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 "internal.h" |
35 | |
36 | /* |
37 | * Attempt to steal a page from a pipe buffer. This should perhaps go into |
38 | * a vm helper function, it's already simplified quite a bit by the |
39 | * addition of remove_mapping(). If success is returned, the caller may |
40 | * attempt to reuse this page for another destination. |
41 | */ |
42 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
43 | struct pipe_buffer *buf) |
44 | { |
45 | struct page *page = buf->page; |
46 | struct address_space *mapping; |
47 | |
48 | lock_page(page); |
49 | |
50 | mapping = page_mapping(page); |
51 | if (mapping) { |
52 | WARN_ON(!PageUptodate(page)); |
53 | |
54 | /* |
55 | * At least for ext2 with nobh option, we need to wait on |
56 | * writeback completing on this page, since we'll remove it |
57 | * from the pagecache. Otherwise truncate wont wait on the |
58 | * page, allowing the disk blocks to be reused by someone else |
59 | * before we actually wrote our data to them. fs corruption |
60 | * ensues. |
61 | */ |
62 | wait_on_page_writeback(page); |
63 | |
64 | if (page_has_private(page) && |
65 | !try_to_release_page(page, GFP_KERNEL)) |
66 | goto out_unlock; |
67 | |
68 | /* |
69 | * If we succeeded in removing the mapping, set LRU flag |
70 | * and return good. |
71 | */ |
72 | if (remove_mapping(mapping, page)) { |
73 | buf->flags |= PIPE_BUF_FLAG_LRU; |
74 | return 0; |
75 | } |
76 | } |
77 | |
78 | /* |
79 | * Raced with truncate or failed to remove page from current |
80 | * address space, unlock and return failure. |
81 | */ |
82 | out_unlock: |
83 | unlock_page(page); |
84 | return 1; |
85 | } |
86 | |
87 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
88 | struct pipe_buffer *buf) |
89 | { |
90 | page_cache_release(buf->page); |
91 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
92 | } |
93 | |
94 | /* |
95 | * Check whether the contents of buf is OK to access. Since the content |
96 | * is a page cache page, IO may be in flight. |
97 | */ |
98 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
99 | struct pipe_buffer *buf) |
100 | { |
101 | struct page *page = buf->page; |
102 | int err; |
103 | |
104 | if (!PageUptodate(page)) { |
105 | lock_page(page); |
106 | |
107 | /* |
108 | * Page got truncated/unhashed. This will cause a 0-byte |
109 | * splice, if this is the first page. |
110 | */ |
111 | if (!page->mapping) { |
112 | err = -ENODATA; |
113 | goto error; |
114 | } |
115 | |
116 | /* |
117 | * Uh oh, read-error from disk. |
118 | */ |
119 | if (!PageUptodate(page)) { |
120 | err = -EIO; |
121 | goto error; |
122 | } |
123 | |
124 | /* |
125 | * Page is ok afterall, we are done. |
126 | */ |
127 | unlock_page(page); |
128 | } |
129 | |
130 | return 0; |
131 | error: |
132 | unlock_page(page); |
133 | return err; |
134 | } |
135 | |
136 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
137 | .can_merge = 0, |
138 | .map = generic_pipe_buf_map, |
139 | .unmap = generic_pipe_buf_unmap, |
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 | .map = generic_pipe_buf_map, |
159 | .unmap = generic_pipe_buf_unmap, |
160 | .confirm = generic_pipe_buf_confirm, |
161 | .release = page_cache_pipe_buf_release, |
162 | .steal = user_page_pipe_buf_steal, |
163 | .get = generic_pipe_buf_get, |
164 | }; |
165 | |
166 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
167 | { |
168 | smp_mb(); |
169 | if (waitqueue_active(&pipe->wait)) |
170 | wake_up_interruptible(&pipe->wait); |
171 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
172 | } |
173 | |
174 | /** |
175 | * splice_to_pipe - fill passed data into a pipe |
176 | * @pipe: pipe to fill |
177 | * @spd: data to fill |
178 | * |
179 | * Description: |
180 | * @spd contains a map of pages and len/offset tuples, along with |
181 | * the struct pipe_buf_operations associated with these pages. This |
182 | * function will link that data to the pipe. |
183 | * |
184 | */ |
185 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
186 | struct splice_pipe_desc *spd) |
187 | { |
188 | unsigned int spd_pages = spd->nr_pages; |
189 | int ret, do_wakeup, page_nr; |
190 | |
191 | ret = 0; |
192 | do_wakeup = 0; |
193 | page_nr = 0; |
194 | |
195 | pipe_lock(pipe); |
196 | |
197 | for (;;) { |
198 | if (!pipe->readers) { |
199 | send_sig(SIGPIPE, current, 0); |
200 | if (!ret) |
201 | ret = -EPIPE; |
202 | break; |
203 | } |
204 | |
205 | if (pipe->nrbufs < pipe->buffers) { |
206 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); |
207 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
208 | |
209 | buf->page = spd->pages[page_nr]; |
210 | buf->offset = spd->partial[page_nr].offset; |
211 | buf->len = spd->partial[page_nr].len; |
212 | buf->private = spd->partial[page_nr].private; |
213 | buf->ops = spd->ops; |
214 | if (spd->flags & SPLICE_F_GIFT) |
215 | buf->flags |= PIPE_BUF_FLAG_GIFT; |
216 | |
217 | pipe->nrbufs++; |
218 | page_nr++; |
219 | ret += buf->len; |
220 | |
221 | if (pipe->inode) |
222 | do_wakeup = 1; |
223 | |
224 | if (!--spd->nr_pages) |
225 | break; |
226 | if (pipe->nrbufs < pipe->buffers) |
227 | continue; |
228 | |
229 | break; |
230 | } |
231 | |
232 | if (spd->flags & SPLICE_F_NONBLOCK) { |
233 | if (!ret) |
234 | ret = -EAGAIN; |
235 | break; |
236 | } |
237 | |
238 | if (signal_pending(current)) { |
239 | if (!ret) |
240 | ret = -ERESTARTSYS; |
241 | break; |
242 | } |
243 | |
244 | if (do_wakeup) { |
245 | smp_mb(); |
246 | if (waitqueue_active(&pipe->wait)) |
247 | wake_up_interruptible_sync(&pipe->wait); |
248 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
249 | do_wakeup = 0; |
250 | } |
251 | |
252 | pipe->waiting_writers++; |
253 | pipe_wait(pipe); |
254 | pipe->waiting_writers--; |
255 | } |
256 | |
257 | pipe_unlock(pipe); |
258 | |
259 | if (do_wakeup) |
260 | wakeup_pipe_readers(pipe); |
261 | |
262 | while (page_nr < spd_pages) |
263 | spd->spd_release(spd, page_nr++); |
264 | |
265 | return ret; |
266 | } |
267 | |
268 | void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
269 | { |
270 | page_cache_release(spd->pages[i]); |
271 | } |
272 | |
273 | /* |
274 | * Check if we need to grow the arrays holding pages and partial page |
275 | * descriptions. |
276 | */ |
277 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
278 | { |
279 | unsigned int buffers = ACCESS_ONCE(pipe->buffers); |
280 | |
281 | spd->nr_pages_max = buffers; |
282 | if (buffers <= PIPE_DEF_BUFFERS) |
283 | return 0; |
284 | |
285 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); |
286 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); |
287 | |
288 | if (spd->pages && spd->partial) |
289 | return 0; |
290 | |
291 | kfree(spd->pages); |
292 | kfree(spd->partial); |
293 | return -ENOMEM; |
294 | } |
295 | |
296 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
297 | { |
298 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
299 | return; |
300 | |
301 | kfree(spd->pages); |
302 | kfree(spd->partial); |
303 | } |
304 | |
305 | static int |
306 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
307 | struct pipe_inode_info *pipe, size_t len, |
308 | unsigned int flags) |
309 | { |
310 | struct address_space *mapping = in->f_mapping; |
311 | unsigned int loff, nr_pages, req_pages; |
