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 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  35
  36 #define MIN_POOL_WRITE          (32)
  37 #define MIN_POOL_COMMIT         (4)
  38
  39 /*
  40  * Local function declarations
  41  */
  42 static void nfs_redirty_request(struct nfs_page *req);
  43 static const struct rpc_call_ops nfs_write_common_ops;
  44 static const struct rpc_call_ops nfs_commit_ops;
  45 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  46 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  47
  48 static struct kmem_cache *nfs_wdata_cachep;
  49 static mempool_t *nfs_wdata_mempool;
  50 static struct kmem_cache *nfs_cdata_cachep;
  51 static mempool_t *nfs_commit_mempool;
  52
  53 struct nfs_commit_data *nfs_commitdata_alloc(void)
  54 {
  55         struct nfs_commit_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
  56
  57         if (p) {
  58                 memset(p, 0, sizeof(*p));
  59                 INIT_LIST_HEAD(&p->pages);
  60         }
  61         return p;
  62 }
  63 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  64
  65 void nfs_commit_free(struct nfs_commit_data *p)
  66 {
  67         mempool_free(p, nfs_commit_mempool);
  68 }
  69 EXPORT_SYMBOL_GPL(nfs_commit_free);
  70
  71 struct nfs_write_header *nfs_writehdr_alloc(void)
  72 {
  73         struct nfs_write_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
  74
  75         if (p) {
  76                 struct nfs_pgio_header *hdr = &p->header;
  77
  78                 memset(p, 0, sizeof(*p));
  79                 INIT_LIST_HEAD(&hdr->pages);
  80                 INIT_LIST_HEAD(&hdr->rpc_list);
  81                 spin_lock_init(&hdr->lock);
  82                 atomic_set(&hdr->refcnt, 0);
  83                 hdr->verf = &p->verf;
  84         }
  85         return p;
  86 }
  87 EXPORT_SYMBOL_GPL(nfs_writehdr_alloc);
  88
  89 static struct nfs_write_data *nfs_writedata_alloc(struct nfs_pgio_header *hdr,
  90                                                   unsigned int pagecount)
  91 {
  92         struct nfs_write_data *data, *prealloc;
  93
  94         prealloc = &container_of(hdr, struct nfs_write_header, header)->rpc_data;
  95         if (prealloc->header == NULL)
  96                 data = prealloc;
  97         else
  98                 data = kzalloc(sizeof(*data), GFP_KERNEL);
  99         if (!data)
 100                 goto out;
 101
 102         if (nfs_pgarray_set(&data->pages, pagecount)) {
 103                 data->header = hdr;
 104                 atomic_inc(&hdr->refcnt);
 105         } else {
 106                 if (data != prealloc)
 107                         kfree(data);
 108                 data = NULL;
 109         }
 110 out:
 111         return data;
 112 }
 113
 114 void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 115 {
 116         struct nfs_write_header *whdr = container_of(hdr, struct nfs_write_header, header);
 117         mempool_free(whdr, nfs_wdata_mempool);
 118 }
 119 EXPORT_SYMBOL_GPL(nfs_writehdr_free);
 120
 121 void nfs_writedata_release(struct nfs_write_data *wdata)
 122 {
 123         struct nfs_pgio_header *hdr = wdata->header;
 124         struct nfs_write_header *write_header = container_of(hdr, struct nfs_write_header, header);
 125
 126         put_nfs_open_context(wdata->args.context);
 127         if (wdata->pages.pagevec != wdata->pages.page_array)
 128                 kfree(wdata->pages.pagevec);
 129         if (wdata != &write_header->rpc_data)
 130                 kfree(wdata);
 131         else
 132                 wdata->header = NULL;
 133         if (atomic_dec_and_test(&hdr->refcnt))
 134                 hdr->completion_ops->completion(hdr);
 135 }
 136 EXPORT_SYMBOL_GPL(nfs_writedata_release);
 137
 138 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 139 {
 140         ctx->error = error;
 141         smp_wmb();
 142         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 143 }
 144
 145 static struct nfs_page *
 146 nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
 147 {
 148         struct nfs_page *req = NULL;
 149
 150         if (PagePrivate(page))
 151                 req = (struct nfs_page *)page_private(page);
 152         else if (unlikely(PageSwapCache(page))) {
 153                 struct nfs_page *freq, *t;
 154
 155                 /* Linearly search the commit list for the correct req */
 156                 list_for_each_entry_safe(freq, t, &nfsi->commit_info.list, wb_list) {
 157                         if (freq->wb_page == page) {
 158                                 req = freq;
 159                                 break;
 160                         }
 161                 }
 162         }
 163
 164         if (req)
 165                 kref_get(&req->wb_kref);
 166
 167         return req;
 168 }
 169
 170 static struct nfs_page *nfs_page_find_request(struct page *page)
 171 {
 172         struct inode *inode = page_file_mapping(page)->host;
 173         struct nfs_page *req = NULL;
 174
 175         spin_lock(&inode->i_lock);
 176         req = nfs_page_find_request_locked(NFS_I(inode), page);
 177         spin_unlock(&inode->i_lock);
 178         return req;
 179 }
 180
 181 /* Adjust the file length if we're writing beyond the end */
 182 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 183 {
 184         struct inode *inode = page_file_mapping(page)->host;
 185         loff_t end, i_size;
 186         pgoff_t end_index;
 187
 188         spin_lock(&inode->i_lock);
 189         i_size = i_size_read(inode);
 190         end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 191         if (i_size > 0 && page_file_index(page) < end_index)
 192                 goto out;
 193         end = page_file_offset(page) + ((loff_t)offset+count);
 194         if (i_size >= end)
 195                 goto out;
 196         i_size_write(inode, end);
 197         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 198 out:
 199         spin_unlock(&inode->i_lock);
 200 }
 201
 202 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 203 static void nfs_set_pageerror(struct page *page)
 204 {
 205         SetPageError(page);
 206         nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
 207 }
 208
 209 /* We can set the PG_uptodate flag if we see that a write request
 210  * covers the full page.
