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/buffer_head.h> |
29 | #include <linux/module.h> |
30 | #include <linux/syscalls.h> |
31 | #include <linux/uio.h> |
32 | #include <linux/security.h> |
33 | #include <linux/gfp.h> |
34 | |
35 | /* |
36 | * Attempt to steal a page from a pipe buffer. This should perhaps go into |
37 | * a vm helper function, it's already simplified quite a bit by the |
38 | * addition of remove_mapping(). If success is returned, the caller may |
39 | * attempt to reuse this page for another destination. |
40 | */ |
41 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
42 | struct pipe_buffer *buf) |
43 | { |
44 | struct page *page = buf->page; |
45 | struct address_space *mapping; |
46 | |
47 | lock_page(page); |
48 | |
49 | mapping = page_mapping(page); |
50 | if (mapping) { |
51 | WARN_ON(!PageUptodate(page)); |
52 | |
53 | /* |
54 | * At least for ext2 with nobh option, we need to wait on |
55 | * writeback completing on this page, since we'll remove it |
56 | * from the pagecache. Otherwise truncate wont wait on the |
57 | * page, allowing the disk blocks to be reused by someone else |
58 | * before we actually wrote our data to them. fs corruption |
59 | * ensues. |
60 | */ |
61 | wait_on_page_writeback(page); |
62 | |
63 | if (page_has_private(page) && |
64 | !try_to_release_page(page, GFP_KERNEL)) |
65 | goto out_unlock; |
66 | |
67 | /* |
68 | * If we succeeded in removing the mapping, set LRU flag |
69 | * and return good. |
70 | */ |
71 | if (remove_mapping(mapping, page)) { |
72 | buf->flags |= PIPE_BUF_FLAG_LRU; |
73 | return 0; |
74 | } |
75 | } |
76 | |
77 | /* |
78 | * Raced with truncate or failed to remove page from current |
79 | * address space, unlock and return failure. |
80 | */ |
81 | out_unlock: |
82 | unlock_page(page); |
83 | return 1; |
84 | } |
85 | |
86 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
87 | struct pipe_buffer *buf) |
88 | { |
89 | page_cache_release(buf->page); |
90 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
91 | } |
92 | |
93 | /* |
94 | * Check whether the contents of buf is OK to access. Since the content |
95 | * is a page cache page, IO may be in flight. |
96 | */ |
97 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
98 | struct pipe_buffer *buf) |
99 | { |
100 | struct page *page = buf->page; |
101 | int err; |
102 | |
103 | if (!PageUptodate(page)) { |
104 | lock_page(page); |
105 | |
106 | /* |
107 | * Page got truncated/unhashed. This will cause a 0-byte |
108 | * splice, if this is the first page. |
109 | */ |
110 | if (!page->mapping) { |
111 | err = -ENODATA; |
112 | goto error; |
113 | } |
114 | |
115 | /* |
116 | * Uh oh, read-error from disk. |
117 | */ |
118 | if (!PageUptodate(page)) { |
119 | err = -EIO; |
120 | goto error; |
121 | } |
122 | |
123 | /* |
124 | * Page is ok afterall, we are done. |
125 | */ |
126 | unlock_page(page); |
127 | } |
128 | |
129 | return 0; |
130 | error: |
131 | unlock_page(page); |
132 | return err; |
133 | } |
134 | |
135 | static const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
136 | .can_merge = 0, |
137 | .map = generic_pipe_buf_map, |
138 | .unmap = generic_pipe_buf_unmap, |
139 | .confirm = page_cache_pipe_buf_confirm, |
140 | .release = page_cache_pipe_buf_release, |
141 | .steal = page_cache_pipe_buf_steal, |
142 | .get = generic_pipe_buf_get, |
143 | }; |
144 | |
145 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
146 | struct pipe_buffer *buf) |
147 | { |
148 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
149 | return 1; |
150 | |
151 | buf->flags |= PIPE_BUF_FLAG_LRU; |
152 | return generic_pipe_buf_steal(pipe, buf); |
153 | } |
154 | |
155 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
156 | .can_merge = 0, |
157 | .map = generic_pipe_buf_map, |
158 | .unmap = generic_pipe_buf_unmap, |
159 | .confirm = generic_pipe_buf_confirm, |
160 | .release = page_cache_pipe_buf_release, |
161 | .steal = user_page_pipe_buf_steal, |
162 | .get = generic_pipe_buf_get, |
163 | }; |
164 | |
165 | /** |
166 | * splice_to_pipe - fill passed data into a pipe |
167 | * @pipe: pipe to fill |
168 | * @spd: data to fill |
169 | * |
170 | * Description: |
171 | * @spd contains a map of pages and len/offset tuples, along with |
172 | * the struct pipe_buf_operations associated with these pages. This |
173 | * function will link that data to the pipe. |
174 | * |
175 | */ |
176 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
177 | struct splice_pipe_desc *spd) |
178 | { |
179 | unsigned int spd_pages = spd->nr_pages; |
180 | int ret, do_wakeup, page_nr; |
181 | |
182 | ret = 0; |
183 | do_wakeup = 0; |
184 | page_nr = 0; |
185 | |
186 | pipe_lock(pipe); |
187 | |
188 | for (;;) { |
189 | if (!pipe->readers) { |
190 | send_sig(SIGPIPE, current, 0); |
191 | if (!ret) |
192 | ret = -EPIPE; |
193 | break; |
194 | } |
195 | |
196 | if (pipe->nrbufs < pipe->buffers) { |
197 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); |
198 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
199 | |
200 | buf->page = spd->pages[page_nr]; |
201 | buf->offset = spd->partial[page_nr].offset; |
202 | buf->len = spd->partial[page_nr].len; |
203 | buf->private = spd->partial[page_nr].private; |
204 | buf->ops = spd->ops; |
205 | if (spd->flags & SPLICE_F_GIFT) |
206 | buf->flags |= PIPE_BUF_FLAG_GIFT; |
207 | |
208 | pipe->nrbufs++; |
209 | page_nr++; |
210 | ret += buf->len; |
211 | |
212 | if (pipe->inode) |
213 | do_wakeup = 1; |
214 | |
215 | if (!--spd->nr_pages) |
216 | break; |
217 | if (pipe->nrbufs < pipe->buffers) |
218 | continue; |
219 | |
220 | break; |
221 | } |
222 | |
223 | if (spd->flags & SPLICE_F_NONBLOCK) { |
224 | if (!ret) |
225 | ret = -EAGAIN; |
226 | break; |
227 | } |
228 | |
229 | if (signal_pending(current)) { |
230 | if (!ret) |
231 | ret = -ERESTARTSYS; |
232 | break; |
233 | } |
234 | |
235 | if (do_wakeup) { |
236 | smp_mb(); |
237 | if (waitqueue_active(&pipe->wait)) |
238 | wake_up_interruptible_sync(&pipe->wait); |
239 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
240 | do_wakeup = 0; |
241 | } |
242 | |
243 | pipe->waiting_writers++; |
244 | pipe_wait(pipe); |
245 | pipe->waiting_writers--; |
246 | } |
247 | |
248 | pipe_unlock(pipe); |
249 | |
250 | if (do_wakeup) { |
251 | smp_mb(); |
252 | if (waitqueue_active(&pipe->wait)) |
253 | wake_up_interruptible(&pipe->wait); |
254 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
255 | } |
256 | |
257 | while (page_nr < spd_pages) |
258 | spd->spd_release(spd, page_nr++); |
259 | |
260 | return ret; |
261 | } |
262 | |
263 | static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
264 | { |
265 | page_cache_release(spd->pages[i]); |
266 | } |
267 | |
268 | /* |
