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 #include <linux/migrate.h>
  17
  18 #include <linux/sunrpc/clnt.h>
  19 #include <linux/nfs_fs.h>
  20 #include <linux/nfs_mount.h>
  21 #include <linux/nfs_page.h>
  22 #include <linux/backing-dev.h>
  23
  24 #include <asm/uaccess.h>
  25
  26 #include "delegation.h"
  27 #include "internal.h"
  28 #include "iostat.h"
  29 #include "nfs4_fs.h"
  30 #include "fscache.h"
  31
  32 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  33
  34 #define MIN_POOL_WRITE          (32)
  35 #define MIN_POOL_COMMIT         (4)
  36
  37 /*
  38  * Local function declarations
  39  */
  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_commitdata_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                 p->res.seq_res.sr_slotid = NFS4_MAX_SLOT_TABLE;
  59         }
  60         return p;
  61 }
  62
  63 void nfs_commit_free(struct nfs_write_data *p)
  64 {
  65         if (p && (p->pagevec != &p->page_array[0]))
  66                 kfree(p->pagevec);
  67         mempool_free(p, nfs_commit_mempool);
  68 }
  69
  70 struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
  71 {
  72         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
  73
  74         if (p) {
  75                 memset(p, 0, sizeof(*p));
  76                 INIT_LIST_HEAD(&p->pages);
  77                 p->npages = pagecount;
  78                 p->res.seq_res.sr_slotid = NFS4_MAX_SLOT_TABLE;
  79                 if (pagecount <= ARRAY_SIZE(p->page_array))
  80                         p->pagevec = p->page_array;
  81                 else {
  82                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
  83                         if (!p->pagevec) {
  84                                 mempool_free(p, nfs_wdata_mempool);
  85                                 p = NULL;
  86                         }
  87                 }
  88         }
  89         return p;
  90 }
  91
  92 void nfs_writedata_free(struct nfs_write_data *p)
  93 {
  94         if (p && (p->pagevec != &p->page_array[0]))
  95                 kfree(p->pagevec);
  96         mempool_free(p, nfs_wdata_mempool);
  97 }
  98
  99 static void nfs_writedata_release(struct nfs_write_data *wdata)
 100 {
 101         put_nfs_open_context(wdata->args.context);
 102         nfs_writedata_free(wdata);
 103 }
 104
 105 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 106 {
 107         ctx->error = error;
 108         smp_wmb();
 109         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 110 }
 111
 112 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 113 {
 114         struct nfs_page *req = NULL;
 115
 116         if (PagePrivate(page)) {
 117                 req = (struct nfs_page *)page_private(page);
 118                 if (req != NULL)
 119                         kref_get(&req->wb_kref);
 120         }
 121         return req;
 122 }
 123
 124 static struct nfs_page *nfs_page_find_request(struct page *page)
 125 {
 126         struct inode *inode = page->mapping->host;
 127         struct nfs_page *req = NULL;
 128
 129         spin_lock(&inode->i_lock);
 130         req = nfs_page_find_request_locked(page);
 131         spin_unlock(&inode->i_lock);
 132         return req;
 133 }
 134
 135 /* Adjust the file length if we're writing beyond the end */
 136 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 137 {
 138         struct inode *inode = page->mapping->host;
 139         loff_t end, i_size;
 140         pgoff_t end_index;
 141
 142         spin_lock(&inode->i_lock);
 143         i_size = i_size_read(inode);
 144         end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 145         if (i_size > 0 && page->index < end_index)
 146                 goto out;
 147         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 148         if (i_size >= end)
 149                 goto out;
 150         i_size_write(inode, end);
 151         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 152 out:
 153         spin_unlock(&inode->i_lock);
 154 }
 155
 156 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 157 static void nfs_set_pageerror(struct page *page)
 158 {
 159         SetPageError(page);
 160         nfs_zap_mapping(page->mapping->host, page->mapping);
 161 }
 162
 163 /* We can set the PG_uptodate flag if we see that a write request
 164  * covers the full page.
 165  */
 166 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 167 {
 168         if (PageUptodate(page))
 169                 return;
 170         if (base != 0)
 171                 return;
 172         if (count != nfs_page_length(page))
 173                 return;
 174         SetPageUptodate(page);
 175 }
 176
 177 static int wb_priority(struct writeback_control *wbc)
 178 {
 179         if (wbc->for_reclaim)
 180                 return FLUSH_HIGHPRI | FLUSH_STABLE;
 181         if (wbc->for_kupdate || wbc->for_background)
 182                 return FLUSH_LOWPRI;
 183         return 0;
 184 }
 185
 186 /*
 187  * NFS congestion control
 188  */
 189
 190 int nfs_congestion_kb;
 191
 192 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 193 #define NFS_CONGESTION_OFF_THRESH       \
 194         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 195
 196 static int nfs_set_page_writeback(struct page *page)
 197 {
 198         int ret = test_set_page_writeback(page);
 199
 200         if (!ret) {
 201                 struct inode *inode = page->mapping->host;
 202                 struct nfs_server *nfss = NFS_SERVER(inode);
 203
 204                 if (atomic_long_inc_return(&nfss->writeback) >
 205                                 NFS_CONGESTION_ON_THRESH) {
 206                         set_bdi_congested(&nfss->backing_dev_info,
 207                                                 BLK_RW_ASYNC);
 208                 }
 209         }
 210         return ret;
 211 }
 212
 213 static void nfs_end_page_writeback(struct page *page)
 214 {
 215         struct inode *inode = page->mapping->host;
 216         struct nfs_server *nfss = NFS_SERVER(inode);
 217
 218         end_page_writeback(page);
 219         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 220                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
 221 }
 222
 223 static struct nfs_page *nfs_find_and_lock_request(struct page *page)
 224 {
 225         struct inode *inode = page->mapping->host;
 226         struct nfs_page *req;
 227         int ret;
 228
 229         spin_lock(&inode->i_lock);
 230         for (;;) {
 231                 req = nfs_page_find_request_locked(page);
 232                 if (req == NULL)
 233                         break;
 234                 if (nfs_set_page_tag_locked(req))
 235                         break;
 236                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 237                  *       then the call to nfs_set_page_tag_locked() will always
 238                  *       succeed provided that someone hasn't already marked the
 239                  *       request as dirty (in which case we don't care).
 240                  */
 241                 spin_unlock(&inode->i_lock);
 242                 ret = nfs_wait_on_request(req);
 243                 nfs_release_request(req);
 244                 if (ret != 0)
 245                         return ERR_PTR(ret);
 246                 spin_lock(&inode->i_lock);
 247         }
 248         spin_unlock(&inode->i_lock);
 249         return req;
 250 }
 251
 252 /*
 253  * Find an associated nfs write request, and prepare to flush it out
 254  * May return an error if the user signalled nfs_wait_on_request().
