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 #include "pnfs.h"
  32
  33 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  34
  35 #define MIN_POOL_WRITE          (32)
  36 #define MIN_POOL_COMMIT         (4)
  37
  38 /*
  39  * Local function declarations
  40  */
  41 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc,
  42                                   struct inode *inode, int ioflags);
  43 static void nfs_redirty_request(struct nfs_page *req);
  44 static const struct rpc_call_ops nfs_write_partial_ops;
  45 static const struct rpc_call_ops nfs_write_full_ops;
  46 static const struct rpc_call_ops nfs_commit_ops;
  47
  48 static struct kmem_cache *nfs_wdata_cachep;
  49 static mempool_t *nfs_wdata_mempool;
  50 static mempool_t *nfs_commit_mempool;
  51
  52 struct nfs_write_data *nfs_commitdata_alloc(void)
  53 {
  54         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
  55
  56         if (p) {
  57                 memset(p, 0, sizeof(*p));
  58                 INIT_LIST_HEAD(&p->pages);
  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                 if (pagecount <= ARRAY_SIZE(p->page_array))
  79                         p->pagevec = p->page_array;
  80                 else {
  81                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
  82                         if (!p->pagevec) {
  83                                 mempool_free(p, nfs_wdata_mempool);
  84                                 p = NULL;
  85                         }
  86                 }
  87         }
  88         return p;
  89 }
  90
  91 void nfs_writedata_free(struct nfs_write_data *p)
  92 {
  93         if (p && (p->pagevec != &p->page_array[0]))
  94                 kfree(p->pagevec);
  95         mempool_free(p, nfs_wdata_mempool);
  96 }
  97
  98 static void nfs_writedata_release(struct nfs_write_data *wdata)
  99 {
 100         put_lseg(wdata->lseg);
 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 | FLUSH_COND_STABLE;
 183         return FLUSH_COND_STABLE;
 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, wbc->sync_mode == WB_SYNC_NONE);
 296         if (ret == -EAGAIN) {
 297                 redirty_page_for_writepage(wbc, page);
 298                 ret = 0;
 299         }
 300         return ret;
 301 }
 302
 303 /*
 304  * Write an mmapped page to the server.
 305  */
 306 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 307 {
 308         struct nfs_pageio_descriptor pgio;
 309         int err;
 310
 311         nfs_pageio_init_write(&pgio, page->mapping->host, wb_priority(wbc));
 312         err = nfs_do_writepage(page, wbc, &pgio);
 313         nfs_pageio_complete(&pgio);
 314         if (err < 0)
 315                 return err;
 316         if (pgio.pg_error < 0)
 317                 return pgio.pg_error;
 318         return 0;
 319 }
 320
 321 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 322 {
 323         int ret;
 324
 325         ret = nfs_writepage_locked(page, wbc);
 326         unlock_page(page);
 327         return ret;
 328 }
 329
 330 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 331 {
 332         int ret;
 333
 334         ret = nfs_do_writepage(page, wbc, data);
 335         unlock_page(page);
 336         return ret;
 337 }
 338
 339 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 340 {
 341         struct inode *inode = mapping->host;
 342         unsigned long *bitlock = &NFS_I(inode)->flags;
 343         struct nfs_pageio_descriptor pgio;
 344         int err;
 345
 346         /* Stop dirtying of new pages while we sync */
 347         err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
 348                         nfs_wait_bit_killable, TASK_KILLABLE);
 349         if (err)
 350                 goto out_err;
 351
 352         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 353
 354         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
 355         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 356         nfs_pageio_complete(&pgio);
 357
 358         clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
 359         smp_mb__after_clear_bit();
 360         wake_up_bit(bitlock, NFS_INO_FLUSHING);
 361
 362         if (err < 0)
 363                 goto out_err;
 364         err = pgio.pg_error;
 365         if (err < 0)
 366                 goto out_err;
 367         return 0;
 368 out_err:
 369         return err;
 370 }
 371
 372 /*
 373  * Insert a write request into an inode
 374  */
 375 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 376 {
 377         struct nfs_inode *nfsi = NFS_I(inode);
 378         int error;
 379
 380         error = radix_tree_preload(GFP_NOFS);
 381         if (error != 0)
 382                 goto out;
 383
 384         /* Lock the request! */
 385         nfs_lock_request_dontget(req);
 386
 387         spin_lock(&inode->i_lock);
 388         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 389         BUG_ON(error);
 390         if (!nfsi->npages) {
 391                 igrab(inode);
 392                 if (nfs_have_delegation(inode, FMODE_WRITE))
 393                         nfsi->change_attr++;
 394         }
 395         set_bit(PG_MAPPED, &req->wb_flags);
 396         SetPagePrivate(req->wb_page);
 397         set_page_private(req->wb_page, (unsigned long)req);
 398         nfsi->npages++;
 399         kref_get(&req->wb_kref);
 400         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
 401                                 NFS_PAGE_TAG_LOCKED);
 402         spin_unlock(&inode->i_lock);
 403         radix_tree_preload_end();
 404 out:
 405         return error;
 406 }
 407
 408 /*
 409  * Remove a write request from an inode
 410  */
 411 static void nfs_inode_remove_request(struct nfs_page *req)
 412 {
 413         struct inode *inode = req->wb_context->path.dentry->d_inode;
 414         struct nfs_inode *nfsi = NFS_I(inode);
 415
 416         BUG_ON (!NFS_WBACK_BUSY(req));
 417
 418         spin_lock(&inode->i_lock);
 419         set_page_private(req->wb_page, 0);
 420         ClearPagePrivate(req->wb_page);
 421         clear_bit(PG_MAPPED, &req->wb_flags);
 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_release_request(req);
 430 }
 431
 432 static void
 433 nfs_mark_request_dirty(struct nfs_page *req)
 434 {
 435         __set_page_dirty_nobuffers(req->wb_page);
 436         __mark_inode_dirty(req->wb_page->mapping->host, I_DIRTY_DATASYNC);
 437 }
 438
 439 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 440 /*
 441  * Add a request to the inode's commit list.
