fs/nfs/write.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/write.c
   4  *
   5  * Write file data over NFS.
   6  *
   7  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/slab.h>
  12 #include <linux/mm.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/file.h>
  15 #include <linux/writeback.h>
  16 #include <linux/swap.h>
  17 #include <linux/migrate.h>
  18
  19 #include <linux/sunrpc/clnt.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_mount.h>
  22 #include <linux/nfs_page.h>
  23 #include <linux/backing-dev.h>
  24 #include <linux/export.h>
  25 #include <linux/freezer.h>
  26 #include <linux/wait.h>
  27 #include <linux/iversion.h>
  28 #include <linux/filelock.h>
  29
  30 #include <linux/uaccess.h>
  31 #include <linux/sched/mm.h>
  32
  33 #include "delegation.h"
  34 #include "internal.h"
  35 #include "iostat.h"
  36 #include "nfs4_fs.h"
  37 #include "fscache.h"
  38 #include "pnfs.h"
  39
  40 #include "nfstrace.h"
  41
  42 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  43
  44 #define MIN_POOL_WRITE          (32)
  45 #define MIN_POOL_COMMIT         (4)
  46
  47 struct nfs_io_completion {
  48         void (*complete)(void *data);
  49         void *data;
  50         struct kref refcount;
  51 };
  52
  53 /*
  54  * Local function declarations
  55  */
  56 static void nfs_redirty_request(struct nfs_page *req);
  57 static const struct rpc_call_ops nfs_commit_ops;
  58 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  59 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  60 static const struct nfs_rw_ops nfs_rw_write_ops;
  61 static void nfs_inode_remove_request(struct nfs_page *req);
  62 static void nfs_clear_request_commit(struct nfs_page *req);
  63 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
  64                                       struct inode *inode);
  65 static struct nfs_page *
  66 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
  67                                                 struct page *page);
  68
  69 static struct kmem_cache *nfs_wdata_cachep;
  70 static mempool_t *nfs_wdata_mempool;
  71 static struct kmem_cache *nfs_cdata_cachep;
  72 static mempool_t *nfs_commit_mempool;
  73
  74 struct nfs_commit_data *nfs_commitdata_alloc(void)
  75 {
  76         struct nfs_commit_data *p;
  77
  78         p = kmem_cache_zalloc(nfs_cdata_cachep, nfs_io_gfp_mask());
  79         if (!p) {
  80                 p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
  81                 if (!p)
  82                         return NULL;
  83                 memset(p, 0, sizeof(*p));
  84         }
  85         INIT_LIST_HEAD(&p->pages);
  86         return p;
  87 }
  88 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  89
  90 void nfs_commit_free(struct nfs_commit_data *p)
  91 {
  92         mempool_free(p, nfs_commit_mempool);
  93 }
  94 EXPORT_SYMBOL_GPL(nfs_commit_free);
  95
  96 static struct nfs_pgio_header *nfs_writehdr_alloc(void)
  97 {
  98         struct nfs_pgio_header *p;
  99
 100         p = kmem_cache_zalloc(nfs_wdata_cachep, nfs_io_gfp_mask());
 101         if (!p) {
 102                 p = mempool_alloc(nfs_wdata_mempool, GFP_NOWAIT);
 103                 if (!p)
 104                         return NULL;
 105                 memset(p, 0, sizeof(*p));
 106         }
 107         p->rw_mode = FMODE_WRITE;
 108         return p;
 109 }
 110
 111 static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 112 {
 113         mempool_free(hdr, nfs_wdata_mempool);
 114 }
 115
 116 static struct nfs_io_completion *nfs_io_completion_alloc(gfp_t gfp_flags)
 117 {
 118         return kmalloc(sizeof(struct nfs_io_completion), gfp_flags);
 119 }
 120
 121 static void nfs_io_completion_init(struct nfs_io_completion *ioc,
 122                 void (*complete)(void *), void *data)
 123 {
 124         ioc->complete = complete;
 125         ioc->data = data;
 126         kref_init(&ioc->refcount);
 127 }
 128
 129 static void nfs_io_completion_release(struct kref *kref)
 130 {
 131         struct nfs_io_completion *ioc = container_of(kref,
 132                         struct nfs_io_completion, refcount);
 133         ioc->complete(ioc->data);
 134         kfree(ioc);
 135 }
 136
 137 static void nfs_io_completion_get(struct nfs_io_completion *ioc)
 138 {
 139         if (ioc != NULL)
 140                 kref_get(&ioc->refcount);
 141 }
 142
 143 static void nfs_io_completion_put(struct nfs_io_completion *ioc)
 144 {
 145         if (ioc != NULL)
 146                 kref_put(&ioc->refcount, nfs_io_completion_release);
 147 }
 148
 149 static void
 150 nfs_page_set_inode_ref(struct nfs_page *req, struct inode *inode)
 151 {
 152         if (!test_and_set_bit(PG_INODE_REF, &req->wb_flags)) {
 153                 kref_get(&req->wb_kref);
 154                 atomic_long_inc(&NFS_I(inode)->nrequests);
 155         }
 156 }
 157
 158 static int
 159 nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode)
 160 {
 161         int ret;
 162
 163         if (!test_bit(PG_REMOVE, &req->wb_flags))
 164                 return 0;
 165         ret = nfs_page_group_lock(req);
 166         if (ret)
 167                 return ret;
 168         if (test_and_clear_bit(PG_REMOVE, &req->wb_flags))
 169                 nfs_page_set_inode_ref(req, inode);
 170         nfs_page_group_unlock(req);
 171         return 0;
 172 }
 173
 174 static struct nfs_page *
 175 nfs_page_private_request(struct page *page)
 176 {
 177         if (!PagePrivate(page))
 178                 return NULL;
 179         return (struct nfs_page *)page_private(page);
 180 }
 181
 182 /*
 183  * nfs_page_find_head_request_locked - find head request associated with @page
 184  *
 185  * must be called while holding the inode lock.
 186  *
 187  * returns matching head request with reference held, or NULL if not found.
 188  */
 189 static struct nfs_page *
 190 nfs_page_find_private_request(struct page *page)
 191 {
 192         struct address_space *mapping = page_file_mapping(page);
 193         struct nfs_page *req;
 194
 195         if (!PagePrivate(page))
 196                 return NULL;
 197         spin_lock(&mapping->private_lock);
 198         req = nfs_page_private_request(page);
 199         if (req) {
 200                 WARN_ON_ONCE(req->wb_head != req);
 201                 kref_get(&req->wb_kref);
 202         }
 203         spin_unlock(&mapping->private_lock);
 204         return req;
 205 }
 206
 207 static struct nfs_page *
 208 nfs_page_find_swap_request(struct page *page)
 209 {
 210         struct inode *inode = page_file_mapping(page)->host;
 211         struct nfs_inode *nfsi = NFS_I(inode);
 212         struct nfs_page *req = NULL;
 213         if (!PageSwapCache(page))
 214                 return NULL;
 215         mutex_lock(&nfsi->commit_mutex);
 216         if (PageSwapCache(page)) {
 217                 req = nfs_page_search_commits_for_head_request_locked(nfsi,
 218                         page);
 219                 if (req) {
 220                         WARN_ON_ONCE(req->wb_head != req);
 221                         kref_get(&req->wb_kref);
 222                 }
 223         }
 224         mutex_unlock(&nfsi->commit_mutex);
 225         return req;
 226 }
 227
 228 /*
 229  * nfs_page_find_head_request - find head request associated with @page
 230  *
 231  * returns matching head request with reference held, or NULL if not found.
