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 #include <linux/export.h>
  24
  25 #include <asm/uaccess.h>
  26
  27 #include "delegation.h"
  28 #include "internal.h"
  29 #include "iostat.h"
  30 #include "nfs4_fs.h"
  31 #include "fscache.h"
  32 #include "pnfs.h"
  33
  34 #include "nfstrace.h"
  35
  36 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  37
  38 #define MIN_POOL_WRITE          (32)
  39 #define MIN_POOL_COMMIT         (4)
  40
  41 /*
  42  * Local function declarations
  43  */
  44 static void nfs_redirty_request(struct nfs_page *req);
  45 static const struct rpc_call_ops nfs_write_common_ops;
  46 static const struct rpc_call_ops nfs_commit_ops;
  47 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  48 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  49
  50 static struct kmem_cache *nfs_wdata_cachep;
  51 static mempool_t *nfs_wdata_mempool;
  52 static struct kmem_cache *nfs_cdata_cachep;
  53 static mempool_t *nfs_commit_mempool;
  54
  55 struct nfs_commit_data *nfs_commitdata_alloc(void)
  56 {
  57         struct nfs_commit_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
  58
  59         if (p) {
  60                 memset(p, 0, sizeof(*p));
  61                 INIT_LIST_HEAD(&p->pages);
  62         }
  63         return p;
  64 }
  65 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  66
  67 void nfs_commit_free(struct nfs_commit_data *p)
  68 {
  69         mempool_free(p, nfs_commit_mempool);
  70 }
  71 EXPORT_SYMBOL_GPL(nfs_commit_free);
  72
  73 struct nfs_write_header *nfs_writehdr_alloc(void)
  74 {
  75         struct nfs_write_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
  76
  77         if (p) {
  78                 struct nfs_pgio_header *hdr = &p->header;
  79
  80                 memset(p, 0, sizeof(*p));
  81                 INIT_LIST_HEAD(&hdr->pages);
  82                 INIT_LIST_HEAD(&hdr->rpc_list);
  83                 spin_lock_init(&hdr->lock);
  84                 atomic_set(&hdr->refcnt, 0);
  85                 hdr->verf = &p->verf;
  86         }
  87         return p;
  88 }
  89 EXPORT_SYMBOL_GPL(nfs_writehdr_alloc);
  90
  91 static struct nfs_write_data *nfs_writedata_alloc(struct nfs_pgio_header *hdr,
  92                                                   unsigned int pagecount)
  93 {
  94         struct nfs_write_data *data, *prealloc;
  95
  96         prealloc = &container_of(hdr, struct nfs_write_header, header)->rpc_data;
  97         if (prealloc->header == NULL)
  98                 data = prealloc;
  99         else
 100                 data = kzalloc(sizeof(*data), GFP_KERNEL);
 101         if (!data)
 102                 goto out;
 103
 104         if (nfs_pgarray_set(&data->pages, pagecount)) {
 105                 data->header = hdr;
 106                 atomic_inc(&hdr->refcnt);
 107         } else {
 108                 if (data != prealloc)
 109                         kfree(data);
 110                 data = NULL;
 111         }
 112 out:
 113         return data;
 114 }
 115
 116 void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 117 {
 118         struct nfs_write_header *whdr = container_of(hdr, struct nfs_write_header, header);
 119         mempool_free(whdr, nfs_wdata_mempool);
 120 }
 121 EXPORT_SYMBOL_GPL(nfs_writehdr_free);
 122
 123 void nfs_writedata_release(struct nfs_write_data *wdata)
 124 {
 125         struct nfs_pgio_header *hdr = wdata->header;
 126         struct nfs_write_header *write_header = container_of(hdr, struct nfs_write_header, header);
 127
 128         put_nfs_open_context(wdata->args.context);
 129         if (wdata->pages.pagevec != wdata->pages.page_array)
 130                 kfree(wdata->pages.pagevec);
 131         if (wdata == &write_header->rpc_data) {
 132                 wdata->header = NULL;
 133                 wdata = NULL;
 134         }
 135         if (atomic_dec_and_test(&hdr->refcnt))
 136                 hdr->completion_ops->completion(hdr);
 137         /* Note: we only free the rpc_task after callbacks are done.
 138          * See the comment in rpc_free_task() for why
 139          */
 140         kfree(wdata);
 141 }
 142 EXPORT_SYMBOL_GPL(nfs_writedata_release);
 143
 144 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 145 {
 146         ctx->error = error;
 147         smp_wmb();
 148         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 149 }
 150
 151 static struct nfs_page *
 152 nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
 153 {
 154         struct nfs_page *req = NULL;
 155
 156         if (PagePrivate(page))
 157                 req = (struct nfs_page *)page_private(page);
 158         else if (unlikely(PageSwapCache(page))) {
 159                 struct nfs_page *freq, *t;
 160
 161                 /* Linearly search the commit list for the correct req */
 162                 list_for_each_entry_safe(freq, t, &nfsi->commit_info.list, wb_list) {
 163                         if (freq->wb_page == page) {
 164                                 req = freq;
 165                                 break;
 166                         }
 167                 }
 168         }
 169
 170         if (req)
 171                 kref_get(&req->wb_kref);
 172
 173         return req;
 174 }
 175
 176 static struct nfs_page *nfs_page_find_request(struct page *page)
 177 {
 178         struct inode *inode = page_file_mapping(page)->host;
 179         struct nfs_page *req = NULL;
 180
 181         spin_lock(&inode->i_lock);
 182         req = nfs_page_find_request_locked(NFS_I(inode), page);
 183         spin_unlock(&inode->i_lock);
 184         return req;
 185 }
 186
 187 /* Adjust the file length if we're writing beyond the end */
 188 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 189 {
 190         struct inode *inode = page_file_mapping(page)->host;
 191         loff_t end, i_size;
 192         pgoff_t end_index;
 193
 194         spin_lock(&inode->i_lock);
 195         i_size = i_size_read(inode);
 196         end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 197         if (i_size > 0 && page_file_index(page) < end_index)
 198                 goto out;
 199         end = page_file_offset(page) + ((loff_t)offset+count);
 200         if (i_size >= end)
 201                 goto out;
 202         i_size_write(inode, end);
 203         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 204 out:
 205         spin_unlock(&inode->i_lock);
 206 }
 207
 208 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 209 static void nfs_set_pageerror(struct page *page)
 210 {
 211         nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
 212 }
 213
 214 /* We can set the PG_uptodate flag if we see that a write request
 215  * covers the full page.
 216  */
 217 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 218 {
 219         if (PageUptodate(page))
 220                 return;
 221         if (base != 0)
 222                 return;
 223         if (count != nfs_page_length(page))
 224                 return;
 225         SetPageUptodate(page);
 226 }
 227
 228 static int wb_priority(struct writeback_control *wbc)
 229 {
 230         if (wbc->for_reclaim)
 231                 return FLUSH_HIGHPRI | FLUSH_STABLE;
 232         if (wbc->for_kupdate || wbc->for_background)
 233                 return FLUSH_LOWPRI | FLUSH_COND_STABLE;
 234         return FLUSH_COND_STABLE;
 235 }
 236
 237 /*
 238  * NFS congestion control
 239  */
 240
 241 int nfs_congestion_kb;
 242
 243 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 244 #define NFS_CONGESTION_OFF_THRESH       \
 245         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 246
 247 static void nfs_set_page_writeback(struct page *page)
 248 {
 249         struct nfs_server *nfss = NFS_SERVER(page_file_mapping(page)->host);
 250         int ret = test_set_page_writeback(page);
 251
 252         WARN_ON_ONCE(ret != 0);
 253
 254         if (atomic_long_inc_return(&nfss->writeback) >
 255                         NFS_CONGESTION_ON_THRESH) {
 256                 set_bdi_congested(&nfss->backing_dev_info,
 257                                         BLK_RW_ASYNC);
 258         }
 259 }
 260
 261 static void nfs_end_page_writeback(struct page *page)
 262 {
 263         struct inode *inode = page_file_mapping(page)->host;
 264         struct nfs_server *nfss = NFS_SERVER(inode);
 265
 266         end_page_writeback(page);
 267         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 268                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
 269 }
 270
 271 static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
 272 {
 273         struct inode *inode = page_file_mapping(page)->host;
 274         struct nfs_page *req;
 275         int ret;
 276
 277         spin_lock(&inode->i_lock);
 278         for (;;) {
 279                 req = nfs_page_find_request_locked(NFS_I(inode), page);
 280                 if (req == NULL)
 281                         break;
 282                 if (nfs_lock_request(req))
 283                         break;
 284                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 285                  *       then the call to nfs_lock_request() will always
 286                  *       succeed provided that someone hasn't already marked the
 287                  *       request as dirty (in which case we don't care).
