linux/fs/nfs/write.c
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   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 */
  42static void nfs_redirty_request(struct nfs_page *req);
  43static const struct rpc_call_ops nfs_write_common_ops;
  44static const struct rpc_call_ops nfs_commit_ops;
  45static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  46static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  47
  48static struct kmem_cache *nfs_wdata_cachep;
  49static mempool_t *nfs_wdata_mempool;
  50static struct kmem_cache *nfs_cdata_cachep;
  51static mempool_t *nfs_commit_mempool;
  52
  53struct 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}
  63EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  64
  65void nfs_commit_free(struct nfs_commit_data *p)
  66{
  67        mempool_free(p, nfs_commit_mempool);
  68}
  69EXPORT_SYMBOL_GPL(nfs_commit_free);
  70
  71struct 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}
  87EXPORT_SYMBOL_GPL(nfs_writehdr_alloc);
  88
  89static 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        }
 110out:
 111        return data;
 112}
 113
 114void 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}
 119EXPORT_SYMBOL_GPL(nfs_writehdr_free);
 120
 121void 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}
 136EXPORT_SYMBOL_GPL(nfs_writedata_release);
 137
 138static 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
 145static struct nfs_page *
 146nfs_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
 170static 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 */
 182static 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);
 198out:
 199        spin_unlock(&inode->i_lock);
 200}
 201
 202/* A writeback failed: mark the page as bad, and invalidate the page cache */
 203static 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 */
 212static 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
 223static 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
 236int 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
 242static 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
 259static 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
 269static 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 */
 305static 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        }
 326out:
 327        return ret;
 328}
 329
 330static 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 */
 350static 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
 368int 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
 377static 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
 386int 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;
 415out_err:
 416        return err;
 417}
 418
 419/*
 420 * Insert a write request into an inode
 421 */
 422static 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 */
 449static 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
 467static void
 468nfs_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 */
 487void
 488nfs_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}
 504EXPORT_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 */
 517void
 518nfs_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}
 526EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 527
 528static 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
 538void 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}
 547EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 548
 549/*
 550 * Add a request to the inode's commit list.
 551 */
 552void
 553nfs_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
 561static void
 562nfs_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
 568static void
 569nfs_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
 585static inline
 586int 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
 594static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 595                                      struct inode *inode)
 596{
 597}
 598
 599void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 600                    struct inode *inode,
 601                    struct nfs_direct_req *dreq)
 602{
 603}
 604
 605void
 606nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 607                        struct nfs_commit_info *cinfo)
 608{
 609}
 610
 611static void
 612nfs_clear_request_commit(struct nfs_page *req)
 613{
 614}
 615
 616static inline
 617int nfs_write_need_commit(struct nfs_write_data *data)
 618{
 619        return 0;
 620}
 621
 622#endif
 623
 624static 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                }
 652remove_req:
 653                nfs_inode_remove_request(req);
 654next:
 655                nfs_unlock_request(req);
 656                nfs_end_page_writeback(req->wb_page);
 657                nfs_release_request(req);
 658        }
 659out:
 660        hdr->release(hdr);
 661}
 662
 663#if  IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
 664static unsigned long
 665nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
 666{
 667        return cinfo->mds->ncommit;
 668}
 669
 670/* cinfo->lock held by caller */
 671int
 672nfs_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 */
 702int
 703nfs_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
 721static unsigned long nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
 722{
 723        return 0;
 724}
 725
 726int 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 */
 740static 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;
 793out_unlock:
 794        spin_unlock(&inode->i_lock);
 795        if (req)
 796                nfs_clear_request_commit(req);
 797        return req;
 798out_flushme:
 799        spin_unlock(&inode->i_lock);
 800        nfs_release_request(req);
 801        error = nfs_wb_page(inode, page);
 802out_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 */
 813static 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);
 826out:
 827        return req;
 828}
 829
 830static 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
 846int nfs_flush_incompatible(struct file *file, struct page *page)
 847{
 848        struct nfs_open_context *ctx = nfs_file_open_context(file);
 849        struct nfs_page *req;
 850        int do_flush, status;
 851        /*
 852         * Look for a request corresponding to this page. If there
 853         * is one, and it belongs to another file, we flush it out
 854         * before we try to copy anything into the page. Do this
 855         * due to the lack of an ACCESS-type call in NFSv2.
 856         * Also do the same if we find a request from an existing
 857         * dropped page.
 858         */
 859        do {
 860                req = nfs_page_find_request(page);
 861                if (req == NULL)
 862                        return 0;
 863                do_flush = req->wb_page != page || req->wb_context != ctx ||
 864                        req->wb_lock_context->lockowner != current->files ||
 865                        req->wb_lock_context->pid != current->tgid;
 866                nfs_release_request(req);
 867                if (!do_flush)
 868                        return 0;
 869                status = nfs_wb_page(page_file_mapping(page)->host, page);
 870        } while (status == 0);
 871        return status;
 872}
 873
 874/*
 875 * If the page cache is marked as unsafe or invalid, then we can't rely on
 876 * the PageUptodate() flag. In this case, we will need to turn off
 877 * write optimisations that depend on the page contents being correct.