312 | struct page *pages[PIPE_DEF_BUFFERS]; |
313 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
314 | struct page *page; |
315 | pgoff_t index, end_index; |
316 | loff_t isize; |
317 | int error, page_nr; |
318 | struct splice_pipe_desc spd = { |
319 | .pages = pages, |
320 | .partial = partial, |
321 | .nr_pages_max = PIPE_DEF_BUFFERS, |
322 | .flags = flags, |
323 | .ops = &page_cache_pipe_buf_ops, |
324 | .spd_release = spd_release_page, |
325 | }; |
326 | |
327 | if (splice_grow_spd(pipe, &spd)) |
328 | return -ENOMEM; |
329 | |
330 | index = *ppos >> PAGE_CACHE_SHIFT; |
331 | loff = *ppos & ~PAGE_CACHE_MASK; |
332 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
333 | nr_pages = min(req_pages, spd.nr_pages_max); |
334 | |
335 | /* |
336 | * Lookup the (hopefully) full range of pages we need. |
337 | */ |
338 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); |
339 | index += spd.nr_pages; |
340 | |
341 | /* |
342 | * If find_get_pages_contig() returned fewer pages than we needed, |
343 | * readahead/allocate the rest and fill in the holes. |
344 | */ |
345 | if (spd.nr_pages < nr_pages) |
346 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
347 | index, req_pages - spd.nr_pages); |
348 | |
349 | error = 0; |
350 | while (spd.nr_pages < nr_pages) { |
351 | /* |
352 | * Page could be there, find_get_pages_contig() breaks on |
353 | * the first hole. |
354 | */ |
355 | page = find_get_page(mapping, index); |
356 | if (!page) { |
357 | /* |
358 | * page didn't exist, allocate one. |
359 | */ |
360 | page = page_cache_alloc_cold(mapping); |
361 | if (!page) |
362 | break; |
363 | |
364 | error = add_to_page_cache_lru(page, mapping, index, |
365 | GFP_KERNEL); |
366 | if (unlikely(error)) { |
367 | page_cache_release(page); |
368 | if (error == -EEXIST) |
369 | continue; |
370 | break; |
371 | } |
372 | /* |
373 | * add_to_page_cache() locks the page, unlock it |
374 | * to avoid convoluting the logic below even more. |
375 | */ |
376 | unlock_page(page); |
377 | } |
378 | |
379 | spd.pages[spd.nr_pages++] = page; |
380 | index++; |
381 | } |
382 | |
383 | /* |
384 | * Now loop over the map and see if we need to start IO on any |
385 | * pages, fill in the partial map, etc. |
386 | */ |
387 | index = *ppos >> PAGE_CACHE_SHIFT; |
388 | nr_pages = spd.nr_pages; |
389 | spd.nr_pages = 0; |
390 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
391 | unsigned int this_len; |
392 | |
393 | if (!len) |
394 | break; |
395 | |
396 | /* |
397 | * this_len is the max we'll use from this page |
398 | */ |
399 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
400 | page = spd.pages[page_nr]; |
401 | |
402 | if (PageReadahead(page)) |
403 | page_cache_async_readahead(mapping, &in->f_ra, in, |
404 | page, index, req_pages - page_nr); |
405 | |
406 | /* |
407 | * If the page isn't uptodate, we may need to start io on it |
408 | */ |
409 | if (!PageUptodate(page)) { |
410 | lock_page(page); |
411 | |
412 | /* |
413 | * Page was truncated, or invalidated by the |
414 | * filesystem. Redo the find/create, but this time the |
415 | * page is kept locked, so there's no chance of another |
416 | * race with truncate/invalidate. |
417 | */ |
418 | if (!page->mapping) { |
419 | unlock_page(page); |
420 | page = find_or_create_page(mapping, index, |
421 | mapping_gfp_mask(mapping)); |
422 | |
423 | if (!page) { |
424 | error = -ENOMEM; |
425 | break; |
426 | } |
427 | page_cache_release(spd.pages[page_nr]); |
428 | spd.pages[page_nr] = page; |
429 | } |
430 | /* |
431 | * page was already under io and is now done, great |
432 | */ |
433 | if (PageUptodate(page)) { |
434 | unlock_page(page); |
435 | goto fill_it; |
436 | } |
437 | |
438 | /* |
439 | * need to read in the page |
440 | */ |
441 | error = mapping->a_ops->readpage(in, page); |
442 | if (unlikely(error)) { |
443 | /* |
444 | * We really should re-lookup the page here, |
445 | * but it complicates things a lot. Instead |
446 | * lets just do what we already stored, and |
447 | * we'll get it the next time we are called. |
448 | */ |
449 | if (error == AOP_TRUNCATED_PAGE) |
450 | error = 0; |
451 | |
452 | break; |
453 | } |
454 | } |
455 | fill_it: |
456 | /* |
457 | * i_size must be checked after PageUptodate. |
458 | */ |
459 | isize = i_size_read(mapping->host); |
460 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
461 | if (unlikely(!isize || index > end_index)) |
462 | break; |
463 | |
464 | /* |
465 | * if this is the last page, see if we need to shrink |
466 | * the length and stop |
467 | */ |
468 | if (end_index == index) { |
469 | unsigned int plen; |
470 | |
471 | /* |
472 | * max good bytes in this page |
473 | */ |
474 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
475 | if (plen <= loff) |
476 | break; |
477 | |
478 | /* |
479 | * force quit after adding this page |
480 | */ |
481 | this_len = min(this_len, plen - loff); |
482 | len = this_len; |
483 | } |
484 | |
485 | spd.partial[page_nr].offset = loff; |
486 | spd.partial[page_nr].len = this_len; |
487 | len -= this_len; |
488 | loff = 0; |
489 | spd.nr_pages++; |
490 | index++; |
491 | } |
492 | |
493 | /* |
494 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
495 | * we got, 'nr_pages' is how many pages are in the map. |
496 | */ |
497 | while (page_nr < nr_pages) |
498 | page_cache_release(spd.pages[page_nr++]); |
499 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
500 | |
501 | if (spd.nr_pages) |
502 | error = splice_to_pipe(pipe, &spd); |
503 | |
504 | splice_shrink_spd(&spd); |
505 | return error; |
506 | } |
507 | |
508 | /** |
509 | * generic_file_splice_read - splice data from file to a pipe |
510 | * @in: file to splice from |
511 | * @ppos: position in @in |
512 | * @pipe: pipe to splice to |
513 | * @len: number of bytes to splice |
514 | * @flags: splice modifier flags |
515 | * |
516 | * Description: |
517 | * Will read pages from given file and fill them into a pipe. Can be |
518 | * used as long as the address_space operations for the source implements |
519 | * a readpage() hook. |
520 | * |
521 | */ |
522 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
523 | struct pipe_inode_info *pipe, size_t len, |
524 | unsigned int flags) |
525 | { |
526 | loff_t isize, left; |
527 | int ret; |
528 | |
529 | isize = i_size_read(in->f_mapping->host); |
530 | if (unlikely(*ppos >= isize)) |
531 | return 0; |
532 | |
533 | left = isize - *ppos; |
534 | if (unlikely(left < len)) |
535 | len = left; |
536 | |
537 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
538 | if (ret > 0) { |
539 | *ppos += ret; |
540 | file_accessed(in); |
541 | } |
542 | |
543 | return ret; |
544 | } |
545 | EXPORT_SYMBOL(generic_file_splice_read); |
546 | |
547 | static const struct pipe_buf_operations default_pipe_buf_ops = { |
548 | .can_merge = 0, |
549 | .map = generic_pipe_buf_map, |
550 | .unmap = generic_pipe_buf_unmap, |
551 | .confirm = generic_pipe_buf_confirm, |
552 | .release = generic_pipe_buf_release, |
553 | .steal = generic_pipe_buf_steal, |
554 | .get = generic_pipe_buf_get, |
555 | }; |
556 | |
557 | static ssize_t kernel_readv(struct file *file, const struct iovec *vec, |
558 | unsigned long vlen, loff_t offset) |
559 | { |
560 | mm_segment_t old_fs; |
