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1 | /* |
2 | * "splice": joining two ropes together by interweaving their strands. |
3 | * |
4 | * This is the "extended pipe" functionality, where a pipe is used as |
5 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel |
6 | * buffer that you can use to transfer data from one end to the other. |
7 | * |
8 | * The traditional unix read/write is extended with a "splice()" operation |
9 | * that transfers data buffers to or from a pipe buffer. |
10 | * |
11 | * Named by Larry McVoy, original implementation from Linus, extended by |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. |
14 | * |
15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> |
18 | * |
19 | */ |
20 | #include <linux/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/buffer_head.h> |
29 | #include <linux/module.h> |
30 | #include <linux/syscalls.h> |
31 | #include <linux/uio.h> |
32 | #include <linux/security.h> |
33 | #include <linux/gfp.h> |
34 | |
35 | /* |
36 | * Attempt to steal a page from a pipe buffer. This should perhaps go into |
37 | * a vm helper function, it's already simplified quite a bit by the |
38 | * addition of remove_mapping(). If success is returned, the caller may |
39 | * attempt to reuse this page for another destination. |
40 | */ |
41 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
42 | struct pipe_buffer *buf) |
43 | { |
44 | struct page *page = buf->page; |
45 | struct address_space *mapping; |
46 | |
47 | lock_page(page); |
48 | |
49 | mapping = page_mapping(page); |
50 | if (mapping) { |
51 | WARN_ON(!PageUptodate(page)); |
52 | |
53 | /* |
54 | * At least for ext2 with nobh option, we need to wait on |
55 | * writeback completing on this page, since we'll remove it |
56 | * from the pagecache. Otherwise truncate wont wait on the |
57 | * page, allowing the disk blocks to be reused by someone else |
58 | * before we actually wrote our data to them. fs corruption |
59 | * ensues. |
60 | */ |
61 | wait_on_page_writeback(page); |
62 | |
63 | if (page_has_private(page) && |
64 | !try_to_release_page(page, GFP_KERNEL)) |
65 | goto out_unlock; |
66 | |
67 | /* |
68 | * If we succeeded in removing the mapping, set LRU flag |
69 | * and return good. |
70 | */ |
71 | if (remove_mapping(mapping, page)) { |
72 | buf->flags |= PIPE_BUF_FLAG_LRU; |
73 | return 0; |
74 | } |
75 | } |
76 | |
77 | /* |
78 | * Raced with truncate or failed to remove page from current |
79 | * address space, unlock and return failure. |
80 | */ |
81 | out_unlock: |
82 | unlock_page(page); |
83 | return 1; |
84 | } |
85 | |
86 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
87 | struct pipe_buffer *buf) |
88 | { |
89 | page_cache_release(buf->page); |
90 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
91 | } |
92 | |
93 | /* |
94 | * Check whether the contents of buf is OK to access. Since the content |
95 | * is a page cache page, IO may be in flight. |
96 | */ |
97 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
98 | struct pipe_buffer *buf) |
99 | { |
100 | struct page *page = buf->page; |
101 | int err; |
102 | |
103 | if (!PageUptodate(page)) { |
104 | lock_page(page); |
105 | |
106 | /* |
107 | * Page got truncated/unhashed. This will cause a 0-byte |
108 | * splice, if this is the first page. |
109 | */ |
110 | if (!page->mapping) { |
111 | err = -ENODATA; |
112 | goto error; |
113 | } |
114 | |
115 | /* |
116 | * Uh oh, read-error from disk. |
117 | */ |
118 | if (!PageUptodate(page)) { |
119 | err = -EIO; |
120 | goto error; |
121 | } |
122 | |
123 | /* |
124 | * Page is ok afterall, we are done. |
125 | */ |
126 | unlock_page(page); |
127 | } |
128 | |
129 | return 0; |
130 | error: |
131 | unlock_page(page); |
132 | return err; |
133 | } |
134 | |
135 | static const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
136 | .can_merge = 0, |
137 | .map = generic_pipe_buf_map, |
138 | .unmap = generic_pipe_buf_unmap, |
139 | .confirm = page_cache_pipe_buf_confirm, |
140 | .release = page_cache_pipe_buf_release, |
141 | .steal = page_cache_pipe_buf_steal, |
142 | .get = generic_pipe_buf_get, |
143 | }; |
144 | |
145 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
146 | struct pipe_buffer *buf) |
147 | { |
148 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
149 | return 1; |
150 | |
151 | buf->flags |= PIPE_BUF_FLAG_LRU; |
152 | return generic_pipe_buf_steal(pipe, buf); |
153 | } |
154 | |
155 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
156 | .can_merge = 0, |
157 | .map = generic_pipe_buf_map, |
158 | .unmap = generic_pipe_buf_unmap, |
159 | .confirm = generic_pipe_buf_confirm, |
160 | .release = page_cache_pipe_buf_release, |
161 | .steal = user_page_pipe_buf_steal, |
162 | .get = generic_pipe_buf_get, |
163 | }; |
164 | |
165 | /** |
166 | * splice_to_pipe - fill passed data into a pipe |
167 | * @pipe: pipe to fill |
168 | * @spd: data to fill |
169 | * |
170 | * Description: |
171 | * @spd contains a map of pages and len/offset tuples, along with |
172 | * the struct pipe_buf_operations associated with these pages. This |
173 | * function will link that data to the pipe. |
174 | * |
175 | */ |
176 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
177 | struct splice_pipe_desc *spd) |
178 | { |
179 | unsigned int spd_pages = spd->nr_pages; |
180 | int ret, do_wakeup, page_nr; |
181 | |
182 | ret = 0; |
183 | do_wakeup = 0; |
184 | page_nr = 0; |
185 | |
186 | pipe_lock(pipe); |
187 | |
188 | for (;;) { |
189 | if (!pipe->readers) { |
190 | send_sig(SIGPIPE, current, 0); |
191 | if (!ret) |
192 | ret = -EPIPE; |
193 | break; |
194 | } |
195 | |
196 | if (pipe->nrbufs < PIPE_BUFFERS) { |
197 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); |
198 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
199 | |
200 | buf->page = spd->pages[page_nr]; |
201 | buf->offset = spd->partial[page_nr].offset; |
202 | buf->len = spd->partial[page_nr].len; |
203 | buf->private = spd->partial[page_nr].private; |
204 | buf->ops = spd->ops; |
205 | if (spd->flags & SPLICE_F_GIFT) |
206 | buf->flags |= PIPE_BUF_FLAG_GIFT; |
207 | |
208 | pipe->nrbufs++; |
209 | page_nr++; |
210 | ret += buf->len; |
211 | |
212 | if (pipe->inode) |
213 | do_wakeup = 1; |
214 | |
215 | if (!--spd->nr_pages) |
216 | break; |
217 | if (pipe->nrbufs < PIPE_BUFFERS) |
218 | continue; |
219 | |
220 | break; |
221 | } |
222 | |
223 | if (spd->flags & SPLICE_F_NONBLOCK) { |
224 | if (!ret) |
225 | ret = -EAGAIN; |
226 | break; |
227 | } |
228 | |
229 | if (signal_pending(current)) { |
230 | if (!ret) |
231 | ret = -ERESTARTSYS; |
232 | break; |
233 | } |
234 | |
235 | if (do_wakeup) { |
236 | smp_mb(); |
237 | if (waitqueue_active(&pipe->wait)) |
238 | wake_up_interruptible_sync(&pipe->wait); |
239 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
240 | do_wakeup = 0; |
241 | } |
242 | |
243 | pipe->waiting_writers++; |
244 | pipe_wait(pipe); |
245 | pipe->waiting_writers--; |
246 | } |
247 | |
248 | pipe_unlock(pipe); |
249 | |
250 | if (do_wakeup) { |
251 | smp_mb(); |
252 | if (waitqueue_active(&pipe->wait)) |
253 | wake_up_interruptible(&pipe->wait); |
254 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
255 | } |
256 | |
257 | while (page_nr < spd_pages) |
258 | spd->spd_release(spd, page_nr++); |
259 | |
260 | return ret; |
261 | } |
262 | |
263 | static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
264 | { |
