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
 192         /* Async requests don't wait here */
 193         if (dreq->iocb)
 194                 goto out;
 195
 196         result = wait_for_completion_interruptible(&dreq->completion);
 197
 198         if (!result)
 199                 result = dreq->error;
 200         if (!result)
 201                 result = dreq->count;
 202
 203 out:
 204         return (ssize_t) result;
 205 }
 206
 207 /*
 208  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
 209  * the iocb is still valid here if this is a synchronous request.
 210  */
 211 static void nfs_direct_complete(struct nfs_direct_req *dreq)
 212 {
 213         if (dreq->iocb) {
 214                 long res = (long) dreq->error;
 215                 if (!res)
 216                         res = (long) dreq->count;
 217                 aio_complete(dreq->iocb, res, 0);
 218         }
 219         complete_all(&dreq->completion);
 220
 221         nfs_direct_req_release(dreq);
 222 }
 223
 224 /*
 225  * We must hold a reference to all the pages in this direct read request
 226  * until the RPCs complete.  This could be long *after* we are woken up in
 227  * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
 228  */
 229 static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
 230 {
 231         struct nfs_read_data *data = calldata;
 232         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 233
 234         if (nfs_readpage_result(task, data) != 0)
 235                 return;
 236
 237         spin_lock(&dreq->lock);
 238         if (unlikely(task->tk_status < 0)) {
 239                 dreq->error = task->tk_status;
 240                 spin_unlock(&dreq->lock);
 241         } else {
 242                 dreq->count += data->res.count;
 243                 spin_unlock(&dreq->lock);
 244                 nfs_direct_dirty_pages(data->pagevec,
 245                                 data->args.pgbase,
 246                                 data->res.count);
 247         }
 248         nfs_direct_release_pages(data->pagevec, data->npages);
 249
 250         if (put_dreq(dreq))
 251                 nfs_direct_complete(dreq);
 252 }
 253
 254 static const struct rpc_call_ops nfs_read_direct_ops = {
 255         .rpc_call_done = nfs_direct_read_result,
 256         .rpc_release = nfs_readdata_release,
 257 };
 258
 259 /*
 260  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
 261  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
 262  * bail and stop sending more reads.  Read length accounting is
 263  * handled automatically by nfs_direct_read_result().  Otherwise, if
 264  * no requests have been sent, just return an error.
 265  */
 266 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
 267                                                 const struct iovec *iov,
 268                                                 loff_t pos)
 269 {
 270         struct nfs_open_context *ctx = dreq->ctx;
 271         struct inode *inode = ctx->path.dentry->d_inode;
 272         unsigned long user_addr = (unsigned long)iov->iov_base;
 273         size_t count = iov->iov_len;
 274         size_t rsize = NFS_SERVER(inode)->rsize;
 275         struct rpc_task *task;
 276         struct rpc_message msg = {
 277                 .rpc_cred = ctx->cred,
 278         };
 279         struct rpc_task_setup task_setup_data = {
 280                 .rpc_client = NFS_CLIENT(inode),
 281                 .rpc_message = &msg,
 282                 .callback_ops = &nfs_read_direct_ops,
 283                 .flags = RPC_TASK_ASYNC,
 284         };
 285         unsigned int pgbase;
 286         int result;
 287         ssize_t started = 0;
 288
 289         do {
 290                 struct nfs_read_data *data;
 291                 size_t bytes;
 292
 293                 pgbase = user_addr & ~PAGE_MASK;
 294                 bytes = min(rsize,count);
 295
 296                 result = -ENOMEM;
 297                 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
 298                 if (unlikely(!data))
 299                         break;
 300
 301                 down_read(&current->mm->mmap_sem);
 302                 result = get_user_pages(current, current->mm, user_addr,
 303                                         data->npages, 1, 0, data->pagevec, NULL);
 304                 up_read(&current->mm->mmap_sem);
 305                 if (result < 0) {
 306                         nfs_readdata_release(data);
