fs/nfs/write.c

   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 static void nfs_commit_rcu_free(struct rcu_head *head)
  62 {
  63         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
  64         if (p && (p->pagevec != &p->page_array[0]))
  65                 kfree(p->pagevec);
  66         mempool_free(p, nfs_commit_mempool);
  67 }
  68
  69 void nfs_commit_free(struct nfs_write_data *wdata)
  70 {
  71         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_commit_rcu_free);
  72 }
  73
  74 struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
  75 {
  76         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
  77
  78         if (p) {
  79                 memset(p, 0, sizeof(*p));
  80                 INIT_LIST_HEAD(&p->pages);
  81                 p->npages = pagecount;
  82                 if (pagecount <= ARRAY_SIZE(p->page_array))
  83                         p->pagevec = p->page_array;
  84                 else {
  85                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
  86                         if (!p->pagevec) {
  87                                 mempool_free(p, nfs_wdata_mempool);
  88                                 p = NULL;
  89                         }
  90                 }
  91         }
  92         return p;
  93 }
  94
  95 static void nfs_writedata_rcu_free(struct rcu_head *head)
  96 {
  97         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
  98         if (p && (p->pagevec != &p->page_array[0]))
  99                 kfree(p->pagevec);
 100         mempool_free(p, nfs_wdata_mempool);
 101 }
 102
 103 static void nfs_writedata_free(struct nfs_write_data *wdata)
 104 {
 105         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free);
 106 }
 107
 108 void nfs_writedata_release(void *wdata)
 109 {
 110         nfs_writedata_free(wdata);
 111 }
 112
 113 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 114 {
 115         ctx->error = error;
 116         smp_wmb();
 117         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 118 }
 119
 120 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 121 {
 122         struct nfs_page *req = NULL;
 123
 124         if (PagePrivate(page)) {
 125                 req = (struct nfs_page *)page_private(page);
 126                 if (req != NULL)
 127                         kref_get(&req->wb_kref);
 128         }
 129         return req;
 130 }
 131
 132 static struct nfs_page *nfs_page_find_request(struct page *page)
 133 {
 134         struct inode *inode = page->mapping->host;
 135         struct nfs_page *req = NULL;
 136
 137         spin_lock(&inode->i_lock);
 138         req = nfs_page_find_request_locked(page);
 139         spin_unlock(&inode->i_lock);
 140         return req;
 141 }
 142
 143 /* Adjust the file length if we're writing beyond the end */
 144 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 145 {
 146         struct inode *inode = page->mapping->host;
 147         loff_t end, i_size = i_size_read(inode);
 148         pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 149
 150         if (i_size > 0 && page->index < end_index)
 151                 return;
 152         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 153         if (i_size >= end)
 154                 return;
 155         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 156         i_size_write(inode, end);
 157 }
 158
 159 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 160 static void nfs_set_pageerror(struct page *page)
 161 {
 162         SetPageError(page);
 163         nfs_zap_mapping(page->mapping->host, page->mapping);
 164 }
 165
 166 /* We can set the PG_uptodate flag if we see that a write request
 167  * covers the full page.
 168  */
 169 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 170 {
 171         if (PageUptodate(page))
 172                 return;
 173         if (base != 0)
 174                 return;
 175         if (count != nfs_page_length(page))
 176                 return;
 177         SetPageUptodate(page);
 178 }
 179
 180 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 181                 unsigned int offset, unsigned int count)
 182 {
 183         struct nfs_page *req;
 184         int ret;
 185
 186         for (;;) {
 187                 req = nfs_update_request(ctx, page, offset, count);
 188                 if (!IS_ERR(req))
 189                         break;
 190                 ret = PTR_ERR(req);
 191                 if (ret != -EBUSY)
 192                         return ret;
 193                 ret = nfs_wb_page(page->mapping->host, page);
 194                 if (ret != 0)
 195                         return ret;
 196         }
 197         /* Update file length */
 198         nfs_grow_file(page, offset, count);
 199         nfs_unlock_request(req);
 200         return 0;
 201 }
 202
 203 static int wb_priority(struct writeback_control *wbc)
 204 {
 205         if (wbc->for_reclaim)
 206                 return FLUSH_HIGHPRI | FLUSH_STABLE;
 207         if (wbc->for_kupdate)
 208                 return FLUSH_LOWPRI;
 209         return 0;
 210 }
 211
 212 /*
 213  * NFS congestion control
 214  */
 215
 216 int nfs_congestion_kb;
 217
 218 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 219 #define NFS_CONGESTION_OFF_THRESH       \
 220         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 221
 222 static int nfs_set_page_writeback(struct page *page)
 223 {
 224         int ret = test_set_page_writeback(page);
 225
 226         if (!ret) {
 227                 struct inode *inode = page->mapping->host;
 228                 struct nfs_server *nfss = NFS_SERVER(inode);
 229
 230                 if (atomic_long_inc_return(&nfss->writeback) >
 231                                 NFS_CONGESTION_ON_THRESH)
 232                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
 233         }
 234         return ret;
 235 }
 236
 237 static void nfs_end_page_writeback(struct page *page)
 238 {
 239         struct inode *inode = page->mapping->host;
 240         struct nfs_server *nfss = NFS_SERVER(inode);
 241
 242         end_page_writeback(page);
 243         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 244                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
 245 }
 246
 247 /*
 248  * Find an associated nfs write request, and prepare to flush it out
 249  * May return an error if the user signalled nfs_wait_on_request().
