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>
30 #include <linux/uio.h>
38 * Passed to splice_to_pipe
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 */
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.
54 static int page_cache_pipe_buf_steal(struct pipe_inode_info
*info
,
55 struct pipe_buffer
*buf
)
57 struct page
*page
= buf
->page
;
58 struct address_space
*mapping
= page_mapping(page
);
62 WARN_ON(!PageUptodate(page
));
65 * At least for ext2 with nobh option, we need to wait on writeback
66 * completing on this page, since we'll remove it from the pagecache.
67 * Otherwise truncate wont wait on the page, allowing the disk
68 * blocks to be reused by someone else before we actually wrote our
69 * data to them. fs corruption ensues.
71 wait_on_page_writeback(page
);
73 if (PagePrivate(page
))
74 try_to_release_page(page
, mapping_gfp_mask(mapping
));
76 if (!remove_mapping(mapping
, page
)) {
81 buf
->flags
|= PIPE_BUF_FLAG_STOLEN
| PIPE_BUF_FLAG_LRU
;
85 static void page_cache_pipe_buf_release(struct pipe_inode_info
*info
,
86 struct pipe_buffer
*buf
)
88 page_cache_release(buf
->page
);
90 buf
->flags
&= ~(PIPE_BUF_FLAG_STOLEN
| PIPE_BUF_FLAG_LRU
);
93 static void *page_cache_pipe_buf_map(struct file
*file
,
94 struct pipe_inode_info
*info
,
95 struct pipe_buffer
*buf
)
97 struct page
*page
= buf
->page
;
100 if (!PageUptodate(page
)) {
104 * Page got truncated/unhashed. This will cause a 0-byte
105 * splice, if this is the first page.
107 if (!page
->mapping
) {
113 * Uh oh, read-error from disk.
115 if (!PageUptodate(page
)) {
121 * Page is ok afterall, fall through to mapping.
132 static void page_cache_pipe_buf_unmap(struct pipe_inode_info
*info
,
133 struct pipe_buffer
*buf
)
138 static void *user_page_pipe_buf_map(struct file
*file
,
139 struct pipe_inode_info
*pipe
,
140 struct pipe_buffer
*buf
)
142 return kmap(buf
->page
);
145 static void user_page_pipe_buf_unmap(struct pipe_inode_info
*pipe
,
146 struct pipe_buffer
*buf
)
151 static void page_cache_pipe_buf_get(struct pipe_inode_info
*info
,
152 struct pipe_buffer
*buf
)
154 page_cache_get(buf
->page
);
157 static struct pipe_buf_operations page_cache_pipe_buf_ops
= {
159 .map
= page_cache_pipe_buf_map
,
160 .unmap
= page_cache_pipe_buf_unmap
,
161 .release
= page_cache_pipe_buf_release
,
162 .steal
= page_cache_pipe_buf_steal
,
163 .get
= page_cache_pipe_buf_get
,
166 static int user_page_pipe_buf_steal(struct pipe_inode_info
*pipe
,
167 struct pipe_buffer
*buf
)
172 static struct pipe_buf_operations user_page_pipe_buf_ops
= {
174 .map
= user_page_pipe_buf_map
,
175 .unmap
= user_page_pipe_buf_unmap
,
176 .release
= page_cache_pipe_buf_release
,
177 .steal
= user_page_pipe_buf_steal
,
178 .get
= page_cache_pipe_buf_get
,
182 * Pipe output worker. This sets up our pipe format with the page cache
183 * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
185 static ssize_t
splice_to_pipe(struct pipe_inode_info
*pipe
,
186 struct splice_pipe_desc
*spd
)
188 int ret
, do_wakeup
, page_nr
;
195 mutex_lock(&pipe
->inode
->i_mutex
);
198 if (!pipe
->readers
) {
199 send_sig(SIGPIPE
, current
, 0);
205 if (pipe
->nrbufs
< PIPE_BUFFERS
) {
206 int newbuf
= (pipe
->curbuf
+ pipe
->nrbufs
) & (PIPE_BUFFERS
- 1);
207 struct pipe_buffer
*buf
= pipe
->bufs
+ newbuf
;
209 buf
->page
= spd
->pages
[page_nr
];
210 buf
->offset
= spd
->partial
[page_nr
].offset
;
211 buf
->len
= spd
->partial
[page_nr
].len
;
220 if (!--spd
->nr_pages
)
