Root/
1 | /* |
2 | * "splice": joining two ropes together by interweaving their strands. |
3 | * |
4 | * This is the "extended pipe" functionality, where a pipe is used as |
5 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel |
6 | * buffer that you can use to transfer data from one end to the other. |
7 | * |
8 | * The traditional unix read/write is extended with a "splice()" operation |
9 | * that transfers data buffers to or from a pipe buffer. |
10 | * |
11 | * Named by Larry McVoy, original implementation from Linus, extended by |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. |
14 | * |
15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> |
18 | * |
19 | */ |
20 | #include <linux/fs.h> |
21 | #include <linux/file.h> |
22 | #include <linux/pagemap.h> |
23 | #include <linux/splice.h> |
24 | #include <linux/memcontrol.h> |
25 | #include <linux/mm_inline.h> |
26 | #include <linux/swap.h> |
27 | #include <linux/writeback.h> |
28 | #include <linux/export.h> |
29 | #include <linux/syscalls.h> |
30 | #include <linux/uio.h> |
31 | #include <linux/security.h> |
32 | #include <linux/gfp.h> |
33 | #include <linux/socket.h> |
34 | #include <linux/compat.h> |
35 | #include "internal.h" |
36 | |
37 | /* |
38 | * Attempt to steal a page from a pipe buffer. This should perhaps go into |
39 | * a vm helper function, it's already simplified quite a bit by the |
40 | * addition of remove_mapping(). If success is returned, the caller may |
41 | * attempt to reuse this page for another destination. |
42 | */ |
43 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
44 | struct pipe_buffer *buf) |
45 | { |
46 | struct page *page = buf->page; |
47 | struct address_space *mapping; |
48 | |
49 | lock_page(page); |
50 | |
51 | mapping = page_mapping(page); |
52 | if (mapping) { |
53 | WARN_ON(!PageUptodate(page)); |
54 | |
55 | /* |
56 | * At least for ext2 with nobh option, we need to wait on |
57 | * writeback completing on this page, since we'll remove it |
58 | * from the pagecache. Otherwise truncate wont wait on the |
59 | * page, allowing the disk blocks to be reused by someone else |
60 | * before we actually wrote our data to them. fs corruption |
61 | * ensues. |
62 | */ |
63 | wait_on_page_writeback(page); |
64 | |
65 | if (page_has_private(page) && |
66 | !try_to_release_page(page, GFP_KERNEL)) |
67 | goto out_unlock; |
68 | |
69 | /* |
70 | * If we succeeded in removing the mapping, set LRU flag |
71 | * and return good. |
72 | */ |
73 | if (remove_mapping(mapping, page)) { |
74 | buf->flags |= PIPE_BUF_FLAG_LRU; |
75 | return 0; |
76 | } |
77 | } |
78 | |
79 | /* |
80 | * Raced with truncate or failed to remove page from current |
81 | * address space, unlock and return failure. |
82 | */ |
83 | out_unlock: |
84 | unlock_page(page); |
85 | return 1; |
86 | } |
87 | |
88 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
89 | struct pipe_buffer *buf) |
90 | { |
91 | page_cache_release(buf->page); |
92 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
93 | } |
94 | |
95 | /* |
96 | * Check whether the contents of buf is OK to access. Since the content |
97 | * is a page cache page, IO may be in flight. |
98 | */ |
99 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
100 | struct pipe_buffer *buf) |
101 | { |
102 | struct page *page = buf->page; |
103 | int err; |
104 | |
105 | if (!PageUptodate(page)) { |
106 | lock_page(page); |
107 | |
108 | /* |
109 | * Page got truncated/unhashed. This will cause a 0-byte |
110 | * splice, if this is the first page. |
111 | */ |
112 | if (!page->mapping) { |
113 | err = -ENODATA; |
114 | goto error; |
115 | } |
116 | |
117 | /* |
118 | * Uh oh, read-error from disk. |
119 | */ |
120 | if (!PageUptodate(page)) { |
121 | err = -EIO; |
122 | goto error; |
123 | } |
124 | |
125 | /* |
126 | * Page is ok afterall, we are done. |
127 | */ |
128 | unlock_page(page); |
129 | } |
130 | |
131 | return 0; |
132 | error: |
133 | unlock_page(page); |
134 | return err; |
135 | } |
136 | |
137 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
138 | .can_merge = 0, |
139 | .map = generic_pipe_buf_map, |
140 | .unmap = generic_pipe_buf_unmap, |
141 | .confirm = page_cache_pipe_buf_confirm, |
142 | .release = page_cache_pipe_buf_release, |
143 | .steal = page_cache_pipe_buf_steal, |
144 | .get = generic_pipe_buf_get, |
145 | }; |
146 | |
147 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
148 | struct pipe_buffer *buf) |
149 | { |
150 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
151 | return 1; |
152 | |
153 | buf->flags |= PIPE_BUF_FLAG_LRU; |
154 | return generic_pipe_buf_steal(pipe, buf); |
155 | } |
156 | |
157 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
158 | .can_merge = 0, |
159 | .map = generic_pipe_buf_map, |
160 | .unmap = generic_pipe_buf_unmap, |
161 | .confirm = generic_pipe_buf_confirm, |
162 | .release = page_cache_pipe_buf_release, |
163 | .steal = user_page_pipe_buf_steal, |
164 | .get = generic_pipe_buf_get, |
165 | }; |
166 | |
167 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
168 | { |
169 | smp_mb(); |
170 | if (waitqueue_active(&pipe->wait)) |
171 | wake_up_interruptible(&pipe->wait); |
172 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
173 | } |
174 | |
175 | /** |
176 | * splice_to_pipe - fill passed data into a pipe |
