git.oblomov.eu Git - linux-2.6/blob - 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 void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc,
  38                                   struct inode *inode, int ioflags);
  39 static void nfs_redirty_request(struct nfs_page *req);
  40 static const struct rpc_call_ops nfs_write_partial_ops;
  41 static const struct rpc_call_ops nfs_write_full_ops;
  42 static const struct rpc_call_ops nfs_commit_ops;
  43
  44 static struct kmem_cache *nfs_wdata_cachep;
  45 static mempool_t *nfs_wdata_mempool;
  46 static mempool_t *nfs_commit_mempool;
  47
  48 struct nfs_write_data *nfs_commitdata_alloc(void)
  49 {
  50         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
  51
  52         if (p) {
  53                 memset(p, 0, sizeof(*p));
  54                 INIT_LIST_HEAD(&p->pages);
  55         }
  56         return p;
  57 }
  58
  59 void nfs_commit_free(struct nfs_write_data *p)
  60 {
  61         if (p && (p->pagevec != &p->page_array[0]))
  62                 kfree(p->pagevec);
  63         mempool_free(p, nfs_commit_mempool);
  64 }
  65
  66 struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
  67 {
  68         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
  69
  70         if (p) {
  71                 memset(p, 0, sizeof(*p));
  72                 INIT_LIST_HEAD(&p->pages);
  73                 p->npages = pagecount;
  74                 if (pagecount <= ARRAY_SIZE(p->page_array))
  75                         p->pagevec = p->page_array;
  76                 else {
  77                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
  78                         if (!p->pagevec) {
  79                                 mempool_free(p, nfs_wdata_mempool);
  80                                 p = NULL;
  81                         }
  82                 }
  83         }
  84         return p;
  85 }
  86
  87 static void nfs_writedata_free(struct nfs_write_data *p)
  88 {
  89         if (p && (p->pagevec != &p->page_array[0]))
  90                 kfree(p->pagevec);
  91         mempool_free(p, nfs_wdata_mempool);
  92 }
  93
  94 void nfs_writedata_release(void *data)
  95 {
  96         struct nfs_write_data *wdata = data;
  97
  98         put_nfs_open_context(wdata->args.context);
  99         nfs_writedata_free(wdata);
 100 }
 101
 102 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 103 {
 104         ctx->error = error;
 105         smp_wmb();
 106         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 107 }
 108
 109 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 110 {
 111         struct nfs_page *req = NULL;
 112
 113         if (PagePrivate(page)) {
 114                 req = (struct nfs_page *)page_private(page);
 115                 if (req != NULL)
 116                         kref_get(&req->wb_kref);
 117         }
 118         return req;
 119 }
 120
 121 static struct nfs_page *nfs_page_find_request(struct page *page)
 122 {
 123         struct inode *inode = page->mapping->host;
 124         struct nfs_page *req = NULL;
 125
 126         spin_lock(&inode->i_lock);
 127         req = nfs_page_find_request_locked(page);
 128         spin_unlock(&inode->i_lock);
 129         return req;
 130 }
 131
 132 /* Adjust the file length if we're writing beyond the end */
 133 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 134 {
 135         struct inode *inode = page->mapping->host;
 136         loff_t end, i_size;
 137         pgoff_t end_index;
 138
 139         spin_lock(&inode->i_lock);
 140         i_size = i_size_read(inode);
 141         end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 142         if (i_size > 0 && page->index < end_index)
 143                 goto out;
 144         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 145         if (i_size >= end)
 146                 goto out;
 147         i_size_write(inode, end);
 148         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 149 out:
 150         spin_unlock(&inode->i_lock);
 151 }
 152
 153 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 154 static void nfs_set_pageerror(struct page *page)
 155 {
 156         SetPageError(page);
 157         nfs_zap_mapping(page->mapping->host, page->mapping);
 158 }
 159
 160 /* We can set the PG_uptodate flag if we see that a write request
 161  * covers the full page.
 162  */
 163 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 164 {
 165         if (PageUptodate(page))
 166                 return;
 167         if (base != 0)
 168                 return;
 169         if (count != nfs_page_length(page))
 170                 return;
 171         SetPageUptodate(page);
 172 }
 173
 174 static int wb_priority(struct writeback_control *wbc)
 175 {
 176         if (wbc->for_reclaim)
 177                 return FLUSH_HIGHPRI | FLUSH_STABLE;
 178         if (wbc->for_kupdate)
 179                 return FLUSH_LOWPRI;
 180         return 0;
 181 }
 182
 183 /*
 184  * NFS congestion control
 185  */
 186
 187 int nfs_congestion_kb;
 188
 189 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 190 #define NFS_CONGESTION_OFF_THRESH       \
 191         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 192
 193 static int nfs_set_page_writeback(struct page *page)
 194 {
 195         int ret = test_set_page_writeback(page);
 196
 197         if (!ret) {
 198                 struct inode *inode = page->mapping->host;
 199                 struct nfs_server *nfss = NFS_SERVER(inode);
 200
 201                 if (atomic_long_inc_return(&nfss->writeback) >
 202                                 NFS_CONGESTION_ON_THRESH)
 203                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
 204         }
 205         return ret;
 206 }
 207
 208 static void nfs_end_page_writeback(struct page *page)
 209 {
 210         struct inode *inode = page->mapping->host;
 211         struct nfs_server *nfss = NFS_SERVER(inode);
 212
 213         end_page_writeback(page);
 214         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 215                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
 216 }
 217
 218 /*
 219  * Find an associated nfs write request, and prepare to flush it out
 220  * May return an error if the user signalled nfs_wait_on_request().
 221  */
 222 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 223                                 struct page *page)
 224 {
 225         struct inode *inode = page->mapping->host;
 226         struct nfs_page *req;
 227         int ret;
 228
 229         spin_lock(&inode->i_lock);
 230         for(;;) {
 231                 req = nfs_page_find_request_locked(page);
 232                 if (req == NULL) {
 233                         spin_unlock(&inode->i_lock);
 234                         return 0;
 235                 }
 236                 if (nfs_set_page_tag_locked(req))
 237                         break;
 238                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 239                  *       then the call to nfs_set_page_tag_locked() will always
 240                  *       succeed provided that someone hasn't already marked the
 241                  *       request as dirty (in which case we don't care).
