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 void
 153 nfs_page_set_inode_ref(struct nfs_page *req, struct inode *inode)
 154 {
 155         if (!test_and_set_bit(PG_INODE_REF, &req->wb_flags)) {
 156                 kref_get(&req->wb_kref);
 157                 atomic_long_inc(&NFS_I(inode)->nrequests);
 158         }
 159 }
 160
 161 static int
 162 nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode)
 163 {
 164         int ret;
 165
 166         if (!test_bit(PG_REMOVE, &req->wb_flags))
 167                 return 0;
 168         ret = nfs_page_group_lock(req);
 169         if (ret)
 170                 return ret;
 171         if (test_and_clear_bit(PG_REMOVE, &req->wb_flags))
 172                 nfs_page_set_inode_ref(req, inode);
 173         nfs_page_group_unlock(req);
 174         return 0;
 175 }
 176
 177 static struct nfs_page *
 178 nfs_page_private_request(struct page *page)
 179 {
 180         if (!PagePrivate(page))
 181                 return NULL;
 182         return (struct nfs_page *)page_private(page);
 183 }
 184
 185 /*
 186  * nfs_page_find_head_request_locked - find head request associated with @page
 187  *
 188  * must be called while holding the inode lock.
 189  *
 190  * returns matching head request with reference held, or NULL if not found.
 191  */
 192 static struct nfs_page *
 193 nfs_page_find_private_request(struct page *page)
 194 {
 195         struct address_space *mapping = page_file_mapping(page);
 196         struct nfs_page *req;
 197
 198         if (!PagePrivate(page))
 199                 return NULL;
 200         spin_lock(&mapping->private_lock);
 201         req = nfs_page_private_request(page);
 202         if (req) {
 203                 WARN_ON_ONCE(req->wb_head != req);
 204                 kref_get(&req->wb_kref);
 205         }
 206         spin_unlock(&mapping->private_lock);
 207         return req;
 208 }
 209
 210 static struct nfs_page *
 211 nfs_page_find_swap_request(struct page *page)
 212 {
 213         struct inode *inode = page_file_mapping(page)->host;
 214         struct nfs_inode *nfsi = NFS_I(inode);
 215         struct nfs_page *req = NULL;
 216         if (!PageSwapCache(page))
 217                 return NULL;
 218         mutex_lock(&nfsi->commit_mutex);
 219         if (PageSwapCache(page)) {
 220                 req = nfs_page_search_commits_for_head_request_locked(nfsi,
 221                         page);
 222                 if (req) {
 223                         WARN_ON_ONCE(req->wb_head != req);
 224                         kref_get(&req->wb_kref);
 225                 }
 226         }
 227         mutex_unlock(&nfsi->commit_mutex);
 228         return req;
 229 }
 230
 231 /*
 232  * nfs_page_find_head_request - find head request associated with @page
 233  *
 234  * returns matching head request with reference held, or NULL if not found.
 235  */
 236 static struct nfs_page *nfs_page_find_head_request(struct page *page)
 237 {
 238         struct nfs_page *req;
 239
 240         req = nfs_page_find_private_request(page);
 241         if (!req)
 242                 req = nfs_page_find_swap_request(page);
 243         return req;
 244 }
 245
 246 static struct nfs_page *nfs_find_and_lock_page_request(struct page *page)
 247 {
 248         struct inode *inode = page_file_mapping(page)->host;
 249         struct nfs_page *req, *head;
 250         int ret;
 251
 252         for (;;) {
 253                 req = nfs_page_find_head_request(page);
 254                 if (!req)
 255                         return req;
 256                 head = nfs_page_group_lock_head(req);
 257                 if (head != req)
 258                         nfs_release_request(req);
 259                 if (IS_ERR(head))
 260                         return head;
 261                 ret = nfs_cancel_remove_inode(head, inode);
 262                 if (ret < 0) {
 263                         nfs_unlock_and_release_request(head);
 264                         return ERR_PTR(ret);
 265                 }
 266                 /* Ensure that nobody removed the request before we locked it */
 267                 if (head == nfs_page_private_request(page))
 268                         break;
 269                 if (PageSwapCache(page))
 270                         break;
 271                 nfs_unlock_and_release_request(head);
 272         }
 273         return head;
 274 }
 275
 276 /* Adjust the file length if we're writing beyond the end */
 277 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 278 {
 279         struct inode *inode = page_file_mapping(page)->host;
 280         loff_t end, i_size;
 281         pgoff_t end_index;
 282
 283         spin_lock(&inode->i_lock);
 284         i_size = i_size_read(inode);
 285         end_index = (i_size - 1) >> PAGE_SHIFT;
 286         if (i_size > 0 && page_index(page) < end_index)
 287                 goto out;
 288         end = page_file_offset(page) + ((loff_t)offset+count);
 289         if (i_size >= end)
 290                 goto out;
 291         i_size_write(inode, end);
 292         NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
 293         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 294 out:
 295         spin_unlock(&inode->i_lock);
 296 }
 297
 298 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 299 static void nfs_set_pageerror(struct address_space *mapping)
 300 {
 301         struct inode *inode = mapping->host;
 302
 303         nfs_zap_mapping(mapping->host, mapping);
 304         /* Force file size revalidation */
 305         spin_lock(&inode->i_lock);
 306         nfs_set_cache_invalid(inode, NFS_INO_REVAL_FORCED |
 307                                              NFS_INO_REVAL_PAGECACHE |
 308                                              NFS_INO_INVALID_SIZE);
 309         spin_unlock(&inode->i_lock);
 310 }
 311
 312 static void nfs_mapping_set_error(struct page *page, int error)
 313 {
 314         struct address_space *mapping = page_file_mapping(page);
 315
 316         SetPageError(page);
 317         mapping_set_error(mapping, error);
 318         nfs_set_pageerror(mapping);
 319 }
 320
 321 /*
 322  * nfs_page_group_search_locked
 323  * @head - head request of page group
 324  * @page_offset - offset into page
 325  *
 326  * Search page group with head @head to find a request that contains the
 327  * page offset @page_offset.
 328  *
 329  * Returns a pointer to the first matching nfs request, or NULL if no
 330  * match is found.
 331  *
 332  * Must be called with the page group lock held
 333  */
 334 static struct nfs_page *
 335 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
 336 {
 337         struct nfs_page *req;
 338
 339         req = head;
 340         do {
 341                 if (page_offset >= req->wb_pgbase &&
 342                     page_offset < (req->wb_pgbase + req->wb_bytes))
 343                         return req;
 344
 345                 req = req->wb_this_page;
 346         } while (req != head);
 347
 348         return NULL;
 349 }
 350
 351 /*
 352  * nfs_page_group_covers_page
 353  * @head - head request of page group
 354  *
 355  * Return true if the page group with head @head covers the whole page,
 356  * returns false otherwise
 357  */
 358 static bool nfs_page_group_covers_page(struct nfs_page *req)
 359 {
 360         struct nfs_page *tmp;
 361         unsigned int pos = 0;
 362         unsigned int len = nfs_page_length(req->wb_page);
 363
 364         nfs_page_group_lock(req);
 365
 366         for (;;) {
 367                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
 368                 if (!tmp)
 369                         break;
 370                 pos = tmp->wb_pgbase + tmp->wb_bytes;
 371         }
 372
 373         nfs_page_group_unlock(req);
 374         return pos >= len;
 375 }
 376
 377 /* We can set the PG_uptodate flag if we see that a write request
 378  * covers the full page.
 379  */
 380 static void nfs_mark_uptodate(struct nfs_page *req)
 381 {
 382         if (PageUptodate(req->wb_page))
 383                 return;
 384         if (!nfs_page_group_covers_page(req))
 385                 return;
 386         SetPageUptodate(req->wb_page);
 387 }
 388
 389 static int wb_priority(struct writeback_control *wbc)
 390 {
 391         int ret = 0;
 392
 393         if (wbc->sync_mode == WB_SYNC_ALL)
 394                 ret = FLUSH_COND_STABLE;
 395         return ret;
 396 }
 397
 398 /*
 399  * NFS congestion control
 400  */
 401
 402 int nfs_congestion_kb;
 403
 404 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 405 #define NFS_CONGESTION_OFF_THRESH       \
 406         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 407
 408 static void nfs_set_page_writeback(struct page *page)
 409 {
 410         struct inode *inode = page_file_mapping(page)->host;
 411         struct nfs_server *nfss = NFS_SERVER(inode);
 412         int ret = test_set_page_writeback(page);
 413
 414         WARN_ON_ONCE(ret != 0);
 415
 416         if (atomic_long_inc_return(&nfss->writeback) >
 417                         NFS_CONGESTION_ON_THRESH)
 418                 set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 419 }
 420
 421 static void nfs_end_page_writeback(struct nfs_page *req)
 422 {
 423         struct inode *inode = page_file_mapping(req->wb_page)->host;
 424         struct nfs_server *nfss = NFS_SERVER(inode);
 425         bool is_done;
 426
 427         is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
 428         nfs_unlock_request(req);
 429         if (!is_done)
 430                 return;
 431
 432         end_page_writeback(req->wb_page);
 433         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 434                 clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 435 }
 436
 437 /*
 438  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
 439  *
 440  * @destroy_list - request list (using wb_this_page) terminated by @old_head
 441  * @old_head - the old head of the list
 442  *
 443  * All subrequests must be locked and removed from all lists, so at this point
 444  * they are only "active" in this function, and possibly in nfs_wait_on_request
 445  * with a reference held by some other context.