177 | * @pipe: pipe to fill |
178 | * @spd: data to fill |
179 | * |
180 | * Description: |
181 | * @spd contains a map of pages and len/offset tuples, along with |
182 | * the struct pipe_buf_operations associated with these pages. This |
183 | * function will link that data to the pipe. |
184 | * |
185 | */ |
186 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
187 | struct splice_pipe_desc *spd) |
188 | { |
189 | unsigned int spd_pages = spd->nr_pages; |
190 | int ret, do_wakeup, page_nr; |
191 | |
192 | ret = 0; |
193 | do_wakeup = 0; |
194 | page_nr = 0; |
195 | |
196 | pipe_lock(pipe); |
197 | |
198 | for (;;) { |
199 | if (!pipe->readers) { |
200 | send_sig(SIGPIPE, current, 0); |
201 | if (!ret) |
202 | ret = -EPIPE; |
203 | break; |
204 | } |
205 | |
206 | if (pipe->nrbufs < pipe->buffers) { |
207 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); |
208 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
209 | |
210 | buf->page = spd->pages[page_nr]; |
211 | buf->offset = spd->partial[page_nr].offset; |
212 | buf->len = spd->partial[page_nr].len; |
213 | buf->private = spd->partial[page_nr].private; |
214 | buf->ops = spd->ops; |
215 | if (spd->flags & SPLICE_F_GIFT) |
216 | buf->flags |= PIPE_BUF_FLAG_GIFT; |
217 | |
218 | pipe->nrbufs++; |
219 | page_nr++; |
220 | ret += buf->len; |
221 | |
222 | if (pipe->files) |
223 | do_wakeup = 1; |
224 | |
225 | if (!--spd->nr_pages) |
226 | break; |
227 | if (pipe->nrbufs < pipe->buffers) |
228 | continue; |
229 | |
230 | break; |
231 | } |
232 | |
233 | if (spd->flags & SPLICE_F_NONBLOCK) { |
234 | if (!ret) |
235 | ret = -EAGAIN; |
236 | break; |
237 | } |
238 | |
239 | if (signal_pending(current)) { |
240 | if (!ret) |
241 | ret = -ERESTARTSYS; |
242 | break; |
243 | } |
244 | |
245 | if (do_wakeup) { |
246 | smp_mb(); |
247 | if (waitqueue_active(&pipe->wait)) |
248 | wake_up_interruptible_sync(&pipe->wait); |
249 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
250 | do_wakeup = 0; |
251 | } |
252 | |
253 | pipe->waiting_writers++; |
254 | pipe_wait(pipe); |
255 | pipe->waiting_writers--; |
256 | } |
257 | |
258 | pipe_unlock(pipe); |
259 | |
260 | if (do_wakeup) |
261 | wakeup_pipe_readers(pipe); |
262 | |
263 | while (page_nr < spd_pages) |
264 | spd->spd_release(spd, page_nr++); |
265 | |
266 | return ret; |
267 | } |
268 | |
269 | void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
270 | { |
271 | page_cache_release(spd->pages[i]); |
272 | } |
273 | |
274 | /* |
275 | * Check if we need to grow the arrays holding pages and partial page |
276 | * descriptions. |
277 | */ |
278 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
279 | { |
280 | unsigned int buffers = ACCESS_ONCE(pipe->buffers); |
281 | |
282 | spd->nr_pages_max = buffers; |
283 | if (buffers <= PIPE_DEF_BUFFERS) |
284 | return 0; |
285 | |
286 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); |
287 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); |
288 | |
289 | if (spd->pages && spd->partial) |
290 | return 0; |
291 | |
292 | kfree(spd->pages); |
293 | kfree(spd->partial); |
294 | return -ENOMEM; |
295 | } |
296 | |
297 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
298 | { |
299 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
300 | return; |
301 | |
302 | kfree(spd->pages); |
303 | kfree(spd->partial); |
304 | } |
305 | |
306 | static int |
307 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
308 | struct pipe_inode_info *pipe, size_t len, |
309 | unsigned int flags) |
310 | { |
311 | struct address_space *mapping = in->f_mapping; |
312 | unsigned int loff, nr_pages, req_pages; |
313 | struct page *pages[PIPE_DEF_BUFFERS]; |
314 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
315 | struct page *page; |
316 | pgoff_t index, end_index; |
317 | loff_t isize; |
318 | int error, page_nr; |
319 | struct splice_pipe_desc spd = { |
320 | .pages = pages, |
321 | .partial = partial, |
322 | .nr_pages_max = PIPE_DEF_BUFFERS, |
323 | .flags = flags, |
324 | .ops = &page_cache_pipe_buf_ops, |
325 | .spd_release = spd_release_page, |
326 | }; |
327 | |
328 | if (splice_grow_spd(pipe, &spd)) |
329 | return -ENOMEM; |
330 | |
331 | index = *ppos >> PAGE_CACHE_SHIFT; |
332 | loff = *ppos & ~PAGE_CACHE_MASK; |
333 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
334 | nr_pages = min(req_pages, spd.nr_pages_max); |
335 | |
336 | /* |
337 | * Lookup the (hopefully) full range of pages we need. |
338 | */ |
339 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); |
340 | index += spd.nr_pages; |
341 | |
342 | /* |
343 | * If find_get_pages_contig() returned fewer pages than we needed, |
344 | * readahead/allocate the rest and fill in the holes. |
345 | */ |
346 | if (spd.nr_pages < nr_pages) |
347 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
348 | index, req_pages - spd.nr_pages); |
349 | |
350 | error = 0; |
351 | while (spd.nr_pages < nr_pages) { |
352 | /* |
353 | * Page could be there, find_get_pages_contig() breaks on |
354 | * the first hole. |
355 | */ |
356 | page = find_get_page(mapping, index); |
357 | if (!page) { |
358 | /* |
359 | * page didn't exist, allocate one. |
360 | */ |
361 | page = page_cache_alloc_cold(mapping); |
362 | if (!page) |
363 | break; |
364 | |
365 | error = add_to_page_cache_lru(page, mapping, index, |