 242                  */
 243                 spin_unlock(&inode->i_lock);
 244                 ret = nfs_wait_on_request(req);
 245                 nfs_release_request(req);
 246                 if (ret != 0)
 247                         return ret;
 248                 spin_lock(&inode->i_lock);
 249         }
 250         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 251                 spin_unlock(&inode->i_lock);
 252                 BUG();
 253         }
 254         if (nfs_set_page_writeback(page) != 0) {
 255                 spin_unlock(&inode->i_lock);
 256                 BUG();
 257         }
 258         spin_unlock(&inode->i_lock);
 259         if (!nfs_pageio_add_request(pgio, req)) {
 260                 nfs_redirty_request(req);
 261                 return pgio->pg_error;
 262         }
 263         return 0;
 264 }
 265
 266 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 267 {
 268         struct inode *inode = page->mapping->host;
 269
 270         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 271         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 272
 273         nfs_pageio_cond_complete(pgio, page->index);
 274         return nfs_page_async_flush(pgio, page);
 275 }
 276
 277 /*
 278  * Write an mmapped page to the server.
 279  */
 280 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 281 {
 282         struct nfs_pageio_descriptor pgio;
 283         int err;
 284
 285         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
 286         err = nfs_do_writepage(page, wbc, &pgio);
 287         nfs_pageio_complete(&pgio);
 288         if (err < 0)
 289                 return err;
 290         if (pgio.pg_error < 0)
 291                 return pgio.pg_error;
 292         return 0;
 293 }
 294
 295 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 296 {
 297         int ret;
 298
 299         ret = nfs_writepage_locked(page, wbc);
 300         unlock_page(page);
 301         return ret;
 302 }
 303
 304 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 305 {
 306         int ret;
 307
 308         ret = nfs_do_writepage(page, wbc, data);
 309         unlock_page(page);
 310         return ret;
 311 }
 312
 313 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 314 {
 315         struct inode *inode = mapping->host;
 316         unsigned long *bitlock = &NFS_I(inode)->flags;
 317         struct nfs_pageio_descriptor pgio;
 318         int err;
 319
 320         /* Stop dirtying of new pages while we sync */
 321         err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
 322                         nfs_wait_bit_killable, TASK_KILLABLE);
 323         if (err)
 324                 goto out_err;
 325
 326         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 327
 328         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
 329         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 330         nfs_pageio_complete(&pgio);
 331
 332         clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
 333         smp_mb__after_clear_bit();
 334         wake_up_bit(bitlock, NFS_INO_FLUSHING);
 335
 336         if (err < 0)
 337                 goto out_err;
 338         err = pgio.pg_error;
 339         if (err < 0)
 340                 goto out_err;
 341         return 0;
 342 out_err:
 343         return err;
 344 }
 345
 346 /*
 347  * Insert a write request into an inode
 348  */
 349 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 350 {
 351         struct nfs_inode *nfsi = NFS_I(inode);
 352         int error;
 353
 354         error = radix_tree_preload(GFP_NOFS);
 355         if (error != 0)
 356                 goto out;
 357
 358         /* Lock the request! */
 359         nfs_lock_request_dontget(req);
 360
 361         spin_lock(&inode->i_lock);
 362         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 363         BUG_ON(error);
 364         if (!nfsi->npages) {
 365                 igrab(inode);
 366                 if (nfs_have_delegation(inode, FMODE_WRITE))
 367                         nfsi->change_attr++;
 368         }
 369         SetPagePrivate(req->wb_page);
 370         set_page_private(req->wb_page, (unsigned long)req);
 371         nfsi->npages++;
 372         kref_get(&req->wb_kref);
 373         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
 374                                 NFS_PAGE_TAG_LOCKED);
 375         spin_unlock(&inode->i_lock);
 376         radix_tree_preload_end();
 377 out:
 378         return error;
 379 }
 380
 381 /*
 382  * Remove a write request from an inode
 383  */
 384 static void nfs_inode_remove_request(struct nfs_page *req)
 385 {
 386         struct inode *inode = req->wb_context->path.dentry->d_inode;
 387         struct nfs_inode *nfsi = NFS_I(inode);
 388
 389         BUG_ON (!NFS_WBACK_BUSY(req));
 390
 391         spin_lock(&inode->i_lock);
 392         set_page_private(req->wb_page, 0);
 393         ClearPagePrivate(req->wb_page);
 394         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 395         nfsi->npages--;
 396         if (!nfsi->npages) {
 397                 spin_unlock(&inode->i_lock);
 398                 iput(inode);
 399         } else
 400                 spin_unlock(&inode->i_lock);
 401         nfs_clear_request(req);
 402         nfs_release_request(req);
 403 }
 404
 405 static void
 406 nfs_mark_request_dirty(struct nfs_page *req)
 407 {
 408         __set_page_dirty_nobuffers(req->wb_page);
 409 }
 410
 411 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 412 /*
 413  * Add a request to the inode's commit list.
 414  */
 415 static void
 416 nfs_mark_request_commit(struct nfs_page *req)
 417 {
 418         struct inode *inode = req->wb_context->path.dentry->d_inode;
 419         struct nfs_inode *nfsi = NFS_I(inode);
 420
 421         spin_lock(&inode->i_lock);
 422         set_bit(PG_CLEAN, &(req)->wb_flags);
 423         radix_tree_tag_set(&nfsi->nfs_page_tree,
 424                         req->wb_index,
 425                         NFS_PAGE_TAG_COMMIT);
 426         spin_unlock(&inode->i_lock);
 427         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 428         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 429         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 430 }
 431
 432 static int
 433 nfs_clear_request_commit(struct nfs_page *req)
 434 {
 435         struct page *page = req->wb_page;
 436
 437         if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
 438                 dec_zone_page_state(page, NR_UNSTABLE_NFS);
 439                 dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 440                 return 1;
 441         }
 442         return 0;
 443 }
 444
 445 static inline
 446 int nfs_write_need_commit(struct nfs_write_data *data)
 447 {
 448         return data->verf.committed != NFS_FILE_SYNC;
 449 }
 450
 451 static inline
 452 int nfs_reschedule_unstable_write(struct nfs_page *req)
 453 {
 454         if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 455                 nfs_mark_request_commit(req);
 456                 return 1;
 457         }
 458         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 459                 nfs_mark_request_dirty(req);
 460                 return 1;
 461         }
 462         return 0;
 463 }
 464 #else
 465 static inline void
 466 nfs_mark_request_commit(struct nfs_page *req)
 467 {
 468 }
 469
 470 static inline int
 471 nfs_clear_request_commit(struct nfs_page *req)
 472 {
 473         return 0;
 474 }
 475
 476 static inline
 477 int nfs_write_need_commit(struct nfs_write_data *data)
 478 {
 479         return 0;
 480 }
 481
 482 static inline
 483 int nfs_reschedule_unstable_write(struct nfs_page *req)
 484 {
 485         return 0;
 486 }
 487 #endif
 488
 489 /*
 490  * Wait for a request to complete.
