[PATCH] mm: clean up pagecache allocation
[linux-2.6.git] / 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@kernel.dk>
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 *pipe,
55                                      struct pipe_buffer *buf)
56 {
57         struct page *page = buf->page;
58         struct address_space *mapping;
59
60         lock_page(page);
61
62         mapping = page_mapping(page);
63         if (mapping) {
64                 WARN_ON(!PageUptodate(page));
65
66                 /*
67                  * At least for ext2 with nobh option, we need to wait on
68                  * writeback completing on this page, since we'll remove it
69                  * from the pagecache.  Otherwise truncate wont wait on the
70                  * page, allowing the disk blocks to be reused by someone else
71                  * before we actually wrote our data to them. fs corruption
72                  * ensues.
73                  */
74                 wait_on_page_writeback(page);
75
76                 if (PagePrivate(page))
77                         try_to_release_page(page, GFP_KERNEL);
78
79                 /*
80                  * If we succeeded in removing the mapping, set LRU flag
81                  * and return good.
82                  */
83                 if (remove_mapping(mapping, page)) {
84                         buf->flags |= PIPE_BUF_FLAG_LRU;
85                         return 0;
86                 }
87         }
88
89         /*
90          * Raced with truncate or failed to remove page from current
91          * address space, unlock and return failure.
92          */
93         unlock_page(page);
94         return 1;
95 }
96
97 static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
98                                         struct pipe_buffer *buf)
99 {
100         page_cache_release(buf->page);
101         buf->flags &= ~PIPE_BUF_FLAG_LRU;
102 }
103
104 static int page_cache_pipe_buf_pin(struct pipe_inode_info *pipe,
105                                    struct pipe_buffer *buf)
106 {
107         struct page *page = buf->page;
108         int err;
109
110         if (!PageUptodate(page)) {
111                 lock_page(page);
112
113                 /*
114                  * Page got truncated/unhashed. This will cause a 0-byte
115                  * splice, if this is the first page.
116                  */
117                 if (!page->mapping) {
118                         err = -ENODATA;
119                         goto error;
120                 }
121
122                 /*
123                  * Uh oh, read-error from disk.
124                  */
125                 if (!PageUptodate(page)) {
126                         err = -EIO;
127                         goto error;
128                 }
129
130                 /*
131                  * Page is ok afterall, we are done.
132                  */
133                 unlock_page(page);
134         }
135
136         return 0;
137 error:
138         unlock_page(page);
139         return err;
140 }
141
142 static struct pipe_buf_operations page_cache_pipe_buf_ops = {
143         .can_merge = 0,
144         .map = generic_pipe_buf_map,
145         .unmap = generic_pipe_buf_unmap,
146         .pin = page_cache_pipe_buf_pin,
147         .release = page_cache_pipe_buf_release,
148         .steal = page_cache_pipe_buf_steal,
149         .get = generic_pipe_buf_get,
150 };
151
152 static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
153                                     struct pipe_buffer *buf)
154 {
155         if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
156                 return 1;
157
158         buf->flags |= PIPE_BUF_FLAG_LRU;
159         return generic_pipe_buf_steal(pipe, buf);
160 }
161
162 static struct pipe_buf_operations user_page_pipe_buf_ops = {
163         .can_merge = 0,
164         .map = generic_pipe_buf_map,
165         .unmap = generic_pipe_buf_unmap,
166         .pin = generic_pipe_buf_pin,
167         .release = page_cache_pipe_buf_release,
168         .steal = user_page_pipe_buf_steal,
169         .get = generic_pipe_buf_get,
170 };
171
172 /*
173  * Pipe output worker. This sets up our pipe format with the page cache
174  * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
175  */
176 static ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
177                               struct splice_pipe_desc *spd)
178 {
179         int ret, do_wakeup, page_nr;
180
181         ret = 0;
182         do_wakeup = 0;
183         page_nr = 0;
184
185         if (pipe->inode)
186                 mutex_lock(&pipe->inode->i_mutex);
187
188         for (;;) {
189                 if (!pipe->readers) {
190                         send_sig(SIGPIPE, current, 0);
191                         if (!ret)
192                                 ret = -EPIPE;
193                         break;
194                 }
195
196                 if (pipe->nrbufs < PIPE_BUFFERS) {
197                         int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
198                         struct pipe_buffer *buf = pipe->bufs + newbuf;
199
200                         buf->page = spd->pages[page_nr];
201                         buf->offset = spd->partial[page_nr].offset;
202                         buf->len = spd->partial[page_nr].len;
203                         buf->ops = spd->ops;
204                         if (spd->flags & SPLICE_F_GIFT)
205                                 buf->flags |= PIPE_BUF_FLAG_GIFT;
206
207                         pipe->nrbufs++;
208                         page_nr++;
209                         ret += buf->len;
210
211                         if (pipe->inode)
212                                 do_wakeup = 1;
213
214                         if (!--spd->nr_pages)
215                                 break;
216                         if (pipe->nrbufs < PIPE_BUFFERS)
217                                 continue;
218
219                         break;
220                 }
221
222                 if (spd->flags & SPLICE_F_NONBLOCK) {
223                         if (!ret)
224                                 ret = -EAGAIN;
225                         break;
226                 }
227
228                 if (signal_pending(current)) {
229                         if (!ret)
230                                 ret = -ERESTARTSYS;
231                         break;
232                 }
233
234                 if (do_wakeup) {
235                         smp_mb();
236                         if (waitqueue_active(&pipe->wait))
237                                 wake_up_interruptible_sync(&pipe->wait);
238                         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
239                         do_wakeup = 0;
240                 }
241
242                 pipe->waiting_writers++;
243                 pipe_wait(pipe);
244                 pipe->waiting_writers--;
245         }
246
247         if (pipe->inode)
248                 mutex_unlock(&pipe->inode->i_mutex);
249
250         if (do_wakeup) {
251                 smp_mb();
252                 if (waitqueue_active(&pipe->wait))
253                         wake_up_interruptible(&pipe->wait);
254                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
255         }
256
257         while (page_nr < spd->nr_pages)
258                 page_cache_release(spd->pages[page_nr++]);
259
260         return ret;
261 }
262
263 static int
264 __generic_file_splice_read(struct file *in, loff_t *ppos,
265                            struct pipe_inode_info *pipe, size_t len,
266                            unsigned int flags)
267 {
268         struct address_space *mapping = in->f_mapping;
269         unsigned int loff, nr_pages;
270         struct page *pages[PIPE_BUFFERS];
271         struct partial_page partial[PIPE_BUFFERS];
272         struct page *page;
273         pgoff_t index, end_index;
274         loff_t isize;
275         size_t total_len;
276         int error, page_nr;
277         struct splice_pipe_desc spd = {
278                 .pages = pages,
279                 .partial = partial,
280                 .flags = flags,
281                 .ops = &page_cache_pipe_buf_ops,
282         };
283
284         index = *ppos >> PAGE_CACHE_SHIFT;
285         loff = *ppos & ~PAGE_CACHE_MASK;
286         nr_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
287
288         if (nr_pages > PIPE_BUFFERS)
289                 nr_pages = PIPE_BUFFERS;
290
291         /*
292          * Initiate read-ahead on this page range. however, don't call into
293          * read-ahead if this is a non-zero offset (we are likely doing small
294          * chunk splice and the page is already there) for a single page.