366 | GFP_KERNEL); |
367 | if (unlikely(error)) { |
368 | page_cache_release(page); |
369 | if (error == -EEXIST) |
370 | continue; |
371 | break; |
372 | } |
373 | /* |
374 | * add_to_page_cache() locks the page, unlock it |
375 | * to avoid convoluting the logic below even more. |
376 | */ |
377 | unlock_page(page); |
378 | } |
379 | |
380 | spd.pages[spd.nr_pages++] = page; |
381 | index++; |
382 | } |
383 | |
384 | /* |
385 | * Now loop over the map and see if we need to start IO on any |
386 | * pages, fill in the partial map, etc. |
387 | */ |
388 | index = *ppos >> PAGE_CACHE_SHIFT; |
389 | nr_pages = spd.nr_pages; |
390 | spd.nr_pages = 0; |
391 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
392 | unsigned int this_len; |
393 | |
394 | if (!len) |
395 | break; |
396 | |
397 | /* |
398 | * this_len is the max we'll use from this page |
399 | */ |
400 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
401 | page = spd.pages[page_nr]; |
402 | |
403 | if (PageReadahead(page)) |
404 | page_cache_async_readahead(mapping, &in->f_ra, in, |
405 | page, index, req_pages - page_nr); |
406 | |
407 | /* |
408 | * If the page isn't uptodate, we may need to start io on it |
409 | */ |
410 | if (!PageUptodate(page)) { |
411 | lock_page(page); |
412 | |
413 | /* |
414 | * Page was truncated, or invalidated by the |
415 | * filesystem. Redo the find/create, but this time the |
416 | * page is kept locked, so there's no chance of another |
417 | * race with truncate/invalidate. |
418 | */ |
419 | if (!page->mapping) { |
420 | unlock_page(page); |
421 | page = find_or_create_page(mapping, index, |
422 | mapping_gfp_mask(mapping)); |
423 | |
424 | if (!page) { |
425 | error = -ENOMEM; |
426 | break; |
427 | } |
428 | page_cache_release(spd.pages[page_nr]); |
429 | spd.pages[page_nr] = page; |
430 | } |
431 | /* |
432 | * page was already under io and is now done, great |
433 | */ |
434 | if (PageUptodate(page)) { |
435 | unlock_page(page); |
436 | goto fill_it; |
437 | } |
438 | |
439 | /* |
440 | * need to read in the page |
441 | */ |
442 | error = mapping->a_ops->readpage(in, page); |
443 | if (unlikely(error)) { |
444 | /* |
445 | * We really should re-lookup the page here, |
446 | * but it complicates things a lot. Instead |
447 | * lets just do what we already stored, and |
448 | * we'll get it the next time we are called. |
449 | */ |
450 | if (error == AOP_TRUNCATED_PAGE) |
451 | error = 0; |
452 | |
453 | break; |
454 | } |
455 | } |
456 | fill_it: |
457 | /* |
458 | * i_size must be checked after PageUptodate. |
459 | */ |
460 | isize = i_size_read(mapping->host); |
461 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
462 | if (unlikely(!isize || index > end_index)) |
463 | break; |
464 | |
465 | /* |
466 | * if this is the last page, see if we need to shrink |
467 | * the length and stop |
468 | */ |
469 | if (end_index == index) { |
470 | unsigned int plen; |
471 | |
472 | /* |
473 | * max good bytes in this page |
474 | */ |
475 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
476 | if (plen <= loff) |
477 | break; |
478 | |
479 | /* |
480 | * force quit after adding this page |
481 | */ |
482 | this_len = min(this_len, plen - loff); |
483 | len = this_len; |
484 | } |
485 | |
486 | spd.partial[page_nr].offset = loff; |
487 | spd.partial[page_nr].len = this_len; |
488 | len -= this_len; |
489 | loff = 0; |
490 | spd.nr_pages++; |
491 | index++; |
492 | } |
493 | |
494 | /* |
495 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
496 | * we got, 'nr_pages' is how many pages are in the map. |
497 | */ |
498 | while (page_nr < nr_pages) |
499 | page_cache_release(spd.pages[page_nr++]); |
500 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
501 | |
502 | if (spd.nr_pages) |
503 | error = splice_to_pipe(pipe, &spd); |
504 | |
505 | splice_shrink_spd(&spd); |
506 | return error; |
507 | } |
508 | |
509 | /** |
510 | * generic_file_splice_read - splice data from file to a pipe |
511 | * @in: file to splice from |
512 | * @ppos: position in @in |
513 | * @pipe: pipe to splice to |
514 | * @len: number of bytes to splice |
515 | * @flags: splice modifier flags |
516 | * |
517 | * Description: |
518 | * Will read pages from given file and fill them into a pipe. Can be |
519 | * used as long as the address_space operations for the source implements |
520 | * a readpage() hook. |
521 | * |
522 | */ |
523 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
524 | struct pipe_inode_info *pipe, size_t len, |
525 | unsigned int flags) |
526 | { |
527 | loff_t isize, left; |
528 | int ret; |
529 | |
530 | isize = i_size_read(in->f_mapping->host); |
531 | if (unlikely(*ppos >= isize)) |
532 | return 0; |
533 | |
534 | left = isize - *ppos; |
535 | if (unlikely(left < len)) |
536 | len = left; |
537 | |
538 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
539 | if (ret > 0) { |
540 | *ppos += ret; |
541 | file_accessed(in); |
542 | } |
543 | |
544 | return ret; |
545 | } |
546 | EXPORT_SYMBOL(generic_file_splice_read); |
547 | |
548 | static const struct pipe_buf_operations default_pipe_buf_ops = { |
549 | .can_merge = 0, |
550 | .map = generic_pipe_buf_map, |
551 | .unmap = generic_pipe_buf_unmap, |
552 | .confirm = generic_pipe_buf_confirm, |