 250  */
 251 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 252                                 struct page *page)
 253 {
 254         struct inode *inode = page->mapping->host;
 255         struct nfs_inode *nfsi = NFS_I(inode);
 256         struct nfs_page *req;
 257         int ret;
 258
 259         spin_lock(&inode->i_lock);
 260         for(;;) {
 261                 req = nfs_page_find_request_locked(page);
 262                 if (req == NULL) {
 263                         spin_unlock(&inode->i_lock);
 264                         return 0;
 265                 }
 266                 if (nfs_lock_request_dontget(req))
 267                         break;
 268                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 269                  *       then the call to nfs_lock_request_dontget() will always
 270                  *       succeed provided that someone hasn't already marked the
 271                  *       request as dirty (in which case we don't care).
 272                  */
 273                 spin_unlock(&inode->i_lock);
 274                 ret = nfs_wait_on_request(req);
 275                 nfs_release_request(req);
 276                 if (ret != 0)
 277                         return ret;
 278                 spin_lock(&inode->i_lock);
 279         }
 280         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 281                 /* This request is marked for commit */
 282                 spin_unlock(&inode->i_lock);
 283                 nfs_unlock_request(req);
 284                 nfs_pageio_complete(pgio);
 285                 return 0;
 286         }
 287         if (nfs_set_page_writeback(page) != 0) {
 288                 spin_unlock(&inode->i_lock);
 289                 BUG();
 290         }
 291         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
 292                         NFS_PAGE_TAG_LOCKED);
 293         spin_unlock(&inode->i_lock);
 294         nfs_pageio_add_request(pgio, req);
 295         return 0;
 296 }
 297
 298 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 299 {
 300         struct inode *inode = page->mapping->host;
 301
 302         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 303         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 304
 305         nfs_pageio_cond_complete(pgio, page->index);
 306         return nfs_page_async_flush(pgio, page);
 307 }
 308
 309 /*
 310  * Write an mmapped page to the server.
 311  */
 312 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 313 {
 314         struct nfs_pageio_descriptor pgio;
 315         int err;
 316
 317         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
 318         err = nfs_do_writepage(page, wbc, &pgio);
 319         nfs_pageio_complete(&pgio);
 320         if (err < 0)
 321                 return err;
 322         if (pgio.pg_error < 0)
 323                 return pgio.pg_error;
 324         return 0;
 325 }
 326
 327 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 328 {
 329         int ret;
 330
 331         ret = nfs_writepage_locked(page, wbc);
 332         unlock_page(page);
 333         return ret;
 334 }
 335
 336 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 337 {
 338         int ret;
 339
 340         ret = nfs_do_writepage(page, wbc, data);
 341         unlock_page(page);
 342         return ret;
 343 }
 344
 345 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 346 {
 347         struct inode *inode = mapping->host;
 348         struct nfs_pageio_descriptor pgio;
 349         int err;
 350
 351         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 352
 353         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
 354         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 355         nfs_pageio_complete(&pgio);
 356         if (err < 0)
 357                 return err;
 358         if (pgio.pg_error < 0)
 359                 return pgio.pg_error;
 360         return 0;
 361 }
 362
 363 /*
 364  * Insert a write request into an inode
 365  */
 366 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 367 {
 368         struct nfs_inode *nfsi = NFS_I(inode);
 369         int error;
 370
 371         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 372         BUG_ON(error == -EEXIST);
 373         if (error)
 374                 return error;
 375         if (!nfsi->npages) {
 376                 igrab(inode);
 377                 if (nfs_have_delegation(inode, FMODE_WRITE))
 378                         nfsi->change_attr++;
 379         }
 380         SetPagePrivate(req->wb_page);
 381         set_page_private(req->wb_page, (unsigned long)req);
 382         nfsi->npages++;
 383         kref_get(&req->wb_kref);
 384         return 0;
 385 }
 386
 387 /*
 388  * Remove a write request from an inode
 389  */
 390 static void nfs_inode_remove_request(struct nfs_page *req)
 391 {
 392         struct inode *inode = req->wb_context->path.dentry->d_inode;
 393         struct nfs_inode *nfsi = NFS_I(inode);
 394
 395         BUG_ON (!NFS_WBACK_BUSY(req));
 396
 397         spin_lock(&inode->i_lock);
 398         set_page_private(req->wb_page, 0);
 399         ClearPagePrivate(req->wb_page);
 400         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 401         nfsi->npages--;
 402         if (!nfsi->npages) {
 403                 spin_unlock(&inode->i_lock);
 404                 iput(inode);
 405         } else
 406                 spin_unlock(&inode->i_lock);
 407         nfs_clear_request(req);
 408         nfs_release_request(req);
 409 }
 410
 411 static void
 412 nfs_redirty_request(struct nfs_page *req)
 413 {
 414         __set_page_dirty_nobuffers(req->wb_page);
 415 }
 416
 417 /*
 418  * Check if a request is dirty
 419  */
 420 static inline int
 421 nfs_dirty_request(struct nfs_page *req)
 422 {
 423         struct page *page = req->wb_page;
 424
 425         if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
 426                 return 0;
 427         return !PageWriteback(req->wb_page);
 428 }
 429
 430 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 431 /*
 432  * Add a request to the inode's commit list.