 288                  */
 289                 spin_unlock(&inode->i_lock);
 290                 if (!nonblock)
 291                         ret = nfs_wait_on_request(req);
 292                 else
 293                         ret = -EAGAIN;
 294                 nfs_release_request(req);
 295                 if (ret != 0)
 296                         return ERR_PTR(ret);
 297                 spin_lock(&inode->i_lock);
 298         }
 299         spin_unlock(&inode->i_lock);
 300         return req;
 301 }
 302
 303 /*
 304  * Find an associated nfs write request, and prepare to flush it out
 305  * May return an error if the user signalled nfs_wait_on_request().
 306  */
 307 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 308                                 struct page *page, bool nonblock)
 309 {
 310         struct nfs_page *req;
 311         int ret = 0;
 312
 313         req = nfs_find_and_lock_request(page, nonblock);
 314         if (!req)
 315                 goto out;
 316         ret = PTR_ERR(req);
 317         if (IS_ERR(req))
 318                 goto out;
 319
 320         nfs_set_page_writeback(page);
 321         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 322
 323         ret = 0;
 324         if (!nfs_pageio_add_request(pgio, req)) {
 325                 nfs_redirty_request(req);
 326                 ret = pgio->pg_error;
 327         }
 328 out:
 329         return ret;
 330 }
 331
 332 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 333 {
 334         struct inode *inode = page_file_mapping(page)->host;
 335         int ret;
 336
 337         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 338         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 339
 340         nfs_pageio_cond_complete(pgio, page_file_index(page));
 341         ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
 342         if (ret == -EAGAIN) {
 343                 redirty_page_for_writepage(wbc, page);
 344                 ret = 0;
 345         }
 346         return ret;
 347 }
 348
 349 /*
 350  * Write an mmapped page to the server.
 351  */
 352 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 353 {
 354         struct nfs_pageio_descriptor pgio;
 355         int err;
 356
 357         NFS_PROTO(page_file_mapping(page)->host)->write_pageio_init(&pgio,
 358                                                           page->mapping->host,
 359                                                           wb_priority(wbc),
 360                                                           &nfs_async_write_completion_ops);
 361         err = nfs_do_writepage(page, wbc, &pgio);
 362         nfs_pageio_complete(&pgio);
 363         if (err < 0)
 364                 return err;
 365         if (pgio.pg_error < 0)
 366                 return pgio.pg_error;
 367         return 0;
 368 }
 369
 370 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 371 {
 372         int ret;
 373
 374         ret = nfs_writepage_locked(page, wbc);
 375         unlock_page(page);
 376         return ret;
 377 }
 378
 379 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 380 {
 381         int ret;
 382
 383         ret = nfs_do_writepage(page, wbc, data);
 384         unlock_page(page);
 385         return ret;
 386 }
 387
 388 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 389 {
 390         struct inode *inode = mapping->host;
 391         unsigned long *bitlock = &NFS_I(inode)->flags;
 392         struct nfs_pageio_descriptor pgio;
 393         int err;
 394
 395         /* Stop dirtying of new pages while we sync */
 396         err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
 397                         nfs_wait_bit_killable, TASK_KILLABLE);
 398         if (err)
 399                 goto out_err;
 400
 401         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 402
 403         NFS_PROTO(inode)->write_pageio_init(&pgio, inode, wb_priority(wbc), &nfs_async_write_completion_ops);
 404         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 405         nfs_pageio_complete(&pgio);
 406
 407         clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
 408         smp_mb__after_clear_bit();
 409         wake_up_bit(bitlock, NFS_INO_FLUSHING);
 410
 411         if (err < 0)
 412                 goto out_err;
 413         err = pgio.pg_error;
 414         if (err < 0)
 415                 goto out_err;
 416         return 0;
 417 out_err:
 418         return err;
 419 }
 420
 421 /*
 422  * Insert a write request into an inode
 423  */
 424 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 425 {
 426         struct nfs_inode *nfsi = NFS_I(inode);
 427
 428         /* Lock the request! */
 429         nfs_lock_request(req);
 430
 431         spin_lock(&inode->i_lock);
 432         if (!nfsi->npages && NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 433                 inode->i_version++;
 434         /*
 435          * Swap-space should not get truncated. Hence no need to plug the race
 436          * with invalidate/truncate.
 437          */
 438         if (likely(!PageSwapCache(req->wb_page))) {
 439                 set_bit(PG_MAPPED, &req->wb_flags);
 440                 SetPagePrivate(req->wb_page);
 441                 set_page_private(req->wb_page, (unsigned long)req);
 442         }
 443         nfsi->npages++;
 444         kref_get(&req->wb_kref);
 445         spin_unlock(&inode->i_lock);
 446 }
 447
 448 /*
 449  * Remove a write request from an inode
 450  */
 451 static void nfs_inode_remove_request(struct nfs_page *req)
 452 {
 453         struct inode *inode = req->wb_context->dentry->d_inode;
 454         struct nfs_inode *nfsi = NFS_I(inode);
 455
 456         spin_lock(&inode->i_lock);
 457         if (likely(!PageSwapCache(req->wb_page))) {
 458                 set_page_private(req->wb_page, 0);
 459                 ClearPagePrivate(req->wb_page);
 460                 clear_bit(PG_MAPPED, &req->wb_flags);
 461         }
 462         nfsi->npages--;
 463         spin_unlock(&inode->i_lock);
 464         nfs_release_request(req);
 465 }
 466
 467 static void
 468 nfs_mark_request_dirty(struct nfs_page *req)
 469 {
 470         __set_page_dirty_nobuffers(req->wb_page);
 471 }
 472
 473 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
 474 /**
 475  * nfs_request_add_commit_list - add request to a commit list
 476  * @req: pointer to a struct nfs_page
 477  * @dst: commit list head
 478  * @cinfo: holds list lock and accounting info
 479  *
 480  * This sets the PG_CLEAN bit, updates the cinfo count of
 481  * number of outstanding requests requiring a commit as well as
 482  * the MM page stats.
 483  *
 484  * The caller must _not_ hold the cinfo->lock, but must be
 485  * holding the nfs_page lock.
 486  */
 487 void
 488 nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
 489                             struct nfs_commit_info *cinfo)
 490 {
 491         set_bit(PG_CLEAN, &(req)->wb_flags);
 492         spin_lock(cinfo->lock);
 493         nfs_list_add_request(req, dst);
 494         cinfo->mds->ncommit++;
 495         spin_unlock(cinfo->lock);
 496         if (!cinfo->dreq) {
 497                 inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 498                 inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
 499                              BDI_RECLAIMABLE);
 500                 __mark_inode_dirty(req->wb_context->dentry->d_inode,
 501                                    I_DIRTY_DATASYNC);
 502         }
 503 }
 504 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 505
 506 /**
 507  * nfs_request_remove_commit_list - Remove request from a commit list
 508  * @req: pointer to a nfs_page
 509  * @cinfo: holds list lock and accounting info
 510  *
 511  * This clears the PG_CLEAN bit, and updates the cinfo's count of
 512  * number of outstanding requests requiring a commit
 513  * It does not update the MM page stats.
