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Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux
[mirror_ubuntu-zesty-kernel.git] / fs / splice.c
CommitLineData
5274f052
JA
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
c2058e06
JA
12 * Jens to support splicing to files, network, direct splicing, etc and
13 * fixing lots of bugs.
5274f052 14 *
0fe23479 15 * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
c2058e06
JA
16 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
17 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
5274f052
JA
18 *
19 */
20#include <linux/fs.h>
21#include <linux/file.h>
22#include <linux/pagemap.h>
d6b29d7c 23#include <linux/splice.h>
08e552c6 24#include <linux/memcontrol.h>
5274f052 25#include <linux/mm_inline.h>
5abc97aa 26#include <linux/swap.h>
4f6f0bd2 27#include <linux/writeback.h>
630d9c47 28#include <linux/export.h>
4f6f0bd2 29#include <linux/syscalls.h>
912d35f8 30#include <linux/uio.h>
29ce2058 31#include <linux/security.h>
5a0e3ad6 32#include <linux/gfp.h>
35f9c09f 33#include <linux/socket.h>
76b021d0 34#include <linux/compat.h>
8d020765 35#include <linux/aio.h>
06ae43f3 36#include "internal.h"
5274f052 37
83f9135b
JA
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 */
76ad4d11 44static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
5abc97aa
JA
45 struct pipe_buffer *buf)
46{
47 struct page *page = buf->page;
9e94cd4f 48 struct address_space *mapping;
5abc97aa 49
9e0267c2
JA
50 lock_page(page);
51
9e94cd4f
JA
52 mapping = page_mapping(page);
53 if (mapping) {
54 WARN_ON(!PageUptodate(page));
5abc97aa 55
9e94cd4f
JA
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);
ad8d6f0a 65
266cf658
DH
66 if (page_has_private(page) &&
67 !try_to_release_page(page, GFP_KERNEL))
ca39d651 68 goto out_unlock;
4f6f0bd2 69
9e94cd4f
JA
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 }
9e0267c2 78 }
5abc97aa 79
9e94cd4f
JA
80 /*
81 * Raced with truncate or failed to remove page from current
82 * address space, unlock and return failure.
83 */
ca39d651 84out_unlock:
9e94cd4f
JA
85 unlock_page(page);
86 return 1;
5abc97aa
JA
87}
88
76ad4d11 89static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
5274f052
JA
90 struct pipe_buffer *buf)
91{
92 page_cache_release(buf->page);
1432873a 93 buf->flags &= ~PIPE_BUF_FLAG_LRU;
5274f052
JA
94}
95
0845718d
JA
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 */
cac36bb0
JA
100static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
101 struct pipe_buffer *buf)
5274f052
JA
102{
103 struct page *page = buf->page;
49d0b21b 104 int err;
5274f052
JA
105
106 if (!PageUptodate(page)) {
49d0b21b
JA
107 lock_page(page);
108
109 /*
110 * Page got truncated/unhashed. This will cause a 0-byte
73d62d83 111 * splice, if this is the first page.
49d0b21b
JA
112 */
113 if (!page->mapping) {
114 err = -ENODATA;
115 goto error;
116 }
5274f052 117
49d0b21b 118 /*
73d62d83 119 * Uh oh, read-error from disk.
49d0b21b
JA
120 */
121 if (!PageUptodate(page)) {
122 err = -EIO;
123 goto error;
124 }
125
126 /*
f84d7519 127 * Page is ok afterall, we are done.
49d0b21b 128 */
5274f052 129 unlock_page(page);
5274f052
JA
130 }
131
f84d7519 132 return 0;
49d0b21b
JA
133error:
134 unlock_page(page);
f84d7519 135 return err;
70524490
JA
136}
137
708e3508 138const struct pipe_buf_operations page_cache_pipe_buf_ops = {
5274f052 139 .can_merge = 0,
cac36bb0 140 .confirm = page_cache_pipe_buf_confirm,
5274f052 141 .release = page_cache_pipe_buf_release,
5abc97aa 142 .steal = page_cache_pipe_buf_steal,
f84d7519 143 .get = generic_pipe_buf_get,
5274f052
JA
144};
145
912d35f8
JA
146static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
147 struct pipe_buffer *buf)
148{
7afa6fd0
JA
149 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
150 return 1;
151
1432873a 152 buf->flags |= PIPE_BUF_FLAG_LRU;
330ab716 153 return generic_pipe_buf_steal(pipe, buf);
912d35f8
JA
154}
155
d4c3cca9 156static const struct pipe_buf_operations user_page_pipe_buf_ops = {
912d35f8 157 .can_merge = 0,
cac36bb0 158 .confirm = generic_pipe_buf_confirm,
912d35f8
JA
159 .release = page_cache_pipe_buf_release,
160 .steal = user_page_pipe_buf_steal,
f84d7519 161 .get = generic_pipe_buf_get,
912d35f8
JA
162};
163
825cdcb1
NK
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
932cc6d4
JA
172/**
173 * splice_to_pipe - fill passed data into a pipe
174 * @pipe: pipe to fill
175 * @spd: data to fill
176 *
177 * Description:
79685b8d 178 * @spd contains a map of pages and len/offset tuples, along with
932cc6d4
JA
179 * the struct pipe_buf_operations associated with these pages. This
180 * function will link that data to the pipe.
181 *
83f9135b 182 */
d6b29d7c
JA
183ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
184 struct splice_pipe_desc *spd)
5274f052 185{
00de00bd 186 unsigned int spd_pages = spd->nr_pages;
912d35f8 187 int ret, do_wakeup, page_nr;
5274f052
JA
188
189 ret = 0;
190 do_wakeup = 0;
912d35f8 191 page_nr = 0;
5274f052 192
61e0d47c 193 pipe_lock(pipe);
5274f052 194
5274f052 195 for (;;) {
3a326a2c 196 if (!pipe->readers) {
5274f052
JA
197 send_sig(SIGPIPE, current, 0);
198 if (!ret)
199 ret = -EPIPE;
200 break;
201 }
202
35f3d14d
JA
203 if (pipe->nrbufs < pipe->buffers) {
204 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
3a326a2c 205 struct pipe_buffer *buf = pipe->bufs + newbuf;
5274f052 206
912d35f8
JA
207 buf->page = spd->pages[page_nr];
208 buf->offset = spd->partial[page_nr].offset;
209 buf->len = spd->partial[page_nr].len;
497f9625 210 buf->private = spd->partial[page_nr].private;
912d35f8 211 buf->ops = spd->ops;
7afa6fd0
JA
212 if (spd->flags & SPLICE_F_GIFT)
213 buf->flags |= PIPE_BUF_FLAG_GIFT;
214
6f767b04 215 pipe->nrbufs++;
912d35f8
JA
216 page_nr++;
217 ret += buf->len;
218
6447a3cf 219 if (pipe->files)
6f767b04 220 do_wakeup = 1;
5274f052 221
912d35f8 222 if (!--spd->nr_pages)
5274f052 223 break;
35f3d14d 224 if (pipe->nrbufs < pipe->buffers)
5274f052
JA
225 continue;
226
227 break;
228 }
229
912d35f8 230 if (spd->flags & SPLICE_F_NONBLOCK) {
29e35094
LT
231 if (!ret)
232 ret = -EAGAIN;
233 break;
234 }
235
5274f052
JA
236 if (signal_pending(current)) {
237 if (!ret)
238 ret = -ERESTARTSYS;
239 break;
240 }
241
242 if (do_wakeup) {
c0bd1f65 243 smp_mb();
3a326a2c
IM
244 if (waitqueue_active(&pipe->wait))
245 wake_up_interruptible_sync(&pipe->wait);
246 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
5274f052
JA
247 do_wakeup = 0;
248 }
249
3a326a2c
IM
250 pipe->waiting_writers++;
251 pipe_wait(pipe);
252 pipe->waiting_writers--;
5274f052
JA
253 }
254
61e0d47c 255 pipe_unlock(pipe);
5274f052 256
825cdcb1
NK
257 if (do_wakeup)
258 wakeup_pipe_readers(pipe);
5274f052 259
00de00bd 260 while (page_nr < spd_pages)
bbdfc2f7 261 spd->spd_release(spd, page_nr++);
5274f052
JA
262
263 return ret;
264}
265
708e3508 266void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
bbdfc2f7
JA
267{
268 page_cache_release(spd->pages[i]);
269}
270
35f3d14d
JA
271/*
272 * Check if we need to grow the arrays holding pages and partial page
273 * descriptions.
