linux/fs/nfs/direct.c
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   1/*
   2 * linux/fs/nfs/direct.c
   3 *
   4 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
   5 *
   6 * High-performance uncached I/O for the Linux NFS client
   7 *
   8 * There are important applications whose performance or correctness
   9 * depends on uncached access to file data.  Database clusters
  10 * (multiple copies of the same instance running on separate hosts)
  11 * implement their own cache coherency protocol that subsumes file
  12 * system cache protocols.  Applications that process datasets
  13 * considerably larger than the client's memory do not always benefit
  14 * from a local cache.  A streaming video server, for instance, has no
  15 * need to cache the contents of a file.
  16 *
  17 * When an application requests uncached I/O, all read and write requests
  18 * are made directly to the server; data stored or fetched via these
  19 * requests is not cached in the Linux page cache.  The client does not
  20 * correct unaligned requests from applications.  All requested bytes are
  21 * held on permanent storage before a direct write system call returns to
  22 * an application.
  23 *
  24 * Solaris implements an uncached I/O facility called directio() that
  25 * is used for backups and sequential I/O to very large files.  Solaris
  26 * also supports uncaching whole NFS partitions with "-o forcedirectio,"
  27 * an undocumented mount option.
  28 *
  29 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
  30 * help from Andrew Morton.
  31 *
  32 * 18 Dec 2001  Initial implementation for 2.4  --cel
  33 * 08 Jul 2002  Version for 2.4.19, with bug fixes --trondmy
  34 * 08 Jun 2003  Port to 2.5 APIs  --cel
  35 * 31 Mar 2004  Handle direct I/O without VFS support  --cel
  36 * 15 Sep 2004  Parallel async reads  --cel
  37 * 04 May 2005  support O_DIRECT with aio  --cel
  38 *
  39 */
  40
  41#include <linux/errno.h>
  42#include <linux/sched.h>
  43#include <linux/kernel.h>
  44#include <linux/file.h>
  45#include <linux/pagemap.h>
  46#include <linux/kref.h>
  47#include <linux/slab.h>
  48#include <linux/task_io_accounting_ops.h>
  49
  50#include <linux/nfs_fs.h>
  51#include <linux/nfs_page.h>
  52#include <linux/sunrpc/clnt.h>
  53
  54#include <asm/system.h>
  55#include <asm/uaccess.h>
  56#include <linux/atomic.h>
  57
  58#include "internal.h"
  59#include "iostat.h"
  60
  61#define NFSDBG_FACILITY         NFSDBG_VFS
  62
  63static struct kmem_cache *nfs_direct_cachep;
  64
  65/*
  66 * This represents a set of asynchronous requests that we're waiting on
  67 */
  68struct nfs_direct_req {
  69        struct kref             kref;           /* release manager */
  70
  71        /* I/O parameters */
  72        struct nfs_open_context *ctx;           /* file open context info */
  73        struct nfs_lock_context *l_ctx;         /* Lock context info */
  74        struct kiocb *          iocb;           /* controlling i/o request */
  75        struct inode *          inode;          /* target file of i/o */
  76
  77        /* completion state */
  78        atomic_t                io_count;       /* i/os we're waiting for */
  79        spinlock_t              lock;           /* protect completion state */
  80        ssize_t                 count,          /* bytes actually processed */
  81                                error;          /* any reported error */
  82        struct completion       completion;     /* wait for i/o completion */
  83
  84        /* commit state */
  85        struct list_head        rewrite_list;   /* saved nfs_write_data structs */
  86        struct nfs_write_data * commit_data;    /* special write_data for commits */
  87        int                     flags;
  88#define NFS_ODIRECT_DO_COMMIT           (1)     /* an unstable reply was received */
  89#define NFS_ODIRECT_RESCHED_WRITES      (2)     /* write verification failed */
  90        struct nfs_writeverf    verf;           /* unstable write verifier */
  91};
  92
  93static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
  94static const struct rpc_call_ops nfs_write_direct_ops;
  95
  96static inline void get_dreq(struct nfs_direct_req *dreq)
  97{
  98        atomic_inc(&dreq->io_count);
  99}
 100
 101static inline int put_dreq(struct nfs_direct_req *dreq)
 102{
 103        return atomic_dec_and_test(&dreq->io_count);
 104}
 105
 106/**
 107 * nfs_direct_IO - NFS address space operation for direct I/O
 108 * @rw: direction (read or write)
 109 * @iocb: target I/O control block
 110 * @iov: array of vectors that define I/O buffer
 111 * @pos: offset in file to begin the operation
 112 * @nr_segs: size of iovec array
 113 *
 114 * The presence of this routine in the address space ops vector means
 115 * the NFS client supports direct I/O.  However, we shunt off direct
 116 * read and write requests before the VFS gets them, so this method
 117 * should never be called.