 433  */
 434 static void
 435 nfs_mark_request_commit(struct nfs_page *req)
 436 {
 437         struct inode *inode = req->wb_context->path.dentry->d_inode;
 438         struct nfs_inode *nfsi = NFS_I(inode);
 439
 440         spin_lock(&inode->i_lock);
 441         nfsi->ncommit++;
 442         set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
 443         radix_tree_tag_set(&nfsi->nfs_page_tree,
 444                         req->wb_index,
 445                         NFS_PAGE_TAG_COMMIT);
 446         spin_unlock(&inode->i_lock);
 447         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 448         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 449         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 450 }
 451
 452 static inline
 453 int nfs_write_need_commit(struct nfs_write_data *data)
 454 {
 455         return data->verf.committed != NFS_FILE_SYNC;
 456 }
 457
 458 static inline
 459 int nfs_reschedule_unstable_write(struct nfs_page *req)
 460 {
 461         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 462                 nfs_mark_request_commit(req);
 463                 return 1;
 464         }
 465         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 466                 nfs_redirty_request(req);
 467                 return 1;
 468         }
 469         return 0;
 470 }
 471 #else
 472 static inline void
 473 nfs_mark_request_commit(struct nfs_page *req)
 474 {
 475 }
 476
 477 static inline
 478 int nfs_write_need_commit(struct nfs_write_data *data)
 479 {
 480         return 0;
 481 }
 482
 483 static inline
 484 int nfs_reschedule_unstable_write(struct nfs_page *req)
 485 {
 486         return 0;
 487 }
 488 #endif
 489
 490 /*
 491  * Wait for a request to complete.
 492  *
 493  * Interruptible by signals only if mounted with intr flag.
 494  */
 495 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
 496 {
 497         struct nfs_inode *nfsi = NFS_I(inode);
 498         struct nfs_page *req;
 499         pgoff_t idx_end, next;
 500         unsigned int            res = 0;
 501         int                     error;
 502
 503         if (npages == 0)
 504                 idx_end = ~0;
 505         else
 506                 idx_end = idx_start + npages - 1;
 507
 508         next = idx_start;
 509         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
 510                 if (req->wb_index > idx_end)
 511                         break;
 512
 513                 next = req->wb_index + 1;
 514                 BUG_ON(!NFS_WBACK_BUSY(req));
 515
 516                 kref_get(&req->wb_kref);
 517                 spin_unlock(&inode->i_lock);
 518                 error = nfs_wait_on_request(req);
 519                 nfs_release_request(req);
 520                 spin_lock(&inode->i_lock);
 521                 if (error < 0)
 522                         return error;
 523                 res++;
 524         }
 525         return res;
 526 }
 527
 528 static void nfs_cancel_commit_list(struct list_head *head)
 529 {
 530         struct nfs_page *req;
 531
 532         while(!list_empty(head)) {
 533                 req = nfs_list_entry(head->next);
 534                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 535                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
 536                                 BDI_RECLAIMABLE);
 537                 nfs_list_remove_request(req);
 538                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
 539                 nfs_inode_remove_request(req);
 540                 nfs_unlock_request(req);
 541         }
 542 }
 543
 544 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 545 /*
 546  * nfs_scan_commit - Scan an inode for commit requests
 547  * @inode: NFS inode to scan
 548  * @dst: destination list
 549  * @idx_start: lower bound of page->index to scan.
 550  * @npages: idx_start + npages sets the upper bound to scan.
 551  *
 552  * Moves requests from the inode's 'commit' request list.
 553  * The requests are *not* checked to ensure that they form a contiguous set.
 554  */
 555 static int
 556 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 557 {
 558         struct nfs_inode *nfsi = NFS_I(inode);
 559         int res = 0;
 560
 561         if (nfsi->ncommit != 0) {
 562                 res = nfs_scan_list(nfsi, dst, idx_start, npages,
 563                                 NFS_PAGE_TAG_COMMIT);
 564                 nfsi->ncommit -= res;
 565         }
 566         return res;
 567 }
 568 #else
 569 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 570 {
 571         return 0;
 572 }
 573 #endif
 574
 575 /*
 576  * Try to update any existing write request, or create one if there is none.
 577  * In order to match, the request's credentials must match those of
 578  * the calling process.
 579  *
 580  * Note: Should always be called with the Page Lock held!
 581  */
 582 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 583                 struct page *page, unsigned int offset, unsigned int bytes)
 584 {
 585         struct address_space *mapping = page->mapping;
 586         struct inode *inode = mapping->host;
 587         struct nfs_page         *req, *new = NULL;
 588         pgoff_t         rqend, end;
 589
 590         end = offset + bytes;
 591
 592         for (;;) {
 593                 /* Loop over all inode entries and see if we find
 594                  * A request for the page we wish to update
 595                  */
 596                 spin_lock(&inode->i_lock);
 597                 req = nfs_page_find_request_locked(page);
 598                 if (req) {
 599                         if (!nfs_lock_request_dontget(req)) {
 600                                 int error;
 601
 602                                 spin_unlock(&inode->i_lock);
 603                                 error = nfs_wait_on_request(req);
 604                                 nfs_release_request(req);
 605                                 if (error < 0) {
 606                                         if (new)
 607                                                 nfs_release_request(new);
 608                                         return ERR_PTR(error);
 609                                 }
 610                                 continue;
 611                         }
 612                         spin_unlock(&inode->i_lock);
 613                         if (new)
 614                                 nfs_release_request(new);
 615                         break;
 616                 }
 617
 618                 if (new) {
 619                         int error;
 620                         nfs_lock_request_dontget(new);
 621                         error = nfs_inode_add_request(inode, new);
 622                         if (error) {
 623                                 spin_unlock(&inode->i_lock);
 624                                 nfs_unlock_request(new);
 625                                 return ERR_PTR(error);
 626                         }
 627                         spin_unlock(&inode->i_lock);
 628                         req = new;
 629                         goto zero_page;
 630                 }
 631                 spin_unlock(&inode->i_lock);
 632
 633                 new = nfs_create_request(ctx, inode, page, offset, bytes);
 634                 if (IS_ERR(new))
 635                         return new;
 636         }
 637
 638         /* We have a request for our page.
 639          * If the creds don't match, or the
 640          * page addresses don't match,
 641          * tell the caller to wait on the conflicting
 642          * request.
