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/uaccess.h>
  55 #include <linux/atomic.h>
  56
  57 #include "internal.h"
  58 #include "iostat.h"
  59 #include "pnfs.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 nfs_mds_commit_info mds_cinfo;   /* Storage for cinfo */
  86         struct pnfs_ds_commit_info ds_cinfo;    /* Storage for cinfo */
  87         struct work_struct      work;
  88         int                     flags;
  89 #define NFS_ODIRECT_DO_COMMIT           (1)     /* an unstable reply was received */
  90 #define NFS_ODIRECT_RESCHED_WRITES      (2)     /* write verification failed */
  91         struct nfs_writeverf    verf;           /* unstable write verifier */
  92 };
  93
  94 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
  95 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
  96 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
  97 static void nfs_direct_write_schedule_work(struct work_struct *work);
  98
  99 static inline void get_dreq(struct nfs_direct_req *dreq)
 100 {
 101         atomic_inc(&dreq->io_count);
 102 }
 103
 104 static inline int put_dreq(struct nfs_direct_req *dreq)
 105 {
 106         return atomic_dec_and_test(&dreq->io_count);
 107 }
 108
 109 /**
 110  * nfs_direct_IO - NFS address space operation for direct I/O
 111  * @rw: direction (read or write)
 112  * @iocb: target I/O control block
 113  * @iov: array of vectors that define I/O buffer
 114  * @pos: offset in file to begin the operation
 115  * @nr_segs: size of iovec array
 116  *
 117  * The presence of this routine in the address space ops vector means
 118  * the NFS client supports direct I/O.  However, we shunt off direct
 119  * read and write requests before the VFS gets them, so this method
 120  * should never be called.
 121  */
 122 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
 123 {
 124         dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
 125                         iocb->ki_filp->f_path.dentry->d_name.name,
 126                         (long long) pos, nr_segs);
 127
 128         return -EINVAL;
 129 }
 130
 131 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
 132 {
 133         unsigned int i;
 134         for (i = 0; i < npages; i++)
 135                 page_cache_release(pages[i]);
 136 }
 137
 138 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
 139                               struct nfs_direct_req *dreq)
 140 {
 141         cinfo->lock = &dreq->lock;
 142         cinfo->mds = &dreq->mds_cinfo;
 143         cinfo->ds = &dreq->ds_cinfo;
 144         cinfo->dreq = dreq;
 145         cinfo->completion_ops = &nfs_direct_commit_completion_ops;
 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_zalloc(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->mds_cinfo.list);
 160         INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
 161         spin_lock_init(&dreq->lock);
 162
 163         return dreq;
 164 }
 165
 166 static void nfs_direct_req_free(struct kref *kref)
 167 {
 168         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
 169
 170         if (dreq->l_ctx != NULL)
 171                 nfs_put_lock_context(dreq->l_ctx);
 172         if (dreq->ctx != NULL)
 173                 put_nfs_open_context(dreq->ctx);
 174         kmem_cache_free(nfs_direct_cachep, dreq);
 175 }
 176
 177 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
 178 {
 179         kref_put(&dreq->kref, nfs_direct_req_free);
 180 }
 181
 182 /*
 183  * Collects and returns the final error value/byte-count.
 184  */
 185 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
 186 {
 187         ssize_t result = -EIOCBQUEUED;
 188
 189         /* Async requests don't wait here */
 190         if (dreq->iocb)
 191                 goto out;
 192
 193         result = wait_for_completion_killable(&dreq->completion);
 194
 195         if (!result)
 196                 result = dreq->error;
 197         if (!result)
 198                 result = dreq->count;
 199
 200 out:
 201         return (ssize_t) result;
 202 }
 203
 204 /*
 205  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
 206  * the iocb is still valid here if this is a synchronous request.
