linux/fs/nfs/read.c
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   1/*
   2 * linux/fs/nfs/read.c
   3 *
   4 * Block I/O for NFS
   5 *
   6 * Partial copy of Linus' read cache modifications to fs/nfs/file.c
   7 * modified for async RPC by okir@monad.swb.de
   8 */
   9
  10#include <linux/time.h>
  11#include <linux/kernel.h>
  12#include <linux/errno.h>
  13#include <linux/fcntl.h>
  14#include <linux/stat.h>
  15#include <linux/mm.h>
  16#include <linux/slab.h>
  17#include <linux/pagemap.h>
  18#include <linux/sunrpc/clnt.h>
  19#include <linux/nfs_fs.h>
  20#include <linux/nfs_page.h>
  21#include <linux/module.h>
  22
  23#include "nfs4_fs.h"
  24#include "internal.h"
  25#include "iostat.h"
  26#include "fscache.h"
  27
  28#define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  29
  30static const struct nfs_pageio_ops nfs_pageio_read_ops;
  31static const struct rpc_call_ops nfs_read_common_ops;
  32static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
  33
  34static struct kmem_cache *nfs_rdata_cachep;
  35
  36struct nfs_read_header *nfs_readhdr_alloc(void)
  37{
  38        struct nfs_read_header *rhdr;
  39
  40        rhdr = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
  41        if (rhdr) {
  42                struct nfs_pgio_header *hdr = &rhdr->header;
  43
  44                INIT_LIST_HEAD(&hdr->pages);
  45                INIT_LIST_HEAD(&hdr->rpc_list);
  46                spin_lock_init(&hdr->lock);
  47                atomic_set(&hdr->refcnt, 0);
  48        }
  49        return rhdr;
  50}
  51EXPORT_SYMBOL_GPL(nfs_readhdr_alloc);
  52
  53static struct nfs_read_data *nfs_readdata_alloc(struct nfs_pgio_header *hdr,
  54                                                unsigned int pagecount)
  55{
  56        struct nfs_read_data *data, *prealloc;
  57
  58        prealloc = &container_of(hdr, struct nfs_read_header, header)->rpc_data;
  59        if (prealloc->header == NULL)
  60                data = prealloc;
  61        else
  62                data = kzalloc(sizeof(*data), GFP_KERNEL);
  63        if (!data)
  64                goto out;
  65
  66        if (nfs_pgarray_set(&data->pages, pagecount)) {
  67                data->header = hdr;
  68                atomic_inc(&hdr->refcnt);
  69        } else {
  70                if (data != prealloc)
  71                        kfree(data);
  72                data = NULL;
  73        }
  74out:
  75        return data;
  76}
  77
  78void nfs_readhdr_free(struct nfs_pgio_header *hdr)
  79{
  80        struct nfs_read_header *rhdr = container_of(hdr, struct nfs_read_header, header);
  81
  82        kmem_cache_free(nfs_rdata_cachep, rhdr);
  83}
  84EXPORT_SYMBOL_GPL(nfs_readhdr_free);
  85
  86void nfs_readdata_release(struct nfs_read_data *rdata)
  87{
  88        struct nfs_pgio_header *hdr = rdata->header;
  89        struct nfs_read_header *read_header = container_of(hdr, struct nfs_read_header, header);
  90
  91        put_nfs_open_context(rdata->args.context);
  92        if (rdata->pages.pagevec != rdata->pages.page_array)
  93                kfree(rdata->pages.pagevec);
  94        if (rdata == &read_header->rpc_data) {
  95                rdata->header = NULL;
  96                rdata = NULL;
  97        }
  98        if (atomic_dec_and_test(&hdr->refcnt))
  99                hdr->completion_ops->completion(hdr);
 100        /* Note: we only free the rpc_task after callbacks are done.