 255  */
 256 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 257                                 struct page *page)
 258 {
 259         struct nfs_page *req;
 260         int ret = 0;
 261
 262         req = nfs_find_and_lock_request(page);
 263         if (!req)
 264                 goto out;
 265         ret = PTR_ERR(req);
 266         if (IS_ERR(req))
 267                 goto out;
 268
 269         ret = nfs_set_page_writeback(page);
 270         BUG_ON(ret != 0);
 271         BUG_ON(test_bit(PG_CLEAN, &req->wb_flags));
 272
 273         if (!nfs_pageio_add_request(pgio, req)) {
 274                 nfs_redirty_request(req);
 275                 ret = pgio->pg_error;
 276         }
 277 out:
 278         return ret;
 279 }
 280
 281 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 282 {
 283         struct inode *inode = page->mapping->host;
 284
 285         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 286         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 287
 288         nfs_pageio_cond_complete(pgio, page->index);
 289         return nfs_page_async_flush(pgio, page);
 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_pageio_descriptor pgio;
 298         int err;
 299
 300         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
 301         err = nfs_do_writepage(page, wbc, &pgio);
 302         nfs_pageio_complete(&pgio);
 303         if (err < 0)
 304                 return err;
 305         if (pgio.pg_error < 0)
 306                 return pgio.pg_error;
 307         return 0;
 308 }
 309
 310 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 311 {
 312         int ret;
 313
 314         ret = nfs_writepage_locked(page, wbc);
 315         unlock_page(page);
 316         return ret;
 317 }
 318
 319 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 320 {
 321         int ret;
 322
 323         ret = nfs_do_writepage(page, wbc, data);
 324         unlock_page(page);
 325         return ret;
 326 }
 327
 328 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 329 {
 330         struct inode *inode = mapping->host;
 331         unsigned long *bitlock = &NFS_I(inode)->flags;
 332         struct nfs_pageio_descriptor pgio;
 333         int err;
 334
 335         /* Stop dirtying of new pages while we sync */
 336         err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
 337                         nfs_wait_bit_killable, TASK_KILLABLE);
 338         if (err)
 339                 goto out_err;
 340
 341         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 342
 343         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
 344         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 345         nfs_pageio_complete(&pgio);
 346
 347         clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
 348         smp_mb__after_clear_bit();
 349         wake_up_bit(bitlock, NFS_INO_FLUSHING);
 350
 351         if (err < 0)
 352                 goto out_err;
 353         err = pgio.pg_error;
 354         if (err < 0)
 355                 goto out_err;
 356         return 0;
 357 out_err:
 358         return err;
 359 }
 360
 361 /*
 362  * Insert a write request into an inode
 363  */
 364 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 365 {
 366         struct nfs_inode *nfsi = NFS_I(inode);
 367         int error;
 368
 369         error = radix_tree_preload(GFP_NOFS);
 370         if (error != 0)
 371                 goto out;
 372
 373         /* Lock the request! */
 374         nfs_lock_request_dontget(req);
 375
 376         spin_lock(&inode->i_lock);
 377         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 378         BUG_ON(error);
 379         if (!nfsi->npages) {
 380                 igrab(inode);
 381                 if (nfs_have_delegation(inode, FMODE_WRITE))
 382                         nfsi->change_attr++;
 383         }
 384         SetPagePrivate(req->wb_page);
 385         set_page_private(req->wb_page, (unsigned long)req);
 386         nfsi->npages++;
 387         kref_get(&req->wb_kref);
 388         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
 389                                 NFS_PAGE_TAG_LOCKED);
 390         spin_unlock(&inode->i_lock);
 391         radix_tree_preload_end();
 392 out:
 393         return error;
 394 }
 395
 396 /*
 397  * Remove a write request from an inode
 398  */
 399 static void nfs_inode_remove_request(struct nfs_page *req)
 400 {
 401         struct inode *inode = req->wb_context->path.dentry->d_inode;
 402         struct nfs_inode *nfsi = NFS_I(inode);
 403
 404         BUG_ON (!NFS_WBACK_BUSY(req));
 405
 406         spin_lock(&inode->i_lock);
 407         set_page_private(req->wb_page, 0);
 408         ClearPagePrivate(req->wb_page);
 409         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 410         nfsi->npages--;
 411         if (!nfsi->npages) {
 412                 spin_unlock(&inode->i_lock);
 413                 iput(inode);
 414         } else
 415                 spin_unlock(&inode->i_lock);
 416         nfs_clear_request(req);
 417         nfs_release_request(req);
 418 }
 419
 420 static void
 421 nfs_mark_request_dirty(struct nfs_page *req)
 422 {
 423         __set_page_dirty_nobuffers(req->wb_page);
 424 }
 425
 426 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 427 /*
 428  * Add a request to the inode's commit list.
 429  */
 430 static void
 431 nfs_mark_request_commit(struct nfs_page *req)
 432 {
 433         struct inode *inode = req->wb_context->path.dentry->d_inode;
 434         struct nfs_inode *nfsi = NFS_I(inode);
 435
 436         spin_lock(&inode->i_lock);
 437         set_bit(PG_CLEAN, &(req)->wb_flags);
 438         radix_tree_tag_set(&nfsi->nfs_page_tree,
 439                         req->wb_index,
 440                         NFS_PAGE_TAG_COMMIT);
 441         nfsi->ncommit++;
 442         spin_unlock(&inode->i_lock);
 443         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 444         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 445         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 446 }
 447
 448 static int
 449 nfs_clear_request_commit(struct nfs_page *req)
 450 {
 451         struct page *page = req->wb_page;
 452
 453         if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
 454                 dec_zone_page_state(page, NR_UNSTABLE_NFS);
 455                 dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 456                 return 1;
 457         }
 458         return 0;
 459 }
 460
 461 static inline
 462 int nfs_write_need_commit(struct nfs_write_data *data)
 463 {
 464         return data->verf.committed != NFS_FILE_SYNC;
 465 }
 466
 467 static inline
 468 int nfs_reschedule_unstable_write(struct nfs_page *req)
 469 {
 470         if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 471                 nfs_mark_request_commit(req);
 472                 return 1;
 473         }
 474         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 475                 nfs_mark_request_dirty(req);
 476                 return 1;
 477         }
 478         return 0;
 479 }
 480 #else
 481 static inline void
 482 nfs_mark_request_commit(struct nfs_page *req)
 483 {
 484 }
 485
 486 static inline int
 487 nfs_clear_request_commit(struct nfs_page *req)
 488 {
 489         return 0;
 490 }
 491
 492 static inline
 493 int nfs_write_need_commit(struct nfs_write_data *data)
 494 {
 495         return 0;
 496 }
 497
 498 static inline
 499 int nfs_reschedule_unstable_write(struct nfs_page *req)
 500 {
 501         return 0;
 502 }
 503 #endif
 504
 505 /*
 506  * Wait for a request to complete.