 442  */
 443 static void
 444 nfs_mark_request_commit(struct nfs_page *req)
 445 {
 446         struct inode *inode = req->wb_context->path.dentry->d_inode;
 447         struct nfs_inode *nfsi = NFS_I(inode);
 448
 449         spin_lock(&inode->i_lock);
 450         set_bit(PG_CLEAN, &(req)->wb_flags);
 451         radix_tree_tag_set(&nfsi->nfs_page_tree,
 452                         req->wb_index,
 453                         NFS_PAGE_TAG_COMMIT);
 454         nfsi->ncommit++;
 455         spin_unlock(&inode->i_lock);
 456         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 457         inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 458         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 459 }
 460
 461 static int
 462 nfs_clear_request_commit(struct nfs_page *req)
 463 {
 464         struct page *page = req->wb_page;
 465
 466         if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
 467                 dec_zone_page_state(page, NR_UNSTABLE_NFS);
 468                 dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 469                 return 1;
 470         }
 471         return 0;
 472 }
 473
 474 static inline
 475 int nfs_write_need_commit(struct nfs_write_data *data)
 476 {
 477         if (data->verf.committed == NFS_DATA_SYNC)
 478                 return data->lseg == NULL;
 479         else
 480                 return data->verf.committed != NFS_FILE_SYNC;
 481 }
 482
 483 static inline
 484 int nfs_reschedule_unstable_write(struct nfs_page *req)
 485 {
 486         if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
 487                 nfs_mark_request_commit(req);
 488                 return 1;
 489         }
 490         if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
 491                 nfs_mark_request_dirty(req);
 492                 return 1;
 493         }
 494         return 0;
 495 }
 496 #else
 497 static inline void
 498 nfs_mark_request_commit(struct nfs_page *req)
 499 {
 500 }
 501
 502 static inline int
 503 nfs_clear_request_commit(struct nfs_page *req)
 504 {
 505         return 0;
 506 }
 507
 508 static inline
 509 int nfs_write_need_commit(struct nfs_write_data *data)
 510 {
 511         return 0;
 512 }
 513
 514 static inline
 515 int nfs_reschedule_unstable_write(struct nfs_page *req)
 516 {
 517         return 0;
 518 }
 519 #endif
 520
 521 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 522 static int
 523 nfs_need_commit(struct nfs_inode *nfsi)
 524 {
 525         return radix_tree_tagged(&nfsi->nfs_page_tree, NFS_PAGE_TAG_COMMIT);
 526 }
 527
 528 /*
 529  * nfs_scan_commit - Scan an inode for commit requests
 530  * @inode: NFS inode to scan
 531  * @dst: destination list
 532  * @idx_start: lower bound of page->index to scan.
 533  * @npages: idx_start + npages sets the upper bound to scan.
 534  *
 535  * Moves requests from the inode's 'commit' request list.
 536  * The requests are *not* checked to ensure that they form a contiguous set.
 537  */
 538 static int
 539 nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 540 {
 541         struct nfs_inode *nfsi = NFS_I(inode);
 542         int ret;
 543
 544         if (!nfs_need_commit(nfsi))
 545                 return 0;
 546
 547         ret = nfs_scan_list(nfsi, dst, idx_start, npages, NFS_PAGE_TAG_COMMIT);
 548         if (ret > 0)
 549                 nfsi->ncommit -= ret;
 550         if (nfs_need_commit(NFS_I(inode)))
 551                 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 552         return ret;
 553 }
 554 #else
 555 static inline int nfs_need_commit(struct nfs_inode *nfsi)
 556 {
 557         return 0;
 558 }
 559
 560 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, unsigned int npages)
 561 {
 562         return 0;
 563 }
 564 #endif
 565
 566 /*
 567  * Search for an existing write request, and attempt to update
 568  * it to reflect a new dirty region on a given page.
 569  *
 570  * If the attempt fails, then the existing request is flushed out
 571  * to disk.
 572  */
 573 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
 574                 struct page *page,
 575                 unsigned int offset,
 576                 unsigned int bytes)
 577 {
 578         struct nfs_page *req;
 579         unsigned int rqend;
 580         unsigned int end;
 581         int error;
 582
 583         if (!PagePrivate(page))
 584                 return NULL;
 585
 586         end = offset + bytes;
 587         spin_lock(&inode->i_lock);
 588
 589         for (;;) {
 590                 req = nfs_page_find_request_locked(page);
 591                 if (req == NULL)
 592                         goto out_unlock;
 593
 594                 rqend = req->wb_offset + req->wb_bytes;
 595                 /*
 596                  * Tell the caller to flush out the request if
 597                  * the offsets are non-contiguous.
 598                  * Note: nfs_flush_incompatible() will already
 599                  * have flushed out requests having wrong owners.
 600                  */
 601                 if (offset > rqend
 602                     || end < req->wb_offset)
 603                         goto out_flushme;
 604
 605                 if (nfs_set_page_tag_locked(req))
 606                         break;
 607
 608                 /* The request is locked, so wait and then retry */
 609                 spin_unlock(&inode->i_lock);
 610                 error = nfs_wait_on_request(req);
 611                 nfs_release_request(req);
 612                 if (error != 0)
 613                         goto out_err;
 614                 spin_lock(&inode->i_lock);
 615         }
 616
 617         if (nfs_clear_request_commit(req) &&
 618                         radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
 619                                 req->wb_index, NFS_PAGE_TAG_COMMIT) != NULL)
 620                 NFS_I(inode)->ncommit--;
 621
 622         /* Okay, the request matches. Update the region */
 623         if (offset < req->wb_offset) {
 624                 req->wb_offset = offset;
 625                 req->wb_pgbase = offset;
 626         }
 627         if (end > rqend)
 628                 req->wb_bytes = end - req->wb_offset;
 629         else
 630                 req->wb_bytes = rqend - req->wb_offset;
 631 out_unlock:
 632         spin_unlock(&inode->i_lock);
 633         return req;
 634 out_flushme:
 635         spin_unlock(&inode->i_lock);
 636         nfs_release_request(req);
 637         error = nfs_wb_page(inode, page);
 638 out_err:
 639         return ERR_PTR(error);
 640 }
 641
 642 /*
 643  * Try to update an existing write request, or create one if there is none.
