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@suse.de>
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/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>
32 * Passed to the actors
35 unsigned int len
, total_len
; /* current and remaining length */
36 unsigned int flags
; /* splice flags */
37 struct file
*file
; /* file to read/write */
38 loff_t pos
; /* file position */
42 * Attempt to steal a page from a pipe buffer. This should perhaps go into
43 * a vm helper function, it's already simplified quite a bit by the
44 * addition of remove_mapping(). If success is returned, the caller may
45 * attempt to reuse this page for another destination.
47 static int page_cache_pipe_buf_steal(struct pipe_inode_info
*info
,
48 struct pipe_buffer
*buf
)
50 struct page
*page
= buf
->page
;
51 struct address_space
*mapping
= page_mapping(page
);
55 WARN_ON(!PageUptodate(page
));
58 * At least for ext2 with nobh option, we need to wait on writeback
59 * completing on this page, since we'll remove it from the pagecache.
60 * Otherwise truncate wont wait on the page, allowing the disk
61 * blocks to be reused by someone else before we actually wrote our
62 * data to them. fs corruption ensues.
64 wait_on_page_writeback(page
);
66 if (PagePrivate(page
))
67 try_to_release_page(page
, mapping_gfp_mask(mapping
));
69 if (!remove_mapping(mapping
, page
)) {
74 buf
->flags
|= PIPE_BUF_FLAG_STOLEN
| PIPE_BUF_FLAG_LRU
;
78 static void page_cache_pipe_buf_release(struct pipe_inode_info
*info
,
79 struct pipe_buffer
*buf
)
81 page_cache_release(buf
->page
);
83 buf
->flags
&= ~(PIPE_BUF_FLAG_STOLEN
| PIPE_BUF_FLAG_LRU
);
86 static void *page_cache_pipe_buf_map(struct file
*file
,
87 struct pipe_inode_info
*info
,
88 struct pipe_buffer
*buf
)
90 struct page
*page
= buf
->page
;
93 if (!PageUptodate(page
)) {
97 * Page got truncated/unhashed. This will cause a 0-byte
98 * splice, if this is the first page.
100 if (!page
->mapping
) {
106 * Uh oh, read-error from disk.
108 if (!PageUptodate(page
)) {
114 * Page is ok afterall, fall through to mapping.
125 static void page_cache_pipe_buf_unmap(struct pipe_inode_info
*info
,
126 struct pipe_buffer
*buf
)
131 static void page_cache_pipe_buf_get(struct pipe_inode_info
*info
,
132 struct pipe_buffer
*buf
)
134 page_cache_get(buf
->page
);
137 static struct pipe_buf_operations page_cache_pipe_buf_ops
= {
139 .map
= page_cache_pipe_buf_map
,
140 .unmap
= page_cache_pipe_buf_unmap
,
141 .release
= page_cache_pipe_buf_release
,
142 .steal
= page_cache_pipe_buf_steal
,
143 .get
= page_cache_pipe_buf_get
,
147 * Pipe output worker. This sets up our pipe format with the page cache
148 * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
150 static ssize_t
move_to_pipe(struct pipe_inode_info
*pipe
, struct page
**pages
,
151 int nr_pages
, unsigned long len
,
152 unsigned int offset
, unsigned int flags
)
154 int ret
, do_wakeup
, i
;
161 mutex_lock(&pipe
->inode
->i_mutex
);
164 if (!pipe
->readers
) {
165 send_sig(SIGPIPE
, current
, 0);
171 if (pipe
->nrbufs
< PIPE_BUFFERS
) {
172 int newbuf
= (pipe
->curbuf
+ pipe
->nrbufs
) & (PIPE_BUFFERS
- 1);
173 struct pipe_buffer
*buf
= pipe
->bufs
+ newbuf
;
174 struct page
*page
= pages
[i
++];
175 unsigned long this_len
;
177 this_len
= PAGE_CACHE_SIZE
- offset
;
182 buf
->offset
= offset
;
184 buf
->ops
= &page_cache_pipe_buf_ops
;
196 if (pipe
->nrbufs
< PIPE_BUFFERS
)
202 if (flags
& SPLICE_F_NONBLOCK
) {
208 if (signal_pending(current
)) {
216 if (waitqueue_active(&pipe
->wait
))
217 wake_up_interruptible_sync(&pipe
->wait
);
218 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
222 pipe
->waiting_writers
++;
224 pipe
->waiting_writers
--;
228 mutex_unlock(&pipe
->inode
->i_mutex
);
232 if (waitqueue_active(&pipe
->wait
))
233 wake_up_interruptible(&pipe
->wait
);
234 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
238 page_cache_release(pages
[i
++]);
244 __generic_file_splice_read(struct file
*in
, loff_t
*ppos
,
245 struct pipe_inode_info
*pipe
, size_t len
,
248 struct address_space
*mapping
= in
->f_mapping
;
249 unsigned int loff
, offset
, nr_pages
;
250 struct page
*pages
[PIPE_BUFFERS
];
252 pgoff_t index
, end_index
;
257 index
= *ppos
>> PAGE_CACHE_SHIFT
;
258 loff
= offset
= *ppos
& ~PAGE_CACHE_MASK
;
259 nr_pages
= (len
+ offset
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
261 if (nr_pages
> PIPE_BUFFERS
)
262 nr_pages
= PIPE_BUFFERS
;
265 * Initiate read-ahead on this page range. however, don't call into
266 * read-ahead if this is a non-zero offset (we are likely doing small
267 * chunk splice and the page is already there) for a single page.
