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 #include <linux/smp_lock.h>
  25
  26 #include "delegation.h"
  27 #include "internal.h"
  28 #include "iostat.h"
  29
  30 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  31
  32 #define MIN_POOL_WRITE          (32)
  33 #define MIN_POOL_COMMIT         (4)
  34
  35 /*
  36  * Local function declarations
  37  */
  38 static struct nfs_page * nfs_update_request(struct nfs_open_context*,
  39                                             struct page *,
  40                                             unsigned int, unsigned int);
  41 static void nfs_mark_request_dirty(struct nfs_page *req);
  42 static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how);
  43 static const struct rpc_call_ops nfs_write_partial_ops;
  44 static const struct rpc_call_ops nfs_write_full_ops;
  45 static const struct rpc_call_ops nfs_commit_ops;
  46
  47 static struct kmem_cache *nfs_wdata_cachep;
  48 static mempool_t *nfs_wdata_mempool;
  49 static mempool_t *nfs_commit_mempool;
  50
  51 struct nfs_write_data *nfs_commit_alloc(void)
  52 {
  53         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
  54
  55         if (p) {
  56                 memset(p, 0, sizeof(*p));
  57                 INIT_LIST_HEAD(&p->pages);
  58         }
  59         return p;
  60 }
  61
  62 void nfs_commit_rcu_free(struct rcu_head *head)
  63 {
  64         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
  65         if (p && (p->pagevec != &p->page_array[0]))
  66                 kfree(p->pagevec);
  67         mempool_free(p, nfs_commit_mempool);
  68 }
  69
  70 void nfs_commit_free(struct nfs_write_data *wdata)
  71 {
  72         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_commit_rcu_free);
  73 }
  74
  75 struct nfs_write_data *nfs_writedata_alloc(size_t len)
  76 {
  77         unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
  78         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
  79
  80         if (p) {
  81                 memset(p, 0, sizeof(*p));
  82                 INIT_LIST_HEAD(&p->pages);
  83                 p->npages = pagecount;
  84                 if (pagecount <= ARRAY_SIZE(p->page_array))
  85                         p->pagevec = p->page_array;
  86                 else {
  87                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
  88                         if (!p->pagevec) {
  89                                 mempool_free(p, nfs_wdata_mempool);
  90                                 p = NULL;
  91                         }
  92                 }
  93         }
  94         return p;
  95 }
  96
  97 static void nfs_writedata_rcu_free(struct rcu_head *head)
  98 {
  99         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
 100         if (p && (p->pagevec != &p->page_array[0]))
 101                 kfree(p->pagevec);
 102         mempool_free(p, nfs_wdata_mempool);
 103 }
 104
 105 static void nfs_writedata_free(struct nfs_write_data *wdata)
 106 {
 107         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free);
 108 }
 109
 110 void nfs_writedata_release(void *wdata)
 111 {
 112         nfs_writedata_free(wdata);
 113 }
 114
 115 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 116 {
 117         struct nfs_page *req = NULL;
 118
 119         if (PagePrivate(page)) {
 120                 req = (struct nfs_page *)page_private(page);
 121                 if (req != NULL)
 122                         atomic_inc(&req->wb_count);
 123         }
 124         return req;
 125 }
 126
 127 static struct nfs_page *nfs_page_find_request(struct page *page)
 128 {
 129         struct nfs_page *req = NULL;
 130         spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
 131
 132         spin_lock(req_lock);
 133         req = nfs_page_find_request_locked(page);
 134         spin_unlock(req_lock);
 135         return req;
 136 }
 137
 138 /* Adjust the file length if we're writing beyond the end */
 139 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 140 {
 141         struct inode *inode = page->mapping->host;
 142         loff_t end, i_size = i_size_read(inode);
 143         unsigned long end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 144
 145         if (i_size > 0 && page->index < end_index)
 146                 return;
 147         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 148         if (i_size >= end)
 149                 return;
 150         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 151         i_size_write(inode, end);
 152 }
 153
 154 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 155 static void nfs_set_pageerror(struct page *page)
 156 {
 157         SetPageError(page);
 158         nfs_zap_mapping(page->mapping->host, page->mapping);
 159 }
 160
 161 /* We can set the PG_uptodate flag if we see that a write request
 162  * covers the full page.
 163  */
 164 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 165 {
 166         if (PageUptodate(page))
 167                 return;
 168         if (base != 0)
 169                 return;
 170         if (count != nfs_page_length(page))
 171                 return;
 172         if (count != PAGE_CACHE_SIZE)
 173                 memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
 174         SetPageUptodate(page);
 175 }
 176
 177 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 178                 unsigned int offset, unsigned int count)
 179 {
 180         struct nfs_page *req;
 181         int ret;
 182
 183         for (;;) {
 184                 req = nfs_update_request(ctx, page, offset, count);
 185                 if (!IS_ERR(req))
 186                         break;
 187                 ret = PTR_ERR(req);
 188                 if (ret != -EBUSY)
 189                         return ret;
 190                 ret = nfs_wb_page(page->mapping->host, page);
 191                 if (ret != 0)
 192                         return ret;
 193         }
 194         /* Update file length */
 195         nfs_grow_file(page, offset, count);
 196         /* Set the PG_uptodate flag? */
 197         nfs_mark_uptodate(page, offset, count);
 198         nfs_unlock_request(req);
 199         return 0;
 200 }
 201
 202 static int wb_priority(struct writeback_control *wbc)
 203 {
 204         if (wbc->for_reclaim)
 205                 return FLUSH_HIGHPRI;
 206         if (wbc->for_kupdate)
 207                 return FLUSH_LOWPRI;
 208         return 0;
 209 }
 210
 211 /*
 212  * NFS congestion control
 213  */
 214
 215 int nfs_congestion_kb;
 216
 217 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 218 #define NFS_CONGESTION_OFF_THRESH       \
 219         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 220
 221 static int nfs_set_page_writeback(struct page *page)
 222 {
 223         int ret = test_set_page_writeback(page);
 224
 225         if (!ret) {
 226                 struct inode *inode = page->mapping->host;
 227                 struct nfs_server *nfss = NFS_SERVER(inode);
 228
 229                 if (atomic_inc_return(&nfss->writeback) >
 230                                 NFS_CONGESTION_ON_THRESH)
 231                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
 232         }
 233         return ret;
 234 }
 235
 236 static void nfs_end_page_writeback(struct page *page)
 237 {
 238         struct inode *inode = page->mapping->host;
 239         struct nfs_server *nfss = NFS_SERVER(inode);
 240
 241         end_page_writeback(page);
 242         if (atomic_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) {
 243                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
 244                 congestion_end(WRITE);
 245         }
 246 }
 247
 248 /*
 249  * Find an associated nfs write request, and prepare to flush it out
 250  * Returns 1 if there was no write request, or if the request was
 251  * already tagged by nfs_set_page_dirty.Returns 0 if the request
 252  * was not tagged.
