2 * "splice": joining two ropes together by interweaving their strands.
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.
8 * The traditional unix read/write is extended with a "splice()" operation
9 * that transfers data buffers to or from a pipe buffer.
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.
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>
21 #include <linux/file.h>
22 #include <linux/pagemap.h>
23 #include <linux/splice.h>
24 #include <linux/memcontrol.h>
25 #include <linux/mm_inline.h>
26 #include <linux/swap.h>
27 #include <linux/writeback.h>
28 #include <linux/buffer_head.h>
29 #include <linux/module.h>
30 #include <linux/syscalls.h>
31 #include <linux/uio.h>
32 #include <linux/security.h>
35 * Attempt to steal a page from a pipe buffer. This should perhaps go into
36 * a vm helper function, it's already simplified quite a bit by the
37 * addition of remove_mapping(). If success is returned, the caller may
38 * attempt to reuse this page for another destination.
40 static int page_cache_pipe_buf_steal(struct pipe_inode_info
*pipe
,
41 struct pipe_buffer
*buf
)
43 struct page
*page
= buf
->page
;
44 struct address_space
*mapping
;
48 mapping
= page_mapping(page
);
50 WARN_ON(!PageUptodate(page
));
53 * At least for ext2 with nobh option, we need to wait on
54 * writeback completing on this page, since we'll remove it
55 * from the pagecache. Otherwise truncate wont wait on the
56 * page, allowing the disk blocks to be reused by someone else
57 * before we actually wrote our data to them. fs corruption
60 wait_on_page_writeback(page
);
62 if (page_has_private(page
) &&
63 !try_to_release_page(page
, GFP_KERNEL
))
67 * If we succeeded in removing the mapping, set LRU flag
70 if (remove_mapping(mapping
, page
)) {
71 buf
->flags
|= PIPE_BUF_FLAG_LRU
;
77 * Raced with truncate or failed to remove page from current
78 * address space, unlock and return failure.
85 static void page_cache_pipe_buf_release(struct pipe_inode_info
*pipe
,
86 struct pipe_buffer
*buf
)
88 page_cache_release(buf
->page
);
89 buf
->flags
&= ~PIPE_BUF_FLAG_LRU
;
93 * Check whether the contents of buf is OK to access. Since the content
94 * is a page cache page, IO may be in flight.
96 static int page_cache_pipe_buf_confirm(struct pipe_inode_info
*pipe
,
97 struct pipe_buffer
*buf
)
99 struct page
*page
= buf
->page
;
102 if (!PageUptodate(page
)) {
106 * Page got truncated/unhashed. This will cause a 0-byte
107 * splice, if this is the first page.
109 if (!page
->mapping
) {
115 * Uh oh, read-error from disk.
117 if (!PageUptodate(page
)) {
123 * Page is ok afterall, we are done.
134 static const struct pipe_buf_operations page_cache_pipe_buf_ops
= {
136 .map
= generic_pipe_buf_map
,
137 .unmap
= generic_pipe_buf_unmap
,
138 .confirm
= page_cache_pipe_buf_confirm
,
139 .release
= page_cache_pipe_buf_release
,
140 .steal
= page_cache_pipe_buf_steal
,
141 .get
= generic_pipe_buf_get
,
144 static int user_page_pipe_buf_steal(struct pipe_inode_info
*pipe
,
145 struct pipe_buffer
*buf
)
147 if (!(buf
->flags
& PIPE_BUF_FLAG_GIFT
))
150 buf
->flags
|= PIPE_BUF_FLAG_LRU
;
151 return generic_pipe_buf_steal(pipe
, buf
);
154 static const struct pipe_buf_operations user_page_pipe_buf_ops
= {
156 .map
= generic_pipe_buf_map
,
157 .unmap
= generic_pipe_buf_unmap
,
158 .confirm
= generic_pipe_buf_confirm
,
159 .release
= page_cache_pipe_buf_release
,
160 .steal
= user_page_pipe_buf_steal
,
161 .get
= generic_pipe_buf_get
,
165 * splice_to_pipe - fill passed data into a pipe
166 * @pipe: pipe to fill
170 * @spd contains a map of pages and len/offset tuples, along with
171 * the struct pipe_buf_operations associated with these pages. This
172 * function will link that data to the pipe.
175 ssize_t
splice_to_pipe(struct pipe_inode_info
*pipe
,
176 struct splice_pipe_desc
*spd
)
178 unsigned int spd_pages
= spd
->nr_pages
;
179 int ret
, do_wakeup
, page_nr
;
188 if (!pipe
->readers
) {
189 send_sig(SIGPIPE
, current
, 0);
195 if (pipe
->nrbufs
< PIPE_BUFFERS
) {
196 int newbuf
= (pipe
->curbuf
+ pipe
->nrbufs
) & (PIPE_BUFFERS
- 1);
197 struct pipe_buffer
*buf
= pipe
->bufs
+ newbuf
;
199 buf
->page
= spd
->pages
[page_nr
];
200 buf
->offset
= spd
->partial
[page_nr
].offset
;
201 buf
->len
= spd
->partial
[page_nr
].len
;
202 buf
->private = spd
->partial
[page_nr
].private;
204 if (spd
->flags
& SPLICE_F_GIFT
)
205 buf
->flags
|= PIPE_BUF_FLAG_GIFT
;
214 if (!--spd
->nr_pages
)
216 if (pipe
->nrbufs
< PIPE_BUFFERS
)
222 if (spd
->flags
& SPLICE_F_NONBLOCK
) {
228 if (signal_pending(current
)) {
236 if (waitqueue_active(&pipe
->wait
))
237 wake_up_interruptible_sync(&pipe
->wait
);
238 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
242 pipe
->waiting_writers
++;
244 pipe
->waiting_writers
--;
251 if (waitqueue_active(&pipe
->wait
))
252 wake_up_interruptible(&pipe
->wait
);
253 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
256 while (page_nr
< spd_pages
)
257 spd
->spd_release(spd
, page_nr
++);
262 static void spd_release_page(struct splice_pipe_desc
*spd
, unsigned int i
)
264 page_cache_release(spd
->pages
[i
]);
268 __generic_file_splice_read(struct file
*in
, loff_t
*ppos
,
269 struct pipe_inode_info
*pipe
, size_t len
,
272 struct address_space
*mapping
= in
->f_mapping
;
273 unsigned int loff
, nr_pages
, req_pages
;
274 struct page
*pages
[PIPE_BUFFERS
];
275 struct partial_page partial
[PIPE_BUFFERS
];
277 pgoff_t index
, end_index
;
280 struct splice_pipe_desc spd
= {
284 .ops
= &page_cache_pipe_buf_ops
,
285 .spd_release
= spd_release_page
,
288 index
= *ppos
>> PAGE_CACHE_SHIFT
;
289 loff
= *ppos
& ~PAGE_CACHE_MASK
;
290 req_pages
= (len
+ loff
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
291 nr_pages
= min(req_pages
, (unsigned)PIPE_BUFFERS
);
294 * Lookup the (hopefully) full range of pages we need.
