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