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   1 /*
   2  * linux/fs/nfs/write.c
   3  *
   4  * Write file data over NFS.
   5  *
   6  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/slab.h>
  11 #include <linux/mm.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/file.h>
  14 #include <linux/writeback.h>
  15 #include <linux/swap.h>
  16
  17 #include <linux/sunrpc/clnt.h>
  18 #include <linux/nfs_fs.h>
  19 #include <linux/nfs_mount.h>
  20 #include <linux/nfs_page.h>
  21 #include <linux/backing-dev.h>
  22
  23 #include <asm/uaccess.h>
  24
  25 #include "delegation.h"
  26 #include "internal.h"
  27 #include "iostat.h"
  28
  29 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  30
  31 #define MIN_POOL_WRITE          (32)
  32 #define MIN_POOL_COMMIT         (4)
  33
  34 /*
  35  * Local function declarations
  36  */
  37 static struct nfs_page * nfs_update_request(struct nfs_open_context*,
  38                                             struct page *,
  39                                             unsigned int, unsigned int);
  40 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc,
  41                                   struct inode *inode, int ioflags);
  42 static const struct rpc_call_ops nfs_write_partial_ops;
  43 static const struct rpc_call_ops nfs_write_full_ops;
  44 static const struct rpc_call_ops nfs_commit_ops;
  45
  46 static struct kmem_cache *nfs_wdata_cachep;
  47 static mempool_t *nfs_wdata_mempool;
  48 static mempool_t *nfs_commit_mempool;
  49
  50 struct nfs_write_data *nfs_commit_alloc(void)
  51 {
  52         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
  53
  54         if (p) {
  55                 memset(p, 0, sizeof(*p));
  56                 INIT_LIST_HEAD(&p->pages);
  57         }
  58         return p;
  59 }
  60
  61 void nfs_commit_free(struct nfs_write_data *p)
  62 {
  63         if (p && (p->pagevec != &p->page_array[0]))
  64                 kfree(p->pagevec);
  65         mempool_free(p, nfs_commit_mempool);
  66 }
  67
  68 struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
  69 {
  70         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
  71
  72         if (p) {
  73                 memset(p, 0, sizeof(*p));
  74                 INIT_LIST_HEAD(&p->pages);
  75                 p->npages = pagecount;
  76                 if (pagecount <= ARRAY_SIZE(p->page_array))
  77                         p->pagevec = p->page_array;
  78                 else {
  79                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
  80                         if (!p->pagevec) {
  81                                 mempool_free(p, nfs_wdata_mempool);
  82                                 p = NULL;
  83                         }
  84                 }
  85         }
  86         return p;
  87 }
  88
  89 static void nfs_writedata_free(struct nfs_write_data *p)
  90 {
  91         if (p && (p->pagevec != &p->page_array[0]))
  92                 kfree(p->pagevec);
  93         mempool_free(p, nfs_wdata_mempool);
  94 }
  95
  96 void nfs_writedata_release(void *data)
  97 {
  98         struct nfs_write_data *wdata = data;
  99
 100         put_nfs_open_context(wdata->args.context);
 101         nfs_writedata_free(wdata);
 102 }
 103
 104 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 105 {
 106         ctx->error = error;
 107         smp_wmb();
 108         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 109 }
 110
 111 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 112 {
 113         struct nfs_page *req = NULL;
 114
 115         if (PagePrivate(page)) {
 116                 req = (struct nfs_page *)page_private(page);
 117                 if (req != NULL)
 118                         kref_get(&req->wb_kref);
 119         }
 120         return req;
 121 }
 122
 123 static struct nfs_page *nfs_page_find_request(struct page *page)
 124 {
 125         struct inode *inode = page->mapping->host;
 126         struct nfs_page *req = NULL;
 127
 128         spin_lock(&inode->i_lock);
 129         req = nfs_page_find_request_locked(page);
 130         spin_unlock(&inode->i_lock);
 131         return req;
 132 }
 133
 134 /* Adjust the file length if we're writing beyond the end */
 135 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 136 {
 137         struct inode *inode = page->mapping->host;
 138         loff_t end, i_size = i_size_read(inode);
 139         pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 140
 141         if (i_size > 0 && page->index < end_index)
 142                 return;
 143         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 144         if (i_size >= end)
 145                 return;
 146         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 147         i_size_write(inode, end);
 148 }
 149
 150 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 151 static void nfs_set_pageerror(struct page *page)
 152 {
 153         SetPageError(page);
 154         nfs_zap_mapping(page->mapping->host, page->mapping);
 155 }
 156
 157 /* We can set the PG_uptodate flag if we see that a write request
 158  * covers the full page.
 159  */
 160 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 161 {
 162         if (PageUptodate(page))
 163                 return;
 164         if (base != 0)
 165                 return;
 166         if (count != nfs_page_length(page))
 167                 return;
 168         SetPageUptodate(page);
 169 }
 170
 171 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 172                 unsigned int offset, unsigned int count)
 173 {
 174         struct nfs_page *req;
 175         int ret;
 176
 177         for (;;) {
 178                 req = nfs_update_request(ctx, page, offset, count);
 179                 if (!IS_ERR(req))
 180                         break;
 181                 ret = PTR_ERR(req);
 182                 if (ret != -EBUSY)
 183                         return ret;
 184                 ret = nfs_wb_page(page->mapping->host, page);
 185                 if (ret != 0)
 186                         return ret;
 187         }
 188         /* Update file length */
 189         nfs_grow_file(page, offset, count);
 190         nfs_clear_page_tag_locked(req);
 191         return 0;
 192 }
 193
 194 static int wb_priority(struct writeback_control *wbc)
 195 {
 196         if (wbc->for_reclaim)
 197                 return FLUSH_HIGHPRI | FLUSH_STABLE;
 198         if (wbc->for_kupdate)
 199                 return FLUSH_LOWPRI;
 200         return 0;
 201 }
 202
 203 /*
 204  * NFS congestion control
 205  */
 206
 207 int nfs_congestion_kb;
 208
 209 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 210 #define NFS_CONGESTION_OFF_THRESH       \
 211         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 212
 213 static int nfs_set_page_writeback(struct page *page)
 214 {
 215         int ret = test_set_page_writeback(page);
 216
 217         if (!ret) {
 218                 struct inode *inode = page->mapping->host;
 219                 struct nfs_server *nfss = NFS_SERVER(inode);
 220
 221                 if (atomic_long_inc_return(&nfss->writeback) >
 222                                 NFS_CONGESTION_ON_THRESH)
 223                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
 224         }
 225         return ret;
 226 }
 227
 228 static void nfs_end_page_writeback(struct page *page)
 229 {
 230         struct inode *inode = page->mapping->host;
 231         struct nfs_server *nfss = NFS_SERVER(inode);
 232
 233         end_page_writeback(page);
 234         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 235                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
 236 }
 237
 238 /*
 239  * Find an associated nfs write request, and prepare to flush it out
 240  * May return an error if the user signalled nfs_wait_on_request().
