fs/nfs/direct.c

   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
  63 static struct kmem_cache *nfs_direct_cachep;
  64
  65 /*
  66  * This represents a set of asynchronous requests that we're waiting on
  67  */
  68 struct 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
  93 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
  94 static const struct rpc_call_ops nfs_write_direct_ops;
  95
  96 static inline void get_dreq(struct nfs_direct_req *dreq)
  97 {
  98         atomic_inc(&dreq->io_count);
  99 }
 100
 101 static 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  */
 119 ssize_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
 128 static 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
 144 static 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
 151 static 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
 175 static 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
 186 static 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  */
 194 static 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
 209 out:
 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  */
 217 static 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  */
 235 static 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
 242 static 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
 267 static 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  */
 282 static 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
 389 static 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
 425 static 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);
 447 out_release:
 448         nfs_direct_req_release(dreq);
 449 out:
 450         return result;
 451 }
 452
 453 static 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)
 464 static 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
 528 static 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
 536 static 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
 556 static 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
 564 static 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
 608 static 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
 629 static 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
 636 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
 637 {
 638         dreq->commit_data = NULL;
 639 }
 640
 641 static 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
 649 static 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  */
 660 static 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         }
 691 out_unlock:
 692         spin_unlock(&dreq->lock);
 693
 694         if (put_dreq(dreq))
 695                 nfs_direct_write_complete(dreq, data->inode);
 696 }
 697
 698 static 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  */
 713 static 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
 824 static 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
 861 static 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);
 890 out_release:
 891         nfs_direct_req_release(dreq);
 892 out:
 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  */
 917 ssize_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
 947 out:
 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  */
 973 ssize_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
1011 out:
1012         return retval;
1013 }
1014
1015 /**
1016  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1017  *
1018  */
1019 int __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  */
1036 void nfs_destroy_directcache(void)
1037 {
1038         kmem_cache_destroy(nfs_direct_cachep);
1039 }