 118 */
 119ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
 120{
 121        dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
 122                        iocb->ki_filp->f_path.dentry->d_name.name,
 123                        (long long) pos, nr_segs);
 124
 125        return -EINVAL;
 126}
 127
 128static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
 129{
 130        unsigned int npages;
 131        unsigned int i;
 132
 133        if (count == 0)
 134                return;
 135        pages += (pgbase >> PAGE_SHIFT);
 136        npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 137        for (i = 0; i < npages; i++) {
 138                struct page *page = pages[i];
 139                if (!PageCompound(page))
 140                        set_page_dirty(page);
 141        }
 142}
 143
 144static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
 145{
 146        unsigned int i;
 147        for (i = 0; i < npages; i++)
 148                page_cache_release(pages[i]);
 149}
 150
 151static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
 152{
 153        struct nfs_direct_req *dreq;
 154
 155        dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
 156        if (!dreq)
 157                return NULL;
 158
 159        kref_init(&dreq->kref);
 160        kref_get(&dreq->kref);
 161        init_completion(&dreq->completion);
 162        INIT_LIST_HEAD(&dreq->rewrite_list);
 163        dreq->iocb = NULL;
 164        dreq->ctx = NULL;
 165        dreq->l_ctx = NULL;
 166        spin_lock_init(&dreq->lock);
 167        atomic_set(&dreq->io_count, 0);
 168        dreq->count = 0;
 169        dreq->error = 0;
 170        dreq->flags = 0;
 171
 172        return dreq;
 173}
 174
 175static void nfs_direct_req_free(struct kref *kref)
 176{
 177        struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
 178
 179        if (dreq->l_ctx != NULL)
 180                nfs_put_lock_context(dreq->l_ctx);
 181        if (dreq->ctx != NULL)
 182                put_nfs_open_context(dreq->ctx);
 183        kmem_cache_free(nfs_direct_cachep, dreq);
 184}
 185
 186static void nfs_direct_req_release(struct nfs_direct_req *dreq)
 187{
 188        kref_put(&dreq->kref, nfs_direct_req_free);
 189}
 190
 191/*
 192 * Collects and returns the final error value/byte-count.
 193 */
 194static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
 195{
 196        ssize_t result = -EIOCBQUEUED;
 197
 198        /* Async requests don't wait here */
 199        if (dreq->iocb)
 200                goto out;
 201
 202        result = wait_for_completion_killable(&dreq->completion);
 203
 204        if (!result)
 205                result = dreq->error;
 206        if (!result)
 207                result = dreq->count;
 208
 209out:
 210        return (ssize_t) result;
 211}
 212
 213/*
 214 * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
 215 * the iocb is still valid here if this is a synchronous request.
 216 */
 217static void nfs_direct_complete(struct nfs_direct_req *dreq)
 218{
 219        if (dreq->iocb) {
 220                long res = (long) dreq->error;
 221                if (!res)
 222                        res = (long) dreq->count;
 223                aio_complete(dreq->iocb, res, 0);
 224        }
 225        complete_all(&dreq->completion);
 226
 227        nfs_direct_req_release(dreq);
 228}
 229
 230/*
 231 * We must hold a reference to all the pages in this direct read request
 232 * until the RPCs complete.  This could be long *after* we are woken up in
 233 * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
 234 */
 235static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
 236{
 237        struct nfs_read_data *data = calldata;
 238
 239        nfs_readpage_result(task, data);
 240}
 241
 242static void nfs_direct_read_release(void *calldata)
 243{
 244
 245        struct nfs_read_data *data = calldata;
 246        struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 247        int status = data->task.tk_status;
 248
 249        spin_lock(&dreq->lock);
 250        if (unlikely(status < 0)) {
 251                dreq->error = status;
 252                spin_unlock(&dreq->lock);
 253        } else {
 254                dreq->count += data->res.count;
 255                spin_unlock(&dreq->lock);
 256                nfs_direct_dirty_pages(data->pagevec,
 257                                data->args.pgbase,
 258                                data->res.count);
 259        }
 260        nfs_direct_release_pages(data->pagevec, data->npages);
 261
 262        if (put_dreq(dreq))
 263                nfs_direct_complete(dreq);
 264        nfs_readdata_free(data);
 265}
 266
 267static const struct rpc_call_ops nfs_read_direct_ops = {
 268#if defined(CONFIG_NFS_V4_1)
 269        .rpc_call_prepare = nfs_read_prepare,
 270#endif /* CONFIG_NFS_V4_1 */
 271        .rpc_call_done = nfs_direct_read_result,
 272        .rpc_release = nfs_direct_read_release,
 273};
 274
 275/*
 276 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
 277 * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
 278 * bail and stop sending more reads.  Read length accounting is
 279 * handled automatically by nfs_direct_read_result().  Otherwise, if
 280 * no requests have been sent, just return an error.