 241  */
 242 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 243                                 struct page *page)
 244 {
 245         struct inode *inode = page->mapping->host;
 246         struct nfs_page *req;
 247         int ret;
 248
 249         spin_lock(&inode->i_lock);
 250         for(;;) {
 251                 req = nfs_page_find_request_locked(page);
 252                 if (req == NULL) {
 253                         spin_unlock(&inode->i_lock);
 254                         return 0;
 255                 }
 256                 if (nfs_set_page_tag_locked(req))
 257                         break;
 258                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 259                  *       then the call to nfs_set_page_tag_locked() will always
 260                  *       succeed provided that someone hasn't already marked the
 261                  *       request as dirty (in which case we don't care).
 262                  */
 263                 spin_unlock(&inode->i_lock);
 264                 ret = nfs_wait_on_request(req);
 265                 nfs_release_request(req);
 266                 if (ret != 0)
 267                         return ret;
 268                 spin_lock(&inode->i_lock);
 269         }
 270         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 271                 /* This request is marked for commit */
 272                 spin_unlock(&inode->i_lock);
 273                 nfs_clear_page_tag_locked(req);
 274                 nfs_pageio_complete(pgio);
 275                 return 0;
 276         }
 277         if (nfs_set_page_writeback(page) != 0) {
 278                 spin_unlock(&inode->i_lock);
 279                 BUG();
 280         }
 281         spin_unlock(&inode->i_lock);
 282         nfs_pageio_add_request(pgio, req);
 283         return 0;
 284 }
 285
 286 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 287 {
 288         struct inode *inode = page->mapping->host;
 289
 290         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 291         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 292
 293         nfs_pageio_cond_complete(pgio, page->index);
 294         return nfs_page_async_flush(pgio, page);
 295 }
 296
 297 /*
 298  * Write an mmapped page to the server.
 299  */
 300 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 301 {
 302         struct nfs_pageio_descriptor pgio;
 303         int err;
 304
 305         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
 306         err = nfs_do_writepage(page, wbc, &pgio);
 307         nfs_pageio_complete(&pgio);
 308         if (err < 0)
 309                 return err;
 310         if (pgio.pg_error < 0)
 311                 return pgio.pg_error;
 312         return 0;
 313 }
 314
 315 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 316 {
 317         int ret;
 318
 319         ret = nfs_writepage_locked(page, wbc);
 320         unlock_page(page);
 321         return ret;
 322 }
 323
 324 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 325 {
 326         int ret;
 327
 328         ret = nfs_do_writepage(page, wbc, data);
 329         unlock_page(page);
 330         return ret;
 331 }
 332
 333 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 334 {
 335         struct inode *inode = mapping->host;
 336         struct nfs_pageio_descriptor pgio;
 337         int err;
 338
 339         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 340
 341         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
 342         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 343         nfs_pageio_complete(&pgio);
 344         if (err < 0)
 345                 return err;
 346         if (pgio.pg_error < 0)
 347                 return pgio.pg_error;
 348         return 0;
 349 }
 350
 351 /*
 352  * Insert a write request into an inode
 353  */
 354 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 355 {
 356         struct nfs_inode *nfsi = NFS_I(inode);
 357         int error;
 358
 359         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 360         BUG_ON(error == -EEXIST);
 361         if (error)
 362                 return error;
 363         if (!nfsi->npages) {
 364                 igrab(inode);
 365                 if (nfs_have_delegation(inode, FMODE_WRITE))
 366                         nfsi->change_attr++;
 367         }
 368         SetPagePrivate(req->wb_page);
 369         set_page_private(req->wb_page, (unsigned long)req);
 370         nfsi->npages++;
 371         kref_get(&req->wb_kref);
 372         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
 373         return 0;
 374 }
 375
 376 /*
 377  * Remove a write request from an inode
 378  */
 379 static void nfs_inode_remove_request(struct nfs_page *req)
 380 {
 381         struct inode *inode = req->wb_context->path.dentry->d_inode;
 382         struct nfs_inode *nfsi = NFS_I(inode);
 383
 384         BUG_ON (!NFS_WBACK_BUSY(req));
 385
 386         spin_lock(&inode->i_lock);
 387         set_page_private(req->wb_page, 0);
 388         ClearPagePrivate(req->wb_page);
 389         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 390         nfsi->npages--;
 391         if (!nfsi->npages) {
 392                 spin_unlock(&inode->i_lock);
 393                 iput(inode);
 394         } else
 395                 spin_unlock(&inode->i_lock);
 396         nfs_clear_request(req);
 397         nfs_release_request(req);
 398 }
 399
 400 static void
 401 nfs_redirty_request(struct nfs_page *req)
 402 {
 403         __set_page_dirty_nobuffers(req->wb_page);
 404 }
 405
 406 /*
 407  * Check if a request is dirty
 408  */
 409 static inline int
 410 nfs_dirty_request(struct nfs_page *req)
 411 {
 412         struct page *page = req->wb_page;
 413
 414         if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
 415                 return 0;
 416         return !PageWriteback(req->wb_page);
 417 }
 418
 419 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 420 /*
 421  * Add a request to the inode's commit list.