561 | loff_t pos = offset; |
562 | ssize_t res; |
563 | |
564 | old_fs = get_fs(); |
565 | set_fs(get_ds()); |
566 | /* The cast to a user pointer is valid due to the set_fs() */ |
567 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos); |
568 | set_fs(old_fs); |
569 | |
570 | return res; |
571 | } |
572 | |
573 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
574 | loff_t pos) |
575 | { |
576 | mm_segment_t old_fs; |
577 | ssize_t res; |
578 | |
579 | old_fs = get_fs(); |
580 | set_fs(get_ds()); |
581 | /* The cast to a user pointer is valid due to the set_fs() */ |
582 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); |
583 | set_fs(old_fs); |
584 | |
585 | return res; |
586 | } |
587 | EXPORT_SYMBOL(kernel_write); |
588 | |
589 | ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
590 | struct pipe_inode_info *pipe, size_t len, |
591 | unsigned int flags) |
592 | { |
593 | unsigned int nr_pages; |
594 | unsigned int nr_freed; |
595 | size_t offset; |
596 | struct page *pages[PIPE_DEF_BUFFERS]; |
597 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
598 | struct iovec *vec, __vec[PIPE_DEF_BUFFERS]; |
599 | ssize_t res; |
600 | size_t this_len; |
601 | int error; |
602 | int i; |
603 | struct splice_pipe_desc spd = { |
604 | .pages = pages, |
605 | .partial = partial, |
606 | .nr_pages_max = PIPE_DEF_BUFFERS, |
607 | .flags = flags, |
608 | .ops = &default_pipe_buf_ops, |
609 | .spd_release = spd_release_page, |
610 | }; |
611 | |
612 | if (splice_grow_spd(pipe, &spd)) |
613 | return -ENOMEM; |
614 | |
615 | res = -ENOMEM; |
616 | vec = __vec; |
617 | if (spd.nr_pages_max > PIPE_DEF_BUFFERS) { |
618 | vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL); |
619 | if (!vec) |
620 | goto shrink_ret; |
621 | } |
622 | |
623 | offset = *ppos & ~PAGE_CACHE_MASK; |
624 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
625 | |
626 | for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) { |
627 | struct page *page; |
628 | |
629 | page = alloc_page(GFP_USER); |
630 | error = -ENOMEM; |
631 | if (!page) |
632 | goto err; |
633 | |
634 | this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); |
635 | vec[i].iov_base = (void __user *) page_address(page); |
636 | vec[i].iov_len = this_len; |
637 | spd.pages[i] = page; |
638 | spd.nr_pages++; |
639 | len -= this_len; |
640 | offset = 0; |
641 | } |
642 | |
643 | res = kernel_readv(in, vec, spd.nr_pages, *ppos); |
644 | if (res < 0) { |
645 | error = res; |
646 | goto err; |
647 | } |
648 | |
649 | error = 0; |
650 | if (!res) |
651 | goto err; |
652 | |
653 | nr_freed = 0; |
654 | for (i = 0; i < spd.nr_pages; i++) { |
655 | this_len = min_t(size_t, vec[i].iov_len, res); |
656 | spd.partial[i].offset = 0; |
657 | spd.partial[i].len = this_len; |
658 | if (!this_len) { |
659 | __free_page(spd.pages[i]); |
660 | spd.pages[i] = NULL; |
661 | nr_freed++; |
662 | } |
663 | res -= this_len; |
664 | } |
665 | spd.nr_pages -= nr_freed; |
666 | |
667 | res = splice_to_pipe(pipe, &spd); |
668 | if (res > 0) |
669 | *ppos += res; |
670 | |
671 | shrink_ret: |
672 | if (vec != __vec) |
673 | kfree(vec); |
674 | splice_shrink_spd(&spd); |
675 | return res; |
676 | |
677 | err: |
678 | for (i = 0; i < spd.nr_pages; i++) |
679 | __free_page(spd.pages[i]); |
680 | |
681 | res = error; |
682 | goto shrink_ret; |
683 | } |
684 | EXPORT_SYMBOL(default_file_splice_read); |
685 | |
686 | /* |
687 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
688 | * using sendpage(). Return the number of bytes sent. |
689 | */ |
690 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
691 | struct pipe_buffer *buf, struct splice_desc *sd) |
692 | { |
693 | struct file *file = sd->u.file; |
694 | loff_t pos = sd->pos; |
695 | int more; |
696 | |
697 | if (!likely(file->f_op && file->f_op->sendpage)) |
698 | return -EINVAL; |
699 | |
700 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
701 | |
702 | if (sd->len < sd->total_len && pipe->nrbufs > 1) |
703 | more |= MSG_SENDPAGE_NOTLAST; |
704 | |
705 | return file->f_op->sendpage(file, buf->page, buf->offset, |
706 | sd->len, &pos, more); |
707 | } |
708 | |
709 | /* |
710 | * This is a little more tricky than the file -> pipe splicing. There are |
711 | * basically three cases: |
712 | * |
713 | * - Destination page already exists in the address space and there |
714 | * are users of it. For that case we have no other option that |
715 | * copying the data. Tough luck. |
716 | * - Destination page already exists in the address space, but there |
717 | * are no users of it. Make sure it's uptodate, then drop it. Fall |
718 | * through to last case. |
719 | * - Destination page does not exist, we can add the pipe page to |
720 | * the page cache and avoid the copy. |
721 | * |
722 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
723 | * sd->flags), we attempt to migrate pages from the pipe to the output |
724 | * file address space page cache. This is possible if no one else has |
725 | * the pipe page referenced outside of the pipe and page cache. If |
726 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create |
727 | * a new page in the output file page cache and fill/dirty that. |
728 | */ |
729 | int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
730 | struct splice_desc *sd) |
731 | { |
732 | struct file *file = sd->u.file; |
733 | struct address_space *mapping = file->f_mapping; |
734 | unsigned int offset, this_len; |
735 | struct page *page; |
736 | void *fsdata; |
737 | int ret; |
738 | |
739 | offset = sd->pos & ~PAGE_CACHE_MASK; |
740 | |
741 | this_len = sd->len; |
742 | if (this_len + offset > PAGE_CACHE_SIZE) |
743 | this_len = PAGE_CACHE_SIZE - offset; |
744 | |
745 | ret = pagecache_write_begin(file, mapping, sd->pos, this_len, |
746 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); |
747 | if (unlikely(ret)) |
748 | goto out; |
749 | |
750 | if (buf->page != page) { |
751 | char *src = buf->ops->map(pipe, buf, 1); |
752 | char *dst = kmap_atomic(page); |
753 | |
754 | memcpy(dst + offset, src + buf->offset, this_len); |
755 | flush_dcache_page(page); |
756 | kunmap_atomic(dst); |
757 | buf->ops->unmap(pipe, buf, src); |
758 | } |
759 | ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, |
760 | page, fsdata); |
761 | out: |
762 | return ret; |
763 | } |
764 | EXPORT_SYMBOL(pipe_to_file); |
765 | |
766 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
767 | { |
768 | smp_mb(); |
769 | if (waitqueue_active(&pipe->wait)) |
770 | wake_up_interruptible(&pipe->wait); |
771 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
772 | } |
773 | |
774 | /** |
775 | * splice_from_pipe_feed - feed available data from a pipe to a file |
776 | * @pipe: pipe to splice from |
777 | * @sd: information to @actor |
778 | * @actor: handler that splices the data |
779 | * |
780 | * Description: |
781 | * This function loops over the pipe and calls @actor to do the |
782 | * actual moving of a single struct pipe_buffer to the desired |
783 | * destination. It returns when there's no more buffers left in |
784 | * the pipe or if the requested number of bytes (@sd->total_len) |
785 | * have been copied. It returns a positive number (one) if the |
786 | * pipe needs to be filled with more data, zero if the required |