 281 */
 282static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
 283                                                const struct iovec *iov,
 284                                                loff_t pos)
 285{
 286        struct nfs_open_context *ctx = dreq->ctx;
 287        struct inode *inode = ctx->dentry->d_inode;
 288        unsigned long user_addr = (unsigned long)iov->iov_base;
 289        size_t count = iov->iov_len;
 290        size_t rsize = NFS_SERVER(inode)->rsize;
 291        struct rpc_task *task;
 292        struct rpc_message msg = {
 293                .rpc_cred = ctx->cred,
 294        };
 295        struct rpc_task_setup task_setup_data = {
 296                .rpc_client = NFS_CLIENT(inode),
 297                .rpc_message = &msg,
 298                .callback_ops = &nfs_read_direct_ops,
 299                .workqueue = nfsiod_workqueue,
 300                .flags = RPC_TASK_ASYNC,
 301        };
 302        unsigned int pgbase;
 303        int result;
 304        ssize_t started = 0;
 305
 306        do {
 307                struct nfs_read_data *data;
 308                size_t bytes;
 309
 310                pgbase = user_addr & ~PAGE_MASK;
 311                bytes = min(rsize,count);
 312
 313                result = -ENOMEM;
 314                data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
 315                if (unlikely(!data))
 316                        break;
 317
 318                down_read(&current->mm->mmap_sem);
 319                result = get_user_pages(current, current->mm, user_addr,
 320                                        data->npages, 1, 0, data->pagevec, NULL);
 321                up_read(&current->mm->mmap_sem);
 322                if (result < 0) {
 323                        nfs_readdata_free(data);
 324                        break;
 325                }
 326                if ((unsigned)result < data->npages) {
 327                        bytes = result * PAGE_SIZE;
 328                        if (bytes <= pgbase) {
 329                                nfs_direct_release_pages(data->pagevec, result);
 330                                nfs_readdata_free(data);
 331                                break;
 332                        }
 333                        bytes -= pgbase;
 334                        data->npages = result;
 335                }
 336
 337                get_dreq(dreq);
 338
 339                data->req = (struct nfs_page *) dreq;
 340                data->inode = inode;
 341                data->cred = msg.rpc_cred;
 342                data->args.fh = NFS_FH(inode);
 343                data->args.context = ctx;
 344                data->args.lock_context = dreq->l_ctx;
 345                data->args.offset = pos;
 346                data->args.pgbase = pgbase;
 347                data->args.pages = data->pagevec;
 348                data->args.count = bytes;
 349                data->res.fattr = &data->fattr;
 350                data->res.eof = 0;
 351                data->res.count = bytes;
 352                nfs_fattr_init(&data->fattr);
 353                msg.rpc_argp = &data->args;
 354                msg.rpc_resp = &data->res;
 355
 356                task_setup_data.task = &data->task;
 357                task_setup_data.callback_data = data;
 358                NFS_PROTO(inode)->read_setup(data, &msg);
 359
 360                task = rpc_run_task(&task_setup_data);
 361                if (IS_ERR(task))
 362                        break;
 363                rpc_put_task(task);
 364
 365                dprintk("NFS: %5u initiated direct read call "
 366                        "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
 367                                data->task.tk_pid,
 368                                inode->i_sb->s_id,
 369                                (long long)NFS_FILEID(inode),
 370                                bytes,
 371                                (unsigned long long)data->args.offset);
 372
 373                started += bytes;
 374                user_addr += bytes;
 375                pos += bytes;
 376                /* FIXME: Remove this unnecessary math from final patch */
 377                pgbase += bytes;
 378                pgbase &= ~PAGE_MASK;
 379                BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
 380
 381                count -= bytes;
 382        } while (count != 0);
 383
 384        if (started)
 385                return started;
 386        return result < 0 ? (ssize_t) result : -EFAULT;
 387}
 388
 389static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 390                                              const struct iovec *iov,
 391                                              unsigned long nr_segs,
 392                                              loff_t pos)
 393{
 394        ssize_t result = -EINVAL;
 395        size_t requested_bytes = 0;
 396        unsigned long seg;
 397
 398        get_dreq(dreq);
 399
 400        for (seg = 0; seg < nr_segs; seg++) {
 401                const struct iovec *vec = &iov[seg];
 402                result = nfs_direct_read_schedule_segment(dreq, vec, pos);
 403                if (result < 0)
 404                        break;
 405                requested_bytes += result;
 406                if ((size_t)result < vec->iov_len)
 407                        break;
 408                pos += vec->iov_len;
 409        }
 410
 411        /*
 412         * If no bytes were started, return the error, and let the
 413         * generic layer handle the completion.