295          */
296         if (!loff || nr_pages > 1)
297                 page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);
298
299         /*
300          * Now fill in the holes:
301          */
302         error = 0;
303         total_len = 0;
304
305         /*
306          * Lookup the (hopefully) full range of pages we need.
307          */
308         spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
309
310         /*
311          * If find_get_pages_contig() returned fewer pages than we needed,
312          * allocate the rest.
313          */
314         index += spd.nr_pages;
315         while (spd.nr_pages < nr_pages) {
316                 /*
317                  * Page could be there, find_get_pages_contig() breaks on
318                  * the first hole.
319                  */
320                 page = find_get_page(mapping, index);
321                 if (!page) {
322                         /*
323                          * Make sure the read-ahead engine is notified
324                          * about this failure.
325                          */
326                         handle_ra_miss(mapping, &in->f_ra, index);
327
328                         /*
329                          * page didn't exist, allocate one.
330                          */
331                         page = page_cache_alloc_cold(mapping);
332                         if (!page)
333                                 break;
334
335                         error = add_to_page_cache_lru(page, mapping, index,
336                                               GFP_KERNEL);
337                         if (unlikely(error)) {
338                                 page_cache_release(page);
339                                 if (error == -EEXIST)
340                                         continue;
341                                 break;
342                         }
343                         /*
344                          * add_to_page_cache() locks the page, unlock it
345                          * to avoid convoluting the logic below even more.
346                          */
347                         unlock_page(page);
348                 }
349
350                 pages[spd.nr_pages++] = page;
351                 index++;
352         }
353
354         /*
355          * Now loop over the map and see if we need to start IO on any
356          * pages, fill in the partial map, etc.
357          */
358         index = *ppos >> PAGE_CACHE_SHIFT;
359         nr_pages = spd.nr_pages;
360         spd.nr_pages = 0;
361         for (page_nr = 0; page_nr < nr_pages; page_nr++) {
362                 unsigned int this_len;
363
364                 if (!len)
365                         break;
366
367                 /*
368                  * this_len is the max we'll use from this page
369                  */
370                 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
371                 page = pages[page_nr];
372
373                 /*
374                  * If the page isn't uptodate, we may need to start io on it
375                  */
376                 if (!PageUptodate(page)) {
377                         /*
378                          * If in nonblock mode then dont block on waiting
379                          * for an in-flight io page
380                          */
381                         if (flags & SPLICE_F_NONBLOCK)
382                                 break;
383
384                         lock_page(page);
385
386                         /*
387                          * page was truncated, stop here. if this isn't the
388                          * first page, we'll just complete what we already
389                          * added
390                          */
391                         if (!page->mapping) {
392                                 unlock_page(page);
393                                 break;
394                         }
395                         /*
396                          * page was already under io and is now done, great
397                          */
398                         if (PageUptodate(page)) {
399                                 unlock_page(page);
400                                 goto fill_it;
401                         }
402
403                         /*
404                          * need to read in the page
405                          */
406                         error = mapping->a_ops->readpage(in, page);
407                         if (unlikely(error)) {
408                                 /*
409                                  * We really should re-lookup the page here,
410                                  * but it complicates things a lot. Instead
411                                  * lets just do what we already stored, and
412                                  * we'll get it the next time we are called.
413                                  */
414                                 if (error == AOP_TRUNCATED_PAGE)
415                                         error = 0;
416
417                                 break;
418                         }
419
420                         /*
421                          * i_size must be checked after ->readpage().
422                          */
423                         isize = i_size_read(mapping->host);
424                         end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
425                         if (unlikely(!isize || index > end_index))
426                                 break;
427
428                         /*
429                          * if this is the last page, see if we need to shrink
430                          * the length and stop
431                          */
432                         if (end_index == index) {
433                                 loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
434                                 if (total_len + loff > isize)
435                                         break;
436                                 /*
437                                  * force quit after adding this page
438                                  */
439                                 len = this_len;
440                                 this_len = min(this_len, loff);
441                                 loff = 0;
442                         }
443                 }
444 fill_it:
445                 partial[page_nr].offset = loff;
446                 partial[page_nr].len = this_len;
447                 len -= this_len;
448                 total_len += this_len;
449                 loff = 0;
450                 spd.nr_pages++;
451                 index++;
452         }
453
454         /*
455          * Release any pages at the end, if we quit early. 'i' is how far
456          * we got, 'nr_pages' is how many pages are in the map.