 207  */
 208 static void nfs_direct_complete(struct nfs_direct_req *dreq)
 209 {
 210         if (dreq->iocb) {
 211                 long res = (long) dreq->error;
 212                 if (!res)
 213                         res = (long) dreq->count;
 214                 aio_complete(dreq->iocb, res, 0);
 215         }
 216         complete_all(&dreq->completion);
 217
 218         nfs_direct_req_release(dreq);
 219 }
 220
 221 static void nfs_direct_readpage_release(struct nfs_page *req)
 222 {
 223         dprintk("NFS: direct read done (%s/%lld %d@%lld)\n",
 224                 req->wb_context->dentry->d_inode->i_sb->s_id,
 225                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
 226                 req->wb_bytes,
 227                 (long long)req_offset(req));
 228         nfs_release_request(req);
 229 }
 230
 231 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
 232 {
 233         unsigned long bytes = 0;
 234         struct nfs_direct_req *dreq = hdr->dreq;
 235
 236         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 237                 goto out_put;
 238
 239         spin_lock(&dreq->lock);
 240         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
 241                 dreq->error = hdr->error;
 242         else
 243                 dreq->count += hdr->good_bytes;
 244         spin_unlock(&dreq->lock);
 245
 246         while (!list_empty(&hdr->pages)) {
 247                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 248                 struct page *page = req->wb_page;
 249
 250                 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 251                         if (bytes > hdr->good_bytes)
 252                                 zero_user(page, 0, PAGE_SIZE);
 253                         else if (hdr->good_bytes - bytes < PAGE_SIZE)
 254                                 zero_user_segment(page,
 255                                         hdr->good_bytes & ~PAGE_MASK,
 256                                         PAGE_SIZE);
 257                 }
 258                 if (!PageCompound(page)) {
 259                         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 260                                 if (bytes < hdr->good_bytes)
 261                                         set_page_dirty(page);
 262                         } else
 263                                 set_page_dirty(page);
 264                 }
 265                 bytes += req->wb_bytes;
 266                 nfs_list_remove_request(req);
 267                 nfs_direct_readpage_release(req);
 268         }
 269 out_put:
 270         if (put_dreq(dreq))
 271                 nfs_direct_complete(dreq);
 272         hdr->release(hdr);
 273 }
 274
 275 static void nfs_read_sync_pgio_error(struct list_head *head)
 276 {
 277         struct nfs_page *req;
 278
 279         while (!list_empty(head)) {
 280                 req = nfs_list_entry(head->next);
 281                 nfs_list_remove_request(req);
 282                 nfs_release_request(req);
 283         }
 284 }
 285
 286 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
 287 {
 288         get_dreq(hdr->dreq);
 289 }
 290
 291 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
 292         .error_cleanup = nfs_read_sync_pgio_error,
 293         .init_hdr = nfs_direct_pgio_init,
 294         .completion = nfs_direct_read_completion,
 295 };
 296
 297 /*
 298  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
 299  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
 300  * bail and stop sending more reads.  Read length accounting is
 301  * handled automatically by nfs_direct_read_result().  Otherwise, if
 302  * no requests have been sent, just return an error.
 303  */
 304 static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
 305                                                 const struct iovec *iov,
 306                                                 loff_t pos)
 307 {
 308         struct nfs_direct_req *dreq = desc->pg_dreq;
 309         struct nfs_open_context *ctx = dreq->ctx;
 310         struct inode *inode = ctx->dentry->d_inode;
 311         unsigned long user_addr = (unsigned long)iov->iov_base;
 312         size_t count = iov->iov_len;
 313         size_t rsize = NFS_SERVER(inode)->rsize;
 314         unsigned int pgbase;
 315         int result;
 316         ssize_t started = 0;
 317         struct page **pagevec = NULL;
 318         unsigned int npages;
 319
 320         do {
 321                 size_t bytes;
 322                 int i;
 323
 324                 pgbase = user_addr & ~PAGE_MASK;
 325                 bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
 326
 327                 result = -ENOMEM;
 328                 npages = nfs_page_array_len(pgbase, bytes);
 329                 if (!pagevec)
 330                         pagevec = kmalloc(npages * sizeof(struct page *),
 331                                           GFP_KERNEL);
 332                 if (!pagevec)
 333                         break;
 334                 down_read(&current->mm->mmap_sem);
 335                 result = get_user_pages(current, current->mm, user_addr,
 336                                         npages, 1, 0, pagevec, NULL);
 337                 up_read(&current->mm->mmap_sem);
 338                 if (result < 0)