 507  *
 508  * Interruptible by fatal signals only.
 509  */
 510 static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, unsigned int npages)
 511 {
 512         struct nfs_inode *nfsi = NFS_I(inode);
 513         struct nfs_page *req;
 514         pgoff_t idx_end, next;
 515         unsigned int            res = 0;
 516         int                     error;
 517
 518         if (npages == 0)
 519                 idx_end = ~0;
 520         else
 521                 idx_end = idx_start + npages - 1;
 522
 523         next = idx_start;
 524         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_LOCKED)) {
 525                 if (req->wb_index > idx_end)
 526                         break;
 527
 528                 next = req->wb_index + 1;
 529                 BUG_ON(!NFS_WBACK_BUSY(req));
 530
 531                 kref_get(&req->wb_kref);
 532                 spin_unlock(&inode->i_lock);
 533                 error = nfs_wait_on_request(req);
 534                 nfs_release_request(req);
 535                 spin_lock(&inode->i_lock);
 536                 if (error < 0)
 537                         return error;
 538                 res++;
 539         }
 540         return res;
 541 }
 542
 543 static void nfs_cancel_commit_list(struct list_head *head)
 544 {
 545         struct nfs_page *req;
 546
 547         while(!list_empty(head)) {
 548                 req = nfs_list_entry(head->next);
 549                 nfs_list_remove_request(req);
 550                 nfs_clear_request_commit(req);
 551                 nfs_inode_remove_request(req);
 552                 nfs_unlock_request(req);
 553         }
 554 }
 555
 556 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 557 static int
 558 nfs_need_commit(struct nfs_inode *nfsi)
 559 {
 560         return radix_tree_tagged(&nfsi->nfs_page_tree, NFS_PAGE_TAG_COMMIT);
 561 }
 562
 563 /*
 564  * nfs_scan_commit - Scan an inode for commit requests
 565  * @inode: NFS inode to scan
 566  * @dst: destination list
 567  * @idx_start: lower bound of page->index to scan.
 568  * @npages: idx_start + npages sets the upper bound to scan.
 569  *
 570  * Moves requests from the inode's 'commit' request list.
 571  * The requests are *not* checked to ensure that they form a contiguous set.
 572  */
 573 static int
 574 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 575 {
 576         struct nfs_inode *nfsi = NFS_I(inode);
 577         int ret;
 578
 579         if (!nfs_need_commit(nfsi))
 580                 return 0;
 581
 582         ret = nfs_scan_list(nfsi, dst, idx_start, npages, NFS_PAGE_TAG_COMMIT);
 583         if (ret > 0)
 584                 nfsi->ncommit -= ret;
 585         return ret;
 586 }
 587 #else
 588 static inline int nfs_need_commit(struct nfs_inode *nfsi)
 589 {
 590         return 0;
 591 }
 592
 593 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 594 {
 595         return 0;
 596 }
 597 #endif
 598
 599 /*
 600  * Search for an existing write request, and attempt to update
 601  * it to reflect a new dirty region on a given page.
 602  *
 603  * If the attempt fails, then the existing request is flushed out
 604  * to disk.
 605  */
 606 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
 607                 struct page *page,
 608                 unsigned int offset,
 609                 unsigned int bytes)
 610 {
 611         struct nfs_page *req;
 612         unsigned int rqend;
 613         unsigned int end;
 614         int error;
 615
 616         if (!PagePrivate(page))
 617                 return NULL;
 618
 619         end = offset + bytes;
 620         spin_lock(&inode->i_lock);
 621
 622         for (;;) {
 623                 req = nfs_page_find_request_locked(page);
 624                 if (req == NULL)
 625                         goto out_unlock;
 626
 627                 rqend = req->wb_offset + req->wb_bytes;
 628                 /*
 629                  * Tell the caller to flush out the request if
 630                  * the offsets are non-contiguous.
 631                  * Note: nfs_flush_incompatible() will already
 632                  * have flushed out requests having wrong owners.
 633                  */
 634                 if (offset > rqend
 635                     || end < req->wb_offset)
 636                         goto out_flushme;
 637
 638                 if (nfs_set_page_tag_locked(req))
 639                         break;
 640
 641                 /* The request is locked, so wait and then retry */
 642                 spin_unlock(&inode->i_lock);
 643                 error = nfs_wait_on_request(req);
 644                 nfs_release_request(req);
 645                 if (error != 0)
 646                         goto out_err;
 647                 spin_lock(&inode->i_lock);
 648         }
 649
 650         if (nfs_clear_request_commit(req) &&
 651                         radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
 652                                 req->wb_index, NFS_PAGE_TAG_COMMIT) != NULL)
 653                 NFS_I(inode)->ncommit--;
 654
 655         /* Okay, the request matches. Update the region */
 656         if (offset < req->wb_offset) {
 657                 req->wb_offset = offset;
 658                 req->wb_pgbase = offset;
 659         }
 660         if (end > rqend)
 661                 req->wb_bytes = end - req->wb_offset;
 662         else
 663                 req->wb_bytes = rqend - req->wb_offset;
 664 out_unlock:
 665         spin_unlock(&inode->i_lock);
 666         return req;
 667 out_flushme:
 668         spin_unlock(&inode->i_lock);
 669         nfs_release_request(req);
 670         error = nfs_wb_page(inode, page);
 671 out_err:
 672         return ERR_PTR(error);
 673 }
 674
 675 /*
 676  * Try to update an existing write request, or create one if there is none.
 677  *
 678  * Note: Should always be called with the Page Lock held to prevent races
 679  * if we have to add a new request. Also assumes that the caller has
 680  * already called nfs_flush_incompatible() if necessary.