274 */
047fe360 275int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
35f3d14d 276{
047fe360
ED
277 unsigned int buffers = ACCESS_ONCE(pipe->buffers);
278
279 spd->nr_pages_max = buffers;
280 if (buffers <= PIPE_DEF_BUFFERS)
35f3d14d
JA
281 return 0;
282
047fe360
ED
283 spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
284 spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
35f3d14d
JA
285
286 if (spd->pages && spd->partial)
287 return 0;
288
289 kfree(spd->pages);
290 kfree(spd->partial);
291 return -ENOMEM;
292}
293
047fe360 294void splice_shrink_spd(struct splice_pipe_desc *spd)
35f3d14d 295{
047fe360 296 if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
35f3d14d
JA
297 return;
298
299 kfree(spd->pages);
300 kfree(spd->partial);
301}
302
3a326a2c 303static int
cbb7e577
JA
304__generic_file_splice_read(struct file *in, loff_t *ppos,
305 struct pipe_inode_info *pipe, size_t len,
306 unsigned int flags)
5274f052
JA
307{
308 struct address_space *mapping = in->f_mapping;
d8983910 309 unsigned int loff, nr_pages, req_pages;
35f3d14d
JA
310 struct page *pages[PIPE_DEF_BUFFERS];
311 struct partial_page partial[PIPE_DEF_BUFFERS];
5274f052 312 struct page *page;
91ad66ef
JA
313 pgoff_t index, end_index;
314 loff_t isize;
eb20796b 315 int error, page_nr;
912d35f8
JA
316 struct splice_pipe_desc spd = {
317 .pages = pages,
318 .partial = partial,
047fe360 319 .nr_pages_max = PIPE_DEF_BUFFERS,
912d35f8
JA
320 .flags = flags,
321 .ops = &page_cache_pipe_buf_ops,
bbdfc2f7 322 .spd_release = spd_release_page,
912d35f8 323 };
5274f052 324
35f3d14d
JA
325 if (splice_grow_spd(pipe, &spd))
326 return -ENOMEM;
327
cbb7e577 328 index = *ppos >> PAGE_CACHE_SHIFT;
912d35f8 329 loff = *ppos & ~PAGE_CACHE_MASK;
d8983910 330 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
047fe360 331 nr_pages = min(req_pages, spd.nr_pages_max);
5274f052 332
eb20796b
JA
333 /*
334 * Lookup the (hopefully) full range of pages we need.
335 */
35f3d14d 336 spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages);
431a4820 337 index += spd.nr_pages;
82aa5d61 338
eb20796b
JA
339 /*
340 * If find_get_pages_contig() returned fewer pages than we needed,
431a4820 341 * readahead/allocate the rest and fill in the holes.
eb20796b 342 */
431a4820 343 if (spd.nr_pages < nr_pages)
cf914a7d
RR
344 page_cache_sync_readahead(mapping, &in->f_ra, in,
345 index, req_pages - spd.nr_pages);
431a4820 346
932cc6d4 347 error = 0;
eb20796b 348 while (spd.nr_pages < nr_pages) {
82aa5d61 349 /*
eb20796b
JA
350 * Page could be there, find_get_pages_contig() breaks on
351 * the first hole.
5274f052 352 */
7480a904
JA
353 page = find_get_page(mapping, index);
354 if (!page) {
7480a904 355 /*
eb20796b 356 * page didn't exist, allocate one.
7480a904
JA
357 */
358 page = page_cache_alloc_cold(mapping);
359 if (!page)
360 break;
361
362 error = add_to_page_cache_lru(page, mapping, index,
0ae0b5d0 363 GFP_KERNEL);
7480a904
JA
364 if (unlikely(error)) {
365 page_cache_release(page);
a0548871
JA
366 if (error == -EEXIST)
367 continue;
7480a904
JA
368 break;
369 }
eb20796b
JA
370 /*
371 * add_to_page_cache() locks the page, unlock it
372 * to avoid convoluting the logic below even more.
373 */
374 unlock_page(page);
7480a904
JA
375 }
376
35f3d14d 377 spd.pages[spd.nr_pages++] = page;
eb20796b
JA
378 index++;
379 }
380
381 /*
382 * Now loop over the map and see if we need to start IO on any
383 * pages, fill in the partial map, etc.
384 */
385 index = *ppos >> PAGE_CACHE_SHIFT;
386 nr_pages = spd.nr_pages;
387 spd.nr_pages = 0;
388 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
389 unsigned int this_len;
390
391 if (!len)
392 break;
393
394 /*
395 * this_len is the max we'll use from this page
396 */
397 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
35f3d14d 398 page = spd.pages[page_nr];
eb20796b 399
a08a166f 400 if (PageReadahead(page))
cf914a7d 401 page_cache_async_readahead(mapping, &in->f_ra, in,
d8983910 402 page, index, req_pages - page_nr);
a08a166f 403
7480a904
JA
404 /*
405 * If the page isn't uptodate, we may need to start io on it
406 */
407 if (!PageUptodate(page)) {
6965031d 408 lock_page(page);
7480a904
JA
409
410 /*
32502b84
MS
411 * Page was truncated, or invalidated by the
412 * filesystem. Redo the find/create, but this time the
413 * page is kept locked, so there's no chance of another
414 * race with truncate/invalidate.
7480a904
JA
415 */
416 if (!page->mapping) {
417 unlock_page(page);
32502b84
MS
418 page = find_or_create_page(mapping, index,
419 mapping_gfp_mask(mapping));
420
421 if (!page) {
422 error = -ENOMEM;
423 break;
424 }
35f3d14d
JA
425 page_cache_release(spd.pages[page_nr]);
426 spd.pages[page_nr] = page;
7480a904
JA
427 }
428 /*
429 * page was already under io and is now done, great
430 */
431 if (PageUptodate(page)) {
432 unlock_page(page);
433 goto fill_it;
434 }
5274f052 435
7480a904
JA
436 /*
437 * need to read in the page
438 */
439 error = mapping->a_ops->readpage(in, page);
5274f052 440 if (unlikely(error)) {
eb20796b
JA
441 /*
442 * We really should re-lookup the page here,
443 * but it complicates things a lot. Instead
444 * lets just do what we already stored, and
445 * we'll get it the next time we are called.
446 */
7480a904 447 if (error == AOP_TRUNCATED_PAGE)
eb20796b
JA
448 error = 0;
449
5274f052
JA
450 break;
451 }
620a324b
JA
452 }
453fill_it:
454 /*
455 * i_size must be checked after PageUptodate.
456 */
457 isize = i_size_read(mapping->host);
458 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
459 if (unlikely(!isize || index > end_index))
460 break;
461
462 /*
463 * if this is the last page, see if we need to shrink
464 * the length and stop
465 */
466 if (end_index == index) {
467 unsigned int plen;
91ad66ef
JA
468
469 /*
620a324b 470 * max good bytes in this page
91ad66ef 471 */
620a324b
JA
472 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
473 if (plen <= loff)
91ad66ef 474 break;
91ad66ef
JA
475
476 /*
620a324b 477 * force quit after adding this page
91ad66ef 478 */
620a324b
JA
479 this_len = min(this_len, plen - loff);
480 len = this_len;
5274f052 481 }
620a324b 482
35f3d14d
JA
483 spd.partial[page_nr].offset = loff;
484 spd.partial[page_nr].len = this_len;
82aa5d61 485 len -= this_len;
91ad66ef 486 loff = 0;
eb20796b
JA
487 spd.nr_pages++;
488 index++;
5274f052
JA
489 }
490
eb20796b 491 /*
475ecade 492 * Release any pages at the end, if we quit early. 'page_nr' is how far
eb20796b
JA
493 * we got, 'nr_pages' is how many pages are in the map.
494 */
495 while (page_nr < nr_pages)
35f3d14d 496 page_cache_release(spd.pages[page_nr++]);
f4e6b498 497 in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
eb20796b 498
912d35f8 499 if (spd.nr_pages)
35f3d14d 500 error = splice_to_pipe(pipe, &spd);
5274f052 501
047fe360 502 splice_shrink_spd(&spd);
7480a904 503 return error;
5274f052
JA
504}
505
83f9135b
JA
506/**
507 * generic_file_splice_read - splice data from file to a pipe
508 * @in: file to splice from
932cc6d4 509 * @ppos: position in @in
83f9135b
JA
510 * @pipe: pipe to splice to
511 * @len: number of bytes to splice
512 * @flags: splice modifier flags
513 *
932cc6d4
JA
514 * Description:
515 * Will read pages from given file and fill them into a pipe. Can be
516 * used as long as the address_space operations for the source implements
517 * a readpage() hook.