222 if (pipe
->nrbufs
< PIPE_BUFFERS
)
228 if (spd
->flags
& SPLICE_F_NONBLOCK
) {
234 if (signal_pending(current
)) {
242 if (waitqueue_active(&pipe
->wait
))
243 wake_up_interruptible_sync(&pipe
->wait
);
244 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
248 pipe
->waiting_writers
++;
250 pipe
->waiting_writers
--;
254 mutex_unlock(&pipe
->inode
->i_mutex
);
258 if (waitqueue_active(&pipe
->wait
))
259 wake_up_interruptible(&pipe
->wait
);
260 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
263 while (page_nr
< spd
->nr_pages
)
264 page_cache_release(spd
->pages
[page_nr
++]);
270 __generic_file_splice_read(struct file
*in
, loff_t
*ppos
,
271 struct pipe_inode_info
*pipe
, size_t len
,
274 struct address_space
*mapping
= in
->f_mapping
;
275 unsigned int loff
, nr_pages
;
276 struct page
*pages
[PIPE_BUFFERS
];
277 struct partial_page partial
[PIPE_BUFFERS
];
279 pgoff_t index
, end_index
;
283 struct splice_pipe_desc spd
= {
287 .ops
= &page_cache_pipe_buf_ops
,
290 index
= *ppos
>> PAGE_CACHE_SHIFT
;
291 loff
= *ppos
& ~PAGE_CACHE_MASK
;
292 nr_pages
= (len
+ loff
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
294 if (nr_pages
> PIPE_BUFFERS
)
295 nr_pages
= PIPE_BUFFERS
;
298 * Initiate read-ahead on this page range. however, don't call into
299 * read-ahead if this is a non-zero offset (we are likely doing small
300 * chunk splice and the page is already there) for a single page.
302 if (!loff
|| nr_pages
> 1)
303 page_cache_readahead(mapping
, &in
->f_ra
, in
, index
, nr_pages
);
306 * Now fill in the holes:
312 * Lookup the (hopefully) full range of pages we need.
314 spd
.nr_pages
= find_get_pages_contig(mapping
, index
, nr_pages
, pages
);
317 * If find_get_pages_contig() returned fewer pages than we needed,
320 index
+= spd
.nr_pages
;
321 while (spd
.nr_pages
< nr_pages
) {
323 * Page could be there, find_get_pages_contig() breaks on
326 page
= find_get_page(mapping
, index
);
329 * page didn't exist, allocate one.
331 page
= page_cache_alloc_cold(mapping
);
335 error
= add_to_page_cache_lru(page
, mapping
, index
,
336 mapping_gfp_mask(mapping
));
337 if (unlikely(error
)) {
338 page_cache_release(page
);
342 * add_to_page_cache() locks the page, unlock it
343 * to avoid convoluting the logic below even more.
348 pages
[spd
.nr_pages
++] = page
;
353 * Now loop over the map and see if we need to start IO on any
354 * pages, fill in the partial map, etc.
356 index
= *ppos
>> PAGE_CACHE_SHIFT
;
357 nr_pages
= spd
.nr_pages
;
359 for (page_nr
= 0; page_nr
< nr_pages
; page_nr
++) {
360 unsigned int this_len
;
366 * this_len is the max we'll use from this page
368 this_len
= min_t(unsigned long, len
, PAGE_CACHE_SIZE
- loff
);
369 page
= pages
[page_nr
];
372 * If the page isn't uptodate, we may need to start io on it
374 if (!PageUptodate(page
)) {
376 * If in nonblock mode then dont block on waiting
377 * for an in-flight io page
379 if (flags
& SPLICE_F_NONBLOCK
)
385 * page was truncated, stop here. if this isn't the
386 * first page, we'll just complete what we already
389 if (!page
->mapping
) {
394 * page was already under io and is now done, great
396 if (PageUptodate(page
)) {
402 * need to read in the page
404 error
= mapping
->a_ops
->readpage(in
, page
);
405 if (unlikely(error
)) {
407 * We really should re-lookup the page here,
408 * but it complicates things a lot. Instead
409 * lets just do what we already stored, and
410 * we'll get it the next time we are called.
