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1/*
2 * "splice": joining two ropes together by interweaving their strands.
3 *
4 * This is the "extended pipe" functionality, where a pipe is used as
5 * an arbitrary in-memory buffer. Think of a pipe as a small kernel
6 * buffer that you can use to transfer data from one end to the other.
7 *
8 * The traditional unix read/write is extended with a "splice()" operation
9 * that transfers data buffers to or from a pipe buffer.
10 *
11 * Named by Larry McVoy, original implementation from Linus, extended by
12 * Jens to support splicing to files, network, direct splicing, etc and
13 * fixing lots of bugs.
14 *
15 * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
16 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
17 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
18 *
19 */
20#include <linux/bvec.h>
21#include <linux/fs.h>
22#include <linux/file.h>
23#include <linux/pagemap.h>
24#include <linux/splice.h>
25#include <linux/memcontrol.h>
26#include <linux/mm_inline.h>
27#include <linux/swap.h>
28#include <linux/writeback.h>
29#include <linux/export.h>
30#include <linux/syscalls.h>
31#include <linux/uio.h>
32#include <linux/security.h>
33#include <linux/gfp.h>
34#include <linux/socket.h>
35#include <linux/compat.h>
36#include <linux/sched/signal.h>
37
38#include "internal.h"
39
40/*
41 * Attempt to steal a page from a pipe buffer. This should perhaps go into
42 * a vm helper function, it's already simplified quite a bit by the
43 * addition of remove_mapping(). If success is returned, the caller may
44 * attempt to reuse this page for another destination.
45 */
46static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
47 struct pipe_buffer *buf)
48{
49 struct page *page = buf->page;
50 struct address_space *mapping;
51
52 lock_page(page);
53
54 mapping = page_mapping(page);
55 if (mapping) {
56 WARN_ON(!PageUptodate(page));
57
58 /*
59 * At least for ext2 with nobh option, we need to wait on
60 * writeback completing on this page, since we'll remove it
61 * from the pagecache. Otherwise truncate wont wait on the
62 * page, allowing the disk blocks to be reused by someone else
63 * before we actually wrote our data to them. fs corruption
64 * ensues.
65 */
66 wait_on_page_writeback(page);
67
68 if (page_has_private(page) &&
69 !try_to_release_page(page, GFP_KERNEL))
70 goto out_unlock;
71
72 /*
73 * If we succeeded in removing the mapping, set LRU flag
74 * and return good.
75 */
76 if (remove_mapping(mapping, page)) {
77 buf->flags |= PIPE_BUF_FLAG_LRU;
78 return 0;
79 }
80 }
81
82 /*
83 * Raced with truncate or failed to remove page from current
84 * address space, unlock and return failure.
85 */
86out_unlock:
87 unlock_page(page);
88 return 1;
89}
90
91static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
92 struct pipe_buffer *buf)
93{
94 put_page(buf->page);
95 buf->flags &= ~PIPE_BUF_FLAG_LRU;
96}
97
98/*
99 * Check whether the contents of buf is OK to access. Since the content
100 * is a page cache page, IO may be in flight.
101 */
102static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
103 struct pipe_buffer *buf)
104{
105 struct page *page = buf->page;
106 int err;
107
108 if (!PageUptodate(page)) {
109 lock_page(page);
110
111 /*
112 * Page got truncated/unhashed. This will cause a 0-byte
113 * splice, if this is the first page.
114 */
115 if (!page->mapping) {
116 err = -ENODATA;
117 goto error;
118 }
119
120 /*
121 * Uh oh, read-error from disk.
122 */
123 if (!PageUptodate(page)) {
124 err = -EIO;
125 goto error;
126 }
127
128 /*
129 * Page is ok afterall, we are done.
130 */
131 unlock_page(page);
132 }
133
134 return 0;
135error:
136 unlock_page(page);
137 return err;
138}
139
140const struct pipe_buf_operations page_cache_pipe_buf_ops = {
141 .can_merge = 0,
142 .confirm = page_cache_pipe_buf_confirm,
143 .release = page_cache_pipe_buf_release,
144 .steal = page_cache_pipe_buf_steal,
145 .get = generic_pipe_buf_get,
146};
147
148static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
149 struct pipe_buffer *buf)
150{
151 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
152 return 1;
153
154 buf->flags |= PIPE_BUF_FLAG_LRU;
155 return generic_pipe_buf_steal(pipe, buf);
156}
157
158static const struct pipe_buf_operations user_page_pipe_buf_ops = {
159 .can_merge = 0,
160 .confirm = generic_pipe_buf_confirm,
161 .release = page_cache_pipe_buf_release,
162 .steal = user_page_pipe_buf_steal,
163 .get = generic_pipe_buf_get,
164};
165
166static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
167{
168 smp_mb();
169 if (waitqueue_active(&pipe->wait))
170 wake_up_interruptible(&pipe->wait);
171 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
172}
173
174/**
175 * splice_to_pipe - fill passed data into a pipe
176 * @pipe: pipe to fill
177 * @spd: data to fill
178 *
179 * Description:
180 * @spd contains a map of pages and len/offset tuples, along with
181 * the struct pipe_buf_operations associated with these pages. This
182 * function will link that data to the pipe.
183 *
184 */
185ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
186 struct splice_pipe_desc *spd)
187{
188 unsigned int spd_pages = spd->nr_pages;
189 int ret = 0, page_nr = 0;
190
191 if (!spd_pages)
192 return 0;
193
194 if (unlikely(!pipe->readers)) {
195 send_sig(SIGPIPE, current, 0);
196 ret = -EPIPE;
197 goto out;
198 }
199
200 while (pipe->nrbufs < pipe->buffers) {
201 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
202 struct pipe_buffer *buf = pipe->bufs + newbuf;
203
204 buf->page = spd->pages[page_nr];
205 buf->offset = spd->partial[page_nr].offset;
206 buf->len = spd->partial[page_nr].len;
207 buf->private = spd->partial[page_nr].private;
208 buf->ops = spd->ops;
209 buf->flags = 0;
210
211 pipe->nrbufs++;
212 page_nr++;
213 ret += buf->len;
214
215 if (!--spd->nr_pages)
216 break;
217 }
218
219 if (!ret)
220 ret = -EAGAIN;
221
222out:
223 while (page_nr < spd_pages)
224 spd->spd_release(spd, page_nr++);
225
226 return ret;
227}
228EXPORT_SYMBOL_GPL(splice_to_pipe);
229
230ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
231{
232 int ret;
233
234 if (unlikely(!pipe->readers)) {
235 send_sig(SIGPIPE, current, 0);
236 ret = -EPIPE;
237 } else if (pipe->nrbufs == pipe->buffers) {
238 ret = -EAGAIN;
239 } else {
240 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
241 pipe->bufs[newbuf] = *buf;
242 pipe->nrbufs++;
243 return buf->len;
244 }
245 pipe_buf_release(pipe, buf);
246 return ret;
247}
248EXPORT_SYMBOL(add_to_pipe);
249
250/*
251 * Check if we need to grow the arrays holding pages and partial page
252 * descriptions.
253 */
254int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
255{
256 unsigned int buffers = READ_ONCE(pipe->buffers);
257
258 spd->nr_pages_max = buffers;
259 if (buffers <= PIPE_DEF_BUFFERS)
260 return 0;
261
262 spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
263 spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
264
265 if (spd->pages && spd->partial)
266 return 0;
267
268 kfree(spd->pages);
269 kfree(spd->partial);
270 return -ENOMEM;
271}
272
273void splice_shrink_spd(struct splice_pipe_desc *spd)
274{
275 if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
276 return;
277
278 kfree(spd->pages);
279 kfree(spd->partial);
280}
281
282/**
283 * generic_file_splice_read - splice data from file to a pipe
284 * @in: file to splice from
285 * @ppos: position in @in
286 * @pipe: pipe to splice to
287 * @len: number of bytes to splice
288 * @flags: splice modifier flags
289 *
290 * Description:
291 * Will read pages from given file and fill them into a pipe. Can be
292 * used as long as it has more or less sane ->read_iter().
293 *
294 */
295ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
296 struct pipe_inode_info *pipe, size_t len,
297 unsigned int flags)
298{
299 struct iov_iter to;
300 struct kiocb kiocb;
301 int idx, ret;
302
303 iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len);
304 idx = to.idx;
305 init_sync_kiocb(&kiocb, in);
306 kiocb.ki_pos = *ppos;
307 ret = call_read_iter(in, &kiocb, &to);
308 if (ret > 0) {
309 *ppos = kiocb.ki_pos;
310 file_accessed(in);
311 } else if (ret < 0) {
312 to.idx = idx;
313 to.iov_offset = 0;
314 iov_iter_advance(&to, 0); /* to free what was emitted */
315 /*
316 * callers of ->splice_read() expect -EAGAIN on
317 * "can't put anything in there", rather than -EFAULT.
318 */
319 if (ret == -EFAULT)
320 ret = -EAGAIN;
321 }
322
323 return ret;
324}
325EXPORT_SYMBOL(generic_file_splice_read);
326
327const struct pipe_buf_operations default_pipe_buf_ops = {
328 .can_merge = 0,
329 .confirm = generic_pipe_buf_confirm,
330 .release = generic_pipe_buf_release,
331 .steal = generic_pipe_buf_steal,
332 .get = generic_pipe_buf_get,
333};
334
335static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
336 struct pipe_buffer *buf)
337{
338 return 1;
339}
340
341/* Pipe buffer operations for a socket and similar. */
342const struct pipe_buf_operations nosteal_pipe_buf_ops = {
343 .can_merge = 0,
344 .confirm = generic_pipe_buf_confirm,
345 .release = generic_pipe_buf_release,
346 .steal = generic_pipe_buf_nosteal,
347 .get = generic_pipe_buf_get,
348};
349EXPORT_SYMBOL(nosteal_pipe_buf_ops);
350
351static ssize_t kernel_readv(struct file *file, const struct kvec *vec,
352 unsigned long vlen, loff_t offset)
353{
354 mm_segment_t old_fs;
355 loff_t pos = offset;
356 ssize_t res;
357
358 old_fs = get_fs();
359 set_fs(get_ds());
360 /* The cast to a user pointer is valid due to the set_fs() */
361 res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0);
362 set_fs(old_fs);
363
364 return res;
365}
366
367static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
368 struct pipe_inode_info *pipe, size_t len,
369 unsigned int flags)
370{
371 struct kvec *vec, __vec[PIPE_DEF_BUFFERS];
372 struct iov_iter to;
373 struct page **pages;
374 unsigned int nr_pages;
375 size_t offset, base, copied = 0;
376 ssize_t res;
377 int i;
378
379 if (pipe->nrbufs == pipe->buffers)
380 return -EAGAIN;
381
382 /*
383 * Try to keep page boundaries matching to source pagecache ones -
384 * it probably won't be much help, but...
385 */
386 offset = *ppos & ~PAGE_MASK;
387
388 iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset);
389
390 res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &base);
391 if (res <= 0)
392 return -ENOMEM;
393
394 nr_pages = DIV_ROUND_UP(res + base, PAGE_SIZE);
395
396 vec = __vec;
397 if (nr_pages > PIPE_DEF_BUFFERS) {
398 vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL);
399 if (unlikely(!vec)) {
400 res = -ENOMEM;
401 goto out;
402 }
403 }
404
405 pipe->bufs[to.idx].offset = offset;
406 pipe->bufs[to.idx].len -= offset;
407
408 for (i = 0; i < nr_pages; i++) {
409 size_t this_len = min_t(size_t, len, PAGE_SIZE - offset);
410 vec[i].iov_base = page_address(pages[i]) + offset;
411 vec[i].iov_len = this_len;
412 len -= this_len;
413 offset = 0;
414 }
415
416 res = kernel_readv(in, vec, nr_pages, *ppos);
417 if (res > 0) {
418 copied = res;
419 *ppos += res;
420 }
421
422 if (vec != __vec)
423 kfree(vec);
424out:
425 for (i = 0; i < nr_pages; i++)
426 put_page(pages[i]);
427 kvfree(pages);
428 iov_iter_advance(&to, copied); /* truncates and discards */
429 return res;
430}
431
432/*
433 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
434 * using sendpage(). Return the number of bytes sent.
