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 577
 578         /* Did we lose a race with nfs_inode_remove_request()? */
 579         if (!(PagePrivate(page) || PageSwapCache(page))) {
 580                 nfs_unlock_and_release_request(head);
 581                 return NULL;
 582         }
 583
 584         /* still holds ref on head from nfs_page_find_head_request
 585          * and still has lock on head from lock loop */
 586         return head;
 587
 588 release_request:
 589         nfs_unlock_and_release_request(head);
 590         return ERR_PTR(ret);
 591 }
 592
 593 static void nfs_write_error(struct nfs_page *req, int error)
 594 {
 595         nfs_set_pageerror(page_file_mapping(req->wb_page));
 596         nfs_mapping_set_error(req->wb_page, error);
 597         nfs_inode_remove_request(req);
 598         nfs_end_page_writeback(req);
 599         nfs_release_request(req);
 600 }
 601
 602 /*
 603  * Find an associated nfs write request, and prepare to flush it out
 604  * May return an error if the user signalled nfs_wait_on_request().
 605  */
 606 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 607                                 struct page *page)
 608 {
 609         struct nfs_page *req;
 610         int ret = 0;
 611
 612         req = nfs_lock_and_join_requests(page);
 613         if (!req)
 614                 goto out;
 615         ret = PTR_ERR(req);
 616         if (IS_ERR(req))
 617                 goto out;
 618
 619         nfs_set_page_writeback(page);
 620         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 621
 622         /* If there is a fatal error that covers this write, just exit */
 623         ret = pgio->pg_error;
 624         if (nfs_error_is_fatal_on_server(ret))
 625                 goto out_launder;
 626
 627         ret = 0;
 628         if (!nfs_pageio_add_request(pgio, req)) {
 629                 ret = pgio->pg_error;
 630                 /*
 631                  * Remove the problematic req upon fatal errors on the server
 632                  */
 633                 if (nfs_error_is_fatal(ret)) {
 634                         if (nfs_error_is_fatal_on_server(ret))
 635                                 goto out_launder;
 636                 } else
 637                         ret = -EAGAIN;
 638                 nfs_redirty_request(req);
 639                 pgio->pg_error = 0;
 640         } else
 641                 nfs_add_stats(page_file_mapping(page)->host,
 642                                 NFSIOS_WRITEPAGES, 1);
 643 out:
 644         return ret;
 645 out_launder:
 646         nfs_write_error(req, ret);
 647         return 0;
 648 }
 649
 650 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
 651                             struct nfs_pageio_descriptor *pgio)
 652 {
 653         int ret;
 654
 655         nfs_pageio_cond_complete(pgio, page_index(page));
 656         ret = nfs_page_async_flush(pgio, page);
 657         if (ret == -EAGAIN) {
 658                 redirty_page_for_writepage(wbc, page);
 659                 ret = AOP_WRITEPAGE_ACTIVATE;
 660         }
 661         return ret;
 662 }
 663
 664 /*
 665  * Write an mmapped page to the server.
 666  */
 667 static int nfs_writepage_locked(struct page *page,
 668                                 struct writeback_control *wbc)
 669 {
 670         struct nfs_pageio_descriptor pgio;
 671         struct inode *inode = page_file_mapping(page)->host;
 672         int err;
 673
 674         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 675         nfs_pageio_init_write(&pgio, inode, 0,
 676                                 false, &nfs_async_write_completion_ops);
 677         err = nfs_do_writepage(page, wbc, &pgio);
 678         pgio.pg_error = 0;
 679         nfs_pageio_complete(&pgio);
 680         if (err < 0)
 681                 return err;
 682         if (nfs_error_is_fatal(pgio.pg_error))
 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         if (ret != AOP_WRITEPAGE_ACTIVATE)
 693                 unlock_page(page);
 694         return ret;
 695 }
 696
 697 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 698 {
 699         int ret;
 700
 701         ret = nfs_do_writepage(page, wbc, data);
 702         if (ret != AOP_WRITEPAGE_ACTIVATE)
 703                 unlock_page(page);
 704         return ret;
 705 }
 706
 707 static void nfs_io_completion_commit(void *inode)
 708 {
 709         nfs_commit_inode(inode, 0);
 710 }
 711
 712 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 713 {
 714         struct inode *inode = mapping->host;
 715         struct nfs_pageio_descriptor pgio;
 716         struct nfs_io_completion *ioc;
 717         int err;
 718
 719         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 720
 721         ioc = nfs_io_completion_alloc(GFP_KERNEL);
 722         if (ioc)
 723                 nfs_io_completion_init(ioc, nfs_io_completion_commit, inode);
 724
 725         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc), false,
 726                                 &nfs_async_write_completion_ops);
 727         pgio.pg_io_completion = ioc;
 728         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 729         pgio.pg_error = 0;
 730         nfs_pageio_complete(&pgio);
 731         nfs_io_completion_put(ioc);
 732
 733         if (err < 0)
 734                 goto out_err;
 735         err = pgio.pg_error;
 736         if (nfs_error_is_fatal(err))
 737                 goto out_err;
 738         return 0;
 739 out_err:
 740         return err;
 741 }
 742
 743 /*
 744  * Insert a write request into an inode
 745  */
 746 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 747 {
 748         struct address_space *mapping = page_file_mapping(req->wb_page);
 749         struct nfs_inode *nfsi = NFS_I(inode);
 750
 751         WARN_ON_ONCE(req->wb_this_page != req);
 752
 753         /* Lock the request! */
 754         nfs_lock_request(req);
 755
 756         /*
 757          * Swap-space should not get truncated. Hence no need to plug the race
 758          * with invalidate/truncate.
 759          */
 760         spin_lock(&mapping->private_lock);
 761         if (!nfs_have_writebacks(inode) &&
 762             NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 763                 inode_inc_iversion_raw(inode);
 764         if (likely(!PageSwapCache(req->wb_page))) {
 765                 set_bit(PG_MAPPED, &req->wb_flags);
 766                 SetPagePrivate(req->wb_page);
 767                 set_page_private(req->wb_page, (unsigned long)req);
 768         }
 769         spin_unlock(&mapping->private_lock);
 770         atomic_long_inc(&nfsi->nrequests);
 771         /* this a head request for a page group - mark it as having an
 772          * extra reference so sub groups can follow suit.