265 | page_cache_release(spd->pages[i]); |
266 | } |
267 | |
268 | static int |
269 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
270 | struct pipe_inode_info *pipe, size_t len, |
271 | unsigned int flags) |
272 | { |
273 | struct address_space *mapping = in->f_mapping; |
274 | unsigned int loff, nr_pages, req_pages; |
275 | struct page *pages[PIPE_BUFFERS]; |
276 | struct partial_page partial[PIPE_BUFFERS]; |
277 | struct page *page; |
278 | pgoff_t index, end_index; |
279 | loff_t isize; |
280 | int error, page_nr; |
281 | struct splice_pipe_desc spd = { |
282 | .pages = pages, |
283 | .partial = partial, |
284 | .flags = flags, |
285 | .ops = &page_cache_pipe_buf_ops, |
286 | .spd_release = spd_release_page, |
287 | }; |
288 | |
289 | index = *ppos >> PAGE_CACHE_SHIFT; |
290 | loff = *ppos & ~PAGE_CACHE_MASK; |
291 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
292 | nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS); |
293 | |
294 | /* |
295 | * Lookup the (hopefully) full range of pages we need. |
296 | */ |
297 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); |
298 | index += spd.nr_pages; |
299 | |
300 | /* |
301 | * If find_get_pages_contig() returned fewer pages than we needed, |
302 | * readahead/allocate the rest and fill in the holes. |
303 | */ |
304 | if (spd.nr_pages < nr_pages) |
305 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
306 | index, req_pages - spd.nr_pages); |
307 | |
308 | error = 0; |
309 | while (spd.nr_pages < nr_pages) { |
310 | /* |
311 | * Page could be there, find_get_pages_contig() breaks on |
312 | * the first hole. |
313 | */ |
314 | page = find_get_page(mapping, index); |
315 | if (!page) { |
316 | /* |
317 | * page didn't exist, allocate one. |
318 | */ |
319 | page = page_cache_alloc_cold(mapping); |
320 | if (!page) |
321 | break; |
322 | |
323 | error = add_to_page_cache_lru(page, mapping, index, |
324 | mapping_gfp_mask(mapping)); |
325 | if (unlikely(error)) { |
326 | page_cache_release(page); |
327 | if (error == -EEXIST) |
328 | continue; |
329 | break; |
330 | } |
331 | /* |
332 | * add_to_page_cache() locks the page, unlock it |
333 | * to avoid convoluting the logic below even more. |
334 | */ |
335 | unlock_page(page); |
336 | } |
337 | |
338 | pages[spd.nr_pages++] = page; |
339 | index++; |
340 | } |
341 | |
342 | /* |
343 | * Now loop over the map and see if we need to start IO on any |
344 | * pages, fill in the partial map, etc. |
345 | */ |
346 | index = *ppos >> PAGE_CACHE_SHIFT; |
347 | nr_pages = spd.nr_pages; |
348 | spd.nr_pages = 0; |
349 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
350 | unsigned int this_len; |
351 | |
352 | if (!len) |
353 | break; |
354 | |
355 | /* |
356 | * this_len is the max we'll use from this page |
357 | */ |
358 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
359 | page = pages[page_nr]; |
360 | |
361 | if (PageReadahead(page)) |
362 | page_cache_async_readahead(mapping, &in->f_ra, in, |
363 | page, index, req_pages - page_nr); |
364 | |
365 | /* |
366 | * If the page isn't uptodate, we may need to start io on it |
367 | */ |
368 | if (!PageUptodate(page)) { |
369 | /* |
370 | * If in nonblock mode then dont block on waiting |
371 | * for an in-flight io page |
372 | */ |
373 | if (flags & SPLICE_F_NONBLOCK) { |
374 | if (!trylock_page(page)) { |
375 | error = -EAGAIN; |
376 | break; |
377 | } |
378 | } else |
379 | lock_page(page); |
380 | |
381 | /* |
382 | * Page was truncated, or invalidated by the |
383 | * filesystem. Redo the find/create, but this time the |
384 | * page is kept locked, so there's no chance of another |
385 | * race with truncate/invalidate. |
386 | */ |
387 | if (!page->mapping) { |
388 | unlock_page(page); |
389 | page = find_or_create_page(mapping, index, |
390 | mapping_gfp_mask(mapping)); |
391 | |
392 | if (!page) { |
393 | error = -ENOMEM; |
394 | break; |
395 | } |
396 | page_cache_release(pages[page_nr]); |
397 | pages[page_nr] = page; |
398 | } |
399 | /* |
400 | * page was already under io and is now done, great |
401 | */ |
402 | if (PageUptodate(page)) { |
403 | unlock_page(page); |
404 | goto fill_it; |
405 | } |
406 | |
407 | /* |
408 | * need to read in the page |
409 | */ |
410 | error = mapping->a_ops->readpage(in, page); |
411 | if (unlikely(error)) { |
412 | /* |
413 | * We really should re-lookup the page here, |
414 | * but it complicates things a lot. Instead |
415 | * lets just do what we already stored, and |
416 | * we'll get it the next time we are called. |
417 | */ |
418 | if (error == AOP_TRUNCATED_PAGE) |
419 | error = 0; |
420 | |
421 | break; |
422 | } |
423 | } |
424 | fill_it: |
425 | /* |
426 | * i_size must be checked after PageUptodate. |
427 | */ |
428 | isize = i_size_read(mapping->host); |
429 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
430 | if (unlikely(!isize || index > end_index)) |
431 | break; |
432 | |
433 | /* |
434 | * if this is the last page, see if we need to shrink |
435 | * the length and stop |
436 | */ |
437 | if (end_index == index) { |
438 | unsigned int plen; |
439 | |
440 | /* |
441 | * max good bytes in this page |
442 | */ |
443 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
444 | if (plen <= loff) |
445 | break; |
446 | |
447 | /* |
448 | * force quit after adding this page |
449 | */ |
450 | this_len = min(this_len, plen - loff); |
451 | len = this_len; |
452 | } |
453 | |
454 | partial[page_nr].offset = loff; |
455 | partial[page_nr].len = this_len; |
456 | len -= this_len; |
457 | loff = 0; |
458 | spd.nr_pages++; |
459 | index++; |
460 | } |
461 | |
462 | /* |
463 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
464 | * we got, 'nr_pages' is how many pages are in the map. |
465 | */ |
466 | while (page_nr < nr_pages) |
467 | page_cache_release(pages[page_nr++]); |
468 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
469 | |
470 | if (spd.nr_pages) |
471 | return splice_to_pipe(pipe, &spd); |
472 | |
473 | return error; |
474 | } |
475 | |
476 | /** |
477 | * generic_file_splice_read - splice data from file to a pipe |
478 | * @in: file to splice from |
479 | * @ppos: position in @in |
480 | * @pipe: pipe to splice to |
481 | * @len: number of bytes to splice |
482 | * @flags: splice modifier flags |
483 | * |
484 | * Description: |
485 | * Will read pages from given file and fill them into a pipe. Can be |
486 | * used as long as the address_space operations for the source implements |
487 | * a readpage() hook. |
488 | * |
489 | */ |
490 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
491 | struct pipe_inode_info *pipe, size_t len, |
492 | unsigned int flags) |
493 | { |
494 | loff_t isize, left; |
495 | int ret; |
496 | |
497 | isize = i_size_read(in->f_mapping->host); |
498 | if (unlikely(*ppos >= isize)) |
499 | return 0; |
500 | |
501 | left = isize - *ppos; |
502 | if (unlikely(left < len)) |
503 | len = left; |
504 | |
505 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
506 | if (ret > 0) { |
507 | *ppos += ret; |
508 | file_accessed(in); |
509 | } |
510 | |
511 | return ret; |
512 | } |
513 | EXPORT_SYMBOL(generic_file_splice_read); |
514 | |
515 | static const struct pipe_buf_operations default_pipe_buf_ops = { |
516 | .can_merge = 0, |
517 | .map = generic_pipe_buf_map, |
518 | .unmap = generic_pipe_buf_unmap, |
519 | .confirm = generic_pipe_buf_confirm, |
520 | .release = generic_pipe_buf_release, |
521 | .steal = generic_pipe_buf_steal, |
