SAFE public projects git trees. - safe/jmp/linux-2.6/blob - fs/splice.c

   1 /*
   2  * "splice": joining two ropes together by interweaving their strands.
   3  *
   4  * This is the "extended pipe" functionality, where a pipe is used as
   5  * an arbitrary in-memory buffer. Think of a pipe as a small kernel
   6  * buffer that you can use to transfer data from one end to the other.
   7  *
   8  * The traditional unix read/write is extended with a "splice()" operation
   9  * that transfers data buffers to or from a pipe buffer.
  10  *
  11  * Named by Larry McVoy, original implementation from Linus, extended by
  12  * Jens to support splicing to files, network, direct splicing, etc and
  13  * fixing lots of bugs.
  14  *
  15  * Copyright (C) 2005-2006 Jens Axboe <axboe@suse.de>
  16  * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
  17  * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
  18  *
  19  */
  20 #include <linux/fs.h>
  21 #include <linux/file.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/pipe_fs_i.h>
  24 #include <linux/mm_inline.h>
  25 #include <linux/swap.h>
  26 #include <linux/writeback.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/module.h>
  29 #include <linux/syscalls.h>
  30 #include <linux/uio.h>
  31
  32 struct partial_page {
  33         unsigned int offset;
  34         unsigned int len;
  35 };
  36
  37 /*
  38  * Passed to splice_to_pipe
  39  */
  40 struct splice_pipe_desc {
  41         struct page **pages;            /* page map */
  42         struct partial_page *partial;   /* pages[] may not be contig */
  43         int nr_pages;                   /* number of pages in map */
  44         unsigned int flags;             /* splice flags */
  45         struct pipe_buf_operations *ops;/* ops associated with output pipe */
  46 };
  47
  48 /*
  49  * Attempt to steal a page from a pipe buffer. This should perhaps go into
  50  * a vm helper function, it's already simplified quite a bit by the
  51  * addition of remove_mapping(). If success is returned, the caller may
  52  * attempt to reuse this page for another destination.
  53  */
  54 static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
  55                                      struct pipe_buffer *buf)
  56 {
  57         struct page *page = buf->page;
  58         struct address_space *mapping = page_mapping(page);
  59
  60         lock_page(page);
  61
  62         WARN_ON(!PageUptodate(page));
  63
  64         /*
  65          * At least for ext2 with nobh option, we need to wait on writeback
  66          * completing on this page, since we'll remove it from the pagecache.
  67          * Otherwise truncate wont wait on the page, allowing the disk
  68          * blocks to be reused by someone else before we actually wrote our
  69          * data to them. fs corruption ensues.
  70          */
  71         wait_on_page_writeback(page);
  72
  73         if (PagePrivate(page))
  74                 try_to_release_page(page, mapping_gfp_mask(mapping));
  75
  76         if (!remove_mapping(mapping, page)) {
  77                 unlock_page(page);
  78                 return 1;
  79         }
  80
  81         return 0;
  82 }
  83
  84 static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
  85                                         struct pipe_buffer *buf)
  86 {
  87         page_cache_release(buf->page);
  88 }
  89
  90 static int page_cache_pipe_buf_pin(struct pipe_inode_info *info,
  91                                    struct pipe_buffer *buf)
  92 {
  93         struct page *page = buf->page;
  94         int err;
  95
  96         if (!PageUptodate(page)) {
  97                 lock_page(page);
  98
  99                 /*
 100                  * Page got truncated/unhashed. This will cause a 0-byte
 101                  * splice, if this is the first page.
 102                  */
 103                 if (!page->mapping) {
 104                         err = -ENODATA;
 105                         goto error;
 106                 }
 107
 108                 /*
 109                  * Uh oh, read-error from disk.
 110                  */
 111                 if (!PageUptodate(page)) {
 112                         err = -EIO;
 113                         goto error;
 114                 }
 115
 116                 /*
 117                  * Page is ok afterall, we are done.
 118                  */
 119                 unlock_page(page);
 120         }
 121
 122         return 0;
 123 error:
 124         unlock_page(page);
 125         return err;
 126 }
 127
 128 static struct pipe_buf_operations page_cache_pipe_buf_ops = {
 129         .can_merge = 0,
 130         .map = generic_pipe_buf_map,
 131         .unmap = generic_pipe_buf_unmap,
 132         .pin = page_cache_pipe_buf_pin,
 133         .release = page_cache_pipe_buf_release,
 134         .steal = page_cache_pipe_buf_steal,
 135         .get = generic_pipe_buf_get,
 136 };
 137
 138 static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
 139                                     struct pipe_buffer *buf)
 140 {
 141         if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
 142                 return 1;
 143
 144         return generic_pipe_buf_steal(pipe, buf);
 145 }
 146
 147 static struct pipe_buf_operations user_page_pipe_buf_ops = {
 148         .can_merge = 0,
 149         .map = generic_pipe_buf_map,
 150         .unmap = generic_pipe_buf_unmap,
 151         .pin = generic_pipe_buf_pin,
 152         .release = page_cache_pipe_buf_release,
 153         .steal = user_page_pipe_buf_steal,
 154         .get = generic_pipe_buf_get,
 155 };
 156
 157 /*
 158  * Pipe output worker. This sets up our pipe format with the page cache
 159  * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
 160  */
 161 static ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
 162                               struct splice_pipe_desc *spd)
 163 {
 164         int ret, do_wakeup, page_nr;
 165
 166         ret = 0;
 167         do_wakeup = 0;
 168         page_nr = 0;
 169
 170         if (pipe->inode)
 171                 mutex_lock(&pipe->inode->i_mutex);
 172
 173         for (;;) {
 174                 if (!pipe->readers) {
 175                         send_sig(SIGPIPE, current, 0);
 176                         if (!ret)
 177                                 ret = -EPIPE;