 307                         break;
 308                 }
 309                 if ((unsigned)result < data->npages) {
 310                         bytes = result * PAGE_SIZE;
 311                         if (bytes <= pgbase) {
 312                                 nfs_direct_release_pages(data->pagevec, result);
 313                                 nfs_readdata_release(data);
 314                                 break;
 315                         }
 316                         bytes -= pgbase;
 317                         data->npages = result;
 318                 }
 319
 320                 get_dreq(dreq);
 321
 322                 data->req = (struct nfs_page *) dreq;
 323                 data->inode = inode;
 324                 data->cred = msg.rpc_cred;
 325                 data->args.fh = NFS_FH(inode);
 326                 data->args.context = ctx;
 327                 data->args.offset = pos;
 328                 data->args.pgbase = pgbase;
 329                 data->args.pages = data->pagevec;
 330                 data->args.count = bytes;
 331                 data->res.fattr = &data->fattr;
 332                 data->res.eof = 0;
 333                 data->res.count = bytes;
 334                 msg.rpc_argp = &data->args;
 335                 msg.rpc_resp = &data->res;
 336
 337                 task_setup_data.task = &data->task;
 338                 task_setup_data.callback_data = data;
 339                 NFS_PROTO(inode)->read_setup(data, &msg);
 340
 341                 task = rpc_run_task(&task_setup_data);
 342                 if (!IS_ERR(task))
 343                         rpc_put_task(task);
 344
 345                 dprintk("NFS: %5u initiated direct read call "
 346                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
 347                                 data->task.tk_pid,
 348                                 inode->i_sb->s_id,
 349                                 (long long)NFS_FILEID(inode),
 350                                 bytes,
 351                                 (unsigned long long)data->args.offset);
 352
 353                 started += bytes;
 354                 user_addr += bytes;
 355                 pos += bytes;
 356                 /* FIXME: Remove this unnecessary math from final patch */
 357                 pgbase += bytes;
 358                 pgbase &= ~PAGE_MASK;
 359                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
 360
 361                 count -= bytes;
 362         } while (count != 0);
 363
 364         if (started)
 365                 return started;
 366         return result < 0 ? (ssize_t) result : -EFAULT;
 367 }
 368
 369 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 370                                               const struct iovec *iov,
 371                                               unsigned long nr_segs,
 372                                               loff_t pos)
 373 {
 374         ssize_t result = -EINVAL;
 375         size_t requested_bytes = 0;
 376         unsigned long seg;
 377
 378         get_dreq(dreq);
 379
 380         for (seg = 0; seg < nr_segs; seg++) {
 381                 const struct iovec *vec = &iov[seg];
 382                 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
 383                 if (result < 0)
 384                         break;
 385                 requested_bytes += result;
 386                 if ((size_t)result < vec->iov_len)
 387                         break;
 388                 pos += vec->iov_len;
 389         }
 390
 391         if (put_dreq(dreq))
 392                 nfs_direct_complete(dreq);
 393
 394         if (requested_bytes != 0)
 395                 return 0;
 396
 397         if (result < 0)
 398                 return result;
 399         return -EIO;
 400 }
 401
 402 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
 403                                unsigned long nr_segs, loff_t pos)
 404 {
 405         ssize_t result = 0;
 406         sigset_t oldset;
 407         struct inode *inode = iocb->ki_filp->f_mapping->host;
 408         struct rpc_clnt *clnt = NFS_CLIENT(inode);
 409         struct nfs_direct_req *dreq;
 410
 411         dreq = nfs_direct_req_alloc();
 412         if (!dreq)
 413                 return -ENOMEM;
 414
 415         dreq->inode = inode;
 416         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 417         if (!is_sync_kiocb(iocb))
 418                 dreq->iocb = iocb;
 419
