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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>
23#include <linux/pipe_fs_i.h>
24#include <linux/mm_inline.h>
5abc97aa 25#include <linux/swap.h>
4f6f0bd2
JA
26#include <linux/writeback.h>
27#include <linux/buffer_head.h>
a0f06780 28#include <linux/module.h>
4f6f0bd2 29#include <linux/syscalls.h>
912d35f8 30#include <linux/uio.h>
5274f052 31
912d35f8
JA
32struct partial_page {
33 unsigned int offset;
34 unsigned int len;
35};
36
37/*
00522fb4 38 * Passed to splice_to_pipe
912d35f8
JA
39 */
40struct splice_pipe_desc {
41 struct page **pages; /* page map */
42 struct partial_page *partial; /* pages[] may not be contig */
43 int nr_pages; /* number of pages in map */
44 unsigned int flags; /* splice flags */
45 struct pipe_buf_operations *ops;/* ops associated with output pipe */
46};
47
83f9135b
JA
48/*
49 * Attempt to steal a page from a pipe buffer. This should perhaps go into
50 * a vm helper function, it's already simplified quite a bit by the
51 * addition of remove_mapping(). If success is returned, the caller may
52 * attempt to reuse this page for another destination.
53 */
76ad4d11 54static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
5abc97aa
JA
55 struct pipe_buffer *buf)
56{
57 struct page *page = buf->page;
9e94cd4f 58 struct address_space *mapping;
5abc97aa 59
9e0267c2
JA
60 lock_page(page);
61
9e94cd4f
JA
62 mapping = page_mapping(page);
63 if (mapping) {
64 WARN_ON(!PageUptodate(page));
5abc97aa 65
9e94cd4f
JA
66 /*
67 * At least for ext2 with nobh option, we need to wait on
68 * writeback completing on this page, since we'll remove it
69 * from the pagecache. Otherwise truncate wont wait on the
70 * page, allowing the disk blocks to be reused by someone else
71 * before we actually wrote our data to them. fs corruption
72 * ensues.
73 */
74 wait_on_page_writeback(page);
ad8d6f0a 75
9e94cd4f
JA
76 if (PagePrivate(page))
77 try_to_release_page(page, mapping_gfp_mask(mapping));
4f6f0bd2 78
9e94cd4f
JA
79 /*
80 * If we succeeded in removing the mapping, set LRU flag
81 * and return good.
82 */
83 if (remove_mapping(mapping, page)) {
84 buf->flags |= PIPE_BUF_FLAG_LRU;
85 return 0;
86 }
9e0267c2 87 }
5abc97aa 88
9e94cd4f
JA
89 /*
90 * Raced with truncate or failed to remove page from current
91 * address space, unlock and return failure.
92 */
93 unlock_page(page);
94 return 1;
5abc97aa
JA
95}
96
76ad4d11 97static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
5274f052
JA
98 struct pipe_buffer *buf)
99{
100 page_cache_release(buf->page);
1432873a 101 buf->flags &= ~PIPE_BUF_FLAG_LRU;
5274f052
JA
102}
103
76ad4d11 104static int page_cache_pipe_buf_pin(struct pipe_inode_info *pipe,
f84d7519 105 struct pipe_buffer *buf)
5274f052
JA
106{
107 struct page *page = buf->page;
49d0b21b 108 int err;
5274f052
JA
109
110 if (!PageUptodate(page)) {
49d0b21b
JA
111 lock_page(page);
112
113 /*
114 * Page got truncated/unhashed. This will cause a 0-byte
73d62d83 115 * splice, if this is the first page.
49d0b21b
JA
116 */
117 if (!page->mapping) {
118 err = -ENODATA;
119 goto error;
120 }
5274f052 121
49d0b21b 122 /*
73d62d83 123 * Uh oh, read-error from disk.
49d0b21b
JA
124 */
125 if (!PageUptodate(page)) {
126 err = -EIO;
127 goto error;
128 }
129
130 /*
f84d7519 131 * Page is ok afterall, we are done.
49d0b21b 132 */
5274f052 133 unlock_page(page);
5274f052
JA
134 }
135
f84d7519 136 return 0;
49d0b21b
JA
137error:
138 unlock_page(page);
f84d7519 139 return err;
70524490
JA
140}
141
5274f052
JA
142static struct pipe_buf_operations page_cache_pipe_buf_ops = {
143 .can_merge = 0,
f84d7519
JA
144 .map = generic_pipe_buf_map,
145 .unmap = generic_pipe_buf_unmap,
146 .pin = page_cache_pipe_buf_pin,
5274f052 147 .release = page_cache_pipe_buf_release,
5abc97aa 148 .steal = page_cache_pipe_buf_steal,
f84d7519 149 .get = generic_pipe_buf_get,
5274f052
JA
150};
151
912d35f8
JA
152static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
153 struct pipe_buffer *buf)
154{
7afa6fd0
JA
155 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
156 return 1;
157
1432873a 158 buf->flags |= PIPE_BUF_FLAG_LRU;
330ab716 159 return generic_pipe_buf_steal(pipe, buf);
912d35f8
JA
160}
161
162static struct pipe_buf_operations user_page_pipe_buf_ops = {
163 .can_merge = 0,
f84d7519
JA
164 .map = generic_pipe_buf_map,
165 .unmap = generic_pipe_buf_unmap,
166 .pin = generic_pipe_buf_pin,
912d35f8
JA
167 .release = page_cache_pipe_buf_release,
168 .steal = user_page_pipe_buf_steal,
f84d7519 169 .get = generic_pipe_buf_get,
912d35f8
JA
170};
171
83f9135b
JA
172/*
173 * Pipe output worker. This sets up our pipe format with the page cache
174 * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
175 */
00522fb4
JA
176static ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
177 struct splice_pipe_desc *spd)
5274f052 178{
912d35f8 179 int ret, do_wakeup, page_nr;
5274f052
JA
180
181 ret = 0;
182 do_wakeup = 0;