 878 */
 879static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
 880{
 881        if (nfs_have_delegated_attributes(inode))
 882                goto out;
 883        if (NFS_I(inode)->cache_validity & NFS_INO_REVAL_PAGECACHE)
 884                return false;
 885out:
 886        return PageUptodate(page) != 0;
 887}
 888
 889/*
 890 * Update and possibly write a cached page of an NFS file.
 891 *
 892 * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 893 * things with a page scheduled for an RPC call (e.g. invalidate it).
 894 */
 895int nfs_updatepage(struct file *file, struct page *page,
 896                unsigned int offset, unsigned int count)
 897{
 898        struct nfs_open_context *ctx = nfs_file_open_context(file);
 899        struct inode    *inode = page_file_mapping(page)->host;
 900        int             status = 0;
 901
 902        nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 903
 904        dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
 905                file->f_path.dentry->d_parent->d_name.name,
 906                file->f_path.dentry->d_name.name, count,
 907                (long long)(page_file_offset(page) + offset));
 908
 909        /* If we're not using byte range locks, and we know the page
 910         * is up to date, it may be more efficient to extend the write
 911         * to cover the entire page in order to avoid fragmentation
 912         * inefficiencies.
 913         */
 914        if (nfs_write_pageuptodate(page, inode) &&
 915                        inode->i_flock == NULL &&
 916                        !(file->f_flags & O_DSYNC)) {
 917                count = max(count + offset, nfs_page_length(page));
 918                offset = 0;
 919        }
 920
 921        status = nfs_writepage_setup(ctx, page, offset, count);
 922        if (status < 0)
 923                nfs_set_pageerror(page);
 924        else
 925                __set_page_dirty_nobuffers(page);
 926
 927        dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 928                        status, (long long)i_size_read(inode));
 929        return status;
 930}
 931
 932static int flush_task_priority(int how)
 933{
 934        switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 935                case FLUSH_HIGHPRI:
 936                        return RPC_PRIORITY_HIGH;
 937                case FLUSH_LOWPRI:
 938                        return RPC_PRIORITY_LOW;
 939        }
 940        return RPC_PRIORITY_NORMAL;
 941}
 942
 943int nfs_initiate_write(struct rpc_clnt *clnt,
 944                       struct nfs_write_data *data,
 945                       const struct rpc_call_ops *call_ops,
 946                       int how, int flags)
 947{
 948        struct inode *inode = data->header->inode;
 949        int priority = flush_task_priority(how);
 950        struct rpc_task *task;
 951        struct rpc_message msg = {
 952                .rpc_argp = &data->args,
 953                .rpc_resp = &data->res,
 954                .rpc_cred = data->header->cred,
 955        };
 956        struct rpc_task_setup task_setup_data = {
 957                .rpc_client = clnt,
 958                .task = &data->task,
 959                .rpc_message = &msg,
 960                .callback_ops = call_ops,
 961                .callback_data = data,
 962                .workqueue = nfsiod_workqueue,
 963                .flags = RPC_TASK_ASYNC | flags,
 964                .priority = priority,
 965        };
 966        int ret = 0;
 967
 968        /* Set up the initial task struct.  */
 969        NFS_PROTO(inode)->write_setup(data, &msg);
 970
 971        dprintk("NFS: %5u initiated write call "
 972                "(req %s/%lld, %u bytes @ offset %llu)\n",
 973                data->task.tk_pid,
 974                inode->i_sb->s_id,
 975                (long long)NFS_FILEID(inode),
 976                data->args.count,
 977                (unsigned long long)data->args.offset);
 978
 979        task = rpc_run_task(&task_setup_data);
 980        if (IS_ERR(task)) {
 981                ret = PTR_ERR(task);
 982                goto out;
 983        }
 984        if (how & FLUSH_SYNC) {
 985                ret = rpc_wait_for_completion_task(task);
 986                if (ret == 0)
 987                        ret = task->tk_status;
 988        }
 989        rpc_put_task(task);
 990out:
 991        return ret;
 992}
 993EXPORT_SYMBOL_GPL(nfs_initiate_write);
 994
 995/*
 996 * Set up the argument/result storage required for the RPC call.