 681  */
 682 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
 683                 struct page *page, unsigned int offset, unsigned int bytes)
 684 {
 685         struct inode *inode = page->mapping->host;
 686         struct nfs_page *req;
 687         int error;
 688
 689         req = nfs_try_to_update_request(inode, page, offset, bytes);
 690         if (req != NULL)
 691                 goto out;
 692         req = nfs_create_request(ctx, inode, page, offset, bytes);
 693         if (IS_ERR(req))
 694                 goto out;
 695         error = nfs_inode_add_request(inode, req);
 696         if (error != 0) {
 697                 nfs_release_request(req);
 698                 req = ERR_PTR(error);
 699         }
 700 out:
 701         return req;
 702 }
 703
 704 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 705                 unsigned int offset, unsigned int count)
 706 {
 707         struct nfs_page *req;
 708
 709         req = nfs_setup_write_request(ctx, page, offset, count);
 710         if (IS_ERR(req))
 711                 return PTR_ERR(req);
 712         /* Update file length */
 713         nfs_grow_file(page, offset, count);
 714         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
 715         nfs_clear_page_tag_locked(req);
 716         return 0;
 717 }
 718
 719 int nfs_flush_incompatible(struct file *file, struct page *page)
 720 {
 721         struct nfs_open_context *ctx = nfs_file_open_context(file);
 722         struct nfs_page *req;
 723         int do_flush, status;
 724         /*
 725          * Look for a request corresponding to this page. If there
 726          * is one, and it belongs to another file, we flush it out
 727          * before we try to copy anything into the page. Do this
 728          * due to the lack of an ACCESS-type call in NFSv2.
 729          * Also do the same if we find a request from an existing
 730          * dropped page.
 731          */
 732         do {
 733                 req = nfs_page_find_request(page);
 734                 if (req == NULL)
 735                         return 0;
 736                 do_flush = req->wb_page != page || req->wb_context != ctx;
 737                 nfs_release_request(req);
 738                 if (!do_flush)
 739                         return 0;
 740                 status = nfs_wb_page(page->mapping->host, page);
 741         } while (status == 0);
 742         return status;
 743 }
 744
 745 /*
 746  * If the page cache is marked as unsafe or invalid, then we can't rely on
 747  * the PageUptodate() flag. In this case, we will need to turn off
 748  * write optimisations that depend on the page contents being correct.
 749  */
 750 static int nfs_write_pageuptodate(struct page *page, struct inode *inode)
 751 {
 752         return PageUptodate(page) &&
 753                 !(NFS_I(inode)->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA));
 754 }
 755
 756 /*
 757  * Update and possibly write a cached page of an NFS file.
 758  *
 759  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 760  * things with a page scheduled for an RPC call (e.g. invalidate it).
 761  */
 762 int nfs_updatepage(struct file *file, struct page *page,
 763                 unsigned int offset, unsigned int count)
 764 {
 765         struct nfs_open_context *ctx = nfs_file_open_context(file);
 766         struct inode    *inode = page->mapping->host;
 767         int             status = 0;
 768
 769         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 770
 771         dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
 772                 file->f_path.dentry->d_parent->d_name.name,
 773                 file->f_path.dentry->d_name.name, count,
 774                 (long long)(page_offset(page) + offset));
 775
 776         /* If we're not using byte range locks, and we know the page
 777          * is up to date, it may be more efficient to extend the write
 778          * to cover the entire page in order to avoid fragmentation
 779          * inefficiencies.
 780          */
 781         if (nfs_write_pageuptodate(page, inode) &&
 782                         inode->i_flock == NULL &&
 783                         !(file->f_flags & O_DSYNC)) {
 784                 count = max(count + offset, nfs_page_length(page));
 785                 offset = 0;
 786         }
 787
 788         status = nfs_writepage_setup(ctx, page, offset, count);
 789         if (status < 0)
 790                 nfs_set_pageerror(page);
 791         else
 792                 __set_page_dirty_nobuffers(page);
 793
 794         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 795                         status, (long long)i_size_read(inode));
 796         return status;
 797 }
 798
 799 static void nfs_writepage_release(struct nfs_page *req)
 800 {
 801
 802         if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req)) {
 803                 nfs_end_page_writeback(req->wb_page);
 804                 nfs_inode_remove_request(req);
 805         } else
 806                 nfs_end_page_writeback(req->wb_page);
 807         nfs_clear_page_tag_locked(req);
 808 }
 809
 810 static int flush_task_priority(int how)
 811 {
 812         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 813                 case FLUSH_HIGHPRI:
 814                         return RPC_PRIORITY_HIGH;
 815                 case FLUSH_LOWPRI:
 816                         return RPC_PRIORITY_LOW;
 817         }
 818         return RPC_PRIORITY_NORMAL;
 819 }
 820
 821 /*
 822  * Set up the argument/result storage required for the RPC call.
 823  */
 824 static int nfs_write_rpcsetup(struct nfs_page *req,
 825                 struct nfs_write_data *data,
 826                 const struct rpc_call_ops *call_ops,
 827                 unsigned int count, unsigned int offset,
 828                 int how)
 829 {
 830         struct inode *inode = req->wb_context->path.dentry->d_inode;
 831         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 832         int priority = flush_task_priority(how);
 833         struct rpc_task *task;
 834         struct rpc_message msg = {
 835                 .rpc_argp = &data->args,
 836                 .rpc_resp = &data->res,
 837                 .rpc_cred = req->wb_context->cred,
 838         };
 839         struct rpc_task_setup task_setup_data = {
 840                 .rpc_client = NFS_CLIENT(inode),
 841                 .task = &data->task,
 842                 .rpc_message = &msg,
 843                 .callback_ops = call_ops,
 844                 .callback_data = data,
 845                 .workqueue = nfsiod_workqueue,
 846                 .flags = flags,
 847                 .priority = priority,
 848         };
 849
 850         /* Set up the RPC argument and reply structs
 851          * NB: take care not to mess about with data->commit et al. */
 852
 853         data->req = req;
 854         data->inode = inode = req->wb_context->path.dentry->d_inode;
 855         data->cred = msg.rpc_cred;
 856
 857         data->args.fh     = NFS_FH(inode);
 858         data->args.offset = req_offset(req) + offset;
 859         data->args.pgbase = req->wb_pgbase + offset;
 860         data->args.pages  = data->pagevec;
 861         data->args.count  = count;
 862         data->args.context = get_nfs_open_context(req->wb_context);
 863         data->args.stable  = NFS_UNSTABLE;
 864         if (how & FLUSH_STABLE) {
 865                 data->args.stable = NFS_DATA_SYNC;
 866                 if (!nfs_need_commit(NFS_I(inode)))
 867                         data->args.stable = NFS_FILE_SYNC;
 868         }
 869
 870         data->res.fattr   = &data->fattr;
 871         data->res.count   = count;
 872         data->res.verf    = &data->verf;
 873         nfs_fattr_init(&data->fattr);
 874
 875         /* Set up the initial task struct.  */
 876         NFS_PROTO(inode)->write_setup(data, &msg);
 877
 878         dprintk("NFS: %5u initiated write call "
 879                 "(req %s/%lld, %u bytes @ offset %llu)\n",
 880                 data->task.tk_pid,
 881                 inode->i_sb->s_id,
 882                 (long long)NFS_FILEID(inode),
 883                 count,
 884                 (unsigned long long)data->args.offset);
 885
 886         task = rpc_run_task(&task_setup_data);
 887         if (IS_ERR(task))
 888                 return PTR_ERR(task);
 889         rpc_put_task(task);
 890         return 0;
 891 }
 892
 893 /* If a nfs_flush_* function fails, it should remove reqs from @head and
 894  * call this on each, which will prepare them to be retried on next
 895  * writeback using standard nfs.