912d35f8 183 page_nr = 0;
5274f052 184
3a326a2c
IM
185 if (pipe->inode)
186 mutex_lock(&pipe->inode->i_mutex);
5274f052 187
5274f052 188 for (;;) {
3a326a2c 189 if (!pipe->readers) {
5274f052
JA
190 send_sig(SIGPIPE, current, 0);
191 if (!ret)
192 ret = -EPIPE;
193 break;
194 }
195
6f767b04
JA
196 if (pipe->nrbufs < PIPE_BUFFERS) {
197 int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
3a326a2c 198 struct pipe_buffer *buf = pipe->bufs + newbuf;
5274f052 199
912d35f8
JA
200 buf->page = spd->pages[page_nr];
201 buf->offset = spd->partial[page_nr].offset;
202 buf->len = spd->partial[page_nr].len;
203 buf->ops = spd->ops;
7afa6fd0
JA
204 if (spd->flags & SPLICE_F_GIFT)
205 buf->flags |= PIPE_BUF_FLAG_GIFT;
206
6f767b04 207 pipe->nrbufs++;
912d35f8
JA
208 page_nr++;
209 ret += buf->len;
210
6f767b04
JA
211 if (pipe->inode)
212 do_wakeup = 1;
5274f052 213
912d35f8 214 if (!--spd->nr_pages)
5274f052 215 break;
6f767b04 216 if (pipe->nrbufs < PIPE_BUFFERS)
5274f052
JA
217 continue;
218
219 break;
220 }
221
912d35f8 222 if (spd->flags & SPLICE_F_NONBLOCK) {
29e35094
LT
223 if (!ret)
224 ret = -EAGAIN;
225 break;
226 }
227
5274f052
JA
228 if (signal_pending(current)) {
229 if (!ret)
230 ret = -ERESTARTSYS;
231 break;
232 }
233
234 if (do_wakeup) {
c0bd1f65 235 smp_mb();
3a326a2c
IM
236 if (waitqueue_active(&pipe->wait))
237 wake_up_interruptible_sync(&pipe->wait);
238 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
5274f052
JA
239 do_wakeup = 0;
240 }
241
3a326a2c
IM
242 pipe->waiting_writers++;
243 pipe_wait(pipe);
244 pipe->waiting_writers--;
5274f052
JA
245 }
246
3a326a2c
IM
247 if (pipe->inode)
248 mutex_unlock(&pipe->inode->i_mutex);
5274f052
JA
249
250 if (do_wakeup) {
c0bd1f65 251 smp_mb();
3a326a2c
IM
252 if (waitqueue_active(&pipe->wait))
253 wake_up_interruptible(&pipe->wait);
254 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
5274f052
JA
255 }
256
912d35f8
JA
257 while (page_nr < spd->nr_pages)
258 page_cache_release(spd->pages[page_nr++]);
5274f052
JA
259
260 return ret;
261}
262
3a326a2c 263static int
cbb7e577
JA
264__generic_file_splice_read(struct file *in, loff_t *ppos,
265 struct pipe_inode_info *pipe, size_t len,
266 unsigned int flags)
5274f052
JA
267{
268 struct address_space *mapping = in->f_mapping;
912d35f8 269 unsigned int loff, nr_pages;
16c523dd 270 struct page *pages[PIPE_BUFFERS];
912d35f8 271 struct partial_page partial[PIPE_BUFFERS];
5274f052 272 struct page *page;
91ad66ef
JA
273 pgoff_t index, end_index;
274 loff_t isize;
912d35f8 275 size_t total_len;
eb20796b 276 int error, page_nr;
912d35f8
JA
277 struct splice_pipe_desc spd = {
278 .pages = pages,
279 .partial = partial,
280 .flags = flags,
281 .ops = &page_cache_pipe_buf_ops,
282 };
5274f052 283
cbb7e577 284 index = *ppos >> PAGE_CACHE_SHIFT;
912d35f8
JA
285 loff = *ppos & ~PAGE_CACHE_MASK;
286 nr_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
5274f052
JA
287
288 if (nr_pages > PIPE_BUFFERS)
289 nr_pages = PIPE_BUFFERS;
290
291 /*
73d62d83 292 * Initiate read-ahead on this page range. however, don't call into
0b749ce3
JA
293 * read-ahead if this is a non-zero offset (we are likely doing small
294 * chunk splice and the page is already there) for a single page.
5274f052 295 */
eb645a24
JA
296 if (!loff || nr_pages > 1)
297 page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);
5274f052 298
5274f052 299 /*
73d62d83 300 * Now fill in the holes:
5274f052 301 */
7480a904 302 error = 0;
912d35f8 303 total_len = 0;
82aa5d61 304
eb20796b
JA
305 /*
306 * Lookup the (hopefully) full range of pages we need.
307 */
308 spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
82aa5d61 309
eb20796b
JA
310 /*
311 * If find_get_pages_contig() returned fewer pages than we needed,
312 * allocate the rest.
313 */
314 index += spd.nr_pages;
315 while (spd.nr_pages < nr_pages) {
82aa5d61 316 /*
eb20796b
JA
317 * Page could be there, find_get_pages_contig() breaks on
318 * the first hole.
5274f052 319 */
7480a904
JA
320 page = find_get_page(mapping, index);
321 if (!page) {
e27dedd8
JA
322 /*
323 * Make sure the read-ahead engine is notified
324 * about this failure.
325 */
326 handle_ra_miss(mapping, &in->f_ra, index);
327
7480a904 328 /*
eb20796b 329 * page didn't exist, allocate one.
7480a904
JA
330 */
331 page = page_cache_alloc_cold(mapping);
332 if (!page)
333 break;
334
335 error = add_to_page_cache_lru(page, mapping, index,
eb20796b 336 mapping_gfp_mask(mapping));
7480a904
JA
337 if (unlikely(error)) {
338 page_cache_release(page);
a0548871
JA
339 if (error == -EEXIST)
340 continue;
7480a904
JA
341 break;
342 }
eb20796b
JA
343 /*
344 * add_to_page_cache() locks the page, unlock it
345 * to avoid convoluting the logic below even more.
346 */
347 unlock_page(page);
7480a904
JA
348 }
349
eb20796b
JA
350 pages[spd.nr_pages++] = page;
351 index++;
352 }
353
354 /*
355 * Now loop over the map and see if we need to start IO on any
356 * pages, fill in the partial map, etc.