 773          * This flag also informs pgio layer when to bump nrequests when
 774          * adding subrequests. */
 775         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 776         kref_get(&req->wb_kref);
 777 }
 778
 779 /*
 780  * Remove a write request from an inode
 781  */
 782 static void nfs_inode_remove_request(struct nfs_page *req)
 783 {
 784         struct address_space *mapping = page_file_mapping(req->wb_page);
 785         struct inode *inode = mapping->host;
 786         struct nfs_inode *nfsi = NFS_I(inode);
 787         struct nfs_page *head;
 788
 789         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
 790                 head = req->wb_head;
 791
 792                 spin_lock(&mapping->private_lock);
 793                 if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
 794                         set_page_private(head->wb_page, 0);
 795                         ClearPagePrivate(head->wb_page);
 796                         clear_bit(PG_MAPPED, &head->wb_flags);
 797                 }
 798                 spin_unlock(&mapping->private_lock);
 799         }
 800
 801         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags)) {
 802                 nfs_release_request(req);
 803                 atomic_long_dec(&nfsi->nrequests);
 804         }
 805 }
 806
 807 static void
 808 nfs_mark_request_dirty(struct nfs_page *req)
 809 {
 810         if (req->wb_page)
 811                 __set_page_dirty_nobuffers(req->wb_page);
 812 }
 813
 814 /*
 815  * nfs_page_search_commits_for_head_request_locked
 816  *
 817  * Search through commit lists on @inode for the head request for @page.
 818  * Must be called while holding the inode (which is cinfo) lock.
 819  *
 820  * Returns the head request if found, or NULL if not found.
 821  */
 822 static struct nfs_page *
 823 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 824                                                 struct page *page)
 825 {
 826         struct nfs_page *freq, *t;
 827         struct nfs_commit_info cinfo;
 828         struct inode *inode = &nfsi->vfs_inode;
 829
 830         nfs_init_cinfo_from_inode(&cinfo, inode);
 831
 832         /* search through pnfs commit lists */
 833         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
 834         if (freq)
 835                 return freq->wb_head;
 836
 837         /* Linearly search the commit list for the correct request */
 838         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
 839                 if (freq->wb_page == page)
 840                         return freq->wb_head;
 841         }
 842
 843         return NULL;
 844 }
 845
 846 /**
 847  * nfs_request_add_commit_list_locked - add request to a commit list
 848  * @req: pointer to a struct nfs_page
 849  * @dst: commit list head
 850  * @cinfo: holds list lock and accounting info
 851  *
 852  * This sets the PG_CLEAN bit, updates the cinfo count of
 853  * number of outstanding requests requiring a commit as well as
 854  * the MM page stats.
 855  *
 856  * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
 857  * nfs_page lock.
 858  */
 859 void
 860 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
 861                             struct nfs_commit_info *cinfo)
 862 {
 863         set_bit(PG_CLEAN, &req->wb_flags);
 864         nfs_list_add_request(req, dst);
 865         atomic_long_inc(&cinfo->mds->ncommit);
 866 }
 867 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 868
 869 /**
 870  * nfs_request_add_commit_list - add request to a commit list
 871  * @req: pointer to a struct nfs_page
 872  * @cinfo: holds list lock and accounting info
 873  *
 874  * This sets the PG_CLEAN bit, updates the cinfo count of
 875  * number of outstanding requests requiring a commit as well as
 876  * the MM page stats.
 877  *
 878  * The caller must _not_ hold the cinfo->lock, but must be
 879  * holding the nfs_page lock.
 880  */
 881 void
 882 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 883 {
 884         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 885         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
 886         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 887         if (req->wb_page)
 888                 nfs_mark_page_unstable(req->wb_page, cinfo);
 889 }
 890 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 891
 892 /**
 893  * nfs_request_remove_commit_list - Remove request from a commit list
 894  * @req: pointer to a nfs_page
 895  * @cinfo: holds list lock and accounting info
 896  *
 897  * This clears the PG_CLEAN bit, and updates the cinfo's count of
 898  * number of outstanding requests requiring a commit
 899  * It does not update the MM page stats.
 900  *
 901  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 902  */
 903 void
 904 nfs_request_remove_commit_list(struct nfs_page *req,
 905                                struct nfs_commit_info *cinfo)
 906 {
 907         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 908                 return;
 909         nfs_list_remove_request(req);
 910         atomic_long_dec(&cinfo->mds->ncommit);
 911 }
 912 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 913
 914 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 915                                       struct inode *inode)
 916 {
 917         cinfo->inode = inode;
 918         cinfo->mds = &NFS_I(inode)->commit_info;
 919         cinfo->ds = pnfs_get_ds_info(inode);
 920         cinfo->dreq = NULL;
 921         cinfo->completion_ops = &nfs_commit_completion_ops;
 922 }
 923
 924 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 925                     struct inode *inode,
 926                     struct nfs_direct_req *dreq)
 927 {
 928         if (dreq)
 929                 nfs_init_cinfo_from_dreq(cinfo, dreq);
 930         else
 931                 nfs_init_cinfo_from_inode(cinfo, inode);
 932 }
 933 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 934
 935 /*
 936  * Add a request to the inode's commit list.