 422  */
 423 static void
 424 nfs_mark_request_commit(struct nfs_page *req)
 425 {
 426         struct inode *inode = req->wb_context->path.dentry->d_inode;
 427         struct nfs_inode *nfsi = NFS_I(inode);
 428
 429         spin_lock(&inode->i_lock);
 430         nfsi->ncommit++;
 431         set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
 432         radix_tree_tag_set(&nfsi->nfs_page_tree,
 433                         req->wb_index,
 434                         NFS_PAGE_TAG_COMMIT);
 435         spin_unlock(&inode->i_lock);
 436         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 437         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 438         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 439 }
 440
 441 static inline
 442 int nfs_write_need_commit(struct nfs_write_data *data)
 443 {
 444         return data->verf.committed != NFS_FILE_SYNC;
 445 }
 446
 447 static inline
 448 int nfs_reschedule_unstable_write(struct nfs_page *req)
 449 {
 450         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 451                 nfs_mark_request_commit(req);
 452                 return 1;
 453         }
 454         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 455                 nfs_redirty_request(req);
 456                 return 1;
 457         }
 458         return 0;
 459 }
 460 #else
 461 static inline void
 462 nfs_mark_request_commit(struct nfs_page *req)
 463 {
 464 }
 465
 466 static inline
 467 int nfs_write_need_commit(struct nfs_write_data *data)
 468 {
 469         return 0;
 470 }
 471
 472 static inline
 473 int nfs_reschedule_unstable_write(struct nfs_page *req)
 474 {
 475         return 0;
 476 }
 477 #endif
 478
 479 /*
 480  * Wait for a request to complete.
 481  *
 482  * Interruptible by fatal signals only.
 483  */
 484 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
 485 {
 486         struct nfs_inode *nfsi = NFS_I(inode);
 487         struct nfs_page *req;
 488         pgoff_t idx_end, next;
 489         unsigned int            res = 0;
 490         int                     error;
 491
 492         if (npages == 0)
 493                 idx_end = ~0;
 494         else
 495                 idx_end = idx_start + npages - 1;
 496
 497         next = idx_start;
 498         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
 499                 if (req->wb_index > idx_end)
 500                         break;
 501
 502                 next = req->wb_index + 1;
 503                 BUG_ON(!NFS_WBACK_BUSY(req));
 504
 505                 kref_get(&req->wb_kref);
 506                 spin_unlock(&inode->i_lock);
 507                 error = nfs_wait_on_request(req);
 508                 nfs_release_request(req);
 509                 spin_lock(&inode->i_lock);
 510                 if (error < 0)
 511                         return error;
 512                 res++;
 513         }
 514         return res;
 515 }
 516
 517 static void nfs_cancel_commit_list(struct list_head *head)
 518 {
 519         struct nfs_page *req;
 520
 521         while(!list_empty(head)) {
 522                 req = nfs_list_entry(head->next);
 523                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 524                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
 525                                 BDI_RECLAIMABLE);
 526                 nfs_list_remove_request(req);
 527                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
 528                 nfs_inode_remove_request(req);
 529                 nfs_unlock_request(req);
 530         }
 531 }
 532
 533 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 534 /*
 535  * nfs_scan_commit - Scan an inode for commit requests
 536  * @inode: NFS inode to scan
 537  * @dst: destination list
 538  * @idx_start: lower bound of page->index to scan.
 539  * @npages: idx_start + npages sets the upper bound to scan.
 540  *
 541  * Moves requests from the inode's 'commit' request list.
 542  * The requests are *not* checked to ensure that they form a contiguous set.
 543  */
 544 static int
 545 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 546 {
 547         struct nfs_inode *nfsi = NFS_I(inode);
 548         int res = 0;
 549
 550         if (nfsi->ncommit != 0) {
 551                 res = nfs_scan_list(nfsi, dst, idx_start, npages,
 552                                 NFS_PAGE_TAG_COMMIT);
 553                 nfsi->ncommit -= res;
 554         }
 555         return res;
 556 }
 557 #else
 558 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 559 {
 560         return 0;
 561 }
 562 #endif
 563
 564 /*
 565  * Try to update any existing write request, or create one if there is none.
 566  * In order to match, the request's credentials must match those of
 567  * the calling process.
 568  *
 569  * Note: Should always be called with the Page Lock held!
 570  */
 571 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 572                 struct page *page, unsigned int offset, unsigned int bytes)
 573 {
 574         struct address_space *mapping = page->mapping;
 575         struct inode *inode = mapping->host;
 576         struct nfs_page         *req, *new = NULL;
 577         pgoff_t         rqend, end;
 578
 579         end = offset + bytes;
 580
 581         for (;;) {
 582                 /* Loop over all inode entries and see if we find
 583                  * A request for the page we wish to update
 584                  */
 585                 spin_lock(&inode->i_lock);
 586                 req = nfs_page_find_request_locked(page);
 587                 if (req) {
 588                         if (!nfs_set_page_tag_locked(req)) {
 589                                 int error;
 590
 591                                 spin_unlock(&inode->i_lock);
 592                                 error = nfs_wait_on_request(req);
 593                                 nfs_release_request(req);
 594                                 if (error < 0) {
 595                                         if (new)
 596                                                 nfs_release_request(new);
 597                                         return ERR_PTR(error);
 598                                 }
 599                                 continue;
 600                         }
 601                         spin_unlock(&inode->i_lock);
 602                         if (new)
 603                                 nfs_release_request(new);
 604                         break;
 605                 }
 606
 607                 if (new) {
 608                         int error;
 609                         nfs_lock_request_dontget(new);
 610                         error = nfs_inode_add_request(inode, new);
 611                         if (error) {
 612                                 spin_unlock(&inode->i_lock);
 613                                 nfs_unlock_request(new);
 614                                 return ERR_PTR(error);
 615                         }
 616                         spin_unlock(&inode->i_lock);
 617                         req = new;
 618                         goto zero_page;
 619                 }
 620                 spin_unlock(&inode->i_lock);
 621
 622                 new = nfs_create_request(ctx, inode, page, offset, bytes);
 623                 if (IS_ERR(new))
 624                         return new;
 625         }
 626
 627         /* We have a request for our page.