 101         * See the comment in rpc_free_task() for why
 102         */
 103        kfree(rdata);
 104}
 105EXPORT_SYMBOL_GPL(nfs_readdata_release);
 106
 107static
 108int nfs_return_empty_page(struct page *page)
 109{
 110        zero_user(page, 0, PAGE_CACHE_SIZE);
 111        SetPageUptodate(page);
 112        unlock_page(page);
 113        return 0;
 114}
 115
 116void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
 117                              struct inode *inode,
 118                              const struct nfs_pgio_completion_ops *compl_ops)
 119{
 120        nfs_pageio_init(pgio, inode, &nfs_pageio_read_ops, compl_ops,
 121                        NFS_SERVER(inode)->rsize, 0);
 122}
 123EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
 124
 125void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
 126{
 127        pgio->pg_ops = &nfs_pageio_read_ops;
 128        pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
 129}
 130EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 131
 132int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
 133                       struct page *page)
 134{
 135        struct nfs_page *new;
 136        unsigned int len;
 137        struct nfs_pageio_descriptor pgio;
 138
 139        len = nfs_page_length(page);
 140        if (len == 0)
 141                return nfs_return_empty_page(page);
 142        new = nfs_create_request(ctx, inode, page, 0, len);
 143        if (IS_ERR(new)) {
 144                unlock_page(page);
 145                return PTR_ERR(new);
 146        }
 147        if (len < PAGE_CACHE_SIZE)
 148                zero_user_segment(page, len, PAGE_CACHE_SIZE);
 149
 150        NFS_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
 151        nfs_pageio_add_request(&pgio, new);
 152        nfs_pageio_complete(&pgio);
 153        NFS_I(inode)->read_io += pgio.pg_bytes_written;
 154        return 0;
 155}
 156
 157static void nfs_readpage_release(struct nfs_page *req)
 158{
 159        struct inode *d_inode = req->wb_context->dentry->d_inode;
 160
 161        if (PageUptodate(req->wb_page))
 162                nfs_readpage_to_fscache(d_inode, req->wb_page, 0);
 163
 164        unlock_page(req->wb_page);
 165
 166        dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",
 167                        req->wb_context->dentry->d_inode->i_sb->s_id,
 168                        (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
 169                        req->wb_bytes,
 170                        (long long)req_offset(req));
 171        nfs_release_request(req);
 172}
 173
 174/* Note io was page aligned */
 175static void nfs_read_completion(struct nfs_pgio_header *hdr)
 176{
 177        unsigned long bytes = 0;
 178
 179        if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 180                goto out;
 181        while (!list_empty(&hdr->pages)) {
 182                struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 183                struct page *page = req->wb_page;
 184
 185                if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 186                        if (bytes > hdr->good_bytes)
 187                                zero_user(page, 0, PAGE_SIZE);
 188                        else if (hdr->good_bytes - bytes < PAGE_SIZE)
 189                                zero_user_segment(page,
 190                                        hdr->good_bytes & ~PAGE_MASK,
 191                                        PAGE_SIZE);
 192                }
 193                bytes += req->wb_bytes;
 194                if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 195                        if (bytes <= hdr->good_bytes)
 196                                SetPageUptodate(page);
 197                } else
 198                        SetPageUptodate(page);
 199                nfs_list_remove_request(req);
 200                nfs_readpage_release(req);
 201        }
 202out:
 203        hdr->release(hdr);
 204}
 205
 206int nfs_initiate_read(struct rpc_clnt *clnt,
 207                      struct nfs_read_data *data,
 208                      const struct rpc_call_ops *call_ops, int flags)
 209{
 210        struct inode *inode = data->header->inode;
 211        int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
 212        struct rpc_task *task;
 213        struct rpc_message msg = {
 214                .rpc_argp = &data->args,
 215                .rpc_resp = &data->res,
 216                .rpc_cred = data->header->cred,
 217        };