357 */
358 index = *ppos >> PAGE_CACHE_SHIFT;
359 nr_pages = spd.nr_pages;
360 spd.nr_pages = 0;
361 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
362 unsigned int this_len;
363
364 if (!len)
365 break;
366
367 /*
368 * this_len is the max we'll use from this page
369 */
370 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
371 page = pages[page_nr];
372
7480a904
JA
373 /*
374 * If the page isn't uptodate, we may need to start io on it
375 */
376 if (!PageUptodate(page)) {
c4f895cb
JA
377 /*
378 * If in nonblock mode then dont block on waiting
379 * for an in-flight io page
380 */
381 if (flags & SPLICE_F_NONBLOCK)
382 break;
383
7480a904
JA
384 lock_page(page);
385
386 /*
387 * page was truncated, stop here. if this isn't the
388 * first page, we'll just complete what we already
389 * added
390 */
391 if (!page->mapping) {
392 unlock_page(page);
7480a904
JA
393 break;
394 }
395 /*
396 * page was already under io and is now done, great
397 */
398 if (PageUptodate(page)) {
399 unlock_page(page);
400 goto fill_it;
401 }
5274f052 402
7480a904
JA
403 /*
404 * need to read in the page
405 */
406 error = mapping->a_ops->readpage(in, page);
5274f052 407 if (unlikely(error)) {
eb20796b
JA
408 /*
409 * We really should re-lookup the page here,
410 * but it complicates things a lot. Instead
411 * lets just do what we already stored, and
412 * we'll get it the next time we are called.
413 */
7480a904 414 if (error == AOP_TRUNCATED_PAGE)
eb20796b
JA
415 error = 0;
416
5274f052
JA
417 break;
418 }
91ad66ef
JA
419
420 /*
421 * i_size must be checked after ->readpage().
422 */
423 isize = i_size_read(mapping->host);
424 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
eb20796b 425 if (unlikely(!isize || index > end_index))
91ad66ef 426 break;
91ad66ef
JA
427
428 /*
429 * if this is the last page, see if we need to shrink
430 * the length and stop
431 */
432 if (end_index == index) {
433 loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
eb20796b 434 if (total_len + loff > isize)
91ad66ef 435 break;
91ad66ef
JA
436 /*
437 * force quit after adding this page
438 */
eb20796b 439 len = this_len;
82aa5d61 440 this_len = min(this_len, loff);
912d35f8 441 loff = 0;
91ad66ef 442 }
5274f052 443 }
7480a904 444fill_it:
eb20796b
JA
445 partial[page_nr].offset = loff;
446 partial[page_nr].len = this_len;
82aa5d61 447 len -= this_len;
912d35f8 448 total_len += this_len;
91ad66ef 449 loff = 0;
eb20796b
JA
450 spd.nr_pages++;
451 index++;
5274f052
JA
452 }
453
eb20796b
JA
454 /*
455 * Release any pages at the end, if we quit early. 'i' is how far
456 * we got, 'nr_pages' is how many pages are in the map.
457 */
458 while (page_nr < nr_pages)
459 page_cache_release(pages[page_nr++]);
460
912d35f8 461 if (spd.nr_pages)
00522fb4 462 return splice_to_pipe(pipe, &spd);
5274f052 463
7480a904 464 return error;
5274f052
JA
465}
466
83f9135b
JA
467/**
468 * generic_file_splice_read - splice data from file to a pipe
469 * @in: file to splice from
470 * @pipe: pipe to splice to
471 * @len: number of bytes to splice
472 * @flags: splice modifier flags
473 *
474 * Will read pages from given file and fill them into a pipe.
83f9135b 475 */
cbb7e577
JA
476ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
477 struct pipe_inode_info *pipe, size_t len,
478 unsigned int flags)
5274f052
JA
479{
480 ssize_t spliced;
481 int ret;
482
483 ret = 0;
484 spliced = 0;
3a326a2c 485
5274f052 486 while (len) {
cbb7e577 487 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
5274f052 488
c4f895cb 489 if (ret < 0)
5274f052 490 break;
c4f895cb
JA
491 else if (!ret) {
492 if (spliced)
493 break;
494 if (flags & SPLICE_F_NONBLOCK) {
495 ret = -EAGAIN;
496 break;
497 }
498 }
5274f052 499
cbb7e577 500 *ppos += ret;
5274f052
JA
501 len -= ret;
502 spliced += ret;
503 }
504
505 if (spliced)
506 return spliced;
507
508 return ret;
509}
510
059a8f37
JA
511EXPORT_SYMBOL(generic_file_splice_read);
512
5274f052 513/*
4f6f0bd2 514 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
016b661e 515 * using sendpage(). Return the number of bytes sent.
5274f052 516 */
76ad4d11 517static int pipe_to_sendpage(struct pipe_inode_info *pipe,
5274f052
JA
518 struct pipe_buffer *buf, struct splice_desc *sd)
519{
520 struct file *file = sd->file;
521 loff_t pos = sd->pos;
f84d7519 522 int ret, more;
5274f052 523
76ad4d11 524 ret = buf->ops->pin(pipe, buf);
f84d7519
JA
525 if (!ret) {
526 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
5274f052 527
f84d7519
JA
528 ret = file->f_op->sendpage(file, buf->page, buf->offset,
529 sd->len, &pos, more);
530 }
5274f052 531
016b661e 532 return ret;
5274f052
JA
533}
534
535/*
536 * This is a little more tricky than the file -> pipe splicing. There are
537 * basically three cases:
538 *
539 * - Destination page already exists in the address space and there
540 * are users of it. For that case we have no other option that
541 * copying the data. Tough luck.
542 * - Destination page already exists in the address space, but there
543 * are no users of it. Make sure it's uptodate, then drop it. Fall
544 * through to last case.
545 * - Destination page does not exist, we can add the pipe page to
546 * the page cache and avoid the copy.
547 *
83f9135b
JA
548 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
549 * sd->flags), we attempt to migrate pages from the pipe to the output
550 * file address space page cache. This is possible if no one else has
551 * the pipe page referenced outside of the pipe and page cache. If
552 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
553 * a new page in the output file page cache and fill/dirty that.