269 | * Check if we need to grow the arrays holding pages and partial page |
270 | * descriptions. |
271 | */ |
272 | int splice_grow_spd(struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
273 | { |
274 | if (pipe->buffers <= PIPE_DEF_BUFFERS) |
275 | return 0; |
276 | |
277 | spd->pages = kmalloc(pipe->buffers * sizeof(struct page *), GFP_KERNEL); |
278 | spd->partial = kmalloc(pipe->buffers * sizeof(struct partial_page), GFP_KERNEL); |
279 | |
280 | if (spd->pages && spd->partial) |
281 | return 0; |
282 | |
283 | kfree(spd->pages); |
284 | kfree(spd->partial); |
285 | return -ENOMEM; |
286 | } |
287 | |
288 | void splice_shrink_spd(struct pipe_inode_info *pipe, |
289 | struct splice_pipe_desc *spd) |
290 | { |
291 | if (pipe->buffers <= PIPE_DEF_BUFFERS) |
292 | return; |
293 | |
294 | kfree(spd->pages); |
295 | kfree(spd->partial); |
296 | } |
297 | |
298 | static int |
299 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
300 | struct pipe_inode_info *pipe, size_t len, |
301 | unsigned int flags) |
302 | { |
303 | struct address_space *mapping = in->f_mapping; |
304 | unsigned int loff, nr_pages, req_pages; |
305 | struct page *pages[PIPE_DEF_BUFFERS]; |
306 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
307 | struct page *page; |
308 | pgoff_t index, end_index; |
309 | loff_t isize; |
310 | int error, page_nr; |
311 | struct splice_pipe_desc spd = { |
312 | .pages = pages, |
313 | .partial = partial, |
314 | .flags = flags, |
315 | .ops = &page_cache_pipe_buf_ops, |
316 | .spd_release = spd_release_page, |
317 | }; |
318 | |
319 | if (splice_grow_spd(pipe, &spd)) |
320 | return -ENOMEM; |
321 | |
322 | index = *ppos >> PAGE_CACHE_SHIFT; |
323 | loff = *ppos & ~PAGE_CACHE_MASK; |
324 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
325 | nr_pages = min(req_pages, pipe->buffers); |
326 | |
327 | /* |
328 | * Lookup the (hopefully) full range of pages we need. |
329 | */ |
330 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); |
331 | index += spd.nr_pages; |
332 | |
333 | /* |
334 | * If find_get_pages_contig() returned fewer pages than we needed, |
335 | * readahead/allocate the rest and fill in the holes. |
336 | */ |
337 | if (spd.nr_pages < nr_pages) |
338 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
339 | index, req_pages - spd.nr_pages); |
340 | |
341 | error = 0; |
342 | while (spd.nr_pages < nr_pages) { |
343 | /* |
344 | * Page could be there, find_get_pages_contig() breaks on |
345 | * the first hole. |
346 | */ |
347 | page = find_get_page(mapping, index); |
348 | if (!page) { |
349 | /* |
350 | * page didn't exist, allocate one. |
351 | */ |
352 | page = page_cache_alloc_cold(mapping); |
353 | if (!page) |
354 | break; |
355 | |
356 | error = add_to_page_cache_lru(page, mapping, index, |
357 | GFP_KERNEL); |
358 | if (unlikely(error)) { |
359 | page_cache_release(page); |
360 | if (error == -EEXIST) |
361 | continue; |
362 | break; |
363 | } |
364 | /* |
365 | * add_to_page_cache() locks the page, unlock it |
366 | * to avoid convoluting the logic below even more. |
367 | */ |
368 | unlock_page(page); |
369 | } |
370 | |
371 | spd.pages[spd.nr_pages++] = page; |
372 | index++; |
373 | } |
374 | |
375 | /* |
376 | * Now loop over the map and see if we need to start IO on any |
377 | * pages, fill in the partial map, etc. |
378 | */ |
379 | index = *ppos >> PAGE_CACHE_SHIFT; |
380 | nr_pages = spd.nr_pages; |
381 | spd.nr_pages = 0; |
382 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
383 | unsigned int this_len; |
384 | |
385 | if (!len) |
386 | break; |
387 | |
388 | /* |
389 | * this_len is the max we'll use from this page |
390 | */ |
391 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
392 | page = spd.pages[page_nr]; |
393 | |
394 | if (PageReadahead(page)) |
395 | page_cache_async_readahead(mapping, &in->f_ra, in, |
396 | page, index, req_pages - page_nr); |
397 | |
398 | /* |
399 | * If the page isn't uptodate, we may need to start io on it |
400 | */ |
401 | if (!PageUptodate(page)) { |
402 | lock_page(page); |
403 | |
404 | /* |
405 | * Page was truncated, or invalidated by the |
406 | * filesystem. Redo the find/create, but this time the |
407 | * page is kept locked, so there's no chance of another |
408 | * race with truncate/invalidate. |
409 | */ |
410 | if (!page->mapping) { |
411 | unlock_page(page); |
412 | page = find_or_create_page(mapping, index, |
413 | mapping_gfp_mask(mapping)); |
414 | |
415 | if (!page) { |
416 | error = -ENOMEM; |
417 | break; |
418 | } |
419 | page_cache_release(spd.pages[page_nr]); |
420 | spd.pages[page_nr] = page; |
421 | } |
422 | /* |
423 | * page was already under io and is now done, great |
424 | */ |
425 | if (PageUptodate(page)) { |
426 | unlock_page(page); |
427 | goto fill_it; |
428 | } |
429 | |
430 | /* |
431 | * need to read in the page |
432 | */ |
433 | error = mapping->a_ops->readpage(in, page); |
434 | if (unlikely(error)) { |
435 | /* |
436 | * We really should re-lookup the page here, |
437 | * but it complicates things a lot. Instead |
438 | * lets just do what we already stored, and |
439 | * we'll get it the next time we are called. |
440 | */ |
441 | if (error == AOP_TRUNCATED_PAGE) |
442 | error = 0; |
443 | |
444 | break; |
445 | } |
446 | } |
447 | fill_it: |
448 | /* |
449 | * i_size must be checked after PageUptodate. |
450 | */ |
451 | isize = i_size_read(mapping->host); |
452 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
453 | if (unlikely(!isize || index > end_index)) |
454 | break; |
455 | |
456 | /* |
457 | * if this is the last page, see if we need to shrink |
458 | * the length and stop |
459 | */ |
460 | if (end_index == index) { |
461 | unsigned int plen; |
462 | |
463 | /* |
464 | * max good bytes in this page |
465 | */ |
466 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
467 | if (plen <= loff) |
468 | break; |
469 | |
470 | /* |
471 | * force quit after adding this page |
472 | */ |
473 | this_len = min(this_len, plen - loff); |
474 | len = this_len; |
475 | } |
476 | |
477 | spd.partial[page_nr].offset = loff; |
478 | spd.partial[page_nr].len = this_len; |
479 | len -= this_len; |
480 | loff = 0; |
481 | spd.nr_pages++; |
482 | index++; |
483 | } |
484 | |
485 | /* |
486 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
487 | * we got, 'nr_pages' is how many pages are in the map. |
488 | */ |
489 | while (page_nr < nr_pages) |
490 | page_cache_release(spd.pages[page_nr++]); |
491 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
492 | |
493 | if (spd.nr_pages) |
494 | error = splice_to_pipe(pipe, &spd); |
495 | |
496 | splice_shrink_spd(pipe, &spd); |
497 | return error; |
498 | } |
499 | |
500 | /** |
501 | * generic_file_splice_read - splice data from file to a pipe |
502 | * @in: file to splice from |
