Root/
1 | /* |
2 | * "splice": joining two ropes together by interweaving their strands. |
3 | * |
4 | * This is the "extended pipe" functionality, where a pipe is used as |
5 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel |
6 | * buffer that you can use to transfer data from one end to the other. |
7 | * |
8 | * The traditional unix read/write is extended with a "splice()" operation |
9 | * that transfers data buffers to or from a pipe buffer. |
10 | * |
11 | * Named by Larry McVoy, original implementation from Linus, extended by |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. |
14 | * |
15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> |
18 | * |
19 | */ |
20 | #include <linux/fs.h> |
21 | #include <linux/file.h> |
22 | #include <linux/pagemap.h> |
23 | #include <linux/splice.h> |
24 | #include <linux/memcontrol.h> |
25 | #include <linux/mm_inline.h> |
26 | #include <linux/swap.h> |
27 | #include <linux/writeback.h> |
28 | #include <linux/export.h> |
29 | #include <linux/syscalls.h> |
30 | #include <linux/uio.h> |
31 | #include <linux/security.h> |
32 | #include <linux/gfp.h> |
33 | #include <linux/socket.h> |
34 | #include <linux/compat.h> |
35 | #include <linux/aio.h> |
36 | #include "internal.h" |
37 | |
38 | /* |
39 | * Attempt to steal a page from a pipe buffer. This should perhaps go into |
40 | * a vm helper function, it's already simplified quite a bit by the |
41 | * addition of remove_mapping(). If success is returned, the caller may |
42 | * attempt to reuse this page for another destination. |
43 | */ |
44 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
45 | struct pipe_buffer *buf) |
46 | { |
47 | struct page *page = buf->page; |
48 | struct address_space *mapping; |
49 | |
50 | lock_page(page); |
51 | |
52 | mapping = page_mapping(page); |
53 | if (mapping) { |
54 | WARN_ON(!PageUptodate(page)); |
55 | |
56 | /* |
57 | * At least for ext2 with nobh option, we need to wait on |
58 | * writeback completing on this page, since we'll remove it |
59 | * from the pagecache. Otherwise truncate wont wait on the |
60 | * page, allowing the disk blocks to be reused by someone else |
61 | * before we actually wrote our data to them. fs corruption |
62 | * ensues. |
63 | */ |
64 | wait_on_page_writeback(page); |
65 | |
66 | if (page_has_private(page) && |
67 | !try_to_release_page(page, GFP_KERNEL)) |
68 | goto out_unlock; |
69 | |
70 | /* |
71 | * If we succeeded in removing the mapping, set LRU flag |
72 | * and return good. |
73 | */ |
74 | if (remove_mapping(mapping, page)) { |
75 | buf->flags |= PIPE_BUF_FLAG_LRU; |
76 | return 0; |
77 | } |
78 | } |
79 | |
80 | /* |
81 | * Raced with truncate or failed to remove page from current |
82 | * address space, unlock and return failure. |
83 | */ |
84 | out_unlock: |
85 | unlock_page(page); |
86 | return 1; |
87 | } |
88 | |
89 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
90 | struct pipe_buffer *buf) |
91 | { |
92 | page_cache_release(buf->page); |
93 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
94 | } |
95 | |
96 | /* |
97 | * Check whether the contents of buf is OK to access. Since the content |
98 | * is a page cache page, IO may be in flight. |
99 | */ |
100 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
101 | struct pipe_buffer *buf) |
102 | { |
103 | struct page *page = buf->page; |
104 | int err; |
105 | |
106 | if (!PageUptodate(page)) { |
107 | lock_page(page); |
108 | |
109 | /* |
110 | * Page got truncated/unhashed. This will cause a 0-byte |
111 | * splice, if this is the first page. |
112 | */ |
113 | if (!page->mapping) { |
114 | err = -ENODATA; |
115 | goto error; |
116 | } |
117 | |
118 | /* |
119 | * Uh oh, read-error from disk. |
120 | */ |
121 | if (!PageUptodate(page)) { |
122 | err = -EIO; |
123 | goto error; |
124 | } |
125 | |
126 | /* |
127 | * Page is ok afterall, we are done. |
128 | */ |
129 | unlock_page(page); |
130 | } |
131 | |
132 | return 0; |
133 | error: |
134 | unlock_page(page); |
135 | return err; |
136 | } |
137 | |
138 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
139 | .can_merge = 0, |
140 | .confirm = page_cache_pipe_buf_confirm, |
141 | .release = page_cache_pipe_buf_release, |
142 | .steal = page_cache_pipe_buf_steal, |
143 | .get = generic_pipe_buf_get, |
144 | }; |
145 | |
146 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
147 | struct pipe_buffer *buf) |
148 | { |
149 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
150 | return 1; |
151 | |
152 | buf->flags |= PIPE_BUF_FLAG_LRU; |
153 | return generic_pipe_buf_steal(pipe, buf); |
154 | } |
155 | |
156 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
157 | .can_merge = 0, |
158 | .confirm = generic_pipe_buf_confirm, |
159 | .release = page_cache_pipe_buf_release, |
160 | .steal = user_page_pipe_buf_steal, |
161 | .get = generic_pipe_buf_get, |
162 | }; |
163 | |
164 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
165 | { |
166 | smp_mb(); |
167 | if (waitqueue_active(&pipe->wait)) |
168 | wake_up_interruptible(&pipe->wait); |
169 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
170 | } |
171 | |
172 | /** |
173 | * splice_to_pipe - fill passed data into a pipe |
174 | * @pipe: pipe to fill |
175 | * @spd: data to fill |
176 | * |
177 | * Description: |
178 | * @spd contains a map of pages and len/offset tuples, along with |
179 | * the struct pipe_buf_operations associated with these pages. This |
180 | * function will link that data to the pipe. |
181 | * |
182 | */ |
183 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
184 | struct splice_pipe_desc *spd) |
185 | { |
186 | unsigned int spd_pages = spd->nr_pages; |
187 | int ret, do_wakeup, page_nr; |
188 | |
189 | ret = 0; |
190 | do_wakeup = 0; |
191 | page_nr = 0; |
192 | |
193 | pipe_lock(pipe); |
194 | |
195 | for (;;) { |
196 | if (!pipe->readers) { |
197 | send_sig(SIGPIPE, current, 0); |
198 | if (!ret) |
199 | ret = -EPIPE; |
200 | break; |
201 | } |
202 | |
203 | if (pipe->nrbufs < pipe->buffers) { |
204 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); |
205 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
206 | |
207 | buf->page = spd->pages[page_nr]; |
208 | buf->offset = spd->partial[page_nr].offset; |
209 | buf->len = spd->partial[page_nr].len; |
210 | buf->private = spd->partial[page_nr].private; |
211 | buf->ops = spd->ops; |
212 | if (spd->flags & SPLICE_F_GIFT) |
213 | buf->flags |= PIPE_BUF_FLAG_GIFT; |
214 | |
215 | pipe->nrbufs++; |
216 | page_nr++; |
217 | ret += buf->len; |
218 | |
219 | if (pipe->files) |
220 | do_wakeup = 1; |