435 */
436static int pipe_to_sendpage(struct pipe_inode_info *pipe,
437 struct pipe_buffer *buf, struct splice_desc *sd)
438{
439 struct file *file = sd->u.file;
440 loff_t pos = sd->pos;
441 int more;
442
443 if (!likely(file->f_op->sendpage))
444 return -EINVAL;
445
446 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
447
448 if (sd->len < sd->total_len && pipe->nrbufs > 1)
449 more |= MSG_SENDPAGE_NOTLAST;
450
451 return file->f_op->sendpage(file, buf->page, buf->offset,
452 sd->len, &pos, more);
453}
454
455static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
456{
457 smp_mb();
458 if (waitqueue_active(&pipe->wait))
459 wake_up_interruptible(&pipe->wait);
460 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
461}
462
463/**
464 * splice_from_pipe_feed - feed available data from a pipe to a file
465 * @pipe: pipe to splice from
466 * @sd: information to @actor
467 * @actor: handler that splices the data
468 *
469 * Description:
470 * This function loops over the pipe and calls @actor to do the
471 * actual moving of a single struct pipe_buffer to the desired
472 * destination. It returns when there's no more buffers left in
473 * the pipe or if the requested number of bytes (@sd->total_len)
474 * have been copied. It returns a positive number (one) if the
475 * pipe needs to be filled with more data, zero if the required
476 * number of bytes have been copied and -errno on error.
477 *
478 * This, together with splice_from_pipe_{begin,end,next}, may be
479 * used to implement the functionality of __splice_from_pipe() when
480 * locking is required around copying the pipe buffers to the
481 * destination.
482 */
483static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
484 splice_actor *actor)
485{
486 int ret;
487
488 while (pipe->nrbufs) {
489 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
490
491 sd->len = buf->len;
492 if (sd->len > sd->total_len)
493 sd->len = sd->total_len;
494
495 ret = pipe_buf_confirm(pipe, buf);
496 if (unlikely(ret)) {
497 if (ret == -ENODATA)
498 ret = 0;
499 return ret;
500 }
501
502 ret = actor(pipe, buf, sd);
503 if (ret <= 0)
504 return ret;
505
506 buf->offset += ret;
507 buf->len -= ret;
508
509 sd->num_spliced += ret;
510 sd->len -= ret;
511 sd->pos += ret;
512 sd->total_len -= ret;
513
514 if (!buf->len) {
515 pipe_buf_release(pipe, buf);
516 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
517 pipe->nrbufs--;
518 if (pipe->files)
519 sd->need_wakeup = true;
520 }
521
522 if (!sd->total_len)
523 return 0;
524 }
525
526 return 1;
527}
528
529/**
530 * splice_from_pipe_next - wait for some data to splice from
531 * @pipe: pipe to splice from
532 * @sd: information about the splice operation
533 *
534 * Description:
535 * This function will wait for some data and return a positive
536 * value (one) if pipe buffers are available. It will return zero
537 * or -errno if no more data needs to be spliced.
538 */
539static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
540{
541 /*
542 * Check for signal early to make process killable when there are
543 * always buffers available
544 */
545 if (signal_pending(current))
546 return -ERESTARTSYS;
547
548 while (!pipe->nrbufs) {
549 if (!pipe->writers)
550 return 0;
551
552 if (!pipe->waiting_writers && sd->num_spliced)
553 return 0;
554
555 if (sd->flags & SPLICE_F_NONBLOCK)
556 return -EAGAIN;
557
558 if (signal_pending(current))
559 return -ERESTARTSYS;
560
561 if (sd->need_wakeup) {
562 wakeup_pipe_writers(pipe);
563 sd->need_wakeup = false;
564 }
565
566 pipe_wait(pipe);
567 }
568
569 return 1;
570}
571
572/**
573 * splice_from_pipe_begin - start splicing from pipe
574 * @sd: information about the splice operation
575 *
576 * Description:
577 * This function should be called before a loop containing
578 * splice_from_pipe_next() and splice_from_pipe_feed() to
579 * initialize the necessary fields of @sd.
580 */
581static void splice_from_pipe_begin(struct splice_desc *sd)
582{
583 sd->num_spliced = 0;
584 sd->need_wakeup = false;
585}
586
587/**
588 * splice_from_pipe_end - finish splicing from pipe
589 * @pipe: pipe to splice from
590 * @sd: information about the splice operation
591 *
592 * Description:
593 * This function will wake up pipe writers if necessary. It should
594 * be called after a loop containing splice_from_pipe_next() and
595 * splice_from_pipe_feed().
596 */
597static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
598{
599 if (sd->need_wakeup)
600 wakeup_pipe_writers(pipe);
601}
602
603/**
604 * __splice_from_pipe - splice data from a pipe to given actor
605 * @pipe: pipe to splice from
606 * @sd: information to @actor
607 * @actor: handler that splices the data
608 *
609 * Description:
610 * This function does little more than loop over the pipe and call
611 * @actor to do the actual moving of a single struct pipe_buffer to
612 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
613 * pipe_to_user.
614 *
615 */
616ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
617 splice_actor *actor)
618{
619 int ret;
620
621 splice_from_pipe_begin(sd);
622 do {
623 cond_resched();
624 ret = splice_from_pipe_next(pipe, sd);
625 if (ret > 0)
626 ret = splice_from_pipe_feed(pipe, sd, actor);
627 } while (ret > 0);
628 splice_from_pipe_end(pipe, sd);
629
630 return sd->num_spliced ? sd->num_spliced : ret;
631}
632EXPORT_SYMBOL(__splice_from_pipe);
633
634/**
635 * splice_from_pipe - splice data from a pipe to a file
636 * @pipe: pipe to splice from
637 * @out: file to splice to
638 * @ppos: position in @out
639 * @len: how many bytes to splice
640 * @flags: splice modifier flags
641 * @actor: handler that splices the data
642 *
643 * Description:
644 * See __splice_from_pipe. This function locks the pipe inode,
645 * otherwise it's identical to __splice_from_pipe().
646 *
647 */
648ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
649 loff_t *ppos, size_t len, unsigned int flags,
650 splice_actor *actor)
651{
652 ssize_t ret;
653 struct splice_desc sd = {
654 .total_len = len,
655 .flags = flags,
656 .pos = *ppos,
657 .u.file = out,
658 };
659
660 pipe_lock(pipe);
661 ret = __splice_from_pipe(pipe, &sd, actor);
662 pipe_unlock(pipe);
663
664 return ret;
665}
666
667/**
668 * iter_file_splice_write - splice data from a pipe to a file
669 * @pipe: pipe info
670 * @out: file to write to
671 * @ppos: position in @out
672 * @len: number of bytes to splice
673 * @flags: splice modifier flags
674 *
675 * Description:
676 * Will either move or copy pages (determined by @flags options) from
677 * the given pipe inode to the given file.
678 * This one is ->write_iter-based.
679 *
680 */
681ssize_t
682iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
683 loff_t *ppos, size_t len, unsigned int flags)
684{
685 struct splice_desc sd = {
686 .total_len = len,
687 .flags = flags,
688 .pos = *ppos,
689 .u.file = out,
690 };
691 int nbufs = pipe->buffers;
692 struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
693 GFP_KERNEL);
694 ssize_t ret;
695
696 if (unlikely(!array))
697 return -ENOMEM;
698
699 pipe_lock(pipe);
700
701 splice_from_pipe_begin(&sd);
702 while (sd.total_len) {
703 struct iov_iter from;
704 size_t left;
705 int n, idx;
706
707 ret = splice_from_pipe_next(pipe, &sd);
708 if (ret <= 0)
709 break;
710
711 if (unlikely(nbufs < pipe->buffers)) {
712 kfree(array);
713 nbufs = pipe->buffers;
714 array = kcalloc(nbufs, sizeof(struct bio_vec),
715 GFP_KERNEL);
716 if (!array) {
717 ret = -ENOMEM;
718 break;
719 }
720 }
721
722 /* build the vector */
723 left = sd.total_len;
724 for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) {
725 struct pipe_buffer *buf = pipe->bufs + idx;
726 size_t this_len = buf->len;
727
728 if (this_len > left)
729 this_len = left;
730
731 if (idx == pipe->buffers - 1)
732 idx = -1;
733
734 ret = pipe_buf_confirm(pipe, buf);
735 if (unlikely(ret)) {
736 if (ret == -ENODATA)
737 ret = 0;
738 goto done;
739 }
740
741 array[n].bv_page = buf->page;
742 array[n].bv_len = this_len;
743 array[n].bv_offset = buf->offset;
744 left -= this_len;
745 }
746
747 iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
748 sd.total_len - left);
749 ret = vfs_iter_write(out, &from, &sd.pos, 0);
750 if (ret <= 0)
751 break;
752
753 sd.num_spliced += ret;
754 sd.total_len -= ret;
755 *ppos = sd.pos;
756
757 /* dismiss the fully eaten buffers, adjust the partial one */
758 while (ret) {
759 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
760 if (ret >= buf->len) {
761 ret -= buf->len;
762 buf->len = 0;
763 pipe_buf_release(pipe, buf);
764 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
765 pipe->nrbufs--;
766 if (pipe->files)
767 sd.need_wakeup = true;
768 } else {
769 buf->offset += ret;
770 buf->len -= ret;
771 ret = 0;
772 }
773 }
774 }
775done:
776 kfree(array);
777 splice_from_pipe_end(pipe, &sd);
778
779 pipe_unlock(pipe);
780
781 if (sd.num_spliced)
782 ret = sd.num_spliced;
783
784 return ret;
785}
786
787EXPORT_SYMBOL(iter_file_splice_write);
788
789static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
790 struct splice_desc *sd)
791{
792 int ret;
793 void *data;
794 loff_t tmp = sd->pos;
795
796 data = kmap(buf->page);
797 ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
798 kunmap(buf->page);
799
800 return ret;
801}
802
803static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
804 struct file *out, loff_t *ppos,
805 size_t len, unsigned int flags)
806{
807 ssize_t ret;
808
809 ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
810 if (ret > 0)
811 *ppos += ret;
812
813 return ret;
814}
815
816/**
817 * generic_splice_sendpage - splice data from a pipe to a socket
818 * @pipe: pipe to splice from
819 * @out: socket to write to
820 * @ppos: position in @out
821 * @len: number of bytes to splice
822 * @flags: splice modifier flags
823 *
824 * Description:
825 * Will send @len bytes from the pipe to a network socket. No data copying
826 * is involved.
827 *
828 */
829ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
830 loff_t *ppos, size_t len, unsigned int flags)
831{
832 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
833}
834
835EXPORT_SYMBOL(generic_splice_sendpage);
836
837/*
838 * Attempt to initiate a splice from pipe to file.
839 */
840static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
841 loff_t *ppos, size_t len, unsigned int flags)
842{
843 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
844 loff_t *, size_t, unsigned int);
845
846 if (out->f_op->splice_write)
847 splice_write = out->f_op->splice_write;
848 else
849 splice_write = default_file_splice_write;
850
851 return splice_write(pipe, out, ppos, len, flags);
852}
853
854/*
855 * Attempt to initiate a splice from a file to a pipe.
856 */
857static long do_splice_to(struct file *in, loff_t *ppos,
858 struct pipe_inode_info *pipe, size_t len,
859 unsigned int flags)
860{
861 ssize_t (*splice_read)(struct file *, loff_t *,
862 struct pipe_inode_info *, size_t, unsigned int);
863 int ret;
864
865 if (unlikely(!(in->f_mode & FMODE_READ)))
866 return -EBADF;
867
868 ret = rw_verify_area(READ, in, ppos, len);
869 if (unlikely(ret < 0))
870 return ret;
871
872 if (unlikely(len > MAX_RW_COUNT))
873 len = MAX_RW_COUNT;
874
875 if (in->f_op->splice_read)
876 splice_read = in->f_op->splice_read;
877 else
878 splice_read = default_file_splice_read;
879
880 return splice_read(in, ppos, pipe, len, flags);
881}
882
883/**
884 * splice_direct_to_actor - splices data directly between two non-pipes
885 * @in: file to splice from
886 * @sd: actor information on where to splice to
887 * @actor: handles the data splicing
888 *
889 * Description:
890 * This is a special case helper to splice directly between two
891 * points, without requiring an explicit pipe. Internally an allocated
892 * pipe is cached in the process, and reused during the lifetime of
893 * that process.