 491  *
 492  * Interruptible by fatal signals only.
 493  */
 494 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
 495 {
 496         struct nfs_inode *nfsi = NFS_I(inode);
 497         struct nfs_page *req;
 498         pgoff_t idx_end, next;
 499         unsigned int            res = 0;
 500         int                     error;
 501
 502         if (npages == 0)
 503                 idx_end = ~0;
 504         else
 505                 idx_end = idx_start + npages - 1;
 506
 507         next = idx_start;
 508         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
 509                 if (req->wb_index > idx_end)
 510                         break;
 511
 512                 next = req->wb_index + 1;
 513                 BUG_ON(!NFS_WBACK_BUSY(req));
 514
 515                 kref_get(&req->wb_kref);
 516                 spin_unlock(&inode->i_lock);
 517                 error = nfs_wait_on_request(req);
 518                 nfs_release_request(req);
 519                 spin_lock(&inode->i_lock);
 520                 if (error < 0)
 521                         return error;
 522                 res++;
 523         }
 524         return res;
 525 }
 526
 527 static void nfs_cancel_commit_list(struct list_head *head)
 528 {
 529         struct nfs_page *req;
 530
 531         while(!list_empty(head)) {
 532                 req = nfs_list_entry(head->next);
 533                 nfs_list_remove_request(req);
 534                 nfs_clear_request_commit(req);
 535                 nfs_inode_remove_request(req);
 536                 nfs_unlock_request(req);
 537         }
 538 }
 539
 540 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 541 static int
 542 nfs_need_commit(struct nfs_inode *nfsi)
 543 {
 544         return radix_tree_tagged(&nfsi->nfs_page_tree, NFS_PAGE_TAG_COMMIT);
 545 }
 546
 547 /*
 548  * nfs_scan_commit - Scan an inode for commit requests
 549  * @inode: NFS inode to scan
 550  * @dst: destination list
 551  * @idx_start: lower bound of page->index to scan.
 552  * @npages: idx_start + npages sets the upper bound to scan.
 553  *
 554  * Moves requests from the inode's 'commit' request list.
 555  * The requests are *not* checked to ensure that they form a contiguous set.
 556  */
 557 static int
 558 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 559 {
 560         struct nfs_inode *nfsi = NFS_I(inode);
 561
 562         if (!nfs_need_commit(nfsi))
 563                 return 0;
 564
 565         return nfs_scan_list(nfsi, dst, idx_start, npages, NFS_PAGE_TAG_COMMIT);
 566 }
 567 #else
 568 static inline int nfs_need_commit(struct nfs_inode *nfsi)
 569 {
 570         return 0;
 571 }
 572
 573 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 574 {
 575         return 0;
 576 }
 577 #endif
 578
 579 /*
 580  * Search for an existing write request, and attempt to update
 581  * it to reflect a new dirty region on a given page.
 582  *
 583  * If the attempt fails, then the existing request is flushed out
 584  * to disk.
 585  */
 586 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
 587                 struct page *page,
 588                 unsigned int offset,
 589                 unsigned int bytes)
 590 {
 591         struct nfs_page *req;
 592         unsigned int rqend;
 593         unsigned int end;
 594         int error;
 595
 596         if (!PagePrivate(page))
 597                 return NULL;
 598
 599         end = offset + bytes;
 600         spin_lock(&inode->i_lock);
 601
 602         for (;;) {
 603                 req = nfs_page_find_request_locked(page);
 604                 if (req == NULL)
 605                         goto out_unlock;
 606
 607                 rqend = req->wb_offset + req->wb_bytes;
 608                 /*
 609                  * Tell the caller to flush out the request if
 610                  * the offsets are non-contiguous.
 611                  * Note: nfs_flush_incompatible() will already
 612                  * have flushed out requests having wrong owners.
 613                  */
 614                 if (offset > rqend
 615                     || end < req->wb_offset)
 616                         goto out_flushme;
 617
 618                 if (nfs_set_page_tag_locked(req))
 619                         break;
 620
 621                 /* The request is locked, so wait and then retry */
 622                 spin_unlock(&inode->i_lock);
 623                 error = nfs_wait_on_request(req);
 624                 nfs_release_request(req);
 625                 if (error != 0)
 626                         goto out_err;
 627                 spin_lock(&inode->i_lock);
 628         }
 629
 630         if (nfs_clear_request_commit(req))
 631                 radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
 632                                 req->wb_index, NFS_PAGE_TAG_COMMIT);
 633
 634         /* Okay, the request matches. Update the region */
 635         if (offset < req->wb_offset) {
 636                 req->wb_offset = offset;
 637                 req->wb_pgbase = offset;
 638         }
 639         if (end > rqend)
 640                 req->wb_bytes = end - req->wb_offset;
 641         else
 642                 req->wb_bytes = rqend - req->wb_offset;
 643 out_unlock:
 644         spin_unlock(&inode->i_lock);
 645         return req;
 646 out_flushme:
 647         spin_unlock(&inode->i_lock);
 648         nfs_release_request(req);
 649         error = nfs_wb_page(inode, page);
 650 out_err:
 651         return ERR_PTR(error);
 652 }
 653
 654 /*
 655  * Try to update an existing write request, or create one if there is none.
 656  *
 657  * Note: Should always be called with the Page Lock held to prevent races
 658  * if we have to add a new request. Also assumes that the caller has
 659  * already called nfs_flush_incompatible() if necessary.