 997 */
 998static void nfs_write_rpcsetup(struct nfs_write_data *data,
 999                unsigned int count, unsigned int offset,
1000                int how, struct nfs_commit_info *cinfo)
1001{
1002        struct nfs_page *req = data->header->req;
1003
1004        /* Set up the RPC argument and reply structs
1005         * NB: take care not to mess about with data->commit et al. */
1006
1007        data->args.fh     = NFS_FH(data->header->inode);
1008        data->args.offset = req_offset(req) + offset;
1009        /* pnfs_set_layoutcommit needs this */
1010        data->mds_offset = data->args.offset;
1011        data->args.pgbase = req->wb_pgbase + offset;
1012        data->args.pages  = data->pages.pagevec;
1013        data->args.count  = count;
1014        data->args.context = get_nfs_open_context(req->wb_context);
1015        data->args.lock_context = req->wb_lock_context;
1016        data->args.stable  = NFS_UNSTABLE;
1017        switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
1018        case 0:
1019                break;
1020        case FLUSH_COND_STABLE:
1021                if (nfs_reqs_to_commit(cinfo))
1022                        break;
1023        default:
1024                data->args.stable = NFS_FILE_SYNC;
1025        }
1026
1027        data->res.fattr   = &data->fattr;
1028        data->res.count   = count;
1029        data->res.verf    = &data->verf;
1030        nfs_fattr_init(&data->fattr);
1031}
1032
1033static int nfs_do_write(struct nfs_write_data *data,
1034                const struct rpc_call_ops *call_ops,
1035                int how)
1036{
1037        struct inode *inode = data->header->inode;
1038
1039        return nfs_initiate_write(NFS_CLIENT(inode), data, call_ops, how, 0);
1040}
1041
1042static int nfs_do_multiple_writes(struct list_head *head,
1043                const struct rpc_call_ops *call_ops,
1044                int how)
1045{
1046        struct nfs_write_data *data;
1047        int ret = 0;
1048
1049        while (!list_empty(head)) {
1050                int ret2;
1051
1052                data = list_first_entry(head, struct nfs_write_data, list);
1053                list_del_init(&data->list);
1054                
1055                ret2 = nfs_do_write(data, call_ops, how);
1056                 if (ret == 0)
1057                         ret = ret2;
1058        }
1059        return ret;
1060}
1061
1062/* If a nfs_flush_* function fails, it should remove reqs from @head and
1063 * call this on each, which will prepare them to be retried on next
1064 * writeback using standard nfs.
1065 */
1066static void nfs_redirty_request(struct nfs_page *req)
1067{
1068        nfs_mark_request_dirty(req);
1069        nfs_unlock_request(req);
1070        nfs_end_page_writeback(req->wb_page);
1071        nfs_release_request(req);
1072}
1073
1074static void nfs_async_write_error(struct list_head *head)
1075{
1076        struct nfs_page *req;
1077
1078        while (!list_empty(head)) {
1079                req = nfs_list_entry(head->next);
1080                nfs_list_remove_request(req);
1081                nfs_redirty_request(req);
1082        }
1083}
1084
1085static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1086        .error_cleanup = nfs_async_write_error,
1087        .completion = nfs_write_completion,
1088};
1089
1090static void nfs_flush_error(struct nfs_pageio_descriptor *desc,
1091                struct nfs_pgio_header *hdr)
1092{
1093        set_bit(NFS_IOHDR_REDO, &hdr->flags);
1094        while (!list_empty(&hdr->rpc_list)) {
1095                struct nfs_write_data *data = list_first_entry(&hdr->rpc_list,
1096                                struct nfs_write_data, list);
1097                list_del(&data->list);
1098                nfs_writedata_release(data);
1099        }
1100        desc->pg_completion_ops->error_cleanup(&desc->pg_list);
1101}
1102
1103/*
1104 * Generate multiple small requests to write out a single
1105 * contiguous dirty area on one page.
1106 */
1107static int nfs_flush_multi(struct nfs_pageio_descriptor *desc,
1108                           struct nfs_pgio_header *hdr)
1109{
1110        struct nfs_page *req = hdr->req;
1111        struct page *page = req->wb_page;
1112        struct nfs_write_data *data;
1113        size_t wsize = desc->pg_bsize, nbytes;
1114        unsigned int offset;
1115        int requests = 0;
1116        struct nfs_commit_info cinfo;
1117
1118        nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
1119
1120        if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1121            (desc->pg_moreio || nfs_reqs_to_commit(&cinfo) ||
1122             desc->pg_count > wsize))
1123                desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1124
1125
1126        offset = 0;
1127        nbytes = desc->pg_count;
1128        do {
1129                size_t len = min(nbytes, wsize);
1130
1131                data = nfs_writedata_alloc(hdr, 1);
1132                if (!data) {
1133                        nfs_flush_error(desc, hdr);
1134                        return -ENOMEM;
1135                }
1136                data->pages.pagevec[0] = page;
1137                nfs_write_rpcsetup(data, len, offset, desc->pg_ioflags, &cinfo);
1138                list_add(&data->list, &hdr->rpc_list);
1139                requests++;
1140                nbytes -= len;
1141                offset += len;
1142        } while (nbytes != 0);
1143        nfs_list_remove_request(req);
1144        nfs_list_add_request(req, &hdr->pages);
1145        desc->pg_rpc_callops = &nfs_write_common_ops;
1146        return 0;
1147}
1148
1149/*
1150 * Create an RPC task for the given write request and kick it.
1151 * The page must have been locked by the caller.
1152 *
1153 * It may happen that the page we're passed is not marked dirty.