 211  */
 212 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 213 {
 214         if (PageUptodate(page))
 215                 return;
 216         if (base != 0)
 217                 return;
 218         if (count != nfs_page_length(page))
 219                 return;
 220         SetPageUptodate(page);
 221 }
 222
 223 static int wb_priority(struct writeback_control *wbc)
 224 {
 225         if (wbc->for_reclaim)
 226                 return FLUSH_HIGHPRI | FLUSH_STABLE;
 227         if (wbc->for_kupdate || wbc->for_background)
 228                 return FLUSH_LOWPRI | FLUSH_COND_STABLE;
 229         return FLUSH_COND_STABLE;
 230 }
 231
 232 /*
 233  * NFS congestion control
 234  */
 235
 236 int nfs_congestion_kb;
 237
 238 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 239 #define NFS_CONGESTION_OFF_THRESH       \
 240         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 241
 242 static int nfs_set_page_writeback(struct page *page)
 243 {
 244         int ret = test_set_page_writeback(page);
 245
 246         if (!ret) {
 247                 struct inode *inode = page_file_mapping(page)->host;
 248                 struct nfs_server *nfss = NFS_SERVER(inode);
 249
 250                 if (atomic_long_inc_return(&nfss->writeback) >
 251                                 NFS_CONGESTION_ON_THRESH) {
 252                         set_bdi_congested(&nfss->backing_dev_info,
 253                                                 BLK_RW_ASYNC);
 254                 }
 255         }
 256         return ret;
 257 }
 258
 259 static void nfs_end_page_writeback(struct page *page)
 260 {
 261         struct inode *inode = page_file_mapping(page)->host;
 262         struct nfs_server *nfss = NFS_SERVER(inode);
 263
 264         end_page_writeback(page);
 265         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 266                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
 267 }
 268
 269 static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
 270 {
 271         struct inode *inode = page_file_mapping(page)->host;
 272         struct nfs_page *req;
 273         int ret;
 274
 275         spin_lock(&inode->i_lock);
 276         for (;;) {
 277                 req = nfs_page_find_request_locked(NFS_I(inode), page);
 278                 if (req == NULL)
 279                         break;
 280                 if (nfs_lock_request(req))
 281                         break;
 282                 /* Note: If we hold the page lock, as is the case in nfs_writepage,
 283                  *       then the call to nfs_lock_request() will always
 284                  *       succeed provided that someone hasn't already marked the
 285                  *       request as dirty (in which case we don't care).
 286                  */
 287                 spin_unlock(&inode->i_lock);
 288                 if (!nonblock)
 289                         ret = nfs_wait_on_request(req);
 290                 else
 291                         ret = -EAGAIN;
 292                 nfs_release_request(req);
 293                 if (ret != 0)
 294                         return ERR_PTR(ret);
 295                 spin_lock(&inode->i_lock);
 296         }
 297         spin_unlock(&inode->i_lock);
 298         return req;
 299 }
 300
 301 /*
 302  * Find an associated nfs write request, and prepare to flush it out
 303  * May return an error if the user signalled nfs_wait_on_request().
 304  */
 305 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 306                                 struct page *page, bool nonblock)
 307 {
 308         struct nfs_page *req;
 309         int ret = 0;
 310
 311         req = nfs_find_and_lock_request(page, nonblock);
 312         if (!req)
 313                 goto out;
 314         ret = PTR_ERR(req);
 315         if (IS_ERR(req))
 316                 goto out;
 317
 318         ret = nfs_set_page_writeback(page);
 319         BUG_ON(ret != 0);
 320         BUG_ON(test_bit(PG_CLEAN, &req->wb_flags));
 321
 322         if (!nfs_pageio_add_request(pgio, req)) {
 323                 nfs_redirty_request(req);
 324                 ret = pgio->pg_error;
 325         }
 326 out:
 327         return ret;
 328 }
 329
 330 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 331 {
 332         struct inode *inode = page_file_mapping(page)->host;
 333         int ret;
 334
 335         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 336         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 337
 338         nfs_pageio_cond_complete(pgio, page_file_index(page));
 339         ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
 340         if (ret == -EAGAIN) {
 341                 redirty_page_for_writepage(wbc, page);
 342                 ret = 0;
 343         }
 344         return ret;
 345 }
 346
 347 /*
 348  * Write an mmapped page to the server.
 349  */
 350 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 351 {
 352         struct nfs_pageio_descriptor pgio;
 353         int err;
 354
 355         NFS_PROTO(page_file_mapping(page)->host)->write_pageio_init(&pgio,
 356                                                           page->mapping->host,
 357                                                           wb_priority(wbc),
 358                                                           &nfs_async_write_completion_ops);
 359         err = nfs_do_writepage(page, wbc, &pgio);
 360         nfs_pageio_complete(&pgio);
 361         if (err < 0)
 362                 return err;
 363         if (pgio.pg_error < 0)
 364                 return pgio.pg_error;
 365         return 0;
 366 }
 367
 368 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 369 {
 370         int ret;
 371
 372         ret = nfs_writepage_locked(page, wbc);
 373         unlock_page(page);
 374         return ret;
 375 }
 376
 377 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 378 {
 379         int ret;
 380
 381         ret = nfs_do_writepage(page, wbc, data);
 382         unlock_page(page);
 383         return ret;
 384 }
 385
 386 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 387 {
 388         struct inode *inode = mapping->host;
 389         unsigned long *bitlock = &NFS_I(inode)->flags;
 390         struct nfs_pageio_descriptor pgio;
 391         int err;
 392
 393         /* Stop dirtying of new pages while we sync */
 394         err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
 395                         nfs_wait_bit_killable, TASK_KILLABLE);
 396         if (err)
 397                 goto out_err;
 398
 399         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 400
 401         NFS_PROTO(inode)->write_pageio_init(&pgio, inode, wb_priority(wbc), &nfs_async_write_completion_ops);
 402         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 403         nfs_pageio_complete(&pgio);
 404
 405         clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
 406         smp_mb__after_clear_bit();
 407         wake_up_bit(bitlock, NFS_INO_FLUSHING);
 408
 409         if (err < 0)
 410                 goto out_err;
 411         err = pgio.pg_error;
 412         if (err < 0)
 413                 goto out_err;
 414         return 0;
 415 out_err:
 416         return err;
 417 }
 418
 419 /*
 420  * Insert a write request into an inode
 421  */
 422 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 423 {
 424         struct nfs_inode *nfsi = NFS_I(inode);
 425
 426         /* Lock the request! */
 427         nfs_lock_request(req);
 428
 429         spin_lock(&inode->i_lock);
 430         if (!nfsi->npages && NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 431                 inode->i_version++;
 432         /*
 433          * Swap-space should not get truncated. Hence no need to plug the race
 434          * with invalidate/truncate.