 178                         break;
 179                 }
 180
 181                 if (pipe->nrbufs < PIPE_BUFFERS) {
 182                         int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
 183                         struct pipe_buffer *buf = pipe->bufs + newbuf;
 184
 185                         buf->page = spd->pages[page_nr];
 186                         buf->offset = spd->partial[page_nr].offset;
 187                         buf->len = spd->partial[page_nr].len;
 188                         buf->ops = spd->ops;
 189                         if (spd->flags & SPLICE_F_GIFT)
 190                                 buf->flags |= PIPE_BUF_FLAG_GIFT;
 191
 192                         pipe->nrbufs++;
 193                         page_nr++;
 194                         ret += buf->len;
 195
 196                         if (pipe->inode)
 197                                 do_wakeup = 1;
 198
 199                         if (!--spd->nr_pages)
 200                                 break;
 201                         if (pipe->nrbufs < PIPE_BUFFERS)
 202                                 continue;
 203
 204                         break;
 205                 }
 206
 207                 if (spd->flags & SPLICE_F_NONBLOCK) {
 208                         if (!ret)
 209                                 ret = -EAGAIN;
 210                         break;
 211                 }
 212
 213                 if (signal_pending(current)) {
 214                         if (!ret)
 215                                 ret = -ERESTARTSYS;
 216                         break;
 217                 }
 218
 219                 if (do_wakeup) {
 220                         smp_mb();
 221                         if (waitqueue_active(&pipe->wait))
 222                                 wake_up_interruptible_sync(&pipe->wait);
 223                         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 224                         do_wakeup = 0;
 225                 }
 226
 227                 pipe->waiting_writers++;
 228                 pipe_wait(pipe);
 229                 pipe->waiting_writers--;
 230         }
 231
 232         if (pipe->inode)
 233                 mutex_unlock(&pipe->inode->i_mutex);
 234
 235         if (do_wakeup) {
 236                 smp_mb();
 237                 if (waitqueue_active(&pipe->wait))
 238                         wake_up_interruptible(&pipe->wait);
 239                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 240         }
 241
 242         while (page_nr < spd->nr_pages)
 243                 page_cache_release(spd->pages[page_nr++]);
 244
 245         return ret;
 246 }
 247
 248 static int
 249 __generic_file_splice_read(struct file *in, loff_t *ppos,
 250                            struct pipe_inode_info *pipe, size_t len,
 251                            unsigned int flags)
 252 {
 253         struct address_space *mapping = in->f_mapping;
 254         unsigned int loff, nr_pages;
 255         struct page *pages[PIPE_BUFFERS];
 256         struct partial_page partial[PIPE_BUFFERS];
 257         struct page *page;
 258         pgoff_t index, end_index;
 259         loff_t isize;
 260         size_t total_len;
 261         int error, page_nr;
 262         struct splice_pipe_desc spd = {
 263                 .pages = pages,
 264                 .partial = partial,
 265                 .flags = flags,
 266                 .ops = &page_cache_pipe_buf_ops,
 267         };
 268
 269         index = *ppos >> PAGE_CACHE_SHIFT;
 270         loff = *ppos & ~PAGE_CACHE_MASK;
 271         nr_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 272
 273         if (nr_pages > PIPE_BUFFERS)
 274                 nr_pages = PIPE_BUFFERS;
 275
 276         /*
 277          * Initiate read-ahead on this page range. however, don't call into
 278          * read-ahead if this is a non-zero offset (we are likely doing small
 279          * chunk splice and the page is already there) for a single page.
 280          */
 281         if (!loff || nr_pages > 1)
 282                 page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);
 283
 284         /*
 285          * Now fill in the holes:
 286          */
 287         error = 0;
 288         total_len = 0;
 289
 290         /*
 291          * Lookup the (hopefully) full range of pages we need.
 292          */
 293         spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
 294
 295         /*
 296          * If find_get_pages_contig() returned fewer pages than we needed,
 297          * allocate the rest.
 298          */
 299         index += spd.nr_pages;
 300         while (spd.nr_pages < nr_pages) {
 301                 /*
 302                  * Page could be there, find_get_pages_contig() breaks on
 303                  * the first hole.
 304                  */
 305                 page = find_get_page(mapping, index);
 306                 if (!page) {
 307                         /*
 308                          * Make sure the read-ahead engine is notified
 309                          * about this failure.
 310                          */
 311                         handle_ra_miss(mapping, &in->f_ra, index);
 312
 313                         /*
 314                          * page didn't exist, allocate one.
 315                          */
 316                         page = page_cache_alloc_cold(mapping);
 317                         if (!page)
 318                                 break;
 319
 320                         error = add_to_page_cache_lru(page, mapping, index,
 321                                               mapping_gfp_mask(mapping));
 322                         if (unlikely(error)) {
 323                                 page_cache_release(page);
 324                                 break;
 325                         }
 326                         /*
 327                          * add_to_page_cache() locks the page, unlock it
 328                          * to avoid convoluting the logic below even more.
 329                          */
 330                         unlock_page(page);
 331                 }
 332
 333                 pages[spd.nr_pages++] = page;
 334                 index++;
 335         }
 336
 337         /*
 338          * Now loop over the map and see if we need to start IO on any
 339          * pages, fill in the partial map, etc.