787 | * number of bytes have been copied and -errno on error. |
788 | * |
789 | * This, together with splice_from_pipe_{begin,end,next}, may be |
790 | * used to implement the functionality of __splice_from_pipe() when |
791 | * locking is required around copying the pipe buffers to the |
792 | * destination. |
793 | */ |
794 | int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
795 | splice_actor *actor) |
796 | { |
797 | int ret; |
798 | |
799 | while (pipe->nrbufs) { |
800 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
801 | const struct pipe_buf_operations *ops = buf->ops; |
802 | |
803 | sd->len = buf->len; |
804 | if (sd->len > sd->total_len) |
805 | sd->len = sd->total_len; |
806 | |
807 | ret = buf->ops->confirm(pipe, buf); |
808 | if (unlikely(ret)) { |
809 | if (ret == -ENODATA) |
810 | ret = 0; |
811 | return ret; |
812 | } |
813 | |
814 | ret = actor(pipe, buf, sd); |
815 | if (ret <= 0) |
816 | return ret; |
817 | |
818 | buf->offset += ret; |
819 | buf->len -= ret; |
820 | |
821 | sd->num_spliced += ret; |
822 | sd->len -= ret; |
823 | sd->pos += ret; |
824 | sd->total_len -= ret; |
825 | |
826 | if (!buf->len) { |
827 | buf->ops = NULL; |
828 | ops->release(pipe, buf); |
829 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
830 | pipe->nrbufs--; |
831 | if (pipe->inode) |
832 | sd->need_wakeup = true; |
833 | } |
834 | |
835 | if (!sd->total_len) |
836 | return 0; |
837 | } |
838 | |
839 | return 1; |
840 | } |
841 | EXPORT_SYMBOL(splice_from_pipe_feed); |
842 | |
843 | /** |
844 | * splice_from_pipe_next - wait for some data to splice from |
845 | * @pipe: pipe to splice from |
846 | * @sd: information about the splice operation |
847 | * |
848 | * Description: |
849 | * This function will wait for some data and return a positive |
850 | * value (one) if pipe buffers are available. It will return zero |
851 | * or -errno if no more data needs to be spliced. |
852 | */ |
853 | int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
854 | { |
855 | while (!pipe->nrbufs) { |
856 | if (!pipe->writers) |
857 | return 0; |
858 | |
859 | if (!pipe->waiting_writers && sd->num_spliced) |
860 | return 0; |
861 | |
862 | if (sd->flags & SPLICE_F_NONBLOCK) |
863 | return -EAGAIN; |
864 | |
865 | if (signal_pending(current)) |
866 | return -ERESTARTSYS; |
867 | |
868 | if (sd->need_wakeup) { |
869 | wakeup_pipe_writers(pipe); |
870 | sd->need_wakeup = false; |
871 | } |
872 | |
873 | pipe_wait(pipe); |
874 | } |
875 | |
876 | return 1; |
877 | } |
878 | EXPORT_SYMBOL(splice_from_pipe_next); |
879 | |
880 | /** |
881 | * splice_from_pipe_begin - start splicing from pipe |
882 | * @sd: information about the splice operation |
883 | * |
884 | * Description: |
885 | * This function should be called before a loop containing |
886 | * splice_from_pipe_next() and splice_from_pipe_feed() to |
887 | * initialize the necessary fields of @sd. |
888 | */ |
889 | void splice_from_pipe_begin(struct splice_desc *sd) |
890 | { |
891 | sd->num_spliced = 0; |
892 | sd->need_wakeup = false; |
893 | } |
894 | EXPORT_SYMBOL(splice_from_pipe_begin); |
895 | |
896 | /** |
897 | * splice_from_pipe_end - finish splicing from pipe |
898 | * @pipe: pipe to splice from |
899 | * @sd: information about the splice operation |
900 | * |
901 | * Description: |
902 | * This function will wake up pipe writers if necessary. It should |
903 | * be called after a loop containing splice_from_pipe_next() and |
904 | * splice_from_pipe_feed(). |
905 | */ |
906 | void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
907 | { |
908 | if (sd->need_wakeup) |
909 | wakeup_pipe_writers(pipe); |
910 | } |
911 | EXPORT_SYMBOL(splice_from_pipe_end); |
912 | |
913 | /** |
914 | * __splice_from_pipe - splice data from a pipe to given actor |
915 | * @pipe: pipe to splice from |
916 | * @sd: information to @actor |
917 | * @actor: handler that splices the data |
918 | * |
919 | * Description: |
920 | * This function does little more than loop over the pipe and call |
921 | * @actor to do the actual moving of a single struct pipe_buffer to |
922 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or |
923 | * pipe_to_user. |
924 | * |
925 | */ |
926 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
927 | splice_actor *actor) |
928 | { |
929 | int ret; |
930 | |
931 | splice_from_pipe_begin(sd); |
932 | do { |
933 | ret = splice_from_pipe_next(pipe, sd); |
934 | if (ret > 0) |
935 | ret = splice_from_pipe_feed(pipe, sd, actor); |
936 | } while (ret > 0); |
937 | splice_from_pipe_end(pipe, sd); |
938 | |
939 | return sd->num_spliced ? sd->num_spliced : ret; |
940 | } |
941 | EXPORT_SYMBOL(__splice_from_pipe); |
942 | |
943 | /** |
944 | * splice_from_pipe - splice data from a pipe to a file |
945 | * @pipe: pipe to splice from |
946 | * @out: file to splice to |
947 | * @ppos: position in @out |
948 | * @len: how many bytes to splice |
949 | * @flags: splice modifier flags |
950 | * @actor: handler that splices the data |
951 | * |
952 | * Description: |
953 | * See __splice_from_pipe. This function locks the pipe inode, |
954 | * otherwise it's identical to __splice_from_pipe(). |
955 | * |
956 | */ |
957 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
958 | loff_t *ppos, size_t len, unsigned int flags, |
959 | splice_actor *actor) |
960 | { |
961 | ssize_t ret; |
962 | struct splice_desc sd = { |
963 | .total_len = len, |
964 | .flags = flags, |
965 | .pos = *ppos, |
966 | .u.file = out, |
967 | }; |
968 | |
969 | pipe_lock(pipe); |
970 | ret = __splice_from_pipe(pipe, &sd, actor); |
971 | pipe_unlock(pipe); |
972 | |
973 | return ret; |
974 | } |
975 | |
976 | /** |
977 | * generic_file_splice_write - splice data from a pipe to a file |
978 | * @pipe: pipe info |
979 | * @out: file to write to |
980 | * @ppos: position in @out |
981 | * @len: number of bytes to splice |
982 | * @flags: splice modifier flags |
983 | * |
984 | * Description: |
985 | * Will either move or copy pages (determined by @flags options) from |
986 | * the given pipe inode to the given file. |
987 | * |
988 | */ |
989 | ssize_t |
990 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, |
991 | loff_t *ppos, size_t len, unsigned int flags) |
992 | { |
993 | struct address_space *mapping = out->f_mapping; |
994 | struct inode *inode = mapping->host; |
995 | struct splice_desc sd = { |
996 | .total_len = len, |
997 | .flags = flags, |
998 | .pos = *ppos, |
999 | .u.file = out, |
1000 | }; |
1001 | ssize_t ret; |
1002 | |
1003 | sb_start_write(inode->i_sb); |
1004 | |
1005 | pipe_lock(pipe); |
1006 | |
1007 | splice_from_pipe_begin(&sd); |
1008 | do { |
1009 | ret = splice_from_pipe_next(pipe, &sd); |
1010 | if (ret <= 0) |
1011 | break; |
1012 | |
1013 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
1014 | ret = file_remove_suid(out); |
1015 | if (!ret) { |
1016 | ret = file_update_time(out); |
1017 | if (!ret) |
1018 | ret = splice_from_pipe_feed(pipe, &sd, |
1019 | pipe_to_file); |
1020 | } |
1021 | mutex_unlock(&inode->i_mutex); |
1022 | } while (ret > 0); |
1023 | splice_from_pipe_end(pipe, &sd); |
1024 | |
1025 | pipe_unlock(pipe); |
1026 | |
1027 | if (sd.num_spliced) |
1028 | ret = sd.num_spliced; |
1029 | |
1030 | if (ret > 0) { |
1031 | int err; |
1032 | |