 435          */
 436         if (likely(!PageSwapCache(req->wb_page))) {
 437                 set_bit(PG_MAPPED, &req->wb_flags);
 438                 SetPagePrivate(req->wb_page);
 439                 set_page_private(req->wb_page, (unsigned long)req);
 440         }
 441         nfsi->npages++;
 442         kref_get(&req->wb_kref);
 443         spin_unlock(&inode->i_lock);
 444 }
 445
 446 /*
 447  * Remove a write request from an inode
 448  */
 449 static void nfs_inode_remove_request(struct nfs_page *req)
 450 {
 451         struct inode *inode = req->wb_context->dentry->d_inode;
 452         struct nfs_inode *nfsi = NFS_I(inode);
 453
 454         BUG_ON (!NFS_WBACK_BUSY(req));
 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) {
 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  * If the page cache is marked as unsafe or invalid, then we can't rely on
 880  * the PageUptodate() flag. In this case, we will need to turn off
 881  * write optimisations that depend on the page contents being correct.
 882  */
 883 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
 884 {
 885         if (nfs_have_delegated_attributes(inode))
 886                 goto out;
 887         if (NFS_I(inode)->cache_validity & NFS_INO_REVAL_PAGECACHE)
 888                 return false;
 889 out:
 890         return PageUptodate(page) != 0;
 891 }
 892
 893 /*
 894  * Update and possibly write a cached page of an NFS file.
 895  *
 896  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 897  * things with a page scheduled for an RPC call (e.g. invalidate it).
 898  */
 899 int nfs_updatepage(struct file *file, struct page *page,
 900                 unsigned int offset, unsigned int count)
 901 {
 902         struct nfs_open_context *ctx = nfs_file_open_context(file);
 903         struct inode    *inode = page_file_mapping(page)->host;
 904         int             status = 0;
 905
 906         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 907
 908         dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
 909                 file->f_path.dentry->d_parent->d_name.name,
 910                 file->f_path.dentry->d_name.name, count,
 911                 (long long)(page_file_offset(page) + offset));
 912
 913         /* If we're not using byte range locks, and we know the page
 914          * is up to date, it may be more efficient to extend the write
 915          * to cover the entire page in order to avoid fragmentation
 916          * inefficiencies.
 917          */
 918         if (nfs_write_pageuptodate(page, inode) &&
 919                         inode->i_flock == NULL &&
 920                         !(file->f_flags & O_DSYNC)) {
 921                 count = max(count + offset, nfs_page_length(page));
 922                 offset = 0;
 923         }
 924
 925         status = nfs_writepage_setup(ctx, page, offset, count);
 926         if (status < 0)
 927                 nfs_set_pageerror(page);
 928         else
 929                 __set_page_dirty_nobuffers(page);
 930
 931         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 932                         status, (long long)i_size_read(inode));
 933         return status;
 934 }
 935
 936 static int flush_task_priority(int how)
 937 {
 938         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 939                 case FLUSH_HIGHPRI:
 940                         return RPC_PRIORITY_HIGH;
 941                 case FLUSH_LOWPRI:
 942                         return RPC_PRIORITY_LOW;
 943         }
 944         return RPC_PRIORITY_NORMAL;
 945 }
 946
 947 int nfs_initiate_write(struct rpc_clnt *clnt,
 948                        struct nfs_write_data *data,
 949                        const struct rpc_call_ops *call_ops,
 950                        int how, int flags)
 951 {
 952         struct inode *inode = data->header->inode;
 953         int priority = flush_task_priority(how);
 954         struct rpc_task *task;
 955         struct rpc_message msg = {
 956                 .rpc_argp = &data->args,
 957                 .rpc_resp = &data->res,
 958                 .rpc_cred = data->header->cred,
 959         };
 960         struct rpc_task_setup task_setup_data = {
 961                 .rpc_client = clnt,
 962                 .task = &data->task,
 963                 .rpc_message = &msg,
 964                 .callback_ops = call_ops,
 965                 .callback_data = data,
 966                 .workqueue = nfsiod_workqueue,
 967                 .flags = RPC_TASK_ASYNC | flags,
 968                 .priority = priority,
 969         };
 970         int ret = 0;
 971
 972         /* Set up the initial task struct.  */
 973         NFS_PROTO(inode)->write_setup(data, &msg);
 974
 975         dprintk("NFS: %5u initiated write call "
 976                 "(req %s/%lld, %u bytes @ offset %llu)\n",
 977                 data->task.tk_pid,
 978                 inode->i_sb->s_id,
 979                 (long long)NFS_FILEID(inode),
 980                 data->args.count,
 981                 (unsigned long long)data->args.offset);
 982
 983         task = rpc_run_task(&task_setup_data);
 984         if (IS_ERR(task)) {
 985                 ret = PTR_ERR(task);
 986                 goto out;
 987         }
 988         if (how & FLUSH_SYNC) {
 989                 ret = rpc_wait_for_completion_task(task);
 990                 if (ret == 0)
 991                         ret = task->tk_status;
 992         }
 993         rpc_put_task(task);
 994 out:
 995         return ret;
 996 }
 997 EXPORT_SYMBOL_GPL(nfs_initiate_write);
 998
 999 /*
1000  * Set up the argument/result storage required for the RPC call.