 340          */
 341         index = *ppos >> PAGE_CACHE_SHIFT;
 342         nr_pages = spd.nr_pages;
 343         spd.nr_pages = 0;
 344         for (page_nr = 0; page_nr < nr_pages; page_nr++) {
 345                 unsigned int this_len;
 346
 347                 if (!len)
 348                         break;
 349
 350                 /*
 351                  * this_len is the max we'll use from this page
 352                  */
 353                 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
 354                 page = pages[page_nr];
 355
 356                 /*
 357                  * If the page isn't uptodate, we may need to start io on it
 358                  */
 359                 if (!PageUptodate(page)) {
 360                         /*
 361                          * If in nonblock mode then dont block on waiting
 362                          * for an in-flight io page
 363                          */
 364                         if (flags & SPLICE_F_NONBLOCK)
 365                                 break;
 366
 367                         lock_page(page);
 368
 369                         /*
 370                          * page was truncated, stop here. if this isn't the
 371                          * first page, we'll just complete what we already
 372                          * added
 373                          */
 374                         if (!page->mapping) {
 375                                 unlock_page(page);
 376                                 break;
 377                         }
 378                         /*
 379                          * page was already under io and is now done, great
 380                          */
 381                         if (PageUptodate(page)) {
 382                                 unlock_page(page);
 383                                 goto fill_it;
 384                         }
 385
 386                         /*
 387                          * need to read in the page
 388                          */
 389                         error = mapping->a_ops->readpage(in, page);
 390                         if (unlikely(error)) {
 391                                 /*
 392                                  * We really should re-lookup the page here,
 393                                  * but it complicates things a lot. Instead
 394                                  * lets just do what we already stored, and
 395                                  * we'll get it the next time we are called.
 396                                  */
 397                                 if (error == AOP_TRUNCATED_PAGE)
 398                                         error = 0;
 399
 400                                 break;
 401                         }
 402
 403                         /*
 404                          * i_size must be checked after ->readpage().
 405                          */
 406                         isize = i_size_read(mapping->host);
 407                         end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
 408                         if (unlikely(!isize || index > end_index))
 409                                 break;
 410
 411                         /*
 412                          * if this is the last page, see if we need to shrink
 413                          * the length and stop
 414                          */
 415                         if (end_index == index) {
 416                                 loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
 417                                 if (total_len + loff > isize)
 418                                         break;
 419                                 /*
 420                                  * force quit after adding this page
 421                                  */
 422                                 len = this_len;
 423                                 this_len = min(this_len, loff);
 424                                 loff = 0;
 425                         }
 426                 }
 427 fill_it:
 428                 partial[page_nr].offset = loff;
 429                 partial[page_nr].len = this_len;
 430                 len -= this_len;
 431                 total_len += this_len;
 432                 loff = 0;
 433                 spd.nr_pages++;
 434                 index++;
 435         }
 436
 437         /*
 438          * Release any pages at the end, if we quit early. 'i' is how far
 439          * we got, 'nr_pages' is how many pages are in the map.
 440          */
 441         while (page_nr < nr_pages)
 442                 page_cache_release(pages[page_nr++]);
 443
 444         if (spd.nr_pages)
 445                 return splice_to_pipe(pipe, &spd);
 446
 447         return error;
 448 }
 449
 450 /**
 451  * generic_file_splice_read - splice data from file to a pipe
 452  * @in:         file to splice from
 453  * @pipe:       pipe to splice to
 454  * @len:        number of bytes to splice
 455  * @flags:      splice modifier flags
 456  *
 457  * Will read pages from given file and fill them into a pipe.
 458  */
 459 ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
 460                                  struct pipe_inode_info *pipe, size_t len,
 461                                  unsigned int flags)
 462 {
 463         ssize_t spliced;
 464         int ret;
 465
 466         ret = 0;
 467         spliced = 0;
 468
 469         while (len) {
 470                 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
 471
 472                 if (ret < 0)
 473                         break;
 474                 else if (!ret) {
 475                         if (spliced)
 476                                 break;
 477                         if (flags & SPLICE_F_NONBLOCK) {
 478                                 ret = -EAGAIN;
 479                                 break;
 480                         }
 481                 }
 482
 483                 *ppos += ret;
 484                 len -= ret;
 485                 spliced += ret;
 486         }
 487
 488         if (spliced)
 489                 return spliced;
 490
 491         return ret;
 492 }
 493
 494 EXPORT_SYMBOL(generic_file_splice_read);
 495
 496 /*
 497  * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
 498  * using sendpage(). Return the number of bytes sent.
 499  */
 500 static int pipe_to_sendpage(struct pipe_inode_info *info,
 501                             struct pipe_buffer *buf, struct splice_desc *sd)
 502 {
 503         struct file *file = sd->file;
 504         loff_t pos = sd->pos;
 505         int ret, more;
 506
 507         ret = buf->ops->pin(info, buf);
 508         if (!ret) {
 509                 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
 510
 511                 ret = file->f_op->sendpage(file, buf->page, buf->offset,
 512                                            sd->len, &pos, more);
 513         }
 514
 515         return ret;
 516 }
 517
 518 /*
 519  * This is a little more tricky than the file -> pipe splicing. There are
 520  * basically three cases:
 521  *
 522  *      - Destination page already exists in the address space and there
 523  *        are users of it. For that case we have no other option that
 524  *        copying the data. Tough luck.
 525  *      - Destination page already exists in the address space, but there
 526  *        are no users of it. Make sure it's uptodate, then drop it. Fall
 527  *        through to last case.
 528  *      - Destination page does not exist, we can add the pipe page to
 529  *        the page cache and avoid the copy.
 530  *
 531  * If asked to move pages to the output file (SPLICE_F_MOVE is set in
 532  * sd->flags), we attempt to migrate pages from the pipe to the output
 533  * file address space page cache. This is possible if no one else has
 534  * the pipe page referenced outside of the pipe and page cache. If
 535  * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
 536  * a new page in the output file page cache and fill/dirty that.
 537  */
 538 static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
 539                         struct splice_desc *sd)
 540 {
 541         struct file *file = sd->file;
 542         struct address_space *mapping = file->f_mapping;
 543         gfp_t gfp_mask = mapping_gfp_mask(mapping);
 544         unsigned int offset, this_len;
 545         struct page *page;
 546         pgoff_t index;
 547         int ret;
 548
 549         /*
 550          * make sure the data in this buffer is uptodate
 551          */
 552         ret = buf->ops->pin(info, buf);
 553         if (unlikely(ret))
 554                 return ret;
 555
 556         index = sd->pos >> PAGE_CACHE_SHIFT;
 557         offset = sd->pos & ~PAGE_CACHE_MASK;
 558
 559         this_len = sd->len;
 560         if (this_len + offset > PAGE_CACHE_SIZE)
 561                 this_len = PAGE_CACHE_SIZE - offset;
 562
 563         /*
 564          * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full
 565          * page.