1033 | err = generic_write_sync(out, *ppos, ret); |
1034 | if (err) |
1035 | ret = err; |
1036 | else |
1037 | *ppos += ret; |
1038 | balance_dirty_pages_ratelimited(mapping); |
1039 | } |
1040 | sb_end_write(inode->i_sb); |
1041 | |
1042 | return ret; |
1043 | } |
1044 | |
1045 | EXPORT_SYMBOL(generic_file_splice_write); |
1046 | |
1047 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1048 | struct splice_desc *sd) |
1049 | { |
1050 | int ret; |
1051 | void *data; |
1052 | loff_t tmp = sd->pos; |
1053 | |
1054 | data = buf->ops->map(pipe, buf, 0); |
1055 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); |
1056 | buf->ops->unmap(pipe, buf, data); |
1057 | |
1058 | return ret; |
1059 | } |
1060 | |
1061 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, |
1062 | struct file *out, loff_t *ppos, |
1063 | size_t len, unsigned int flags) |
1064 | { |
1065 | ssize_t ret; |
1066 | |
1067 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
1068 | if (ret > 0) |
1069 | *ppos += ret; |
1070 | |
1071 | return ret; |
1072 | } |
1073 | |
1074 | /** |
1075 | * generic_splice_sendpage - splice data from a pipe to a socket |
1076 | * @pipe: pipe to splice from |
1077 | * @out: socket to write to |
1078 | * @ppos: position in @out |
1079 | * @len: number of bytes to splice |
1080 | * @flags: splice modifier flags |
1081 | * |
1082 | * Description: |
1083 | * Will send @len bytes from the pipe to a network socket. No data copying |
1084 | * is involved. |
1085 | * |
1086 | */ |
1087 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
1088 | loff_t *ppos, size_t len, unsigned int flags) |
1089 | { |
1090 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
1091 | } |
1092 | |
1093 | EXPORT_SYMBOL(generic_splice_sendpage); |
1094 | |
1095 | /* |
1096 | * Attempt to initiate a splice from pipe to file. |
1097 | */ |
1098 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
1099 | loff_t *ppos, size_t len, unsigned int flags) |
1100 | { |
1101 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
1102 | loff_t *, size_t, unsigned int); |
1103 | int ret; |
1104 | |
1105 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1106 | return -EBADF; |
1107 | |
1108 | if (unlikely(out->f_flags & O_APPEND)) |
1109 | return -EINVAL; |
1110 | |
1111 | ret = rw_verify_area(WRITE, out, ppos, len); |
1112 | if (unlikely(ret < 0)) |
1113 | return ret; |
1114 | |
1115 | if (out->f_op && out->f_op->splice_write) |
1116 | splice_write = out->f_op->splice_write; |
1117 | else |
1118 | splice_write = default_file_splice_write; |
1119 | |
1120 | return splice_write(pipe, out, ppos, len, flags); |
1121 | } |
1122 | |
1123 | /* |
1124 | * Attempt to initiate a splice from a file to a pipe. |
1125 | */ |
1126 | static long do_splice_to(struct file *in, loff_t *ppos, |
1127 | struct pipe_inode_info *pipe, size_t len, |
1128 | unsigned int flags) |
1129 | { |
1130 | ssize_t (*splice_read)(struct file *, loff_t *, |
1131 | struct pipe_inode_info *, size_t, unsigned int); |
1132 | int ret; |
1133 | |
1134 | if (unlikely(!(in->f_mode & FMODE_READ))) |
1135 | return -EBADF; |
1136 | |
1137 | ret = rw_verify_area(READ, in, ppos, len); |
1138 | if (unlikely(ret < 0)) |
1139 | return ret; |
1140 | |
1141 | if (in->f_op && in->f_op->splice_read) |
1142 | splice_read = in->f_op->splice_read; |
1143 | else |
1144 | splice_read = default_file_splice_read; |
1145 | |
1146 | return splice_read(in, ppos, pipe, len, flags); |
1147 | } |
1148 | |
1149 | /** |
1150 | * splice_direct_to_actor - splices data directly between two non-pipes |
1151 | * @in: file to splice from |
1152 | * @sd: actor information on where to splice to |
1153 | * @actor: handles the data splicing |
1154 | * |
1155 | * Description: |
1156 | * This is a special case helper to splice directly between two |
1157 | * points, without requiring an explicit pipe. Internally an allocated |
1158 | * pipe is cached in the process, and reused during the lifetime of |
1159 | * that process. |
1160 | * |
1161 | */ |
1162 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, |
1163 | splice_direct_actor *actor) |
1164 | { |
1165 | struct pipe_inode_info *pipe; |
1166 | long ret, bytes; |
1167 | umode_t i_mode; |
1168 | size_t len; |
1169 | int i, flags; |
1170 | |
1171 | /* |
1172 | * We require the input being a regular file, as we don't want to |
1173 | * randomly drop data for eg socket -> socket splicing. Use the |
1174 | * piped splicing for that! |
1175 | */ |
1176 | i_mode = file_inode(in)->i_mode; |
1177 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
1178 | return -EINVAL; |
1179 | |
1180 | /* |
1181 | * neither in nor out is a pipe, setup an internal pipe attached to |
1182 | * 'out' and transfer the wanted data from 'in' to 'out' through that |
1183 | */ |
1184 | pipe = current->splice_pipe; |
1185 | if (unlikely(!pipe)) { |
1186 | pipe = alloc_pipe_info(NULL); |
1187 | if (!pipe) |
1188 | return -ENOMEM; |
1189 | |
1190 | /* |
1191 | * We don't have an immediate reader, but we'll read the stuff |
1192 | * out of the pipe right after the splice_to_pipe(). So set |
1193 | * PIPE_READERS appropriately. |
1194 | */ |
1195 | pipe->readers = 1; |
1196 | |
1197 | current->splice_pipe = pipe; |
1198 | } |
1199 | |
1200 | /* |
1201 | * Do the splice. |
1202 | */ |
1203 | ret = 0; |
1204 | bytes = 0; |
1205 | len = sd->total_len; |
1206 | flags = sd->flags; |
1207 | |
1208 | /* |
1209 | * Don't block on output, we have to drain the direct pipe. |
1210 | */ |
1211 | sd->flags &= ~SPLICE_F_NONBLOCK; |
1212 | |
1213 | while (len) { |
1214 | size_t read_len; |
1215 | loff_t pos = sd->pos, prev_pos = pos; |
1216 | |
1217 | ret = do_splice_to(in, &pos, pipe, len, flags); |
1218 | if (unlikely(ret <= 0)) |
1219 | goto out_release; |
1220 | |
1221 | read_len = ret; |
1222 | sd->total_len = read_len; |
1223 | |
1224 | /* |
1225 | * NOTE: nonblocking mode only applies to the input. We |
1226 | * must not do the output in nonblocking mode as then we |
1227 | * could get stuck data in the internal pipe: |
1228 | */ |
1229 | ret = actor(pipe, sd); |
1230 | if (unlikely(ret <= 0)) { |
1231 | sd->pos = prev_pos; |
1232 | goto out_release; |
1233 | } |
1234 | |
1235 | bytes += ret; |
1236 | len -= ret; |
1237 | sd->pos = pos; |
1238 | |
1239 | if (ret < read_len) { |
1240 | sd->pos = prev_pos + ret; |
1241 | goto out_release; |
1242 | } |
1243 | } |
1244 | |
1245 | done: |
1246 | pipe->nrbufs = pipe->curbuf = 0; |
1247 | file_accessed(in); |
1248 | return bytes; |
1249 | |
1250 | out_release: |
1251 | /* |
1252 | * If we did an incomplete transfer we must release |
1253 | * the pipe buffers in question: |
1254 | */ |
1255 | for (i = 0; i < pipe->buffers; i++) { |
1256 | struct pipe_buffer *buf = pipe->bufs + i; |
1257 | |
1258 | if (buf->ops) { |
1259 | buf->ops->release(pipe, buf); |
1260 | buf->ops = NULL; |
1261 | } |
1262 | } |
1263 | |
1264 | if (!bytes) |
1265 | bytes = ret; |
1266 | |
1267 | goto done; |
1268 | } |
1269 | EXPORT_SYMBOL(splice_direct_to_actor); |
1270 | |
1271 | static int direct_splice_actor(struct pipe_inode_info *pipe, |
1272 | struct splice_desc *sd) |
1273 | { |
1274 | struct file *file = sd->u.file; |
1275 | |
1276 | return do_splice_from(pipe, file, &file->f_pos, sd->total_len, |
1277 | sd->flags); |
1278 | } |
1279 | |