 420         rpc_clnt_sigmask(clnt, &oldset);
 421         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
 422         if (!result)
 423                 result = nfs_direct_wait(dreq);
 424         rpc_clnt_sigunmask(clnt, &oldset);
 425         nfs_direct_req_release(dreq);
 426
 427         return result;
 428 }
 429
 430 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
 431 {
 432         while (!list_empty(&dreq->rewrite_list)) {
 433                 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
 434                 list_del(&data->pages);
 435                 nfs_direct_release_pages(data->pagevec, data->npages);
 436                 nfs_writedata_release(data);
 437         }
 438 }
 439
 440 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 441 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 442 {
 443         struct inode *inode = dreq->inode;
 444         struct list_head *p;
 445         struct nfs_write_data *data;
 446         struct rpc_task *task;
 447         struct rpc_message msg = {
 448                 .rpc_cred = dreq->ctx->cred,
 449         };
 450         struct rpc_task_setup task_setup_data = {
 451                 .rpc_client = NFS_CLIENT(inode),
 452                 .callback_ops = &nfs_write_direct_ops,
 453                 .flags = RPC_TASK_ASYNC,
 454         };
 455
 456         dreq->count = 0;
 457         get_dreq(dreq);
 458
 459         list_for_each(p, &dreq->rewrite_list) {
 460                 data = list_entry(p, struct nfs_write_data, pages);
 461
 462                 get_dreq(dreq);
 463
 464                 /* Use stable writes */
 465                 data->args.stable = NFS_FILE_SYNC;
 466
 467                 /*
 468                  * Reset data->res.
 469                  */
 470                 nfs_fattr_init(&data->fattr);
 471                 data->res.count = data->args.count;
 472                 memset(&data->verf, 0, sizeof(data->verf));
 473
 474                 /*
 475                  * Reuse data->task; data->args should not have changed
 476                  * since the original request was sent.
 477                  */
 478                 task_setup_data.task = &data->task;
 479                 task_setup_data.callback_data = data;
 480                 msg.rpc_argp = &data->args;
 481                 msg.rpc_resp = &data->res;
 482                 NFS_PROTO(inode)->write_setup(data, &msg);
 483
 484                 /*
 485                  * We're called via an RPC callback, so BKL is already held.
 486                  */
 487                 task = rpc_run_task(&task_setup_data);
 488                 if (!IS_ERR(task))
 489                         rpc_put_task(task);
 490
 491                 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
 492                                 data->task.tk_pid,
 493                                 inode->i_sb->s_id,
 494                                 (long long)NFS_FILEID(inode),
 495                                 data->args.count,
 496                                 (unsigned long long)data->args.offset);
 497         }
 498
 499         if (put_dreq(dreq))
 500                 nfs_direct_write_complete(dreq, inode);
 501 }
 502
 503 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
 504 {
 505         struct nfs_write_data *data = calldata;
 506         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 507
 508         /* Call the NFS version-specific code */
 509         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
 510                 return;
 511         if (unlikely(task->tk_status < 0)) {
 512                 dprintk("NFS: %5u commit failed with error %d.\n",
 513                                 task->tk_pid, task->tk_status);
 514                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 515         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
 516                 dprintk("NFS: %5u commit verify failed\n", task->tk_pid);
 517                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 518         }
 519
 520         dprintk("NFS: %5u commit returned %d\n", task->tk_pid, task->tk_status);
 521         nfs_direct_write_complete(dreq, data->inode);
 522 }
 523
 524 static const struct rpc_call_ops nfs_commit_direct_ops = {
 525         .rpc_call_done = nfs_direct_commit_result,
 526         .rpc_release = nfs_commit_release,
 527 };
 528
 529 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 530 {