1154 * This is the case if nfs_updatepage detects a conflicting request
1155 * that has been written but not committed.
1156 */
1157static int nfs_flush_one(struct nfs_pageio_descriptor *desc,
1158                         struct nfs_pgio_header *hdr)
1159{
1160        struct nfs_page         *req;
1161        struct page             **pages;
1162        struct nfs_write_data   *data;
1163        struct list_head *head = &desc->pg_list;
1164        struct nfs_commit_info cinfo;
1165
1166        data = nfs_writedata_alloc(hdr, nfs_page_array_len(desc->pg_base,
1167                                                           desc->pg_count));
1168        if (!data) {
1169                nfs_flush_error(desc, hdr);
1170                return -ENOMEM;
1171        }
1172
1173        nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
1174        pages = data->pages.pagevec;
1175        while (!list_empty(head)) {
1176                req = nfs_list_entry(head->next);
1177                nfs_list_remove_request(req);
1178                nfs_list_add_request(req, &hdr->pages);
1179                *pages++ = req->wb_page;
1180        }
1181
1182        if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1183            (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
1184                desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1185
1186        /* Set up the argument struct */
1187        nfs_write_rpcsetup(data, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
1188        list_add(&data->list, &hdr->rpc_list);
1189        desc->pg_rpc_callops = &nfs_write_common_ops;
1190        return 0;
1191}
1192
1193int nfs_generic_flush(struct nfs_pageio_descriptor *desc,
1194                      struct nfs_pgio_header *hdr)
1195{
1196        if (desc->pg_bsize < PAGE_CACHE_SIZE)
1197                return nfs_flush_multi(desc, hdr);
1198        return nfs_flush_one(desc, hdr);
1199}
1200EXPORT_SYMBOL_GPL(nfs_generic_flush);
1201
1202static int nfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
1203{
1204        struct nfs_write_header *whdr;
1205        struct nfs_pgio_header *hdr;
1206        int ret;
1207
1208        whdr = nfs_writehdr_alloc();
1209        if (!whdr) {
1210                desc->pg_completion_ops->error_cleanup(&desc->pg_list);
1211                return -ENOMEM;
1212        }
1213        hdr = &whdr->header;
1214        nfs_pgheader_init(desc, hdr, nfs_writehdr_free);
1215        atomic_inc(&hdr->refcnt);
1216        ret = nfs_generic_flush(desc, hdr);
1217        if (ret == 0)
1218                ret = nfs_do_multiple_writes(&hdr->rpc_list,
1219                                             desc->pg_rpc_callops,
1220                                             desc->pg_ioflags);
1221        if (atomic_dec_and_test(&hdr->refcnt))
1222                hdr->completion_ops->completion(hdr);
1223        return ret;
1224}
1225
1226static const struct nfs_pageio_ops nfs_pageio_write_ops = {
1227        .pg_test = nfs_generic_pg_test,
1228        .pg_doio = nfs_generic_pg_writepages,
1229};
1230
1231void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1232                               struct inode *inode, int ioflags,
1233                               const struct nfs_pgio_completion_ops *compl_ops)
1234{
1235        nfs_pageio_init(pgio, inode, &nfs_pageio_write_ops, compl_ops,
1236                                NFS_SERVER(inode)->wsize, ioflags);
1237}
1238EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1239
1240void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1241{
1242        pgio->pg_ops = &nfs_pageio_write_ops;
1243        pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1244}
1245EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1246
1247
1248void nfs_write_prepare(struct rpc_task *task, void *calldata)
1249{
1250        struct nfs_write_data *data = calldata;
1251        NFS_PROTO(data->header->inode)->write_rpc_prepare(task, data);
1252}
1253
1254void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1255{
1256        struct nfs_commit_data *data = calldata;
1257
1258        NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1259}
1260
1261/*
1262 * Handle a write reply that flushes a whole page.
1263 *
1264 * FIXME: There is an inherent race with invalidate_inode_pages and
1265 *        writebacks since the page->count is kept > 1 for as long
1266 *        as the page has a write request pending.
1267 */
1268static void nfs_writeback_done_common(struct rpc_task *task, void *calldata)
1269{
1270        struct nfs_write_data   *data = calldata;
1271
1272        nfs_writeback_done(task, data);
1273}
1274
1275static void nfs_writeback_release_common(void *calldata)
1276{
1277        struct nfs_write_data   *data = calldata;
1278        struct nfs_pgio_header *hdr = data->header;
1279        int status = data->task.tk_status;
1280
1281        if ((status >= 0) && nfs_write_need_commit(data)) {
1282                spin_lock(&hdr->lock);
1283                if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags))
1284                        ; /* Do nothing */
1285                else if (!test_and_set_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags))
1286                        memcpy(hdr->verf, &data->verf, sizeof(*hdr->verf));
1287                else if (memcmp(hdr->verf, &data->verf, sizeof(*hdr->verf)))
1288                        set_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags);
1289                spin_unlock(&hdr->lock);
1290        }
1291        nfs_writedata_release(data);
1292}
1293
1294static const struct rpc_call_ops nfs_write_common_ops = {
1295        .rpc_call_prepare = nfs_write_prepare,
1296        .rpc_call_done = nfs_writeback_done_common,
1297        .rpc_release = nfs_writeback_release_common,
1298};
1299
1300
1301/*
1302 * This function is called when the WRITE call is complete.
