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                 page_cache_get(page);
 205                 if (atomic_long_inc_return(&nfss->writeback) >
 206                                 NFS_CONGESTION_ON_THRESH) {
 207                         set_bdi_congested(&nfss->backing_dev_info,
 208                                                 BLK_RW_ASYNC);
 209                 }
 210         }
 211         return ret;
 212 }
 213
 214 static void nfs_end_page_writeback(struct page *page)
 215 {
 216         struct inode *inode = page->mapping->host;
 217         struct nfs_server *nfss = NFS_SERVER(inode);
 218
 219         end_page_writeback(page);
 220         page_cache_release(page);
 221         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 222                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
 223 }
 224
 225 static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
 226 {
 227         struct inode *inode = page->mapping->host;
 228         struct nfs_page *req;
 229         int ret;
 230
 231         spin_lock(&inode->i_lock);
 232         for (;;) {
 233                 req = nfs_page_find_request_locked(page);
 234                 if (req == NULL)
 235                         break;
 236                 if (nfs_set_page_tag_locked(req))
 237                         break;
 238                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 239                  *       then the call to nfs_set_page_tag_locked() will always
 240                  *       succeed provided that someone hasn't already marked the
 241                  *       request as dirty (in which case we don't care).
 242                  */
 243                 spin_unlock(&inode->i_lock);
 244                 if (!nonblock)
 245                         ret = nfs_wait_on_request(req);
 246                 else
 247                         ret = -EAGAIN;
 248                 nfs_release_request(req);
 249                 if (ret != 0)
 250                         return ERR_PTR(ret);
 251                 spin_lock(&inode->i_lock);
 252         }
 253         spin_unlock(&inode->i_lock);
 254         return req;
 255 }
 256
 257 /*
 258  * Find an associated nfs write request, and prepare to flush it out
 259  * May return an error if the user signalled nfs_wait_on_request().
 260  */
 261 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 262                                 struct page *page, bool nonblock)
 263 {
 264         struct nfs_page *req;
 265         int ret = 0;
 266
 267         req = nfs_find_and_lock_request(page, nonblock);
 268         if (!req)
 269                 goto out;
 270         ret = PTR_ERR(req);
 271         if (IS_ERR(req))
 272                 goto out;
 273
 274         ret = nfs_set_page_writeback(page);
 275         BUG_ON(ret != 0);
 276         BUG_ON(test_bit(PG_CLEAN, &req->wb_flags));
 277
 278         if (!nfs_pageio_add_request(pgio, req)) {
 279                 nfs_redirty_request(req);
 280                 ret = pgio->pg_error;
 281         }
 282 out:
 283         return ret;
 284 }
 285
 286 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 287 {
 288         struct inode *inode = page->mapping->host;
 289         int ret;
 290
 291         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 292         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 293
 294         nfs_pageio_cond_complete(pgio, page->index);
 295         ret = nfs_page_async_flush(pgio, page,
 296                         wbc->sync_mode == WB_SYNC_NONE ||
 297                         wbc->nonblocking != 0);
 298         if (ret == -EAGAIN) {
 299                 redirty_page_for_writepage(wbc, page);
 300                 ret = 0;
 301         }
 302         return ret;
 303 }
 304
 305 /*
 306  * Write an mmapped page to the server.
 307  */
 308 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 309 {
 310         struct nfs_pageio_descriptor pgio;
 311         int err;
 312
 313         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
 314         err = nfs_do_writepage(page, wbc, &pgio);
 315         nfs_pageio_complete(&pgio);
 316         if (err < 0)
 317                 return err;
 318         if (pgio.pg_error < 0)
 319                 return pgio.pg_error;
 320         return 0;
 321 }
 322
 323 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 324 {
 325         int ret;
 326
 327         ret = nfs_writepage_locked(page, wbc);
 328         unlock_page(page);
 329         return ret;
 330 }
 331
 332 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 333 {
 334         int ret;
 335
 336         ret = nfs_do_writepage(page, wbc, data);
 337         unlock_page(page);
 338         return ret;
 339 }
 340
 341 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 342 {
 343         struct inode *inode = mapping->host;
 344         unsigned long *bitlock = &NFS_I(inode)->flags;
 345         struct nfs_pageio_descriptor pgio;
 346         int err;
 347
 348         /* Stop dirtying of new pages while we sync */
 349         err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
 350                         nfs_wait_bit_killable, TASK_KILLABLE);
 351         if (err)
 352                 goto out_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
 360         clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
 361         smp_mb__after_clear_bit();
 362         wake_up_bit(bitlock, NFS_INO_FLUSHING);
 363
 364         if (err < 0)
 365                 goto out_err;
 366         err = pgio.pg_error;
 367         if (err < 0)
 368                 goto out_err;
 369         return 0;
 370 out_err:
 371         return err;
 372 }
 373
 374 /*
 375  * Insert a write request into an inode
 376  */
 377 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 378 {
 379         struct nfs_inode *nfsi = NFS_I(inode);
 380         int error;
 381
 382         error = radix_tree_preload(GFP_NOFS);
 383         if (error != 0)
 384                 goto out;
 385
 386         /* Lock the request! */
 387         nfs_lock_request_dontget(req);
 388
 389         spin_lock(&inode->i_lock);
 390         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 391         BUG_ON(error);
 392         if (!nfsi->npages) {
 393                 igrab(inode);
 394                 if (nfs_have_delegation(inode, FMODE_WRITE))
 395                         nfsi->change_attr++;
 396         }
 397         SetPagePrivate(req->wb_page);
 398         set_page_private(req->wb_page, (unsigned long)req);
 399         nfsi->npages++;
 400         kref_get(&req->wb_kref);
 401         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
 402                                 NFS_PAGE_TAG_LOCKED);
 403         spin_unlock(&inode->i_lock);
 404         radix_tree_preload_end();
 405 out:
 406         return error;
 407 }
 408
 409 /*
 410  * Remove a write request from an inode
 411  */
 412 static void nfs_inode_remove_request(struct nfs_page *req)
 413 {
 414         struct inode *inode = req->wb_context->path.dentry->d_inode;
 415         struct nfs_inode *nfsi = NFS_I(inode);
 416
 417         BUG_ON (!NFS_WBACK_BUSY(req));
 418
 419         spin_lock(&inode->i_lock);
 420         set_page_private(req->wb_page, 0);
 421         ClearPagePrivate(req->wb_page);
 422         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 423         nfsi->npages--;
 424         if (!nfsi->npages) {
 425                 spin_unlock(&inode->i_lock);
 426                 iput(inode);
 427         } else
 428                 spin_unlock(&inode->i_lock);
 429         nfs_clear_request(req);
 430         nfs_release_request(req);
 431 }
 432
 433 static void
 434 nfs_mark_request_dirty(struct nfs_page *req)
 435 {
 436         __set_page_dirty_nobuffers(req->wb_page);
 437         __mark_inode_dirty(req->wb_page->mapping->host, I_DIRTY_DATASYNC);
 438 }
 439
 440 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 441 /*
 442  * Add a request to the inode's commit list.