 253  * May also return an error if the user signalled nfs_wait_on_request().
 254  */
 255 static int nfs_page_mark_flush(struct page *page)
 256 {
 257         struct nfs_page *req;
 258         spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
 259         int ret;
 260
 261         spin_lock(req_lock);
 262         for(;;) {
 263                 req = nfs_page_find_request_locked(page);
 264                 if (req == NULL) {
 265                         spin_unlock(req_lock);
 266                         return 1;
 267                 }
 268                 if (nfs_lock_request_dontget(req))
 269                         break;
 270                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 271                  *       then the call to nfs_lock_request_dontget() will always
 272                  *       succeed provided that someone hasn't already marked the
 273                  *       request as dirty (in which case we don't care).
 274                  */
 275                 spin_unlock(req_lock);
 276                 ret = nfs_wait_on_request(req);
 277                 nfs_release_request(req);
 278                 if (ret != 0)
 279                         return ret;
 280                 spin_lock(req_lock);
 281         }
 282         spin_unlock(req_lock);
 283         if (nfs_set_page_writeback(page) == 0)
 284                 nfs_mark_request_dirty(req);
 285         ret = test_bit(PG_NEED_FLUSH, &req->wb_flags);
 286         nfs_unlock_request(req);
 287         return ret;
 288 }
 289
 290 /*
 291  * Write an mmapped page to the server.
 292  */
 293 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 294 {
 295         struct nfs_open_context *ctx;
 296         struct inode *inode = page->mapping->host;
 297         unsigned offset;
 298         int err;
 299
 300         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 301         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 302
 303         err = nfs_page_mark_flush(page);
 304         if (err <= 0)
 305                 goto out;
 306         err = 0;
 307         offset = nfs_page_length(page);
 308         if (!offset)
 309                 goto out;
 310
 311         ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
 312         if (ctx == NULL) {
 313                 err = -EBADF;
 314                 goto out;
 315         }
 316         err = nfs_writepage_setup(ctx, page, 0, offset);
 317         put_nfs_open_context(ctx);
 318         if (err != 0)
 319                 goto out;
 320         err = nfs_page_mark_flush(page);
 321         if (err > 0)
 322                 err = 0;
 323 out:
 324         if (!wbc->for_writepages)
 325                 nfs_flush_mapping(page->mapping, wbc, FLUSH_STABLE|wb_priority(wbc));
 326         return err;
 327 }
 328
 329 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 330 {
 331         int err;
 332
 333         err = nfs_writepage_locked(page, wbc);
 334         unlock_page(page);
 335         return err;
 336 }
 337
 338 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 339 {
 340         struct inode *inode = mapping->host;
 341         int err;
 342
 343         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 344
 345         err = generic_writepages(mapping, wbc);
 346         if (err)
 347                 return err;
 348         err = nfs_flush_mapping(mapping, wbc, wb_priority(wbc));
 349         if (err < 0)
 350                 goto out;
 351         nfs_add_stats(inode, NFSIOS_WRITEPAGES, err);
 352         err = 0;
 353 out:
 354         return err;
 355 }
 356
 357 /*
 358  * Insert a write request into an inode
 359  */
 360 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 361 {
 362         struct nfs_inode *nfsi = NFS_I(inode);
 363         int error;
 364
 365         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 366         BUG_ON(error == -EEXIST);
 367         if (error)
 368                 return error;
 369         if (!nfsi->npages) {
 370                 igrab(inode);
 371                 nfs_begin_data_update(inode);
 372                 if (nfs_have_delegation(inode, FMODE_WRITE))
 373                         nfsi->change_attr++;
 374         }
 375         SetPagePrivate(req->wb_page);
 376         set_page_private(req->wb_page, (unsigned long)req);
 377         nfsi->npages++;
 378         atomic_inc(&req->wb_count);
 379         return 0;
 380 }
 381
 382 /*
 383  * Remove a write request from an inode
 384  */
 385 static void nfs_inode_remove_request(struct nfs_page *req)
 386 {
 387         struct inode *inode = req->wb_context->dentry->d_inode;
 388         struct nfs_inode *nfsi = NFS_I(inode);
 389
 390         BUG_ON (!NFS_WBACK_BUSY(req));
 391
 392         spin_lock(&nfsi->req_lock);
 393         set_page_private(req->wb_page, 0);
 394         ClearPagePrivate(req->wb_page);
 395         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 396         nfsi->npages--;
 397         if (!nfsi->npages) {
 398                 spin_unlock(&nfsi->req_lock);
 399                 nfs_end_data_update(inode);
 400                 iput(inode);
 401         } else
 402                 spin_unlock(&nfsi->req_lock);
 403         nfs_clear_request(req);
 404         nfs_release_request(req);
 405 }
 406
 407 /*
 408  * Add a request to the inode's dirty list.
 409  */
 410 static void
 411 nfs_mark_request_dirty(struct nfs_page *req)
 412 {
 413         struct inode *inode = req->wb_context->dentry->d_inode;
 414         struct nfs_inode *nfsi = NFS_I(inode);
 415
 416         spin_lock(&nfsi->req_lock);
 417         radix_tree_tag_set(&nfsi->nfs_page_tree,
 418                         req->wb_index, NFS_PAGE_TAG_DIRTY);
 419         nfs_list_add_request(req, &nfsi->dirty);
 420         nfsi->ndirty++;
 421         spin_unlock(&nfsi->req_lock);
 422         __mark_inode_dirty(inode, I_DIRTY_PAGES);
 423 }
 424
 425 static void
 426 nfs_redirty_request(struct nfs_page *req)
 427 {
 428         __set_page_dirty_nobuffers(req->wb_page);
 429 }
 430
 431 /*
 432  * Check if a request is dirty
 433  */
 434 static inline int
 435 nfs_dirty_request(struct nfs_page *req)
 436 {
 437         struct page *page = req->wb_page;
 438
 439         if (page == NULL)
 440                 return 0;
 441         return !PageWriteback(req->wb_page);
 442 }
 443
 444 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 445 /*
 446  * Add a request to the inode's commit list.