 531         struct nfs_write_data *data = dreq->commit_data;
 532         struct rpc_task *task;
 533         struct rpc_message msg = {
 534                 .rpc_argp = &data->args,
 535                 .rpc_resp = &data->res,
 536                 .rpc_cred = dreq->ctx->cred,
 537         };
 538         struct rpc_task_setup task_setup_data = {
 539                 .task = &data->task,
 540                 .rpc_client = NFS_CLIENT(dreq->inode),
 541                 .rpc_message = &msg,
 542                 .callback_ops = &nfs_commit_direct_ops,
 543                 .callback_data = data,
 544                 .flags = RPC_TASK_ASYNC,
 545         };
 546
 547         data->inode = dreq->inode;
 548         data->cred = msg.rpc_cred;
 549
 550         data->args.fh = NFS_FH(data->inode);
 551         data->args.offset = 0;
 552         data->args.count = 0;
 553         data->res.count = 0;
 554         data->res.fattr = &data->fattr;
 555         data->res.verf = &data->verf;
 556
 557         NFS_PROTO(data->inode)->commit_setup(data, &msg);
 558
 559         /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
 560         dreq->commit_data = NULL;
 561
 562         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
 563
 564         task = rpc_run_task(&task_setup_data);
 565         if (!IS_ERR(task))
 566                 rpc_put_task(task);
 567 }
 568
 569 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 570 {
 571         int flags = dreq->flags;
 572
 573         dreq->flags = 0;
 574         switch (flags) {
 575                 case NFS_ODIRECT_DO_COMMIT:
 576                         nfs_direct_commit_schedule(dreq);
 577                         break;
 578                 case NFS_ODIRECT_RESCHED_WRITES:
 579                         nfs_direct_write_reschedule(dreq);
 580                         break;
 581                 default:
 582                         if (dreq->commit_data != NULL)
 583                                 nfs_commit_free(dreq->commit_data);
 584                         nfs_direct_free_writedata(dreq);
 585                         nfs_zap_mapping(inode, inode->i_mapping);
 586                         nfs_direct_complete(dreq);
 587         }
 588 }
 589
 590 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
 591 {
 592         dreq->commit_data = nfs_commit_alloc();
 593         if (dreq->commit_data != NULL)
 594                 dreq->commit_data->req = (struct nfs_page *) dreq;
 595 }
 596 #else
 597 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
 598 {
 599         dreq->commit_data = NULL;
 600 }
 601
 602 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 603 {
 604         nfs_direct_free_writedata(dreq);
 605         nfs_zap_mapping(inode, inode->i_mapping);
 606         nfs_direct_complete(dreq);
 607 }
 608 #endif
 609
 610 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
 611 {
 612         struct nfs_write_data *data = calldata;
 613         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 614         int status = task->tk_status;
 615
 616         if (nfs_writeback_done(task, data) != 0)
 617                 return;
 618
 619         spin_lock(&dreq->lock);
 620
 621         if (unlikely(status < 0)) {
 622                 /* An error has occurred, so we should not commit */
 623                 dreq->flags = 0;
 624                 dreq->error = status;
 625         }
 626         if (unlikely(dreq->error != 0))
 627                 goto out_unlock;
 628
 629         dreq->count += data->res.count;
 630
 631         if (data->res.verf->committed != NFS_FILE_SYNC) {
 632                 switch (dreq->flags) {
 633                         case 0:
 634                                 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
 635                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
 636                                 break;
 637                         case NFS_ODIRECT_DO_COMMIT:
 638                                 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
 639                                         dprintk("NFS: %5u write verify failed\n", task->tk_pid);
 640                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 641                                 }
 642                 }
 643         }
 644 out_unlock:
 645         spin_unlock(&dreq->lock);
 646 }
 647
 648 /*
 649  * NB: Return the value of the first error return code.  Subsequent
 650  *     errors after the first one are ignored.
