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   1 /*
   2  * linux/fs/nfs/write.c
   3  *
   4  * Write file data over NFS.
   5  *
   6  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/slab.h>
  11 #include <linux/mm.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/file.h>
  14 #include <linux/writeback.h>
  15 #include <linux/swap.h>
  16
  17 #include <linux/sunrpc/clnt.h>
  18 #include <linux/nfs_fs.h>
  19 #include <linux/nfs_mount.h>
  20 #include <linux/nfs_page.h>
  21 #include <linux/backing-dev.h>
  22
  23 #include <asm/uaccess.h>
  24 #include <linux/smp_lock.h>
  25
  26 #include "delegation.h"
  27 #include "internal.h"
  28 #include "iostat.h"
  29
  30 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  31
  32 #define MIN_POOL_WRITE          (32)
  33 #define MIN_POOL_COMMIT         (4)
  34
  35 /*
  36  * Local function declarations
  37  */
  38 static struct nfs_page * nfs_update_request(struct nfs_open_context*,
  39                                             struct page *,
  40                                             unsigned int, unsigned int);
  41 static void nfs_mark_request_dirty(struct nfs_page *req);
  42 static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how);
  43 static const struct rpc_call_ops nfs_write_partial_ops;
  44 static const struct rpc_call_ops nfs_write_full_ops;
  45 static const struct rpc_call_ops nfs_commit_ops;
  46
  47 static struct kmem_cache *nfs_wdata_cachep;
  48 static mempool_t *nfs_wdata_mempool;
  49 static mempool_t *nfs_commit_mempool;
  50
  51 struct nfs_write_data *nfs_commit_alloc(void)
  52 {
  53         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
  54
  55         if (p) {
  56                 memset(p, 0, sizeof(*p));
  57                 INIT_LIST_HEAD(&p->pages);
  58         }
  59         return p;
  60 }
  61
  62 void nfs_commit_rcu_free(struct rcu_head *head)
  63 {
  64         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
  65         if (p && (p->pagevec != &p->page_array[0]))
  66                 kfree(p->pagevec);
  67         mempool_free(p, nfs_commit_mempool);
  68 }
  69
  70 void nfs_commit_free(struct nfs_write_data *wdata)
  71 {
  72         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_commit_rcu_free);
  73 }
  74
  75 struct nfs_write_data *nfs_writedata_alloc(size_t len)
  76 {
  77         unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
  78         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
  79
  80         if (p) {
  81                 memset(p, 0, sizeof(*p));
  82                 INIT_LIST_HEAD(&p->pages);
  83                 p->npages = pagecount;
  84                 if (pagecount <= ARRAY_SIZE(p->page_array))
  85                         p->pagevec = p->page_array;
  86                 else {
  87                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
  88                         if (!p->pagevec) {
  89                                 mempool_free(p, nfs_wdata_mempool);
  90                                 p = NULL;
  91                         }
  92                 }
  93         }
  94         return p;
  95 }
  96
  97 static void nfs_writedata_rcu_free(struct rcu_head *head)
  98 {
  99         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
 100         if (p && (p->pagevec != &p->page_array[0]))
 101                 kfree(p->pagevec);
 102         mempool_free(p, nfs_wdata_mempool);
 103 }
 104
 105 static void nfs_writedata_free(struct nfs_write_data *wdata)
 106 {
 107         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free);
 108 }
 109
 110 void nfs_writedata_release(void *wdata)
 111 {
 112         nfs_writedata_free(wdata);
 113 }
 114
 115 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 116 {
 117         struct nfs_page *req = NULL;
 118
 119         if (PagePrivate(page)) {
 120                 req = (struct nfs_page *)page_private(page);
 121                 if (req != NULL)
 122                         atomic_inc(&req->wb_count);
 123         }
 124         return req;
 125 }
 126
 127 static struct nfs_page *nfs_page_find_request(struct page *page)
 128 {
 129         struct nfs_page *req = NULL;
 130         spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
 131
 132         spin_lock(req_lock);
 133         req = nfs_page_find_request_locked(page);
 134         spin_unlock(req_lock);
 135         return req;
 136 }
 137
 138 /* Adjust the file length if we're writing beyond the end */
 139 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 140 {
 141         struct inode *inode = page->mapping->host;
 142         loff_t end, i_size = i_size_read(inode);
 143         unsigned long end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 144
 145         if (i_size > 0 && page->index < end_index)
 146                 return;
 147         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 148         if (i_size >= end)
 149                 return;
 150         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 151         i_size_write(inode, end);
 152 }
 153
 154 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 155 static void nfs_set_pageerror(struct page *page)
 156 {
 157         SetPageError(page);
 158         nfs_zap_mapping(page->mapping->host, page->mapping);
 159 }
 160
 161 /* We can set the PG_uptodate flag if we see that a write request
 162  * covers the full page.
 163  */
 164 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 165 {
 166         if (PageUptodate(page))
 167                 return;
 168         if (base != 0)
 169                 return;
 170         if (count != nfs_page_length(page))
 171                 return;
 172         if (count != PAGE_CACHE_SIZE)
 173                 memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
 174         SetPageUptodate(page);
 175 }
 176
 177 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 178                 unsigned int offset, unsigned int count)
 179 {
 180         struct nfs_page *req;
 181         int ret;
 182
 183         for (;;) {
 184                 req = nfs_update_request(ctx, page, offset, count);
 185                 if (!IS_ERR(req))
 186                         break;
 187                 ret = PTR_ERR(req);
 188                 if (ret != -EBUSY)
 189                         return ret;
 190                 ret = nfs_wb_page(page->mapping->host, page);
 191                 if (ret != 0)
 192                         return ret;
 193         }
 194         /* Update file length */
 195         nfs_grow_file(page, offset, count);
 196         /* Set the PG_uptodate flag? */
 197         nfs_mark_uptodate(page, offset, count);
 198         nfs_unlock_request(req);
 199         return 0;
 200 }
 201
 202 static int wb_priority(struct writeback_control *wbc)
 203 {
 204         if (wbc->for_reclaim)
 205                 return FLUSH_HIGHPRI;
 206         if (wbc->for_kupdate)
 207                 return FLUSH_LOWPRI;
 208         return 0;
 209 }
 210
 211 /*
 212  * NFS congestion control
 213  */
 214
 215 int nfs_congestion_kb;
 216
 217 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 218 #define NFS_CONGESTION_OFF_THRESH       \
 219         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 220
 221 static int nfs_set_page_writeback(struct page *page)
 222 {
 223         int ret = test_set_page_writeback(page);
 224
 225         if (!ret) {
 226                 struct inode *inode = page->mapping->host;
 227                 struct nfs_server *nfss = NFS_SERVER(inode);
 228
 229                 if (atomic_inc_return(&nfss->writeback) >
 230                                 NFS_CONGESTION_ON_THRESH)
 231                         set_bdi_congested(&nfss->backing_dev_info, WRITE);
 232         }
 233         return ret;
 234 }
 235
 236 static void nfs_end_page_writeback(struct page *page)
 237 {
 238         struct inode *inode = page->mapping->host;
 239         struct nfs_server *nfss = NFS_SERVER(inode);
 240
 241         end_page_writeback(page);
 242         if (atomic_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) {
 243                 clear_bdi_congested(&nfss->backing_dev_info, WRITE);
 244                 congestion_end(WRITE);
 245         }
 246 }
 247
 248 /*
 249  * Find an associated nfs write request, and prepare to flush it out
 250  * Returns 1 if there was no write request, or if the request was
 251  * already tagged by nfs_set_page_dirty.Returns 0 if the request
 252  * was not tagged.