221 | |
222 | if (!--spd->nr_pages) |
223 | break; |
224 | if (pipe->nrbufs < pipe->buffers) |
225 | continue; |
226 | |
227 | break; |
228 | } |
229 | |
230 | if (spd->flags & SPLICE_F_NONBLOCK) { |
231 | if (!ret) |
232 | ret = -EAGAIN; |
233 | break; |
234 | } |
235 | |
236 | if (signal_pending(current)) { |
237 | if (!ret) |
238 | ret = -ERESTARTSYS; |
239 | break; |
240 | } |
241 | |
242 | if (do_wakeup) { |
243 | smp_mb(); |
244 | if (waitqueue_active(&pipe->wait)) |
245 | wake_up_interruptible_sync(&pipe->wait); |
246 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
247 | do_wakeup = 0; |
248 | } |
249 | |
250 | pipe->waiting_writers++; |
251 | pipe_wait(pipe); |
252 | pipe->waiting_writers--; |
253 | } |
254 | |
255 | pipe_unlock(pipe); |
256 | |
257 | if (do_wakeup) |
258 | wakeup_pipe_readers(pipe); |
259 | |
260 | while (page_nr < spd_pages) |
261 | spd->spd_release(spd, page_nr++); |
262 | |
263 | return ret; |
264 | } |
265 | |
266 | void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
267 | { |
268 | page_cache_release(spd->pages[i]); |
269 | } |
270 | |
271 | /* |
272 | * Check if we need to grow the arrays holding pages and partial page |
273 | * descriptions. |
274 | */ |
275 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
276 | { |
277 | unsigned int buffers = ACCESS_ONCE(pipe->buffers); |
278 | |
279 | spd->nr_pages_max = buffers; |
280 | if (buffers <= PIPE_DEF_BUFFERS) |
281 | return 0; |
282 | |
283 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); |
284 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); |
285 | |
286 | if (spd->pages && spd->partial) |
287 | return 0; |
288 | |
289 | kfree(spd->pages); |
290 | kfree(spd->partial); |
291 | return -ENOMEM; |
292 | } |
293 | |
294 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
295 | { |
296 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
297 | return; |
298 | |
299 | kfree(spd->pages); |
300 | kfree(spd->partial); |
301 | } |
302 | |
303 | static int |
304 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
305 | struct pipe_inode_info *pipe, size_t len, |
306 | unsigned int flags) |
307 | { |
308 | struct address_space *mapping = in->f_mapping; |
309 | unsigned int loff, nr_pages, req_pages; |
310 | struct page *pages[PIPE_DEF_BUFFERS]; |
311 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
312 | struct page *page; |
313 | pgoff_t index, end_index; |
314 | loff_t isize; |
315 | int error, page_nr; |
316 | struct splice_pipe_desc spd = { |
317 | .pages = pages, |
318 | .partial = partial, |
319 | .nr_pages_max = PIPE_DEF_BUFFERS, |
320 | .flags = flags, |
321 | .ops = &page_cache_pipe_buf_ops, |
322 | .spd_release = spd_release_page, |
323 | }; |
324 | |
325 | if (splice_grow_spd(pipe, &spd)) |
326 | return -ENOMEM; |
327 | |
328 | index = *ppos >> PAGE_CACHE_SHIFT; |
329 | loff = *ppos & ~PAGE_CACHE_MASK; |
330 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
331 | nr_pages = min(req_pages, spd.nr_pages_max); |
332 | |
333 | /* |
334 | * Lookup the (hopefully) full range of pages we need. |
335 | */ |
336 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); |
337 | index += spd.nr_pages; |
338 | |
339 | /* |
340 | * If find_get_pages_contig() returned fewer pages than we needed, |
341 | * readahead/allocate the rest and fill in the holes. |
342 | */ |
343 | if (spd.nr_pages < nr_pages) |
344 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
345 | index, req_pages - spd.nr_pages); |
346 | |
347 | error = 0; |
348 | while (spd.nr_pages < nr_pages) { |
349 | /* |
350 | * Page could be there, find_get_pages_contig() breaks on |
351 | * the first hole. |
352 | */ |
353 | page = find_get_page(mapping, index); |
354 | if (!page) { |
355 | /* |
356 | * page didn't exist, allocate one. |
357 | */ |
358 | page = page_cache_alloc_cold(mapping); |
359 | if (!page) |
360 | break; |
361 | |
362 | error = add_to_page_cache_lru(page, mapping, index, |
363 | GFP_KERNEL); |
364 | if (unlikely(error)) { |
365 | page_cache_release(page); |
366 | if (error == -EEXIST) |
367 | continue; |
368 | break; |
369 | } |
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); |
375 | } |
376 | |
377 | spd.pages[spd.nr_pages++] = page; |
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); |
398 | page = spd.pages[page_nr]; |
399 | |
400 | if (PageReadahead(page)) |
401 | page_cache_async_readahead(mapping, &in->f_ra, in, |
402 | page, index, req_pages - page_nr); |
403 | |
404 | /* |
405 | * If the page isn't uptodate, we may need to start io on it |
406 | */ |
407 | if (!PageUptodate(page)) { |
408 | lock_page(page); |
409 | |
410 | /* |
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. |
415 | */ |
416 | if (!page->mapping) { |
417 | unlock_page(page); |
418 | page = find_or_create_page(mapping, index, |
419 | mapping_gfp_mask(mapping)); |
420 | |
421 | if (!page) { |
422 | error = -ENOMEM; |
423 | break; |
424 | } |
425 | page_cache_release(spd.pages[page_nr]); |
426 | spd.pages[page_nr] = page; |
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 | } |
435 | |
436 | /* |
437 | * need to read in the page |
438 | */ |
439 | error = mapping->a_ops->readpage(in, page); |
440 | if (unlikely(error)) { |
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 | */ |
447 | if (error == AOP_TRUNCATED_PAGE) |
448 | error = 0; |
449 | |
450 | break; |
451 | } |
452 | } |
453 | fill_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; |
468 | |
469 | /* |
470 | * max good bytes in this page |
471 | */ |
472 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
473 | if (plen <= loff) |
474 | break; |
475 | |
476 | /* |
477 | * force quit after adding this page |
478 | */ |
479 | this_len = min(this_len, plen - loff); |
480 | len = this_len; |
481 | } |
482 | |
483 | spd.partial[page_nr].offset = loff; |
484 | spd.partial[page_nr].len = this_len; |
485 | len -= this_len; |
486 | loff = 0; |
487 | spd.nr_pages++; |
488 | index++; |
489 | } |
490 | |
491 | /* |
492 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
493 | * we got, 'nr_pages' is how many pages are in the map. |
494 | */ |
495 | while (page_nr < nr_pages) |
496 | page_cache_release(spd.pages[page_nr++]); |
497 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
498 | |
499 | if (spd.nr_pages) |
500 | error = splice_to_pipe(pipe, &spd); |
501 | |
502 | splice_shrink_spd(&spd); |
503 | return error; |
504 | } |
505 | |
506 | /** |
507 | * generic_file_splice_read - splice data from file to a pipe |
508 | * @in: file to splice from |
509 | * @ppos: position in @in |