 660  */
 661 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
 662                 struct page *page, unsigned int offset, unsigned int bytes)
 663 {
 664         struct inode *inode = page->mapping->host;
 665         struct nfs_page *req;
 666         int error;
 667
 668         req = nfs_try_to_update_request(inode, page, offset, bytes);
 669         if (req != NULL)
 670                 goto out;
 671         req = nfs_create_request(ctx, inode, page, offset, bytes);
 672         if (IS_ERR(req))
 673                 goto out;
 674         error = nfs_inode_add_request(inode, req);
 675         if (error != 0) {
 676                 nfs_release_request(req);
 677                 req = ERR_PTR(error);
 678         }
 679 out:
 680         return req;
 681 }
 682
 683 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 684                 unsigned int offset, unsigned int count)
 685 {
 686         struct nfs_page *req;
 687
 688         req = nfs_setup_write_request(ctx, page, offset, count);
 689         if (IS_ERR(req))
 690                 return PTR_ERR(req);
 691         /* Update file length */
 692         nfs_grow_file(page, offset, count);
 693         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
 694         nfs_clear_page_tag_locked(req);
 695         return 0;
 696 }
 697
 698 int nfs_flush_incompatible(struct file *file, struct page *page)
 699 {
 700         struct nfs_open_context *ctx = nfs_file_open_context(file);
 701         struct nfs_page *req;
 702         int do_flush, status;
 703         /*
 704          * Look for a request corresponding to this page. If there
 705          * is one, and it belongs to another file, we flush it out
 706          * before we try to copy anything into the page. Do this
 707          * due to the lack of an ACCESS-type call in NFSv2.
 708          * Also do the same if we find a request from an existing
 709          * dropped page.
 710          */
 711         do {
 712                 req = nfs_page_find_request(page);
 713                 if (req == NULL)
 714                         return 0;
 715                 do_flush = req->wb_page != page || req->wb_context != ctx;
 716                 nfs_release_request(req);
 717                 if (!do_flush)
 718                         return 0;
 719                 status = nfs_wb_page(page->mapping->host, page);
 720         } while (status == 0);
 721         return status;
 722 }
 723
 724 /*
 725  * If the page cache is marked as unsafe or invalid, then we can't rely on
 726  * the PageUptodate() flag. In this case, we will need to turn off
 727  * write optimisations that depend on the page contents being correct.
 728  */
 729 static int nfs_write_pageuptodate(struct page *page, struct inode *inode)
 730 {
 731         return PageUptodate(page) &&
 732                 !(NFS_I(inode)->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA));
 733 }
 734
 735 /*
 736  * Update and possibly write a cached page of an NFS file.
 737  *
 738  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 739  * things with a page scheduled for an RPC call (e.g. invalidate it).
 740  */
 741 int nfs_updatepage(struct file *file, struct page *page,
 742                 unsigned int offset, unsigned int count)
 743 {
 744         struct nfs_open_context *ctx = nfs_file_open_context(file);
 745         struct inode    *inode = page->mapping->host;
 746         int             status = 0;
 747
 748         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 749
 750         dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
 751                 file->f_path.dentry->d_parent->d_name.name,
 752                 file->f_path.dentry->d_name.name, count,
 753                 (long long)(page_offset(page) + offset));
 754
 755         /* If we're not using byte range locks, and we know the page
 756          * is up to date, it may be more efficient to extend the write
 757          * to cover the entire page in order to avoid fragmentation
 758          * inefficiencies.
 759          */
 760         if (nfs_write_pageuptodate(page, inode) &&
 761                         inode->i_flock == NULL &&
 762                         !(file->f_flags & O_SYNC)) {
 763                 count = max(count + offset, nfs_page_length(page));
 764                 offset = 0;
 765         }
 766
 767         status = nfs_writepage_setup(ctx, page, offset, count);
 768         if (status < 0)
 769                 nfs_set_pageerror(page);
 770         else
 771                 __set_page_dirty_nobuffers(page);
 772
 773         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 774                         status, (long long)i_size_read(inode));
 775         return status;
 776 }
 777
 778 static void nfs_writepage_release(struct nfs_page *req)
 779 {
 780
 781         if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req)) {
 782                 nfs_end_page_writeback(req->wb_page);
 783                 nfs_inode_remove_request(req);
 784         } else
 785                 nfs_end_page_writeback(req->wb_page);
 786         nfs_clear_page_tag_locked(req);
 787 }
 788
 789 static int flush_task_priority(int how)
 790 {
 791         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 792                 case FLUSH_HIGHPRI:
 793                         return RPC_PRIORITY_HIGH;
 794                 case FLUSH_LOWPRI:
 795                         return RPC_PRIORITY_LOW;
 796         }
 797         return RPC_PRIORITY_NORMAL;
 798 }
 799
 800 /*
 801  * Set up the argument/result storage required for the RPC call.