 937  */
 938 void
 939 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 940                         struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 941 {
 942         if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 943                 return;
 944         nfs_request_add_commit_list(req, cinfo);
 945 }
 946
 947 static void
 948 nfs_clear_page_commit(struct page *page)
 949 {
 950         dec_node_page_state(page, NR_UNSTABLE_NFS);
 951         dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
 952                     WB_RECLAIMABLE);
 953 }
 954
 955 /* Called holding the request lock on @req */
 956 static void
 957 nfs_clear_request_commit(struct nfs_page *req)
 958 {
 959         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 960                 struct nfs_open_context *ctx = nfs_req_openctx(req);
 961                 struct inode *inode = d_inode(ctx->dentry);
 962                 struct nfs_commit_info cinfo;
 963
 964                 nfs_init_cinfo_from_inode(&cinfo, inode);
 965                 mutex_lock(&NFS_I(inode)->commit_mutex);
 966                 if (!pnfs_clear_request_commit(req, &cinfo)) {
 967                         nfs_request_remove_commit_list(req, &cinfo);
 968                 }
 969                 mutex_unlock(&NFS_I(inode)->commit_mutex);
 970                 nfs_clear_page_commit(req->wb_page);
 971         }
 972 }
 973
 974 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 975 {
 976         if (hdr->verf.committed == NFS_DATA_SYNC)
 977                 return hdr->lseg == NULL;
 978         return hdr->verf.committed != NFS_FILE_SYNC;
 979 }
 980
 981 static void nfs_async_write_init(struct nfs_pgio_header *hdr)
 982 {
 983         nfs_io_completion_get(hdr->io_completion);
 984 }
 985
 986 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 987 {
 988         struct nfs_commit_info cinfo;
 989         unsigned long bytes = 0;
 990
 991         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 992                 goto out;
 993         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
 994         while (!list_empty(&hdr->pages)) {
 995                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 996
 997                 bytes += req->wb_bytes;
 998                 nfs_list_remove_request(req);
 999                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
1000                     (hdr->good_bytes < bytes)) {
1001                         nfs_set_pageerror(page_file_mapping(req->wb_page));
1002                         nfs_mapping_set_error(req->wb_page, hdr->error);
1003                         goto remove_req;
1004                 }
1005                 if (nfs_write_need_commit(hdr)) {
1006                         /* Reset wb_nio, since the write was successful. */
1007                         req->wb_nio = 0;
1008                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1009                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1010                                 hdr->pgio_mirror_idx);
1011                         goto next;
1012                 }
1013 remove_req:
1014                 nfs_inode_remove_request(req);
1015 next:
1016                 nfs_end_page_writeback(req);
1017                 nfs_release_request(req);
1018         }
1019 out:
1020         nfs_io_completion_put(hdr->io_completion);
1021         hdr->release(hdr);
1022 }
1023
1024 unsigned long
1025 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1026 {
1027         return atomic_long_read(&cinfo->mds->ncommit);
1028 }
1029
1030 /* NFS_I(cinfo->inode)->commit_mutex held by caller */
1031 int
1032 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1033                      struct nfs_commit_info *cinfo, int max)
1034 {
1035         struct nfs_page *req, *tmp;
1036         int ret = 0;
1037
1038 restart:
1039         list_for_each_entry_safe(req, tmp, src, wb_list) {
1040                 kref_get(&req->wb_kref);
1041                 if (!nfs_lock_request(req)) {
1042                         int status;
1043
1044                         /* Prevent deadlock with nfs_lock_and_join_requests */
1045                         if (!list_empty(dst)) {
1046                                 nfs_release_request(req);
1047                                 continue;
1048                         }
1049                         /* Ensure we make progress to prevent livelock */
1050                         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1051                         status = nfs_wait_on_request(req);
1052                         nfs_release_request(req);
1053                         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1054                         if (status < 0)
1055                                 break;
1056                         goto restart;
1057                 }
1058                 nfs_request_remove_commit_list(req, cinfo);
1059                 clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1060                 nfs_list_add_request(req, dst);
1061                 ret++;
1062                 if ((ret == max) && !cinfo->dreq)
1063                         break;
1064                 cond_resched();
1065         }
1066         return ret;
1067 }
1068 EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1069
1070 /*
1071  * nfs_scan_commit - Scan an inode for commit requests
1072  * @inode: NFS inode to scan
1073  * @dst: mds destination list
1074  * @cinfo: mds and ds lists of reqs ready to commit
1075  *
1076  * Moves requests from the inode's 'commit' request list.
1077  * The requests are *not* checked to ensure that they form a contiguous set.
1078  */
1079 int
1080 nfs_scan_commit(struct inode *inode, struct list_head *dst,
1081                 struct nfs_commit_info *cinfo)
1082 {
1083         int ret = 0;
1084
1085         if (!atomic_long_read(&cinfo->mds->ncommit))
1086                 return 0;
1087         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1088         if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1089                 const int max = INT_MAX;
1090
1091                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1092                                            cinfo, max);
1093                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1094         }
1095         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1096         return ret;
1097 }
1098
1099 /*
1100  * Search for an existing write request, and attempt to update
1101  * it to reflect a new dirty region on a given page.
1102  *
1103  * If the attempt fails, then the existing request is flushed out
1104  * to disk.
1105  */
1106 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1107                 struct page *page,
1108                 unsigned int offset,
1109                 unsigned int bytes)
1110 {
1111         struct nfs_page *req;
1112         unsigned int rqend;
1113         unsigned int end;
1114         int error;
1115
1116         end = offset + bytes;
1117
1118         req = nfs_lock_and_join_requests(page);
1119         if (IS_ERR_OR_NULL(req))
1120                 return req;
1121
1122         rqend = req->wb_offset + req->wb_bytes;
1123         /*
1124          * Tell the caller to flush out the request if
1125          * the offsets are non-contiguous.
1126          * Note: nfs_flush_incompatible() will already
1127          * have flushed out requests having wrong owners.
1128          */
1129         if (offset > rqend || end < req->wb_offset)
1130                 goto out_flushme;
1131
1132         /* Okay, the request matches. Update the region */
1133         if (offset < req->wb_offset) {
1134                 req->wb_offset = offset;
1135                 req->wb_pgbase = offset;
1136         }
1137         if (end > rqend)
1138                 req->wb_bytes = end - req->wb_offset;
1139         else
1140                 req->wb_bytes = rqend - req->wb_offset;
1141         req->wb_nio = 0;
1142         return req;
1143 out_flushme:
1144         /*
1145          * Note: we mark the request dirty here because
1146          * nfs_lock_and_join_requests() cannot preserve
1147          * commit flags, so we have to replay the write.
1148          */
1149         nfs_mark_request_dirty(req);
1150         nfs_unlock_and_release_request(req);
1151         error = nfs_wb_page(inode, page);
1152         return (error < 0) ? ERR_PTR(error) : NULL;
1153 }
1154
1155 /*
1156  * Try to update an existing write request, or create one if there is none.
1157  *
1158  * Note: Should always be called with the Page Lock held to prevent races
1159  * if we have to add a new request. Also assumes that the caller has
1160  * already called nfs_flush_incompatible() if necessary.
1161  */
1162 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1163                 struct page *page, unsigned int offset, unsigned int bytes)
1164 {
1165         struct inode *inode = page_file_mapping(page)->host;
1166         struct nfs_page *req;
1167
1168         req = nfs_try_to_update_request(inode, page, offset, bytes);
1169         if (req != NULL)
1170                 goto out;
1171         req = nfs_create_request(ctx, page, offset, bytes);
1172         if (IS_ERR(req))
1173                 goto out;
1174         nfs_inode_add_request(inode, req);
1175 out:
1176         return req;
1177 }
1178
1179 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1180                 unsigned int offset, unsigned int count)
1181 {
1182         struct nfs_page *req;
1183
1184         req = nfs_setup_write_request(ctx, page, offset, count);
1185         if (IS_ERR(req))
1186                 return PTR_ERR(req);
1187         /* Update file length */
1188         nfs_grow_file(page, offset, count);
1189         nfs_mark_uptodate(req);
1190         nfs_mark_request_dirty(req);
1191         nfs_unlock_and_release_request(req);
1192         return 0;
1193 }
1194
1195 int nfs_flush_incompatible(struct file *file, struct page *page)
1196 {
1197         struct nfs_open_context *ctx = nfs_file_open_context(file);
1198         struct nfs_lock_context *l_ctx;
1199         struct file_lock_context *flctx = file_inode(file)->i_flctx;
1200         struct nfs_page *req;
1201         int do_flush, status;
1202         /*
1203          * Look for a request corresponding to this page. If there
1204          * is one, and it belongs to another file, we flush it out
1205          * before we try to copy anything into the page. Do this
1206          * due to the lack of an ACCESS-type call in NFSv2.