412 if (error
== AOP_TRUNCATED_PAGE
)
419 * i_size must be checked after ->readpage().
421 isize
= i_size_read(mapping
->host
);
422 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
423 if (unlikely(!isize
|| index
> end_index
))
427 * if this is the last page, see if we need to shrink
428 * the length and stop
430 if (end_index
== index
) {
431 loff
= PAGE_CACHE_SIZE
- (isize
& ~PAGE_CACHE_MASK
);
432 if (total_len
+ loff
> isize
)
435 * force quit after adding this page
438 this_len
= min(this_len
, loff
);
443 partial
[page_nr
].offset
= loff
;
444 partial
[page_nr
].len
= this_len
;
446 total_len
+= this_len
;
453 * Release any pages at the end, if we quit early. 'i' is how far
454 * we got, 'nr_pages' is how many pages are in the map.
456 while (page_nr
< nr_pages
)
457 page_cache_release(pages
[page_nr
++]);
460 return splice_to_pipe(pipe
, &spd
);
466 * generic_file_splice_read - splice data from file to a pipe
467 * @in: file to splice from
468 * @pipe: pipe to splice to
469 * @len: number of bytes to splice
470 * @flags: splice modifier flags
472 * Will read pages from given file and fill them into a pipe.
474 ssize_t
generic_file_splice_read(struct file
*in
, loff_t
*ppos
,
475 struct pipe_inode_info
*pipe
, size_t len
,
485 ret
= __generic_file_splice_read(in
, ppos
, pipe
, len
, flags
);
492 if (flags
& SPLICE_F_NONBLOCK
) {
509 EXPORT_SYMBOL(generic_file_splice_read
);
512 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
513 * using sendpage(). Return the number of bytes sent.
515 static int pipe_to_sendpage(struct pipe_inode_info
*info
,
516 struct pipe_buffer
*buf
, struct splice_desc
*sd
)
518 struct file
*file
= sd
->file
;
519 loff_t pos
= sd
->pos
;
525 * Sub-optimal, but we are limited by the pipe ->map. We don't
526 * need a kmap'ed buffer here, we just want to make sure we
527 * have the page pinned if the pipe page originates from the
530 ptr
= buf
->ops
->map(file
, info
, buf
);
534 more
= (sd
->flags
& SPLICE_F_MORE
) || sd
->len
< sd
->total_len
;
536 ret
= file
->f_op
->sendpage(file
, buf
->page
, buf
->offset
, sd
->len
,
539 buf
->ops
->unmap(info
, buf
);
544 * This is a little more tricky than the file -> pipe splicing. There are
545 * basically three cases:
547 * - Destination page already exists in the address space and there
548 * are users of it. For that case we have no other option that
549 * copying the data. Tough luck.
550 * - Destination page already exists in the address space, but there
551 * are no users of it. Make sure it's uptodate, then drop it. Fall
552 * through to last case.
553 * - Destination page does not exist, we can add the pipe page to
554 * the page cache and avoid the copy.
556 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
557 * sd->flags), we attempt to migrate pages from the pipe to the output
558 * file address space page cache. This is possible if no one else has
559 * the pipe page referenced outside of the pipe and page cache. If
560 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
561 * a new page in the output file page cache and fill/dirty that.
563 static int pipe_to_file(struct pipe_inode_info
*info
, struct pipe_buffer
*buf
,
564 struct splice_desc
*sd
)
566 struct file
*file
= sd
->file
;
567 struct address_space
*mapping
= file
->f_mapping
;
568 gfp_t gfp_mask
= mapping_gfp_mask(mapping
);
569 unsigned int offset
, this_len
;
576 * make sure the data in this buffer is uptodate
578 src
= buf
->ops
->map(file
, info
, buf
);
582 index
= sd
->pos
>> PAGE_CACHE_SHIFT
;
583 offset
= sd
->pos
& ~PAGE_CACHE_MASK
;
586 if (this_len
+ offset
> PAGE_CACHE_SIZE
)
587 this_len
= PAGE_CACHE_SIZE
- offset
;
590 * Reuse buf page, if SPLICE_F_MOVE is set.