 443  */
 444 static void
 445 nfs_mark_request_commit(struct nfs_page *req)
 446 {
 447         struct inode *inode = req->wb_context->path.dentry->d_inode;
 448         struct nfs_inode *nfsi = NFS_I(inode);
 449
 450         spin_lock(&inode->i_lock);
 451         set_bit(PG_CLEAN, &(req)->wb_flags);
 452         radix_tree_tag_set(&nfsi->nfs_page_tree,
 453                         req->wb_index,
 454                         NFS_PAGE_TAG_COMMIT);
 455         nfsi->ncommit++;
 456         spin_unlock(&inode->i_lock);
 457         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 458         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 459         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 460 }
 461
 462 static int
 463 nfs_clear_request_commit(struct nfs_page *req)
 464 {
 465         struct page *page = req->wb_page;
 466
 467         if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
 468                 dec_zone_page_state(page, NR_UNSTABLE_NFS);
 469                 dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 470                 return 1;
 471         }
 472         return 0;
 473 }
 474
 475 static inline
 476 int nfs_write_need_commit(struct nfs_write_data *data)
 477 {
 478         return data->verf.committed != NFS_FILE_SYNC;
 479 }
 480
 481 static inline
 482 int nfs_reschedule_unstable_write(struct nfs_page *req)
 483 {
 484         if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 485                 nfs_mark_request_commit(req);
 486                 return 1;
 487         }
 488         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 489                 nfs_mark_request_dirty(req);
 490                 return 1;
 491         }
 492         return 0;
 493 }
 494 #else
 495 static inline void
 496 nfs_mark_request_commit(struct nfs_page *req)
 497 {
 498 }
 499
 500 static inline int
 501 nfs_clear_request_commit(struct nfs_page *req)
 502 {
 503         return 0;
 504 }
 505
 506 static inline
 507 int nfs_write_need_commit(struct nfs_write_data *data)
 508 {
 509         return 0;
 510 }
 511
 512 static inline
 513 int nfs_reschedule_unstable_write(struct nfs_page *req)
 514 {
 515         return 0;
 516 }
 517 #endif
 518
 519 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 520 static int
 521 nfs_need_commit(struct nfs_inode *nfsi)
 522 {
 523         return radix_tree_tagged(&nfsi->nfs_page_tree, NFS_PAGE_TAG_COMMIT);
 524 }
 525
 526 /*
 527  * nfs_scan_commit - Scan an inode for commit requests
 528  * @inode: NFS inode to scan
 529  * @dst: destination list
 530  * @idx_start: lower bound of page->index to scan.
 531  * @npages: idx_start + npages sets the upper bound to scan.
 532  *
 533  * Moves requests from the inode's 'commit' request list.
 534  * The requests are *not* checked to ensure that they form a contiguous set.
 535  */
 536 static int
 537 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 538 {
 539         struct nfs_inode *nfsi = NFS_I(inode);
 540         int ret;
 541
 542         if (!nfs_need_commit(nfsi))
 543                 return 0;
 544
 545         ret = nfs_scan_list(nfsi, dst, idx_start, npages, NFS_PAGE_TAG_COMMIT);
 546         if (ret > 0)
 547                 nfsi->ncommit -= ret;
 548         if (nfs_need_commit(NFS_I(inode)))
 549                 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 550         return ret;
 551 }
 552 #else
 553 static inline int nfs_need_commit(struct nfs_inode *nfsi)
 554 {
 555         return 0;
 556 }
 557
 558 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 559 {
 560         return 0;
 561 }
 562 #endif
 563
 564 /*
 565  * Search for an existing write request, and attempt to update
 566  * it to reflect a new dirty region on a given page.
 567  *
 568  * If the attempt fails, then the existing request is flushed out
 569  * to disk.
 570  */
 571 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
 572                 struct page *page,
 573                 unsigned int offset,
 574                 unsigned int bytes)
 575 {
 576         struct nfs_page *req;
 577         unsigned int rqend;
 578         unsigned int end;
 579         int error;
 580
 581         if (!PagePrivate(page))
 582                 return NULL;
 583
 584         end = offset + bytes;
 585         spin_lock(&inode->i_lock);
 586
 587         for (;;) {
 588                 req = nfs_page_find_request_locked(page);
 589                 if (req == NULL)
 590                         goto out_unlock;
 591
 592                 rqend = req->wb_offset + req->wb_bytes;
 593                 /*
 594                  * Tell the caller to flush out the request if
 595                  * the offsets are non-contiguous.
 596                  * Note: nfs_flush_incompatible() will already
 597                  * have flushed out requests having wrong owners.