 643          */
 644         rqend = req->wb_offset + req->wb_bytes;
 645         if (req->wb_context != ctx
 646             || req->wb_page != page
 647             || !nfs_dirty_request(req)
 648             || offset > rqend || end < req->wb_offset) {
 649                 nfs_unlock_request(req);
 650                 return ERR_PTR(-EBUSY);
 651         }
 652
 653         /* Okay, the request matches. Update the region */
 654         if (offset < req->wb_offset) {
 655                 req->wb_offset = offset;
 656                 req->wb_pgbase = offset;
 657                 req->wb_bytes = max(end, rqend) - req->wb_offset;
 658                 goto zero_page;
 659         }
 660
 661         if (end > rqend)
 662                 req->wb_bytes = end - req->wb_offset;
 663
 664         return req;
 665 zero_page:
 666         /* If this page might potentially be marked as up to date,
 667          * then we need to zero any uninitalised data. */
 668         if (req->wb_pgbase == 0 && req->wb_bytes != PAGE_CACHE_SIZE
 669                         && !PageUptodate(req->wb_page))
 670                 zero_user_page(req->wb_page, req->wb_bytes,
 671                                 PAGE_CACHE_SIZE - req->wb_bytes,
 672                                 KM_USER0);
 673         return req;
 674 }
 675
 676 int nfs_flush_incompatible(struct file *file, struct page *page)
 677 {
 678         struct nfs_open_context *ctx = nfs_file_open_context(file);
 679         struct nfs_page *req;
 680         int do_flush, status;
 681         /*
 682          * Look for a request corresponding to this page. If there
 683          * is one, and it belongs to another file, we flush it out
 684          * before we try to copy anything into the page. Do this
 685          * due to the lack of an ACCESS-type call in NFSv2.
 686          * Also do the same if we find a request from an existing
 687          * dropped page.
 688          */
 689         do {
 690                 req = nfs_page_find_request(page);
 691                 if (req == NULL)
 692                         return 0;
 693                 do_flush = req->wb_page != page || req->wb_context != ctx
 694                         || !nfs_dirty_request(req);
 695                 nfs_release_request(req);
 696                 if (!do_flush)
 697                         return 0;
 698                 status = nfs_wb_page(page->mapping->host, page);
 699         } while (status == 0);
 700         return status;
 701 }
 702
 703 /*
 704  * Update and possibly write a cached page of an NFS file.
 705  *
 706  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 707  * things with a page scheduled for an RPC call (e.g. invalidate it).
 708  */
 709 int nfs_updatepage(struct file *file, struct page *page,
 710                 unsigned int offset, unsigned int count)
 711 {
 712         struct nfs_open_context *ctx = nfs_file_open_context(file);
 713         struct inode    *inode = page->mapping->host;
 714         int             status = 0;
 715
 716         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 717
 718         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
 719                 file->f_path.dentry->d_parent->d_name.name,
 720                 file->f_path.dentry->d_name.name, count,
 721                 (long long)(page_offset(page) +offset));
 722
 723         /* If we're not using byte range locks, and we know the page
 724          * is entirely in cache, it may be more efficient to avoid
 725          * fragmenting write requests.
 726          */
 727         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
 728                 count = max(count + offset, nfs_page_length(page));
 729                 offset = 0;
 730         }
 731
 732         status = nfs_writepage_setup(ctx, page, offset, count);
 733         __set_page_dirty_nobuffers(page);
 734
 735         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
 736                         status, (long long)i_size_read(inode));
 737         if (status < 0)
 738                 nfs_set_pageerror(page);
 739         return status;
 740 }
 741
 742 static void nfs_writepage_release(struct nfs_page *req)
 743 {
 744
 745         if (PageError(req->wb_page)) {
 746                 nfs_end_page_writeback(req->wb_page);
 747                 nfs_inode_remove_request(req);
 748         } else if (!nfs_reschedule_unstable_write(req)) {
 749                 /* Set the PG_uptodate flag */
 750                 nfs_mark_uptodate(req->wb_page, req->wb_pgbase, req->wb_bytes);
 751                 nfs_end_page_writeback(req->wb_page);
 752                 nfs_inode_remove_request(req);
 753         } else
 754                 nfs_end_page_writeback(req->wb_page);
 755         nfs_clear_page_tag_locked(req);
 756 }
 757
 758 static inline int flush_task_priority(int how)
 759 {
 760         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 761                 case FLUSH_HIGHPRI:
 762                         return RPC_PRIORITY_HIGH;
 763                 case FLUSH_LOWPRI:
 764                         return RPC_PRIORITY_LOW;
 765         }
 766         return RPC_PRIORITY_NORMAL;
 767 }
 768
 769 /*
 770  * Set up the argument/result storage required for the RPC call.