592 if (sd
->flags
& SPLICE_F_MOVE
) {
594 * If steal succeeds, buf->page is now pruned from the vm
595 * side (LRU and page cache) and we can reuse it. The page
596 * will also be looked on successful return.
598 if (buf
->ops
->steal(info
, buf
))
602 if (add_to_page_cache(page
, mapping
, index
, gfp_mask
))
605 if (!(buf
->flags
& PIPE_BUF_FLAG_LRU
))
609 page
= find_lock_page(mapping
, index
);
612 page
= page_cache_alloc_cold(mapping
);
617 * This will also lock the page
619 ret
= add_to_page_cache_lru(page
, mapping
, index
,
626 * We get here with the page locked. If the page is also
627 * uptodate, we don't need to do more. If it isn't, we
628 * may need to bring it in if we are not going to overwrite
631 if (!PageUptodate(page
)) {
632 if (this_len
< PAGE_CACHE_SIZE
) {
633 ret
= mapping
->a_ops
->readpage(file
, page
);
639 if (!PageUptodate(page
)) {
641 * Page got invalidated, repeat.
643 if (!page
->mapping
) {
645 page_cache_release(page
);
652 SetPageUptodate(page
);
656 ret
= mapping
->a_ops
->prepare_write(file
, page
, offset
, offset
+this_len
);
657 if (ret
== AOP_TRUNCATED_PAGE
) {
658 page_cache_release(page
);
663 if (!(buf
->flags
& PIPE_BUF_FLAG_STOLEN
)) {
664 char *dst
= kmap_atomic(page
, KM_USER0
);
666 memcpy(dst
+ offset
, src
+ buf
->offset
, this_len
);
667 flush_dcache_page(page
);
668 kunmap_atomic(dst
, KM_USER0
);
671 ret
= mapping
->a_ops
->commit_write(file
, page
, offset
, offset
+this_len
);
672 if (ret
== AOP_TRUNCATED_PAGE
) {
673 page_cache_release(page
);
679 * Return the number of bytes written.
682 mark_page_accessed(page
);
683 balance_dirty_pages_ratelimited(mapping
);
685 if (!(buf
->flags
& PIPE_BUF_FLAG_STOLEN
))
686 page_cache_release(page
);
690 buf
->ops
->unmap(info
, buf
);
695 * Pipe input worker. Most of this logic works like a regular pipe, the
696 * key here is the 'actor' worker passed in that actually moves the data
697 * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
699 ssize_t
splice_from_pipe(struct pipe_inode_info
*pipe
, struct file
*out
,
700 loff_t
*ppos
, size_t len
, unsigned int flags
,
703 int ret
, do_wakeup
, err
;
704 struct splice_desc sd
;
715 mutex_lock(&pipe
->inode
->i_mutex
);
719 struct pipe_buffer
*buf
= pipe
->bufs
+ pipe
->curbuf
;
720 struct pipe_buf_operations
*ops
= buf
->ops
;
723 if (sd
.len
> sd
.total_len
)
724 sd
.len
= sd
.total_len
;
726 err
= actor(pipe
, buf
, &sd
);
728 if (!ret
&& err
!= -ENODATA
)
746 ops
->release(pipe
, buf
);
747 pipe
->curbuf
= (pipe
->curbuf
+ 1) & (PIPE_BUFFERS
- 1);
761 if (!pipe
->waiting_writers
) {
766 if (flags
& SPLICE_F_NONBLOCK
) {
772 if (signal_pending(current
)) {
780 if (waitqueue_active(&pipe
->wait
))
781 wake_up_interruptible_sync(&pipe
->wait
);
782 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
790 mutex_unlock(&pipe
->inode
->i_mutex
);
794 if (waitqueue_active(&pipe
->wait
))
795 wake_up_interruptible(&pipe
->wait
);
796 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
803 * generic_file_splice_write - splice data from a pipe to a file
805 * @out: file to write to
806 * @len: number of bytes to splice
807 * @flags: splice modifier flags
809 * Will either move or copy pages (determined by @flags options) from
810 * the given pipe inode to the given file.