5274f052 554 */
76ad4d11 555static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
5274f052
JA
556 struct splice_desc *sd)
557{
558 struct file *file = sd->file;
559 struct address_space *mapping = file->f_mapping;
3e7ee3e7 560 gfp_t gfp_mask = mapping_gfp_mask(mapping);
016b661e 561 unsigned int offset, this_len;
5274f052 562 struct page *page;
5274f052 563 pgoff_t index;
3e7ee3e7 564 int ret;
5274f052
JA
565
566 /*
49d0b21b 567 * make sure the data in this buffer is uptodate
5274f052 568 */
76ad4d11 569 ret = buf->ops->pin(pipe, buf);
f84d7519
JA
570 if (unlikely(ret))
571 return ret;
5274f052
JA
572
573 index = sd->pos >> PAGE_CACHE_SHIFT;
574 offset = sd->pos & ~PAGE_CACHE_MASK;
575
016b661e
JA
576 this_len = sd->len;
577 if (this_len + offset > PAGE_CACHE_SIZE)
578 this_len = PAGE_CACHE_SIZE - offset;
579
5274f052 580 /*
0568b409
JA
581 * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full
582 * page.
5274f052 583 */
0568b409 584 if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
83f9135b 585 /*
1432873a
JA
586 * If steal succeeds, buf->page is now pruned from the
587 * pagecache and we can reuse it. The page will also be
588 * locked on successful return.
83f9135b 589 */
76ad4d11 590 if (buf->ops->steal(pipe, buf))
5abc97aa
JA
591 goto find_page;
592
593 page = buf->page;
46e678c9
JA
594 if (add_to_page_cache(page, mapping, index, gfp_mask)) {
595 unlock_page(page);
5abc97aa 596 goto find_page;
46e678c9 597 }
1432873a
JA
598
599 page_cache_get(page);
600
601 if (!(buf->flags & PIPE_BUF_FLAG_LRU))
602 lru_cache_add(page);
5abc97aa
JA
603 } else {
604find_page:
9e0267c2
JA
605 page = find_lock_page(mapping, index);
606 if (!page) {
607 ret = -ENOMEM;
608 page = page_cache_alloc_cold(mapping);
609 if (unlikely(!page))
610 goto out_nomem;
611
612 /*
613 * This will also lock the page
614 */
615 ret = add_to_page_cache_lru(page, mapping, index,
616 gfp_mask);
617 if (unlikely(ret))
618 goto out;
619 }
5abc97aa
JA
620
621 /*
9e0267c2
JA
622 * We get here with the page locked. If the page is also
623 * uptodate, we don't need to do more. If it isn't, we
624 * may need to bring it in if we are not going to overwrite
625 * the full page.
5abc97aa
JA
626 */
627 if (!PageUptodate(page)) {
016b661e 628 if (this_len < PAGE_CACHE_SIZE) {
5abc97aa
JA
629 ret = mapping->a_ops->readpage(file, page);
630 if (unlikely(ret))
631 goto out;
632
633 lock_page(page);
634
635 if (!PageUptodate(page)) {
636 /*
73d62d83 637 * Page got invalidated, repeat.
5abc97aa
JA
638 */
639 if (!page->mapping) {
640 unlock_page(page);
641 page_cache_release(page);
642 goto find_page;
643 }
644 ret = -EIO;
645 goto out;
5274f052 646 }
9e0267c2 647 } else
5abc97aa 648 SetPageUptodate(page);
5274f052
JA
649 }
650 }
651
016b661e 652 ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
bfc4ee39
JA
653 if (unlikely(ret)) {
654 loff_t isize = i_size_read(mapping->host);
655
656 if (ret != AOP_TRUNCATED_PAGE)
657 unlock_page(page);
4f6f0bd2 658 page_cache_release(page);
bfc4ee39
JA
659 if (ret == AOP_TRUNCATED_PAGE)
660 goto find_page;
661
662 /*
663 * prepare_write() may have instantiated a few blocks
664 * outside i_size. Trim these off again.
665 */
666 if (sd->pos + this_len > isize)
667 vmtruncate(mapping->host, isize);
668
5274f052 669 goto out;
bfc4ee39 670 }
5274f052 671
0568b409 672 if (buf->page != page) {
f84d7519
JA
673 /*
674 * Careful, ->map() uses KM_USER0!
675 */
76ad4d11 676 char *src = buf->ops->map(pipe, buf, 1);
f84d7519 677 char *dst = kmap_atomic(page, KM_USER1);
5abc97aa 678
016b661e 679 memcpy(dst + offset, src + buf->offset, this_len);
5abc97aa 680 flush_dcache_page(page);
f84d7519 681 kunmap_atomic(dst, KM_USER1);
76ad4d11 682 buf->ops->unmap(pipe, buf, src);
5abc97aa 683 }
5274f052 684
016b661e 685 ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
0568b409
JA
686 if (!ret) {
687 /*
688 * Return the number of bytes written and mark page as
689 * accessed, we are now done!
690 */
691 ret = this_len;
692 mark_page_accessed(page);
693 balance_dirty_pages_ratelimited(mapping);
694 } else if (ret == AOP_TRUNCATED_PAGE) {
4f6f0bd2
JA
695 page_cache_release(page);
696 goto find_page;
0568b409 697 }
5274f052 698out:
0568b409 699 page_cache_release(page);
9e0267c2 700 unlock_page(page);
9aefe431 701out_nomem:
5274f052
JA
702 return ret;
703}
704
83f9135b
JA
705/*
706 * Pipe input worker. Most of this logic works like a regular pipe, the
707 * key here is the 'actor' worker passed in that actually moves the data
708 * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
709 */
00522fb4
JA
710ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
711 loff_t *ppos, size_t len, unsigned int flags,
712 splice_actor *actor)
5274f052 713{
5274f052
JA
714 int ret, do_wakeup, err;
715 struct splice_desc sd;
716
717 ret = 0;
718 do_wakeup = 0;
719
720 sd.total_len = len;
721 sd.flags = flags;
722 sd.file = out;
cbb7e577 723 sd.pos = *ppos;
5274f052 724
3a326a2c
IM
725 if (pipe->inode)
726 mutex_lock(&pipe->inode->i_mutex);
5274f052 727
5274f052 728 for (;;) {
6f767b04
JA
729 if (pipe->nrbufs) {
730 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
5274f052
JA
731 struct pipe_buf_operations *ops = buf->ops;
732
733 sd.len = buf->len;
734 if (sd.len > sd.total_len)
735 sd.len = sd.total_len;
736
3a326a2c 737 err = actor(pipe, buf, &sd);
016b661e 738 if (err <= 0) {
5274f052
JA
739 if (!ret && err != -ENODATA)
740 ret = err;
741
742 break;
743 }
744
016b661e
JA
745 ret += err;