 771  */
 772 static void nfs_write_rpcsetup(struct nfs_page *req,
 773                 struct nfs_write_data *data,
 774                 const struct rpc_call_ops *call_ops,
 775                 unsigned int count, unsigned int offset,
 776                 int how)
 777 {
 778         struct inode            *inode;
 779         int flags;
 780
 781         /* Set up the RPC argument and reply structs
 782          * NB: take care not to mess about with data->commit et al. */
 783
 784         data->req = req;
 785         data->inode = inode = req->wb_context->path.dentry->d_inode;
 786         data->cred = req->wb_context->cred;
 787
 788         data->args.fh     = NFS_FH(inode);
 789         data->args.offset = req_offset(req) + offset;
 790         data->args.pgbase = req->wb_pgbase + offset;
 791         data->args.pages  = data->pagevec;
 792         data->args.count  = count;
 793         data->args.context = req->wb_context;
 794
 795         data->res.fattr   = &data->fattr;
 796         data->res.count   = count;
 797         data->res.verf    = &data->verf;
 798         nfs_fattr_init(&data->fattr);
 799
 800         /* Set up the initial task struct.  */
 801         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 802         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
 803         NFS_PROTO(inode)->write_setup(data, how);
 804
 805         data->task.tk_priority = flush_task_priority(how);
 806         data->task.tk_cookie = (unsigned long)inode;
 807
 808         dprintk("NFS: %5u initiated write call "
 809                 "(req %s/%Ld, %u bytes @ offset %Lu)\n",
 810                 data->task.tk_pid,
 811                 inode->i_sb->s_id,
 812                 (long long)NFS_FILEID(inode),
 813                 count,
 814                 (unsigned long long)data->args.offset);
 815 }
 816
 817 static void nfs_execute_write(struct nfs_write_data *data)
 818 {
 819         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
 820         sigset_t oldset;
 821
 822         rpc_clnt_sigmask(clnt, &oldset);
 823         rpc_execute(&data->task);
 824         rpc_clnt_sigunmask(clnt, &oldset);
 825 }
 826
 827 /*
 828  * Generate multiple small requests to write out a single
 829  * contiguous dirty area on one page.
 830  */
 831 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 832 {
 833         struct nfs_page *req = nfs_list_entry(head->next);
 834         struct page *page = req->wb_page;
 835         struct nfs_write_data *data;
 836         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 837         unsigned int offset;
 838         int requests = 0;
 839         LIST_HEAD(list);
 840
 841         nfs_list_remove_request(req);
 842
 843         nbytes = count;
 844         do {
 845                 size_t len = min(nbytes, wsize);
 846
 847                 data = nfs_writedata_alloc(1);
 848                 if (!data)
 849                         goto out_bad;
 850                 list_add(&data->pages, &list);
 851                 requests++;
 852                 nbytes -= len;
 853         } while (nbytes != 0);
 854         atomic_set(&req->wb_complete, requests);
 855
 856         ClearPageError(page);
 857         offset = 0;
 858         nbytes = count;
 859         do {
 860                 data = list_entry(list.next, struct nfs_write_data, pages);
 861                 list_del_init(&data->pages);
 862
 863                 data->pagevec[0] = page;
 864
 865                 if (nbytes < wsize)
 866                         wsize = nbytes;
 867                 nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 868                                    wsize, offset, how);
 869                 offset += wsize;
 870                 nbytes -= wsize;
 871                 nfs_execute_write(data);
 872         } while (nbytes != 0);
 873
 874         return 0;
 875
 876 out_bad:
 877         while (!list_empty(&list)) {
 878                 data = list_entry(list.next, struct nfs_write_data, pages);
 879                 list_del(&data->pages);
 880                 nfs_writedata_release(data);
 881         }
 882         nfs_redirty_request(req);
 883         nfs_end_page_writeback(req->wb_page);
 884         nfs_clear_page_tag_locked(req);
 885         return -ENOMEM;
 886 }
 887
 888 /*
 889  * Create an RPC task for the given write request and kick it.
 890  * The page must have been locked by the caller.
 891  *
 892  * It may happen that the page we're passed is not marked dirty.
 893  * This is the case if nfs_updatepage detects a conflicting request
 894  * that has been written but not committed.
 895  */
 896 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 897 {
 898         struct nfs_page         *req;
 899         struct page             **pages;
 900         struct nfs_write_data   *data;
 901
 902         data = nfs_writedata_alloc(npages);
 903         if (!data)
 904                 goto out_bad;
 905
 906         pages = data->pagevec;
 907         while (!list_empty(head)) {
 908                 req = nfs_list_entry(head->next);
 909                 nfs_list_remove_request(req);
 910                 nfs_list_add_request(req, &data->pages);
 911                 ClearPageError(req->wb_page);
 912                 *pages++ = req->wb_page;
 913         }
 914         req = nfs_list_entry(data->pages.next);
 915
 916         /* Set up the argument struct */
 917         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 918
 919         nfs_execute_write(data);
 920         return 0;
 921  out_bad:
 922         while (!list_empty(head)) {
 923                 req = nfs_list_entry(head->next);
 924                 nfs_list_remove_request(req);
 925                 nfs_redirty_request(req);
 926                 nfs_end_page_writeback(req->wb_page);
 927                 nfs_clear_page_tag_locked(req);
 928         }
 929         return -ENOMEM;
 930 }
 931
 932 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
 933                                   struct inode *inode, int ioflags)
 934 {
 935         int wsize = NFS_SERVER(inode)->wsize;
 936
 937         if (wsize < PAGE_CACHE_SIZE)
 938                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
 939         else
 940                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
 941 }
 942
 943 /*
 944  * Handle a write reply that flushed part of a page.
 945  */
 946 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
 947 {
 948         struct nfs_write_data   *data = calldata;
 949         struct nfs_page         *req = data->req;
 950         struct page             *page = req->wb_page;
 951
 952         dprintk("NFS: write (%s/%Ld %d@%Ld)",
 953                 req->wb_context->path.dentry->d_inode->i_sb->s_id,
 954                 (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
 955                 req->wb_bytes,
 956                 (long long)req_offset(req));
 957
 958         if (nfs_writeback_done(task, data) != 0)
 959                 return;
 960
 961         if (task->tk_status < 0) {
 962                 nfs_set_pageerror(page);
 963                 nfs_context_set_write_error(req->wb_context, task->tk_status);
 964                 dprintk(", error = %d\n", task->tk_status);
 965                 goto out;
 966         }
 967
 968         if (nfs_write_need_commit(data)) {
 969                 struct inode *inode = page->mapping->host;
 970
 971                 spin_lock(&inode->i_lock);
 972                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 973                         /* Do nothing we need to resend the writes */
 974                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 975                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
 976                         dprintk(" defer commit\n");
 977                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
 978                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
 979                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
 980                         dprintk(" server reboot detected\n");
 981                 }
 982                 spin_unlock(&inode->i_lock);
 983         } else
 984                 dprintk(" OK\n");
 985
 986 out:
 987         if (atomic_dec_and_test(&req->wb_complete))
 988                 nfs_writepage_release(req);
 989 }
 990
 991 static const struct rpc_call_ops nfs_write_partial_ops = {
 992         .rpc_call_done = nfs_writeback_done_partial,
 993         .rpc_release = nfs_writedata_release,
 994 };
 995
 996 /*
 997  * Handle a write reply that flushes a whole page.