814 generic_file_splice_write(struct pipe_inode_info
*pipe
, struct file
*out
,
815 loff_t
*ppos
, size_t len
, unsigned int flags
)
817 struct address_space
*mapping
= out
->f_mapping
;
820 ret
= splice_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_file
);
822 struct inode
*inode
= mapping
->host
;
827 * If file or inode is SYNC and we actually wrote some data,
830 if (unlikely((out
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
833 mutex_lock(&inode
->i_mutex
);
834 err
= generic_osync_inode(inode
, mapping
,
835 OSYNC_METADATA
|OSYNC_DATA
);
836 mutex_unlock(&inode
->i_mutex
);
846 EXPORT_SYMBOL(generic_file_splice_write
);
849 * generic_splice_sendpage - splice data from a pipe to a socket
851 * @out: socket to write to
852 * @len: number of bytes to splice
853 * @flags: splice modifier flags
855 * Will send @len bytes from the pipe to a network socket. No data copying
859 ssize_t
generic_splice_sendpage(struct pipe_inode_info
*pipe
, struct file
*out
,
860 loff_t
*ppos
, size_t len
, unsigned int flags
)
862 return splice_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_sendpage
);
865 EXPORT_SYMBOL(generic_splice_sendpage
);
868 * Attempt to initiate a splice from pipe to file.
870 static long do_splice_from(struct pipe_inode_info
*pipe
, struct file
*out
,
871 loff_t
*ppos
, size_t len
, unsigned int flags
)
875 if (unlikely(!out
->f_op
|| !out
->f_op
->splice_write
))
878 if (unlikely(!(out
->f_mode
& FMODE_WRITE
)))
881 ret
= rw_verify_area(WRITE
, out
, ppos
, len
);
882 if (unlikely(ret
< 0))
885 return out
->f_op
->splice_write(pipe
, out
, ppos
, len
, flags
);
889 * Attempt to initiate a splice from a file to a pipe.
891 static long do_splice_to(struct file
*in
, loff_t
*ppos
,
892 struct pipe_inode_info
*pipe
, size_t len
,
898 if (unlikely(!in
->f_op
|| !in
->f_op
->splice_read
))
901 if (unlikely(!(in
->f_mode
& FMODE_READ
)))
904 ret
= rw_verify_area(READ
, in
, ppos
, len
);
905 if (unlikely(ret
< 0))
908 isize
= i_size_read(in
->f_mapping
->host
);
909 if (unlikely(*ppos
>= isize
))
912 left
= isize
- *ppos
;
913 if (unlikely(left
< len
))
916 return in
->f_op
->splice_read(in
, ppos
, pipe
, len
, flags
);
919 long do_splice_direct(struct file
*in
, loff_t
*ppos
, struct file
*out
,
920 size_t len
, unsigned int flags
)
922 struct pipe_inode_info
*pipe
;
929 * We require the input being a regular file, as we don't want to
930 * randomly drop data for eg socket -> socket splicing. Use the
931 * piped splicing for that!
933 i_mode
= in
->f_dentry
->d_inode
->i_mode
;
934 if (unlikely(!S_ISREG(i_mode
) && !S_ISBLK(i_mode
)))
938 * neither in nor out is a pipe, setup an internal pipe attached to
939 * 'out' and transfer the wanted data from 'in' to 'out' through that
941 pipe
= current
->splice_pipe
;
942 if (unlikely(!pipe
)) {
943 pipe
= alloc_pipe_info(NULL
);
948 * We don't have an immediate reader, but we'll read the stuff
949 * out of the pipe right after the splice_to_pipe(). So set
950 * PIPE_READERS appropriately.