503 | * @ppos: position in @in |
504 | * @pipe: pipe to splice to |
505 | * @len: number of bytes to splice |
506 | * @flags: splice modifier flags |
507 | * |
508 | * Description: |
509 | * Will read pages from given file and fill them into a pipe. Can be |
510 | * used as long as the address_space operations for the source implements |
511 | * a readpage() hook. |
512 | * |
513 | */ |
514 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
515 | struct pipe_inode_info *pipe, size_t len, |
516 | unsigned int flags) |
517 | { |
518 | loff_t isize, left; |
519 | int ret; |
520 | |
521 | isize = i_size_read(in->f_mapping->host); |
522 | if (unlikely(*ppos >= isize)) |
523 | return 0; |
524 | |
525 | left = isize - *ppos; |
526 | if (unlikely(left < len)) |
527 | len = left; |
528 | |
529 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
530 | if (ret > 0) { |
531 | *ppos += ret; |
532 | file_accessed(in); |
533 | } |
534 | |
535 | return ret; |
536 | } |
537 | EXPORT_SYMBOL(generic_file_splice_read); |
538 | |
539 | static const struct pipe_buf_operations default_pipe_buf_ops = { |
540 | .can_merge = 0, |
541 | .map = generic_pipe_buf_map, |
542 | .unmap = generic_pipe_buf_unmap, |
543 | .confirm = generic_pipe_buf_confirm, |
544 | .release = generic_pipe_buf_release, |
545 | .steal = generic_pipe_buf_steal, |
546 | .get = generic_pipe_buf_get, |
547 | }; |
548 | |
549 | static ssize_t kernel_readv(struct file *file, const struct iovec *vec, |
550 | unsigned long vlen, loff_t offset) |
551 | { |
552 | mm_segment_t old_fs; |
553 | loff_t pos = offset; |
554 | ssize_t res; |
555 | |
556 | old_fs = get_fs(); |
557 | set_fs(get_ds()); |
558 | /* The cast to a user pointer is valid due to the set_fs() */ |
559 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos); |
560 | set_fs(old_fs); |
561 | |
562 | return res; |
563 | } |
564 | |
565 | static ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
566 | loff_t pos) |
567 | { |
568 | mm_segment_t old_fs; |
569 | ssize_t res; |
570 | |
571 | old_fs = get_fs(); |
572 | set_fs(get_ds()); |
573 | /* The cast to a user pointer is valid due to the set_fs() */ |
574 | res = vfs_write(file, (const char __user *)buf, count, &pos); |
575 | set_fs(old_fs); |
576 | |
577 | return res; |
578 | } |
579 | |
580 | ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
581 | struct pipe_inode_info *pipe, size_t len, |
582 | unsigned int flags) |
583 | { |
584 | unsigned int nr_pages; |
585 | unsigned int nr_freed; |
586 | size_t offset; |
587 | struct page *pages[PIPE_DEF_BUFFERS]; |
588 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
589 | struct iovec *vec, __vec[PIPE_DEF_BUFFERS]; |
590 | ssize_t res; |
591 | size_t this_len; |
592 | int error; |
593 | int i; |
594 | struct splice_pipe_desc spd = { |
595 | .pages = pages, |
596 | .partial = partial, |
597 | .flags = flags, |
598 | .ops = &default_pipe_buf_ops, |
599 | .spd_release = spd_release_page, |
600 | }; |
601 | |
602 | if (splice_grow_spd(pipe, &spd)) |
603 | return -ENOMEM; |
604 | |
605 | res = -ENOMEM; |
606 | vec = __vec; |
607 | if (pipe->buffers > PIPE_DEF_BUFFERS) { |
608 | vec = kmalloc(pipe->buffers * sizeof(struct iovec), GFP_KERNEL); |
609 | if (!vec) |
610 | goto shrink_ret; |
611 | } |
612 | |
613 | offset = *ppos & ~PAGE_CACHE_MASK; |
614 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
615 | |
616 | for (i = 0; i < nr_pages && i < pipe->buffers && len; i++) { |
617 | struct page *page; |
618 | |
619 | page = alloc_page(GFP_USER); |
620 | error = -ENOMEM; |
621 | if (!page) |
622 | goto err; |
623 | |
624 | this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); |
625 | vec[i].iov_base = (void __user *) page_address(page); |
626 | vec[i].iov_len = this_len; |
627 | spd.pages[i] = page; |
628 | spd.nr_pages++; |
629 | len -= this_len; |
630 | offset = 0; |
631 | } |
632 | |
633 | res = kernel_readv(in, vec, spd.nr_pages, *ppos); |
634 | if (res < 0) { |
635 | error = res; |
636 | goto err; |
637 | } |
638 | |
639 | error = 0; |
640 | if (!res) |
641 | goto err; |
642 | |
643 | nr_freed = 0; |
644 | for (i = 0; i < spd.nr_pages; i++) { |
645 | this_len = min_t(size_t, vec[i].iov_len, res); |
646 | spd.partial[i].offset = 0; |
647 | spd.partial[i].len = this_len; |
648 | if (!this_len) { |
649 | __free_page(spd.pages[i]); |
650 | spd.pages[i] = NULL; |
651 | nr_freed++; |
652 | } |
653 | res -= this_len; |
654 | } |
655 | spd.nr_pages -= nr_freed; |
656 | |
657 | res = splice_to_pipe(pipe, &spd); |
658 | if (res > 0) |
659 | *ppos += res; |
660 | |
661 | shrink_ret: |
662 | if (vec != __vec) |
663 | kfree(vec); |
664 | splice_shrink_spd(pipe, &spd); |
665 | return res; |
666 | |
667 | err: |
668 | for (i = 0; i < spd.nr_pages; i++) |
669 | __free_page(spd.pages[i]); |
670 | |
671 | res = error; |
672 | goto shrink_ret; |
673 | } |
674 | EXPORT_SYMBOL(default_file_splice_read); |
675 | |
676 | /* |
677 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
678 | * using sendpage(). Return the number of bytes sent. |
679 | */ |
680 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
681 | struct pipe_buffer *buf, struct splice_desc *sd) |
682 | { |
683 | struct file *file = sd->u.file; |
684 | loff_t pos = sd->pos; |
685 | int ret, more; |
686 | |
687 | ret = buf->ops->confirm(pipe, buf); |
688 | if (!ret) { |
689 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
690 | if (file->f_op && file->f_op->sendpage) |
691 | ret = file->f_op->sendpage(file, buf->page, buf->offset, |
692 | sd->len, &pos, more); |
693 | else |
694 | ret = -EINVAL; |
695 | } |
696 | |
697 | return ret; |
698 | } |
699 | |
700 | /* |
701 | * This is a little more tricky than the file -> pipe splicing. There are |
702 | * basically three cases: |
703 | * |
704 | * - Destination page already exists in the address space and there |
705 | * are users of it. For that case we have no other option that |
706 | * copying the data. Tough luck. |
707 | * - Destination page already exists in the address space, but there |
708 | * are no users of it. Make sure it's uptodate, then drop it. Fall |
709 | * through to last case. |
710 | * - Destination page does not exist, we can add the pipe page to |
711 | * the page cache and avoid the copy. |
712 | * |
713 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
714 | * sd->flags), we attempt to migrate pages from the pipe to the output |
715 | * file address space page cache. This is possible if no one else has |
716 | * the pipe page referenced outside of the pipe and page cache. If |
717 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create |
718 | * a new page in the output file page cache and fill/dirty that. |
719 | */ |
720 | int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
721 | struct splice_desc *sd) |