 253  * May also return an error if the user signalled nfs_wait_on_request().
 254  */
 255 static int nfs_page_mark_flush(struct page *page)
 256 {
 257         struct nfs_page *req;
 258         spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
 259         int ret;
 260
 261         spin_lock(req_lock);
 262         for(;;) {
 263                 req = nfs_page_find_request_locked(page);
 264                 if (req == NULL) {
 265                         spin_unlock(req_lock);
 266                         return 1;
 267                 }
 268                 if (nfs_lock_request_dontget(req))
 269                         break;
 270                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 271                  *       then the call to nfs_lock_request_dontget() will always
 272                  *       succeed provided that someone hasn't already marked the
 273                  *       request as dirty (in which case we don't care).
 274                  */
 275                 spin_unlock(req_lock);
 276                 ret = nfs_wait_on_request(req);
 277                 nfs_release_request(req);
 278                 if (ret != 0)
 279                         return ret;
 280                 spin_lock(req_lock);
 281         }
 282         spin_unlock(req_lock);
 283         if (nfs_set_page_writeback(page) == 0) {
 284                 nfs_list_remove_request(req);
 285                 nfs_mark_request_dirty(req);
 286         }
 287         ret = test_bit(PG_NEED_FLUSH, &req->wb_flags);
 288         nfs_unlock_request(req);
 289         return ret;
 290 }
 291
 292 /*
 293  * Write an mmapped page to the server.
 294  */
 295 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 296 {
 297         struct nfs_open_context *ctx;
 298         struct inode *inode = page->mapping->host;
 299         unsigned offset;
 300         int err;
 301
 302         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 303         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 304
 305         err = nfs_page_mark_flush(page);
 306         if (err <= 0)
 307                 goto out;
 308         err = 0;
 309         offset = nfs_page_length(page);
 310         if (!offset)
 311                 goto out;
 312
 313         ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
 314         if (ctx == NULL) {
 315                 err = -EBADF;
 316                 goto out;
 317         }
 318         err = nfs_writepage_setup(ctx, page, 0, offset);
 319         put_nfs_open_context(ctx);
 320         if (err != 0)
 321                 goto out;
 322         err = nfs_page_mark_flush(page);
 323         if (err > 0)
 324                 err = 0;
 325 out:
 326         if (!wbc->for_writepages)
 327                 nfs_flush_mapping(page->mapping, wbc, FLUSH_STABLE|wb_priority(wbc));
 328         return err;
 329 }
 330
 331 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 332 {
 333         int err;
 334
 335         err = nfs_writepage_locked(page, wbc);
 336         unlock_page(page);
 337         return err;
 338 }
 339
 340 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 341 {
 342         struct inode *inode = mapping->host;
 343         int err;
 344
 345         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 346
 347         err = generic_writepages(mapping, wbc);
 348         if (err)
 349                 return err;
 350         err = nfs_flush_mapping(mapping, wbc, wb_priority(wbc));
 351         if (err < 0)
 352                 goto out;
 353         nfs_add_stats(inode, NFSIOS_WRITEPAGES, err);
 354         err = 0;
 355 out:
 356         return err;
 357 }
 358
 359 /*
 360  * Insert a write request into an inode
 361  */
 362 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 363 {
 364         struct nfs_inode *nfsi = NFS_I(inode);
 365         int error;
 366
 367         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 368         BUG_ON(error == -EEXIST);
 369         if (error)
 370                 return error;
 371         if (!nfsi->npages) {
 372                 igrab(inode);
 373                 nfs_begin_data_update(inode);
 374                 if (nfs_have_delegation(inode, FMODE_WRITE))
 375                         nfsi->change_attr++;
 376         }
 377         SetPagePrivate(req->wb_page);
 378         set_page_private(req->wb_page, (unsigned long)req);
 379         nfsi->npages++;
 380         atomic_inc(&req->wb_count);
 381         return 0;
 382 }
 383
 384 /*
 385  * Remove a write request from an inode
 386  */
 387 static void nfs_inode_remove_request(struct nfs_page *req)
 388 {
 389         struct inode *inode = req->wb_context->dentry->d_inode;
 390         struct nfs_inode *nfsi = NFS_I(inode);
 391
 392         BUG_ON (!NFS_WBACK_BUSY(req));
 393
 394         spin_lock(&nfsi->req_lock);
 395         set_page_private(req->wb_page, 0);
 396         ClearPagePrivate(req->wb_page);
 397         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 398         nfsi->npages--;
 399         if (!nfsi->npages) {
 400                 spin_unlock(&nfsi->req_lock);
 401                 nfs_end_data_update(inode);
 402                 iput(inode);
 403         } else
 404                 spin_unlock(&nfsi->req_lock);
 405         nfs_clear_request(req);
 406         nfs_release_request(req);
 407 }
 408
 409 /*
 410  * Add a request to the inode's dirty list.