1001  */
1002 static void nfs_write_rpcsetup(struct nfs_write_data *data,
1003                 unsigned int count, unsigned int offset,
1004                 int how, struct nfs_commit_info *cinfo)
1005 {
1006         struct nfs_page *req = data->header->req;
1007
1008         /* Set up the RPC argument and reply structs
1009          * NB: take care not to mess about with data->commit et al. */
1010
1011         data->args.fh     = NFS_FH(data->header->inode);
1012         data->args.offset = req_offset(req) + offset;
1013         /* pnfs_set_layoutcommit needs this */
1014         data->mds_offset = data->args.offset;
1015         data->args.pgbase = req->wb_pgbase + offset;
1016         data->args.pages  = data->pages.pagevec;
1017         data->args.count  = count;
1018         data->args.context = get_nfs_open_context(req->wb_context);
1019         data->args.lock_context = req->wb_lock_context;
1020         data->args.stable  = NFS_UNSTABLE;
1021         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
1022         case 0:
1023                 break;
1024         case FLUSH_COND_STABLE:
1025                 if (nfs_reqs_to_commit(cinfo))
1026                         break;
1027         default:
1028                 data->args.stable = NFS_FILE_SYNC;
1029         }
1030
1031         data->res.fattr   = &data->fattr;
1032         data->res.count   = count;
1033         data->res.verf    = &data->verf;
1034         nfs_fattr_init(&data->fattr);
1035 }
1036
1037 static int nfs_do_write(struct nfs_write_data *data,
1038                 const struct rpc_call_ops *call_ops,
1039                 int how)
1040 {
1041         struct inode *inode = data->header->inode;
1042
1043         return nfs_initiate_write(NFS_CLIENT(inode), data, call_ops, how, 0);
1044 }
1045
1046 static int nfs_do_multiple_writes(struct list_head *head,
1047                 const struct rpc_call_ops *call_ops,
1048                 int how)
1049 {
1050         struct nfs_write_data *data;
1051         int ret = 0;
1052
1053         while (!list_empty(head)) {
1054                 int ret2;
1055
1056                 data = list_first_entry(head, struct nfs_write_data, list);
1057                 list_del_init(&data->list);
1058
1059                 ret2 = nfs_do_write(data, call_ops, how);
1060                  if (ret == 0)
1061                          ret = ret2;
1062         }
1063         return ret;
1064 }
1065
1066 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1067  * call this on each, which will prepare them to be retried on next
1068  * writeback using standard nfs.
1069  */
1070 static void nfs_redirty_request(struct nfs_page *req)
1071 {
1072         nfs_mark_request_dirty(req);
1073         nfs_unlock_request(req);
1074         nfs_end_page_writeback(req->wb_page);
1075         nfs_release_request(req);
1076 }
1077
1078 static void nfs_async_write_error(struct list_head *head)
1079 {
1080         struct nfs_page *req;
1081
1082         while (!list_empty(head)) {
1083                 req = nfs_list_entry(head->next);
1084                 nfs_list_remove_request(req);
1085                 nfs_redirty_request(req);
1086         }
1087 }
1088
1089 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1090         .error_cleanup = nfs_async_write_error,
1091         .completion = nfs_write_completion,
1092 };
1093
1094 static void nfs_flush_error(struct nfs_pageio_descriptor *desc,
1095                 struct nfs_pgio_header *hdr)
1096 {
1097         set_bit(NFS_IOHDR_REDO, &hdr->flags);
1098         while (!list_empty(&hdr->rpc_list)) {
1099                 struct nfs_write_data *data = list_first_entry(&hdr->rpc_list,
1100                                 struct nfs_write_data, list);
1101                 list_del(&data->list);
1102                 nfs_writedata_release(data);
1103         }
1104         desc->pg_completion_ops->error_cleanup(&desc->pg_list);
1105 }
1106
1107 /*
1108  * Generate multiple small requests to write out a single
1109  * contiguous dirty area on one page.
1110  */
1111 static int nfs_flush_multi(struct nfs_pageio_descriptor *desc,
1112                            struct nfs_pgio_header *hdr)
1113 {
1114         struct nfs_page *req = hdr->req;
1115         struct page *page = req->wb_page;
1116         struct nfs_write_data *data;
1117         size_t wsize = desc->pg_bsize, nbytes;
1118         unsigned int offset;
1119         int requests = 0;
1120         struct nfs_commit_info cinfo;
1121
1122         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
1123
1124         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1125             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo) ||
1126              desc->pg_count > wsize))
1127                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1128
1129
1130         offset = 0;
1131         nbytes = desc->pg_count;
1132         do {
1133                 size_t len = min(nbytes, wsize);
1134
1135                 data = nfs_writedata_alloc(hdr, 1);
1136                 if (!data) {
1137                         nfs_flush_error(desc, hdr);
1138                         return -ENOMEM;
1139                 }
1140                 data->pages.pagevec[0] = page;
1141                 nfs_write_rpcsetup(data, len, offset, desc->pg_ioflags, &cinfo);
1142                 list_add(&data->list, &hdr->rpc_list);
1143                 requests++;
1144                 nbytes -= len;
1145                 offset += len;
1146         } while (nbytes != 0);
1147         nfs_list_remove_request(req);
1148         nfs_list_add_request(req, &hdr->pages);
1149         desc->pg_rpc_callops = &nfs_write_common_ops;
1150         return 0;
1151 }
1152
1153 /*
1154  * Create an RPC task for the given write request and kick it.
1155  * The page must have been locked by the caller.
1156  *
1157  * It may happen that the page we're passed is not marked dirty.
1158  * This is the case if nfs_updatepage detects a conflicting request
1159  * that has been written but not committed.