 446  */
 447 static void
 448 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 449                                  struct nfs_page *old_head,
 450                                  struct inode *inode)
 451 {
 452         while (destroy_list) {
 453                 struct nfs_page *subreq = destroy_list;
 454
 455                 destroy_list = (subreq->wb_this_page == old_head) ?
 456                                    NULL : subreq->wb_this_page;
 457
 458                 /* Note: lock subreq in order to change subreq->wb_head */
 459                 nfs_page_set_headlock(subreq);
 460                 WARN_ON_ONCE(old_head != subreq->wb_head);
 461
 462                 /* make sure old group is not used */
 463                 subreq->wb_this_page = subreq;
 464                 subreq->wb_head = subreq;
 465
 466                 clear_bit(PG_REMOVE, &subreq->wb_flags);
 467
 468                 /* Note: races with nfs_page_group_destroy() */
 469                 if (!kref_read(&subreq->wb_kref)) {
 470                         /* Check if we raced with nfs_page_group_destroy() */
 471                         if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags)) {
 472                                 nfs_page_clear_headlock(subreq);
 473                                 nfs_free_request(subreq);
 474                         } else
 475                                 nfs_page_clear_headlock(subreq);
 476                         continue;
 477                 }
 478                 nfs_page_clear_headlock(subreq);
 479
 480                 nfs_release_request(old_head);
 481
 482                 if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 483                         nfs_release_request(subreq);
 484                         atomic_long_dec(&NFS_I(inode)->nrequests);
 485                 }
 486
 487                 /* subreq is now totally disconnected from page group or any
 488                  * write / commit lists. last chance to wake any waiters */
 489                 nfs_unlock_and_release_request(subreq);
 490         }
 491 }
 492
 493 /*
 494  * nfs_join_page_group - destroy subrequests of the head req
 495  * @head: the page used to lookup the "page group" of nfs_page structures
 496  * @inode: Inode to which the request belongs.
 497  *
 498  * This function joins all sub requests to the head request by first
 499  * locking all requests in the group, cancelling any pending operations
 500  * and finally updating the head request to cover the whole range covered by
 501  * the (former) group.  All subrequests are removed from any write or commit
 502  * lists, unlinked from the group and destroyed.
 503  */
 504 void
 505 nfs_join_page_group(struct nfs_page *head, struct inode *inode)
 506 {
 507         struct nfs_page *subreq;
 508         struct nfs_page *destroy_list = NULL;
 509         unsigned int pgbase, off, bytes;
 510
 511         pgbase = head->wb_pgbase;
 512         bytes = head->wb_bytes;
 513         off = head->wb_offset;
 514         for (subreq = head->wb_this_page; subreq != head;
 515                         subreq = subreq->wb_this_page) {
 516                 /* Subrequests should always form a contiguous range */
 517                 if (pgbase > subreq->wb_pgbase) {
 518                         off -= pgbase - subreq->wb_pgbase;
 519                         bytes += pgbase - subreq->wb_pgbase;
 520                         pgbase = subreq->wb_pgbase;
 521                 }
 522                 bytes = max(subreq->wb_pgbase + subreq->wb_bytes
 523                                 - pgbase, bytes);
 524         }
 525
 526         /* Set the head request's range to cover the former page group */
 527         head->wb_pgbase = pgbase;
 528         head->wb_bytes = bytes;
 529         head->wb_offset = off;
 530
 531         /* Now that all requests are locked, make sure they aren't on any list.
 532          * Commit list removal accounting is done after locks are dropped */
 533         subreq = head;
 534         do {
 535                 nfs_clear_request_commit(subreq);
 536                 subreq = subreq->wb_this_page;
 537         } while (subreq != head);
 538
 539         /* unlink subrequests from head, destroy them later */
 540         if (head->wb_this_page != head) {
 541                 /* destroy list will be terminated by head */
 542                 destroy_list = head->wb_this_page;
 543                 head->wb_this_page = head;
 544         }
 545
 546         nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 547 }
 548
 549 /*
 550  * nfs_lock_and_join_requests - join all subreqs to the head req
 551  * @page: the page used to lookup the "page group" of nfs_page structures
 552  *
 553  * This function joins all sub requests to the head request by first
 554  * locking all requests in the group, cancelling any pending operations
 555  * and finally updating the head request to cover the whole range covered by
 556  * the (former) group.  All subrequests are removed from any write or commit
 557  * lists, unlinked from the group and destroyed.
 558  *
 559  * Returns a locked, referenced pointer to the head request - which after
 560  * this call is guaranteed to be the only request associated with the page.
 561  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
 562  * error was encountered.
 563  */
 564 static struct nfs_page *
 565 nfs_lock_and_join_requests(struct page *page)
 566 {
 567         struct inode *inode = page_file_mapping(page)->host;
 568         struct nfs_page *head;
 569         int ret;
 570
 571         /*
 572          * A reference is taken only on the head request which acts as a
 573          * reference to the whole page group - the group will not be destroyed
 574          * until the head reference is released.
 575          */
 576         head = nfs_find_and_lock_page_request(page);
 577         if (IS_ERR_OR_NULL(head))
 578                 return head;
 579
 580         /* lock each request in the page group */
 581         ret = nfs_page_group_lock_subrequests(head);
 582         if (ret < 0) {
 583                 nfs_unlock_and_release_request(head);
 584                 return ERR_PTR(ret);
 585         }
 586
 587         nfs_join_page_group(head, inode);
 588
 589         return head;
 590 }
 591
 592 static void nfs_write_error(struct nfs_page *req, int error)
 593 {
 594         trace_nfs_write_error(req, error);
 595         nfs_mapping_set_error(req->wb_page, error);
 596         nfs_inode_remove_request(req);
 597         nfs_end_page_writeback(req);
 598         nfs_release_request(req);
 599 }
 600
 601 /*
 602  * Find an associated nfs write request, and prepare to flush it out
 603  * May return an error if the user signalled nfs_wait_on_request().
 604  */
 605 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 606                                 struct page *page)
 607 {
 608         struct nfs_page *req;
 609         int ret = 0;
 610
 611         req = nfs_lock_and_join_requests(page);
 612         if (!req)
 613                 goto out;
 614         ret = PTR_ERR(req);
 615         if (IS_ERR(req))
 616                 goto out;
 617
 618         nfs_set_page_writeback(page);
 619         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 620
 621         /* If there is a fatal error that covers this write, just exit */
 622         ret = pgio->pg_error;
 623         if (nfs_error_is_fatal_on_server(ret))
 624                 goto out_launder;
 625
 626         ret = 0;
 627         if (!nfs_pageio_add_request(pgio, req)) {
 628                 ret = pgio->pg_error;
 629                 /*
 630                  * Remove the problematic req upon fatal errors on the server
 631                  */
 632                 if (nfs_error_is_fatal(ret)) {
 633                         if (nfs_error_is_fatal_on_server(ret))
 634                                 goto out_launder;
 635                 } else
 636                         ret = -EAGAIN;
 637                 nfs_redirty_request(req);
 638                 pgio->pg_error = 0;
 639         } else
 640                 nfs_add_stats(page_file_mapping(page)->host,
 641                                 NFSIOS_WRITEPAGES, 1);
 642 out:
 643         return ret;
 644 out_launder:
 645         nfs_write_error(req, ret);
 646         return 0;
 647 }
 648
 649 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
 650                             struct nfs_pageio_descriptor *pgio)
 651 {
 652         int ret;
 653
 654         nfs_pageio_cond_complete(pgio, page_index(page));
 655         ret = nfs_page_async_flush(pgio, page);
 656         if (ret == -EAGAIN) {
 657                 redirty_page_for_writepage(wbc, page);
 658                 ret = AOP_WRITEPAGE_ACTIVATE;
 659         }
 660         return ret;
 661 }
 662
 663 /*
 664  * Write an mmapped page to the server.