 218        struct rpc_task_setup task_setup_data = {
 219                .task = &data->task,
 220                .rpc_client = clnt,
 221                .rpc_message = &msg,
 222                .callback_ops = call_ops,
 223                .callback_data = data,
 224                .workqueue = nfsiod_workqueue,
 225                .flags = RPC_TASK_ASYNC | swap_flags | flags,
 226        };
 227
 228        /* Set up the initial task struct. */
 229        NFS_PROTO(inode)->read_setup(data, &msg);
 230
 231        dprintk("NFS: %5u initiated read call (req %s/%lld, %u bytes @ "
 232                        "offset %llu)\n",
 233                        data->task.tk_pid,
 234                        inode->i_sb->s_id,
 235                        (long long)NFS_FILEID(inode),
 236                        data->args.count,
 237                        (unsigned long long)data->args.offset);
 238
 239        task = rpc_run_task(&task_setup_data);
 240        if (IS_ERR(task))
 241                return PTR_ERR(task);
 242        rpc_put_task(task);
 243        return 0;
 244}
 245EXPORT_SYMBOL_GPL(nfs_initiate_read);
 246
 247/*
 248 * Set up the NFS read request struct
 249 */
 250static void nfs_read_rpcsetup(struct nfs_read_data *data,
 251                unsigned int count, unsigned int offset)
 252{
 253        struct nfs_page *req = data->header->req;
 254
 255        data->args.fh     = NFS_FH(data->header->inode);
 256        data->args.offset = req_offset(req) + offset;
 257        data->args.pgbase = req->wb_pgbase + offset;
 258        data->args.pages  = data->pages.pagevec;
 259        data->args.count  = count;
 260        data->args.context = get_nfs_open_context(req->wb_context);
 261        data->args.lock_context = req->wb_lock_context;
 262
 263        data->res.fattr   = &data->fattr;
 264        data->res.count   = count;
 265        data->res.eof     = 0;
 266        nfs_fattr_init(&data->fattr);
 267}
 268
 269static int nfs_do_read(struct nfs_read_data *data,
 270                const struct rpc_call_ops *call_ops)
 271{
 272        struct inode *inode = data->header->inode;
 273
 274        return nfs_initiate_read(NFS_CLIENT(inode), data, call_ops, 0);
 275}
 276
 277static int
 278nfs_do_multiple_reads(struct list_head *head,
 279                const struct rpc_call_ops *call_ops)
 280{
 281        struct nfs_read_data *data;
 282        int ret = 0;
 283
 284        while (!list_empty(head)) {
 285                int ret2;
 286
 287                data = list_first_entry(head, struct nfs_read_data, list);
 288                list_del_init(&data->list);
 289
 290                ret2 = nfs_do_read(data, call_ops);
 291                if (ret == 0)
 292                        ret = ret2;
 293        }
 294        return ret;
 295}
 296
 297static void
 298nfs_async_read_error(struct list_head *head)
 299{
 300        struct nfs_page *req;
 301
 302        while (!list_empty(head)) {
 303                req = nfs_list_entry(head->next);
 304                nfs_list_remove_request(req);
 305                nfs_readpage_release(req);
 306        }
 307}
 308
 309static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 310        .error_cleanup = nfs_async_read_error,
 311        .completion = nfs_read_completion,
 312};
 313
 314static void nfs_pagein_error(struct nfs_pageio_descriptor *desc,
 315                struct nfs_pgio_header *hdr)
 316{
 317        set_bit(NFS_IOHDR_REDO, &hdr->flags);
 318        while (!list_empty(&hdr->rpc_list)) {
 319                struct nfs_read_data *data = list_first_entry(&hdr->rpc_list,
 320                                struct nfs_read_data, list);
 321                list_del(&data->list);
 322                nfs_readdata_release(data);
 323        }
 324        desc->pg_completion_ops->error_cleanup(&desc->pg_list);
 325}
 326
 327/*
 328 * Generate multiple requests to fill a single page.
 329 *
 330 * We optimize to reduce the number of read operations on the wire.  If we
 331 * detect that we're reading a page, or an area of a page, that is past the
 332 * end of file, we do not generate NFS read operations but just clear the
 333 * parts of the page that would have come back zero from the server anyway.
 334 *
 335 * We rely on the cached value of i_size to make this determination; another
 336 * client can fill pages on the server past our cached end-of-file, but we
 337 * won't see the new data until our attribute cache is updated.  This is more
 338 * or less conventional NFS client behavior.