1160  */
1161 static int nfs_flush_one(struct nfs_pageio_descriptor *desc,
1162                          struct nfs_pgio_header *hdr)
1163 {
1164         struct nfs_page         *req;
1165         struct page             **pages;
1166         struct nfs_write_data   *data;
1167         struct list_head *head = &desc->pg_list;
1168         struct nfs_commit_info cinfo;
1169
1170         data = nfs_writedata_alloc(hdr, nfs_page_array_len(desc->pg_base,
1171                                                            desc->pg_count));
1172         if (!data) {
1173                 nfs_flush_error(desc, hdr);
1174                 return -ENOMEM;
1175         }
1176
1177         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
1178         pages = data->pages.pagevec;
1179         while (!list_empty(head)) {
1180                 req = nfs_list_entry(head->next);
1181                 nfs_list_remove_request(req);
1182                 nfs_list_add_request(req, &hdr->pages);
1183                 *pages++ = req->wb_page;
1184         }
1185
1186         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1187             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
1188                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1189
1190         /* Set up the argument struct */
1191         nfs_write_rpcsetup(data, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
1192         list_add(&data->list, &hdr->rpc_list);
1193         desc->pg_rpc_callops = &nfs_write_common_ops;
1194         return 0;
1195 }
1196
1197 int nfs_generic_flush(struct nfs_pageio_descriptor *desc,
1198                       struct nfs_pgio_header *hdr)
1199 {
1200         if (desc->pg_bsize < PAGE_CACHE_SIZE)
1201                 return nfs_flush_multi(desc, hdr);
1202         return nfs_flush_one(desc, hdr);
1203 }
1204 EXPORT_SYMBOL_GPL(nfs_generic_flush);
1205
1206 static int nfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
1207 {
1208         struct nfs_write_header *whdr;
1209         struct nfs_pgio_header *hdr;
1210         int ret;
1211
1212         whdr = nfs_writehdr_alloc();
1213         if (!whdr) {
1214                 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
1215                 return -ENOMEM;
1216         }
1217         hdr = &whdr->header;
1218         nfs_pgheader_init(desc, hdr, nfs_writehdr_free);
1219         atomic_inc(&hdr->refcnt);
1220         ret = nfs_generic_flush(desc, hdr);
1221         if (ret == 0)
1222                 ret = nfs_do_multiple_writes(&hdr->rpc_list,
1223                                              desc->pg_rpc_callops,
1224                                              desc->pg_ioflags);
1225         if (atomic_dec_and_test(&hdr->refcnt))
1226                 hdr->completion_ops->completion(hdr);
1227         return ret;
1228 }
1229
1230 static const struct nfs_pageio_ops nfs_pageio_write_ops = {
1231         .pg_test = nfs_generic_pg_test,
1232         .pg_doio = nfs_generic_pg_writepages,
1233 };
1234
1235 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1236                                struct inode *inode, int ioflags,
1237                                const struct nfs_pgio_completion_ops *compl_ops)
1238 {
1239         nfs_pageio_init(pgio, inode, &nfs_pageio_write_ops, compl_ops,
1240                                 NFS_SERVER(inode)->wsize, ioflags);
1241 }
1242 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1243
1244 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1245 {
1246         pgio->pg_ops = &nfs_pageio_write_ops;
1247         pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1248 }
1249 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1250
1251
1252 void nfs_write_prepare(struct rpc_task *task, void *calldata)
1253 {
1254         struct nfs_write_data *data = calldata;
1255         NFS_PROTO(data->header->inode)->write_rpc_prepare(task, data);
1256 }
1257
1258 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1259 {
1260         struct nfs_commit_data *data = calldata;
1261
1262         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1263 }
1264
1265 /*
1266  * Handle a write reply that flushes a whole page.
1267  *
1268  * FIXME: There is an inherent race with invalidate_inode_pages and
1269  *        writebacks since the page->count is kept > 1 for as long
1270  *        as the page has a write request pending.
1271  */
1272 static void nfs_writeback_done_common(struct rpc_task *task, void *calldata)
1273 {
1274         struct nfs_write_data   *data = calldata;
1275
1276         nfs_writeback_done(task, data);
1277 }
1278
1279 static void nfs_writeback_release_common(void *calldata)
1280 {
1281         struct nfs_write_data   *data = calldata;
1282         struct nfs_pgio_header *hdr = data->header;
1283         int status = data->task.tk_status;
1284
1285         if ((status >= 0) && nfs_write_need_commit(data)) {
1286                 spin_lock(&hdr->lock);
1287                 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags))
1288                         ; /* Do nothing */
1289                 else if (!test_and_set_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags))
1290                         memcpy(hdr->verf, &data->verf, sizeof(*hdr->verf));
1291                 else if (memcmp(hdr->verf, &data->verf, sizeof(*hdr->verf)))
1292                         set_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags);
1293                 spin_unlock(&hdr->lock);
1294         }
1295         nfs_writedata_release(data);
1296 }
1297
1298 static const struct rpc_call_ops nfs_write_common_ops = {
1299         .rpc_call_prepare = nfs_write_prepare,
1300         .rpc_call_done = nfs_writeback_done_common,
1301         .rpc_release = nfs_writeback_release_common,
1302 };
1303
1304
1305 /*
1306  * This function is called when the WRITE call is complete.
1307  */
1308 void nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1309 {
1310         struct nfs_writeargs    *argp = &data->args;
1311         struct nfs_writeres     *resp = &data->res;
1312         struct inode            *inode = data->header->inode;
1313         int status;
1314
1315         dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1316                 task->tk_pid, task->tk_status);
1317
1318         /*
1319          * ->write_done will attempt to use post-op attributes to detect
1320          * conflicting writes by other clients.  A strict interpretation
1321          * of close-to-open would allow us to continue caching even if
1322          * another writer had changed the file, but some applications
1323          * depend on tighter cache coherency when writing.
1324          */
1325         status = NFS_PROTO(inode)->write_done(task, data);
1326         if (status != 0)
1327                 return;
1328         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1329
1330 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
1331         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1332                 /* We tried a write call, but the server did not
1333                  * commit data to stable storage even though we
1334                  * requested it.
1335                  * Note: There is a known bug in Tru64 < 5.0 in which
1336                  *       the server reports NFS_DATA_SYNC, but performs
1337                  *       NFS_FILE_SYNC. We therefore implement this checking
1338                  *       as a dprintk() in order to avoid filling syslog.