553 | .release = generic_pipe_buf_release, |
554 | .steal = generic_pipe_buf_steal, |
555 | .get = generic_pipe_buf_get, |
556 | }; |
557 | |
558 | static ssize_t kernel_readv(struct file *file, const struct iovec *vec, |
559 | unsigned long vlen, loff_t offset) |
560 | { |
561 | mm_segment_t old_fs; |
562 | loff_t pos = offset; |
563 | ssize_t res; |
564 | |
565 | old_fs = get_fs(); |
566 | set_fs(get_ds()); |
567 | /* The cast to a user pointer is valid due to the set_fs() */ |
568 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos); |
569 | set_fs(old_fs); |
570 | |
571 | return res; |
572 | } |
573 | |
574 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
575 | loff_t pos) |
576 | { |
577 | mm_segment_t old_fs; |
578 | ssize_t res; |
579 | |
580 | old_fs = get_fs(); |
581 | set_fs(get_ds()); |
582 | /* The cast to a user pointer is valid due to the set_fs() */ |
583 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); |
584 | set_fs(old_fs); |
585 | |
586 | return res; |
587 | } |
588 | EXPORT_SYMBOL(kernel_write); |
589 | |
590 | ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
591 | struct pipe_inode_info *pipe, size_t len, |
592 | unsigned int flags) |
593 | { |
594 | unsigned int nr_pages; |
595 | unsigned int nr_freed; |
596 | size_t offset; |
597 | struct page *pages[PIPE_DEF_BUFFERS]; |
598 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
599 | struct iovec *vec, __vec[PIPE_DEF_BUFFERS]; |
600 | ssize_t res; |
601 | size_t this_len; |
602 | int error; |
603 | int i; |
604 | struct splice_pipe_desc spd = { |
605 | .pages = pages, |
606 | .partial = partial, |
607 | .nr_pages_max = PIPE_DEF_BUFFERS, |
608 | .flags = flags, |
609 | .ops = &default_pipe_buf_ops, |
610 | .spd_release = spd_release_page, |
611 | }; |
612 | |
613 | if (splice_grow_spd(pipe, &spd)) |
614 | return -ENOMEM; |
615 | |
616 | res = -ENOMEM; |
617 | vec = __vec; |
618 | if (spd.nr_pages_max > PIPE_DEF_BUFFERS) { |
619 | vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL); |
620 | if (!vec) |
621 | goto shrink_ret; |
622 | } |
623 | |
624 | offset = *ppos & ~PAGE_CACHE_MASK; |
625 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
626 | |
627 | for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) { |
628 | struct page *page; |
629 | |
630 | page = alloc_page(GFP_USER); |
631 | error = -ENOMEM; |
632 | if (!page) |
633 | goto err; |
634 | |
635 | this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); |
636 | vec[i].iov_base = (void __user *) page_address(page); |
637 | vec[i].iov_len = this_len; |
638 | spd.pages[i] = page; |
639 | spd.nr_pages++; |
640 | len -= this_len; |
641 | offset = 0; |
642 | } |
643 | |
644 | res = kernel_readv(in, vec, spd.nr_pages, *ppos); |
645 | if (res < 0) { |
646 | error = res; |
647 | goto err; |
648 | } |
649 | |
650 | error = 0; |
651 | if (!res) |
652 | goto err; |
653 | |
654 | nr_freed = 0; |
655 | for (i = 0; i < spd.nr_pages; i++) { |
656 | this_len = min_t(size_t, vec[i].iov_len, res); |
657 | spd.partial[i].offset = 0; |
658 | spd.partial[i].len = this_len; |
659 | if (!this_len) { |
660 | __free_page(spd.pages[i]); |
661 | spd.pages[i] = NULL; |
662 | nr_freed++; |
663 | } |
664 | res -= this_len; |
665 | } |
666 | spd.nr_pages -= nr_freed; |
667 | |
668 | res = splice_to_pipe(pipe, &spd); |
669 | if (res > 0) |
670 | *ppos += res; |
671 | |
672 | shrink_ret: |
673 | if (vec != __vec) |
674 | kfree(vec); |
675 | splice_shrink_spd(&spd); |
676 | return res; |
677 | |
678 | err: |
679 | for (i = 0; i < spd.nr_pages; i++) |
680 | __free_page(spd.pages[i]); |
681 | |
682 | res = error; |
683 | goto shrink_ret; |
684 | } |
685 | EXPORT_SYMBOL(default_file_splice_read); |
686 | |
687 | /* |
688 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
689 | * using sendpage(). Return the number of bytes sent. |
690 | */ |
691 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
692 | struct pipe_buffer *buf, struct splice_desc *sd) |
693 | { |
694 | struct file *file = sd->u.file; |
695 | loff_t pos = sd->pos; |
696 | int more; |
697 | |
698 | if (!likely(file->f_op && file->f_op->sendpage)) |
699 | return -EINVAL; |
700 | |
701 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
702 | |
703 | if (sd->len < sd->total_len && pipe->nrbufs > 1) |
704 | more |= MSG_SENDPAGE_NOTLAST; |
705 | |
706 | return file->f_op->sendpage(file, buf->page, buf->offset, |
707 | sd->len, &pos, more); |
708 | } |
709 | |
710 | /* |
711 | * This is a little more tricky than the file -> pipe splicing. There are |
712 | * basically three cases: |
713 | * |
714 | * - Destination page already exists in the address space and there |
715 | * are users of it. For that case we have no other option that |
716 | * copying the data. Tough luck. |
717 | * - Destination page already exists in the address space, but there |
718 | * are no users of it. Make sure it's uptodate, then drop it. Fall |
719 | * through to last case. |
720 | * - Destination page does not exist, we can add the pipe page to |
721 | * the page cache and avoid the copy. |
722 | * |
723 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
724 | * sd->flags), we attempt to migrate pages from the pipe to the output |
725 | * file address space page cache. This is possible if no one else has |
726 | * the pipe page referenced outside of the pipe and page cache. If |