269 if (!offset
|| nr_pages
> 1)
270 do_page_cache_readahead(mapping
, in
, index
, nr_pages
);
273 * Now fill in the holes:
277 for (i
= 0; i
< nr_pages
; i
++, index
++) {
280 * lookup the page for this index
282 page
= find_get_page(mapping
, index
);
285 * page didn't exist, allocate one
287 page
= page_cache_alloc_cold(mapping
);
291 error
= add_to_page_cache_lru(page
, mapping
, index
,
292 mapping_gfp_mask(mapping
));
293 if (unlikely(error
)) {
294 page_cache_release(page
);
302 * If the page isn't uptodate, we may need to start io on it
304 if (!PageUptodate(page
)) {
306 * If in nonblock mode then dont block on waiting
307 * for an in-flight io page
309 if (flags
& SPLICE_F_NONBLOCK
)
315 * page was truncated, stop here. if this isn't the
316 * first page, we'll just complete what we already
319 if (!page
->mapping
) {
321 page_cache_release(page
);
325 * page was already under io and is now done, great
327 if (PageUptodate(page
)) {
334 * need to read in the page
336 error
= mapping
->a_ops
->readpage(in
, page
);
338 if (unlikely(error
)) {
339 page_cache_release(page
);
340 if (error
== AOP_TRUNCATED_PAGE
)
346 * i_size must be checked after ->readpage().
348 isize
= i_size_read(mapping
->host
);
349 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
350 if (unlikely(!isize
|| index
> end_index
)) {
351 page_cache_release(page
);
356 * if this is the last page, see if we need to shrink
357 * the length and stop
359 if (end_index
== index
) {
360 loff
= PAGE_CACHE_SIZE
- (isize
& ~PAGE_CACHE_MASK
);
361 if (bytes
+ loff
> isize
) {
362 page_cache_release(page
);
366 * force quit after adding this page
373 bytes
+= PAGE_CACHE_SIZE
- loff
;
378 return move_to_pipe(pipe
, pages
, i
, bytes
, offset
, flags
);
384 * generic_file_splice_read - splice data from file to a pipe
385 * @in: file to splice from
386 * @pipe: pipe to splice to
387 * @len: number of bytes to splice
388 * @flags: splice modifier flags
390 * Will read pages from given file and fill them into a pipe.
392 ssize_t
generic_file_splice_read(struct file
*in
, loff_t
*ppos
,
393 struct pipe_inode_info
*pipe
, size_t len
,
403 ret
= __generic_file_splice_read(in
, ppos
, pipe
, len
, flags
);
410 if (flags
& SPLICE_F_NONBLOCK
) {
427 EXPORT_SYMBOL(generic_file_splice_read
);
430 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
433 static int pipe_to_sendpage(struct pipe_inode_info
*info
,
434 struct pipe_buffer
*buf
, struct splice_desc
*sd
)
436 struct file
*file
= sd
->file
;
437 loff_t pos
= sd
->pos
;
444 * Sub-optimal, but we are limited by the pipe ->map. We don't
445 * need a kmap'ed buffer here, we just want to make sure we
446 * have the page pinned if the pipe page originates from the
449 ptr
= buf
->ops
->map(file
, info
, buf
);
453 offset
= pos
& ~PAGE_CACHE_MASK
;
454 more
= (sd
->flags
& SPLICE_F_MORE
) || sd
->len
< sd
->total_len
;
456 ret
= file
->f_op
->sendpage(file
, buf
->page
, offset
, sd
->len
, &pos
,more
);
458 buf
->ops
->unmap(info
, buf
);
466 * This is a little more tricky than the file -> pipe splicing. There are
467 * basically three cases:
469 * - Destination page already exists in the address space and there
470 * are users of it. For that case we have no other option that
471 * copying the data. Tough luck.