 414         */
 415        if (requested_bytes == 0) {
 416                nfs_direct_req_release(dreq);
 417                return result < 0 ? result : -EIO;
 418        }
 419
 420        if (put_dreq(dreq))
 421                nfs_direct_complete(dreq);
 422        return 0;
 423}
 424
 425static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
 426                               unsigned long nr_segs, loff_t pos)
 427{
 428        ssize_t result = -ENOMEM;
 429        struct inode *inode = iocb->ki_filp->f_mapping->host;
 430        struct nfs_direct_req *dreq;
 431
 432        dreq = nfs_direct_req_alloc();
 433        if (dreq == NULL)
 434                goto out;
 435
 436        dreq->inode = inode;
 437        dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 438        dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
 439        if (dreq->l_ctx == NULL)
 440                goto out_release;
 441        if (!is_sync_kiocb(iocb))
 442                dreq->iocb = iocb;
 443
 444        result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
 445        if (!result)
 446                result = nfs_direct_wait(dreq);
 447out_release:
 448        nfs_direct_req_release(dreq);
 449out:
 450        return result;
 451}
 452
 453static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
 454{
 455        while (!list_empty(&dreq->rewrite_list)) {
 456                struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
 457                list_del(&data->pages);
 458                nfs_direct_release_pages(data->pagevec, data->npages);
 459                nfs_writedata_free(data);
 460        }
 461}
 462
 463#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 464static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 465{
 466        struct inode *inode = dreq->inode;
 467        struct list_head *p;
 468        struct nfs_write_data *data;
 469        struct rpc_task *task;
 470        struct rpc_message msg = {
 471                .rpc_cred = dreq->ctx->cred,
 472        };
 473        struct rpc_task_setup task_setup_data = {
 474                .rpc_client = NFS_CLIENT(inode),
 475                .rpc_message = &msg,
 476                .callback_ops = &nfs_write_direct_ops,
 477                .workqueue = nfsiod_workqueue,
 478                .flags = RPC_TASK_ASYNC,
 479        };
 480
 481        dreq->count = 0;
 482        get_dreq(dreq);
 483
 484        list_for_each(p, &dreq->rewrite_list) {
 485                data = list_entry(p, struct nfs_write_data, pages);
 486
 487                get_dreq(dreq);
 488
 489                /* Use stable writes */
 490                data->args.stable = NFS_FILE_SYNC;
 491
 492                /*
 493                 * Reset data->res.
 494                 */
 495                nfs_fattr_init(&data->fattr);
 496                data->res.count = data->args.count;
 497                memset(&data->verf, 0, sizeof(data->verf));
 498
 499                /*
 500                 * Reuse data->task; data->args should not have changed
 501                 * since the original request was sent.
 502                 */
 503                task_setup_data.task = &data->task;
 504                task_setup_data.callback_data = data;
 505                msg.rpc_argp = &data->args;
 506                msg.rpc_resp = &data->res;
 507                NFS_PROTO(inode)->write_setup(data, &msg);
 508
 509                /*
 510                 * We're called via an RPC callback, so BKL is already held.