 628          * If the creds don't match, or the
 629          * page addresses don't match,
 630          * tell the caller to wait on the conflicting
 631          * request.
 632          */
 633         rqend = req->wb_offset + req->wb_bytes;
 634         if (req->wb_context != ctx
 635             || req->wb_page != page
 636             || !nfs_dirty_request(req)
 637             || offset > rqend || end < req->wb_offset) {
 638                 nfs_clear_page_tag_locked(req);
 639                 return ERR_PTR(-EBUSY);
 640         }
 641
 642         /* Okay, the request matches. Update the region */
 643         if (offset < req->wb_offset) {
 644                 req->wb_offset = offset;
 645                 req->wb_pgbase = offset;
 646                 req->wb_bytes = max(end, rqend) - req->wb_offset;
 647                 goto zero_page;
 648         }
 649
 650         if (end > rqend)
 651                 req->wb_bytes = end - req->wb_offset;
 652
 653         return req;
 654 zero_page:
 655         /* If this page might potentially be marked as up to date,
 656          * then we need to zero any uninitalised data. */
 657         if (req->wb_pgbase == 0 && req->wb_bytes != PAGE_CACHE_SIZE
 658                         && !PageUptodate(req->wb_page))
 659                 zero_user_segment(req->wb_page, req->wb_bytes, PAGE_CACHE_SIZE);
 660         return req;
 661 }
 662
 663 int nfs_flush_incompatible(struct file *file, struct page *page)
 664 {
 665         struct nfs_open_context *ctx = nfs_file_open_context(file);
 666         struct nfs_page *req;
 667         int do_flush, status;
 668         /*
 669          * Look for a request corresponding to this page. If there
 670          * is one, and it belongs to another file, we flush it out
 671          * before we try to copy anything into the page. Do this
 672          * due to the lack of an ACCESS-type call in NFSv2.
 673          * Also do the same if we find a request from an existing
 674          * dropped page.
 675          */
 676         do {
 677                 req = nfs_page_find_request(page);
 678                 if (req == NULL)
 679                         return 0;
 680                 do_flush = req->wb_page != page || req->wb_context != ctx
 681                         || !nfs_dirty_request(req);
 682                 nfs_release_request(req);
 683                 if (!do_flush)
 684                         return 0;
 685                 status = nfs_wb_page(page->mapping->host, page);
 686         } while (status == 0);
 687         return status;
 688 }
 689
 690 /*
 691  * If the page cache is marked as unsafe or invalid, then we can't rely on
 692  * the PageUptodate() flag. In this case, we will need to turn off
 693  * write optimisations that depend on the page contents being correct.
 694  */
 695 static int nfs_write_pageuptodate(struct page *page, struct inode *inode)
 696 {
 697         return PageUptodate(page) &&
 698                 !(NFS_I(inode)->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA));
 699 }
 700
 701 /*
 702  * Update and possibly write a cached page of an NFS file.
 703  *
 704  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 705  * things with a page scheduled for an RPC call (e.g. invalidate it).
 706  */
 707 int nfs_updatepage(struct file *file, struct page *page,
 708                 unsigned int offset, unsigned int count)
 709 {
 710         struct nfs_open_context *ctx = nfs_file_open_context(file);
 711         struct inode    *inode = page->mapping->host;
 712         int             status = 0;
 713
 714         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 715
 716         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
 717                 file->f_path.dentry->d_parent->d_name.name,
 718                 file->f_path.dentry->d_name.name, count,
 719                 (long long)(page_offset(page) +offset));
 720
 721         /* If we're not using byte range locks, and we know the page
 722          * is up to date, it may be more efficient to extend the write
 723          * to cover the entire page in order to avoid fragmentation
 724          * inefficiencies.
 725          */
 726         if (nfs_write_pageuptodate(page, inode) &&
 727                         inode->i_flock == NULL &&
 728                         !(file->f_flags & O_SYNC)) {
 729                 count = max(count + offset, nfs_page_length(page));
 730                 offset = 0;
 731         }
 732
 733         status = nfs_writepage_setup(ctx, page, offset, count);
 734         __set_page_dirty_nobuffers(page);
 735
 736         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
 737                         status, (long long)i_size_read(inode));
 738         if (status < 0)
 739                 nfs_set_pageerror(page);
 740         return status;
 741 }
 742
 743 static void nfs_writepage_release(struct nfs_page *req)
 744 {
 745
 746         if (PageError(req->wb_page)) {
 747                 nfs_end_page_writeback(req->wb_page);
 748                 nfs_inode_remove_request(req);
 749         } else if (!nfs_reschedule_unstable_write(req)) {
 750                 /* Set the PG_uptodate flag */
 751                 nfs_mark_uptodate(req->wb_page, req->wb_pgbase, req->wb_bytes);
 752                 nfs_end_page_writeback(req->wb_page);
 753                 nfs_inode_remove_request(req);
 754         } else
 755                 nfs_end_page_writeback(req->wb_page);
 756         nfs_clear_page_tag_locked(req);
 757 }
 758
 759 static int flush_task_priority(int how)
 760 {
 761         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 762                 case FLUSH_HIGHPRI:
 763                         return RPC_PRIORITY_HIGH;
 764                 case FLUSH_LOWPRI:
 765                         return RPC_PRIORITY_LOW;
 766         }
 767         return RPC_PRIORITY_NORMAL;
 768 }
 769
 770 /*
 771  * Set up the argument/result storage required for the RPC call.