 651  */
 652 static void nfs_direct_write_release(void *calldata)
 653 {
 654         struct nfs_write_data *data = calldata;
 655         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 656
 657         if (put_dreq(dreq))
 658                 nfs_direct_write_complete(dreq, data->inode);
 659 }
 660
 661 static const struct rpc_call_ops nfs_write_direct_ops = {
 662         .rpc_call_done = nfs_direct_write_result,
 663         .rpc_release = nfs_direct_write_release,
 664 };
 665
 666 /*
 667  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
 668  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
 669  * bail and stop sending more writes.  Write length accounting is
 670  * handled automatically by nfs_direct_write_result().  Otherwise, if
 671  * no requests have been sent, just return an error.
 672  */
 673 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
 674                                                  const struct iovec *iov,
 675                                                  loff_t pos, int sync)
 676 {
 677         struct nfs_open_context *ctx = dreq->ctx;
 678         struct inode *inode = ctx->path.dentry->d_inode;
 679         unsigned long user_addr = (unsigned long)iov->iov_base;
 680         size_t count = iov->iov_len;
 681         struct rpc_task *task;
 682         struct rpc_message msg = {
 683                 .rpc_cred = ctx->cred,
 684         };
 685         struct rpc_task_setup task_setup_data = {
 686                 .rpc_client = NFS_CLIENT(inode),
 687                 .rpc_message = &msg,
 688                 .callback_ops = &nfs_write_direct_ops,
 689                 .flags = RPC_TASK_ASYNC,
 690         };
 691         size_t wsize = NFS_SERVER(inode)->wsize;
 692         unsigned int pgbase;
 693         int result;
 694         ssize_t started = 0;
 695
 696         do {
 697                 struct nfs_write_data *data;
 698                 size_t bytes;
 699
 700                 pgbase = user_addr & ~PAGE_MASK;
 701                 bytes = min(wsize,count);
 702
 703                 result = -ENOMEM;
 704                 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
 705                 if (unlikely(!data))
 706                         break;
 707
 708                 down_read(&current->mm->mmap_sem);
 709                 result = get_user_pages(current, current->mm, user_addr,
 710                                         data->npages, 0, 0, data->pagevec, NULL);
 711                 up_read(&current->mm->mmap_sem);
 712                 if (result < 0) {
 713                         nfs_writedata_release(data);
 714                         break;
 715                 }
 716                 if ((unsigned)result < data->npages) {
 717                         bytes = result * PAGE_SIZE;
 718                         if (bytes <= pgbase) {
 719                                 nfs_direct_release_pages(data->pagevec, result);
 720                                 nfs_writedata_release(data);
 721                                 break;
 722                         }
 723                         bytes -= pgbase;
 724                         data->npages = result;
 725                 }
 726
 727                 get_dreq(dreq);
 728
 729                 list_move_tail(&data->pages, &dreq->rewrite_list);
 730
 731                 data->req = (struct nfs_page *) dreq;
 732                 data->inode = inode;
 733                 data->cred = msg.rpc_cred;
 734                 data->args.fh = NFS_FH(inode);
 735                 data->args.context = ctx;
 736                 data->args.offset = pos;
 737                 data->args.pgbase = pgbase;
 738                 data->args.pages = data->pagevec;
 739                 data->args.count = bytes;
 740                 data->args.stable = sync;
 741                 data->res.fattr = &data->fattr;
 742                 data->res.count = bytes;
 743                 data->res.verf = &data->verf;
 744
 745                 task_setup_data.task = &data->task;
 746                 task_setup_data.callback_data = data;
 747                 msg.rpc_argp = &data->args;
 748                 msg.rpc_resp = &data->res;
 749                 NFS_PROTO(inode)->write_setup(data, &msg);
 750
 751                 task = rpc_run_task(&task_setup_data);
 752                 if (!IS_ERR(task))
 753                         rpc_put_task(task);
 754
 755                 dprintk("NFS: %5u initiated direct write call "
 756                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