 511                 */
 512                task = rpc_run_task(&task_setup_data);
 513                if (!IS_ERR(task))
 514                        rpc_put_task(task);
 515
 516                dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
 517                                data->task.tk_pid,
 518                                inode->i_sb->s_id,
 519                                (long long)NFS_FILEID(inode),
 520                                data->args.count,
 521                                (unsigned long long)data->args.offset);
 522        }
 523
 524        if (put_dreq(dreq))
 525                nfs_direct_write_complete(dreq, inode);
 526}
 527
 528static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
 529{
 530        struct nfs_write_data *data = calldata;
 531
 532        /* Call the NFS version-specific code */
 533        NFS_PROTO(data->inode)->commit_done(task, data);
 534}
 535
 536static void nfs_direct_commit_release(void *calldata)
 537{
 538        struct nfs_write_data *data = calldata;
 539        struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 540        int status = data->task.tk_status;
 541
 542        if (status < 0) {
 543                dprintk("NFS: %5u commit failed with error %d.\n",
 544                                data->task.tk_pid, status);
 545                dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 546        } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
 547                dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
 548                dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 549        }
 550
 551        dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
 552        nfs_direct_write_complete(dreq, data->inode);
 553        nfs_commit_free(data);
 554}
 555
 556static const struct rpc_call_ops nfs_commit_direct_ops = {
 557#if defined(CONFIG_NFS_V4_1)
 558        .rpc_call_prepare = nfs_write_prepare,
 559#endif /* CONFIG_NFS_V4_1 */
 560        .rpc_call_done = nfs_direct_commit_result,
 561        .rpc_release = nfs_direct_commit_release,
 562};
 563
 564static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 565{
 566        struct nfs_write_data *data = dreq->commit_data;
 567        struct rpc_task *task;
 568        struct rpc_message msg = {
 569                .rpc_argp = &data->args,
 570                .rpc_resp = &data->res,
 571                .rpc_cred = dreq->ctx->cred,
 572        };
 573        struct rpc_task_setup task_setup_data = {
 574                .task = &data->task,
 575                .rpc_client = NFS_CLIENT(dreq->inode),
 576                .rpc_message = &msg,
 577                .callback_ops = &nfs_commit_direct_ops,
 578                .callback_data = data,
 579                .workqueue = nfsiod_workqueue,
 580                .flags = RPC_TASK_ASYNC,
 581        };
 582
 583        data->inode = dreq->inode;
 584        data->cred = msg.rpc_cred;
 585
 586        data->args.fh = NFS_FH(data->inode);
 587        data->args.offset = 0;
 588        data->args.count = 0;
 589        data->args.context = dreq->ctx;
 590        data->args.lock_context = dreq->l_ctx;
 591        data->res.count = 0;
 592        data->res.fattr = &data->fattr;
 593        data->res.verf = &data->verf;
 594        nfs_fattr_init(&data->fattr);
 595
 596        NFS_PROTO(data->inode)->commit_setup(data, &msg);
 597
 598        /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
 599        dreq->commit_data = NULL;
 600
 601        dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
 602
 603        task = rpc_run_task(&task_setup_data);
 604        if (!IS_ERR(task))
 605                rpc_put_task(task);
 606}
 607
 608static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 609{
 610        int flags = dreq->flags;
 611
 612        dreq->flags = 0;
 613        switch (flags) {
 614                case NFS_ODIRECT_DO_COMMIT:
 615                        nfs_direct_commit_schedule(dreq);
 616                        break;
 617                case NFS_ODIRECT_RESCHED_WRITES:
 618                        nfs_direct_write_reschedule(dreq);
 619                        break;
 620                default:
 621                        if (dreq->commit_data != NULL)
 622                                nfs_commit_free(dreq->commit_data);
 623                        nfs_direct_free_writedata(dreq);
 624                        nfs_zap_mapping(inode, inode->i_mapping);
 625                        nfs_direct_complete(dreq);
 626        }
 627}
 628
 629static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
 630{
 631        dreq->commit_data = nfs_commitdata_alloc();
 632        if (dreq->commit_data != NULL)
 633                dreq->commit_data->req = (struct nfs_page *) dreq;
 634}
 635#else
 636static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
 637{
 638        dreq->commit_data = NULL;
 639}
 640
 641static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 642{
 643        nfs_direct_free_writedata(dreq);
 644        nfs_zap_mapping(inode, inode->i_mapping);
 645        nfs_direct_complete(dreq);
 646}
 647#endif
 648
 649static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
 650{
 651        struct nfs_write_data *data = calldata;
 652
 653        nfs_writeback_done(task, data);
 654}
 655
 656/*
 657 * NB: Return the value of the first error return code.  Subsequent
 658 *     errors after the first one are ignored.
