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