 411  */
 412 static void
 413 nfs_mark_request_dirty(struct nfs_page *req)
 414 {
 415         struct inode *inode = req->wb_context->dentry->d_inode;
 416         struct nfs_inode *nfsi = NFS_I(inode);
 417
 418         spin_lock(&nfsi->req_lock);
 419         radix_tree_tag_set(&nfsi->nfs_page_tree,
 420                         req->wb_index, NFS_PAGE_TAG_DIRTY);
 421         nfs_list_add_request(req, &nfsi->dirty);
 422         nfsi->ndirty++;
 423         spin_unlock(&nfsi->req_lock);
 424         __mark_inode_dirty(inode, I_DIRTY_PAGES);
 425 }
 426
 427 static void
 428 nfs_redirty_request(struct nfs_page *req)
 429 {
 430         __set_page_dirty_nobuffers(req->wb_page);
 431 }
 432
 433 /*
 434  * Check if a request is dirty
 435  */
 436 static inline int
 437 nfs_dirty_request(struct nfs_page *req)
 438 {
 439         struct page *page = req->wb_page;
 440
 441         if (page == NULL)
 442                 return 0;
 443         return !PageWriteback(req->wb_page);
 444 }
 445
 446 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 447 /*
 448  * Add a request to the inode's commit list.
 449  */
 450 static void
 451 nfs_mark_request_commit(struct nfs_page *req)
 452 {
 453         struct inode *inode = req->wb_context->dentry->d_inode;
 454         struct nfs_inode *nfsi = NFS_I(inode);
 455
 456         spin_lock(&nfsi->req_lock);
 457         nfs_list_add_request(req, &nfsi->commit);
 458         nfsi->ncommit++;
 459         spin_unlock(&nfsi->req_lock);
 460         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 461         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 462 }
 463 #endif
 464
 465 /*
 466  * Wait for a request to complete.
 467  *
 468  * Interruptible by signals only if mounted with intr flag.
 469  */
 470 static int nfs_wait_on_requests_locked(struct inode *inode, unsigned long idx_start, unsigned int npages)
 471 {
 472         struct nfs_inode *nfsi = NFS_I(inode);
 473         struct nfs_page *req;
 474         unsigned long           idx_end, next;
 475         unsigned int            res = 0;
 476         int                     error;
 477
 478         if (npages == 0)
 479                 idx_end = ~0;
 480         else
 481                 idx_end = idx_start + npages - 1;
 482
 483         next = idx_start;
 484         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
 485                 if (req->wb_index > idx_end)
 486                         break;
 487
 488                 next = req->wb_index + 1;
 489                 BUG_ON(!NFS_WBACK_BUSY(req));
 490
 491                 atomic_inc(&req->wb_count);
 492                 spin_unlock(&nfsi->req_lock);
 493                 error = nfs_wait_on_request(req);
 494                 nfs_release_request(req);
 495                 spin_lock(&nfsi->req_lock);
 496                 if (error < 0)
 497                         return error;
 498                 res++;
 499         }
 500         return res;
 501 }
 502
 503 static void nfs_cancel_dirty_list(struct list_head *head)
 504 {
 505         struct nfs_page *req;
 506         while(!list_empty(head)) {
 507                 req = nfs_list_entry(head->next);
 508                 nfs_list_remove_request(req);
 509                 nfs_end_page_writeback(req->wb_page);
 510                 nfs_inode_remove_request(req);
 511                 nfs_clear_page_writeback(req);
 512         }
 513 }
 514
 515 static void nfs_cancel_commit_list(struct list_head *head)
 516 {
 517         struct nfs_page *req;
 518
 519         while(!list_empty(head)) {
 520                 req = nfs_list_entry(head->next);
 521                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 522                 nfs_list_remove_request(req);
 523                 nfs_inode_remove_request(req);
 524                 nfs_unlock_request(req);
 525         }
 526 }
 527
 528 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 529 /*
 530  * nfs_scan_commit - Scan an inode for commit requests
 531  * @inode: NFS inode to scan
 532  * @dst: destination list
 533  * @idx_start: lower bound of page->index to scan.
 534  * @npages: idx_start + npages sets the upper bound to scan.
 535  *
 536  * Moves requests from the inode's 'commit' request list.
 537  * The requests are *not* checked to ensure that they form a contiguous set.
 538  */
 539 static int
 540 nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 541 {
 542         struct nfs_inode *nfsi = NFS_I(inode);
 543         int res = 0;
 544
 545         if (nfsi->ncommit != 0) {
 546                 res = nfs_scan_list(nfsi, &nfsi->commit, dst, idx_start, npages);
 547                 nfsi->ncommit -= res;
 548                 if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
 549                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
 550         }
 551         return res;
 552 }
 553 #else
 554 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 555 {
 556         return 0;
 557 }
 558 #endif
 559
 560 static int nfs_wait_on_write_congestion(struct address_space *mapping)
 561 {
 562         struct inode *inode = mapping->host;
 563         struct backing_dev_info *bdi = mapping->backing_dev_info;
 564         int ret = 0;
 565
 566         might_sleep();
 567
 568         if (!bdi_write_congested(bdi))
 569                 return 0;
 570
 571         nfs_inc_stats(inode, NFSIOS_CONGESTIONWAIT);
 572
 573         do {
 574                 struct rpc_clnt *clnt = NFS_CLIENT(inode);
 575                 sigset_t oldset;
 576
 577                 rpc_clnt_sigmask(clnt, &oldset);
 578                 ret = congestion_wait_interruptible(WRITE, HZ/10);
 579                 rpc_clnt_sigunmask(clnt, &oldset);
 580                 if (ret == -ERESTARTSYS)
 581                         break;
 582                 ret = 0;
 583         } while (bdi_write_congested(bdi));
 584
 585         return ret;
 586 }
 587
 588 /*
 589  * Try to update any existing write request, or create one if there is none.
 590  * In order to match, the request's credentials must match those of
 591  * the calling process.
 592  *
 593  * Note: Should always be called with the Page Lock held!