 998  *
 999  * FIXME: There is an inherent race with invalidate_inode_pages and
1000  *        writebacks since the page->count is kept > 1 for as long
1001  *        as the page has a write request pending.
1002  */
1003 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1004 {
1005         struct nfs_write_data   *data = calldata;
1006         struct nfs_page         *req;
1007         struct page             *page;
1008
1009         if (nfs_writeback_done(task, data) != 0)
1010                 return;
1011
1012         /* Update attributes as result of writeback. */
1013         while (!list_empty(&data->pages)) {
1014                 req = nfs_list_entry(data->pages.next);
1015                 nfs_list_remove_request(req);
1016                 page = req->wb_page;
1017
1018                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1019                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1020                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1021                         req->wb_bytes,
1022                         (long long)req_offset(req));
1023
1024                 if (task->tk_status < 0) {
1025                         nfs_set_pageerror(page);
1026                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1027                         dprintk(", error = %d\n", task->tk_status);
1028                         goto remove_request;
1029                 }
1030
1031                 if (nfs_write_need_commit(data)) {
1032                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1033                         nfs_mark_request_commit(req);
1034                         nfs_end_page_writeback(page);
1035                         dprintk(" marked for commit\n");
1036                         goto next;
1037                 }
1038                 /* Set the PG_uptodate flag? */
1039                 nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
1040                 dprintk(" OK\n");
1041 remove_request:
1042                 nfs_end_page_writeback(page);
1043                 nfs_inode_remove_request(req);
1044         next:
1045                 nfs_clear_page_tag_locked(req);
1046         }
1047 }
1048
1049 static const struct rpc_call_ops nfs_write_full_ops = {
1050         .rpc_call_done = nfs_writeback_done_full,
1051         .rpc_release = nfs_writedata_release,
1052 };
1053
1054
1055 /*
1056  * This function is called when the WRITE call is complete.
1057  */
1058 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1059 {
1060         struct nfs_writeargs    *argp = &data->args;
1061         struct nfs_writeres     *resp = &data->res;
1062         int status;
1063
1064         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1065                 task->tk_pid, task->tk_status);
1066
1067         /*
1068          * ->write_done will attempt to use post-op attributes to detect
1069          * conflicting writes by other clients.  A strict interpretation
1070          * of close-to-open would allow us to continue caching even if
1071          * another writer had changed the file, but some applications
1072          * depend on tighter cache coherency when writing.
1073          */
1074         status = NFS_PROTO(data->inode)->write_done(task, data);
1075         if (status != 0)
1076                 return status;
1077         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1078
1079 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1080         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1081                 /* We tried a write call, but the server did not
1082                  * commit data to stable storage even though we
1083                  * requested it.
1084                  * Note: There is a known bug in Tru64 < 5.0 in which
1085                  *       the server reports NFS_DATA_SYNC, but performs
1086                  *       NFS_FILE_SYNC. We therefore implement this checking
1087                  *       as a dprintk() in order to avoid filling syslog.
1088                  */
1089                 static unsigned long    complain;
1090
1091                 if (time_before(complain, jiffies)) {
1092                         dprintk("NFS: faulty NFS server %s:"
1093                                 " (committed = %d) != (stable = %d)\n",
1094                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1095                                 resp->verf->committed, argp->stable);
1096                         complain = jiffies + 300 * HZ;
1097                 }
1098         }
1099 #endif
1100         /* Is this a short write? */
1101         if (task->tk_status >= 0 && resp->count < argp->count) {
1102                 static unsigned long    complain;
1103
1104                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1105
1106                 /* Has the server at least made some progress? */
1107                 if (resp->count != 0) {
1108                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1109                         if (resp->verf->committed != NFS_UNSTABLE) {
1110                                 /* Resend from where the server left off */
1111                                 argp->offset += resp->count;
1112                                 argp->pgbase += resp->count;
1113                                 argp->count -= resp->count;
1114                         } else {
1115                                 /* Resend as a stable write in order to avoid
1116                                  * headaches in the case of a server crash.
1117                                  */
1118                                 argp->stable = NFS_FILE_SYNC;
1119                         }
1120                         rpc_restart_call(task);
1121                         return -EAGAIN;
1122                 }
1123                 if (time_before(complain, jiffies)) {
1124                         printk(KERN_WARNING
1125                                "NFS: Server wrote zero bytes, expected %u.\n",
1126                                         argp->count);
1127                         complain = jiffies + 300 * HZ;
1128                 }
1129                 /* Can't do anything about it except throw an error. */
1130                 task->tk_status = -EIO;
1131         }
1132         return 0;
1133 }
1134
1135
1136 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1137 void nfs_commit_release(void *wdata)
1138 {
1139         nfs_commit_free(wdata);
1140 }
1141
1142 /*
1143  * Set up the argument/result storage required for the RPC call.