 659 */
 660static void nfs_direct_write_release(void *calldata)
 661{
 662        struct nfs_write_data *data = calldata;
 663        struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 664        int status = data->task.tk_status;
 665
 666        spin_lock(&dreq->lock);
 667
 668        if (unlikely(status < 0)) {
 669                /* An error has occurred, so we should not commit */
 670                dreq->flags = 0;
 671                dreq->error = status;
 672        }
 673        if (unlikely(dreq->error != 0))
 674                goto out_unlock;
 675
 676        dreq->count += data->res.count;
 677
 678        if (data->res.verf->committed != NFS_FILE_SYNC) {
 679                switch (dreq->flags) {
 680                        case 0:
 681                                memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
 682                                dreq->flags = NFS_ODIRECT_DO_COMMIT;
 683                                break;
 684                        case NFS_ODIRECT_DO_COMMIT:
 685                                if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
 686                                        dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
 687                                        dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 688                                }
 689                }
 690        }
 691out_unlock:
 692        spin_unlock(&dreq->lock);
 693
 694        if (put_dreq(dreq))
 695                nfs_direct_write_complete(dreq, data->inode);
 696}
 697
 698static const struct rpc_call_ops nfs_write_direct_ops = {
 699#if defined(CONFIG_NFS_V4_1)
 700        .rpc_call_prepare = nfs_write_prepare,
 701#endif /* CONFIG_NFS_V4_1 */
 702        .rpc_call_done = nfs_direct_write_result,
 703        .rpc_release = nfs_direct_write_release,
 704};
 705
 706/*
 707 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
 708 * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
 709 * bail and stop sending more writes.  Write length accounting is
 710 * handled automatically by nfs_direct_write_result().  Otherwise, if
 711 * no requests have been sent, just return an error.
 712 */
 713static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
 714                                                 const struct iovec *iov,
 715                                                 loff_t pos, int sync)
 716{
 717        struct nfs_open_context *ctx = dreq->ctx;
 718        struct inode *inode = ctx->dentry->d_inode;
 719        unsigned long user_addr = (unsigned long)iov->iov_base;
 720        size_t count = iov->iov_len;
 721        struct rpc_task *task;
 722        struct rpc_message msg = {
 723                .rpc_cred = ctx->cred,
 724        };
 725        struct rpc_task_setup task_setup_data = {
 726                .rpc_client = NFS_CLIENT(inode),
 727                .rpc_message = &msg,
 728                .callback_ops = &nfs_write_direct_ops,
 729                .workqueue = nfsiod_workqueue,
 730                .flags = RPC_TASK_ASYNC,
 731        };
 732        size_t wsize = NFS_SERVER(inode)->wsize;
 733        unsigned int pgbase;
 734        int result;
 735        ssize_t started = 0;
 736
 737        do {
 738                struct nfs_write_data *data;
 739                size_t bytes;
 740
 741                pgbase = user_addr & ~PAGE_MASK;
 742                bytes = min(wsize,count);
 743
 744                result = -ENOMEM;
 745                data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
 746                if (unlikely(!data))
 747                        break;
 748
 749                down_read(&current->mm->mmap_sem);
 750                result = get_user_pages(current, current->mm, user_addr,
 751                                        data->npages, 0, 0, data->pagevec, NULL);
 752                up_read(&current->mm->mmap_sem);
 753                if (result < 0) {
 754                        nfs_writedata_free(data);
 755                        break;
 756                }
 757                if ((unsigned)result < data->npages) {
 758                        bytes = result * PAGE_SIZE;
 759                        if (bytes <= pgbase) {
 760                                nfs_direct_release_pages(data->pagevec, result);
 761                                nfs_writedata_free(data);
 762                                break;
 763                        }
 764                        bytes -= pgbase;
 765                        data->npages = result;
 766                }
 767
 768                get_dreq(dreq);
 769
 770                list_move_tail(&data->pages, &dreq->rewrite_list);
 771
 772                data->req = (struct nfs_page *) dreq;
 773                data->inode = inode;
 774                data->cred = msg.rpc_cred;
 775                data->args.fh = NFS_FH(inode);
 776                data->args.context = ctx;
 777                data->args.lock_context = dreq->l_ctx;
 778                data->args.offset = pos;
 779                data->args.pgbase = pgbase;
 780                data->args.pages = data->pagevec;
 781                data->args.count = bytes;