 802  */
 803 static int nfs_write_rpcsetup(struct nfs_page *req,
 804                 struct nfs_write_data *data,
 805                 const struct rpc_call_ops *call_ops,
 806                 unsigned int count, unsigned int offset,
 807                 int how)
 808 {
 809         struct inode *inode = req->wb_context->path.dentry->d_inode;
 810         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 811         int priority = flush_task_priority(how);
 812         struct rpc_task *task;
 813         struct rpc_message msg = {
 814                 .rpc_argp = &data->args,
 815                 .rpc_resp = &data->res,
 816                 .rpc_cred = req->wb_context->cred,
 817         };
 818         struct rpc_task_setup task_setup_data = {
 819                 .rpc_client = NFS_CLIENT(inode),
 820                 .task = &data->task,
 821                 .rpc_message = &msg,
 822                 .callback_ops = call_ops,
 823                 .callback_data = data,
 824                 .workqueue = nfsiod_workqueue,
 825                 .flags = flags,
 826                 .priority = priority,
 827         };
 828
 829         /* Set up the RPC argument and reply structs
 830          * NB: take care not to mess about with data->commit et al. */
 831
 832         data->req = req;
 833         data->inode = inode = req->wb_context->path.dentry->d_inode;
 834         data->cred = msg.rpc_cred;
 835
 836         data->args.fh     = NFS_FH(inode);
 837         data->args.offset = req_offset(req) + offset;
 838         data->args.pgbase = req->wb_pgbase + offset;
 839         data->args.pages  = data->pagevec;
 840         data->args.count  = count;
 841         data->args.context = get_nfs_open_context(req->wb_context);
 842         data->args.stable  = NFS_UNSTABLE;
 843         if (how & FLUSH_STABLE) {
 844                 data->args.stable = NFS_DATA_SYNC;
 845                 if (!nfs_need_commit(NFS_I(inode)))
 846                         data->args.stable = NFS_FILE_SYNC;
 847         }
 848
 849         data->res.fattr   = &data->fattr;
 850         data->res.count   = count;
 851         data->res.verf    = &data->verf;
 852         nfs_fattr_init(&data->fattr);
 853
 854         /* Set up the initial task struct.  */
 855         NFS_PROTO(inode)->write_setup(data, &msg);
 856
 857         dprintk("NFS: %5u initiated write call "
 858                 "(req %s/%lld, %u bytes @ offset %llu)\n",
 859                 data->task.tk_pid,
 860                 inode->i_sb->s_id,
 861                 (long long)NFS_FILEID(inode),
 862                 count,
 863                 (unsigned long long)data->args.offset);
 864
 865         task = rpc_run_task(&task_setup_data);
 866         if (IS_ERR(task))
 867                 return PTR_ERR(task);
 868         rpc_put_task(task);
 869         return 0;
 870 }
 871
 872 /* If a nfs_flush_* function fails, it should remove reqs from @head and
 873  * call this on each, which will prepare them to be retried on next
 874  * writeback using standard nfs.
 875  */
 876 static void nfs_redirty_request(struct nfs_page *req)
 877 {
 878         nfs_mark_request_dirty(req);
 879         nfs_end_page_writeback(req->wb_page);
 880         nfs_clear_page_tag_locked(req);
 881 }
 882
 883 /*
 884  * Generate multiple small requests to write out a single
 885  * contiguous dirty area on one page.
 886  */
 887 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 888 {
 889         struct nfs_page *req = nfs_list_entry(head->next);
 890         struct page *page = req->wb_page;
 891         struct nfs_write_data *data;
 892         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 893         unsigned int offset;
 894         int requests = 0;
 895         int ret = 0;
 896         LIST_HEAD(list);
 897
 898         nfs_list_remove_request(req);
 899
 900         nbytes = count;
 901         do {
 902                 size_t len = min(nbytes, wsize);
 903
 904                 data = nfs_writedata_alloc(1);
 905                 if (!data)
 906                         goto out_bad;
 907                 list_add(&data->pages, &list);
 908                 requests++;
 909                 nbytes -= len;
 910         } while (nbytes != 0);
 911         atomic_set(&req->wb_complete, requests);
 912
 913         ClearPageError(page);
 914         offset = 0;
 915         nbytes = count;
 916         do {
 917                 int ret2;
 918
 919                 data = list_entry(list.next, struct nfs_write_data, pages);
 920                 list_del_init(&data->pages);
 921
 922                 data->pagevec[0] = page;
 923
 924                 if (nbytes < wsize)
 925                         wsize = nbytes;
 926                 ret2 = nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 927                                    wsize, offset, how);
 928                 if (ret == 0)
 929                         ret = ret2;
 930                 offset += wsize;
 931                 nbytes -= wsize;
 932         } while (nbytes != 0);
 933
 934         return ret;
 935
 936 out_bad:
 937         while (!list_empty(&list)) {
 938                 data = list_entry(list.next, struct nfs_write_data, pages);
 939                 list_del(&data->pages);
 940                 nfs_writedata_release(data);
 941         }
 942         nfs_redirty_request(req);
 943         return -ENOMEM;
 944 }
 945
 946 /*
 947  * Create an RPC task for the given write request and kick it.
 948  * The page must have been locked by the caller.
 949  *
 950  * It may happen that the page we're passed is not marked dirty.
 951  * This is the case if nfs_updatepage detects a conflicting request
 952  * that has been written but not committed.
 953  */
 954 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 955 {
 956         struct nfs_page         *req;
 957         struct page             **pages;
 958         struct nfs_write_data   *data;
 959
 960         data = nfs_writedata_alloc(npages);
 961         if (!data)
 962                 goto out_bad;
 963
 964         pages = data->pagevec;
 965         while (!list_empty(head)) {
 966                 req = nfs_list_entry(head->next);
 967                 nfs_list_remove_request(req);
 968                 nfs_list_add_request(req, &data->pages);
 969                 ClearPageError(req->wb_page);
 970                 *pages++ = req->wb_page;
 971         }
 972         req = nfs_list_entry(data->pages.next);
 973
 974         /* Set up the argument struct */
 975         return nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 976  out_bad:
 977         while (!list_empty(head)) {
 978                 req = nfs_list_entry(head->next);
 979                 nfs_list_remove_request(req);
 980                 nfs_redirty_request(req);
 981         }
 982         return -ENOMEM;
 983 }
 984
 985 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
 986                                   struct inode *inode, int ioflags)
 987 {
 988         size_t wsize = NFS_SERVER(inode)->wsize;
 989
 990         if (wsize < PAGE_CACHE_SIZE)
 991                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
 992         else
 993                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
 994 }
 995
 996 /*
 997  * Handle a write reply that flushed part of a page.