894 *
895 */
896ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
897 splice_direct_actor *actor)
898{
899 struct pipe_inode_info *pipe;
900 long ret, bytes;
901 umode_t i_mode;
902 size_t len;
903 int i, flags, more;
904
905 /*
906 * We require the input being a regular file, as we don't want to
907 * randomly drop data for eg socket -> socket splicing. Use the
908 * piped splicing for that!
909 */
910 i_mode = file_inode(in)->i_mode;
911 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
912 return -EINVAL;
913
914 /*
915 * neither in nor out is a pipe, setup an internal pipe attached to
916 * 'out' and transfer the wanted data from 'in' to 'out' through that
917 */
918 pipe = current->splice_pipe;
919 if (unlikely(!pipe)) {
920 pipe = alloc_pipe_info();
921 if (!pipe)
922 return -ENOMEM;
923
924 /*
925 * We don't have an immediate reader, but we'll read the stuff
926 * out of the pipe right after the splice_to_pipe(). So set
927 * PIPE_READERS appropriately.
928 */
929 pipe->readers = 1;
930
931 current->splice_pipe = pipe;
932 }
933
934 /*
935 * Do the splice.
936 */
937 ret = 0;
938 bytes = 0;
939 len = sd->total_len;
940 flags = sd->flags;
941
942 /*
943 * Don't block on output, we have to drain the direct pipe.
944 */
945 sd->flags &= ~SPLICE_F_NONBLOCK;
946 more = sd->flags & SPLICE_F_MORE;
947
948 while (len) {
949 size_t read_len;
950 loff_t pos = sd->pos, prev_pos = pos;
951
952 ret = do_splice_to(in, &pos, pipe, len, flags);
953 if (unlikely(ret <= 0))
954 goto out_release;
955
956 read_len = ret;
957 sd->total_len = read_len;
958
959 /*
960 * If more data is pending, set SPLICE_F_MORE
961 * If this is the last data and SPLICE_F_MORE was not set
962 * initially, clears it.
963 */
964 if (read_len < len)
965 sd->flags |= SPLICE_F_MORE;
966 else if (!more)
967 sd->flags &= ~SPLICE_F_MORE;
968 /*
969 * NOTE: nonblocking mode only applies to the input. We
970 * must not do the output in nonblocking mode as then we
971 * could get stuck data in the internal pipe:
972 */
973 ret = actor(pipe, sd);
974 if (unlikely(ret <= 0)) {
975 sd->pos = prev_pos;
976 goto out_release;
977 }
978
979 bytes += ret;
980 len -= ret;
981 sd->pos = pos;
982
983 if (ret < read_len) {
984 sd->pos = prev_pos + ret;
985 goto out_release;
986 }
987 }
988
989done:
990 pipe->nrbufs = pipe->curbuf = 0;
991 file_accessed(in);
992 return bytes;
993
994out_release:
995 /*
996 * If we did an incomplete transfer we must release
997 * the pipe buffers in question:
998 */
999 for (i = 0; i < pipe->buffers; i++) {
1000 struct pipe_buffer *buf = pipe->bufs + i;
1001
1002 if (buf->ops)
1003 pipe_buf_release(pipe, buf);
1004 }
1005
1006 if (!bytes)
1007 bytes = ret;
1008
1009 goto done;
1010}
1011EXPORT_SYMBOL(splice_direct_to_actor);
1012
1013static int direct_splice_actor(struct pipe_inode_info *pipe,
1014 struct splice_desc *sd)
1015{
1016 struct file *file = sd->u.file;
1017
1018 return do_splice_from(pipe, file, sd->opos, sd->total_len,
1019 sd->flags);
1020}
1021
1022/**
1023 * do_splice_direct - splices data directly between two files
1024 * @in: file to splice from
1025 * @ppos: input file offset
1026 * @out: file to splice to
1027 * @opos: output file offset
1028 * @len: number of bytes to splice
1029 * @flags: splice modifier flags
1030 *
1031 * Description:
1032 * For use by do_sendfile(). splice can easily emulate sendfile, but
1033 * doing it in the application would incur an extra system call
1034 * (splice in + splice out, as compared to just sendfile()). So this helper
1035 * can splice directly through a process-private pipe.
1036 *
1037 */
1038long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
1039 loff_t *opos, size_t len, unsigned int flags)
1040{
1041 struct splice_desc sd = {
1042 .len = len,
1043 .total_len = len,
1044 .flags = flags,
1045 .pos = *ppos,
1046 .u.file = out,
1047 .opos = opos,
1048 };
1049 long ret;
1050
1051 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1052 return -EBADF;
1053
1054 if (unlikely(out->f_flags & O_APPEND))
1055 return -EINVAL;
1056
1057 ret = rw_verify_area(WRITE, out, opos, len);
1058 if (unlikely(ret < 0))
1059 return ret;
1060
1061 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
1062 if (ret > 0)
1063 *ppos = sd.pos;
1064
1065 return ret;
1066}
1067EXPORT_SYMBOL(do_splice_direct);
1068
1069static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
1070{
1071 for (;;) {
1072 if (unlikely(!pipe->readers)) {
1073 send_sig(SIGPIPE, current, 0);
1074 return -EPIPE;
1075 }
1076 if (pipe->nrbufs != pipe->buffers)
1077 return 0;
1078 if (flags & SPLICE_F_NONBLOCK)
1079 return -EAGAIN;
1080 if (signal_pending(current))
1081 return -ERESTARTSYS;
1082 pipe->waiting_writers++;
1083 pipe_wait(pipe);
1084 pipe->waiting_writers--;
1085 }
1086}
1087
1088static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1089 struct pipe_inode_info *opipe,
1090 size_t len, unsigned int flags);
1091
1092/*
1093 * Determine where to splice to/from.
1094 */
1095static long do_splice(struct file *in, loff_t __user *off_in,
1096 struct file *out, loff_t __user *off_out,
1097 size_t len, unsigned int flags)
1098{
1099 struct pipe_inode_info *ipipe;
1100 struct pipe_inode_info *opipe;
1101 loff_t offset;
1102 long ret;
1103
1104 ipipe = get_pipe_info(in);
1105 opipe = get_pipe_info(out);
1106
1107 if (ipipe && opipe) {
1108 if (off_in || off_out)
1109 return -ESPIPE;
1110
1111 if (!(in->f_mode & FMODE_READ))
1112 return -EBADF;
1113
1114 if (!(out->f_mode & FMODE_WRITE))
1115 return -EBADF;
1116
1117 /* Splicing to self would be fun, but... */
1118 if (ipipe == opipe)
1119 return -EINVAL;
1120
1121 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1122 }
1123
1124 if (ipipe) {
1125 if (off_in)
1126 return -ESPIPE;
1127 if (off_out) {
1128 if (!(out->f_mode & FMODE_PWRITE))
1129 return -EINVAL;
1130 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
1131 return -EFAULT;
1132 } else {
1133 offset = out->f_pos;
1134 }
1135
1136 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1137 return -EBADF;
1138
1139 if (unlikely(out->f_flags & O_APPEND))
1140 return -EINVAL;
1141
1142 ret = rw_verify_area(WRITE, out, &offset, len);
1143 if (unlikely(ret < 0))
1144 return ret;
1145
1146 file_start_write(out);
1147 ret = do_splice_from(ipipe, out, &offset, len, flags);
1148 file_end_write(out);
1149
1150 if (!off_out)
1151 out->f_pos = offset;
1152 else if (copy_to_user(off_out, &offset, sizeof(loff_t)))
1153 ret = -EFAULT;
1154
1155 return ret;
1156 }
1157
1158 if (opipe) {
1159 if (off_out)
1160 return -ESPIPE;
1161 if (off_in) {
1162 if (!(in->f_mode & FMODE_PREAD))
1163 return -EINVAL;
1164 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
1165 return -EFAULT;
1166 } else {
1167 offset = in->f_pos;
1168 }
1169
1170 pipe_lock(opipe);
1171 ret = wait_for_space(opipe, flags);
1172 if (!ret)
1173 ret = do_splice_to(in, &offset, opipe, len, flags);
1174 pipe_unlock(opipe);
1175 if (ret > 0)
1176 wakeup_pipe_readers(opipe);
1177 if (!off_in)
1178 in->f_pos = offset;
1179 else if (copy_to_user(off_in, &offset, sizeof(loff_t)))
1180 ret = -EFAULT;
1181
1182 return ret;
1183 }
1184
1185 return -EINVAL;
1186}
1187
1188static int iter_to_pipe(struct iov_iter *from,
1189 struct pipe_inode_info *pipe,
1190 unsigned flags)
1191{
1192 struct pipe_buffer buf = {
1193 .ops = &user_page_pipe_buf_ops,
1194 .flags = flags
1195 };
1196 size_t total = 0;
1197 int ret = 0;
1198 bool failed = false;
1199
1200 while (iov_iter_count(from) && !failed) {
1201 struct page *pages[16];
1202 ssize_t copied;
1203 size_t start;
1204 int n;
1205
1206 copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start);
1207 if (copied <= 0) {
1208 ret = copied;
1209 break;
1210 }
1211
1212 for (n = 0; copied; n++, start = 0) {
1213 int size = min_t(int, copied, PAGE_SIZE - start);
1214 if (!failed) {
1215 buf.page = pages[n];
1216 buf.offset = start;
1217 buf.len = size;
1218 ret = add_to_pipe(pipe, &buf);
1219 if (unlikely(ret < 0)) {
1220 failed = true;
1221 } else {
1222 iov_iter_advance(from, ret);
1223 total += ret;
1224 }
1225 } else {
1226 put_page(pages[n]);
1227 }
1228 copied -= size;
1229 }
1230 }
1231 return total ? total : ret;
1232}
1233
1234static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1235 struct splice_desc *sd)
1236{
1237 int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
1238 return n == sd->len ? n : -EFAULT;
1239}
1240
1241/*
1242 * For lack of a better implementation, implement vmsplice() to userspace
1243 * as a simple copy of the pipes pages to the user iov.
1244 */
1245static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
1246 unsigned long nr_segs, unsigned int flags)
1247{
1248 struct pipe_inode_info *pipe;
1249 struct splice_desc sd;
1250 long ret;
1251 struct iovec iovstack[UIO_FASTIOV];
1252 struct iovec *iov = iovstack;
1253 struct iov_iter iter;
1254
1255 pipe = get_pipe_info(file);
1256 if (!pipe)
1257 return -EBADF;
1258
1259 ret = import_iovec(READ, uiov, nr_segs,
1260 ARRAY_SIZE(iovstack), &iov, &iter);
1261 if (ret < 0)
1262 return ret;
1263
1264 sd.total_len = iov_iter_count(&iter);
1265 sd.len = 0;
1266 sd.flags = flags;
1267 sd.u.data = &iter;
1268 sd.pos = 0;
1269
1270 if (sd.total_len) {
1271 pipe_lock(pipe);
1272 ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
1273 pipe_unlock(pipe);
1274 }
1275
1276 kfree(iov);
1277 return ret;
1278}
1279
1280/*
1281 * vmsplice splices a user address range into a pipe. It can be thought of
1282 * as splice-from-memory, where the regular splice is splice-from-file (or
1283 * to file). In both cases the output is a pipe, naturally.
1284 */
1285static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
1286 unsigned long nr_segs, unsigned int flags)
1287{
1288 struct pipe_inode_info *pipe;
1289 struct iovec iovstack[UIO_FASTIOV];
1290 struct iovec *iov = iovstack;
1291 struct iov_iter from;
1292 long ret;
1293 unsigned buf_flag = 0;
1294
1295 if (flags & SPLICE_F_GIFT)
1296 buf_flag = PIPE_BUF_FLAG_GIFT;
1297
1298 pipe = get_pipe_info(file);
1299 if (!pipe)
1300 return -EBADF;
1301
1302 ret = import_iovec(WRITE, uiov, nr_segs,
1303 ARRAY_SIZE(iovstack), &iov, &from);
1304 if (ret < 0)
1305 return ret;
1306
1307 pipe_lock(pipe);
1308 ret = wait_for_space(pipe, flags);
1309 if (!ret)
1310 ret = iter_to_pipe(&from, pipe, buf_flag);
1311 pipe_unlock(pipe);
1312 if (ret > 0)
1313 wakeup_pipe_readers(pipe);
1314 kfree(iov);
1315 return ret;
1316}
1317
1318/*
1319 * Note that vmsplice only really supports true splicing _from_ user memory
1320 * to a pipe, not the other way around. Splicing from user memory is a simple
1321 * operation that can be supported without any funky alignment restrictions
1322 * or nasty vm tricks. We simply map in the user memory and fill them into
1323 * a pipe. The reverse isn't quite as easy, though. There are two possible
1324 * solutions for that:
1325 *
1326 * - memcpy() the data internally, at which point we might as well just
1327 * do a regular read() on the buffer anyway.