510 | * @pipe: pipe to splice to |
511 | * @len: number of bytes to splice |
512 | * @flags: splice modifier flags |
513 | * |
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 | * |
519 | */ |
520 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
521 | struct pipe_inode_info *pipe, size_t len, |
522 | unsigned int flags) |
523 | { |
524 | loff_t isize, left; |
525 | int ret; |
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; |
534 | |
535 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
536 | if (ret > 0) { |
537 | *ppos += ret; |
538 | file_accessed(in); |
539 | } |
540 | |
541 | return ret; |
542 | } |
543 | EXPORT_SYMBOL(generic_file_splice_read); |
544 | |
545 | static const struct pipe_buf_operations default_pipe_buf_ops = { |
546 | .can_merge = 0, |
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 | |
553 | static 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. */ |
560 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { |
561 | .can_merge = 0, |
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 | }; |
567 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); |
568 | |
569 | static 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 | |
585 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
586 | loff_t pos) |
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() */ |
594 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); |
595 | set_fs(old_fs); |
596 | |
597 | return res; |
598 | } |
599 | EXPORT_SYMBOL(kernel_write); |
600 | |
601 | ssize_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; |
608 | struct page *pages[PIPE_DEF_BUFFERS]; |
609 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
610 | struct iovec *vec, __vec[PIPE_DEF_BUFFERS]; |
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, |
618 | .nr_pages_max = PIPE_DEF_BUFFERS, |
619 | .flags = flags, |
620 | .ops = &default_pipe_buf_ops, |
621 | .spd_release = spd_release_page, |
622 | }; |
623 | |
624 | if (splice_grow_spd(pipe, &spd)) |
625 | return -ENOMEM; |
626 | |
627 | res = -ENOMEM; |
628 | vec = __vec; |
629 | if (spd.nr_pages_max > PIPE_DEF_BUFFERS) { |
630 | vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL); |
631 | if (!vec) |
632 | goto shrink_ret; |
633 | } |
634 | |
635 | offset = *ppos & ~PAGE_CACHE_MASK; |
636 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
637 | |
638 | for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) { |
639 | struct page *page; |
640 | |
641 | page = alloc_page(GFP_USER); |
642 | error = -ENOMEM; |
643 | if (!page) |
644 | goto err; |
645 | |
646 | this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); |
647 | vec[i].iov_base = (void __user *) page_address(page); |
648 | vec[i].iov_len = this_len; |
649 | spd.pages[i] = page; |
650 | spd.nr_pages++; |
651 | len -= this_len; |
652 | offset = 0; |
653 | } |
654 | |
655 | res = kernel_readv(in, vec, spd.nr_pages, *ppos); |
656 | if (res < 0) { |
657 | error = res; |
658 | goto err; |
659 | } |
660 | |
661 | error = 0; |
662 | if (!res) |
663 | goto err; |
664 | |
665 | nr_freed = 0; |
666 | for (i = 0; i < spd.nr_pages; i++) { |
667 | this_len = min_t(size_t, vec[i].iov_len, res); |
668 | spd.partial[i].offset = 0; |
669 | spd.partial[i].len = this_len; |
670 | if (!this_len) { |
671 | __free_page(spd.pages[i]); |
672 | spd.pages[i] = NULL; |
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 | |
683 | shrink_ret: |
684 | if (vec != __vec) |
685 | kfree(vec); |
686 | splice_shrink_spd(&spd); |
687 | return res; |
688 | |
689 | err: |
690 | for (i = 0; i < spd.nr_pages; i++) |
691 | __free_page(spd.pages[i]); |
692 | |
693 | res = error; |
694 | goto shrink_ret; |
695 | } |
696 | EXPORT_SYMBOL(default_file_splice_read); |
697 | |
698 | /* |
699 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
700 | * using sendpage(). Return the number of bytes sent. |
701 | */ |
702 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
703 | struct pipe_buffer *buf, struct splice_desc *sd) |
704 | { |
705 | struct file *file = sd->u.file; |
706 | loff_t pos = sd->pos; |
707 | int more; |
708 | |
709 | if (!likely(file->f_op->sendpage)) |
710 | return -EINVAL; |
711 | |
712 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
713 | |
714 | if (sd->len < sd->total_len && pipe->nrbufs > 1) |
715 | more |= MSG_SENDPAGE_NOTLAST; |
716 | |
717 | return file->f_op->sendpage(file, buf->page, buf->offset, |
718 | sd->len, &pos, more); |
719 | } |
720 | |
721 | static 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 | |
729 | /** |
730 | * splice_from_pipe_feed - feed available data from a pipe to a file |
731 | * @pipe: pipe to splice from |
732 | * @sd: information to @actor |
733 | * @actor: handler that splices the data |
734 | * |
735 | * Description: |
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. |
743 | * |
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. |
748 | */ |
749 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
750 | splice_actor *actor) |
751 | { |
752 | int ret; |
753 | |
754 | while (pipe->nrbufs) { |
755 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
756 | const struct pipe_buf_operations *ops = buf->ops; |
757 | |
758 | sd->len = buf->len; |
759 | if (sd->len > sd->total_len) |
760 | sd->len = sd->total_len; |
761 | |
762 | ret = buf->ops->confirm(pipe, buf); |
763 | if (unlikely(ret)) { |
764 | if (ret == -ENODATA) |
765 | ret = 0; |
766 | return ret; |
767 | } |
768 | |
769 | ret = actor(pipe, buf, sd); |
770 | if (ret <= 0) |
771 | return ret; |
772 | |
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); |
784 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
785 | pipe->nrbufs--; |
786 | if (pipe->files) |
787 | sd->need_wakeup = true; |
788 | } |
789 | |
790 | if (!sd->total_len) |
791 | return 0; |
792 | } |
793 | |
794 | return 1; |
795 | } |
796 | |
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 | */ |
807 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
808 | { |
809 | while (!pipe->nrbufs) { |
810 | if (!pipe->writers) |
811 | return 0; |
812 | |
813 | if (!pipe->waiting_writers && sd->num_spliced) |
814 | return 0; |
815 | |
816 | if (sd->flags & SPLICE_F_NONBLOCK) |
817 | return -EAGAIN; |
818 | |
819 | if (signal_pending(current)) |
820 | return -ERESTARTSYS; |
821 | |
822 | if (sd->need_wakeup) { |
823 | wakeup_pipe_writers(pipe); |
824 | sd->need_wakeup = false; |
825 | } |
826 | |
827 | pipe_wait(pipe); |
828 | } |
829 | |
830 | return 1; |
831 | } |
832 | |
833 | /** |
834 | * splice_from_pipe_begin - start splicing from pipe |