727 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create |
728 | * a new page in the output file page cache and fill/dirty that. |
729 | */ |
730 | int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
731 | struct splice_desc *sd) |
732 | { |
733 | struct file *file = sd->u.file; |
734 | struct address_space *mapping = file->f_mapping; |
735 | unsigned int offset, this_len; |
736 | struct page *page; |
737 | void *fsdata; |
738 | int ret; |
739 | |
740 | offset = sd->pos & ~PAGE_CACHE_MASK; |
741 | |
742 | this_len = sd->len; |
743 | if (this_len + offset > PAGE_CACHE_SIZE) |
744 | this_len = PAGE_CACHE_SIZE - offset; |
745 | |
746 | ret = pagecache_write_begin(file, mapping, sd->pos, this_len, |
747 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); |
748 | if (unlikely(ret)) |
749 | goto out; |
750 | |
751 | if (buf->page != page) { |
752 | char *src = buf->ops->map(pipe, buf, 1); |
753 | char *dst = kmap_atomic(page); |
754 | |
755 | memcpy(dst + offset, src + buf->offset, this_len); |
756 | flush_dcache_page(page); |
757 | kunmap_atomic(dst); |
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 = buf->ops->confirm(pipe, buf); |
809 | if (unlikely(ret)) { |
810 | if (ret == -ENODATA) |
811 | ret = 0; |
812 | return ret; |
813 | } |
814 | |
815 | ret = actor(pipe, buf, sd); |
816 | if (ret <= 0) |
817 | return ret; |
818 | |
819 | buf->offset += ret; |
820 | buf->len -= ret; |
821 | |
822 | sd->num_spliced += ret; |
823 | sd->len -= ret; |
824 | sd->pos += ret; |
825 | sd->total_len -= ret; |
826 | |
827 | if (!buf->len) { |
828 | buf->ops = NULL; |
829 | ops->release(pipe, buf); |
830 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
831 | pipe->nrbufs--; |
832 | if (pipe->files) |
833 | sd->need_wakeup = true; |
834 | } |
835 | |
836 | if (!sd->total_len) |
837 | return 0; |
838 | } |
839 | |
840 | return 1; |
841 | } |
842 | EXPORT_SYMBOL(splice_from_pipe_feed); |
843 | |
844 | /** |
845 | * splice_from_pipe_next - wait for some data to splice from |
846 | * @pipe: pipe to splice from |
847 | * @sd: information about the splice operation |
848 | * |
849 | * Description: |
850 | * This function will wait for some data and return a positive |
851 | * value (one) if pipe buffers are available. It will return zero |
852 | * or -errno if no more data needs to be spliced. |
853 | */ |
854 | int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
855 | { |
856 | while (!pipe->nrbufs) { |
857 | if (!pipe->writers) |
858 | return 0; |
859 | |
860 | if (!pipe->waiting_writers && sd->num_spliced) |
861 | return 0; |
862 | |
863 | if (sd->flags & SPLICE_F_NONBLOCK) |
864 | return -EAGAIN; |
865 | |
866 | if (signal_pending(current)) |
867 | return -ERESTARTSYS; |
868 | |
869 | if (sd->need_wakeup) { |
870 | wakeup_pipe_writers(pipe); |
871 | sd->need_wakeup = false; |
872 | } |
873 | |
874 | pipe_wait(pipe); |
875 | } |
876 | |
877 | return 1; |
878 | } |
879 | EXPORT_SYMBOL(splice_from_pipe_next); |
880 | |
881 | /** |
882 | * splice_from_pipe_begin - start splicing from pipe |
883 | * @sd: information about the splice operation |
884 | * |
885 | * Description: |
886 | * This function should be called before a loop containing |
887 | * splice_from_pipe_next() and splice_from_pipe_feed() to |
888 | * initialize the necessary fields of @sd. |
889 | */ |
890 | void splice_from_pipe_begin(struct splice_desc *sd) |
891 | { |
892 | sd->num_spliced = 0; |
893 | sd->need_wakeup = false; |
894 | } |
895 | EXPORT_SYMBOL(splice_from_pipe_begin); |
896 | |
897 | /** |
898 | * splice_from_pipe_end - finish splicing from pipe |
899 | * @pipe: pipe to splice from |
900 | * @sd: information about the splice operation |
901 | * |
902 | * Description: |
903 | * This function will wake up pipe writers if necessary. It should |
904 | * be called after a loop containing splice_from_pipe_next() and |
905 | * splice_from_pipe_feed(). |
906 | */ |
907 | void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
908 | { |
909 | if (sd->need_wakeup) |
910 | wakeup_pipe_writers(pipe); |
911 | } |
912 | EXPORT_SYMBOL(splice_from_pipe_end); |
913 | |
914 | /** |
915 | * __splice_from_pipe - splice data from a pipe to given actor |
916 | * @pipe: pipe to splice from |
917 | * @sd: information to @actor |
918 | * @actor: handler that splices the data |
919 | * |
920 | * Description: |
921 | * This function does little more than loop over the pipe and call |
922 | * @actor to do the actual moving of a single struct pipe_buffer to |
923 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or |
924 | * pipe_to_user. |
925 | * |
926 | */ |
927 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
928 | splice_actor *actor) |
929 | { |
930 | int ret; |
931 | |
932 | splice_from_pipe_begin(sd); |
933 | do { |
934 | ret = splice_from_pipe_next(pipe, sd); |
935 | if (ret > 0) |
936 | ret = splice_from_pipe_feed(pipe, sd, actor); |
937 | } while (ret > 0); |
938 | splice_from_pipe_end(pipe, sd); |
939 | |
940 | return sd->num_spliced ? sd->num_spliced : ret; |
941 | } |
942 | EXPORT_SYMBOL(__splice_from_pipe); |
943 | |
944 | /** |
945 | * splice_from_pipe - splice data from a pipe to a file |
946 | * @pipe: pipe to splice from |
947 | * @out: file to splice to |
948 | * @ppos: position in @out |