457          */
458         while (page_nr < nr_pages)
459                 page_cache_release(pages[page_nr++]);
460
461         if (spd.nr_pages)
462                 return splice_to_pipe(pipe, &spd);
463
464         return error;
465 }
466
467 /**
468  * generic_file_splice_read - splice data from file to a pipe
469  * @in:         file to splice from
470  * @pipe:       pipe to splice to
471  * @len:        number of bytes to splice
472  * @flags:      splice modifier flags
473  *
474  * Will read pages from given file and fill them into a pipe.
475  */
476 ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
477                                  struct pipe_inode_info *pipe, size_t len,
478                                  unsigned int flags)
479 {
480         ssize_t spliced;
481         int ret;
482
483         ret = 0;
484         spliced = 0;
485
486         while (len) {
487                 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
488
489                 if (ret < 0)
490                         break;
491                 else if (!ret) {
492                         if (spliced)
493                                 break;
494                         if (flags & SPLICE_F_NONBLOCK) {
495                                 ret = -EAGAIN;
496                                 break;
497                         }
498                 }
499
500                 *ppos += ret;
501                 len -= ret;
502                 spliced += ret;
503         }
504
505         if (spliced)
506                 return spliced;
507
508         return ret;
509 }
510
511 EXPORT_SYMBOL(generic_file_splice_read);
512
513 /*
514  * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
515  * using sendpage(). Return the number of bytes sent.
516  */
517 static int pipe_to_sendpage(struct pipe_inode_info *pipe,
518                             struct pipe_buffer *buf, struct splice_desc *sd)
519 {
520         struct file *file = sd->file;
521         loff_t pos = sd->pos;
522         int ret, more;
523
524         ret = buf->ops->pin(pipe, buf);
525         if (!ret) {
526                 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
527
528                 ret = file->f_op->sendpage(file, buf->page, buf->offset,
529                                            sd->len, &pos, more);
530         }
531
532         return ret;
533 }
534
535 /*
536  * This is a little more tricky than the file -> pipe splicing. There are
537  * basically three cases:
538  *
539  *      - Destination page already exists in the address space and there
540  *        are users of it. For that case we have no other option that
541  *        copying the data. Tough luck.
542  *      - Destination page already exists in the address space, but there
543  *        are no users of it. Make sure it's uptodate, then drop it. Fall
544  *        through to last case.
545  *      - Destination page does not exist, we can add the pipe page to
546  *        the page cache and avoid the copy.
547  *
548  * If asked to move pages to the output file (SPLICE_F_MOVE is set in
549  * sd->flags), we attempt to migrate pages from the pipe to the output
550  * file address space page cache. This is possible if no one else has
551  * the pipe page referenced outside of the pipe and page cache. If
552  * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
553  * a new page in the output file page cache and fill/dirty that.
554  */
555 static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
556                         struct splice_desc *sd)
557 {
558         struct file *file = sd->file;
559         struct address_space *mapping = file->f_mapping;
560         unsigned int offset, this_len;
561         struct page *page;
562         pgoff_t index;
563         int ret;
564
565         /*
566          * make sure the data in this buffer is uptodate
567          */
568         ret = buf->ops->pin(pipe, buf);
569         if (unlikely(ret))
570                 return ret;
571
572         index = sd->pos >> PAGE_CACHE_SHIFT;
573         offset = sd->pos & ~PAGE_CACHE_MASK;
574
575         this_len = sd->len;
576         if (this_len + offset > PAGE_CACHE_SIZE)
577                 this_len = PAGE_CACHE_SIZE - offset;
578
579         /*
580          * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full
581          * page.
582          */
583         if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
584                 /*
585                  * If steal succeeds, buf->page is now pruned from the
586                  * pagecache and we can reuse it. The page will also be
587                  * locked on successful return.
588                  */
589                 if (buf->ops->steal(pipe, buf))
590                         goto find_page;
591
592                 page = buf->page;
593                 if (add_to_page_cache(page, mapping, index, GFP_KERNEL)) {
594                         unlock_page(page);
595                         goto find_page;
596                 }
597
598                 page_cache_get(page);
599
600                 if (!(buf->flags & PIPE_BUF_FLAG_LRU))
601                         lru_cache_add(page);
602         } else {
603 find_page:
604                 page = find_lock_page(mapping, index);
605                 if (!page) {
606                         ret = -ENOMEM;
607                         page = page_cache_alloc_cold(mapping);
608                         if (unlikely(!page))
609                                 goto out_ret;
610
611                         /*
612                          * This will also lock the page
613                          */
614                         ret = add_to_page_cache_lru(page, mapping, index,
615                                                     GFP_KERNEL);
616                         if (unlikely(ret))
617                                 goto out;
618                 }
619
620                 /*
621                  * We get here with the page locked. If the page is also
622                  * uptodate, we don't need to do more. If it isn't, we
623                  * may need to bring it in if we are not going to overwrite
624                  * the full page.
625                  */
626                 if (!PageUptodate(page)) {
627                         if (this_len < PAGE_CACHE_SIZE) {
628                                 ret = mapping->a_ops->readpage(file, page);
629                                 if (unlikely(ret))
630                                         goto out;
631
632                                 lock_page(page);
633
634                                 if (!PageUptodate(page)) {
635                                         /*
636                                          * Page got invalidated, repeat.