1303 */
1304void nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1305{
1306        struct nfs_writeargs    *argp = &data->args;
1307        struct nfs_writeres     *resp = &data->res;
1308        struct inode            *inode = data->header->inode;
1309        int status;
1310
1311        dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1312                task->tk_pid, task->tk_status);
1313
1314        /*
1315         * ->write_done will attempt to use post-op attributes to detect
1316         * conflicting writes by other clients.  A strict interpretation
1317         * of close-to-open would allow us to continue caching even if
1318         * another writer had changed the file, but some applications
1319         * depend on tighter cache coherency when writing.
1320         */
1321        status = NFS_PROTO(inode)->write_done(task, data);
1322        if (status != 0)
1323                return;
1324        nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1325
1326#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
1327        if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1328                /* We tried a write call, but the server did not
1329                 * commit data to stable storage even though we
1330                 * requested it.
1331                 * Note: There is a known bug in Tru64 < 5.0 in which
1332                 *       the server reports NFS_DATA_SYNC, but performs
1333                 *       NFS_FILE_SYNC. We therefore implement this checking
1334                 *       as a dprintk() in order to avoid filling syslog.
1335                 */
1336                static unsigned long    complain;
1337
1338                /* Note this will print the MDS for a DS write */
1339                if (time_before(complain, jiffies)) {
1340                        dprintk("NFS:       faulty NFS server %s:"
1341                                " (committed = %d) != (stable = %d)\n",
1342                                NFS_SERVER(inode)->nfs_client->cl_hostname,
1343                                resp->verf->committed, argp->stable);
1344                        complain = jiffies + 300 * HZ;
1345                }
1346        }
1347#endif
1348        if (task->tk_status < 0)
1349                nfs_set_pgio_error(data->header, task->tk_status, argp->offset);
1350        else if (resp->count < argp->count) {
1351                static unsigned long    complain;
1352
1353                /* This a short write! */
1354                nfs_inc_stats(inode, NFSIOS_SHORTWRITE);
1355
1356                /* Has the server at least made some progress? */
1357                if (resp->count == 0) {
1358                        if (time_before(complain, jiffies)) {
1359                                printk(KERN_WARNING
1360                                       "NFS: Server wrote zero bytes, expected %u.\n",
1361                                       argp->count);
1362                                complain = jiffies + 300 * HZ;
1363                        }
1364                        nfs_set_pgio_error(data->header, -EIO, argp->offset);
1365                        task->tk_status = -EIO;
1366                        return;
1367                }
1368                /* Was this an NFSv2 write or an NFSv3 stable write? */
1369                if (resp->verf->committed != NFS_UNSTABLE) {
1370                        /* Resend from where the server left off */
1371                        data->mds_offset += resp->count;
1372                        argp->offset += resp->count;
1373                        argp->pgbase += resp->count;
1374                        argp->count -= resp->count;
1375                } else {
1376                        /* Resend as a stable write in order to avoid
1377                         * headaches in the case of a server crash.
1378                         */
1379                        argp->stable = NFS_FILE_SYNC;
1380                }
1381                rpc_restart_call_prepare(task);
1382        }
1383}
1384
1385
1386#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
1387static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
1388{
1389        int ret;
1390
1391        if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))
1392                return 1;
1393        if (!may_wait)
1394                return 0;
1395        ret = out_of_line_wait_on_bit_lock(&nfsi->flags,
1396                                NFS_INO_COMMIT,
1397                                nfs_wait_bit_killable,
1398                                TASK_KILLABLE);
1399        return (ret < 0) ? ret : 1;
1400}
1401
1402static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
1403{
1404        clear_bit(NFS_INO_COMMIT, &nfsi->flags);
1405        smp_mb__after_clear_bit();
1406        wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
1407}
1408
1409void nfs_commitdata_release(struct nfs_commit_data *data)
1410{
1411        put_nfs_open_context(data->context);
1412        nfs_commit_free(data);
1413}
1414EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1415
1416int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1417                        const struct rpc_call_ops *call_ops,
1418                        int how, int flags)
1419{
1420        struct rpc_task *task;
1421        int priority = flush_task_priority(how);
1422        struct rpc_message msg = {
1423                .rpc_argp = &data->args,
1424                .rpc_resp = &data->res,
1425                .rpc_cred = data->cred,
1426        };
1427        struct rpc_task_setup task_setup_data = {
1428                .task = &data->task,
1429                .rpc_client = clnt,
1430                .rpc_message = &msg,
1431                .callback_ops = call_ops,
1432                .callback_data = data,
1433                .workqueue = nfsiod_workqueue,
1434                .flags = RPC_TASK_ASYNC | flags,
1435                .priority = priority,
1436        };
1437        /* Set up the initial task struct.  */
1438        NFS_PROTO(data->inode)->commit_setup(data, &msg);
1439
1440        dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
1441
1442        task = rpc_run_task(&task_setup_data);
1443        if (IS_ERR(task))
1444                return PTR_ERR(task);
1445        if (how & FLUSH_SYNC)
1446                rpc_wait_for_completion_task(task);
1447        rpc_put_task(task);
1448        return 0;
1449}
1450EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1451
1452/*
1453 * Set up the argument/result storage required for the RPC call.