 594  */
 595 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 596                 struct page *page, unsigned int offset, unsigned int bytes)
 597 {
 598         struct address_space *mapping = page->mapping;
 599         struct inode *inode = mapping->host;
 600         struct nfs_inode *nfsi = NFS_I(inode);
 601         struct nfs_page         *req, *new = NULL;
 602         unsigned long           rqend, end;
 603
 604         end = offset + bytes;
 605
 606         if (nfs_wait_on_write_congestion(mapping))
 607                 return ERR_PTR(-ERESTARTSYS);
 608         for (;;) {
 609                 /* Loop over all inode entries and see if we find
 610                  * A request for the page we wish to update
 611                  */
 612                 spin_lock(&nfsi->req_lock);
 613                 req = nfs_page_find_request_locked(page);
 614                 if (req) {
 615                         if (!nfs_lock_request_dontget(req)) {
 616                                 int error;
 617
 618                                 spin_unlock(&nfsi->req_lock);
 619                                 error = nfs_wait_on_request(req);
 620                                 nfs_release_request(req);
 621                                 if (error < 0) {
 622                                         if (new)
 623                                                 nfs_release_request(new);
 624                                         return ERR_PTR(error);
 625                                 }
 626                                 continue;
 627                         }
 628                         spin_unlock(&nfsi->req_lock);
 629                         if (new)
 630                                 nfs_release_request(new);
 631                         break;
 632                 }
 633
 634                 if (new) {
 635                         int error;
 636                         nfs_lock_request_dontget(new);
 637                         error = nfs_inode_add_request(inode, new);
 638                         if (error) {
 639                                 spin_unlock(&nfsi->req_lock);
 640                                 nfs_unlock_request(new);
 641                                 return ERR_PTR(error);
 642                         }
 643                         spin_unlock(&nfsi->req_lock);
 644                         return new;
 645                 }
 646                 spin_unlock(&nfsi->req_lock);
 647
 648                 new = nfs_create_request(ctx, inode, page, offset, bytes);
 649                 if (IS_ERR(new))
 650                         return new;
 651         }
 652
 653         /* We have a request for our page.
 654          * If the creds don't match, or the
 655          * page addresses don't match,
 656          * tell the caller to wait on the conflicting
 657          * request.
 658          */
 659         rqend = req->wb_offset + req->wb_bytes;
 660         if (req->wb_context != ctx
 661             || req->wb_page != page
 662             || !nfs_dirty_request(req)
 663             || offset > rqend || end < req->wb_offset) {
 664                 nfs_unlock_request(req);
 665                 return ERR_PTR(-EBUSY);
 666         }
 667
 668         /* Okay, the request matches. Update the region */
 669         if (offset < req->wb_offset) {
 670                 req->wb_offset = offset;
 671                 req->wb_pgbase = offset;
 672                 req->wb_bytes = rqend - req->wb_offset;
 673         }
 674
 675         if (end > rqend)
 676                 req->wb_bytes = end - req->wb_offset;
 677
 678         return req;
 679 }
 680
 681 int nfs_flush_incompatible(struct file *file, struct page *page)
 682 {
 683         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 684         struct nfs_page *req;
 685         int do_flush, status;
 686         /*
 687          * Look for a request corresponding to this page. If there
 688          * is one, and it belongs to another file, we flush it out
 689          * before we try to copy anything into the page. Do this
 690          * due to the lack of an ACCESS-type call in NFSv2.
 691          * Also do the same if we find a request from an existing
 692          * dropped page.
 693          */
 694         do {
 695                 req = nfs_page_find_request(page);
 696                 if (req == NULL)
 697                         return 0;
 698                 do_flush = req->wb_page != page || req->wb_context != ctx
 699                         || !nfs_dirty_request(req);
 700                 nfs_release_request(req);
 701                 if (!do_flush)
 702                         return 0;
 703                 status = nfs_wb_page(page->mapping->host, page);
 704         } while (status == 0);
 705         return status;
 706 }
 707
 708 /*
 709  * Update and possibly write a cached page of an NFS file.
 710  *
 711  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 712  * things with a page scheduled for an RPC call (e.g. invalidate it).
 713  */
 714 int nfs_updatepage(struct file *file, struct page *page,
 715                 unsigned int offset, unsigned int count)
 716 {
 717         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 718         struct inode    *inode = page->mapping->host;
 719         int             status = 0;
 720
 721         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 722
 723         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
 724                 file->f_path.dentry->d_parent->d_name.name,
 725                 file->f_path.dentry->d_name.name, count,
 726                 (long long)(page_offset(page) +offset));
 727
 728         /* If we're not using byte range locks, and we know the page
 729          * is entirely in cache, it may be more efficient to avoid
 730          * fragmenting write requests.
 731          */
 732         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
 733                 count = max(count + offset, nfs_page_length(page));
 734                 offset = 0;
 735         }
 736
 737         status = nfs_writepage_setup(ctx, page, offset, count);
 738         __set_page_dirty_nobuffers(page);
 739
 740         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
 741                         status, (long long)i_size_read(inode));
 742         if (status < 0)
 743                 nfs_set_pageerror(page);
 744         return status;
 745 }
 746
 747 static void nfs_writepage_release(struct nfs_page *req)
 748 {
 749         nfs_end_page_writeback(req->wb_page);
 750
 751 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 752         if (!PageError(req->wb_page)) {
 753                 if (NFS_NEED_RESCHED(req)) {
 754                         nfs_redirty_request(req);
 755                         goto out;
 756                 } else if (NFS_NEED_COMMIT(req)) {
 757                         nfs_mark_request_commit(req);
 758                         goto out;
 759                 }
 760         }
 761         nfs_inode_remove_request(req);
 762
 763 out:
 764         nfs_clear_commit(req);
 765         nfs_clear_reschedule(req);
 766 #else
 767         nfs_inode_remove_request(req);
 768 #endif
 769         nfs_clear_page_writeback(req);
 770 }
 771
 772 static inline int flush_task_priority(int how)
 773 {
 774         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 775                 case FLUSH_HIGHPRI:
 776                         return RPC_PRIORITY_HIGH;
 777                 case FLUSH_LOWPRI:
 778                         return RPC_PRIORITY_LOW;
 779         }
 780         return RPC_PRIORITY_NORMAL;
 781 }
 782
 783 /*
 784  * Set up the argument/result storage required for the RPC call.