522 | .get = generic_pipe_buf_get, |
523 | }; |
524 | |
525 | static ssize_t kernel_readv(struct file *file, const struct iovec *vec, |
526 | unsigned long vlen, loff_t offset) |
527 | { |
528 | mm_segment_t old_fs; |
529 | loff_t pos = offset; |
530 | ssize_t res; |
531 | |
532 | old_fs = get_fs(); |
533 | set_fs(get_ds()); |
534 | /* The cast to a user pointer is valid due to the set_fs() */ |
535 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos); |
536 | set_fs(old_fs); |
537 | |
538 | return res; |
539 | } |
540 | |
541 | static ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
542 | loff_t pos) |
543 | { |
544 | mm_segment_t old_fs; |
545 | ssize_t res; |
546 | |
547 | old_fs = get_fs(); |
548 | set_fs(get_ds()); |
549 | /* The cast to a user pointer is valid due to the set_fs() */ |
550 | res = vfs_write(file, (const char __user *)buf, count, &pos); |
551 | set_fs(old_fs); |
552 | |
553 | return res; |
554 | } |
555 | |
556 | ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
557 | struct pipe_inode_info *pipe, size_t len, |
558 | unsigned int flags) |
559 | { |
560 | unsigned int nr_pages; |
561 | unsigned int nr_freed; |
562 | size_t offset; |
563 | struct page *pages[PIPE_BUFFERS]; |
564 | struct partial_page partial[PIPE_BUFFERS]; |
565 | struct iovec vec[PIPE_BUFFERS]; |
566 | pgoff_t index; |
567 | ssize_t res; |
568 | size_t this_len; |
569 | int error; |
570 | int i; |
571 | struct splice_pipe_desc spd = { |
572 | .pages = pages, |
573 | .partial = partial, |
574 | .flags = flags, |
575 | .ops = &default_pipe_buf_ops, |
576 | .spd_release = spd_release_page, |
577 | }; |
578 | |
579 | index = *ppos >> PAGE_CACHE_SHIFT; |
580 | offset = *ppos & ~PAGE_CACHE_MASK; |
581 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
582 | |
583 | for (i = 0; i < nr_pages && i < PIPE_BUFFERS && len; i++) { |
584 | struct page *page; |
585 | |
586 | page = alloc_page(GFP_USER); |
587 | error = -ENOMEM; |
588 | if (!page) |
589 | goto err; |
590 | |
591 | this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); |
592 | vec[i].iov_base = (void __user *) page_address(page); |
593 | vec[i].iov_len = this_len; |
594 | pages[i] = page; |
595 | spd.nr_pages++; |
596 | len -= this_len; |
597 | offset = 0; |
598 | } |
599 | |
600 | res = kernel_readv(in, vec, spd.nr_pages, *ppos); |
601 | if (res < 0) { |
602 | error = res; |
603 | goto err; |
604 | } |
605 | |
606 | error = 0; |
607 | if (!res) |
608 | goto err; |
609 | |
610 | nr_freed = 0; |
611 | for (i = 0; i < spd.nr_pages; i++) { |
612 | this_len = min_t(size_t, vec[i].iov_len, res); |
613 | partial[i].offset = 0; |
614 | partial[i].len = this_len; |
615 | if (!this_len) { |
616 | __free_page(pages[i]); |
617 | pages[i] = NULL; |
618 | nr_freed++; |
619 | } |
620 | res -= this_len; |
621 | } |
622 | spd.nr_pages -= nr_freed; |
623 | |
624 | res = splice_to_pipe(pipe, &spd); |
625 | if (res > 0) |
626 | *ppos += res; |
627 | |
628 | return res; |
629 | |
630 | err: |
631 | for (i = 0; i < spd.nr_pages; i++) |
632 | __free_page(pages[i]); |
633 | |
634 | return error; |
635 | } |
636 | EXPORT_SYMBOL(default_file_splice_read); |
637 | |
638 | /* |
639 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
640 | * using sendpage(). Return the number of bytes sent. |
641 | */ |
642 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
643 | struct pipe_buffer *buf, struct splice_desc *sd) |
644 | { |
645 | struct file *file = sd->u.file; |
646 | loff_t pos = sd->pos; |
647 | int ret, more; |
648 | |
649 | ret = buf->ops->confirm(pipe, buf); |
650 | if (!ret) { |
651 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
652 | if (file->f_op && file->f_op->sendpage) |
653 | ret = file->f_op->sendpage(file, buf->page, buf->offset, |
654 | sd->len, &pos, more); |
655 | else |
656 | ret = -EINVAL; |
657 | } |
658 | |
659 | return ret; |
660 | } |
661 | |
662 | /* |
663 | * This is a little more tricky than the file -> pipe splicing. There are |
664 | * basically three cases: |
665 | * |
666 | * - Destination page already exists in the address space and there |
667 | * are users of it. For that case we have no other option that |
668 | * copying the data. Tough luck. |
669 | * - Destination page already exists in the address space, but there |
670 | * are no users of it. Make sure it's uptodate, then drop it. Fall |
671 | * through to last case. |
672 | * - Destination page does not exist, we can add the pipe page to |
673 | * the page cache and avoid the copy. |
674 | * |
675 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
676 | * sd->flags), we attempt to migrate pages from the pipe to the output |
677 | * file address space page cache. This is possible if no one else has |
678 | * the pipe page referenced outside of the pipe and page cache. If |
679 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create |
680 | * a new page in the output file page cache and fill/dirty that. |
681 | */ |
682 | int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
683 | struct splice_desc *sd) |
684 | { |
685 | struct file *file = sd->u.file; |
686 | struct address_space *mapping = file->f_mapping; |
687 | unsigned int offset, this_len; |
688 | struct page *page; |
689 | void *fsdata; |
690 | int ret; |
691 | |
692 | /* |
693 | * make sure the data in this buffer is uptodate |
694 | */ |
695 | ret = buf->ops->confirm(pipe, buf); |
696 | if (unlikely(ret)) |
697 | return ret; |
698 | |
699 | offset = sd->pos & ~PAGE_CACHE_MASK; |
700 | |
701 | this_len = sd->len; |
702 | if (this_len + offset > PAGE_CACHE_SIZE) |
703 | this_len = PAGE_CACHE_SIZE - offset; |
704 | |
705 | ret = pagecache_write_begin(file, mapping, sd->pos, this_len, |
706 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); |
707 | if (unlikely(ret)) |
708 | goto out; |
709 | |
710 | if (buf->page != page) { |
711 | /* |
712 | * Careful, ->map() uses KM_USER0! |
713 | */ |
714 | char *src = buf->ops->map(pipe, buf, 1); |
715 | char *dst = kmap_atomic(page, KM_USER1); |
716 | |
717 | memcpy(dst + offset, src + buf->offset, this_len); |
718 | flush_dcache_page(page); |
719 | kunmap_atomic(dst, KM_USER1); |
720 | buf->ops->unmap(pipe, buf, src); |
721 | } |
722 | ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, |
723 | page, fsdata); |
724 | out: |
725 | return ret; |
726 | } |
727 | EXPORT_SYMBOL(pipe_to_file); |
728 | |
729 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
730 | { |
731 | smp_mb(); |
732 | if (waitqueue_active(&pipe->wait)) |
733 | wake_up_interruptible(&pipe->wait); |
734 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
735 | } |
736 | |
737 | /** |
738 | * splice_from_pipe_feed - feed available data from a pipe to a file |
739 | * @pipe: pipe to splice from |
740 | * @sd: information to @actor |
741 | * @actor: handler that splices the data |
742 | * |
743 | * Description: |
744 | * This function loops over the pipe and calls @actor to do the |
745 | * actual moving of a single struct pipe_buffer to the desired |
746 | * destination. It returns when there's no more buffers left in |
747 | * the pipe or if the requested number of bytes (@sd->total_len) |
748 | * have been copied. It returns a positive number (one) if the |
749 | * pipe needs to be filled with more data, zero if the required |
750 | * number of bytes have been copied and -errno on error. |
751 | * |
752 | * This, together with splice_from_pipe_{begin,end,next}, may be |