 232  */
 233 static struct nfs_page *nfs_page_find_head_request(struct page *page)
 234 {
 235         struct nfs_page *req;
 236
 237         req = nfs_page_find_private_request(page);
 238         if (!req)
 239                 req = nfs_page_find_swap_request(page);
 240         return req;
 241 }
 242
 243 static struct nfs_page *nfs_find_and_lock_page_request(struct page *page)
 244 {
 245         struct inode *inode = page_file_mapping(page)->host;
 246         struct nfs_page *req, *head;
 247         int ret;
 248
 249         for (;;) {
 250                 req = nfs_page_find_head_request(page);
 251                 if (!req)
 252                         return req;
 253                 head = nfs_page_group_lock_head(req);
 254                 if (head != req)
 255                         nfs_release_request(req);
 256                 if (IS_ERR(head))
 257                         return head;
 258                 ret = nfs_cancel_remove_inode(head, inode);
 259                 if (ret < 0) {
 260                         nfs_unlock_and_release_request(head);
 261                         return ERR_PTR(ret);
 262                 }
 263                 /* Ensure that nobody removed the request before we locked it */
 264                 if (head == nfs_page_private_request(page))
 265                         break;
 266                 if (PageSwapCache(page))
 267                         break;
 268                 nfs_unlock_and_release_request(head);
 269         }
 270         return head;
 271 }
 272
 273 /* Adjust the file length if we're writing beyond the end */
 274 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 275 {
 276         struct inode *inode = page_file_mapping(page)->host;
 277         loff_t end, i_size;
 278         pgoff_t end_index;
 279
 280         spin_lock(&inode->i_lock);
 281         i_size = i_size_read(inode);
 282         end_index = (i_size - 1) >> PAGE_SHIFT;
 283         if (i_size > 0 && page_index(page) < end_index)
 284                 goto out;
 285         end = page_file_offset(page) + ((loff_t)offset+count);
 286         if (i_size >= end)
 287                 goto out;
 288         trace_nfs_size_grow(inode, end);
 289         i_size_write(inode, end);
 290         NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
 291         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 292 out:
 293         spin_unlock(&inode->i_lock);
 294         nfs_fscache_invalidate(inode, 0);
 295 }
 296
 297 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 298 static void nfs_set_pageerror(struct address_space *mapping)
 299 {
 300         struct inode *inode = mapping->host;
 301
 302         nfs_zap_mapping(mapping->host, mapping);
 303         /* Force file size revalidation */
 304         spin_lock(&inode->i_lock);
 305         nfs_set_cache_invalid(inode, NFS_INO_REVAL_FORCED |
 306                                              NFS_INO_INVALID_CHANGE |
 307                                              NFS_INO_INVALID_SIZE);
 308         spin_unlock(&inode->i_lock);
 309 }
 310
 311 static void nfs_mapping_set_error(struct page *page, int error)
 312 {
 313         struct address_space *mapping = page_file_mapping(page);
 314
 315         SetPageError(page);
 316         filemap_set_wb_err(mapping, error);
 317         if (mapping->host)
 318                 errseq_set(&mapping->host->i_sb->s_wb_err,
 319                            error == -ENOSPC ? -ENOSPC : -EIO);
 320         nfs_set_pageerror(mapping);
 321 }
 322
 323 /*
 324  * nfs_page_group_search_locked
 325  * @head - head request of page group
 326  * @page_offset - offset into page
 327  *
 328  * Search page group with head @head to find a request that contains the
 329  * page offset @page_offset.
 330  *
 331  * Returns a pointer to the first matching nfs request, or NULL if no
 332  * match is found.
 333  *
 334  * Must be called with the page group lock held
 335  */
 336 static struct nfs_page *
 337 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
 338 {
 339         struct nfs_page *req;
 340
 341         req = head;
 342         do {
 343                 if (page_offset >= req->wb_pgbase &&
 344                     page_offset < (req->wb_pgbase + req->wb_bytes))
 345                         return req;
 346
 347                 req = req->wb_this_page;
 348         } while (req != head);
 349
 350         return NULL;
 351 }
 352
 353 /*
 354  * nfs_page_group_covers_page
 355  * @head - head request of page group
 356  *
 357  * Return true if the page group with head @head covers the whole page,
 358  * returns false otherwise
 359  */
 360 static bool nfs_page_group_covers_page(struct nfs_page *req)
 361 {
 362         struct nfs_page *tmp;
 363         unsigned int pos = 0;
 364         unsigned int len = nfs_page_length(req->wb_page);
 365
 366         nfs_page_group_lock(req);
 367
 368         for (;;) {
 369                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
 370                 if (!tmp)
 371                         break;
 372                 pos = tmp->wb_pgbase + tmp->wb_bytes;
 373         }
 374
 375         nfs_page_group_unlock(req);
 376         return pos >= len;
 377 }
 378
 379 /* We can set the PG_uptodate flag if we see that a write request
 380  * covers the full page.
 381  */
 382 static void nfs_mark_uptodate(struct nfs_page *req)
 383 {
 384         if (PageUptodate(req->wb_page))
 385                 return;
 386         if (!nfs_page_group_covers_page(req))
 387                 return;
 388         SetPageUptodate(req->wb_page);
 389 }
 390
 391 static int wb_priority(struct writeback_control *wbc)
 392 {
 393         int ret = 0;
 394
 395         if (wbc->sync_mode == WB_SYNC_ALL)
 396                 ret = FLUSH_COND_STABLE;
 397         return ret;
 398 }
 399
 400 /*
 401  * NFS congestion control
 402  */
 403
 404 int nfs_congestion_kb;
 405
 406 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 407 #define NFS_CONGESTION_OFF_THRESH       \
 408         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 409
 410 static void nfs_set_page_writeback(struct page *page)
 411 {
 412         struct inode *inode = page_file_mapping(page)->host;
 413         struct nfs_server *nfss = NFS_SERVER(inode);
 414         int ret = test_set_page_writeback(page);
 415
 416         WARN_ON_ONCE(ret != 0);
 417
 418         if (atomic_long_inc_return(&nfss->writeback) >
 419                         NFS_CONGESTION_ON_THRESH)
 420                 nfss->write_congested = 1;
 421 }
 422
 423 static void nfs_end_page_writeback(struct nfs_page *req)
 424 {
 425         struct inode *inode = page_file_mapping(req->wb_page)->host;
 426         struct nfs_server *nfss = NFS_SERVER(inode);
 427         bool is_done;
 428
 429         is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
 430         nfs_unlock_request(req);
 431         if (!is_done)
 432                 return;
 433
 434         end_page_writeback(req->wb_page);
 435         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 436                 nfss->write_congested = 0;
 437 }
 438
 439 /*
 440  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
 441  *
 442  * @destroy_list - request list (using wb_this_page) terminated by @old_head
 443  * @old_head - the old head of the list
 444  *
 445  * All subrequests must be locked and removed from all lists, so at this point
 446  * they are only "active" in this function, and possibly in nfs_wait_on_request
 447  * with a reference held by some other context.
 448  */
 449 static void
 450 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 451                                  struct nfs_page *old_head,
 452                                  struct inode *inode)
 453 {
 454         while (destroy_list) {
 455                 struct nfs_page *subreq = destroy_list;
 456
 457                 destroy_list = (subreq->wb_this_page == old_head) ?
 458                                    NULL : subreq->wb_this_page;
 459
 460                 /* Note: lock subreq in order to change subreq->wb_head */
 461                 nfs_page_set_headlock(subreq);
 462                 WARN_ON_ONCE(old_head != subreq->wb_head);
 463
 464                 /* make sure old group is not used */
 465                 subreq->wb_this_page = subreq;
 466                 subreq->wb_head = subreq;
 467
 468                 clear_bit(PG_REMOVE, &subreq->wb_flags);
 469
 470                 /* Note: races with nfs_page_group_destroy() */
 471                 if (!kref_read(&subreq->wb_kref)) {
 472                         /* Check if we raced with nfs_page_group_destroy() */
 473                         if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags)) {
 474                                 nfs_page_clear_headlock(subreq);
 475                                 nfs_free_request(subreq);
 476                         } else
 477                                 nfs_page_clear_headlock(subreq);
 478                         continue;
 479                 }
 480                 nfs_page_clear_headlock(subreq);
 481
 482                 nfs_release_request(old_head);
 483
 484                 if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 485                         nfs_release_request(subreq);
 486                         atomic_long_dec(&NFS_I(inode)->nrequests);
 487                 }
 488
 489                 /* subreq is now totally disconnected from page group or any
 490                  * write / commit lists. last chance to wake any waiters */
 491                 nfs_unlock_and_release_request(subreq);
 492         }
 493 }
 494
 495 /*
 496  * nfs_join_page_group - destroy subrequests of the head req
 497  * @head: the page used to lookup the "page group" of nfs_page structures
 498  * @inode: Inode to which the request belongs.
 499  *
 500  * This function joins all sub requests to the head request by first
 501  * locking all requests in the group, cancelling any pending operations
 502  * and finally updating the head request to cover the whole range covered by
 503  * the (former) group.  All subrequests are removed from any write or commit
 504  * lists, unlinked from the group and destroyed.
 505  */
 506 void
 507 nfs_join_page_group(struct nfs_page *head, struct inode *inode)
 508 {
 509         struct nfs_page *subreq;
 510         struct nfs_page *destroy_list = NULL;
 511         unsigned int pgbase, off, bytes;
 512
 513         pgbase = head->wb_pgbase;
 514         bytes = head->wb_bytes;
 515         off = head->wb_offset;
 516         for (subreq = head->wb_this_page; subreq != head;
 517                         subreq = subreq->wb_this_page) {
 518                 /* Subrequests should always form a contiguous range */
 519                 if (pgbase > subreq->wb_pgbase) {
 520                         off -= pgbase - subreq->wb_pgbase;
 521                         bytes += pgbase - subreq->wb_pgbase;
 522                         pgbase = subreq->wb_pgbase;
 523                 }
 524                 bytes = max(subreq->wb_pgbase + subreq->wb_bytes
 525                                 - pgbase, bytes);
 526         }
 527
 528         /* Set the head request's range to cover the former page group */
 529         head->wb_pgbase = pgbase;
 530         head->wb_bytes = bytes;
 531         head->wb_offset = off;
 532
 533         /* Now that all requests are locked, make sure they aren't on any list.
 534          * Commit list removal accounting is done after locks are dropped */
 535         subreq = head;
 536         do {
 537                 nfs_clear_request_commit(subreq);
 538                 subreq = subreq->wb_this_page;
 539         } while (subreq != head);
 540
 541         /* unlink subrequests from head, destroy them later */
 542         if (head->wb_this_page != head) {
 543                 /* destroy list will be terminated by head */
 544                 destroy_list = head->wb_this_page;
 545                 head->wb_this_page = head;
 546         }
 547
 548         nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 549 }
 550
 551 /*
 552  * nfs_lock_and_join_requests - join all subreqs to the head req
 553  * @page: the page used to lookup the "page group" of nfs_page structures
 554  *
 555  * This function joins all sub requests to the head request by first
 556  * locking all requests in the group, cancelling any pending operations
 557  * and finally updating the head request to cover the whole range covered by
 558  * the (former) group.  All subrequests are removed from any write or commit
 559  * lists, unlinked from the group and destroyed.