954 current
->splice_pipe
= pipe
;
965 size_t read_len
, max_read_len
;
968 * Do at most PIPE_BUFFERS pages worth of transfer:
970 max_read_len
= min(len
, (size_t)(PIPE_BUFFERS
*PAGE_SIZE
));
972 ret
= do_splice_to(in
, ppos
, pipe
, max_read_len
, flags
);
973 if (unlikely(ret
< 0))
979 * NOTE: nonblocking mode only applies to the input. We
980 * must not do the output in nonblocking mode as then we
981 * could get stuck data in the internal pipe:
983 ret
= do_splice_from(pipe
, out
, &out_off
, read_len
,
984 flags
& ~SPLICE_F_NONBLOCK
);
985 if (unlikely(ret
< 0))
992 * In nonblocking mode, if we got back a short read then
993 * that was due to either an IO error or due to the
994 * pagecache entry not being there. In the IO error case
995 * the _next_ splice attempt will produce a clean IO error
996 * return value (not a short read), so in both cases it's
997 * correct to break out of the loop here:
999 if ((flags
& SPLICE_F_NONBLOCK
) && (read_len
< max_read_len
))
1003 pipe
->nrbufs
= pipe
->curbuf
= 0;
1009 * If we did an incomplete transfer we must release
1010 * the pipe buffers in question:
1012 for (i
= 0; i
< PIPE_BUFFERS
; i
++) {
1013 struct pipe_buffer
*buf
= pipe
->bufs
+ i
;
1016 buf
->ops
->release(pipe
, buf
);
1020 pipe
->nrbufs
= pipe
->curbuf
= 0;
1023 * If we transferred some data, return the number of bytes:
1031 EXPORT_SYMBOL(do_splice_direct
);
1034 * Determine where to splice to/from.
1036 static long do_splice(struct file
*in
, loff_t __user
*off_in
,
1037 struct file
*out
, loff_t __user
*off_out
,
1038 size_t len
, unsigned int flags
)
1040 struct pipe_inode_info
*pipe
;
1041 loff_t offset
, *off
;
1044 pipe
= in
->f_dentry
->d_inode
->i_pipe
;
1049 if (out
->f_op
->llseek
== no_llseek
)
1051 if (copy_from_user(&offset
, off_out
, sizeof(loff_t
)))
1057 ret
= do_splice_from(pipe
, out
, off
, len
, flags
);
1059 if (off_out
&& copy_to_user(off_out
, off
, sizeof(loff_t
)))
1065 pipe
= out
->f_dentry
->d_inode
->i_pipe
;
1070 if (in
->f_op
->llseek
== no_llseek
)
1072 if (copy_from_user(&offset
, off_in
, sizeof(loff_t
)))
1078 ret
= do_splice_to(in
, off
, pipe
, len
, flags
);
1080 if (off_in
&& copy_to_user(off_in
, off
, sizeof(loff_t
)))
1090 * Map an iov into an array of pages and offset/length tupples. With the
1091 * partial_page structure, we can map several non-contiguous ranges into
1092 * our ones pages[] map instead of splitting that operation into pieces.
1093 * Could easily be exported as a generic helper for other users, in which
1094 * case one would probably want to add a 'max_nr_pages' parameter as well.
1096 static int get_iovec_page_array(const struct iovec __user
*iov
,
1097 unsigned int nr_vecs
, struct page
**pages
,
1098 struct partial_page
*partial
)
1100 int buffers
= 0, error
= 0;
1103 * It's ok to take the mmap_sem for reading, even
1104 * across a "get_user()".
1106 down_read(¤t
->mm
->mmap_sem
);
1109 unsigned long off
, npages
;
1115 * Get user address base and length for this iovec.
1117 error
= get_user(base
, &iov
->iov_base
);
1118 if (unlikely(error
))
1120 error
= get_user(len
, &iov
->iov_len
);
1121 if (unlikely(error
))
1125 * Sanity check this iovec. 0 read succeeds.
1130 if (unlikely(!base
))
1134 * Get this base offset and number of pages, then map
1135 * in the user pages.
1137 off
= (unsigned long) base
& ~PAGE_MASK
;
1138 npages
= (off
+ len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1139 if (npages
> PIPE_BUFFERS
- buffers
)
1140 npages
= PIPE_BUFFERS
- buffers
;
1142 error
= get_user_pages(current
, current
->mm
,
1143 (unsigned long) base
, npages
, 0, 0,
1144 &pages
[buffers
], NULL
);
1146 if (unlikely(error
<= 0))
1150 * Fill this contiguous range into the partial page map.