753 | * used to implement the functionality of __splice_from_pipe() when |
754 | * locking is required around copying the pipe buffers to the |
755 | * destination. |
756 | */ |
757 | int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
758 | splice_actor *actor) |
759 | { |
760 | int ret; |
761 | |
762 | while (pipe->nrbufs) { |
763 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
764 | const struct pipe_buf_operations *ops = buf->ops; |
765 | |
766 | sd->len = buf->len; |
767 | if (sd->len > sd->total_len) |
768 | sd->len = sd->total_len; |
769 | |
770 | ret = actor(pipe, buf, sd); |
771 | if (ret <= 0) { |
772 | if (ret == -ENODATA) |
773 | ret = 0; |
774 | return ret; |
775 | } |
776 | buf->offset += ret; |
777 | buf->len -= ret; |
778 | |
779 | sd->num_spliced += ret; |
780 | sd->len -= ret; |
781 | sd->pos += ret; |
782 | sd->total_len -= ret; |
783 | |
784 | if (!buf->len) { |
785 | buf->ops = NULL; |
786 | ops->release(pipe, buf); |
787 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
788 | pipe->nrbufs--; |
789 | if (pipe->inode) |
790 | sd->need_wakeup = true; |
791 | } |
792 | |
793 | if (!sd->total_len) |
794 | return 0; |
795 | } |
796 | |
797 | return 1; |
798 | } |
799 | EXPORT_SYMBOL(splice_from_pipe_feed); |
800 | |
801 | /** |
802 | * splice_from_pipe_next - wait for some data to splice from |
803 | * @pipe: pipe to splice from |
804 | * @sd: information about the splice operation |
805 | * |
806 | * Description: |
807 | * This function will wait for some data and return a positive |
808 | * value (one) if pipe buffers are available. It will return zero |
809 | * or -errno if no more data needs to be spliced. |
810 | */ |
811 | int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
812 | { |
813 | while (!pipe->nrbufs) { |
814 | if (!pipe->writers) |
815 | return 0; |
816 | |
817 | if (!pipe->waiting_writers && sd->num_spliced) |
818 | return 0; |
819 | |
820 | if (sd->flags & SPLICE_F_NONBLOCK) |
821 | return -EAGAIN; |
822 | |
823 | if (signal_pending(current)) |
824 | return -ERESTARTSYS; |
825 | |
826 | if (sd->need_wakeup) { |
827 | wakeup_pipe_writers(pipe); |
828 | sd->need_wakeup = false; |
829 | } |
830 | |
831 | pipe_wait(pipe); |
832 | } |
833 | |
834 | return 1; |
835 | } |
836 | EXPORT_SYMBOL(splice_from_pipe_next); |
837 | |
838 | /** |
839 | * splice_from_pipe_begin - start splicing from pipe |
840 | * @sd: information about the splice operation |
841 | * |
842 | * Description: |
843 | * This function should be called before a loop containing |
844 | * splice_from_pipe_next() and splice_from_pipe_feed() to |
845 | * initialize the necessary fields of @sd. |
846 | */ |
847 | void splice_from_pipe_begin(struct splice_desc *sd) |
848 | { |
849 | sd->num_spliced = 0; |
850 | sd->need_wakeup = false; |
851 | } |
852 | EXPORT_SYMBOL(splice_from_pipe_begin); |
853 | |
854 | /** |
855 | * splice_from_pipe_end - finish splicing from pipe |
856 | * @pipe: pipe to splice from |
857 | * @sd: information about the splice operation |
858 | * |
859 | * Description: |
860 | * This function will wake up pipe writers if necessary. It should |
861 | * be called after a loop containing splice_from_pipe_next() and |
862 | * splice_from_pipe_feed(). |
863 | */ |
864 | void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
865 | { |
866 | if (sd->need_wakeup) |
867 | wakeup_pipe_writers(pipe); |
868 | } |
869 | EXPORT_SYMBOL(splice_from_pipe_end); |
870 | |
871 | /** |
872 | * __splice_from_pipe - splice data from a pipe to given actor |
873 | * @pipe: pipe to splice from |
874 | * @sd: information to @actor |
875 | * @actor: handler that splices the data |
876 | * |
877 | * Description: |
878 | * This function does little more than loop over the pipe and call |
879 | * @actor to do the actual moving of a single struct pipe_buffer to |
880 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or |
881 | * pipe_to_user. |
882 | * |
883 | */ |
884 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
885 | splice_actor *actor) |
886 | { |
887 | int ret; |
888 | |
889 | splice_from_pipe_begin(sd); |
890 | do { |
891 | ret = splice_from_pipe_next(pipe, sd); |
892 | if (ret > 0) |
893 | ret = splice_from_pipe_feed(pipe, sd, actor); |
894 | } while (ret > 0); |
895 | splice_from_pipe_end(pipe, sd); |
896 | |
897 | return sd->num_spliced ? sd->num_spliced : ret; |
898 | } |
899 | EXPORT_SYMBOL(__splice_from_pipe); |
900 | |
901 | /** |
902 | * splice_from_pipe - splice data from a pipe to a file |
903 | * @pipe: pipe to splice from |
904 | * @out: file to splice to |
905 | * @ppos: position in @out |
906 | * @len: how many bytes to splice |
907 | * @flags: splice modifier flags |
908 | * @actor: handler that splices the data |
909 | * |
910 | * Description: |
911 | * See __splice_from_pipe. This function locks the pipe inode, |
912 | * otherwise it's identical to __splice_from_pipe(). |
913 | * |
914 | */ |
915 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
916 | loff_t *ppos, size_t len, unsigned int flags, |
917 | splice_actor *actor) |
918 | { |
919 | ssize_t ret; |
920 | struct splice_desc sd = { |
921 | .total_len = len, |
922 | .flags = flags, |
923 | .pos = *ppos, |
924 | .u.file = out, |
925 | }; |
926 | |
927 | pipe_lock(pipe); |
928 | ret = __splice_from_pipe(pipe, &sd, actor); |
929 | pipe_unlock(pipe); |
930 | |
931 | return ret; |
932 | } |
933 | |
934 | /** |
935 | * generic_file_splice_write - splice data from a pipe to a file |
936 | * @pipe: pipe info |
937 | * @out: file to write to |
938 | * @ppos: position in @out |
939 | * @len: number of bytes to splice |
940 | * @flags: splice modifier flags |
941 | * |
942 | * Description: |
943 | * Will either move or copy pages (determined by @flags options) from |
944 | * the given pipe inode to the given file. |
945 | * |
946 | */ |
947 | ssize_t |
948 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, |
949 | loff_t *ppos, size_t len, unsigned int flags) |
950 | { |
951 | struct address_space *mapping = out->f_mapping; |
952 | struct inode *inode = mapping->host; |
953 | struct splice_desc sd = { |
954 | .total_len = len, |
955 | .flags = flags, |
956 | .pos = *ppos, |
957 | .u.file = out, |
958 | }; |
959 | ssize_t ret; |
960 | |
961 | pipe_lock(pipe); |
962 | |
963 | splice_from_pipe_begin(&sd); |
964 | do { |
965 | ret = splice_from_pipe_next(pipe, &sd); |
966 | if (ret <= 0) |
967 | break; |
968 | |
969 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
970 | ret = file_remove_suid(out); |
971 | if (!ret) { |
972 | file_update_time(out); |
973 | ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file); |
974 | } |
975 | mutex_unlock(&inode->i_mutex); |
976 | } while (ret > 0); |
977 | splice_from_pipe_end(pipe, &sd); |
978 | |
979 | pipe_unlock(pipe); |
980 | |
981 | if (sd.num_spliced) |
982 | ret = sd.num_spliced; |
983 | |
984 | if (ret > 0) { |
985 | unsigned long nr_pages; |
986 | int err; |
987 | |
988 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
989 | |
990 | err = generic_write_sync(out, *ppos, ret); |
991 | if (err) |
992 | ret = err; |
993 | else |
994 | *ppos += ret; |
995 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
996 | } |
997 | |
998 | return ret; |
999 | } |
1000 | |
1001 | EXPORT_SYMBOL(generic_file_splice_write); |
1002 | |
1003 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1004 | struct splice_desc *sd) |
1005 | { |
1006 | int ret; |