 998  */
 999 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
1000 {
1001         struct nfs_write_data   *data = calldata;
1002
1003         dprintk("NFS: %5u write(%s/%lld %d@%lld)",
1004                 task->tk_pid,
1005                 data->req->wb_context->path.dentry->d_inode->i_sb->s_id,
1006                 (long long)
1007                   NFS_FILEID(data->req->wb_context->path.dentry->d_inode),
1008                 data->req->wb_bytes, (long long)req_offset(data->req));
1009
1010         nfs_writeback_done(task, data);
1011 }
1012
1013 static void nfs_writeback_release_partial(void *calldata)
1014 {
1015         struct nfs_write_data   *data = calldata;
1016         struct nfs_page         *req = data->req;
1017         struct page             *page = req->wb_page;
1018         int status = data->task.tk_status;
1019
1020         if (status < 0) {
1021                 nfs_set_pageerror(page);
1022                 nfs_context_set_write_error(req->wb_context, status);
1023                 dprintk(", error = %d\n", status);
1024                 goto out;
1025         }
1026
1027         if (nfs_write_need_commit(data)) {
1028                 struct inode *inode = page->mapping->host;
1029
1030                 spin_lock(&inode->i_lock);
1031                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
1032                         /* Do nothing we need to resend the writes */
1033                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1034                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1035                         dprintk(" defer commit\n");
1036                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1037                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
1038                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
1039                         dprintk(" server reboot detected\n");
1040                 }
1041                 spin_unlock(&inode->i_lock);
1042         } else
1043                 dprintk(" OK\n");
1044
1045 out:
1046         if (atomic_dec_and_test(&req->wb_complete))
1047                 nfs_writepage_release(req);
1048         nfs_writedata_release(calldata);
1049 }
1050
1051 static const struct rpc_call_ops nfs_write_partial_ops = {
1052         .rpc_call_done = nfs_writeback_done_partial,
1053         .rpc_release = nfs_writeback_release_partial,
1054 };
1055
1056 /*
1057  * Handle a write reply that flushes a whole page.
1058  *
1059  * FIXME: There is an inherent race with invalidate_inode_pages and
1060  *        writebacks since the page->count is kept > 1 for as long
1061  *        as the page has a write request pending.
1062  */
1063 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1064 {
1065         struct nfs_write_data   *data = calldata;
1066
1067         nfs_writeback_done(task, data);
1068 }
1069
1070 static void nfs_writeback_release_full(void *calldata)
1071 {
1072         struct nfs_write_data   *data = calldata;
1073         int status = data->task.tk_status;
1074
1075         /* Update attributes as result of writeback. */
1076         while (!list_empty(&data->pages)) {
1077                 struct nfs_page *req = nfs_list_entry(data->pages.next);
1078                 struct page *page = req->wb_page;
1079
1080                 nfs_list_remove_request(req);
1081
1082                 dprintk("NFS: %5u write (%s/%lld %d@%lld)",
1083                         data->task.tk_pid,
1084                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1085                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1086                         req->wb_bytes,
1087                         (long long)req_offset(req));
1088
1089                 if (status < 0) {
1090                         nfs_set_pageerror(page);
1091                         nfs_context_set_write_error(req->wb_context, status);
1092                         dprintk(", error = %d\n", status);
1093                         goto remove_request;
1094                 }
1095
1096                 if (nfs_write_need_commit(data)) {
1097                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1098                         nfs_mark_request_commit(req);
1099                         nfs_end_page_writeback(page);
1100                         dprintk(" marked for commit\n");
1101                         goto next;
1102                 }
1103                 dprintk(" OK\n");
1104 remove_request:
1105                 nfs_end_page_writeback(page);
1106                 nfs_inode_remove_request(req);
1107         next:
1108                 nfs_clear_page_tag_locked(req);
1109         }
1110         nfs_writedata_release(calldata);
1111 }
1112
1113 static const struct rpc_call_ops nfs_write_full_ops = {
1114         .rpc_call_done = nfs_writeback_done_full,
1115         .rpc_release = nfs_writeback_release_full,
1116 };
1117
1118
1119 /*
1120  * This function is called when the WRITE call is complete.
1121  */
1122 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1123 {
1124         struct nfs_writeargs    *argp = &data->args;
1125         struct nfs_writeres     *resp = &data->res;
1126         int status;
1127
1128         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1129                 task->tk_pid, task->tk_status);
1130
1131         /*
1132          * ->write_done will attempt to use post-op attributes to detect
1133          * conflicting writes by other clients.  A strict interpretation
1134          * of close-to-open would allow us to continue caching even if
1135          * another writer had changed the file, but some applications
1136          * depend on tighter cache coherency when writing.
1137          */
1138         status = NFS_PROTO(data->inode)->write_done(task, data);
1139         if (status != 0)
1140                 return status;
1141         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1142
1143 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1144         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1145                 /* We tried a write call, but the server did not
1146                  * commit data to stable storage even though we
1147                  * requested it.
1148                  * Note: There is a known bug in Tru64 < 5.0 in which
1149                  *       the server reports NFS_DATA_SYNC, but performs
1150                  *       NFS_FILE_SYNC. We therefore implement this checking
1151                  *       as a dprintk() in order to avoid filling syslog.
1152                  */
1153                 static unsigned long    complain;
1154
1155                 if (time_before(complain, jiffies)) {
1156                         dprintk("NFS:       faulty NFS server %s:"
1157                                 " (committed = %d) != (stable = %d)\n",
1158                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1159                                 resp->verf->committed, argp->stable);
1160                         complain = jiffies + 300 * HZ;
1161                 }
1162         }
1163 #endif
1164         /* Is this a short write? */
1165         if (task->tk_status >= 0 && resp->count < argp->count) {
1166                 static unsigned long    complain;
1167
1168                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1169
1170                 /* Has the server at least made some progress? */
1171                 if (resp->count != 0) {
1172                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1173                         if (resp->verf->committed != NFS_UNSTABLE) {
1174                                 /* Resend from where the server left off */
1175                                 argp->offset += resp->count;
1176                                 argp->pgbase += resp->count;
1177                                 argp->count -= resp->count;
1178                         } else {
1179                                 /* Resend as a stable write in order to avoid
1180                                  * headaches in the case of a server crash.
1181                                  */
1182                                 argp->stable = NFS_FILE_SYNC;
1183                         }
1184                         rpc_restart_call(task);
1185                         return -EAGAIN;
1186                 }
1187                 if (time_before(complain, jiffies)) {
1188                         printk(KERN_WARNING
1189                                "NFS: Server wrote zero bytes, expected %u.\n",
1190                                         argp->count);
1191                         complain = jiffies + 300 * HZ;
1192                 }
1193                 /* Can't do anything about it except throw an error. */
1194                 task->tk_status = -EIO;
1195         }
1196         return 0;
1197 }
1198
1199
1200 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1201 void nfs_commitdata_release(void *data)
1202 {
1203         struct nfs_write_data *wdata = data;
1204
1205         put_nfs_open_context(wdata->args.context);
1206         nfs_commit_free(wdata);
1207 }
1208
1209 /*
1210  * Set up the argument/result storage required for the RPC call.