1152 for (i
= 0; i
< error
; i
++) {
1153 const int plen
= min_t(size_t, len
, PAGE_SIZE
) - off
;
1155 partial
[buffers
].offset
= off
;
1156 partial
[buffers
].len
= plen
;
1164 * We didn't complete this iov, stop here since it probably
1165 * means we have to move some of this into a pipe to
1166 * be able to continue.
1172 * Don't continue if we mapped fewer pages than we asked for,
1173 * or if we mapped the max number of pages that we have
1176 if (error
< npages
|| buffers
== PIPE_BUFFERS
)
1183 up_read(¤t
->mm
->mmap_sem
);
1192 * vmsplice splices a user address range into a pipe. It can be thought of
1193 * as splice-from-memory, where the regular splice is splice-from-file (or
1194 * to file). In both cases the output is a pipe, naturally.
1196 * Note that vmsplice only supports splicing _from_ user memory to a pipe,
1197 * not the other way around. Splicing from user memory is a simple operation
1198 * that can be supported without any funky alignment restrictions or nasty
1199 * vm tricks. We simply map in the user memory and fill them into a pipe.
1200 * The reverse isn't quite as easy, though. There are two possible solutions
1203 * - memcpy() the data internally, at which point we might as well just
1204 * do a regular read() on the buffer anyway.
1205 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1206 * has restriction limitations on both ends of the pipe).
1208 * Alas, it isn't here.
1211 static long do_vmsplice(struct file
*file
, const struct iovec __user
*iov
,
1212 unsigned long nr_segs
, unsigned int flags
)
1214 struct pipe_inode_info
*pipe
= file
->f_dentry
->d_inode
->i_pipe
;
1215 struct page
*pages
[PIPE_BUFFERS
];
1216 struct partial_page partial
[PIPE_BUFFERS
];
1217 struct splice_pipe_desc spd
= {
1221 .ops
= &user_page_pipe_buf_ops
,
1224 if (unlikely(!pipe
))
1226 if (unlikely(nr_segs
> UIO_MAXIOV
))
1228 else if (unlikely(!nr_segs
))
1231 spd
.nr_pages
= get_iovec_page_array(iov
, nr_segs
, pages
, partial
);
1232 if (spd
.nr_pages
<= 0)
1233 return spd
.nr_pages
;
1235 return splice_to_pipe(pipe
, &spd
);
1238 asmlinkage
long sys_vmsplice(int fd
, const struct iovec __user
*iov
,
1239 unsigned long nr_segs
, unsigned int flags
)
1246 file
= fget_light(fd
, &fput
);
1248 if (file
->f_mode
& FMODE_WRITE
)
1249 error
= do_vmsplice(file
, iov
, nr_segs
, flags
);
1251 fput_light(file
, fput
);
1257 asmlinkage
long sys_splice(int fd_in
, loff_t __user
*off_in
,
1258 int fd_out
, loff_t __user
*off_out
,
1259 size_t len
, unsigned int flags
)
1262 struct file
*in
, *out
;
1263 int fput_in
, fput_out
;
1269 in
= fget_light(fd_in
, &fput_in
);
1271 if (in
->f_mode
& FMODE_READ
) {
1272 out
= fget_light(fd_out
, &fput_out
);
1274 if (out
->f_mode
& FMODE_WRITE
)
1275 error
= do_splice(in
, off_in
,
1278 fput_light(out
, fput_out
);
1282 fput_light(in
, fput_in
);
1289 * Link contents of ipipe to opipe.
1291 static int link_pipe(struct pipe_inode_info
*ipipe
,
1292 struct pipe_inode_info
*opipe
,
1293 size_t len
, unsigned int flags
)
1295 struct pipe_buffer
*ibuf
, *obuf
;
1296 int ret
, do_wakeup
, i
, ipipe_first
;
1298 ret
= do_wakeup
= ipipe_first
= 0;
1301 * Potential ABBA deadlock, work around it by ordering lock
1302 * grabbing by inode address. Otherwise two different processes
1303 * could deadlock (one doing tee from A -> B, the other from B -> A).