1207          * Also do the same if we find a request from an existing
1208          * dropped page.
1209          */
1210         do {
1211                 req = nfs_page_find_head_request(page);
1212                 if (req == NULL)
1213                         return 0;
1214                 l_ctx = req->wb_lock_context;
1215                 do_flush = req->wb_page != page ||
1216                         !nfs_match_open_context(nfs_req_openctx(req), ctx);
1217                 if (l_ctx && flctx &&
1218                     !(list_empty_careful(&flctx->flc_posix) &&
1219                       list_empty_careful(&flctx->flc_flock))) {
1220                         do_flush |= l_ctx->lockowner != current->files;
1221                 }
1222                 nfs_release_request(req);
1223                 if (!do_flush)
1224                         return 0;
1225                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1226         } while (status == 0);
1227         return status;
1228 }
1229
1230 /*
1231  * Avoid buffered writes when a open context credential's key would
1232  * expire soon.
1233  *
1234  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1235  *
1236  * Return 0 and set a credential flag which triggers the inode to flush
1237  * and performs  NFS_FILE_SYNC writes if the key will expired within
1238  * RPC_KEY_EXPIRE_TIMEO.
1239  */
1240 int
1241 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1242 {
1243         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1244
1245         if (nfs_ctx_key_to_expire(ctx, inode) &&
1246             !ctx->ll_cred)
1247                 /* Already expired! */
1248                 return -EACCES;
1249         return 0;
1250 }
1251
1252 /*
1253  * Test if the open context credential key is marked to expire soon.
1254  */
1255 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1256 {
1257         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1258         struct rpc_cred *cred = ctx->ll_cred;
1259         struct auth_cred acred = {
1260                 .cred = ctx->cred,
1261         };
1262
1263         if (cred && !cred->cr_ops->crmatch(&acred, cred, 0)) {
1264                 put_rpccred(cred);
1265                 ctx->ll_cred = NULL;
1266                 cred = NULL;
1267         }
1268         if (!cred)
1269                 cred = auth->au_ops->lookup_cred(auth, &acred, 0);
1270         if (!cred || IS_ERR(cred))
1271                 return true;
1272         ctx->ll_cred = cred;
1273         return !!(cred->cr_ops->crkey_timeout &&
1274                   cred->cr_ops->crkey_timeout(cred));
1275 }
1276
1277 /*
1278  * If the page cache is marked as unsafe or invalid, then we can't rely on
1279  * the PageUptodate() flag. In this case, we will need to turn off
1280  * write optimisations that depend on the page contents being correct.
1281  */
1282 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
1283 {
1284         struct nfs_inode *nfsi = NFS_I(inode);
1285
1286         if (nfs_have_delegated_attributes(inode))
1287                 goto out;
1288         if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
1289                 return false;
1290         smp_rmb();
1291         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
1292                 return false;
1293 out:
1294         if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
1295                 return false;
1296         return PageUptodate(page) != 0;
1297 }
1298
1299 static bool
1300 is_whole_file_wrlock(struct file_lock *fl)
1301 {
1302         return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1303                         fl->fl_type == F_WRLCK;
1304 }
1305
1306 /* If we know the page is up to date, and we're not using byte range locks (or
1307  * if we have the whole file locked for writing), it may be more efficient to
1308  * extend the write to cover the entire page in order to avoid fragmentation
1309  * inefficiencies.
1310  *
1311  * If the file is opened for synchronous writes then we can just skip the rest
1312  * of the checks.
1313  */
1314 static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
1315 {
1316         int ret;
1317         struct file_lock_context *flctx = inode->i_flctx;
1318         struct file_lock *fl;
1319
1320         if (file->f_flags & O_DSYNC)
1321                 return 0;
1322         if (!nfs_write_pageuptodate(page, inode))
1323                 return 0;
1324         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1325                 return 1;
1326         if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1327                        list_empty_careful(&flctx->flc_posix)))
1328                 return 1;
1329
1330         /* Check to see if there are whole file write locks */
1331         ret = 0;
1332         spin_lock(&flctx->flc_lock);
1333         if (!list_empty(&flctx->flc_posix)) {
1334                 fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1335                                         fl_list);
1336                 if (is_whole_file_wrlock(fl))
1337                         ret = 1;
1338         } else if (!list_empty(&flctx->flc_flock)) {
1339                 fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1340                                         fl_list);
1341                 if (fl->fl_type == F_WRLCK)
1342                         ret = 1;
1343         }
1344         spin_unlock(&flctx->flc_lock);
1345         return ret;
1346 }
1347
1348 /*
1349  * Update and possibly write a cached page of an NFS file.
1350  *
1351  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1352  * things with a page scheduled for an RPC call (e.g. invalidate it).
1353  */
1354 int nfs_updatepage(struct file *file, struct page *page,
1355                 unsigned int offset, unsigned int count)
1356 {
1357         struct nfs_open_context *ctx = nfs_file_open_context(file);
1358         struct address_space *mapping = page_file_mapping(page);
1359         struct inode    *inode = mapping->host;
1360         int             status = 0;
1361
1362         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1363
1364         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1365                 file, count, (long long)(page_file_offset(page) + offset));
1366
1367         if (!count)
1368                 goto out;
1369
1370         if (nfs_can_extend_write(file, page, inode)) {
1371                 count = max(count + offset, nfs_page_length(page));
1372                 offset = 0;
1373         }
1374
1375         status = nfs_writepage_setup(ctx, page, offset, count);
1376         if (status < 0)
1377                 nfs_set_pageerror(mapping);
1378         else
1379                 __set_page_dirty_nobuffers(page);
1380 out:
1381         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1382                         status, (long long)i_size_read(inode));
1383         return status;
1384 }
1385
1386 static int flush_task_priority(int how)
1387 {
1388         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1389                 case FLUSH_HIGHPRI:
1390                         return RPC_PRIORITY_HIGH;
1391                 case FLUSH_LOWPRI:
1392                         return RPC_PRIORITY_LOW;
1393         }
1394         return RPC_PRIORITY_NORMAL;
1395 }
1396
1397 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1398                                struct rpc_message *msg,
1399                                const struct nfs_rpc_ops *rpc_ops,
1400                                struct rpc_task_setup *task_setup_data, int how)
1401 {
1402         int priority = flush_task_priority(how);
1403
1404         task_setup_data->priority = priority;
1405         rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1406         trace_nfs_initiate_write(hdr->inode, hdr->io_start, hdr->good_bytes,
1407                                  hdr->args.stable);
1408 }
1409
1410 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1411  * call this on each, which will prepare them to be retried on next
1412  * writeback using standard nfs.