746 buf->offset += err;
747 buf->len -= err;
748
749 sd.len -= err;
750 sd.pos += err;
751 sd.total_len -= err;
752 if (sd.len)
753 continue;
73d62d83 754
5274f052
JA
755 if (!buf->len) {
756 buf->ops = NULL;
3a326a2c 757 ops->release(pipe, buf);
6f767b04
JA
758 pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
759 pipe->nrbufs--;
760 if (pipe->inode)
761 do_wakeup = 1;
5274f052
JA
762 }
763
5274f052
JA
764 if (!sd.total_len)
765 break;
766 }
767
6f767b04 768 if (pipe->nrbufs)
5274f052 769 continue;
3a326a2c 770 if (!pipe->writers)
5274f052 771 break;
3a326a2c 772 if (!pipe->waiting_writers) {
5274f052
JA
773 if (ret)
774 break;
775 }
776
29e35094
LT
777 if (flags & SPLICE_F_NONBLOCK) {
778 if (!ret)
779 ret = -EAGAIN;
780 break;
781 }
782
5274f052
JA
783 if (signal_pending(current)) {
784 if (!ret)
785 ret = -ERESTARTSYS;
786 break;
787 }
788
789 if (do_wakeup) {
c0bd1f65 790 smp_mb();
3a326a2c
IM
791 if (waitqueue_active(&pipe->wait))
792 wake_up_interruptible_sync(&pipe->wait);
793 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
5274f052
JA
794 do_wakeup = 0;
795 }
796
3a326a2c 797 pipe_wait(pipe);
5274f052
JA
798 }
799
3a326a2c
IM
800 if (pipe->inode)
801 mutex_unlock(&pipe->inode->i_mutex);
5274f052
JA
802
803 if (do_wakeup) {
c0bd1f65 804 smp_mb();
3a326a2c
IM
805 if (waitqueue_active(&pipe->wait))
806 wake_up_interruptible(&pipe->wait);
807 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
5274f052
JA
808 }
809
5274f052 810 return ret;
5274f052
JA
811}
812
83f9135b
JA
813/**
814 * generic_file_splice_write - splice data from a pipe to a file
3a326a2c 815 * @pipe: pipe info
83f9135b
JA
816 * @out: file to write to
817 * @len: number of bytes to splice
818 * @flags: splice modifier flags
819 *
820 * Will either move or copy pages (determined by @flags options) from
821 * the given pipe inode to the given file.
822 *
823 */
3a326a2c
IM
824ssize_t
825generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
cbb7e577 826 loff_t *ppos, size_t len, unsigned int flags)
5274f052 827{
4f6f0bd2 828 struct address_space *mapping = out->f_mapping;
3a326a2c
IM
829 ssize_t ret;
830
00522fb4 831 ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
a4514ebd 832 if (ret > 0) {
4f6f0bd2 833 struct inode *inode = mapping->host;
4f6f0bd2 834
a4514ebd
JA
835 *ppos += ret;
836
837 /*
838 * If file or inode is SYNC and we actually wrote some data,
839 * sync it.
840 */
841 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
842 int err;
843
844 mutex_lock(&inode->i_mutex);
845 err = generic_osync_inode(inode, mapping,
846 OSYNC_METADATA|OSYNC_DATA);
847 mutex_unlock(&inode->i_mutex);
4f6f0bd2 848
a4514ebd
JA
849 if (err)
850 ret = err;
851 }
4f6f0bd2
JA
852 }
853
854 return ret;
5274f052
JA
855}
856
059a8f37
JA
857EXPORT_SYMBOL(generic_file_splice_write);
858
83f9135b
JA
859/**
860 * generic_splice_sendpage - splice data from a pipe to a socket
861 * @inode: pipe inode
862 * @out: socket to write to
863 * @len: number of bytes to splice
864 * @flags: splice modifier flags
865 *
866 * Will send @len bytes from the pipe to a network socket. No data copying
867 * is involved.
868 *
869 */
3a326a2c 870ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
cbb7e577 871 loff_t *ppos, size_t len, unsigned int flags)
5274f052 872{
00522fb4 873 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
5274f052
JA
874}
875
059a8f37 876EXPORT_SYMBOL(generic_splice_sendpage);
a0f06780 877
83f9135b
JA
878/*
879 * Attempt to initiate a splice from pipe to file.
880 */
3a326a2c 881static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
cbb7e577 882 loff_t *ppos, size_t len, unsigned int flags)
5274f052 883{
5274f052
JA
884 int ret;
885
49570e9b 886 if (unlikely(!out->f_op || !out->f_op->splice_write))
5274f052
JA
887 return -EINVAL;
888
49570e9b 889 if (unlikely(!(out->f_mode & FMODE_WRITE)))
5274f052
JA
890 return -EBADF;
891
cbb7e577 892 ret = rw_verify_area(WRITE, out, ppos, len);
5274f052
JA
893 if (unlikely(ret < 0))
894 return ret;
895
cbb7e577 896 return out->f_op->splice_write(pipe, out, ppos, len, flags);
5274f052
JA
897}
898
83f9135b
JA
899/*
900 * Attempt to initiate a splice from a file to a pipe.
901 */
cbb7e577
JA
902static long do_splice_to(struct file *in, loff_t *ppos,
903 struct pipe_inode_info *pipe, size_t len,
904 unsigned int flags)
5274f052 905{
cbb7e577 906 loff_t isize, left;
5274f052
JA
907 int ret;
908
49570e9b 909 if (unlikely(!in->f_op || !in->f_op->splice_read))
5274f052
JA
910 return -EINVAL;
911
49570e9b 912 if (unlikely(!(in->f_mode & FMODE_READ)))
5274f052
JA
913 return -EBADF;
914
cbb7e577 915 ret = rw_verify_area(READ, in, ppos, len);
5274f052
JA
916 if (unlikely(ret < 0))
917 return ret;
918
919 isize = i_size_read(in->f_mapping->host);
cbb7e577 920 if (unlikely(*ppos >= isize))
5274f052
JA
921 return 0;
922
cbb7e577 923 left = isize - *ppos;
49570e9b 924 if (unlikely(left < len))
5274f052
JA
925 len = left;
926
cbb7e577 927 return in->f_op->splice_read(in, ppos, pipe, len, flags);
5274f052
JA
928}
929
cbb7e577
JA
930long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
931 size_t len, unsigned int flags)
b92ce558
JA
932{
933 struct pipe_inode_info *pipe;
934 long ret, bytes;
cbb7e577 935 loff_t out_off;
b92ce558
JA
936 umode_t i_mode;
937 int i;
938
939 /*
940 * We require the input being a regular file, as we don't want to
941 * randomly drop data for eg socket -> socket splicing. Use the
942 * piped splicing for that!