637                                          */
638                                         if (!page->mapping) {
639                                                 unlock_page(page);
640                                                 page_cache_release(page);
641                                                 goto find_page;
642                                         }
643                                         ret = -EIO;
644                                         goto out;
645                                 }
646                         } else
647                                 SetPageUptodate(page);
648                 }
649         }
650
651         ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
652         if (unlikely(ret)) {
653                 loff_t isize = i_size_read(mapping->host);
654
655                 if (ret != AOP_TRUNCATED_PAGE)
656                         unlock_page(page);
657                 page_cache_release(page);
658                 if (ret == AOP_TRUNCATED_PAGE)
659                         goto find_page;
660
661                 /*
662                  * prepare_write() may have instantiated a few blocks
663                  * outside i_size.  Trim these off again.
664                  */
665                 if (sd->pos + this_len > isize)
666                         vmtruncate(mapping->host, isize);
667
668                 goto out_ret;
669         }
670
671         if (buf->page != page) {
672                 /*
673                  * Careful, ->map() uses KM_USER0!
674                  */
675                 char *src = buf->ops->map(pipe, buf, 1);
676                 char *dst = kmap_atomic(page, KM_USER1);
677
678                 memcpy(dst + offset, src + buf->offset, this_len);
679                 flush_dcache_page(page);
680                 kunmap_atomic(dst, KM_USER1);
681                 buf->ops->unmap(pipe, buf, src);
682         }
683
684         ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
685         if (!ret) {
686                 /*
687                  * Return the number of bytes written and mark page as
688                  * accessed, we are now done!
689                  */
690                 ret = this_len;
691                 mark_page_accessed(page);
692                 balance_dirty_pages_ratelimited(mapping);
693         } else if (ret == AOP_TRUNCATED_PAGE) {
694                 page_cache_release(page);
695                 goto find_page;
696         }
697 out:
698         page_cache_release(page);
699         unlock_page(page);
700 out_ret:
701         return ret;
702 }
703
704 /*
705  * Pipe input worker. Most of this logic works like a regular pipe, the
706  * key here is the 'actor' worker passed in that actually moves the data
707  * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
708  */
709 static ssize_t __splice_from_pipe(struct pipe_inode_info *pipe,
710                                   struct file *out, loff_t *ppos, size_t len,
711                                   unsigned int flags, splice_actor *actor)
712 {
713         int ret, do_wakeup, err;
714         struct splice_desc sd;
715
716         ret = 0;
717         do_wakeup = 0;
718
719         sd.total_len = len;
720         sd.flags = flags;
721         sd.file = out;
722         sd.pos = *ppos;
723
724         for (;;) {
725                 if (pipe->nrbufs) {
726                         struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
727                         struct pipe_buf_operations *ops = buf->ops;
728
729                         sd.len = buf->len;
730                         if (sd.len > sd.total_len)
731                                 sd.len = sd.total_len;
732
733                         err = actor(pipe, buf, &sd);
734                         if (err <= 0) {
735                                 if (!ret && err != -ENODATA)
736                                         ret = err;
737
738                                 break;
739                         }
740
741                         ret += err;
742                         buf->offset += err;
743                         buf->len -= err;
744
745                         sd.len -= err;
746                         sd.pos += err;
747                         sd.total_len -= err;
748                         if (sd.len)
749                                 continue;
750
751                         if (!buf->len) {
752                                 buf->ops = NULL;
753                                 ops->release(pipe, buf);
754                                 pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
755                                 pipe->nrbufs--;
756                                 if (pipe->inode)
757                                         do_wakeup = 1;
758                         }
759
760                         if (!sd.total_len)
761                                 break;
762                 }
763
764                 if (pipe->nrbufs)
765                         continue;
766                 if (!pipe->writers)
767                         break;
768                 if (!pipe->waiting_writers) {
769                         if (ret)
770                                 break;
771                 }
772
773                 if (flags & SPLICE_F_NONBLOCK) {
774                         if (!ret)
775                                 ret = -EAGAIN;
776                         break;
777                 }
778
779                 if (signal_pending(current)) {
780                         if (!ret)
781                                 ret = -ERESTARTSYS;
782                         break;
783                 }
784
785                 if (do_wakeup) {
786                         smp_mb();
787                         if (waitqueue_active(&pipe->wait))
788                                 wake_up_interruptible_sync(&pipe->wait);
789                         kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
790                         do_wakeup = 0;
791                 }
792
793                 pipe_wait(pipe);
794         }
795
796         if (do_wakeup) {
797                 smp_mb();
798                 if (waitqueue_active(&pipe->wait))
799                         wake_up_interruptible(&pipe->wait);
800                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
801         }
802
803         return ret;
804 }
805
806 ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
807                          loff_t *ppos, size_t len, unsigned int flags,
808                          splice_actor *actor)
809 {
810         ssize_t ret;
811         struct inode *inode = out->f_mapping->host;
812
813         /*
814          * The actor worker might be calling ->prepare_write and
815          * ->commit_write. Most of the time, these expect i_mutex to
816          * be held. Since this may result in an ABBA deadlock with
817          * pipe->inode, we have to order lock acquiry here.
818          */
819         inode_double_lock(inode, pipe->inode);
820         ret = __splice_from_pipe(pipe, out, ppos, len, flags, actor);
821         inode_double_unlock(inode, pipe->inode);
822
823         return ret;
824 }
825
826 /**
827  * generic_file_splice_write_nolock - generic_file_splice_write without mutexes
828  * @pipe:       pipe info
829  * @out:        file to write to
830  * @len:        number of bytes to splice
831  * @flags:      splice modifier flags
832  *
833  * Will either move or copy pages (determined by @flags options) from
834  * the given pipe inode to the given file. The caller is responsible
835  * for acquiring i_mutex on both inodes.