 772  */
 773 static void nfs_write_rpcsetup(struct nfs_page *req,
 774                 struct nfs_write_data *data,
 775                 const struct rpc_call_ops *call_ops,
 776                 unsigned int count, unsigned int offset,
 777                 int how)
 778 {
 779         struct inode *inode = req->wb_context->path.dentry->d_inode;
 780         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 781         int priority = flush_task_priority(how);
 782         struct rpc_task *task;
 783         struct rpc_message msg = {
 784                 .rpc_argp = &data->args,
 785                 .rpc_resp = &data->res,
 786                 .rpc_cred = req->wb_context->cred,
 787         };
 788         struct rpc_task_setup task_setup_data = {
 789                 .rpc_client = NFS_CLIENT(inode),
 790                 .task = &data->task,
 791                 .rpc_message = &msg,
 792                 .callback_ops = call_ops,
 793                 .callback_data = data,
 794                 .workqueue = nfsiod_workqueue,
 795                 .flags = flags,
 796                 .priority = priority,
 797         };
 798
 799         /* Set up the RPC argument and reply structs
 800          * NB: take care not to mess about with data->commit et al. */
 801
 802         data->req = req;
 803         data->inode = inode = req->wb_context->path.dentry->d_inode;
 804         data->cred = msg.rpc_cred;
 805
 806         data->args.fh     = NFS_FH(inode);
 807         data->args.offset = req_offset(req) + offset;
 808         data->args.pgbase = req->wb_pgbase + offset;
 809         data->args.pages  = data->pagevec;
 810         data->args.count  = count;
 811         data->args.context = get_nfs_open_context(req->wb_context);
 812         data->args.stable  = NFS_UNSTABLE;
 813         if (how & FLUSH_STABLE) {
 814                 data->args.stable = NFS_DATA_SYNC;
 815                 if (!NFS_I(inode)->ncommit)
 816                         data->args.stable = NFS_FILE_SYNC;
 817         }
 818
 819         data->res.fattr   = &data->fattr;
 820         data->res.count   = count;
 821         data->res.verf    = &data->verf;
 822         nfs_fattr_init(&data->fattr);
 823
 824         /* Set up the initial task struct.  */
 825         NFS_PROTO(inode)->write_setup(data, &msg);
 826
 827         dprintk("NFS: %5u initiated write call "
 828                 "(req %s/%Ld, %u bytes @ offset %Lu)\n",
 829                 data->task.tk_pid,
 830                 inode->i_sb->s_id,
 831                 (long long)NFS_FILEID(inode),
 832                 count,
 833                 (unsigned long long)data->args.offset);
 834
 835         task = rpc_run_task(&task_setup_data);
 836         if (!IS_ERR(task))
 837                 rpc_put_task(task);
 838 }
 839
 840 /*
 841  * Generate multiple small requests to write out a single
 842  * contiguous dirty area on one page.
 843  */
 844 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 845 {
 846         struct nfs_page *req = nfs_list_entry(head->next);
 847         struct page *page = req->wb_page;
 848         struct nfs_write_data *data;
 849         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 850         unsigned int offset;
 851         int requests = 0;
 852         LIST_HEAD(list);
 853
 854         nfs_list_remove_request(req);
 855
 856         nbytes = count;
 857         do {
 858                 size_t len = min(nbytes, wsize);
 859
 860                 data = nfs_writedata_alloc(1);
 861                 if (!data)
 862                         goto out_bad;
 863                 list_add(&data->pages, &list);
 864                 requests++;
 865                 nbytes -= len;
 866         } while (nbytes != 0);
 867         atomic_set(&req->wb_complete, requests);
 868
 869         ClearPageError(page);
 870         offset = 0;
 871         nbytes = count;
 872         do {
 873                 data = list_entry(list.next, struct nfs_write_data, pages);
 874                 list_del_init(&data->pages);
 875
 876                 data->pagevec[0] = page;
 877
 878                 if (nbytes < wsize)
 879                         wsize = nbytes;
 880                 nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 881                                    wsize, offset, how);
 882                 offset += wsize;
 883                 nbytes -= wsize;
 884         } while (nbytes != 0);
 885
 886         return 0;
 887
 888 out_bad:
 889         while (!list_empty(&list)) {
 890                 data = list_entry(list.next, struct nfs_write_data, pages);
 891                 list_del(&data->pages);
 892                 nfs_writedata_release(data);
 893         }
 894         nfs_redirty_request(req);
 895         nfs_end_page_writeback(req->wb_page);
 896         nfs_clear_page_tag_locked(req);
 897         return -ENOMEM;
 898 }
 899
 900 /*
 901  * Create an RPC task for the given write request and kick it.
 902  * The page must have been locked by the caller.
 903  *
 904  * It may happen that the page we're passed is not marked dirty.
 905  * This is the case if nfs_updatepage detects a conflicting request
 906  * that has been written but not committed.
 907  */
 908 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 909 {
 910         struct nfs_page         *req;
 911         struct page             **pages;
 912         struct nfs_write_data   *data;
 913
 914         data = nfs_writedata_alloc(npages);
 915         if (!data)
 916                 goto out_bad;
 917
 918         pages = data->pagevec;
 919         while (!list_empty(head)) {
 920                 req = nfs_list_entry(head->next);
 921                 nfs_list_remove_request(req);
 922                 nfs_list_add_request(req, &data->pages);
 923                 ClearPageError(req->wb_page);
 924                 *pages++ = req->wb_page;
 925         }
 926         req = nfs_list_entry(data->pages.next);
 927
 928         /* Set up the argument struct */
 929         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 930
 931         return 0;
 932  out_bad:
 933         while (!list_empty(head)) {
 934                 req = nfs_list_entry(head->next);
 935                 nfs_list_remove_request(req);
 936                 nfs_redirty_request(req);
 937                 nfs_end_page_writeback(req->wb_page);
 938                 nfs_clear_page_tag_locked(req);
 939         }
 940         return -ENOMEM;
 941 }
 942
 943 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
 944                                   struct inode *inode, int ioflags)
 945 {
 946         size_t wsize = NFS_SERVER(inode)->wsize;
 947
 948         if (wsize < PAGE_CACHE_SIZE)
 949                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
 950         else
 951                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
 952 }
 953
 954 /*
 955  * Handle a write reply that flushed part of a page.