 566          */
 567         if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
 568                 /*
 569                  * If steal succeeds, buf->page is now pruned from the vm
 570                  * side (page cache) and we can reuse it. The page will also
 571                  * be locked on successful return.
 572                  */
 573                 if (buf->ops->steal(info, buf))
 574                         goto find_page;
 575
 576                 page = buf->page;
 577                 page_cache_get(page);
 578
 579                 /*
 580                  * page must be on the LRU for adding to the pagecache.
 581                  * Check this without grabbing the zone lock, if it isn't
 582                  * the do grab the zone lock, recheck, and add if necessary.
 583                  */
 584                 if (!PageLRU(page)) {
 585                         struct zone *zone = page_zone(page);
 586
 587                         spin_lock_irq(&zone->lru_lock);
 588                         if (!PageLRU(page)) {
 589                                 SetPageLRU(page);
 590                                 add_page_to_inactive_list(zone, page);
 591                         }
 592                         spin_unlock_irq(&zone->lru_lock);
 593                 }
 594
 595                 if (add_to_page_cache(page, mapping, index, gfp_mask)) {
 596                         page_cache_release(page);
 597                         unlock_page(page);
 598                         goto find_page;
 599                 }
 600         } else {
 601 find_page:
 602                 page = find_lock_page(mapping, index);
 603                 if (!page) {
 604                         ret = -ENOMEM;
 605                         page = page_cache_alloc_cold(mapping);
 606                         if (unlikely(!page))
 607                                 goto out_nomem;
 608
 609                         /*
 610                          * This will also lock the page
 611                          */
 612                         ret = add_to_page_cache_lru(page, mapping, index,
 613                                                     gfp_mask);
 614                         if (unlikely(ret))
 615                                 goto out;
 616                 }
 617
 618                 /*
 619                  * We get here with the page locked. If the page is also
 620                  * uptodate, we don't need to do more. If it isn't, we
 621                  * may need to bring it in if we are not going to overwrite
 622                  * the full page.
 623                  */
 624                 if (!PageUptodate(page)) {
 625                         if (this_len < PAGE_CACHE_SIZE) {
 626                                 ret = mapping->a_ops->readpage(file, page);
 627                                 if (unlikely(ret))
 628                                         goto out;
 629
 630                                 lock_page(page);
 631
 632                                 if (!PageUptodate(page)) {
 633                                         /*
 634                                          * Page got invalidated, repeat.
 635                                          */
 636                                         if (!page->mapping) {
 637                                                 unlock_page(page);
 638                                                 page_cache_release(page);
 639                                                 goto find_page;
 640                                         }
 641                                         ret = -EIO;
 642                                         goto out;
 643                                 }
 644                         } else
 645                                 SetPageUptodate(page);
 646                 }
 647         }
 648
 649         ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
 650         if (unlikely(ret)) {
 651                 loff_t isize = i_size_read(mapping->host);
 652
 653                 if (ret != AOP_TRUNCATED_PAGE)
 654                         unlock_page(page);
 655                 page_cache_release(page);
 656                 if (ret == AOP_TRUNCATED_PAGE)
 657                         goto find_page;
 658
 659                 /*
 660                  * prepare_write() may have instantiated a few blocks
 661                  * outside i_size.  Trim these off again.
 662                  */
 663                 if (sd->pos + this_len > isize)
 664                         vmtruncate(mapping->host, isize);
 665
 666                 goto out;
 667         }
 668
 669         if (buf->page != page) {
 670                 /*
 671                  * Careful, ->map() uses KM_USER0!
 672                  */
 673                 char *src = buf->ops->map(info, buf, 1);
 674                 char *dst = kmap_atomic(page, KM_USER1);
 675
 676                 memcpy(dst + offset, src + buf->offset, this_len);
 677                 flush_dcache_page(page);
 678                 kunmap_atomic(dst, KM_USER1);
 679                 buf->ops->unmap(info, buf, src);
 680         }
 681
 682         ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
 683         if (!ret) {
 684                 /*
 685                  * Return the number of bytes written and mark page as
 686                  * accessed, we are now done!