1328 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1329 * has restriction limitations on both ends of the pipe).
1330 *
1331 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1332 *
1333 */
1334static long do_vmsplice(int fd, const struct iovec __user *iov,
1335 unsigned long nr_segs, unsigned int flags)
1336{
1337 struct fd f;
1338 long error;
1339
1340 if (unlikely(flags & ~SPLICE_F_ALL))
1341 return -EINVAL;
1342 if (unlikely(nr_segs > UIO_MAXIOV))
1343 return -EINVAL;
1344 else if (unlikely(!nr_segs))
1345 return 0;
1346
1347 error = -EBADF;
1348 f = fdget(fd);
1349 if (f.file) {
1350 if (f.file->f_mode & FMODE_WRITE)
1351 error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
1352 else if (f.file->f_mode & FMODE_READ)
1353 error = vmsplice_to_user(f.file, iov, nr_segs, flags);
1354
1355 fdput(f);
1356 }
1357
1358 return error;
1359}
1360
1361SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
1362 unsigned long, nr_segs, unsigned int, flags)
1363{
1364 return do_vmsplice(fd, iov, nr_segs, flags);
1365}
1366
1367#ifdef CONFIG_COMPAT
1368COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
1369 unsigned int, nr_segs, unsigned int, flags)
1370{
1371 unsigned i;
1372 struct iovec __user *iov;
1373 if (nr_segs > UIO_MAXIOV)
1374 return -EINVAL;
1375 iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
1376 for (i = 0; i < nr_segs; i++) {
1377 struct compat_iovec v;
1378 if (get_user(v.iov_base, &iov32[i].iov_base) ||
1379 get_user(v.iov_len, &iov32[i].iov_len) ||
1380 put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
1381 put_user(v.iov_len, &iov[i].iov_len))
1382 return -EFAULT;
1383 }
1384 return do_vmsplice(fd, iov, nr_segs, flags);
1385}
1386#endif
1387
1388SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1389 int, fd_out, loff_t __user *, off_out,
1390 size_t, len, unsigned int, flags)
1391{
1392 struct fd in, out;
1393 long error;
1394
1395 if (unlikely(!len))
1396 return 0;
1397
1398 if (unlikely(flags & ~SPLICE_F_ALL))
1399 return -EINVAL;
1400
1401 error = -EBADF;
1402 in = fdget(fd_in);
1403 if (in.file) {
1404 if (in.file->f_mode & FMODE_READ) {
1405 out = fdget(fd_out);
1406 if (out.file) {
1407 if (out.file->f_mode & FMODE_WRITE)
1408 error = do_splice(in.file, off_in,
1409 out.file, off_out,
1410 len, flags);
1411 fdput(out);
1412 }
1413 }
1414 fdput(in);
1415 }
1416 return error;
1417}
1418
1419/*
1420 * Make sure there's data to read. Wait for input if we can, otherwise
1421 * return an appropriate error.
1422 */
1423static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1424{
1425 int ret;
1426
1427 /*
1428 * Check ->nrbufs without the inode lock first. This function
1429 * is speculative anyways, so missing one is ok.
1430 */
1431 if (pipe->nrbufs)
1432 return 0;
1433
1434 ret = 0;
1435 pipe_lock(pipe);
1436
1437 while (!pipe->nrbufs) {
1438 if (signal_pending(current)) {
1439 ret = -ERESTARTSYS;
1440 break;
1441 }
1442 if (!pipe->writers)
1443 break;
1444 if (!pipe->waiting_writers) {
1445 if (flags & SPLICE_F_NONBLOCK) {
1446 ret = -EAGAIN;
1447 break;
1448 }
1449 }
1450 pipe_wait(pipe);
1451 }
1452
1453 pipe_unlock(pipe);
1454 return ret;
1455}
1456
1457/*
1458 * Make sure there's writeable room. Wait for room if we can, otherwise
1459 * return an appropriate error.
1460 */
1461static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1462{
1463 int ret;
1464
1465 /*
1466 * Check ->nrbufs without the inode lock first. This function
1467 * is speculative anyways, so missing one is ok.
1468 */
1469 if (pipe->nrbufs < pipe->buffers)
1470 return 0;
1471
1472 ret = 0;
1473 pipe_lock(pipe);
1474
1475 while (pipe->nrbufs >= pipe->buffers) {
1476 if (!pipe->readers) {
1477 send_sig(SIGPIPE, current, 0);
1478 ret = -EPIPE;
1479 break;
1480 }
1481 if (flags & SPLICE_F_NONBLOCK) {
1482 ret = -EAGAIN;
1483 break;
1484 }
1485 if (signal_pending(current)) {
1486 ret = -ERESTARTSYS;
1487 break;
1488 }
1489 pipe->waiting_writers++;
1490 pipe_wait(pipe);
1491 pipe->waiting_writers--;
1492 }
1493
1494 pipe_unlock(pipe);
1495 return ret;
1496}
1497
1498/*
1499 * Splice contents of ipipe to opipe.
1500 */
1501static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1502 struct pipe_inode_info *opipe,
1503 size_t len, unsigned int flags)
1504{
1505 struct pipe_buffer *ibuf, *obuf;
1506 int ret = 0, nbuf;
1507 bool input_wakeup = false;
1508
1509
1510retry:
1511 ret = ipipe_prep(ipipe, flags);
1512 if (ret)
1513 return ret;
1514
1515 ret = opipe_prep(opipe, flags);
1516 if (ret)
1517 return ret;
1518
1519 /*
1520 * Potential ABBA deadlock, work around it by ordering lock
1521 * grabbing by pipe info address. Otherwise two different processes
1522 * could deadlock (one doing tee from A -> B, the other from B -> A).
1523 */
1524 pipe_double_lock(ipipe, opipe);
1525
1526 do {
1527 if (!opipe->readers) {
1528 send_sig(SIGPIPE, current, 0);
1529 if (!ret)
1530 ret = -EPIPE;
1531 break;
1532 }
1533
1534 if (!ipipe->nrbufs && !ipipe->writers)
1535 break;
1536
1537 /*
1538 * Cannot make any progress, because either the input
1539 * pipe is empty or the output pipe is full.
1540 */
1541 if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
1542 /* Already processed some buffers, break */
1543 if (ret)
1544 break;
1545
1546 if (flags & SPLICE_F_NONBLOCK) {
1547 ret = -EAGAIN;
1548 break;
1549 }
1550
1551 /*
1552 * We raced with another reader/writer and haven't
1553 * managed to process any buffers. A zero return
1554 * value means EOF, so retry instead.
1555 */
1556 pipe_unlock(ipipe);
1557 pipe_unlock(opipe);
1558 goto retry;
1559 }
1560
1561 ibuf = ipipe->bufs + ipipe->curbuf;
1562 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
1563 obuf = opipe->bufs + nbuf;
1564
1565 if (len >= ibuf->len) {
1566 /*
1567 * Simply move the whole buffer from ipipe to opipe
1568 */
1569 *obuf = *ibuf;
1570 ibuf->ops = NULL;
1571 opipe->nrbufs++;
1572 ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
1573 ipipe->nrbufs--;
1574 input_wakeup = true;
1575 } else {
1576 /*
1577 * Get a reference to this pipe buffer,
1578 * so we can copy the contents over.
1579 */
1580 pipe_buf_get(ipipe, ibuf);
1581 *obuf = *ibuf;
1582
1583 /*
1584 * Don't inherit the gift flag, we need to
1585 * prevent multiple steals of this page.
1586 */
1587 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1588
1589 obuf->len = len;
1590 opipe->nrbufs++;
1591 ibuf->offset += obuf->len;
1592 ibuf->len -= obuf->len;
1593 }
1594 ret += obuf->len;
1595 len -= obuf->len;
1596 } while (len);
1597
1598 pipe_unlock(ipipe);
1599 pipe_unlock(opipe);
1600
1601 /*
1602 * If we put data in the output pipe, wakeup any potential readers.
1603 */
1604 if (ret > 0)
1605 wakeup_pipe_readers(opipe);
1606
1607 if (input_wakeup)
1608 wakeup_pipe_writers(ipipe);
1609
1610 return ret;
1611}
1612
1613/*
1614 * Link contents of ipipe to opipe.
1615 */
1616static int link_pipe(struct pipe_inode_info *ipipe,
1617 struct pipe_inode_info *opipe,
1618 size_t len, unsigned int flags)
1619{
1620 struct pipe_buffer *ibuf, *obuf;
1621 int ret = 0, i = 0, nbuf;
1622
1623 /*
1624 * Potential ABBA deadlock, work around it by ordering lock
1625 * grabbing by pipe info address. Otherwise two different processes
1626 * could deadlock (one doing tee from A -> B, the other from B -> A).
1627 */
1628 pipe_double_lock(ipipe, opipe);
1629
1630 do {
1631 if (!opipe->readers) {
1632 send_sig(SIGPIPE, current, 0);
1633 if (!ret)
1634 ret = -EPIPE;
1635 break;
1636 }
1637
1638 /*
1639 * If we have iterated all input buffers or ran out of
1640 * output room, break.
1641 */
1642 if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
1643 break;
1644
1645 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
1646 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
1647
1648 /*
1649 * Get a reference to this pipe buffer,
1650 * so we can copy the contents over.
1651 */
1652 pipe_buf_get(ipipe, ibuf);
1653
1654 obuf = opipe->bufs + nbuf;
1655 *obuf = *ibuf;
1656
1657 /*
1658 * Don't inherit the gift flag, we need to
1659 * prevent multiple steals of this page.
1660 */
1661 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1662
1663 if (obuf->len > len)
1664 obuf->len = len;
1665
1666 opipe->nrbufs++;
1667 ret += obuf->len;
1668 len -= obuf->len;
1669 i++;
1670 } while (len);
1671
1672 /*
1673 * return EAGAIN if we have the potential of some data in the
1674 * future, otherwise just return 0
1675 */
1676 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1677 ret = -EAGAIN;
1678
1679 pipe_unlock(ipipe);
1680 pipe_unlock(opipe);
1681
1682 /*
1683 * If we put data in the output pipe, wakeup any potential readers.
1684 */
1685 if (ret > 0)
1686 wakeup_pipe_readers(opipe);
1687
1688 return ret;
1689}
1690
1691/*
1692 * This is a tee(1) implementation that works on pipes. It doesn't copy
1693 * any data, it simply references the 'in' pages on the 'out' pipe.
1694 * The 'flags' used are the SPLICE_F_* variants, currently the only
1695 * applicable one is SPLICE_F_NONBLOCK.
1696 */
1697static long do_tee(struct file *in, struct file *out, size_t len,
1698 unsigned int flags)
1699{
1700 struct pipe_inode_info *ipipe = get_pipe_info(in);
1701 struct pipe_inode_info *opipe = get_pipe_info(out);
1702 int ret = -EINVAL;
1703
1704 /*
1705 * Duplicate the contents of ipipe to opipe without actually
1706 * copying the data.
1707 */
1708 if (ipipe && opipe && ipipe != opipe) {
1709 /*
1710 * Keep going, unless we encounter an error. The ipipe/opipe
1711 * ordering doesn't really matter.
1712 */
1713 ret = ipipe_prep(ipipe, flags);
1714 if (!ret) {
1715 ret = opipe_prep(opipe, flags);
1716 if (!ret)
1717 ret = link_pipe(ipipe, opipe, len, flags);
1718 }
1719 }
1720
1721 return ret;
1722}
1723
1724SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
1725{
1726 struct fd in;
1727 int error;
1728
1729 if (unlikely(flags & ~SPLICE_F_ALL))
1730 return -EINVAL;
1731
1732 if (unlikely(!len))
1733 return 0;
1734
1735 error = -EBADF;
1736 in = fdget(fdin);
1737 if (in.file) {
1738 if (in.file->f_mode & FMODE_READ) {
1739 struct fd out = fdget(fdout);
1740 if (out.file) {
1741 if (out.file->f_mode & FMODE_WRITE)
1742 error = do_tee(in.file, out.file,
1743 len, flags);
1744 fdput(out);
1745 }
1746 }
1747 fdput(in);
1748 }
1749
1750 return error;
1751}
1/*
2 * "splice": joining two ropes together by interweaving their strands.
