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