 447  */
 448 static void
 449 nfs_mark_request_commit(struct nfs_page *req)
 450 {
 451         struct inode *inode = req->wb_context->dentry->d_inode;
 452         struct nfs_inode *nfsi = NFS_I(inode);
 453
 454         spin_lock(&nfsi->req_lock);
 455         nfs_list_add_request(req, &nfsi->commit);
 456         nfsi->ncommit++;
 457         spin_unlock(&nfsi->req_lock);
 458         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 459         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 460 }
 461 #endif
 462
 463 /*
 464  * Wait for a request to complete.
 465  *
 466  * Interruptible by signals only if mounted with intr flag.
 467  */
 468 static int nfs_wait_on_requests_locked(struct inode *inode, unsigned long idx_start, unsigned int npages)
 469 {
 470         struct nfs_inode *nfsi = NFS_I(inode);
 471         struct nfs_page *req;
 472         unsigned long           idx_end, next;
 473         unsigned int            res = 0;
 474         int                     error;
 475
 476         if (npages == 0)
 477                 idx_end = ~0;
 478         else
 479                 idx_end = idx_start + npages - 1;
 480
 481         next = idx_start;
 482         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
 483                 if (req->wb_index > idx_end)
 484                         break;
 485
 486                 next = req->wb_index + 1;
 487                 BUG_ON(!NFS_WBACK_BUSY(req));
 488
 489                 atomic_inc(&req->wb_count);
 490                 spin_unlock(&nfsi->req_lock);
 491                 error = nfs_wait_on_request(req);
 492                 nfs_release_request(req);
 493                 spin_lock(&nfsi->req_lock);
 494                 if (error < 0)
 495                         return error;
 496                 res++;
 497         }
 498         return res;
 499 }
 500
 501 static void nfs_cancel_dirty_list(struct list_head *head)
 502 {
 503         struct nfs_page *req;
 504         while(!list_empty(head)) {
 505                 req = nfs_list_entry(head->next);
 506                 nfs_list_remove_request(req);
 507                 nfs_end_page_writeback(req->wb_page);
 508                 nfs_inode_remove_request(req);
 509                 nfs_clear_page_writeback(req);
 510         }
 511 }
 512
 513 static void nfs_cancel_commit_list(struct list_head *head)
 514 {
 515         struct nfs_page *req;
 516
 517         while(!list_empty(head)) {
 518                 req = nfs_list_entry(head->next);
 519                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 520                 nfs_list_remove_request(req);
 521                 nfs_inode_remove_request(req);
 522                 nfs_unlock_request(req);
 523         }
 524 }
 525
 526 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 527 /*
 528  * nfs_scan_commit - Scan an inode for commit requests
 529  * @inode: NFS inode to scan
 530  * @dst: destination list
 531  * @idx_start: lower bound of page->index to scan.
 532  * @npages: idx_start + npages sets the upper bound to scan.
 533  *
 534  * Moves requests from the inode's 'commit' request list.
 535  * The requests are *not* checked to ensure that they form a contiguous set.
 536  */
 537 static int
 538 nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 539 {
 540         struct nfs_inode *nfsi = NFS_I(inode);
 541         int res = 0;
 542
 543         if (nfsi->ncommit != 0) {
 544                 res = nfs_scan_list(nfsi, &nfsi->commit, dst, idx_start, npages);
 545                 nfsi->ncommit -= res;
 546                 if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
 547                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
 548         }
 549         return res;
 550 }
 551 #else
 552 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 553 {
 554         return 0;
 555 }
 556 #endif
 557
 558 static int nfs_wait_on_write_congestion(struct address_space *mapping)
 559 {
 560         struct inode *inode = mapping->host;
 561         struct backing_dev_info *bdi = mapping->backing_dev_info;
 562         int ret = 0;
 563
 564         might_sleep();
 565
 566         if (!bdi_write_congested(bdi))
 567                 return 0;
 568
 569         nfs_inc_stats(inode, NFSIOS_CONGESTIONWAIT);
 570
 571         do {
 572                 struct rpc_clnt *clnt = NFS_CLIENT(inode);
 573                 sigset_t oldset;
 574
 575                 rpc_clnt_sigmask(clnt, &oldset);
 576                 ret = congestion_wait_interruptible(WRITE, HZ/10);
 577                 rpc_clnt_sigunmask(clnt, &oldset);
 578                 if (ret == -ERESTARTSYS)
 579                         break;
 580                 ret = 0;
 581         } while (bdi_write_congested(bdi));
 582
 583         return ret;
 584 }
 585
 586 /*
 587  * Try to update any existing write request, or create one if there is none.
 588  * In order to match, the request's credentials must match those of
 589  * the calling process.
 590  *
 591  * Note: Should always be called with the Page Lock held!