835 | * @sd: information about the splice operation |
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 | */ |
842 | static void splice_from_pipe_begin(struct splice_desc *sd) |
843 | { |
844 | sd->num_spliced = 0; |
845 | sd->need_wakeup = false; |
846 | } |
847 | |
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 | */ |
858 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
859 | { |
860 | if (sd->need_wakeup) |
861 | wakeup_pipe_writers(pipe); |
862 | } |
863 | |
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 | */ |
877 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
878 | splice_actor *actor) |
879 | { |
880 | int ret; |
881 | |
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; |
891 | } |
892 | EXPORT_SYMBOL(__splice_from_pipe); |
893 | |
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: |
904 | * See __splice_from_pipe. This function locks the pipe inode, |
905 | * otherwise it's identical to __splice_from_pipe(). |
906 | * |
907 | */ |
908 | ssize_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; |
913 | struct splice_desc sd = { |
914 | .total_len = len, |
915 | .flags = flags, |
916 | .pos = *ppos, |
917 | .u.file = out, |
918 | }; |
919 | |
920 | pipe_lock(pipe); |
921 | ret = __splice_from_pipe(pipe, &sd, actor); |
922 | pipe_unlock(pipe); |
923 | |
924 | return ret; |
925 | } |
926 | |
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 | */ |
941 | ssize_t |
942 | iter_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; |
964 | struct kiocb kiocb; |
965 | size_t left; |
966 | int n, idx; |
967 | |
968 | ret = splice_from_pipe_next(pipe, &sd); |
969 | if (ret <= 0) |
970 | break; |
971 | |
972 | if (unlikely(nbufs < pipe->buffers)) { |
973 | kfree(array); |
974 | nbufs = pipe->buffers; |
975 | array = kcalloc(nbufs, sizeof(struct bio_vec), |
976 | GFP_KERNEL); |
977 | if (!array) { |
978 | ret = -ENOMEM; |
979 | break; |
980 | } |
981 | } |
982 | |
983 | /* build the vector */ |
984 | left = sd.total_len; |
985 | for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) { |
986 | struct pipe_buffer *buf = pipe->bufs + idx; |
987 | size_t this_len = buf->len; |
988 | |
989 | if (this_len > left) |
990 | this_len = left; |
991 | |
992 | if (idx == pipe->buffers - 1) |
993 | idx = -1; |
994 | |
995 | ret = buf->ops->confirm(pipe, buf); |
996 | if (unlikely(ret)) { |
997 | if (ret == -ENODATA) |
998 | ret = 0; |
999 | goto done; |
1000 | } |
1001 | |
1002 | array[n].bv_page = buf->page; |
1003 | array[n].bv_len = this_len; |
1004 | array[n].bv_offset = buf->offset; |
1005 | left -= this_len; |
1006 | } |
1007 | |
1008 | /* ... iov_iter */ |
1009 | from.type = ITER_BVEC | WRITE; |
1010 | from.bvec = array; |
1011 | from.nr_segs = n; |
1012 | from.count = sd.total_len - left; |
1013 | from.iov_offset = 0; |
1014 | |
1015 | /* ... and iocb */ |
1016 | init_sync_kiocb(&kiocb, out); |
1017 | kiocb.ki_pos = sd.pos; |
1018 | kiocb.ki_nbytes = sd.total_len - left; |
1019 | |
1020 | /* now, send it */ |
1021 | ret = out->f_op->write_iter(&kiocb, &from); |
1022 | if (-EIOCBQUEUED == ret) |
1023 | ret = wait_on_sync_kiocb(&kiocb); |
1024 | |
1025 | if (ret <= 0) |
1026 | break; |
1027 | |
1028 | sd.num_spliced += ret; |
1029 | sd.total_len -= ret; |
1030 | *ppos = sd.pos = kiocb.ki_pos; |
1031 | |
1032 | /* dismiss the fully eaten buffers, adjust the partial one */ |
1033 | while (ret) { |
1034 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
1035 | if (ret >= buf->len) { |
1036 | const struct pipe_buf_operations *ops = buf->ops; |
1037 | ret -= buf->len; |
1038 | buf->len = 0; |
1039 | buf->ops = NULL; |
1040 | ops->release(pipe, buf); |
1041 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
1042 | pipe->nrbufs--; |
1043 | if (pipe->files) |
1044 | sd.need_wakeup = true; |
1045 | } else { |
1046 | buf->offset += ret; |
1047 | buf->len -= ret; |
1048 | ret = 0; |
1049 | } |
1050 | } |
1051 | } |
1052 | done: |
1053 | kfree(array); |
1054 | splice_from_pipe_end(pipe, &sd); |
1055 | |
1056 | pipe_unlock(pipe); |
1057 | |
1058 | if (sd.num_spliced) |
1059 | ret = sd.num_spliced; |
1060 | |
1061 | return ret; |
1062 | } |
1063 | |
1064 | EXPORT_SYMBOL(iter_file_splice_write); |
1065 | |
1066 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1067 | struct splice_desc *sd) |
1068 | { |
1069 | int ret; |
1070 | void *data; |
1071 | loff_t tmp = sd->pos; |
1072 | |
1073 | data = kmap(buf->page); |
1074 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); |
1075 | kunmap(buf->page); |
1076 | |
1077 | return ret; |
1078 | } |
1079 | |
1080 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, |
1081 | struct file *out, loff_t *ppos, |
1082 | size_t len, unsigned int flags) |
1083 | { |
1084 | ssize_t ret; |
1085 | |
1086 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
1087 | if (ret > 0) |
1088 | *ppos += ret; |
1089 | |
1090 | return ret; |
1091 | } |
1092 | |
1093 | /** |
1094 | * generic_splice_sendpage - splice data from a pipe to a socket |
1095 | * @pipe: pipe to splice from |
1096 | * @out: socket to write to |
1097 | * @ppos: position in @out |
1098 | * @len: number of bytes to splice |
1099 | * @flags: splice modifier flags |
1100 | * |
1101 | * Description: |
1102 | * Will send @len bytes from the pipe to a network socket. No data copying |
1103 | * is involved. |
1104 | * |
1105 | */ |
1106 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
1107 | loff_t *ppos, size_t len, unsigned int flags) |
1108 | { |
1109 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
1110 | } |
1111 | |
1112 | EXPORT_SYMBOL(generic_splice_sendpage); |
1113 | |
1114 | /* |
1115 | * Attempt to initiate a splice from pipe to file. |
1116 | */ |
1117 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
1118 | loff_t *ppos, size_t len, unsigned int flags) |
1119 | { |
1120 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
1121 | loff_t *, size_t, unsigned int); |
1122 | |
1123 | if (out->f_op->splice_write) |
1124 | splice_write = out->f_op->splice_write; |
1125 | else |
1126 | splice_write = default_file_splice_write; |
1127 | |
1128 | return splice_write(pipe, out, ppos, len, flags); |
1129 | } |
1130 | |
1131 | /* |
1132 | * Attempt to initiate a splice from a file to a pipe. |
1133 | */ |
1134 | static long do_splice_to(struct file *in, loff_t *ppos, |
1135 | struct pipe_inode_info *pipe, size_t len, |
1136 | unsigned int flags) |
1137 | { |
1138 | ssize_t (*splice_read)(struct file *, loff_t *, |
1139 | struct pipe_inode_info *, size_t, unsigned int); |
1140 | int ret; |
1141 | |
1142 | if (unlikely(!(in->f_mode & FMODE_READ))) |