1211  */
1212 static int nfs_commit_rpcsetup(struct list_head *head,
1213                 struct nfs_write_data *data,
1214                 int how)
1215 {
1216         struct nfs_page *first = nfs_list_entry(head->next);
1217         struct inode *inode = first->wb_context->path.dentry->d_inode;
1218         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1219         int priority = flush_task_priority(how);
1220         struct rpc_task *task;
1221         struct rpc_message msg = {
1222                 .rpc_argp = &data->args,
1223                 .rpc_resp = &data->res,
1224                 .rpc_cred = first->wb_context->cred,
1225         };
1226         struct rpc_task_setup task_setup_data = {
1227                 .task = &data->task,
1228                 .rpc_client = NFS_CLIENT(inode),
1229                 .rpc_message = &msg,
1230                 .callback_ops = &nfs_commit_ops,
1231                 .callback_data = data,
1232                 .workqueue = nfsiod_workqueue,
1233                 .flags = flags,
1234                 .priority = priority,
1235         };
1236
1237         /* Set up the RPC argument and reply structs
1238          * NB: take care not to mess about with data->commit et al. */
1239
1240         list_splice_init(head, &data->pages);
1241
1242         data->inode       = inode;
1243         data->cred        = msg.rpc_cred;
1244
1245         data->args.fh     = NFS_FH(data->inode);
1246         /* Note: we always request a commit of the entire inode */
1247         data->args.offset = 0;
1248         data->args.count  = 0;
1249         data->args.context = get_nfs_open_context(first->wb_context);
1250         data->res.count   = 0;
1251         data->res.fattr   = &data->fattr;
1252         data->res.verf    = &data->verf;
1253         nfs_fattr_init(&data->fattr);
1254
1255         /* Set up the initial task struct.  */
1256         NFS_PROTO(inode)->commit_setup(data, &msg);
1257
1258         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1259
1260         task = rpc_run_task(&task_setup_data);
1261         if (IS_ERR(task))
1262                 return PTR_ERR(task);
1263         rpc_put_task(task);
1264         return 0;
1265 }
1266
1267 /*
1268  * Commit dirty pages
1269  */
1270 static int
1271 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1272 {
1273         struct nfs_write_data   *data;
1274         struct nfs_page         *req;
1275
1276         data = nfs_commitdata_alloc();
1277
1278         if (!data)
1279                 goto out_bad;
1280
1281         /* Set up the argument struct */
1282         return nfs_commit_rpcsetup(head, data, how);
1283  out_bad:
1284         while (!list_empty(head)) {
1285                 req = nfs_list_entry(head->next);
1286                 nfs_list_remove_request(req);
1287                 nfs_mark_request_commit(req);
1288                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1289                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1290                                 BDI_RECLAIMABLE);
1291                 nfs_clear_page_tag_locked(req);
1292         }
1293         return -ENOMEM;
1294 }
1295
1296 /*
1297  * COMMIT call returned
1298  */
1299 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1300 {
1301         struct nfs_write_data   *data = calldata;
1302
1303         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1304                                 task->tk_pid, task->tk_status);
1305
1306         /* Call the NFS version-specific code */
1307         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1308                 return;
1309 }
1310
1311 static void nfs_commit_release(void *calldata)
1312 {
1313         struct nfs_write_data   *data = calldata;
1314         struct nfs_page         *req;
1315         int status = data->task.tk_status;
1316
1317         while (!list_empty(&data->pages)) {
1318                 req = nfs_list_entry(data->pages.next);
1319                 nfs_list_remove_request(req);
1320                 nfs_clear_request_commit(req);
1321
1322                 dprintk("NFS:       commit (%s/%lld %d@%lld)",
1323                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1324                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1325                         req->wb_bytes,
1326                         (long long)req_offset(req));
1327                 if (status < 0) {
1328                         nfs_context_set_write_error(req->wb_context, status);
1329                         nfs_inode_remove_request(req);
1330                         dprintk(", error = %d\n", status);
1331                         goto next;
1332                 }
1333
1334                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1335                  * returned by the server against all stored verfs. */
1336                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1337                         /* We have a match */
1338                         nfs_inode_remove_request(req);
1339                         dprintk(" OK\n");
1340                         goto next;
1341                 }
1342                 /* We have a mismatch. Write the page again */
1343                 dprintk(" mismatch\n");
1344                 nfs_mark_request_dirty(req);
1345         next:
1346                 nfs_clear_page_tag_locked(req);
1347         }
1348         nfs_commitdata_release(calldata);
1349 }
1350
1351 static const struct rpc_call_ops nfs_commit_ops = {
1352         .rpc_call_done = nfs_commit_done,
1353         .rpc_release = nfs_commit_release,
1354 };
1355
1356 int nfs_commit_inode(struct inode *inode, int how)
1357 {
1358         LIST_HEAD(head);
1359         int res;
1360
1361         spin_lock(&inode->i_lock);
1362         res = nfs_scan_commit(inode, &head, 0, 0);
1363         spin_unlock(&inode->i_lock);
1364         if (res) {
1365                 int error = nfs_commit_list(inode, &head, how);
1366                 if (error < 0)
1367                         return error;
1368         }
1369         return res;
1370 }
1371 #else
1372 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1373 {
1374         return 0;
1375 }
1376 #endif
1377
1378 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1379 {
1380         struct inode *inode = mapping->host;
1381         pgoff_t idx_start, idx_end;
1382         unsigned int npages = 0;
1383         LIST_HEAD(head);
1384         int nocommit = how & FLUSH_NOCOMMIT;
1385         long pages, ret;
1386
1387         /* FIXME */
1388         if (wbc->range_cyclic)
1389                 idx_start = 0;
1390         else {
1391                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1392                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1393                 if (idx_end > idx_start) {
1394                         pgoff_t l_npages = 1 + idx_end - idx_start;
1395                         npages = l_npages;
1396                         if (sizeof(npages) != sizeof(l_npages) &&
1397                                         (pgoff_t)npages != l_npages)
1398                                 npages = 0;
1399                 }
1400         }
1401         how &= ~FLUSH_NOCOMMIT;
1402         spin_lock(&inode->i_lock);
1403         do {
1404                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1405                 if (ret != 0)