 644  *
 645  * Note: Should always be called with the Page Lock held to prevent races
 646  * if we have to add a new request. Also assumes that the caller has
 647  * already called nfs_flush_incompatible() if necessary.
 648  */
 649 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
 650                 struct page *page, unsigned int offset, unsigned int bytes)
 651 {
 652         struct inode *inode = page->mapping->host;
 653         struct nfs_page *req;
 654         int error;
 655
 656         req = nfs_try_to_update_request(inode, page, offset, bytes);
 657         if (req != NULL)
 658                 goto out;
 659         req = nfs_create_request(ctx, inode, page, offset, bytes);
 660         if (IS_ERR(req))
 661                 goto out;
 662         error = nfs_inode_add_request(inode, req);
 663         if (error != 0) {
 664                 nfs_release_request(req);
 665                 req = ERR_PTR(error);
 666         }
 667 out:
 668         return req;
 669 }
 670
 671 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 672                 unsigned int offset, unsigned int count)
 673 {
 674         struct nfs_page *req;
 675
 676         req = nfs_setup_write_request(ctx, page, offset, count);
 677         if (IS_ERR(req))
 678                 return PTR_ERR(req);
 679         nfs_mark_request_dirty(req);
 680         /* Update file length */
 681         nfs_grow_file(page, offset, count);
 682         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
 683         nfs_mark_request_dirty(req);
 684         nfs_clear_page_tag_locked(req);
 685         return 0;
 686 }
 687
 688 int nfs_flush_incompatible(struct file *file, struct page *page)
 689 {
 690         struct nfs_open_context *ctx = nfs_file_open_context(file);
 691         struct nfs_page *req;
 692         int do_flush, status;
 693         /*
 694          * Look for a request corresponding to this page. If there
 695          * is one, and it belongs to another file, we flush it out
 696          * before we try to copy anything into the page. Do this
 697          * due to the lack of an ACCESS-type call in NFSv2.
 698          * Also do the same if we find a request from an existing
 699          * dropped page.
 700          */
 701         do {
 702                 req = nfs_page_find_request(page);
 703                 if (req == NULL)
 704                         return 0;
 705                 do_flush = req->wb_page != page || req->wb_context != ctx ||
 706                         req->wb_lock_context->lockowner != current->files ||
 707                         req->wb_lock_context->pid != current->tgid;
 708                 nfs_release_request(req);
 709                 if (!do_flush)
 710                         return 0;
 711                 status = nfs_wb_page(page->mapping->host, page);
 712         } while (status == 0);
 713         return status;
 714 }
 715
 716 /*
 717  * If the page cache is marked as unsafe or invalid, then we can't rely on
 718  * the PageUptodate() flag. In this case, we will need to turn off
 719  * write optimisations that depend on the page contents being correct.
 720  */
 721 static int nfs_write_pageuptodate(struct page *page, struct inode *inode)
 722 {
 723         return PageUptodate(page) &&
 724                 !(NFS_I(inode)->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_DATA));
 725 }
 726
 727 /*
 728  * Update and possibly write a cached page of an NFS file.
 729  *
 730  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 731  * things with a page scheduled for an RPC call (e.g. invalidate it).
 732  */
 733 int nfs_updatepage(struct file *file, struct page *page,
 734                 unsigned int offset, unsigned int count)
 735 {
 736         struct nfs_open_context *ctx = nfs_file_open_context(file);
 737         struct inode    *inode = page->mapping->host;
 738         int             status = 0;
 739
 740         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 741
 742         dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
 743                 file->f_path.dentry->d_parent->d_name.name,
 744                 file->f_path.dentry->d_name.name, count,
 745                 (long long)(page_offset(page) + offset));
 746
 747         /* If we're not using byte range locks, and we know the page
 748          * is up to date, it may be more efficient to extend the write
 749          * to cover the entire page in order to avoid fragmentation
 750          * inefficiencies.
 751          */
 752         if (nfs_write_pageuptodate(page, inode) &&
 753                         inode->i_flock == NULL &&
 754                         !(file->f_flags & O_DSYNC)) {
 755                 count = max(count + offset, nfs_page_length(page));
 756                 offset = 0;
 757         }
 758
 759         status = nfs_writepage_setup(ctx, page, offset, count);
 760         if (status < 0)
 761                 nfs_set_pageerror(page);
 762
 763         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 764                         status, (long long)i_size_read(inode));
 765         return status;
 766 }
 767
 768 static void nfs_writepage_release(struct nfs_page *req)
 769 {
 770         struct page *page = req->wb_page;
 771
 772         if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req))
 773                 nfs_inode_remove_request(req);
 774         nfs_clear_page_tag_locked(req);
 775         nfs_end_page_writeback(page);
 776 }
 777
 778 static int flush_task_priority(int how)
 779 {
 780         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 781                 case FLUSH_HIGHPRI:
 782                         return RPC_PRIORITY_HIGH;
 783                 case FLUSH_LOWPRI:
 784                         return RPC_PRIORITY_LOW;
 785         }
 786         return RPC_PRIORITY_NORMAL;
 787 }
 788
 789 int nfs_initiate_write(struct nfs_write_data *data,
 790                        struct rpc_clnt *clnt,
 791                        const struct rpc_call_ops *call_ops,
 792                        int how)
 793 {
 794         struct inode *inode = data->inode;
 795         int priority = flush_task_priority(how);
 796         struct rpc_task *task;
 797         struct rpc_message msg = {
 798                 .rpc_argp = &data->args,
 799                 .rpc_resp = &data->res,
 800                 .rpc_cred = data->cred,
 801         };
 802         struct rpc_task_setup task_setup_data = {
 803                 .rpc_client = clnt,
 804                 .task = &data->task,
 805                 .rpc_message = &msg,
 806                 .callback_ops = call_ops,
 807                 .callback_data = data,
 808                 .workqueue = nfsiod_workqueue,
 809                 .flags = RPC_TASK_ASYNC,
 810                 .priority = priority,
 811         };
 812         int ret = 0;
 813
 814         /* Set up the initial task struct.  */
 815         NFS_PROTO(inode)->write_setup(data, &msg);
 816
 817         dprintk("NFS: %5u initiated write call "
 818                 "(req %s/%lld, %u bytes @ offset %llu)\n",
 819                 data->task.tk_pid,
 820                 inode->i_sb->s_id,
 821                 (long long)NFS_FILEID(inode),
 822                 data->args.count,
 823                 (unsigned long long)data->args.offset);
 824
 825         task = rpc_run_task(&task_setup_data);
 826         if (IS_ERR(task)) {
 827                 ret = PTR_ERR(task);
 828                 goto out;
 829         }
 830         if (how & FLUSH_SYNC) {
 831                 ret = rpc_wait_for_completion_task(task);
 832                 if (ret == 0)
 833                         ret = task->tk_status;
 834         }
 835         rpc_put_task(task);
 836 out:
 837         return ret;
 838 }
 839 EXPORT_SYMBOL_GPL(nfs_initiate_write);
 840
 841 /*
 842  * Set up the argument/result storage required for the RPC call.