 782                data->args.stable = sync;
 783                data->res.fattr = &data->fattr;
 784                data->res.count = bytes;
 785                data->res.verf = &data->verf;
 786                nfs_fattr_init(&data->fattr);
 787
 788                task_setup_data.task = &data->task;
 789                task_setup_data.callback_data = data;
 790                msg.rpc_argp = &data->args;
 791                msg.rpc_resp = &data->res;
 792                NFS_PROTO(inode)->write_setup(data, &msg);
 793
 794                task = rpc_run_task(&task_setup_data);
 795                if (IS_ERR(task))
 796                        break;
 797                rpc_put_task(task);
 798
 799                dprintk("NFS: %5u initiated direct write call "
 800                        "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
 801                                data->task.tk_pid,
 802                                inode->i_sb->s_id,
 803                                (long long)NFS_FILEID(inode),
 804                                bytes,
 805                                (unsigned long long)data->args.offset);
 806
 807                started += bytes;
 808                user_addr += bytes;
 809                pos += bytes;
 810
 811                /* FIXME: Remove this useless math from the final patch */
 812                pgbase += bytes;
 813                pgbase &= ~PAGE_MASK;
 814                BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
 815
 816                count -= bytes;
 817        } while (count != 0);
 818
 819        if (started)
 820                return started;
 821        return result < 0 ? (ssize_t) result : -EFAULT;
 822}
 823
 824static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 825                                               const struct iovec *iov,
 826                                               unsigned long nr_segs,
 827                                               loff_t pos, int sync)
 828{
 829        ssize_t result = 0;
 830        size_t requested_bytes = 0;
 831        unsigned long seg;
 832
 833        get_dreq(dreq);
 834
 835        for (seg = 0; seg < nr_segs; seg++) {
 836                const struct iovec *vec = &iov[seg];
 837                result = nfs_direct_write_schedule_segment(dreq, vec,
 838                                                           pos, sync);
 839                if (result < 0)
 840                        break;
 841                requested_bytes += result;
 842                if ((size_t)result < vec->iov_len)
 843                        break;
 844                pos += vec->iov_len;
 845        }
 846
 847        /*
 848         * If no bytes were started, return the error, and let the
 849         * generic layer handle the completion.
 850         */
 851        if (requested_bytes == 0) {
 852                nfs_direct_req_release(dreq);
 853                return result < 0 ? result : -EIO;
 854        }
 855
 856        if (put_dreq(dreq))
 857                nfs_direct_write_complete(dreq, dreq->inode);
 858        return 0;
 859}
 860
 861static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
 862                                unsigned long nr_segs, loff_t pos,
 863                                size_t count)
 864{
 865        ssize_t result = -ENOMEM;
 866        struct inode *inode = iocb->ki_filp->f_mapping->host;
 867        struct nfs_direct_req *dreq;
 868        size_t wsize = NFS_SERVER(inode)->wsize;
 869        int sync = NFS_UNSTABLE;
 870
 871        dreq = nfs_direct_req_alloc();
 872        if (!dreq)
 873                goto out;
 874        nfs_alloc_commit_data(dreq);
 875
 876        if (dreq->commit_data == NULL || count <= wsize)
 877                sync = NFS_FILE_SYNC;
 878
 879        dreq->inode = inode;
 880        dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 881        dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
 882        if (dreq->l_ctx == NULL)
 883                goto out_release;
 884        if (!is_sync_kiocb(iocb))
 885                dreq->iocb = iocb;
 886
 887        result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
 888        if (!result)
 889                result = nfs_direct_wait(dreq);
 890out_release:
 891        nfs_direct_req_release(dreq);
 892out:
 893        return result;
 894}
 895
 896/**
 897 * nfs_file_direct_read - file direct read operation for NFS files
 898 * @iocb: target I/O control block
 899 * @iov: vector of user buffers into which to read data
 900 * @nr_segs: size of iov vector
 901 * @pos: byte offset in file where reading starts
 902 *
 903 * We use this function for direct reads instead of calling
 904 * generic_file_aio_read() in order to avoid gfar's check to see if
 905 * the request starts before the end of the file.  For that check
 906 * to work, we must generate a GETATTR before each direct read, and
 907 * even then there is a window between the GETATTR and the subsequent
 908 * READ where the file size could change.  Our preference is simply
 909 * to do all reads the application wants, and the server will take
 910 * care of managing the end of file boundary.
