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