 843  */
 844 static int nfs_write_rpcsetup(struct nfs_page *req,
 845                 struct nfs_write_data *data,
 846                 const struct rpc_call_ops *call_ops,
 847                 unsigned int count, unsigned int offset,
 848                 struct pnfs_layout_segment *lseg,
 849                 int how)
 850 {
 851         struct inode *inode = req->wb_context->path.dentry->d_inode;
 852
 853         /* Set up the RPC argument and reply structs
 854          * NB: take care not to mess about with data->commit et al. */
 855
 856         data->req = req;
 857         data->inode = inode = req->wb_context->path.dentry->d_inode;
 858         data->cred = req->wb_context->cred;
 859         data->lseg = get_lseg(lseg);
 860
 861         data->args.fh     = NFS_FH(inode);
 862         data->args.offset = req_offset(req) + offset;
 863         data->args.pgbase = req->wb_pgbase + offset;
 864         data->args.pages  = data->pagevec;
 865         data->args.count  = count;
 866         data->args.context = get_nfs_open_context(req->wb_context);
 867         data->args.lock_context = req->wb_lock_context;
 868         data->args.stable  = NFS_UNSTABLE;
 869         if (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 870                 data->args.stable = NFS_DATA_SYNC;
 871                 if (!nfs_need_commit(NFS_I(inode)))
 872                         data->args.stable = NFS_FILE_SYNC;
 873         }
 874
 875         data->res.fattr   = &data->fattr;
 876         data->res.count   = count;
 877         data->res.verf    = &data->verf;
 878         nfs_fattr_init(&data->fattr);
 879
 880         if (data->lseg &&
 881             (pnfs_try_to_write_data(data, call_ops, how) == PNFS_ATTEMPTED))
 882                 return 0;
 883
 884         return nfs_initiate_write(data, NFS_CLIENT(inode), call_ops, how);
 885 }
 886
 887 /* If a nfs_flush_* function fails, it should remove reqs from @head and
 888  * call this on each, which will prepare them to be retried on next
 889  * writeback using standard nfs.
 890  */
 891 static void nfs_redirty_request(struct nfs_page *req)
 892 {
 893         struct page *page = req->wb_page;
 894
 895         nfs_mark_request_dirty(req);
 896         nfs_clear_page_tag_locked(req);
 897         nfs_end_page_writeback(page);
 898 }
 899
 900 /*
 901  * Generate multiple small requests to write out a single
 902  * contiguous dirty area on one page.
 903  */
 904 static int nfs_flush_multi(struct nfs_pageio_descriptor *desc)
 905 {
 906         struct nfs_page *req = nfs_list_entry(desc->pg_list.next);
 907         struct page *page = req->wb_page;
 908         struct nfs_write_data *data;
 909         size_t wsize = NFS_SERVER(desc->pg_inode)->wsize, nbytes;
 910         unsigned int offset;
 911         int requests = 0;
 912         int ret = 0;
 913         struct pnfs_layout_segment *lseg;
 914         LIST_HEAD(list);
 915
 916         nfs_list_remove_request(req);
 917
 918         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 919             (desc->pg_moreio || NFS_I(desc->pg_inode)->ncommit ||
 920              desc->pg_count > wsize))
 921                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 922
 923
 924         nbytes = desc->pg_count;
 925         do {
 926                 size_t len = min(nbytes, wsize);
 927
 928                 data = nfs_writedata_alloc(1);
 929                 if (!data)
 930                         goto out_bad;
 931                 list_add(&data->pages, &list);
 932                 requests++;
 933                 nbytes -= len;
 934         } while (nbytes != 0);
 935         atomic_set(&req->wb_complete, requests);
 936
 937         BUG_ON(desc->pg_lseg);
 938         lseg = pnfs_update_layout(desc->pg_inode, req->wb_context, IOMODE_RW);
 939         ClearPageError(page);
 940         offset = 0;
 941         nbytes = desc->pg_count;
 942         do {
 943                 int ret2;
 944
 945                 data = list_entry(list.next, struct nfs_write_data, pages);
 946                 list_del_init(&data->pages);
 947
 948                 data->pagevec[0] = page;
 949
 950                 if (nbytes < wsize)
 951                         wsize = nbytes;
 952                 ret2 = nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 953                                           wsize, offset, lseg, desc->pg_ioflags);
 954                 if (ret == 0)
 955                         ret = ret2;
 956                 offset += wsize;
 957                 nbytes -= wsize;
 958         } while (nbytes != 0);
 959
 960         put_lseg(lseg);
 961         desc->pg_lseg = NULL;
 962         return ret;
 963
 964 out_bad:
 965         while (!list_empty(&list)) {
 966                 data = list_entry(list.next, struct nfs_write_data, pages);
 967                 list_del(&data->pages);
 968                 nfs_writedata_free(data);
 969         }
 970         nfs_redirty_request(req);
 971         return -ENOMEM;
 972 }
 973
 974 /*
 975  * Create an RPC task for the given write request and kick it.