 757                                 data->task.tk_pid,
 758                                 inode->i_sb->s_id,
 759                                 (long long)NFS_FILEID(inode),
 760                                 bytes,
 761                                 (unsigned long long)data->args.offset);
 762
 763                 started += bytes;
 764                 user_addr += bytes;
 765                 pos += bytes;
 766
 767                 /* FIXME: Remove this useless math from the final patch */
 768                 pgbase += bytes;
 769                 pgbase &= ~PAGE_MASK;
 770                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
 771
 772                 count -= bytes;
 773         } while (count != 0);
 774
 775         if (started)
 776                 return started;
 777         return result < 0 ? (ssize_t) result : -EFAULT;
 778 }
 779
 780 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 781                                                const struct iovec *iov,
 782                                                unsigned long nr_segs,
 783                                                loff_t pos, int sync)
 784 {
 785         ssize_t result = 0;
 786         size_t requested_bytes = 0;
 787         unsigned long seg;
 788
 789         get_dreq(dreq);
 790
 791         for (seg = 0; seg < nr_segs; seg++) {
 792                 const struct iovec *vec = &iov[seg];
 793                 result = nfs_direct_write_schedule_segment(dreq, vec,
 794                                                            pos, sync);
 795                 if (result < 0)
 796                         break;
 797                 requested_bytes += result;
 798                 if ((size_t)result < vec->iov_len)
 799                         break;
 800                 pos += vec->iov_len;
 801         }
 802
 803         if (put_dreq(dreq))
 804                 nfs_direct_write_complete(dreq, dreq->inode);
 805
 806         if (requested_bytes != 0)
 807                 return 0;
 808
 809         if (result < 0)
 810                 return result;
 811         return -EIO;
 812 }
 813
 814 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
 815                                 unsigned long nr_segs, loff_t pos,
 816                                 size_t count)
 817 {
 818         ssize_t result = 0;
 819         sigset_t oldset;
 820         struct inode *inode = iocb->ki_filp->f_mapping->host;
 821         struct rpc_clnt *clnt = NFS_CLIENT(inode);
 822         struct nfs_direct_req *dreq;
 823         size_t wsize = NFS_SERVER(inode)->wsize;
 824         int sync = NFS_UNSTABLE;
 825
 826         dreq = nfs_direct_req_alloc();
 827         if (!dreq)
 828                 return -ENOMEM;
 829         nfs_alloc_commit_data(dreq);
 830
 831         if (dreq->commit_data == NULL || count < wsize)
 832                 sync = NFS_FILE_SYNC;
 833
 834         dreq->inode = inode;
 835         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 836         if (!is_sync_kiocb(iocb))
 837                 dreq->iocb = iocb;
 838
 839         rpc_clnt_sigmask(clnt, &oldset);
 840         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
 841         if (!result)
 842                 result = nfs_direct_wait(dreq);
 843         rpc_clnt_sigunmask(clnt, &oldset);
 844         nfs_direct_req_release(dreq);
 845
 846         return result;
 847 }
 848
 849 /**
 850  * nfs_file_direct_read - file direct read operation for NFS files
 851  * @iocb: target I/O control block
 852  * @iov: vector of user buffers into which to read data
 853  * @nr_segs: size of iov vector
 854  * @pos: byte offset in file where reading starts
 855  *
 856  * We use this function for direct reads instead of calling
 857  * generic_file_aio_read() in order to avoid gfar's check to see if
 858  * the request starts before the end of the file.  For that check
 859  * to work, we must generate a GETATTR before each direct read, and
 860  * even then there is a window between the GETATTR and the subsequent
 861  * READ where the file size could change.  Our preference is simply
 862  * to do all reads the application wants, and the server will take
 863  * care of managing the end of file boundary.
 864  *
 865  * This function also eliminates unnecessarily updating the file's
 866  * atime locally, as the NFS server sets the file's atime, and this
 867  * client must read the updated atime from the server back into its
 868  * cache.