836  *
837  */
838 ssize_t
839 generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
840                                  loff_t *ppos, size_t len, unsigned int flags)
841 {
842         struct address_space *mapping = out->f_mapping;
843         struct inode *inode = mapping->host;
844         ssize_t ret;
845         int err;
846
847         err = remove_suid(out->f_dentry);
848         if (unlikely(err))
849                 return err;
850
851         ret = __splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
852         if (ret > 0) {
853                 *ppos += ret;
854
855                 /*
856                  * If file or inode is SYNC and we actually wrote some data,
857                  * sync it.
858                  */
859                 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
860                         err = generic_osync_inode(inode, mapping,
861                                                   OSYNC_METADATA|OSYNC_DATA);
862
863                         if (err)
864                                 ret = err;
865                 }
866         }
867
868         return ret;
869 }
870
871 EXPORT_SYMBOL(generic_file_splice_write_nolock);
872
873 /**
874  * generic_file_splice_write - splice data from a pipe to a file
875  * @pipe:       pipe info
876  * @out:        file to write to
877  * @len:        number of bytes to splice
878  * @flags:      splice modifier flags
879  *
880  * Will either move or copy pages (determined by @flags options) from
881  * the given pipe inode to the given file.
882  *
883  */
884 ssize_t
885 generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
886                           loff_t *ppos, size_t len, unsigned int flags)
887 {
888         struct address_space *mapping = out->f_mapping;
889         struct inode *inode = mapping->host;
890         ssize_t ret;
891         int err;
892
893         err = should_remove_suid(out->f_dentry);
894         if (unlikely(err)) {
895                 mutex_lock(&inode->i_mutex);
896                 err = __remove_suid(out->f_dentry, err);
897                 mutex_unlock(&inode->i_mutex);
898                 if (err)
899                         return err;
900         }
901
902         ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
903         if (ret > 0) {
904                 *ppos += ret;
905
906                 /*
907                  * If file or inode is SYNC and we actually wrote some data,
908                  * sync it.
909                  */
910                 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
911                         mutex_lock(&inode->i_mutex);
912                         err = generic_osync_inode(inode, mapping,
913                                                   OSYNC_METADATA|OSYNC_DATA);
914                         mutex_unlock(&inode->i_mutex);
915
916                         if (err)
917                                 ret = err;
918                 }
919         }
920
921         return ret;
922 }
923
924 EXPORT_SYMBOL(generic_file_splice_write);
925
926 /**
927  * generic_splice_sendpage - splice data from a pipe to a socket
928  * @inode:      pipe inode
929  * @out:        socket to write to
930  * @len:        number of bytes to splice
931  * @flags:      splice modifier flags
932  *
933  * Will send @len bytes from the pipe to a network socket. No data copying
934  * is involved.
935  *
936  */
937 ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
938                                 loff_t *ppos, size_t len, unsigned int flags)
939 {
940         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
941 }
942
943 EXPORT_SYMBOL(generic_splice_sendpage);
944
945 /*
946  * Attempt to initiate a splice from pipe to file.
947  */
948 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
949                            loff_t *ppos, size_t len, unsigned int flags)
950 {
951         int ret;
952
953         if (unlikely(!out->f_op || !out->f_op->splice_write))
954                 return -EINVAL;
955
956         if (unlikely(!(out->f_mode & FMODE_WRITE)))
957                 return -EBADF;
958
959         ret = rw_verify_area(WRITE, out, ppos, len);
960         if (unlikely(ret < 0))
961                 return ret;
962
963         return out->f_op->splice_write(pipe, out, ppos, len, flags);
964 }
965
966 /*
967  * Attempt to initiate a splice from a file to a pipe.
968  */
969 static long do_splice_to(struct file *in, loff_t *ppos,
970                          struct pipe_inode_info *pipe, size_t len,
971                          unsigned int flags)
972 {
973         loff_t isize, left;
974         int ret;
975
976         if (unlikely(!in->f_op || !in->f_op->splice_read))
977                 return -EINVAL;
978
979         if (unlikely(!(in->f_mode & FMODE_READ)))
980                 return -EBADF;
981
982         ret = rw_verify_area(READ, in, ppos, len);
983         if (unlikely(ret < 0))
984                 return ret;
985
986         isize = i_size_read(in->f_mapping->host);
987         if (unlikely(*ppos >= isize))
988                 return 0;
989         
990         left = isize - *ppos;
991         if (unlikely(left < len))
992                 len = left;
993
994         return in->f_op->splice_read(in, ppos, pipe, len, flags);
995 }
996
997 long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
998                       size_t len, unsigned int flags)
999 {
1000         struct pipe_inode_info *pipe;
1001         long ret, bytes;
1002         loff_t out_off;
1003         umode_t i_mode;
1004         int i;
1005
1006         /*
1007          * We require the input being a regular file, as we don't want to
1008          * randomly drop data for eg socket -> socket splicing. Use the
1009          * piped splicing for that!
1010          */
1011         i_mode = in->f_dentry->d_inode->i_mode;
1012         if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
1013                 return -EINVAL;
1014
1015         /*
1016          * neither in nor out is a pipe, setup an internal pipe attached to
1017          * 'out' and transfer the wanted data from 'in' to 'out' through that
1018          */
1019         pipe = current->splice_pipe;
1020         if (unlikely(!pipe)) {
1021                 pipe = alloc_pipe_info(NULL);
1022                 if (!pipe)
1023                         return -ENOMEM;
1024
1025                 /*
1026                  * We don't have an immediate reader, but we'll read the stuff
1027                  * out of the pipe right after the splice_to_pipe(). So set
1028                  * PIPE_READERS appropriately.
1029                  */
1030                 pipe->readers = 1;
1031
1032                 current->splice_pipe = pipe;
1033         }
1034
1035         /*
1036          * Do the splice.