 665  */
 666 static int nfs_writepage_locked(struct page *page,
 667                                 struct writeback_control *wbc)
 668 {
 669         struct nfs_pageio_descriptor pgio;
 670         struct inode *inode = page_file_mapping(page)->host;
 671         int err;
 672
 673         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 674         nfs_pageio_init_write(&pgio, inode, 0,
 675                                 false, &nfs_async_write_completion_ops);
 676         err = nfs_do_writepage(page, wbc, &pgio);
 677         pgio.pg_error = 0;
 678         nfs_pageio_complete(&pgio);
 679         if (err < 0)
 680                 return err;
 681         if (nfs_error_is_fatal(pgio.pg_error))
 682                 return pgio.pg_error;
 683         return 0;
 684 }
 685
 686 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 687 {
 688         int ret;
 689
 690         ret = nfs_writepage_locked(page, wbc);
 691         if (ret != AOP_WRITEPAGE_ACTIVATE)
 692                 unlock_page(page);
 693         return ret;
 694 }
 695
 696 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 697 {
 698         int ret;
 699
 700         ret = nfs_do_writepage(page, wbc, data);
 701         if (ret != AOP_WRITEPAGE_ACTIVATE)
 702                 unlock_page(page);
 703         return ret;
 704 }
 705
 706 static void nfs_io_completion_commit(void *inode)
 707 {
 708         nfs_commit_inode(inode, 0);
 709 }
 710
 711 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 712 {
 713         struct inode *inode = mapping->host;
 714         struct nfs_pageio_descriptor pgio;
 715         struct nfs_io_completion *ioc = NULL;
 716         unsigned int mntflags = NFS_SERVER(inode)->flags;
 717         int priority = 0;
 718         int err;
 719
 720         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 721
 722         if (!(mntflags & NFS_MOUNT_WRITE_EAGER) || wbc->for_kupdate ||
 723             wbc->for_background || wbc->for_sync || wbc->for_reclaim) {
 724                 ioc = nfs_io_completion_alloc(GFP_KERNEL);
 725                 if (ioc)
 726                         nfs_io_completion_init(ioc, nfs_io_completion_commit,
 727                                                inode);
 728                 priority = wb_priority(wbc);
 729         }
 730
 731         nfs_pageio_init_write(&pgio, inode, priority, false,
 732                                 &nfs_async_write_completion_ops);
 733         pgio.pg_io_completion = ioc;
 734         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 735         pgio.pg_error = 0;
 736         nfs_pageio_complete(&pgio);
 737         nfs_io_completion_put(ioc);
 738
 739         if (err < 0)
 740                 goto out_err;
 741         err = pgio.pg_error;
 742         if (nfs_error_is_fatal(err))
 743                 goto out_err;
 744         return 0;
 745 out_err:
 746         return err;
 747 }
 748
 749 /*
 750  * Insert a write request into an inode
 751  */
 752 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 753 {
 754         struct address_space *mapping = page_file_mapping(req->wb_page);
 755         struct nfs_inode *nfsi = NFS_I(inode);
 756
 757         WARN_ON_ONCE(req->wb_this_page != req);
 758
 759         /* Lock the request! */
 760         nfs_lock_request(req);
 761
 762         /*
 763          * Swap-space should not get truncated. Hence no need to plug the race
 764          * with invalidate/truncate.
 765          */
 766         spin_lock(&mapping->private_lock);
 767         if (likely(!PageSwapCache(req->wb_page))) {
 768                 set_bit(PG_MAPPED, &req->wb_flags);
 769                 SetPagePrivate(req->wb_page);
 770                 set_page_private(req->wb_page, (unsigned long)req);
 771         }
 772         spin_unlock(&mapping->private_lock);
 773         atomic_long_inc(&nfsi->nrequests);
 774         /* this a head request for a page group - mark it as having an
 775          * extra reference so sub groups can follow suit.
 776          * This flag also informs pgio layer when to bump nrequests when
 777          * adding subrequests. */
 778         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 779         kref_get(&req->wb_kref);
 780 }
 781
 782 /*
 783  * Remove a write request from an inode
 784  */
 785 static void nfs_inode_remove_request(struct nfs_page *req)
 786 {
 787         struct address_space *mapping = page_file_mapping(req->wb_page);
 788         struct inode *inode = mapping->host;
 789         struct nfs_inode *nfsi = NFS_I(inode);
 790         struct nfs_page *head;
 791
 792         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
 793                 head = req->wb_head;
 794
 795                 spin_lock(&mapping->private_lock);
 796                 if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
 797                         set_page_private(head->wb_page, 0);
 798                         ClearPagePrivate(head->wb_page);
 799                         clear_bit(PG_MAPPED, &head->wb_flags);
 800                 }
 801                 spin_unlock(&mapping->private_lock);
 802         }
 803
 804         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags)) {
 805                 nfs_release_request(req);
 806                 atomic_long_dec(&nfsi->nrequests);
 807         }
 808 }
 809
 810 static void
 811 nfs_mark_request_dirty(struct nfs_page *req)
 812 {
 813         if (req->wb_page)
 814                 __set_page_dirty_nobuffers(req->wb_page);
 815 }
 816
 817 /*
 818  * nfs_page_search_commits_for_head_request_locked
 819  *
 820  * Search through commit lists on @inode for the head request for @page.
 821  * Must be called while holding the inode (which is cinfo) lock.
 822  *
 823  * Returns the head request if found, or NULL if not found.
 824  */
 825 static struct nfs_page *
 826 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 827                                                 struct page *page)
 828 {
 829         struct nfs_page *freq, *t;
 830         struct nfs_commit_info cinfo;
 831         struct inode *inode = &nfsi->vfs_inode;
 832
 833         nfs_init_cinfo_from_inode(&cinfo, inode);
 834
 835         /* search through pnfs commit lists */
 836         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
 837         if (freq)
 838                 return freq->wb_head;
 839
 840         /* Linearly search the commit list for the correct request */
 841         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
 842                 if (freq->wb_page == page)
 843                         return freq->wb_head;
 844         }
 845
 846         return NULL;
 847 }
 848
 849 /**
 850  * nfs_request_add_commit_list_locked - add request to a commit list
 851  * @req: pointer to a struct nfs_page
 852  * @dst: commit list head
 853  * @cinfo: holds list lock and accounting info
 854  *
 855  * This sets the PG_CLEAN bit, updates the cinfo count of
 856  * number of outstanding requests requiring a commit as well as
 857  * the MM page stats.
 858  *
 859  * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
 860  * nfs_page lock.
 861  */
 862 void
 863 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
 864                             struct nfs_commit_info *cinfo)
 865 {
 866         set_bit(PG_CLEAN, &req->wb_flags);
 867         nfs_list_add_request(req, dst);
 868         atomic_long_inc(&cinfo->mds->ncommit);
 869 }
 870 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 871
 872 /**
 873  * nfs_request_add_commit_list - add request to a commit list
 874  * @req: pointer to a struct nfs_page
 875  * @cinfo: holds list lock and accounting info
 876  *
 877  * This sets the PG_CLEAN bit, updates the cinfo count of
 878  * number of outstanding requests requiring a commit as well as
 879  * the MM page stats.
 880  *
 881  * The caller must _not_ hold the cinfo->lock, but must be
 882  * holding the nfs_page lock.
 883  */
 884 void
 885 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 886 {
 887         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 888         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
 889         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 890         if (req->wb_page)
 891                 nfs_mark_page_unstable(req->wb_page, cinfo);
 892 }
 893 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 894
 895 /**
 896  * nfs_request_remove_commit_list - Remove request from a commit list
 897  * @req: pointer to a nfs_page
 898  * @cinfo: holds list lock and accounting info
 899  *
 900  * This clears the PG_CLEAN bit, and updates the cinfo's count of
 901  * number of outstanding requests requiring a commit
 902  * It does not update the MM page stats.