722 | { |
723 | struct file *file = sd->u.file; |
724 | struct address_space *mapping = file->f_mapping; |
725 | unsigned int offset, this_len; |
726 | struct page *page; |
727 | void *fsdata; |
728 | int ret; |
729 | |
730 | /* |
731 | * make sure the data in this buffer is uptodate |
732 | */ |
733 | ret = buf->ops->confirm(pipe, buf); |
734 | if (unlikely(ret)) |
735 | return ret; |
736 | |
737 | offset = sd->pos & ~PAGE_CACHE_MASK; |
738 | |
739 | this_len = sd->len; |
740 | if (this_len + offset > PAGE_CACHE_SIZE) |
741 | this_len = PAGE_CACHE_SIZE - offset; |
742 | |
743 | ret = pagecache_write_begin(file, mapping, sd->pos, this_len, |
744 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); |
745 | if (unlikely(ret)) |
746 | goto out; |
747 | |
748 | if (buf->page != page) { |
749 | /* |
750 | * Careful, ->map() uses KM_USER0! |
751 | */ |
752 | char *src = buf->ops->map(pipe, buf, 1); |
753 | char *dst = kmap_atomic(page, KM_USER1); |
754 | |
755 | memcpy(dst + offset, src + buf->offset, this_len); |
756 | flush_dcache_page(page); |
757 | kunmap_atomic(dst, KM_USER1); |
758 | buf->ops->unmap(pipe, buf, src); |
759 | } |
760 | ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, |
761 | page, fsdata); |
762 | out: |
763 | return ret; |
764 | } |
765 | EXPORT_SYMBOL(pipe_to_file); |
766 | |
767 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
768 | { |
769 | smp_mb(); |
770 | if (waitqueue_active(&pipe->wait)) |
771 | wake_up_interruptible(&pipe->wait); |
772 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
773 | } |
774 | |
775 | /** |
776 | * splice_from_pipe_feed - feed available data from a pipe to a file |
777 | * @pipe: pipe to splice from |
778 | * @sd: information to @actor |
779 | * @actor: handler that splices the data |
780 | * |
781 | * Description: |
782 | * This function loops over the pipe and calls @actor to do the |
783 | * actual moving of a single struct pipe_buffer to the desired |
784 | * destination. It returns when there's no more buffers left in |
785 | * the pipe or if the requested number of bytes (@sd->total_len) |
786 | * have been copied. It returns a positive number (one) if the |
787 | * pipe needs to be filled with more data, zero if the required |
788 | * number of bytes have been copied and -errno on error. |
789 | * |
790 | * This, together with splice_from_pipe_{begin,end,next}, may be |
791 | * used to implement the functionality of __splice_from_pipe() when |
792 | * locking is required around copying the pipe buffers to the |
793 | * destination. |
794 | */ |
795 | int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
796 | splice_actor *actor) |
797 | { |
798 | int ret; |
799 | |
800 | while (pipe->nrbufs) { |
801 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
802 | const struct pipe_buf_operations *ops = buf->ops; |
803 | |
804 | sd->len = buf->len; |
805 | if (sd->len > sd->total_len) |
806 | sd->len = sd->total_len; |
807 | |
808 | ret = actor(pipe, buf, sd); |
809 | if (ret <= 0) { |
810 | if (ret == -ENODATA) |
811 | 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 | file_update_time(out); |
1011 | ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file); |
1012 | } |
1013 | mutex_unlock(&inode->i_mutex); |
1014 | } while (ret > 0); |
1015 | splice_from_pipe_end(pipe, &sd); |
1016 | |
1017 | pipe_unlock(pipe); |
1018 | |
1019 | if (sd.num_spliced) |
1020 | ret = sd.num_spliced; |
1021 | |
1022 | if (ret > 0) { |
1023 | unsigned long nr_pages; |
1024 | int err; |
1025 | |
1026 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1027 | |
1028 | err = generic_write_sync(out, *ppos, ret); |
1029 | if (err) |
1030 | ret = err; |
1031 | else |
1032 | *ppos += ret; |
1033 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
1034 | } |
1035 | |
1036 | return ret; |
1037 | } |
1038 | |
1039 | EXPORT_SYMBOL(generic_file_splice_write); |
1040 | |
1041 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1042 | struct splice_desc *sd) |
1043 | { |
1044 | int ret; |
1045 | void *data; |
1046 | |
1047 | ret = buf->ops->confirm(pipe, buf); |
1048 | if (ret) |
1049 | return ret; |
1050 | |
1051 | data = buf->ops->map(pipe, buf, 0); |
1052 | ret = kernel_write(sd->u.file, data + buf->offset, sd->len, sd->pos); |
1053 | buf->ops->unmap(pipe, buf, data); |
1054 | |
1055 | return ret; |
1056 | } |
1057 | |
1058 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, |
1059 | struct file *out, loff_t *ppos, |
1060 | size_t len, unsigned int flags) |
1061 | { |
1062 | ssize_t ret; |
1063 | |
1064 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
1065 | if (ret > 0) |
1066 | *ppos += ret; |
1067 | |
1068 | return ret; |
1069 | } |
1070 | |
1071 | /** |
1072 | * generic_splice_sendpage - splice data from a pipe to a socket |
1073 | * @pipe: pipe to splice from |
1074 | * @out: socket to write to |
1075 | * @ppos: position in @out |
1076 | * @len: number of bytes to splice |
1077 | * @flags: splice modifier flags |
1078 | * |
1079 | * Description: |
1080 | * Will send @len bytes from the pipe to a network socket. No data copying |
1081 | * is involved. |
1082 | * |
1083 | */ |
1084 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
1085 | loff_t *ppos, size_t len, unsigned int flags) |
1086 | { |
1087 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
1088 | } |
1089 | |
1090 | EXPORT_SYMBOL(generic_splice_sendpage); |
1091 | |
1092 | /* |
1093 | * Attempt to initiate a splice from pipe to file. |
1094 | */ |
1095 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
1096 | loff_t *ppos, size_t len, unsigned int flags) |
1097 | { |
1098 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
1099 | loff_t *, size_t, unsigned int); |
1100 | int ret; |
1101 | |
1102 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1103 | return -EBADF; |
1104 | |
1105 | if (unlikely(out->f_flags & O_APPEND)) |
1106 | return -EINVAL; |
1107 | |
1108 | ret = rw_verify_area(WRITE, out, ppos, len); |
1109 | if (unlikely(ret < 0)) |
1110 | return ret; |
1111 | |
1112 | if (out->f_op && out->f_op->splice_write) |
1113 | splice_write = out->f_op->splice_write; |
1114 | else |
1115 | splice_write = default_file_splice_write; |
1116 | |
1117 | return splice_write(pipe, out, ppos, len, flags); |
1118 | } |
1119 | |
1120 | /* |
1121 | * Attempt to initiate a splice from a file to a pipe. |
1122 | */ |
1123 | static long do_splice_to(struct file *in, loff_t *ppos, |
1124 | struct pipe_inode_info *pipe, size_t len, |
1125 | unsigned int flags) |
1126 | { |
1127 | ssize_t (*splice_read)(struct file *, loff_t *, |
1128 | struct pipe_inode_info *, size_t, unsigned int); |
1129 | int ret; |
1130 | |
1131 | if (unlikely(!(in->f_mode & FMODE_READ))) |
1132 | return -EBADF; |
1133 | |