1413  */
1414 static void nfs_redirty_request(struct nfs_page *req)
1415 {
1416         /* Bump the transmission count */
1417         req->wb_nio++;
1418         nfs_mark_request_dirty(req);
1419         set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1420         nfs_end_page_writeback(req);
1421         nfs_release_request(req);
1422 }
1423
1424 static void nfs_async_write_error(struct list_head *head, int error)
1425 {
1426         struct nfs_page *req;
1427
1428         while (!list_empty(head)) {
1429                 req = nfs_list_entry(head->next);
1430                 nfs_list_remove_request(req);
1431                 if (nfs_error_is_fatal(error))
1432                         nfs_write_error(req, error);
1433                 else
1434                         nfs_redirty_request(req);
1435         }
1436 }
1437
1438 static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1439 {
1440         nfs_async_write_error(&hdr->pages, 0);
1441         filemap_fdatawrite_range(hdr->inode->i_mapping, hdr->args.offset,
1442                         hdr->args.offset + hdr->args.count - 1);
1443 }
1444
1445 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1446         .init_hdr = nfs_async_write_init,
1447         .error_cleanup = nfs_async_write_error,
1448         .completion = nfs_write_completion,
1449         .reschedule_io = nfs_async_write_reschedule_io,
1450 };
1451
1452 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1453                                struct inode *inode, int ioflags, bool force_mds,
1454                                const struct nfs_pgio_completion_ops *compl_ops)
1455 {
1456         struct nfs_server *server = NFS_SERVER(inode);
1457         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1458
1459 #ifdef CONFIG_NFS_V4_1
1460         if (server->pnfs_curr_ld && !force_mds)
1461                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1462 #endif
1463         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1464                         server->wsize, ioflags);
1465 }
1466 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1467
1468 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1469 {
1470         struct nfs_pgio_mirror *mirror;
1471
1472         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1473                 pgio->pg_ops->pg_cleanup(pgio);
1474
1475         pgio->pg_ops = &nfs_pgio_rw_ops;
1476
1477         nfs_pageio_stop_mirroring(pgio);
1478
1479         mirror = &pgio->pg_mirrors[0];
1480         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1481 }
1482 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1483
1484
1485 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1486 {
1487         struct nfs_commit_data *data = calldata;
1488
1489         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1490 }
1491
1492 /*
1493  * Special version of should_remove_suid() that ignores capabilities.
1494  */
1495 static int nfs_should_remove_suid(const struct inode *inode)
1496 {
1497         umode_t mode = inode->i_mode;
1498         int kill = 0;
1499
1500         /* suid always must be killed */
1501         if (unlikely(mode & S_ISUID))
1502                 kill = ATTR_KILL_SUID;
1503
1504         /*
1505          * sgid without any exec bits is just a mandatory locking mark; leave
1506          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1507          */
1508         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1509                 kill |= ATTR_KILL_SGID;
1510
1511         if (unlikely(kill && S_ISREG(mode)))
1512                 return kill;
1513
1514         return 0;
1515 }
1516
1517 static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1518                 struct nfs_fattr *fattr)
1519 {
1520         struct nfs_pgio_args *argp = &hdr->args;
1521         struct nfs_pgio_res *resp = &hdr->res;
1522         u64 size = argp->offset + resp->count;
1523
1524         if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1525                 fattr->size = size;
1526         if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1527                 fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1528                 return;
1529         }
1530         if (size != fattr->size)
1531                 return;
1532         /* Set attribute barrier */
1533         nfs_fattr_set_barrier(fattr);
1534         /* ...and update size */
1535         fattr->valid |= NFS_ATTR_FATTR_SIZE;
1536 }
1537
1538 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1539 {
1540         struct nfs_fattr *fattr = &hdr->fattr;
1541         struct inode *inode = hdr->inode;
1542
1543         spin_lock(&inode->i_lock);
1544         nfs_writeback_check_extend(hdr, fattr);
1545         nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1546         spin_unlock(&inode->i_lock);
1547 }
1548 EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1549
1550 /*
1551  * This function is called when the WRITE call is complete.
1552  */
1553 static int nfs_writeback_done(struct rpc_task *task,
1554                               struct nfs_pgio_header *hdr,
1555                               struct inode *inode)
1556 {
1557         int status;
1558
1559         /*
1560          * ->write_done will attempt to use post-op attributes to detect
1561          * conflicting writes by other clients.  A strict interpretation
1562          * of close-to-open would allow us to continue caching even if
1563          * another writer had changed the file, but some applications
1564          * depend on tighter cache coherency when writing.
1565          */
1566         status = NFS_PROTO(inode)->write_done(task, hdr);
1567         if (status != 0)
1568                 return status;
1569
1570         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1571         trace_nfs_writeback_done(inode, task->tk_status,
1572                                  hdr->args.offset, hdr->res.verf);
1573
1574         if (hdr->res.verf->committed < hdr->args.stable &&
1575             task->tk_status >= 0) {
1576                 /* We tried a write call, but the server did not
1577                  * commit data to stable storage even though we
1578                  * requested it.
1579                  * Note: There is a known bug in Tru64 < 5.0 in which
1580                  *       the server reports NFS_DATA_SYNC, but performs
1581                  *       NFS_FILE_SYNC. We therefore implement this checking
1582                  *       as a dprintk() in order to avoid filling syslog.
1583                  */
1584                 static unsigned long    complain;
1585
1586                 /* Note this will print the MDS for a DS write */
1587                 if (time_before(complain, jiffies)) {
1588                         dprintk("NFS:       faulty NFS server %s:"
1589                                 " (committed = %d) != (stable = %d)\n",
1590                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1591                                 hdr->res.verf->committed, hdr->args.stable);
1592                         complain = jiffies + 300 * HZ;
1593                 }
1594         }
1595
1596         /* Deal with the suid/sgid bit corner case */
1597         if (nfs_should_remove_suid(inode)) {
1598                 spin_lock(&inode->i_lock);
1599                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_OTHER;
1600                 spin_unlock(&inode->i_lock);
1601         }
1602         return 0;
1603 }
1604
1605 /*
1606  * This function is called when the WRITE call is complete.