 592  */
 593 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 594                 struct page *page, unsigned int offset, unsigned int bytes)
 595 {
 596         struct address_space *mapping = page->mapping;
 597         struct inode *inode = mapping->host;
 598         struct nfs_inode *nfsi = NFS_I(inode);
 599         struct nfs_page         *req, *new = NULL;
 600         unsigned long           rqend, end;
 601
 602         end = offset + bytes;
 603
 604         if (nfs_wait_on_write_congestion(mapping))
 605                 return ERR_PTR(-ERESTARTSYS);
 606         for (;;) {
 607                 /* Loop over all inode entries and see if we find
 608                  * A request for the page we wish to update
 609                  */
 610                 spin_lock(&nfsi->req_lock);
 611                 req = nfs_page_find_request_locked(page);
 612                 if (req) {
 613                         if (!nfs_lock_request_dontget(req)) {
 614                                 int error;
 615
 616                                 spin_unlock(&nfsi->req_lock);
 617                                 error = nfs_wait_on_request(req);
 618                                 nfs_release_request(req);
 619                                 if (error < 0) {
 620                                         if (new)
 621                                                 nfs_release_request(new);
 622                                         return ERR_PTR(error);
 623                                 }
 624                                 continue;
 625                         }
 626                         spin_unlock(&nfsi->req_lock);
 627                         if (new)
 628                                 nfs_release_request(new);
 629                         break;
 630                 }
 631
 632                 if (new) {
 633                         int error;
 634                         nfs_lock_request_dontget(new);
 635                         error = nfs_inode_add_request(inode, new);
 636                         if (error) {
 637                                 spin_unlock(&nfsi->req_lock);
 638                                 nfs_unlock_request(new);
 639                                 return ERR_PTR(error);
 640                         }
 641                         spin_unlock(&nfsi->req_lock);
 642                         return new;
 643                 }
 644                 spin_unlock(&nfsi->req_lock);
 645
 646                 new = nfs_create_request(ctx, inode, page, offset, bytes);
 647                 if (IS_ERR(new))
 648                         return new;
 649         }
 650
 651         /* We have a request for our page.
 652          * If the creds don't match, or the
 653          * page addresses don't match,
 654          * tell the caller to wait on the conflicting
 655          * request.
 656          */
 657         rqend = req->wb_offset + req->wb_bytes;
 658         if (req->wb_context != ctx
 659             || req->wb_page != page
 660             || !nfs_dirty_request(req)
 661             || offset > rqend || end < req->wb_offset) {
 662                 nfs_unlock_request(req);
 663                 return ERR_PTR(-EBUSY);
 664         }
 665
 666         /* Okay, the request matches. Update the region */
 667         if (offset < req->wb_offset) {
 668                 req->wb_offset = offset;
 669                 req->wb_pgbase = offset;
 670                 req->wb_bytes = rqend - req->wb_offset;
 671         }
 672
 673         if (end > rqend)
 674                 req->wb_bytes = end - req->wb_offset;
 675
 676         return req;
 677 }
 678
 679 int nfs_flush_incompatible(struct file *file, struct page *page)
 680 {
 681         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 682         struct nfs_page *req;
 683         int do_flush, status;
 684         /*
 685          * Look for a request corresponding to this page. If there
 686          * is one, and it belongs to another file, we flush it out
 687          * before we try to copy anything into the page. Do this
 688          * due to the lack of an ACCESS-type call in NFSv2.
 689          * Also do the same if we find a request from an existing
 690          * dropped page.
 691          */
 692         do {
 693                 req = nfs_page_find_request(page);
 694                 if (req == NULL)
 695                         return 0;
 696                 do_flush = req->wb_page != page || req->wb_context != ctx
 697                         || !nfs_dirty_request(req);
 698                 nfs_release_request(req);
 699                 if (!do_flush)
 700                         return 0;
 701                 status = nfs_wb_page(page->mapping->host, page);
 702         } while (status == 0);
 703         return status;
 704 }
 705
 706 /*
 707  * Update and possibly write a cached page of an NFS file.
 708  *
 709  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 710  * things with a page scheduled for an RPC call (e.g. invalidate it).
 711  */
 712 int nfs_updatepage(struct file *file, struct page *page,
 713                 unsigned int offset, unsigned int count)
 714 {
 715         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 716         struct inode    *inode = page->mapping->host;
 717         int             status = 0;
 718
 719         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 720
 721         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
 722                 file->f_path.dentry->d_parent->d_name.name,
 723                 file->f_path.dentry->d_name.name, count,
 724                 (long long)(page_offset(page) +offset));
 725
 726         /* If we're not using byte range locks, and we know the page
 727          * is entirely in cache, it may be more efficient to avoid
 728          * fragmenting write requests.
 729          */
 730         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
 731                 count = max(count + offset, nfs_page_length(page));
 732                 offset = 0;
 733         }
 734
 735         status = nfs_writepage_setup(ctx, page, offset, count);
 736         __set_page_dirty_nobuffers(page);
 737
 738         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
 739                         status, (long long)i_size_read(inode));
 740         if (status < 0)
 741                 nfs_set_pageerror(page);
 742         return status;
 743 }
 744
 745 static void nfs_writepage_release(struct nfs_page *req)
 746 {
 747         nfs_end_page_writeback(req->wb_page);
 748
 749 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 750         if (!PageError(req->wb_page)) {
 751                 if (NFS_NEED_RESCHED(req)) {
 752                         nfs_redirty_request(req);
 753                         goto out;
 754                 } else if (NFS_NEED_COMMIT(req)) {
 755                         nfs_mark_request_commit(req);
 756                         goto out;
 757                 }
 758         }
 759         nfs_inode_remove_request(req);
 760
 761 out:
 762         nfs_clear_commit(req);
 763         nfs_clear_reschedule(req);
 764 #else
 765         nfs_inode_remove_request(req);
 766 #endif
 767         nfs_clear_page_writeback(req);
 768 }
 769
 770 static inline int flush_task_priority(int how)
 771 {
 772         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 773                 case FLUSH_HIGHPRI:
 774                         return RPC_PRIORITY_HIGH;
 775                 case FLUSH_LOWPRI:
 776                         return RPC_PRIORITY_LOW;
 777         }
 778         return RPC_PRIORITY_NORMAL;
 779 }
 780
 781 /*
 782  * Set up the argument/result storage required for the RPC call.