518 *
83f9135b 519 */
cbb7e577
JA
520ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
521 struct pipe_inode_info *pipe, size_t len,
522 unsigned int flags)
5274f052 523{
d366d398 524 loff_t isize, left;
8191ecd1 525 int ret;
d366d398
JA
526
527 isize = i_size_read(in->f_mapping->host);
528 if (unlikely(*ppos >= isize))
529 return 0;
530
531 left = isize - *ppos;
532 if (unlikely(left < len))
533 len = left;
5274f052 534
8191ecd1 535 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
723590ed 536 if (ret > 0) {
cbb7e577 537 *ppos += ret;
723590ed
MS
538 file_accessed(in);
539 }
5274f052
JA
540
541 return ret;
542}
059a8f37
JA
543EXPORT_SYMBOL(generic_file_splice_read);
544
6818173b
MS
545static const struct pipe_buf_operations default_pipe_buf_ops = {
546 .can_merge = 0,
6818173b
MS
547 .confirm = generic_pipe_buf_confirm,
548 .release = generic_pipe_buf_release,
549 .steal = generic_pipe_buf_steal,
550 .get = generic_pipe_buf_get,
551};
552
28a625cb
MS
553static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
554 struct pipe_buffer *buf)
555{
556 return 1;
557}
558
559/* Pipe buffer operations for a socket and similar. */
560const struct pipe_buf_operations nosteal_pipe_buf_ops = {
561 .can_merge = 0,
28a625cb
MS
562 .confirm = generic_pipe_buf_confirm,
563 .release = generic_pipe_buf_release,
564 .steal = generic_pipe_buf_nosteal,
565 .get = generic_pipe_buf_get,
566};
567EXPORT_SYMBOL(nosteal_pipe_buf_ops);
568
6818173b
MS
569static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
570 unsigned long vlen, loff_t offset)
571{
572 mm_segment_t old_fs;
573 loff_t pos = offset;
574 ssize_t res;
575
576 old_fs = get_fs();
577 set_fs(get_ds());
578 /* The cast to a user pointer is valid due to the set_fs() */
579 res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos);
580 set_fs(old_fs);
581
582 return res;
583}
584
7bb307e8 585ssize_t kernel_write(struct file *file, const char *buf, size_t count,
b2858d7d 586 loff_t pos)
0b0a47f5
MS
587{
588 mm_segment_t old_fs;
589 ssize_t res;
590
591 old_fs = get_fs();
592 set_fs(get_ds());
593 /* The cast to a user pointer is valid due to the set_fs() */
7bb307e8 594 res = vfs_write(file, (__force const char __user *)buf, count, &pos);
0b0a47f5
MS
595 set_fs(old_fs);
596
597 return res;
598}
7bb307e8 599EXPORT_SYMBOL(kernel_write);
0b0a47f5 600
6818173b
MS
601ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
602 struct pipe_inode_info *pipe, size_t len,
603 unsigned int flags)
604{
605 unsigned int nr_pages;
606 unsigned int nr_freed;
607 size_t offset;
35f3d14d
JA
608 struct page *pages[PIPE_DEF_BUFFERS];
609 struct partial_page partial[PIPE_DEF_BUFFERS];
610 struct iovec *vec, __vec[PIPE_DEF_BUFFERS];
6818173b
MS
611 ssize_t res;
612 size_t this_len;
613 int error;
614 int i;
615 struct splice_pipe_desc spd = {
616 .pages = pages,
617 .partial = partial,
047fe360 618 .nr_pages_max = PIPE_DEF_BUFFERS,
6818173b
MS
619 .flags = flags,
620 .ops = &default_pipe_buf_ops,
621 .spd_release = spd_release_page,
622 };
623
35f3d14d
JA
624 if (splice_grow_spd(pipe, &spd))
625 return -ENOMEM;
626
627 res = -ENOMEM;
628 vec = __vec;
047fe360
ED
629 if (spd.nr_pages_max > PIPE_DEF_BUFFERS) {
630 vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL);
35f3d14d
JA
631 if (!vec)
632 goto shrink_ret;
633 }
634
6818173b
MS
635 offset = *ppos & ~PAGE_CACHE_MASK;
636 nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
637
047fe360 638 for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) {
6818173b
MS
639 struct page *page;
640
4f231228 641 page = alloc_page(GFP_USER);
6818173b
MS
642 error = -ENOMEM;
643 if (!page)
644 goto err;
645
646 this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset);
4f231228 647 vec[i].iov_base = (void __user *) page_address(page);
6818173b 648 vec[i].iov_len = this_len;
35f3d14d 649 spd.pages[i] = page;
6818173b
MS
650 spd.nr_pages++;
651 len -= this_len;
652 offset = 0;
653 }
654
655 res = kernel_readv(in, vec, spd.nr_pages, *ppos);
77f6bf57
AM
656 if (res < 0) {
657 error = res;
6818173b 658 goto err;
77f6bf57 659 }
6818173b
MS
660
661 error = 0;
662 if (!res)
663 goto err;
664
665 nr_freed = 0;
666 for (i = 0; i < spd.nr_pages; i++) {
6818173b 667 this_len = min_t(size_t, vec[i].iov_len, res);
35f3d14d
JA
668 spd.partial[i].offset = 0;
669 spd.partial[i].len = this_len;
6818173b 670 if (!this_len) {
35f3d14d
JA
671 __free_page(spd.pages[i]);
672 spd.pages[i] = NULL;
6818173b
MS
673 nr_freed++;
674 }
675 res -= this_len;
676 }
677 spd.nr_pages -= nr_freed;
678
679 res = splice_to_pipe(pipe, &spd);
680 if (res > 0)
681 *ppos += res;
682
35f3d14d
JA
683shrink_ret:
684 if (vec != __vec)
685 kfree(vec);
047fe360 686 splice_shrink_spd(&spd);
6818173b
MS
687 return res;
688
689err:
4f231228 690 for (i = 0; i < spd.nr_pages; i++)
35f3d14d 691 __free_page(spd.pages[i]);
4f231228 692
35f3d14d
JA
693 res = error;
694 goto shrink_ret;
6818173b
MS
695}
696EXPORT_SYMBOL(default_file_splice_read);
697
5274f052 698/*
4f6f0bd2 699 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
016b661e 700 * using sendpage(). Return the number of bytes sent.
5274f052 701 */
76ad4d11 702static int pipe_to_sendpage(struct pipe_inode_info *pipe,
5274f052
JA
703 struct pipe_buffer *buf, struct splice_desc *sd)
704{
6a14b90b 705 struct file *file = sd->u.file;
5274f052 706 loff_t pos = sd->pos;
a8adbe37 707 int more;
5274f052 708
72c2d531 709 if (!likely(file->f_op->sendpage))
a8adbe37
MM
710 return -EINVAL;
711
35f9c09f 712 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
ae62ca7b
ED
713
714 if (sd->len < sd->total_len && pipe->nrbufs > 1)
35f9c09f 715 more |= MSG_SENDPAGE_NOTLAST;
ae62ca7b 716
a8adbe37
MM
717 return file->f_op->sendpage(file, buf->page, buf->offset,
718 sd->len, &pos, more);
5274f052
JA
719}
720
b3c2d2dd
MS
721static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
722{
723 smp_mb();
724 if (waitqueue_active(&pipe->wait))
725 wake_up_interruptible(&pipe->wait);
726 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
727}
728
932cc6d4 729/**
b3c2d2dd 730 * splice_from_pipe_feed - feed available data from a pipe to a file
932cc6d4
JA
731 * @pipe: pipe to splice from
732 * @sd: information to @actor
733 * @actor: handler that splices the data
734 *
735 * Description:
b3c2d2dd
MS
736 * This function loops over the pipe and calls @actor to do the
737 * actual moving of a single struct pipe_buffer to the desired
738 * destination. It returns when there's no more buffers left in
739 * the pipe or if the requested number of bytes (@sd->total_len)
740 * have been copied. It returns a positive number (one) if the
741 * pipe needs to be filled with more data, zero if the required
742 * number of bytes have been copied and -errno on error.
932cc6d4 743 *
b3c2d2dd
MS
744 * This, together with splice_from_pipe_{begin,end,next}, may be
745 * used to implement the functionality of __splice_from_pipe() when
746 * locking is required around copying the pipe buffers to the
747 * destination.