 785  */
 786 static void nfs_write_rpcsetup(struct nfs_page *req,
 787                 struct nfs_write_data *data,
 788                 const struct rpc_call_ops *call_ops,
 789                 unsigned int count, unsigned int offset,
 790                 int how)
 791 {
 792         struct inode            *inode;
 793         int flags;
 794
 795         /* Set up the RPC argument and reply structs
 796          * NB: take care not to mess about with data->commit et al. */
 797
 798         data->req = req;
 799         data->inode = inode = req->wb_context->dentry->d_inode;
 800         data->cred = req->wb_context->cred;
 801
 802         data->args.fh     = NFS_FH(inode);
 803         data->args.offset = req_offset(req) + offset;
 804         data->args.pgbase = req->wb_pgbase + offset;
 805         data->args.pages  = data->pagevec;
 806         data->args.count  = count;
 807         data->args.context = req->wb_context;
 808
 809         data->res.fattr   = &data->fattr;
 810         data->res.count   = count;
 811         data->res.verf    = &data->verf;
 812         nfs_fattr_init(&data->fattr);
 813
 814         /* Set up the initial task struct.  */
 815         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 816         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
 817         NFS_PROTO(inode)->write_setup(data, how);
 818
 819         data->task.tk_priority = flush_task_priority(how);
 820         data->task.tk_cookie = (unsigned long)inode;
 821
 822         dprintk("NFS: %5u initiated write call "
 823                 "(req %s/%Ld, %u bytes @ offset %Lu)\n",
 824                 data->task.tk_pid,
 825                 inode->i_sb->s_id,
 826                 (long long)NFS_FILEID(inode),
 827                 count,
 828                 (unsigned long long)data->args.offset);
 829 }
 830
 831 static void nfs_execute_write(struct nfs_write_data *data)
 832 {
 833         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
 834         sigset_t oldset;
 835
 836         rpc_clnt_sigmask(clnt, &oldset);
 837         rpc_execute(&data->task);
 838         rpc_clnt_sigunmask(clnt, &oldset);
 839 }
 840
 841 /*
 842  * Generate multiple small requests to write out a single
 843  * contiguous dirty area on one page.
 844  */
 845 static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
 846 {
 847         struct nfs_page *req = nfs_list_entry(head->next);
 848         struct page *page = req->wb_page;
 849         struct nfs_write_data *data;
 850         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 851         unsigned int offset;
 852         int requests = 0;
 853         LIST_HEAD(list);
 854
 855         nfs_list_remove_request(req);
 856
 857         nbytes = req->wb_bytes;
 858         do {
 859                 size_t len = min(nbytes, wsize);
 860
 861                 data = nfs_writedata_alloc(len);
 862                 if (!data)
 863                         goto out_bad;
 864                 list_add(&data->pages, &list);
 865                 requests++;
 866                 nbytes -= len;
 867         } while (nbytes != 0);
 868         atomic_set(&req->wb_complete, requests);
 869
 870         ClearPageError(page);
 871         offset = 0;
 872         nbytes = req->wb_bytes;
 873         do {
 874                 data = list_entry(list.next, struct nfs_write_data, pages);
 875                 list_del_init(&data->pages);
 876
 877                 data->pagevec[0] = page;
 878
 879                 if (nbytes > wsize) {
 880                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 881                                         wsize, offset, how);
 882                         offset += wsize;
 883                         nbytes -= wsize;
 884                 } else {
 885                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 886                                         nbytes, offset, how);
 887                         nbytes = 0;
 888                 }
 889                 nfs_execute_write(data);
 890         } while (nbytes != 0);
 891
 892         return 0;
 893
 894 out_bad:
 895         while (!list_empty(&list)) {
 896                 data = list_entry(list.next, struct nfs_write_data, pages);
 897                 list_del(&data->pages);
 898                 nfs_writedata_release(data);
 899         }
 900         nfs_end_page_writeback(req->wb_page);
 901         nfs_redirty_request(req);
 902         nfs_clear_page_writeback(req);
 903         return -ENOMEM;
 904 }
 905
 906 /*
 907  * Create an RPC task for the given write request and kick it.
 908  * The page must have been locked by the caller.
 909  *
 910  * It may happen that the page we're passed is not marked dirty.
 911  * This is the case if nfs_updatepage detects a conflicting request
 912  * that has been written but not committed.
 913  */
 914 static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
 915 {
 916         struct nfs_page         *req;
 917         struct page             **pages;
 918         struct nfs_write_data   *data;
 919         unsigned int            count;
 920
 921         data = nfs_writedata_alloc(NFS_SERVER(inode)->wsize);
 922         if (!data)
 923                 goto out_bad;
 924
 925         pages = data->pagevec;
 926         count = 0;
 927         while (!list_empty(head)) {
 928                 req = nfs_list_entry(head->next);
 929                 nfs_list_remove_request(req);
 930                 nfs_list_add_request(req, &data->pages);
 931                 ClearPageError(req->wb_page);
 932                 *pages++ = req->wb_page;
 933                 count += req->wb_bytes;
 934         }
 935         req = nfs_list_entry(data->pages.next);
 936
 937         /* Set up the argument struct */
 938         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 939
 940         nfs_execute_write(data);
 941         return 0;
 942  out_bad:
 943         while (!list_empty(head)) {
 944                 struct nfs_page *req = nfs_list_entry(head->next);
 945                 nfs_list_remove_request(req);
 946                 nfs_end_page_writeback(req->wb_page);
 947                 nfs_redirty_request(req);
 948                 nfs_clear_page_writeback(req);
 949         }
 950         return -ENOMEM;
 951 }
 952
 953 static int nfs_flush_list(struct inode *inode, struct list_head *head, int npages, int how)
 954 {
 955         LIST_HEAD(one_request);
 956         int (*flush_one)(struct inode *, struct list_head *, int);
 957         struct nfs_page *req;
 958         int wpages = NFS_SERVER(inode)->wpages;
 959         int wsize = NFS_SERVER(inode)->wsize;
 960         int error;
 961
 962         flush_one = nfs_flush_one;
 963         if (wsize < PAGE_CACHE_SIZE)
 964                 flush_one = nfs_flush_multi;
 965         /* For single writes, FLUSH_STABLE is more efficient */
 966         if (npages <= wpages && npages == NFS_I(inode)->npages
 967                         && nfs_list_entry(head->next)->wb_bytes <= wsize)
 968                 how |= FLUSH_STABLE;
 969
 970         do {
 971                 nfs_coalesce_requests(head, &one_request, wpages);
 972                 req = nfs_list_entry(one_request.next);
 973                 error = flush_one(inode, &one_request, how);
 974                 if (error < 0)
 975                         goto out_err;
 976         } while (!list_empty(head));
 977         return 0;
 978 out_err:
 979         while (!list_empty(head)) {
 980                 req = nfs_list_entry(head->next);
 981                 nfs_list_remove_request(req);
 982                 nfs_end_page_writeback(req->wb_page);
 983                 nfs_redirty_request(req);
 984                 nfs_clear_page_writeback(req);
 985         }
 986         return error;
 987 }
 988
 989 /*
 990  * Handle a write reply that flushed part of a page.