3 *
4 * This is the "extended pipe" functionality, where a pipe is used as
5 * an arbitrary in-memory buffer. Think of a pipe as a small kernel
6 * buffer that you can use to transfer data from one end to the other.
7 *
8 * The traditional unix read/write is extended with a "splice()" operation
9 * that transfers data buffers to or from a pipe buffer.
10 *
11 * Named by Larry McVoy, original implementation from Linus, extended by
12 * Jens to support splicing to files, network, direct splicing, etc and
13 * fixing lots of bugs.
14 *
15 * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
16 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
17 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
18 *
19 */
20#include <linux/bvec.h>
21#include <linux/fs.h>
22#include <linux/file.h>
23#include <linux/pagemap.h>
24#include <linux/splice.h>
25#include <linux/memcontrol.h>
26#include <linux/mm_inline.h>
27#include <linux/swap.h>
28#include <linux/writeback.h>
29#include <linux/export.h>
30#include <linux/syscalls.h>
31#include <linux/uio.h>
32#include <linux/security.h>
33#include <linux/gfp.h>
34#include <linux/socket.h>
35#include <linux/compat.h>
36#include "internal.h"
37
38/*
39 * Attempt to steal a page from a pipe buffer. This should perhaps go into
40 * a vm helper function, it's already simplified quite a bit by the
41 * addition of remove_mapping(). If success is returned, the caller may
42 * attempt to reuse this page for another destination.
43 */
44static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
45 struct pipe_buffer *buf)
46{
47 struct page *page = buf->page;
48 struct address_space *mapping;
49
50 lock_page(page);
51
52 mapping = page_mapping(page);
53 if (mapping) {
54 WARN_ON(!PageUptodate(page));
55
56 /*
57 * At least for ext2 with nobh option, we need to wait on
58 * writeback completing on this page, since we'll remove it
59 * from the pagecache. Otherwise truncate wont wait on the
60 * page, allowing the disk blocks to be reused by someone else
61 * before we actually wrote our data to them. fs corruption
62 * ensues.
63 */
64 wait_on_page_writeback(page);
65
66 if (page_has_private(page) &&
67 !try_to_release_page(page, GFP_KERNEL))
68 goto out_unlock;
69
70 /*
71 * If we succeeded in removing the mapping, set LRU flag
72 * and return good.
73 */
74 if (remove_mapping(mapping, page)) {
75 buf->flags |= PIPE_BUF_FLAG_LRU;
76 return 0;
77 }
78 }
79
80 /*
81 * Raced with truncate or failed to remove page from current
82 * address space, unlock and return failure.
83 */
84out_unlock:
85 unlock_page(page);
86 return 1;
87}
88
89static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
90 struct pipe_buffer *buf)
91{
92 put_page(buf->page);
93 buf->flags &= ~PIPE_BUF_FLAG_LRU;
94}
95
96/*
97 * Check whether the contents of buf is OK to access. Since the content
98 * is a page cache page, IO may be in flight.
99 */
100static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
101 struct pipe_buffer *buf)
102{
103 struct page *page = buf->page;
104 int err;
105
106 if (!PageUptodate(page)) {
107 lock_page(page);
108
109 /*
110 * Page got truncated/unhashed. This will cause a 0-byte
111 * splice, if this is the first page.
112 */
113 if (!page->mapping) {
114 err = -ENODATA;
115 goto error;
116 }
117
118 /*
119 * Uh oh, read-error from disk.
120 */
121 if (!PageUptodate(page)) {
122 err = -EIO;
123 goto error;
124 }
125
126 /*
127 * Page is ok afterall, we are done.
128 */
129 unlock_page(page);
130 }
131
132 return 0;
133error:
134 unlock_page(page);
135 return err;
136}
137
138const struct pipe_buf_operations page_cache_pipe_buf_ops = {
139 .can_merge = 0,
140 .confirm = page_cache_pipe_buf_confirm,
141 .release = page_cache_pipe_buf_release,
142 .steal = page_cache_pipe_buf_steal,
143 .get = generic_pipe_buf_get,
144};
145
146static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
147 struct pipe_buffer *buf)
148{
149 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
150 return 1;
151
152 buf->flags |= PIPE_BUF_FLAG_LRU;
153 return generic_pipe_buf_steal(pipe, buf);
154}
155
156static const struct pipe_buf_operations user_page_pipe_buf_ops = {
157 .can_merge = 0,
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,
162};
163
164static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
165{
166 smp_mb();
167 if (waitqueue_active(&pipe->wait))
168 wake_up_interruptible(&pipe->wait);
169 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
170}
171
172/**
173 * splice_to_pipe - fill passed data into a pipe
174 * @pipe: pipe to fill
175 * @spd: data to fill
176 *
177 * Description:
178 * @spd contains a map of pages and len/offset tuples, along with
179 * the struct pipe_buf_operations associated with these pages. This
180 * function will link that data to the pipe.
181 *
182 */
183ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
184 struct splice_pipe_desc *spd)
185{
186 unsigned int spd_pages = spd->nr_pages;
187 int ret = 0, page_nr = 0;
188
189 if (!spd_pages)
190 return 0;
191
192 if (unlikely(!pipe->readers)) {
193 send_sig(SIGPIPE, current, 0);
194 ret = -EPIPE;
195 goto out;
196 }
197
198 while (pipe->nrbufs < pipe->buffers) {
199 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
200 struct pipe_buffer *buf = pipe->bufs + newbuf;
201
202 buf->page = spd->pages[page_nr];
203 buf->offset = spd->partial[page_nr].offset;
204 buf->len = spd->partial[page_nr].len;
205 buf->private = spd->partial[page_nr].private;
206 buf->ops = spd->ops;
207 buf->flags = 0;
208
209 pipe->nrbufs++;
210 page_nr++;
211 ret += buf->len;
212
213 if (!--spd->nr_pages)
214 break;
215 }
216
217 if (!ret)
218 ret = -EAGAIN;
219
220out:
221 while (page_nr < spd_pages)
222 spd->spd_release(spd, page_nr++);
223
224 return ret;
225}
226EXPORT_SYMBOL_GPL(splice_to_pipe);
227
228ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
229{
230 int ret;
231
232 if (unlikely(!pipe->readers)) {
233 send_sig(SIGPIPE, current, 0);
234 ret = -EPIPE;
235 } else if (pipe->nrbufs == pipe->buffers) {
236 ret = -EAGAIN;
237 } else {
238 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
239 pipe->bufs[newbuf] = *buf;
240 pipe->nrbufs++;
241 return buf->len;
242 }
243 pipe_buf_release(pipe, buf);
244 return ret;
245}
246EXPORT_SYMBOL(add_to_pipe);
247
248void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
249{
250 put_page(spd->pages[i]);
251}
252
253/*
254 * Check if we need to grow the arrays holding pages and partial page
255 * descriptions.
256 */
257int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
258{
259 unsigned int buffers = ACCESS_ONCE(pipe->buffers);
260
261 spd->nr_pages_max = buffers;
262 if (buffers <= PIPE_DEF_BUFFERS)
263 return 0;
264
265 spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
266 spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
267
268 if (spd->pages && spd->partial)
269 return 0;
270
271 kfree(spd->pages);
272 kfree(spd->partial);
273 return -ENOMEM;
274}
275
276void splice_shrink_spd(struct splice_pipe_desc *spd)
277{
278 if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
279 return;
280
281 kfree(spd->pages);
282 kfree(spd->partial);
283}
284
285/**
286 * generic_file_splice_read - splice data from file to a pipe
287 * @in: file to splice from
288 * @ppos: position in @in
289 * @pipe: pipe to splice to
290 * @len: number of bytes to splice
291 * @flags: splice modifier flags
292 *
293 * Description:
294 * Will read pages from given file and fill them into a pipe. Can be
295 * used as long as it has more or less sane ->read_iter().
296 *
297 */
298ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
299 struct pipe_inode_info *pipe, size_t len,
300 unsigned int flags)
301{
302 struct iov_iter to;
303 struct kiocb kiocb;
304 int idx, ret;
305
306 iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len);
307 idx = to.idx;
308 init_sync_kiocb(&kiocb, in);
309 kiocb.ki_pos = *ppos;
310 ret = in->f_op->read_iter(&kiocb, &to);
311 if (ret > 0) {
312 *ppos = kiocb.ki_pos;
313 file_accessed(in);
314 } else if (ret < 0) {
315 to.idx = idx;
316 to.iov_offset = 0;
317 iov_iter_advance(&to, 0); /* to free what was emitted */
318 /*
319 * callers of ->splice_read() expect -EAGAIN on
320 * "can't put anything in there", rather than -EFAULT.
321 */
322 if (ret == -EFAULT)
323 ret = -EAGAIN;
324 }
325
326 return ret;
327}
328EXPORT_SYMBOL(generic_file_splice_read);
329
330const struct pipe_buf_operations default_pipe_buf_ops = {
331 .can_merge = 0,
332 .confirm = generic_pipe_buf_confirm,
333 .release = generic_pipe_buf_release,
334 .steal = generic_pipe_buf_steal,
335 .get = generic_pipe_buf_get,
336};
337
338static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
339 struct pipe_buffer *buf)
340{
341 return 1;
342}
343
344/* Pipe buffer operations for a socket and similar. */
345const struct pipe_buf_operations nosteal_pipe_buf_ops = {
346 .can_merge = 0,
347 .confirm = generic_pipe_buf_confirm,
348 .release = generic_pipe_buf_release,
349 .steal = generic_pipe_buf_nosteal,
350 .get = generic_pipe_buf_get,
351};
352EXPORT_SYMBOL(nosteal_pipe_buf_ops);
353
354static ssize_t kernel_readv(struct file *file, const struct kvec *vec,
355 unsigned long vlen, loff_t offset)
356{
357 mm_segment_t old_fs;
358 loff_t pos = offset;
359 ssize_t res;
360
361 old_fs = get_fs();
362 set_fs(get_ds());
363 /* The cast to a user pointer is valid due to the set_fs() */
364 res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0);
365 set_fs(old_fs);
366
367 return res;
368}
369
370ssize_t kernel_write(struct file *file, const char *buf, size_t count,
371 loff_t pos)
372{
373 mm_segment_t old_fs;
374 ssize_t res;
375
376 old_fs = get_fs();
377 set_fs(get_ds());
378 /* The cast to a user pointer is valid due to the set_fs() */
379 res = vfs_write(file, (__force const char __user *)buf, count, &pos);
380 set_fs(old_fs);
381
382 return res;
383}
384EXPORT_SYMBOL(kernel_write);
385
386static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
387 struct pipe_inode_info *pipe, size_t len,
388 unsigned int flags)
389{
390 struct kvec *vec, __vec[PIPE_DEF_BUFFERS];
391 struct iov_iter to;
392 struct page **pages;
393 unsigned int nr_pages;
394 size_t offset, dummy, copied = 0;
395 ssize_t res;
396 int i;
397
398 if (pipe->nrbufs == pipe->buffers)
399 return -EAGAIN;
400
401 /*
402 * Try to keep page boundaries matching to source pagecache ones -
403 * it probably won't be much help, but...
404 */
405 offset = *ppos & ~PAGE_MASK;
406
407 iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset);
408
409 res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &dummy);
410 if (res <= 0)
411 return -ENOMEM;
412
413 BUG_ON(dummy);
414 nr_pages = DIV_ROUND_UP(res, PAGE_SIZE);
415
416 vec = __vec;
417 if (nr_pages > PIPE_DEF_BUFFERS) {
418 vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL);
419 if (unlikely(!vec)) {
420 res = -ENOMEM;
421 goto out;
422 }
423 }
424
425 pipe->bufs[to.idx].offset = offset;
426 pipe->bufs[to.idx].len -= offset;
427
428 for (i = 0; i < nr_pages; i++) {
429 size_t this_len = min_t(size_t, len, PAGE_SIZE - offset);
430 vec[i].iov_base = page_address(pages[i]) + offset;
431 vec[i].iov_len = this_len;
432 len -= this_len;
433 offset = 0;
434 }
435
436 res = kernel_readv(in, vec, nr_pages, *ppos);
437 if (res > 0) {
438 copied = res;
439 *ppos += res;
440 }
441
442 if (vec != __vec)
443 kfree(vec);
444out:
445 for (i = 0; i < nr_pages; i++)
446 put_page(pages[i]);
447 kvfree(pages);
448 iov_iter_advance(&to, copied); /* truncates and discards */
449 return res;
450}
451
452/*
453 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
454 * using sendpage(). Return the number of bytes sent.