296 spd
.nr_pages
= find_get_pages_contig(mapping
, index
, nr_pages
, pages
);
297 index
+= spd
.nr_pages
;
300 * If find_get_pages_contig() returned fewer pages than we needed,
301 * readahead/allocate the rest and fill in the holes.
303 if (spd
.nr_pages
< nr_pages
)
304 page_cache_sync_readahead(mapping
, &in
->f_ra
, in
,
305 index
, req_pages
- spd
.nr_pages
);
308 while (spd
.nr_pages
< nr_pages
) {
310 * Page could be there, find_get_pages_contig() breaks on
313 page
= find_get_page(mapping
, index
);
316 * page didn't exist, allocate one.
318 page
= page_cache_alloc_cold(mapping
);
322 error
= add_to_page_cache_lru(page
, mapping
, index
,
323 mapping_gfp_mask(mapping
));
324 if (unlikely(error
)) {
325 page_cache_release(page
);
326 if (error
== -EEXIST
)
331 * add_to_page_cache() locks the page, unlock it
332 * to avoid convoluting the logic below even more.
337 pages
[spd
.nr_pages
++] = page
;
342 * Now loop over the map and see if we need to start IO on any
343 * pages, fill in the partial map, etc.
345 index
= *ppos
>> PAGE_CACHE_SHIFT
;
346 nr_pages
= spd
.nr_pages
;
348 for (page_nr
= 0; page_nr
< nr_pages
; page_nr
++) {
349 unsigned int this_len
;
355 * this_len is the max we'll use from this page
357 this_len
= min_t(unsigned long, len
, PAGE_CACHE_SIZE
- loff
);
358 page
= pages
[page_nr
];
360 if (PageReadahead(page
))
361 page_cache_async_readahead(mapping
, &in
->f_ra
, in
,
362 page
, index
, req_pages
- page_nr
);
365 * If the page isn't uptodate, we may need to start io on it
367 if (!PageUptodate(page
)) {
369 * If in nonblock mode then dont block on waiting
370 * for an in-flight io page
372 if (flags
& SPLICE_F_NONBLOCK
) {
373 if (!trylock_page(page
)) {
381 * Page was truncated, or invalidated by the
382 * filesystem. Redo the find/create, but this time the
383 * page is kept locked, so there's no chance of another
384 * race with truncate/invalidate.
386 if (!page
->mapping
) {
388 page
= find_or_create_page(mapping
, index
,
389 mapping_gfp_mask(mapping
));
395 page_cache_release(pages
[page_nr
]);
396 pages
[page_nr
] = page
;
399 * page was already under io and is now done, great
401 if (PageUptodate(page
)) {
407 * need to read in the page
409 error
= mapping
->a_ops
->readpage(in
, page
);
410 if (unlikely(error
)) {
412 * We really should re-lookup the page here,
413 * but it complicates things a lot. Instead
414 * lets just do what we already stored, and
415 * we'll get it the next time we are called.
417 if (error
== AOP_TRUNCATED_PAGE
)
425 * i_size must be checked after PageUptodate.
427 isize
= i_size_read(mapping
->host
);
428 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
429 if (unlikely(!isize
|| index
> end_index
))
433 * if this is the last page, see if we need to shrink
434 * the length and stop
436 if (end_index
== index
) {
440 * max good bytes in this page
442 plen
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
447 * force quit after adding this page
449 this_len
= min(this_len
, plen
- loff
);
453 partial
[page_nr
].offset
= loff
;
454 partial
[page_nr
].len
= this_len
;
462 * Release any pages at the end, if we quit early. 'page_nr' is how far
463 * we got, 'nr_pages' is how many pages are in the map.