 903  *
 904  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 905  */
 906 void
 907 nfs_request_remove_commit_list(struct nfs_page *req,
 908                                struct nfs_commit_info *cinfo)
 909 {
 910         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 911                 return;
 912         nfs_list_remove_request(req);
 913         atomic_long_dec(&cinfo->mds->ncommit);
 914 }
 915 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 916
 917 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 918                                       struct inode *inode)
 919 {
 920         cinfo->inode = inode;
 921         cinfo->mds = &NFS_I(inode)->commit_info;
 922         cinfo->ds = pnfs_get_ds_info(inode);
 923         cinfo->dreq = NULL;
 924         cinfo->completion_ops = &nfs_commit_completion_ops;
 925 }
 926
 927 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 928                     struct inode *inode,
 929                     struct nfs_direct_req *dreq)
 930 {
 931         if (dreq)
 932                 nfs_init_cinfo_from_dreq(cinfo, dreq);
 933         else
 934                 nfs_init_cinfo_from_inode(cinfo, inode);
 935 }
 936 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 937
 938 /*
 939  * Add a request to the inode's commit list.
 940  */
 941 void
 942 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 943                         struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 944 {
 945         if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 946                 return;
 947         nfs_request_add_commit_list(req, cinfo);
 948 }
 949
 950 static void
 951 nfs_clear_page_commit(struct page *page)
 952 {
 953         dec_node_page_state(page, NR_WRITEBACK);
 954         dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
 955                     WB_WRITEBACK);
 956 }
 957
 958 /* Called holding the request lock on @req */
 959 static void
 960 nfs_clear_request_commit(struct nfs_page *req)
 961 {
 962         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 963                 struct nfs_open_context *ctx = nfs_req_openctx(req);
 964                 struct inode *inode = d_inode(ctx->dentry);
 965                 struct nfs_commit_info cinfo;
 966
 967                 nfs_init_cinfo_from_inode(&cinfo, inode);
 968                 mutex_lock(&NFS_I(inode)->commit_mutex);
 969                 if (!pnfs_clear_request_commit(req, &cinfo)) {
 970                         nfs_request_remove_commit_list(req, &cinfo);
 971                 }
 972                 mutex_unlock(&NFS_I(inode)->commit_mutex);
 973                 nfs_clear_page_commit(req->wb_page);
 974         }
 975 }
 976
 977 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 978 {
 979         if (hdr->verf.committed == NFS_DATA_SYNC)
 980                 return hdr->lseg == NULL;
 981         return hdr->verf.committed != NFS_FILE_SYNC;
 982 }
 983
 984 static void nfs_async_write_init(struct nfs_pgio_header *hdr)
 985 {
 986         nfs_io_completion_get(hdr->io_completion);
 987 }
 988
 989 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 990 {
 991         struct nfs_commit_info cinfo;
 992         unsigned long bytes = 0;
 993
 994         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 995                 goto out;
 996         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
 997         while (!list_empty(&hdr->pages)) {
 998                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 999
1000                 bytes += req->wb_bytes;
1001                 nfs_list_remove_request(req);
1002                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
1003                     (hdr->good_bytes < bytes)) {
1004                         trace_nfs_comp_error(req, hdr->error);
1005                         nfs_mapping_set_error(req->wb_page, hdr->error);
1006                         goto remove_req;
1007                 }
1008                 if (nfs_write_need_commit(hdr)) {
1009                         /* Reset wb_nio, since the write was successful. */
1010                         req->wb_nio = 0;
1011                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1012                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1013                                 hdr->pgio_mirror_idx);
1014                         goto next;
1015                 }
1016 remove_req:
1017                 nfs_inode_remove_request(req);
1018 next:
1019                 nfs_end_page_writeback(req);
1020                 nfs_release_request(req);
1021         }
1022 out:
1023         nfs_io_completion_put(hdr->io_completion);
1024         hdr->release(hdr);
1025 }
1026
1027 unsigned long
1028 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1029 {
1030         return atomic_long_read(&cinfo->mds->ncommit);
1031 }
1032
1033 /* NFS_I(cinfo->inode)->commit_mutex held by caller */
1034 int
1035 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1036                      struct nfs_commit_info *cinfo, int max)
1037 {
1038         struct nfs_page *req, *tmp;
1039         int ret = 0;
1040
1041 restart:
1042         list_for_each_entry_safe(req, tmp, src, wb_list) {
1043                 kref_get(&req->wb_kref);
1044                 if (!nfs_lock_request(req)) {
1045                         int status;
1046
1047                         /* Prevent deadlock with nfs_lock_and_join_requests */
1048                         if (!list_empty(dst)) {
1049                                 nfs_release_request(req);
1050                                 continue;
1051                         }
1052                         /* Ensure we make progress to prevent livelock */
1053                         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1054                         status = nfs_wait_on_request(req);
1055                         nfs_release_request(req);
1056                         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1057                         if (status < 0)
1058                                 break;
1059                         goto restart;
1060                 }
1061                 nfs_request_remove_commit_list(req, cinfo);
1062                 clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1063                 nfs_list_add_request(req, dst);
1064                 ret++;
1065                 if ((ret == max) && !cinfo->dreq)
1066                         break;
1067                 cond_resched();
1068         }
1069         return ret;
1070 }
1071 EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1072
1073 /*
1074  * nfs_scan_commit - Scan an inode for commit requests
1075  * @inode: NFS inode to scan
1076  * @dst: mds destination list
1077  * @cinfo: mds and ds lists of reqs ready to commit
1078  *
1079  * Moves requests from the inode's 'commit' request list.
1080  * The requests are *not* checked to ensure that they form a contiguous set.
1081  */
1082 int
1083 nfs_scan_commit(struct inode *inode, struct list_head *dst,
1084                 struct nfs_commit_info *cinfo)
1085 {
1086         int ret = 0;
1087
1088         if (!atomic_long_read(&cinfo->mds->ncommit))
1089                 return 0;
1090         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1091         if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1092                 const int max = INT_MAX;
1093
1094                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1095                                            cinfo, max);
1096                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1097         }
1098         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1099         return ret;
1100 }
1101
1102 /*
1103  * Search for an existing write request, and attempt to update
1104  * it to reflect a new dirty region on a given page.
1105  *
1106  * If the attempt fails, then the existing request is flushed out
1107  * to disk.
1108  */
1109 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1110                 struct page *page,
1111                 unsigned int offset,
1112                 unsigned int bytes)
1113 {
1114         struct nfs_page *req;
1115         unsigned int rqend;
1116         unsigned int end;
1117         int error;
1118
1119         end = offset + bytes;
1120
1121         req = nfs_lock_and_join_requests(page);
1122         if (IS_ERR_OR_NULL(req))
1123                 return req;
1124
1125         rqend = req->wb_offset + req->wb_bytes;
1126         /*
1127          * Tell the caller to flush out the request if
1128          * the offsets are non-contiguous.
1129          * Note: nfs_flush_incompatible() will already
1130          * have flushed out requests having wrong owners.
1131          */
1132         if (offset > rqend || end < req->wb_offset)
1133                 goto out_flushme;
1134
1135         /* Okay, the request matches. Update the region */
1136         if (offset < req->wb_offset) {
1137                 req->wb_offset = offset;
1138                 req->wb_pgbase = offset;
1139         }
1140         if (end > rqend)
1141                 req->wb_bytes = end - req->wb_offset;
1142         else
1143                 req->wb_bytes = rqend - req->wb_offset;
1144         req->wb_nio = 0;
1145         return req;
1146 out_flushme:
1147         /*
1148          * Note: we mark the request dirty here because
1149          * nfs_lock_and_join_requests() cannot preserve
1150          * commit flags, so we have to replay the write.
1151          */
1152         nfs_mark_request_dirty(req);
1153         nfs_unlock_and_release_request(req);
1154         error = nfs_wb_page(inode, page);
1155         return (error < 0) ? ERR_PTR(error) : NULL;
1156 }
1157
1158 /*
1159  * Try to update an existing write request, or create one if there is none.
1160  *
1161  * Note: Should always be called with the Page Lock held to prevent races
1162  * if we have to add a new request. Also assumes that the caller has
1163  * already called nfs_flush_incompatible() if necessary.