83f9135b 748 */
96f9bc8f 749static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
b3c2d2dd 750 splice_actor *actor)
5274f052 751{
b3c2d2dd 752 int ret;
5274f052 753
b3c2d2dd
MS
754 while (pipe->nrbufs) {
755 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
756 const struct pipe_buf_operations *ops = buf->ops;
5274f052 757
b3c2d2dd
MS
758 sd->len = buf->len;
759 if (sd->len > sd->total_len)
760 sd->len = sd->total_len;
5274f052 761
a8adbe37
MM
762 ret = buf->ops->confirm(pipe, buf);
763 if (unlikely(ret)) {
b3c2d2dd
MS
764 if (ret == -ENODATA)
765 ret = 0;
766 return ret;
767 }
a8adbe37
MM
768
769 ret = actor(pipe, buf, sd);
770 if (ret <= 0)
771 return ret;
772
b3c2d2dd
MS
773 buf->offset += ret;
774 buf->len -= ret;
775
776 sd->num_spliced += ret;
777 sd->len -= ret;
778 sd->pos += ret;
779 sd->total_len -= ret;
780
781 if (!buf->len) {
782 buf->ops = NULL;
783 ops->release(pipe, buf);
35f3d14d 784 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
b3c2d2dd 785 pipe->nrbufs--;
6447a3cf 786 if (pipe->files)
b3c2d2dd
MS
787 sd->need_wakeup = true;
788 }
5274f052 789
b3c2d2dd
MS
790 if (!sd->total_len)
791 return 0;
792 }
5274f052 793
b3c2d2dd
MS
794 return 1;
795}
5274f052 796
b3c2d2dd
MS
797/**
798 * splice_from_pipe_next - wait for some data to splice from
799 * @pipe: pipe to splice from
800 * @sd: information about the splice operation
801 *
802 * Description:
803 * This function will wait for some data and return a positive
804 * value (one) if pipe buffers are available. It will return zero
805 * or -errno if no more data needs to be spliced.
806 */
96f9bc8f 807static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
b3c2d2dd
MS
808{
809 while (!pipe->nrbufs) {
810 if (!pipe->writers)
811 return 0;
016b661e 812
b3c2d2dd
MS
813 if (!pipe->waiting_writers && sd->num_spliced)
814 return 0;
73d62d83 815
b3c2d2dd
MS
816 if (sd->flags & SPLICE_F_NONBLOCK)
817 return -EAGAIN;
5274f052 818
b3c2d2dd
MS
819 if (signal_pending(current))
820 return -ERESTARTSYS;
5274f052 821
b3c2d2dd
MS
822 if (sd->need_wakeup) {
823 wakeup_pipe_writers(pipe);
824 sd->need_wakeup = false;
5274f052
JA
825 }
826
b3c2d2dd
MS
827 pipe_wait(pipe);
828 }
29e35094 829
b3c2d2dd
MS
830 return 1;
831}
5274f052 832
b3c2d2dd
MS
833/**
834 * splice_from_pipe_begin - start splicing from pipe
b80901bb 835 * @sd: information about the splice operation
b3c2d2dd
MS
836 *
837 * Description:
838 * This function should be called before a loop containing
839 * splice_from_pipe_next() and splice_from_pipe_feed() to
840 * initialize the necessary fields of @sd.
841 */
96f9bc8f 842static void splice_from_pipe_begin(struct splice_desc *sd)
b3c2d2dd
MS
843{
844 sd->num_spliced = 0;
845 sd->need_wakeup = false;
846}
5274f052 847
b3c2d2dd
MS
848/**
849 * splice_from_pipe_end - finish splicing from pipe
850 * @pipe: pipe to splice from
851 * @sd: information about the splice operation
852 *
853 * Description:
854 * This function will wake up pipe writers if necessary. It should
855 * be called after a loop containing splice_from_pipe_next() and
856 * splice_from_pipe_feed().
857 */
96f9bc8f 858static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
b3c2d2dd
MS
859{
860 if (sd->need_wakeup)
861 wakeup_pipe_writers(pipe);
862}
5274f052 863
b3c2d2dd
MS
864/**
865 * __splice_from_pipe - splice data from a pipe to given actor
866 * @pipe: pipe to splice from
867 * @sd: information to @actor
868 * @actor: handler that splices the data
869 *
870 * Description:
871 * This function does little more than loop over the pipe and call
872 * @actor to do the actual moving of a single struct pipe_buffer to
873 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
874 * pipe_to_user.
875 *
876 */
877ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
878 splice_actor *actor)
879{
880 int ret;
5274f052 881
b3c2d2dd
MS
882 splice_from_pipe_begin(sd);
883 do {
884 ret = splice_from_pipe_next(pipe, sd);
885 if (ret > 0)
886 ret = splice_from_pipe_feed(pipe, sd, actor);
887 } while (ret > 0);
888 splice_from_pipe_end(pipe, sd);
889
890 return sd->num_spliced ? sd->num_spliced : ret;
5274f052 891}
40bee44e 892EXPORT_SYMBOL(__splice_from_pipe);
5274f052 893
932cc6d4
JA
894/**
895 * splice_from_pipe - splice data from a pipe to a file
896 * @pipe: pipe to splice from
897 * @out: file to splice to
898 * @ppos: position in @out
899 * @len: how many bytes to splice
900 * @flags: splice modifier flags
901 * @actor: handler that splices the data
902 *
903 * Description:
2933970b 904 * See __splice_from_pipe. This function locks the pipe inode,
932cc6d4
JA
905 * otherwise it's identical to __splice_from_pipe().
906 *
907 */
6da61809
MF
908ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
909 loff_t *ppos, size_t len, unsigned int flags,
910 splice_actor *actor)
911{
912 ssize_t ret;
c66ab6fa
JA
913 struct splice_desc sd = {
914 .total_len = len,
915 .flags = flags,
916 .pos = *ppos,
6a14b90b 917 .u.file = out,
c66ab6fa 918 };
6da61809 919
61e0d47c 920 pipe_lock(pipe);
c66ab6fa 921 ret = __splice_from_pipe(pipe, &sd, actor);
61e0d47c 922 pipe_unlock(pipe);
6da61809
MF
923
924 return ret;
925}
926
8d020765
AV
927/**
928 * iter_file_splice_write - splice data from a pipe to a file
929 * @pipe: pipe info
930 * @out: file to write to
931 * @ppos: position in @out
932 * @len: number of bytes to splice
933 * @flags: splice modifier flags
934 *
935 * Description:
936 * Will either move or copy pages (determined by @flags options) from
937 * the given pipe inode to the given file.
938 * This one is ->write_iter-based.
939 *
940 */
941ssize_t
942iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
943 loff_t *ppos, size_t len, unsigned int flags)
944{
945 struct splice_desc sd = {
946 .total_len = len,
947 .flags = flags,
948 .pos = *ppos,
949 .u.file = out,
950 };
951 int nbufs = pipe->buffers;
952 struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
953 GFP_KERNEL);
954 ssize_t ret;
955
956 if (unlikely(!array))
957 return -ENOMEM;
958
959 pipe_lock(pipe);
960
961 splice_from_pipe_begin(&sd);
962 while (sd.total_len) {
963 struct iov_iter from;
8d020765
AV
964 size_t left;
965 int n, idx;
966
967 ret = splice_from_pipe_next(pipe, &sd);
968 if (ret <= 0)
969 break;
970
971 if (unlikely(nbufs < pipe->buffers)) {
972 kfree(array);
973 nbufs = pipe->buffers;
974 array = kcalloc(nbufs, sizeof(struct bio_vec),
975 GFP_KERNEL);
976 if (!array) {
977 ret = -ENOMEM;
978 break;
979 }
980 }
981
982 /* build the vector */
983 left = sd.total_len;
984 for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) {
985 struct pipe_buffer *buf = pipe->bufs + idx;
986 size_t this_len = buf->len;
987
988 if (this_len > left)
989 this_len = left;
990
991 if (idx == pipe->buffers - 1)
992 idx = -1;
993
994 ret = buf->ops->confirm(pipe, buf);
995 if (unlikely(ret)) {
996 if (ret == -ENODATA)
997 ret = 0;
998 goto done;
999 }
1000
1001 array[n].bv_page = buf->page;
1002 array[n].bv_len = this_len;
1003 array[n].bv_offset = buf->offset;
1004 left -= this_len;
1005 }
1006
05afcb77
AV
1007 iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
1008 sd.total_len - left);
dbe4e192 1009 ret = vfs_iter_write(out, &from, &sd.pos);
8d020765
AV
1010 if (ret <= 0)
1011 break;
1012
1013 sd.num_spliced += ret;
1014 sd.total_len -= ret;
dbe4e192 1015 *ppos = sd.pos;
8d020765
AV
1016
1017 /* dismiss the fully eaten buffers, adjust the partial one */
1018 while (ret) {
1019 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
1020 if (ret >= buf->len) {
1021 const struct pipe_buf_operations *ops = buf->ops;
1022 ret -= buf->len;
1023 buf->len = 0;
1024 buf->ops = NULL;
1025 ops->release(pipe, buf);
1026 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
1027 pipe->nrbufs--;
1028 if (pipe->files)
1029 sd.need_wakeup = true;
1030 } else {
1031 buf->offset += ret;
1032 buf->len -= ret;
1033 ret = 0;
1034 }
1035 }
1036 }
1037done:
1038 kfree(array);
1039 splice_from_pipe_end(pipe, &sd);
1040
1041 pipe_unlock(pipe);
1042
1043 if (sd.num_spliced)
1044 ret = sd.num_spliced;
1045
1046 return ret;
1047}
1048
1049EXPORT_SYMBOL(iter_file_splice_write);
1050
b2858d7d
MS
1051static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1052 struct splice_desc *sd)
0b0a47f5 1053{
b2858d7d
MS
1054 int ret;
1055 void *data;
06ae43f3 1056 loff_t tmp = sd->pos;
b2858d7d 1057
fbb32750 1058 data = kmap(buf->page);
06ae43f3 1059 ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
fbb32750 1060 kunmap(buf->page);
b2858d7d
MS
1061
1062 return ret;
0b0a47f5
MS
1063}
1064
1065static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
1066 struct file *out, loff_t *ppos,
1067 size_t len, unsigned int flags)
1068{
b2858d7d 1069 ssize_t ret;
0b0a47f5 1070
b2858d7d
MS
1071 ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
1072 if (ret > 0)
1073 *ppos += ret;
0b0a47f5 1074
b2858d7d 1075 return ret;
0b0a47f5
MS
1076}
1077
83f9135b
JA
1078/**
1079 * generic_splice_sendpage - splice data from a pipe to a socket
932cc6d4 1080 * @pipe: pipe to splice from
83f9135b 1081 * @out: socket to write to
932cc6d4 1082 * @ppos: position in @out
83f9135b
JA
1083 * @len: number of bytes to splice
1084 * @flags: splice modifier flags
1085 *
932cc6d4
JA
1086 * Description:
1087 * Will send @len bytes from the pipe to a network socket. No data copying
1088 * is involved.