 598                  */
 599                 if (offset > rqend
 600                     || end < req->wb_offset)
 601                         goto out_flushme;
 602
 603                 if (nfs_set_page_tag_locked(req))
 604                         break;
 605
 606                 /* The request is locked, so wait and then retry */
 607                 spin_unlock(&inode->i_lock);
 608                 error = nfs_wait_on_request(req);
 609                 nfs_release_request(req);
 610                 if (error != 0)
 611                         goto out_err;
 612                 spin_lock(&inode->i_lock);
 613         }
 614
 615         if (nfs_clear_request_commit(req) &&
 616                         radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
 617                                 req->wb_index, NFS_PAGE_TAG_COMMIT) != NULL)
 618                 NFS_I(inode)->ncommit--;
 619
 620         /* Okay, the request matches. Update the region */
 621         if (offset < req->wb_offset) {
 622                 req->wb_offset = offset;
 623                 req->wb_pgbase = offset;
 624         }
 625         if (end > rqend)
 626                 req->wb_bytes = end - req->wb_offset;
 627         else
 628                 req->wb_bytes = rqend - req->wb_offset;
 629 out_unlock:
 630         spin_unlock(&inode->i_lock);
 631         return req;
 632 out_flushme:
 633         spin_unlock(&inode->i_lock);
 634         nfs_release_request(req);
 635         error = nfs_wb_page(inode, page);
 636 out_err:
 637         return ERR_PTR(error);
 638 }
 639
 640 /*
 641  * Try to update an existing write request, or create one if there is none.
 642  *
 643  * Note: Should always be called with the Page Lock held to prevent races
 644  * if we have to add a new request. Also assumes that the caller has
 645  * already called nfs_flush_incompatible() if necessary.
 646  */
 647 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
 648                 struct page *page, unsigned int offset, unsigned int bytes)
 649 {
 650         struct inode *inode = page->mapping->host;
 651         struct nfs_page *req;
 652         int error;
 653
 654         req = nfs_try_to_update_request(inode, page, offset, bytes);
 655         if (req != NULL)
 656                 goto out;
 657         req = nfs_create_request(ctx, inode, page, offset, bytes);
 658         if (IS_ERR(req))
 659                 goto out;
 660         error = nfs_inode_add_request(inode, req);
 661         if (error != 0) {
 662                 nfs_release_request(req);
 663                 req = ERR_PTR(error);
 664         }
 665 out:
 666         return req;
 667 }
 668
 669 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 670                 unsigned int offset, unsigned int count)
 671 {
 672         struct nfs_page *req;
 673
 674         req = nfs_setup_write_request(ctx, page, offset, count);
 675         if (IS_ERR(req))
 676                 return PTR_ERR(req);
 677         nfs_mark_request_dirty(req);
 678         /* Update file length */
 679         nfs_grow_file(page, offset, count);
 680         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
 681         nfs_mark_request_dirty(req);
 682         nfs_clear_page_tag_locked(req);
 683         return 0;
 684 }
 685
 686 int nfs_flush_incompatible(struct file *file, struct page *page)
 687 {
 688         struct nfs_open_context *ctx = nfs_file_open_context(file);
 689         struct nfs_page *req;
 690         int do_flush, status;
 691         /*
 692          * Look for a request corresponding to this page. If there
 693          * is one, and it belongs to another file, we flush it out
 694          * before we try to copy anything into the page. Do this
 695          * due to the lack of an ACCESS-type call in NFSv2.
 696          * Also do the same if we find a request from an existing
 697          * dropped page.
 698          */
 699         do {
 700                 req = nfs_page_find_request(page);
 701                 if (req == NULL)
 702                         return 0;
 703                 do_flush = req->wb_page != page || req->wb_context != ctx ||
 704                         req->wb_lock_context->lockowner != current->files ||
 705                         req->wb_lock_context->pid != current->tgid;
 706                 nfs_release_request(req);
 707                 if (!do_flush)
 708                         return 0;
 709                 status = nfs_wb_page(page->mapping->host, page);
 710         } while (status == 0);
 711         return status;
 712 }
 713
 714 /*
 715  * If the page cache is marked as unsafe or invalid, then we can't rely on
 716  * the PageUptodate() flag. In this case, we will need to turn off
 717  * write optimisations that depend on the page contents being correct.
 718  */
 719 static int nfs_write_pageuptodate(struct page *page, struct inode *inode)
 720 {
 721         return PageUptodate(page) &&
 722                 !(NFS_I(inode)->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA));
 723 }
 724
 725 /*
 726  * Update and possibly write a cached page of an NFS file.
 727  *
 728  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 729  * things with a page scheduled for an RPC call (e.g. invalidate it).
 730  */
 731 int nfs_updatepage(struct file *file, struct page *page,
 732                 unsigned int offset, unsigned int count)
 733 {
 734         struct nfs_open_context *ctx = nfs_file_open_context(file);
 735         struct inode    *inode = page->mapping->host;
 736         int             status = 0;
 737
 738         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 739
 740         dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
 741                 file->f_path.dentry->d_parent->d_name.name,
 742                 file->f_path.dentry->d_name.name, count,
 743                 (long long)(page_offset(page) + offset));
 744
 745         /* If we're not using byte range locks, and we know the page
 746          * is up to date, it may be more efficient to extend the write
 747          * to cover the entire page in order to avoid fragmentation
 748          * inefficiencies.