1280 | /** |
1281 | * do_splice_direct - splices data directly between two files |
1282 | * @in: file to splice from |
1283 | * @ppos: input file offset |
1284 | * @out: file to splice to |
1285 | * @len: number of bytes to splice |
1286 | * @flags: splice modifier flags |
1287 | * |
1288 | * Description: |
1289 | * For use by do_sendfile(). splice can easily emulate sendfile, but |
1290 | * doing it in the application would incur an extra system call |
1291 | * (splice in + splice out, as compared to just sendfile()). So this helper |
1292 | * can splice directly through a process-private pipe. |
1293 | * |
1294 | */ |
1295 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1296 | size_t len, unsigned int flags) |
1297 | { |
1298 | struct splice_desc sd = { |
1299 | .len = len, |
1300 | .total_len = len, |
1301 | .flags = flags, |
1302 | .pos = *ppos, |
1303 | .u.file = out, |
1304 | }; |
1305 | long ret; |
1306 | |
1307 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
1308 | if (ret > 0) |
1309 | *ppos = sd.pos; |
1310 | |
1311 | return ret; |
1312 | } |
1313 | |
1314 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1315 | struct pipe_inode_info *opipe, |
1316 | size_t len, unsigned int flags); |
1317 | |
1318 | /* |
1319 | * Determine where to splice to/from. |
1320 | */ |
1321 | static long do_splice(struct file *in, loff_t __user *off_in, |
1322 | struct file *out, loff_t __user *off_out, |
1323 | size_t len, unsigned int flags) |
1324 | { |
1325 | struct pipe_inode_info *ipipe; |
1326 | struct pipe_inode_info *opipe; |
1327 | loff_t offset, *off; |
1328 | long ret; |
1329 | |
1330 | ipipe = get_pipe_info(in); |
1331 | opipe = get_pipe_info(out); |
1332 | |
1333 | if (ipipe && opipe) { |
1334 | if (off_in || off_out) |
1335 | return -ESPIPE; |
1336 | |
1337 | if (!(in->f_mode & FMODE_READ)) |
1338 | return -EBADF; |
1339 | |
1340 | if (!(out->f_mode & FMODE_WRITE)) |
1341 | return -EBADF; |
1342 | |
1343 | /* Splicing to self would be fun, but... */ |
1344 | if (ipipe == opipe) |
1345 | return -EINVAL; |
1346 | |
1347 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1348 | } |
1349 | |
1350 | if (ipipe) { |
1351 | if (off_in) |
1352 | return -ESPIPE; |
1353 | if (off_out) { |
1354 | if (!(out->f_mode & FMODE_PWRITE)) |
1355 | return -EINVAL; |
1356 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
1357 | return -EFAULT; |
1358 | off = &offset; |
1359 | } else |
1360 | off = &out->f_pos; |
1361 | |
1362 | ret = do_splice_from(ipipe, out, off, len, flags); |
1363 | |
1364 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) |
1365 | ret = -EFAULT; |
1366 | |
1367 | return ret; |
1368 | } |
1369 | |
1370 | if (opipe) { |
1371 | if (off_out) |
1372 | return -ESPIPE; |
1373 | if (off_in) { |
1374 | if (!(in->f_mode & FMODE_PREAD)) |
1375 | return -EINVAL; |
1376 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
1377 | return -EFAULT; |
1378 | off = &offset; |
1379 | } else |
1380 | off = &in->f_pos; |
1381 | |
1382 | ret = do_splice_to(in, off, opipe, len, flags); |
1383 | |
1384 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) |
1385 | ret = -EFAULT; |
1386 | |
1387 | return ret; |
1388 | } |
1389 | |
1390 | return -EINVAL; |
1391 | } |
1392 | |
1393 | /* |
1394 | * Map an iov into an array of pages and offset/length tupples. With the |
1395 | * partial_page structure, we can map several non-contiguous ranges into |
1396 | * our ones pages[] map instead of splitting that operation into pieces. |
1397 | * Could easily be exported as a generic helper for other users, in which |
1398 | * case one would probably want to add a 'max_nr_pages' parameter as well. |
1399 | */ |
1400 | static int get_iovec_page_array(const struct iovec __user *iov, |
1401 | unsigned int nr_vecs, struct page **pages, |
1402 | struct partial_page *partial, bool aligned, |
1403 | unsigned int pipe_buffers) |
1404 | { |
1405 | int buffers = 0, error = 0; |
1406 | |
1407 | while (nr_vecs) { |
1408 | unsigned long off, npages; |
1409 | struct iovec entry; |
1410 | void __user *base; |
1411 | size_t len; |
1412 | int i; |
1413 | |
1414 | error = -EFAULT; |
1415 | if (copy_from_user(&entry, iov, sizeof(entry))) |
1416 | break; |
1417 | |
1418 | base = entry.iov_base; |
1419 | len = entry.iov_len; |
1420 | |
1421 | /* |
1422 | * Sanity check this iovec. 0 read succeeds. |
1423 | */ |
1424 | error = 0; |
1425 | if (unlikely(!len)) |
1426 | break; |
1427 | error = -EFAULT; |
1428 | if (!access_ok(VERIFY_READ, base, len)) |
1429 | break; |
1430 | |
1431 | /* |
1432 | * Get this base offset and number of pages, then map |
1433 | * in the user pages. |
1434 | */ |
1435 | off = (unsigned long) base & ~PAGE_MASK; |
1436 | |
1437 | /* |
1438 | * If asked for alignment, the offset must be zero and the |
1439 | * length a multiple of the PAGE_SIZE. |
1440 | */ |
1441 | error = -EINVAL; |
1442 | if (aligned && (off || len & ~PAGE_MASK)) |
1443 | break; |
1444 | |
1445 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1446 | if (npages > pipe_buffers - buffers) |
1447 | npages = pipe_buffers - buffers; |
1448 | |
1449 | error = get_user_pages_fast((unsigned long)base, npages, |
1450 | 0, &pages[buffers]); |
1451 | |
1452 | if (unlikely(error <= 0)) |
1453 | break; |
1454 | |
1455 | /* |
1456 | * Fill this contiguous range into the partial page map. |
1457 | */ |
1458 | for (i = 0; i < error; i++) { |
1459 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
1460 | |
1461 | partial[buffers].offset = off; |
1462 | partial[buffers].len = plen; |
1463 | |
1464 | off = 0; |
1465 | len -= plen; |
1466 | buffers++; |
1467 | } |
1468 | |
1469 | /* |
1470 | * We didn't complete this iov, stop here since it probably |
1471 | * means we have to move some of this into a pipe to |
1472 | * be able to continue. |
1473 | */ |
1474 | if (len) |
1475 | break; |
1476 | |
1477 | /* |
1478 | * Don't continue if we mapped fewer pages than we asked for, |
1479 | * or if we mapped the max number of pages that we have |
1480 | * room for. |
1481 | */ |
1482 | if (error < npages || buffers == pipe_buffers) |
1483 | break; |
1484 | |
1485 | nr_vecs--; |
1486 | iov++; |
1487 | } |
1488 | |
1489 | if (buffers) |
1490 | return buffers; |
1491 | |
1492 | return error; |
1493 | } |
1494 | |
1495 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1496 | struct splice_desc *sd) |
1497 | { |
1498 | char *src; |
1499 | int ret; |
1500 | |
1501 | /* |
1502 | * See if we can use the atomic maps, by prefaulting in the |
1503 | * pages and doing an atomic copy |
1504 | */ |
1505 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { |
1506 | src = buf->ops->map(pipe, buf, 1); |
1507 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, |
1508 | sd->len); |
1509 | buf->ops->unmap(pipe, buf, src); |
1510 | if (!ret) { |
1511 | ret = sd->len; |
1512 | goto out; |
1513 | } |
1514 | } |
1515 | |
1516 | /* |
1517 | * No dice, use slow non-atomic map and copy |
1518 | */ |
1519 | src = buf->ops->map(pipe, buf, 0); |
1520 | |
1521 | ret = sd->len; |
1522 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) |
1523 | ret = -EFAULT; |
1524 | |
1525 | buf->ops->unmap(pipe, buf, src); |
1526 | out: |
1527 | if (ret > 0) |
1528 | sd->u.userptr += ret; |
1529 | return ret; |
1530 | } |
1531 | |