 956  */
 957 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
 958 {
 959         struct nfs_write_data   *data = calldata;
 960         struct nfs_page         *req = data->req;
 961         struct page             *page = req->wb_page;
 962
 963         dprintk("NFS: write (%s/%Ld %d@%Ld)",
 964                 req->wb_context->path.dentry->d_inode->i_sb->s_id,
 965                 (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
 966                 req->wb_bytes,
 967                 (long long)req_offset(req));
 968
 969         if (nfs_writeback_done(task, data) != 0)
 970                 return;
 971
 972         if (task->tk_status < 0) {
 973                 nfs_set_pageerror(page);
 974                 nfs_context_set_write_error(req->wb_context, task->tk_status);
 975                 dprintk(", error = %d\n", task->tk_status);
 976                 goto out;
 977         }
 978
 979         if (nfs_write_need_commit(data)) {
 980                 struct inode *inode = page->mapping->host;
 981
 982                 spin_lock(&inode->i_lock);
 983                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 984                         /* Do nothing we need to resend the writes */
 985                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 986                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
 987                         dprintk(" defer commit\n");
 988                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
 989                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
 990                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
 991                         dprintk(" server reboot detected\n");
 992                 }
 993                 spin_unlock(&inode->i_lock);
 994         } else
 995                 dprintk(" OK\n");
 996
 997 out:
 998         if (atomic_dec_and_test(&req->wb_complete))
 999                 nfs_writepage_release(req);
1000 }
1001
1002 static const struct rpc_call_ops nfs_write_partial_ops = {
1003         .rpc_call_done = nfs_writeback_done_partial,
1004         .rpc_release = nfs_writedata_release,
1005 };
1006
1007 /*
1008  * Handle a write reply that flushes a whole page.
1009  *
1010  * FIXME: There is an inherent race with invalidate_inode_pages and
1011  *        writebacks since the page->count is kept > 1 for as long
1012  *        as the page has a write request pending.
1013  */
1014 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1015 {
1016         struct nfs_write_data   *data = calldata;
1017         struct nfs_page         *req;
1018         struct page             *page;
1019
1020         if (nfs_writeback_done(task, data) != 0)
1021                 return;
1022
1023         /* Update attributes as result of writeback. */
1024         while (!list_empty(&data->pages)) {
1025                 req = nfs_list_entry(data->pages.next);
1026                 nfs_list_remove_request(req);
1027                 page = req->wb_page;
1028
1029                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1030                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1031                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1032                         req->wb_bytes,
1033                         (long long)req_offset(req));
1034
1035                 if (task->tk_status < 0) {
1036                         nfs_set_pageerror(page);
1037                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1038                         dprintk(", error = %d\n", task->tk_status);
1039                         goto remove_request;
1040                 }
1041
1042                 if (nfs_write_need_commit(data)) {
1043                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1044                         nfs_mark_request_commit(req);
1045                         nfs_end_page_writeback(page);
1046                         dprintk(" marked for commit\n");
1047                         goto next;
1048                 }
1049                 /* Set the PG_uptodate flag? */
1050                 nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
1051                 dprintk(" OK\n");
1052 remove_request:
1053                 nfs_end_page_writeback(page);
1054                 nfs_inode_remove_request(req);
1055         next:
1056                 nfs_clear_page_tag_locked(req);
1057         }
1058 }
1059
1060 static const struct rpc_call_ops nfs_write_full_ops = {
1061         .rpc_call_done = nfs_writeback_done_full,
1062         .rpc_release = nfs_writedata_release,
1063 };
1064
1065
1066 /*
1067  * This function is called when the WRITE call is complete.
1068  */
1069 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1070 {
1071         struct nfs_writeargs    *argp = &data->args;
1072         struct nfs_writeres     *resp = &data->res;
1073         int status;
1074
1075         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1076                 task->tk_pid, task->tk_status);
1077
1078         /*
1079          * ->write_done will attempt to use post-op attributes to detect
1080          * conflicting writes by other clients.  A strict interpretation
1081          * of close-to-open would allow us to continue caching even if
1082          * another writer had changed the file, but some applications
1083          * depend on tighter cache coherency when writing.
1084          */
1085         status = NFS_PROTO(data->inode)->write_done(task, data);
1086         if (status != 0)
1087                 return status;
1088         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1089
1090 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1091         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1092                 /* We tried a write call, but the server did not
1093                  * commit data to stable storage even though we
1094                  * requested it.
1095                  * Note: There is a known bug in Tru64 < 5.0 in which
1096                  *       the server reports NFS_DATA_SYNC, but performs
1097                  *       NFS_FILE_SYNC. We therefore implement this checking
1098                  *       as a dprintk() in order to avoid filling syslog.
1099                  */
1100                 static unsigned long    complain;
1101
1102                 if (time_before(complain, jiffies)) {
1103                         dprintk("NFS: faulty NFS server %s:"
1104                                 " (committed = %d) != (stable = %d)\n",
1105                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1106                                 resp->verf->committed, argp->stable);
1107                         complain = jiffies + 300 * HZ;
1108                 }
1109         }
1110 #endif
1111         /* Is this a short write? */
1112         if (task->tk_status >= 0 && resp->count < argp->count) {
1113                 static unsigned long    complain;
1114
1115                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1116
1117                 /* Has the server at least made some progress? */
1118                 if (resp->count != 0) {
1119                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1120                         if (resp->verf->committed != NFS_UNSTABLE) {
1121                                 /* Resend from where the server left off */
1122                                 argp->offset += resp->count;
1123                                 argp->pgbase += resp->count;
1124                                 argp->count -= resp->count;
1125                         } else {
1126                                 /* Resend as a stable write in order to avoid
1127                                  * headaches in the case of a server crash.
1128                                  */
1129                                 argp->stable = NFS_FILE_SYNC;
1130                         }
1131                         rpc_restart_call(task);
1132                         return -EAGAIN;
1133                 }
1134                 if (time_before(complain, jiffies)) {
1135                         printk(KERN_WARNING
1136                                "NFS: Server wrote zero bytes, expected %u.\n",
1137                                         argp->count);
1138                         complain = jiffies + 300 * HZ;
1139                 }
1140                 /* Can't do anything about it except throw an error. */
1141                 task->tk_status = -EIO;
1142         }
1143         return 0;
1144 }
1145
1146
1147 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1148 void nfs_commit_release(void *data)
1149 {
1150         struct nfs_write_data *wdata = data;
1151
1152         put_nfs_open_context(wdata->args.context);
1153         nfs_commit_free(wdata);
1154 }
1155
1156 /*
1157  * Set up the argument/result storage required for the RPC call.