 560  *
 561  * Returns a locked, referenced pointer to the head request - which after
 562  * this call is guaranteed to be the only request associated with the page.
 563  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
 564  * error was encountered.
 565  */
 566 static struct nfs_page *
 567 nfs_lock_and_join_requests(struct page *page)
 568 {
 569         struct inode *inode = page_file_mapping(page)->host;
 570         struct nfs_page *head;
 571         int ret;
 572
 573         /*
 574          * A reference is taken only on the head request which acts as a
 575          * reference to the whole page group - the group will not be destroyed
 576          * until the head reference is released.
 577          */
 578         head = nfs_find_and_lock_page_request(page);
 579         if (IS_ERR_OR_NULL(head))
 580                 return head;
 581
 582         /* lock each request in the page group */
 583         ret = nfs_page_group_lock_subrequests(head);
 584         if (ret < 0) {
 585                 nfs_unlock_and_release_request(head);
 586                 return ERR_PTR(ret);
 587         }
 588
 589         nfs_join_page_group(head, inode);
 590
 591         return head;
 592 }
 593
 594 static void nfs_write_error(struct nfs_page *req, int error)
 595 {
 596         trace_nfs_write_error(page_file_mapping(req->wb_page)->host, req,
 597                               error);
 598         nfs_mapping_set_error(req->wb_page, error);
 599         nfs_inode_remove_request(req);
 600         nfs_end_page_writeback(req);
 601         nfs_release_request(req);
 602 }
 603
 604 /*
 605  * Find an associated nfs write request, and prepare to flush it out
 606  * May return an error if the user signalled nfs_wait_on_request().
 607  */
 608 static int nfs_page_async_flush(struct page *page,
 609                                 struct writeback_control *wbc,
 610                                 struct nfs_pageio_descriptor *pgio)
 611 {
 612         struct nfs_page *req;
 613         int ret = 0;
 614
 615         req = nfs_lock_and_join_requests(page);
 616         if (!req)
 617                 goto out;
 618         ret = PTR_ERR(req);
 619         if (IS_ERR(req))
 620                 goto out;
 621
 622         nfs_set_page_writeback(page);
 623         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 624
 625         /* If there is a fatal error that covers this write, just exit */
 626         ret = pgio->pg_error;
 627         if (nfs_error_is_fatal_on_server(ret))
 628                 goto out_launder;
 629
 630         ret = 0;
 631         if (!nfs_pageio_add_request(pgio, req)) {
 632                 ret = pgio->pg_error;
 633                 /*
 634                  * Remove the problematic req upon fatal errors on the server
 635                  */
 636                 if (nfs_error_is_fatal_on_server(ret))
 637                         goto out_launder;
 638                 if (wbc->sync_mode == WB_SYNC_NONE)
 639                         ret = AOP_WRITEPAGE_ACTIVATE;
 640                 redirty_page_for_writepage(wbc, page);
 641                 nfs_redirty_request(req);
 642                 pgio->pg_error = 0;
 643         } else
 644                 nfs_add_stats(page_file_mapping(page)->host,
 645                                 NFSIOS_WRITEPAGES, 1);
 646 out:
 647         return ret;
 648 out_launder:
 649         nfs_write_error(req, ret);
 650         return 0;
 651 }
 652
 653 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
 654                             struct nfs_pageio_descriptor *pgio)
 655 {
 656         nfs_pageio_cond_complete(pgio, page_index(page));
 657         return nfs_page_async_flush(page, wbc, pgio);
 658 }
 659
 660 /*
 661  * Write an mmapped page to the server.
 662  */
 663 static int nfs_writepage_locked(struct page *page,
 664                                 struct writeback_control *wbc)
 665 {
 666         struct nfs_pageio_descriptor pgio;
 667         struct inode *inode = page_file_mapping(page)->host;
 668         int err;
 669
 670         if (wbc->sync_mode == WB_SYNC_NONE &&
 671             NFS_SERVER(inode)->write_congested)
 672                 return AOP_WRITEPAGE_ACTIVATE;
 673
 674         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 675         nfs_pageio_init_write(&pgio, inode, 0,
 676                                 false, &nfs_async_write_completion_ops);
 677         err = nfs_do_writepage(page, wbc, &pgio);
 678         pgio.pg_error = 0;
 679         nfs_pageio_complete(&pgio);
 680         return err;
 681 }
 682
 683 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 684 {
 685         int ret;
 686
 687         ret = nfs_writepage_locked(page, wbc);
 688         if (ret != AOP_WRITEPAGE_ACTIVATE)
 689                 unlock_page(page);
 690         return ret;
 691 }
 692
 693 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 694 {
 695         int ret;
 696
 697         ret = nfs_do_writepage(page, wbc, data);
 698         if (ret != AOP_WRITEPAGE_ACTIVATE)
 699                 unlock_page(page);
 700         return ret;
 701 }
 702
 703 static void nfs_io_completion_commit(void *inode)
 704 {
 705         nfs_commit_inode(inode, 0);
 706 }
 707
 708 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 709 {
 710         struct inode *inode = mapping->host;
 711         struct nfs_pageio_descriptor pgio;
 712         struct nfs_io_completion *ioc = NULL;
 713         unsigned int mntflags = NFS_SERVER(inode)->flags;
 714         int priority = 0;
 715         int err;
 716
 717         if (wbc->sync_mode == WB_SYNC_NONE &&
 718             NFS_SERVER(inode)->write_congested)
 719                 return 0;
 720
 721         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 722
 723         if (!(mntflags & NFS_MOUNT_WRITE_EAGER) || wbc->for_kupdate ||
 724             wbc->for_background || wbc->for_sync || wbc->for_reclaim) {
 725                 ioc = nfs_io_completion_alloc(GFP_KERNEL);
 726                 if (ioc)
 727                         nfs_io_completion_init(ioc, nfs_io_completion_commit,
 728                                                inode);
 729                 priority = wb_priority(wbc);
 730         }
 731
 732         do {
 733                 nfs_pageio_init_write(&pgio, inode, priority, false,
 734                                       &nfs_async_write_completion_ops);
 735                 pgio.pg_io_completion = ioc;
 736                 err = write_cache_pages(mapping, wbc, nfs_writepages_callback,
 737                                         &pgio);
 738                 pgio.pg_error = 0;
 739                 nfs_pageio_complete(&pgio);
 740         } while (err < 0 && !nfs_error_is_fatal(err));
 741         nfs_io_completion_put(ioc);
 742
 743         if (err < 0)
 744                 goto out_err;
 745         return 0;
 746 out_err:
 747         return err;
 748 }
 749
 750 /*
 751  * Insert a write request into an inode
 752  */
 753 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 754 {
 755         struct address_space *mapping = page_file_mapping(req->wb_page);
 756         struct nfs_inode *nfsi = NFS_I(inode);
 757
 758         WARN_ON_ONCE(req->wb_this_page != req);
 759
 760         /* Lock the request! */
 761         nfs_lock_request(req);
 762
 763         /*
 764          * Swap-space should not get truncated. Hence no need to plug the race
 765          * with invalidate/truncate.
 766          */
 767         spin_lock(&mapping->private_lock);
 768         if (likely(!PageSwapCache(req->wb_page))) {
 769                 set_bit(PG_MAPPED, &req->wb_flags);
 770                 SetPagePrivate(req->wb_page);
 771                 set_page_private(req->wb_page, (unsigned long)req);
 772         }
 773         spin_unlock(&mapping->private_lock);
 774         atomic_long_inc(&nfsi->nrequests);
 775         /* this a head request for a page group - mark it as having an
 776          * extra reference so sub groups can follow suit.
 777          * This flag also informs pgio layer when to bump nrequests when
 778          * adding subrequests. */
 779         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 780         kref_get(&req->wb_kref);
 781 }
 782
 783 /*
 784  * Remove a write request from an inode
 785  */
 786 static void nfs_inode_remove_request(struct nfs_page *req)
 787 {
 788         struct address_space *mapping = page_file_mapping(req->wb_page);
 789         struct inode *inode = mapping->host;
 790         struct nfs_inode *nfsi = NFS_I(inode);
 791         struct nfs_page *head;
 792
 793         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
 794                 head = req->wb_head;
 795
 796                 spin_lock(&mapping->private_lock);
 797                 if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
 798                         set_page_private(head->wb_page, 0);
 799                         ClearPagePrivate(head->wb_page);
 800                         clear_bit(PG_MAPPED, &head->wb_flags);
 801                 }
 802                 spin_unlock(&mapping->private_lock);
 803         }
 804
 805         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags)) {
 806                 nfs_release_request(req);
 807                 atomic_long_dec(&nfsi->nrequests);
 808         }
 809 }
 810
 811 static void
 812 nfs_mark_request_dirty(struct nfs_page *req)
 813 {
 814         if (req->wb_page)
 815                 __set_page_dirty_nobuffers(req->wb_page);
 816 }
 817
 818 /*
 819  * nfs_page_search_commits_for_head_request_locked
 820  *
 821  * Search through commit lists on @inode for the head request for @page.