 749          */
 750         if (nfs_write_pageuptodate(page, inode) &&
 751                         inode->i_flock == NULL &&
 752                         !(file->f_flags & O_DSYNC)) {
 753                 count = max(count + offset, nfs_page_length(page));
 754                 offset = 0;
 755         }
 756
 757         status = nfs_writepage_setup(ctx, page, offset, count);
 758         if (status < 0)
 759                 nfs_set_pageerror(page);
 760
 761         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 762                         status, (long long)i_size_read(inode));
 763         return status;
 764 }
 765
 766 static void nfs_writepage_release(struct nfs_page *req)
 767 {
 768         struct page *page = req->wb_page;
 769
 770         if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req))
 771                 nfs_inode_remove_request(req);
 772         nfs_clear_page_tag_locked(req);
 773         nfs_end_page_writeback(page);
 774 }
 775
 776 static int flush_task_priority(int how)
 777 {
 778         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 779                 case FLUSH_HIGHPRI:
 780                         return RPC_PRIORITY_HIGH;
 781                 case FLUSH_LOWPRI:
 782                         return RPC_PRIORITY_LOW;
 783         }
 784         return RPC_PRIORITY_NORMAL;
 785 }
 786
 787 /*
 788  * Set up the argument/result storage required for the RPC call.
 789  */
 790 static int nfs_write_rpcsetup(struct nfs_page *req,
 791                 struct nfs_write_data *data,
 792                 const struct rpc_call_ops *call_ops,
 793                 unsigned int count, unsigned int offset,
 794                 int how)
 795 {
 796         struct inode *inode = req->wb_context->path.dentry->d_inode;
 797         int priority = flush_task_priority(how);
 798         struct rpc_task *task;
 799         struct rpc_message msg = {
 800                 .rpc_argp = &data->args,
 801                 .rpc_resp = &data->res,
 802                 .rpc_cred = req->wb_context->cred,
 803         };
 804         struct rpc_task_setup task_setup_data = {
 805                 .rpc_client = NFS_CLIENT(inode),
 806                 .task = &data->task,
 807                 .rpc_message = &msg,
 808                 .callback_ops = call_ops,
 809                 .callback_data = data,
 810                 .workqueue = nfsiod_workqueue,
 811                 .flags = RPC_TASK_ASYNC,
 812                 .priority = priority,
 813         };
 814         int ret = 0;
 815
 816         /* Set up the RPC argument and reply structs
 817          * NB: take care not to mess about with data->commit et al. */
 818
 819         data->req = req;
 820         data->inode = inode = req->wb_context->path.dentry->d_inode;
 821         data->cred = msg.rpc_cred;
 822
 823         data->args.fh     = NFS_FH(inode);
 824         data->args.offset = req_offset(req) + offset;
 825         data->args.pgbase = req->wb_pgbase + offset;
 826         data->args.pages  = data->pagevec;
 827         data->args.count  = count;
 828         data->args.context = get_nfs_open_context(req->wb_context);
 829         data->args.lock_context = req->wb_lock_context;
 830         data->args.stable  = NFS_UNSTABLE;
 831         if (how & FLUSH_STABLE) {
 832                 data->args.stable = NFS_DATA_SYNC;
 833                 if (!nfs_need_commit(NFS_I(inode)))
 834                         data->args.stable = NFS_FILE_SYNC;
 835         }
 836
 837         data->res.fattr   = &data->fattr;
 838         data->res.count   = count;
 839         data->res.verf    = &data->verf;
 840         nfs_fattr_init(&data->fattr);
 841
 842         /* Set up the initial task struct.  */
 843         NFS_PROTO(inode)->write_setup(data, &msg);
 844
 845         dprintk("NFS: %5u initiated write call "
 846                 "(req %s/%lld, %u bytes @ offset %llu)\n",
 847                 data->task.tk_pid,
 848                 inode->i_sb->s_id,
 849                 (long long)NFS_FILEID(inode),
 850                 count,
 851                 (unsigned long long)data->args.offset);
 852
 853         task = rpc_run_task(&task_setup_data);
 854         if (IS_ERR(task)) {
 855                 ret = PTR_ERR(task);
 856                 goto out;
 857         }
 858         if (how & FLUSH_SYNC) {
 859                 ret = rpc_wait_for_completion_task(task);
 860                 if (ret == 0)
 861                         ret = task->tk_status;
 862         }
 863         rpc_put_task(task);
 864 out:
 865         return ret;
 866 }
 867
 868 /* If a nfs_flush_* function fails, it should remove reqs from @head and
 869  * call this on each, which will prepare them to be retried on next
 870  * writeback using standard nfs.
 871  */
 872 static void nfs_redirty_request(struct nfs_page *req)
 873 {
 874         struct page *page = req->wb_page;
 875
 876         nfs_mark_request_dirty(req);
 877         nfs_clear_page_tag_locked(req);
 878         nfs_end_page_writeback(page);
 879 }
 880
 881 /*
 882  * Generate multiple small requests to write out a single
 883  * contiguous dirty area on one page.
 884  */
 885 static int nfs_flush_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 886 {
 887         struct nfs_page *req = nfs_list_entry(head->next);
 888         struct page *page = req->wb_page;
 889         struct nfs_write_data *data;
 890         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 891         unsigned int offset;
 892         int requests = 0;
 893         int ret = 0;
 894         LIST_HEAD(list);
 895
 896         nfs_list_remove_request(req);
 897
 898         nbytes = count;
 899         do {
 900                 size_t len = min(nbytes, wsize);
 901
 902                 data = nfs_writedata_alloc(1);
 903                 if (!data)
 904                         goto out_bad;
 905                 list_add(&data->pages, &list);
 906                 requests++;
 907                 nbytes -= len;
 908         } while (nbytes != 0);
 909         atomic_set(&req->wb_complete, requests);
 910
 911         ClearPageError(page);
 912         offset = 0;
 913         nbytes = count;
 914         do {
 915                 int ret2;
 916
 917                 data = list_entry(list.next, struct nfs_write_data, pages);
 918                 list_del_init(&data->pages);
 919
 920                 data->pagevec[0] = page;
 921
 922                 if (nbytes < wsize)
 923                         wsize = nbytes;
 924                 ret2 = nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 925                                    wsize, offset, how);
 926                 if (ret == 0)
 927                         ret = ret2;
 928                 offset += wsize;
 929                 nbytes -= wsize;
 930         } while (nbytes != 0);
 931
 932         return ret;
 933
 934 out_bad:
 935         while (!list_empty(&list)) {
 936                 data = list_entry(list.next, struct nfs_write_data, pages);
 937                 list_del(&data->pages);
 938                 nfs_writedata_release(data);
 939         }
 940         nfs_redirty_request(req);
 941         return -ENOMEM;
 942 }
 943
 944 /*
 945  * Create an RPC task for the given write request and kick it.