1007 | void *data; |
1008 | |
1009 | ret = buf->ops->confirm(pipe, buf); |
1010 | if (ret) |
1011 | return ret; |
1012 | |
1013 | data = buf->ops->map(pipe, buf, 0); |
1014 | ret = kernel_write(sd->u.file, data + buf->offset, sd->len, sd->pos); |
1015 | buf->ops->unmap(pipe, buf, data); |
1016 | |
1017 | return ret; |
1018 | } |
1019 | |
1020 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, |
1021 | struct file *out, loff_t *ppos, |
1022 | size_t len, unsigned int flags) |
1023 | { |
1024 | ssize_t ret; |
1025 | |
1026 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
1027 | if (ret > 0) |
1028 | *ppos += ret; |
1029 | |
1030 | return ret; |
1031 | } |
1032 | |
1033 | /** |
1034 | * generic_splice_sendpage - splice data from a pipe to a socket |
1035 | * @pipe: pipe to splice from |
1036 | * @out: socket to write to |
1037 | * @ppos: position in @out |
1038 | * @len: number of bytes to splice |
1039 | * @flags: splice modifier flags |
1040 | * |
1041 | * Description: |
1042 | * Will send @len bytes from the pipe to a network socket. No data copying |
1043 | * is involved. |
1044 | * |
1045 | */ |
1046 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
1047 | loff_t *ppos, size_t len, unsigned int flags) |
1048 | { |
1049 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
1050 | } |
1051 | |
1052 | EXPORT_SYMBOL(generic_splice_sendpage); |
1053 | |
1054 | /* |
1055 | * Attempt to initiate a splice from pipe to file. |
1056 | */ |
1057 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
1058 | loff_t *ppos, size_t len, unsigned int flags) |
1059 | { |
1060 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
1061 | loff_t *, size_t, unsigned int); |
1062 | int ret; |
1063 | |
1064 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1065 | return -EBADF; |
1066 | |
1067 | if (unlikely(out->f_flags & O_APPEND)) |
1068 | return -EINVAL; |
1069 | |
1070 | ret = rw_verify_area(WRITE, out, ppos, len); |
1071 | if (unlikely(ret < 0)) |
1072 | return ret; |
1073 | |
1074 | if (out->f_op && out->f_op->splice_write) |
1075 | splice_write = out->f_op->splice_write; |
1076 | else |
1077 | splice_write = default_file_splice_write; |
1078 | |
1079 | return splice_write(pipe, out, ppos, len, flags); |
1080 | } |
1081 | |
1082 | /* |
1083 | * Attempt to initiate a splice from a file to a pipe. |
1084 | */ |
1085 | static long do_splice_to(struct file *in, loff_t *ppos, |
1086 | struct pipe_inode_info *pipe, size_t len, |
1087 | unsigned int flags) |
1088 | { |
1089 | ssize_t (*splice_read)(struct file *, loff_t *, |
1090 | struct pipe_inode_info *, size_t, unsigned int); |
1091 | int ret; |
1092 | |
1093 | if (unlikely(!(in->f_mode & FMODE_READ))) |
1094 | return -EBADF; |
1095 | |
1096 | ret = rw_verify_area(READ, in, ppos, len); |
1097 | if (unlikely(ret < 0)) |
1098 | return ret; |
1099 | |
1100 | if (in->f_op && in->f_op->splice_read) |
1101 | splice_read = in->f_op->splice_read; |
1102 | else |
1103 | splice_read = default_file_splice_read; |
1104 | |
1105 | return splice_read(in, ppos, pipe, len, flags); |
1106 | } |
1107 | |
1108 | /** |
1109 | * splice_direct_to_actor - splices data directly between two non-pipes |
1110 | * @in: file to splice from |
1111 | * @sd: actor information on where to splice to |
1112 | * @actor: handles the data splicing |
1113 | * |
1114 | * Description: |
1115 | * This is a special case helper to splice directly between two |
1116 | * points, without requiring an explicit pipe. Internally an allocated |
1117 | * pipe is cached in the process, and reused during the lifetime of |
1118 | * that process. |
1119 | * |
1120 | */ |
1121 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, |
1122 | splice_direct_actor *actor) |
1123 | { |
1124 | struct pipe_inode_info *pipe; |
1125 | long ret, bytes; |
1126 | umode_t i_mode; |
1127 | size_t len; |
1128 | int i, flags; |
1129 | |
1130 | /* |
1131 | * We require the input being a regular file, as we don't want to |
1132 | * randomly drop data for eg socket -> socket splicing. Use the |
1133 | * piped splicing for that! |
1134 | */ |
1135 | i_mode = in->f_path.dentry->d_inode->i_mode; |
1136 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
1137 | return -EINVAL; |
1138 | |
1139 | /* |
1140 | * neither in nor out is a pipe, setup an internal pipe attached to |
1141 | * 'out' and transfer the wanted data from 'in' to 'out' through that |
1142 | */ |
1143 | pipe = current->splice_pipe; |
1144 | if (unlikely(!pipe)) { |
1145 | pipe = alloc_pipe_info(NULL); |
1146 | if (!pipe) |
1147 | return -ENOMEM; |
1148 | |
1149 | /* |
1150 | * We don't have an immediate reader, but we'll read the stuff |
1151 | * out of the pipe right after the splice_to_pipe(). So set |
1152 | * PIPE_READERS appropriately. |
1153 | */ |
1154 | pipe->readers = 1; |
1155 | |
1156 | current->splice_pipe = pipe; |
1157 | } |
1158 | |
1159 | /* |
1160 | * Do the splice. |
1161 | */ |
1162 | ret = 0; |
1163 | bytes = 0; |
1164 | len = sd->total_len; |
1165 | flags = sd->flags; |
1166 | |
1167 | /* |
1168 | * Don't block on output, we have to drain the direct pipe. |
1169 | */ |
1170 | sd->flags &= ~SPLICE_F_NONBLOCK; |
1171 | |
1172 | while (len) { |
1173 | size_t read_len; |
1174 | loff_t pos = sd->pos, prev_pos = pos; |
1175 | |
1176 | ret = do_splice_to(in, &pos, pipe, len, flags); |
1177 | if (unlikely(ret <= 0)) |
1178 | goto out_release; |
1179 | |
1180 | read_len = ret; |
1181 | sd->total_len = read_len; |
1182 | |
1183 | /* |
1184 | * NOTE: nonblocking mode only applies to the input. We |
1185 | * must not do the output in nonblocking mode as then we |
1186 | * could get stuck data in the internal pipe: |
1187 | */ |
1188 | ret = actor(pipe, sd); |
1189 | if (unlikely(ret <= 0)) { |
1190 | sd->pos = prev_pos; |
1191 | goto out_release; |
1192 | } |
1193 | |
1194 | bytes += ret; |
1195 | len -= ret; |
1196 | sd->pos = pos; |
1197 | |
1198 | if (ret < read_len) { |
1199 | sd->pos = prev_pos + ret; |
1200 | goto out_release; |
1201 | } |
1202 | } |
1203 | |
1204 | done: |
1205 | pipe->nrbufs = pipe->curbuf = 0; |
1206 | file_accessed(in); |
1207 | return bytes; |
1208 | |
1209 | out_release: |
1210 | /* |
1211 | * If we did an incomplete transfer we must release |
1212 | * the pipe buffers in question: |
1213 | */ |
1214 | for (i = 0; i < PIPE_BUFFERS; i++) { |
1215 | struct pipe_buffer *buf = pipe->bufs + i; |
1216 | |
1217 | if (buf->ops) { |
1218 | buf->ops->release(pipe, buf); |
1219 | buf->ops = NULL; |
1220 | } |
1221 | } |
1222 | |
1223 | if (!bytes) |
1224 | bytes = ret; |
1225 | |
1226 | goto done; |
1227 | } |
1228 | EXPORT_SYMBOL(splice_direct_to_actor); |
1229 | |
1230 | static int direct_splice_actor(struct pipe_inode_info *pipe, |
1231 | struct splice_desc *sd) |
1232 | { |
1233 | struct file *file = sd->u.file; |
1234 | |
1235 | return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags); |
1236 | } |
1237 | |
1238 | /** |
1239 | * do_splice_direct - splices data directly between two files |
1240 | * @in: file to splice from |
1241 | * @ppos: input file offset |
1242 | * @out: file to splice to |
1243 | * @len: number of bytes to splice |
1244 | * @flags: splice modifier flags |
1245 | * |
1246 | * Description: |
1247 | * For use by do_sendfile(). splice can easily emulate sendfile, but |
1248 | * doing it in the application would incur an extra system call |
1249 | * (splice in + splice out, as compared to just sendfile()). So this helper |