83f9135b
JA
1089 *
1090 */
3a326a2c 1091ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
cbb7e577 1092 loff_t *ppos, size_t len, unsigned int flags)
5274f052 1093{
00522fb4 1094 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
5274f052
JA
1095}
1096
059a8f37 1097EXPORT_SYMBOL(generic_splice_sendpage);
a0f06780 1098
83f9135b
JA
1099/*
1100 * Attempt to initiate a splice from pipe to file.
1101 */
3a326a2c 1102static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
cbb7e577 1103 loff_t *ppos, size_t len, unsigned int flags)
5274f052 1104{
0b0a47f5
MS
1105 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
1106 loff_t *, size_t, unsigned int);
5274f052 1107
72c2d531 1108 if (out->f_op->splice_write)
cc56f7de
CG
1109 splice_write = out->f_op->splice_write;
1110 else
0b0a47f5
MS
1111 splice_write = default_file_splice_write;
1112
500368f7 1113 return splice_write(pipe, out, ppos, len, flags);
5274f052
JA
1114}
1115
83f9135b
JA
1116/*
1117 * Attempt to initiate a splice from a file to a pipe.
1118 */
cbb7e577
JA
1119static long do_splice_to(struct file *in, loff_t *ppos,
1120 struct pipe_inode_info *pipe, size_t len,
1121 unsigned int flags)
5274f052 1122{
6818173b
MS
1123 ssize_t (*splice_read)(struct file *, loff_t *,
1124 struct pipe_inode_info *, size_t, unsigned int);
5274f052
JA
1125 int ret;
1126
49570e9b 1127 if (unlikely(!(in->f_mode & FMODE_READ)))
5274f052
JA
1128 return -EBADF;
1129
cbb7e577 1130 ret = rw_verify_area(READ, in, ppos, len);
5274f052
JA
1131 if (unlikely(ret < 0))
1132 return ret;
1133
72c2d531 1134 if (in->f_op->splice_read)
cc56f7de
CG
1135 splice_read = in->f_op->splice_read;
1136 else
6818173b
MS
1137 splice_read = default_file_splice_read;
1138
1139 return splice_read(in, ppos, pipe, len, flags);
5274f052
JA
1140}
1141
932cc6d4
JA
1142/**
1143 * splice_direct_to_actor - splices data directly between two non-pipes
1144 * @in: file to splice from
1145 * @sd: actor information on where to splice to
1146 * @actor: handles the data splicing
1147 *
1148 * Description:
1149 * This is a special case helper to splice directly between two
1150 * points, without requiring an explicit pipe. Internally an allocated
79685b8d 1151 * pipe is cached in the process, and reused during the lifetime of
932cc6d4
JA
1152 * that process.
1153 *
c66ab6fa
JA
1154 */
1155ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
1156 splice_direct_actor *actor)
b92ce558
JA
1157{
1158 struct pipe_inode_info *pipe;
1159 long ret, bytes;
1160 umode_t i_mode;
c66ab6fa
JA
1161 size_t len;
1162 int i, flags;
b92ce558
JA
1163
1164 /*
1165 * We require the input being a regular file, as we don't want to
1166 * randomly drop data for eg socket -> socket splicing. Use the
1167 * piped splicing for that!
1168 */
496ad9aa 1169 i_mode = file_inode(in)->i_mode;
b92ce558
JA
1170 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
1171 return -EINVAL;
1172
1173 /*
1174 * neither in nor out is a pipe, setup an internal pipe attached to
1175 * 'out' and transfer the wanted data from 'in' to 'out' through that
1176 */
1177 pipe = current->splice_pipe;
49570e9b 1178 if (unlikely(!pipe)) {
7bee130e 1179 pipe = alloc_pipe_info();
b92ce558
JA
1180 if (!pipe)
1181 return -ENOMEM;
1182
1183 /*
1184 * We don't have an immediate reader, but we'll read the stuff
00522fb4 1185 * out of the pipe right after the splice_to_pipe(). So set
b92ce558
JA
1186 * PIPE_READERS appropriately.
1187 */
1188 pipe->readers = 1;
1189
1190 current->splice_pipe = pipe;
1191 }
1192
1193 /*
73d62d83 1194 * Do the splice.
b92ce558
JA
1195 */
1196 ret = 0;
1197 bytes = 0;
c66ab6fa
JA
1198 len = sd->total_len;
1199 flags = sd->flags;
1200
1201 /*
1202 * Don't block on output, we have to drain the direct pipe.
1203 */
1204 sd->flags &= ~SPLICE_F_NONBLOCK;
b92ce558
JA
1205
1206 while (len) {
51a92c0f 1207 size_t read_len;
a82c53a0 1208 loff_t pos = sd->pos, prev_pos = pos;
b92ce558 1209
bcd4f3ac 1210 ret = do_splice_to(in, &pos, pipe, len, flags);
51a92c0f 1211 if (unlikely(ret <= 0))
b92ce558
JA
1212 goto out_release;
1213
1214 read_len = ret;
c66ab6fa 1215 sd->total_len = read_len;
b92ce558
JA
1216
1217 /*
1218 * NOTE: nonblocking mode only applies to the input. We
1219 * must not do the output in nonblocking mode as then we
1220 * could get stuck data in the internal pipe:
1221 */
c66ab6fa 1222 ret = actor(pipe, sd);
a82c53a0
TZ
1223 if (unlikely(ret <= 0)) {
1224 sd->pos = prev_pos;
b92ce558 1225 goto out_release;
a82c53a0 1226 }
b92ce558
JA
1227
1228 bytes += ret;
1229 len -= ret;
bcd4f3ac 1230 sd->pos = pos;
b92ce558 1231
a82c53a0
TZ
1232 if (ret < read_len) {
1233 sd->pos = prev_pos + ret;
51a92c0f 1234 goto out_release;
a82c53a0 1235 }
b92ce558
JA
1236 }
1237
9e97198d 1238done:
b92ce558 1239 pipe->nrbufs = pipe->curbuf = 0;
80848708 1240 file_accessed(in);
b92ce558
JA
1241 return bytes;
1242
1243out_release:
1244 /*
1245 * If we did an incomplete transfer we must release
1246 * the pipe buffers in question:
1247 */
35f3d14d 1248 for (i = 0; i < pipe->buffers; i++) {
b92ce558
JA
1249 struct pipe_buffer *buf = pipe->bufs + i;
1250
1251 if (buf->ops) {
1252 buf->ops->release(pipe, buf);
1253 buf->ops = NULL;
1254 }
1255 }
b92ce558 1256
9e97198d
JA
1257 if (!bytes)
1258 bytes = ret;
c66ab6fa 1259
9e97198d 1260 goto done;
c66ab6fa
JA
1261}
1262EXPORT_SYMBOL(splice_direct_to_actor);
1263
1264static int direct_splice_actor(struct pipe_inode_info *pipe,
1265 struct splice_desc *sd)
1266{
6a14b90b 1267 struct file *file = sd->u.file;
c66ab6fa 1268
7995bd28 1269 return do_splice_from(pipe, file, sd->opos, sd->total_len,
2cb4b05e 1270 sd->flags);
c66ab6fa
JA
1271}
1272
932cc6d4
JA
1273/**
1274 * do_splice_direct - splices data directly between two files
1275 * @in: file to splice from
1276 * @ppos: input file offset
1277 * @out: file to splice to
acdb37c3 1278 * @opos: output file offset
932cc6d4
JA
1279 * @len: number of bytes to splice
1280 * @flags: splice modifier flags
1281 *
1282 * Description:
1283 * For use by do_sendfile(). splice can easily emulate sendfile, but
1284 * doing it in the application would incur an extra system call
1285 * (splice in + splice out, as compared to just sendfile()). So this helper
1286 * can splice directly through a process-private pipe.