 687                  */
 688                 ret = this_len;
 689                 mark_page_accessed(page);
 690                 balance_dirty_pages_ratelimited(mapping);
 691         } else if (ret == AOP_TRUNCATED_PAGE) {
 692                 page_cache_release(page);
 693                 goto find_page;
 694         }
 695 out:
 696         page_cache_release(page);
 697         unlock_page(page);
 698 out_nomem:
 699         return ret;
 700 }
 701
 702 /*
 703  * Pipe input worker. Most of this logic works like a regular pipe, the
 704  * key here is the 'actor' worker passed in that actually moves the data
 705  * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
 706  */
 707 ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
 708                          loff_t *ppos, size_t len, unsigned int flags,
 709                          splice_actor *actor)
 710 {
 711         int ret, do_wakeup, err;
 712         struct splice_desc sd;
 713
 714         ret = 0;
 715         do_wakeup = 0;
 716
 717         sd.total_len = len;
 718         sd.flags = flags;
 719         sd.file = out;
 720         sd.pos = *ppos;
 721
 722         if (pipe->inode)
 723                 mutex_lock(&pipe->inode->i_mutex);
 724
 725         for (;;) {
 726                 if (pipe->nrbufs) {
 727                         struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
 728                         struct pipe_buf_operations *ops = buf->ops;
 729
 730                         sd.len = buf->len;
 731                         if (sd.len > sd.total_len)
 732                                 sd.len = sd.total_len;
 733
 734                         err = actor(pipe, buf, &sd);
 735                         if (err <= 0) {
 736                                 if (!ret && err != -ENODATA)
 737                                         ret = err;
 738
 739                                 break;
 740                         }
 741
 742                         ret += err;
 743                         buf->offset += err;
 744                         buf->len -= err;
 745
 746                         sd.len -= err;
 747                         sd.pos += err;
 748                         sd.total_len -= err;
 749                         if (sd.len)
 750                                 continue;
 751
 752                         if (!buf->len) {
 753                                 buf->ops = NULL;
 754                                 ops->release(pipe, buf);
 755                                 pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
 756                                 pipe->nrbufs--;
 757                                 if (pipe->inode)
 758                                         do_wakeup = 1;
 759                         }
 760
 761                         if (!sd.total_len)
 762                                 break;
 763                 }
 764
 765                 if (pipe->nrbufs)
 766                         continue;
 767                 if (!pipe->writers)
 768                         break;
 769                 if (!pipe->waiting_writers) {
 770                         if (ret)
 771                                 break;
 772                 }
 773
 774                 if (flags & SPLICE_F_NONBLOCK) {
 775                         if (!ret)
 776                                 ret = -EAGAIN;
 777                         break;
 778                 }
 779
 780                 if (signal_pending(current)) {
 781                         if (!ret)
 782                                 ret = -ERESTARTSYS;
 783                         break;
 784                 }
 785
 786                 if (do_wakeup) {
 787                         smp_mb();
 788                         if (waitqueue_active(&pipe->wait))
 789                                 wake_up_interruptible_sync(&pipe->wait);
 790                         kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 791                         do_wakeup = 0;
 792                 }
 793
 794                 pipe_wait(pipe);
 795         }
 796
 797         if (pipe->inode)
 798                 mutex_unlock(&pipe->inode->i_mutex);
 799
 800         if (do_wakeup) {
 801                 smp_mb();
 802                 if (waitqueue_active(&pipe->wait))
 803                         wake_up_interruptible(&pipe->wait);
 804                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 805         }
 806
 807         return ret;
 808 }
 809
 810 /**
 811  * generic_file_splice_write - splice data from a pipe to a file
 812  * @pipe:       pipe info
 813  * @out:        file to write to
 814  * @len:        number of bytes to splice
 815  * @flags:      splice modifier flags
 816  *
 817  * Will either move or copy pages (determined by @flags options) from
 818  * the given pipe inode to the given file.
 819  *
 820  */
 821 ssize_t
 822 generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 823                           loff_t *ppos, size_t len, unsigned int flags)
 824 {
 825         struct address_space *mapping = out->f_mapping;
 826         ssize_t ret;
 827
 828         ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
 829         if (ret > 0) {
 830                 struct inode *inode = mapping->host;
 831
 832                 *ppos += ret;
 833
 834                 /*
 835                  * If file or inode is SYNC and we actually wrote some data,
 836                  * sync it.
 837                  */
 838                 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
 839                         int err;
 840
 841                         mutex_lock(&inode->i_mutex);
 842                         err = generic_osync_inode(inode, mapping,
 843                                                   OSYNC_METADATA|OSYNC_DATA);
 844                         mutex_unlock(&inode->i_mutex);
 845
 846                         if (err)
 847                                 ret = err;
 848                 }
 849         }
 850
 851         return ret;
 852 }
 853
 854 EXPORT_SYMBOL(generic_file_splice_write);
 855
 856 /**
 857  * generic_splice_sendpage - splice data from a pipe to a socket
 858  * @inode:      pipe inode
 859  * @out:        socket to write to
 860  * @len:        number of bytes to splice
 861  * @flags:      splice modifier flags
 862  *
 863  * Will send @len bytes from the pipe to a network socket. No data copying
 864  * is involved.
 865  *
 866  */
 867 ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
 868                                 loff_t *ppos, size_t len, unsigned int flags)
 869 {
 870         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
 871 }
 872
 873 EXPORT_SYMBOL(generic_splice_sendpage);
 874
 875 /*
 876  * Attempt to initiate a splice from pipe to file.
 877  */
 878 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 879                            loff_t *ppos, size_t len, unsigned int flags)
 880 {
 881         int ret;
 882
 883         if (unlikely(!out->f_op || !out->f_op->splice_write))
 884                 return -EINVAL;
 885
 886         if (unlikely(!(out->f_mode & FMODE_WRITE)))
 887                 return -EBADF;
 888
 889         ret = rw_verify_area(WRITE, out, ppos, len);
 890         if (unlikely(ret < 0))
 891                 return ret;
 892
 893         return out->f_op->splice_write(pipe, out, ppos, len, flags);
 894 }
 895
 896 /*
 897  * Attempt to initiate a splice from a file to a pipe.
 898  */
 899 static long do_splice_to(struct file *in, loff_t *ppos,
 900                          struct pipe_inode_info *pipe, size_t len,
 901                          unsigned int flags)
 902 {
 903         loff_t isize, left;
 904         int ret;
 905
 906         if (unlikely(!in->f_op || !in->f_op->splice_read))
 907                 return -EINVAL;
 908
 909         if (unlikely(!(in->f_mode & FMODE_READ)))
 910                 return -EBADF;
 911
 912         ret = rw_verify_area(READ, in, ppos, len);
 913         if (unlikely(ret < 0))
 914                 return ret;
 915
 916         isize = i_size_read(in->f_mapping->host);
 917         if (unlikely(*ppos >= isize))
 918                 return 0;
 919
 920         left = isize - *ppos;
 921         if (unlikely(left < len))
 922                 len = left;
 923
 924         return in->f_op->splice_read(in, ppos, pipe, len, flags);
 925 }
 926
 927 long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
 928                       size_t len, unsigned int flags)
 929 {
 930         struct pipe_inode_info *pipe;
 931         long ret, bytes;
 932         loff_t out_off;
 933         umode_t i_mode;
 934         int i;
 935
 936         /*
 937          * We require the input being a regular file, as we don't want to
 938          * randomly drop data for eg socket -> socket splicing. Use the
 939          * piped splicing for that!