1250 | * can splice directly through a process-private pipe. |
1251 | * |
1252 | */ |
1253 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1254 | size_t len, unsigned int flags) |
1255 | { |
1256 | struct splice_desc sd = { |
1257 | .len = len, |
1258 | .total_len = len, |
1259 | .flags = flags, |
1260 | .pos = *ppos, |
1261 | .u.file = out, |
1262 | }; |
1263 | long ret; |
1264 | |
1265 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
1266 | if (ret > 0) |
1267 | *ppos = sd.pos; |
1268 | |
1269 | return ret; |
1270 | } |
1271 | |
1272 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1273 | struct pipe_inode_info *opipe, |
1274 | size_t len, unsigned int flags); |
1275 | /* |
1276 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same |
1277 | * location, so checking ->i_pipe is not enough to verify that this is a |
1278 | * pipe. |
1279 | */ |
1280 | static inline struct pipe_inode_info *pipe_info(struct inode *inode) |
1281 | { |
1282 | if (S_ISFIFO(inode->i_mode)) |
1283 | return inode->i_pipe; |
1284 | |
1285 | return NULL; |
1286 | } |
1287 | |
1288 | /* |
1289 | * Determine where to splice to/from. |
1290 | */ |
1291 | static long do_splice(struct file *in, loff_t __user *off_in, |
1292 | struct file *out, loff_t __user *off_out, |
1293 | size_t len, unsigned int flags) |
1294 | { |
1295 | struct pipe_inode_info *ipipe; |
1296 | struct pipe_inode_info *opipe; |
1297 | loff_t offset, *off; |
1298 | long ret; |
1299 | |
1300 | ipipe = pipe_info(in->f_path.dentry->d_inode); |
1301 | opipe = pipe_info(out->f_path.dentry->d_inode); |
1302 | |
1303 | if (ipipe && opipe) { |
1304 | if (off_in || off_out) |
1305 | return -ESPIPE; |
1306 | |
1307 | if (!(in->f_mode & FMODE_READ)) |
1308 | return -EBADF; |
1309 | |
1310 | if (!(out->f_mode & FMODE_WRITE)) |
1311 | return -EBADF; |
1312 | |
1313 | /* Splicing to self would be fun, but... */ |
1314 | if (ipipe == opipe) |
1315 | return -EINVAL; |
1316 | |
1317 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1318 | } |
1319 | |
1320 | if (ipipe) { |
1321 | if (off_in) |
1322 | return -ESPIPE; |
1323 | if (off_out) { |
1324 | if (!out->f_op || !out->f_op->llseek || |
1325 | out->f_op->llseek == no_llseek) |
1326 | return -EINVAL; |
1327 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
1328 | return -EFAULT; |
1329 | off = &offset; |
1330 | } else |
1331 | off = &out->f_pos; |
1332 | |
1333 | ret = do_splice_from(ipipe, out, off, len, flags); |
1334 | |
1335 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) |
1336 | ret = -EFAULT; |
1337 | |
1338 | return ret; |
1339 | } |
1340 | |
1341 | if (opipe) { |
1342 | if (off_out) |
1343 | return -ESPIPE; |
1344 | if (off_in) { |
1345 | if (!in->f_op || !in->f_op->llseek || |
1346 | in->f_op->llseek == no_llseek) |
1347 | return -EINVAL; |
1348 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
1349 | return -EFAULT; |
1350 | off = &offset; |
1351 | } else |
1352 | off = &in->f_pos; |
1353 | |
1354 | ret = do_splice_to(in, off, opipe, len, flags); |
1355 | |
1356 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) |
1357 | ret = -EFAULT; |
1358 | |
1359 | return ret; |
1360 | } |
1361 | |
1362 | return -EINVAL; |
1363 | } |
1364 | |
1365 | /* |
1366 | * Map an iov into an array of pages and offset/length tupples. With the |
1367 | * partial_page structure, we can map several non-contiguous ranges into |
1368 | * our ones pages[] map instead of splitting that operation into pieces. |
1369 | * Could easily be exported as a generic helper for other users, in which |
1370 | * case one would probably want to add a 'max_nr_pages' parameter as well. |
1371 | */ |
1372 | static int get_iovec_page_array(const struct iovec __user *iov, |
1373 | unsigned int nr_vecs, struct page **pages, |
1374 | struct partial_page *partial, int aligned) |
1375 | { |
1376 | int buffers = 0, error = 0; |
1377 | |
1378 | while (nr_vecs) { |
1379 | unsigned long off, npages; |
1380 | struct iovec entry; |
1381 | void __user *base; |
1382 | size_t len; |
1383 | int i; |
1384 | |
1385 | error = -EFAULT; |
1386 | if (copy_from_user(&entry, iov, sizeof(entry))) |
1387 | break; |
1388 | |
1389 | base = entry.iov_base; |
1390 | len = entry.iov_len; |
1391 | |
1392 | /* |
1393 | * Sanity check this iovec. 0 read succeeds. |
1394 | */ |
1395 | error = 0; |
1396 | if (unlikely(!len)) |
1397 | break; |
1398 | error = -EFAULT; |
1399 | if (!access_ok(VERIFY_READ, base, len)) |
1400 | break; |
1401 | |
1402 | /* |
1403 | * Get this base offset and number of pages, then map |
1404 | * in the user pages. |
1405 | */ |
1406 | off = (unsigned long) base & ~PAGE_MASK; |
1407 | |
1408 | /* |
1409 | * If asked for alignment, the offset must be zero and the |
1410 | * length a multiple of the PAGE_SIZE. |
1411 | */ |
1412 | error = -EINVAL; |
1413 | if (aligned && (off || len & ~PAGE_MASK)) |
1414 | break; |
1415 | |
1416 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1417 | if (npages > PIPE_BUFFERS - buffers) |
1418 | npages = PIPE_BUFFERS - buffers; |
1419 | |
1420 | error = get_user_pages_fast((unsigned long)base, npages, |
1421 | 0, &pages[buffers]); |
1422 | |
1423 | if (unlikely(error <= 0)) |
1424 | break; |
1425 | |
1426 | /* |
1427 | * Fill this contiguous range into the partial page map. |
1428 | */ |
1429 | for (i = 0; i < error; i++) { |
1430 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
1431 | |
1432 | partial[buffers].offset = off; |
1433 | partial[buffers].len = plen; |
1434 | |
1435 | off = 0; |
1436 | len -= plen; |
1437 | buffers++; |
1438 | } |
1439 | |
1440 | /* |
1441 | * We didn't complete this iov, stop here since it probably |
1442 | * means we have to move some of this into a pipe to |
1443 | * be able to continue. |
1444 | */ |
1445 | if (len) |
1446 | break; |
1447 | |
1448 | /* |
1449 | * Don't continue if we mapped fewer pages than we asked for, |
1450 | * or if we mapped the max number of pages that we have |
1451 | * room for. |
1452 | */ |
1453 | if (error < npages || buffers == PIPE_BUFFERS) |
1454 | break; |
1455 | |
1456 | nr_vecs--; |
1457 | iov++; |
1458 | } |
1459 | |
1460 | if (buffers) |
1461 | return buffers; |
1462 | |
1463 | return error; |
1464 | } |
1465 | |
1466 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1467 | struct splice_desc *sd) |
1468 | { |
1469 | char *src; |
1470 | int ret; |
1471 | |
1472 | ret = buf->ops->confirm(pipe, buf); |
1473 | if (unlikely(ret)) |
1474 | return ret; |
1475 | |
1476 | /* |
1477 | * See if we can use the atomic maps, by prefaulting in the |
1478 | * pages and doing an atomic copy |
1479 | */ |
1480 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { |
1481 | src = buf->ops->map(pipe, buf, 1); |
1482 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, |
1483 | sd->len); |
1484 | buf->ops->unmap(pipe, buf, src); |
1485 | if (!ret) { |
1486 | ret = sd->len; |
1487 | goto out; |
1488 | } |
1489 | } |
1490 | |
1491 | /* |
1492 | * No dice, use slow non-atomic map and copy |
1493 | */ |
1494 | src = buf->ops->map(pipe, buf, 0); |
1495 | |
1496 | ret = sd->len; |
1497 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) |
1498 | ret = -EFAULT; |
1499 | |
1500 | buf->ops->unmap(pipe, buf, src); |
1501 | out: |
1502 | if (ret > 0) |
1503 | sd->u.userptr += ret; |
1504 | return ret; |
1505 | } |
1506 | |
1507 | /* |
1508 | * For lack of a better implementation, implement vmsplice() to userspace |