 514  *
 515  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 516  */
 517 void
 518 nfs_request_remove_commit_list(struct nfs_page *req,
 519                                struct nfs_commit_info *cinfo)
 520 {
 521         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 522                 return;
 523         nfs_list_remove_request(req);
 524         cinfo->mds->ncommit--;
 525 }
 526 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 527
 528 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 529                                       struct inode *inode)
 530 {
 531         cinfo->lock = &inode->i_lock;
 532         cinfo->mds = &NFS_I(inode)->commit_info;
 533         cinfo->ds = pnfs_get_ds_info(inode);
 534         cinfo->dreq = NULL;
 535         cinfo->completion_ops = &nfs_commit_completion_ops;
 536 }
 537
 538 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 539                     struct inode *inode,
 540                     struct nfs_direct_req *dreq)
 541 {
 542         if (dreq)
 543                 nfs_init_cinfo_from_dreq(cinfo, dreq);
 544         else
 545                 nfs_init_cinfo_from_inode(cinfo, inode);
 546 }
 547 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 548
 549 /*
 550  * Add a request to the inode's commit list.
 551  */
 552 void
 553 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 554                         struct nfs_commit_info *cinfo)
 555 {
 556         if (pnfs_mark_request_commit(req, lseg, cinfo))
 557                 return;
 558         nfs_request_add_commit_list(req, &cinfo->mds->list, cinfo);
 559 }
 560
 561 static void
 562 nfs_clear_page_commit(struct page *page)
 563 {
 564         dec_zone_page_state(page, NR_UNSTABLE_NFS);
 565         dec_bdi_stat(page_file_mapping(page)->backing_dev_info, BDI_RECLAIMABLE);
 566 }
 567
 568 static void
 569 nfs_clear_request_commit(struct nfs_page *req)
 570 {
 571         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 572                 struct inode *inode = req->wb_context->dentry->d_inode;
 573                 struct nfs_commit_info cinfo;
 574
 575                 nfs_init_cinfo_from_inode(&cinfo, inode);
 576                 if (!pnfs_clear_request_commit(req, &cinfo)) {
 577                         spin_lock(cinfo.lock);
 578                         nfs_request_remove_commit_list(req, &cinfo);
 579                         spin_unlock(cinfo.lock);
 580                 }
 581                 nfs_clear_page_commit(req->wb_page);
 582         }
 583 }
 584
 585 static inline
 586 int nfs_write_need_commit(struct nfs_write_data *data)
 587 {
 588         if (data->verf.committed == NFS_DATA_SYNC)
 589                 return data->header->lseg == NULL;
 590         return data->verf.committed != NFS_FILE_SYNC;
 591 }
 592
 593 #else
 594 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 595                                       struct inode *inode)
 596 {
 597 }
 598
 599 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 600                     struct inode *inode,
 601                     struct nfs_direct_req *dreq)
 602 {
 603 }
 604
 605 void
 606 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 607                         struct nfs_commit_info *cinfo)
 608 {
 609 }
 610
 611 static void
 612 nfs_clear_request_commit(struct nfs_page *req)
 613 {
 614 }
 615
 616 static inline
 617 int nfs_write_need_commit(struct nfs_write_data *data)
 618 {
 619         return 0;
 620 }
 621
 622 #endif
 623
 624 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 625 {
 626         struct nfs_commit_info cinfo;
 627         unsigned long bytes = 0;
 628
 629         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 630                 goto out;
 631         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
 632         while (!list_empty(&hdr->pages)) {
 633                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 634
 635                 bytes += req->wb_bytes;
 636                 nfs_list_remove_request(req);
 637                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
 638                     (hdr->good_bytes < bytes)) {
 639                         nfs_set_pageerror(req->wb_page);
 640                         nfs_context_set_write_error(req->wb_context, hdr->error);
 641                         goto remove_req;
 642                 }
 643                 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
 644                         nfs_mark_request_dirty(req);
 645                         goto next;
 646                 }
 647                 if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
 648                         memcpy(&req->wb_verf, &hdr->verf->verifier, sizeof(req->wb_verf));
 649                         nfs_mark_request_commit(req, hdr->lseg, &cinfo);
 650                         goto next;
 651                 }
 652 remove_req:
 653                 nfs_inode_remove_request(req);
 654 next:
 655                 nfs_unlock_request(req);
 656                 nfs_end_page_writeback(req->wb_page);
 657                 nfs_release_request(req);
 658         }
 659 out:
 660         hdr->release(hdr);
 661 }
 662
 663 #if  IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
 664 static unsigned long
 665 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
 666 {
 667         return cinfo->mds->ncommit;
 668 }
 669
 670 /* cinfo->lock held by caller */
 671 int
 672 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
 673                      struct nfs_commit_info *cinfo, int max)
 674 {
 675         struct nfs_page *req, *tmp;
 676         int ret = 0;
 677
 678         list_for_each_entry_safe(req, tmp, src, wb_list) {
 679                 if (!nfs_lock_request(req))
 680                         continue;
 681                 kref_get(&req->wb_kref);
 682                 if (cond_resched_lock(cinfo->lock))
 683                         list_safe_reset_next(req, tmp, wb_list);
 684                 nfs_request_remove_commit_list(req, cinfo);
 685                 nfs_list_add_request(req, dst);
 686                 ret++;
 687                 if ((ret == max) && !cinfo->dreq)
 688                         break;
 689         }
 690         return ret;
 691 }
 692
 693 /*
 694  * nfs_scan_commit - Scan an inode for commit requests
 695  * @inode: NFS inode to scan
 696  * @dst: mds destination list
 697  * @cinfo: mds and ds lists of reqs ready to commit
 698  *
 699  * Moves requests from the inode's 'commit' request list.
 700  * The requests are *not* checked to ensure that they form a contiguous set.
 701  */
 702 int
 703 nfs_scan_commit(struct inode *inode, struct list_head *dst,
 704                 struct nfs_commit_info *cinfo)
 705 {
 706         int ret = 0;
 707
 708         spin_lock(cinfo->lock);
 709         if (cinfo->mds->ncommit > 0) {
 710                 const int max = INT_MAX;
 711
 712                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
 713                                            cinfo, max);
 714                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
 715         }
 716         spin_unlock(cinfo->lock);
 717         return ret;
 718 }
 719
 720 #else
 721 static unsigned long nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
 722 {
 723         return 0;
 724 }
 725
 726 int nfs_scan_commit(struct inode *inode, struct list_head *dst,
 727                     struct nfs_commit_info *cinfo)
 728 {
 729         return 0;
 730 }
 731 #endif
 732
 733 /*
 734  * Search for an existing write request, and attempt to update
 735  * it to reflect a new dirty region on a given page.
 736  *
 737  * If the attempt fails, then the existing request is flushed out
 738  * to disk.
 739  */
 740 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
 741                 struct page *page,
 742                 unsigned int offset,
 743                 unsigned int bytes)
 744 {
 745         struct nfs_page *req;
 746         unsigned int rqend;
 747         unsigned int end;
 748         int error;
 749
 750         if (!PagePrivate(page))
 751                 return NULL;
 752
 753         end = offset + bytes;
 754         spin_lock(&inode->i_lock);
 755
 756         for (;;) {
 757                 req = nfs_page_find_request_locked(NFS_I(inode), page);
 758                 if (req == NULL)
 759                         goto out_unlock;
 760
 761                 rqend = req->wb_offset + req->wb_bytes;
 762                 /*
 763                  * Tell the caller to flush out the request if
 764                  * the offsets are non-contiguous.
 765                  * Note: nfs_flush_incompatible() will already
 766                  * have flushed out requests having wrong owners.
 767                  */
 768                 if (offset > rqend
 769                     || end < req->wb_offset)
 770                         goto out_flushme;
 771
 772                 if (nfs_lock_request(req))
 773                         break;
 774
 775                 /* The request is locked, so wait and then retry */
 776                 spin_unlock(&inode->i_lock);
 777                 error = nfs_wait_on_request(req);
 778                 nfs_release_request(req);
 779                 if (error != 0)
 780                         goto out_err;
 781                 spin_lock(&inode->i_lock);
 782         }
 783
 784         /* Okay, the request matches. Update the region */
 785         if (offset < req->wb_offset) {
 786                 req->wb_offset = offset;
 787                 req->wb_pgbase = offset;
 788         }
 789         if (end > rqend)
 790                 req->wb_bytes = end - req->wb_offset;
 791         else
 792                 req->wb_bytes = rqend - req->wb_offset;
 793 out_unlock:
 794         spin_unlock(&inode->i_lock);
 795         if (req)
 796                 nfs_clear_request_commit(req);
 797         return req;
 798 out_flushme:
 799         spin_unlock(&inode->i_lock);
 800         nfs_release_request(req);
 801         error = nfs_wb_page(inode, page);
 802 out_err:
 803         return ERR_PTR(error);
 804 }
 805
 806 /*
 807  * Try to update an existing write request, or create one if there is none.