 339                         break;
 340                 if ((unsigned)result < npages) {
 341                         bytes = result * PAGE_SIZE;
 342                         if (bytes <= pgbase) {
 343                                 nfs_direct_release_pages(pagevec, result);
 344                                 break;
 345                         }
 346                         bytes -= pgbase;
 347                         npages = result;
 348                 }
 349
 350                 for (i = 0; i < npages; i++) {
 351                         struct nfs_page *req;
 352                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 353                         /* XXX do we need to do the eof zeroing found in async_filler? */
 354                         req = nfs_create_request(dreq->ctx, dreq->inode,
 355                                                  pagevec[i],
 356                                                  pgbase, req_len);
 357                         if (IS_ERR(req)) {
 358                                 result = PTR_ERR(req);
 359                                 break;
 360                         }
 361                         req->wb_index = pos >> PAGE_SHIFT;
 362                         req->wb_offset = pos & ~PAGE_MASK;
 363                         if (!nfs_pageio_add_request(desc, req)) {
 364                                 result = desc->pg_error;
 365                                 nfs_release_request(req);
 366                                 break;
 367                         }
 368                         pgbase = 0;
 369                         bytes -= req_len;
 370                         started += req_len;
 371                         user_addr += req_len;
 372                         pos += req_len;
 373                         count -= req_len;
 374                 }
 375                 /* The nfs_page now hold references to these pages */
 376                 nfs_direct_release_pages(pagevec, npages);
 377         } while (count != 0 && result >= 0);
 378
 379         kfree(pagevec);
 380
 381         if (started)
 382                 return started;
 383         return result < 0 ? (ssize_t) result : -EFAULT;
 384 }
 385
 386 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 387                                               const struct iovec *iov,
 388                                               unsigned long nr_segs,
 389                                               loff_t pos)
 390 {
 391         struct nfs_pageio_descriptor desc;
 392         ssize_t result = -EINVAL;
 393         size_t requested_bytes = 0;
 394         unsigned long seg;
 395
 396         nfs_pageio_init_read(&desc, dreq->inode,
 397                              &nfs_direct_read_completion_ops);
 398         get_dreq(dreq);
 399         desc.pg_dreq = dreq;
 400
 401         for (seg = 0; seg < nr_segs; seg++) {
 402                 const struct iovec *vec = &iov[seg];
 403                 result = nfs_direct_read_schedule_segment(&desc, vec, pos);
 404                 if (result < 0)
 405                         break;
 406                 requested_bytes += result;
 407                 if ((size_t)result < vec->iov_len)
 408                         break;
 409                 pos += vec->iov_len;
 410         }
 411
 412         nfs_pageio_complete(&desc);
 413
 414         /*
 415          * If no bytes were started, return the error, and let the
 416          * generic layer handle the completion.
 417          */
 418         if (requested_bytes == 0) {
 419                 nfs_direct_req_release(dreq);
 420                 return result < 0 ? result : -EIO;
 421         }
 422
 423         if (put_dreq(dreq))
 424                 nfs_direct_complete(dreq);
 425         return 0;
 426 }
 427
 428 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
 429                                unsigned long nr_segs, loff_t pos)
 430 {
 431         ssize_t result = -ENOMEM;
 432         struct inode *inode = iocb->ki_filp->f_mapping->host;
 433         struct nfs_direct_req *dreq;
 434
 435         dreq = nfs_direct_req_alloc();
 436         if (dreq == NULL)
 437                 goto out;
 438
 439         dreq->inode = inode;
 440         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 441         dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
 442         if (dreq->l_ctx == NULL)
 443                 goto out_release;
 444         if (!is_sync_kiocb(iocb))
 445                 dreq->iocb = iocb;
 446
 447         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
 448         if (!result)
 449                 result = nfs_direct_wait(dreq);
 450         NFS_I(inode)->read_io += result;
 451 out_release:
 452         nfs_direct_req_release(dreq);
 453 out:
 454         return result;
 455 }
 456
 457 static void nfs_inode_dio_write_done(struct inode *inode)
 458 {
 459         nfs_zap_mapping(inode, inode->i_mapping);
 460         inode_dio_done(inode);
 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 nfs_pageio_descriptor desc;
 467         struct nfs_page *req, *tmp;
 468         LIST_HEAD(reqs);
 469         struct nfs_commit_info cinfo;
 470         LIST_HEAD(failed);
 471
 472         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 473         pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