472 * - Destination page already exists in the address space, but there
473 * are no users of it. Make sure it's uptodate, then drop it. Fall
474 * through to last case.
475 * - Destination page does not exist, we can add the pipe page to
476 * the page cache and avoid the copy.
478 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
479 * sd->flags), we attempt to migrate pages from the pipe to the output
480 * file address space page cache. This is possible if no one else has
481 * the pipe page referenced outside of the pipe and page cache. If
482 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
483 * a new page in the output file page cache and fill/dirty that.
485 static int pipe_to_file(struct pipe_inode_info
*info
, struct pipe_buffer
*buf
,
486 struct splice_desc
*sd
)
488 struct file
*file
= sd
->file
;
489 struct address_space
*mapping
= file
->f_mapping
;
490 gfp_t gfp_mask
= mapping_gfp_mask(mapping
);
498 * make sure the data in this buffer is uptodate
500 src
= buf
->ops
->map(file
, info
, buf
);
504 index
= sd
->pos
>> PAGE_CACHE_SHIFT
;
505 offset
= sd
->pos
& ~PAGE_CACHE_MASK
;
508 * Reuse buf page, if SPLICE_F_MOVE is set.
510 if (sd
->flags
& SPLICE_F_MOVE
) {
512 * If steal succeeds, buf->page is now pruned from the vm
513 * side (LRU and page cache) and we can reuse it. The page
514 * will also be looked on successful return.
516 if (buf
->ops
->steal(info
, buf
))
520 if (add_to_page_cache(page
, mapping
, index
, gfp_mask
))
523 if (!(buf
->flags
& PIPE_BUF_FLAG_LRU
))
527 page
= find_lock_page(mapping
, index
);
530 page
= page_cache_alloc_cold(mapping
);
535 * This will also lock the page
537 ret
= add_to_page_cache_lru(page
, mapping
, index
,
544 * We get here with the page locked. If the page is also
545 * uptodate, we don't need to do more. If it isn't, we
546 * may need to bring it in if we are not going to overwrite
549 if (!PageUptodate(page
)) {
550 if (sd
->len
< PAGE_CACHE_SIZE
) {
551 ret
= mapping
->a_ops
->readpage(file
, page
);
557 if (!PageUptodate(page
)) {
559 * Page got invalidated, repeat.
561 if (!page
->mapping
) {
563 page_cache_release(page
);
570 SetPageUptodate(page
);
574 ret
= mapping
->a_ops
->prepare_write(file
, page
, 0, sd
->len
);
575 if (ret
== AOP_TRUNCATED_PAGE
) {
576 page_cache_release(page
);
581 if (!(buf
->flags
& PIPE_BUF_FLAG_STOLEN
)) {
582 char *dst
= kmap_atomic(page
, KM_USER0
);
584 memcpy(dst
+ offset
, src
+ buf
->offset
, sd
->len
);
585 flush_dcache_page(page
);
586 kunmap_atomic(dst
, KM_USER0
);
589 ret
= mapping
->a_ops
->commit_write(file
, page
, 0, sd
->len
);
590 if (ret
== AOP_TRUNCATED_PAGE
) {
591 page_cache_release(page
);
596 mark_page_accessed(page
);
597 balance_dirty_pages_ratelimited(mapping
);
599 if (!(buf
->flags
& PIPE_BUF_FLAG_STOLEN
))
600 page_cache_release(page
);
604 buf
->ops
->unmap(info
, buf
);
608 typedef int (splice_actor
)(struct pipe_inode_info
*, struct pipe_buffer
*,
609 struct splice_desc
*);
612 * Pipe input worker. Most of this logic works like a regular pipe, the
613 * key here is the 'actor' worker passed in that actually moves the data
614 * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
616 static ssize_t
move_from_pipe(struct pipe_inode_info
*pipe
, struct file
*out
,
617 loff_t
*ppos
, size_t len
, unsigned int flags
,
620 int ret
, do_wakeup
, err
;
621 struct splice_desc sd
;
632 mutex_lock(&pipe
->inode
->i_mutex
);
636 struct pipe_buffer
*buf
= pipe
->bufs
+ pipe
->curbuf
;
637 struct pipe_buf_operations
*ops
= buf
->ops