 946  * The page must have been locked by the caller.
 947  *
 948  * It may happen that the page we're passed is not marked dirty.
 949  * This is the case if nfs_updatepage detects a conflicting request
 950  * that has been written but not committed.
 951  */
 952 static int nfs_flush_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int how)
 953 {
 954         struct nfs_page         *req;
 955         struct page             **pages;
 956         struct nfs_write_data   *data;
 957
 958         data = nfs_writedata_alloc(npages);
 959         if (!data)
 960                 goto out_bad;
 961
 962         pages = data->pagevec;
 963         while (!list_empty(head)) {
 964                 req = nfs_list_entry(head->next);
 965                 nfs_list_remove_request(req);
 966                 nfs_list_add_request(req, &data->pages);
 967                 ClearPageError(req->wb_page);
 968                 *pages++ = req->wb_page;
 969         }
 970         req = nfs_list_entry(data->pages.next);
 971
 972         /* Set up the argument struct */
 973         return nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 974  out_bad:
 975         while (!list_empty(head)) {
 976                 req = nfs_list_entry(head->next);
 977                 nfs_list_remove_request(req);
 978                 nfs_redirty_request(req);
 979         }
 980         return -ENOMEM;
 981 }
 982
 983 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
 984                                   struct inode *inode, int ioflags)
 985 {
 986         size_t wsize = NFS_SERVER(inode)->wsize;
 987
 988         if (wsize < PAGE_CACHE_SIZE)
 989                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
 990         else
 991                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
 992 }
 993
 994 /*
 995  * Handle a write reply that flushed part of a page.
 996  */
 997 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
 998 {
 999         struct nfs_write_data   *data = calldata;
1000
1001         dprintk("NFS: %5u write(%s/%lld %d@%lld)",
1002                 task->tk_pid,
1003                 data->req->wb_context->path.dentry->d_inode->i_sb->s_id,
1004                 (long long)
1005                   NFS_FILEID(data->req->wb_context->path.dentry->d_inode),
1006                 data->req->wb_bytes, (long long)req_offset(data->req));
1007
1008         nfs_writeback_done(task, data);
1009 }
1010
1011 static void nfs_writeback_release_partial(void *calldata)
1012 {
1013         struct nfs_write_data   *data = calldata;
1014         struct nfs_page         *req = data->req;
1015         struct page             *page = req->wb_page;
1016         int status = data->task.tk_status;
1017
1018         if (status < 0) {
1019                 nfs_set_pageerror(page);
1020                 nfs_context_set_write_error(req->wb_context, status);
1021                 dprintk(", error = %d\n", status);
1022                 goto out;
1023         }
1024
1025         if (nfs_write_need_commit(data)) {
1026                 struct inode *inode = page->mapping->host;
1027
1028                 spin_lock(&inode->i_lock);
1029                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
1030                         /* Do nothing we need to resend the writes */
1031                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1032                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1033                         dprintk(" defer commit\n");
1034                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1035                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
1036                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
1037                         dprintk(" server reboot detected\n");
1038                 }
1039                 spin_unlock(&inode->i_lock);
1040         } else
1041                 dprintk(" OK\n");
1042
1043 out:
1044         if (atomic_dec_and_test(&req->wb_complete))
1045                 nfs_writepage_release(req);
1046         nfs_writedata_release(calldata);
1047 }
1048
1049 #if defined(CONFIG_NFS_V4_1)
1050 void nfs_write_prepare(struct rpc_task *task, void *calldata)
1051 {
1052         struct nfs_write_data *data = calldata;
1053
1054         if (nfs4_setup_sequence(NFS_SERVER(data->inode),
1055                                 &data->args.seq_args,
1056                                 &data->res.seq_res, 1, task))
1057                 return;
1058         rpc_call_start(task);
1059 }
1060 #endif /* CONFIG_NFS_V4_1 */
1061
1062 static const struct rpc_call_ops nfs_write_partial_ops = {
1063 #if defined(CONFIG_NFS_V4_1)
1064         .rpc_call_prepare = nfs_write_prepare,
1065 #endif /* CONFIG_NFS_V4_1 */
1066         .rpc_call_done = nfs_writeback_done_partial,
1067         .rpc_release = nfs_writeback_release_partial,
1068 };
1069
1070 /*
1071  * Handle a write reply that flushes a whole page.
1072  *
1073  * FIXME: There is an inherent race with invalidate_inode_pages and
1074  *        writebacks since the page->count is kept > 1 for as long
1075  *        as the page has a write request pending.