1037          */
1038         ret = 0;
1039         bytes = 0;
1040         out_off = 0;
1041
1042         while (len) {
1043                 size_t read_len, max_read_len;
1044
1045                 /*
1046                  * Do at most PIPE_BUFFERS pages worth of transfer:
1047                  */
1048                 max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
1049
1050                 ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
1051                 if (unlikely(ret < 0))
1052                         goto out_release;
1053
1054                 read_len = ret;
1055
1056                 /*
1057                  * NOTE: nonblocking mode only applies to the input. We
1058                  * must not do the output in nonblocking mode as then we
1059                  * could get stuck data in the internal pipe:
1060                  */
1061                 ret = do_splice_from(pipe, out, &out_off, read_len,
1062                                      flags & ~SPLICE_F_NONBLOCK);
1063                 if (unlikely(ret < 0))
1064                         goto out_release;
1065
1066                 bytes += ret;
1067                 len -= ret;
1068
1069                 /*
1070                  * In nonblocking mode, if we got back a short read then
1071                  * that was due to either an IO error or due to the
1072                  * pagecache entry not being there. In the IO error case
1073                  * the _next_ splice attempt will produce a clean IO error
1074                  * return value (not a short read), so in both cases it's
1075                  * correct to break out of the loop here:
1076                  */
1077                 if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
1078                         break;
1079         }
1080
1081         pipe->nrbufs = pipe->curbuf = 0;
1082
1083         return bytes;
1084
1085 out_release:
1086         /*
1087          * If we did an incomplete transfer we must release
1088          * the pipe buffers in question:
1089          */
1090         for (i = 0; i < PIPE_BUFFERS; i++) {
1091                 struct pipe_buffer *buf = pipe->bufs + i;
1092
1093                 if (buf->ops) {
1094                         buf->ops->release(pipe, buf);
1095                         buf->ops = NULL;
1096                 }
1097         }
1098         pipe->nrbufs = pipe->curbuf = 0;
1099
1100         /*
1101          * If we transferred some data, return the number of bytes:
1102          */
1103         if (bytes > 0)
1104                 return bytes;
1105
1106         return ret;
1107 }
1108
1109 EXPORT_SYMBOL(do_splice_direct);
1110
1111 /*
1112  * Determine where to splice to/from.
1113  */
1114 static long do_splice(struct file *in, loff_t __user *off_in,
1115                       struct file *out, loff_t __user *off_out,
1116                       size_t len, unsigned int flags)
1117 {
1118         struct pipe_inode_info *pipe;
1119         loff_t offset, *off;
1120         long ret;
1121
1122         pipe = in->f_dentry->d_inode->i_pipe;
1123         if (pipe) {
1124                 if (off_in)
1125                         return -ESPIPE;
1126                 if (off_out) {
1127                         if (out->f_op->llseek == no_llseek)
1128                                 return -EINVAL;
1129                         if (copy_from_user(&offset, off_out, sizeof(loff_t)))
1130                                 return -EFAULT;
1131                         off = &offset;
1132                 } else
1133                         off = &out->f_pos;
1134
1135                 ret = do_splice_from(pipe, out, off, len, flags);
1136
1137                 if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
1138                         ret = -EFAULT;
1139
1140                 return ret;
1141         }
1142
1143         pipe = out->f_dentry->d_inode->i_pipe;
1144         if (pipe) {
1145                 if (off_out)
1146                         return -ESPIPE;
1147                 if (off_in) {
1148                         if (in->f_op->llseek == no_llseek)
1149                                 return -EINVAL;
1150                         if (copy_from_user(&offset, off_in, sizeof(loff_t)))
1151                                 return -EFAULT;
1152                         off = &offset;
1153                 } else
1154                         off = &in->f_pos;
1155
1156                 ret = do_splice_to(in, off, pipe, len, flags);
1157
1158                 if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
1159                         ret = -EFAULT;
1160
1161                 return ret;
1162         }
1163
1164         return -EINVAL;
1165 }
1166
1167 /*
1168  * Map an iov into an array of pages and offset/length tupples. With the
1169  * partial_page structure, we can map several non-contiguous ranges into
1170  * our ones pages[] map instead of splitting that operation into pieces.
1171  * Could easily be exported as a generic helper for other users, in which
1172  * case one would probably want to add a 'max_nr_pages' parameter as well.
1173  */
1174 static int get_iovec_page_array(const struct iovec __user *iov,
1175                                 unsigned int nr_vecs, struct page **pages,
1176                                 struct partial_page *partial, int aligned)
1177 {
1178         int buffers = 0, error = 0;
1179
1180         /*
1181          * It's ok to take the mmap_sem for reading, even
1182          * across a "get_user()".
1183          */
1184         down_read(&current->mm->mmap_sem);
1185
1186         while (nr_vecs) {
1187                 unsigned long off, npages;
1188                 void __user *base;
1189                 size_t len;
1190                 int i;
1191
1192                 /*
1193                  * Get user address base and length for this iovec.
1194                  */
1195                 error = get_user(base, &iov->iov_base);
1196                 if (unlikely(error))
1197                         break;
1198                 error = get_user(len, &iov->iov_len);
1199                 if (unlikely(error))
1200                         break;
1201
1202                 /*
1203                  * Sanity check this iovec. 0 read succeeds.
1204                  */
1205                 if (unlikely(!len))
1206                         break;
1207                 error = -EFAULT;
1208                 if (unlikely(!base))
1209                         break;
1210
1211                 /*
1212                  * Get this base offset and number of pages, then map
1213                  * in the user pages.
1214                  */
1215                 off = (unsigned long) base & ~PAGE_MASK;
1216
1217                 /*
1218                  * If asked for alignment, the offset must be zero and the
1219                  * length a multiple of the PAGE_SIZE.