 783  */
 784 static void nfs_write_rpcsetup(struct nfs_page *req,
 785                 struct nfs_write_data *data,
 786                 const struct rpc_call_ops *call_ops,
 787                 unsigned int count, unsigned int offset,
 788                 int how)
 789 {
 790         struct inode            *inode;
 791         int flags;
 792
 793         /* Set up the RPC argument and reply structs
 794          * NB: take care not to mess about with data->commit et al. */
 795
 796         data->req = req;
 797         data->inode = inode = req->wb_context->dentry->d_inode;
 798         data->cred = req->wb_context->cred;
 799
 800         data->args.fh     = NFS_FH(inode);
 801         data->args.offset = req_offset(req) + offset;
 802         data->args.pgbase = req->wb_pgbase + offset;
 803         data->args.pages  = data->pagevec;
 804         data->args.count  = count;
 805         data->args.context = req->wb_context;
 806
 807         data->res.fattr   = &data->fattr;
 808         data->res.count   = count;
 809         data->res.verf    = &data->verf;
 810         nfs_fattr_init(&data->fattr);
 811
 812         /* Set up the initial task struct.  */
 813         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 814         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
 815         NFS_PROTO(inode)->write_setup(data, how);
 816
 817         data->task.tk_priority = flush_task_priority(how);
 818         data->task.tk_cookie = (unsigned long)inode;
 819
 820         dprintk("NFS: %5u initiated write call "
 821                 "(req %s/%Ld, %u bytes @ offset %Lu)\n",
 822                 data->task.tk_pid,
 823                 inode->i_sb->s_id,
 824                 (long long)NFS_FILEID(inode),
 825                 count,
 826                 (unsigned long long)data->args.offset);
 827 }
 828
 829 static void nfs_execute_write(struct nfs_write_data *data)
 830 {
 831         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
 832         sigset_t oldset;
 833
 834         rpc_clnt_sigmask(clnt, &oldset);
 835         rpc_execute(&data->task);
 836         rpc_clnt_sigunmask(clnt, &oldset);
 837 }
 838
 839 /*
 840  * Generate multiple small requests to write out a single
 841  * contiguous dirty area on one page.
 842  */
 843 static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
 844 {
 845         struct nfs_page *req = nfs_list_entry(head->next);
 846         struct page *page = req->wb_page;
 847         struct nfs_write_data *data;
 848         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 849         unsigned int offset;
 850         int requests = 0;
 851         LIST_HEAD(list);
 852
 853         nfs_list_remove_request(req);
 854
 855         nbytes = req->wb_bytes;
 856         do {
 857                 size_t len = min(nbytes, wsize);
 858
 859                 data = nfs_writedata_alloc(len);
 860                 if (!data)
 861                         goto out_bad;
 862                 list_add(&data->pages, &list);
 863                 requests++;
 864                 nbytes -= len;
 865         } while (nbytes != 0);
 866         atomic_set(&req->wb_complete, requests);
 867
 868         ClearPageError(page);
 869         offset = 0;
 870         nbytes = req->wb_bytes;
 871         do {
 872                 data = list_entry(list.next, struct nfs_write_data, pages);
 873                 list_del_init(&data->pages);
 874
 875                 data->pagevec[0] = page;
 876
 877                 if (nbytes > wsize) {
 878                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 879                                         wsize, offset, how);
 880                         offset += wsize;
 881                         nbytes -= wsize;
 882                 } else {
 883                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 884                                         nbytes, offset, how);
 885                         nbytes = 0;
 886                 }
 887                 nfs_execute_write(data);
 888         } while (nbytes != 0);
 889
 890         return 0;
 891
 892 out_bad:
 893         while (!list_empty(&list)) {
 894                 data = list_entry(list.next, struct nfs_write_data, pages);
 895                 list_del(&data->pages);
 896                 nfs_writedata_release(data);
 897         }
 898         nfs_end_page_writeback(req->wb_page);
 899         nfs_redirty_request(req);
 900         nfs_clear_page_writeback(req);
 901         return -ENOMEM;
 902 }
 903
 904 /*
 905  * Create an RPC task for the given write request and kick it.
 906  * The page must have been locked by the caller.
 907  *
 908  * It may happen that the page we're passed is not marked dirty.
 909  * This is the case if nfs_updatepage detects a conflicting request
 910  * that has been written but not committed.
 911  */
 912 static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
 913 {
 914         struct nfs_page         *req;
 915         struct page             **pages;
 916         struct nfs_write_data   *data;
 917         unsigned int            count;
 918
 919         data = nfs_writedata_alloc(NFS_SERVER(inode)->wsize);
 920         if (!data)
 921                 goto out_bad;
 922
 923         pages = data->pagevec;
 924         count = 0;
 925         while (!list_empty(head)) {
 926                 req = nfs_list_entry(head->next);
 927                 nfs_list_remove_request(req);
 928                 nfs_list_add_request(req, &data->pages);
 929                 ClearPageError(req->wb_page);
 930                 *pages++ = req->wb_page;
 931                 count += req->wb_bytes;
 932         }
 933         req = nfs_list_entry(data->pages.next);
 934
 935         /* Set up the argument struct */
 936         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 937
 938         nfs_execute_write(data);
 939         return 0;
 940  out_bad:
 941         while (!list_empty(head)) {
 942                 struct nfs_page *req = nfs_list_entry(head->next);
 943                 nfs_list_remove_request(req);
 944                 nfs_end_page_writeback(req->wb_page);
 945                 nfs_redirty_request(req);
 946                 nfs_clear_page_writeback(req);
 947         }
 948         return -ENOMEM;
 949 }
 950
 951 static int nfs_flush_list(struct inode *inode, struct list_head *head, int npages, int how)
 952 {
 953         LIST_HEAD(one_request);
 954         int (*flush_one)(struct inode *, struct list_head *, int);
 955         struct nfs_page *req;
 956         int wpages = NFS_SERVER(inode)->wpages;
 957         int wsize = NFS_SERVER(inode)->wsize;
 958         int error;
 959
 960         flush_one = nfs_flush_one;
 961         if (wsize < PAGE_CACHE_SIZE)
 962                 flush_one = nfs_flush_multi;
 963         /* For single writes, FLUSH_STABLE is more efficient */
 964         if (npages <= wpages && npages == NFS_I(inode)->npages
 965                         && nfs_list_entry(head->next)->wb_bytes <= wsize)
 966                 how |= FLUSH_STABLE;
 967
 968         do {
 969                 nfs_coalesce_requests(head, &one_request, wpages);
 970                 req = nfs_list_entry(one_request.next);
 971                 error = flush_one(inode, &one_request, how);
 972                 if (error < 0)
 973                         goto out_err;
 974         } while (!list_empty(head));
 975         return 0;
 976 out_err:
 977         while (!list_empty(head)) {
 978                 req = nfs_list_entry(head->next);
 979                 nfs_list_remove_request(req);
 980                 nfs_end_page_writeback(req->wb_page);
 981                 nfs_redirty_request(req);
 982                 nfs_clear_page_writeback(req);
 983         }
 984         return error;
 985 }
 986
 987 /*
 988  * Handle a write reply that flushed part of a page.