1532 | /* |
1533 | * For lack of a better implementation, implement vmsplice() to userspace |
1534 | * as a simple copy of the pipes pages to the user iov. |
1535 | */ |
1536 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, |
1537 | unsigned long nr_segs, unsigned int flags) |
1538 | { |
1539 | struct pipe_inode_info *pipe; |
1540 | struct splice_desc sd; |
1541 | ssize_t size; |
1542 | int error; |
1543 | long ret; |
1544 | |
1545 | pipe = get_pipe_info(file); |
1546 | if (!pipe) |
1547 | return -EBADF; |
1548 | |
1549 | pipe_lock(pipe); |
1550 | |
1551 | error = ret = 0; |
1552 | while (nr_segs) { |
1553 | void __user *base; |
1554 | size_t len; |
1555 | |
1556 | /* |
1557 | * Get user address base and length for this iovec. |
1558 | */ |
1559 | error = get_user(base, &iov->iov_base); |
1560 | if (unlikely(error)) |
1561 | break; |
1562 | error = get_user(len, &iov->iov_len); |
1563 | if (unlikely(error)) |
1564 | break; |
1565 | |
1566 | /* |
1567 | * Sanity check this iovec. 0 read succeeds. |
1568 | */ |
1569 | if (unlikely(!len)) |
1570 | break; |
1571 | if (unlikely(!base)) { |
1572 | error = -EFAULT; |
1573 | break; |
1574 | } |
1575 | |
1576 | if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { |
1577 | error = -EFAULT; |
1578 | break; |
1579 | } |
1580 | |
1581 | sd.len = 0; |
1582 | sd.total_len = len; |
1583 | sd.flags = flags; |
1584 | sd.u.userptr = base; |
1585 | sd.pos = 0; |
1586 | |
1587 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); |
1588 | if (size < 0) { |
1589 | if (!ret) |
1590 | ret = size; |
1591 | |
1592 | break; |
1593 | } |
1594 | |
1595 | ret += size; |
1596 | |
1597 | if (size < len) |
1598 | break; |
1599 | |
1600 | nr_segs--; |
1601 | iov++; |
1602 | } |
1603 | |
1604 | pipe_unlock(pipe); |
1605 | |
1606 | if (!ret) |
1607 | ret = error; |
1608 | |
1609 | return ret; |
1610 | } |
1611 | |
1612 | /* |
1613 | * vmsplice splices a user address range into a pipe. It can be thought of |
1614 | * as splice-from-memory, where the regular splice is splice-from-file (or |
1615 | * to file). In both cases the output is a pipe, naturally. |
1616 | */ |
1617 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1618 | unsigned long nr_segs, unsigned int flags) |
1619 | { |
1620 | struct pipe_inode_info *pipe; |
1621 | struct page *pages[PIPE_DEF_BUFFERS]; |
1622 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1623 | struct splice_pipe_desc spd = { |
1624 | .pages = pages, |
1625 | .partial = partial, |
1626 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1627 | .flags = flags, |
1628 | .ops = &user_page_pipe_buf_ops, |
1629 | .spd_release = spd_release_page, |
1630 | }; |
1631 | long ret; |
1632 | |
1633 | pipe = get_pipe_info(file); |
1634 | if (!pipe) |
1635 | return -EBADF; |
1636 | |
1637 | if (splice_grow_spd(pipe, &spd)) |
1638 | return -ENOMEM; |
1639 | |
1640 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, |
1641 | spd.partial, false, |
1642 | spd.nr_pages_max); |
1643 | if (spd.nr_pages <= 0) |
1644 | ret = spd.nr_pages; |
1645 | else |
1646 | ret = splice_to_pipe(pipe, &spd); |
1647 | |
1648 | splice_shrink_spd(&spd); |
1649 | return ret; |
1650 | } |
1651 | |
1652 | /* |
1653 | * Note that vmsplice only really supports true splicing _from_ user memory |
1654 | * to a pipe, not the other way around. Splicing from user memory is a simple |
1655 | * operation that can be supported without any funky alignment restrictions |
1656 | * or nasty vm tricks. We simply map in the user memory and fill them into |
1657 | * a pipe. The reverse isn't quite as easy, though. There are two possible |
1658 | * solutions for that: |
1659 | * |
1660 | * - memcpy() the data internally, at which point we might as well just |
1661 | * do a regular read() on the buffer anyway. |
1662 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it |
1663 | * has restriction limitations on both ends of the pipe). |
1664 | * |
1665 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). |
1666 | * |
1667 | */ |
1668 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1669 | unsigned long, nr_segs, unsigned int, flags) |
1670 | { |
1671 | struct fd f; |
1672 | long error; |
1673 | |
1674 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1675 | return -EINVAL; |
1676 | else if (unlikely(!nr_segs)) |
1677 | return 0; |
1678 | |
1679 | error = -EBADF; |
1680 | f = fdget(fd); |
1681 | if (f.file) { |
1682 | if (f.file->f_mode & FMODE_WRITE) |
1683 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); |
1684 | else if (f.file->f_mode & FMODE_READ) |
1685 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); |
1686 | |
1687 | fdput(f); |
1688 | } |
1689 | |
1690 | return error; |
1691 | } |
1692 | |
1693 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1694 | int, fd_out, loff_t __user *, off_out, |
1695 | size_t, len, unsigned int, flags) |
1696 | { |
1697 | struct fd in, out; |
1698 | long error; |
1699 | |
1700 | if (unlikely(!len)) |
1701 | return 0; |
1702 | |
1703 | error = -EBADF; |
1704 | in = fdget(fd_in); |
1705 | if (in.file) { |
1706 | if (in.file->f_mode & FMODE_READ) { |
1707 | out = fdget(fd_out); |
1708 | if (out.file) { |
1709 | if (out.file->f_mode & FMODE_WRITE) |
1710 | error = do_splice(in.file, off_in, |
1711 | out.file, off_out, |
1712 | len, flags); |
1713 | fdput(out); |
1714 | } |
1715 | } |
1716 | fdput(in); |
1717 | } |
1718 | return error; |
1719 | } |
1720 | |
1721 | /* |
1722 | * Make sure there's data to read. Wait for input if we can, otherwise |
1723 | * return an appropriate error. |
1724 | */ |
1725 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1726 | { |
1727 | int ret; |
1728 | |
1729 | /* |
1730 | * Check ->nrbufs without the inode lock first. This function |
1731 | * is speculative anyways, so missing one is ok. |
1732 | */ |
1733 | if (pipe->nrbufs) |
1734 | return 0; |
1735 | |
1736 | ret = 0; |
1737 | pipe_lock(pipe); |
1738 | |
1739 | while (!pipe->nrbufs) { |
1740 | if (signal_pending(current)) { |
1741 | ret = -ERESTARTSYS; |
1742 | break; |
1743 | } |
1744 | if (!pipe->writers) |
1745 | break; |
1746 | if (!pipe->waiting_writers) { |
1747 | if (flags & SPLICE_F_NONBLOCK) { |
1748 | ret = -EAGAIN; |
1749 | break; |
1750 | } |
1751 | } |
1752 | pipe_wait(pipe); |
1753 | } |
1754 | |
1755 | pipe_unlock(pipe); |
1756 | return ret; |
1757 | } |
1758 | |
1759 | /* |
1760 | * Make sure there's writeable room. Wait for room if we can, otherwise |
1761 | * return an appropriate error. |
1762 | */ |
1763 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1764 | { |
1765 | int ret; |
1766 | |
1767 | /* |
1768 | * Check ->nrbufs without the inode lock first. This function |
1769 | * is speculative anyways, so missing one is ok. |
1770 | */ |
1771 | if (pipe->nrbufs < pipe->buffers) |
1772 | return 0; |
1773 | |
1774 | ret = 0; |
1775 | pipe_lock(pipe); |
1776 | |
1777 | while (pipe->nrbufs >= pipe->buffers) { |
1778 | if (!pipe->readers) { |
1779 | send_sig(SIGPIPE, current, 0); |
1780 | ret = -EPIPE; |
1781 | break; |
1782 | } |
1783 | if (flags & SPLICE_F_NONBLOCK) { |
1784 | ret = -EAGAIN; |
1785 | break; |
1786 | } |
1787 | if (signal_pending(current)) { |
1788 | ret = -ERESTARTSYS; |
1789 | break; |
1790 | } |
1791 | pipe->waiting_writers++; |