 339 */
 340static int nfs_pagein_multi(struct nfs_pageio_descriptor *desc,
 341                            struct nfs_pgio_header *hdr)
 342{
 343        struct nfs_page *req = hdr->req;
 344        struct page *page = req->wb_page;
 345        struct nfs_read_data *data;
 346        size_t rsize = desc->pg_bsize, nbytes;
 347        unsigned int offset;
 348
 349        offset = 0;
 350        nbytes = desc->pg_count;
 351        do {
 352                size_t len = min(nbytes,rsize);
 353
 354                data = nfs_readdata_alloc(hdr, 1);
 355                if (!data) {
 356                        nfs_pagein_error(desc, hdr);
 357                        return -ENOMEM;
 358                }
 359                data->pages.pagevec[0] = page;
 360                nfs_read_rpcsetup(data, len, offset);
 361                list_add(&data->list, &hdr->rpc_list);
 362                nbytes -= len;
 363                offset += len;
 364        } while (nbytes != 0);
 365
 366        nfs_list_remove_request(req);
 367        nfs_list_add_request(req, &hdr->pages);
 368        desc->pg_rpc_callops = &nfs_read_common_ops;
 369        return 0;
 370}
 371
 372static int nfs_pagein_one(struct nfs_pageio_descriptor *desc,
 373                          struct nfs_pgio_header *hdr)
 374{
 375        struct nfs_page         *req;
 376        struct page             **pages;
 377        struct nfs_read_data    *data;
 378        struct list_head *head = &desc->pg_list;
 379
 380        data = nfs_readdata_alloc(hdr, nfs_page_array_len(desc->pg_base,
 381                                                          desc->pg_count));
 382        if (!data) {
 383                nfs_pagein_error(desc, hdr);
 384                return -ENOMEM;
 385        }
 386
 387        pages = data->pages.pagevec;
 388        while (!list_empty(head)) {
 389                req = nfs_list_entry(head->next);
 390                nfs_list_remove_request(req);
 391                nfs_list_add_request(req, &hdr->pages);
 392                *pages++ = req->wb_page;
 393        }
 394
 395        nfs_read_rpcsetup(data, desc->pg_count, 0);
 396        list_add(&data->list, &hdr->rpc_list);
 397        desc->pg_rpc_callops = &nfs_read_common_ops;
 398        return 0;
 399}
 400
 401int nfs_generic_pagein(struct nfs_pageio_descriptor *desc,
 402                       struct nfs_pgio_header *hdr)
 403{
 404        if (desc->pg_bsize < PAGE_CACHE_SIZE)
 405                return nfs_pagein_multi(desc, hdr);
 406        return nfs_pagein_one(desc, hdr);
 407}
 408EXPORT_SYMBOL_GPL(nfs_generic_pagein);
 409
 410static int nfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
 411{
 412        struct nfs_read_header *rhdr;
 413        struct nfs_pgio_header *hdr;
 414        int ret;
 415
 416        rhdr = nfs_readhdr_alloc();
 417        if (!rhdr) {
 418                desc->pg_completion_ops->error_cleanup(&desc->pg_list);
 419                return -ENOMEM;
 420        }
 421        hdr = &rhdr->header;
 422        nfs_pgheader_init(desc, hdr, nfs_readhdr_free);
 423        atomic_inc(&hdr->refcnt);
 424        ret = nfs_generic_pagein(desc, hdr);
 425        if (ret == 0)
 426                ret = nfs_do_multiple_reads(&hdr->rpc_list,
 427                                            desc->pg_rpc_callops);
 428        if (atomic_dec_and_test(&hdr->refcnt))
 429                hdr->completion_ops->completion(hdr);
 430        return ret;
 431}
 432
 433static const struct nfs_pageio_ops nfs_pageio_read_ops = {
 434        .pg_test = nfs_generic_pg_test,
 435        .pg_doio = nfs_generic_pg_readpages,
 436};
 437
 438/*
 439 * This is the callback from RPC telling us whether a reply was
 440 * received or some error occurred (timeout or socket shutdown).