 989  */
 990 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
 991 {
 992         struct nfs_write_data   *data = calldata;
 993         struct nfs_page         *req = data->req;
 994         struct page             *page = req->wb_page;
 995
 996         dprintk("NFS: write (%s/%Ld %d@%Ld)",
 997                 req->wb_context->dentry->d_inode->i_sb->s_id,
 998                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
 999                 req->wb_bytes,
1000                 (long long)req_offset(req));
1001
1002         if (nfs_writeback_done(task, data) != 0)
1003                 return;
1004
1005         if (task->tk_status < 0) {
1006                 nfs_set_pageerror(page);
1007                 req->wb_context->error = task->tk_status;
1008                 dprintk(", error = %d\n", task->tk_status);
1009         } else {
1010 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1011                 if (data->verf.committed < NFS_FILE_SYNC) {
1012                         if (!NFS_NEED_COMMIT(req)) {
1013                                 nfs_defer_commit(req);
1014                                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1015                                 dprintk(" defer commit\n");
1016                         } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1017                                 nfs_defer_reschedule(req);
1018                                 dprintk(" server reboot detected\n");
1019                         }
1020                 } else
1021 #endif
1022                         dprintk(" OK\n");
1023         }
1024
1025         if (atomic_dec_and_test(&req->wb_complete))
1026                 nfs_writepage_release(req);
1027 }
1028
1029 static const struct rpc_call_ops nfs_write_partial_ops = {
1030         .rpc_call_done = nfs_writeback_done_partial,
1031         .rpc_release = nfs_writedata_release,
1032 };
1033
1034 /*
1035  * Handle a write reply that flushes a whole page.
1036  *
1037  * FIXME: There is an inherent race with invalidate_inode_pages and
1038  *        writebacks since the page->count is kept > 1 for as long
1039  *        as the page has a write request pending.
1040  */
1041 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1042 {
1043         struct nfs_write_data   *data = calldata;
1044         struct nfs_page         *req;
1045         struct page             *page;
1046
1047         if (nfs_writeback_done(task, data) != 0)
1048                 return;
1049
1050         /* Update attributes as result of writeback. */
1051         while (!list_empty(&data->pages)) {
1052                 req = nfs_list_entry(data->pages.next);
1053                 nfs_list_remove_request(req);
1054                 page = req->wb_page;
1055
1056                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1057                         req->wb_context->dentry->d_inode->i_sb->s_id,
1058                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1059                         req->wb_bytes,
1060                         (long long)req_offset(req));
1061
1062                 if (task->tk_status < 0) {
1063                         nfs_set_pageerror(page);
1064                         req->wb_context->error = task->tk_status;
1065                         nfs_end_page_writeback(page);
1066                         nfs_inode_remove_request(req);
1067                         dprintk(", error = %d\n", task->tk_status);
1068                         goto next;
1069                 }
1070                 nfs_end_page_writeback(page);
1071
1072 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1073                 if (data->args.stable != NFS_UNSTABLE || data->verf.committed == NFS_FILE_SYNC) {
1074                         nfs_inode_remove_request(req);
1075                         dprintk(" OK\n");
1076                         goto next;
1077                 }
1078                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1079                 nfs_mark_request_commit(req);
1080                 dprintk(" marked for commit\n");
1081 #else
1082                 nfs_inode_remove_request(req);
1083 #endif
1084         next:
1085                 nfs_clear_page_writeback(req);
1086         }
1087 }
1088
1089 static const struct rpc_call_ops nfs_write_full_ops = {
1090         .rpc_call_done = nfs_writeback_done_full,
1091         .rpc_release = nfs_writedata_release,
1092 };
1093
1094
1095 /*
1096  * This function is called when the WRITE call is complete.
1097  */
1098 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1099 {
1100         struct nfs_writeargs    *argp = &data->args;
1101         struct nfs_writeres     *resp = &data->res;
1102         int status;
1103
1104         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1105                 task->tk_pid, task->tk_status);
1106
1107         /*
1108          * ->write_done will attempt to use post-op attributes to detect
1109          * conflicting writes by other clients.  A strict interpretation
1110          * of close-to-open would allow us to continue caching even if
1111          * another writer had changed the file, but some applications
1112          * depend on tighter cache coherency when writing.
1113          */
1114         status = NFS_PROTO(data->inode)->write_done(task, data);
1115         if (status != 0)
1116                 return status;
1117         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1118
1119 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1120         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1121                 /* We tried a write call, but the server did not
1122                  * commit data to stable storage even though we
1123                  * requested it.
1124                  * Note: There is a known bug in Tru64 < 5.0 in which
1125                  *       the server reports NFS_DATA_SYNC, but performs
1126                  *       NFS_FILE_SYNC. We therefore implement this checking
1127                  *       as a dprintk() in order to avoid filling syslog.
1128                  */
1129                 static unsigned long    complain;
1130
1131                 if (time_before(complain, jiffies)) {
1132                         dprintk("NFS: faulty NFS server %s:"
1133                                 " (committed = %d) != (stable = %d)\n",
1134                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1135                                 resp->verf->committed, argp->stable);
1136                         complain = jiffies + 300 * HZ;
1137                 }
1138         }
1139 #endif
1140         /* Is this a short write? */
1141         if (task->tk_status >= 0 && resp->count < argp->count) {
1142                 static unsigned long    complain;
1143
1144                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1145
1146                 /* Has the server at least made some progress? */
1147                 if (resp->count != 0) {
1148                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1149                         if (resp->verf->committed != NFS_UNSTABLE) {
1150                                 /* Resend from where the server left off */
1151                                 argp->offset += resp->count;
1152                                 argp->pgbase += resp->count;
1153                                 argp->count -= resp->count;
1154                         } else {
1155                                 /* Resend as a stable write in order to avoid
1156                                  * headaches in the case of a server crash.