;
640 if (sd
.len
> sd
.total_len
)
641 sd
.len
= sd
.total_len
;
643 err
= actor(pipe
, buf
, &sd
);
645 if (!ret
&& err
!= -ENODATA
)
652 buf
->offset
+= sd
.len
;
657 ops
->release(pipe
, buf
);
658 pipe
->curbuf
= (pipe
->curbuf
+ 1) & (PIPE_BUFFERS
- 1);
665 sd
.total_len
-= sd
.len
;
674 if (!pipe
->waiting_writers
) {
679 if (flags
& SPLICE_F_NONBLOCK
) {
685 if (signal_pending(current
)) {
693 if (waitqueue_active(&pipe
->wait
))
694 wake_up_interruptible_sync(&pipe
->wait
);
695 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
703 mutex_unlock(&pipe
->inode
->i_mutex
);
707 if (waitqueue_active(&pipe
->wait
))
708 wake_up_interruptible(&pipe
->wait
);
709 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
716 * generic_file_splice_write - splice data from a pipe to a file
718 * @out: file to write to
719 * @len: number of bytes to splice
720 * @flags: splice modifier flags
722 * Will either move or copy pages (determined by @flags options) from
723 * the given pipe inode to the given file.
727 generic_file_splice_write(struct pipe_inode_info
*pipe
, struct file
*out
,
728 loff_t
*ppos
, size_t len
, unsigned int flags
)
730 struct address_space
*mapping
= out
->f_mapping
;
733 ret
= move_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_file
);
735 struct inode
*inode
= mapping
->host
;
740 * If file or inode is SYNC and we actually wrote some data,
743 if (unlikely((out
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
746 mutex_lock(&inode
->i_mutex
);
747 err
= generic_osync_inode(inode
, mapping
,
748 OSYNC_METADATA
|OSYNC_DATA
);
749 mutex_unlock(&inode
->i_mutex
);
759 EXPORT_SYMBOL(generic_file_splice_write
);
762 * generic_splice_sendpage - splice data from a pipe to a socket
764 * @out: socket to write to
765 * @len: number of bytes to splice
766 * @flags: splice modifier flags
768 * Will send @len bytes from the pipe to a network socket. No data copying
772 ssize_t
generic_splice_sendpage(struct pipe_inode_info
*pipe
, struct file
*out
,
773 loff_t
*ppos
, size_t len
, unsigned int flags
)
775 return move_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_sendpage
);
778 EXPORT_SYMBOL(generic_splice_sendpage
);
781 * Attempt to initiate a splice from pipe to file.
783 static long do_splice_from(struct pipe_inode_info
*pipe
, struct file
*out
,
784 loff_t
*ppos
, size_t len
, unsigned int flags
)
788 if (unlikely(!out
->f_op
|| !out
->f_op
->splice_write
))
791 if (unlikely(!(out
->f_mode
& FMODE_WRITE
)))
794 ret
= rw_verify_area(WRITE
, out
, ppos
, len
);
795 if (unlikely(ret
< 0))
798 return out
->f_op
->splice_write(pipe
, out
, ppos
, len
, flags
);
802 * Attempt to initiate a splice from a file to a pipe.
804 static long do_splice_to(struct file
*in
, loff_t
*ppos
,
805 struct pipe_inode_info
*pipe
, size_t len
,
811 if (unlikely(!in
->f_op
|| !in
->f_op
->splice_read
))
814 if (unlikely(!(in
->f_mode
& FMODE_READ
)))
817 ret
= rw_verify_area(READ
, in
, ppos
, len
);
818 if (unlikely(ret
< 0))
821 isize
= i_size_read(in
->f_mapping
->host
);
822 if (unlikely(*ppos
>= isize
))
825 left
= isize
- *ppos
;
826 if (unlikely(left
< len
))
829 return in
->f_op
->splice_read(in
, ppos
, pipe
, len
, flags
);
832 long do_splice_direct(struct file
*in
, loff_t
*ppos
, struct file
*out
,
833 size_t len
, unsigned int flags
)
835 struct pipe_inode_info
*pipe
;
842 * We require the input being a regular file, as we don't want to
843 * randomly drop data for eg socket -> socket splicing. Use the
844 * piped splicing for that!