 822  * Must be called while holding the inode (which is cinfo) lock.
 823  *
 824  * Returns the head request if found, or NULL if not found.
 825  */
 826 static struct nfs_page *
 827 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 828                                                 struct page *page)
 829 {
 830         struct nfs_page *freq, *t;
 831         struct nfs_commit_info cinfo;
 832         struct inode *inode = &nfsi->vfs_inode;
 833
 834         nfs_init_cinfo_from_inode(&cinfo, inode);
 835
 836         /* search through pnfs commit lists */
 837         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
 838         if (freq)
 839                 return freq->wb_head;
 840
 841         /* Linearly search the commit list for the correct request */
 842         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
 843                 if (freq->wb_page == page)
 844                         return freq->wb_head;
 845         }
 846
 847         return NULL;
 848 }
 849
 850 /**
 851  * nfs_request_add_commit_list_locked - add request to a commit list
 852  * @req: pointer to a struct nfs_page
 853  * @dst: commit list head
 854  * @cinfo: holds list lock and accounting info
 855  *
 856  * This sets the PG_CLEAN bit, updates the cinfo count of
 857  * number of outstanding requests requiring a commit as well as
 858  * the MM page stats.
 859  *
 860  * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
 861  * nfs_page lock.
 862  */
 863 void
 864 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
 865                             struct nfs_commit_info *cinfo)
 866 {
 867         set_bit(PG_CLEAN, &req->wb_flags);
 868         nfs_list_add_request(req, dst);
 869         atomic_long_inc(&cinfo->mds->ncommit);
 870 }
 871 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 872
 873 /**
 874  * nfs_request_add_commit_list - add request to a commit list
 875  * @req: pointer to a struct nfs_page
 876  * @cinfo: holds list lock and accounting info
 877  *
 878  * This sets the PG_CLEAN bit, updates the cinfo count of
 879  * number of outstanding requests requiring a commit as well as
 880  * the MM page stats.
 881  *
 882  * The caller must _not_ hold the cinfo->lock, but must be
 883  * holding the nfs_page lock.
 884  */
 885 void
 886 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 887 {
 888         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 889         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
 890         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 891         if (req->wb_page)
 892                 nfs_mark_page_unstable(req->wb_page, cinfo);
 893 }
 894 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 895
 896 /**
 897  * nfs_request_remove_commit_list - Remove request from a commit list
 898  * @req: pointer to a nfs_page
 899  * @cinfo: holds list lock and accounting info
 900  *
 901  * This clears the PG_CLEAN bit, and updates the cinfo's count of
 902  * number of outstanding requests requiring a commit
 903  * It does not update the MM page stats.
 904  *
 905  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 906  */
 907 void
 908 nfs_request_remove_commit_list(struct nfs_page *req,
 909                                struct nfs_commit_info *cinfo)
 910 {
 911         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 912                 return;
 913         nfs_list_remove_request(req);
 914         atomic_long_dec(&cinfo->mds->ncommit);
 915 }
 916 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 917
 918 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 919                                       struct inode *inode)
 920 {
 921         cinfo->inode = inode;
 922         cinfo->mds = &NFS_I(inode)->commit_info;
 923         cinfo->ds = pnfs_get_ds_info(inode);
 924         cinfo->dreq = NULL;
 925         cinfo->completion_ops = &nfs_commit_completion_ops;
 926 }
 927
 928 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 929                     struct inode *inode,
 930                     struct nfs_direct_req *dreq)
 931 {
 932         if (dreq)
 933                 nfs_init_cinfo_from_dreq(cinfo, dreq);
 934         else
 935                 nfs_init_cinfo_from_inode(cinfo, inode);
 936 }
 937 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 938
 939 /*
 940  * Add a request to the inode's commit list.
 941  */
 942 void
 943 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 944                         struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 945 {
 946         if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 947                 return;
 948         nfs_request_add_commit_list(req, cinfo);
 949 }
 950
 951 static void
 952 nfs_clear_page_commit(struct page *page)
 953 {
 954         dec_node_page_state(page, NR_WRITEBACK);
 955         dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
 956                     WB_WRITEBACK);
 957 }
 958
 959 /* Called holding the request lock on @req */
 960 static void
 961 nfs_clear_request_commit(struct nfs_page *req)
 962 {
 963         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 964                 struct nfs_open_context *ctx = nfs_req_openctx(req);
 965                 struct inode *inode = d_inode(ctx->dentry);
 966                 struct nfs_commit_info cinfo;
 967
 968                 nfs_init_cinfo_from_inode(&cinfo, inode);
 969                 mutex_lock(&NFS_I(inode)->commit_mutex);
 970                 if (!pnfs_clear_request_commit(req, &cinfo)) {
 971                         nfs_request_remove_commit_list(req, &cinfo);
 972                 }
 973                 mutex_unlock(&NFS_I(inode)->commit_mutex);
 974                 nfs_clear_page_commit(req->wb_page);
 975         }
 976 }
 977
 978 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 979 {
 980         if (hdr->verf.committed == NFS_DATA_SYNC)
 981                 return hdr->lseg == NULL;
 982         return hdr->verf.committed != NFS_FILE_SYNC;
 983 }
 984
 985 static void nfs_async_write_init(struct nfs_pgio_header *hdr)
 986 {
 987         nfs_io_completion_get(hdr->io_completion);
 988 }
 989
 990 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 991 {
 992         struct nfs_commit_info cinfo;
 993         unsigned long bytes = 0;
 994
 995         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 996                 goto out;
 997         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
 998         while (!list_empty(&hdr->pages)) {
 999                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1000
1001                 bytes += req->wb_bytes;
1002                 nfs_list_remove_request(req);
1003                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
1004                     (hdr->good_bytes < bytes)) {
1005                         trace_nfs_comp_error(hdr->inode, req, hdr->error);
1006                         nfs_mapping_set_error(req->wb_page, hdr->error);
1007                         goto remove_req;
1008                 }
1009                 if (nfs_write_need_commit(hdr)) {
1010                         /* Reset wb_nio, since the write was successful. */
1011                         req->wb_nio = 0;
1012                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1013                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1014                                 hdr->pgio_mirror_idx);
1015                         goto next;
1016                 }
1017 remove_req:
1018                 nfs_inode_remove_request(req);
1019 next:
1020                 nfs_end_page_writeback(req);
1021                 nfs_release_request(req);
1022         }
1023 out:
1024         nfs_io_completion_put(hdr->io_completion);
1025         hdr->release(hdr);
1026 }
1027
1028 unsigned long
1029 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1030 {
1031         return atomic_long_read(&cinfo->mds->ncommit);
1032 }
1033
1034 /* NFS_I(cinfo->inode)->commit_mutex held by caller */
1035 int
1036 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1037                      struct nfs_commit_info *cinfo, int max)
1038 {
1039         struct nfs_page *req, *tmp;
1040         int ret = 0;
1041
1042         list_for_each_entry_safe(req, tmp, src, wb_list) {
1043                 kref_get(&req->wb_kref);
1044                 if (!nfs_lock_request(req)) {
1045                         nfs_release_request(req);
1046                         continue;
1047                 }
1048                 nfs_request_remove_commit_list(req, cinfo);
1049                 clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1050                 nfs_list_add_request(req, dst);
1051                 ret++;
1052                 if ((ret == max) && !cinfo->dreq)
1053                         break;
1054                 cond_resched();
1055         }
1056         return ret;
1057 }
1058 EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1059
1060 /*
1061  * nfs_scan_commit - Scan an inode for commit requests
1062  * @inode: NFS inode to scan
1063  * @dst: mds destination list
1064  * @cinfo: mds and ds lists of reqs ready to commit
1065  *
1066  * Moves requests from the inode's 'commit' request list.
1067  * The requests are *not* checked to ensure that they form a contiguous set.
1068  */
1069 int
1070 nfs_scan_commit(struct inode *inode, struct list_head *dst,
1071                 struct nfs_commit_info *cinfo)
1072 {
1073         int ret = 0;
1074
1075         if (!atomic_long_read(&cinfo->mds->ncommit))
1076                 return 0;
1077         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1078         if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1079                 const int max = INT_MAX;
1080
1081                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1082                                            cinfo, max);
1083                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1084         }
1085         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1086         return ret;
1087 }
1088
1089 /*
1090  * Search for an existing write request, and attempt to update
1091  * it to reflect a new dirty region on a given page.
1092  *
1093  * If the attempt fails, then the existing request is flushed out
1094  * to disk.
1095  */
1096 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1097                 struct page *page,
1098                 unsigned int offset,
1099                 unsigned int bytes)
1100 {
1101         struct nfs_page *req;
1102         unsigned int rqend;
1103         unsigned int end;
1104         int error;
1105
1106         end = offset + bytes;
1107
1108         req = nfs_lock_and_join_requests(page);
1109         if (IS_ERR_OR_NULL(req))
1110                 return req;
1111
1112         rqend = req->wb_offset + req->wb_bytes;
1113         /*
1114          * Tell the caller to flush out the request if
1115          * the offsets are non-contiguous.