 911 *
 912 * This function also eliminates unnecessarily updating the file's
 913 * atime locally, as the NFS server sets the file's atime, and this
 914 * client must read the updated atime from the server back into its
 915 * cache.
 916 */
 917ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
 918                                unsigned long nr_segs, loff_t pos)
 919{
 920        ssize_t retval = -EINVAL;
 921        struct file *file = iocb->ki_filp;
 922        struct address_space *mapping = file->f_mapping;
 923        size_t count;
 924
 925        count = iov_length(iov, nr_segs);
 926        nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 927
 928        dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
 929                file->f_path.dentry->d_parent->d_name.name,
 930                file->f_path.dentry->d_name.name,
 931                count, (long long) pos);
 932
 933        retval = 0;
 934        if (!count)
 935                goto out;
 936
 937        retval = nfs_sync_mapping(mapping);
 938        if (retval)
 939                goto out;
 940
 941        task_io_account_read(count);
 942
 943        retval = nfs_direct_read(iocb, iov, nr_segs, pos);
 944        if (retval > 0)
 945                iocb->ki_pos = pos + retval;
 946
 947out:
 948        return retval;
 949}
 950
 951/**
 952 * nfs_file_direct_write - file direct write operation for NFS files
 953 * @iocb: target I/O control block
 954 * @iov: vector of user buffers from which to write data
 955 * @nr_segs: size of iov vector
 956 * @pos: byte offset in file where writing starts
 957 *
 958 * We use this function for direct writes instead of calling
 959 * generic_file_aio_write() in order to avoid taking the inode
 960 * semaphore and updating the i_size.  The NFS server will set
 961 * the new i_size and this client must read the updated size
 962 * back into its cache.  We let the server do generic write
 963 * parameter checking and report problems.
 964 *
 965 * We eliminate local atime updates, see direct read above.
 966 *
 967 * We avoid unnecessary page cache invalidations for normal cached
 968 * readers of this file.
 969 *
 970 * Note that O_APPEND is not supported for NFS direct writes, as there
 971 * is no atomic O_APPEND write facility in the NFS protocol.
 972 */
 973ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 974                                unsigned long nr_segs, loff_t pos)
 975{
 976        ssize_t retval = -EINVAL;
 977        struct file *file = iocb->ki_filp;
 978        struct address_space *mapping = file->f_mapping;
 979        size_t count;
 980
 981        count = iov_length(iov, nr_segs);
 982        nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 983
 984        dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
 985                file->f_path.dentry->d_parent->d_name.name,
 986                file->f_path.dentry->d_name.name,
 987                count, (long long) pos);
 988
 989        retval = generic_write_checks(file, &pos, &count, 0);
 990        if (retval)
 991                goto out;
 992
 993        retval = -EINVAL;
 994        if ((ssize_t) count < 0)
 995                goto out;
 996        retval = 0;
 997        if (!count)
 998                goto out;
 999
1000        retval = nfs_sync_mapping(mapping);
1001        if (retval)
1002                goto out;
1003
1004        task_io_account_write(count);
1005
1006        retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
1007
1008        if (retval > 0)
1009                iocb->ki_pos = pos + retval;
1010
1011out:
1012        return retval;
1013}
1014
1015/**
1016 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1017 *
1018 */
1019int __init nfs_init_directcache(void)
1020{
1021        nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1022                                                sizeof(struct nfs_direct_req),
1023                                                0, (SLAB_RECLAIM_ACCOUNT|
1024                                                        SLAB_MEM_SPREAD),
1025                                                NULL);
1026        if (nfs_direct_cachep == NULL)
1027                return -ENOMEM;
1028
1029        return 0;
1030}
1031
1032/**
1033 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1034 *
1035 */
1036void nfs_destroy_directcache(void)
1037{
1038        kmem_cache_destroy(nfs_direct_cachep);
1039}
1040