 940          */
 941         i_mode = in->f_dentry->d_inode->i_mode;
 942         if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
 943                 return -EINVAL;
 944
 945         /*
 946          * neither in nor out is a pipe, setup an internal pipe attached to
 947          * 'out' and transfer the wanted data from 'in' to 'out' through that
 948          */
 949         pipe = current->splice_pipe;
 950         if (unlikely(!pipe)) {
 951                 pipe = alloc_pipe_info(NULL);
 952                 if (!pipe)
 953                         return -ENOMEM;
 954
 955                 /*
 956                  * We don't have an immediate reader, but we'll read the stuff
 957                  * out of the pipe right after the splice_to_pipe(). So set
 958                  * PIPE_READERS appropriately.
 959                  */
 960                 pipe->readers = 1;
 961
 962                 current->splice_pipe = pipe;
 963         }
 964
 965         /*
 966          * Do the splice.
 967          */
 968         ret = 0;
 969         bytes = 0;
 970         out_off = 0;
 971
 972         while (len) {
 973                 size_t read_len, max_read_len;
 974
 975                 /*
 976                  * Do at most PIPE_BUFFERS pages worth of transfer:
 977                  */
 978                 max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
 979
 980                 ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
 981                 if (unlikely(ret < 0))
 982                         goto out_release;
 983
 984                 read_len = ret;
 985
 986                 /*
 987                  * NOTE: nonblocking mode only applies to the input. We
 988                  * must not do the output in nonblocking mode as then we
 989                  * could get stuck data in the internal pipe:
 990                  */
 991                 ret = do_splice_from(pipe, out, &out_off, read_len,
 992                                      flags & ~SPLICE_F_NONBLOCK);
 993                 if (unlikely(ret < 0))
 994                         goto out_release;
 995
 996                 bytes += ret;
 997                 len -= ret;
 998
 999                 /*
1000                  * In nonblocking mode, if we got back a short read then
1001                  * that was due to either an IO error or due to the
1002                  * pagecache entry not being there. In the IO error case
1003                  * the _next_ splice attempt will produce a clean IO error
1004                  * return value (not a short read), so in both cases it's
1005                  * correct to break out of the loop here:
1006                  */
1007                 if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
1008                         break;
1009         }
1010
1011         pipe->nrbufs = pipe->curbuf = 0;
1012
1013         return bytes;
1014
1015 out_release:
1016         /*
1017          * If we did an incomplete transfer we must release
1018          * the pipe buffers in question:
1019          */
1020         for (i = 0; i < PIPE_BUFFERS; i++) {
1021                 struct pipe_buffer *buf = pipe->bufs + i;
1022
1023                 if (buf->ops) {
1024                         buf->ops->release(pipe, buf);
1025                         buf->ops = NULL;
1026                 }
1027         }
1028         pipe->nrbufs = pipe->curbuf = 0;
1029
1030         /*
1031          * If we transferred some data, return the number of bytes:
1032          */
1033         if (bytes > 0)
1034                 return bytes;
1035
1036         return ret;
1037 }
1038
1039 EXPORT_SYMBOL(do_splice_direct);
1040
1041 /*
1042  * Determine where to splice to/from.
1043  */
1044 static long do_splice(struct file *in, loff_t __user *off_in,
1045                       struct file *out, loff_t __user *off_out,
1046                       size_t len, unsigned int flags)
1047 {
1048         struct pipe_inode_info *pipe;
1049         loff_t offset, *off;
1050         long ret;
1051
1052         pipe = in->f_dentry->d_inode->i_pipe;
1053         if (pipe) {
1054                 if (off_in)
1055                         return -ESPIPE;
1056                 if (off_out) {
1057                         if (out->f_op->llseek == no_llseek)
1058                                 return -EINVAL;
1059                         if (copy_from_user(&offset, off_out, sizeof(loff_t)))
1060                                 return -EFAULT;
1061                         off = &offset;
1062                 } else
1063                         off = &out->f_pos;
1064
1065                 ret = do_splice_from(pipe, out, off, len, flags);
1066
1067                 if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
1068                         ret = -EFAULT;
1069
1070                 return ret;
1071         }
1072
1073         pipe = out->f_dentry->d_inode->i_pipe;
1074         if (pipe) {
1075                 if (off_out)
1076                         return -ESPIPE;
1077                 if (off_in) {
1078                         if (in->f_op->llseek == no_llseek)
1079                                 return -EINVAL;
1080                         if (copy_from_user(&offset, off_in, sizeof(loff_t)))
1081                                 return -EFAULT;
1082                         off = &offset;
1083                 } else
1084                         off = &in->f_pos;
1085
1086                 ret = do_splice_to(in, off, pipe, len, flags);
1087
1088                 if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
1089                         ret = -EFAULT;
1090
1091                 return ret;
1092         }
1093
1094         return -EINVAL;
1095 }
1096
1097 /*
1098  * Map an iov into an array of pages and offset/length tupples. With the
1099  * partial_page structure, we can map several non-contiguous ranges into
1100  * our ones pages[] map instead of splitting that operation into pieces.
1101  * Could easily be exported as a generic helper for other users, in which
1102  * case one would probably want to add a 'max_nr_pages' parameter as well.
1103  */
1104 static int get_iovec_page_array(const struct iovec __user *iov,
1105                                 unsigned int nr_vecs, struct page **pages,
1106                                 struct partial_page *partial, int aligned)
1107 {
1108         int buffers = 0, error = 0;
1109
1110         /*
1111          * It's ok to take the mmap_sem for reading, even
1112          * across a "get_user()".
1113          */
1114         down_read(&current->mm->mmap_sem);
1115
1116         while (nr_vecs) {
1117                 unsigned long off, npages;
1118                 void __user *base;
1119                 size_t len;
1120                 int i;
1121
1122                 /*
1123                  * Get user address base and length for this iovec.
1124                  */
1125                 error = get_user(base, &iov->iov_base);
1126                 if (unlikely(error))
1127                         break;
1128                 error = get_user(len, &iov->iov_len);
1129                 if (unlikely(error))
1130                         break;
1131
1132                 /*
1133                  * Sanity check this iovec. 0 read succeeds.