 869  */
 870 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
 871                                 unsigned long nr_segs, loff_t pos)
 872 {
 873         ssize_t retval = -EINVAL;
 874         struct file *file = iocb->ki_filp;
 875         struct address_space *mapping = file->f_mapping;
 876         size_t count;
 877
 878         count = iov_length(iov, nr_segs);
 879         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 880
 881         dprintk("nfs: direct read(%s/%s, %zd@%Ld)\n",
 882                 file->f_path.dentry->d_parent->d_name.name,
 883                 file->f_path.dentry->d_name.name,
 884                 count, (long long) pos);
 885
 886         retval = 0;
 887         if (!count)
 888                 goto out;
 889
 890         retval = nfs_sync_mapping(mapping);
 891         if (retval)
 892                 goto out;
 893
 894         retval = nfs_direct_read(iocb, iov, nr_segs, pos);
 895         if (retval > 0)
 896                 iocb->ki_pos = pos + retval;
 897
 898 out:
 899         return retval;
 900 }
 901
 902 /**
 903  * nfs_file_direct_write - file direct write operation for NFS files
 904  * @iocb: target I/O control block
 905  * @iov: vector of user buffers from which to write data
 906  * @nr_segs: size of iov vector
 907  * @pos: byte offset in file where writing starts
 908  *
 909  * We use this function for direct writes instead of calling
 910  * generic_file_aio_write() in order to avoid taking the inode
 911  * semaphore and updating the i_size.  The NFS server will set
 912  * the new i_size and this client must read the updated size
 913  * back into its cache.  We let the server do generic write
 914  * parameter checking and report problems.
 915  *
 916  * We also avoid an unnecessary invocation of generic_osync_inode(),
 917  * as it is fairly meaningless to sync the metadata of an NFS file.
 918  *
 919  * We eliminate local atime updates, see direct read above.
 920  *
 921  * We avoid unnecessary page cache invalidations for normal cached
 922  * readers of this file.
 923  *
 924  * Note that O_APPEND is not supported for NFS direct writes, as there
 925  * is no atomic O_APPEND write facility in the NFS protocol.
 926  */
 927 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 928                                 unsigned long nr_segs, loff_t pos)
 929 {
 930         ssize_t retval = -EINVAL;
 931         struct file *file = iocb->ki_filp;
 932         struct address_space *mapping = file->f_mapping;
 933         size_t count;
 934
 935         count = iov_length(iov, nr_segs);
 936         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 937
 938         dfprintk(VFS, "nfs: direct write(%s/%s, %zd@%Ld)\n",
 939                 file->f_path.dentry->d_parent->d_name.name,
 940                 file->f_path.dentry->d_name.name,
 941                 count, (long long) pos);
 942
 943         retval = generic_write_checks(file, &pos, &count, 0);
 944         if (retval)
 945                 goto out;
 946
 947         retval = -EINVAL;
 948         if ((ssize_t) count < 0)
 949                 goto out;
 950         retval = 0;
 951         if (!count)
 952                 goto out;
 953
 954         retval = nfs_sync_mapping(mapping);
 955         if (retval)
 956                 goto out;
 957
 958         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
 959
 960         if (retval > 0)
 961                 iocb->ki_pos = pos + retval;
 962
 963 out:
 964         return retval;
 965 }
 966
 967 /**
 968  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
 969  *
 970  */
 971 int __init nfs_init_directcache(void)
 972 {
 973         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
 974                                                 sizeof(struct nfs_direct_req),
 975                                                 0, (SLAB_RECLAIM_ACCOUNT|
 976                                                         SLAB_MEM_SPREAD),
 977                                                 NULL);
 978         if (nfs_direct_cachep == NULL)
 979                 return -ENOMEM;
 980
 981         return 0;
 982 }
 983
 984 /**
 985  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
 986  *
 987  */
 988 void nfs_destroy_directcache(void)
 989 {
 990         kmem_cache_destroy(nfs_direct_cachep);
 991 }