1157                                  */
1158                                 argp->stable = NFS_FILE_SYNC;
1159                         }
1160                         rpc_restart_call(task);
1161                         return -EAGAIN;
1162                 }
1163                 if (time_before(complain, jiffies)) {
1164                         printk(KERN_WARNING
1165                                "NFS: Server wrote zero bytes, expected %u.\n",
1166                                         argp->count);
1167                         complain = jiffies + 300 * HZ;
1168                 }
1169                 /* Can't do anything about it except throw an error. */
1170                 task->tk_status = -EIO;
1171         }
1172         return 0;
1173 }
1174
1175
1176 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1177 void nfs_commit_release(void *wdata)
1178 {
1179         nfs_commit_free(wdata);
1180 }
1181
1182 /*
1183  * Set up the argument/result storage required for the RPC call.
1184  */
1185 static void nfs_commit_rpcsetup(struct list_head *head,
1186                 struct nfs_write_data *data,
1187                 int how)
1188 {
1189         struct nfs_page         *first;
1190         struct inode            *inode;
1191         int flags;
1192
1193         /* Set up the RPC argument and reply structs
1194          * NB: take care not to mess about with data->commit et al. */
1195
1196         list_splice_init(head, &data->pages);
1197         first = nfs_list_entry(data->pages.next);
1198         inode = first->wb_context->dentry->d_inode;
1199
1200         data->inode       = inode;
1201         data->cred        = first->wb_context->cred;
1202
1203         data->args.fh     = NFS_FH(data->inode);
1204         /* Note: we always request a commit of the entire inode */
1205         data->args.offset = 0;
1206         data->args.count  = 0;
1207         data->res.count   = 0;
1208         data->res.fattr   = &data->fattr;
1209         data->res.verf    = &data->verf;
1210         nfs_fattr_init(&data->fattr);
1211
1212         /* Set up the initial task struct.  */
1213         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1214         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1215         NFS_PROTO(inode)->commit_setup(data, how);
1216
1217         data->task.tk_priority = flush_task_priority(how);
1218         data->task.tk_cookie = (unsigned long)inode;
1219
1220         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1221 }
1222
1223 /*
1224  * Commit dirty pages
1225  */
1226 static int
1227 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1228 {
1229         struct nfs_write_data   *data;
1230         struct nfs_page         *req;
1231
1232         data = nfs_commit_alloc();
1233
1234         if (!data)
1235                 goto out_bad;
1236
1237         /* Set up the argument struct */
1238         nfs_commit_rpcsetup(head, data, how);
1239
1240         nfs_execute_write(data);
1241         return 0;
1242  out_bad:
1243         while (!list_empty(head)) {
1244                 req = nfs_list_entry(head->next);
1245                 nfs_list_remove_request(req);
1246                 nfs_mark_request_commit(req);
1247                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1248                 nfs_clear_page_writeback(req);
1249         }
1250         return -ENOMEM;
1251 }
1252
1253 /*
1254  * COMMIT call returned
1255  */
1256 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1257 {
1258         struct nfs_write_data   *data = calldata;
1259         struct nfs_page         *req;
1260
1261         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1262                                 task->tk_pid, task->tk_status);
1263
1264         /* Call the NFS version-specific code */
1265         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1266                 return;
1267
1268         while (!list_empty(&data->pages)) {
1269                 req = nfs_list_entry(data->pages.next);
1270                 nfs_list_remove_request(req);
1271                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1272
1273                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1274                         req->wb_context->dentry->d_inode->i_sb->s_id,
1275                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1276                         req->wb_bytes,
1277                         (long long)req_offset(req));
1278                 if (task->tk_status < 0) {
1279                         req->wb_context->error = task->tk_status;
1280                         nfs_inode_remove_request(req);
1281                         dprintk(", error = %d\n", task->tk_status);
1282                         goto next;
1283                 }
1284
1285                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1286                  * returned by the server against all stored verfs. */
1287                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1288                         /* We have a match */
1289                         nfs_inode_remove_request(req);
1290                         dprintk(" OK\n");
1291                         goto next;
1292                 }
1293                 /* We have a mismatch. Write the page again */
1294                 dprintk(" mismatch\n");
1295                 nfs_redirty_request(req);
1296         next:
1297                 nfs_clear_page_writeback(req);
1298         }
1299 }
1300
1301 static const struct rpc_call_ops nfs_commit_ops = {
1302         .rpc_call_done = nfs_commit_done,
1303         .rpc_release = nfs_commit_release,
1304 };
1305 #else
1306 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1307 {
1308         return 0;
1309 }
1310 #endif
1311
1312 static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1313 {
1314         struct nfs_inode *nfsi = NFS_I(mapping->host);
1315         LIST_HEAD(head);
1316         long res;
1317
1318         spin_lock(&nfsi->req_lock);
1319         res = nfs_scan_dirty(mapping, wbc, &head);
1320         spin_unlock(&nfsi->req_lock);
1321         if (res) {
1322                 int error = nfs_flush_list(mapping->host, &head, res, how);
1323                 if (error < 0)
1324                         return error;
1325         }
1326         return res;
1327 }
1328
1329 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1330 int nfs_commit_inode(struct inode *inode, int how)
1331 {
1332         struct nfs_inode *nfsi = NFS_I(inode);
1333         LIST_HEAD(head);
1334         int res;
1335
1336         spin_lock(&nfsi->req_lock);
1337         res = nfs_scan_commit(inode, &head, 0, 0);
1338         spin_unlock(&nfsi->req_lock);
1339         if (res) {
1340                 int error = nfs_commit_list(inode, &head, how);
1341                 if (error < 0)
1342                         return error;
1343         }
1344         return res;
1345 }
1346 #endif
1347
1348 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1349 {
1350         struct inode *inode = mapping->host;
1351         struct nfs_inode *nfsi = NFS_I(inode);
1352         unsigned long idx_start, idx_end;
1353         unsigned int npages = 0;
1354         LIST_HEAD(head);
1355         int nocommit = how & FLUSH_NOCOMMIT;
1356         long pages, ret;
1357
1358         /* FIXME */
1359         if (wbc->range_cyclic)
1360                 idx_start = 0;
1361         else {
1362                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1363                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1364                 if (idx_end > idx_start) {
1365                         unsigned long l_npages = 1 + idx_end - idx_start;
1366                         npages = l_npages;
1367                         if (sizeof(npages) != sizeof(l_npages) &&
1368                                         (unsigned long)npages != l_npages)
1369                                 npages = 0;
1370                 }
1371         }
1372         how &= ~FLUSH_NOCOMMIT;
1373         spin_lock(&nfsi->req_lock);
1374         do {
1375                 wbc->pages_skipped = 0;
1376                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1377                 if (ret != 0)
1378                         continue;
1379                 pages = nfs_scan_dirty(mapping, wbc, &head);
1380                 if (pages != 0) {
1381                         spin_unlock(&nfsi->req_lock);
1382                         if (how & FLUSH_INVALIDATE) {
1383                                 nfs_cancel_dirty_list(&head);
1384                                 ret = pages;
1385                         } else
1386                                 ret = nfs_flush_list(inode, &head, pages, how);
1387                         spin_lock(&nfsi->req_lock);
1388                         continue;
1389                 }
1390                 if (wbc->pages_skipped != 0)
1391                         continue;
1392                 if (nocommit)
1393                         break;
1394                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1395                 if (pages == 0) {
1396                         if (wbc->pages_skipped != 0)
1397                                 continue;
1398                         break;
1399                 }
1400                 if (how & FLUSH_INVALIDATE) {
1401                         spin_unlock(&nfsi->req_lock);
1402                         nfs_cancel_commit_list(&head);
1403                         ret = pages;
1404                         spin_lock(&nfsi->req_lock);
1405                         continue;
1406                 }
1407                 pages += nfs_scan_commit(inode, &head, 0, 0);
1408                 spin_unlock(&nfsi->req_lock);
1409                 ret = nfs_commit_list(inode, &head, how);
1410                 spin_lock(&nfsi->req_lock);
1411         } while (ret >= 0);
1412         spin_unlock(&nfsi->req_lock);
1413         return ret;
1414 }
1415
1416 /*
1417  * flush the inode to disk.