1116          * Note: nfs_flush_incompatible() will already
1117          * have flushed out requests having wrong owners.
1118          */
1119         if (offset > rqend || end < req->wb_offset)
1120                 goto out_flushme;
1121
1122         /* Okay, the request matches. Update the region */
1123         if (offset < req->wb_offset) {
1124                 req->wb_offset = offset;
1125                 req->wb_pgbase = offset;
1126         }
1127         if (end > rqend)
1128                 req->wb_bytes = end - req->wb_offset;
1129         else
1130                 req->wb_bytes = rqend - req->wb_offset;
1131         req->wb_nio = 0;
1132         return req;
1133 out_flushme:
1134         /*
1135          * Note: we mark the request dirty here because
1136          * nfs_lock_and_join_requests() cannot preserve
1137          * commit flags, so we have to replay the write.
1138          */
1139         nfs_mark_request_dirty(req);
1140         nfs_unlock_and_release_request(req);
1141         error = nfs_wb_page(inode, page);
1142         return (error < 0) ? ERR_PTR(error) : NULL;
1143 }
1144
1145 /*
1146  * Try to update an existing write request, or create one if there is none.
1147  *
1148  * Note: Should always be called with the Page Lock held to prevent races
1149  * if we have to add a new request. Also assumes that the caller has
1150  * already called nfs_flush_incompatible() if necessary.
1151  */
1152 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1153                 struct page *page, unsigned int offset, unsigned int bytes)
1154 {
1155         struct inode *inode = page_file_mapping(page)->host;
1156         struct nfs_page *req;
1157
1158         req = nfs_try_to_update_request(inode, page, offset, bytes);
1159         if (req != NULL)
1160                 goto out;
1161         req = nfs_create_request(ctx, page, offset, bytes);
1162         if (IS_ERR(req))
1163                 goto out;
1164         nfs_inode_add_request(inode, req);
1165 out:
1166         return req;
1167 }
1168
1169 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1170                 unsigned int offset, unsigned int count)
1171 {
1172         struct nfs_page *req;
1173
1174         req = nfs_setup_write_request(ctx, page, offset, count);
1175         if (IS_ERR(req))
1176                 return PTR_ERR(req);
1177         /* Update file length */
1178         nfs_grow_file(page, offset, count);
1179         nfs_mark_uptodate(req);
1180         nfs_mark_request_dirty(req);
1181         nfs_unlock_and_release_request(req);
1182         return 0;
1183 }
1184
1185 int nfs_flush_incompatible(struct file *file, struct page *page)
1186 {
1187         struct nfs_open_context *ctx = nfs_file_open_context(file);
1188         struct nfs_lock_context *l_ctx;
1189         struct file_lock_context *flctx = locks_inode_context(file_inode(file));
1190         struct nfs_page *req;
1191         int do_flush, status;
1192         /*
1193          * Look for a request corresponding to this page. If there
1194          * is one, and it belongs to another file, we flush it out
1195          * before we try to copy anything into the page. Do this
1196          * due to the lack of an ACCESS-type call in NFSv2.
1197          * Also do the same if we find a request from an existing
1198          * dropped page.
1199          */
1200         do {
1201                 req = nfs_page_find_head_request(page);
1202                 if (req == NULL)
1203                         return 0;
1204                 l_ctx = req->wb_lock_context;
1205                 do_flush = req->wb_page != page ||
1206                         !nfs_match_open_context(nfs_req_openctx(req), ctx);
1207                 if (l_ctx && flctx &&
1208                     !(list_empty_careful(&flctx->flc_posix) &&
1209                       list_empty_careful(&flctx->flc_flock))) {
1210                         do_flush |= l_ctx->lockowner != current->files;
1211                 }
1212                 nfs_release_request(req);
1213                 if (!do_flush)
1214                         return 0;
1215                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1216         } while (status == 0);
1217         return status;
1218 }
1219
1220 /*
1221  * Avoid buffered writes when a open context credential's key would
1222  * expire soon.
1223  *
1224  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1225  *
1226  * Return 0 and set a credential flag which triggers the inode to flush
1227  * and performs  NFS_FILE_SYNC writes if the key will expired within
1228  * RPC_KEY_EXPIRE_TIMEO.
1229  */
1230 int
1231 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1232 {
1233         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1234
1235         if (nfs_ctx_key_to_expire(ctx, inode) &&
1236             !rcu_access_pointer(ctx->ll_cred))
1237                 /* Already expired! */
1238                 return -EACCES;
1239         return 0;
1240 }
1241
1242 /*
1243  * Test if the open context credential key is marked to expire soon.
1244  */
1245 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1246 {
1247         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1248         struct rpc_cred *cred, *new, *old = NULL;
1249         struct auth_cred acred = {
1250                 .cred = ctx->cred,
1251         };
1252         bool ret = false;
1253
1254         rcu_read_lock();
1255         cred = rcu_dereference(ctx->ll_cred);
1256         if (cred && !(cred->cr_ops->crkey_timeout &&
1257                       cred->cr_ops->crkey_timeout(cred)))
1258                 goto out;
1259         rcu_read_unlock();
1260
1261         new = auth->au_ops->lookup_cred(auth, &acred, 0);
1262         if (new == cred) {
1263                 put_rpccred(new);
1264                 return true;
1265         }
1266         if (IS_ERR_OR_NULL(new)) {
1267                 new = NULL;
1268                 ret = true;
1269         } else if (new->cr_ops->crkey_timeout &&
1270                    new->cr_ops->crkey_timeout(new))
1271                 ret = true;
1272
1273         rcu_read_lock();
1274         old = rcu_dereference_protected(xchg(&ctx->ll_cred,
1275                                              RCU_INITIALIZER(new)), 1);
1276 out:
1277         rcu_read_unlock();
1278         put_rpccred(old);
1279         return ret;
1280 }
1281
1282 /*
1283  * If the page cache is marked as unsafe or invalid, then we can't rely on
1284  * the PageUptodate() flag. In this case, we will need to turn off
1285  * write optimisations that depend on the page contents being correct.
1286  */
1287 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode,
1288                                    unsigned int pagelen)
1289 {
1290         struct nfs_inode *nfsi = NFS_I(inode);
1291
1292         if (nfs_have_delegated_attributes(inode))
1293                 goto out;
1294         if (nfsi->cache_validity &
1295             (NFS_INO_INVALID_CHANGE | NFS_INO_INVALID_SIZE))
1296                 return false;
1297         smp_rmb();
1298         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags) && pagelen != 0)
1299                 return false;
1300 out:
1301         if (nfsi->cache_validity & NFS_INO_INVALID_DATA && pagelen != 0)
1302                 return false;
1303         return PageUptodate(page) != 0;
1304 }
1305
1306 static bool
1307 is_whole_file_wrlock(struct file_lock *fl)
1308 {
1309         return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1310                         fl->fl_type == F_WRLCK;
1311 }
1312
1313 /* If we know the page is up to date, and we're not using byte range locks (or
1314  * if we have the whole file locked for writing), it may be more efficient to
1315  * extend the write to cover the entire page in order to avoid fragmentation
1316  * inefficiencies.
1317  *
1318  * If the file is opened for synchronous writes then we can just skip the rest
1319  * of the checks.
1320  */
1321 static int nfs_can_extend_write(struct file *file, struct page *page,
1322                                 struct inode *inode, unsigned int pagelen)
1323 {
1324         int ret;
1325         struct file_lock_context *flctx = locks_inode_context(inode);
1326         struct file_lock *fl;
1327
1328         if (file->f_flags & O_DSYNC)
1329                 return 0;
1330         if (!nfs_write_pageuptodate(page, inode, pagelen))
1331                 return 0;
1332         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1333                 return 1;
1334         if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1335                        list_empty_careful(&flctx->flc_posix)))
1336                 return 1;
1337
1338         /* Check to see if there are whole file write locks */
1339         ret = 0;
1340         spin_lock(&flctx->flc_lock);
1341         if (!list_empty(&flctx->flc_posix)) {
1342                 fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1343                                         fl_list);
1344                 if (is_whole_file_wrlock(fl))
1345                         ret = 1;
1346         } else if (!list_empty(&flctx->flc_flock)) {
1347                 fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1348                                         fl_list);
1349                 if (fl->fl_type == F_WRLCK)
1350                         ret = 1;
1351         }
1352         spin_unlock(&flctx->flc_lock);
1353         return ret;
1354 }
1355
1356 /*
1357  * Update and possibly write a cached page of an NFS file.
1358  *
1359  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1360  * things with a page scheduled for an RPC call (e.g. invalidate it).