1454 */
1455void nfs_init_commit(struct nfs_commit_data *data,
1456                     struct list_head *head,
1457                     struct pnfs_layout_segment *lseg,
1458                     struct nfs_commit_info *cinfo)
1459{
1460        struct nfs_page *first = nfs_list_entry(head->next);
1461        struct inode *inode = first->wb_context->dentry->d_inode;
1462
1463        /* Set up the RPC argument and reply structs
1464         * NB: take care not to mess about with data->commit et al. */
1465
1466        list_splice_init(head, &data->pages);
1467
1468        data->inode       = inode;
1469        data->cred        = first->wb_context->cred;
1470        data->lseg        = lseg; /* reference transferred */
1471        data->mds_ops     = &nfs_commit_ops;
1472        data->completion_ops = cinfo->completion_ops;
1473        data->dreq        = cinfo->dreq;
1474
1475        data->args.fh     = NFS_FH(data->inode);
1476        /* Note: we always request a commit of the entire inode */
1477        data->args.offset = 0;
1478        data->args.count  = 0;
1479        data->context     = get_nfs_open_context(first->wb_context);
1480        data->res.fattr   = &data->fattr;
1481        data->res.verf    = &data->verf;
1482        nfs_fattr_init(&data->fattr);
1483}
1484EXPORT_SYMBOL_GPL(nfs_init_commit);
1485
1486void nfs_retry_commit(struct list_head *page_list,
1487                      struct pnfs_layout_segment *lseg,
1488                      struct nfs_commit_info *cinfo)
1489{
1490        struct nfs_page *req;
1491
1492        while (!list_empty(page_list)) {
1493                req = nfs_list_entry(page_list->next);
1494                nfs_list_remove_request(req);
1495                nfs_mark_request_commit(req, lseg, cinfo);
1496                if (!cinfo->dreq) {
1497                        dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1498                        dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
1499                                     BDI_RECLAIMABLE);
1500                }
1501                nfs_unlock_and_release_request(req);
1502        }
1503}
1504EXPORT_SYMBOL_GPL(nfs_retry_commit);
1505
1506/*
1507 * Commit dirty pages
1508 */
1509static int
1510nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1511                struct nfs_commit_info *cinfo)
1512{
1513        struct nfs_commit_data  *data;
1514
1515        data = nfs_commitdata_alloc();
1516
1517        if (!data)
1518                goto out_bad;
1519
1520        /* Set up the argument struct */
1521        nfs_init_commit(data, head, NULL, cinfo);
1522        atomic_inc(&cinfo->mds->rpcs_out);
1523        return nfs_initiate_commit(NFS_CLIENT(inode), data, data->mds_ops,
1524                                   how, 0);
1525 out_bad:
1526        nfs_retry_commit(head, NULL, cinfo);
1527        cinfo->completion_ops->error_cleanup(NFS_I(inode));
1528        return -ENOMEM;
1529}
1530
1531/*
1532 * COMMIT call returned
1533 */
1534static void nfs_commit_done(struct rpc_task *task, void *calldata)
1535{
1536        struct nfs_commit_data  *data = calldata;
1537
1538        dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1539                                task->tk_pid, task->tk_status);
1540
1541        /* Call the NFS version-specific code */
1542        NFS_PROTO(data->inode)->commit_done(task, data);
1543}
1544
1545static void nfs_commit_release_pages(struct nfs_commit_data *data)
1546{
1547        struct nfs_page *req;
1548        int status = data->task.tk_status;
1549        struct nfs_commit_info cinfo;
1550
1551        while (!list_empty(&data->pages)) {
1552                req = nfs_list_entry(data->pages.next);
1553                nfs_list_remove_request(req);
1554                nfs_clear_page_commit(req->wb_page);
1555
1556                dprintk("NFS:       commit (%s/%lld %d@%lld)",
1557                        req->wb_context->dentry->d_sb->s_id,
1558                        (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1559                        req->wb_bytes,
1560                        (long long)req_offset(req));
1561                if (status < 0) {
1562                        nfs_context_set_write_error(req->wb_context, status);
1563                        nfs_inode_remove_request(req);
1564                        dprintk(", error = %d\n", status);
1565                        goto next;
1566                }
1567
1568                /* Okay, COMMIT succeeded, apparently. Check the verifier
1569                 * returned by the server against all stored verfs. */
1570                if (!memcmp(&req->wb_verf, &data->verf.verifier, sizeof(req->wb_verf))) {
1571                        /* We have a match */
1572                        nfs_inode_remove_request(req);
