fs/nfs/write.c

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