943 */
944 i_mode = in->f_dentry->d_inode->i_mode;
945 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
946 return -EINVAL;
947
948 /*
949 * neither in nor out is a pipe, setup an internal pipe attached to
950 * 'out' and transfer the wanted data from 'in' to 'out' through that
951 */
952 pipe = current->splice_pipe;
49570e9b 953 if (unlikely(!pipe)) {
b92ce558
JA
954 pipe = alloc_pipe_info(NULL);
955 if (!pipe)
956 return -ENOMEM;
957
958 /*
959 * We don't have an immediate reader, but we'll read the stuff
00522fb4 960 * out of the pipe right after the splice_to_pipe(). So set
b92ce558
JA
961 * PIPE_READERS appropriately.
962 */
963 pipe->readers = 1;
964
965 current->splice_pipe = pipe;
966 }
967
968 /*
73d62d83 969 * Do the splice.
b92ce558
JA
970 */
971 ret = 0;
972 bytes = 0;
cbb7e577 973 out_off = 0;
b92ce558
JA
974
975 while (len) {
976 size_t read_len, max_read_len;
977
978 /*
979 * Do at most PIPE_BUFFERS pages worth of transfer:
980 */
981 max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
982
cbb7e577 983 ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
b92ce558
JA
984 if (unlikely(ret < 0))
985 goto out_release;
986
987 read_len = ret;
988
989 /*
990 * NOTE: nonblocking mode only applies to the input. We
991 * must not do the output in nonblocking mode as then we
992 * could get stuck data in the internal pipe:
993 */
cbb7e577 994 ret = do_splice_from(pipe, out, &out_off, read_len,
b92ce558
JA
995 flags & ~SPLICE_F_NONBLOCK);
996 if (unlikely(ret < 0))
997 goto out_release;
998
999 bytes += ret;
1000 len -= ret;
1001
1002 /*
1003 * In nonblocking mode, if we got back a short read then
1004 * that was due to either an IO error or due to the
1005 * pagecache entry not being there. In the IO error case
1006 * the _next_ splice attempt will produce a clean IO error
1007 * return value (not a short read), so in both cases it's
1008 * correct to break out of the loop here:
1009 */
1010 if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
1011 break;
1012 }
1013
1014 pipe->nrbufs = pipe->curbuf = 0;
1015
1016 return bytes;
1017
1018out_release:
1019 /*
1020 * If we did an incomplete transfer we must release
1021 * the pipe buffers in question:
1022 */
1023 for (i = 0; i < PIPE_BUFFERS; i++) {
1024 struct pipe_buffer *buf = pipe->bufs + i;
1025
1026 if (buf->ops) {
1027 buf->ops->release(pipe, buf);
1028 buf->ops = NULL;
1029 }
1030 }
1031 pipe->nrbufs = pipe->curbuf = 0;
1032
1033 /*
1034 * If we transferred some data, return the number of bytes:
1035 */
1036 if (bytes > 0)
1037 return bytes;
1038
1039 return ret;
1040}
1041
1042EXPORT_SYMBOL(do_splice_direct);
1043
83f9135b
JA
1044/*
1045 * Determine where to splice to/from.
1046 */
529565dc
IM
1047static long do_splice(struct file *in, loff_t __user *off_in,
1048 struct file *out, loff_t __user *off_out,
1049 size_t len, unsigned int flags)
5274f052 1050{
3a326a2c 1051 struct pipe_inode_info *pipe;
cbb7e577 1052 loff_t offset, *off;
a4514ebd 1053 long ret;
5274f052 1054
3a326a2c 1055 pipe = in->f_dentry->d_inode->i_pipe;
529565dc
IM
1056 if (pipe) {
1057 if (off_in)
1058 return -ESPIPE;
b92ce558
JA
1059 if (off_out) {
1060 if (out->f_op->llseek == no_llseek)
1061 return -EINVAL;
cbb7e577 1062 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
b92ce558 1063 return -EFAULT;
cbb7e577
JA
1064 off = &offset;
1065 } else
1066 off = &out->f_pos;
529565dc 1067
a4514ebd
JA
1068 ret = do_splice_from(pipe, out, off, len, flags);
1069
1070 if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
1071 ret = -EFAULT;
1072
1073 return ret;
529565dc 1074 }
5274f052 1075
3a326a2c 1076 pipe = out->f_dentry->d_inode->i_pipe;
529565dc
IM
1077 if (pipe) {
1078 if (off_out)
1079 return -ESPIPE;
b92ce558
JA
1080 if (off_in) {
1081 if (in->f_op->llseek == no_llseek)
1082 return -EINVAL;
cbb7e577 1083 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
b92ce558 1084 return -EFAULT;
cbb7e577
JA
1085 off = &offset;
1086 } else
1087 off = &in->f_pos;
529565dc 1088
a4514ebd
JA
1089 ret = do_splice_to(in, off, pipe, len, flags);
1090
1091 if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
1092 ret = -EFAULT;
1093
1094 return ret;
529565dc 1095 }
5274f052
JA
1096
1097 return -EINVAL;
1098}
1099
912d35f8
JA
1100/*
1101 * Map an iov into an array of pages and offset/length tupples. With the
1102 * partial_page structure, we can map several non-contiguous ranges into
1103 * our ones pages[] map instead of splitting that operation into pieces.
1104 * Could easily be exported as a generic helper for other users, in which
1105 * case one would probably want to add a 'max_nr_pages' parameter as well.
1106 */
1107static int get_iovec_page_array(const struct iovec __user *iov,
1108 unsigned int nr_vecs, struct page **pages,
7afa6fd0 1109 struct partial_page *partial, int aligned)
912d35f8
JA
1110{
1111 int buffers = 0, error = 0;
1112
1113 /*
1114 * It's ok to take the mmap_sem for reading, even
1115 * across a "get_user()".
1116 */
1117 down_read(&current->mm->mmap_sem);
1118
1119 while (nr_vecs) {
1120 unsigned long off, npages;
1121 void __user *base;
1122 size_t len;
1123 int i;
1124
1125 /*
1126 * Get user address base and length for this iovec.