 991  */
 992 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
 993 {
 994         struct nfs_write_data   *data = calldata;
 995         struct nfs_page         *req = data->req;
 996         struct page             *page = req->wb_page;
 997
 998         dprintk("NFS: write (%s/%Ld %d@%Ld)",
 999                 req->wb_context->dentry->d_inode->i_sb->s_id,
1000                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1001                 req->wb_bytes,
1002                 (long long)req_offset(req));
1003
1004         if (nfs_writeback_done(task, data) != 0)
1005                 return;
1006
1007         if (task->tk_status < 0) {
1008                 nfs_set_pageerror(page);
1009                 req->wb_context->error = task->tk_status;
1010                 dprintk(", error = %d\n", task->tk_status);
1011         } else {
1012 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1013                 if (data->verf.committed < NFS_FILE_SYNC) {
1014                         if (!NFS_NEED_COMMIT(req)) {
1015                                 nfs_defer_commit(req);
1016                                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1017                                 dprintk(" defer commit\n");
1018                         } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1019                                 nfs_defer_reschedule(req);
1020                                 dprintk(" server reboot detected\n");
1021                         }
1022                 } else
1023 #endif
1024                         dprintk(" OK\n");
1025         }
1026
1027         if (atomic_dec_and_test(&req->wb_complete))
1028                 nfs_writepage_release(req);
1029 }
1030
1031 static const struct rpc_call_ops nfs_write_partial_ops = {
1032         .rpc_call_done = nfs_writeback_done_partial,
1033         .rpc_release = nfs_writedata_release,
1034 };
1035
1036 /*
1037  * Handle a write reply that flushes a whole page.
1038  *
1039  * FIXME: There is an inherent race with invalidate_inode_pages and
1040  *        writebacks since the page->count is kept > 1 for as long
1041  *        as the page has a write request pending.
1042  */
1043 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1044 {
1045         struct nfs_write_data   *data = calldata;
1046         struct nfs_page         *req;
1047         struct page             *page;
1048
1049         if (nfs_writeback_done(task, data) != 0)
1050                 return;
1051
1052         /* Update attributes as result of writeback. */
1053         while (!list_empty(&data->pages)) {
1054                 req = nfs_list_entry(data->pages.next);
1055                 nfs_list_remove_request(req);
1056                 page = req->wb_page;
1057
1058                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1059                         req->wb_context->dentry->d_inode->i_sb->s_id,
1060                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1061                         req->wb_bytes,
1062                         (long long)req_offset(req));
1063
1064                 if (task->tk_status < 0) {
1065                         nfs_set_pageerror(page);
1066                         req->wb_context->error = task->tk_status;
1067                         nfs_end_page_writeback(page);
1068                         nfs_inode_remove_request(req);
1069                         dprintk(", error = %d\n", task->tk_status);
1070                         goto next;
1071                 }
1072                 nfs_end_page_writeback(page);
1073
1074 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1075                 if (data->args.stable != NFS_UNSTABLE || data->verf.committed == NFS_FILE_SYNC) {
1076                         nfs_inode_remove_request(req);
1077                         dprintk(" OK\n");
1078                         goto next;
1079                 }
1080                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1081                 nfs_mark_request_commit(req);
1082                 dprintk(" marked for commit\n");
1083 #else
1084                 nfs_inode_remove_request(req);
1085 #endif
1086         next:
1087                 nfs_clear_page_writeback(req);
1088         }
1089 }
1090
1091 static const struct rpc_call_ops nfs_write_full_ops = {
1092         .rpc_call_done = nfs_writeback_done_full,
1093         .rpc_release = nfs_writedata_release,
1094 };
1095
1096
1097 /*
1098  * This function is called when the WRITE call is complete.
1099  */
1100 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1101 {
1102         struct nfs_writeargs    *argp = &data->args;
1103         struct nfs_writeres     *resp = &data->res;
1104         int status;
1105
1106         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1107                 task->tk_pid, task->tk_status);
1108
1109         /*
1110          * ->write_done will attempt to use post-op attributes to detect
1111          * conflicting writes by other clients.  A strict interpretation
1112          * of close-to-open would allow us to continue caching even if
1113          * another writer had changed the file, but some applications
1114          * depend on tighter cache coherency when writing.
1115          */
1116         status = NFS_PROTO(data->inode)->write_done(task, data);
1117         if (status != 0)
1118                 return status;
1119         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1120
1121 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1122         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1123                 /* We tried a write call, but the server did not
1124                  * commit data to stable storage even though we
1125                  * requested it.
1126                  * Note: There is a known bug in Tru64 < 5.0 in which
1127                  *       the server reports NFS_DATA_SYNC, but performs
1128                  *       NFS_FILE_SYNC. We therefore implement this checking
1129                  *       as a dprintk() in order to avoid filling syslog.
1130                  */
1131                 static unsigned long    complain;
1132
1133                 if (time_before(complain, jiffies)) {
1134                         dprintk("NFS: faulty NFS server %s:"
1135                                 " (committed = %d) != (stable = %d)\n",
1136                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1137                                 resp->verf->committed, argp->stable);
1138                         complain = jiffies + 300 * HZ;
1139                 }
1140         }
1141 #endif
1142         /* Is this a short write? */
1143         if (task->tk_status >= 0 && resp->count < argp->count) {
1144                 static unsigned long    complain;
1145
1146                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1147
1148                 /* Has the server at least made some progress? */
1149                 if (resp->count != 0) {
1150                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1151                         if (resp->verf->committed != NFS_UNSTABLE) {
1152                                 /* Resend from where the server left off */
1153                                 argp->offset += resp->count;
1154                                 argp->pgbase += resp->count;
1155                                 argp->count -= resp->count;
1156                         } else {
1157                                 /* Resend as a stable write in order to avoid
1158                                  * headaches in the case of a server crash.