 976  * The page must have been locked by the caller.
 977  *
 978  * It may happen that the page we're passed is not marked dirty.
 979  * This is the case if nfs_updatepage detects a conflicting request
 980  * that has been written but not committed.
 981  */
 982 static int nfs_flush_one(struct nfs_pageio_descriptor *desc)
 983 {
 984         struct nfs_page         *req;
 985         struct page             **pages;
 986         struct nfs_write_data   *data;
 987         struct list_head *head = &desc->pg_list;
 988         struct pnfs_layout_segment *lseg = desc->pg_lseg;
 989         int ret;
 990
 991         data = nfs_writedata_alloc(nfs_page_array_len(desc->pg_base,
 992                                                       desc->pg_count));
 993         if (!data) {
 994                 while (!list_empty(head)) {
 995                         req = nfs_list_entry(head->next);
 996                         nfs_list_remove_request(req);
 997                         nfs_redirty_request(req);
 998                 }
 999                 ret = -ENOMEM;
1000                 goto out;
1001         }
1002         pages = data->pagevec;
1003         while (!list_empty(head)) {
1004                 req = nfs_list_entry(head->next);
1005                 nfs_list_remove_request(req);
1006                 nfs_list_add_request(req, &data->pages);
1007                 ClearPageError(req->wb_page);
1008                 *pages++ = req->wb_page;
1009         }
1010         req = nfs_list_entry(data->pages.next);
1011         if ((!lseg) && list_is_singular(&data->pages))
1012                 lseg = pnfs_update_layout(desc->pg_inode, req->wb_context, IOMODE_RW);
1013
1014         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1015             (desc->pg_moreio || NFS_I(desc->pg_inode)->ncommit))
1016                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1017
1018         /* Set up the argument struct */
1019         ret = nfs_write_rpcsetup(req, data, &nfs_write_full_ops, desc->pg_count, 0, lseg, desc->pg_ioflags);
1020 out:
1021         put_lseg(lseg); /* Cleans any gotten in ->pg_test */
1022         desc->pg_lseg = NULL;
1023         return ret;
1024 }
1025
1026 static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1027                                   struct inode *inode, int ioflags)
1028 {
1029         size_t wsize = NFS_SERVER(inode)->wsize;
1030
1031         pnfs_pageio_init_write(pgio, inode);
1032
1033         if (wsize < PAGE_CACHE_SIZE)
1034                 nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
1035         else
1036                 nfs_pageio_init(pgio, inode, nfs_flush_one, wsize, ioflags);
1037 }
1038
1039 /*
1040  * Handle a write reply that flushed part of a page.
1041  */
1042 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
1043 {
1044         struct nfs_write_data   *data = calldata;
1045
1046         dprintk("NFS: %5u write(%s/%lld %d@%lld)",
1047                 task->tk_pid,
1048                 data->req->wb_context->path.dentry->d_inode->i_sb->s_id,
1049                 (long long)
1050                   NFS_FILEID(data->req->wb_context->path.dentry->d_inode),
1051                 data->req->wb_bytes, (long long)req_offset(data->req));
1052
1053         nfs_writeback_done(task, data);
1054 }
1055
1056 static void nfs_writeback_release_partial(void *calldata)
1057 {
1058         struct nfs_write_data   *data = calldata;
1059         struct nfs_page         *req = data->req;
1060         struct page             *page = req->wb_page;
1061         int status = data->task.tk_status;
1062
1063         if (status < 0) {
1064                 nfs_set_pageerror(page);
1065                 nfs_context_set_write_error(req->wb_context, status);
1066                 dprintk(", error = %d\n", status);
1067                 goto out;
1068         }
1069
1070         if (nfs_write_need_commit(data)) {
1071                 struct inode *inode = page->mapping->host;
1072
1073                 spin_lock(&inode->i_lock);
1074                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
1075                         /* Do nothing we need to resend the writes */
1076                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
1077                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1078                         dprintk(" defer commit\n");
1079                 } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1080                         set_bit(PG_NEED_RESCHED, &req->wb_flags);
1081                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
1082                         dprintk(" server reboot detected\n");
1083                 }
1084                 spin_unlock(&inode->i_lock);
1085         } else
1086                 dprintk(" OK\n");
1087
1088 out:
1089         if (atomic_dec_and_test(&req->wb_complete))
1090                 nfs_writepage_release(req);
1091         nfs_writedata_release(calldata);
1092 }
1093
1094 #if defined(CONFIG_NFS_V4_1)
1095 void nfs_write_prepare(struct rpc_task *task, void *calldata)
1096 {
1097         struct nfs_write_data *data = calldata;
1098
1099         if (nfs4_setup_sequence(NFS_SERVER(data->inode),
1100                                 &data->args.seq_args,
1101                                 &data->res.seq_res, 1, task))
1102                 return;
1103         rpc_call_start(task);
1104 }
1105 #endif /* CONFIG_NFS_V4_1 */
1106
1107 static const struct rpc_call_ops nfs_write_partial_ops = {
1108 #if defined(CONFIG_NFS_V4_1)
1109         .rpc_call_prepare = nfs_write_prepare,
1110 #endif /* CONFIG_NFS_V4_1 */
1111         .rpc_call_done = nfs_writeback_done_partial,
1112         .rpc_release = nfs_writeback_release_partial,
1113 };
1114
1115 /*
1116  * Handle a write reply that flushes a whole page.
1117  *
1118  * FIXME: There is an inherent race with invalidate_inode_pages and
1119  *        writebacks since the page->count is kept > 1 for as long
1120  *        as the page has a write request pending.