 808  *
 809  * Note: Should always be called with the Page Lock held to prevent races
 810  * if we have to add a new request. Also assumes that the caller has
 811  * already called nfs_flush_incompatible() if necessary.
 812  */
 813 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
 814                 struct page *page, unsigned int offset, unsigned int bytes)
 815 {
 816         struct inode *inode = page_file_mapping(page)->host;
 817         struct nfs_page *req;
 818
 819         req = nfs_try_to_update_request(inode, page, offset, bytes);
 820         if (req != NULL)
 821                 goto out;
 822         req = nfs_create_request(ctx, inode, page, offset, bytes);
 823         if (IS_ERR(req))
 824                 goto out;
 825         nfs_inode_add_request(inode, req);
 826 out:
 827         return req;
 828 }
 829
 830 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 831                 unsigned int offset, unsigned int count)
 832 {
 833         struct nfs_page *req;
 834
 835         req = nfs_setup_write_request(ctx, page, offset, count);
 836         if (IS_ERR(req))
 837                 return PTR_ERR(req);
 838         /* Update file length */
 839         nfs_grow_file(page, offset, count);
 840         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
 841         nfs_mark_request_dirty(req);
 842         nfs_unlock_and_release_request(req);
 843         return 0;
 844 }
 845
 846 int nfs_flush_incompatible(struct file *file, struct page *page)
 847 {
 848         struct nfs_open_context *ctx = nfs_file_open_context(file);
 849         struct nfs_lock_context *l_ctx;
 850         struct nfs_page *req;
 851         int do_flush, status;
 852         /*
 853          * Look for a request corresponding to this page. If there
 854          * is one, and it belongs to another file, we flush it out
 855          * before we try to copy anything into the page. Do this
 856          * due to the lack of an ACCESS-type call in NFSv2.
 857          * Also do the same if we find a request from an existing
 858          * dropped page.
 859          */
 860         do {
 861                 req = nfs_page_find_request(page);
 862                 if (req == NULL)
 863                         return 0;
 864                 l_ctx = req->wb_lock_context;
 865                 do_flush = req->wb_page != page || req->wb_context != ctx;
 866                 if (l_ctx && ctx->dentry->d_inode->i_flock != NULL) {
 867                         do_flush |= l_ctx->lockowner.l_owner != current->files
 868                                 || l_ctx->lockowner.l_pid != current->tgid;
 869                 }
 870                 nfs_release_request(req);
 871                 if (!do_flush)
 872                         return 0;
 873                 status = nfs_wb_page(page_file_mapping(page)->host, page);
 874         } while (status == 0);
 875         return status;
 876 }
 877
 878 /*
 879  * Avoid buffered writes when a open context credential's key would
 880  * expire soon.
 881  *
 882  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
 883  *
 884  * Return 0 and set a credential flag which triggers the inode to flush
 885  * and performs  NFS_FILE_SYNC writes if the key will expired within
 886  * RPC_KEY_EXPIRE_TIMEO.
 887  */
 888 int
 889 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
 890 {
 891         struct nfs_open_context *ctx = nfs_file_open_context(filp);
 892         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
 893
 894         return rpcauth_key_timeout_notify(auth, ctx->cred);
 895 }
 896
 897 /*
 898  * Test if the open context credential key is marked to expire soon.
 899  */
 900 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx)
 901 {
 902         return rpcauth_cred_key_to_expire(ctx->cred);
 903 }
 904
 905 /*
 906  * If the page cache is marked as unsafe or invalid, then we can't rely on
 907  * the PageUptodate() flag. In this case, we will need to turn off
 908  * write optimisations that depend on the page contents being correct.
 909  */
 910 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
 911 {
 912         struct nfs_inode *nfsi = NFS_I(inode);
 913
 914         if (nfs_have_delegated_attributes(inode))
 915                 goto out;
 916         if (nfsi->cache_validity & (NFS_INO_INVALID_DATA|NFS_INO_REVAL_PAGECACHE))
 917                 return false;
 918         smp_rmb();
 919         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
 920                 return false;
 921 out:
 922         return PageUptodate(page) != 0;
 923 }
 924
 925 /* If we know the page is up to date, and we're not using byte range locks (or
 926  * if we have the whole file locked for writing), it may be more efficient to
 927  * extend the write to cover the entire page in order to avoid fragmentation
 928  * inefficiencies.
 929  *
 930  * If the file is opened for synchronous writes then we can just skip the rest
 931  * of the checks.
 932  */
 933 static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
 934 {
 935         if (file->f_flags & O_DSYNC)
 936                 return 0;
 937         if (!nfs_write_pageuptodate(page, inode))
 938                 return 0;
 939         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 940                 return 1;
 941         if (inode->i_flock == NULL || (inode->i_flock->fl_start == 0 &&
 942                         inode->i_flock->fl_end == OFFSET_MAX &&
 943                         inode->i_flock->fl_type != F_RDLCK))
 944                 return 1;
 945         return 0;
 946 }
 947
 948 /*
 949  * Update and possibly write a cached page of an NFS file.
 950  *
 951  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 952  * things with a page scheduled for an RPC call (e.g. invalidate it).
 953  */
 954 int nfs_updatepage(struct file *file, struct page *page,
 955                 unsigned int offset, unsigned int count)
 956 {
 957         struct nfs_open_context *ctx = nfs_file_open_context(file);
 958         struct inode    *inode = page_file_mapping(page)->host;
 959         int             status = 0;
 960
 961         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 962
 963         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
 964                 file, count, (long long)(page_file_offset(page) + offset));
 965
 966         if (nfs_can_extend_write(file, page, inode)) {
 967                 count = max(count + offset, nfs_page_length(page));
 968                 offset = 0;
 969         }
 970
 971         status = nfs_writepage_setup(ctx, page, offset, count);
 972         if (status < 0)
 973                 nfs_set_pageerror(page);
 974         else
 975                 __set_page_dirty_nobuffers(page);
 976
 977         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 978                         status, (long long)i_size_read(inode));
 979         return status;
 980 }
 981
 982 static int flush_task_priority(int how)
 983 {
 984         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 985                 case FLUSH_HIGHPRI:
 986                         return RPC_PRIORITY_HIGH;
 987                 case FLUSH_LOWPRI:
 988                         return RPC_PRIORITY_LOW;
 989         }
 990         return RPC_PRIORITY_NORMAL;
 991 }
 992
 993 int nfs_initiate_write(struct rpc_clnt *clnt,
 994                        struct nfs_write_data *data,
 995                        const struct rpc_call_ops *call_ops,
 996                        int how, int flags)
 997 {
 998         struct inode *inode = data->header->inode;
 999         int priority = flush_task_priority(how);
1000         struct rpc_task *task;
1001         struct rpc_message msg = {
1002                 .rpc_argp = &data->args,
1003                 .rpc_resp = &data->res,
1004                 .rpc_cred = data->header->cred,
1005         };
1006         struct rpc_task_setup task_setup_data = {
1007                 .rpc_client = clnt,
1008                 .task = &data->task,
1009                 .rpc_message = &msg,
1010                 .callback_ops = call_ops,
1011                 .callback_data = data,
1012                 .workqueue = nfsiod_workqueue,
1013                 .flags = RPC_TASK_ASYNC | flags,
1014                 .priority = priority,
1015         };
1016         int ret = 0;
1017
1018         /* Set up the initial task struct.  */
1019         NFS_PROTO(inode)->write_setup(data, &msg);
1020
1021         dprintk("NFS: %5u initiated write call "
1022                 "(req %s/%llu, %u bytes @ offset %llu)\n",
1023                 data->task.tk_pid,
1024                 inode->i_sb->s_id,
1025                 (unsigned long long)NFS_FILEID(inode),
1026                 data->args.count,
1027                 (unsigned long long)data->args.offset);
1028
1029         nfs4_state_protect_write(NFS_SERVER(inode)->nfs_client,
1030                                  &task_setup_data.rpc_client, &msg, data);
1031
1032         task = rpc_run_task(&task_setup_data);
1033         if (IS_ERR(task)) {
1034                 ret = PTR_ERR(task);
1035                 goto out;
1036         }
1037         if (how & FLUSH_SYNC) {
1038                 ret = rpc_wait_for_completion_task(task);
1039                 if (ret == 0)
1040                         ret = task->tk_status;
1041         }
1042         rpc_put_task(task);
1043 out:
1044         return ret;
1045 }
1046 EXPORT_SYMBOL_GPL(nfs_initiate_write);
1047
1048 /*
1049  * Set up the argument/result storage required for the RPC call.