1159                                  */
1160                                 argp->stable = NFS_FILE_SYNC;
1161                         }
1162                         rpc_restart_call(task);
1163                         return -EAGAIN;
1164                 }
1165                 if (time_before(complain, jiffies)) {
1166                         printk(KERN_WARNING
1167                                "NFS: Server wrote zero bytes, expected %u.\n",
1168                                         argp->count);
1169                         complain = jiffies + 300 * HZ;
1170                 }
1171                 /* Can't do anything about it except throw an error. */
1172                 task->tk_status = -EIO;
1173         }
1174         return 0;
1175 }
1176
1177
1178 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1179 void nfs_commit_release(void *wdata)
1180 {
1181         nfs_commit_free(wdata);
1182 }
1183
1184 /*
1185  * Set up the argument/result storage required for the RPC call.
1186  */
1187 static void nfs_commit_rpcsetup(struct list_head *head,
1188                 struct nfs_write_data *data,
1189                 int how)
1190 {
1191         struct nfs_page         *first;
1192         struct inode            *inode;
1193         int flags;
1194
1195         /* Set up the RPC argument and reply structs
1196          * NB: take care not to mess about with data->commit et al. */
1197
1198         list_splice_init(head, &data->pages);
1199         first = nfs_list_entry(data->pages.next);
1200         inode = first->wb_context->dentry->d_inode;
1201
1202         data->inode       = inode;
1203         data->cred        = first->wb_context->cred;
1204
1205         data->args.fh     = NFS_FH(data->inode);
1206         /* Note: we always request a commit of the entire inode */
1207         data->args.offset = 0;
1208         data->args.count  = 0;
1209         data->res.count   = 0;
1210         data->res.fattr   = &data->fattr;
1211         data->res.verf    = &data->verf;
1212         nfs_fattr_init(&data->fattr);
1213
1214         /* Set up the initial task struct.  */
1215         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1216         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1217         NFS_PROTO(inode)->commit_setup(data, how);
1218
1219         data->task.tk_priority = flush_task_priority(how);
1220         data->task.tk_cookie = (unsigned long)inode;
1221
1222         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1223 }
1224
1225 /*
1226  * Commit dirty pages
1227  */
1228 static int
1229 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1230 {
1231         struct nfs_write_data   *data;
1232         struct nfs_page         *req;
1233
1234         data = nfs_commit_alloc();
1235
1236         if (!data)
1237                 goto out_bad;
1238
1239         /* Set up the argument struct */
1240         nfs_commit_rpcsetup(head, data, how);
1241
1242         nfs_execute_write(data);
1243         return 0;
1244  out_bad:
1245         while (!list_empty(head)) {
1246                 req = nfs_list_entry(head->next);
1247                 nfs_list_remove_request(req);
1248                 nfs_mark_request_commit(req);
1249                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1250                 nfs_clear_page_writeback(req);
1251         }
1252         return -ENOMEM;
1253 }
1254
1255 /*
1256  * COMMIT call returned
1257  */
1258 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1259 {
1260         struct nfs_write_data   *data = calldata;
1261         struct nfs_page         *req;
1262
1263         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1264                                 task->tk_pid, task->tk_status);
1265
1266         /* Call the NFS version-specific code */
1267         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1268                 return;
1269
1270         while (!list_empty(&data->pages)) {
1271                 req = nfs_list_entry(data->pages.next);
1272                 nfs_list_remove_request(req);
1273                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1274
1275                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1276                         req->wb_context->dentry->d_inode->i_sb->s_id,
1277                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1278                         req->wb_bytes,
1279                         (long long)req_offset(req));
1280                 if (task->tk_status < 0) {
1281                         req->wb_context->error = task->tk_status;
1282                         nfs_inode_remove_request(req);
1283                         dprintk(", error = %d\n", task->tk_status);
1284                         goto next;
1285                 }
1286
1287                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1288                  * returned by the server against all stored verfs. */
1289                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1290                         /* We have a match */
1291                         nfs_inode_remove_request(req);
1292                         dprintk(" OK\n");
1293                         goto next;
1294                 }
1295                 /* We have a mismatch. Write the page again */
1296                 dprintk(" mismatch\n");
1297                 nfs_redirty_request(req);
1298         next:
1299                 nfs_clear_page_writeback(req);
1300         }
1301 }
1302
1303 static const struct rpc_call_ops nfs_commit_ops = {
1304         .rpc_call_done = nfs_commit_done,
1305         .rpc_release = nfs_commit_release,
1306 };
1307 #else
1308 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1309 {
1310         return 0;
1311 }
1312 #endif
1313
1314 static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1315 {
1316         struct nfs_inode *nfsi = NFS_I(mapping->host);
1317         LIST_HEAD(head);
1318         long res;
1319
1320         spin_lock(&nfsi->req_lock);
1321         res = nfs_scan_dirty(mapping, wbc, &head);
1322         spin_unlock(&nfsi->req_lock);
1323         if (res) {
1324                 int error = nfs_flush_list(mapping->host, &head, res, how);
1325                 if (error < 0)
1326                         return error;
1327         }
1328         return res;
1329 }
1330
1331 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1332 int nfs_commit_inode(struct inode *inode, int how)
1333 {
1334         struct nfs_inode *nfsi = NFS_I(inode);
1335         LIST_HEAD(head);
1336         int res;
1337
1338         spin_lock(&nfsi->req_lock);
1339         res = nfs_scan_commit(inode, &head, 0, 0);
1340         spin_unlock(&nfsi->req_lock);
1341         if (res) {
1342                 int error = nfs_commit_list(inode, &head, how);
1343                 if (error < 0)
1344                         return error;
1345         }
1346         return res;
1347 }
1348 #endif
1349
1350 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1351 {
1352         struct inode *inode = mapping->host;
1353         struct nfs_inode *nfsi = NFS_I(inode);
1354         unsigned long idx_start, idx_end;
1355         unsigned int npages = 0;
1356         LIST_HEAD(head);
1357         int nocommit = how & FLUSH_NOCOMMIT;
1358         long pages, ret;
1359
1360         /* FIXME */
1361         if (wbc->range_cyclic)
1362                 idx_start = 0;
1363         else {
1364                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1365                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1366                 if (idx_end > idx_start) {
1367                         unsigned long l_npages = 1 + idx_end - idx_start;
1368                         npages = l_npages;
1369                         if (sizeof(npages) != sizeof(l_npages) &&
1370                                         (unsigned long)npages != l_npages)
1371                                 npages = 0;
1372                 }
1373         }
1374         how &= ~FLUSH_NOCOMMIT;
1375         spin_lock(&nfsi->req_lock);
1376         do {
1377                 wbc->pages_skipped = 0;
1378                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1379                 if (ret != 0)
1380                         continue;
1381                 pages = nfs_scan_dirty(mapping, wbc, &head);
1382                 if (pages != 0) {
1383                         spin_unlock(&nfsi->req_lock);
1384                         if (how & FLUSH_INVALIDATE) {
1385                                 nfs_cancel_dirty_list(&head);
1386                                 ret = pages;
1387                         } else
1388                                 ret = nfs_flush_list(inode, &head, pages, how);
1389                         spin_lock(&nfsi->req_lock);
1390                         continue;
1391                 }
1392                 if (wbc->pages_skipped != 0)
1393                         continue;
1394                 if (nocommit)
1395                         break;
1396                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1397                 if (pages == 0) {
1398                         if (wbc->pages_skipped != 0)
1399                                 continue;
1400                         break;
1401                 }
1402                 if (how & FLUSH_INVALIDATE) {
1403                         spin_unlock(&nfsi->req_lock);
1404                         nfs_cancel_commit_list(&head);
1405                         ret = pages;
1406                         spin_lock(&nfsi->req_lock);
1407                         continue;
1408                 }
1409                 pages += nfs_scan_commit(inode, &head, 0, 0);
1410                 spin_unlock(&nfsi->req_lock);
1411                 ret = nfs_commit_list(inode, &head, how);
1412                 spin_lock(&nfsi->req_lock);
1413         } while (ret >= 0);
1414         spin_unlock(&nfsi->req_lock);
1415         return ret;
1416 }
1417
1418 /*
1419  * flush the inode to disk.