 441 */
 442int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
 443{
 444        struct inode *inode = data->header->inode;
 445        int status;
 446
 447        dprintk("NFS: %s: %5u, (status %d)\n", __func__, task->tk_pid,
 448                        task->tk_status);
 449
 450        status = NFS_PROTO(inode)->read_done(task, data);
 451        if (status != 0)
 452                return status;
 453
 454        nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, data->res.count);
 455
 456        if (task->tk_status == -ESTALE) {
 457                set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
 458                nfs_mark_for_revalidate(inode);
 459        }
 460        return 0;
 461}
 462
 463static void nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
 464{
 465        struct nfs_readargs *argp = &data->args;
 466        struct nfs_readres *resp = &data->res;
 467
 468        /* This is a short read! */
 469        nfs_inc_stats(data->header->inode, NFSIOS_SHORTREAD);
 470        /* Has the server at least made some progress? */
 471        if (resp->count == 0) {
 472                nfs_set_pgio_error(data->header, -EIO, argp->offset);
 473                return;
 474        }
 475        /* Yes, so retry the read at the end of the data */
 476        data->mds_offset += resp->count;
 477        argp->offset += resp->count;
 478        argp->pgbase += resp->count;
 479        argp->count -= resp->count;
 480        rpc_restart_call_prepare(task);
 481}
 482
 483static void nfs_readpage_result_common(struct rpc_task *task, void *calldata)
 484{
 485        struct nfs_read_data *data = calldata;
 486        struct nfs_pgio_header *hdr = data->header;
 487
 488        /* Note the only returns of nfs_readpage_result are 0 and -EAGAIN */
 489        if (nfs_readpage_result(task, data) != 0)
 490                return;
 491        if (task->tk_status < 0)
 492                nfs_set_pgio_error(hdr, task->tk_status, data->args.offset);
 493        else if (data->res.eof) {
 494                loff_t bound;
 495
 496                bound = data->args.offset + data->res.count;
 497                spin_lock(&hdr->lock);
 498                if (bound < hdr->io_start + hdr->good_bytes) {
 499                        set_bit(NFS_IOHDR_EOF, &hdr->flags);
 500                        clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
 501                        hdr->good_bytes = bound - hdr->io_start;
 502                }
 503                spin_unlock(&hdr->lock);
 504        } else if (data->res.count != data->args.count)
 505                nfs_readpage_retry(task, data);
 506}
 507
 508static void nfs_readpage_release_common(void *calldata)
 509{
 510        nfs_readdata_release(calldata);
 511}
 512
 513void nfs_read_prepare(struct rpc_task *task, void *calldata)
 514{
 515        struct nfs_read_data *data = calldata;
 516        NFS_PROTO(data->header->inode)->read_rpc_prepare(task, data);
 517}
 518
 519static const struct rpc_call_ops nfs_read_common_ops = {
 520        .rpc_call_prepare = nfs_read_prepare,
 521        .rpc_call_done = nfs_readpage_result_common,
 522        .rpc_release = nfs_readpage_release_common,
 523};
 524
 525/*
 526 * Read a page over NFS.
 527 * We read the page synchronously in the following case:
 528 *  -   The error flag is set for this page. This happens only when a
 529 *      previous async read operation failed.
 530 */
 531int nfs_readpage(struct file *file, struct page *page)
 532{
 533        struct nfs_open_context *ctx;
 534        struct inode *inode = page_file_mapping(page)->host;
 535        int             error;
 536
 537        dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
 538                page, PAGE_CACHE_SIZE, page_file_index(page));
 539        nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
 540        nfs_add_stats(inode, NFSIOS_READPAGES, 1);
 541
 542        /*
 543         * Try to flush any pending writes to the file..
 544         *
 545         * NOTE! Because we own the page lock, there cannot
 546         * be any new pending writes generated at this point
 547         * for this page (other pages can be written to).