1144  */
1145 static void nfs_commit_rpcsetup(struct list_head *head,
1146                 struct nfs_write_data *data,
1147                 int how)
1148 {
1149         struct nfs_page         *first;
1150         struct inode            *inode;
1151         int flags;
1152
1153         /* Set up the RPC argument and reply structs
1154          * NB: take care not to mess about with data->commit et al. */
1155
1156         list_splice_init(head, &data->pages);
1157         first = nfs_list_entry(data->pages.next);
1158         inode = first->wb_context->path.dentry->d_inode;
1159
1160         data->inode       = inode;
1161         data->cred        = first->wb_context->cred;
1162
1163         data->args.fh     = NFS_FH(data->inode);
1164         /* Note: we always request a commit of the entire inode */
1165         data->args.offset = 0;
1166         data->args.count  = 0;
1167         data->res.count   = 0;
1168         data->res.fattr   = &data->fattr;
1169         data->res.verf    = &data->verf;
1170         nfs_fattr_init(&data->fattr);
1171
1172         /* Set up the initial task struct.  */
1173         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1174         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1175         NFS_PROTO(inode)->commit_setup(data, how);
1176
1177         data->task.tk_priority = flush_task_priority(how);
1178         data->task.tk_cookie = (unsigned long)inode;
1179
1180         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1181 }
1182
1183 /*
1184  * Commit dirty pages
1185  */
1186 static int
1187 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1188 {
1189         struct nfs_write_data   *data;
1190         struct nfs_page         *req;
1191
1192         data = nfs_commit_alloc();
1193
1194         if (!data)
1195                 goto out_bad;
1196
1197         /* Set up the argument struct */
1198         nfs_commit_rpcsetup(head, data, how);
1199
1200         nfs_execute_write(data);
1201         return 0;
1202  out_bad:
1203         while (!list_empty(head)) {
1204                 req = nfs_list_entry(head->next);
1205                 nfs_list_remove_request(req);
1206                 nfs_mark_request_commit(req);
1207                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1208                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1209                                 BDI_RECLAIMABLE);
1210                 nfs_clear_page_tag_locked(req);
1211         }
1212         return -ENOMEM;
1213 }
1214
1215 /*
1216  * COMMIT call returned
1217  */
1218 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1219 {
1220         struct nfs_write_data   *data = calldata;
1221         struct nfs_page         *req;
1222
1223         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1224                                 task->tk_pid, task->tk_status);
1225
1226         /* Call the NFS version-specific code */
1227         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1228                 return;
1229
1230         while (!list_empty(&data->pages)) {
1231                 req = nfs_list_entry(data->pages.next);
1232                 nfs_list_remove_request(req);
1233                 clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
1234                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1235                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1236                                 BDI_RECLAIMABLE);
1237
1238                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1239                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1240                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1241                         req->wb_bytes,
1242                         (long long)req_offset(req));
1243                 if (task->tk_status < 0) {
1244                         nfs_context_set_write_error(req->wb_context, task->tk_status);
1245                         nfs_inode_remove_request(req);
1246                         dprintk(", error = %d\n", task->tk_status);
1247                         goto next;
1248                 }
1249
1250                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1251                  * returned by the server against all stored verfs. */
1252                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1253                         /* We have a match */
1254                         /* Set the PG_uptodate flag */
1255                         nfs_mark_uptodate(req->wb_page, req->wb_pgbase,
1256                                         req->wb_bytes);
1257                         nfs_inode_remove_request(req);
1258                         dprintk(" OK\n");
1259                         goto next;
1260                 }
1261                 /* We have a mismatch. Write the page again */
1262                 dprintk(" mismatch\n");
1263                 nfs_redirty_request(req);
1264         next:
1265                 nfs_clear_page_tag_locked(req);
1266         }
1267 }
1268
1269 static const struct rpc_call_ops nfs_commit_ops = {
1270         .rpc_call_done = nfs_commit_done,
1271         .rpc_release = nfs_commit_release,
1272 };
1273
1274 int nfs_commit_inode(struct inode *inode, int how)
1275 {
1276         LIST_HEAD(head);
1277         int res;
1278
1279         spin_lock(&inode->i_lock);
1280         res = nfs_scan_commit(inode, &head, 0, 0);
1281         spin_unlock(&inode->i_lock);
1282         if (res) {
1283                 int error = nfs_commit_list(inode, &head, how);
1284                 if (error < 0)
1285                         return error;
1286         }
1287         return res;
1288 }
1289 #else
1290 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1291 {
1292         return 0;
1293 }
1294 #endif
1295
1296 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1297 {
1298         struct inode *inode = mapping->host;
1299         pgoff_t idx_start, idx_end;
1300         unsigned int npages = 0;
1301         LIST_HEAD(head);
1302         int nocommit = how & FLUSH_NOCOMMIT;
1303         long pages, ret;
1304
1305         /* FIXME */
1306         if (wbc->range_cyclic)
1307                 idx_start = 0;
1308         else {
1309                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1310                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1311                 if (idx_end > idx_start) {
1312                         pgoff_t l_npages = 1 + idx_end - idx_start;
1313                         npages = l_npages;
1314                         if (sizeof(npages) != sizeof(l_npages) &&
1315                                         (pgoff_t)npages != l_npages)
1316                                 npages = 0;
1317                 }
1318         }
1319         how &= ~FLUSH_NOCOMMIT;
1320         spin_lock(&inode->i_lock);
1321         do {
1322                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1323                 if (ret != 0)
1324                         continue;
1325                 if (nocommit)
1326                         break;
1327                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1328                 if (pages == 0)
1329                         break;
1330                 if (how & FLUSH_INVALIDATE) {
1331                         spin_unlock(&inode->i_lock);
1332                         nfs_cancel_commit_list(&head);
1333                         ret = pages;
1334                         spin_lock(&inode->i_lock);
1335                         continue;
1336                 }
1337                 pages += nfs_scan_commit(inode, &head, 0, 0);
1338                 spin_unlock(&inode->i_lock);
1339                 ret = nfs_commit_list(inode, &head, how);
1340                 spin_lock(&inode->i_lock);
1341
1342         } while (ret >= 0);
1343         spin_unlock(&inode->i_lock);
1344         return ret;
1345 }
1346
1347 static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1348 {
1349         int ret;
1350
1351         ret = nfs_writepages(mapping, wbc);
1352         if (ret < 0)
1353                 goto out;
1354         ret = nfs_sync_mapping_wait(mapping, wbc, how);
1355         if (ret < 0)
1356                 goto out;
1357         return 0;
1358 out:
1359         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1360         return ret;
1361 }
1362
1363 /* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
1364 static int nfs_write_mapping(struct address_space *mapping, int how)
1365 {
1366         struct writeback_control wbc = {
1367                 .bdi = mapping->backing_dev_info,
1368                 .sync_mode = WB_SYNC_NONE,
1369                 .nr_to_write = LONG_MAX,
1370                 .for_writepages = 1,
1371                 .range_cyclic = 1,
1372         };
1373         int ret;
1374
1375         ret = __nfs_write_mapping(mapping, &wbc, how);
1376         if (ret < 0)
1377                 return ret;
1378         wbc.sync_mode = WB_SYNC_ALL;
1379         return __nfs_write_mapping(mapping, &wbc, how);
1380 }
1381
1382 /*
1383  * flush the inode to disk.