1121  */
1122 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1123 {
1124         struct nfs_write_data   *data = calldata;
1125
1126         nfs_writeback_done(task, data);
1127 }
1128
1129 static void nfs_writeback_release_full(void *calldata)
1130 {
1131         struct nfs_write_data   *data = calldata;
1132         int status = data->task.tk_status;
1133
1134         /* Update attributes as result of writeback. */
1135         while (!list_empty(&data->pages)) {
1136                 struct nfs_page *req = nfs_list_entry(data->pages.next);
1137                 struct page *page = req->wb_page;
1138
1139                 nfs_list_remove_request(req);
1140
1141                 dprintk("NFS: %5u write (%s/%lld %d@%lld)",
1142                         data->task.tk_pid,
1143                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1144                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1145                         req->wb_bytes,
1146                         (long long)req_offset(req));
1147
1148                 if (status < 0) {
1149                         nfs_set_pageerror(page);
1150                         nfs_context_set_write_error(req->wb_context, status);
1151                         dprintk(", error = %d\n", status);
1152                         goto remove_request;
1153                 }
1154
1155                 if (nfs_write_need_commit(data)) {
1156                         memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1157                         nfs_mark_request_commit(req);
1158                         dprintk(" marked for commit\n");
1159                         goto next;
1160                 }
1161                 dprintk(" OK\n");
1162 remove_request:
1163                 nfs_inode_remove_request(req);
1164         next:
1165                 nfs_clear_page_tag_locked(req);
1166                 nfs_end_page_writeback(page);
1167         }
1168         nfs_writedata_release(calldata);
1169 }
1170
1171 static const struct rpc_call_ops nfs_write_full_ops = {
1172 #if defined(CONFIG_NFS_V4_1)
1173         .rpc_call_prepare = nfs_write_prepare,
1174 #endif /* CONFIG_NFS_V4_1 */
1175         .rpc_call_done = nfs_writeback_done_full,
1176         .rpc_release = nfs_writeback_release_full,
1177 };
1178
1179
1180 /*
1181  * This function is called when the WRITE call is complete.
1182  */
1183 void nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1184 {
1185         struct nfs_writeargs    *argp = &data->args;
1186         struct nfs_writeres     *resp = &data->res;
1187         struct nfs_server       *server = NFS_SERVER(data->inode);
1188         int status;
1189
1190         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1191                 task->tk_pid, task->tk_status);
1192
1193         /*
1194          * ->write_done will attempt to use post-op attributes to detect
1195          * conflicting writes by other clients.  A strict interpretation
1196          * of close-to-open would allow us to continue caching even if
1197          * another writer had changed the file, but some applications
1198          * depend on tighter cache coherency when writing.
1199          */
1200         status = NFS_PROTO(data->inode)->write_done(task, data);
1201         if (status != 0)
1202                 return;
1203         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1204
1205 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1206         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1207                 /* We tried a write call, but the server did not
1208                  * commit data to stable storage even though we
1209                  * requested it.
1210                  * Note: There is a known bug in Tru64 < 5.0 in which
1211                  *       the server reports NFS_DATA_SYNC, but performs
1212                  *       NFS_FILE_SYNC. We therefore implement this checking
1213                  *       as a dprintk() in order to avoid filling syslog.
1214                  */
1215                 static unsigned long    complain;
1216
1217                 /* Note this will print the MDS for a DS write */
1218                 if (time_before(complain, jiffies)) {
1219                         dprintk("NFS:       faulty NFS server %s:"
1220                                 " (committed = %d) != (stable = %d)\n",
1221                                 server->nfs_client->cl_hostname,
1222                                 resp->verf->committed, argp->stable);
1223                         complain = jiffies + 300 * HZ;
1224                 }
1225         }
1226 #endif
1227         /* Is this a short write? */
1228         if (task->tk_status >= 0 && resp->count < argp->count) {
1229                 static unsigned long    complain;
1230
1231                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1232
1233                 /* Has the server at least made some progress? */
1234                 if (resp->count != 0) {
1235                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1236                         if (resp->verf->committed != NFS_UNSTABLE) {
1237                                 /* Resend from where the server left off */
1238                                 data->mds_offset += resp->count;
1239                                 argp->offset += resp->count;
1240                                 argp->pgbase += resp->count;
1241                                 argp->count -= resp->count;
1242                         } else {
1243                                 /* Resend as a stable write in order to avoid
1244                                  * headaches in the case of a server crash.
1245                                  */
1246                                 argp->stable = NFS_FILE_SYNC;
1247                         }
1248                         nfs_restart_rpc(task, server->nfs_client);
1249                         return;
1250                 }
1251                 if (time_before(complain, jiffies)) {
1252                         printk(KERN_WARNING
1253                                "NFS: Server wrote zero bytes, expected %u.\n",
1254                                         argp->count);
1255                         complain = jiffies + 300 * HZ;
1256                 }
1257                 /* Can't do anything about it except throw an error. */
1258                 task->tk_status = -EIO;
1259         }
1260         return;
1261 }
1262
1263
1264 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1265 static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
1266 {
1267         int ret;
1268
1269         if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
1270                 return 1;
1271         if (!may_wait)
1272                 return 0;
1273         ret = out_of_line_wait_on_bit_lock(&nfsi->flags,
1274                                 NFS_INO_COMMIT,
1275                                 nfs_wait_bit_killable,
1276                                 TASK_KILLABLE);
1277         return (ret < 0) ? ret : 1;
1278 }
1279
1280 static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
1281 {
1282         clear_bit(NFS_INO_COMMIT, &nfsi->flags);
1283         smp_mb__after_clear_bit();
1284         wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
1285 }
1286
1287
1288 static void nfs_commitdata_release(void *data)
1289 {
1290         struct nfs_write_data *wdata = data;
1291
1292         put_nfs_open_context(wdata->args.context);
1293         nfs_commit_free(wdata);
1294 }
1295
1296 /*
1297  * Set up the argument/result storage required for the RPC call.