949 | * @len: how many bytes to splice |
950 | * @flags: splice modifier flags |
951 | * @actor: handler that splices the data |
952 | * |
953 | * Description: |
954 | * See __splice_from_pipe. This function locks the pipe inode, |
955 | * otherwise it's identical to __splice_from_pipe(). |
956 | * |
957 | */ |
958 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
959 | loff_t *ppos, size_t len, unsigned int flags, |
960 | splice_actor *actor) |
961 | { |
962 | ssize_t ret; |
963 | struct splice_desc sd = { |
964 | .total_len = len, |
965 | .flags = flags, |
966 | .pos = *ppos, |
967 | .u.file = out, |
968 | }; |
969 | |
970 | pipe_lock(pipe); |
971 | ret = __splice_from_pipe(pipe, &sd, actor); |
972 | pipe_unlock(pipe); |
973 | |
974 | return ret; |
975 | } |
976 | |
977 | /** |
978 | * generic_file_splice_write - splice data from a pipe to a file |
979 | * @pipe: pipe info |
980 | * @out: file to write to |
981 | * @ppos: position in @out |
982 | * @len: number of bytes to splice |
983 | * @flags: splice modifier flags |
984 | * |
985 | * Description: |
986 | * Will either move or copy pages (determined by @flags options) from |
987 | * the given pipe inode to the given file. |
988 | * |
989 | */ |
990 | ssize_t |
991 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, |
992 | loff_t *ppos, size_t len, unsigned int flags) |
993 | { |
994 | struct address_space *mapping = out->f_mapping; |
995 | struct inode *inode = mapping->host; |
996 | struct splice_desc sd = { |
997 | .total_len = len, |
998 | .flags = flags, |
999 | .pos = *ppos, |
1000 | .u.file = out, |
1001 | }; |
1002 | ssize_t ret; |
1003 | |
1004 | pipe_lock(pipe); |
1005 | |
1006 | splice_from_pipe_begin(&sd); |
1007 | do { |
1008 | ret = splice_from_pipe_next(pipe, &sd); |
1009 | if (ret <= 0) |
1010 | break; |
1011 | |
1012 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
1013 | ret = file_remove_suid(out); |
1014 | if (!ret) { |
1015 | ret = file_update_time(out); |
1016 | if (!ret) |
1017 | ret = splice_from_pipe_feed(pipe, &sd, |
1018 | pipe_to_file); |
1019 | } |
1020 | mutex_unlock(&inode->i_mutex); |
1021 | } while (ret > 0); |
1022 | splice_from_pipe_end(pipe, &sd); |
1023 | |
1024 | pipe_unlock(pipe); |
1025 | |
1026 | if (sd.num_spliced) |
1027 | ret = sd.num_spliced; |
1028 | |
1029 | if (ret > 0) { |
1030 | int err; |
1031 | |
1032 | err = generic_write_sync(out, *ppos, ret); |
1033 | if (err) |
1034 | ret = err; |
1035 | else |
1036 | *ppos += ret; |
1037 | balance_dirty_pages_ratelimited(mapping); |
1038 | } |
1039 | |
1040 | return ret; |
1041 | } |
1042 | |
1043 | EXPORT_SYMBOL(generic_file_splice_write); |
1044 | |
1045 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1046 | struct splice_desc *sd) |
1047 | { |
1048 | int ret; |
1049 | void *data; |
1050 | loff_t tmp = sd->pos; |
1051 | |
1052 | data = buf->ops->map(pipe, buf, 0); |
1053 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); |
1054 | buf->ops->unmap(pipe, buf, data); |
1055 | |
1056 | return ret; |
1057 | } |
1058 | |
1059 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, |
1060 | struct file *out, loff_t *ppos, |
1061 | size_t len, unsigned int flags) |
1062 | { |
1063 | ssize_t ret; |
1064 | |
1065 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
1066 | if (ret > 0) |
1067 | *ppos += ret; |
1068 | |
1069 | return ret; |
1070 | } |
1071 | |
1072 | /** |
1073 | * generic_splice_sendpage - splice data from a pipe to a socket |
1074 | * @pipe: pipe to splice from |
1075 | * @out: socket to write to |
1076 | * @ppos: position in @out |
1077 | * @len: number of bytes to splice |
1078 | * @flags: splice modifier flags |
1079 | * |
1080 | * Description: |
1081 | * Will send @len bytes from the pipe to a network socket. No data copying |
1082 | * is involved. |
1083 | * |
1084 | */ |
1085 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
1086 | loff_t *ppos, size_t len, unsigned int flags) |
1087 | { |
1088 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
1089 | } |
1090 | |
1091 | EXPORT_SYMBOL(generic_splice_sendpage); |
1092 | |
1093 | /* |
1094 | * Attempt to initiate a splice from pipe to file. |
1095 | */ |
1096 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
1097 | loff_t *ppos, size_t len, unsigned int flags) |
1098 | { |
1099 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
1100 | loff_t *, size_t, unsigned int); |
1101 | |
1102 | if (out->f_op && out->f_op->splice_write) |
1103 | splice_write = out->f_op->splice_write; |
1104 | else |
1105 | splice_write = default_file_splice_write; |
1106 | |
1107 | return splice_write(pipe, out, ppos, len, flags); |
1108 | } |
1109 | |
1110 | /* |
1111 | * Attempt to initiate a splice from a file to a pipe. |
1112 | */ |
1113 | static long do_splice_to(struct file *in, loff_t *ppos, |
1114 | struct pipe_inode_info *pipe, size_t len, |
1115 | unsigned int flags) |
1116 | { |
1117 | ssize_t (*splice_read)(struct file *, loff_t *, |
1118 | struct pipe_inode_info *, size_t, unsigned int); |
1119 | int ret; |
1120 | |
1121 | if (unlikely(!(in->f_mode & FMODE_READ))) |
1122 | return -EBADF; |
1123 | |
1124 | ret = rw_verify_area(READ, in, ppos, len); |
1125 | if (unlikely(ret < 0)) |
1126 | return ret; |
1127 | |
1128 | if (in->f_op && in->f_op->splice_read) |
1129 | splice_read = in->f_op->splice_read; |