1076  */
1077 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1078 {
1079         struct nfs_write_data   *data = calldata;
1080
1081         nfs_writeback_done(task, data);
1082 }
1083
1084 static void nfs_writeback_release_full(void *calldata)
1085 {
1086         struct nfs_write_data   *data = calldata;
1087         int status = data->task.tk_status;
1088
1089         /* Update attributes as result of writeback. */
1090         while (!list_empty(&data->pages)) {
1091                 struct nfs_page *req = nfs_list_entry(data->pages.next);
1092                 struct page *page = req->wb_page;
1093
1094                 nfs_list_remove_request(req);
1095
1096                 dprintk("NFS: %5u write (%s/%lld %d@%lld)",
1097                         data->task.tk_pid,
1098                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1099                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1100                         req->wb_bytes,
1101                         (long long)req_offset(req));
1102
1103                 if (status < 0) {
1104                         nfs_set_pageerror(page);
1105                         nfs_context_set_write_error(req->wb_context, status);
1106                         dprintk(", error = %d\n", status);
1107                         goto remove_request;
1108                 }
1109
1110                 if (nfs_write_need_commit(data)) {
1111                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1112                         nfs_mark_request_commit(req);
1113                         dprintk(" marked for commit\n");
1114                         goto next;
1115                 }
1116                 dprintk(" OK\n");
1117 remove_request:
1118                 nfs_inode_remove_request(req);
1119         next:
1120                 nfs_clear_page_tag_locked(req);
1121                 nfs_end_page_writeback(page);
1122         }
1123         nfs_writedata_release(calldata);
1124 }
1125
1126 static const struct rpc_call_ops nfs_write_full_ops = {
1127 #if defined(CONFIG_NFS_V4_1)
1128         .rpc_call_prepare = nfs_write_prepare,
1129 #endif /* CONFIG_NFS_V4_1 */
1130         .rpc_call_done = nfs_writeback_done_full,
1131         .rpc_release = nfs_writeback_release_full,
1132 };
1133
1134
1135 /*
1136  * This function is called when the WRITE call is complete.
1137  */
1138 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1139 {
1140         struct nfs_writeargs    *argp = &data->args;
1141         struct nfs_writeres     *resp = &data->res;
1142         struct nfs_server       *server = NFS_SERVER(data->inode);
1143         int status;
1144
1145         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1146                 task->tk_pid, task->tk_status);
1147
1148         /*
1149          * ->write_done will attempt to use post-op attributes to detect
1150          * conflicting writes by other clients.  A strict interpretation
1151          * of close-to-open would allow us to continue caching even if
1152          * another writer had changed the file, but some applications
1153          * depend on tighter cache coherency when writing.
1154          */
1155         status = NFS_PROTO(data->inode)->write_done(task, data);
1156         if (status != 0)
1157                 return status;
1158         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1159
1160 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1161         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1162                 /* We tried a write call, but the server did not
1163                  * commit data to stable storage even though we
1164                  * requested it.
1165                  * Note: There is a known bug in Tru64 < 5.0 in which
1166                  *       the server reports NFS_DATA_SYNC, but performs
1167                  *       NFS_FILE_SYNC. We therefore implement this checking
1168                  *       as a dprintk() in order to avoid filling syslog.
1169                  */
1170                 static unsigned long    complain;
1171
1172                 if (time_before(complain, jiffies)) {
1173                         dprintk("NFS:       faulty NFS server %s:"
1174                                 " (committed = %d) != (stable = %d)\n",
1175                                 server->nfs_client->cl_hostname,
1176                                 resp->verf->committed, argp->stable);
1177                         complain = jiffies + 300 * HZ;
1178                 }
1179         }
1180 #endif
1181         /* Is this a short write? */
1182         if (task->tk_status >= 0 && resp->count < argp->count) {
1183                 static unsigned long    complain;
1184
1185                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1186
1187                 /* Has the server at least made some progress? */
1188                 if (resp->count != 0) {
1189                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1190                         if (resp->verf->committed != NFS_UNSTABLE) {
1191                                 /* Resend from where the server left off */
1192                                 argp->offset += resp->count;
1193                                 argp->pgbase += resp->count;
1194                                 argp->count -= resp->count;
1195                         } else {
1196                                 /* Resend as a stable write in order to avoid
1197                                  * headaches in the case of a server crash.
1198                                  */
1199                                 argp->stable = NFS_FILE_SYNC;
1200                         }
1201                         nfs_restart_rpc(task, server->nfs_client);
1202                         return -EAGAIN;
1203                 }
1204                 if (time_before(complain, jiffies)) {
1205                         printk(KERN_WARNING
1206                                "NFS: Server wrote zero bytes, expected %u.\n",
1207                                         argp->count);
1208                         complain = jiffies + 300 * HZ;
1209                 }
1210                 /* Can't do anything about it except throw an error. */
1211                 task->tk_status = -EIO;
1212         }
1213         return 0;
1214 }
1215
1216
1217 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1218 static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
1219 {
1220         if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
1221                 return 1;
1222         if (may_wait && !out_of_line_wait_on_bit_lock(&nfsi->flags,
1223                                 NFS_INO_COMMIT, nfs_wait_bit_killable,
1224                                 TASK_KILLABLE))
1225                 return 1;
1226         return 0;
1227 }
1228
1229 static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
1230 {
1231         clear_bit(NFS_INO_COMMIT, &nfsi->flags);
1232         smp_mb__after_clear_bit();
1233         wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
1234 }
1235
1236
1237 static void nfs_commitdata_release(void *data)
1238 {
1239         struct nfs_write_data *wdata = data;
1240
1241         put_nfs_open_context(wdata->args.context);
1242         nfs_commit_free(wdata);
1243 }
1244
1245 /*
1246  * Set up the argument/result storage required for the RPC call.