455 */
456static int pipe_to_sendpage(struct pipe_inode_info *pipe,
457 struct pipe_buffer *buf, struct splice_desc *sd)
458{
459 struct file *file = sd->u.file;
460 loff_t pos = sd->pos;
461 int more;
462
463 if (!likely(file->f_op->sendpage))
464 return -EINVAL;
465
466 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
467
468 if (sd->len < sd->total_len && pipe->nrbufs > 1)
469 more |= MSG_SENDPAGE_NOTLAST;
470
471 return file->f_op->sendpage(file, buf->page, buf->offset,
472 sd->len, &pos, more);
473}
474
475static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
476{
477 smp_mb();
478 if (waitqueue_active(&pipe->wait))
479 wake_up_interruptible(&pipe->wait);
480 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
481}
482
483/**
484 * splice_from_pipe_feed - feed available data from a pipe to a file
485 * @pipe: pipe to splice from
486 * @sd: information to @actor
487 * @actor: handler that splices the data
488 *
489 * Description:
490 * This function loops over the pipe and calls @actor to do the
491 * actual moving of a single struct pipe_buffer to the desired
492 * destination. It returns when there's no more buffers left in
493 * the pipe or if the requested number of bytes (@sd->total_len)
494 * have been copied. It returns a positive number (one) if the
495 * pipe needs to be filled with more data, zero if the required
496 * number of bytes have been copied and -errno on error.
497 *
498 * This, together with splice_from_pipe_{begin,end,next}, may be
499 * used to implement the functionality of __splice_from_pipe() when
500 * locking is required around copying the pipe buffers to the
501 * destination.
502 */
503static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
504 splice_actor *actor)
505{
506 int ret;
507
508 while (pipe->nrbufs) {
509 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
510
511 sd->len = buf->len;
512 if (sd->len > sd->total_len)
513 sd->len = sd->total_len;
514
515 ret = pipe_buf_confirm(pipe, buf);
516 if (unlikely(ret)) {
517 if (ret == -ENODATA)
518 ret = 0;
519 return ret;
520 }
521
522 ret = actor(pipe, buf, sd);
523 if (ret <= 0)
524 return ret;
525
526 buf->offset += ret;
527 buf->len -= ret;
528
529 sd->num_spliced += ret;
530 sd->len -= ret;
531 sd->pos += ret;
532 sd->total_len -= ret;
533
534 if (!buf->len) {
535 pipe_buf_release(pipe, buf);
536 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
537 pipe->nrbufs--;
538 if (pipe->files)
539 sd->need_wakeup = true;
540 }
541
542 if (!sd->total_len)
543 return 0;
544 }
545
546 return 1;
547}
548
549/**
550 * splice_from_pipe_next - wait for some data to splice from
551 * @pipe: pipe to splice from
552 * @sd: information about the splice operation
553 *
554 * Description:
555 * This function will wait for some data and return a positive
556 * value (one) if pipe buffers are available. It will return zero
557 * or -errno if no more data needs to be spliced.
558 */
559static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
560{
561 /*
562 * Check for signal early to make process killable when there are
563 * always buffers available
564 */
565 if (signal_pending(current))
566 return -ERESTARTSYS;
567
568 while (!pipe->nrbufs) {
569 if (!pipe->writers)
570 return 0;
571
572 if (!pipe->waiting_writers && sd->num_spliced)
573 return 0;
574
575 if (sd->flags & SPLICE_F_NONBLOCK)
576 return -EAGAIN;
577
578 if (signal_pending(current))
579 return -ERESTARTSYS;
580
581 if (sd->need_wakeup) {
582 wakeup_pipe_writers(pipe);
583 sd->need_wakeup = false;
584 }
585
586 pipe_wait(pipe);
587 }
588
589 return 1;
590}
591
592/**
593 * splice_from_pipe_begin - start splicing from pipe
594 * @sd: information about the splice operation
595 *
596 * Description:
597 * This function should be called before a loop containing
598 * splice_from_pipe_next() and splice_from_pipe_feed() to
599 * initialize the necessary fields of @sd.
600 */
601static void splice_from_pipe_begin(struct splice_desc *sd)
602{
603 sd->num_spliced = 0;
604 sd->need_wakeup = false;
605}
606
607/**
608 * splice_from_pipe_end - finish splicing from pipe
609 * @pipe: pipe to splice from
610 * @sd: information about the splice operation
611 *
612 * Description:
613 * This function will wake up pipe writers if necessary. It should
614 * be called after a loop containing splice_from_pipe_next() and
615 * splice_from_pipe_feed().
616 */
617static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
618{
619 if (sd->need_wakeup)
620 wakeup_pipe_writers(pipe);
621}
622
623/**
624 * __splice_from_pipe - splice data from a pipe to given actor
625 * @pipe: pipe to splice from
626 * @sd: information to @actor
627 * @actor: handler that splices the data
628 *
629 * Description:
630 * This function does little more than loop over the pipe and call
631 * @actor to do the actual moving of a single struct pipe_buffer to
632 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
633 * pipe_to_user.
634 *
635 */
636ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
637 splice_actor *actor)
638{
639 int ret;
640
641 splice_from_pipe_begin(sd);
642 do {
643 cond_resched();
644 ret = splice_from_pipe_next(pipe, sd);
645 if (ret > 0)
646 ret = splice_from_pipe_feed(pipe, sd, actor);
647 } while (ret > 0);
648 splice_from_pipe_end(pipe, sd);
649
650 return sd->num_spliced ? sd->num_spliced : ret;
651}
652EXPORT_SYMBOL(__splice_from_pipe);
653
654/**
655 * splice_from_pipe - splice data from a pipe to a file
656 * @pipe: pipe to splice from
657 * @out: file to splice to
658 * @ppos: position in @out
659 * @len: how many bytes to splice
660 * @flags: splice modifier flags
661 * @actor: handler that splices the data
662 *
663 * Description:
664 * See __splice_from_pipe. This function locks the pipe inode,
665 * otherwise it's identical to __splice_from_pipe().
666 *
667 */
668ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
669 loff_t *ppos, size_t len, unsigned int flags,
670 splice_actor *actor)
671{
672 ssize_t ret;
673 struct splice_desc sd = {
674 .total_len = len,
675 .flags = flags,
676 .pos = *ppos,
677 .u.file = out,
678 };
679
680 pipe_lock(pipe);
681 ret = __splice_from_pipe(pipe, &sd, actor);
682 pipe_unlock(pipe);
683
684 return ret;
685}
686
687/**
688 * iter_file_splice_write - splice data from a pipe to a file
689 * @pipe: pipe info
690 * @out: file to write to
691 * @ppos: position in @out
692 * @len: number of bytes to splice
693 * @flags: splice modifier flags
694 *
695 * Description:
696 * Will either move or copy pages (determined by @flags options) from
697 * the given pipe inode to the given file.
698 * This one is ->write_iter-based.
699 *
700 */
701ssize_t
702iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
703 loff_t *ppos, size_t len, unsigned int flags)
704{
705 struct splice_desc sd = {
706 .total_len = len,
707 .flags = flags,
708 .pos = *ppos,
709 .u.file = out,
710 };
711 int nbufs = pipe->buffers;
712 struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
713 GFP_KERNEL);
714 ssize_t ret;
715
716 if (unlikely(!array))
717 return -ENOMEM;
718
719 pipe_lock(pipe);
720
721 splice_from_pipe_begin(&sd);
722 while (sd.total_len) {
723 struct iov_iter from;
724 size_t left;
725 int n, idx;
726
727 ret = splice_from_pipe_next(pipe, &sd);
728 if (ret <= 0)
729 break;
730
731 if (unlikely(nbufs < pipe->buffers)) {
732 kfree(array);
733 nbufs = pipe->buffers;
734 array = kcalloc(nbufs, sizeof(struct bio_vec),
735 GFP_KERNEL);
736 if (!array) {
737 ret = -ENOMEM;
738 break;
739 }
740 }
741
742 /* build the vector */
743 left = sd.total_len;
744 for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) {
745 struct pipe_buffer *buf = pipe->bufs + idx;
746 size_t this_len = buf->len;
747
748 if (this_len > left)
749 this_len = left;
750
751 if (idx == pipe->buffers - 1)
752 idx = -1;
753
754 ret = pipe_buf_confirm(pipe, buf);
755 if (unlikely(ret)) {
756 if (ret == -ENODATA)
757 ret = 0;
758 goto done;
759 }
760
761 array[n].bv_page = buf->page;
762 array[n].bv_len = this_len;
763 array[n].bv_offset = buf->offset;
764 left -= this_len;
765 }
766
767 iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
768 sd.total_len - left);
769 ret = vfs_iter_write(out, &from, &sd.pos);
770 if (ret <= 0)
771 break;
772
773 sd.num_spliced += ret;
774 sd.total_len -= ret;
775 *ppos = sd.pos;
776
777 /* dismiss the fully eaten buffers, adjust the partial one */
778 while (ret) {
779 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
780 if (ret >= buf->len) {
781 ret -= buf->len;
782 buf->len = 0;
783 pipe_buf_release(pipe, buf);
784 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
785 pipe->nrbufs--;
786 if (pipe->files)
787 sd.need_wakeup = true;
788 } else {
789 buf->offset += ret;
790 buf->len -= ret;
791 ret = 0;
792 }
793 }
794 }
795done:
796 kfree(array);
797 splice_from_pipe_end(pipe, &sd);
798
799 pipe_unlock(pipe);
800
801 if (sd.num_spliced)
802 ret = sd.num_spliced;
803
804 return ret;
805}
806
807EXPORT_SYMBOL(iter_file_splice_write);
808
809static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
810 struct splice_desc *sd)
811{
812 int ret;
813 void *data;
814 loff_t tmp = sd->pos;
815
816 data = kmap(buf->page);
817 ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
818 kunmap(buf->page);
819
820 return ret;
821}
822
823static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
824 struct file *out, loff_t *ppos,
825 size_t len, unsigned int flags)
826{
827 ssize_t ret;
828
829 ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
830 if (ret > 0)
831 *ppos += ret;
832
833 return ret;
834}
835
836/**
837 * generic_splice_sendpage - splice data from a pipe to a socket
838 * @pipe: pipe to splice from
839 * @out: socket to write to
840 * @ppos: position in @out
841 * @len: number of bytes to splice
842 * @flags: splice modifier flags
843 *
844 * Description:
845 * Will send @len bytes from the pipe to a network socket. No data copying
846 * is involved.
847 *
848 */
849ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
850 loff_t *ppos, size_t len, unsigned int flags)
851{
852 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
853}
854
855EXPORT_SYMBOL(generic_splice_sendpage);
856
857/*
858 * Attempt to initiate a splice from pipe to file.
859 */
860static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
861 loff_t *ppos, size_t len, unsigned int flags)
862{
863 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
864 loff_t *, size_t, unsigned int);
865
866 if (out->f_op->splice_write)
867 splice_write = out->f_op->splice_write;
868 else
869 splice_write = default_file_splice_write;
870
871 return splice_write(pipe, out, ppos, len, flags);
872}
873
874/*
875 * Attempt to initiate a splice from a file to a pipe.
876 */
877static long do_splice_to(struct file *in, loff_t *ppos,
878 struct pipe_inode_info *pipe, size_t len,
879 unsigned int flags)
880{
881 ssize_t (*splice_read)(struct file *, loff_t *,
882 struct pipe_inode_info *, size_t, unsigned int);
883 int ret;
884
885 if (unlikely(!(in->f_mode & FMODE_READ)))
886 return -EBADF;
887
888 ret = rw_verify_area(READ, in, ppos, len);
889 if (unlikely(ret < 0))
890 return ret;
891
892 if (unlikely(len > MAX_RW_COUNT))
893 len = MAX_RW_COUNT;
894
895 if (in->f_op->splice_read)
896 splice_read = in->f_op->splice_read;
897 else
898 splice_read = default_file_splice_read;
899
900 return splice_read(in, ppos, pipe, len, flags);
901}
902
903/**
904 * splice_direct_to_actor - splices data directly between two non-pipes
905 * @in: file to splice from
906 * @sd: actor information on where to splice to
907 * @actor: handles the data splicing
908 *
909 * Description:
910 * This is a special case helper to splice directly between two
911 * points, without requiring an explicit pipe. Internally an allocated
912 * pipe is cached in the process, and reused during the lifetime of
913 * that process.