1339                  */
1340                 static unsigned long    complain;
1341
1342                 /* Note this will print the MDS for a DS write */
1343                 if (time_before(complain, jiffies)) {
1344                         dprintk("NFS:       faulty NFS server %s:"
1345                                 " (committed = %d) != (stable = %d)\n",
1346                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1347                                 resp->verf->committed, argp->stable);
1348                         complain = jiffies + 300 * HZ;
1349                 }
1350         }
1351 #endif
1352         if (task->tk_status < 0)
1353                 nfs_set_pgio_error(data->header, task->tk_status, argp->offset);
1354         else if (resp->count < argp->count) {
1355                 static unsigned long    complain;
1356
1357                 /* This a short write! */
1358                 nfs_inc_stats(inode, NFSIOS_SHORTWRITE);
1359
1360                 /* Has the server at least made some progress? */
1361                 if (resp->count == 0) {
1362                         if (time_before(complain, jiffies)) {
1363                                 printk(KERN_WARNING
1364                                        "NFS: Server wrote zero bytes, expected %u.\n",
1365                                        argp->count);
1366                                 complain = jiffies + 300 * HZ;
1367                         }
1368                         nfs_set_pgio_error(data->header, -EIO, argp->offset);
1369                         task->tk_status = -EIO;
1370                         return;
1371                 }
1372                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1373                 if (resp->verf->committed != NFS_UNSTABLE) {
1374                         /* Resend from where the server left off */
1375                         data->mds_offset += resp->count;
1376                         argp->offset += resp->count;
1377                         argp->pgbase += resp->count;
1378                         argp->count -= resp->count;
1379                 } else {
1380                         /* Resend as a stable write in order to avoid
1381                          * headaches in the case of a server crash.
1382                          */
1383                         argp->stable = NFS_FILE_SYNC;
1384                 }
1385                 rpc_restart_call_prepare(task);
1386         }
1387 }
1388
1389
1390 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
1391 static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
1392 {
1393         int ret;
1394
1395         if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
1396                 return 1;
1397         if (!may_wait)
1398                 return 0;
1399         ret = out_of_line_wait_on_bit_lock(&nfsi->flags,
1400                                 NFS_INO_COMMIT,
1401                                 nfs_wait_bit_killable,
1402                                 TASK_KILLABLE);
1403         return (ret < 0) ? ret : 1;
1404 }
1405
1406 static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
1407 {
1408         clear_bit(NFS_INO_COMMIT, &nfsi->flags);
1409         smp_mb__after_clear_bit();
1410         wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
1411 }
1412
1413 void nfs_commitdata_release(struct nfs_commit_data *data)
1414 {
1415         put_nfs_open_context(data->context);
1416         nfs_commit_free(data);
1417 }
1418 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1419
1420 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1421                         const struct rpc_call_ops *call_ops,
1422                         int how, int flags)
1423 {
1424         struct rpc_task *task;
1425         int priority = flush_task_priority(how);
1426         struct rpc_message msg = {
1427                 .rpc_argp = &data->args,
1428                 .rpc_resp = &data->res,
1429                 .rpc_cred = data->cred,
1430         };
1431         struct rpc_task_setup task_setup_data = {
1432                 .task = &data->task,
1433                 .rpc_client = clnt,
1434                 .rpc_message = &msg,
1435                 .callback_ops = call_ops,
1436                 .callback_data = data,
1437                 .workqueue = nfsiod_workqueue,
1438                 .flags = RPC_TASK_ASYNC | flags,
1439                 .priority = priority,
1440         };
1441         /* Set up the initial task struct.  */
1442         NFS_PROTO(data->inode)->commit_setup(data, &msg);
1443
1444         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1445
1446         task = rpc_run_task(&task_setup_data);
1447         if (IS_ERR(task))
1448                 return PTR_ERR(task);
1449         if (how & FLUSH_SYNC)
1450                 rpc_wait_for_completion_task(task);
1451         rpc_put_task(task);
1452         return 0;
1453 }
1454 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1455
1456 /*
1457  * Set up the argument/result storage required for the RPC call.
1458  */
1459 void nfs_init_commit(struct nfs_commit_data *data,
1460                      struct list_head *head,
1461                      struct pnfs_layout_segment *lseg,
1462                      struct nfs_commit_info *cinfo)
1463 {
1464         struct nfs_page *first = nfs_list_entry(head->next);
1465         struct inode *inode = first->wb_context->dentry->d_inode;
1466
1467         /* Set up the RPC argument and reply structs
1468          * NB: take care not to mess about with data->commit et al. */
1469
1470         list_splice_init(head, &data->pages);
1471
1472         data->inode       = inode;
1473         data->cred        = first->wb_context->cred;
1474         data->lseg        = lseg; /* reference transferred */
1475         data->mds_ops     = &nfs_commit_ops;
1476         data->completion_ops = cinfo->completion_ops;
1477         data->dreq        = cinfo->dreq;
1478
1479         data->args.fh     = NFS_FH(data->inode);
1480         /* Note: we always request a commit of the entire inode */
1481         data->args.offset = 0;
1482         data->args.count  = 0;
1483         data->context     = get_nfs_open_context(first->wb_context);
1484         data->res.fattr   = &data->fattr;
1485         data->res.verf    = &data->verf;
1486         nfs_fattr_init(&data->fattr);
1487 }
1488 EXPORT_SYMBOL_GPL(nfs_init_commit);
1489
1490 void nfs_retry_commit(struct list_head *page_list,
1491                       struct pnfs_layout_segment *lseg,
1492                       struct nfs_commit_info *cinfo)
1493 {
1494         struct nfs_page *req;
1495
1496         while (!list_empty(page_list)) {
1497                 req = nfs_list_entry(page_list->next);
1498                 nfs_list_remove_request(req);
1499                 nfs_mark_request_commit(req, lseg, cinfo);