1287 *
1288 */
c66ab6fa 1289long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
7995bd28 1290 loff_t *opos, size_t len, unsigned int flags)
c66ab6fa
JA
1291{
1292 struct splice_desc sd = {
1293 .len = len,
1294 .total_len = len,
1295 .flags = flags,
1296 .pos = *ppos,
6a14b90b 1297 .u.file = out,
7995bd28 1298 .opos = opos,
c66ab6fa 1299 };
51a92c0f 1300 long ret;
c66ab6fa 1301
18c67cb9
AV
1302 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1303 return -EBADF;
1304
1305 if (unlikely(out->f_flags & O_APPEND))
1306 return -EINVAL;
1307
1308 ret = rw_verify_area(WRITE, out, opos, len);
1309 if (unlikely(ret < 0))
1310 return ret;
1311
c66ab6fa 1312 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
51a92c0f 1313 if (ret > 0)
a82c53a0 1314 *ppos = sd.pos;
51a92c0f 1315
c66ab6fa 1316 return ret;
b92ce558 1317}
1c118596 1318EXPORT_SYMBOL(do_splice_direct);
b92ce558 1319
7c77f0b3
MS
1320static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1321 struct pipe_inode_info *opipe,
1322 size_t len, unsigned int flags);
ddac0d39 1323
83f9135b
JA
1324/*
1325 * Determine where to splice to/from.
1326 */
529565dc
IM
1327static long do_splice(struct file *in, loff_t __user *off_in,
1328 struct file *out, loff_t __user *off_out,
1329 size_t len, unsigned int flags)
5274f052 1330{
7c77f0b3
MS
1331 struct pipe_inode_info *ipipe;
1332 struct pipe_inode_info *opipe;
7995bd28 1333 loff_t offset;
a4514ebd 1334 long ret;
5274f052 1335
71993e62
LT
1336 ipipe = get_pipe_info(in);
1337 opipe = get_pipe_info(out);
7c77f0b3
MS
1338
1339 if (ipipe && opipe) {
1340 if (off_in || off_out)
1341 return -ESPIPE;
1342
1343 if (!(in->f_mode & FMODE_READ))
1344 return -EBADF;
1345
1346 if (!(out->f_mode & FMODE_WRITE))
1347 return -EBADF;
1348
1349 /* Splicing to self would be fun, but... */
1350 if (ipipe == opipe)
1351 return -EINVAL;
1352
1353 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1354 }
1355
1356 if (ipipe) {
529565dc
IM
1357 if (off_in)
1358 return -ESPIPE;
b92ce558 1359 if (off_out) {
19c9a49b 1360 if (!(out->f_mode & FMODE_PWRITE))
b92ce558 1361 return -EINVAL;
cbb7e577 1362 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
b92ce558 1363 return -EFAULT;
7995bd28
AV
1364 } else {
1365 offset = out->f_pos;
1366 }
529565dc 1367
18c67cb9
AV
1368 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1369 return -EBADF;
1370
1371 if (unlikely(out->f_flags & O_APPEND))
1372 return -EINVAL;
1373
1374 ret = rw_verify_area(WRITE, out, &offset, len);
1375 if (unlikely(ret < 0))
1376 return ret;
1377
500368f7 1378 file_start_write(out);
7995bd28 1379 ret = do_splice_from(ipipe, out, &offset, len, flags);
500368f7 1380 file_end_write(out);
a4514ebd 1381
7995bd28
AV
1382 if (!off_out)
1383 out->f_pos = offset;
1384 else if (copy_to_user(off_out, &offset, sizeof(loff_t)))
a4514ebd
JA
1385 ret = -EFAULT;
1386
1387 return ret;
529565dc 1388 }
5274f052 1389
7c77f0b3 1390 if (opipe) {
529565dc
IM
1391 if (off_out)
1392 return -ESPIPE;
b92ce558 1393 if (off_in) {
19c9a49b 1394 if (!(in->f_mode & FMODE_PREAD))
b92ce558 1395 return -EINVAL;
cbb7e577 1396 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
b92ce558 1397 return -EFAULT;
7995bd28
AV
1398 } else {
1399 offset = in->f_pos;
1400 }
529565dc 1401
7995bd28 1402 ret = do_splice_to(in, &offset, opipe, len, flags);
a4514ebd 1403
7995bd28
AV
1404 if (!off_in)
1405 in->f_pos = offset;
1406 else if (copy_to_user(off_in, &offset, sizeof(loff_t)))
a4514ebd
JA
1407 ret = -EFAULT;
1408
1409 return ret;
529565dc 1410 }
5274f052
JA
1411
1412 return -EINVAL;
1413}
1414
912d35f8
JA
1415/*
1416 * Map an iov into an array of pages and offset/length tupples. With the
1417 * partial_page structure, we can map several non-contiguous ranges into
1418 * our ones pages[] map instead of splitting that operation into pieces.
1419 * Could easily be exported as a generic helper for other users, in which
1420 * case one would probably want to add a 'max_nr_pages' parameter as well.
1421 */
1422static int get_iovec_page_array(const struct iovec __user *iov,
1423 unsigned int nr_vecs, struct page **pages,
bd1a68b5 1424 struct partial_page *partial, bool aligned,
35f3d14d 1425 unsigned int pipe_buffers)
912d35f8
JA
1426{
1427 int buffers = 0, error = 0;
1428
912d35f8
JA
1429 while (nr_vecs) {
1430 unsigned long off, npages;
75723957 1431 struct iovec entry;
912d35f8
JA
1432 void __user *base;
1433 size_t len;
1434 int i;
1435
75723957 1436 error = -EFAULT;
bc40d73c 1437 if (copy_from_user(&entry, iov, sizeof(entry)))
912d35f8
JA
1438 break;
1439
75723957
LT
1440 base = entry.iov_base;
1441 len = entry.iov_len;
1442
912d35f8
JA
1443 /*
1444 * Sanity check this iovec. 0 read succeeds.
1445 */
75723957 1446 error = 0;
912d35f8
JA
1447 if (unlikely(!len))
1448 break;
1449 error = -EFAULT;
712a30e6 1450 if (!access_ok(VERIFY_READ, base, len))
912d35f8
JA
1451 break;
1452
1453 /*
1454 * Get this base offset and number of pages, then map
1455 * in the user pages.
1456 */
1457 off = (unsigned long) base & ~PAGE_MASK;
7afa6fd0
JA
1458
1459 /*
1460 * If asked for alignment, the offset must be zero and the
1461 * length a multiple of the PAGE_SIZE.
1462 */
1463 error = -EINVAL;
1464 if (aligned && (off || len & ~PAGE_MASK))
1465 break;
1466
912d35f8 1467 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
35f3d14d
JA
1468 if (npages > pipe_buffers - buffers)
1469 npages = pipe_buffers - buffers;
912d35f8 1470
bc40d73c
NP
1471 error = get_user_pages_fast((unsigned long)base, npages,
1472 0, &pages[buffers]);
912d35f8
JA
1473
1474 if (unlikely(error <= 0))
1475 break;
1476
1477 /*
1478 * Fill this contiguous range into the partial page map.
1479 */
1480 for (i = 0; i < error; i++) {
7591489a 1481 const int plen = min_t(size_t, len, PAGE_SIZE - off);
912d35f8
JA
1482
1483 partial[buffers].offset = off;
1484 partial[buffers].len = plen;
1485
1486 off = 0;
1487 len -= plen;
1488 buffers++;
1489 }
1490
1491 /*
1492 * We didn't complete this iov, stop here since it probably
1493 * means we have to move some of this into a pipe to
1494 * be able to continue.
1495 */
1496 if (len)
1497 break;
1498
1499 /*
1500 * Don't continue if we mapped fewer pages than we asked for,
1501 * or if we mapped the max number of pages that we have
1502 * room for.
1503 */
35f3d14d 1504 if (error < npages || buffers == pipe_buffers)
912d35f8
JA
1505 break;
1506
1507 nr_vecs--;
1508 iov++;
1509 }
1510
912d35f8
JA
1511 if (buffers)
1512 return buffers;
1513
1514 return error;
1515}
1516
6a14b90b
JA
1517static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1518 struct splice_desc *sd)
1519{
6130f531
AV
1520 int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
1521 return n == sd->len ? n : -EFAULT;
6a14b90b
JA
1522}
1523
1524/*
1525 * For lack of a better implementation, implement vmsplice() to userspace
1526 * as a simple copy of the pipes pages to the user iov.