1420  */
1421 int nfs_wb_all(struct inode *inode)
1422 {
1423         struct address_space *mapping = inode->i_mapping;
1424         struct writeback_control wbc = {
1425                 .bdi = mapping->backing_dev_info,
1426                 .sync_mode = WB_SYNC_ALL,
1427                 .nr_to_write = LONG_MAX,
1428                 .for_writepages = 1,
1429                 .range_cyclic = 1,
1430         };
1431         int ret;
1432
1433         ret = generic_writepages(mapping, &wbc);
1434         if (ret < 0)
1435                 goto out;
1436         ret = nfs_sync_mapping_wait(mapping, &wbc, 0);
1437         if (ret >= 0)
1438                 return 0;
1439 out:
1440         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1441         return ret;
1442 }
1443
1444 int nfs_sync_mapping_range(struct address_space *mapping, loff_t range_start, loff_t range_end, int how)
1445 {
1446         struct writeback_control wbc = {
1447                 .bdi = mapping->backing_dev_info,
1448                 .sync_mode = WB_SYNC_ALL,
1449                 .nr_to_write = LONG_MAX,
1450                 .range_start = range_start,
1451                 .range_end = range_end,
1452                 .for_writepages = 1,
1453         };
1454         int ret;
1455
1456         if (!(how & FLUSH_NOWRITEPAGE)) {
1457                 ret = generic_writepages(mapping, &wbc);
1458                 if (ret < 0)
1459                         goto out;
1460         }
1461         ret = nfs_sync_mapping_wait(mapping, &wbc, how);
1462         if (ret >= 0)
1463                 return 0;
1464 out:
1465         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1466         return ret;
1467 }
1468
1469 int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)
1470 {
1471         loff_t range_start = page_offset(page);
1472         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1473         struct writeback_control wbc = {
1474                 .bdi = page->mapping->backing_dev_info,
1475                 .sync_mode = WB_SYNC_ALL,
1476                 .nr_to_write = LONG_MAX,
1477                 .range_start = range_start,
1478                 .range_end = range_end,
1479         };
1480         int ret;
1481
1482         BUG_ON(!PageLocked(page));
1483         if (!(how & FLUSH_NOWRITEPAGE) && clear_page_dirty_for_io(page)) {
1484                 ret = nfs_writepage_locked(page, &wbc);
1485                 if (ret < 0)
1486                         goto out;
1487         }
1488         if (!PagePrivate(page))
1489                 return 0;
1490         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1491         if (ret >= 0)
1492                 return 0;
1493 out:
1494         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1495         return ret;
1496 }
1497
1498 /*
1499  * Write back all requests on one page - we do this before reading it.
1500  */
1501 int nfs_wb_page(struct inode *inode, struct page* page)
1502 {
1503         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1504 }
1505
1506 int nfs_set_page_dirty(struct page *page)
1507 {
1508         struct nfs_page *req;
1509
1510         req = nfs_page_find_request(page);
1511         if (req != NULL) {
1512                 /* Mark any existing write requests for flushing */
1513                 set_bit(PG_NEED_FLUSH, &req->wb_flags);
1514                 nfs_release_request(req);
1515         }
1516         return __set_page_dirty_nobuffers(page);
1517 }
1518
1519
1520 int __init nfs_init_writepagecache(void)
1521 {
1522         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1523                                              sizeof(struct nfs_write_data),
1524                                              0, SLAB_HWCACHE_ALIGN,
1525                                              NULL, NULL);
1526         if (nfs_wdata_cachep == NULL)
1527                 return -ENOMEM;
1528
1529         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1530                                                      nfs_wdata_cachep);
1531         if (nfs_wdata_mempool == NULL)
1532                 return -ENOMEM;
1533
1534         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1535                                                       nfs_wdata_cachep);
1536         if (nfs_commit_mempool == NULL)
1537                 return -ENOMEM;
1538
1539         /*
1540          * NFS congestion size, scale with available memory.
1541          *
1542          *  64MB:    8192k
1543          * 128MB:   11585k
1544          * 256MB:   16384k
1545          * 512MB:   23170k
1546          *   1GB:   32768k
1547          *   2GB:   46340k
1548          *   4GB:   65536k
1549          *   8GB:   92681k
1550          *  16GB:  131072k
1551          *
1552          * This allows larger machines to have larger/more transfers.
1553          * Limit the default to 256M
1554          */
1555         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1556         if (nfs_congestion_kb > 256*1024)
1557                 nfs_congestion_kb = 256*1024;
1558
1559         return 0;
1560 }
1561
1562 void nfs_destroy_writepagecache(void)
1563 {
1564         mempool_destroy(nfs_commit_mempool);
1565         mempool_destroy(nfs_wdata_mempool);
1566         kmem_cache_destroy(nfs_wdata_cachep);
1567 }
1568