1792 | pipe_wait(pipe); |
1793 | pipe->waiting_writers--; |
1794 | } |
1795 | |
1796 | pipe_unlock(pipe); |
1797 | return ret; |
1798 | } |
1799 | |
1800 | /* |
1801 | * Splice contents of ipipe to opipe. |
1802 | */ |
1803 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1804 | struct pipe_inode_info *opipe, |
1805 | size_t len, unsigned int flags) |
1806 | { |
1807 | struct pipe_buffer *ibuf, *obuf; |
1808 | int ret = 0, nbuf; |
1809 | bool input_wakeup = false; |
1810 | |
1811 | |
1812 | retry: |
1813 | ret = ipipe_prep(ipipe, flags); |
1814 | if (ret) |
1815 | return ret; |
1816 | |
1817 | ret = opipe_prep(opipe, flags); |
1818 | if (ret) |
1819 | return ret; |
1820 | |
1821 | /* |
1822 | * Potential ABBA deadlock, work around it by ordering lock |
1823 | * grabbing by pipe info address. Otherwise two different processes |
1824 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1825 | */ |
1826 | pipe_double_lock(ipipe, opipe); |
1827 | |
1828 | do { |
1829 | if (!opipe->readers) { |
1830 | send_sig(SIGPIPE, current, 0); |
1831 | if (!ret) |
1832 | ret = -EPIPE; |
1833 | break; |
1834 | } |
1835 | |
1836 | if (!ipipe->nrbufs && !ipipe->writers) |
1837 | break; |
1838 | |
1839 | /* |
1840 | * Cannot make any progress, because either the input |
1841 | * pipe is empty or the output pipe is full. |
1842 | */ |
1843 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
1844 | /* Already processed some buffers, break */ |
1845 | if (ret) |
1846 | break; |
1847 | |
1848 | if (flags & SPLICE_F_NONBLOCK) { |
1849 | ret = -EAGAIN; |
1850 | break; |
1851 | } |
1852 | |
1853 | /* |
1854 | * We raced with another reader/writer and haven't |
1855 | * managed to process any buffers. A zero return |
1856 | * value means EOF, so retry instead. |
1857 | */ |
1858 | pipe_unlock(ipipe); |
1859 | pipe_unlock(opipe); |
1860 | goto retry; |
1861 | } |
1862 | |
1863 | ibuf = ipipe->bufs + ipipe->curbuf; |
1864 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1865 | obuf = opipe->bufs + nbuf; |
1866 | |
1867 | if (len >= ibuf->len) { |
1868 | /* |
1869 | * Simply move the whole buffer from ipipe to opipe |
1870 | */ |
1871 | *obuf = *ibuf; |
1872 | ibuf->ops = NULL; |
1873 | opipe->nrbufs++; |
1874 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
1875 | ipipe->nrbufs--; |
1876 | input_wakeup = true; |
1877 | } else { |
1878 | /* |
1879 | * Get a reference to this pipe buffer, |
1880 | * so we can copy the contents over. |
1881 | */ |
1882 | ibuf->ops->get(ipipe, ibuf); |
1883 | *obuf = *ibuf; |
1884 | |
1885 | /* |
1886 | * Don't inherit the gift flag, we need to |
1887 | * prevent multiple steals of this page. |
1888 | */ |
1889 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1890 | |
1891 | obuf->len = len; |
1892 | opipe->nrbufs++; |
1893 | ibuf->offset += obuf->len; |
1894 | ibuf->len -= obuf->len; |
1895 | } |
1896 | ret += obuf->len; |
1897 | len -= obuf->len; |
1898 | } while (len); |
1899 | |
1900 | pipe_unlock(ipipe); |
1901 | pipe_unlock(opipe); |
1902 | |
1903 | /* |
1904 | * If we put data in the output pipe, wakeup any potential readers. |
1905 | */ |
1906 | if (ret > 0) |
1907 | wakeup_pipe_readers(opipe); |
1908 | |
1909 | if (input_wakeup) |
1910 | wakeup_pipe_writers(ipipe); |
1911 | |
1912 | return ret; |
1913 | } |
1914 | |
1915 | /* |
1916 | * Link contents of ipipe to opipe. |
1917 | */ |
1918 | static int link_pipe(struct pipe_inode_info *ipipe, |
1919 | struct pipe_inode_info *opipe, |
1920 | size_t len, unsigned int flags) |
1921 | { |
1922 | struct pipe_buffer *ibuf, *obuf; |
1923 | int ret = 0, i = 0, nbuf; |
1924 | |
1925 | /* |
1926 | * Potential ABBA deadlock, work around it by ordering lock |
1927 | * grabbing by pipe info address. Otherwise two different processes |
1928 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1929 | */ |
1930 | pipe_double_lock(ipipe, opipe); |
1931 | |
1932 | do { |
1933 | if (!opipe->readers) { |
1934 | send_sig(SIGPIPE, current, 0); |
1935 | if (!ret) |
1936 | ret = -EPIPE; |
1937 | break; |
1938 | } |
1939 | |
1940 | /* |
1941 | * If we have iterated all input buffers or ran out of |
1942 | * output room, break. |
1943 | */ |
1944 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
1945 | break; |
1946 | |
1947 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
1948 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1949 | |
1950 | /* |
1951 | * Get a reference to this pipe buffer, |
1952 | * so we can copy the contents over. |
1953 | */ |
1954 | ibuf->ops->get(ipipe, ibuf); |
1955 | |
1956 | obuf = opipe->bufs + nbuf; |
1957 | *obuf = *ibuf; |
1958 | |
1959 | /* |
1960 | * Don't inherit the gift flag, we need to |
1961 | * prevent multiple steals of this page. |
1962 | */ |
1963 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1964 | |
1965 | if (obuf->len > len) |
1966 | obuf->len = len; |
1967 | |
1968 | opipe->nrbufs++; |
1969 | ret += obuf->len; |
1970 | len -= obuf->len; |
1971 | i++; |
1972 | } while (len); |
1973 | |
1974 | /* |
1975 | * return EAGAIN if we have the potential of some data in the |
1976 | * future, otherwise just return 0 |
1977 | */ |
1978 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) |
1979 | ret = -EAGAIN; |
1980 | |
1981 | pipe_unlock(ipipe); |
1982 | pipe_unlock(opipe); |
1983 | |
1984 | /* |
1985 | * If we put data in the output pipe, wakeup any potential readers. |
1986 | */ |
1987 | if (ret > 0) |
1988 | wakeup_pipe_readers(opipe); |
1989 | |
1990 | return ret; |
1991 | } |
1992 | |
1993 | /* |
1994 | * This is a tee(1) implementation that works on pipes. It doesn't copy |
1995 | * any data, it simply references the 'in' pages on the 'out' pipe. |
1996 | * The 'flags' used are the SPLICE_F_* variants, currently the only |
1997 | * applicable one is SPLICE_F_NONBLOCK. |
1998 | */ |
1999 | static long do_tee(struct file *in, struct file *out, size_t len, |
2000 | unsigned int flags) |
2001 | { |
2002 | struct pipe_inode_info *ipipe = get_pipe_info(in); |
2003 | struct pipe_inode_info *opipe = get_pipe_info(out); |
2004 | int ret = -EINVAL; |
2005 | |
2006 | /* |
2007 | * Duplicate the contents of ipipe to opipe without actually |
2008 | * copying the data. |
2009 | */ |
2010 | if (ipipe && opipe && ipipe != opipe) { |
2011 | /* |
2012 | * Keep going, unless we encounter an error. The ipipe/opipe |
2013 | * ordering doesn't really matter. |
2014 | */ |
2015 | ret = ipipe_prep(ipipe, flags); |
2016 | if (!ret) { |
2017 | ret = opipe_prep(opipe, flags); |
2018 | if (!ret) |
2019 | ret = link_pipe(ipipe, opipe, len, flags); |
2020 | } |
2021 | } |
2022 | |
2023 | return ret; |
2024 | } |
2025 | |
2026 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
2027 | { |
2028 | struct fd in; |
2029 | int error; |
2030 | |
2031 | if (unlikely(!len)) |
2032 | return 0; |
2033 | |
2034 | error = -EBADF; |
2035 | in = fdget(fdin); |
2036 | if (in.file) { |
2037 | if (in.file->f_mode & FMODE_READ) { |
2038 | struct fd out = fdget(fdout); |
2039 | if (out.file) { |
2040 | if (out.file->f_mode & FMODE_WRITE) |
2041 | error = do_tee(in.file, out.file, |
2042 | len, flags); |
2043 | fdput(out); |
2044 | } |
2045 | } |
2046 | fdput(in); |
2047 | } |
2048 | |
2049 | return error; |
2050 | } |
2051 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9