914 *
915 */
916ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
917 splice_direct_actor *actor)
918{
919 struct pipe_inode_info *pipe;
920 long ret, bytes;
921 umode_t i_mode;
922 size_t len;
923 int i, flags, more;
924
925 /*
926 * We require the input being a regular file, as we don't want to
927 * randomly drop data for eg socket -> socket splicing. Use the
928 * piped splicing for that!
929 */
930 i_mode = file_inode(in)->i_mode;
931 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
932 return -EINVAL;
933
934 /*
935 * neither in nor out is a pipe, setup an internal pipe attached to
936 * 'out' and transfer the wanted data from 'in' to 'out' through that
937 */
938 pipe = current->splice_pipe;
939 if (unlikely(!pipe)) {
940 pipe = alloc_pipe_info();
941 if (!pipe)
942 return -ENOMEM;
943
944 /*
945 * We don't have an immediate reader, but we'll read the stuff
946 * out of the pipe right after the splice_to_pipe(). So set
947 * PIPE_READERS appropriately.
948 */
949 pipe->readers = 1;
950
951 current->splice_pipe = pipe;
952 }
953
954 /*
955 * Do the splice.
956 */
957 ret = 0;
958 bytes = 0;
959 len = sd->total_len;
960 flags = sd->flags;
961
962 /*
963 * Don't block on output, we have to drain the direct pipe.
964 */
965 sd->flags &= ~SPLICE_F_NONBLOCK;
966 more = sd->flags & SPLICE_F_MORE;
967
968 while (len) {
969 size_t read_len;
970 loff_t pos = sd->pos, prev_pos = pos;
971
972 ret = do_splice_to(in, &pos, pipe, len, flags);
973 if (unlikely(ret <= 0))
974 goto out_release;
975
976 read_len = ret;
977 sd->total_len = read_len;
978
979 /*
980 * If more data is pending, set SPLICE_F_MORE
981 * If this is the last data and SPLICE_F_MORE was not set
982 * initially, clears it.
983 */
984 if (read_len < len)
985 sd->flags |= SPLICE_F_MORE;
986 else if (!more)
987 sd->flags &= ~SPLICE_F_MORE;
988 /*
989 * NOTE: nonblocking mode only applies to the input. We
990 * must not do the output in nonblocking mode as then we
991 * could get stuck data in the internal pipe:
992 */
993 ret = actor(pipe, sd);
994 if (unlikely(ret <= 0)) {
995 sd->pos = prev_pos;
996 goto out_release;
997 }
998
999 bytes += ret;
1000 len -= ret;
1001 sd->pos = pos;
1002
1003 if (ret < read_len) {
1004 sd->pos = prev_pos + ret;
1005 goto out_release;
1006 }
1007 }
1008
1009done:
1010 pipe->nrbufs = pipe->curbuf = 0;
1011 file_accessed(in);
1012 return bytes;
1013
1014out_release:
1015 /*
1016 * If we did an incomplete transfer we must release
1017 * the pipe buffers in question:
1018 */
1019 for (i = 0; i < pipe->buffers; i++) {
1020 struct pipe_buffer *buf = pipe->bufs + i;
1021
1022 if (buf->ops)
1023 pipe_buf_release(pipe, buf);
1024 }
1025
1026 if (!bytes)
1027 bytes = ret;
1028
1029 goto done;
1030}
1031EXPORT_SYMBOL(splice_direct_to_actor);
1032
1033static int direct_splice_actor(struct pipe_inode_info *pipe,
1034 struct splice_desc *sd)
1035{
1036 struct file *file = sd->u.file;
1037
1038 return do_splice_from(pipe, file, sd->opos, sd->total_len,
1039 sd->flags);
1040}
1041
1042/**
1043 * do_splice_direct - splices data directly between two files
1044 * @in: file to splice from
1045 * @ppos: input file offset
1046 * @out: file to splice to
1047 * @opos: output file offset
1048 * @len: number of bytes to splice
1049 * @flags: splice modifier flags
1050 *
1051 * Description:
1052 * For use by do_sendfile(). splice can easily emulate sendfile, but
1053 * doing it in the application would incur an extra system call
1054 * (splice in + splice out, as compared to just sendfile()). So this helper
1055 * can splice directly through a process-private pipe.
1056 *
1057 */
1058long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
1059 loff_t *opos, size_t len, unsigned int flags)
1060{
1061 struct splice_desc sd = {
1062 .len = len,
1063 .total_len = len,
1064 .flags = flags,
1065 .pos = *ppos,
1066 .u.file = out,
1067 .opos = opos,
1068 };
1069 long ret;
1070
1071 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1072 return -EBADF;
1073
1074 if (unlikely(out->f_flags & O_APPEND))
1075 return -EINVAL;
1076
1077 ret = rw_verify_area(WRITE, out, opos, len);
1078 if (unlikely(ret < 0))
1079 return ret;
1080
1081 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
1082 if (ret > 0)
1083 *ppos = sd.pos;
1084
1085 return ret;
1086}
1087EXPORT_SYMBOL(do_splice_direct);
1088
1089static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
1090{
1091 for (;;) {
1092 if (unlikely(!pipe->readers)) {
1093 send_sig(SIGPIPE, current, 0);
1094 return -EPIPE;
1095 }
1096 if (pipe->nrbufs != pipe->buffers)
1097 return 0;
1098 if (flags & SPLICE_F_NONBLOCK)
1099 return -EAGAIN;
1100 if (signal_pending(current))
1101 return -ERESTARTSYS;
1102 pipe->waiting_writers++;
1103 pipe_wait(pipe);
1104 pipe->waiting_writers--;
1105 }
1106}
1107
1108static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1109 struct pipe_inode_info *opipe,
1110 size_t len, unsigned int flags);
1111
1112/*
1113 * Determine where to splice to/from.
1114 */
1115static long do_splice(struct file *in, loff_t __user *off_in,
1116 struct file *out, loff_t __user *off_out,
1117 size_t len, unsigned int flags)
1118{
1119 struct pipe_inode_info *ipipe;
1120 struct pipe_inode_info *opipe;
1121 loff_t offset;
1122 long ret;
1123
1124 ipipe = get_pipe_info(in);
1125 opipe = get_pipe_info(out);
1126
1127 if (ipipe && opipe) {
1128 if (off_in || off_out)
1129 return -ESPIPE;
1130
1131 if (!(in->f_mode & FMODE_READ))
1132 return -EBADF;
1133
1134 if (!(out->f_mode & FMODE_WRITE))
1135 return -EBADF;
1136
1137 /* Splicing to self would be fun, but... */
1138 if (ipipe == opipe)
1139 return -EINVAL;
1140
1141 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1142 }
1143
1144 if (ipipe) {
1145 if (off_in)
1146 return -ESPIPE;
1147 if (off_out) {
1148 if (!(out->f_mode & FMODE_PWRITE))
1149 return -EINVAL;
1150 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
1151 return -EFAULT;
1152 } else {
1153 offset = out->f_pos;
1154 }
1155
1156 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1157 return -EBADF;
1158
1159 if (unlikely(out->f_flags & O_APPEND))
1160 return -EINVAL;
1161
1162 ret = rw_verify_area(WRITE, out, &offset, len);
1163 if (unlikely(ret < 0))
1164 return ret;
1165
1166 file_start_write(out);
1167 ret = do_splice_from(ipipe, out, &offset, len, flags);
1168 file_end_write(out);
1169
1170 if (!off_out)
1171 out->f_pos = offset;
1172 else if (copy_to_user(off_out, &offset, sizeof(loff_t)))
1173 ret = -EFAULT;
1174
1175 return ret;
1176 }
1177
1178 if (opipe) {
1179 if (off_out)
1180 return -ESPIPE;
1181 if (off_in) {
1182 if (!(in->f_mode & FMODE_PREAD))
1183 return -EINVAL;
1184 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
1185 return -EFAULT;
1186 } else {
1187 offset = in->f_pos;
1188 }
1189
1190 pipe_lock(opipe);
1191 ret = wait_for_space(opipe, flags);
1192 if (!ret)
1193 ret = do_splice_to(in, &offset, opipe, len, flags);
1194 pipe_unlock(opipe);
1195 if (ret > 0)
1196 wakeup_pipe_readers(opipe);
1197 if (!off_in)
1198 in->f_pos = offset;
1199 else if (copy_to_user(off_in, &offset, sizeof(loff_t)))
1200 ret = -EFAULT;
1201
1202 return ret;
1203 }
1204
1205 return -EINVAL;
1206}
1207
1208static int iter_to_pipe(struct iov_iter *from,
1209 struct pipe_inode_info *pipe,
1210 unsigned flags)
1211{
1212 struct pipe_buffer buf = {
1213 .ops = &user_page_pipe_buf_ops,
1214 .flags = flags
1215 };
1216 size_t total = 0;
1217 int ret = 0;
1218 bool failed = false;
1219
1220 while (iov_iter_count(from) && !failed) {
1221 struct page *pages[16];
1222 ssize_t copied;
1223 size_t start;
1224 int n;
1225
1226 copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start);
1227 if (copied <= 0) {
1228 ret = copied;
1229 break;
1230 }
1231
1232 for (n = 0; copied; n++, start = 0) {
1233 int size = min_t(int, copied, PAGE_SIZE - start);
1234 if (!failed) {
1235 buf.page = pages[n];
1236 buf.offset = start;
1237 buf.len = size;
1238 ret = add_to_pipe(pipe, &buf);
1239 if (unlikely(ret < 0)) {
1240 failed = true;
1241 } else {
1242 iov_iter_advance(from, ret);
1243 total += ret;
1244 }
1245 } else {
1246 put_page(pages[n]);
1247 }
1248 copied -= size;
1249 }
1250 }
1251 return total ? total : ret;
1252}
1253
1254static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1255 struct splice_desc *sd)
1256{
1257 int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
1258 return n == sd->len ? n : -EFAULT;
1259}
1260
1261/*
1262 * For lack of a better implementation, implement vmsplice() to userspace
1263 * as a simple copy of the pipes pages to the user iov.
1264 */
1265static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
1266 unsigned long nr_segs, unsigned int flags)
1267{
1268 struct pipe_inode_info *pipe;
1269 struct splice_desc sd;
1270 long ret;
1271 struct iovec iovstack[UIO_FASTIOV];
1272 struct iovec *iov = iovstack;
1273 struct iov_iter iter;
1274
1275 pipe = get_pipe_info(file);
1276 if (!pipe)
1277 return -EBADF;
1278
1279 ret = import_iovec(READ, uiov, nr_segs,
1280 ARRAY_SIZE(iovstack), &iov, &iter);
1281 if (ret < 0)
1282 return ret;
1283
1284 sd.total_len = iov_iter_count(&iter);
1285 sd.len = 0;
1286 sd.flags = flags;
1287 sd.u.data = &iter;
1288 sd.pos = 0;
1289
1290 if (sd.total_len) {
1291 pipe_lock(pipe);
1292 ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
1293 pipe_unlock(pipe);
1294 }
1295
1296 kfree(iov);
1297 return ret;
1298}
1299
1300/*
1301 * vmsplice splices a user address range into a pipe. It can be thought of
1302 * as splice-from-memory, where the regular splice is splice-from-file (or
1303 * to file). In both cases the output is a pipe, naturally.
1304 */
1305static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
1306 unsigned long nr_segs, unsigned int flags)
1307{
1308 struct pipe_inode_info *pipe;
1309 struct iovec iovstack[UIO_FASTIOV];
1310 struct iovec *iov = iovstack;
1311 struct iov_iter from;
1312 long ret;
1313 unsigned buf_flag = 0;
1314
1315 if (flags & SPLICE_F_GIFT)
1316 buf_flag = PIPE_BUF_FLAG_GIFT;
1317
1318 pipe = get_pipe_info(file);
1319 if (!pipe)
1320 return -EBADF;
1321
1322 ret = import_iovec(WRITE, uiov, nr_segs,
1323 ARRAY_SIZE(iovstack), &iov, &from);
1324 if (ret < 0)
1325 return ret;
1326
1327 pipe_lock(pipe);
1328 ret = wait_for_space(pipe, flags);
1329 if (!ret)
1330 ret = iter_to_pipe(&from, pipe, buf_flag);
1331 pipe_unlock(pipe);
1332 if (ret > 0)
1333 wakeup_pipe_readers(pipe);
1334 kfree(iov);
1335 return ret;
1336}
1337
1338/*
1339 * Note that vmsplice only really supports true splicing _from_ user memory
1340 * to a pipe, not the other way around. Splicing from user memory is a simple
1341 * operation that can be supported without any funky alignment restrictions
1342 * or nasty vm tricks. We simply map in the user memory and fill them into
1343 * a pipe. The reverse isn't quite as easy, though. There are two possible
1344 * solutions for that:
1345 *
1346 * - memcpy() the data internally, at which point we might as well just
1347 * do a regular read() on the buffer anyway.