1305 if (ipipe
->inode
< opipe
->inode
) {
1307 mutex_lock(&ipipe
->inode
->i_mutex
);
1308 mutex_lock(&opipe
->inode
->i_mutex
);
1310 mutex_lock(&opipe
->inode
->i_mutex
);
1311 mutex_lock(&ipipe
->inode
->i_mutex
);
1315 if (!opipe
->readers
) {
1316 send_sig(SIGPIPE
, current
, 0);
1321 if (ipipe
->nrbufs
- i
) {
1322 ibuf
= ipipe
->bufs
+ ((ipipe
->curbuf
+ i
) & (PIPE_BUFFERS
- 1));
1325 * If we have room, fill this buffer
1327 if (opipe
->nrbufs
< PIPE_BUFFERS
) {
1328 int nbuf
= (opipe
->curbuf
+ opipe
->nrbufs
) & (PIPE_BUFFERS
- 1);
1331 * Get a reference to this pipe buffer,
1332 * so we can copy the contents over.
1334 ibuf
->ops
->get(ipipe
, ibuf
);
1336 obuf
= opipe
->bufs
+ nbuf
;
1339 if (obuf
->len
> len
)
1349 if (opipe
->nrbufs
< PIPE_BUFFERS
)
1354 * We have input available, but no output room.
1355 * If we already copied data, return that. If we
1356 * need to drop the opipe lock, it must be ordered
1357 * last to avoid deadlocks.
1359 if ((flags
& SPLICE_F_NONBLOCK
) || !ipipe_first
) {
1364 if (signal_pending(current
)) {
1371 if (waitqueue_active(&opipe
->wait
))
1372 wake_up_interruptible(&opipe
->wait
);
1373 kill_fasync(&opipe
->fasync_readers
, SIGIO
, POLL_IN
);
1377 opipe
->waiting_writers
++;
1379 opipe
->waiting_writers
--;
1384 * No input buffers, do the usual checks for available
1385 * writers and blocking and wait if necessary
1387 if (!ipipe
->writers
)
1389 if (!ipipe
->waiting_writers
) {
1394 * pipe_wait() drops the ipipe mutex. To avoid deadlocks
1395 * with another process, we can only safely do that if
1396 * the ipipe lock is ordered last.
1398 if ((flags
& SPLICE_F_NONBLOCK
) || ipipe_first
) {
1403 if (signal_pending(current
)) {
1409 if (waitqueue_active(&ipipe
->wait
))
1410 wake_up_interruptible_sync(&ipipe
->wait
);
1411 kill_fasync(&ipipe
->fasync_writers
, SIGIO
, POLL_OUT
);
1416 mutex_unlock(&ipipe
->inode
->i_mutex
);
1417 mutex_unlock(&opipe
->inode
->i_mutex
);
1421 if (waitqueue_active(&opipe
->wait
))
1422 wake_up_interruptible(&opipe
->wait
);
1423 kill_fasync(&opipe
->fasync_readers
, SIGIO
, POLL_IN
);
1430 * This is a tee(1) implementation that works on pipes. It doesn't copy
1431 * any data, it simply references the 'in' pages on the 'out' pipe.
1432 * The 'flags' used are the SPLICE_F_* variants, currently the only
1433 * applicable one is SPLICE_F_NONBLOCK.
1435 static long do_tee(struct file
*in
, struct file
*out
, size_t len
,
1438 struct pipe_inode_info
*ipipe
= in
->f_dentry
->d_inode
->i_pipe
;
1439 struct pipe_inode_info
*opipe
= out
->f_dentry
->d_inode
->i_pipe
;
1442 * Link ipipe to the two output pipes, consuming as we go along.
1445 return link_pipe(ipipe
, opipe
, len
, flags
);
1450 asmlinkage
long sys_tee(int fdin
, int fdout
, size_t len
, unsigned int flags
)
1459 in
= fget_light(fdin
, &fput_in
);
1461 if (in
->f_mode
& FMODE_READ
) {
1463 struct file
*out
= fget_light(fdout
, &fput_out
);
1466 if (out
->f_mode
& FMODE_WRITE
)
1467 error
= do_tee(in
, out
, len
, flags
);
1468 fput_light(out
, fput_out
);
1471 fput_light(in
, fput_in
);