1247  */
1248 static int nfs_commit_rpcsetup(struct list_head *head,
1249                 struct nfs_write_data *data,
1250                 int how)
1251 {
1252         struct nfs_page *first = nfs_list_entry(head->next);
1253         struct inode *inode = first->wb_context->path.dentry->d_inode;
1254         int priority = flush_task_priority(how);
1255         struct rpc_task *task;
1256         struct rpc_message msg = {
1257                 .rpc_argp = &data->args,
1258                 .rpc_resp = &data->res,
1259                 .rpc_cred = first->wb_context->cred,
1260         };
1261         struct rpc_task_setup task_setup_data = {
1262                 .task = &data->task,
1263                 .rpc_client = NFS_CLIENT(inode),
1264                 .rpc_message = &msg,
1265                 .callback_ops = &nfs_commit_ops,
1266                 .callback_data = data,
1267                 .workqueue = nfsiod_workqueue,
1268                 .flags = RPC_TASK_ASYNC,
1269                 .priority = priority,
1270         };
1271
1272         /* Set up the RPC argument and reply structs
1273          * NB: take care not to mess about with data->commit et al. */
1274
1275         list_splice_init(head, &data->pages);
1276
1277         data->inode       = inode;
1278         data->cred        = msg.rpc_cred;
1279
1280         data->args.fh     = NFS_FH(data->inode);
1281         /* Note: we always request a commit of the entire inode */
1282         data->args.offset = 0;
1283         data->args.count  = 0;
1284         data->args.context = get_nfs_open_context(first->wb_context);
1285         data->res.count   = 0;
1286         data->res.fattr   = &data->fattr;
1287         data->res.verf    = &data->verf;
1288         nfs_fattr_init(&data->fattr);
1289
1290         /* Set up the initial task struct.  */
1291         NFS_PROTO(inode)->commit_setup(data, &msg);
1292
1293         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1294
1295         task = rpc_run_task(&task_setup_data);
1296         if (IS_ERR(task))
1297                 return PTR_ERR(task);
1298         rpc_put_task(task);
1299         return 0;
1300 }
1301
1302 /*
1303  * Commit dirty pages
1304  */
1305 static int
1306 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1307 {
1308         struct nfs_write_data   *data;
1309         struct nfs_page         *req;
1310
1311         data = nfs_commitdata_alloc();
1312
1313         if (!data)
1314                 goto out_bad;
1315
1316         /* Set up the argument struct */
1317         return nfs_commit_rpcsetup(head, data, how);
1318  out_bad:
1319         while (!list_empty(head)) {
1320                 req = nfs_list_entry(head->next);
1321                 nfs_list_remove_request(req);
1322                 nfs_mark_request_commit(req);
1323                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1324                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1325                                 BDI_RECLAIMABLE);
1326                 nfs_clear_page_tag_locked(req);
1327         }
1328         nfs_commit_clear_lock(NFS_I(inode));
1329         return -ENOMEM;
1330 }
1331
1332 /*
1333  * COMMIT call returned
1334  */
1335 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1336 {
1337         struct nfs_write_data   *data = calldata;
1338
1339         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1340                                 task->tk_pid, task->tk_status);
1341
1342         /* Call the NFS version-specific code */
1343         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1344                 return;
1345 }
1346
1347 static void nfs_commit_release(void *calldata)
1348 {
1349         struct nfs_write_data   *data = calldata;
1350         struct nfs_page         *req;
1351         int status = data->task.tk_status;
1352
1353         while (!list_empty(&data->pages)) {
1354                 req = nfs_list_entry(data->pages.next);
1355                 nfs_list_remove_request(req);
1356                 nfs_clear_request_commit(req);
1357
1358                 dprintk("NFS:       commit (%s/%lld %d@%lld)",
1359                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1360                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1361                         req->wb_bytes,
1362                         (long long)req_offset(req));
1363                 if (status < 0) {
1364                         nfs_context_set_write_error(req->wb_context, status);
1365                         nfs_inode_remove_request(req);
1366                         dprintk(", error = %d\n", status);
1367                         goto next;
1368                 }
1369
1370                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1371                  * returned by the server against all stored verfs. */
1372                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1373                         /* We have a match */
1374                         nfs_inode_remove_request(req);
1375                         dprintk(" OK\n");
1376                         goto next;
1377                 }
1378                 /* We have a mismatch. Write the page again */
1379                 dprintk(" mismatch\n");
1380                 nfs_mark_request_dirty(req);
1381         next:
1382                 nfs_clear_page_tag_locked(req);
1383         }
1384         nfs_commit_clear_lock(NFS_I(data->inode));
1385         nfs_commitdata_release(calldata);
1386 }
1387
1388 static const struct rpc_call_ops nfs_commit_ops = {
1389 #if defined(CONFIG_NFS_V4_1)
1390         .rpc_call_prepare = nfs_write_prepare,
1391 #endif /* CONFIG_NFS_V4_1 */
1392         .rpc_call_done = nfs_commit_done,
1393         .rpc_release = nfs_commit_release,
1394 };
1395
1396 int nfs_commit_inode(struct inode *inode, int how)
1397 {
1398         LIST_HEAD(head);
1399         int may_wait = how & FLUSH_SYNC;
1400         int res = 0;
1401
1402         if (!nfs_commit_set_lock(NFS_I(inode), may_wait))
1403                 goto out_mark_dirty;
1404         spin_lock(&inode->i_lock);
1405         res = nfs_scan_commit(inode, &head, 0, 0);
1406         spin_unlock(&inode->i_lock);
1407         if (res) {
1408                 int error = nfs_commit_list(inode, &head, how);
1409                 if (error < 0)
1410                         return error;
1411                 if (may_wait)
1412                         wait_on_bit(&NFS_I(inode)->flags, NFS_INO_COMMIT,
1413                                         nfs_wait_bit_killable,
1414                                         TASK_KILLABLE);
1415                 else
1416                         goto out_mark_dirty;
1417         } else
1418                 nfs_commit_clear_lock(NFS_I(inode));
1419         return res;
1420         /* Note: If we exit without ensuring that the commit is complete,
1421          * we must mark the inode as dirty. Otherwise, future calls to
1422          * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
1423          * that the data is on the disk.
1424          */
1425 out_mark_dirty:
1426         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1427         return res;
1428 }
1429
1430 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1431 {
1432         struct nfs_inode *nfsi = NFS_I(inode);
1433         int flags = FLUSH_SYNC;
1434         int ret = 0;
1435
1436         /* Don't commit yet if this is a non-blocking flush and there are
1437          * lots of outstanding writes for this mapping.