 896  */
 897 static void nfs_redirty_request(struct nfs_page *req)
 898 {
 899         nfs_mark_request_dirty(req);
 900         nfs_end_page_writeback(req->wb_page);
 901         nfs_clear_page_tag_locked(req);
 902 }
 903
 904 /*
 905  * Generate multiple small requests to write out a single
 906  * contiguous dirty area on one page.
 907  */
 908 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 909 {
 910         struct nfs_page *req = nfs_list_entry(head->next);
 911         struct page *page = req->wb_page;
 912         struct nfs_write_data *data;
 913         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 914         unsigned int offset;
 915         int requests = 0;
 916         int ret = 0;
 917         LIST_HEAD(list);
 918
 919         nfs_list_remove_request(req);
 920
 921         nbytes = count;
 922         do {
 923                 size_t len = min(nbytes, wsize);
 924
 925                 data = nfs_writedata_alloc(1);
 926                 if (!data)
 927                         goto out_bad;
 928                 list_add(&data->pages, &list);
 929                 requests++;
 930                 nbytes -= len;
 931         } while (nbytes != 0);
 932         atomic_set(&req->wb_complete, requests);
 933
 934         ClearPageError(page);
 935         offset = 0;
 936         nbytes = count;
 937         do {
 938                 int ret2;
 939
 940                 data = list_entry(list.next, struct nfs_write_data, pages);
 941                 list_del_init(&data->pages);
 942
 943                 data->pagevec[0] = page;
 944
 945                 if (nbytes < wsize)
 946                         wsize = nbytes;
 947                 ret2 = nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 948                                    wsize, offset, how);
 949                 if (ret == 0)
 950                         ret = ret2;
 951                 offset += wsize;
 952                 nbytes -= wsize;
 953         } while (nbytes != 0);
 954
 955         return ret;
 956
 957 out_bad:
 958         while (!list_empty(&list)) {
 959                 data = list_entry(list.next, struct nfs_write_data, pages);
 960                 list_del(&data->pages);
 961                 nfs_writedata_release(data);
 962         }
 963         nfs_redirty_request(req);
 964         return -ENOMEM;
 965 }
 966
 967 /*
 968  * Create an RPC task for the given write request and kick it.
 969  * The page must have been locked by the caller.
 970  *
 971  * It may happen that the page we're passed is not marked dirty.
 972  * This is the case if nfs_updatepage detects a conflicting request
 973  * that has been written but not committed.
 974  */
 975 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 976 {
 977         struct nfs_page         *req;
 978         struct page             **pages;
 979         struct nfs_write_data   *data;
 980
 981         data = nfs_writedata_alloc(npages);
 982         if (!data)
 983                 goto out_bad;
 984
 985         pages = data->pagevec;
 986         while (!list_empty(head)) {
 987                 req = nfs_list_entry(head->next);
 988                 nfs_list_remove_request(req);
 989                 nfs_list_add_request(req, &data->pages);
 990                 ClearPageError(req->wb_page);
 991                 *pages++ = req->wb_page;
 992         }
 993         req = nfs_list_entry(data->pages.next);
 994
 995         /* Set up the argument struct */
 996         return nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 997  out_bad:
 998         while (!list_empty(head)) {
 999                 req = nfs_list_entry(head->next);
1000                 nfs_list_remove_request(req);
1001                 nfs_redirty_request(req);
1002         }
1003         return -ENOMEM;
1004 }
1005
1006 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1007                                   struct inode *inode, int ioflags)
1008 {
1009         size_t wsize = NFS_SERVER(inode)->wsize;
1010
1011         if (wsize < PAGE_CACHE_SIZE)
1012                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
1013         else
1014                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
1015 }
1016
1017 /*
1018  * Handle a write reply that flushed part of a page.
1019  */
1020 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
1021 {
1022         struct nfs_write_data   *data = calldata;
1023
1024         dprintk("NFS: %5u write(%s/%lld %d@%lld)",
1025                 task->tk_pid,
1026                 data->req->wb_context->path.dentry->d_inode->i_sb->s_id,
1027                 (long long)
1028                   NFS_FILEID(data->req->wb_context->path.dentry->d_inode),
1029                 data->req->wb_bytes, (long long)req_offset(data->req));
1030
1031         nfs_writeback_done(task, data);
1032 }
1033
1034 static void nfs_writeback_release_partial(void *calldata)
1035 {
1036         struct nfs_write_data   *data = calldata;
1037         struct nfs_page         *req = data->req;
1038         struct page             *page = req->wb_page;
1039         int status = data->task.tk_status;
1040
1041         if (status < 0) {
1042                 nfs_set_pageerror(page);
1043                 nfs_context_set_write_error(req->wb_context, status);
1044                 dprintk(", error = %d\n", status);
1045                 goto out;
1046         }
1047
1048         if (nfs_write_need_commit(data)) {
1049                 struct inode *inode = page->mapping->host;
1050
1051                 spin_lock(&inode->i_lock);
1052                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
1053                         /* Do nothing we need to resend the writes */
1054                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1055                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1056                         dprintk(" defer commit\n");
1057                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1058                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
1059                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
1060                         dprintk(" server reboot detected\n");
1061                 }
1062                 spin_unlock(&inode->i_lock);
1063         } else
1064                 dprintk(" OK\n");
1065
1066 out:
1067         if (atomic_dec_and_test(&req->wb_complete))
1068                 nfs_writepage_release(req);
1069         nfs_writedata_release(calldata);
1070 }
1071
1072 #if defined(CONFIG_NFS_V4_1)
1073 void nfs_write_prepare(struct rpc_task *task, void *calldata)
1074 {
1075         struct nfs_write_data *data = calldata;
1076         struct nfs_client *clp = (NFS_SERVER(data->inode))->nfs_client;
1077
1078         if (nfs4_setup_sequence(clp, &data->args.seq_args,
1079                                 &data->res.seq_res, 1, task))
1080                 return;
1081         rpc_call_start(task);
1082 }
1083 #endif /* CONFIG_NFS_V4_1 */
1084
1085 static const struct rpc_call_ops nfs_write_partial_ops = {
1086 #if defined(CONFIG_NFS_V4_1)
1087         .rpc_call_prepare = nfs_write_prepare,
1088 #endif /* CONFIG_NFS_V4_1 */
1089         .rpc_call_done = nfs_writeback_done_partial,
1090         .rpc_release = nfs_writeback_release_partial,
1091 };
1092
1093 /*
1094  * Handle a write reply that flushes a whole page.