 474         spin_lock(cinfo.lock);
 475         nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
 476         spin_unlock(cinfo.lock);
 477
 478         dreq->count = 0;
 479         get_dreq(dreq);
 480
 481         nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE,
 482                               &nfs_direct_write_completion_ops);
 483         desc.pg_dreq = dreq;
 484
 485         list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
 486                 if (!nfs_pageio_add_request(&desc, req)) {
 487                         nfs_list_remove_request(req);
 488                         nfs_list_add_request(req, &failed);
 489                         spin_lock(cinfo.lock);
 490                         dreq->flags = 0;
 491                         dreq->error = -EIO;
 492                         spin_unlock(cinfo.lock);
 493                 }
 494                 nfs_release_request(req);
 495         }
 496         nfs_pageio_complete(&desc);
 497
 498         while (!list_empty(&failed)) {
 499                 req = nfs_list_entry(failed.next);
 500                 nfs_list_remove_request(req);
 501                 nfs_unlock_and_release_request(req);
 502         }
 503
 504         if (put_dreq(dreq))
 505                 nfs_direct_write_complete(dreq, dreq->inode);
 506 }
 507
 508 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
 509 {
 510         struct nfs_direct_req *dreq = data->dreq;
 511         struct nfs_commit_info cinfo;
 512         struct nfs_page *req;
 513         int status = data->task.tk_status;
 514
 515         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 516         if (status < 0) {
 517                 dprintk("NFS: %5u commit failed with error %d.\n",
 518                         data->task.tk_pid, status);
 519                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 520         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
 521                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
 522                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 523         }
 524
 525         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
 526         while (!list_empty(&data->pages)) {
 527                 req = nfs_list_entry(data->pages.next);
 528                 nfs_list_remove_request(req);
 529                 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
 530                         /* Note the rewrite will go through mds */
 531                         nfs_mark_request_commit(req, NULL, &cinfo);
 532                 } else
 533                         nfs_release_request(req);
 534                 nfs_unlock_and_release_request(req);
 535         }
 536
 537         if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
 538                 nfs_direct_write_complete(dreq, data->inode);
 539 }
 540
 541 static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
 542 {
 543         /* There is no lock to clear */
 544 }
 545
 546 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
 547         .completion = nfs_direct_commit_complete,
 548         .error_cleanup = nfs_direct_error_cleanup,
 549 };
 550
 551 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 552 {
 553         int res;
 554         struct nfs_commit_info cinfo;
 555         LIST_HEAD(mds_list);
 556
 557         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 558         nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
 559         res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
 560         if (res < 0) /* res == -ENOMEM */
 561                 nfs_direct_write_reschedule(dreq);
 562 }
 563
 564 static void nfs_direct_write_schedule_work(struct work_struct *work)
 565 {
 566         struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
 567         int flags = dreq->flags;
 568
 569         dreq->flags = 0;
 570         switch (flags) {
 571                 case NFS_ODIRECT_DO_COMMIT:
 572                         nfs_direct_commit_schedule(dreq);
 573                         break;
 574                 case NFS_ODIRECT_RESCHED_WRITES:
 575                         nfs_direct_write_reschedule(dreq);
 576                         break;
 577                 default:
 578                         nfs_inode_dio_write_done(dreq->inode);
 579                         nfs_direct_complete(dreq);
 580         }
 581 }
 582
 583 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 584 {
 585         schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
 586 }
 587
 588 #else
 589 static void nfs_direct_write_schedule_work(struct work_struct *work)
 590 {
 591 }
 592
 593 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 594 {
 595         nfs_inode_dio_write_done(inode);
 596         nfs_direct_complete(dreq);
 597 }
 598 #endif
 599
 600 /*
 601  * NB: Return the value of the first error return code.  Subsequent
 602  *     errors after the first one are ignored.
 603  */
 604 /*
 605  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
 606  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
 607  * bail and stop sending more writes.  Write length accounting is
 608  * handled automatically by nfs_direct_write_result().  Otherwise, if
 609  * no requests have been sent, just return an error.