1220                  */
1221                 error = -EINVAL;
1222                 if (aligned && (off || len & ~PAGE_MASK))
1223                         break;
1224
1225                 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1226                 if (npages > PIPE_BUFFERS - buffers)
1227                         npages = PIPE_BUFFERS - buffers;
1228
1229                 error = get_user_pages(current, current->mm,
1230                                        (unsigned long) base, npages, 0, 0,
1231                                        &pages[buffers], NULL);
1232
1233                 if (unlikely(error <= 0))
1234                         break;
1235
1236                 /*
1237                  * Fill this contiguous range into the partial page map.
1238                  */
1239                 for (i = 0; i < error; i++) {
1240                         const int plen = min_t(size_t, len, PAGE_SIZE - off);
1241
1242                         partial[buffers].offset = off;
1243                         partial[buffers].len = plen;
1244
1245                         off = 0;
1246                         len -= plen;
1247                         buffers++;
1248                 }
1249
1250                 /*
1251                  * We didn't complete this iov, stop here since it probably
1252                  * means we have to move some of this into a pipe to
1253                  * be able to continue.
1254                  */
1255                 if (len)
1256                         break;
1257
1258                 /*
1259                  * Don't continue if we mapped fewer pages than we asked for,
1260                  * or if we mapped the max number of pages that we have
1261                  * room for.
1262                  */
1263                 if (error < npages || buffers == PIPE_BUFFERS)
1264                         break;
1265
1266                 nr_vecs--;
1267                 iov++;
1268         }
1269
1270         up_read(&current->mm->mmap_sem);
1271
1272         if (buffers)
1273                 return buffers;
1274
1275         return error;
1276 }
1277
1278 /*
1279  * vmsplice splices a user address range into a pipe. It can be thought of
1280  * as splice-from-memory, where the regular splice is splice-from-file (or
1281  * to file). In both cases the output is a pipe, naturally.
1282  *
1283  * Note that vmsplice only supports splicing _from_ user memory to a pipe,
1284  * not the other way around. Splicing from user memory is a simple operation
1285  * that can be supported without any funky alignment restrictions or nasty
1286  * vm tricks. We simply map in the user memory and fill them into a pipe.
1287  * The reverse isn't quite as easy, though. There are two possible solutions
1288  * for that:
1289  *
1290  *      - memcpy() the data internally, at which point we might as well just
1291  *        do a regular read() on the buffer anyway.
1292  *      - Lots of nasty vm tricks, that are neither fast nor flexible (it
1293  *        has restriction limitations on both ends of the pipe).
1294  *
1295  * Alas, it isn't here.
1296  *
1297  */
1298 static long do_vmsplice(struct file *file, const struct iovec __user *iov,
1299                         unsigned long nr_segs, unsigned int flags)
1300 {
1301         struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe;
1302         struct page *pages[PIPE_BUFFERS];
1303         struct partial_page partial[PIPE_BUFFERS];
1304         struct splice_pipe_desc spd = {
1305                 .pages = pages,
1306                 .partial = partial,
1307                 .flags = flags,
1308                 .ops = &user_page_pipe_buf_ops,
1309         };
1310
1311         if (unlikely(!pipe))
1312                 return -EBADF;
1313         if (unlikely(nr_segs > UIO_MAXIOV))
1314                 return -EINVAL;
1315         else if (unlikely(!nr_segs))
1316                 return 0;
1317
1318         spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
1319                                             flags & SPLICE_F_GIFT);
1320         if (spd.nr_pages <= 0)
1321                 return spd.nr_pages;
1322
1323         return splice_to_pipe(pipe, &spd);
1324 }
1325
1326 asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
1327                              unsigned long nr_segs, unsigned int flags)
1328 {
1329         struct file *file;
1330         long error;
1331         int fput;
1332
1333         error = -EBADF;
1334         file = fget_light(fd, &fput);
1335         if (file) {
1336                 if (file->f_mode & FMODE_WRITE)
1337                         error = do_vmsplice(file, iov, nr_segs, flags);
1338
1339                 fput_light(file, fput);
1340         }
1341
1342         return error;
1343 }
1344
1345 asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
1346                            int fd_out, loff_t __user *off_out,
1347                            size_t len, unsigned int flags)
1348 {
1349         long error;
1350         struct file *in, *out;
1351         int fput_in, fput_out;
1352
1353         if (unlikely(!len))
1354                 return 0;
1355
1356         error = -EBADF;
1357         in = fget_light(fd_in, &fput_in);
1358         if (in) {
1359                 if (in->f_mode & FMODE_READ) {
1360                         out = fget_light(fd_out, &fput_out);
1361                         if (out) {
1362                                 if (out->f_mode & FMODE_WRITE)
1363                                         error = do_splice(in, off_in,
1364                                                           out, off_out,
1365                                                           len, flags);
1366                                 fput_light(out, fput_out);
1367                         }
1368                 }
1369
1370                 fput_light(in, fput_in);
1371         }
1372
1373         return error;
1374 }
1375
1376 /*
1377  * Make sure there's data to read. Wait for input if we can, otherwise
1378  * return an appropriate error.
1379  */
1380 static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1381 {
1382         int ret;
1383
1384         /*
1385          * Check ->nrbufs without the inode lock first. This function
1386          * is speculative anyways, so missing one is ok.
1387          */
1388         if (pipe->nrbufs)
1389                 return 0;
1390
1391         ret = 0;
1392         mutex_lock(&pipe->inode->i_mutex);
1393
1394         while (!pipe->nrbufs) {
1395                 if (signal_pending(current)) {
1396                         ret = -ERESTARTSYS;
1397                         break;
1398                 }
1399                 if (!pipe->writers)
1400                         break;
1401                 if (!pipe->waiting_writers) {
1402                         if (flags & SPLICE_F_NONBLOCK) {
1403                                 ret = -EAGAIN;
1404                                 break;
1405                         }
1406                 }
1407                 pipe_wait(pipe);
1408         }
1409
1410         mutex_unlock(&pipe->inode->i_mutex);
1411         return ret;
1412 }
1413
1414 /*
1415  * Make sure there's writeable room. Wait for room if we can, otherwise
1416  * return an appropriate error.