1134                  */
1135                 if (unlikely(!len))
1136                         break;
1137                 error = -EFAULT;
1138                 if (unlikely(!base))
1139                         break;
1140
1141                 /*
1142                  * Get this base offset and number of pages, then map
1143                  * in the user pages.
1144                  */
1145                 off = (unsigned long) base & ~PAGE_MASK;
1146
1147                 /*
1148                  * If asked for alignment, the offset must be zero and the
1149                  * length a multiple of the PAGE_SIZE.
1150                  */
1151                 error = -EINVAL;
1152                 if (aligned && (off || len & ~PAGE_MASK))
1153                         break;
1154
1155                 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1156                 if (npages > PIPE_BUFFERS - buffers)
1157                         npages = PIPE_BUFFERS - buffers;
1158
1159                 error = get_user_pages(current, current->mm,
1160                                        (unsigned long) base, npages, 0, 0,
1161                                        &pages[buffers], NULL);
1162
1163                 if (unlikely(error <= 0))
1164                         break;
1165
1166                 /*
1167                  * Fill this contiguous range into the partial page map.
1168                  */
1169                 for (i = 0; i < error; i++) {
1170                         const int plen = min_t(size_t, len, PAGE_SIZE - off);
1171
1172                         partial[buffers].offset = off;
1173                         partial[buffers].len = plen;
1174
1175                         off = 0;
1176                         len -= plen;
1177                         buffers++;
1178                 }
1179
1180                 /*
1181                  * We didn't complete this iov, stop here since it probably
1182                  * means we have to move some of this into a pipe to
1183                  * be able to continue.
1184                  */
1185                 if (len)
1186                         break;
1187
1188                 /*
1189                  * Don't continue if we mapped fewer pages than we asked for,
1190                  * or if we mapped the max number of pages that we have
1191                  * room for.
1192                  */
1193                 if (error < npages || buffers == PIPE_BUFFERS)
1194                         break;
1195
1196                 nr_vecs--;
1197                 iov++;
1198         }
1199
1200         up_read(&current->mm->mmap_sem);
1201
1202         if (buffers)
1203                 return buffers;
1204
1205         return error;
1206 }
1207
1208 /*
1209  * vmsplice splices a user address range into a pipe. It can be thought of
1210  * as splice-from-memory, where the regular splice is splice-from-file (or
1211  * to file). In both cases the output is a pipe, naturally.
1212  *
1213  * Note that vmsplice only supports splicing _from_ user memory to a pipe,
1214  * not the other way around. Splicing from user memory is a simple operation
1215  * that can be supported without any funky alignment restrictions or nasty
1216  * vm tricks. We simply map in the user memory and fill them into a pipe.
1217  * The reverse isn't quite as easy, though. There are two possible solutions
1218  * for that:
1219  *
1220  *      - memcpy() the data internally, at which point we might as well just
1221  *        do a regular read() on the buffer anyway.
1222  *      - Lots of nasty vm tricks, that are neither fast nor flexible (it
1223  *        has restriction limitations on both ends of the pipe).
1224  *
1225  * Alas, it isn't here.
1226  *
1227  */
1228 static long do_vmsplice(struct file *file, const struct iovec __user *iov,
1229                         unsigned long nr_segs, unsigned int flags)
1230 {
1231         struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe;
1232         struct page *pages[PIPE_BUFFERS];
1233         struct partial_page partial[PIPE_BUFFERS];
1234         struct splice_pipe_desc spd = {
1235                 .pages = pages,
1236                 .partial = partial,
1237                 .flags = flags,
1238                 .ops = &user_page_pipe_buf_ops,
1239         };
1240
1241         if (unlikely(!pipe))
1242                 return -EBADF;
1243         if (unlikely(nr_segs > UIO_MAXIOV))
1244                 return -EINVAL;
1245         else if (unlikely(!nr_segs))
1246                 return 0;
1247
1248         spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
1249                                             flags & SPLICE_F_GIFT);
1250         if (spd.nr_pages <= 0)
1251                 return spd.nr_pages;
1252
1253         return splice_to_pipe(pipe, &spd);
1254 }
1255
1256 asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
1257                              unsigned long nr_segs, unsigned int flags)
1258 {
1259         struct file *file;
1260         long error;
1261         int fput;
1262
1263         error = -EBADF;
1264         file = fget_light(fd, &fput);
1265         if (file) {
1266                 if (file->f_mode & FMODE_WRITE)
1267                         error = do_vmsplice(file, iov, nr_segs, flags);
1268
1269                 fput_light(file, fput);
1270         }
1271
1272         return error;
1273 }
1274
1275 asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
1276                            int fd_out, loff_t __user *off_out,
1277                            size_t len, unsigned int flags)
1278 {
1279         long error;
1280         struct file *in, *out;
1281         int fput_in, fput_out;
1282
1283         if (unlikely(!len))
1284                 return 0;
1285
1286         error = -EBADF;
1287         in = fget_light(fd_in, &fput_in);
1288         if (in) {
1289                 if (in->f_mode & FMODE_READ) {
1290                         out = fget_light(fd_out, &fput_out);
1291                         if (out) {
1292                                 if (out->f_mode & FMODE_WRITE)
1293                                         error = do_splice(in, off_in,
1294                                                           out, off_out,
1295                                                           len, flags);
1296                                 fput_light(out, fput_out);
1297                         }
1298                 }
1299
1300                 fput_light(in, fput_in);
1301         }
1302
1303         return error;
1304 }
1305
1306 /*
1307  * Link contents of ipipe to opipe.