1361  */
1362 int nfs_updatepage(struct file *file, struct page *page,
1363                 unsigned int offset, unsigned int count)
1364 {
1365         struct nfs_open_context *ctx = nfs_file_open_context(file);
1366         struct address_space *mapping = page_file_mapping(page);
1367         struct inode    *inode = mapping->host;
1368         unsigned int    pagelen = nfs_page_length(page);
1369         int             status = 0;
1370
1371         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1372
1373         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1374                 file, count, (long long)(page_file_offset(page) + offset));
1375
1376         if (!count)
1377                 goto out;
1378
1379         if (nfs_can_extend_write(file, page, inode, pagelen)) {
1380                 count = max(count + offset, pagelen);
1381                 offset = 0;
1382         }
1383
1384         status = nfs_writepage_setup(ctx, page, offset, count);
1385         if (status < 0)
1386                 nfs_set_pageerror(mapping);
1387 out:
1388         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1389                         status, (long long)i_size_read(inode));
1390         return status;
1391 }
1392
1393 static int flush_task_priority(int how)
1394 {
1395         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1396                 case FLUSH_HIGHPRI:
1397                         return RPC_PRIORITY_HIGH;
1398                 case FLUSH_LOWPRI:
1399                         return RPC_PRIORITY_LOW;
1400         }
1401         return RPC_PRIORITY_NORMAL;
1402 }
1403
1404 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1405                                struct rpc_message *msg,
1406                                const struct nfs_rpc_ops *rpc_ops,
1407                                struct rpc_task_setup *task_setup_data, int how)
1408 {
1409         int priority = flush_task_priority(how);
1410
1411         if (IS_SWAPFILE(hdr->inode))
1412                 task_setup_data->flags |= RPC_TASK_SWAPPER;
1413         task_setup_data->priority = priority;
1414         rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1415         trace_nfs_initiate_write(hdr);
1416 }
1417
1418 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1419  * call this on each, which will prepare them to be retried on next
1420  * writeback using standard nfs.
1421  */
1422 static void nfs_redirty_request(struct nfs_page *req)
1423 {
1424         struct nfs_inode *nfsi = NFS_I(page_file_mapping(req->wb_page)->host);
1425
1426         /* Bump the transmission count */
1427         req->wb_nio++;
1428         nfs_mark_request_dirty(req);
1429         atomic_long_inc(&nfsi->redirtied_pages);
1430         nfs_end_page_writeback(req);
1431         nfs_release_request(req);
1432 }
1433
1434 static void nfs_async_write_error(struct list_head *head, int error)
1435 {
1436         struct nfs_page *req;
1437
1438         while (!list_empty(head)) {
1439                 req = nfs_list_entry(head->next);
1440                 nfs_list_remove_request(req);
1441                 if (nfs_error_is_fatal_on_server(error))
1442                         nfs_write_error(req, error);
1443                 else
1444                         nfs_redirty_request(req);
1445         }
1446 }
1447
1448 static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1449 {
1450         nfs_async_write_error(&hdr->pages, 0);
1451 }
1452
1453 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1454         .init_hdr = nfs_async_write_init,
1455         .error_cleanup = nfs_async_write_error,
1456         .completion = nfs_write_completion,
1457         .reschedule_io = nfs_async_write_reschedule_io,
1458 };
1459
1460 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1461                                struct inode *inode, int ioflags, bool force_mds,
1462                                const struct nfs_pgio_completion_ops *compl_ops)
1463 {
1464         struct nfs_server *server = NFS_SERVER(inode);
1465         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1466
1467 #ifdef CONFIG_NFS_V4_1
1468         if (server->pnfs_curr_ld && !force_mds)
1469                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1470 #endif
1471         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1472                         server->wsize, ioflags);
1473 }
1474 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1475
1476 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1477 {
1478         struct nfs_pgio_mirror *mirror;
1479
1480         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1481                 pgio->pg_ops->pg_cleanup(pgio);
1482
1483         pgio->pg_ops = &nfs_pgio_rw_ops;
1484
1485         nfs_pageio_stop_mirroring(pgio);
1486
1487         mirror = &pgio->pg_mirrors[0];
1488         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1489 }
1490 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1491
1492
1493 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1494 {
1495         struct nfs_commit_data *data = calldata;
1496
1497         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1498 }
1499
1500 static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1501                 struct nfs_fattr *fattr)
1502 {
1503         struct nfs_pgio_args *argp = &hdr->args;
1504         struct nfs_pgio_res *resp = &hdr->res;
1505         u64 size = argp->offset + resp->count;
1506
1507         if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1508                 fattr->size = size;
1509         if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1510                 fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1511                 return;
1512         }
1513         if (size != fattr->size)
1514                 return;
1515         /* Set attribute barrier */
1516         nfs_fattr_set_barrier(fattr);
1517         /* ...and update size */
1518         fattr->valid |= NFS_ATTR_FATTR_SIZE;
1519 }
1520
1521 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1522 {
1523         struct nfs_fattr *fattr = &hdr->fattr;
1524         struct inode *inode = hdr->inode;
1525
1526         spin_lock(&inode->i_lock);
1527         nfs_writeback_check_extend(hdr, fattr);
1528         nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1529         spin_unlock(&inode->i_lock);
1530 }
1531 EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1532
1533 /*
1534  * This function is called when the WRITE call is complete.
1535  */
1536 static int nfs_writeback_done(struct rpc_task *task,
1537                               struct nfs_pgio_header *hdr,
1538                               struct inode *inode)
1539 {
1540         int status;
1541
1542         /*
1543          * ->write_done will attempt to use post-op attributes to detect
1544          * conflicting writes by other clients.  A strict interpretation
1545          * of close-to-open would allow us to continue caching even if
1546          * another writer had changed the file, but some applications
1547          * depend on tighter cache coherency when writing.
1548          */
1549         status = NFS_PROTO(inode)->write_done(task, hdr);
1550         if (status != 0)
1551                 return status;
1552
1553         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1554         trace_nfs_writeback_done(task, hdr);
1555
1556         if (task->tk_status >= 0) {
1557                 enum nfs3_stable_how committed = hdr->res.verf->committed;
1558
1559                 if (committed == NFS_UNSTABLE) {
1560                         /*
1561                          * We have some uncommitted data on the server at
1562                          * this point, so ensure that we keep track of that
1563                          * fact irrespective of what later writes do.
1564                          */
1565                         set_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags);
1566                 }
1567
1568                 if (committed < hdr->args.stable) {
1569                         /* We tried a write call, but the server did not
1570                          * commit data to stable storage even though we
1571                          * requested it.
1572                          * Note: There is a known bug in Tru64 < 5.0 in which
1573                          *       the server reports NFS_DATA_SYNC, but performs
1574                          *       NFS_FILE_SYNC. We therefore implement this checking
1575                          *       as a dprintk() in order to avoid filling syslog.
1576                          */
1577                         static unsigned long    complain;
1578
1579                         /* Note this will print the MDS for a DS write */
1580                         if (time_before(complain, jiffies)) {
1581                                 dprintk("NFS:       faulty NFS server %s:"
1582                                         " (committed = %d) != (stable = %d)\n",
1583                                         NFS_SERVER(inode)->nfs_client->cl_hostname,
1584                                         committed, hdr->args.stable);
1585                                 complain = jiffies + 300 * HZ;
1586                         }
1587                 }
1588         }
1589
1590         /* Deal with the suid/sgid bit corner case */
1591         if (nfs_should_remove_suid(inode)) {
1592                 spin_lock(&inode->i_lock);
1593                 nfs_set_cache_invalid(inode, NFS_INO_INVALID_MODE);
1594                 spin_unlock(&inode->i_lock);
1595         }
1596         return 0;
1597 }
1598
1599 /*
1600  * This function is called when the WRITE call is complete.
1601  */
1602 static void nfs_writeback_result(struct rpc_task *task,
1603                                  struct nfs_pgio_header *hdr)
1604 {
1605         struct nfs_pgio_args    *argp = &hdr->args;
1606         struct nfs_pgio_res     *resp = &hdr->res;
1607
1608         if (resp->count < argp->count) {
1609                 static unsigned long    complain;
1610
1611                 /* This a short write! */
1612                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1613
1614                 /* Has the server at least made some progress? */
1615                 if (resp->count == 0) {
1616                         if (time_before(complain, jiffies)) {
1617                                 printk(KERN_WARNING
1618                                        "NFS: Server wrote zero bytes, expected %u.\n",
1619                                        argp->count);
1620                                 complain = jiffies + 300 * HZ;
1621                         }
1622                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1623                         task->tk_status = -EIO;
1624                         return;
1625                 }
1626
1627                 /* For non rpc-based layout drivers, retry-through-MDS */
1628                 if (!task->tk_ops) {
1629                         hdr->pnfs_error = -EAGAIN;
1630                         return;
1631                 }
1632
1633                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1634                 if (resp->verf->committed != NFS_UNSTABLE) {
1635                         /* Resend from where the server left off */
1636                         hdr->mds_offset += resp->count;
1637                         argp->offset += resp->count;
1638                         argp->pgbase += resp->count;
1639                         argp->count -= resp->count;
1640                 } else {
1641                         /* Resend as a stable write in order to avoid
1642                          * headaches in the case of a server crash.