1417  */
1418 static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1419 {
1420         int ret;
1421
1422         /*
1423          * Check ->nrbufs without the inode lock first. This function
1424          * is speculative anyways, so missing one is ok.
1425          */
1426         if (pipe->nrbufs < PIPE_BUFFERS)
1427                 return 0;
1428
1429         ret = 0;
1430         mutex_lock(&pipe->inode->i_mutex);
1431
1432         while (pipe->nrbufs >= PIPE_BUFFERS) {
1433                 if (!pipe->readers) {
1434                         send_sig(SIGPIPE, current, 0);
1435                         ret = -EPIPE;
1436                         break;
1437                 }
1438                 if (flags & SPLICE_F_NONBLOCK) {
1439                         ret = -EAGAIN;
1440                         break;
1441                 }
1442                 if (signal_pending(current)) {
1443                         ret = -ERESTARTSYS;
1444                         break;
1445                 }
1446                 pipe->waiting_writers++;
1447                 pipe_wait(pipe);
1448                 pipe->waiting_writers--;
1449         }
1450
1451         mutex_unlock(&pipe->inode->i_mutex);
1452         return ret;
1453 }
1454
1455 /*
1456  * Link contents of ipipe to opipe.
1457  */
1458 static int link_pipe(struct pipe_inode_info *ipipe,
1459                      struct pipe_inode_info *opipe,
1460                      size_t len, unsigned int flags)
1461 {
1462         struct pipe_buffer *ibuf, *obuf;
1463         int ret = 0, i = 0, nbuf;
1464
1465         /*
1466          * Potential ABBA deadlock, work around it by ordering lock
1467          * grabbing by inode address. Otherwise two different processes
1468          * could deadlock (one doing tee from A -> B, the other from B -> A).
1469          */
1470         inode_double_lock(ipipe->inode, opipe->inode);
1471
1472         do {
1473                 if (!opipe->readers) {
1474                         send_sig(SIGPIPE, current, 0);
1475                         if (!ret)
1476                                 ret = -EPIPE;
1477                         break;
1478                 }
1479
1480                 /*
1481                  * If we have iterated all input buffers or ran out of
1482                  * output room, break.
1483                  */
1484                 if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS)
1485                         break;
1486
1487                 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
1488                 nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
1489
1490                 /*
1491                  * Get a reference to this pipe buffer,
1492                  * so we can copy the contents over.
1493                  */
1494                 ibuf->ops->get(ipipe, ibuf);
1495
1496                 obuf = opipe->bufs + nbuf;
1497                 *obuf = *ibuf;
1498
1499                 /*
1500                  * Don't inherit the gift flag, we need to
1501                  * prevent multiple steals of this page.
1502                  */
1503                 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1504
1505                 if (obuf->len > len)
1506                         obuf->len = len;
1507
1508                 opipe->nrbufs++;
1509                 ret += obuf->len;
1510                 len -= obuf->len;
1511                 i++;
1512         } while (len);
1513
1514         inode_double_unlock(ipipe->inode, opipe->inode);
1515
1516         /*
1517          * If we put data in the output pipe, wakeup any potential readers.
1518          */
1519         if (ret > 0) {
1520                 smp_mb();
1521                 if (waitqueue_active(&opipe->wait))
1522                         wake_up_interruptible(&opipe->wait);
1523                 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1524         }
1525
1526         return ret;
1527 }
1528
1529 /*
1530  * This is a tee(1) implementation that works on pipes. It doesn't copy
1531  * any data, it simply references the 'in' pages on the 'out' pipe.
1532  * The 'flags' used are the SPLICE_F_* variants, currently the only
1533  * applicable one is SPLICE_F_NONBLOCK.
1534  */
1535 static long do_tee(struct file *in, struct file *out, size_t len,
1536                    unsigned int flags)
1537 {
1538         struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
1539         struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
1540         int ret = -EINVAL;
1541
1542         /*
1543          * Duplicate the contents of ipipe to opipe without actually
1544          * copying the data.
1545          */
1546         if (ipipe && opipe && ipipe != opipe) {
1547                 /*
1548                  * Keep going, unless we encounter an error. The ipipe/opipe
1549                  * ordering doesn't really matter.
1550                  */
1551                 ret = link_ipipe_prep(ipipe, flags);
1552                 if (!ret) {
1553                         ret = link_opipe_prep(opipe, flags);
1554                         if (!ret) {
1555                                 ret = link_pipe(ipipe, opipe, len, flags);
1556                                 if (!ret && (flags & SPLICE_F_NONBLOCK))
1557                                         ret = -EAGAIN;
1558                         }
1559                 }
1560         }
1561
1562         return ret;
1563 }
1564
1565 asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
1566 {
1567         struct file *in;
1568         int error, fput_in;
1569
1570         if (unlikely(!len))
1571                 return 0;
1572
1573         error = -EBADF;
1574         in = fget_light(fdin, &fput_in);
1575         if (in) {
1576                 if (in->f_mode & FMODE_READ) {
1577                         int fput_out;
1578                         struct file *out = fget_light(fdout, &fput_out);
1579
1580                         if (out) {
1581                                 if (out->f_mode & FMODE_WRITE)
1582                                         error = do_tee(in, out, len, flags);
1583                                 fput_light(out, fput_out);
1584                         }
1585                 }
1586                 fput_light(in, fput_in);
1587         }
1588
1589         return error;
1590 }