 548         */
 549        error = nfs_wb_page(inode, page);
 550        if (error)
 551                goto out_unlock;
 552        if (PageUptodate(page))
 553                goto out_unlock;
 554
 555        error = -ESTALE;
 556        if (NFS_STALE(inode))
 557                goto out_unlock;
 558
 559        if (file == NULL) {
 560                error = -EBADF;
 561                ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 562                if (ctx == NULL)
 563                        goto out_unlock;
 564        } else
 565                ctx = get_nfs_open_context(nfs_file_open_context(file));
 566
 567        if (!IS_SYNC(inode)) {
 568                error = nfs_readpage_from_fscache(ctx, inode, page);
 569                if (error == 0)
 570                        goto out;
 571        }
 572
 573        error = nfs_readpage_async(ctx, inode, page);
 574
 575out:
 576        put_nfs_open_context(ctx);
 577        return error;
 578out_unlock:
 579        unlock_page(page);
 580        return error;
 581}
 582
 583struct nfs_readdesc {
 584        struct nfs_pageio_descriptor *pgio;
 585        struct nfs_open_context *ctx;
 586};
 587
 588static int
 589readpage_async_filler(void *data, struct page *page)
 590{
 591        struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
 592        struct inode *inode = page_file_mapping(page)->host;
 593        struct nfs_page *new;
 594        unsigned int len;
 595        int error;
 596
 597        len = nfs_page_length(page);
 598        if (len == 0)
 599                return nfs_return_empty_page(page);
 600
 601        new = nfs_create_request(desc->ctx, inode, page, 0, len);
 602        if (IS_ERR(new))
 603                goto out_error;
 604
 605        if (len < PAGE_CACHE_SIZE)
 606                zero_user_segment(page, len, PAGE_CACHE_SIZE);
 607        if (!nfs_pageio_add_request(desc->pgio, new)) {
 608                error = desc->pgio->pg_error;
 609                goto out_unlock;
 610        }
 611        return 0;
 612out_error:
 613        error = PTR_ERR(new);
 614out_unlock:
 615        unlock_page(page);
 616        return error;
 617}
 618
 619int nfs_readpages(struct file *filp, struct address_space *mapping,
 620                struct list_head *pages, unsigned nr_pages)
 621{
 622        struct nfs_pageio_descriptor pgio;
 623        struct nfs_readdesc desc = {
 624                .pgio = &pgio,
 625        };
 626        struct inode *inode = mapping->host;
 627        unsigned long npages;
 628        int ret = -ESTALE;
 629
 630        dprintk("NFS: nfs_readpages (%s/%Ld %d)\n",
 631                        inode->i_sb->s_id,
 632                        (long long)NFS_FILEID(inode),
 633                        nr_pages);
 634        nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 635
 636        if (NFS_STALE(inode))
 637                goto out;
 638
 639        if (filp == NULL) {
 640                desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 641                if (desc.ctx == NULL)
 642                        return -EBADF;
 643        } else
 644                desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
 645
 646        /* attempt to read as many of the pages as possible from the cache
 647         * - this returns -ENOBUFS immediately if the cookie is negative
 648         */
 649        ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
 650                                         pages, &nr_pages);
 651        if (ret == 0)
 652                goto read_complete; /* all pages were read */
 653
 654        NFS_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
 655
 656        ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
 657
 658        nfs_pageio_complete(&pgio);
 659        NFS_I(inode)->read_io += pgio.pg_bytes_written;
 660        npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 661        nfs_add_stats(inode, NFSIOS_READPAGES, npages);
 662read_complete:
 663        put_nfs_open_context(desc.ctx);
 664out:
 665        return ret;
 666}
 667
 668int __init nfs_init_readpagecache(void)
 669{
 670        nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
 671                                             sizeof(struct nfs_read_header),
 672                                             0, SLAB_HWCACHE_ALIGN,
 673                                             NULL);
 674        if (nfs_rdata_cachep == NULL)
 675                return -ENOMEM;
 676
 677        return 0;
 678}
 679
 680void nfs_destroy_readpagecache(void)
 681{
 682        kmem_cache_destroy(nfs_rdata_cachep);
 683}
 684
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