1164  */
1165 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1166                 struct page *page, unsigned int offset, unsigned int bytes)
1167 {
1168         struct inode *inode = page_file_mapping(page)->host;
1169         struct nfs_page *req;
1170
1171         req = nfs_try_to_update_request(inode, page, offset, bytes);
1172         if (req != NULL)
1173                 goto out;
1174         req = nfs_create_request(ctx, page, offset, bytes);
1175         if (IS_ERR(req))
1176                 goto out;
1177         nfs_inode_add_request(inode, req);
1178 out:
1179         return req;
1180 }
1181
1182 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1183                 unsigned int offset, unsigned int count)
1184 {
1185         struct nfs_page *req;
1186
1187         req = nfs_setup_write_request(ctx, page, offset, count);
1188         if (IS_ERR(req))
1189                 return PTR_ERR(req);
1190         /* Update file length */
1191         nfs_grow_file(page, offset, count);
1192         nfs_mark_uptodate(req);
1193         nfs_mark_request_dirty(req);
1194         nfs_unlock_and_release_request(req);
1195         return 0;
1196 }
1197
1198 int nfs_flush_incompatible(struct file *file, struct page *page)
1199 {
1200         struct nfs_open_context *ctx = nfs_file_open_context(file);
1201         struct nfs_lock_context *l_ctx;
1202         struct file_lock_context *flctx = file_inode(file)->i_flctx;
1203         struct nfs_page *req;
1204         int do_flush, status;
1205         /*
1206          * Look for a request corresponding to this page. If there
1207          * is one, and it belongs to another file, we flush it out
1208          * before we try to copy anything into the page. Do this
1209          * due to the lack of an ACCESS-type call in NFSv2.
1210          * Also do the same if we find a request from an existing
1211          * dropped page.
1212          */
1213         do {
1214                 req = nfs_page_find_head_request(page);
1215                 if (req == NULL)
1216                         return 0;
1217                 l_ctx = req->wb_lock_context;
1218                 do_flush = req->wb_page != page ||
1219                         !nfs_match_open_context(nfs_req_openctx(req), ctx);
1220                 if (l_ctx && flctx &&
1221                     !(list_empty_careful(&flctx->flc_posix) &&
1222                       list_empty_careful(&flctx->flc_flock))) {
1223                         do_flush |= l_ctx->lockowner != current->files;
1224                 }
1225                 nfs_release_request(req);
1226                 if (!do_flush)
1227                         return 0;
1228                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1229         } while (status == 0);
1230         return status;
1231 }
1232
1233 /*
1234  * Avoid buffered writes when a open context credential's key would
1235  * expire soon.
1236  *
1237  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1238  *
1239  * Return 0 and set a credential flag which triggers the inode to flush
1240  * and performs  NFS_FILE_SYNC writes if the key will expired within
1241  * RPC_KEY_EXPIRE_TIMEO.
1242  */
1243 int
1244 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1245 {
1246         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1247
1248         if (nfs_ctx_key_to_expire(ctx, inode) &&
1249             !ctx->ll_cred)
1250                 /* Already expired! */
1251                 return -EACCES;
1252         return 0;
1253 }
1254
1255 /*
1256  * Test if the open context credential key is marked to expire soon.
1257  */
1258 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1259 {
1260         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1261         struct rpc_cred *cred = ctx->ll_cred;
1262         struct auth_cred acred = {
1263                 .cred = ctx->cred,
1264         };
1265
1266         if (cred && !cred->cr_ops->crmatch(&acred, cred, 0)) {
1267                 put_rpccred(cred);
1268                 ctx->ll_cred = NULL;
1269                 cred = NULL;
1270         }
1271         if (!cred)
1272                 cred = auth->au_ops->lookup_cred(auth, &acred, 0);
1273         if (!cred || IS_ERR(cred))
1274                 return true;
1275         ctx->ll_cred = cred;
1276         return !!(cred->cr_ops->crkey_timeout &&
1277                   cred->cr_ops->crkey_timeout(cred));
1278 }
1279
1280 /*
1281  * If the page cache is marked as unsafe or invalid, then we can't rely on
1282  * the PageUptodate() flag. In this case, we will need to turn off
1283  * write optimisations that depend on the page contents being correct.
1284  */
1285 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode,
1286                                    unsigned int pagelen)
1287 {
1288         struct nfs_inode *nfsi = NFS_I(inode);
1289
1290         if (nfs_have_delegated_attributes(inode))
1291                 goto out;
1292         if (nfsi->cache_validity &
1293             (NFS_INO_INVALID_CHANGE | NFS_INO_INVALID_SIZE))
1294                 return false;
1295         smp_rmb();
1296         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags) && pagelen != 0)
1297                 return false;
1298 out:
1299         if (nfsi->cache_validity & NFS_INO_INVALID_DATA && pagelen != 0)
1300                 return false;
1301         return PageUptodate(page) != 0;
1302 }
1303
1304 static bool
1305 is_whole_file_wrlock(struct file_lock *fl)
1306 {
1307         return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1308                         fl->fl_type == F_WRLCK;
1309 }
1310
1311 /* If we know the page is up to date, and we're not using byte range locks (or
1312  * if we have the whole file locked for writing), it may be more efficient to
1313  * extend the write to cover the entire page in order to avoid fragmentation
1314  * inefficiencies.
1315  *
1316  * If the file is opened for synchronous writes then we can just skip the rest
1317  * of the checks.
1318  */
1319 static int nfs_can_extend_write(struct file *file, struct page *page,
1320                                 struct inode *inode, unsigned int pagelen)
1321 {
1322         int ret;
1323         struct file_lock_context *flctx = inode->i_flctx;
1324         struct file_lock *fl;
1325
1326         if (file->f_flags & O_DSYNC)
1327                 return 0;
1328         if (!nfs_write_pageuptodate(page, inode, pagelen))
1329                 return 0;
1330         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1331                 return 1;
1332         if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1333                        list_empty_careful(&flctx->flc_posix)))
1334                 return 1;
1335
1336         /* Check to see if there are whole file write locks */
1337         ret = 0;
1338         spin_lock(&flctx->flc_lock);
1339         if (!list_empty(&flctx->flc_posix)) {
1340                 fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1341                                         fl_list);
1342                 if (is_whole_file_wrlock(fl))
1343                         ret = 1;
1344         } else if (!list_empty(&flctx->flc_flock)) {
1345                 fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1346                                         fl_list);
1347                 if (fl->fl_type == F_WRLCK)
1348                         ret = 1;
1349         }
1350         spin_unlock(&flctx->flc_lock);
1351         return ret;
1352 }
1353
1354 /*
1355  * Update and possibly write a cached page of an NFS file.
1356  *
1357  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1358  * things with a page scheduled for an RPC call (e.g. invalidate it).
1359  */
1360 int nfs_updatepage(struct file *file, struct page *page,
1361                 unsigned int offset, unsigned int count)
1362 {
1363         struct nfs_open_context *ctx = nfs_file_open_context(file);
1364         struct address_space *mapping = page_file_mapping(page);
1365         struct inode    *inode = mapping->host;
1366         unsigned int    pagelen = nfs_page_length(page);
1367         int             status = 0;
1368
1369         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1370
1371         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1372                 file, count, (long long)(page_file_offset(page) + offset));
1373
1374         if (!count)
1375                 goto out;
1376
1377         if (nfs_can_extend_write(file, page, inode, pagelen)) {
1378                 count = max(count + offset, pagelen);
1379                 offset = 0;
1380         }
1381
1382         status = nfs_writepage_setup(ctx, page, offset, count);
1383         if (status < 0)
1384                 nfs_set_pageerror(mapping);
1385         else
1386                 __set_page_dirty_nobuffers(page);
1387 out:
1388         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1389                         status, (long long)i_size_read(inode));
1390         return status;
1391 }
1392
1393 static int flush_task_priority(int how)
1394 {
1395         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1396                 case FLUSH_HIGHPRI:
1397                         return RPC_PRIORITY_HIGH;
1398                 case FLUSH_LOWPRI:
1399                         return RPC_PRIORITY_LOW;
1400         }
1401         return RPC_PRIORITY_NORMAL;
1402 }
1403
1404 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1405                                struct rpc_message *msg,
1406                                const struct nfs_rpc_ops *rpc_ops,
1407                                struct rpc_task_setup *task_setup_data, int how)
1408 {
1409         int priority = flush_task_priority(how);
1410
1411         task_setup_data->priority = priority;
1412         rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1413         trace_nfs_initiate_write(hdr);
1414 }
1415
1416 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1417  * call this on each, which will prepare them to be retried on next
1418  * writeback using standard nfs.