1607  */
1608 static void nfs_writeback_result(struct rpc_task *task,
1609                                  struct nfs_pgio_header *hdr)
1610 {
1611         struct nfs_pgio_args    *argp = &hdr->args;
1612         struct nfs_pgio_res     *resp = &hdr->res;
1613
1614         if (resp->count < argp->count) {
1615                 static unsigned long    complain;
1616
1617                 /* This a short write! */
1618                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1619
1620                 /* Has the server at least made some progress? */
1621                 if (resp->count == 0) {
1622                         if (time_before(complain, jiffies)) {
1623                                 printk(KERN_WARNING
1624                                        "NFS: Server wrote zero bytes, expected %u.\n",
1625                                        argp->count);
1626                                 complain = jiffies + 300 * HZ;
1627                         }
1628                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1629                         task->tk_status = -EIO;
1630                         return;
1631                 }
1632
1633                 /* For non rpc-based layout drivers, retry-through-MDS */
1634                 if (!task->tk_ops) {
1635                         hdr->pnfs_error = -EAGAIN;
1636                         return;
1637                 }
1638
1639                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1640                 if (resp->verf->committed != NFS_UNSTABLE) {
1641                         /* Resend from where the server left off */
1642                         hdr->mds_offset += resp->count;
1643                         argp->offset += resp->count;
1644                         argp->pgbase += resp->count;
1645                         argp->count -= resp->count;
1646                 } else {
1647                         /* Resend as a stable write in order to avoid
1648                          * headaches in the case of a server crash.
1649                          */
1650                         argp->stable = NFS_FILE_SYNC;
1651                 }
1652                 rpc_restart_call_prepare(task);
1653         }
1654 }
1655
1656 static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1657 {
1658         return wait_var_event_killable(&cinfo->rpcs_out,
1659                                        !atomic_read(&cinfo->rpcs_out));
1660 }
1661
1662 static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1663 {
1664         atomic_inc(&cinfo->rpcs_out);
1665 }
1666
1667 static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1668 {
1669         if (atomic_dec_and_test(&cinfo->rpcs_out))
1670                 wake_up_var(&cinfo->rpcs_out);
1671 }
1672
1673 void nfs_commitdata_release(struct nfs_commit_data *data)
1674 {
1675         put_nfs_open_context(data->context);
1676         nfs_commit_free(data);
1677 }
1678 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1679
1680 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1681                         const struct nfs_rpc_ops *nfs_ops,
1682                         const struct rpc_call_ops *call_ops,
1683                         int how, int flags)
1684 {
1685         struct rpc_task *task;
1686         int priority = flush_task_priority(how);
1687         struct rpc_message msg = {
1688                 .rpc_argp = &data->args,
1689                 .rpc_resp = &data->res,
1690                 .rpc_cred = data->cred,
1691         };
1692         struct rpc_task_setup task_setup_data = {
1693                 .task = &data->task,
1694                 .rpc_client = clnt,
1695                 .rpc_message = &msg,
1696                 .callback_ops = call_ops,
1697                 .callback_data = data,
1698                 .workqueue = nfsiod_workqueue,
1699                 .flags = RPC_TASK_ASYNC | flags,
1700                 .priority = priority,
1701         };
1702         /* Set up the initial task struct.  */
1703         nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1704         trace_nfs_initiate_commit(data);
1705
1706         dprintk("NFS: initiated commit call\n");
1707
1708         task = rpc_run_task(&task_setup_data);
1709         if (IS_ERR(task))
1710                 return PTR_ERR(task);
1711         if (how & FLUSH_SYNC)
1712                 rpc_wait_for_completion_task(task);
1713         rpc_put_task(task);
1714         return 0;
1715 }
1716 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1717
1718 static loff_t nfs_get_lwb(struct list_head *head)
1719 {
1720         loff_t lwb = 0;
1721         struct nfs_page *req;
1722
1723         list_for_each_entry(req, head, wb_list)
1724                 if (lwb < (req_offset(req) + req->wb_bytes))
1725                         lwb = req_offset(req) + req->wb_bytes;
1726
1727         return lwb;
1728 }
1729
1730 /*
1731  * Set up the argument/result storage required for the RPC call.
1732  */
1733 void nfs_init_commit(struct nfs_commit_data *data,
1734                      struct list_head *head,
1735                      struct pnfs_layout_segment *lseg,
1736                      struct nfs_commit_info *cinfo)
1737 {
1738         struct nfs_page *first = nfs_list_entry(head->next);
1739         struct nfs_open_context *ctx = nfs_req_openctx(first);
1740         struct inode *inode = d_inode(ctx->dentry);
1741
1742         /* Set up the RPC argument and reply structs
1743          * NB: take care not to mess about with data->commit et al. */
1744
1745         list_splice_init(head, &data->pages);
1746
1747         data->inode       = inode;
1748         data->cred        = ctx->cred;
1749         data->lseg        = lseg; /* reference transferred */
1750         /* only set lwb for pnfs commit */
1751         if (lseg)
1752                 data->lwb = nfs_get_lwb(&data->pages);
1753         data->mds_ops     = &nfs_commit_ops;
1754         data->completion_ops = cinfo->completion_ops;
1755         data->dreq        = cinfo->dreq;
1756
1757         data->args.fh     = NFS_FH(data->inode);
1758         /* Note: we always request a commit of the entire inode */
1759         data->args.offset = 0;
1760         data->args.count  = 0;
1761         data->context     = get_nfs_open_context(ctx);
1762         data->res.fattr   = &data->fattr;
1763         data->res.verf    = &data->verf;
1764         nfs_fattr_init(&data->fattr);
1765 }
1766 EXPORT_SYMBOL_GPL(nfs_init_commit);
1767
1768 void nfs_retry_commit(struct list_head *page_list,
1769                       struct pnfs_layout_segment *lseg,
1770                       struct nfs_commit_info *cinfo,
1771                       u32 ds_commit_idx)
1772 {
1773         struct nfs_page *req;
1774
1775         while (!list_empty(page_list)) {
1776                 req = nfs_list_entry(page_list->next);
1777                 nfs_list_remove_request(req);
1778                 nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1779                 if (!cinfo->dreq)
1780                         nfs_clear_page_commit(req->wb_page);
1781                 nfs_unlock_and_release_request(req);
1782         }
1783 }
1784 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1785
1786 static void
1787 nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1788                 struct nfs_page *req)
1789 {
1790         __set_page_dirty_nobuffers(req->wb_page);
1791 }
1792
1793 /*
1794  * Commit dirty pages
1795  */
1796 static int
1797 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1798                 struct nfs_commit_info *cinfo)
1799 {