1050  */
1051 static void nfs_write_rpcsetup(struct nfs_write_data *data,
1052                 unsigned int count, unsigned int offset,
1053                 int how, struct nfs_commit_info *cinfo)
1054 {
1055         struct nfs_page *req = data->header->req;
1056
1057         /* Set up the RPC argument and reply structs
1058          * NB: take care not to mess about with data->commit et al. */
1059
1060         data->args.fh     = NFS_FH(data->header->inode);
1061         data->args.offset = req_offset(req) + offset;
1062         /* pnfs_set_layoutcommit needs this */
1063         data->mds_offset = data->args.offset;
1064         data->args.pgbase = req->wb_pgbase + offset;
1065         data->args.pages  = data->pages.pagevec;
1066         data->args.count  = count;
1067         data->args.context = get_nfs_open_context(req->wb_context);
1068         data->args.lock_context = req->wb_lock_context;
1069         data->args.stable  = NFS_UNSTABLE;
1070         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
1071         case 0:
1072                 break;
1073         case FLUSH_COND_STABLE:
1074                 if (nfs_reqs_to_commit(cinfo))
1075                         break;
1076         default:
1077                 data->args.stable = NFS_FILE_SYNC;
1078         }
1079
1080         data->res.fattr   = &data->fattr;
1081         data->res.count   = count;
1082         data->res.verf    = &data->verf;
1083         nfs_fattr_init(&data->fattr);
1084 }
1085
1086 static int nfs_do_write(struct nfs_write_data *data,
1087                 const struct rpc_call_ops *call_ops,
1088                 int how)
1089 {
1090         struct inode *inode = data->header->inode;
1091
1092         return nfs_initiate_write(NFS_CLIENT(inode), data, call_ops, how, 0);
1093 }
1094
1095 static int nfs_do_multiple_writes(struct list_head *head,
1096                 const struct rpc_call_ops *call_ops,
1097                 int how)
1098 {
1099         struct nfs_write_data *data;
1100         int ret = 0;
1101
1102         while (!list_empty(head)) {
1103                 int ret2;
1104
1105                 data = list_first_entry(head, struct nfs_write_data, list);
1106                 list_del_init(&data->list);
1107
1108                 ret2 = nfs_do_write(data, call_ops, how);
1109                  if (ret == 0)
1110                          ret = ret2;
1111         }
1112         return ret;
1113 }
1114
1115 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1116  * call this on each, which will prepare them to be retried on next
1117  * writeback using standard nfs.
1118  */
1119 static void nfs_redirty_request(struct nfs_page *req)
1120 {
1121         nfs_mark_request_dirty(req);
1122         nfs_unlock_request(req);
1123         nfs_end_page_writeback(req->wb_page);
1124         nfs_release_request(req);
1125 }
1126
1127 static void nfs_async_write_error(struct list_head *head)
1128 {
1129         struct nfs_page *req;
1130
1131         while (!list_empty(head)) {
1132                 req = nfs_list_entry(head->next);
1133                 nfs_list_remove_request(req);
1134                 nfs_redirty_request(req);
1135         }
1136 }
1137
1138 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1139         .error_cleanup = nfs_async_write_error,
1140         .completion = nfs_write_completion,
1141 };
1142
1143 static void nfs_flush_error(struct nfs_pageio_descriptor *desc,
1144                 struct nfs_pgio_header *hdr)
1145 {
1146         set_bit(NFS_IOHDR_REDO, &hdr->flags);
1147         while (!list_empty(&hdr->rpc_list)) {
1148                 struct nfs_write_data *data = list_first_entry(&hdr->rpc_list,
1149                                 struct nfs_write_data, list);
1150                 list_del(&data->list);
1151                 nfs_writedata_release(data);
1152         }
1153         desc->pg_completion_ops->error_cleanup(&desc->pg_list);
1154 }
1155
1156 /*
1157  * Generate multiple small requests to write out a single
1158  * contiguous dirty area on one page.
1159  */
1160 static int nfs_flush_multi(struct nfs_pageio_descriptor *desc,
1161                            struct nfs_pgio_header *hdr)
1162 {
1163         struct nfs_page *req = hdr->req;
1164         struct page *page = req->wb_page;
1165         struct nfs_write_data *data;
1166         size_t wsize = desc->pg_bsize, nbytes;
1167         unsigned int offset;
1168         int requests = 0;
1169         struct nfs_commit_info cinfo;
1170
1171         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
1172
1173         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1174             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo) ||
1175              desc->pg_count > wsize))
1176                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1177
1178
1179         offset = 0;
1180         nbytes = desc->pg_count;
1181         do {
1182                 size_t len = min(nbytes, wsize);
1183
1184                 data = nfs_writedata_alloc(hdr, 1);
1185                 if (!data) {
1186                         nfs_flush_error(desc, hdr);
1187                         return -ENOMEM;
1188                 }
1189                 data->pages.pagevec[0] = page;
1190                 nfs_write_rpcsetup(data, len, offset, desc->pg_ioflags, &cinfo);
1191                 list_add(&data->list, &hdr->rpc_list);
1192                 requests++;
1193                 nbytes -= len;
1194                 offset += len;
1195         } while (nbytes != 0);
1196         nfs_list_remove_request(req);
1197         nfs_list_add_request(req, &hdr->pages);
1198         desc->pg_rpc_callops = &nfs_write_common_ops;
1199         return 0;
1200 }
1201
1202 /*
1203  * Create an RPC task for the given write request and kick it.
1204  * The page must have been locked by the caller.
1205  *
1206  * It may happen that the page we're passed is not marked dirty.
1207  * This is the case if nfs_updatepage detects a conflicting request
1208  * that has been written but not committed.