1643                          */
1644                         argp->stable = NFS_FILE_SYNC;
1645                 }
1646                 resp->count = 0;
1647                 resp->verf->committed = 0;
1648                 rpc_restart_call_prepare(task);
1649         }
1650 }
1651
1652 static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1653 {
1654         return wait_var_event_killable(&cinfo->rpcs_out,
1655                                        !atomic_read(&cinfo->rpcs_out));
1656 }
1657
1658 static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1659 {
1660         atomic_inc(&cinfo->rpcs_out);
1661 }
1662
1663 bool nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1664 {
1665         if (atomic_dec_and_test(&cinfo->rpcs_out)) {
1666                 wake_up_var(&cinfo->rpcs_out);
1667                 return true;
1668         }
1669         return false;
1670 }
1671
1672 void nfs_commitdata_release(struct nfs_commit_data *data)
1673 {
1674         put_nfs_open_context(data->context);
1675         nfs_commit_free(data);
1676 }
1677 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1678
1679 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1680                         const struct nfs_rpc_ops *nfs_ops,
1681                         const struct rpc_call_ops *call_ops,
1682                         int how, int flags)
1683 {
1684         struct rpc_task *task;
1685         int priority = flush_task_priority(how);
1686         struct rpc_message msg = {
1687                 .rpc_argp = &data->args,
1688                 .rpc_resp = &data->res,
1689                 .rpc_cred = data->cred,
1690         };
1691         struct rpc_task_setup task_setup_data = {
1692                 .task = &data->task,
1693                 .rpc_client = clnt,
1694                 .rpc_message = &msg,
1695                 .callback_ops = call_ops,
1696                 .callback_data = data,
1697                 .workqueue = nfsiod_workqueue,
1698                 .flags = RPC_TASK_ASYNC | flags,
1699                 .priority = priority,
1700         };
1701
1702         if (nfs_server_capable(data->inode, NFS_CAP_MOVEABLE))
1703                 task_setup_data.flags |= RPC_TASK_MOVEABLE;
1704
1705         /* Set up the initial task struct.  */
1706         nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1707         trace_nfs_initiate_commit(data);
1708
1709         dprintk("NFS: initiated commit call\n");
1710
1711         task = rpc_run_task(&task_setup_data);
1712         if (IS_ERR(task))
1713                 return PTR_ERR(task);
1714         if (how & FLUSH_SYNC)
1715                 rpc_wait_for_completion_task(task);
1716         rpc_put_task(task);
1717         return 0;
1718 }
1719 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1720
1721 static loff_t nfs_get_lwb(struct list_head *head)
1722 {
1723         loff_t lwb = 0;
1724         struct nfs_page *req;
1725
1726         list_for_each_entry(req, head, wb_list)
1727                 if (lwb < (req_offset(req) + req->wb_bytes))
1728                         lwb = req_offset(req) + req->wb_bytes;
1729
1730         return lwb;
1731 }
1732
1733 /*
1734  * Set up the argument/result storage required for the RPC call.
1735  */
1736 void nfs_init_commit(struct nfs_commit_data *data,
1737                      struct list_head *head,
1738                      struct pnfs_layout_segment *lseg,
1739                      struct nfs_commit_info *cinfo)
1740 {
1741         struct nfs_page *first;
1742         struct nfs_open_context *ctx;
1743         struct inode *inode;
1744
1745         /* Set up the RPC argument and reply structs
1746          * NB: take care not to mess about with data->commit et al. */
1747
1748         if (head)
1749                 list_splice_init(head, &data->pages);
1750
1751         first = nfs_list_entry(data->pages.next);
1752         ctx = nfs_req_openctx(first);
1753         inode = d_inode(ctx->dentry);
1754
1755         data->inode       = inode;
1756         data->cred        = ctx->cred;
1757         data->lseg        = lseg; /* reference transferred */
1758         /* only set lwb for pnfs commit */
1759         if (lseg)
1760                 data->lwb = nfs_get_lwb(&data->pages);
1761         data->mds_ops     = &nfs_commit_ops;
1762         data->completion_ops = cinfo->completion_ops;
1763         data->dreq        = cinfo->dreq;
1764
1765         data->args.fh     = NFS_FH(data->inode);
1766         /* Note: we always request a commit of the entire inode */
1767         data->args.offset = 0;
1768         data->args.count  = 0;
1769         data->context     = get_nfs_open_context(ctx);
1770         data->res.fattr   = &data->fattr;
1771         data->res.verf    = &data->verf;
1772         nfs_fattr_init(&data->fattr);
1773         nfs_commit_begin(cinfo->mds);
1774 }
1775 EXPORT_SYMBOL_GPL(nfs_init_commit);
1776
1777 void nfs_retry_commit(struct list_head *page_list,
1778                       struct pnfs_layout_segment *lseg,
1779                       struct nfs_commit_info *cinfo,
1780                       u32 ds_commit_idx)
1781 {
1782         struct nfs_page *req;
1783
1784         while (!list_empty(page_list)) {
1785                 req = nfs_list_entry(page_list->next);
1786                 nfs_list_remove_request(req);
1787                 nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1788                 if (!cinfo->dreq)
1789                         nfs_clear_page_commit(req->wb_page);
1790                 nfs_unlock_and_release_request(req);
1791         }
1792 }
1793 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1794
1795 static void
1796 nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1797                 struct nfs_page *req)
1798 {
1799         __set_page_dirty_nobuffers(req->wb_page);
1800 }
1801
1802 /*
1803  * Commit dirty pages
1804  */
1805 static int
1806 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1807                 struct nfs_commit_info *cinfo)
1808 {
1809         struct nfs_commit_data  *data;
1810         unsigned short task_flags = 0;
1811
1812         /* another commit raced with us */
1813         if (list_empty(head))
1814                 return 0;
1815
1816         data = nfs_commitdata_alloc();
1817         if (!data) {
1818                 nfs_retry_commit(head, NULL, cinfo, -1);
1819                 return -ENOMEM;
1820         }
1821
1822         /* Set up the argument struct */
1823         nfs_init_commit(data, head, NULL, cinfo);
1824         if (NFS_SERVER(inode)->nfs_client->cl_minorversion)
1825                 task_flags = RPC_TASK_MOVEABLE;
1826         return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1827                                    data->mds_ops, how,
1828                                    RPC_TASK_CRED_NOREF | task_flags);
1829 }
1830
1831 /*
1832  * COMMIT call returned
1833  */
1834 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1835 {
1836         struct nfs_commit_data  *data = calldata;
1837
1838         /* Call the NFS version-specific code */
1839         NFS_PROTO(data->inode)->commit_done(task, data);
1840         trace_nfs_commit_done(task, data);
1841 }
1842
1843 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1844 {
1845         const struct nfs_writeverf *verf = data->res.verf;
1846         struct nfs_page *req;
1847         int status = data->task.tk_status;
1848         struct nfs_commit_info cinfo;
1849         struct nfs_server *nfss;
1850
1851         while (!list_empty(&data->pages)) {
1852                 req = nfs_list_entry(data->pages.next);
1853                 nfs_list_remove_request(req);
1854                 if (req->wb_page)
1855                         nfs_clear_page_commit(req->wb_page);
1856
1857                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1858                         nfs_req_openctx(req)->dentry->d_sb->s_id,
1859                         (unsigned long long)NFS_FILEID(d_inode(nfs_req_openctx(req)->dentry)),
1860                         req->wb_bytes,
1861                         (long long)req_offset(req));
1862                 if (status < 0) {
1863                         if (req->wb_page) {
1864                                 trace_nfs_commit_error(data->inode, req,
1865                                                        status);
1866                                 nfs_mapping_set_error(req->wb_page, status);
1867                                 nfs_inode_remove_request(req);
1868                         }
1869                         dprintk_cont(", error = %d\n", status);
1870                         goto next;
1871                 }
1872
1873                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1874                  * returned by the server against all stored verfs. */
1875                 if (nfs_write_match_verf(verf, req)) {
1876                         /* We have a match */
1877                         if (req->wb_page)
1878                                 nfs_inode_remove_request(req);
1879                         dprintk_cont(" OK\n");
1880                         goto next;
1881                 }
1882                 /* We have a mismatch. Write the page again */
1883                 dprintk_cont(" mismatch\n");
1884                 nfs_mark_request_dirty(req);
1885                 atomic_long_inc(&NFS_I(data->inode)->redirtied_pages);
1886         next:
1887                 nfs_unlock_and_release_request(req);
1888                 /* Latency breaker */
1889                 cond_resched();
1890         }
1891         nfss = NFS_SERVER(data->inode);
1892         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1893                 nfss->write_congested = 0;
1894
1895         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1896         nfs_commit_end(cinfo.mds);
1897 }
1898
1899 static void nfs_commit_release(void *calldata)
1900 {
1901         struct nfs_commit_data *data = calldata;
1902
1903         data->completion_ops->completion(data);
1904         nfs_commitdata_release(calldata);
1905 }
1906
1907 static const struct rpc_call_ops nfs_commit_ops = {
1908         .rpc_call_prepare = nfs_commit_prepare,
1909         .rpc_call_done = nfs_commit_done,
1910         .rpc_release = nfs_commit_release,
1911 };
1912
1913 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1914         .completion = nfs_commit_release_pages,
1915         .resched_write = nfs_commit_resched_write,
1916 };
1917
1918 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1919                             int how, struct nfs_commit_info *cinfo)
1920 {
1921         int status;
1922
1923         status = pnfs_commit_list(inode, head, how, cinfo);
1924         if (status == PNFS_NOT_ATTEMPTED)
1925                 status = nfs_commit_list(inode, head, how, cinfo);
1926         return status;
1927 }
1928
1929 static int __nfs_commit_inode(struct inode *inode, int how,
1930                 struct writeback_control *wbc)
1931 {
1932         LIST_HEAD(head);
1933         struct nfs_commit_info cinfo;
1934         int may_wait = how & FLUSH_SYNC;
1935         int ret, nscan;
1936
1937         how &= ~FLUSH_SYNC;
1938         nfs_init_cinfo_from_inode(&cinfo, inode);
1939         nfs_commit_begin(cinfo.mds);
1940         for (;;) {
1941                 ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1942                 if (ret <= 0)
1943                         break;
1944                 ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1945                 if (ret < 0)
1946                         break;
1947                 ret = 0;
1948                 if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1949                         if (nscan < wbc->nr_to_write)
1950                                 wbc->nr_to_write -= nscan;
1951                         else
1952                                 wbc->nr_to_write = 0;
1953                 }
1954                 if (nscan < INT_MAX)
1955                         break;
1956                 cond_resched();
1957         }
1958         nfs_commit_end(cinfo.mds);
1959         if (ret || !may_wait)
1960                 return ret;
1961         return wait_on_commit(cinfo.mds);
1962 }
1963
1964 int nfs_commit_inode(struct inode *inode, int how)
1965 {
1966         return __nfs_commit_inode(inode, how, NULL);
1967 }
1968 EXPORT_SYMBOL_GPL(nfs_commit_inode);
1969
1970 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1971 {
1972         struct nfs_inode *nfsi = NFS_I(inode);
1973         int flags = FLUSH_SYNC;
1974         int ret = 0;
1975
1976         if (wbc->sync_mode == WB_SYNC_NONE) {
1977                 /* no commits means nothing needs to be done */
1978                 if (!atomic_long_read(&nfsi->commit_info.ncommit))
1979                         goto check_requests_outstanding;
1980
1981                 /* Don't commit yet if this is a non-blocking flush and there
1982                  * are a lot of outstanding writes for this mapping.