1134 | ret = rw_verify_area(READ, in, ppos, len); |
1135 | if (unlikely(ret < 0)) |
1136 | return ret; |
1137 | |
1138 | if (in->f_op && in->f_op->splice_read) |
1139 | splice_read = in->f_op->splice_read; |
1140 | else |
1141 | splice_read = default_file_splice_read; |
1142 | |
1143 | return splice_read(in, ppos, pipe, len, flags); |
1144 | } |
1145 | |
1146 | /** |
1147 | * splice_direct_to_actor - splices data directly between two non-pipes |
1148 | * @in: file to splice from |
1149 | * @sd: actor information on where to splice to |
1150 | * @actor: handles the data splicing |
1151 | * |
1152 | * Description: |
1153 | * This is a special case helper to splice directly between two |
1154 | * points, without requiring an explicit pipe. Internally an allocated |
1155 | * pipe is cached in the process, and reused during the lifetime of |
1156 | * that process. |
1157 | * |
1158 | */ |
1159 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, |
1160 | splice_direct_actor *actor) |
1161 | { |
1162 | struct pipe_inode_info *pipe; |
1163 | long ret, bytes; |
1164 | umode_t i_mode; |
1165 | size_t len; |
1166 | int i, flags; |
1167 | |
1168 | /* |
1169 | * We require the input being a regular file, as we don't want to |
1170 | * randomly drop data for eg socket -> socket splicing. Use the |
1171 | * piped splicing for that! |
1172 | */ |
1173 | i_mode = in->f_path.dentry->d_inode->i_mode; |
1174 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
1175 | return -EINVAL; |
1176 | |
1177 | /* |
1178 | * neither in nor out is a pipe, setup an internal pipe attached to |
1179 | * 'out' and transfer the wanted data from 'in' to 'out' through that |
1180 | */ |
1181 | pipe = current->splice_pipe; |
1182 | if (unlikely(!pipe)) { |
1183 | pipe = alloc_pipe_info(NULL); |
1184 | if (!pipe) |
1185 | return -ENOMEM; |
1186 | |
1187 | /* |
1188 | * We don't have an immediate reader, but we'll read the stuff |
1189 | * out of the pipe right after the splice_to_pipe(). So set |
1190 | * PIPE_READERS appropriately. |
1191 | */ |
1192 | pipe->readers = 1; |
1193 | |
1194 | current->splice_pipe = pipe; |
1195 | } |
1196 | |
1197 | /* |
1198 | * Do the splice. |
1199 | */ |
1200 | ret = 0; |
1201 | bytes = 0; |
1202 | len = sd->total_len; |
1203 | flags = sd->flags; |
1204 | |
1205 | /* |
1206 | * Don't block on output, we have to drain the direct pipe. |
1207 | */ |
1208 | sd->flags &= ~SPLICE_F_NONBLOCK; |
1209 | |
1210 | while (len) { |
1211 | size_t read_len; |
1212 | loff_t pos = sd->pos, prev_pos = pos; |
1213 | |
1214 | ret = do_splice_to(in, &pos, pipe, len, flags); |
1215 | if (unlikely(ret <= 0)) |
1216 | goto out_release; |
1217 | |
1218 | read_len = ret; |
1219 | sd->total_len = read_len; |
1220 | |
1221 | /* |
1222 | * NOTE: nonblocking mode only applies to the input. We |
1223 | * must not do the output in nonblocking mode as then we |
1224 | * could get stuck data in the internal pipe: |
1225 | */ |
1226 | ret = actor(pipe, sd); |
1227 | if (unlikely(ret <= 0)) { |
1228 | sd->pos = prev_pos; |
1229 | goto out_release; |
1230 | } |
1231 | |
1232 | bytes += ret; |
1233 | len -= ret; |
1234 | sd->pos = pos; |
1235 | |
1236 | if (ret < read_len) { |
1237 | sd->pos = prev_pos + ret; |
1238 | goto out_release; |
1239 | } |
1240 | } |
1241 | |
1242 | done: |
1243 | pipe->nrbufs = pipe->curbuf = 0; |
1244 | file_accessed(in); |
1245 | return bytes; |
1246 | |
1247 | out_release: |
1248 | /* |
1249 | * If we did an incomplete transfer we must release |
1250 | * the pipe buffers in question: |
1251 | */ |
1252 | for (i = 0; i < pipe->buffers; i++) { |
1253 | struct pipe_buffer *buf = pipe->bufs + i; |
1254 | |
1255 | if (buf->ops) { |
1256 | buf->ops->release(pipe, buf); |
1257 | buf->ops = NULL; |
1258 | } |
1259 | } |
1260 | |
1261 | if (!bytes) |
1262 | bytes = ret; |
1263 | |
1264 | goto done; |
1265 | } |
1266 | EXPORT_SYMBOL(splice_direct_to_actor); |
1267 | |
1268 | static int direct_splice_actor(struct pipe_inode_info *pipe, |
1269 | struct splice_desc *sd) |
1270 | { |
1271 | struct file *file = sd->u.file; |
1272 | |
1273 | return do_splice_from(pipe, file, &file->f_pos, sd->total_len, |
1274 | sd->flags); |
1275 | } |
1276 | |
1277 | /** |
1278 | * do_splice_direct - splices data directly between two files |
1279 | * @in: file to splice from |
1280 | * @ppos: input file offset |
1281 | * @out: file to splice to |
1282 | * @len: number of bytes to splice |
1283 | * @flags: splice modifier flags |
1284 | * |
1285 | * Description: |
1286 | * For use by do_sendfile(). splice can easily emulate sendfile, but |
1287 | * doing it in the application would incur an extra system call |
1288 | * (splice in + splice out, as compared to just sendfile()). So this helper |
1289 | * can splice directly through a process-private pipe. |
1290 | * |
1291 | */ |
1292 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1293 | size_t len, unsigned int flags) |
1294 | { |
1295 | struct splice_desc sd = { |
1296 | .len = len, |
1297 | .total_len = len, |
1298 | .flags = flags, |
1299 | .pos = *ppos, |
1300 | .u.file = out, |
1301 | }; |
1302 | long ret; |
1303 | |
1304 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
1305 | if (ret > 0) |
1306 | *ppos = sd.pos; |
1307 | |
1308 | return ret; |
1309 | } |
1310 | |
1311 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1312 | struct pipe_inode_info *opipe, |
1313 | size_t len, unsigned int flags); |
1314 | /* |
1315 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same |
1316 | * location, so checking ->i_pipe is not enough to verify that this is a |
1317 | * pipe. |
1318 | */ |
1319 | static inline struct pipe_inode_info *pipe_info(struct inode *inode) |
1320 | { |
1321 | if (S_ISFIFO(inode->i_mode)) |
1322 | return inode->i_pipe; |
1323 | |
1324 | return NULL; |
1325 | } |
1326 | |
1327 | /* |
1328 | * Determine where to splice to/from. |
1329 | */ |
1330 | static long do_splice(struct file *in, loff_t __user *off_in, |
1331 | struct file *out, loff_t __user *off_out, |
1332 | size_t len, unsigned int flags) |
1333 | { |
1334 | struct pipe_inode_info *ipipe; |
1335 | struct pipe_inode_info *opipe; |
1336 | loff_t offset, *off; |
1337 | long ret; |
1338 | |
1339 | ipipe = pipe_info(in->f_path.dentry->d_inode); |
1340 | opipe = pipe_info(out->f_path.dentry->d_inode); |
1341 | |
1342 | if (ipipe && opipe) { |
1343 | if (off_in || off_out) |
1344 | return -ESPIPE; |
1345 | |
1346 | if (!(in->f_mode & FMODE_READ)) |
1347 | return -EBADF; |
1348 | |
1349 | if (!(out->f_mode & FMODE_WRITE)) |
1350 | return -EBADF; |
1351 | |
1352 | /* Splicing to self would be fun, but... */ |
1353 | if (ipipe == opipe) |
1354 | return -EINVAL; |
1355 | |
1356 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1357 | } |
1358 | |
1359 | if (ipipe) { |