846 i_mode
= in
->f_dentry
->d_inode
->i_mode
;
847 if (unlikely(!S_ISREG(i_mode
) && !S_ISBLK(i_mode
)))
851 * neither in nor out is a pipe, setup an internal pipe attached to
852 * 'out' and transfer the wanted data from 'in' to 'out' through that
854 pipe
= current
->splice_pipe
;
855 if (unlikely(!pipe
)) {
856 pipe
= alloc_pipe_info(NULL
);
861 * We don't have an immediate reader, but we'll read the stuff
862 * out of the pipe right after the move_to_pipe(). So set
863 * PIPE_READERS appropriately.
867 current
->splice_pipe
= pipe
;
878 size_t read_len
, max_read_len
;
881 * Do at most PIPE_BUFFERS pages worth of transfer:
883 max_read_len
= min(len
, (size_t)(PIPE_BUFFERS
*PAGE_SIZE
));
885 ret
= do_splice_to(in
, ppos
, pipe
, max_read_len
, flags
);
886 if (unlikely(ret
< 0))
892 * NOTE: nonblocking mode only applies to the input. We
893 * must not do the output in nonblocking mode as then we
894 * could get stuck data in the internal pipe:
896 ret
= do_splice_from(pipe
, out
, &out_off
, read_len
,
897 flags
& ~SPLICE_F_NONBLOCK
);
898 if (unlikely(ret
< 0))
905 * In nonblocking mode, if we got back a short read then
906 * that was due to either an IO error or due to the
907 * pagecache entry not being there. In the IO error case
908 * the _next_ splice attempt will produce a clean IO error
909 * return value (not a short read), so in both cases it's
910 * correct to break out of the loop here:
912 if ((flags
& SPLICE_F_NONBLOCK
) && (read_len
< max_read_len
))
916 pipe
->nrbufs
= pipe
->curbuf
= 0;
922 * If we did an incomplete transfer we must release
923 * the pipe buffers in question:
925 for (i
= 0; i
< PIPE_BUFFERS
; i
++) {
926 struct pipe_buffer
*buf
= pipe
->bufs
+ i
;
929 buf
->ops
->release(pipe
, buf
);
933 pipe
->nrbufs
= pipe
->curbuf
= 0;
936 * If we transferred some data, return the number of bytes:
944 EXPORT_SYMBOL(do_splice_direct
);
947 * Determine where to splice to/from.
949 static long do_splice(struct file
*in
, loff_t __user
*off_in
,
950 struct file
*out
, loff_t __user
*off_out
,
951 size_t len
, unsigned int flags
)
953 struct pipe_inode_info
*pipe
;
957 pipe
= in
->f_dentry
->d_inode
->i_pipe
;
962 if (out
->f_op
->llseek
== no_llseek
)
964 if (copy_from_user(&offset
, off_out
, sizeof(loff_t
)))
970 ret
= do_splice_from(pipe
, out
, off
, len
, flags
);
972 if (off_out
&& copy_to_user(off_out
, off
, sizeof(loff_t
)))
978 pipe
= out
->f_dentry
->d_inode
->i_pipe
;
983 if (in
->f_op
->llseek
== no_llseek
)
985 if (copy_from_user(&offset
, off_in
, sizeof(loff_t
)))
991 ret
= do_splice_to(in
, off
, pipe
, len
, flags
);
993 if (off_in
&& copy_to_user(off_in
, off
, sizeof(loff_t
)))
1002 asmlinkage
long sys_splice(int fd_in
, loff_t __user
*off_in
,
1003 int fd_out
, loff_t __user
*off_out
,
1004 size_t len
, unsigned int flags
)
1007 struct file
*in
, *out
;
1008 int fput_in
, fput_out
;
1014 in
= fget_light(fd_in
, &fput_in
);
1016 if (in
->f_mode
& FMODE_READ
) {
1017 out
= fget_light(fd_out
, &fput_out
);
1019 if (out
->f_mode
& FMODE_WRITE
)
1020 error
= do_splice(in
, off_in
,
1023 fput_light(out
, fput_out
);
1027 fput_light(in
, fput_in
);
1034 * Link contents of ipipe to opipe.
1036 static int link_pipe(struct pipe_inode_info
*ipipe
,
1037 struct pipe_inode_info
*opipe
,
1038 size_t len
, unsigned int flags
)
1040 struct pipe_buffer
*ibuf
, *obuf
;
1041 int ret
, do_wakeup
, i
, ipipe_first
;
1043 ret
= do_wakeup
= ipipe_first
= 0;
1046 * Potential ABBA deadlock, work around it by ordering lock
1047 * grabbing by inode address. Otherwise two different processes
1048 * could deadlock (one doing tee from A -> B, the other from B -> A).