1127 */
1128 error = get_user(base, &iov->iov_base);
1129 if (unlikely(error))
1130 break;
1131 error = get_user(len, &iov->iov_len);
1132 if (unlikely(error))
1133 break;
1134
1135 /*
1136 * Sanity check this iovec. 0 read succeeds.
1137 */
1138 if (unlikely(!len))
1139 break;
1140 error = -EFAULT;
1141 if (unlikely(!base))
1142 break;
1143
1144 /*
1145 * Get this base offset and number of pages, then map
1146 * in the user pages.
1147 */
1148 off = (unsigned long) base & ~PAGE_MASK;
7afa6fd0
JA
1149
1150 /*
1151 * If asked for alignment, the offset must be zero and the
1152 * length a multiple of the PAGE_SIZE.
1153 */
1154 error = -EINVAL;
1155 if (aligned && (off || len & ~PAGE_MASK))
1156 break;
1157
912d35f8
JA
1158 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1159 if (npages > PIPE_BUFFERS - buffers)
1160 npages = PIPE_BUFFERS - buffers;
1161
1162 error = get_user_pages(current, current->mm,
1163 (unsigned long) base, npages, 0, 0,
1164 &pages[buffers], NULL);
1165
1166 if (unlikely(error <= 0))
1167 break;
1168
1169 /*
1170 * Fill this contiguous range into the partial page map.
1171 */
1172 for (i = 0; i < error; i++) {
7591489a 1173 const int plen = min_t(size_t, len, PAGE_SIZE - off);
912d35f8
JA
1174
1175 partial[buffers].offset = off;
1176 partial[buffers].len = plen;
1177
1178 off = 0;
1179 len -= plen;
1180 buffers++;
1181 }
1182
1183 /*
1184 * We didn't complete this iov, stop here since it probably
1185 * means we have to move some of this into a pipe to
1186 * be able to continue.
1187 */
1188 if (len)
1189 break;
1190
1191 /*
1192 * Don't continue if we mapped fewer pages than we asked for,
1193 * or if we mapped the max number of pages that we have
1194 * room for.
1195 */
1196 if (error < npages || buffers == PIPE_BUFFERS)
1197 break;
1198
1199 nr_vecs--;
1200 iov++;
1201 }
1202
1203 up_read(&current->mm->mmap_sem);
1204
1205 if (buffers)
1206 return buffers;
1207
1208 return error;
1209}
1210
1211/*
1212 * vmsplice splices a user address range into a pipe. It can be thought of
1213 * as splice-from-memory, where the regular splice is splice-from-file (or
1214 * to file). In both cases the output is a pipe, naturally.
1215 *
1216 * Note that vmsplice only supports splicing _from_ user memory to a pipe,
1217 * not the other way around. Splicing from user memory is a simple operation
1218 * that can be supported without any funky alignment restrictions or nasty
1219 * vm tricks. We simply map in the user memory and fill them into a pipe.
1220 * The reverse isn't quite as easy, though. There are two possible solutions
1221 * for that:
1222 *
1223 * - memcpy() the data internally, at which point we might as well just
1224 * do a regular read() on the buffer anyway.
1225 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1226 * has restriction limitations on both ends of the pipe).
1227 *
1228 * Alas, it isn't here.
1229 *
1230 */
1231static long do_vmsplice(struct file *file, const struct iovec __user *iov,
1232 unsigned long nr_segs, unsigned int flags)
1233{
1234 struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe;
1235 struct page *pages[PIPE_BUFFERS];
1236 struct partial_page partial[PIPE_BUFFERS];
1237 struct splice_pipe_desc spd = {
1238 .pages = pages,
1239 .partial = partial,
1240 .flags = flags,
1241 .ops = &user_page_pipe_buf_ops,
1242 };
1243
1244 if (unlikely(!pipe))
1245 return -EBADF;
1246 if (unlikely(nr_segs > UIO_MAXIOV))
1247 return -EINVAL;
1248 else if (unlikely(!nr_segs))
1249 return 0;
1250
7afa6fd0
JA
1251 spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
1252 flags & SPLICE_F_GIFT);
912d35f8
JA
1253 if (spd.nr_pages <= 0)
1254 return spd.nr_pages;
1255
00522fb4 1256 return splice_to_pipe(pipe, &spd);
912d35f8
JA
1257}
1258
1259asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
1260 unsigned long nr_segs, unsigned int flags)
1261{
1262 struct file *file;
1263 long error;
1264 int fput;
1265
1266 error = -EBADF;
1267 file = fget_light(fd, &fput);
1268 if (file) {
1269 if (file->f_mode & FMODE_WRITE)
1270 error = do_vmsplice(file, iov, nr_segs, flags);
1271
1272 fput_light(file, fput);
1273 }
1274
1275 return error;
1276}
1277
529565dc
IM
1278asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
1279 int fd_out, loff_t __user *off_out,
1280 size_t len, unsigned int flags)
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1281{
1282 long error;
1283 struct file *in, *out;
1284 int fput_in, fput_out;
1285
1286 if (unlikely(!len))
1287 return 0;
1288
1289 error = -EBADF;
529565dc 1290 in = fget_light(fd_in, &fput_in);
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1291 if (in) {
1292 if (in->f_mode & FMODE_READ) {
529565dc 1293 out = fget_light(fd_out, &fput_out);
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1294 if (out) {
1295 if (out->f_mode & FMODE_WRITE)
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1296 error = do_splice(in, off_in,
1297 out, off_out,
1298 len, flags);
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1299 fput_light(out, fput_out);
1300 }
1301 }
1302
1303 fput_light(in, fput_in);
1304 }
1305
1306 return error;
1307}
70524490 1308
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1309/*
1310 * Make sure there's data to read. Wait for input if we can, otherwise
1311 * return an appropriate error.
1312 */
1313static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1314{
1315 int ret;
1316
1317 /*
1318 * Check ->nrbufs without the inode lock first. This function
1319 * is speculative anyways, so missing one is ok.