1360 | if (off_in) |
1361 | return -ESPIPE; |
1362 | if (off_out) { |
1363 | if (!(out->f_mode & FMODE_PWRITE)) |
1364 | return -EINVAL; |
1365 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
1366 | return -EFAULT; |
1367 | off = &offset; |
1368 | } else |
1369 | off = &out->f_pos; |
1370 | |
1371 | ret = do_splice_from(ipipe, out, off, len, flags); |
1372 | |
1373 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) |
1374 | ret = -EFAULT; |
1375 | |
1376 | return ret; |
1377 | } |
1378 | |
1379 | if (opipe) { |
1380 | if (off_out) |
1381 | return -ESPIPE; |
1382 | if (off_in) { |
1383 | if (!(in->f_mode & FMODE_PREAD)) |
1384 | return -EINVAL; |
1385 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
1386 | return -EFAULT; |
1387 | off = &offset; |
1388 | } else |
1389 | off = &in->f_pos; |
1390 | |
1391 | ret = do_splice_to(in, off, opipe, len, flags); |
1392 | |
1393 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) |
1394 | ret = -EFAULT; |
1395 | |
1396 | return ret; |
1397 | } |
1398 | |
1399 | return -EINVAL; |
1400 | } |
1401 | |
1402 | /* |
1403 | * Map an iov into an array of pages and offset/length tupples. With the |
1404 | * partial_page structure, we can map several non-contiguous ranges into |
1405 | * our ones pages[] map instead of splitting that operation into pieces. |
1406 | * Could easily be exported as a generic helper for other users, in which |
1407 | * case one would probably want to add a 'max_nr_pages' parameter as well. |
1408 | */ |
1409 | static int get_iovec_page_array(const struct iovec __user *iov, |
1410 | unsigned int nr_vecs, struct page **pages, |
1411 | struct partial_page *partial, int aligned, |
1412 | unsigned int pipe_buffers) |
1413 | { |
1414 | int buffers = 0, error = 0; |
1415 | |
1416 | while (nr_vecs) { |
1417 | unsigned long off, npages; |
1418 | struct iovec entry; |
1419 | void __user *base; |
1420 | size_t len; |
1421 | int i; |
1422 | |
1423 | error = -EFAULT; |
1424 | if (copy_from_user(&entry, iov, sizeof(entry))) |
1425 | break; |
1426 | |
1427 | base = entry.iov_base; |
1428 | len = entry.iov_len; |
1429 | |
1430 | /* |
1431 | * Sanity check this iovec. 0 read succeeds. |
1432 | */ |
1433 | error = 0; |
1434 | if (unlikely(!len)) |
1435 | break; |
1436 | error = -EFAULT; |
1437 | if (!access_ok(VERIFY_READ, base, len)) |
1438 | break; |
1439 | |
1440 | /* |
1441 | * Get this base offset and number of pages, then map |
1442 | * in the user pages. |
1443 | */ |
1444 | off = (unsigned long) base & ~PAGE_MASK; |
1445 | |
1446 | /* |
1447 | * If asked for alignment, the offset must be zero and the |
1448 | * length a multiple of the PAGE_SIZE. |
1449 | */ |
1450 | error = -EINVAL; |
1451 | if (aligned && (off || len & ~PAGE_MASK)) |
1452 | break; |
1453 | |
1454 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1455 | if (npages > pipe_buffers - buffers) |
1456 | npages = pipe_buffers - buffers; |
1457 | |
1458 | error = get_user_pages_fast((unsigned long)base, npages, |
1459 | 0, &pages[buffers]); |
1460 | |
1461 | if (unlikely(error <= 0)) |
1462 | break; |
1463 | |
1464 | /* |
1465 | * Fill this contiguous range into the partial page map. |
1466 | */ |
1467 | for (i = 0; i < error; i++) { |
1468 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
1469 | |
1470 | partial[buffers].offset = off; |
1471 | partial[buffers].len = plen; |
1472 | |
1473 | off = 0; |
1474 | len -= plen; |
1475 | buffers++; |
1476 | } |
1477 | |
1478 | /* |
1479 | * We didn't complete this iov, stop here since it probably |
1480 | * means we have to move some of this into a pipe to |
1481 | * be able to continue. |
1482 | */ |
1483 | if (len) |
1484 | break; |
1485 | |
1486 | /* |
1487 | * Don't continue if we mapped fewer pages than we asked for, |
1488 | * or if we mapped the max number of pages that we have |
1489 | * room for. |
1490 | */ |
1491 | if (error < npages || buffers == pipe_buffers) |
1492 | break; |
1493 | |
1494 | nr_vecs--; |
1495 | iov++; |
1496 | } |
1497 | |
1498 | if (buffers) |
1499 | return buffers; |
1500 | |
1501 | return error; |
1502 | } |
1503 | |
1504 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1505 | struct splice_desc *sd) |
1506 | { |
1507 | char *src; |
1508 | int ret; |
1509 | |
1510 | ret = buf->ops->confirm(pipe, buf); |
1511 | if (unlikely(ret)) |
1512 | return ret; |
1513 | |
1514 | /* |
1515 | * See if we can use the atomic maps, by prefaulting in the |
1516 | * pages and doing an atomic copy |
1517 | */ |
1518 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { |
1519 | src = buf->ops->map(pipe, buf, 1); |
1520 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, |
1521 | sd->len); |
1522 | buf->ops->unmap(pipe, buf, src); |
1523 | if (!ret) { |
1524 | ret = sd->len; |
1525 | goto out; |
1526 | } |
1527 | } |
1528 | |
1529 | /* |
1530 | * No dice, use slow non-atomic map and copy |
1531 | */ |
1532 | src = buf->ops->map(pipe, buf, 0); |
1533 | |
1534 | ret = sd->len; |
1535 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) |
1536 | ret = -EFAULT; |
1537 | |
1538 | buf->ops->unmap(pipe, buf, src); |
1539 | out: |
1540 | if (ret > 0) |
1541 | sd->u.userptr += ret; |
1542 | return ret; |
1543 | } |
1544 | |
1545 | /* |
1546 | * For lack of a better implementation, implement vmsplice() to userspace |
1547 | * as a simple copy of the pipes pages to the user iov. |
1548 | */ |
1549 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, |
1550 | unsigned long nr_segs, unsigned int flags) |
1551 | { |
1552 | struct pipe_inode_info *pipe; |
1553 | struct splice_desc sd; |
1554 | ssize_t size; |
1555 | int error; |
1556 | long ret; |
1557 | |
1558 | pipe = pipe_info(file->f_path.dentry->d_inode); |
1559 | if (!pipe) |
1560 | return -EBADF; |
1561 | |
1562 | pipe_lock(pipe); |
1563 | |
1564 | error = ret = 0; |
1565 | while (nr_segs) { |
1566 | void __user *base; |
1567 | size_t len; |
1568 | |
1569 | /* |
1570 | * Get user address base and length for this iovec. |
1571 | */ |
1572 | error = get_user(base, &iov->iov_base); |
1573 | if (unlikely(error)) |
1574 | break; |
1575 | error = get_user(len, &iov->iov_len); |
1576 | if (unlikely(error)) |
1577 | break; |
1578 | |
1579 | /* |
1580 | * Sanity check this iovec. 0 read succeeds. |
1581 | */ |
1582 | if (unlikely(!len)) |
1583 | break; |
1584 | if (unlikely(!base)) { |
1585 | error = -EFAULT; |
1586 | break; |
1587 | } |
1588 | |
1589 | if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { |
1590 | error = -EFAULT; |
1591 | break; |
1592 | } |
1593 | |
1594 | sd.len = 0; |
1595 | sd.total_len = len; |
1596 | sd.flags = flags; |
1597 | sd.u.userptr = base; |
1598 | sd.pos = 0; |
1599 | |
1600 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); |
1601 | if (size < 0) { |
1602 | if (!ret) |