1573                        dprintk(" OK\n");
1574                        goto next;
1575                }
1576                /* We have a mismatch. Write the page again */
1577                dprintk(" mismatch\n");
1578                nfs_mark_request_dirty(req);
1579        next:
1580                nfs_unlock_and_release_request(req);
1581        }
1582        nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1583        if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
1584                nfs_commit_clear_lock(NFS_I(data->inode));
1585}
1586
1587static void nfs_commit_release(void *calldata)
1588{
1589        struct nfs_commit_data *data = calldata;
1590
1591        data->completion_ops->completion(data);
1592        nfs_commitdata_release(calldata);
1593}
1594
1595static const struct rpc_call_ops nfs_commit_ops = {
1596        .rpc_call_prepare = nfs_commit_prepare,
1597        .rpc_call_done = nfs_commit_done,
1598        .rpc_release = nfs_commit_release,
1599};
1600
1601static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1602        .completion = nfs_commit_release_pages,
1603        .error_cleanup = nfs_commit_clear_lock,
1604};
1605
1606int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1607                            int how, struct nfs_commit_info *cinfo)
1608{
1609        int status;
1610
1611        status = pnfs_commit_list(inode, head, how, cinfo);
1612        if (status == PNFS_NOT_ATTEMPTED)
1613                status = nfs_commit_list(inode, head, how, cinfo);
1614        return status;
1615}
1616
1617int nfs_commit_inode(struct inode *inode, int how)
1618{
1619        LIST_HEAD(head);
1620        struct nfs_commit_info cinfo;
1621        int may_wait = how & FLUSH_SYNC;
1622        int res;
1623
1624        res = nfs_commit_set_lock(NFS_I(inode), may_wait);
1625        if (res <= 0)
1626                goto out_mark_dirty;
1627        nfs_init_cinfo_from_inode(&cinfo, inode);
1628        res = nfs_scan_commit(inode, &head, &cinfo);
1629        if (res) {
1630                int error;
1631
1632                error = nfs_generic_commit_list(inode, &head, how, &cinfo);
1633                if (error < 0)
1634                        return error;
1635                if (!may_wait)
1636                        goto out_mark_dirty;
1637                error = wait_on_bit(&NFS_I(inode)->flags,
1638                                NFS_INO_COMMIT,
1639                                nfs_wait_bit_killable,
1640                                TASK_KILLABLE);
1641                if (error < 0)
1642                        return error;
1643        } else
1644                nfs_commit_clear_lock(NFS_I(inode));
1645        return res;
1646        /* Note: If we exit without ensuring that the commit is complete,
1647         * we must mark the inode as dirty. Otherwise, future calls to
1648         * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
1649         * that the data is on the disk.
1650         */
1651out_mark_dirty:
1652        __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1653        return res;
1654}
1655
1656static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1657{
1658        struct nfs_inode *nfsi = NFS_I(inode);
1659        int flags = FLUSH_SYNC;
1660        int ret = 0;
1661
1662        /* no commits means nothing needs to be done */
1663        if (!nfsi->commit_info.ncommit)
1664                return ret;
1665
1666        if (wbc->sync_mode == WB_SYNC_NONE) {
1667                /* Don't commit yet if this is a non-blocking flush and there
1668                 * are a lot of outstanding writes for this mapping.
1669                 */
1670                if (nfsi->commit_info.ncommit <= (nfsi->npages >> 1))
1671                        goto out_mark_dirty;
1672
1673                /* don't wait for the COMMIT response */
1674                flags = 0;
1675        }
1676
1677        ret = nfs_commit_inode(inode, flags);
1678        if (ret >= 0) {
1679                if (wbc->sync_mode == WB_SYNC_NONE) {
1680                        if (ret < wbc->nr_to_write)
1681                                wbc->nr_to_write -= ret;
1682                        else
1683                                wbc->nr_to_write = 0;
1684                }
1685                return 0;
1686        }
1687out_mark_dirty:
1688        __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1689        return ret;
1690}
1691#else
1692static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
1693{
1694        return 0;
1695}
1696#endif
1697
1698int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1699{
1700        return nfs_commit_unstable_pages(inode, wbc);
1701}
1702EXPORT_SYMBOL_GPL(nfs_write_inode);
1703
1704/*
1705 * flush the inode to disk.