1158  */
1159 static void nfs_commit_rpcsetup(struct list_head *head,
1160                 struct nfs_write_data *data,
1161                 int how)
1162 {
1163         struct nfs_page *first = nfs_list_entry(head->next);
1164         struct inode *inode = first->wb_context->path.dentry->d_inode;
1165         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1166         int priority = flush_task_priority(how);
1167         struct rpc_task *task;
1168         struct rpc_message msg = {
1169                 .rpc_argp = &data->args,
1170                 .rpc_resp = &data->res,
1171                 .rpc_cred = first->wb_context->cred,
1172         };
1173         struct rpc_task_setup task_setup_data = {
1174                 .task = &data->task,
1175                 .rpc_client = NFS_CLIENT(inode),
1176                 .rpc_message = &msg,
1177                 .callback_ops = &nfs_commit_ops,
1178                 .callback_data = data,
1179                 .workqueue = nfsiod_workqueue,
1180                 .flags = flags,
1181                 .priority = priority,
1182         };
1183
1184         /* Set up the RPC argument and reply structs
1185          * NB: take care not to mess about with data->commit et al. */
1186
1187         list_splice_init(head, &data->pages);
1188
1189         data->inode       = inode;
1190         data->cred        = msg.rpc_cred;
1191
1192         data->args.fh     = NFS_FH(data->inode);
1193         /* Note: we always request a commit of the entire inode */
1194         data->args.offset = 0;
1195         data->args.count  = 0;
1196         data->args.context = get_nfs_open_context(first->wb_context);
1197         data->res.count   = 0;
1198         data->res.fattr   = &data->fattr;
1199         data->res.verf    = &data->verf;
1200         nfs_fattr_init(&data->fattr);
1201
1202         /* Set up the initial task struct.  */
1203         NFS_PROTO(inode)->commit_setup(data, &msg);
1204
1205         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1206
1207         task = rpc_run_task(&task_setup_data);
1208         if (!IS_ERR(task))
1209                 rpc_put_task(task);
1210 }
1211
1212 /*
1213  * Commit dirty pages
1214  */
1215 static int
1216 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1217 {
1218         struct nfs_write_data   *data;
1219         struct nfs_page         *req;
1220
1221         data = nfs_commit_alloc();
1222
1223         if (!data)
1224                 goto out_bad;
1225
1226         /* Set up the argument struct */
1227         nfs_commit_rpcsetup(head, data, how);
1228
1229         return 0;
1230  out_bad:
1231         while (!list_empty(head)) {
1232                 req = nfs_list_entry(head->next);
1233                 nfs_list_remove_request(req);
1234                 nfs_mark_request_commit(req);
1235                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1236                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1237                                 BDI_RECLAIMABLE);
1238                 nfs_clear_page_tag_locked(req);
1239         }
1240         return -ENOMEM;
1241 }
1242
1243 /*
1244  * COMMIT call returned
1245  */
1246 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1247 {
1248         struct nfs_write_data   *data = calldata;
1249         struct nfs_page         *req;
1250
1251         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1252                                 task->tk_pid, task->tk_status);
1253
1254         /* Call the NFS version-specific code */
1255         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1256                 return;
1257
1258         while (!list_empty(&data->pages)) {
1259                 req = nfs_list_entry(data->pages.next);
1260                 nfs_list_remove_request(req);
1261                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
1262                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1263                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1264                                 BDI_RECLAIMABLE);
1265
1266                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1267                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1268                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1269                         req->wb_bytes,
1270                         (long long)req_offset(req));
1271                 if (task->tk_status < 0) {
1272                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1273                         nfs_inode_remove_request(req);
1274                         dprintk(", error = %d\n", task->tk_status);
1275                         goto next;
1276                 }
1277
1278                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1279                  * returned by the server against all stored verfs. */
1280                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1281                         /* We have a match */
1282                         /* Set the PG_uptodate flag */
1283                         nfs_mark_uptodate(req->wb_page, req->wb_pgbase,
1284                                         req->wb_bytes);
1285                         nfs_inode_remove_request(req);
1286                         dprintk(" OK\n");
1287                         goto next;
1288                 }
1289                 /* We have a mismatch. Write the page again */
1290                 dprintk(" mismatch\n");
1291                 nfs_redirty_request(req);
1292         next:
1293                 nfs_clear_page_tag_locked(req);
1294         }
1295 }
1296
1297 static const struct rpc_call_ops nfs_commit_ops = {
1298         .rpc_call_done = nfs_commit_done,
1299         .rpc_release = nfs_commit_release,
1300 };
1301
1302 int nfs_commit_inode(struct inode *inode, int how)
1303 {
1304         LIST_HEAD(head);
1305         int res;
1306
1307         spin_lock(&inode->i_lock);
1308         res = nfs_scan_commit(inode, &head, 0, 0);
1309         spin_unlock(&inode->i_lock);
1310         if (res) {
1311                 int error = nfs_commit_list(inode, &head, how);
1312                 if (error < 0)
1313                         return error;
1314         }
1315         return res;
1316 }
1317 #else
1318 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1319 {
1320         return 0;
1321 }
1322 #endif
1323
1324 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1325 {
1326         struct inode *inode = mapping->host;
1327         pgoff_t idx_start, idx_end;
1328         unsigned int npages = 0;
1329         LIST_HEAD(head);
1330         int nocommit = how & FLUSH_NOCOMMIT;
1331         long pages, ret;
1332
1333         /* FIXME */
1334         if (wbc->range_cyclic)
1335                 idx_start = 0;
1336         else {
1337                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1338                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1339                 if (idx_end > idx_start) {
1340                         pgoff_t l_npages = 1 + idx_end - idx_start;
1341                         npages = l_npages;
1342                         if (sizeof(npages) != sizeof(l_npages) &&
1343                                         (pgoff_t)npages != l_npages)
1344                                 npages = 0;
1345                 }
1346         }
1347         how &= ~FLUSH_NOCOMMIT;
1348         spin_lock(&inode->i_lock);
1349         do {