1130 | else |
1131 | splice_read = default_file_splice_read; |
1132 | |
1133 | return splice_read(in, ppos, pipe, len, flags); |
1134 | } |
1135 | |
1136 | /** |
1137 | * splice_direct_to_actor - splices data directly between two non-pipes |
1138 | * @in: file to splice from |
1139 | * @sd: actor information on where to splice to |
1140 | * @actor: handles the data splicing |
1141 | * |
1142 | * Description: |
1143 | * This is a special case helper to splice directly between two |
1144 | * points, without requiring an explicit pipe. Internally an allocated |
1145 | * pipe is cached in the process, and reused during the lifetime of |
1146 | * that process. |
1147 | * |
1148 | */ |
1149 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, |
1150 | splice_direct_actor *actor) |
1151 | { |
1152 | struct pipe_inode_info *pipe; |
1153 | long ret, bytes; |
1154 | umode_t i_mode; |
1155 | size_t len; |
1156 | int i, flags; |
1157 | |
1158 | /* |
1159 | * We require the input being a regular file, as we don't want to |
1160 | * randomly drop data for eg socket -> socket splicing. Use the |
1161 | * piped splicing for that! |
1162 | */ |
1163 | i_mode = file_inode(in)->i_mode; |
1164 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
1165 | return -EINVAL; |
1166 | |
1167 | /* |
1168 | * neither in nor out is a pipe, setup an internal pipe attached to |
1169 | * 'out' and transfer the wanted data from 'in' to 'out' through that |
1170 | */ |
1171 | pipe = current->splice_pipe; |
1172 | if (unlikely(!pipe)) { |
1173 | pipe = alloc_pipe_info(); |
1174 | if (!pipe) |
1175 | return -ENOMEM; |
1176 | |
1177 | /* |
1178 | * We don't have an immediate reader, but we'll read the stuff |
1179 | * out of the pipe right after the splice_to_pipe(). So set |
1180 | * PIPE_READERS appropriately. |
1181 | */ |
1182 | pipe->readers = 1; |
1183 | |
1184 | current->splice_pipe = pipe; |
1185 | } |
1186 | |
1187 | /* |
1188 | * Do the splice. |
1189 | */ |
1190 | ret = 0; |
1191 | bytes = 0; |
1192 | len = sd->total_len; |
1193 | flags = sd->flags; |
1194 | |
1195 | /* |
1196 | * Don't block on output, we have to drain the direct pipe. |
1197 | */ |
1198 | sd->flags &= ~SPLICE_F_NONBLOCK; |
1199 | |
1200 | while (len) { |
1201 | size_t read_len; |
1202 | loff_t pos = sd->pos, prev_pos = pos; |
1203 | |
1204 | ret = do_splice_to(in, &pos, pipe, len, flags); |
1205 | if (unlikely(ret <= 0)) |
1206 | goto out_release; |
1207 | |
1208 | read_len = ret; |
1209 | sd->total_len = read_len; |
1210 | |
1211 | /* |
1212 | * NOTE: nonblocking mode only applies to the input. We |
1213 | * must not do the output in nonblocking mode as then we |
1214 | * could get stuck data in the internal pipe: |
1215 | */ |
1216 | ret = actor(pipe, sd); |
1217 | if (unlikely(ret <= 0)) { |
1218 | sd->pos = prev_pos; |
1219 | goto out_release; |
1220 | } |
1221 | |
1222 | bytes += ret; |
1223 | len -= ret; |
1224 | sd->pos = pos; |
1225 | |
1226 | if (ret < read_len) { |
1227 | sd->pos = prev_pos + ret; |
1228 | goto out_release; |
1229 | } |
1230 | } |
1231 | |
1232 | done: |
1233 | pipe->nrbufs = pipe->curbuf = 0; |
1234 | file_accessed(in); |
1235 | return bytes; |
1236 | |
1237 | out_release: |
1238 | /* |
1239 | * If we did an incomplete transfer we must release |
1240 | * the pipe buffers in question: |
1241 | */ |
1242 | for (i = 0; i < pipe->buffers; i++) { |
1243 | struct pipe_buffer *buf = pipe->bufs + i; |
1244 | |
1245 | if (buf->ops) { |
1246 | buf->ops->release(pipe, buf); |
1247 | buf->ops = NULL; |
1248 | } |
1249 | } |
1250 | |
1251 | if (!bytes) |
1252 | bytes = ret; |
1253 | |
1254 | goto done; |
1255 | } |
1256 | EXPORT_SYMBOL(splice_direct_to_actor); |
1257 | |
1258 | static int direct_splice_actor(struct pipe_inode_info *pipe, |
1259 | struct splice_desc *sd) |
1260 | { |
1261 | struct file *file = sd->u.file; |
1262 | |
1263 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
1264 | sd->flags); |
1265 | } |
1266 | |
1267 | /** |
1268 | * do_splice_direct - splices data directly between two files |
1269 | * @in: file to splice from |
1270 | * @ppos: input file offset |
1271 | * @out: file to splice to |
1272 | * @opos: output file offset |
1273 | * @len: number of bytes to splice |
1274 | * @flags: splice modifier flags |
1275 | * |
1276 | * Description: |
1277 | * For use by do_sendfile(). splice can easily emulate sendfile, but |
1278 | * doing it in the application would incur an extra system call |
1279 | * (splice in + splice out, as compared to just sendfile()). So this helper |
1280 | * can splice directly through a process-private pipe. |
1281 | * |
1282 | */ |
1283 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1284 | loff_t *opos, size_t len, unsigned int flags) |
1285 | { |
1286 | struct splice_desc sd = { |
1287 | .len = len, |
1288 | .total_len = len, |
1289 | .flags = flags, |
1290 | .pos = *ppos, |
1291 | .u.file = out, |
1292 | .opos = opos, |
1293 | }; |
1294 | long ret; |
1295 | |
1296 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1297 | return -EBADF; |
1298 | |
1299 | if (unlikely(out->f_flags & O_APPEND)) |
1300 | return -EINVAL; |
1301 | |
1302 | ret = rw_verify_area(WRITE, out, opos, len); |
1303 | if (unlikely(ret < 0)) |
1304 | return ret; |
1305 | |
1306 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