 610  */
 611 static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
 612                                                  const struct iovec *iov,
 613                                                  loff_t pos)
 614 {
 615         struct nfs_direct_req *dreq = desc->pg_dreq;
 616         struct nfs_open_context *ctx = dreq->ctx;
 617         struct inode *inode = ctx->dentry->d_inode;
 618         unsigned long user_addr = (unsigned long)iov->iov_base;
 619         size_t count = iov->iov_len;
 620         size_t wsize = NFS_SERVER(inode)->wsize;
 621         unsigned int pgbase;
 622         int result;
 623         ssize_t started = 0;
 624         struct page **pagevec = NULL;
 625         unsigned int npages;
 626
 627         do {
 628                 size_t bytes;
 629                 int i;
 630
 631                 pgbase = user_addr & ~PAGE_MASK;
 632                 bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
 633
 634                 result = -ENOMEM;
 635                 npages = nfs_page_array_len(pgbase, bytes);
 636                 if (!pagevec)
 637                         pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
 638                 if (!pagevec)
 639                         break;
 640
 641                 down_read(&current->mm->mmap_sem);
 642                 result = get_user_pages(current, current->mm, user_addr,
 643                                         npages, 0, 0, pagevec, NULL);
 644                 up_read(&current->mm->mmap_sem);
 645                 if (result < 0)
 646                         break;
 647
 648                 if ((unsigned)result < npages) {
 649                         bytes = result * PAGE_SIZE;
 650                         if (bytes <= pgbase) {
 651                                 nfs_direct_release_pages(pagevec, result);
 652                                 break;
 653                         }
 654                         bytes -= pgbase;
 655                         npages = result;
 656                 }
 657
 658                 for (i = 0; i < npages; i++) {
 659                         struct nfs_page *req;
 660                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 661
 662                         req = nfs_create_request(dreq->ctx, dreq->inode,
 663                                                  pagevec[i],
 664                                                  pgbase, req_len);
 665                         if (IS_ERR(req)) {
 666                                 result = PTR_ERR(req);
 667                                 break;
 668                         }
 669                         nfs_lock_request(req);
 670                         req->wb_index = pos >> PAGE_SHIFT;
 671                         req->wb_offset = pos & ~PAGE_MASK;
 672                         if (!nfs_pageio_add_request(desc, req)) {
 673                                 result = desc->pg_error;
 674                                 nfs_unlock_and_release_request(req);
 675                                 break;
 676                         }
 677                         pgbase = 0;
 678                         bytes -= req_len;
 679                         started += req_len;
 680                         user_addr += req_len;
 681                         pos += req_len;
 682                         count -= req_len;
 683                 }
 684                 /* The nfs_page now hold references to these pages */
 685                 nfs_direct_release_pages(pagevec, npages);
 686         } while (count != 0 && result >= 0);
 687
 688         kfree(pagevec);
 689
 690         if (started)
 691                 return started;
 692         return result < 0 ? (ssize_t) result : -EFAULT;
 693 }
 694
 695 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 696 {
 697         struct nfs_direct_req *dreq = hdr->dreq;
 698         struct nfs_commit_info cinfo;
 699         int bit = -1;
 700         struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 701
 702         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 703                 goto out_put;
 704
 705         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 706
 707         spin_lock(&dreq->lock);
 708
 709         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 710                 dreq->flags = 0;
 711                 dreq->error = hdr->error;
 712         }
 713         if (dreq->error != 0)
 714                 bit = NFS_IOHDR_ERROR;
 715         else {
 716                 dreq->count += hdr->good_bytes;
 717                 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
 718                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 719                         bit = NFS_IOHDR_NEED_RESCHED;
 720                 } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
 721                         if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
 722                                 bit = NFS_IOHDR_NEED_RESCHED;
 723                         else if (dreq->flags == 0) {
 724                                 memcpy(&dreq->verf, hdr->verf,
 725                                        sizeof(dreq->verf));
 726                                 bit = NFS_IOHDR_NEED_COMMIT;
 727                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
 728                         } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