1350                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1351                 if (ret != 0)
1352                         continue;
1353                 if (nocommit)
1354                         break;
1355                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1356                 if (pages == 0)
1357                         break;
1358                 if (how & FLUSH_INVALIDATE) {
1359                         spin_unlock(&inode->i_lock);
1360                         nfs_cancel_commit_list(&head);
1361                         ret = pages;
1362                         spin_lock(&inode->i_lock);
1363                         continue;
1364                 }
1365                 pages += nfs_scan_commit(inode, &head, 0, 0);
1366                 spin_unlock(&inode->i_lock);
1367                 ret = nfs_commit_list(inode, &head, how);
1368                 spin_lock(&inode->i_lock);
1369
1370         } while (ret >= 0);
1371         spin_unlock(&inode->i_lock);
1372         return ret;
1373 }
1374
1375 static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1376 {
1377         int ret;
1378
1379         ret = nfs_writepages(mapping, wbc);
1380         if (ret < 0)
1381                 goto out;
1382         ret = nfs_sync_mapping_wait(mapping, wbc, how);
1383         if (ret < 0)
1384                 goto out;
1385         return 0;
1386 out:
1387         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1388         return ret;
1389 }
1390
1391 /* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
1392 static int nfs_write_mapping(struct address_space *mapping, int how)
1393 {
1394         struct writeback_control wbc = {
1395                 .bdi = mapping->backing_dev_info,
1396                 .sync_mode = WB_SYNC_NONE,
1397                 .nr_to_write = LONG_MAX,
1398                 .for_writepages = 1,
1399                 .range_cyclic = 1,
1400         };
1401         int ret;
1402
1403         ret = __nfs_write_mapping(mapping, &wbc, how);
1404         if (ret < 0)
1405                 return ret;
1406         wbc.sync_mode = WB_SYNC_ALL;
1407         return __nfs_write_mapping(mapping, &wbc, how);
1408 }
1409
1410 /*
1411  * flush the inode to disk.
1412  */
1413 int nfs_wb_all(struct inode *inode)
1414 {
1415         return nfs_write_mapping(inode->i_mapping, 0);
1416 }
1417
1418 int nfs_wb_nocommit(struct inode *inode)
1419 {
1420         return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
1421 }
1422
1423 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1424 {
1425         struct nfs_page *req;
1426         loff_t range_start = page_offset(page);
1427         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1428         struct writeback_control wbc = {
1429                 .bdi = page->mapping->backing_dev_info,
1430                 .sync_mode = WB_SYNC_ALL,
1431                 .nr_to_write = LONG_MAX,
1432                 .range_start = range_start,
1433                 .range_end = range_end,
1434         };
1435         int ret = 0;
1436
1437         BUG_ON(!PageLocked(page));
1438         for (;;) {
1439                 req = nfs_page_find_request(page);
1440                 if (req == NULL)
1441                         goto out;
1442                 if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1443                         nfs_release_request(req);
1444                         break;
1445                 }
1446                 if (nfs_lock_request_dontget(req)) {
1447                         nfs_inode_remove_request(req);
1448                         /*
1449                          * In case nfs_inode_remove_request has marked the
1450                          * page as being dirty
1451                          */
1452                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1453                         nfs_unlock_request(req);
1454                         break;
1455                 }
1456                 ret = nfs_wait_on_request(req);
1457                 if (ret < 0)
1458                         goto out;
1459         }
1460         if (!PagePrivate(page))
1461                 return 0;
1462         ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
1463 out:
1464         return ret;
1465 }
1466
1467 static int nfs_wb_page_priority(struct inode *inode, struct page *page,
1468                                 int how)
1469 {
1470         loff_t range_start = page_offset(page);
1471         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1472         struct writeback_control wbc = {
1473                 .bdi = page->mapping->backing_dev_info,
1474                 .sync_mode = WB_SYNC_ALL,
1475                 .nr_to_write = LONG_MAX,
1476                 .range_start = range_start,
1477                 .range_end = range_end,
1478         };
1479         int ret;
1480
1481         BUG_ON(!PageLocked(page));
1482         if (clear_page_dirty_for_io(page)) {
1483                 ret = nfs_writepage_locked(page, &wbc);
1484                 if (ret < 0)
1485                         goto out;
1486         }
1487         if (!PagePrivate(page))
1488                 return 0;
1489         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1490         if (ret >= 0)
1491                 return 0;
1492 out:
1493         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1494         return ret;
1495 }
1496
1497 /*
1498  * Write back all requests on one page - we do this before reading it.
1499  */
1500 int nfs_wb_page(struct inode *inode, struct page* page)
1501 {
1502         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1503 }
1504
1505 int __init nfs_init_writepagecache(void)
1506 {
1507         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1508                                              sizeof(struct nfs_write_data),
1509                                              0, SLAB_HWCACHE_ALIGN,
1510                                              NULL);
1511         if (nfs_wdata_cachep == NULL)
1512                 return -ENOMEM;
1513
1514         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1515                                                      nfs_wdata_cachep);
1516         if (nfs_wdata_mempool == NULL)
1517                 return -ENOMEM;
1518
1519         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1520                                                       nfs_wdata_cachep);
1521         if (nfs_commit_mempool == NULL)
1522                 return -ENOMEM;
1523
1524         /*
1525          * NFS congestion size, scale with available memory.
1526          *
1527          *  64MB:    8192k
1528          * 128MB:   11585k
1529          * 256MB:   16384k
1530          * 512MB:   23170k
1531          *   1GB:   32768k
1532          *   2GB:   46340k
1533          *   4GB:   65536k
1534          *   8GB:   92681k
1535          *  16GB:  131072k
1536          *
1537          * This allows larger machines to have larger/more transfers.
1538          * Limit the default to 256M
1539          */
1540         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1541         if (nfs_congestion_kb > 256*1024)
1542                 nfs_congestion_kb = 256*1024;
1543
1544         return 0;
1545 }
1546
1547 void nfs_destroy_writepagecache(void)
1548 {
1549         mempool_destroy(nfs_commit_mempool);
1550         mempool_destroy(nfs_wdata_mempool);
1551         kmem_cache_destroy(nfs_wdata_cachep);
1552 }
1553