1209  */
1210 static int nfs_flush_one(struct nfs_pageio_descriptor *desc,
1211                          struct nfs_pgio_header *hdr)
1212 {
1213         struct nfs_page         *req;
1214         struct page             **pages;
1215         struct nfs_write_data   *data;
1216         struct list_head *head = &desc->pg_list;
1217         struct nfs_commit_info cinfo;
1218
1219         data = nfs_writedata_alloc(hdr, nfs_page_array_len(desc->pg_base,
1220                                                            desc->pg_count));
1221         if (!data) {
1222                 nfs_flush_error(desc, hdr);
1223                 return -ENOMEM;
1224         }
1225
1226         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
1227         pages = data->pages.pagevec;
1228         while (!list_empty(head)) {
1229                 req = nfs_list_entry(head->next);
1230                 nfs_list_remove_request(req);
1231                 nfs_list_add_request(req, &hdr->pages);
1232                 *pages++ = req->wb_page;
1233         }
1234
1235         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1236             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
1237                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1238
1239         /* Set up the argument struct */
1240         nfs_write_rpcsetup(data, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
1241         list_add(&data->list, &hdr->rpc_list);
1242         desc->pg_rpc_callops = &nfs_write_common_ops;
1243         return 0;
1244 }
1245
1246 int nfs_generic_flush(struct nfs_pageio_descriptor *desc,
1247                       struct nfs_pgio_header *hdr)
1248 {
1249         if (desc->pg_bsize < PAGE_CACHE_SIZE)
1250                 return nfs_flush_multi(desc, hdr);
1251         return nfs_flush_one(desc, hdr);
1252 }
1253 EXPORT_SYMBOL_GPL(nfs_generic_flush);
1254
1255 static int nfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
1256 {
1257         struct nfs_write_header *whdr;
1258         struct nfs_pgio_header *hdr;
1259         int ret;
1260
1261         whdr = nfs_writehdr_alloc();
1262         if (!whdr) {
1263                 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
1264                 return -ENOMEM;
1265         }
1266         hdr = &whdr->header;
1267         nfs_pgheader_init(desc, hdr, nfs_writehdr_free);
1268         atomic_inc(&hdr->refcnt);
1269         ret = nfs_generic_flush(desc, hdr);
1270         if (ret == 0)
1271                 ret = nfs_do_multiple_writes(&hdr->rpc_list,
1272                                              desc->pg_rpc_callops,
1273                                              desc->pg_ioflags);
1274         if (atomic_dec_and_test(&hdr->refcnt))
1275                 hdr->completion_ops->completion(hdr);
1276         return ret;
1277 }
1278
1279 static const struct nfs_pageio_ops nfs_pageio_write_ops = {
1280         .pg_test = nfs_generic_pg_test,
1281         .pg_doio = nfs_generic_pg_writepages,
1282 };
1283
1284 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1285                                struct inode *inode, int ioflags,
1286                                const struct nfs_pgio_completion_ops *compl_ops)
1287 {
1288         nfs_pageio_init(pgio, inode, &nfs_pageio_write_ops, compl_ops,
1289                                 NFS_SERVER(inode)->wsize, ioflags);
1290 }
1291 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1292
1293 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1294 {
1295         pgio->pg_ops = &nfs_pageio_write_ops;
1296         pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1297 }
1298 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1299
1300
1301 void nfs_write_prepare(struct rpc_task *task, void *calldata)
1302 {
1303         struct nfs_write_data *data = calldata;
1304         int err;
1305         err = NFS_PROTO(data->header->inode)->write_rpc_prepare(task, data);
1306         if (err)
1307                 rpc_exit(task, err);
1308 }
1309
1310 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1311 {
1312         struct nfs_commit_data *data = calldata;
1313
1314         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1315 }
1316
1317 /*
1318  * Handle a write reply that flushes a whole page.
1319  *
1320  * FIXME: There is an inherent race with invalidate_inode_pages and
1321  *        writebacks since the page->count is kept > 1 for as long
1322  *        as the page has a write request pending.
1323  */
1324 static void nfs_writeback_done_common(struct rpc_task *task, void *calldata)
1325 {
1326         struct nfs_write_data   *data = calldata;
1327
1328         nfs_writeback_done(task, data);
1329 }
1330
1331 static void nfs_writeback_release_common(void *calldata)
1332 {
1333         struct nfs_write_data   *data = calldata;
1334         struct nfs_pgio_header *hdr = data->header;
1335         int status = data->task.tk_status;
1336
1337         if ((status >= 0) && nfs_write_need_commit(data)) {
1338                 spin_lock(&hdr->lock);
1339                 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags))
1340                         ; /* Do nothing */
1341                 else if (!test_and_set_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags))
1342                         memcpy(hdr->verf, &data->verf, sizeof(*hdr->verf));
1343                 else if (memcmp(hdr->verf, &data->verf, sizeof(*hdr->verf)))
1344                         set_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags);
1345                 spin_unlock(&hdr->lock);
1346         }
1347         nfs_writedata_release(data);
1348 }
1349
1350 static const struct rpc_call_ops nfs_write_common_ops = {
1351         .rpc_call_prepare = nfs_write_prepare,
1352         .rpc_call_done = nfs_writeback_done_common,
1353         .rpc_release = nfs_writeback_release_common,
1354 };
1355
1356 /*
1357  * Special version of should_remove_suid() that ignores capabilities.
1358  */
1359 static int nfs_should_remove_suid(const struct inode *inode)
1360 {
1361         umode_t mode = inode->i_mode;
1362         int kill = 0;
1363
1364         /* suid always must be killed */
1365         if (unlikely(mode & S_ISUID))
1366                 kill = ATTR_KILL_SUID;
1367
1368         /*
1369          * sgid without any exec bits is just a mandatory locking mark; leave
1370          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1371          */
1372         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1373                 kill |= ATTR_KILL_SGID;
1374
1375         if (unlikely(kill && S_ISREG(mode)))
1376                 return kill;
1377
1378         return 0;
1379 }
1380
1381 /*
1382  * This function is called when the WRITE call is complete.
1383  */
1384 void nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1385 {
1386         struct nfs_writeargs    *argp = &data->args;
1387         struct nfs_writeres     *resp = &data->res;
1388         struct inode            *inode = data->header->inode;
1389         int status;
1390
1391         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1392                 task->tk_pid, task->tk_status);
1393
1394         /*
1395          * ->write_done will attempt to use post-op attributes to detect
1396          * conflicting writes by other clients.  A strict interpretation
1397          * of close-to-open would allow us to continue caching even if
1398          * another writer had changed the file, but some applications
1399          * depend on tighter cache coherency when writing.
1400          */
1401         status = NFS_PROTO(inode)->write_done(task, data);
1402         if (status != 0)
1403                 return;
1404         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1405
1406 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
1407         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1408                 /* We tried a write call, but the server did not
1409                  * commit data to stable storage even though we
1410                  * requested it.
1411                  * Note: There is a known bug in Tru64 < 5.0 in which
1412                  *       the server reports NFS_DATA_SYNC, but performs
1413                  *       NFS_FILE_SYNC. We therefore implement this checking
1414                  *       as a dprintk() in order to avoid filling syslog.
1415                  */
1416                 static unsigned long    complain;
1417
1418                 /* Note this will print the MDS for a DS write */
1419                 if (time_before(complain, jiffies)) {
1420                         dprintk("NFS:       faulty NFS server %s:"
1421                                 " (committed = %d) != (stable = %d)\n",
1422                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1423                                 resp->verf->committed, argp->stable);
1424                         complain = jiffies + 300 * HZ;
1425                 }
1426         }
1427 #endif
1428         if (task->tk_status < 0) {
1429                 nfs_set_pgio_error(data->header, task->tk_status, argp->offset);
1430                 return;
1431         }
1432
1433         /* Deal with the suid/sgid bit corner case */
1434         if (nfs_should_remove_suid(inode))
1435                 nfs_mark_for_revalidate(inode);
1436
1437         if (resp->count < argp->count) {
1438                 static unsigned long    complain;
1439
1440                 /* This a short write! */
1441                 nfs_inc_stats(inode, NFSIOS_SHORTWRITE);
1442
1443                 /* Has the server at least made some progress? */
1444                 if (resp->count == 0) {
1445                         if (time_before(complain, jiffies)) {
1446                                 printk(KERN_WARNING
1447                                        "NFS: Server wrote zero bytes, expected %u.\n",
1448                                        argp->count);
1449                                 complain = jiffies + 300 * HZ;
1450                         }
1451                         nfs_set_pgio_error(data->header, -EIO, argp->offset);
1452                         task->tk_status = -EIO;
1453                         return;
1454                 }
1455                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1456                 if (resp->verf->committed != NFS_UNSTABLE) {
1457                         /* Resend from where the server left off */
1458                         data->mds_offset += resp->count;
1459                         argp->offset += resp->count;
1460                         argp->pgbase += resp->count;
1461                         argp->count -= resp->count;
1462                 } else {
1463                         /* Resend as a stable write in order to avoid
1464                          * headaches in the case of a server crash.