1603 | ret = size; |
1604 | |
1605 | break; |
1606 | } |
1607 | |
1608 | ret += size; |
1609 | |
1610 | if (size < len) |
1611 | break; |
1612 | |
1613 | nr_segs--; |
1614 | iov++; |
1615 | } |
1616 | |
1617 | pipe_unlock(pipe); |
1618 | |
1619 | if (!ret) |
1620 | ret = error; |
1621 | |
1622 | return ret; |
1623 | } |
1624 | |
1625 | /* |
1626 | * vmsplice splices a user address range into a pipe. It can be thought of |
1627 | * as splice-from-memory, where the regular splice is splice-from-file (or |
1628 | * to file). In both cases the output is a pipe, naturally. |
1629 | */ |
1630 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1631 | unsigned long nr_segs, unsigned int flags) |
1632 | { |
1633 | struct pipe_inode_info *pipe; |
1634 | struct page *pages[PIPE_DEF_BUFFERS]; |
1635 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1636 | struct splice_pipe_desc spd = { |
1637 | .pages = pages, |
1638 | .partial = partial, |
1639 | .flags = flags, |
1640 | .ops = &user_page_pipe_buf_ops, |
1641 | .spd_release = spd_release_page, |
1642 | }; |
1643 | long ret; |
1644 | |
1645 | pipe = pipe_info(file->f_path.dentry->d_inode); |
1646 | if (!pipe) |
1647 | return -EBADF; |
1648 | |
1649 | if (splice_grow_spd(pipe, &spd)) |
1650 | return -ENOMEM; |
1651 | |
1652 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, |
1653 | spd.partial, flags & SPLICE_F_GIFT, |
1654 | pipe->buffers); |
1655 | if (spd.nr_pages <= 0) |
1656 | ret = spd.nr_pages; |
1657 | else |
1658 | ret = splice_to_pipe(pipe, &spd); |
1659 | |
1660 | splice_shrink_spd(pipe, &spd); |
1661 | return ret; |
1662 | } |
1663 | |
1664 | /* |
1665 | * Note that vmsplice only really supports true splicing _from_ user memory |
1666 | * to a pipe, not the other way around. Splicing from user memory is a simple |
1667 | * operation that can be supported without any funky alignment restrictions |
1668 | * or nasty vm tricks. We simply map in the user memory and fill them into |
1669 | * a pipe. The reverse isn't quite as easy, though. There are two possible |
1670 | * solutions for that: |
1671 | * |
1672 | * - memcpy() the data internally, at which point we might as well just |
1673 | * do a regular read() on the buffer anyway. |
1674 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it |
1675 | * has restriction limitations on both ends of the pipe). |
1676 | * |
1677 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). |
1678 | * |
1679 | */ |
1680 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1681 | unsigned long, nr_segs, unsigned int, flags) |
1682 | { |
1683 | struct file *file; |
1684 | long error; |
1685 | int fput; |
1686 | |
1687 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1688 | return -EINVAL; |
1689 | else if (unlikely(!nr_segs)) |
1690 | return 0; |
1691 | |
1692 | error = -EBADF; |
1693 | file = fget_light(fd, &fput); |
1694 | if (file) { |
1695 | if (file->f_mode & FMODE_WRITE) |
1696 | error = vmsplice_to_pipe(file, iov, nr_segs, flags); |
1697 | else if (file->f_mode & FMODE_READ) |
1698 | error = vmsplice_to_user(file, iov, nr_segs, flags); |
1699 | |
1700 | fput_light(file, fput); |
1701 | } |
1702 | |
1703 | return error; |
1704 | } |
1705 | |
1706 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1707 | int, fd_out, loff_t __user *, off_out, |
1708 | size_t, len, unsigned int, flags) |
1709 | { |
1710 | long error; |
1711 | struct file *in, *out; |
1712 | int fput_in, fput_out; |
1713 | |
1714 | if (unlikely(!len)) |
1715 | return 0; |
1716 | |
1717 | error = -EBADF; |
1718 | in = fget_light(fd_in, &fput_in); |
1719 | if (in) { |
1720 | if (in->f_mode & FMODE_READ) { |
1721 | out = fget_light(fd_out, &fput_out); |
1722 | if (out) { |
1723 | if (out->f_mode & FMODE_WRITE) |
1724 | error = do_splice(in, off_in, |
1725 | out, off_out, |
1726 | len, flags); |
1727 | fput_light(out, fput_out); |
1728 | } |
1729 | } |
1730 | |
1731 | fput_light(in, fput_in); |
1732 | } |
1733 | |
1734 | return error; |
1735 | } |
1736 | |
1737 | /* |
1738 | * Make sure there's data to read. Wait for input if we can, otherwise |
1739 | * return an appropriate error. |
1740 | */ |
1741 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1742 | { |
1743 | int ret; |
1744 | |
1745 | /* |
1746 | * Check ->nrbufs without the inode lock first. This function |
1747 | * is speculative anyways, so missing one is ok. |
1748 | */ |
1749 | if (pipe->nrbufs) |
1750 | return 0; |
1751 | |
1752 | ret = 0; |
1753 | pipe_lock(pipe); |
1754 | |
1755 | while (!pipe->nrbufs) { |
1756 | if (signal_pending(current)) { |
1757 | ret = -ERESTARTSYS; |
1758 | break; |
1759 | } |
1760 | if (!pipe->writers) |
1761 | break; |
1762 | if (!pipe->waiting_writers) { |
1763 | if (flags & SPLICE_F_NONBLOCK) { |
1764 | ret = -EAGAIN; |
1765 | break; |
1766 | } |
1767 | } |
1768 | pipe_wait(pipe); |
1769 | } |
1770 | |
1771 | pipe_unlock(pipe); |
1772 | return ret; |
1773 | } |
1774 | |
1775 | /* |
1776 | * Make sure there's writeable room. Wait for room if we can, otherwise |
1777 | * return an appropriate error. |
1778 | */ |
1779 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1780 | { |
1781 | int ret; |
1782 | |
1783 | /* |
1784 | * Check ->nrbufs without the inode lock first. This function |
1785 | * is speculative anyways, so missing one is ok. |
1786 | */ |
1787 | if (pipe->nrbufs < pipe->buffers) |
1788 | return 0; |
1789 | |
1790 | ret = 0; |
1791 | pipe_lock(pipe); |
1792 | |
1793 | while (pipe->nrbufs >= pipe->buffers) { |
1794 | if (!pipe->readers) { |
1795 | send_sig(SIGPIPE, current, 0); |
1796 | ret = -EPIPE; |
1797 | break; |
1798 | } |
1799 | if (flags & SPLICE_F_NONBLOCK) { |
1800 | ret = -EAGAIN; |
1801 | break; |
1802 | } |
1803 | if (signal_pending(current)) { |
1804 | ret = -ERESTARTSYS; |
1805 | break; |
1806 | } |
1807 | pipe->waiting_writers++; |
1808 | pipe_wait(pipe); |
1809 | pipe->waiting_writers--; |
1810 | } |
1811 | |
1812 | pipe_unlock(pipe); |
1813 | return ret; |
1814 | } |
1815 | |
1816 | /* |
1817 | * Splice contents of ipipe to opipe. |
1818 | */ |
1819 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1820 | struct pipe_inode_info *opipe, |
1821 | size_t len, unsigned int flags) |
1822 | { |
1823 | struct pipe_buffer *ibuf, *obuf; |
1824 | int ret = 0, nbuf; |
1825 | bool input_wakeup = false; |
1826 | |
1827 | |
1828 | retry: |
1829 | ret = ipipe_prep(ipipe, flags); |
1830 | if (ret) |
1831 | return ret; |
1832 | |
1833 | ret = opipe_prep(opipe, flags); |
1834 | if (ret) |
1835 | return ret; |
1836 | |
1837 | /* |
1838 | * Potential ABBA deadlock, work around it by ordering lock |
1839 | * grabbing by pipe info address. Otherwise two different processes |
1840 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1841 | */ |
1842 | pipe_double_lock(ipipe, opipe); |