1527 */
6130f531 1528static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
6a14b90b
JA
1529 unsigned long nr_segs, unsigned int flags)
1530{
1531 struct pipe_inode_info *pipe;
1532 struct splice_desc sd;
6a14b90b 1533 long ret;
6130f531
AV
1534 struct iovec iovstack[UIO_FASTIOV];
1535 struct iovec *iov = iovstack;
1536 struct iov_iter iter;
b6dd6f47 1537 ssize_t count;
6a14b90b 1538
71993e62 1539 pipe = get_pipe_info(file);
6a14b90b
JA
1540 if (!pipe)
1541 return -EBADF;
1542
6130f531
AV
1543 ret = rw_copy_check_uvector(READ, uiov, nr_segs,
1544 ARRAY_SIZE(iovstack), iovstack, &iov);
1545 if (ret <= 0)
b6dd6f47 1546 goto out;
6a14b90b 1547
b6dd6f47 1548 count = ret;
71d8e532 1549 iov_iter_init(&iter, READ, iov, nr_segs, count);
6a14b90b 1550
6130f531
AV
1551 sd.len = 0;
1552 sd.total_len = count;
1553 sd.flags = flags;
1554 sd.u.data = &iter;
1555 sd.pos = 0;
6a14b90b 1556
6130f531
AV
1557 pipe_lock(pipe);
1558 ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
61e0d47c 1559 pipe_unlock(pipe);
6a14b90b 1560
b6dd6f47 1561out:
6130f531
AV
1562 if (iov != iovstack)
1563 kfree(iov);
6a14b90b
JA
1564
1565 return ret;
1566}
1567
912d35f8
JA
1568/*
1569 * vmsplice splices a user address range into a pipe. It can be thought of
1570 * as splice-from-memory, where the regular splice is splice-from-file (or
1571 * to file). In both cases the output is a pipe, naturally.
912d35f8 1572 */
6a14b90b
JA
1573static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
1574 unsigned long nr_segs, unsigned int flags)
912d35f8 1575{
ddac0d39 1576 struct pipe_inode_info *pipe;
35f3d14d
JA
1577 struct page *pages[PIPE_DEF_BUFFERS];
1578 struct partial_page partial[PIPE_DEF_BUFFERS];
912d35f8
JA
1579 struct splice_pipe_desc spd = {
1580 .pages = pages,
1581 .partial = partial,
047fe360 1582 .nr_pages_max = PIPE_DEF_BUFFERS,
912d35f8
JA
1583 .flags = flags,
1584 .ops = &user_page_pipe_buf_ops,
bbdfc2f7 1585 .spd_release = spd_release_page,
912d35f8 1586 };
35f3d14d 1587 long ret;
912d35f8 1588
71993e62 1589 pipe = get_pipe_info(file);
ddac0d39 1590 if (!pipe)
912d35f8 1591 return -EBADF;
912d35f8 1592
35f3d14d
JA
1593 if (splice_grow_spd(pipe, &spd))
1594 return -ENOMEM;
1595
1596 spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
bd1a68b5 1597 spd.partial, false,
047fe360 1598 spd.nr_pages_max);
912d35f8 1599 if (spd.nr_pages <= 0)
35f3d14d
JA
1600 ret = spd.nr_pages;
1601 else
1602 ret = splice_to_pipe(pipe, &spd);
912d35f8 1603
047fe360 1604 splice_shrink_spd(&spd);
35f3d14d 1605 return ret;
912d35f8
JA
1606}
1607
6a14b90b
JA
1608/*
1609 * Note that vmsplice only really supports true splicing _from_ user memory
1610 * to a pipe, not the other way around. Splicing from user memory is a simple
1611 * operation that can be supported without any funky alignment restrictions
1612 * or nasty vm tricks. We simply map in the user memory and fill them into
1613 * a pipe. The reverse isn't quite as easy, though. There are two possible
1614 * solutions for that:
1615 *
1616 * - memcpy() the data internally, at which point we might as well just
1617 * do a regular read() on the buffer anyway.
1618 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1619 * has restriction limitations on both ends of the pipe).
1620 *
1621 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1622 *
1623 */
836f92ad
HC
1624SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
1625 unsigned long, nr_segs, unsigned int, flags)
912d35f8 1626{
2903ff01 1627 struct fd f;
912d35f8 1628 long error;
912d35f8 1629
6a14b90b
JA
1630 if (unlikely(nr_segs > UIO_MAXIOV))
1631 return -EINVAL;
1632 else if (unlikely(!nr_segs))
1633 return 0;
1634
912d35f8 1635 error = -EBADF;
2903ff01
AV
1636 f = fdget(fd);
1637 if (f.file) {
1638 if (f.file->f_mode & FMODE_WRITE)
1639 error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
1640 else if (f.file->f_mode & FMODE_READ)
1641 error = vmsplice_to_user(f.file, iov, nr_segs, flags);
1642
1643 fdput(f);
912d35f8
JA
1644 }
1645
1646 return error;
1647}
1648
76b021d0
AV
1649#ifdef CONFIG_COMPAT
1650COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
1651 unsigned int, nr_segs, unsigned int, flags)
1652{
1653 unsigned i;
1654 struct iovec __user *iov;
1655 if (nr_segs > UIO_MAXIOV)
1656 return -EINVAL;
1657 iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
1658 for (i = 0; i < nr_segs; i++) {
1659 struct compat_iovec v;
1660 if (get_user(v.iov_base, &iov32[i].iov_base) ||
1661 get_user(v.iov_len, &iov32[i].iov_len) ||
1662 put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
1663 put_user(v.iov_len, &iov[i].iov_len))
1664 return -EFAULT;
1665 }
1666 return sys_vmsplice(fd, iov, nr_segs, flags);
1667}
1668#endif
1669
836f92ad
HC
1670SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1671 int, fd_out, loff_t __user *, off_out,
1672 size_t, len, unsigned int, flags)
5274f052 1673{
2903ff01 1674 struct fd in, out;
5274f052 1675 long error;
5274f052
JA
1676
1677 if (unlikely(!len))
1678 return 0;
1679
1680 error = -EBADF;
2903ff01
AV
1681 in = fdget(fd_in);
1682 if (in.file) {
1683 if (in.file->f_mode & FMODE_READ) {
1684 out = fdget(fd_out);
1685 if (out.file) {
1686 if (out.file->f_mode & FMODE_WRITE)
1687 error = do_splice(in.file, off_in,
1688 out.file, off_out,
529565dc 1689 len, flags);
2903ff01 1690 fdput(out);
5274f052
JA
1691 }
1692 }
2903ff01 1693 fdput(in);
5274f052 1694 }
5274f052
JA
1695 return error;
1696}
70524490 1697
aadd06e5
JA
1698/*
1699 * Make sure there's data to read. Wait for input if we can, otherwise
1700 * return an appropriate error.
1701 */
7c77f0b3 1702static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
aadd06e5
JA
1703{
1704 int ret;
1705
1706 /*
1707 * Check ->nrbufs without the inode lock first. This function
1708 * is speculative anyways, so missing one is ok.
1709 */
1710 if (pipe->nrbufs)
1711 return 0;
1712
1713 ret = 0;
61e0d47c 1714 pipe_lock(pipe);
aadd06e5
JA
1715
1716 while (!pipe->nrbufs) {
1717 if (signal_pending(current)) {
1718 ret = -ERESTARTSYS;
1719 break;
1720 }
1721 if (!pipe->writers)
1722 break;
1723 if (!pipe->waiting_writers) {
1724 if (flags & SPLICE_F_NONBLOCK) {
1725 ret = -EAGAIN;
1726 break;
1727 }
1728 }
1729 pipe_wait(pipe);
1730 }
1731
61e0d47c 1732 pipe_unlock(pipe);
aadd06e5
JA
1733 return ret;
1734}
1735
1736/*
1737 * Make sure there's writeable room. Wait for room if we can, otherwise
1738 * return an appropriate error.
1739 */
7c77f0b3 1740static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
aadd06e5
JA
1741{
1742 int ret;
1743
1744 /*
1745 * Check ->nrbufs without the inode lock first. This function
1746 * is speculative anyways, so missing one is ok.
1747 */
35f3d14d 1748 if (pipe->nrbufs < pipe->buffers)
aadd06e5
JA
1749 return 0;
1750
1751 ret = 0;
61e0d47c 1752 pipe_lock(pipe);
aadd06e5 1753
35f3d14d 1754 while (pipe->nrbufs >= pipe->buffers) {
aadd06e5
JA
1755 if (!pipe->readers) {
1756 send_sig(SIGPIPE, current, 0);
1757 ret = -EPIPE;
1758 break;
1759 }
1760 if (flags & SPLICE_F_NONBLOCK) {
1761 ret = -EAGAIN;
1762 break;
1763 }
1764 if (signal_pending(current)) {
1765 ret = -ERESTARTSYS;
1766 break;
1767 }
1768 pipe->waiting_writers++;
1769 pipe_wait(pipe);
1770 pipe->waiting_writers--;
1771 }
1772
61e0d47c 1773 pipe_unlock(pipe);
aadd06e5
JA
1774 return ret;
1775}
1776
7c77f0b3
MS
1777/*
1778 * Splice contents of ipipe to opipe.