1983                  */
1984                 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1985                         goto out_mark_dirty;
1986
1987                 /* don't wait for the COMMIT response */
1988                 flags = 0;
1989         }
1990
1991         ret = __nfs_commit_inode(inode, flags, wbc);
1992         if (!ret) {
1993                 if (flags & FLUSH_SYNC)
1994                         return 0;
1995         } else if (atomic_long_read(&nfsi->commit_info.ncommit))
1996                 goto out_mark_dirty;
1997
1998 check_requests_outstanding:
1999         if (!atomic_read(&nfsi->commit_info.rpcs_out))
2000                 return ret;
2001 out_mark_dirty:
2002         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
2003         return ret;
2004 }
2005 EXPORT_SYMBOL_GPL(nfs_write_inode);
2006
2007 /*
2008  * Wrapper for filemap_write_and_wait_range()
2009  *
2010  * Needed for pNFS in order to ensure data becomes visible to the
2011  * client.
2012  */
2013 int nfs_filemap_write_and_wait_range(struct address_space *mapping,
2014                 loff_t lstart, loff_t lend)
2015 {
2016         int ret;
2017
2018         ret = filemap_write_and_wait_range(mapping, lstart, lend);
2019         if (ret == 0)
2020                 ret = pnfs_sync_inode(mapping->host, true);
2021         return ret;
2022 }
2023 EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
2024
2025 /*
2026  * flush the inode to disk.
2027  */
2028 int nfs_wb_all(struct inode *inode)
2029 {
2030         int ret;
2031
2032         trace_nfs_writeback_inode_enter(inode);
2033
2034         ret = filemap_write_and_wait(inode->i_mapping);
2035         if (ret)
2036                 goto out;
2037         ret = nfs_commit_inode(inode, FLUSH_SYNC);
2038         if (ret < 0)
2039                 goto out;
2040         pnfs_sync_inode(inode, true);
2041         ret = 0;
2042
2043 out:
2044         trace_nfs_writeback_inode_exit(inode, ret);
2045         return ret;
2046 }
2047 EXPORT_SYMBOL_GPL(nfs_wb_all);
2048
2049 int nfs_wb_folio_cancel(struct inode *inode, struct folio *folio)
2050 {
2051         struct nfs_page *req;
2052         int ret = 0;
2053
2054         folio_wait_writeback(folio);
2055
2056         /* blocking call to cancel all requests and join to a single (head)
2057          * request */
2058         req = nfs_lock_and_join_requests(&folio->page);
2059
2060         if (IS_ERR(req)) {
2061                 ret = PTR_ERR(req);
2062         } else if (req) {
2063                 /* all requests from this folio have been cancelled by
2064                  * nfs_lock_and_join_requests, so just remove the head
2065                  * request from the inode / page_private pointer and
2066                  * release it */
2067                 nfs_inode_remove_request(req);
2068                 nfs_unlock_and_release_request(req);
2069         }
2070
2071         return ret;
2072 }
2073
2074 /*
2075  * Write back all requests on one page - we do this before reading it.
2076  */
2077 int nfs_wb_page(struct inode *inode, struct page *page)
2078 {
2079         loff_t range_start = page_file_offset(page);
2080         loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2081         struct writeback_control wbc = {
2082                 .sync_mode = WB_SYNC_ALL,
2083                 .nr_to_write = 0,
2084                 .range_start = range_start,
2085                 .range_end = range_end,
2086         };
2087         int ret;
2088
2089         trace_nfs_writeback_page_enter(inode);
2090
2091         for (;;) {
2092                 wait_on_page_writeback(page);
2093                 if (clear_page_dirty_for_io(page)) {
2094                         ret = nfs_writepage_locked(page, &wbc);
2095                         if (ret < 0)
2096                                 goto out_error;
2097                         continue;
2098                 }
2099                 ret = 0;
2100                 if (!PagePrivate(page))
2101                         break;
2102                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
2103                 if (ret < 0)
2104                         goto out_error;
2105         }
2106 out_error:
2107         trace_nfs_writeback_page_exit(inode, ret);
2108         return ret;
2109 }
2110
2111 #ifdef CONFIG_MIGRATION
2112 int nfs_migrate_folio(struct address_space *mapping, struct folio *dst,
2113                 struct folio *src, enum migrate_mode mode)
2114 {
2115         /*
2116          * If the private flag is set, the folio is currently associated with
2117          * an in-progress read or write request. Don't try to migrate it.
2118          *
2119          * FIXME: we could do this in principle, but we'll need a way to ensure
2120          *        that we can safely release the inode reference while holding
2121          *        the folio lock.
2122          */
2123         if (folio_test_private(src))
2124                 return -EBUSY;
2125
2126         if (folio_test_fscache(src)) {
2127                 if (mode == MIGRATE_ASYNC)
2128                         return -EBUSY;
2129                 folio_wait_fscache(src);
2130         }
2131
2132         return migrate_folio(mapping, dst, src, mode);
2133 }
2134 #endif
2135
2136 int __init nfs_init_writepagecache(void)
2137 {
2138         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2139                                              sizeof(struct nfs_pgio_header),
2140                                              0, SLAB_HWCACHE_ALIGN,
2141                                              NULL);
2142         if (nfs_wdata_cachep == NULL)
2143                 return -ENOMEM;
2144
2145         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2146                                                      nfs_wdata_cachep);
2147         if (nfs_wdata_mempool == NULL)
2148                 goto out_destroy_write_cache;
2149
2150         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2151                                              sizeof(struct nfs_commit_data),
2152                                              0, SLAB_HWCACHE_ALIGN,
2153                                              NULL);
2154         if (nfs_cdata_cachep == NULL)
2155                 goto out_destroy_write_mempool;
2156
2157         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2158                                                       nfs_cdata_cachep);
2159         if (nfs_commit_mempool == NULL)
2160                 goto out_destroy_commit_cache;
2161
2162         /*
2163          * NFS congestion size, scale with available memory.
2164          *
2165          *  64MB:    8192k
2166          * 128MB:   11585k
2167          * 256MB:   16384k
2168          * 512MB:   23170k
2169          *   1GB:   32768k
2170          *   2GB:   46340k
2171          *   4GB:   65536k
2172          *   8GB:   92681k
2173          *  16GB:  131072k
2174          *
2175          * This allows larger machines to have larger/more transfers.
2176          * Limit the default to 256M
2177          */
2178         nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2179         if (nfs_congestion_kb > 256*1024)
2180                 nfs_congestion_kb = 256*1024;
2181
2182         return 0;
2183
2184 out_destroy_commit_cache:
2185         kmem_cache_destroy(nfs_cdata_cachep);
2186 out_destroy_write_mempool:
2187         mempool_destroy(nfs_wdata_mempool);
2188 out_destroy_write_cache:
2189         kmem_cache_destroy(nfs_wdata_cachep);
2190         return -ENOMEM;
2191 }
2192
2193 void nfs_destroy_writepagecache(void)
2194 {
2195         mempool_destroy(nfs_commit_mempool);
2196         kmem_cache_destroy(nfs_cdata_cachep);
2197         mempool_destroy(nfs_wdata_mempool);
2198         kmem_cache_destroy(nfs_wdata_cachep);
2199 }
2200
2201 static const struct nfs_rw_ops nfs_rw_write_ops = {
2202         .rw_alloc_header        = nfs_writehdr_alloc,
2203         .rw_free_header         = nfs_writehdr_free,
2204         .rw_done                = nfs_writeback_done,
2205         .rw_result              = nfs_writeback_result,
2206         .rw_initiate            = nfs_initiate_write,
2207 };