1419  */
1420 static void nfs_redirty_request(struct nfs_page *req)
1421 {
1422         /* Bump the transmission count */
1423         req->wb_nio++;
1424         nfs_mark_request_dirty(req);
1425         set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1426         nfs_end_page_writeback(req);
1427         nfs_release_request(req);
1428 }
1429
1430 static void nfs_async_write_error(struct list_head *head, int error)
1431 {
1432         struct nfs_page *req;
1433
1434         while (!list_empty(head)) {
1435                 req = nfs_list_entry(head->next);
1436                 nfs_list_remove_request(req);
1437                 if (nfs_error_is_fatal(error))
1438                         nfs_write_error(req, error);
1439                 else
1440                         nfs_redirty_request(req);
1441         }
1442 }
1443
1444 static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1445 {
1446         nfs_async_write_error(&hdr->pages, 0);
1447         filemap_fdatawrite_range(hdr->inode->i_mapping, hdr->args.offset,
1448                         hdr->args.offset + hdr->args.count - 1);
1449 }
1450
1451 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1452         .init_hdr = nfs_async_write_init,
1453         .error_cleanup = nfs_async_write_error,
1454         .completion = nfs_write_completion,
1455         .reschedule_io = nfs_async_write_reschedule_io,
1456 };
1457
1458 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1459                                struct inode *inode, int ioflags, bool force_mds,
1460                                const struct nfs_pgio_completion_ops *compl_ops)
1461 {
1462         struct nfs_server *server = NFS_SERVER(inode);
1463         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1464
1465 #ifdef CONFIG_NFS_V4_1
1466         if (server->pnfs_curr_ld && !force_mds)
1467                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1468 #endif
1469         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1470                         server->wsize, ioflags);
1471 }
1472 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1473
1474 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1475 {
1476         struct nfs_pgio_mirror *mirror;
1477
1478         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1479                 pgio->pg_ops->pg_cleanup(pgio);
1480
1481         pgio->pg_ops = &nfs_pgio_rw_ops;
1482
1483         nfs_pageio_stop_mirroring(pgio);
1484
1485         mirror = &pgio->pg_mirrors[0];
1486         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1487 }
1488 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1489
1490
1491 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1492 {
1493         struct nfs_commit_data *data = calldata;
1494
1495         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1496 }
1497
1498 /*
1499  * Special version of should_remove_suid() that ignores capabilities.
1500  */
1501 static int nfs_should_remove_suid(const struct inode *inode)
1502 {
1503         umode_t mode = inode->i_mode;
1504         int kill = 0;
1505
1506         /* suid always must be killed */
1507         if (unlikely(mode & S_ISUID))
1508                 kill = ATTR_KILL_SUID;
1509
1510         /*
1511          * sgid without any exec bits is just a mandatory locking mark; leave
1512          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1513          */
1514         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1515                 kill |= ATTR_KILL_SGID;
1516
1517         if (unlikely(kill && S_ISREG(mode)))
1518                 return kill;
1519
1520         return 0;
1521 }
1522
1523 static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1524                 struct nfs_fattr *fattr)
1525 {
1526         struct nfs_pgio_args *argp = &hdr->args;
1527         struct nfs_pgio_res *resp = &hdr->res;
1528         u64 size = argp->offset + resp->count;
1529
1530         if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1531                 fattr->size = size;
1532         if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1533                 fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1534                 return;
1535         }
1536         if (size != fattr->size)
1537                 return;
1538         /* Set attribute barrier */
1539         nfs_fattr_set_barrier(fattr);
1540         /* ...and update size */
1541         fattr->valid |= NFS_ATTR_FATTR_SIZE;
1542 }
1543
1544 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1545 {
1546         struct nfs_fattr *fattr = &hdr->fattr;
1547         struct inode *inode = hdr->inode;
1548
1549         spin_lock(&inode->i_lock);
1550         nfs_writeback_check_extend(hdr, fattr);
1551         nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1552         spin_unlock(&inode->i_lock);
1553 }
1554 EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1555
1556 /*
1557  * This function is called when the WRITE call is complete.
1558  */
1559 static int nfs_writeback_done(struct rpc_task *task,
1560                               struct nfs_pgio_header *hdr,
1561                               struct inode *inode)
1562 {
1563         int status;
1564
1565         /*
1566          * ->write_done will attempt to use post-op attributes to detect
1567          * conflicting writes by other clients.  A strict interpretation
1568          * of close-to-open would allow us to continue caching even if
1569          * another writer had changed the file, but some applications
1570          * depend on tighter cache coherency when writing.
1571          */
1572         status = NFS_PROTO(inode)->write_done(task, hdr);
1573         if (status != 0)
1574                 return status;
1575
1576         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1577         trace_nfs_writeback_done(task, hdr);
1578
1579         if (hdr->res.verf->committed < hdr->args.stable &&
1580             task->tk_status >= 0) {
1581                 /* We tried a write call, but the server did not
1582                  * commit data to stable storage even though we
1583                  * requested it.
1584                  * Note: There is a known bug in Tru64 < 5.0 in which
1585                  *       the server reports NFS_DATA_SYNC, but performs
1586                  *       NFS_FILE_SYNC. We therefore implement this checking
1587                  *       as a dprintk() in order to avoid filling syslog.
1588                  */
1589                 static unsigned long    complain;
1590
1591                 /* Note this will print the MDS for a DS write */
1592                 if (time_before(complain, jiffies)) {
1593                         dprintk("NFS:       faulty NFS server %s:"
1594                                 " (committed = %d) != (stable = %d)\n",
1595                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1596                                 hdr->res.verf->committed, hdr->args.stable);
1597                         complain = jiffies + 300 * HZ;
1598                 }
1599         }
1600
1601         /* Deal with the suid/sgid bit corner case */
1602         if (nfs_should_remove_suid(inode)) {
1603                 spin_lock(&inode->i_lock);
1604                 nfs_set_cache_invalid(inode, NFS_INO_INVALID_MODE);
1605                 spin_unlock(&inode->i_lock);
1606         }
1607         return 0;
1608 }
1609
1610 /*
1611  * This function is called when the WRITE call is complete.
1612  */
1613 static void nfs_writeback_result(struct rpc_task *task,
1614                                  struct nfs_pgio_header *hdr)
1615 {
1616         struct nfs_pgio_args    *argp = &hdr->args;
1617         struct nfs_pgio_res     *resp = &hdr->res;
1618
1619         if (resp->count < argp->count) {
1620                 static unsigned long    complain;
1621
1622                 /* This a short write! */
1623                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1624
1625                 /* Has the server at least made some progress? */
1626                 if (resp->count == 0) {
1627                         if (time_before(complain, jiffies)) {
1628                                 printk(KERN_WARNING
1629                                        "NFS: Server wrote zero bytes, expected %u.\n",
1630                                        argp->count);
1631                                 complain = jiffies + 300 * HZ;
1632                         }
1633                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1634                         task->tk_status = -EIO;
1635                         return;
1636                 }
1637
1638                 /* For non rpc-based layout drivers, retry-through-MDS */
1639                 if (!task->tk_ops) {
1640                         hdr->pnfs_error = -EAGAIN;
1641                         return;
1642                 }
1643
1644                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1645                 if (resp->verf->committed != NFS_UNSTABLE) {
1646                         /* Resend from where the server left off */
1647                         hdr->mds_offset += resp->count;
1648                         argp->offset += resp->count;
1649                         argp->pgbase += resp->count;
1650                         argp->count -= resp->count;
1651                 } else {
1652                         /* Resend as a stable write in order to avoid
1653                          * headaches in the case of a server crash.
1654                          */
1655                         argp->stable = NFS_FILE_SYNC;
1656                 }
1657                 resp->count = 0;
1658                 resp->verf->committed = 0;
1659                 rpc_restart_call_prepare(task);
1660         }
1661 }
1662
1663 static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1664 {
1665         return wait_var_event_killable(&cinfo->rpcs_out,
1666                                        !atomic_read(&cinfo->rpcs_out));
1667 }
1668
1669 static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1670 {
1671         atomic_inc(&cinfo->rpcs_out);
1672 }
1673
1674 static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1675 {
1676         if (atomic_dec_and_test(&cinfo->rpcs_out))
1677                 wake_up_var(&cinfo->rpcs_out);
1678 }
1679
1680 void nfs_commitdata_release(struct nfs_commit_data *data)
1681 {
1682         put_nfs_open_context(data->context);
1683         nfs_commit_free(data);
1684 }
1685 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1686
1687 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1688                         const struct nfs_rpc_ops *nfs_ops,
1689                         const struct rpc_call_ops *call_ops,
1690                         int how, int flags)
1691 {
1692         struct rpc_task *task;
1693         int priority = flush_task_priority(how);
1694         struct rpc_message msg = {
1695                 .rpc_argp = &data->args,
1696                 .rpc_resp = &data->res,
1697                 .rpc_cred = data->cred,
1698         };
1699         struct rpc_task_setup task_setup_data = {
1700                 .task = &data->task,
1701                 .rpc_client = clnt,
1702                 .rpc_message = &msg,
1703                 .callback_ops = call_ops,
1704                 .callback_data = data,
1705                 .workqueue = nfsiod_workqueue,
1706                 .flags = RPC_TASK_ASYNC | flags,
1707                 .priority = priority,
1708         };
1709         /* Set up the initial task struct.  */
1710         nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1711         trace_nfs_initiate_commit(data);
1712
1713         dprintk("NFS: initiated commit call\n");
1714
1715         task = rpc_run_task(&task_setup_data);
1716         if (IS_ERR(task))
1717                 return PTR_ERR(task);
1718         if (how & FLUSH_SYNC)
1719                 rpc_wait_for_completion_task(task);
1720         rpc_put_task(task);
1721         return 0;
1722 }
1723 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1724
1725 static loff_t nfs_get_lwb(struct list_head *head)
1726 {
1727         loff_t lwb = 0;
1728         struct nfs_page *req;
1729
1730         list_for_each_entry(req, head, wb_list)
1731                 if (lwb < (req_offset(req) + req->wb_bytes))
1732                         lwb = req_offset(req) + req->wb_bytes;
1733
1734         return lwb;
1735 }
1736
1737 /*
1738  * Set up the argument/result storage required for the RPC call.