1509 | * as a simple copy of the pipes pages to the user iov. |
1510 | */ |
1511 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, |
1512 | unsigned long nr_segs, unsigned int flags) |
1513 | { |
1514 | struct pipe_inode_info *pipe; |
1515 | struct splice_desc sd; |
1516 | ssize_t size; |
1517 | int error; |
1518 | long ret; |
1519 | |
1520 | pipe = pipe_info(file->f_path.dentry->d_inode); |
1521 | if (!pipe) |
1522 | return -EBADF; |
1523 | |
1524 | pipe_lock(pipe); |
1525 | |
1526 | error = ret = 0; |
1527 | while (nr_segs) { |
1528 | void __user *base; |
1529 | size_t len; |
1530 | |
1531 | /* |
1532 | * Get user address base and length for this iovec. |
1533 | */ |
1534 | error = get_user(base, &iov->iov_base); |
1535 | if (unlikely(error)) |
1536 | break; |
1537 | error = get_user(len, &iov->iov_len); |
1538 | if (unlikely(error)) |
1539 | break; |
1540 | |
1541 | /* |
1542 | * Sanity check this iovec. 0 read succeeds. |
1543 | */ |
1544 | if (unlikely(!len)) |
1545 | break; |
1546 | if (unlikely(!base)) { |
1547 | error = -EFAULT; |
1548 | break; |
1549 | } |
1550 | |
1551 | if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { |
1552 | error = -EFAULT; |
1553 | break; |
1554 | } |
1555 | |
1556 | sd.len = 0; |
1557 | sd.total_len = len; |
1558 | sd.flags = flags; |
1559 | sd.u.userptr = base; |
1560 | sd.pos = 0; |
1561 | |
1562 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); |
1563 | if (size < 0) { |
1564 | if (!ret) |
1565 | ret = size; |
1566 | |
1567 | break; |
1568 | } |
1569 | |
1570 | ret += size; |
1571 | |
1572 | if (size < len) |
1573 | break; |
1574 | |
1575 | nr_segs--; |
1576 | iov++; |
1577 | } |
1578 | |
1579 | pipe_unlock(pipe); |
1580 | |
1581 | if (!ret) |
1582 | ret = error; |
1583 | |
1584 | return ret; |
1585 | } |
1586 | |
1587 | /* |
1588 | * vmsplice splices a user address range into a pipe. It can be thought of |
1589 | * as splice-from-memory, where the regular splice is splice-from-file (or |
1590 | * to file). In both cases the output is a pipe, naturally. |
1591 | */ |
1592 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1593 | unsigned long nr_segs, unsigned int flags) |
1594 | { |
1595 | struct pipe_inode_info *pipe; |
1596 | struct page *pages[PIPE_BUFFERS]; |
1597 | struct partial_page partial[PIPE_BUFFERS]; |
1598 | struct splice_pipe_desc spd = { |
1599 | .pages = pages, |
1600 | .partial = partial, |
1601 | .flags = flags, |
1602 | .ops = &user_page_pipe_buf_ops, |
1603 | .spd_release = spd_release_page, |
1604 | }; |
1605 | |
1606 | pipe = pipe_info(file->f_path.dentry->d_inode); |
1607 | if (!pipe) |
1608 | return -EBADF; |
1609 | |
1610 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial, |
1611 | flags & SPLICE_F_GIFT); |
1612 | if (spd.nr_pages <= 0) |
1613 | return spd.nr_pages; |
1614 | |
1615 | return splice_to_pipe(pipe, &spd); |
1616 | } |
1617 | |
1618 | /* |
1619 | * Note that vmsplice only really supports true splicing _from_ user memory |
1620 | * to a pipe, not the other way around. Splicing from user memory is a simple |
1621 | * operation that can be supported without any funky alignment restrictions |
1622 | * or nasty vm tricks. We simply map in the user memory and fill them into |
1623 | * a pipe. The reverse isn't quite as easy, though. There are two possible |
1624 | * solutions for that: |
1625 | * |
1626 | * - memcpy() the data internally, at which point we might as well just |
1627 | * do a regular read() on the buffer anyway. |
1628 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it |
1629 | * has restriction limitations on both ends of the pipe). |
1630 | * |
1631 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). |
1632 | * |
1633 | */ |
1634 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1635 | unsigned long, nr_segs, unsigned int, flags) |
1636 | { |
1637 | struct file *file; |
1638 | long error; |
1639 | int fput; |
1640 | |
1641 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1642 | return -EINVAL; |
1643 | else if (unlikely(!nr_segs)) |
1644 | return 0; |
1645 | |
1646 | error = -EBADF; |
1647 | file = fget_light(fd, &fput); |
1648 | if (file) { |
1649 | if (file->f_mode & FMODE_WRITE) |
1650 | error = vmsplice_to_pipe(file, iov, nr_segs, flags); |
1651 | else if (file->f_mode & FMODE_READ) |
1652 | error = vmsplice_to_user(file, iov, nr_segs, flags); |
1653 | |
1654 | fput_light(file, fput); |
1655 | } |
1656 | |
1657 | return error; |
1658 | } |
1659 | |
1660 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1661 | int, fd_out, loff_t __user *, off_out, |
1662 | size_t, len, unsigned int, flags) |
1663 | { |
1664 | long error; |
1665 | struct file *in, *out; |
1666 | int fput_in, fput_out; |
1667 | |
1668 | if (unlikely(!len)) |
1669 | return 0; |
1670 | |
1671 | error = -EBADF; |
1672 | in = fget_light(fd_in, &fput_in); |
1673 | if (in) { |
1674 | if (in->f_mode & FMODE_READ) { |
1675 | out = fget_light(fd_out, &fput_out); |
1676 | if (out) { |
1677 | if (out->f_mode & FMODE_WRITE) |
1678 | error = do_splice(in, off_in, |
1679 | out, off_out, |
1680 | len, flags); |
1681 | fput_light(out, fput_out); |
1682 | } |
1683 | } |
1684 | |
1685 | fput_light(in, fput_in); |
1686 | } |
1687 | |
1688 | return error; |
1689 | } |
1690 | |
1691 | /* |
1692 | * Make sure there's data to read. Wait for input if we can, otherwise |
1693 | * return an appropriate error. |
1694 | */ |
1695 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1696 | { |
1697 | int ret; |
1698 | |
1699 | /* |
1700 | * Check ->nrbufs without the inode lock first. This function |
1701 | * is speculative anyways, so missing one is ok. |
1702 | */ |
1703 | if (pipe->nrbufs) |
1704 | return 0; |
1705 | |
1706 | ret = 0; |
1707 | pipe_lock(pipe); |
1708 | |
1709 | while (!pipe->nrbufs) { |
1710 | if (signal_pending(current)) { |
1711 | ret = -ERESTARTSYS; |
1712 | break; |
1713 | } |
1714 | if (!pipe->writers) |
1715 | break; |
1716 | if (!pipe->waiting_writers) { |
1717 | if (flags & SPLICE_F_NONBLOCK) { |
1718 | ret = -EAGAIN; |
1719 | break; |
1720 | } |
1721 | } |
1722 | pipe_wait(pipe); |
1723 | } |
1724 | |
1725 | pipe_unlock(pipe); |
1726 | return ret; |
1727 | } |
1728 | |
1729 | /* |
1730 | * Make sure there's writeable room. Wait for room if we can, otherwise |
1731 | * return an appropriate error. |
1732 | */ |
1733 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1734 | { |
1735 | int ret; |
1736 | |
1737 | /* |
1738 | * Check ->nrbufs without the inode lock first. This function |
1739 | * is speculative anyways, so missing one is ok. |
1740 | */ |
1741 | if (pipe->nrbufs < PIPE_BUFFERS) |
1742 | return 0; |
1743 | |
1744 | ret = 0; |
1745 | pipe_lock(pipe); |
1746 | |
1747 | while (pipe->nrbufs >= PIPE_BUFFERS) { |
1748 | if (!pipe->readers) { |
1749 | send_sig(SIGPIPE, current, 0); |
1750 | ret = -EPIPE; |
1751 | break; |
1752 | } |
1753 | if (flags & SPLICE_F_NONBLOCK) { |
1754 | ret = -EAGAIN; |
1755 | break; |
1756 | } |
1757 | if (signal_pending(current)) { |
1758 | ret = -ERESTARTSYS; |
1759 | break; |
1760 | } |
1761 | pipe->waiting_writers++; |
1762 | pipe_wait(pipe); |
1763 | pipe->waiting_writers--; |
1764 | } |
1765 | |
1766 | pipe_unlock(pipe); |
1767 | return ret; |
1768 | } |
1769 | |
1770 | /* |
1771 | * Splice contents of ipipe to opipe. |
1772 | */ |
1773 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1774 | struct pipe_inode_info *opipe, |