1706 */
1707int nfs_wb_all(struct inode *inode)
1708{
1709        struct writeback_control wbc = {
1710                .sync_mode = WB_SYNC_ALL,
1711                .nr_to_write = LONG_MAX,
1712                .range_start = 0,
1713                .range_end = LLONG_MAX,
1714        };
1715
1716        return sync_inode(inode, &wbc);
1717}
1718EXPORT_SYMBOL_GPL(nfs_wb_all);
1719
1720int nfs_wb_page_cancel(struct inode *inode, struct page *page)
1721{
1722        struct nfs_page *req;
1723        int ret = 0;
1724
1725        BUG_ON(!PageLocked(page));
1726        for (;;) {
1727                wait_on_page_writeback(page);
1728                req = nfs_page_find_request(page);
1729                if (req == NULL)
1730                        break;
1731                if (nfs_lock_request(req)) {
1732                        nfs_clear_request_commit(req);
1733                        nfs_inode_remove_request(req);
1734                        /*
1735                         * In case nfs_inode_remove_request has marked the
1736                         * page as being dirty
1737                         */
1738                        cancel_dirty_page(page, PAGE_CACHE_SIZE);
1739                        nfs_unlock_and_release_request(req);
1740                        break;
1741                }
1742                ret = nfs_wait_on_request(req);
1743                nfs_release_request(req);
1744                if (ret < 0)
1745                        break;
1746        }
1747        return ret;
1748}
1749
1750/*
1751 * Write back all requests on one page - we do this before reading it.
1752 */
1753int nfs_wb_page(struct inode *inode, struct page *page)
1754{
1755        loff_t range_start = page_file_offset(page);
1756        loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1757        struct writeback_control wbc = {
1758                .sync_mode = WB_SYNC_ALL,
1759                .nr_to_write = 0,
1760                .range_start = range_start,
1761                .range_end = range_end,
1762        };
1763        int ret;
1764
1765        for (;;) {
1766                wait_on_page_writeback(page);
1767                if (clear_page_dirty_for_io(page)) {
1768                        ret = nfs_writepage_locked(page, &wbc);
1769                        if (ret < 0)
1770                                goto out_error;
1771                        continue;
1772                }
1773                if (!PagePrivate(page))
1774                        break;
1775                ret = nfs_commit_inode(inode, FLUSH_SYNC);
1776                if (ret < 0)
1777                        goto out_error;
1778        }
1779        return 0;
1780out_error:
1781        return ret;
1782}
1783
1784#ifdef CONFIG_MIGRATION
1785int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
1786                struct page *page, enum migrate_mode mode)
1787{
1788        /*
1789         * If PagePrivate is set, then the page is currently associated with
1790         * an in-progress read or write request. Don't try to migrate it.
1791         *
1792         * FIXME: we could do this in principle, but we'll need a way to ensure
1793         *        that we can safely release the inode reference while holding
1794         *        the page lock.
1795         */
1796        if (PagePrivate(page))
1797                return -EBUSY;
1798
1799        nfs_fscache_release_page(page, GFP_KERNEL);
1800
1801        return migrate_page(mapping, newpage, page, mode);
1802}
1803#endif
1804
1805int __init nfs_init_writepagecache(void)
1806{
1807        nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1808                                             sizeof(struct nfs_write_header),
1809                                             0, SLAB_HWCACHE_ALIGN,
1810                                             NULL);
1811        if (nfs_wdata_cachep == NULL)
1812                return -ENOMEM;
1813
1814        nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1815                                                     nfs_wdata_cachep);
1816        if (nfs_wdata_mempool == NULL)
1817                goto out_destroy_write_cache;
1818
1819        nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
1820                                             sizeof(struct nfs_commit_data),
1821                                             0, SLAB_HWCACHE_ALIGN,
1822                                             NULL);
1823        if (nfs_cdata_cachep == NULL)
1824                goto out_destroy_write_mempool;
1825
1826        nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1827                                                      nfs_wdata_cachep);
1828        if (nfs_commit_mempool == NULL)
1829                goto out_destroy_commit_cache;
1830
1831        /*
1832         * NFS congestion size, scale with available memory.
1833         *
1834         *  64MB:    8192k
1835         * 128MB:   11585k
1836         * 256MB:   16384k
1837         * 512MB:   23170k
1838         *   1GB:   32768k
1839         *   2GB:   46340k
1840         *   4GB:   65536k
1841         *   8GB:   92681k
1842         *  16GB:  131072k
1843         *
1844         * This allows larger machines to have larger/more transfers.
1845         * Limit the default to 256M
1846         */
1847        nfs_congestion_kb = (16*int_sqrt(totalram_pages)) << (PAGE_SHIFT-10);
1848        if (nfs_congestion_kb > 256*1024)
1849                nfs_congestion_kb = 256*1024;
1850
1851        return 0;
1852
1853out_destroy_commit_cache:
1854        kmem_cache_destroy(nfs_cdata_cachep);
1855out_destroy_write_mempool:
1856        mempool_destroy(nfs_wdata_mempool);
1857out_destroy_write_cache:
1858        kmem_cache_destroy(nfs_wdata_cachep);
1859        return -ENOMEM;
1860}
1861
1862void nfs_destroy_writepagecache(void)
1863{
1864        mempool_destroy(nfs_commit_mempool);
1865        kmem_cache_destroy(nfs_cdata_cachep);
1866        mempool_destroy(nfs_wdata_mempool);
1867        kmem_cache_destroy(nfs_wdata_cachep);
1868}
1869
1870
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