1298  */
1299 static int nfs_commit_rpcsetup(struct list_head *head,
1300                 struct nfs_write_data *data,
1301                 int how)
1302 {
1303         struct nfs_page *first = nfs_list_entry(head->next);
1304         struct inode *inode = first->wb_context->path.dentry->d_inode;
1305         int priority = flush_task_priority(how);
1306         struct rpc_task *task;
1307         struct rpc_message msg = {
1308                 .rpc_argp = &data->args,
1309                 .rpc_resp = &data->res,
1310                 .rpc_cred = first->wb_context->cred,
1311         };
1312         struct rpc_task_setup task_setup_data = {
1313                 .task = &data->task,
1314                 .rpc_client = NFS_CLIENT(inode),
1315                 .rpc_message = &msg,
1316                 .callback_ops = &nfs_commit_ops,
1317                 .callback_data = data,
1318                 .workqueue = nfsiod_workqueue,
1319                 .flags = RPC_TASK_ASYNC,
1320                 .priority = priority,
1321         };
1322
1323         /* Set up the RPC argument and reply structs
1324          * NB: take care not to mess about with data->commit et al. */
1325
1326         list_splice_init(head, &data->pages);
1327
1328         data->inode       = inode;
1329         data->cred        = msg.rpc_cred;
1330
1331         data->args.fh     = NFS_FH(data->inode);
1332         /* Note: we always request a commit of the entire inode */
1333         data->args.offset = 0;
1334         data->args.count  = 0;
1335         data->args.context = get_nfs_open_context(first->wb_context);
1336         data->res.count   = 0;
1337         data->res.fattr   = &data->fattr;
1338         data->res.verf    = &data->verf;
1339         nfs_fattr_init(&data->fattr);
1340
1341         /* Set up the initial task struct.  */
1342         NFS_PROTO(inode)->commit_setup(data, &msg);
1343
1344         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1345
1346         task = rpc_run_task(&task_setup_data);
1347         if (IS_ERR(task))
1348                 return PTR_ERR(task);
1349         if (how & FLUSH_SYNC)
1350                 rpc_wait_for_completion_task(task);
1351         rpc_put_task(task);
1352         return 0;
1353 }
1354
1355 /*
1356  * Commit dirty pages
1357  */
1358 static int
1359 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1360 {
1361         struct nfs_write_data   *data;
1362         struct nfs_page         *req;
1363
1364         data = nfs_commitdata_alloc();
1365
1366         if (!data)
1367                 goto out_bad;
1368
1369         /* Set up the argument struct */
1370         return nfs_commit_rpcsetup(head, data, how);
1371  out_bad:
1372         while (!list_empty(head)) {
1373                 req = nfs_list_entry(head->next);
1374                 nfs_list_remove_request(req);
1375                 nfs_mark_request_commit(req);
1376                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1377                 dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
1378                                 BDI_RECLAIMABLE);
1379                 nfs_clear_page_tag_locked(req);
1380         }
1381         nfs_commit_clear_lock(NFS_I(inode));
1382         return -ENOMEM;
1383 }
1384
1385 /*
1386  * COMMIT call returned
1387  */
1388 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1389 {
1390         struct nfs_write_data   *data = calldata;
1391
1392         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1393                                 task->tk_pid, task->tk_status);
1394
1395         /* Call the NFS version-specific code */
1396         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1397                 return;
1398 }
1399
1400 static void nfs_commit_release(void *calldata)
1401 {
1402         struct nfs_write_data   *data = calldata;
1403         struct nfs_page         *req;
1404         int status = data->task.tk_status;
1405
1406         while (!list_empty(&data->pages)) {
1407                 req = nfs_list_entry(data->pages.next);
1408                 nfs_list_remove_request(req);
1409                 nfs_clear_request_commit(req);
1410
1411                 dprintk("NFS:       commit (%s/%lld %d@%lld)",
1412                         req->wb_context->path.dentry->d_inode->i_sb->s_id,
1413                         (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
1414                         req->wb_bytes,
1415                         (long long)req_offset(req));
1416                 if (status < 0) {
1417                         nfs_context_set_write_error(req->wb_context, status);
1418                         nfs_inode_remove_request(req);
1419                         dprintk(", error = %d\n", status);
1420                         goto next;
1421                 }
1422
1423                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1424                  * returned by the server against all stored verfs. */
1425                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1426                         /* We have a match */
1427                         nfs_inode_remove_request(req);
1428                         dprintk(" OK\n");
1429                         goto next;
1430                 }
1431                 /* We have a mismatch. Write the page again */
1432                 dprintk(" mismatch\n");
1433                 nfs_mark_request_dirty(req);
1434         next:
1435                 nfs_clear_page_tag_locked(req);
1436         }
1437         nfs_commit_clear_lock(NFS_I(data->inode));
1438         nfs_commitdata_release(calldata);
1439 }
1440
1441 static const struct rpc_call_ops nfs_commit_ops = {
1442 #if defined(CONFIG_NFS_V4_1)
1443         .rpc_call_prepare = nfs_write_prepare,
1444 #endif /* CONFIG_NFS_V4_1 */
1445         .rpc_call_done = nfs_commit_done,
1446         .rpc_release = nfs_commit_release,
1447 };
1448
1449 int nfs_commit_inode(struct inode *inode, int how)
1450 {
1451         LIST_HEAD(head);
1452         int may_wait = how & FLUSH_SYNC;
1453         int res;
1454
1455         res = nfs_commit_set_lock(NFS_I(inode), may_wait);
1456         if (res <= 0)
1457                 goto out_mark_dirty;
1458         spin_lock(&inode->i_lock);
1459         res = nfs_scan_commit(inode, &head, 0, 0);
1460         spin_unlock(&inode->i_lock);
1461         if (res) {
1462                 int error = nfs_commit_list(inode, &head, how);
1463                 if (error < 0)
1464                         return error;
1465                 if (!may_wait)
1466                         goto out_mark_dirty;
1467                 error = wait_on_bit(&NFS_I(inode)->flags,
1468                                 NFS_INO_COMMIT,
1469                                 nfs_wait_bit_killable,
1470                                 TASK_KILLABLE);
1471                 if (error < 0)
1472                         return error;
1473         } else
1474                 nfs_commit_clear_lock(NFS_I(inode));
1475         return res;
1476         /* Note: If we exit without ensuring that the commit is complete,
1477          * we must mark the inode as dirty. Otherwise, future calls to
1478          * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
1479          * that the data is on the disk.