1800         struct nfs_commit_data  *data;
1801
1802         /* another commit raced with us */
1803         if (list_empty(head))
1804                 return 0;
1805
1806         data = nfs_commitdata_alloc(true);
1807
1808         /* Set up the argument struct */
1809         nfs_init_commit(data, head, NULL, cinfo);
1810         atomic_inc(&cinfo->mds->rpcs_out);
1811         return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1812                                    data->mds_ops, how, 0);
1813 }
1814
1815 /*
1816  * COMMIT call returned
1817  */
1818 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1819 {
1820         struct nfs_commit_data  *data = calldata;
1821
1822         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1823                                 task->tk_pid, task->tk_status);
1824
1825         /* Call the NFS version-specific code */
1826         NFS_PROTO(data->inode)->commit_done(task, data);
1827         trace_nfs_commit_done(data);
1828 }
1829
1830 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1831 {
1832         struct nfs_page *req;
1833         int status = data->task.tk_status;
1834         struct nfs_commit_info cinfo;
1835         struct nfs_server *nfss;
1836
1837         while (!list_empty(&data->pages)) {
1838                 req = nfs_list_entry(data->pages.next);
1839                 nfs_list_remove_request(req);
1840                 if (req->wb_page)
1841                         nfs_clear_page_commit(req->wb_page);
1842
1843                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1844                         nfs_req_openctx(req)->dentry->d_sb->s_id,
1845                         (unsigned long long)NFS_FILEID(d_inode(nfs_req_openctx(req)->dentry)),
1846                         req->wb_bytes,
1847                         (long long)req_offset(req));
1848                 if (status < 0) {
1849                         if (req->wb_page) {
1850                                 nfs_mapping_set_error(req->wb_page, status);
1851                                 nfs_inode_remove_request(req);
1852                         }
1853                         dprintk_cont(", error = %d\n", status);
1854                         goto next;
1855                 }
1856
1857                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1858                  * returned by the server against all stored verfs. */
1859                 if (!nfs_write_verifier_cmp(&req->wb_verf, &data->verf.verifier)) {
1860                         /* We have a match */
1861                         if (req->wb_page)
1862                                 nfs_inode_remove_request(req);
1863                         dprintk_cont(" OK\n");
1864                         goto next;
1865                 }
1866                 /* We have a mismatch. Write the page again */
1867                 dprintk_cont(" mismatch\n");
1868                 nfs_mark_request_dirty(req);
1869                 set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1870         next:
1871                 nfs_unlock_and_release_request(req);
1872                 /* Latency breaker */
1873                 cond_resched();
1874         }
1875         nfss = NFS_SERVER(data->inode);
1876         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1877                 clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
1878
1879         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1880         nfs_commit_end(cinfo.mds);
1881 }
1882
1883 static void nfs_commit_release(void *calldata)
1884 {
1885         struct nfs_commit_data *data = calldata;
1886
1887         data->completion_ops->completion(data);
1888         nfs_commitdata_release(calldata);
1889 }
1890
1891 static const struct rpc_call_ops nfs_commit_ops = {
1892         .rpc_call_prepare = nfs_commit_prepare,
1893         .rpc_call_done = nfs_commit_done,
1894         .rpc_release = nfs_commit_release,
1895 };
1896
1897 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1898         .completion = nfs_commit_release_pages,
1899         .resched_write = nfs_commit_resched_write,
1900 };
1901
1902 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1903                             int how, struct nfs_commit_info *cinfo)
1904 {
1905         int status;
1906
1907         status = pnfs_commit_list(inode, head, how, cinfo);
1908         if (status == PNFS_NOT_ATTEMPTED)
1909                 status = nfs_commit_list(inode, head, how, cinfo);
1910         return status;
1911 }
1912
1913 static int __nfs_commit_inode(struct inode *inode, int how,
1914                 struct writeback_control *wbc)
1915 {
1916         LIST_HEAD(head);
1917         struct nfs_commit_info cinfo;
1918         int may_wait = how & FLUSH_SYNC;
1919         int ret, nscan;
1920
1921         nfs_init_cinfo_from_inode(&cinfo, inode);
1922         nfs_commit_begin(cinfo.mds);
1923         for (;;) {
1924                 ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1925                 if (ret <= 0)
1926                         break;
1927                 ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1928                 if (ret < 0)
1929                         break;
1930                 ret = 0;
1931                 if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1932                         if (nscan < wbc->nr_to_write)
1933                                 wbc->nr_to_write -= nscan;
1934                         else
1935                                 wbc->nr_to_write = 0;
1936                 }
1937                 if (nscan < INT_MAX)
1938                         break;
1939                 cond_resched();
1940         }
1941         nfs_commit_end(cinfo.mds);
1942         if (ret || !may_wait)
1943                 return ret;
1944         return wait_on_commit(cinfo.mds);
1945 }
1946
1947 int nfs_commit_inode(struct inode *inode, int how)
1948 {
1949         return __nfs_commit_inode(inode, how, NULL);
1950 }
1951 EXPORT_SYMBOL_GPL(nfs_commit_inode);
1952
1953 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1954 {
1955         struct nfs_inode *nfsi = NFS_I(inode);
1956         int flags = FLUSH_SYNC;
1957         int ret = 0;
1958
1959         if (wbc->sync_mode == WB_SYNC_NONE) {
1960                 /* no commits means nothing needs to be done */
1961                 if (!atomic_long_read(&nfsi->commit_info.ncommit))
1962                         goto check_requests_outstanding;
1963
1964                 /* Don't commit yet if this is a non-blocking flush and there
1965                  * are a lot of outstanding writes for this mapping.
1966                  */
1967                 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1968                         goto out_mark_dirty;
1969
1970                 /* don't wait for the COMMIT response */
1971                 flags = 0;
1972         }
1973
1974         ret = __nfs_commit_inode(inode, flags, wbc);
1975         if (!ret) {
1976                 if (flags & FLUSH_SYNC)
1977                         return 0;
1978         } else if (atomic_long_read(&nfsi->commit_info.ncommit))
1979                 goto out_mark_dirty;
1980
1981 check_requests_outstanding:
1982         if (!atomic_read(&nfsi->commit_info.rpcs_out))
1983                 return ret;
1984 out_mark_dirty:
1985         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1986         return ret;
1987 }
1988 EXPORT_SYMBOL_GPL(nfs_write_inode);
1989
1990 /*
1991  * Wrapper for filemap_write_and_wait_range()
1992  *
1993  * Needed for pNFS in order to ensure data becomes visible to the
1994  * client.