1320 */
1321 if (pipe->nrbufs)
1322 return 0;
1323
1324 ret = 0;
1325 mutex_lock(&pipe->inode->i_mutex);
1326
1327 while (!pipe->nrbufs) {
1328 if (signal_pending(current)) {
1329 ret = -ERESTARTSYS;
1330 break;
1331 }
1332 if (!pipe->writers)
1333 break;
1334 if (!pipe->waiting_writers) {
1335 if (flags & SPLICE_F_NONBLOCK) {
1336 ret = -EAGAIN;
1337 break;
1338 }
1339 }
1340 pipe_wait(pipe);
1341 }
1342
1343 mutex_unlock(&pipe->inode->i_mutex);
1344 return ret;
1345}
1346
1347/*
1348 * Make sure there's writeable room. Wait for room if we can, otherwise
1349 * return an appropriate error.
1350 */
1351static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1352{
1353 int ret;
1354
1355 /*
1356 * Check ->nrbufs without the inode lock first. This function
1357 * is speculative anyways, so missing one is ok.
1358 */
1359 if (pipe->nrbufs < PIPE_BUFFERS)
1360 return 0;
1361
1362 ret = 0;
1363 mutex_lock(&pipe->inode->i_mutex);
1364
1365 while (pipe->nrbufs >= PIPE_BUFFERS) {
1366 if (!pipe->readers) {
1367 send_sig(SIGPIPE, current, 0);
1368 ret = -EPIPE;
1369 break;
1370 }
1371 if (flags & SPLICE_F_NONBLOCK) {
1372 ret = -EAGAIN;
1373 break;
1374 }
1375 if (signal_pending(current)) {
1376 ret = -ERESTARTSYS;
1377 break;
1378 }
1379 pipe->waiting_writers++;
1380 pipe_wait(pipe);
1381 pipe->waiting_writers--;
1382 }
1383
1384 mutex_unlock(&pipe->inode->i_mutex);
1385 return ret;
1386}
1387
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1388/*
1389 * Link contents of ipipe to opipe.
1390 */
1391static int link_pipe(struct pipe_inode_info *ipipe,
1392 struct pipe_inode_info *opipe,
1393 size_t len, unsigned int flags)
1394{
1395 struct pipe_buffer *ibuf, *obuf;
aadd06e5 1396 int ret = 0, i = 0, nbuf;
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1397
1398 /*
1399 * Potential ABBA deadlock, work around it by ordering lock
1400 * grabbing by inode address. Otherwise two different processes
1401 * could deadlock (one doing tee from A -> B, the other from B -> A).
1402 */
1403 if (ipipe->inode < opipe->inode) {
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1404 mutex_lock_nested(&ipipe->inode->i_mutex, I_MUTEX_PARENT);
1405 mutex_lock_nested(&opipe->inode->i_mutex, I_MUTEX_CHILD);
70524490 1406 } else {
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1407 mutex_lock_nested(&opipe->inode->i_mutex, I_MUTEX_PARENT);
1408 mutex_lock_nested(&ipipe->inode->i_mutex, I_MUTEX_CHILD);
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1409 }
1410
aadd06e5 1411 do {
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1412 if (!opipe->readers) {
1413 send_sig(SIGPIPE, current, 0);
1414 if (!ret)
1415 ret = -EPIPE;
1416 break;
1417 }
70524490 1418
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1419 /*
1420 * If we have iterated all input buffers or ran out of
1421 * output room, break.
1422 */
1423 if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS)
1424 break;
70524490 1425
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1426 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
1427 nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
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1428
1429 /*
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1430 * Get a reference to this pipe buffer,
1431 * so we can copy the contents over.
70524490 1432 */
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1433 ibuf->ops->get(ipipe, ibuf);
1434
1435 obuf = opipe->bufs + nbuf;
1436 *obuf = *ibuf;
1437
2a27250e 1438 /*
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1439 * Don't inherit the gift flag, we need to
1440 * prevent multiple steals of this page.
2a27250e 1441 */
aadd06e5 1442 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
70524490 1443
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1444 if (obuf->len > len)
1445 obuf->len = len;
70524490 1446
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1447 opipe->nrbufs++;
1448 ret += obuf->len;
1449 len -= obuf->len;
1450 i++;
1451 } while (len);
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1452
1453 mutex_unlock(&ipipe->inode->i_mutex);
1454 mutex_unlock(&opipe->inode->i_mutex);
1455
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1456 /*
1457 * If we put data in the output pipe, wakeup any potential readers.
1458 */
1459 if (ret > 0) {
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1460 smp_mb();
1461 if (waitqueue_active(&opipe->wait))
1462 wake_up_interruptible(&opipe->wait);
1463 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1464 }
1465
1466 return ret;
1467}
1468
1469/*
1470 * This is a tee(1) implementation that works on pipes. It doesn't copy
1471 * any data, it simply references the 'in' pages on the 'out' pipe.
1472 * The 'flags' used are the SPLICE_F_* variants, currently the only
1473 * applicable one is SPLICE_F_NONBLOCK.
1474 */
1475static long do_tee(struct file *in, struct file *out, size_t len,
1476 unsigned int flags)
1477{
1478 struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
1479 struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
aadd06e5 1480 int ret = -EINVAL;
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1481
1482 /*
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1483 * Duplicate the contents of ipipe to opipe without actually
1484 * copying the data.
70524490 1485 */
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1486 if (ipipe && opipe && ipipe != opipe) {
1487 /*
1488 * Keep going, unless we encounter an error. The ipipe/opipe
1489 * ordering doesn't really matter.
1490 */
1491 ret = link_ipipe_prep(ipipe, flags);
1492 if (!ret) {
1493 ret = link_opipe_prep(opipe, flags);
1494 if (!ret) {
1495 ret = link_pipe(ipipe, opipe, len, flags);
1496 if (!ret && (flags & SPLICE_F_NONBLOCK))
1497 ret = -EAGAIN;
1498 }
1499 }
1500 }
70524490 1501
aadd06e5 1502 return ret;
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1503}
1504
1505asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
1506{
1507 struct file *in;
1508 int error, fput_in;
1509
1510 if (unlikely(!len))
1511 return 0;
1512
1513 error = -EBADF;
1514 in = fget_light(fdin, &fput_in);
1515 if (in) {
1516 if (in->f_mode & FMODE_READ) {
1517 int fput_out;
1518 struct file *out = fget_light(fdout, &fput_out);
1519
1520 if (out) {
1521 if (out->f_mode & FMODE_WRITE)
1522 error = do_tee(in, out, len, flags);
1523 fput_light(out, fput_out);
1524 }
1525 }
1526 fput_light(in, fput_in);
1527 }
1528
1529 return error;
1530}