1143 | return -EBADF; |
1144 | |
1145 | ret = rw_verify_area(READ, in, ppos, len); |
1146 | if (unlikely(ret < 0)) |
1147 | return ret; |
1148 | |
1149 | if (in->f_op->splice_read) |
1150 | splice_read = in->f_op->splice_read; |
1151 | else |
1152 | splice_read = default_file_splice_read; |
1153 | |
1154 | return splice_read(in, ppos, pipe, len, flags); |
1155 | } |
1156 | |
1157 | /** |
1158 | * splice_direct_to_actor - splices data directly between two non-pipes |
1159 | * @in: file to splice from |
1160 | * @sd: actor information on where to splice to |
1161 | * @actor: handles the data splicing |
1162 | * |
1163 | * Description: |
1164 | * This is a special case helper to splice directly between two |
1165 | * points, without requiring an explicit pipe. Internally an allocated |
1166 | * pipe is cached in the process, and reused during the lifetime of |
1167 | * that process. |
1168 | * |
1169 | */ |
1170 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, |
1171 | splice_direct_actor *actor) |
1172 | { |
1173 | struct pipe_inode_info *pipe; |
1174 | long ret, bytes; |
1175 | umode_t i_mode; |
1176 | size_t len; |
1177 | int i, flags; |
1178 | |
1179 | /* |
1180 | * We require the input being a regular file, as we don't want to |
1181 | * randomly drop data for eg socket -> socket splicing. Use the |
1182 | * piped splicing for that! |
1183 | */ |
1184 | i_mode = file_inode(in)->i_mode; |
1185 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
1186 | return -EINVAL; |
1187 | |
1188 | /* |
1189 | * neither in nor out is a pipe, setup an internal pipe attached to |
1190 | * 'out' and transfer the wanted data from 'in' to 'out' through that |
1191 | */ |
1192 | pipe = current->splice_pipe; |
1193 | if (unlikely(!pipe)) { |
1194 | pipe = alloc_pipe_info(); |
1195 | if (!pipe) |
1196 | return -ENOMEM; |
1197 | |
1198 | /* |
1199 | * We don't have an immediate reader, but we'll read the stuff |
1200 | * out of the pipe right after the splice_to_pipe(). So set |
1201 | * PIPE_READERS appropriately. |
1202 | */ |
1203 | pipe->readers = 1; |
1204 | |
1205 | current->splice_pipe = pipe; |
1206 | } |
1207 | |
1208 | /* |
1209 | * Do the splice. |
1210 | */ |
1211 | ret = 0; |
1212 | bytes = 0; |
1213 | len = sd->total_len; |
1214 | flags = sd->flags; |
1215 | |
1216 | /* |
1217 | * Don't block on output, we have to drain the direct pipe. |
1218 | */ |
1219 | sd->flags &= ~SPLICE_F_NONBLOCK; |
1220 | |
1221 | while (len) { |
1222 | size_t read_len; |
1223 | loff_t pos = sd->pos, prev_pos = pos; |
1224 | |
1225 | ret = do_splice_to(in, &pos, pipe, len, flags); |
1226 | if (unlikely(ret <= 0)) |
1227 | goto out_release; |
1228 | |
1229 | read_len = ret; |
1230 | sd->total_len = read_len; |
1231 | |
1232 | /* |
1233 | * NOTE: nonblocking mode only applies to the input. We |
1234 | * must not do the output in nonblocking mode as then we |
1235 | * could get stuck data in the internal pipe: |
1236 | */ |
1237 | ret = actor(pipe, sd); |
1238 | if (unlikely(ret <= 0)) { |
1239 | sd->pos = prev_pos; |
1240 | goto out_release; |
1241 | } |
1242 | |
1243 | bytes += ret; |
1244 | len -= ret; |
1245 | sd->pos = pos; |
1246 | |
1247 | if (ret < read_len) { |
1248 | sd->pos = prev_pos + ret; |
1249 | goto out_release; |
1250 | } |
1251 | } |
1252 | |
1253 | done: |
1254 | pipe->nrbufs = pipe->curbuf = 0; |
1255 | file_accessed(in); |
1256 | return bytes; |
1257 | |
1258 | out_release: |
1259 | /* |
1260 | * If we did an incomplete transfer we must release |
1261 | * the pipe buffers in question: |
1262 | */ |
1263 | for (i = 0; i < pipe->buffers; i++) { |
1264 | struct pipe_buffer *buf = pipe->bufs + i; |
1265 | |
1266 | if (buf->ops) { |
1267 | buf->ops->release(pipe, buf); |
1268 | buf->ops = NULL; |
1269 | } |
1270 | } |
1271 | |
1272 | if (!bytes) |
1273 | bytes = ret; |
1274 | |
1275 | goto done; |
1276 | } |
1277 | EXPORT_SYMBOL(splice_direct_to_actor); |
1278 | |
1279 | static int direct_splice_actor(struct pipe_inode_info *pipe, |
1280 | struct splice_desc *sd) |
1281 | { |
1282 | struct file *file = sd->u.file; |
1283 | |
1284 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
1285 | sd->flags); |
1286 | } |
1287 | |
1288 | /** |
1289 | * do_splice_direct - splices data directly between two files |
1290 | * @in: file to splice from |
1291 | * @ppos: input file offset |
1292 | * @out: file to splice to |
1293 | * @opos: output file offset |
1294 | * @len: number of bytes to splice |
1295 | * @flags: splice modifier flags |
1296 | * |
1297 | * Description: |
1298 | * For use by do_sendfile(). splice can easily emulate sendfile, but |
1299 | * doing it in the application would incur an extra system call |
1300 | * (splice in + splice out, as compared to just sendfile()). So this helper |
1301 | * can splice directly through a process-private pipe. |
1302 | * |
1303 | */ |
1304 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1305 | loff_t *opos, size_t len, unsigned int flags) |
1306 | { |
1307 | struct splice_desc sd = { |
1308 | .len = len, |
1309 | .total_len = len, |
1310 | .flags = flags, |
1311 | .pos = *ppos, |
1312 | .u.file = out, |
1313 | .opos = opos, |
1314 | }; |
1315 | long ret; |
1316 | |
1317 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1318 | return -EBADF; |
1319 | |
1320 | if (unlikely(out->f_flags & O_APPEND)) |
1321 | return -EINVAL; |
1322 | |
1323 | ret = rw_verify_area(WRITE, out, opos, len); |
1324 | if (unlikely(ret < 0)) |
1325 | return ret; |
1326 | |
1327 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
1328 | if (ret > 0) |
1329 | *ppos = sd.pos; |
1330 | |
1331 | return ret; |
1332 | } |
1333 | EXPORT_SYMBOL(do_splice_direct); |
1334 | |
1335 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1336 | struct pipe_inode_info *opipe, |
1337 | size_t len, unsigned int flags); |
1338 | |
1339 | /* |
1340 | * Determine where to splice to/from. |
1341 | */ |
1342 | static long do_splice(struct file *in, loff_t __user *off_in, |
1343 | struct file *out, loff_t __user *off_out, |
1344 | size_t len, unsigned int flags) |
1345 | { |
1346 | struct pipe_inode_info *ipipe; |
1347 | struct pipe_inode_info *opipe; |
1348 | loff_t offset; |
1349 | long ret; |
1350 | |
1351 | ipipe = get_pipe_info(in); |
1352 | opipe = get_pipe_info(out); |
1353 | |
1354 | if (ipipe && opipe) { |
1355 | if (off_in || off_out) |
1356 | return -ESPIPE; |
1357 | |
1358 | if (!(in->f_mode & FMODE_READ)) |
1359 | return -EBADF; |
1360 | |
1361 | if (!(out->f_mode & FMODE_WRITE)) |
1362 | return -EBADF; |
1363 | |