1095  *
1096  * FIXME: There is an inherent race with invalidate_inode_pages and
1097  *        writebacks since the page->count is kept > 1 for as long
1098  *        as the page has a write request pending.
1099  */
1100 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1101 {
1102         struct nfs_write_data   *data = calldata;
1103
1104         nfs_writeback_done(task, data);
1105 }
1106
1107 static void nfs_writeback_release_full(void *calldata)
1108 {
1109         struct nfs_write_data   *data = calldata;
1110         int status = data->task.tk_status;
1111
1112         /* Update attributes as result of writeback. */
1113         while (!list_empty(&data->pages)) {
1114                 struct nfs_page *req = nfs_list_entry(data->pages.next);
1115                 struct page *page = req->wb_page;
1116
1117                 nfs_list_remove_request(req);
1118
1119                 dprintk("NFS: %5u write (%s/%lld %d@%lld)",
1120                         data->task.tk_pid,
1121                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1122                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1123                         req->wb_bytes,
1124                         (long long)req_offset(req));
1125
1126                 if (status < 0) {
1127                         nfs_set_pageerror(page);
1128                         nfs_context_set_write_error(req->wb_context, status);
1129                         dprintk(", error = %d\n", status);
1130                         goto remove_request;
1131                 }
1132
1133                 if (nfs_write_need_commit(data)) {
1134                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1135                         nfs_mark_request_commit(req);
1136                         nfs_end_page_writeback(page);
1137                         dprintk(" marked for commit\n");
1138                         goto next;
1139                 }
1140                 dprintk(" OK\n");
1141 remove_request:
1142                 nfs_end_page_writeback(page);
1143                 nfs_inode_remove_request(req);
1144         next:
1145                 nfs_clear_page_tag_locked(req);
1146         }
1147         nfs_writedata_release(calldata);
1148 }
1149
1150 static const struct rpc_call_ops nfs_write_full_ops = {
1151 #if defined(CONFIG_NFS_V4_1)
1152         .rpc_call_prepare = nfs_write_prepare,
1153 #endif /* CONFIG_NFS_V4_1 */
1154         .rpc_call_done = nfs_writeback_done_full,
1155         .rpc_release = nfs_writeback_release_full,
1156 };
1157
1158
1159 /*
1160  * This function is called when the WRITE call is complete.
1161  */
1162 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1163 {
1164         struct nfs_writeargs    *argp = &data->args;
1165         struct nfs_writeres     *resp = &data->res;
1166         struct nfs_server       *server = NFS_SERVER(data->inode);
1167         int status;
1168
1169         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1170                 task->tk_pid, task->tk_status);
1171
1172         /*
1173          * ->write_done will attempt to use post-op attributes to detect
1174          * conflicting writes by other clients.  A strict interpretation
1175          * of close-to-open would allow us to continue caching even if
1176          * another writer had changed the file, but some applications
1177          * depend on tighter cache coherency when writing.
1178          */
1179         status = NFS_PROTO(data->inode)->write_done(task, data);
1180         if (status != 0)
1181                 return status;
1182         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1183
1184 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1185         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1186                 /* We tried a write call, but the server did not
1187                  * commit data to stable storage even though we
1188                  * requested it.
1189                  * Note: There is a known bug in Tru64 < 5.0 in which
1190                  *       the server reports NFS_DATA_SYNC, but performs
1191                  *       NFS_FILE_SYNC. We therefore implement this checking
1192                  *       as a dprintk() in order to avoid filling syslog.
1193                  */
1194                 static unsigned long    complain;
1195
1196                 if (time_before(complain, jiffies)) {
1197                         dprintk("NFS:       faulty NFS server %s:"
1198                                 " (committed = %d) != (stable = %d)\n",
1199                                 server->nfs_client->cl_hostname,
1200                                 resp->verf->committed, argp->stable);
1201                         complain = jiffies + 300 * HZ;
1202                 }
1203         }
1204 #endif
1205         /* Is this a short write? */
1206         if (task->tk_status >= 0 && resp->count < argp->count) {
1207                 static unsigned long    complain;
1208
1209                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1210
1211                 /* Has the server at least made some progress? */
1212                 if (resp->count != 0) {
1213                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1214                         if (resp->verf->committed != NFS_UNSTABLE) {
1215                                 /* Resend from where the server left off */
1216                                 argp->offset += resp->count;
1217                                 argp->pgbase += resp->count;
1218                                 argp->count -= resp->count;
1219                         } else {
1220                                 /* Resend as a stable write in order to avoid
1221                                  * headaches in the case of a server crash.
1222                                  */
1223                                 argp->stable = NFS_FILE_SYNC;
1224                         }
1225                         nfs_restart_rpc(task, server->nfs_client);
1226                         return -EAGAIN;
1227                 }
1228                 if (time_before(complain, jiffies)) {
1229                         printk(KERN_WARNING
1230                                "NFS: Server wrote zero bytes, expected %u.\n",
1231                                         argp->count);
1232                         complain = jiffies + 300 * HZ;
1233                 }
1234                 /* Can't do anything about it except throw an error. */
1235                 task->tk_status = -EIO;
1236         }
1237         return 0;
1238 }
1239
1240
1241 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1242 static void nfs_commitdata_release(void *data)
1243 {
1244         struct nfs_write_data *wdata = data;
1245
1246         put_nfs_open_context(wdata->args.context);
1247         nfs_commit_free(wdata);
1248 }
1249
1250 /*
1251  * Set up the argument/result storage required for the RPC call.