1050 if (ipipe
->inode
< opipe
->inode
) {
1052 mutex_lock(&ipipe
->inode
->i_mutex
);
1053 mutex_lock(&opipe
->inode
->i_mutex
);
1055 mutex_lock(&opipe
->inode
->i_mutex
);
1056 mutex_lock(&ipipe
->inode
->i_mutex
);
1060 if (!opipe
->readers
) {
1061 send_sig(SIGPIPE
, current
, 0);
1066 if (ipipe
->nrbufs
- i
) {
1067 ibuf
= ipipe
->bufs
+ ((ipipe
->curbuf
+ i
) & (PIPE_BUFFERS
- 1));
1070 * If we have room, fill this buffer
1072 if (opipe
->nrbufs
< PIPE_BUFFERS
) {
1073 int nbuf
= (opipe
->curbuf
+ opipe
->nrbufs
) & (PIPE_BUFFERS
- 1);
1076 * Get a reference to this pipe buffer,
1077 * so we can copy the contents over.
1079 ibuf
->ops
->get(ipipe
, ibuf
);
1081 obuf
= opipe
->bufs
+ nbuf
;
1084 if (obuf
->len
> len
)
1094 if (opipe
->nrbufs
< PIPE_BUFFERS
)
1099 * We have input available, but no output room.
1100 * If we already copied data, return that. If we
1101 * need to drop the opipe lock, it must be ordered
1102 * last to avoid deadlocks.
1104 if ((flags
& SPLICE_F_NONBLOCK
) || !ipipe_first
) {
1109 if (signal_pending(current
)) {
1116 if (waitqueue_active(&opipe
->wait
))
1117 wake_up_interruptible(&opipe
->wait
);
1118 kill_fasync(&opipe
->fasync_readers
, SIGIO
, POLL_IN
);
1122 opipe
->waiting_writers
++;
1124 opipe
->waiting_writers
--;
1129 * No input buffers, do the usual checks for available
1130 * writers and blocking and wait if necessary
1132 if (!ipipe
->writers
)
1134 if (!ipipe
->waiting_writers
) {
1139 * pipe_wait() drops the ipipe mutex. To avoid deadlocks
1140 * with another process, we can only safely do that if
1141 * the ipipe lock is ordered last.
1143 if ((flags
& SPLICE_F_NONBLOCK
) || ipipe_first
) {
1148 if (signal_pending(current
)) {
1154 if (waitqueue_active(&ipipe
->wait
))
1155 wake_up_interruptible_sync(&ipipe
->wait
);
1156 kill_fasync(&ipipe
->fasync_writers
, SIGIO
, POLL_OUT
);
1161 mutex_unlock(&ipipe
->inode
->i_mutex
);
1162 mutex_unlock(&opipe
->inode
->i_mutex
);
1166 if (waitqueue_active(&opipe
->wait
))
1167 wake_up_interruptible(&opipe
->wait
);
1168 kill_fasync(&opipe
->fasync_readers
, SIGIO
, POLL_IN
);
1175 * This is a tee(1) implementation that works on pipes. It doesn't copy
1176 * any data, it simply references the 'in' pages on the 'out' pipe.
1177 * The 'flags' used are the SPLICE_F_* variants, currently the only
1178 * applicable one is SPLICE_F_NONBLOCK.
1180 static long do_tee(struct file
*in
, struct file
*out
, size_t len
,
1183 struct pipe_inode_info
*ipipe
= in
->f_dentry
->d_inode
->i_pipe
;
1184 struct pipe_inode_info
*opipe
= out
->f_dentry
->d_inode
->i_pipe
;
1187 * Link ipipe to the two output pipes, consuming as we go along.
1190 return link_pipe(ipipe
, opipe
, len
, flags
);
1195 asmlinkage
long sys_tee(int fdin
, int fdout
, size_t len
, unsigned int flags
)
1204 in
= fget_light(fdin
, &fput_in
);
1206 if (in
->f_mode
& FMODE_READ
) {
1208 struct file
*out
= fget_light(fdout
, &fput_out
);
1211 if (out
->f_mode
& FMODE_WRITE
)
1212 error
= do_tee(in
, out
, len
, flags
);
1213 fput_light(out
, fput_out
);
1216 fput_light(in
, fput_in
);