1364 | /* Splicing to self would be fun, but... */ |
1365 | if (ipipe == opipe) |
1366 | return -EINVAL; |
1367 | |
1368 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1369 | } |
1370 | |
1371 | if (ipipe) { |
1372 | if (off_in) |
1373 | return -ESPIPE; |
1374 | if (off_out) { |
1375 | if (!(out->f_mode & FMODE_PWRITE)) |
1376 | return -EINVAL; |
1377 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
1378 | return -EFAULT; |
1379 | } else { |
1380 | offset = out->f_pos; |
1381 | } |
1382 | |
1383 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1384 | return -EBADF; |
1385 | |
1386 | if (unlikely(out->f_flags & O_APPEND)) |
1387 | return -EINVAL; |
1388 | |
1389 | ret = rw_verify_area(WRITE, out, &offset, len); |
1390 | if (unlikely(ret < 0)) |
1391 | return ret; |
1392 | |
1393 | file_start_write(out); |
1394 | ret = do_splice_from(ipipe, out, &offset, len, flags); |
1395 | file_end_write(out); |
1396 | |
1397 | if (!off_out) |
1398 | out->f_pos = offset; |
1399 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) |
1400 | ret = -EFAULT; |
1401 | |
1402 | return ret; |
1403 | } |
1404 | |
1405 | if (opipe) { |
1406 | if (off_out) |
1407 | return -ESPIPE; |
1408 | if (off_in) { |
1409 | if (!(in->f_mode & FMODE_PREAD)) |
1410 | return -EINVAL; |
1411 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
1412 | return -EFAULT; |
1413 | } else { |
1414 | offset = in->f_pos; |
1415 | } |
1416 | |
1417 | ret = do_splice_to(in, &offset, opipe, len, flags); |
1418 | |
1419 | if (!off_in) |
1420 | in->f_pos = offset; |
1421 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) |
1422 | ret = -EFAULT; |
1423 | |
1424 | return ret; |
1425 | } |
1426 | |
1427 | return -EINVAL; |
1428 | } |
1429 | |
1430 | /* |
1431 | * Map an iov into an array of pages and offset/length tupples. With the |
1432 | * partial_page structure, we can map several non-contiguous ranges into |
1433 | * our ones pages[] map instead of splitting that operation into pieces. |
1434 | * Could easily be exported as a generic helper for other users, in which |
1435 | * case one would probably want to add a 'max_nr_pages' parameter as well. |
1436 | */ |
1437 | static int get_iovec_page_array(const struct iovec __user *iov, |
1438 | unsigned int nr_vecs, struct page **pages, |
1439 | struct partial_page *partial, bool aligned, |
1440 | unsigned int pipe_buffers) |
1441 | { |
1442 | int buffers = 0, error = 0; |
1443 | |
1444 | while (nr_vecs) { |
1445 | unsigned long off, npages; |
1446 | struct iovec entry; |
1447 | void __user *base; |
1448 | size_t len; |
1449 | int i; |
1450 | |
1451 | error = -EFAULT; |
1452 | if (copy_from_user(&entry, iov, sizeof(entry))) |
1453 | break; |
1454 | |
1455 | base = entry.iov_base; |
1456 | len = entry.iov_len; |
1457 | |
1458 | /* |
1459 | * Sanity check this iovec. 0 read succeeds. |
1460 | */ |
1461 | error = 0; |
1462 | if (unlikely(!len)) |
1463 | break; |
1464 | error = -EFAULT; |
1465 | if (!access_ok(VERIFY_READ, base, len)) |
1466 | break; |
1467 | |
1468 | /* |
1469 | * Get this base offset and number of pages, then map |
1470 | * in the user pages. |
1471 | */ |
1472 | off = (unsigned long) base & ~PAGE_MASK; |
1473 | |
1474 | /* |
1475 | * If asked for alignment, the offset must be zero and the |
1476 | * length a multiple of the PAGE_SIZE. |
1477 | */ |
1478 | error = -EINVAL; |
1479 | if (aligned && (off || len & ~PAGE_MASK)) |
1480 | break; |
1481 | |
1482 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1483 | if (npages > pipe_buffers - buffers) |
1484 | npages = pipe_buffers - buffers; |
1485 | |
1486 | error = get_user_pages_fast((unsigned long)base, npages, |
1487 | 0, &pages[buffers]); |
1488 | |
1489 | if (unlikely(error <= 0)) |
1490 | break; |
1491 | |
1492 | /* |
1493 | * Fill this contiguous range into the partial page map. |
1494 | */ |
1495 | for (i = 0; i < error; i++) { |
1496 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
1497 | |
1498 | partial[buffers].offset = off; |
1499 | partial[buffers].len = plen; |
1500 | |
1501 | off = 0; |
1502 | len -= plen; |
1503 | buffers++; |
1504 | } |
1505 | |
1506 | /* |
1507 | * We didn't complete this iov, stop here since it probably |
1508 | * means we have to move some of this into a pipe to |
1509 | * be able to continue. |
1510 | */ |
1511 | if (len) |
1512 | break; |
1513 | |
1514 | /* |
1515 | * Don't continue if we mapped fewer pages than we asked for, |
1516 | * or if we mapped the max number of pages that we have |
1517 | * room for. |
1518 | */ |
1519 | if (error < npages || buffers == pipe_buffers) |
1520 | break; |
1521 | |
1522 | nr_vecs--; |
1523 | iov++; |
1524 | } |
1525 | |
1526 | if (buffers) |
1527 | return buffers; |
1528 | |
1529 | return error; |
1530 | } |
1531 | |
1532 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1533 | struct splice_desc *sd) |
1534 | { |
1535 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
1536 | return n == sd->len ? n : -EFAULT; |
1537 | } |
1538 | |
1539 | /* |
1540 | * For lack of a better implementation, implement vmsplice() to userspace |
1541 | * as a simple copy of the pipes pages to the user iov. |
1542 | */ |
1543 | static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov, |
1544 | unsigned long nr_segs, unsigned int flags) |
1545 | { |
1546 | struct pipe_inode_info *pipe; |
1547 | struct splice_desc sd; |
1548 | long ret; |
1549 | struct iovec iovstack[UIO_FASTIOV]; |
1550 | struct iovec *iov = iovstack; |
1551 | struct iov_iter iter; |
1552 | ssize_t count; |
1553 | |
1554 | pipe = get_pipe_info(file); |
1555 | if (!pipe) |
1556 | return -EBADF; |
1557 | |
1558 | ret = rw_copy_check_uvector(READ, uiov, nr_segs, |
1559 | ARRAY_SIZE(iovstack), iovstack, &iov); |
1560 | if (ret <= 0) |
1561 | goto out; |
1562 | |
1563 | count = ret; |
1564 | iov_iter_init(&iter, READ, iov, nr_segs, count); |
1565 | |
1566 | sd.len = 0; |
1567 | sd.total_len = count; |
1568 | sd.flags = flags; |
1569 | sd.u.data = &iter; |
1570 | sd.pos = 0; |
1571 | |
1572 | pipe_lock(pipe); |
1573 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); |
1574 | pipe_unlock(pipe); |
1575 | |
1576 | out: |
1577 | if (iov != iovstack) |
1578 | kfree(iov); |
1579 | |
1580 | return ret; |
1581 | } |
1582 | |
1583 | /* |
1584 | * vmsplice splices a user address range into a pipe. It can be thought of |
1585 | * as splice-from-memory, where the regular splice is splice-from-file (or |
1586 | * to file). In both cases the output is a pipe, naturally. |
1587 | */ |
1588 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1589 | unsigned long nr_segs, unsigned int flags) |