465 while (page_nr
< nr_pages
)
466 page_cache_release(pages
[page_nr
++]);
467 in
->f_ra
.prev_pos
= (loff_t
)index
<< PAGE_CACHE_SHIFT
;
470 return splice_to_pipe(pipe
, &spd
);
476 * generic_file_splice_read - splice data from file to a pipe
477 * @in: file to splice from
478 * @ppos: position in @in
479 * @pipe: pipe to splice to
480 * @len: number of bytes to splice
481 * @flags: splice modifier flags
484 * Will read pages from given file and fill them into a pipe. Can be
485 * used as long as the address_space operations for the source implements
489 ssize_t
generic_file_splice_read(struct file
*in
, loff_t
*ppos
,
490 struct pipe_inode_info
*pipe
, size_t len
,
496 isize
= i_size_read(in
->f_mapping
->host
);
497 if (unlikely(*ppos
>= isize
))
500 left
= isize
- *ppos
;
501 if (unlikely(left
< len
))
504 ret
= __generic_file_splice_read(in
, ppos
, pipe
, len
, flags
);
510 EXPORT_SYMBOL(generic_file_splice_read
);
512 static const struct pipe_buf_operations default_pipe_buf_ops
= {
514 .map
= generic_pipe_buf_map
,
515 .unmap
= generic_pipe_buf_unmap
,
516 .confirm
= generic_pipe_buf_confirm
,
517 .release
= generic_pipe_buf_release
,
518 .steal
= generic_pipe_buf_steal
,
519 .get
= generic_pipe_buf_get
,
522 static ssize_t
kernel_readv(struct file
*file
, const struct iovec
*vec
,
523 unsigned long vlen
, loff_t offset
)
531 /* The cast to a user pointer is valid due to the set_fs() */
532 res
= vfs_readv(file
, (const struct iovec __user
*)vec
, vlen
, &pos
);
538 static ssize_t
kernel_writev(struct file
*file
, const struct iovec
*vec
,
539 unsigned long vlen
, loff_t
*ppos
)
546 /* The cast to a user pointer is valid due to the set_fs() */
547 res
= vfs_writev(file
, (const struct iovec __user
*)vec
, vlen
, ppos
);
553 ssize_t
default_file_splice_read(struct file
*in
, loff_t
*ppos
,
554 struct pipe_inode_info
*pipe
, size_t len
,
557 unsigned int nr_pages
;
558 unsigned int nr_freed
;
560 struct page
*pages
[PIPE_BUFFERS
];
561 struct partial_page partial
[PIPE_BUFFERS
];
562 struct iovec vec
[PIPE_BUFFERS
];
568 struct splice_pipe_desc spd
= {
572 .ops
= &default_pipe_buf_ops
,
573 .spd_release
= spd_release_page
,
576 index
= *ppos
>> PAGE_CACHE_SHIFT
;
577 offset
= *ppos
& ~PAGE_CACHE_MASK
;
578 nr_pages
= (len
+ offset
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
580 for (i
= 0; i
< nr_pages
&& i
< PIPE_BUFFERS
&& len
; i
++) {
583 page
= alloc_page(GFP_USER
);
588 this_len
= min_t(size_t, len
, PAGE_CACHE_SIZE
- offset
);
589 vec
[i
].iov_base
= (void __user
*) page_address(page
);
590 vec
[i
].iov_len
= this_len
;
597 res
= kernel_readv(in
, vec
, spd
.nr_pages
, *ppos
);
608 for (i
= 0; i
< spd
.nr_pages
; i
++) {
609 this_len
= min_t(size_t, vec
[i
].iov_len
, res
);
610 partial
[i
].offset
= 0;
611 partial
[i
].len
= this_len
;
613 __free_page(pages
[i
]);
619 spd
.nr_pages
-= nr_freed
;
621 res
= splice_to_pipe(pipe
, &spd
);
628 for (i
= 0; i
< spd
.nr_pages
; i
++)
629 __free_page(pages
[i
]);
633 EXPORT_SYMBOL(default_file_splice_read
);
636 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
637 * using sendpage(). Return the number of bytes sent.
639 static int pipe_to_sendpage(struct pipe_inode_info
*pipe
,
640 struct pipe_buffer
*buf
, struct splice_desc
*sd
)
642 struct file
*file
= sd
->u
.file
;
643 loff_t pos
= sd
->pos
;
646 ret
= buf
->ops
->confirm(pipe
, buf
);
648 more
= (sd
->flags
& SPLICE_F_MORE
) || sd
->len
< sd
->total_len
;
650 ret
= file
->f_op
->sendpage(file
, buf
->page
, buf
->offset
,
651 sd
->len
, &pos
, more
);
658 * This is a little more tricky than the file -> pipe splicing. There are
659 * basically three cases:
661 * - Destination page already exists in the address space and there
662 * are users of it. For that case we have no other option that
663 * copying the data. Tough luck.
664 * - Destination page already exists in the address space, but there
665 * are no users of it. Make sure it's uptodate, then drop it. Fall
666 * through to last case.
667 * - Destination page does not exist, we can add the pipe page to
668 * the page cache and avoid the copy.
670 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
671 * sd->flags), we attempt to migrate pages from the pipe to the output
672 * file address space page cache. This is possible if no one else has
673 * the pipe page referenced outside of the pipe and page cache. If
674 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
675 * a new page in the output file page cache and fill/dirty that.
677 int pipe_to_file(struct pipe_inode_info
*pipe
, struct pipe_buffer
*buf
,
678 struct splice_desc
*sd
)
680 struct file
*file
= sd
->u
.file
;
681 struct address_space
*mapping
= file
->f_mapping
;
682 unsigned int offset
, this_len
;
688 * make sure the data in this buffer is uptodate
690 ret
= buf
->ops
->confirm(pipe
, buf
);
694 offset
= sd
->pos
& ~PAGE_CACHE_MASK
;
697 if (this_len
+ offset
> PAGE_CACHE_SIZE
)
698 this_len
= PAGE_CACHE_SIZE
- offset
;
700 ret
= pagecache_write_begin(file
, mapping
, sd
->pos
, this_len
,
701 AOP_FLAG_UNINTERRUPTIBLE
, &page
, &fsdata
);
705 if (buf
->page
!= page
) {
707 * Careful, ->map() uses KM_USER0!
709 char *src
= buf
->ops
->map(pipe
, buf
, 1);
710 char *dst
= kmap_atomic(page
, KM_USER1
);
712 memcpy(dst
+ offset
, src
+ buf
->offset
, this_len
);
713 flush_dcache_page(page
);
714 kunmap_atomic(dst
, KM_USER1
);
715 buf
->ops
->unmap(pipe
, buf
, src
);
717 ret
= pagecache_write_end(file
, mapping
, sd
->pos
, this_len
, this_len
,
722 EXPORT_SYMBOL(pipe_to_file
);
724 static void wakeup_pipe_writers(struct pipe_inode_info
*pipe
)
727 if (waitqueue_active(&pipe
->wait
))
728 wake_up_interruptible(&pipe
->wait
);
729 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
733 * splice_from_pipe_feed - feed available data from a pipe to a file
734 * @pipe: pipe to splice from
735 * @sd: information to @actor
736 * @actor: handler that splices the data
739 * This function loops over the pipe and calls @actor to do the
740 * actual moving of a single struct pipe_buffer to the desired
741 * destination. It returns when there's no more buffers left in
742 * the pipe or if the requested number of bytes (@sd->total_len)
743 * have been copied. It returns a positive number (one) if the
744 * pipe needs to be filled with more data, zero if the required
745 * number of bytes have been copied and -errno on error.