1465                          */
1466                         argp->stable = NFS_FILE_SYNC;
1467                 }
1468                 rpc_restart_call_prepare(task);
1469         }
1470 }
1471
1472
1473 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
1474 static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
1475 {
1476         int ret;
1477
1478         if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
1479                 return 1;
1480         if (!may_wait)
1481                 return 0;
1482         ret = out_of_line_wait_on_bit_lock(&nfsi->flags,
1483                                 NFS_INO_COMMIT,
1484                                 nfs_wait_bit_killable,
1485                                 TASK_KILLABLE);
1486         return (ret < 0) ? ret : 1;
1487 }
1488
1489 static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
1490 {
1491         clear_bit(NFS_INO_COMMIT, &nfsi->flags);
1492         smp_mb__after_clear_bit();
1493         wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
1494 }
1495
1496 void nfs_commitdata_release(struct nfs_commit_data *data)
1497 {
1498         put_nfs_open_context(data->context);
1499         nfs_commit_free(data);
1500 }
1501 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1502
1503 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1504                         const struct rpc_call_ops *call_ops,
1505                         int how, int flags)
1506 {
1507         struct rpc_task *task;
1508         int priority = flush_task_priority(how);
1509         struct rpc_message msg = {
1510                 .rpc_argp = &data->args,
1511                 .rpc_resp = &data->res,
1512                 .rpc_cred = data->cred,
1513         };
1514         struct rpc_task_setup task_setup_data = {
1515                 .task = &data->task,
1516                 .rpc_client = clnt,
1517                 .rpc_message = &msg,
1518                 .callback_ops = call_ops,
1519                 .callback_data = data,
1520                 .workqueue = nfsiod_workqueue,
1521                 .flags = RPC_TASK_ASYNC | flags,
1522                 .priority = priority,
1523         };
1524         /* Set up the initial task struct.  */
1525         NFS_PROTO(data->inode)->commit_setup(data, &msg);
1526
1527         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1528
1529         nfs4_state_protect(NFS_SERVER(data->inode)->nfs_client,
1530                 NFS_SP4_MACH_CRED_COMMIT, &task_setup_data.rpc_client, &msg);
1531
1532         task = rpc_run_task(&task_setup_data);
1533         if (IS_ERR(task))
1534                 return PTR_ERR(task);
1535         if (how & FLUSH_SYNC)
1536                 rpc_wait_for_completion_task(task);
1537         rpc_put_task(task);
1538         return 0;
1539 }
1540 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1541
1542 /*
1543  * Set up the argument/result storage required for the RPC call.
1544  */
1545 void nfs_init_commit(struct nfs_commit_data *data,
1546                      struct list_head *head,
1547                      struct pnfs_layout_segment *lseg,
1548                      struct nfs_commit_info *cinfo)
1549 {
1550         struct nfs_page *first = nfs_list_entry(head->next);
1551         struct inode *inode = first->wb_context->dentry->d_inode;
1552
1553         /* Set up the RPC argument and reply structs
1554          * NB: take care not to mess about with data->commit et al. */
1555
1556         list_splice_init(head, &data->pages);
1557
1558         data->inode       = inode;
1559         data->cred        = first->wb_context->cred;
1560         data->lseg        = lseg; /* reference transferred */
1561         data->mds_ops     = &nfs_commit_ops;
1562         data->completion_ops = cinfo->completion_ops;
1563         data->dreq        = cinfo->dreq;
1564
1565         data->args.fh     = NFS_FH(data->inode);
1566         /* Note: we always request a commit of the entire inode */
1567         data->args.offset = 0;
1568         data->args.count  = 0;
1569         data->context     = get_nfs_open_context(first->wb_context);
1570         data->res.fattr   = &data->fattr;
1571         data->res.verf    = &data->verf;
1572         nfs_fattr_init(&data->fattr);
1573 }
1574 EXPORT_SYMBOL_GPL(nfs_init_commit);
1575
1576 void nfs_retry_commit(struct list_head *page_list,
1577                       struct pnfs_layout_segment *lseg,
1578                       struct nfs_commit_info *cinfo)
1579 {
1580         struct nfs_page *req;
1581
1582         while (!list_empty(page_list)) {
1583                 req = nfs_list_entry(page_list->next);
1584                 nfs_list_remove_request(req);
1585                 nfs_mark_request_commit(req, lseg, cinfo);
1586                 if (!cinfo->dreq) {
1587                         dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1588                         dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
1589                                      BDI_RECLAIMABLE);
1590                 }
1591                 nfs_unlock_and_release_request(req);
1592         }
1593 }
1594 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1595
1596 /*
1597  * Commit dirty pages
1598  */
1599 static int
1600 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1601                 struct nfs_commit_info *cinfo)
1602 {
1603         struct nfs_commit_data  *data;
1604
1605         data = nfs_commitdata_alloc();
1606
1607         if (!data)
1608                 goto out_bad;
1609
1610         /* Set up the argument struct */
1611         nfs_init_commit(data, head, NULL, cinfo);
1612         atomic_inc(&cinfo->mds->rpcs_out);
1613         return nfs_initiate_commit(NFS_CLIENT(inode), data, data->mds_ops,
1614                                    how, 0);
1615  out_bad:
1616         nfs_retry_commit(head, NULL, cinfo);
1617         cinfo->completion_ops->error_cleanup(NFS_I(inode));
1618         return -ENOMEM;
1619 }
1620
1621 /*
1622  * COMMIT call returned
1623  */
1624 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1625 {
1626         struct nfs_commit_data  *data = calldata;
1627
1628         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1629                                 task->tk_pid, task->tk_status);
1630
1631         /* Call the NFS version-specific code */
1632         NFS_PROTO(data->inode)->commit_done(task, data);
1633 }
1634
1635 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1636 {
1637         struct nfs_page *req;
1638         int status = data->task.tk_status;
1639         struct nfs_commit_info cinfo;
1640
1641         while (!list_empty(&data->pages)) {
1642                 req = nfs_list_entry(data->pages.next);
1643                 nfs_list_remove_request(req);
1644                 nfs_clear_page_commit(req->wb_page);
1645
1646                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1647                         req->wb_context->dentry->d_sb->s_id,
1648                         (unsigned long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1649                         req->wb_bytes,
1650                         (long long)req_offset(req));
1651                 if (status < 0) {
1652                         nfs_context_set_write_error(req->wb_context, status);
1653                         nfs_inode_remove_request(req);
1654                         dprintk(", error = %d\n", status);
1655                         goto next;
1656                 }
1657
1658                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1659                  * returned by the server against all stored verfs. */
1660                 if (!memcmp(&req->wb_verf, &data->verf.verifier, sizeof(req->wb_verf))) {
1661                         /* We have a match */
1662                         nfs_inode_remove_request(req);
1663                         dprintk(" OK\n");
1664                         goto next;
1665                 }
1666                 /* We have a mismatch. Write the page again */
1667                 dprintk(" mismatch\n");
1668                 nfs_mark_request_dirty(req);
1669                 set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1670         next:
1671                 nfs_unlock_and_release_request(req);
1672         }
1673         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1674         if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
1675                 nfs_commit_clear_lock(NFS_I(data->inode));
1676 }
1677
1678 static void nfs_commit_release(void *calldata)
1679 {
1680         struct nfs_commit_data *data = calldata;
1681
1682         data->completion_ops->completion(data);
1683         nfs_commitdata_release(calldata);
1684 }
1685
1686 static const struct rpc_call_ops nfs_commit_ops = {
1687         .rpc_call_prepare = nfs_commit_prepare,
1688         .rpc_call_done = nfs_commit_done,
1689         .rpc_release = nfs_commit_release,
1690 };
1691
1692 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1693         .completion = nfs_commit_release_pages,
1694         .error_cleanup = nfs_commit_clear_lock,
1695 };
1696
1697 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1698                             int how, struct nfs_commit_info *cinfo)
1699 {
1700         int status;
1701
1702         status = pnfs_commit_list(inode, head, how, cinfo);
1703         if (status == PNFS_NOT_ATTEMPTED)
1704                 status = nfs_commit_list(inode, head, how, cinfo);
1705         return status;
1706 }
1707
1708 int nfs_commit_inode(struct inode *inode, int how)
1709 {
1710         LIST_HEAD(head);
1711         struct nfs_commit_info cinfo;
1712         int may_wait = how & FLUSH_SYNC;
1713         int res;
1714
1715         res = nfs_commit_set_lock(NFS_I(inode), may_wait);
1716         if (res <= 0)
1717                 goto out_mark_dirty;
1718         nfs_init_cinfo_from_inode(&cinfo, inode);
1719         res = nfs_scan_commit(inode, &head, &cinfo);
1720         if (res) {
1721                 int error;
1722
1723                 error = nfs_generic_commit_list(inode, &head, how, &cinfo);
1724                 if (error < 0)
1725                         return error;
1726                 if (!may_wait)
1727                         goto out_mark_dirty;
1728                 error = wait_on_bit(&NFS_I(inode)->flags,
1729                                 NFS_INO_COMMIT,
1730                                 nfs_wait_bit_killable,
1731                                 TASK_KILLABLE);
1732                 if (error < 0)
1733                         return error;
1734         } else
1735                 nfs_commit_clear_lock(NFS_I(inode));
1736         return res;
1737         /* Note: If we exit without ensuring that the commit is complete,
1738          * we must mark the inode as dirty. Otherwise, future calls to
1739          * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
1740          * that the data is on the disk.