1843 | |
1844 | do { |
1845 | if (!opipe->readers) { |
1846 | send_sig(SIGPIPE, current, 0); |
1847 | if (!ret) |
1848 | ret = -EPIPE; |
1849 | break; |
1850 | } |
1851 | |
1852 | if (!ipipe->nrbufs && !ipipe->writers) |
1853 | break; |
1854 | |
1855 | /* |
1856 | * Cannot make any progress, because either the input |
1857 | * pipe is empty or the output pipe is full. |
1858 | */ |
1859 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
1860 | /* Already processed some buffers, break */ |
1861 | if (ret) |
1862 | break; |
1863 | |
1864 | if (flags & SPLICE_F_NONBLOCK) { |
1865 | ret = -EAGAIN; |
1866 | break; |
1867 | } |
1868 | |
1869 | /* |
1870 | * We raced with another reader/writer and haven't |
1871 | * managed to process any buffers. A zero return |
1872 | * value means EOF, so retry instead. |
1873 | */ |
1874 | pipe_unlock(ipipe); |
1875 | pipe_unlock(opipe); |
1876 | goto retry; |
1877 | } |
1878 | |
1879 | ibuf = ipipe->bufs + ipipe->curbuf; |
1880 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1881 | obuf = opipe->bufs + nbuf; |
1882 | |
1883 | if (len >= ibuf->len) { |
1884 | /* |
1885 | * Simply move the whole buffer from ipipe to opipe |
1886 | */ |
1887 | *obuf = *ibuf; |
1888 | ibuf->ops = NULL; |
1889 | opipe->nrbufs++; |
1890 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
1891 | ipipe->nrbufs--; |
1892 | input_wakeup = true; |
1893 | } else { |
1894 | /* |
1895 | * Get a reference to this pipe buffer, |
1896 | * so we can copy the contents over. |
1897 | */ |
1898 | ibuf->ops->get(ipipe, ibuf); |
1899 | *obuf = *ibuf; |
1900 | |
1901 | /* |
1902 | * Don't inherit the gift flag, we need to |
1903 | * prevent multiple steals of this page. |
1904 | */ |
1905 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1906 | |
1907 | obuf->len = len; |
1908 | opipe->nrbufs++; |
1909 | ibuf->offset += obuf->len; |
1910 | ibuf->len -= obuf->len; |
1911 | } |
1912 | ret += obuf->len; |
1913 | len -= obuf->len; |
1914 | } while (len); |
1915 | |
1916 | pipe_unlock(ipipe); |
1917 | pipe_unlock(opipe); |
1918 | |
1919 | /* |
1920 | * If we put data in the output pipe, wakeup any potential readers. |
1921 | */ |
1922 | if (ret > 0) { |
1923 | smp_mb(); |
1924 | if (waitqueue_active(&opipe->wait)) |
1925 | wake_up_interruptible(&opipe->wait); |
1926 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); |
1927 | } |
1928 | if (input_wakeup) |
1929 | wakeup_pipe_writers(ipipe); |
1930 | |
1931 | return ret; |
1932 | } |
1933 | |
1934 | /* |
1935 | * Link contents of ipipe to opipe. |
1936 | */ |
1937 | static int link_pipe(struct pipe_inode_info *ipipe, |
1938 | struct pipe_inode_info *opipe, |
1939 | size_t len, unsigned int flags) |
1940 | { |
1941 | struct pipe_buffer *ibuf, *obuf; |
1942 | int ret = 0, i = 0, nbuf; |
1943 | |
1944 | /* |
1945 | * Potential ABBA deadlock, work around it by ordering lock |
1946 | * grabbing by pipe info address. Otherwise two different processes |
1947 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1948 | */ |
1949 | pipe_double_lock(ipipe, opipe); |
1950 | |
1951 | do { |
1952 | if (!opipe->readers) { |
1953 | send_sig(SIGPIPE, current, 0); |
1954 | if (!ret) |
1955 | ret = -EPIPE; |
1956 | break; |
1957 | } |
1958 | |
1959 | /* |
1960 | * If we have iterated all input buffers or ran out of |
1961 | * output room, break. |
1962 | */ |
1963 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
1964 | break; |
1965 | |
1966 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
1967 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1968 | |
1969 | /* |
1970 | * Get a reference to this pipe buffer, |
1971 | * so we can copy the contents over. |
1972 | */ |
1973 | ibuf->ops->get(ipipe, ibuf); |
1974 | |
1975 | obuf = opipe->bufs + nbuf; |
1976 | *obuf = *ibuf; |
1977 | |
1978 | /* |
1979 | * Don't inherit the gift flag, we need to |
1980 | * prevent multiple steals of this page. |
1981 | */ |
1982 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1983 | |
1984 | if (obuf->len > len) |
1985 | obuf->len = len; |
1986 | |
1987 | opipe->nrbufs++; |
1988 | ret += obuf->len; |
1989 | len -= obuf->len; |
1990 | i++; |
1991 | } while (len); |
1992 | |
1993 | /* |
1994 | * return EAGAIN if we have the potential of some data in the |
1995 | * future, otherwise just return 0 |
1996 | */ |
1997 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) |
1998 | ret = -EAGAIN; |
1999 | |
2000 | pipe_unlock(ipipe); |
2001 | pipe_unlock(opipe); |
2002 | |
2003 | /* |
2004 | * If we put data in the output pipe, wakeup any potential readers. |
2005 | */ |
2006 | if (ret > 0) { |
2007 | smp_mb(); |
2008 | if (waitqueue_active(&opipe->wait)) |
2009 | wake_up_interruptible(&opipe->wait); |
2010 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); |
2011 | } |
2012 | |
2013 | return ret; |
2014 | } |
2015 | |
2016 | /* |
2017 | * This is a tee(1) implementation that works on pipes. It doesn't copy |
2018 | * any data, it simply references the 'in' pages on the 'out' pipe. |
2019 | * The 'flags' used are the SPLICE_F_* variants, currently the only |
2020 | * applicable one is SPLICE_F_NONBLOCK. |
2021 | */ |
2022 | static long do_tee(struct file *in, struct file *out, size_t len, |
2023 | unsigned int flags) |
2024 | { |
2025 | struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode); |
2026 | struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode); |
2027 | int ret = -EINVAL; |
2028 | |
2029 | /* |
2030 | * Duplicate the contents of ipipe to opipe without actually |
2031 | * copying the data. |
2032 | */ |
2033 | if (ipipe && opipe && ipipe != opipe) { |
2034 | /* |
2035 | * Keep going, unless we encounter an error. The ipipe/opipe |
2036 | * ordering doesn't really matter. |
2037 | */ |
2038 | ret = ipipe_prep(ipipe, flags); |
2039 | if (!ret) { |
2040 | ret = opipe_prep(opipe, flags); |
2041 | if (!ret) |
2042 | ret = link_pipe(ipipe, opipe, len, flags); |
2043 | } |
2044 | } |
2045 | |
2046 | return ret; |
2047 | } |
2048 | |
2049 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
2050 | { |
2051 | struct file *in; |
2052 | int error, fput_in; |
2053 | |
2054 | if (unlikely(!len)) |
2055 | return 0; |
2056 | |
2057 | error = -EBADF; |
2058 | in = fget_light(fdin, &fput_in); |
2059 | if (in) { |
2060 | if (in->f_mode & FMODE_READ) { |
2061 | int fput_out; |
2062 | struct file *out = fget_light(fdout, &fput_out); |
2063 | |
2064 | if (out) { |
2065 | if (out->f_mode & FMODE_WRITE) |
2066 | error = do_tee(in, out, len, flags); |
2067 | fput_light(out, fput_out); |
2068 | } |
2069 | } |
2070 | fput_light(in, fput_in); |
2071 | } |
2072 | |
2073 | return error; |
2074 | } |
2075 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
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v3.9