1348 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1349 * has restriction limitations on both ends of the pipe).
1350 *
1351 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1352 *
1353 */
1354SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
1355 unsigned long, nr_segs, unsigned int, flags)
1356{
1357 struct fd f;
1358 long error;
1359
1360 if (unlikely(nr_segs > UIO_MAXIOV))
1361 return -EINVAL;
1362 else if (unlikely(!nr_segs))
1363 return 0;
1364
1365 error = -EBADF;
1366 f = fdget(fd);
1367 if (f.file) {
1368 if (f.file->f_mode & FMODE_WRITE)
1369 error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
1370 else if (f.file->f_mode & FMODE_READ)
1371 error = vmsplice_to_user(f.file, iov, nr_segs, flags);
1372
1373 fdput(f);
1374 }
1375
1376 return error;
1377}
1378
1379#ifdef CONFIG_COMPAT
1380COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
1381 unsigned int, nr_segs, unsigned int, flags)
1382{
1383 unsigned i;
1384 struct iovec __user *iov;
1385 if (nr_segs > UIO_MAXIOV)
1386 return -EINVAL;
1387 iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
1388 for (i = 0; i < nr_segs; i++) {
1389 struct compat_iovec v;
1390 if (get_user(v.iov_base, &iov32[i].iov_base) ||
1391 get_user(v.iov_len, &iov32[i].iov_len) ||
1392 put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
1393 put_user(v.iov_len, &iov[i].iov_len))
1394 return -EFAULT;
1395 }
1396 return sys_vmsplice(fd, iov, nr_segs, flags);
1397}
1398#endif
1399
1400SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1401 int, fd_out, loff_t __user *, off_out,
1402 size_t, len, unsigned int, flags)
1403{
1404 struct fd in, out;
1405 long error;
1406
1407 if (unlikely(!len))
1408 return 0;
1409
1410 error = -EBADF;
1411 in = fdget(fd_in);
1412 if (in.file) {
1413 if (in.file->f_mode & FMODE_READ) {
1414 out = fdget(fd_out);
1415 if (out.file) {
1416 if (out.file->f_mode & FMODE_WRITE)
1417 error = do_splice(in.file, off_in,
1418 out.file, off_out,
1419 len, flags);
1420 fdput(out);
1421 }
1422 }
1423 fdput(in);
1424 }
1425 return error;
1426}
1427
1428/*
1429 * Make sure there's data to read. Wait for input if we can, otherwise
1430 * return an appropriate error.
1431 */
1432static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1433{
1434 int ret;
1435
1436 /*
1437 * Check ->nrbufs without the inode lock first. This function
1438 * is speculative anyways, so missing one is ok.
1439 */
1440 if (pipe->nrbufs)
1441 return 0;
1442
1443 ret = 0;
1444 pipe_lock(pipe);
1445
1446 while (!pipe->nrbufs) {
1447 if (signal_pending(current)) {
1448 ret = -ERESTARTSYS;
1449 break;
1450 }
1451 if (!pipe->writers)
1452 break;
1453 if (!pipe->waiting_writers) {
1454 if (flags & SPLICE_F_NONBLOCK) {
1455 ret = -EAGAIN;
1456 break;
1457 }
1458 }
1459 pipe_wait(pipe);
1460 }
1461
1462 pipe_unlock(pipe);
1463 return ret;
1464}
1465
1466/*
1467 * Make sure there's writeable room. Wait for room if we can, otherwise
1468 * return an appropriate error.
1469 */
1470static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1471{
1472 int ret;
1473
1474 /*
1475 * Check ->nrbufs without the inode lock first. This function
1476 * is speculative anyways, so missing one is ok.
1477 */
1478 if (pipe->nrbufs < pipe->buffers)
1479 return 0;
1480
1481 ret = 0;
1482 pipe_lock(pipe);
1483
1484 while (pipe->nrbufs >= pipe->buffers) {
1485 if (!pipe->readers) {
1486 send_sig(SIGPIPE, current, 0);
1487 ret = -EPIPE;
1488 break;
1489 }
1490 if (flags & SPLICE_F_NONBLOCK) {
1491 ret = -EAGAIN;
1492 break;
1493 }
1494 if (signal_pending(current)) {
1495 ret = -ERESTARTSYS;
1496 break;
1497 }
1498 pipe->waiting_writers++;
1499 pipe_wait(pipe);
1500 pipe->waiting_writers--;
1501 }
1502
1503 pipe_unlock(pipe);
1504 return ret;
1505}
1506
1507/*
1508 * Splice contents of ipipe to opipe.
1509 */
1510static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1511 struct pipe_inode_info *opipe,
1512 size_t len, unsigned int flags)
1513{
1514 struct pipe_buffer *ibuf, *obuf;
1515 int ret = 0, nbuf;
1516 bool input_wakeup = false;
1517
1518
1519retry:
1520 ret = ipipe_prep(ipipe, flags);
1521 if (ret)
1522 return ret;
1523
1524 ret = opipe_prep(opipe, flags);
1525 if (ret)
1526 return ret;
1527
1528 /*
1529 * Potential ABBA deadlock, work around it by ordering lock
1530 * grabbing by pipe info address. Otherwise two different processes
1531 * could deadlock (one doing tee from A -> B, the other from B -> A).
1532 */
1533 pipe_double_lock(ipipe, opipe);
1534
1535 do {
1536 if (!opipe->readers) {
1537 send_sig(SIGPIPE, current, 0);
1538 if (!ret)
1539 ret = -EPIPE;
1540 break;
1541 }
1542
1543 if (!ipipe->nrbufs && !ipipe->writers)
1544 break;
1545
1546 /*
1547 * Cannot make any progress, because either the input
1548 * pipe is empty or the output pipe is full.
1549 */
1550 if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
1551 /* Already processed some buffers, break */
1552 if (ret)
1553 break;
1554
1555 if (flags & SPLICE_F_NONBLOCK) {
1556 ret = -EAGAIN;
1557 break;
1558 }
1559
1560 /*
1561 * We raced with another reader/writer and haven't
1562 * managed to process any buffers. A zero return
1563 * value means EOF, so retry instead.
1564 */
1565 pipe_unlock(ipipe);
1566 pipe_unlock(opipe);
1567 goto retry;
1568 }
1569
1570 ibuf = ipipe->bufs + ipipe->curbuf;
1571 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
1572 obuf = opipe->bufs + nbuf;
1573
1574 if (len >= ibuf->len) {
1575 /*
1576 * Simply move the whole buffer from ipipe to opipe
1577 */
1578 *obuf = *ibuf;
1579 ibuf->ops = NULL;
1580 opipe->nrbufs++;
1581 ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
1582 ipipe->nrbufs--;
1583 input_wakeup = true;
1584 } else {
1585 /*
1586 * Get a reference to this pipe buffer,
1587 * so we can copy the contents over.
1588 */
1589 pipe_buf_get(ipipe, ibuf);
1590 *obuf = *ibuf;
1591
1592 /*
1593 * Don't inherit the gift flag, we need to
1594 * prevent multiple steals of this page.
1595 */
1596 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1597
1598 obuf->len = len;
1599 opipe->nrbufs++;
1600 ibuf->offset += obuf->len;
1601 ibuf->len -= obuf->len;
1602 }
1603 ret += obuf->len;
1604 len -= obuf->len;
1605 } while (len);
1606
1607 pipe_unlock(ipipe);
1608 pipe_unlock(opipe);
1609
1610 /*
1611 * If we put data in the output pipe, wakeup any potential readers.
1612 */
1613 if (ret > 0)
1614 wakeup_pipe_readers(opipe);
1615
1616 if (input_wakeup)
1617 wakeup_pipe_writers(ipipe);
1618
1619 return ret;
1620}
1621
1622/*
1623 * Link contents of ipipe to opipe.
1624 */
1625static int link_pipe(struct pipe_inode_info *ipipe,
1626 struct pipe_inode_info *opipe,
1627 size_t len, unsigned int flags)
1628{
1629 struct pipe_buffer *ibuf, *obuf;
1630 int ret = 0, i = 0, nbuf;
1631
1632 /*
1633 * Potential ABBA deadlock, work around it by ordering lock
1634 * grabbing by pipe info address. Otherwise two different processes
1635 * could deadlock (one doing tee from A -> B, the other from B -> A).
1636 */
1637 pipe_double_lock(ipipe, opipe);
1638
1639 do {
1640 if (!opipe->readers) {
1641 send_sig(SIGPIPE, current, 0);
1642 if (!ret)
1643 ret = -EPIPE;
1644 break;
1645 }
1646
1647 /*
1648 * If we have iterated all input buffers or ran out of
1649 * output room, break.
1650 */
1651 if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
1652 break;
1653
1654 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
1655 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
1656
1657 /*
1658 * Get a reference to this pipe buffer,
1659 * so we can copy the contents over.
1660 */
1661 pipe_buf_get(ipipe, ibuf);
1662
1663 obuf = opipe->bufs + nbuf;
1664 *obuf = *ibuf;
1665
1666 /*
1667 * Don't inherit the gift flag, we need to
1668 * prevent multiple steals of this page.
1669 */
1670 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1671
1672 if (obuf->len > len)
1673 obuf->len = len;
1674
1675 opipe->nrbufs++;
1676 ret += obuf->len;
1677 len -= obuf->len;
1678 i++;
1679 } while (len);
1680
1681 /*
1682 * return EAGAIN if we have the potential of some data in the
1683 * future, otherwise just return 0
1684 */
1685 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1686 ret = -EAGAIN;
1687
1688 pipe_unlock(ipipe);
1689 pipe_unlock(opipe);
1690
1691 /*
1692 * If we put data in the output pipe, wakeup any potential readers.
1693 */
1694 if (ret > 0)
1695 wakeup_pipe_readers(opipe);
1696
1697 return ret;
1698}
1699
1700/*
1701 * This is a tee(1) implementation that works on pipes. It doesn't copy
1702 * any data, it simply references the 'in' pages on the 'out' pipe.
1703 * The 'flags' used are the SPLICE_F_* variants, currently the only
1704 * applicable one is SPLICE_F_NONBLOCK.
1705 */
1706static long do_tee(struct file *in, struct file *out, size_t len,
1707 unsigned int flags)
1708{
1709 struct pipe_inode_info *ipipe = get_pipe_info(in);
1710 struct pipe_inode_info *opipe = get_pipe_info(out);
1711 int ret = -EINVAL;
1712
1713 /*
1714 * Duplicate the contents of ipipe to opipe without actually
1715 * copying the data.
1716 */
1717 if (ipipe && opipe && ipipe != opipe) {
1718 /*
1719 * Keep going, unless we encounter an error. The ipipe/opipe
1720 * ordering doesn't really matter.
1721 */
1722 ret = ipipe_prep(ipipe, flags);
1723 if (!ret) {
1724 ret = opipe_prep(opipe, flags);
1725 if (!ret)
1726 ret = link_pipe(ipipe, opipe, len, flags);
1727 }
1728 }
1729
1730 return ret;
1731}
1732
1733SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
1734{
1735 struct fd in;
1736 int error;
1737
1738 if (unlikely(!len))
1739 return 0;
1740
1741 error = -EBADF;
1742 in = fdget(fdin);
1743 if (in.file) {
1744 if (in.file->f_mode & FMODE_READ) {
1745 struct fd out = fdget(fdout);
1746 if (out.file) {
1747 if (out.file->f_mode & FMODE_WRITE)
1748 error = do_tee(in.file, out.file,
1749 len, flags);
1750 fdput(out);
1751 }
1752 }
1753 fdput(in);
1754 }
1755
1756 return error;
1757}