1480          */
1481 out_mark_dirty:
1482         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1483         return res;
1484 }
1485
1486 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1487 {
1488         struct nfs_inode *nfsi = NFS_I(inode);
1489         int flags = FLUSH_SYNC;
1490         int ret = 0;
1491
1492         if (wbc->sync_mode == WB_SYNC_NONE) {
1493                 /* Don't commit yet if this is a non-blocking flush and there
1494                  * are a lot of outstanding writes for this mapping.
1495                  */
1496                 if (nfsi->ncommit <= (nfsi->npages >> 1))
1497                         goto out_mark_dirty;
1498
1499                 /* don't wait for the COMMIT response */
1500                 flags = 0;
1501         }
1502
1503         ret = nfs_commit_inode(inode, flags);
1504         if (ret >= 0) {
1505                 if (wbc->sync_mode == WB_SYNC_NONE) {
1506                         if (ret < wbc->nr_to_write)
1507                                 wbc->nr_to_write -= ret;
1508                         else
1509                                 wbc->nr_to_write = 0;
1510                 }
1511                 return 0;
1512         }
1513 out_mark_dirty:
1514         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1515         return ret;
1516 }
1517 #else
1518 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1519 {
1520         return 0;
1521 }
1522 #endif
1523
1524 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1525 {
1526         return nfs_commit_unstable_pages(inode, wbc);
1527 }
1528
1529 /*
1530  * flush the inode to disk.
1531  */
1532 int nfs_wb_all(struct inode *inode)
1533 {
1534         struct writeback_control wbc = {
1535                 .sync_mode = WB_SYNC_ALL,
1536                 .nr_to_write = LONG_MAX,
1537                 .range_start = 0,
1538                 .range_end = LLONG_MAX,
1539         };
1540
1541         return sync_inode(inode, &wbc);
1542 }
1543
1544 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1545 {
1546         struct nfs_page *req;
1547         int ret = 0;
1548
1549         BUG_ON(!PageLocked(page));
1550         for (;;) {
1551                 wait_on_page_writeback(page);
1552                 req = nfs_page_find_request(page);
1553                 if (req == NULL)
1554                         break;
1555                 if (nfs_lock_request_dontget(req)) {
1556                         nfs_inode_remove_request(req);
1557                         /*
1558                          * In case nfs_inode_remove_request has marked the
1559                          * page as being dirty
1560                          */
1561                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1562                         nfs_unlock_request(req);
1563                         break;
1564                 }
1565                 ret = nfs_wait_on_request(req);
1566                 nfs_release_request(req);
1567                 if (ret < 0)
1568                         break;
1569         }
1570         return ret;
1571 }
1572
1573 /*
1574  * Write back all requests on one page - we do this before reading it.
1575  */
1576 int nfs_wb_page(struct inode *inode, struct page *page)
1577 {
1578         loff_t range_start = page_offset(page);
1579         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1580         struct writeback_control wbc = {
1581                 .sync_mode = WB_SYNC_ALL,
1582                 .nr_to_write = 0,
1583                 .range_start = range_start,
1584                 .range_end = range_end,
1585         };
1586         int ret;
1587
1588         for (;;) {
1589                 wait_on_page_writeback(page);
1590                 if (clear_page_dirty_for_io(page)) {
1591                         ret = nfs_writepage_locked(page, &wbc);
1592                         if (ret < 0)
1593                                 goto out_error;
1594                         continue;
1595                 }
1596                 if (!PagePrivate(page))
1597                         break;
1598                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
1599                 if (ret < 0)
1600                         goto out_error;
1601         }
1602         return 0;
1603 out_error:
1604         return ret;
1605 }
1606
1607 #ifdef CONFIG_MIGRATION
1608 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
1609                 struct page *page)
1610 {
1611         struct nfs_page *req;
1612         int ret;
1613
1614         nfs_fscache_release_page(page, GFP_KERNEL);
1615
1616         req = nfs_find_and_lock_request(page, false);
1617         ret = PTR_ERR(req);
1618         if (IS_ERR(req))
1619                 goto out;
1620
1621         ret = migrate_page(mapping, newpage, page);
1622         if (!req)
1623                 goto out;
1624         if (ret)
1625                 goto out_unlock;
1626         page_cache_get(newpage);
1627         spin_lock(&mapping->host->i_lock);
1628         req->wb_page = newpage;
1629         SetPagePrivate(newpage);
1630         set_page_private(newpage, (unsigned long)req);
1631         ClearPagePrivate(page);
1632         set_page_private(page, 0);
1633         spin_unlock(&mapping->host->i_lock);
1634         page_cache_release(page);
1635 out_unlock:
1636         nfs_clear_page_tag_locked(req);
1637 out:
1638         return ret;
1639 }
1640 #endif
1641
1642 int __init nfs_init_writepagecache(void)
1643 {
1644         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1645                                              sizeof(struct nfs_write_data),
1646                                              0, SLAB_HWCACHE_ALIGN,
1647                                              NULL);
1648         if (nfs_wdata_cachep == NULL)
1649                 return -ENOMEM;
1650
1651         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1652                                                      nfs_wdata_cachep);
1653         if (nfs_wdata_mempool == NULL)
1654                 return -ENOMEM;
1655
1656         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1657                                                       nfs_wdata_cachep);
1658         if (nfs_commit_mempool == NULL)
1659                 return -ENOMEM;
1660
1661         /*
1662          * NFS congestion size, scale with available memory.
1663          *
1664          *  64MB:    8192k
1665          * 128MB:   11585k
1666          * 256MB:   16384k
1667          * 512MB:   23170k
1668          *   1GB:   32768k
1669          *   2GB:   46340k
1670          *   4GB:   65536k
1671          *   8GB:   92681k
1672          *  16GB:  131072k
1673          *
1674          * This allows larger machines to have larger/more transfers.
1675          * Limit the default to 256M
1676          */
1677         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1678         if (nfs_congestion_kb > 256*1024)
1679                 nfs_congestion_kb = 256*1024;
1680
1681         return 0;
1682 }
1683
1684 void nfs_destroy_writepagecache(void)
1685 {
1686         mempool_destroy(nfs_commit_mempool);
1687         mempool_destroy(nfs_wdata_mempool);
1688         kmem_cache_destroy(nfs_wdata_cachep);
1689 }
1690