1418  */
1419 int nfs_wb_all(struct inode *inode)
1420 {
1421         struct address_space *mapping = inode->i_mapping;
1422         struct writeback_control wbc = {
1423                 .bdi = mapping->backing_dev_info,
1424                 .sync_mode = WB_SYNC_ALL,
1425                 .nr_to_write = LONG_MAX,
1426                 .for_writepages = 1,
1427                 .range_cyclic = 1,
1428         };
1429         int ret;
1430
1431         ret = generic_writepages(mapping, &wbc);
1432         if (ret < 0)
1433                 goto out;
1434         ret = nfs_sync_mapping_wait(mapping, &wbc, 0);
1435         if (ret >= 0)
1436                 return 0;
1437 out:
1438         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1439         return ret;
1440 }
1441
1442 int nfs_sync_mapping_range(struct address_space *mapping, loff_t range_start, loff_t range_end, int how)
1443 {
1444         struct writeback_control wbc = {
1445                 .bdi = 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                 .for_writepages = 1,
1451         };
1452         int ret;
1453
1454         if (!(how & FLUSH_NOWRITEPAGE)) {
1455                 ret = generic_writepages(mapping, &wbc);
1456                 if (ret < 0)
1457                         goto out;
1458         }
1459         ret = nfs_sync_mapping_wait(mapping, &wbc, how);
1460         if (ret >= 0)
1461                 return 0;
1462 out:
1463         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1464         return ret;
1465 }
1466
1467 int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)
1468 {
1469         loff_t range_start = page_offset(page);
1470         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1471         struct writeback_control wbc = {
1472                 .bdi = page->mapping->backing_dev_info,
1473                 .sync_mode = WB_SYNC_ALL,
1474                 .nr_to_write = LONG_MAX,
1475                 .range_start = range_start,
1476                 .range_end = range_end,
1477         };
1478         int ret;
1479
1480         BUG_ON(!PageLocked(page));
1481         if (!(how & FLUSH_NOWRITEPAGE) && clear_page_dirty_for_io(page)) {
1482                 ret = nfs_writepage_locked(page, &wbc);
1483                 if (ret < 0)
1484                         goto out;
1485         }
1486         if (!PagePrivate(page))
1487                 return 0;
1488         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1489         if (ret >= 0)
1490                 return 0;
1491 out:
1492         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1493         return ret;
1494 }
1495
1496 /*
1497  * Write back all requests on one page - we do this before reading it.
1498  */
1499 int nfs_wb_page(struct inode *inode, struct page* page)
1500 {
1501         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1502 }
1503
1504 int nfs_set_page_dirty(struct page *page)
1505 {
1506         struct nfs_page *req;
1507
1508         req = nfs_page_find_request(page);
1509         if (req != NULL) {
1510                 /* Mark any existing write requests for flushing */
1511                 set_bit(PG_NEED_FLUSH, &req->wb_flags);
1512                 nfs_release_request(req);
1513         }
1514         return __set_page_dirty_nobuffers(page);
1515 }
1516
1517
1518 int __init nfs_init_writepagecache(void)
1519 {
1520         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1521                                              sizeof(struct nfs_write_data),
1522                                              0, SLAB_HWCACHE_ALIGN,
1523                                              NULL, NULL);
1524         if (nfs_wdata_cachep == NULL)
1525                 return -ENOMEM;
1526
1527         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1528                                                      nfs_wdata_cachep);
1529         if (nfs_wdata_mempool == NULL)
1530                 return -ENOMEM;
1531
1532         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1533                                                       nfs_wdata_cachep);
1534         if (nfs_commit_mempool == NULL)
1535                 return -ENOMEM;
1536
1537         /*
1538          * NFS congestion size, scale with available memory.
1539          *
1540          *  64MB:    8192k
1541          * 128MB:   11585k
1542          * 256MB:   16384k
1543          * 512MB:   23170k
1544          *   1GB:   32768k
1545          *   2GB:   46340k
1546          *   4GB:   65536k
1547          *   8GB:   92681k
1548          *  16GB:  131072k
1549          *
1550          * This allows larger machines to have larger/more transfers.
1551          * Limit the default to 256M
1552          */
1553         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1554         if (nfs_congestion_kb > 256*1024)
1555                 nfs_congestion_kb = 256*1024;
1556
1557         return 0;
1558 }
1559
1560 void nfs_destroy_writepagecache(void)
1561 {
1562         mempool_destroy(nfs_commit_mempool);
1563         mempool_destroy(nfs_wdata_mempool);
1564         kmem_cache_destroy(nfs_wdata_cachep);
1565 }
1566