1252  */
1253 static int nfs_commit_rpcsetup(struct list_head *head,
1254                 struct nfs_write_data *data,
1255                 int how)
1256 {
1257         struct nfs_page *first = nfs_list_entry(head->next);
1258         struct inode *inode = first->wb_context->path.dentry->d_inode;
1259         int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1260         int priority = flush_task_priority(how);
1261         struct rpc_task *task;
1262         struct rpc_message msg = {
1263                 .rpc_argp = &data->args,
1264                 .rpc_resp = &data->res,
1265                 .rpc_cred = first->wb_context->cred,
1266         };
1267         struct rpc_task_setup task_setup_data = {
1268                 .task = &data->task,
1269                 .rpc_client = NFS_CLIENT(inode),
1270                 .rpc_message = &msg,
1271                 .callback_ops = &nfs_commit_ops,
1272                 .callback_data = data,
1273                 .workqueue = nfsiod_workqueue,
1274                 .flags = flags,
1275                 .priority = priority,
1276         };
1277
1278         /* Set up the RPC argument and reply structs
1279          * NB: take care not to mess about with data->commit et al. */
1280
1281         list_splice_init(head, &data->pages);
1282
1283         data->inode       = inode;
1284         data->cred        = msg.rpc_cred;
1285
1286         data->args.fh     = NFS_FH(data->inode);
1287         /* Note: we always request a commit of the entire inode */
1288         data->args.offset = 0;
1289         data->args.count  = 0;
1290         data->args.context = get_nfs_open_context(first->wb_context);
1291         data->res.count   = 0;
1292         data->res.fattr   = &data->fattr;
1293         data->res.verf    = &data->verf;
1294         nfs_fattr_init(&data->fattr);
1295
1296         /* Set up the initial task struct.  */
1297         NFS_PROTO(inode)->commit_setup(data, &msg);
1298
1299         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1300
1301         task = rpc_run_task(&task_setup_data);
1302         if (IS_ERR(task))
1303                 return PTR_ERR(task);
1304         rpc_put_task(task);
1305         return 0;
1306 }
1307
1308 /*
1309  * Commit dirty pages
1310  */
1311 static int
1312 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1313 {
1314         struct nfs_write_data   *data;
1315         struct nfs_page         *req;
1316
1317         data = nfs_commitdata_alloc();
1318
1319         if (!data)
1320                 goto out_bad;
1321
1322         /* Set up the argument struct */
1323         return nfs_commit_rpcsetup(head, data, how);
1324  out_bad:
1325         while (!list_empty(head)) {
1326                 req = nfs_list_entry(head->next);
1327                 nfs_list_remove_request(req);
1328                 nfs_mark_request_commit(req);
1329                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1330                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1331                                 BDI_RECLAIMABLE);
1332                 nfs_clear_page_tag_locked(req);
1333         }
1334         return -ENOMEM;
1335 }
1336
1337 /*
1338  * COMMIT call returned
1339  */
1340 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1341 {
1342         struct nfs_write_data   *data = calldata;
1343
1344         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1345                                 task->tk_pid, task->tk_status);
1346
1347         /* Call the NFS version-specific code */
1348         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1349                 return;
1350 }
1351
1352 static void nfs_commit_release(void *calldata)
1353 {
1354         struct nfs_write_data   *data = calldata;
1355         struct nfs_page         *req;
1356         int status = data->task.tk_status;
1357
1358         while (!list_empty(&data->pages)) {
1359                 req = nfs_list_entry(data->pages.next);
1360                 nfs_list_remove_request(req);
1361                 nfs_clear_request_commit(req);
1362
1363                 dprintk("NFS:       commit (%s/%lld %d@%lld)",
1364                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1365                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1366                         req->wb_bytes,
1367                         (long long)req_offset(req));
1368                 if (status < 0) {
1369                         nfs_context_set_write_error(req->wb_context, status);
1370                         nfs_inode_remove_request(req);
1371                         dprintk(", error = %d\n", status);
1372                         goto next;
1373                 }
1374
1375                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1376                  * returned by the server against all stored verfs. */
1377                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1378                         /* We have a match */
1379                         nfs_inode_remove_request(req);
1380                         dprintk(" OK\n");
1381                         goto next;
1382                 }
1383                 /* We have a mismatch. Write the page again */
1384                 dprintk(" mismatch\n");
1385                 nfs_mark_request_dirty(req);
1386         next:
1387                 nfs_clear_page_tag_locked(req);
1388         }
1389         nfs_commitdata_release(calldata);
1390 }
1391
1392 static const struct rpc_call_ops nfs_commit_ops = {
1393 #if defined(CONFIG_NFS_V4_1)
1394         .rpc_call_prepare = nfs_write_prepare,
1395 #endif /* CONFIG_NFS_V4_1 */
1396         .rpc_call_done = nfs_commit_done,
1397         .rpc_release = nfs_commit_release,
1398 };
1399
1400 static int nfs_commit_inode(struct inode *inode, int how)
1401 {
1402         LIST_HEAD(head);
1403         int res;
1404
1405         spin_lock(&inode->i_lock);
1406         res = nfs_scan_commit(inode, &head, 0, 0);
1407         spin_unlock(&inode->i_lock);
1408         if (res) {
1409                 int error = nfs_commit_list(inode, &head, how);
1410                 if (error < 0)
1411                         return error;
1412         }
1413         return res;
1414 }
1415
1416 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1417 {
1418         int ret;
1419
1420         ret = nfs_commit_inode(inode,
1421                         wbc->sync_mode == WB_SYNC_ALL ? FLUSH_SYNC : 0);
1422         if (ret >= 0)
1423                 return 0;
1424         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1425         return ret;
1426 }
1427 #else
1428 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1429 {
1430         return 0;
1431 }
1432
1433 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1434 {
1435         return 0;
1436 }
1437 #endif
1438
1439 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1440 {
1441         return nfs_commit_unstable_pages(inode, wbc);
1442 }
1443
1444 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1445 {
1446         struct inode *inode = mapping->host;
1447         pgoff_t idx_start, idx_end;
1448         unsigned int npages = 0;
1449         LIST_HEAD(head);
1450         int nocommit = how & FLUSH_NOCOMMIT;
1451         long pages, ret;
1452
1453         /* FIXME */
1454         if (wbc->range_cyclic)
1455                 idx_start = 0;
1456         else {
1457                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1458                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1459                 if (idx_end > idx_start) {
1460                         pgoff_t l_npages = 1 + idx_end - idx_start;
1461                         npages = l_npages;
1462                         if (sizeof(npages) != sizeof(l_npages) &&
1463                                         (pgoff_t)npages != l_npages)
1464                                 npages = 0;
1465                 }
1466         }
1467         how &= ~FLUSH_NOCOMMIT;
1468         spin_lock(&inode->i_lock);
1469         do {
1470                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1471                 if (ret != 0)
1472                         continue;
1473                 if (nocommit)
1474                         break;
1475                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1476                 if (pages == 0)
1477                         break;
1478                 if (how & FLUSH_INVALIDATE) {
1479                         spin_unlock(&inode->i_lock);
1480                         nfs_cancel_commit_list(&head);
1481                         ret = pages;
1482                         spin_lock(&inode->i_lock);
1483                         continue;
1484                 }
1485                 pages += nfs_scan_commit(inode, &head, 0, 0);
1486                 spin_unlock(&inode->i_lock);
1487                 ret = nfs_commit_list(inode, &head, how);
1488                 spin_lock(&inode->i_lock);
1489
1490         } while (ret >= 0);
1491         spin_unlock(&inode->i_lock);
1492         return ret;
1493 }
1494
1495 static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1496 {
1497         int ret;
1498
1499         ret = nfs_writepages(mapping, wbc);
1500         if (ret < 0)
1501                 goto out;
1502         ret = nfs_sync_mapping_wait(mapping, wbc, how);
1503         if (ret < 0)
1504                 goto out;
1505         return 0;
1506 out:
1507         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
1508         return ret;
1509 }
1510
1511 /* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
1512 static int nfs_write_mapping(struct address_space *mapping, int how)
1513 {
1514         struct writeback_control wbc = {
1515                 .bdi = mapping->backing_dev_info,
1516                 .sync_mode = WB_SYNC_ALL,
1517                 .nr_to_write = LONG_MAX,
1518                 .range_start = 0,
1519                 .range_end = LLONG_MAX,
1520         };
1521
1522         return __nfs_write_mapping(mapping, &wbc, how);
1523 }
1524
1525 /*
1526  * flush the inode to disk.