747 * This, together with splice_from_pipe_{begin,end,next}, may be
748 * used to implement the functionality of __splice_from_pipe() when
749 * locking is required around copying the pipe buffers to the
752 int splice_from_pipe_feed(struct pipe_inode_info
*pipe
, struct splice_desc
*sd
,
757 while (pipe
->nrbufs
) {
758 struct pipe_buffer
*buf
= pipe
->bufs
+ pipe
->curbuf
;
759 const struct pipe_buf_operations
*ops
= buf
->ops
;
762 if (sd
->len
> sd
->total_len
)
763 sd
->len
= sd
->total_len
;
765 ret
= actor(pipe
, buf
, sd
);
774 sd
->num_spliced
+= ret
;
777 sd
->total_len
-= ret
;
781 ops
->release(pipe
, buf
);
782 pipe
->curbuf
= (pipe
->curbuf
+ 1) & (PIPE_BUFFERS
- 1);
785 sd
->need_wakeup
= true;
794 EXPORT_SYMBOL(splice_from_pipe_feed
);
797 * splice_from_pipe_next - wait for some data to splice from
798 * @pipe: pipe to splice from
799 * @sd: information about the splice operation
802 * This function will wait for some data and return a positive
803 * value (one) if pipe buffers are available. It will return zero
804 * or -errno if no more data needs to be spliced.
806 int splice_from_pipe_next(struct pipe_inode_info
*pipe
, struct splice_desc
*sd
)
808 while (!pipe
->nrbufs
) {
812 if (!pipe
->waiting_writers
&& sd
->num_spliced
)
815 if (sd
->flags
& SPLICE_F_NONBLOCK
)
818 if (signal_pending(current
))
821 if (sd
->need_wakeup
) {
822 wakeup_pipe_writers(pipe
);
823 sd
->need_wakeup
= false;
831 EXPORT_SYMBOL(splice_from_pipe_next
);
834 * splice_from_pipe_begin - start splicing from pipe
835 * @sd: information about the splice operation
838 * This function should be called before a loop containing
839 * splice_from_pipe_next() and splice_from_pipe_feed() to
840 * initialize the necessary fields of @sd.
842 void splice_from_pipe_begin(struct splice_desc
*sd
)
845 sd
->need_wakeup
= false;
847 EXPORT_SYMBOL(splice_from_pipe_begin
);
850 * splice_from_pipe_end - finish splicing from pipe
851 * @pipe: pipe to splice from
852 * @sd: information about the splice operation
855 * This function will wake up pipe writers if necessary. It should
856 * be called after a loop containing splice_from_pipe_next() and
857 * splice_from_pipe_feed().
859 void splice_from_pipe_end(struct pipe_inode_info
*pipe
, struct splice_desc
*sd
)
862 wakeup_pipe_writers(pipe
);
864 EXPORT_SYMBOL(splice_from_pipe_end
);
867 * __splice_from_pipe - splice data from a pipe to given actor
868 * @pipe: pipe to splice from
869 * @sd: information to @actor
870 * @actor: handler that splices the data
873 * This function does little more than loop over the pipe and call
874 * @actor to do the actual moving of a single struct pipe_buffer to
875 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
879 ssize_t
__splice_from_pipe(struct pipe_inode_info
*pipe
, struct splice_desc
*sd
,
884 splice_from_pipe_begin(sd
);
886 ret
= splice_from_pipe_next(pipe
, sd
);
888 ret
= splice_from_pipe_feed(pipe
, sd
, actor
);
890 splice_from_pipe_end(pipe
, sd
);
892 return sd
->num_spliced
? sd
->num_spliced
: ret
;
894 EXPORT_SYMBOL(__splice_from_pipe
);
897 * splice_from_pipe - splice data from a pipe to a file
898 * @pipe: pipe to splice from
899 * @out: file to splice to
900 * @ppos: position in @out
901 * @len: how many bytes to splice
902 * @flags: splice modifier flags
903 * @actor: handler that splices the data
906 * See __splice_from_pipe. This function locks the pipe inode,
907 * otherwise it's identical to __splice_from_pipe().
910 ssize_t
splice_from_pipe(struct pipe_inode_info
*pipe
, struct file
*out
,
911 loff_t
*ppos
, size_t len
, unsigned int flags
,
915 struct splice_desc sd
= {
923 ret
= __splice_from_pipe(pipe
, &sd
, actor
);
930 * generic_file_splice_write - splice data from a pipe to a file
932 * @out: file to write to
933 * @ppos: position in @out
934 * @len: number of bytes to splice
935 * @flags: splice modifier flags
938 * Will either move or copy pages (determined by @flags options) from
939 * the given pipe inode to the given file.
943 generic_file_splice_write(struct pipe_inode_info
*pipe
, struct file
*out
,
944 loff_t
*ppos
, size_t len
, unsigned int flags
)
946 struct address_space
*mapping
= out
->f_mapping
;
947 struct inode
*inode
= mapping
->host
;
948 struct splice_desc sd
= {
958 splice_from_pipe_begin(&sd
);
960 ret
= splice_from_pipe_next(pipe
, &sd
);
964 mutex_lock_nested(&inode
->i_mutex
, I_MUTEX_CHILD
);
965 ret
= file_remove_suid(out
);
967 ret
= splice_from_pipe_feed(pipe
, &sd
, pipe_to_file
);
968 mutex_unlock(&inode
->i_mutex
);
970 splice_from_pipe_end(pipe
, &sd
);
975 ret
= sd
.num_spliced
;
978 unsigned long nr_pages
;
981 nr_pages
= (ret
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
984 * If file or inode is SYNC and we actually wrote some data,
987 if (unlikely((out
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
990 mutex_lock(&inode
->i_mutex
);
991 err
= generic_osync_inode(inode
, mapping
,
992 OSYNC_METADATA
|OSYNC_DATA
);
993 mutex_unlock(&inode
->i_mutex
);