1741          */
1742 out_mark_dirty:
1743         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1744         return res;
1745 }
1746
1747 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1748 {
1749         struct nfs_inode *nfsi = NFS_I(inode);
1750         int flags = FLUSH_SYNC;
1751         int ret = 0;
1752
1753         /* no commits means nothing needs to be done */
1754         if (!nfsi->commit_info.ncommit)
1755                 return ret;
1756
1757         if (wbc->sync_mode == WB_SYNC_NONE) {
1758                 /* Don't commit yet if this is a non-blocking flush and there
1759                  * are a lot of outstanding writes for this mapping.
1760                  */
1761                 if (nfsi->commit_info.ncommit <= (nfsi->npages >> 1))
1762                         goto out_mark_dirty;
1763
1764                 /* don't wait for the COMMIT response */
1765                 flags = 0;
1766         }
1767
1768         ret = nfs_commit_inode(inode, flags);
1769         if (ret >= 0) {
1770                 if (wbc->sync_mode == WB_SYNC_NONE) {
1771                         if (ret < wbc->nr_to_write)
1772                                 wbc->nr_to_write -= ret;
1773                         else
1774                                 wbc->nr_to_write = 0;
1775                 }
1776                 return 0;
1777         }
1778 out_mark_dirty:
1779         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1780         return ret;
1781 }
1782 #else
1783 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1784 {
1785         return 0;
1786 }
1787 #endif
1788
1789 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1790 {
1791         return nfs_commit_unstable_pages(inode, wbc);
1792 }
1793 EXPORT_SYMBOL_GPL(nfs_write_inode);
1794
1795 /*
1796  * flush the inode to disk.
1797  */
1798 int nfs_wb_all(struct inode *inode)
1799 {
1800         struct writeback_control wbc = {
1801                 .sync_mode = WB_SYNC_ALL,
1802                 .nr_to_write = LONG_MAX,
1803                 .range_start = 0,
1804                 .range_end = LLONG_MAX,
1805         };
1806         int ret;
1807
1808         trace_nfs_writeback_inode_enter(inode);
1809
1810         ret = sync_inode(inode, &wbc);
1811
1812         trace_nfs_writeback_inode_exit(inode, ret);
1813         return ret;
1814 }
1815 EXPORT_SYMBOL_GPL(nfs_wb_all);
1816
1817 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1818 {
1819         struct nfs_page *req;
1820         int ret = 0;
1821
1822         for (;;) {
1823                 wait_on_page_writeback(page);
1824                 req = nfs_page_find_request(page);
1825                 if (req == NULL)
1826                         break;
1827                 if (nfs_lock_request(req)) {
1828                         nfs_clear_request_commit(req);
1829                         nfs_inode_remove_request(req);
1830                         /*
1831                          * In case nfs_inode_remove_request has marked the
1832                          * page as being dirty
1833                          */
1834                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1835                         nfs_unlock_and_release_request(req);
1836                         break;
1837                 }
1838                 ret = nfs_wait_on_request(req);
1839                 nfs_release_request(req);
1840                 if (ret < 0)
1841                         break;
1842         }
1843         return ret;
1844 }
1845
1846 /*
1847  * Write back all requests on one page - we do this before reading it.
1848  */
1849 int nfs_wb_page(struct inode *inode, struct page *page)
1850 {
1851         loff_t range_start = page_file_offset(page);
1852         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1853         struct writeback_control wbc = {
1854                 .sync_mode = WB_SYNC_ALL,
1855                 .nr_to_write = 0,
1856                 .range_start = range_start,
1857                 .range_end = range_end,
1858         };
1859         int ret;
1860
1861         trace_nfs_writeback_page_enter(inode);
1862
1863         for (;;) {
1864                 wait_on_page_writeback(page);
1865                 if (clear_page_dirty_for_io(page)) {
1866                         ret = nfs_writepage_locked(page, &wbc);
1867                         if (ret < 0)
1868                                 goto out_error;
1869                         continue;
1870                 }
1871                 ret = 0;
1872                 if (!PagePrivate(page))
1873                         break;
1874                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
1875                 if (ret < 0)
1876                         goto out_error;
1877         }
1878 out_error:
1879         trace_nfs_writeback_page_exit(inode, ret);
1880         return ret;
1881 }
1882
1883 #ifdef CONFIG_MIGRATION
1884 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
1885                 struct page *page, enum migrate_mode mode)
1886 {
1887         /*
1888          * If PagePrivate is set, then the page is currently associated with
1889          * an in-progress read or write request. Don't try to migrate it.
1890          *
1891          * FIXME: we could do this in principle, but we'll need a way to ensure
1892          *        that we can safely release the inode reference while holding
1893          *        the page lock.
1894          */
1895         if (PagePrivate(page))
1896                 return -EBUSY;
1897
1898         if (!nfs_fscache_release_page(page, GFP_KERNEL))
1899                 return -EBUSY;
1900
1901         return migrate_page(mapping, newpage, page, mode);
1902 }
1903 #endif
1904
1905 int __init nfs_init_writepagecache(void)
1906 {
1907         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1908                                              sizeof(struct nfs_write_header),
1909                                              0, SLAB_HWCACHE_ALIGN,
1910                                              NULL);
1911         if (nfs_wdata_cachep == NULL)
1912                 return -ENOMEM;
1913
1914         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1915                                                      nfs_wdata_cachep);
1916         if (nfs_wdata_mempool == NULL)
1917                 goto out_destroy_write_cache;
1918
1919         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
1920                                              sizeof(struct nfs_commit_data),
1921                                              0, SLAB_HWCACHE_ALIGN,
1922                                              NULL);
1923         if (nfs_cdata_cachep == NULL)
1924                 goto out_destroy_write_mempool;
1925
1926         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1927                                                       nfs_cdata_cachep);
1928         if (nfs_commit_mempool == NULL)
1929                 goto out_destroy_commit_cache;
1930
1931         /*
1932          * NFS congestion size, scale with available memory.
1933          *
1934          *  64MB:    8192k
1935          * 128MB:   11585k
1936          * 256MB:   16384k
1937          * 512MB:   23170k
1938          *   1GB:   32768k
1939          *   2GB:   46340k
1940          *   4GB:   65536k
1941          *   8GB:   92681k
1942          *  16GB:  131072k
1943          *
1944          * This allows larger machines to have larger/more transfers.
1945          * Limit the default to 256M
1946          */
1947         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1948         if (nfs_congestion_kb > 256*1024)
1949                 nfs_congestion_kb = 256*1024;
1950
1951         return 0;
1952
1953 out_destroy_commit_cache:
1954         kmem_cache_destroy(nfs_cdata_cachep);
1955 out_destroy_write_mempool:
1956         mempool_destroy(nfs_wdata_mempool);
1957 out_destroy_write_cache:
1958         kmem_cache_destroy(nfs_wdata_cachep);
1959         return -ENOMEM;
1960 }
1961
1962 void nfs_destroy_writepagecache(void)
1963 {
1964         mempool_destroy(nfs_commit_mempool);
1965         kmem_cache_destroy(nfs_cdata_cachep);
1966         mempool_destroy(nfs_wdata_mempool);
1967         kmem_cache_destroy(nfs_wdata_cachep);
1968 }
1969