1779 */
1780static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1781 struct pipe_inode_info *opipe,
1782 size_t len, unsigned int flags)
1783{
1784 struct pipe_buffer *ibuf, *obuf;
1785 int ret = 0, nbuf;
1786 bool input_wakeup = false;
1787
1788
1789retry:
1790 ret = ipipe_prep(ipipe, flags);
1791 if (ret)
1792 return ret;
1793
1794 ret = opipe_prep(opipe, flags);
1795 if (ret)
1796 return ret;
1797
1798 /*
1799 * Potential ABBA deadlock, work around it by ordering lock
1800 * grabbing by pipe info address. Otherwise two different processes
1801 * could deadlock (one doing tee from A -> B, the other from B -> A).
1802 */
1803 pipe_double_lock(ipipe, opipe);
1804
1805 do {
1806 if (!opipe->readers) {
1807 send_sig(SIGPIPE, current, 0);
1808 if (!ret)
1809 ret = -EPIPE;
1810 break;
1811 }
1812
1813 if (!ipipe->nrbufs && !ipipe->writers)
1814 break;
1815
1816 /*
1817 * Cannot make any progress, because either the input
1818 * pipe is empty or the output pipe is full.
1819 */
35f3d14d 1820 if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
7c77f0b3
MS
1821 /* Already processed some buffers, break */
1822 if (ret)
1823 break;
1824
1825 if (flags & SPLICE_F_NONBLOCK) {
1826 ret = -EAGAIN;
1827 break;
1828 }
1829
1830 /*
1831 * We raced with another reader/writer and haven't
1832 * managed to process any buffers. A zero return
1833 * value means EOF, so retry instead.
1834 */
1835 pipe_unlock(ipipe);
1836 pipe_unlock(opipe);
1837 goto retry;
1838 }
1839
1840 ibuf = ipipe->bufs + ipipe->curbuf;
35f3d14d 1841 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
7c77f0b3
MS
1842 obuf = opipe->bufs + nbuf;
1843
1844 if (len >= ibuf->len) {
1845 /*
1846 * Simply move the whole buffer from ipipe to opipe
1847 */
1848 *obuf = *ibuf;
1849 ibuf->ops = NULL;
1850 opipe->nrbufs++;
35f3d14d 1851 ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
7c77f0b3
MS
1852 ipipe->nrbufs--;
1853 input_wakeup = true;
1854 } else {
1855 /*
1856 * Get a reference to this pipe buffer,
1857 * so we can copy the contents over.
1858 */
1859 ibuf->ops->get(ipipe, ibuf);
1860 *obuf = *ibuf;
1861
1862 /*
1863 * Don't inherit the gift flag, we need to
1864 * prevent multiple steals of this page.
1865 */
1866 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1867
1868 obuf->len = len;
1869 opipe->nrbufs++;
1870 ibuf->offset += obuf->len;
1871 ibuf->len -= obuf->len;
1872 }
1873 ret += obuf->len;
1874 len -= obuf->len;
1875 } while (len);
1876
1877 pipe_unlock(ipipe);
1878 pipe_unlock(opipe);
1879
1880 /*
1881 * If we put data in the output pipe, wakeup any potential readers.
1882 */
825cdcb1
NK
1883 if (ret > 0)
1884 wakeup_pipe_readers(opipe);
1885
7c77f0b3
MS
1886 if (input_wakeup)
1887 wakeup_pipe_writers(ipipe);
1888
1889 return ret;
1890}
1891
70524490
JA
1892/*
1893 * Link contents of ipipe to opipe.
1894 */
1895static int link_pipe(struct pipe_inode_info *ipipe,
1896 struct pipe_inode_info *opipe,
1897 size_t len, unsigned int flags)
1898{
1899 struct pipe_buffer *ibuf, *obuf;
aadd06e5 1900 int ret = 0, i = 0, nbuf;
70524490
JA
1901
1902 /*
1903 * Potential ABBA deadlock, work around it by ordering lock
61e0d47c 1904 * grabbing by pipe info address. Otherwise two different processes
70524490
JA
1905 * could deadlock (one doing tee from A -> B, the other from B -> A).
1906 */
61e0d47c 1907 pipe_double_lock(ipipe, opipe);
70524490 1908
aadd06e5 1909 do {
70524490
JA
1910 if (!opipe->readers) {
1911 send_sig(SIGPIPE, current, 0);
1912 if (!ret)
1913 ret = -EPIPE;
1914 break;
1915 }
70524490 1916
aadd06e5
JA
1917 /*
1918 * If we have iterated all input buffers or ran out of
1919 * output room, break.
1920 */
35f3d14d 1921 if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
aadd06e5 1922 break;
70524490 1923
35f3d14d
JA
1924 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
1925 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
70524490
JA
1926
1927 /*
aadd06e5
JA
1928 * Get a reference to this pipe buffer,
1929 * so we can copy the contents over.
70524490 1930 */
aadd06e5
JA
1931 ibuf->ops->get(ipipe, ibuf);
1932
1933 obuf = opipe->bufs + nbuf;
1934 *obuf = *ibuf;
1935
2a27250e 1936 /*
aadd06e5
JA
1937 * Don't inherit the gift flag, we need to
1938 * prevent multiple steals of this page.
2a27250e 1939 */
aadd06e5 1940 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
70524490 1941
aadd06e5
JA
1942 if (obuf->len > len)
1943 obuf->len = len;
70524490 1944
aadd06e5
JA
1945 opipe->nrbufs++;
1946 ret += obuf->len;
1947 len -= obuf->len;
1948 i++;
1949 } while (len);
70524490 1950
02cf01ae
JA
1951 /*
1952 * return EAGAIN if we have the potential of some data in the
1953 * future, otherwise just return 0
1954 */
1955 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1956 ret = -EAGAIN;
1957
61e0d47c
MS
1958 pipe_unlock(ipipe);
1959 pipe_unlock(opipe);
70524490 1960
aadd06e5
JA
1961 /*
1962 * If we put data in the output pipe, wakeup any potential readers.
1963 */
825cdcb1
NK
1964 if (ret > 0)
1965 wakeup_pipe_readers(opipe);
70524490
JA
1966
1967 return ret;
1968}
1969
1970/*
1971 * This is a tee(1) implementation that works on pipes. It doesn't copy
1972 * any data, it simply references the 'in' pages on the 'out' pipe.
1973 * The 'flags' used are the SPLICE_F_* variants, currently the only
1974 * applicable one is SPLICE_F_NONBLOCK.
1975 */
1976static long do_tee(struct file *in, struct file *out, size_t len,
1977 unsigned int flags)
1978{
71993e62
LT
1979 struct pipe_inode_info *ipipe = get_pipe_info(in);
1980 struct pipe_inode_info *opipe = get_pipe_info(out);
aadd06e5 1981 int ret = -EINVAL;
70524490
JA
1982
1983 /*
aadd06e5
JA
1984 * Duplicate the contents of ipipe to opipe without actually
1985 * copying the data.
70524490 1986 */
aadd06e5
JA
1987 if (ipipe && opipe && ipipe != opipe) {
1988 /*
1989 * Keep going, unless we encounter an error. The ipipe/opipe
1990 * ordering doesn't really matter.
1991 */
7c77f0b3 1992 ret = ipipe_prep(ipipe, flags);
aadd06e5 1993 if (!ret) {
7c77f0b3 1994 ret = opipe_prep(opipe, flags);
02cf01ae 1995 if (!ret)
aadd06e5 1996 ret = link_pipe(ipipe, opipe, len, flags);
aadd06e5
JA
1997 }
1998 }
70524490 1999
aadd06e5 2000 return ret;
70524490
JA
2001}
2002
836f92ad 2003SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
70524490 2004{
2903ff01
AV
2005 struct fd in;
2006 int error;
70524490
JA
2007
2008 if (unlikely(!len))
2009 return 0;
2010
2011 error = -EBADF;
2903ff01
AV
2012 in = fdget(fdin);
2013 if (in.file) {
2014 if (in.file->f_mode & FMODE_READ) {
2015 struct fd out = fdget(fdout);
2016 if (out.file) {
2017 if (out.file->f_mode & FMODE_WRITE)
2018 error = do_tee(in.file, out.file,
2019 len, flags);
2020 fdput(out);
70524490
JA
2021 }
2022 }
2903ff01 2023 fdput(in);
70524490
JA
2024 }
2025
2026 return error;
2027}