 729                                 if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
 730                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 731                                         bit = NFS_IOHDR_NEED_RESCHED;
 732                                 } else
 733                                         bit = NFS_IOHDR_NEED_COMMIT;
 734                         }
 735                 }
 736         }
 737         spin_unlock(&dreq->lock);
 738
 739         while (!list_empty(&hdr->pages)) {
 740                 req = nfs_list_entry(hdr->pages.next);
 741                 nfs_list_remove_request(req);
 742                 switch (bit) {
 743                 case NFS_IOHDR_NEED_RESCHED:
 744                 case NFS_IOHDR_NEED_COMMIT:
 745                         kref_get(&req->wb_kref);
 746                         nfs_mark_request_commit(req, hdr->lseg, &cinfo);
 747                 }
 748                 nfs_unlock_and_release_request(req);
 749         }
 750
 751 out_put:
 752         if (put_dreq(dreq))
 753                 nfs_direct_write_complete(dreq, hdr->inode);
 754         hdr->release(hdr);
 755 }
 756
 757 static void nfs_write_sync_pgio_error(struct list_head *head)
 758 {
 759         struct nfs_page *req;
 760
 761         while (!list_empty(head)) {
 762                 req = nfs_list_entry(head->next);
 763                 nfs_list_remove_request(req);
 764                 nfs_unlock_and_release_request(req);
 765         }
 766 }
 767
 768 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
 769         .error_cleanup = nfs_write_sync_pgio_error,
 770         .init_hdr = nfs_direct_pgio_init,
 771         .completion = nfs_direct_write_completion,
 772 };
 773
 774 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 775                                                const struct iovec *iov,
 776                                                unsigned long nr_segs,
 777                                                loff_t pos)
 778 {
 779         struct nfs_pageio_descriptor desc;
 780         struct inode *inode = dreq->inode;
 781         ssize_t result = 0;
 782         size_t requested_bytes = 0;
 783         unsigned long seg;
 784
 785         nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE,
 786                               &nfs_direct_write_completion_ops);
 787         desc.pg_dreq = dreq;
 788         get_dreq(dreq);
 789         atomic_inc(&inode->i_dio_count);
 790
 791         for (seg = 0; seg < nr_segs; seg++) {
 792                 const struct iovec *vec = &iov[seg];
 793                 result = nfs_direct_write_schedule_segment(&desc, vec, pos);
 794                 if (result < 0)
 795                         break;
 796                 requested_bytes += result;
 797                 if ((size_t)result < vec->iov_len)
 798                         break;
 799                 pos += vec->iov_len;
 800         }
 801         nfs_pageio_complete(&desc);
 802         NFS_I(dreq->inode)->write_io += desc.pg_bytes_written;
 803
 804         /*
 805          * If no bytes were started, return the error, and let the
 806          * generic layer handle the completion.
 807          */
 808         if (requested_bytes == 0) {
 809                 inode_dio_done(inode);
 810                 nfs_direct_req_release(dreq);
 811                 return result < 0 ? result : -EIO;
 812         }
 813
 814         if (put_dreq(dreq))
 815                 nfs_direct_write_complete(dreq, dreq->inode);
 816         return 0;
 817 }
 818
 819 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
 820                                 unsigned long nr_segs, loff_t pos,
 821                                 size_t count)
 822 {
 823         ssize_t result = -ENOMEM;
 824         struct inode *inode = iocb->ki_filp->f_mapping->host;
 825         struct nfs_direct_req *dreq;
 826
 827         dreq = nfs_direct_req_alloc();
 828         if (!dreq)
 829                 goto out;
 830
 831         dreq->inode = inode;
 832         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 833         dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
 834         if (dreq->l_ctx == NULL)
 835                 goto out_release;
 836         if (!is_sync_kiocb(iocb))
 837                 dreq->iocb = iocb;
 838
 839         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos);
 840         if (!result)
 841                 result = nfs_direct_wait(dreq);
 842 out_release:
 843         nfs_direct_req_release(dreq);
 844 out:
 845         return result;
 846 }
 847
 848 /**
 849  * nfs_file_direct_read - file direct read operation for NFS files
 850  * @iocb: target I/O control block
 851  * @iov: vector of user buffers into which to read data
 852  * @nr_segs: size of iov vector
 853  * @pos: byte offset in file where reading starts
 854  *
 855  * We use this function for direct reads instead of calling
 856  * generic_file_aio_read() in order to avoid gfar's check to see if
 857  * the request starts before the end of the file.  For that check
 858  * to work, we must generate a GETATTR before each direct read, and
 859  * even then there is a window between the GETATTR and the subsequent
 860  * READ where the file size could change.  Our preference is simply
 861  * to do all reads the application wants, and the server will take
 862  * care of managing the end of file boundary.