1775 | size_t len, unsigned int flags) |
1776 | { |
1777 | struct pipe_buffer *ibuf, *obuf; |
1778 | int ret = 0, nbuf; |
1779 | bool input_wakeup = false; |
1780 | |
1781 | |
1782 | retry: |
1783 | ret = ipipe_prep(ipipe, flags); |
1784 | if (ret) |
1785 | return ret; |
1786 | |
1787 | ret = opipe_prep(opipe, flags); |
1788 | if (ret) |
1789 | return ret; |
1790 | |
1791 | /* |
1792 | * Potential ABBA deadlock, work around it by ordering lock |
1793 | * grabbing by pipe info address. Otherwise two different processes |
1794 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1795 | */ |
1796 | pipe_double_lock(ipipe, opipe); |
1797 | |
1798 | do { |
1799 | if (!opipe->readers) { |
1800 | send_sig(SIGPIPE, current, 0); |
1801 | if (!ret) |
1802 | ret = -EPIPE; |
1803 | break; |
1804 | } |
1805 | |
1806 | if (!ipipe->nrbufs && !ipipe->writers) |
1807 | break; |
1808 | |
1809 | /* |
1810 | * Cannot make any progress, because either the input |
1811 | * pipe is empty or the output pipe is full. |
1812 | */ |
1813 | if (!ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) { |
1814 | /* Already processed some buffers, break */ |
1815 | if (ret) |
1816 | break; |
1817 | |
1818 | if (flags & SPLICE_F_NONBLOCK) { |
1819 | ret = -EAGAIN; |
1820 | break; |
1821 | } |
1822 | |
1823 | /* |
1824 | * We raced with another reader/writer and haven't |
1825 | * managed to process any buffers. A zero return |
1826 | * value means EOF, so retry instead. |
1827 | */ |
1828 | pipe_unlock(ipipe); |
1829 | pipe_unlock(opipe); |
1830 | goto retry; |
1831 | } |
1832 | |
1833 | ibuf = ipipe->bufs + ipipe->curbuf; |
1834 | nbuf = (opipe->curbuf + opipe->nrbufs) % PIPE_BUFFERS; |
1835 | obuf = opipe->bufs + nbuf; |
1836 | |
1837 | if (len >= ibuf->len) { |
1838 | /* |
1839 | * Simply move the whole buffer from ipipe to opipe |
1840 | */ |
1841 | *obuf = *ibuf; |
1842 | ibuf->ops = NULL; |
1843 | opipe->nrbufs++; |
1844 | ipipe->curbuf = (ipipe->curbuf + 1) % PIPE_BUFFERS; |
1845 | ipipe->nrbufs--; |
1846 | input_wakeup = true; |
1847 | } else { |
1848 | /* |
1849 | * Get a reference to this pipe buffer, |
1850 | * so we can copy the contents over. |
1851 | */ |
1852 | ibuf->ops->get(ipipe, ibuf); |
1853 | *obuf = *ibuf; |
1854 | |
1855 | /* |
1856 | * Don't inherit the gift flag, we need to |
1857 | * prevent multiple steals of this page. |
1858 | */ |
1859 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1860 | |
1861 | obuf->len = len; |
1862 | opipe->nrbufs++; |
1863 | ibuf->offset += obuf->len; |
1864 | ibuf->len -= obuf->len; |
1865 | } |
1866 | ret += obuf->len; |
1867 | len -= obuf->len; |
1868 | } while (len); |
1869 | |
1870 | pipe_unlock(ipipe); |
1871 | pipe_unlock(opipe); |
1872 | |
1873 | /* |
1874 | * If we put data in the output pipe, wakeup any potential readers. |
1875 | */ |
1876 | if (ret > 0) { |
1877 | smp_mb(); |
1878 | if (waitqueue_active(&opipe->wait)) |
1879 | wake_up_interruptible(&opipe->wait); |
1880 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); |
1881 | } |
1882 | if (input_wakeup) |
1883 | wakeup_pipe_writers(ipipe); |
1884 | |
1885 | return ret; |
1886 | } |
1887 | |
1888 | /* |
1889 | * Link contents of ipipe to opipe. |
1890 | */ |
1891 | static int link_pipe(struct pipe_inode_info *ipipe, |
1892 | struct pipe_inode_info *opipe, |
1893 | size_t len, unsigned int flags) |
1894 | { |
1895 | struct pipe_buffer *ibuf, *obuf; |
1896 | int ret = 0, i = 0, nbuf; |
1897 | |
1898 | /* |
1899 | * Potential ABBA deadlock, work around it by ordering lock |
1900 | * grabbing by pipe info address. Otherwise two different processes |
1901 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1902 | */ |
1903 | pipe_double_lock(ipipe, opipe); |
1904 | |
1905 | do { |
1906 | if (!opipe->readers) { |
1907 | send_sig(SIGPIPE, current, 0); |
1908 | if (!ret) |
1909 | ret = -EPIPE; |
1910 | break; |
1911 | } |
1912 | |
1913 | /* |
1914 | * If we have iterated all input buffers or ran out of |
1915 | * output room, break. |
1916 | */ |
1917 | if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) |
1918 | break; |
1919 | |
1920 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); |
1921 | nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); |
1922 | |
1923 | /* |
1924 | * Get a reference to this pipe buffer, |
1925 | * so we can copy the contents over. |
1926 | */ |
1927 | ibuf->ops->get(ipipe, ibuf); |
1928 | |
1929 | obuf = opipe->bufs + nbuf; |
1930 | *obuf = *ibuf; |
1931 | |
1932 | /* |
1933 | * Don't inherit the gift flag, we need to |
1934 | * prevent multiple steals of this page. |
1935 | */ |
1936 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1937 | |
1938 | if (obuf->len > len) |
1939 | obuf->len = len; |
1940 | |
1941 | opipe->nrbufs++; |
1942 | ret += obuf->len; |
1943 | len -= obuf->len; |
1944 | i++; |
1945 | } while (len); |
1946 | |
1947 | /* |
1948 | * return EAGAIN if we have the potential of some data in the |
1949 | * future, otherwise just return 0 |
1950 | */ |
1951 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) |
1952 | ret = -EAGAIN; |
1953 | |
1954 | pipe_unlock(ipipe); |
1955 | pipe_unlock(opipe); |
1956 | |
1957 | /* |
1958 | * If we put data in the output pipe, wakeup any potential readers. |
1959 | */ |
1960 | if (ret > 0) { |
1961 | smp_mb(); |
1962 | if (waitqueue_active(&opipe->wait)) |
1963 | wake_up_interruptible(&opipe->wait); |
1964 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); |
1965 | } |
1966 | |
1967 | return ret; |
1968 | } |
1969 | |
1970 | /* |
1971 | * This is a tee(1) implementation that works on pipes. It doesn't copy |
1972 | * any data, it simply references the 'in' pages on the 'out' pipe. |
1973 | * The 'flags' used are the SPLICE_F_* variants, currently the only |
1974 | * applicable one is SPLICE_F_NONBLOCK. |
1975 | */ |
1976 | static long do_tee(struct file *in, struct file *out, size_t len, |
1977 | unsigned int flags) |
1978 | { |
1979 | struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode); |
1980 | struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode); |
1981 | int ret = -EINVAL; |
1982 | |
1983 | /* |
1984 | * Duplicate the contents of ipipe to opipe without actually |
1985 | * copying the data. |
1986 | */ |
1987 | if (ipipe && opipe && ipipe != opipe) { |
1988 | /* |
1989 | * Keep going, unless we encounter an error. The ipipe/opipe |
1990 | * ordering doesn't really matter. |
1991 | */ |
1992 | ret = ipipe_prep(ipipe, flags); |
1993 | if (!ret) { |
1994 | ret = opipe_prep(opipe, flags); |
1995 | if (!ret) |
1996 | ret = link_pipe(ipipe, opipe, len, flags); |
1997 | } |
1998 | } |
1999 | |
2000 | return ret; |
2001 | } |
2002 | |
2003 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
2004 | { |
2005 | struct file *in; |
2006 | int error, fput_in; |
2007 | |
2008 | if (unlikely(!len)) |
2009 | return 0; |
2010 | |
2011 | error = -EBADF; |
2012 | in = fget_light(fdin, &fput_in); |
2013 | if (in) { |
2014 | if (in->f_mode & FMODE_READ) { |
2015 | int fput_out; |
2016 | struct file *out = fget_light(fdout, &fput_out); |
2017 | |
2018 | if (out) { |
2019 | if (out->f_mode & FMODE_WRITE) |
2020 | error = do_tee(in, out, len, flags); |
2021 | fput_light(out, fput_out); |
2022 | } |
2023 | } |
2024 | fput_light(in, fput_in); |
2025 | } |
2026 | |
2027 | return error; |
2028 | } |
2029 |
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v2.6.34-rc5
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