1438          */
1439         if (wbc->sync_mode == WB_SYNC_NONE &&
1440             nfsi->ncommit <= (nfsi->npages >> 1))
1441                 goto out_mark_dirty;
1442
1443         if (wbc->nonblocking || wbc->for_background)
1444                 flags = 0;
1445         ret = nfs_commit_inode(inode, flags);
1446         if (ret >= 0) {
1447                 if (wbc->sync_mode == WB_SYNC_NONE) {
1448                         if (ret < wbc->nr_to_write)
1449                                 wbc->nr_to_write -= ret;
1450                         else
1451                                 wbc->nr_to_write = 0;
1452                 }
1453                 return 0;
1454         }
1455 out_mark_dirty:
1456         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1457         return ret;
1458 }
1459 #else
1460 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1461 {
1462         return 0;
1463 }
1464 #endif
1465
1466 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1467 {
1468         return nfs_commit_unstable_pages(inode, wbc);
1469 }
1470
1471 /*
1472  * flush the inode to disk.
1473  */
1474 int nfs_wb_all(struct inode *inode)
1475 {
1476         struct writeback_control wbc = {
1477                 .sync_mode = WB_SYNC_ALL,
1478                 .nr_to_write = LONG_MAX,
1479                 .range_start = 0,
1480                 .range_end = LLONG_MAX,
1481         };
1482
1483         return sync_inode(inode, &wbc);
1484 }
1485
1486 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1487 {
1488         struct nfs_page *req;
1489         int ret = 0;
1490
1491         BUG_ON(!PageLocked(page));
1492         for (;;) {
1493                 wait_on_page_writeback(page);
1494                 req = nfs_page_find_request(page);
1495                 if (req == NULL)
1496                         break;
1497                 if (nfs_lock_request_dontget(req)) {
1498                         nfs_inode_remove_request(req);
1499                         /*
1500                          * In case nfs_inode_remove_request has marked the
1501                          * page as being dirty
1502                          */
1503                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1504                         nfs_unlock_request(req);
1505                         break;
1506                 }
1507                 ret = nfs_wait_on_request(req);
1508                 nfs_release_request(req);
1509                 if (ret < 0)
1510                         break;
1511         }
1512         return ret;
1513 }
1514
1515 /*
1516  * Write back all requests on one page - we do this before reading it.
1517  */
1518 int nfs_wb_page(struct inode *inode, struct page *page)
1519 {
1520         loff_t range_start = page_offset(page);
1521         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1522         struct writeback_control wbc = {
1523                 .sync_mode = WB_SYNC_ALL,
1524                 .nr_to_write = 0,
1525                 .range_start = range_start,
1526                 .range_end = range_end,
1527         };
1528         int ret;
1529
1530         for (;;) {
1531                 wait_on_page_writeback(page);
1532                 if (clear_page_dirty_for_io(page)) {
1533                         ret = nfs_writepage_locked(page, &wbc);
1534                         if (ret < 0)
1535                                 goto out_error;
1536                         continue;
1537                 }
1538                 if (!PagePrivate(page))
1539                         break;
1540                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
1541                 if (ret < 0)
1542                         goto out_error;
1543         }
1544         return 0;
1545 out_error:
1546         return ret;
1547 }
1548
1549 #ifdef CONFIG_MIGRATION
1550 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
1551                 struct page *page)
1552 {
1553         struct nfs_page *req;
1554         int ret;
1555
1556         nfs_fscache_release_page(page, GFP_KERNEL);
1557
1558         req = nfs_find_and_lock_request(page, false);
1559         ret = PTR_ERR(req);
1560         if (IS_ERR(req))
1561                 goto out;
1562
1563         ret = migrate_page(mapping, newpage, page);
1564         if (!req)
1565                 goto out;
1566         if (ret)
1567                 goto out_unlock;
1568         page_cache_get(newpage);
1569         spin_lock(&mapping->host->i_lock);
1570         req->wb_page = newpage;
1571         SetPagePrivate(newpage);
1572         set_page_private(newpage, (unsigned long)req);
1573         ClearPagePrivate(page);
1574         set_page_private(page, 0);
1575         spin_unlock(&mapping->host->i_lock);
1576         page_cache_release(page);
1577 out_unlock:
1578         nfs_clear_page_tag_locked(req);
1579 out:
1580         return ret;
1581 }
1582 #endif
1583
1584 int __init nfs_init_writepagecache(void)
1585 {
1586         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1587                                              sizeof(struct nfs_write_data),
1588                                              0, SLAB_HWCACHE_ALIGN,
1589                                              NULL);
1590         if (nfs_wdata_cachep == NULL)
1591                 return -ENOMEM;
1592
1593         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1594                                                      nfs_wdata_cachep);
1595         if (nfs_wdata_mempool == NULL)
1596                 return -ENOMEM;
1597
1598         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1599                                                       nfs_wdata_cachep);
1600         if (nfs_commit_mempool == NULL)
1601                 return -ENOMEM;
1602
1603         /*
1604          * NFS congestion size, scale with available memory.
1605          *
1606          *  64MB:    8192k
1607          * 128MB:   11585k
1608          * 256MB:   16384k
1609          * 512MB:   23170k
1610          *   1GB:   32768k
1611          *   2GB:   46340k
1612          *   4GB:   65536k
1613          *   8GB:   92681k
1614          *  16GB:  131072k
1615          *
1616          * This allows larger machines to have larger/more transfers.
1617          * Limit the default to 256M
1618          */
1619         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1620         if (nfs_congestion_kb > 256*1024)
1621                 nfs_congestion_kb = 256*1024;
1622
1623         return 0;
1624 }
1625
1626 void nfs_destroy_writepagecache(void)
1627 {
1628         mempool_destroy(nfs_commit_mempool);
1629         mempool_destroy(nfs_wdata_mempool);
1630         kmem_cache_destroy(nfs_wdata_cachep);
1631 }
1632