1590 | { |
1591 | struct pipe_inode_info *pipe; |
1592 | struct page *pages[PIPE_DEF_BUFFERS]; |
1593 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1594 | struct splice_pipe_desc spd = { |
1595 | .pages = pages, |
1596 | .partial = partial, |
1597 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1598 | .flags = flags, |
1599 | .ops = &user_page_pipe_buf_ops, |
1600 | .spd_release = spd_release_page, |
1601 | }; |
1602 | long ret; |
1603 | |
1604 | pipe = get_pipe_info(file); |
1605 | if (!pipe) |
1606 | return -EBADF; |
1607 | |
1608 | if (splice_grow_spd(pipe, &spd)) |
1609 | return -ENOMEM; |
1610 | |
1611 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, |
1612 | spd.partial, false, |
1613 | spd.nr_pages_max); |
1614 | if (spd.nr_pages <= 0) |
1615 | ret = spd.nr_pages; |
1616 | else |
1617 | ret = splice_to_pipe(pipe, &spd); |
1618 | |
1619 | splice_shrink_spd(&spd); |
1620 | return ret; |
1621 | } |
1622 | |
1623 | /* |
1624 | * Note that vmsplice only really supports true splicing _from_ user memory |
1625 | * to a pipe, not the other way around. Splicing from user memory is a simple |
1626 | * operation that can be supported without any funky alignment restrictions |
1627 | * or nasty vm tricks. We simply map in the user memory and fill them into |
1628 | * a pipe. The reverse isn't quite as easy, though. There are two possible |
1629 | * solutions for that: |
1630 | * |
1631 | * - memcpy() the data internally, at which point we might as well just |
1632 | * do a regular read() on the buffer anyway. |
1633 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it |
1634 | * has restriction limitations on both ends of the pipe). |
1635 | * |
1636 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). |
1637 | * |
1638 | */ |
1639 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1640 | unsigned long, nr_segs, unsigned int, flags) |
1641 | { |
1642 | struct fd f; |
1643 | long error; |
1644 | |
1645 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1646 | return -EINVAL; |
1647 | else if (unlikely(!nr_segs)) |
1648 | return 0; |
1649 | |
1650 | error = -EBADF; |
1651 | f = fdget(fd); |
1652 | if (f.file) { |
1653 | if (f.file->f_mode & FMODE_WRITE) |
1654 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); |
1655 | else if (f.file->f_mode & FMODE_READ) |
1656 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); |
1657 | |
1658 | fdput(f); |
1659 | } |
1660 | |
1661 | return error; |
1662 | } |
1663 | |
1664 | #ifdef CONFIG_COMPAT |
1665 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, |
1666 | unsigned int, nr_segs, unsigned int, flags) |
1667 | { |
1668 | unsigned i; |
1669 | struct iovec __user *iov; |
1670 | if (nr_segs > UIO_MAXIOV) |
1671 | return -EINVAL; |
1672 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); |
1673 | for (i = 0; i < nr_segs; i++) { |
1674 | struct compat_iovec v; |
1675 | if (get_user(v.iov_base, &iov32[i].iov_base) || |
1676 | get_user(v.iov_len, &iov32[i].iov_len) || |
1677 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || |
1678 | put_user(v.iov_len, &iov[i].iov_len)) |
1679 | return -EFAULT; |
1680 | } |
1681 | return sys_vmsplice(fd, iov, nr_segs, flags); |
1682 | } |
1683 | #endif |
1684 | |
1685 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1686 | int, fd_out, loff_t __user *, off_out, |
1687 | size_t, len, unsigned int, flags) |
1688 | { |
1689 | struct fd in, out; |
1690 | long error; |
1691 | |
1692 | if (unlikely(!len)) |
1693 | return 0; |
1694 | |
1695 | error = -EBADF; |
1696 | in = fdget(fd_in); |
1697 | if (in.file) { |
1698 | if (in.file->f_mode & FMODE_READ) { |
1699 | out = fdget(fd_out); |
1700 | if (out.file) { |
1701 | if (out.file->f_mode & FMODE_WRITE) |
1702 | error = do_splice(in.file, off_in, |
1703 | out.file, off_out, |
1704 | len, flags); |
1705 | fdput(out); |
1706 | } |
1707 | } |
1708 | fdput(in); |
1709 | } |
1710 | return error; |
1711 | } |
1712 | |
1713 | /* |
1714 | * Make sure there's data to read. Wait for input if we can, otherwise |
1715 | * return an appropriate error. |
1716 | */ |
1717 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1718 | { |
1719 | int ret; |
1720 | |
1721 | /* |
1722 | * Check ->nrbufs without the inode lock first. This function |
1723 | * is speculative anyways, so missing one is ok. |
1724 | */ |
1725 | if (pipe->nrbufs) |
1726 | return 0; |
1727 | |
1728 | ret = 0; |
1729 | pipe_lock(pipe); |
1730 | |
1731 | while (!pipe->nrbufs) { |
1732 | if (signal_pending(current)) { |
1733 | ret = -ERESTARTSYS; |
1734 | break; |
1735 | } |
1736 | if (!pipe->writers) |
1737 | break; |
1738 | if (!pipe->waiting_writers) { |
1739 | if (flags & SPLICE_F_NONBLOCK) { |
1740 | ret = -EAGAIN; |
1741 | break; |
1742 | } |
1743 | } |
1744 | pipe_wait(pipe); |
1745 | } |
1746 | |
1747 | pipe_unlock(pipe); |
1748 | return ret; |
1749 | } |
1750 | |
1751 | /* |
1752 | * Make sure there's writeable room. Wait for room if we can, otherwise |
1753 | * return an appropriate error. |
1754 | */ |
1755 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1756 | { |
1757 | int ret; |
1758 | |
1759 | /* |
1760 | * Check ->nrbufs without the inode lock first. This function |
1761 | * is speculative anyways, so missing one is ok. |
1762 | */ |
1763 | if (pipe->nrbufs < pipe->buffers) |
1764 | return 0; |
1765 | |
1766 | ret = 0; |
1767 | pipe_lock(pipe); |
1768 | |
1769 | while (pipe->nrbufs >= pipe->buffers) { |
1770 | if (!pipe->readers) { |
1771 | send_sig(SIGPIPE, current, 0); |
1772 | ret = -EPIPE; |
1773 | break; |
1774 | } |
1775 | if (flags & SPLICE_F_NONBLOCK) { |
1776 | ret = -EAGAIN; |
1777 | break; |
1778 | } |
1779 | if (signal_pending(current)) { |
1780 | ret = -ERESTARTSYS; |
1781 | break; |
1782 | } |
1783 | pipe->waiting_writers++; |
1784 | pipe_wait(pipe); |
1785 | pipe->waiting_writers--; |
1786 | } |
1787 | |
1788 | pipe_unlock(pipe); |
1789 | return ret; |
1790 | } |
1791 | |
1792 | /* |
1793 | * Splice contents of ipipe to opipe. |
1794 | */ |
1795 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1796 | struct pipe_inode_info *opipe, |
1797 | size_t len, unsigned int flags) |
1798 | { |
1799 | struct pipe_buffer *ibuf, *obuf; |
1800 | int ret = 0, nbuf; |
1801 | bool input_wakeup = false; |
1802 | |
1803 | |
1804 | retry: |
1805 | ret = ipipe_prep(ipipe, flags); |
1806 | if (ret) |
1807 | return ret; |
1808 | |
1809 | ret = opipe_prep(opipe, flags); |
1810 | if (ret) |
1811 | return ret; |
1812 | |
1813 | /* |
1814 | * Potential ABBA deadlock, work around it by ordering lock |