1500                 if (!cinfo->dreq) {
1501                         dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1502                         dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
1503                                      BDI_RECLAIMABLE);
1504                 }
1505                 nfs_unlock_and_release_request(req);
1506         }
1507 }
1508 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1509
1510 /*
1511  * Commit dirty pages
1512  */
1513 static int
1514 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1515                 struct nfs_commit_info *cinfo)
1516 {
1517         struct nfs_commit_data  *data;
1518
1519         data = nfs_commitdata_alloc();
1520
1521         if (!data)
1522                 goto out_bad;
1523
1524         /* Set up the argument struct */
1525         nfs_init_commit(data, head, NULL, cinfo);
1526         atomic_inc(&cinfo->mds->rpcs_out);
1527         return nfs_initiate_commit(NFS_CLIENT(inode), data, data->mds_ops,
1528                                    how, 0);
1529  out_bad:
1530         nfs_retry_commit(head, NULL, cinfo);
1531         cinfo->completion_ops->error_cleanup(NFS_I(inode));
1532         return -ENOMEM;
1533 }
1534
1535 /*
1536  * COMMIT call returned
1537  */
1538 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1539 {
1540         struct nfs_commit_data  *data = calldata;
1541
1542         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1543                                 task->tk_pid, task->tk_status);
1544
1545         /* Call the NFS version-specific code */
1546         NFS_PROTO(data->inode)->commit_done(task, data);
1547 }
1548
1549 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1550 {
1551         struct nfs_page *req;
1552         int status = data->task.tk_status;
1553         struct nfs_commit_info cinfo;
1554
1555         while (!list_empty(&data->pages)) {
1556                 req = nfs_list_entry(data->pages.next);
1557                 nfs_list_remove_request(req);
1558                 nfs_clear_page_commit(req->wb_page);
1559
1560                 dprintk("NFS:       commit (%s/%lld %d@%lld)",
1561                         req->wb_context->dentry->d_sb->s_id,
1562                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1563                         req->wb_bytes,
1564                         (long long)req_offset(req));
1565                 if (status < 0) {
1566                         nfs_context_set_write_error(req->wb_context, status);
1567                         nfs_inode_remove_request(req);
1568                         dprintk(", error = %d\n", status);
1569                         goto next;
1570                 }
1571
1572                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1573                  * returned by the server against all stored verfs. */
1574                 if (!memcmp(&req->wb_verf, &data->verf.verifier, sizeof(req->wb_verf))) {
1575                         /* We have a match */
1576                         nfs_inode_remove_request(req);
1577                         dprintk(" OK\n");
1578                         goto next;
1579                 }
1580                 /* We have a mismatch. Write the page again */
1581                 dprintk(" mismatch\n");
1582                 nfs_mark_request_dirty(req);
1583                 set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
1584         next:
1585                 nfs_unlock_and_release_request(req);
1586         }
1587         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1588         if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
1589                 nfs_commit_clear_lock(NFS_I(data->inode));
1590 }
1591
1592 static void nfs_commit_release(void *calldata)
1593 {
1594         struct nfs_commit_data *data = calldata;
1595
1596         data->completion_ops->completion(data);
1597         nfs_commitdata_release(calldata);
1598 }
1599
1600 static const struct rpc_call_ops nfs_commit_ops = {
1601         .rpc_call_prepare = nfs_commit_prepare,
1602         .rpc_call_done = nfs_commit_done,
1603         .rpc_release = nfs_commit_release,
1604 };
1605
1606 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1607         .completion = nfs_commit_release_pages,
1608         .error_cleanup = nfs_commit_clear_lock,
1609 };
1610
1611 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1612                             int how, struct nfs_commit_info *cinfo)
1613 {
1614         int status;
1615
1616         status = pnfs_commit_list(inode, head, how, cinfo);
1617         if (status == PNFS_NOT_ATTEMPTED)
1618                 status = nfs_commit_list(inode, head, how, cinfo);
1619         return status;
1620 }
1621
1622 int nfs_commit_inode(struct inode *inode, int how)
1623 {
1624         LIST_HEAD(head);
1625         struct nfs_commit_info cinfo;
1626         int may_wait = how & FLUSH_SYNC;
1627         int res;
1628
1629         res = nfs_commit_set_lock(NFS_I(inode), may_wait);
1630         if (res <= 0)
1631                 goto out_mark_dirty;
1632         nfs_init_cinfo_from_inode(&cinfo, inode);
1633         res = nfs_scan_commit(inode, &head, &cinfo);
1634         if (res) {
1635                 int error;
1636
1637                 error = nfs_generic_commit_list(inode, &head, how, &cinfo);
1638                 if (error < 0)
1639                         return error;
1640                 if (!may_wait)
1641                         goto out_mark_dirty;
1642                 error = wait_on_bit(&NFS_I(inode)->flags,
1643                                 NFS_INO_COMMIT,
1644                                 nfs_wait_bit_killable,
1645                                 TASK_KILLABLE);
1646                 if (error < 0)
1647                         return error;
1648         } else
1649                 nfs_commit_clear_lock(NFS_I(inode));
1650         return res;
1651         /* Note: If we exit without ensuring that the commit is complete,
1652          * we must mark the inode as dirty. Otherwise, future calls to
1653          * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
1654          * that the data is on the disk.
1655          */
1656 out_mark_dirty:
1657         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1658         return res;
1659 }
1660
1661 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1662 {
1663         struct nfs_inode *nfsi = NFS_I(inode);
1664         int flags = FLUSH_SYNC;
1665         int ret = 0;
1666
1667         /* no commits means nothing needs to be done */
1668         if (!nfsi->commit_info.ncommit)
1669                 return ret;
1670
1671         if (wbc->sync_mode == WB_SYNC_NONE) {
1672                 /* Don't commit yet if this is a non-blocking flush and there
1673                  * are a lot of outstanding writes for this mapping.