 863  *
 864  * This function also eliminates unnecessarily updating the file's
 865  * atime locally, as the NFS server sets the file's atime, and this
 866  * client must read the updated atime from the server back into its
 867  * cache.
 868  */
 869 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
 870                                 unsigned long nr_segs, loff_t pos)
 871 {
 872         ssize_t retval = -EINVAL;
 873         struct file *file = iocb->ki_filp;
 874         struct address_space *mapping = file->f_mapping;
 875         size_t count;
 876
 877         count = iov_length(iov, nr_segs);
 878         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 879
 880         dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
 881                 file->f_path.dentry->d_parent->d_name.name,
 882                 file->f_path.dentry->d_name.name,
 883                 count, (long long) pos);
 884
 885         retval = 0;
 886         if (!count)
 887                 goto out;
 888
 889         retval = nfs_sync_mapping(mapping);
 890         if (retval)
 891                 goto out;
 892
 893         task_io_account_read(count);
 894
 895         retval = nfs_direct_read(iocb, iov, nr_segs, pos);
 896         if (retval > 0)
 897                 iocb->ki_pos = pos + retval;
 898
 899 out:
 900         return retval;
 901 }
 902
 903 /**
 904  * nfs_file_direct_write - file direct write operation for NFS files
 905  * @iocb: target I/O control block
 906  * @iov: vector of user buffers from which to write data
 907  * @nr_segs: size of iov vector
 908  * @pos: byte offset in file where writing starts
 909  *
 910  * We use this function for direct writes instead of calling
 911  * generic_file_aio_write() in order to avoid taking the inode
 912  * semaphore and updating the i_size.  The NFS server will set
 913  * the new i_size and this client must read the updated size
 914  * back into its cache.  We let the server do generic write
 915  * parameter checking and report problems.
 916  *
 917  * We eliminate local atime updates, see direct read above.
 918  *
 919  * We avoid unnecessary page cache invalidations for normal cached
 920  * readers of this file.
 921  *
 922  * Note that O_APPEND is not supported for NFS direct writes, as there
 923  * is no atomic O_APPEND write facility in the NFS protocol.
 924  */
 925 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 926                                 unsigned long nr_segs, loff_t pos)
 927 {
 928         ssize_t retval = -EINVAL;
 929         struct file *file = iocb->ki_filp;
 930         struct address_space *mapping = file->f_mapping;
 931         size_t count;
 932
 933         count = iov_length(iov, nr_segs);
 934         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 935
 936         dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
 937                 file->f_path.dentry->d_parent->d_name.name,
 938                 file->f_path.dentry->d_name.name,
 939                 count, (long long) pos);
 940
 941         retval = generic_write_checks(file, &pos, &count, 0);
 942         if (retval)
 943                 goto out;
 944
 945         retval = -EINVAL;
 946         if ((ssize_t) count < 0)
 947                 goto out;
 948         retval = 0;
 949         if (!count)
 950                 goto out;
 951
 952         retval = nfs_sync_mapping(mapping);
 953         if (retval)
 954                 goto out;
 955
 956         task_io_account_write(count);
 957
 958         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
 959         if (retval > 0) {
 960                 struct inode *inode = mapping->host;
 961
 962                 iocb->ki_pos = pos + retval;
 963                 spin_lock(&inode->i_lock);
 964                 if (i_size_read(inode) < iocb->ki_pos)
 965                         i_size_write(inode, iocb->ki_pos);
 966                 spin_unlock(&inode->i_lock);
 967         }
 968 out:
 969         return retval;
 970 }
 971
 972 /**
 973  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
 974  *
 975  */
 976 int __init nfs_init_directcache(void)
 977 {
 978         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
 979                                                 sizeof(struct nfs_direct_req),
 980                                                 0, (SLAB_RECLAIM_ACCOUNT|
 981                                                         SLAB_MEM_SPREAD),
 982                                                 NULL);
 983         if (nfs_direct_cachep == NULL)
 984                 return -ENOMEM;
 985
 986         return 0;
 987 }
 988
 989 /**
 990  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
 991  *
 992  */
 993 void nfs_destroy_directcache(void)
 994 {
 995         kmem_cache_destroy(nfs_direct_cachep);
 996 }