1384  */
1385 int nfs_wb_all(struct inode *inode)
1386 {
1387         return nfs_write_mapping(inode->i_mapping, 0);
1388 }
1389
1390 int nfs_wb_nocommit(struct inode *inode)
1391 {
1392         return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
1393 }
1394
1395 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1396 {
1397         struct nfs_page *req;
1398         loff_t range_start = page_offset(page);
1399         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1400         struct writeback_control wbc = {
1401                 .bdi = page->mapping->backing_dev_info,
1402                 .sync_mode = WB_SYNC_ALL,
1403                 .nr_to_write = LONG_MAX,
1404                 .range_start = range_start,
1405                 .range_end = range_end,
1406         };
1407         int ret = 0;
1408
1409         BUG_ON(!PageLocked(page));
1410         for (;;) {
1411                 req = nfs_page_find_request(page);
1412                 if (req == NULL)
1413                         goto out;
1414                 if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1415                         nfs_release_request(req);
1416                         break;
1417                 }
1418                 if (nfs_lock_request_dontget(req)) {
1419                         nfs_inode_remove_request(req);
1420                         /*
1421                          * In case nfs_inode_remove_request has marked the
1422                          * page as being dirty
1423                          */
1424                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1425                         nfs_unlock_request(req);
1426                         break;
1427                 }
1428                 ret = nfs_wait_on_request(req);
1429                 if (ret < 0)
1430                         goto out;
1431         }
1432         if (!PagePrivate(page))
1433                 return 0;
1434         ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
1435 out:
1436         return ret;
1437 }
1438
1439 static int nfs_wb_page_priority(struct inode *inode, struct page *page,
1440                                 int how)
1441 {
1442         loff_t range_start = page_offset(page);
1443         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1444         struct writeback_control wbc = {
1445                 .bdi = page->mapping->backing_dev_info,
1446                 .sync_mode = WB_SYNC_ALL,
1447                 .nr_to_write = LONG_MAX,
1448                 .range_start = range_start,
1449                 .range_end = range_end,
1450         };
1451         int ret;
1452
1453         BUG_ON(!PageLocked(page));
1454         if (clear_page_dirty_for_io(page)) {
1455                 ret = nfs_writepage_locked(page, &wbc);
1456                 if (ret < 0)
1457                         goto out;
1458         }
1459         if (!PagePrivate(page))
1460                 return 0;
1461         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1462         if (ret >= 0)
1463                 return 0;
1464 out:
1465         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1466         return ret;
1467 }
1468
1469 /*
1470  * Write back all requests on one page - we do this before reading it.
1471  */
1472 int nfs_wb_page(struct inode *inode, struct page* page)
1473 {
1474         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1475 }
1476
1477 int __init nfs_init_writepagecache(void)
1478 {
1479         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1480                                              sizeof(struct nfs_write_data),
1481                                              0, SLAB_HWCACHE_ALIGN,
1482                                              NULL);
1483         if (nfs_wdata_cachep == NULL)
1484                 return -ENOMEM;
1485
1486         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1487                                                      nfs_wdata_cachep);
1488         if (nfs_wdata_mempool == NULL)
1489                 return -ENOMEM;
1490
1491         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1492                                                       nfs_wdata_cachep);
1493         if (nfs_commit_mempool == NULL)
1494                 return -ENOMEM;
1495
1496         /*
1497          * NFS congestion size, scale with available memory.
1498          *
1499          *  64MB:    8192k
1500          * 128MB:   11585k
1501          * 256MB:   16384k
1502          * 512MB:   23170k
1503          *   1GB:   32768k
1504          *   2GB:   46340k
1505          *   4GB:   65536k
1506          *   8GB:   92681k
1507          *  16GB:  131072k
1508          *
1509          * This allows larger machines to have larger/more transfers.
1510          * Limit the default to 256M
1511          */
1512         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1513         if (nfs_congestion_kb > 256*1024)
1514                 nfs_congestion_kb = 256*1024;
1515
1516         return 0;
1517 }
1518
1519 void nfs_destroy_writepagecache(void)
1520 {
1521         mempool_destroy(nfs_commit_mempool);
1522         mempool_destroy(nfs_wdata_mempool);
1523         kmem_cache_destroy(nfs_wdata_cachep);
1524 }
1525