998 balance_dirty_pages_ratelimited_nr(mapping
, nr_pages
);
1004 EXPORT_SYMBOL(generic_file_splice_write
);
1006 static struct pipe_buffer
*nth_pipe_buf(struct pipe_inode_info
*pipe
, int n
)
1008 return &pipe
->bufs
[(pipe
->curbuf
+ n
) % PIPE_BUFFERS
];
1011 static ssize_t
default_file_splice_write(struct pipe_inode_info
*pipe
,
1012 struct file
*out
, loff_t
*ppos
,
1013 size_t len
, unsigned int flags
)
1016 ssize_t total_len
= 0;
1021 struct pipe_buffer
*buf
;
1022 void *data
[PIPE_BUFFERS
];
1023 struct iovec vec
[PIPE_BUFFERS
];
1024 unsigned int nr_pages
= 0;
1025 unsigned int write_len
= 0;
1026 unsigned int now_len
= len
;
1027 unsigned int this_len
;
1030 BUG_ON(pipe
->nrbufs
> PIPE_BUFFERS
);
1031 for (i
= 0; i
< pipe
->nrbufs
&& now_len
; i
++) {
1032 buf
= nth_pipe_buf(pipe
, i
);
1034 ret
= buf
->ops
->confirm(pipe
, buf
);
1038 data
[i
] = buf
->ops
->map(pipe
, buf
, 0);
1039 this_len
= min(buf
->len
, now_len
);
1040 vec
[i
].iov_base
= (void __user
*) data
[i
] + buf
->offset
;
1041 vec
[i
].iov_len
= this_len
;
1042 now_len
-= this_len
;
1043 write_len
+= this_len
;
1048 ret
= kernel_writev(out
, vec
, nr_pages
, ppos
);
1057 for (i
= 0; i
< nr_pages
; i
++) {
1058 buf
= nth_pipe_buf(pipe
, i
);
1059 buf
->ops
->unmap(pipe
, buf
, data
[i
]);
1062 this_len
= min_t(unsigned, vec
[i
].iov_len
, ret
);
1063 buf
->offset
+= this_len
;
1064 buf
->len
-= this_len
;
1072 while (pipe
->nrbufs
) {
1073 const struct pipe_buf_operations
*ops
;
1075 buf
= nth_pipe_buf(pipe
, 0);
1081 ops
->release(pipe
, buf
);
1082 pipe
->curbuf
= (pipe
->curbuf
+ 1) % PIPE_BUFFERS
;
1092 if (!pipe
->waiting_writers
) {
1097 if (flags
& SPLICE_F_NONBLOCK
) {
1102 if (signal_pending(current
)) {
1108 wakeup_pipe_writers(pipe
);
1117 wakeup_pipe_writers(pipe
);
1119 return total_len
? total_len
: ret
;
1123 * generic_splice_sendpage - splice data from a pipe to a socket
1124 * @pipe: pipe to splice from
1125 * @out: socket to write to
1126 * @ppos: position in @out
1127 * @len: number of bytes to splice
1128 * @flags: splice modifier flags
1131 * Will send @len bytes from the pipe to a network socket. No data copying
1135 ssize_t
generic_splice_sendpage(struct pipe_inode_info
*pipe
, struct file
*out
,
1136 loff_t
*ppos
, size_t len
, unsigned int flags
)
1138 return splice_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_sendpage
);
1141 EXPORT_SYMBOL(generic_splice_sendpage
);
1144 * Attempt to initiate a splice from pipe to file.
1146 static long do_splice_from(struct pipe_inode_info
*pipe
, struct file
*out
,
1147 loff_t
*ppos
, size_t len
, unsigned int flags
)
1149 ssize_t (*splice_write
)(struct pipe_inode_info
*, struct file
*,
1150 loff_t
*, size_t, unsigned int);
1153 if (unlikely(!(out
->f_mode
& FMODE_WRITE
)))
1156 if (unlikely(out
->f_flags
& O_APPEND
))
1159 ret
= rw_verify_area(WRITE
, out
, ppos
, len
);
1160 if (unlikely(ret
< 0))
1163 splice_write
= out
->f_op
->splice_write
;
1165 splice_write
= default_file_splice_write
;
1167 return splice_write(pipe
, out
, ppos
, len
, flags
);
1171 * Attempt to initiate a splice from a file to a pipe.
1173 static long do_splice_to(struct file
*in
, loff_t
*ppos
,
1174 struct pipe_inode_info
*pipe
, size_t len
,
1177 ssize_t (*splice_read
)(struct file
*, loff_t
*,
1178 struct pipe_inode_info
*, size_t, unsigned int);
1181 if (unlikely(!(in
->f_mode
& FMODE_READ
)))
1184 ret
= rw_verify_area(READ
, in
, ppos
, len
);
1185 if (unlikely(ret
< 0))
1188 splice_read
= in
->f_op
->splice_read
;
1190 splice_read
= default_file_splice_read
;
1192 return splice_read(in
, ppos
, pipe
, len
, flags
);
1196 * splice_direct_to_actor - splices data directly between two non-pipes
1197 * @in: file to splice from
1198 * @sd: actor information on where to splice to
1199 * @actor: handles the data splicing
1202 * This is a special case helper to splice directly between two
1203 * points, without requiring an explicit pipe. Internally an allocated
1204 * pipe is cached in the process, and reused during the lifetime of
1208 ssize_t
splice_direct_to_actor(struct file
*in
, struct splice_desc
*sd
,
1209 splice_direct_actor
*actor
)
1211 struct pipe_inode_info
*pipe
;
1218 * We require the input being a regular file, as we don't want to
1219 * randomly drop data for eg socket -> socket splicing. Use the
1220 * piped splicing for that!
1222 i_mode
= in
->f_path
.dentry
->d_inode
->i_mode
;
1223 if (unlikely(!S_ISREG(i_mode
) && !S_ISBLK(i_mode
)))
1227 * neither in nor out is a pipe, setup an internal pipe attached to
1228 * 'out' and transfer the wanted data from 'in' to 'out' through that
1230 pipe
= current
->splice_pipe
;
1231 if (unlikely(!pipe
)) {
1232 pipe
= alloc_pipe_info(NULL
);
1237 * We don't have an immediate reader, but we'll read the stuff
1238 * out of the pipe right after the splice_to_pipe(). So set
1239 * PIPE_READERS appropriately.
1243 current
->splice_pipe
= pipe
;
1251 len
= sd
->total_len
;
1255 * Don't block on output, we have to drain the direct pipe.