1739  */
1740 void nfs_init_commit(struct nfs_commit_data *data,
1741                      struct list_head *head,
1742                      struct pnfs_layout_segment *lseg,
1743                      struct nfs_commit_info *cinfo)
1744 {
1745         struct nfs_page *first;
1746         struct nfs_open_context *ctx;
1747         struct inode *inode;
1748
1749         /* Set up the RPC argument and reply structs
1750          * NB: take care not to mess about with data->commit et al. */
1751
1752         if (head)
1753                 list_splice_init(head, &data->pages);
1754
1755         first = nfs_list_entry(data->pages.next);
1756         ctx = nfs_req_openctx(first);
1757         inode = d_inode(ctx->dentry);
1758
1759         data->inode       = inode;
1760         data->cred        = ctx->cred;
1761         data->lseg        = lseg; /* reference transferred */
1762         /* only set lwb for pnfs commit */
1763         if (lseg)
1764                 data->lwb = nfs_get_lwb(&data->pages);
1765         data->mds_ops     = &nfs_commit_ops;
1766         data->completion_ops = cinfo->completion_ops;
1767         data->dreq        = cinfo->dreq;
1768
1769         data->args.fh     = NFS_FH(data->inode);
1770         /* Note: we always request a commit of the entire inode */
1771         data->args.offset = 0;
1772         data->args.count  = 0;
1773         data->context     = get_nfs_open_context(ctx);
1774         data->res.fattr   = &data->fattr;
1775         data->res.verf    = &data->verf;
1776         nfs_fattr_init(&data->fattr);
1777 }
1778 EXPORT_SYMBOL_GPL(nfs_init_commit);
1779
1780 void nfs_retry_commit(struct list_head *page_list,
1781                       struct pnfs_layout_segment *lseg,
1782                       struct nfs_commit_info *cinfo,
1783                       u32 ds_commit_idx)
1784 {
1785         struct nfs_page *req;
1786
1787         while (!list_empty(page_list)) {
1788                 req = nfs_list_entry(page_list->next);
1789                 nfs_list_remove_request(req);
1790                 nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1791                 if (!cinfo->dreq)
1792                         nfs_clear_page_commit(req->wb_page);
1793                 nfs_unlock_and_release_request(req);
1794         }
1795 }
1796 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1797
1798 static void
1799 nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1800                 struct nfs_page *req)
1801 {
1802         __set_page_dirty_nobuffers(req->wb_page);
1803 }
1804
1805 /*
1806  * Commit dirty pages
1807  */
1808 static int
1809 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1810                 struct nfs_commit_info *cinfo)
1811 {
1812         struct nfs_commit_data  *data;
1813         unsigned short task_flags = 0;
1814
1815         /* another commit raced with us */
1816         if (list_empty(head))
1817                 return 0;
1818
1819         data = nfs_commitdata_alloc(true);
1820
1821         /* Set up the argument struct */
1822         nfs_init_commit(data, head, NULL, cinfo);
1823         atomic_inc(&cinfo->mds->rpcs_out);
1824         if (NFS_SERVER(inode)->nfs_client->cl_minorversion)
1825                 task_flags = RPC_TASK_MOVEABLE;
1826         return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1827                                    data->mds_ops, how,
1828                                    RPC_TASK_CRED_NOREF | task_flags);
1829 }
1830
1831 /*
1832  * COMMIT call returned
1833  */
1834 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1835 {
1836         struct nfs_commit_data  *data = calldata;
1837
1838         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1839                                 task->tk_pid, task->tk_status);
1840
1841         /* Call the NFS version-specific code */
1842         NFS_PROTO(data->inode)->commit_done(task, data);
1843         trace_nfs_commit_done(task, data);
1844 }
1845
1846 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1847 {
1848         const struct nfs_writeverf *verf = data->res.verf;
1849         struct nfs_page *req;
1850         int status = data->task.tk_status;
1851         struct nfs_commit_info cinfo;
1852         struct nfs_server *nfss;
1853
1854         while (!list_empty(&data->pages)) {
1855                 req = nfs_list_entry(data->pages.next);
1856                 nfs_list_remove_request(req);
1857                 if (req->wb_page)
1858                         nfs_clear_page_commit(req->wb_page);
1859
1860                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1861                         nfs_req_openctx(req)->dentry->d_sb->s_id,
1862                         (unsigned long long)NFS_FILEID(d_inode(nfs_req_openctx(req)->dentry)),
1863                         req->wb_bytes,
1864                         (long long)req_offset(req));
1865                 if (status < 0) {
1866                         if (req->wb_page) {
1867                                 trace_nfs_commit_error(req, status);
1868                                 nfs_mapping_set_error(req->wb_page, status);
1869                                 nfs_inode_remove_request(req);
1870                         }
1871                         dprintk_cont(", error = %d\n", status);
1872                         goto next;
1873                 }
1874
1875                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1876                  * returned by the server against all stored verfs. */
1877                 if (nfs_write_match_verf(verf, req)) {
1878                         /* We have a match */
1879                         if (req->wb_page)
1880                                 nfs_inode_remove_request(req);
1881                         dprintk_cont(" OK\n");
1882                         goto next;
1883                 }
1884                 /* We have a mismatch. Write the page again */
1885                 dprintk_cont(" mismatch\n");
1886                 nfs_mark_request_dirty(req);
1887                 set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1888         next:
1889                 nfs_unlock_and_release_request(req);
1890                 /* Latency breaker */
1891                 cond_resched();
1892         }
1893         nfss = NFS_SERVER(data->inode);
1894         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1895                 clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
1896
1897         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1898         nfs_commit_end(cinfo.mds);
1899 }
1900
1901 static void nfs_commit_release(void *calldata)
1902 {
1903         struct nfs_commit_data *data = calldata;
1904
1905         data->completion_ops->completion(data);
1906         nfs_commitdata_release(calldata);
1907 }
1908
1909 static const struct rpc_call_ops nfs_commit_ops = {
1910         .rpc_call_prepare = nfs_commit_prepare,
1911         .rpc_call_done = nfs_commit_done,
1912         .rpc_release = nfs_commit_release,
1913 };
1914
1915 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1916         .completion = nfs_commit_release_pages,
1917         .resched_write = nfs_commit_resched_write,
1918 };
1919
1920 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1921                             int how, struct nfs_commit_info *cinfo)
1922 {
1923         int status;
1924
1925         status = pnfs_commit_list(inode, head, how, cinfo);
1926         if (status == PNFS_NOT_ATTEMPTED)
1927                 status = nfs_commit_list(inode, head, how, cinfo);
1928         return status;
1929 }
1930
1931 static int __nfs_commit_inode(struct inode *inode, int how,
1932                 struct writeback_control *wbc)
1933 {
1934         LIST_HEAD(head);
1935         struct nfs_commit_info cinfo;
1936         int may_wait = how & FLUSH_SYNC;
1937         int ret, nscan;
1938
1939         nfs_init_cinfo_from_inode(&cinfo, inode);
1940         nfs_commit_begin(cinfo.mds);
1941         for (;;) {
1942                 ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1943                 if (ret <= 0)
1944                         break;
1945                 ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1946                 if (ret < 0)
1947                         break;
1948                 ret = 0;
1949                 if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1950                         if (nscan < wbc->nr_to_write)
1951                                 wbc->nr_to_write -= nscan;
1952                         else
1953                                 wbc->nr_to_write = 0;
1954                 }
1955                 if (nscan < INT_MAX)
1956                         break;
1957                 cond_resched();
1958         }
1959         nfs_commit_end(cinfo.mds);
1960         if (ret || !may_wait)
1961                 return ret;
1962         return wait_on_commit(cinfo.mds);
1963 }
1964
1965 int nfs_commit_inode(struct inode *inode, int how)
1966 {
1967         return __nfs_commit_inode(inode, how, NULL);
1968 }
1969 EXPORT_SYMBOL_GPL(nfs_commit_inode);
1970
1971 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1972 {
1973         struct nfs_inode *nfsi = NFS_I(inode);
1974         int flags = FLUSH_SYNC;
1975         int ret = 0;
1976
1977         if (wbc->sync_mode == WB_SYNC_NONE) {
1978                 /* no commits means nothing needs to be done */
1979                 if (!atomic_long_read(&nfsi->commit_info.ncommit))
1980                         goto check_requests_outstanding;
1981
1982                 /* Don't commit yet if this is a non-blocking flush and there
1983                  * are a lot of outstanding writes for this mapping.