1527  */
1528 int nfs_wb_all(struct inode *inode)
1529 {
1530         return nfs_write_mapping(inode->i_mapping, 0);
1531 }
1532
1533 int nfs_wb_nocommit(struct inode *inode)
1534 {
1535         return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
1536 }
1537
1538 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1539 {
1540         struct nfs_page *req;
1541         loff_t range_start = page_offset(page);
1542         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1543         struct writeback_control wbc = {
1544                 .bdi = page->mapping->backing_dev_info,
1545                 .sync_mode = WB_SYNC_ALL,
1546                 .nr_to_write = LONG_MAX,
1547                 .range_start = range_start,
1548                 .range_end = range_end,
1549         };
1550         int ret = 0;
1551
1552         BUG_ON(!PageLocked(page));
1553         for (;;) {
1554                 req = nfs_page_find_request(page);
1555                 if (req == NULL)
1556                         goto out;
1557                 if (test_bit(PG_CLEAN, &req->wb_flags)) {
1558                         nfs_release_request(req);
1559                         break;
1560                 }
1561                 if (nfs_lock_request_dontget(req)) {
1562                         nfs_inode_remove_request(req);
1563                         /*
1564                          * In case nfs_inode_remove_request has marked the
1565                          * page as being dirty
1566                          */
1567                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1568                         nfs_unlock_request(req);
1569                         break;
1570                 }
1571                 ret = nfs_wait_on_request(req);
1572                 nfs_release_request(req);
1573                 if (ret < 0)
1574                         goto out;
1575         }
1576         if (!PagePrivate(page))
1577                 return 0;
1578         ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);
1579 out:
1580         return ret;
1581 }
1582
1583 static int nfs_wb_page_priority(struct inode *inode, struct page *page,
1584                                 int how)
1585 {
1586         loff_t range_start = page_offset(page);
1587         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1588         struct writeback_control wbc = {
1589                 .bdi = page->mapping->backing_dev_info,
1590                 .sync_mode = WB_SYNC_ALL,
1591                 .nr_to_write = LONG_MAX,
1592                 .range_start = range_start,
1593                 .range_end = range_end,
1594         };
1595         int ret;
1596
1597         do {
1598                 if (clear_page_dirty_for_io(page)) {
1599                         ret = nfs_writepage_locked(page, &wbc);
1600                         if (ret < 0)
1601                                 goto out_error;
1602                 } else if (!PagePrivate(page))
1603                         break;
1604                 ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1605                 if (ret < 0)
1606                         goto out_error;
1607         } while (PagePrivate(page));
1608         return 0;
1609 out_error:
1610         __mark_inode_dirty(inode, I_DIRTY_PAGES);
1611         return ret;
1612 }
1613
1614 /*
1615  * Write back all requests on one page - we do this before reading it.
1616  */
1617 int nfs_wb_page(struct inode *inode, struct page* page)
1618 {
1619         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1620 }
1621
1622 #ifdef CONFIG_MIGRATION
1623 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
1624                 struct page *page)
1625 {
1626         struct nfs_page *req;
1627         int ret;
1628
1629         nfs_fscache_release_page(page, GFP_KERNEL);
1630
1631         req = nfs_find_and_lock_request(page);
1632         ret = PTR_ERR(req);
1633         if (IS_ERR(req))
1634                 goto out;
1635
1636         ret = migrate_page(mapping, newpage, page);
1637         if (!req)
1638                 goto out;
1639         if (ret)
1640                 goto out_unlock;
1641         page_cache_get(newpage);
1642         spin_lock(&mapping->host->i_lock);
1643         req->wb_page = newpage;
1644         SetPagePrivate(newpage);
1645         set_page_private(newpage, (unsigned long)req);
1646         ClearPagePrivate(page);
1647         set_page_private(page, 0);
1648         spin_unlock(&mapping->host->i_lock);
1649         page_cache_release(page);
1650 out_unlock:
1651         nfs_clear_page_tag_locked(req);
1652 out:
1653         return ret;
1654 }
1655 #endif
1656
1657 int __init nfs_init_writepagecache(void)
1658 {
1659         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1660                                              sizeof(struct nfs_write_data),
1661                                              0, SLAB_HWCACHE_ALIGN,
1662                                              NULL);
1663         if (nfs_wdata_cachep == NULL)
1664                 return -ENOMEM;
1665
1666         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1667                                                      nfs_wdata_cachep);
1668         if (nfs_wdata_mempool == NULL)
1669                 return -ENOMEM;
1670
1671         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1672                                                       nfs_wdata_cachep);
1673         if (nfs_commit_mempool == NULL)
1674                 return -ENOMEM;
1675
1676         /*
1677          * NFS congestion size, scale with available memory.
1678          *
1679          *  64MB:    8192k
1680          * 128MB:   11585k
1681          * 256MB:   16384k
1682          * 512MB:   23170k
1683          *   1GB:   32768k
1684          *   2GB:   46340k
1685          *   4GB:   65536k
1686          *   8GB:   92681k
1687          *  16GB:  131072k
1688          *
1689          * This allows larger machines to have larger/more transfers.
1690          * Limit the default to 256M
1691          */
1692         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1693         if (nfs_congestion_kb > 256*1024)
1694                 nfs_congestion_kb = 256*1024;
1695
1696         return 0;
1697 }
1698
1699 void nfs_destroy_writepagecache(void)
1700 {
1701         mempool_destroy(nfs_commit_mempool);
1702         mempool_destroy(nfs_wdata_mempool);
1703         kmem_cache_destroy(nfs_wdata_cachep);
1704 }
1705