1257 sd
->flags
&= ~SPLICE_F_NONBLOCK
;
1261 loff_t pos
= sd
->pos
, prev_pos
= pos
;
1263 ret
= do_splice_to(in
, &pos
, pipe
, len
, flags
);
1264 if (unlikely(ret
<= 0))
1268 sd
->total_len
= read_len
;
1271 * NOTE: nonblocking mode only applies to the input. We
1272 * must not do the output in nonblocking mode as then we
1273 * could get stuck data in the internal pipe:
1275 ret
= actor(pipe
, sd
);
1276 if (unlikely(ret
<= 0)) {
1285 if (ret
< read_len
) {
1286 sd
->pos
= prev_pos
+ ret
;
1292 pipe
->nrbufs
= pipe
->curbuf
= 0;
1298 * If we did an incomplete transfer we must release
1299 * the pipe buffers in question:
1301 for (i
= 0; i
< PIPE_BUFFERS
; i
++) {
1302 struct pipe_buffer
*buf
= pipe
->bufs
+ i
;
1305 buf
->ops
->release(pipe
, buf
);
1315 EXPORT_SYMBOL(splice_direct_to_actor
);
1317 static int direct_splice_actor(struct pipe_inode_info
*pipe
,
1318 struct splice_desc
*sd
)
1320 struct file
*file
= sd
->u
.file
;
1322 return do_splice_from(pipe
, file
, &sd
->pos
, sd
->total_len
, sd
->flags
);
1326 * do_splice_direct - splices data directly between two files
1327 * @in: file to splice from
1328 * @ppos: input file offset
1329 * @out: file to splice to
1330 * @len: number of bytes to splice
1331 * @flags: splice modifier flags
1334 * For use by do_sendfile(). splice can easily emulate sendfile, but
1335 * doing it in the application would incur an extra system call
1336 * (splice in + splice out, as compared to just sendfile()). So this helper
1337 * can splice directly through a process-private pipe.
1340 long do_splice_direct(struct file
*in
, loff_t
*ppos
, struct file
*out
,
1341 size_t len
, unsigned int flags
)
1343 struct splice_desc sd
= {
1352 ret
= splice_direct_to_actor(in
, &sd
, direct_splice_actor
);
1359 static int splice_pipe_to_pipe(struct pipe_inode_info
*ipipe
,
1360 struct pipe_inode_info
*opipe
,
1361 size_t len
, unsigned int flags
);
1363 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1364 * location, so checking ->i_pipe is not enough to verify that this is a
1367 static inline struct pipe_inode_info
*pipe_info(struct inode
*inode
)
1369 if (S_ISFIFO(inode
->i_mode
))
1370 return inode
->i_pipe
;
1376 * Determine where to splice to/from.
1378 static long do_splice(struct file
*in
, loff_t __user
*off_in
,
1379 struct file
*out
, loff_t __user
*off_out
,
1380 size_t len
, unsigned int flags
)
1382 struct pipe_inode_info
*ipipe
;
1383 struct pipe_inode_info
*opipe
;
1384 loff_t offset
, *off
;
1387 ipipe
= pipe_info(in
->f_path
.dentry
->d_inode
);
1388 opipe
= pipe_info(out
->f_path
.dentry
->d_inode
);
1390 if (ipipe
&& opipe
) {
1391 if (off_in
|| off_out
)
1394 if (!(in
->f_mode
& FMODE_READ
))
1397 if (!(out
->f_mode
& FMODE_WRITE
))
1400 /* Splicing to self would be fun, but... */
1404 return splice_pipe_to_pipe(ipipe
, opipe
, len
, flags
);
1411 if (out
->f_op
->llseek
== no_llseek
)
1413 if (copy_from_user(&offset
, off_out
, sizeof(loff_t
)))
1419 ret
= do_splice_from(ipipe
, out
, off
, len
, flags
);
1421 if (off_out
&& copy_to_user(off_out
, off
, sizeof(loff_t
)))
1431 if (in
->f_op
->llseek
== no_llseek
)
1433 if (copy_from_user(&offset
, off_in
, sizeof(loff_t
)))
1439 ret
= do_splice_to(in
, off
, opipe
, len
, flags
);
1441 if (off_in
&& copy_to_user(off_in
, off
, sizeof(loff_t
)))
1451 * Map an iov into an array of pages and offset/length tupples. With the
1452 * partial_page structure, we can map several non-contiguous ranges into
1453 * our ones pages[] map instead of splitting that operation into pieces.
1454 * Could easily be exported as a generic helper for other users, in which
1455 * case one would probably want to add a 'max_nr_pages' parameter as well.
1457 static int get_iovec_page_array(const struct iovec __user
*iov
,
1458 unsigned int nr_vecs
, struct page
**pages
,
1459 struct partial_page
*partial
, int aligned
)
1461 int buffers
= 0, error
= 0;
1464 unsigned long off
, npages
;
1471 if (copy_from_user(&entry
, iov
, sizeof(entry
)))
1474 base
= entry
.iov_base
;
1475 len
= entry
.iov_len
;
1478 * Sanity check this iovec. 0 read succeeds.
1484 if (!access_ok(VERIFY_READ
, base
, len
))
1488 * Get this base offset and number of pages, then map
1489 * in the user pages.
1491 off
= (unsigned long) base
& ~PAGE_MASK
;
1494 * If asked for alignment, the offset must be zero and the
1495 * length a multiple of the PAGE_SIZE.
1498 if (aligned
&& (off
|| len
& ~PAGE_MASK
))
1501 npages
= (off
+ len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1502 if (npages
> PIPE_BUFFERS
- buffers
)
1503 npages
= PIPE_BUFFERS
- buffers
;
1505 error
= get_user_pages_fast((unsigned long)base
, npages
,
1506 0, &pages
[buffers
]);
1508 if (unlikely(error
<= 0))
1512 * Fill this contiguous range into the partial page map.
1514 for (i
= 0; i
< error
; i
++) {
1515 const int plen
= min_t(size_t, len
, PAGE_SIZE
- off
);
1517 partial
[buffers
].offset
= off
;
1518 partial
[buffers
].len
= plen
;
1526 * We didn't complete this iov, stop here since it probably
1527 * means we have to move some of this into a pipe to
1528 * be able to continue.