1984                  */
1985                 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1986                         goto out_mark_dirty;
1987
1988                 /* don't wait for the COMMIT response */
1989                 flags = 0;
1990         }
1991
1992         ret = __nfs_commit_inode(inode, flags, wbc);
1993         if (!ret) {
1994                 if (flags & FLUSH_SYNC)
1995                         return 0;
1996         } else if (atomic_long_read(&nfsi->commit_info.ncommit))
1997                 goto out_mark_dirty;
1998
1999 check_requests_outstanding:
2000         if (!atomic_read(&nfsi->commit_info.rpcs_out))
2001                 return ret;
2002 out_mark_dirty:
2003         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
2004         return ret;
2005 }
2006 EXPORT_SYMBOL_GPL(nfs_write_inode);
2007
2008 /*
2009  * Wrapper for filemap_write_and_wait_range()
2010  *
2011  * Needed for pNFS in order to ensure data becomes visible to the
2012  * client.
2013  */
2014 int nfs_filemap_write_and_wait_range(struct address_space *mapping,
2015                 loff_t lstart, loff_t lend)
2016 {
2017         int ret;
2018
2019         ret = filemap_write_and_wait_range(mapping, lstart, lend);
2020         if (ret == 0)
2021                 ret = pnfs_sync_inode(mapping->host, true);
2022         return ret;
2023 }
2024 EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
2025
2026 /*
2027  * flush the inode to disk.
2028  */
2029 int nfs_wb_all(struct inode *inode)
2030 {
2031         int ret;
2032
2033         trace_nfs_writeback_inode_enter(inode);
2034
2035         ret = filemap_write_and_wait(inode->i_mapping);
2036         if (ret)
2037                 goto out;
2038         ret = nfs_commit_inode(inode, FLUSH_SYNC);
2039         if (ret < 0)
2040                 goto out;
2041         pnfs_sync_inode(inode, true);
2042         ret = 0;
2043
2044 out:
2045         trace_nfs_writeback_inode_exit(inode, ret);
2046         return ret;
2047 }
2048 EXPORT_SYMBOL_GPL(nfs_wb_all);
2049
2050 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
2051 {
2052         struct nfs_page *req;
2053         int ret = 0;
2054
2055         wait_on_page_writeback(page);
2056
2057         /* blocking call to cancel all requests and join to a single (head)
2058          * request */
2059         req = nfs_lock_and_join_requests(page);
2060
2061         if (IS_ERR(req)) {
2062                 ret = PTR_ERR(req);
2063         } else if (req) {
2064                 /* all requests from this page have been cancelled by
2065                  * nfs_lock_and_join_requests, so just remove the head
2066                  * request from the inode / page_private pointer and
2067                  * release it */
2068                 nfs_inode_remove_request(req);
2069                 nfs_unlock_and_release_request(req);
2070         }
2071
2072         return ret;
2073 }
2074
2075 /*
2076  * Write back all requests on one page - we do this before reading it.
2077  */
2078 int nfs_wb_page(struct inode *inode, struct page *page)
2079 {
2080         loff_t range_start = page_file_offset(page);
2081         loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2082         struct writeback_control wbc = {
2083                 .sync_mode = WB_SYNC_ALL,
2084                 .nr_to_write = 0,
2085                 .range_start = range_start,
2086                 .range_end = range_end,
2087         };
2088         int ret;
2089
2090         trace_nfs_writeback_page_enter(inode);
2091
2092         for (;;) {
2093                 wait_on_page_writeback(page);
2094                 if (clear_page_dirty_for_io(page)) {
2095                         ret = nfs_writepage_locked(page, &wbc);
2096                         if (ret < 0)
2097                                 goto out_error;
2098                         continue;
2099                 }
2100                 ret = 0;
2101                 if (!PagePrivate(page))
2102                         break;
2103                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
2104                 if (ret < 0)
2105                         goto out_error;
2106         }
2107 out_error:
2108         trace_nfs_writeback_page_exit(inode, ret);
2109         return ret;
2110 }
2111
2112 #ifdef CONFIG_MIGRATION
2113 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
2114                 struct page *page, enum migrate_mode mode)
2115 {
2116         /*
2117          * If PagePrivate is set, then the page is currently associated with
2118          * an in-progress read or write request. Don't try to migrate it.
2119          *
2120          * FIXME: we could do this in principle, but we'll need a way to ensure
2121          *        that we can safely release the inode reference while holding
2122          *        the page lock.
2123          */
2124         if (PagePrivate(page))
2125                 return -EBUSY;
2126
2127         if (!nfs_fscache_release_page(page, GFP_KERNEL))
2128                 return -EBUSY;
2129
2130         return migrate_page(mapping, newpage, page, mode);
2131 }
2132 #endif
2133
2134 int __init nfs_init_writepagecache(void)
2135 {
2136         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2137                                              sizeof(struct nfs_pgio_header),
2138                                              0, SLAB_HWCACHE_ALIGN,
2139                                              NULL);
2140         if (nfs_wdata_cachep == NULL)
2141                 return -ENOMEM;
2142
2143         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2144                                                      nfs_wdata_cachep);
2145         if (nfs_wdata_mempool == NULL)
2146                 goto out_destroy_write_cache;
2147
2148         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2149                                              sizeof(struct nfs_commit_data),
2150                                              0, SLAB_HWCACHE_ALIGN,
2151                                              NULL);
2152         if (nfs_cdata_cachep == NULL)
2153                 goto out_destroy_write_mempool;
2154
2155         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2156                                                       nfs_cdata_cachep);
2157         if (nfs_commit_mempool == NULL)
2158                 goto out_destroy_commit_cache;
2159
2160         /*
2161          * NFS congestion size, scale with available memory.
2162          *
2163          *  64MB:    8192k
2164          * 128MB:   11585k
2165          * 256MB:   16384k
2166          * 512MB:   23170k
2167          *   1GB:   32768k
2168          *   2GB:   46340k
2169          *   4GB:   65536k
2170          *   8GB:   92681k
2171          *  16GB:  131072k
2172          *
2173          * This allows larger machines to have larger/more transfers.
2174          * Limit the default to 256M
2175          */
2176         nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2177         if (nfs_congestion_kb > 256*1024)
2178                 nfs_congestion_kb = 256*1024;
2179
2180         return 0;
2181
2182 out_destroy_commit_cache:
2183         kmem_cache_destroy(nfs_cdata_cachep);
2184 out_destroy_write_mempool:
2185         mempool_destroy(nfs_wdata_mempool);
2186 out_destroy_write_cache:
2187         kmem_cache_destroy(nfs_wdata_cachep);
2188         return -ENOMEM;
2189 }
2190
2191 void nfs_destroy_writepagecache(void)
2192 {
2193         mempool_destroy(nfs_commit_mempool);
2194         kmem_cache_destroy(nfs_cdata_cachep);
2195         mempool_destroy(nfs_wdata_mempool);
2196         kmem_cache_destroy(nfs_wdata_cachep);
2197 }
2198
2199 static const struct nfs_rw_ops nfs_rw_write_ops = {
2200         .rw_alloc_header        = nfs_writehdr_alloc,
2201         .rw_free_header         = nfs_writehdr_free,
2202         .rw_done                = nfs_writeback_done,
2203         .rw_result              = nfs_writeback_result,
2204         .rw_initiate            = nfs_initiate_write,
2205 };