1815 | * grabbing by pipe info address. Otherwise two different processes |
1816 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1817 | */ |
1818 | pipe_double_lock(ipipe, opipe); |
1819 | |
1820 | do { |
1821 | if (!opipe->readers) { |
1822 | send_sig(SIGPIPE, current, 0); |
1823 | if (!ret) |
1824 | ret = -EPIPE; |
1825 | break; |
1826 | } |
1827 | |
1828 | if (!ipipe->nrbufs && !ipipe->writers) |
1829 | break; |
1830 | |
1831 | /* |
1832 | * Cannot make any progress, because either the input |
1833 | * pipe is empty or the output pipe is full. |
1834 | */ |
1835 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
1836 | /* Already processed some buffers, break */ |
1837 | if (ret) |
1838 | break; |
1839 | |
1840 | if (flags & SPLICE_F_NONBLOCK) { |
1841 | ret = -EAGAIN; |
1842 | break; |
1843 | } |
1844 | |
1845 | /* |
1846 | * We raced with another reader/writer and haven't |
1847 | * managed to process any buffers. A zero return |
1848 | * value means EOF, so retry instead. |
1849 | */ |
1850 | pipe_unlock(ipipe); |
1851 | pipe_unlock(opipe); |
1852 | goto retry; |
1853 | } |
1854 | |
1855 | ibuf = ipipe->bufs + ipipe->curbuf; |
1856 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1857 | obuf = opipe->bufs + nbuf; |
1858 | |
1859 | if (len >= ibuf->len) { |
1860 | /* |
1861 | * Simply move the whole buffer from ipipe to opipe |
1862 | */ |
1863 | *obuf = *ibuf; |
1864 | ibuf->ops = NULL; |
1865 | opipe->nrbufs++; |
1866 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
1867 | ipipe->nrbufs--; |
1868 | input_wakeup = true; |
1869 | } else { |
1870 | /* |
1871 | * Get a reference to this pipe buffer, |
1872 | * so we can copy the contents over. |
1873 | */ |
1874 | ibuf->ops->get(ipipe, ibuf); |
1875 | *obuf = *ibuf; |
1876 | |
1877 | /* |
1878 | * Don't inherit the gift flag, we need to |
1879 | * prevent multiple steals of this page. |
1880 | */ |
1881 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1882 | |
1883 | obuf->len = len; |
1884 | opipe->nrbufs++; |
1885 | ibuf->offset += obuf->len; |
1886 | ibuf->len -= obuf->len; |
1887 | } |
1888 | ret += obuf->len; |
1889 | len -= obuf->len; |
1890 | } while (len); |
1891 | |
1892 | pipe_unlock(ipipe); |
1893 | pipe_unlock(opipe); |
1894 | |
1895 | /* |
1896 | * If we put data in the output pipe, wakeup any potential readers. |
1897 | */ |
1898 | if (ret > 0) |
1899 | wakeup_pipe_readers(opipe); |
1900 | |
1901 | if (input_wakeup) |
1902 | wakeup_pipe_writers(ipipe); |
1903 | |
1904 | return ret; |
1905 | } |
1906 | |
1907 | /* |
1908 | * Link contents of ipipe to opipe. |
1909 | */ |
1910 | static int link_pipe(struct pipe_inode_info *ipipe, |
1911 | struct pipe_inode_info *opipe, |
1912 | size_t len, unsigned int flags) |
1913 | { |
1914 | struct pipe_buffer *ibuf, *obuf; |
1915 | int ret = 0, i = 0, nbuf; |
1916 | |
1917 | /* |
1918 | * Potential ABBA deadlock, work around it by ordering lock |
1919 | * grabbing by pipe info address. Otherwise two different processes |
1920 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1921 | */ |
1922 | pipe_double_lock(ipipe, opipe); |
1923 | |
1924 | do { |
1925 | if (!opipe->readers) { |
1926 | send_sig(SIGPIPE, current, 0); |
1927 | if (!ret) |
1928 | ret = -EPIPE; |
1929 | break; |
1930 | } |
1931 | |
1932 | /* |
1933 | * If we have iterated all input buffers or ran out of |
1934 | * output room, break. |
1935 | */ |
1936 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
1937 | break; |
1938 | |
1939 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
1940 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1941 | |
1942 | /* |
1943 | * Get a reference to this pipe buffer, |
1944 | * so we can copy the contents over. |
1945 | */ |
1946 | ibuf->ops->get(ipipe, ibuf); |
1947 | |
1948 | obuf = opipe->bufs + nbuf; |
1949 | *obuf = *ibuf; |
1950 | |
1951 | /* |
1952 | * Don't inherit the gift flag, we need to |
1953 | * prevent multiple steals of this page. |
1954 | */ |
1955 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1956 | |
1957 | if (obuf->len > len) |
1958 | obuf->len = len; |
1959 | |
1960 | opipe->nrbufs++; |
1961 | ret += obuf->len; |
1962 | len -= obuf->len; |
1963 | i++; |
1964 | } while (len); |
1965 | |
1966 | /* |
1967 | * return EAGAIN if we have the potential of some data in the |
1968 | * future, otherwise just return 0 |
1969 | */ |
1970 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) |
1971 | ret = -EAGAIN; |
1972 | |
1973 | pipe_unlock(ipipe); |
1974 | pipe_unlock(opipe); |
1975 | |
1976 | /* |
1977 | * If we put data in the output pipe, wakeup any potential readers. |
1978 | */ |
1979 | if (ret > 0) |
1980 | wakeup_pipe_readers(opipe); |
1981 | |
1982 | return ret; |
1983 | } |
1984 | |
1985 | /* |
1986 | * This is a tee(1) implementation that works on pipes. It doesn't copy |
1987 | * any data, it simply references the 'in' pages on the 'out' pipe. |
1988 | * The 'flags' used are the SPLICE_F_* variants, currently the only |
1989 | * applicable one is SPLICE_F_NONBLOCK. |
1990 | */ |
1991 | static long do_tee(struct file *in, struct file *out, size_t len, |
1992 | unsigned int flags) |
1993 | { |
1994 | struct pipe_inode_info *ipipe = get_pipe_info(in); |
1995 | struct pipe_inode_info *opipe = get_pipe_info(out); |
1996 | int ret = -EINVAL; |
1997 | |
1998 | /* |
1999 | * Duplicate the contents of ipipe to opipe without actually |
2000 | * copying the data. |
2001 | */ |
2002 | if (ipipe && opipe && ipipe != opipe) { |
2003 | /* |
2004 | * Keep going, unless we encounter an error. The ipipe/opipe |
2005 | * ordering doesn't really matter. |
2006 | */ |
2007 | ret = ipipe_prep(ipipe, flags); |
2008 | if (!ret) { |
2009 | ret = opipe_prep(opipe, flags); |
2010 | if (!ret) |
2011 | ret = link_pipe(ipipe, opipe, len, flags); |
2012 | } |
2013 | } |
2014 | |
2015 | return ret; |
2016 | } |
2017 | |
2018 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
2019 | { |
2020 | struct fd in; |
2021 | int error; |
2022 | |
2023 | if (unlikely(!len)) |
2024 | return 0; |
2025 | |
2026 | error = -EBADF; |
2027 | in = fdget(fdin); |
2028 | if (in.file) { |
2029 | if (in.file->f_mode & FMODE_READ) { |
2030 | struct fd out = fdget(fdout); |
2031 | if (out.file) { |
2032 | if (out.file->f_mode & FMODE_WRITE) |
2033 | error = do_tee(in.file, out.file, |
2034 | len, flags); |
2035 | fdput(out); |
2036 | } |
2037 | } |
2038 | fdput(in); |
2039 | } |
2040 | |
2041 | return error; |
2042 | } |
2043 |
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v2.6.34-rc5
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