1534 * Don't continue if we mapped fewer pages than we asked for,
1535 * or if we mapped the max number of pages that we have
1538 if (error
< npages
|| buffers
== PIPE_BUFFERS
)
1551 static int pipe_to_user(struct pipe_inode_info
*pipe
, struct pipe_buffer
*buf
,
1552 struct splice_desc
*sd
)
1557 ret
= buf
->ops
->confirm(pipe
, buf
);
1562 * See if we can use the atomic maps, by prefaulting in the
1563 * pages and doing an atomic copy
1565 if (!fault_in_pages_writeable(sd
->u
.userptr
, sd
->len
)) {
1566 src
= buf
->ops
->map(pipe
, buf
, 1);
1567 ret
= __copy_to_user_inatomic(sd
->u
.userptr
, src
+ buf
->offset
,
1569 buf
->ops
->unmap(pipe
, buf
, src
);
1577 * No dice, use slow non-atomic map and copy
1579 src
= buf
->ops
->map(pipe
, buf
, 0);
1582 if (copy_to_user(sd
->u
.userptr
, src
+ buf
->offset
, sd
->len
))
1585 buf
->ops
->unmap(pipe
, buf
, src
);
1588 sd
->u
.userptr
+= ret
;
1593 * For lack of a better implementation, implement vmsplice() to userspace
1594 * as a simple copy of the pipes pages to the user iov.
1596 static long vmsplice_to_user(struct file
*file
, const struct iovec __user
*iov
,
1597 unsigned long nr_segs
, unsigned int flags
)
1599 struct pipe_inode_info
*pipe
;
1600 struct splice_desc sd
;
1605 pipe
= pipe_info(file
->f_path
.dentry
->d_inode
);
1617 * Get user address base and length for this iovec.
1619 error
= get_user(base
, &iov
->iov_base
);
1620 if (unlikely(error
))
1622 error
= get_user(len
, &iov
->iov_len
);
1623 if (unlikely(error
))
1627 * Sanity check this iovec. 0 read succeeds.
1631 if (unlikely(!base
)) {
1636 if (unlikely(!access_ok(VERIFY_WRITE
, base
, len
))) {
1644 sd
.u
.userptr
= base
;
1647 size
= __splice_from_pipe(pipe
, &sd
, pipe_to_user
);
1673 * vmsplice splices a user address range into a pipe. It can be thought of
1674 * as splice-from-memory, where the regular splice is splice-from-file (or
1675 * to file). In both cases the output is a pipe, naturally.
1677 static long vmsplice_to_pipe(struct file
*file
, const struct iovec __user
*iov
,
1678 unsigned long nr_segs
, unsigned int flags
)
1680 struct pipe_inode_info
*pipe
;
1681 struct page
*pages
[PIPE_BUFFERS
];
1682 struct partial_page partial
[PIPE_BUFFERS
];
1683 struct splice_pipe_desc spd
= {
1687 .ops
= &user_page_pipe_buf_ops
,
1688 .spd_release
= spd_release_page
,
1691 pipe
= pipe_info(file
->f_path
.dentry
->d_inode
);
1695 spd
.nr_pages
= get_iovec_page_array(iov
, nr_segs
, pages
, partial
,
1696 flags
& SPLICE_F_GIFT
);
1697 if (spd
.nr_pages
<= 0)
1698 return spd
.nr_pages
;
1700 return splice_to_pipe(pipe
, &spd
);
1704 * Note that vmsplice only really supports true splicing _from_ user memory
1705 * to a pipe, not the other way around. Splicing from user memory is a simple
1706 * operation that can be supported without any funky alignment restrictions
1707 * or nasty vm tricks. We simply map in the user memory and fill them into
1708 * a pipe. The reverse isn't quite as easy, though. There are two possible
1709 * solutions for that:
1711 * - memcpy() the data internally, at which point we might as well just
1712 * do a regular read() on the buffer anyway.
1713 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1714 * has restriction limitations on both ends of the pipe).
1716 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1719 SYSCALL_DEFINE4(vmsplice
, int, fd
, const struct iovec __user
*, iov
,
1720 unsigned long, nr_segs
, unsigned int, flags
)
1726 if (unlikely(nr_segs
> UIO_MAXIOV
))
1728 else if (unlikely(!nr_segs
))
1732 file
= fget_light(fd
, &fput
);
1734 if (file
->f_mode
& FMODE_WRITE
)
1735 error
= vmsplice_to_pipe(file
, iov
, nr_segs
, flags
);
1736 else if (file
->f_mode
& FMODE_READ
)
1737 error
= vmsplice_to_user(file
, iov
, nr_segs
, flags
);
1739 fput_light(file
, fput
);
1745 SYSCALL_DEFINE6(splice
, int, fd_in
, loff_t __user
*, off_in
,
1746 int, fd_out
, loff_t __user
*, off_out
,
1747 size_t, len
, unsigned int, flags
)
1750 struct file
*in
, *out
;
1751 int fput_in
, fput_out
;
1757 in
= fget_light(fd_in
, &fput_in
);
1759 if (in
->f_mode
& FMODE_READ
) {
1760 out
= fget_light(fd_out
, &fput_out
);
1762 if (out
->f_mode
& FMODE_WRITE
)
1763 error
= do_splice(in
, off_in
,
1766 fput_light(out
, fput_out
);
1770 fput_light(in
, fput_in
);
1777 * Make sure there's data to read. Wait for input if we can, otherwise
1778 * return an appropriate error.
1780 static int ipipe_prep(struct pipe_inode_info
*pipe
, unsigned int flags
)
1785 * Check ->nrbufs without the inode lock first. This function
1786 * is speculative anyways, so missing one is ok.
1794 while (!pipe
->nrbufs
) {
1795 if (signal_pending(current
)) {
1801 if (!pipe
->waiting_writers
) {
1802 if (flags
& SPLICE_F_NONBLOCK
) {
1815 * Make sure there's writeable room. Wait for room if we can, otherwise
1816 * return an appropriate error.
1818 static int opipe_prep(struct pipe_inode_info
*pipe
, unsigned int flags
)
1823 * Check ->nrbufs without the inode lock first. This function
1824 * is speculative anyways, so missing one is ok.
1826 if (pipe
->nrbufs
< PIPE_BUFFERS
)
1832 while (pipe
->nrbufs
>= PIPE_BUFFERS
) {
1833 if (!pipe
->readers
) {
1834 send_sig(SIGPIPE
, current
, 0);
1838 if (flags
& SPLICE_F_NONBLOCK
) {
1842 if (signal_pending(current
)) {
1846 pipe
->waiting_writers
++;
1848 pipe
->waiting_writers
--;
1856 * Splice contents of ipipe to opipe.