1995  */
1996 int nfs_filemap_write_and_wait_range(struct address_space *mapping,
1997                 loff_t lstart, loff_t lend)
1998 {
1999         int ret;
2000
2001         ret = filemap_write_and_wait_range(mapping, lstart, lend);
2002         if (ret == 0)
2003                 ret = pnfs_sync_inode(mapping->host, true);
2004         return ret;
2005 }
2006 EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
2007
2008 /*
2009  * flush the inode to disk.
2010  */
2011 int nfs_wb_all(struct inode *inode)
2012 {
2013         int ret;
2014
2015         trace_nfs_writeback_inode_enter(inode);
2016
2017         ret = filemap_write_and_wait(inode->i_mapping);
2018         if (ret)
2019                 goto out;
2020         ret = nfs_commit_inode(inode, FLUSH_SYNC);
2021         if (ret < 0)
2022                 goto out;
2023         pnfs_sync_inode(inode, true);
2024         ret = 0;
2025
2026 out:
2027         trace_nfs_writeback_inode_exit(inode, ret);
2028         return ret;
2029 }
2030 EXPORT_SYMBOL_GPL(nfs_wb_all);
2031
2032 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
2033 {
2034         struct nfs_page *req;
2035         int ret = 0;
2036
2037         wait_on_page_writeback(page);
2038
2039         /* blocking call to cancel all requests and join to a single (head)
2040          * request */
2041         req = nfs_lock_and_join_requests(page);
2042
2043         if (IS_ERR(req)) {
2044                 ret = PTR_ERR(req);
2045         } else if (req) {
2046                 /* all requests from this page have been cancelled by
2047                  * nfs_lock_and_join_requests, so just remove the head
2048                  * request from the inode / page_private pointer and
2049                  * release it */
2050                 nfs_inode_remove_request(req);
2051                 nfs_unlock_and_release_request(req);
2052         }
2053
2054         return ret;
2055 }
2056
2057 /*
2058  * Write back all requests on one page - we do this before reading it.
2059  */
2060 int nfs_wb_page(struct inode *inode, struct page *page)
2061 {
2062         loff_t range_start = page_file_offset(page);
2063         loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2064         struct writeback_control wbc = {
2065                 .sync_mode = WB_SYNC_ALL,
2066                 .nr_to_write = 0,
2067                 .range_start = range_start,
2068                 .range_end = range_end,
2069         };
2070         int ret;
2071
2072         trace_nfs_writeback_page_enter(inode);
2073
2074         for (;;) {
2075                 wait_on_page_writeback(page);
2076                 if (clear_page_dirty_for_io(page)) {
2077                         ret = nfs_writepage_locked(page, &wbc);
2078                         if (ret < 0)
2079                                 goto out_error;
2080                         continue;
2081                 }
2082                 ret = 0;
2083                 if (!PagePrivate(page))
2084                         break;
2085                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
2086                 if (ret < 0)
2087                         goto out_error;
2088         }
2089 out_error:
2090         trace_nfs_writeback_page_exit(inode, ret);
2091         return ret;
2092 }
2093
2094 #ifdef CONFIG_MIGRATION
2095 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
2096                 struct page *page, enum migrate_mode mode)
2097 {
2098         /*
2099          * If PagePrivate is set, then the page is currently associated with
2100          * an in-progress read or write request. Don't try to migrate it.
2101          *
2102          * FIXME: we could do this in principle, but we'll need a way to ensure
2103          *        that we can safely release the inode reference while holding
2104          *        the page lock.
2105          */
2106         if (PagePrivate(page))
2107                 return -EBUSY;
2108
2109         if (!nfs_fscache_release_page(page, GFP_KERNEL))
2110                 return -EBUSY;
2111
2112         return migrate_page(mapping, newpage, page, mode);
2113 }
2114 #endif
2115
2116 int __init nfs_init_writepagecache(void)
2117 {
2118         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2119                                              sizeof(struct nfs_pgio_header),
2120                                              0, SLAB_HWCACHE_ALIGN,
2121                                              NULL);
2122         if (nfs_wdata_cachep == NULL)
2123                 return -ENOMEM;
2124
2125         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2126                                                      nfs_wdata_cachep);
2127         if (nfs_wdata_mempool == NULL)
2128                 goto out_destroy_write_cache;
2129
2130         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2131                                              sizeof(struct nfs_commit_data),
2132                                              0, SLAB_HWCACHE_ALIGN,
2133                                              NULL);
2134         if (nfs_cdata_cachep == NULL)
2135                 goto out_destroy_write_mempool;
2136
2137         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2138                                                       nfs_cdata_cachep);
2139         if (nfs_commit_mempool == NULL)
2140                 goto out_destroy_commit_cache;
2141
2142         /*
2143          * NFS congestion size, scale with available memory.
2144          *
2145          *  64MB:    8192k
2146          * 128MB:   11585k
2147          * 256MB:   16384k
2148          * 512MB:   23170k
2149          *   1GB:   32768k
2150          *   2GB:   46340k
2151          *   4GB:   65536k
2152          *   8GB:   92681k
2153          *  16GB:  131072k
2154          *
2155          * This allows larger machines to have larger/more transfers.
2156          * Limit the default to 256M
2157          */
2158         nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2159         if (nfs_congestion_kb > 256*1024)
2160                 nfs_congestion_kb = 256*1024;
2161
2162         return 0;
2163
2164 out_destroy_commit_cache:
2165         kmem_cache_destroy(nfs_cdata_cachep);
2166 out_destroy_write_mempool:
2167         mempool_destroy(nfs_wdata_mempool);
2168 out_destroy_write_cache:
2169         kmem_cache_destroy(nfs_wdata_cachep);
2170         return -ENOMEM;
2171 }
2172
2173 void nfs_destroy_writepagecache(void)
2174 {
2175         mempool_destroy(nfs_commit_mempool);
2176         kmem_cache_destroy(nfs_cdata_cachep);
2177         mempool_destroy(nfs_wdata_mempool);
2178         kmem_cache_destroy(nfs_wdata_cachep);
2179 }
2180
2181 static const struct nfs_rw_ops nfs_rw_write_ops = {
2182         .rw_alloc_header        = nfs_writehdr_alloc,
2183         .rw_free_header         = nfs_writehdr_free,
2184         .rw_done                = nfs_writeback_done,
2185         .rw_result              = nfs_writeback_result,
2186         .rw_initiate            = nfs_initiate_write,
2187 };