1674                  */
1675                 if (nfsi->commit_info.ncommit <= (nfsi->npages >> 1))
1676                         goto out_mark_dirty;
1677
1678                 /* don't wait for the COMMIT response */
1679                 flags = 0;
1680         }
1681
1682         ret = nfs_commit_inode(inode, flags);
1683         if (ret >= 0) {
1684                 if (wbc->sync_mode == WB_SYNC_NONE) {
1685                         if (ret < wbc->nr_to_write)
1686                                 wbc->nr_to_write -= ret;
1687                         else
1688                                 wbc->nr_to_write = 0;
1689                 }
1690                 return 0;
1691         }
1692 out_mark_dirty:
1693         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1694         return ret;
1695 }
1696 #else
1697 static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1698 {
1699         return 0;
1700 }
1701 #endif
1702
1703 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1704 {
1705         return nfs_commit_unstable_pages(inode, wbc);
1706 }
1707 EXPORT_SYMBOL_GPL(nfs_write_inode);
1708
1709 /*
1710  * flush the inode to disk.
1711  */
1712 int nfs_wb_all(struct inode *inode)
1713 {
1714         struct writeback_control wbc = {
1715                 .sync_mode = WB_SYNC_ALL,
1716                 .nr_to_write = LONG_MAX,
1717                 .range_start = 0,
1718                 .range_end = LLONG_MAX,
1719         };
1720
1721         return sync_inode(inode, &wbc);
1722 }
1723 EXPORT_SYMBOL_GPL(nfs_wb_all);
1724
1725 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1726 {
1727         struct nfs_page *req;
1728         int ret = 0;
1729
1730         BUG_ON(!PageLocked(page));
1731         for (;;) {
1732                 wait_on_page_writeback(page);
1733                 req = nfs_page_find_request(page);
1734                 if (req == NULL)
1735                         break;
1736                 if (nfs_lock_request(req)) {
1737                         nfs_clear_request_commit(req);
1738                         nfs_inode_remove_request(req);
1739                         /*
1740                          * In case nfs_inode_remove_request has marked the
1741                          * page as being dirty
1742                          */
1743                         cancel_dirty_page(page, PAGE_CACHE_SIZE);
1744                         nfs_unlock_and_release_request(req);
1745                         break;
1746                 }
1747                 ret = nfs_wait_on_request(req);
1748                 nfs_release_request(req);
1749                 if (ret < 0)
1750                         break;
1751         }
1752         return ret;
1753 }
1754
1755 /*
1756  * Write back all requests on one page - we do this before reading it.
1757  */
1758 int nfs_wb_page(struct inode *inode, struct page *page)
1759 {
1760         loff_t range_start = page_file_offset(page);
1761         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1762         struct writeback_control wbc = {
1763                 .sync_mode = WB_SYNC_ALL,
1764                 .nr_to_write = 0,
1765                 .range_start = range_start,
1766                 .range_end = range_end,
1767         };
1768         int ret;
1769
1770         for (;;) {
1771                 wait_on_page_writeback(page);
1772                 if (clear_page_dirty_for_io(page)) {
1773                         ret = nfs_writepage_locked(page, &wbc);
1774                         if (ret < 0)
1775                                 goto out_error;
1776                         continue;
1777                 }
1778                 if (!PagePrivate(page))
1779                         break;
1780                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
1781                 if (ret < 0)
1782                         goto out_error;
1783         }
1784         return 0;
1785 out_error:
1786         return ret;
1787 }
1788
1789 #ifdef CONFIG_MIGRATION
1790 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
1791                 struct page *page, enum migrate_mode mode)
1792 {
1793         /*
1794          * If PagePrivate is set, then the page is currently associated with
1795          * an in-progress read or write request. Don't try to migrate it.
1796          *
1797          * FIXME: we could do this in principle, but we'll need a way to ensure
1798          *        that we can safely release the inode reference while holding
1799          *        the page lock.
1800          */
1801         if (PagePrivate(page))
1802                 return -EBUSY;
1803
1804         nfs_fscache_release_page(page, GFP_KERNEL);
1805
1806         return migrate_page(mapping, newpage, page, mode);
1807 }
1808 #endif
1809
1810 int __init nfs_init_writepagecache(void)
1811 {
1812         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1813                                              sizeof(struct nfs_write_header),
1814                                              0, SLAB_HWCACHE_ALIGN,
1815                                              NULL);
1816         if (nfs_wdata_cachep == NULL)
1817                 return -ENOMEM;
1818
1819         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1820                                                      nfs_wdata_cachep);
1821         if (nfs_wdata_mempool == NULL)
1822                 goto out_destroy_write_cache;
1823
1824         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
1825                                              sizeof(struct nfs_commit_data),
1826                                              0, SLAB_HWCACHE_ALIGN,
1827                                              NULL);
1828         if (nfs_cdata_cachep == NULL)
1829                 goto out_destroy_write_mempool;
1830
1831         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1832                                                       nfs_wdata_cachep);
1833         if (nfs_commit_mempool == NULL)
1834                 goto out_destroy_commit_cache;
1835
1836         /*
1837          * NFS congestion size, scale with available memory.
1838          *
1839          *  64MB:    8192k
1840          * 128MB:   11585k
1841          * 256MB:   16384k
1842          * 512MB:   23170k
1843          *   1GB:   32768k
1844          *   2GB:   46340k
1845          *   4GB:   65536k
1846          *   8GB:   92681k
1847          *  16GB:  131072k
1848          *
1849          * This allows larger machines to have larger/more transfers.
1850          * Limit the default to 256M
1851          */
1852         nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1853         if (nfs_congestion_kb > 256*1024)
1854                 nfs_congestion_kb = 256*1024;
1855
1856         return 0;
1857
1858 out_destroy_commit_cache:
1859         kmem_cache_destroy(nfs_cdata_cachep);
1860 out_destroy_write_mempool:
1861         mempool_destroy(nfs_wdata_mempool);
1862 out_destroy_write_cache:
1863         kmem_cache_destroy(nfs_wdata_cachep);
1864         return -ENOMEM;
1865 }
1866
1867 void nfs_destroy_writepagecache(void)
1868 {
1869         mempool_destroy(nfs_commit_mempool);
1870         kmem_cache_destroy(nfs_cdata_cachep);
1871         mempool_destroy(nfs_wdata_mempool);
1872         kmem_cache_destroy(nfs_wdata_cachep);
1873 }
1874