1406                         continue;
1407                 if (nocommit)
1408                         break;
1409                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1410                 if (pages == 0)
1411                         break;
1412                 if (how & FLUSH_INVALIDATE) {
1413                         spin_unlock(&inode->i_lock);
1414                         nfs_cancel_commit_list(&head);
1415                         ret = pages;
1416                         spin_lock(&inode->i_lock);
1417                         continue;
1418                 }
1419                 pages += nfs_scan_commit(inode, &head, 0, 0);
1420                 spin_unlock(&inode->i_lock);
1421                 ret = nfs_commit_list(inode, &head, how);
1422                 spin_lock(&inode->i_lock);
1423
1424         } while (ret >= 0);
1425         spin_unlock(&inode->i_lock);
1426         return ret;
1427 }
1428
1429 static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1430 {
1431         int ret;
1432
1433         ret = nfs_writepages(mapping, wbc);
1434         if (ret < 0)
1435                 goto out;
1436         ret = nfs_sync_mapping_wait(mapping, wbc, how);
1437         if (ret < 0)
1438                 goto out;
1439         return 0;
1440 out:
1441         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1442         return ret;
1443 }
1444
1445 /* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
1446 static int nfs_write_mapping(struct address_space *mapping, int how)
1447 {
1448         struct writeback_control wbc = {
1449                 .bdi = mapping->backing_dev_info,
1450                 .sync_mode = WB_SYNC_ALL,
1451                 .nr_to_write = LONG_MAX,
1452                 .range_start = 0,
1453                 .range_end = LLONG_MAX,
1454                 .for_writepages = 1,
1455         };
1456
1457         return __nfs_write_mapping(mapping, &wbc, how);
1458 }
1459
1460 /*
1461  * flush the inode to disk.
1462  */
1463 int nfs_wb_all(struct inode *inode)
1464 {
1465         return nfs_write_mapping(inode->i_mapping, 0);
1466 }
1467
1468 int nfs_wb_nocommit(struct inode *inode)
1469 {
1470         return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
1471 }
1472
1473 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1474 {
1475         struct nfs_page *req;
1476         loff_t range_start = page_offset(page);
1477         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1478         struct writeback_control wbc = {
1479                 .bdi = page->mapping->backing_dev_info,
1480                 .sync_mode = WB_SYNC_ALL,
1481                 .nr_to_write = LONG_MAX,
1482                 .range_start = range_start,
1483                 .range_end = range_end,
1484         };
1485         int ret = 0;
1486
1487         BUG_ON(!PageLocked(page));
1488         for (;;) {
1489                 req = nfs_page_find_request(page);
1490                 if (req == NULL)
1491                         goto out;
1492                 if (test_bit(PG_CLEAN, &req->wb_flags)) {
1493                         nfs_release_request(req);
1494                         break;
1495                 }
1496                 if (nfs_lock_request_dontget(req)) {
1497                         nfs_inode_remove_request(req);
1498                         /*
1499                          * In case nfs_inode_remove_request has marked the
1500                          * page as being dirty
1501                          */
1502                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1503                         nfs_unlock_request(req);
1504                         break;
1505                 }
1506                 ret = nfs_wait_on_request(req);
1507                 if (ret < 0)
1508                         goto out;
1509         }
1510         if (!PagePrivate(page))
1511                 return 0;
1512         ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
1513 out:
1514         return ret;
1515 }
1516
1517 static int nfs_wb_page_priority(struct inode *inode, struct page *page,
1518                                 int how)
1519 {
1520         loff_t range_start = page_offset(page);
1521         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1522         struct writeback_control wbc = {
1523                 .bdi = page->mapping->backing_dev_info,
1524                 .sync_mode = WB_SYNC_ALL,
1525                 .nr_to_write = LONG_MAX,
1526                 .range_start = range_start,
1527                 .range_end = range_end,
1528         };
1529         int ret;
1530
1531         do {
1532                 if (clear_page_dirty_for_io(page)) {
1533                         ret = nfs_writepage_locked(page, &wbc);
1534                         if (ret < 0)
1535                                 goto out_error;
1536                 } else if (!PagePrivate(page))
1537                         break;
1538                 ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1539                 if (ret < 0)
1540                         goto out_error;
1541         } while (PagePrivate(page));
1542         return 0;
1543 out_error:
1544         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1545         return ret;
1546 }
1547
1548 /*
1549  * Write back all requests on one page - we do this before reading it.
1550  */
1551 int nfs_wb_page(struct inode *inode, struct page* page)
1552 {
1553         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1554 }
1555
1556 int __init nfs_init_writepagecache(void)
1557 {
1558         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1559                                              sizeof(struct nfs_write_data),
1560                                              0, SLAB_HWCACHE_ALIGN,
1561                                              NULL);
1562         if (nfs_wdata_cachep == NULL)
1563                 return -ENOMEM;
1564
1565         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1566                                                      nfs_wdata_cachep);
1567         if (nfs_wdata_mempool == NULL)
1568                 return -ENOMEM;
1569
1570         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1571                                                       nfs_wdata_cachep);
1572         if (nfs_commit_mempool == NULL)
1573                 return -ENOMEM;
1574
1575         /*
1576          * NFS congestion size, scale with available memory.
1577          *
1578          *  64MB:    8192k
1579          * 128MB:   11585k
1580          * 256MB:   16384k
1581          * 512MB:   23170k
1582          *   1GB:   32768k
1583          *   2GB:   46340k
1584          *   4GB:   65536k
1585          *   8GB:   92681k
1586          *  16GB:  131072k
1587          *
1588          * This allows larger machines to have larger/more transfers.
1589          * Limit the default to 256M
1590          */
1591         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1592         if (nfs_congestion_kb > 256*1024)
1593                 nfs_congestion_kb = 256*1024;
1594
1595         return 0;
1596 }
1597
1598 void nfs_destroy_writepagecache(void)
1599 {
1600         mempool_destroy(nfs_commit_mempool);
1601         mempool_destroy(nfs_wdata_mempool);
1602         kmem_cache_destroy(nfs_wdata_cachep);
1603 }
1604