1858 static int splice_pipe_to_pipe(struct pipe_inode_info
*ipipe
,
1859 struct pipe_inode_info
*opipe
,
1860 size_t len
, unsigned int flags
)
1862 struct pipe_buffer
*ibuf
, *obuf
;
1864 bool input_wakeup
= false;
1868 ret
= ipipe_prep(ipipe
, flags
);
1872 ret
= opipe_prep(opipe
, flags
);
1877 * Potential ABBA deadlock, work around it by ordering lock
1878 * grabbing by pipe info address. Otherwise two different processes
1879 * could deadlock (one doing tee from A -> B, the other from B -> A).
1881 pipe_double_lock(ipipe
, opipe
);
1884 if (!opipe
->readers
) {
1885 send_sig(SIGPIPE
, current
, 0);
1891 if (!ipipe
->nrbufs
&& !ipipe
->writers
)
1895 * Cannot make any progress, because either the input
1896 * pipe is empty or the output pipe is full.
1898 if (!ipipe
->nrbufs
|| opipe
->nrbufs
>= PIPE_BUFFERS
) {
1899 /* Already processed some buffers, break */
1903 if (flags
& SPLICE_F_NONBLOCK
) {
1909 * We raced with another reader/writer and haven't
1910 * managed to process any buffers. A zero return
1911 * value means EOF, so retry instead.
1918 ibuf
= ipipe
->bufs
+ ipipe
->curbuf
;
1919 nbuf
= (opipe
->curbuf
+ opipe
->nrbufs
) % PIPE_BUFFERS
;
1920 obuf
= opipe
->bufs
+ nbuf
;
1922 if (len
>= ibuf
->len
) {
1924 * Simply move the whole buffer from ipipe to opipe
1929 ipipe
->curbuf
= (ipipe
->curbuf
+ 1) % PIPE_BUFFERS
;
1931 input_wakeup
= true;
1934 * Get a reference to this pipe buffer,
1935 * so we can copy the contents over.
1937 ibuf
->ops
->get(ipipe
, ibuf
);
1941 * Don't inherit the gift flag, we need to
1942 * prevent multiple steals of this page.
1944 obuf
->flags
&= ~PIPE_BUF_FLAG_GIFT
;
1948 ibuf
->offset
+= obuf
->len
;
1949 ibuf
->len
-= obuf
->len
;
1959 * If we put data in the output pipe, wakeup any potential readers.
1963 if (waitqueue_active(&opipe
->wait
))
1964 wake_up_interruptible(&opipe
->wait
);
1965 kill_fasync(&opipe
->fasync_readers
, SIGIO
, POLL_IN
);
1968 wakeup_pipe_writers(ipipe
);
1974 * Link contents of ipipe to opipe.
1976 static int link_pipe(struct pipe_inode_info
*ipipe
,
1977 struct pipe_inode_info
*opipe
,
1978 size_t len
, unsigned int flags
)
1980 struct pipe_buffer
*ibuf
, *obuf
;
1981 int ret
= 0, i
= 0, nbuf
;
1984 * Potential ABBA deadlock, work around it by ordering lock
1985 * grabbing by pipe info address. Otherwise two different processes
1986 * could deadlock (one doing tee from A -> B, the other from B -> A).
1988 pipe_double_lock(ipipe
, opipe
);
1991 if (!opipe
->readers
) {
1992 send_sig(SIGPIPE
, current
, 0);
1999 * If we have iterated all input buffers or ran out of
2000 * output room, break.
2002 if (i
>= ipipe
->nrbufs
|| opipe
->nrbufs
>= PIPE_BUFFERS
)
2005 ibuf
= ipipe
->bufs
+ ((ipipe
->curbuf
+ i
) & (PIPE_BUFFERS
- 1));
2006 nbuf
= (opipe
->curbuf
+ opipe
->nrbufs
) & (PIPE_BUFFERS
- 1);
2009 * Get a reference to this pipe buffer,
2010 * so we can copy the contents over.
2012 ibuf
->ops
->get(ipipe
, ibuf
);
2014 obuf
= opipe
->bufs
+ nbuf
;
2018 * Don't inherit the gift flag, we need to
2019 * prevent multiple steals of this page.
2021 obuf
->flags
&= ~PIPE_BUF_FLAG_GIFT
;
2023 if (obuf
->len
> len
)
2033 * return EAGAIN if we have the potential of some data in the
2034 * future, otherwise just return 0
2036 if (!ret
&& ipipe
->waiting_writers
&& (flags
& SPLICE_F_NONBLOCK
))
2043 * If we put data in the output pipe, wakeup any potential readers.
2047 if (waitqueue_active(&opipe
->wait
))
2048 wake_up_interruptible(&opipe
->wait
);
2049 kill_fasync(&opipe
->fasync_readers
, SIGIO
, POLL_IN
);
2056 * This is a tee(1) implementation that works on pipes. It doesn't copy
2057 * any data, it simply references the 'in' pages on the 'out' pipe.
2058 * The 'flags' used are the SPLICE_F_* variants, currently the only
2059 * applicable one is SPLICE_F_NONBLOCK.
2061 static long do_tee(struct file
*in
, struct file
*out
, size_t len
,
2064 struct pipe_inode_info
*ipipe
= pipe_info(in
->f_path
.dentry
->d_inode
);
2065 struct pipe_inode_info
*opipe
= pipe_info(out
->f_path
.dentry
->d_inode
);
2069 * Duplicate the contents of ipipe to opipe without actually
2072 if (ipipe
&& opipe
&& ipipe
!= opipe
) {
2074 * Keep going, unless we encounter an error. The ipipe/opipe
2075 * ordering doesn't really matter.
2077 ret
= ipipe_prep(ipipe
, flags
);
2079 ret
= opipe_prep(opipe
, flags
);
2081 ret
= link_pipe(ipipe
, opipe
, len
, flags
);
2088 SYSCALL_DEFINE4(tee
, int, fdin
, int, fdout
, size_t, len
, unsigned int, flags
)
2097 in
= fget_light(fdin
, &fput_in
);
2099 if (in
->f_mode
& FMODE_READ
) {
2101 struct file
*out
= fget_light(fdout
, &fput_out
);
2104 if (out
->f_mode
& FMODE_WRITE
)
2105 error
= do_tee(in
, out
, len
, flags
);
2106 fput_light(out
, fput_out
);
2109 fput_light(in
, fput_in
);