1308  */
1309 static int link_pipe(struct pipe_inode_info *ipipe,
1310                      struct pipe_inode_info *opipe,
1311                      size_t len, unsigned int flags)
1312 {
1313         struct pipe_buffer *ibuf, *obuf;
1314         int ret, do_wakeup, i, ipipe_first;
1315
1316         ret = do_wakeup = ipipe_first = 0;
1317
1318         /*
1319          * Potential ABBA deadlock, work around it by ordering lock
1320          * grabbing by inode address. Otherwise two different processes
1321          * could deadlock (one doing tee from A -> B, the other from B -> A).
1322          */
1323         if (ipipe->inode < opipe->inode) {
1324                 ipipe_first = 1;
1325                 mutex_lock(&ipipe->inode->i_mutex);
1326                 mutex_lock(&opipe->inode->i_mutex);
1327         } else {
1328                 mutex_lock(&opipe->inode->i_mutex);
1329                 mutex_lock(&ipipe->inode->i_mutex);
1330         }
1331
1332         for (i = 0;; i++) {
1333                 if (!opipe->readers) {
1334                         send_sig(SIGPIPE, current, 0);
1335                         if (!ret)
1336                                 ret = -EPIPE;
1337                         break;
1338                 }
1339                 if (ipipe->nrbufs - i) {
1340                         ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
1341
1342                         /*
1343                          * If we have room, fill this buffer
1344                          */
1345                         if (opipe->nrbufs < PIPE_BUFFERS) {
1346                                 int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
1347
1348                                 /*
1349                                  * Get a reference to this pipe buffer,
1350                                  * so we can copy the contents over.
1351                                  */
1352                                 ibuf->ops->get(ipipe, ibuf);
1353
1354                                 obuf = opipe->bufs + nbuf;
1355                                 *obuf = *ibuf;
1356
1357                                 /*
1358                                  * Don't inherit the gift flag, we need to
1359                                  * prevent multiple steals of this page.
1360                                  */
1361                                 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1362
1363                                 if (obuf->len > len)
1364                                         obuf->len = len;
1365
1366                                 opipe->nrbufs++;
1367                                 do_wakeup = 1;
1368                                 ret += obuf->len;
1369                                 len -= obuf->len;
1370
1371                                 if (!len)
1372                                         break;
1373                                 if (opipe->nrbufs < PIPE_BUFFERS)
1374                                         continue;
1375                         }
1376
1377                         /*
1378                          * We have input available, but no output room.
1379                          * If we already copied data, return that. If we
1380                          * need to drop the opipe lock, it must be ordered
1381                          * last to avoid deadlocks.
1382                          */
1383                         if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) {
1384                                 if (!ret)
1385                                         ret = -EAGAIN;
1386                                 break;
1387                         }
1388                         if (signal_pending(current)) {
1389                                 if (!ret)
1390                                         ret = -ERESTARTSYS;
1391                                 break;
1392                         }
1393                         if (do_wakeup) {
1394                                 smp_mb();
1395                                 if (waitqueue_active(&opipe->wait))
1396                                         wake_up_interruptible(&opipe->wait);
1397                                 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1398                                 do_wakeup = 0;
1399                         }
1400
1401                         opipe->waiting_writers++;
1402                         pipe_wait(opipe);
1403                         opipe->waiting_writers--;
1404                         continue;
1405                 }
1406
1407                 /*
1408                  * No input buffers, do the usual checks for available
1409                  * writers and blocking and wait if necessary
1410                  */
1411                 if (!ipipe->writers)
1412                         break;
1413                 if (!ipipe->waiting_writers) {
1414                         if (ret)
1415                                 break;
1416                 }
1417                 /*
1418                  * pipe_wait() drops the ipipe mutex. To avoid deadlocks
1419                  * with another process, we can only safely do that if
1420                  * the ipipe lock is ordered last.
1421                  */
1422                 if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) {
1423                         if (!ret)
1424                                 ret = -EAGAIN;
1425                         break;
1426                 }
1427                 if (signal_pending(current)) {
1428                         if (!ret)
1429                                 ret = -ERESTARTSYS;
1430                         break;
1431                 }
1432
1433                 if (waitqueue_active(&ipipe->wait))
1434                         wake_up_interruptible_sync(&ipipe->wait);
1435                 kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT);
1436
1437                 pipe_wait(ipipe);
1438         }
1439
1440         mutex_unlock(&ipipe->inode->i_mutex);
1441         mutex_unlock(&opipe->inode->i_mutex);
1442
1443         if (do_wakeup) {
1444                 smp_mb();
1445                 if (waitqueue_active(&opipe->wait))
1446                         wake_up_interruptible(&opipe->wait);
1447                 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1448         }
1449
1450         return ret;
1451 }
1452
1453 /*
1454  * This is a tee(1) implementation that works on pipes. It doesn't copy
1455  * any data, it simply references the 'in' pages on the 'out' pipe.
1456  * The 'flags' used are the SPLICE_F_* variants, currently the only
1457  * applicable one is SPLICE_F_NONBLOCK.
1458  */
1459 static long do_tee(struct file *in, struct file *out, size_t len,
1460                    unsigned int flags)
1461 {
1462         struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
1463         struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
1464
1465         /*
1466          * Link ipipe to the two output pipes, consuming as we go along.
1467          */
1468         if (ipipe && opipe)
1469                 return link_pipe(ipipe, opipe, len, flags);
1470
1471         return -EINVAL;
1472 }
1473
1474 asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
1475 {
1476         struct file *in;
1477         int error, fput_in;
1478
1479         if (unlikely(!len))
1480                 return 0;
1481
1482         error = -EBADF;
1483         in = fget_light(fdin, &fput_in);
1484         if (in) {
1485                 if (in->f_mode & FMODE_READ) {
1486                         int fput_out;
1487                         struct file *out = fget_light(fdout, &fput_out);
1488
1489                         if (out) {
1490                                 if (out->f_mode & FMODE_WRITE)
1491                                         error = do_tee(in, out, len, flags);
1492                                 fput_light(out, fput_out);
1493                         }
1494                 }
1495                 fput_light(in, fput_in);
1496         }
1497
1498         return error;
1499 }