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