1307 | if (ret > 0) |
1308 | *ppos = sd.pos; |
1309 | |
1310 | return ret; |
1311 | } |
1312 | |
1313 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1314 | struct pipe_inode_info *opipe, |
1315 | size_t len, unsigned int flags); |
1316 | |
1317 | /* |
1318 | * Determine where to splice to/from. |
1319 | */ |
1320 | static long do_splice(struct file *in, loff_t __user *off_in, |
1321 | struct file *out, loff_t __user *off_out, |
1322 | size_t len, unsigned int flags) |
1323 | { |
1324 | struct pipe_inode_info *ipipe; |
1325 | struct pipe_inode_info *opipe; |
1326 | loff_t offset; |
1327 | long ret; |
1328 | |
1329 | ipipe = get_pipe_info(in); |
1330 | opipe = get_pipe_info(out); |
1331 | |
1332 | if (ipipe && opipe) { |
1333 | if (off_in || off_out) |
1334 | return -ESPIPE; |
1335 | |
1336 | if (!(in->f_mode & FMODE_READ)) |
1337 | return -EBADF; |
1338 | |
1339 | if (!(out->f_mode & FMODE_WRITE)) |
1340 | return -EBADF; |
1341 | |
1342 | /* Splicing to self would be fun, but... */ |
1343 | if (ipipe == opipe) |
1344 | return -EINVAL; |
1345 | |
1346 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1347 | } |
1348 | |
1349 | if (ipipe) { |
1350 | if (off_in) |
1351 | return -ESPIPE; |
1352 | if (off_out) { |
1353 | if (!(out->f_mode & FMODE_PWRITE)) |
1354 | return -EINVAL; |
1355 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
1356 | return -EFAULT; |
1357 | } else { |
1358 | offset = out->f_pos; |
1359 | } |
1360 | |
1361 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1362 | return -EBADF; |
1363 | |
1364 | if (unlikely(out->f_flags & O_APPEND)) |
1365 | return -EINVAL; |
1366 | |
1367 | ret = rw_verify_area(WRITE, out, &offset, len); |
1368 | if (unlikely(ret < 0)) |
1369 | return ret; |
1370 | |
1371 | file_start_write(out); |
1372 | ret = do_splice_from(ipipe, out, &offset, len, flags); |
1373 | file_end_write(out); |
1374 | |
1375 | if (!off_out) |
1376 | out->f_pos = offset; |
1377 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) |
1378 | ret = -EFAULT; |
1379 | |
1380 | return ret; |
1381 | } |
1382 | |
1383 | if (opipe) { |
1384 | if (off_out) |
1385 | return -ESPIPE; |
1386 | if (off_in) { |
1387 | if (!(in->f_mode & FMODE_PREAD)) |
1388 | return -EINVAL; |
1389 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
1390 | return -EFAULT; |
1391 | } else { |
1392 | offset = in->f_pos; |
1393 | } |
1394 | |
1395 | ret = do_splice_to(in, &offset, opipe, len, flags); |
1396 | |
1397 | if (!off_in) |
1398 | in->f_pos = offset; |
1399 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) |
1400 | ret = -EFAULT; |
1401 | |
1402 | return ret; |
1403 | } |
1404 | |
1405 | return -EINVAL; |
1406 | } |
1407 | |
1408 | /* |
1409 | * Map an iov into an array of pages and offset/length tupples. With the |
1410 | * partial_page structure, we can map several non-contiguous ranges into |
1411 | * our ones pages[] map instead of splitting that operation into pieces. |
1412 | * Could easily be exported as a generic helper for other users, in which |
1413 | * case one would probably want to add a 'max_nr_pages' parameter as well. |
1414 | */ |
1415 | static int get_iovec_page_array(const struct iovec __user *iov, |
1416 | unsigned int nr_vecs, struct page **pages, |
1417 | struct partial_page *partial, bool aligned, |
1418 | unsigned int pipe_buffers) |
1419 | { |
1420 | int buffers = 0, error = 0; |
1421 | |
1422 | while (nr_vecs) { |
1423 | unsigned long off, npages; |
1424 | struct iovec entry; |
1425 | void __user *base; |
1426 | size_t len; |
1427 | int i; |
1428 | |
1429 | error = -EFAULT; |
1430 | if (copy_from_user(&entry, iov, sizeof(entry))) |
1431 | break; |
1432 | |
1433 | base = entry.iov_base; |
1434 | len = entry.iov_len; |
1435 | |
1436 | /* |
1437 | * Sanity check this iovec. 0 read succeeds. |
1438 | */ |
1439 | error = 0; |
1440 | if (unlikely(!len)) |
1441 | break; |
1442 | error = -EFAULT; |
1443 | if (!access_ok(VERIFY_READ, base, len)) |
1444 | break; |
1445 | |
1446 | /* |
1447 | * Get this base offset and number of pages, then map |
1448 | * in the user pages. |
1449 | */ |
1450 | off = (unsigned long) base & ~PAGE_MASK; |
1451 | |
1452 | /* |
1453 | * If asked for alignment, the offset must be zero and the |
1454 | * length a multiple of the PAGE_SIZE. |
1455 | */ |
1456 | error = -EINVAL; |
1457 | if (aligned && (off || len & ~PAGE_MASK)) |
1458 | break; |
1459 | |
1460 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1461 | if (npages > pipe_buffers - buffers) |
1462 | npages = pipe_buffers - buffers; |
1463 | |
1464 | error = get_user_pages_fast((unsigned long)base, npages, |
1465 | 0, &pages[buffers]); |
1466 | |
1467 | if (unlikely(error <= 0)) |
1468 | break; |
1469 | |
1470 | /* |
1471 | * Fill this contiguous range into the partial page map. |
1472 | */ |
1473 | for (i = 0; i < error; i++) { |
1474 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
1475 | |
1476 | partial[buffers].offset = off; |
1477 | partial[buffers].len = plen; |
1478 | |
1479 | off = 0; |
1480 | len -= plen; |
1481 | buffers++; |
1482 | } |
1483 | |
1484 | /* |
1485 | * We didn't complete this iov, stop here since it probably |
1486 | * means we have to move some of this into a pipe to |
1487 | * be able to continue. |
1488 | */ |
1489 | if (len) |
1490 | break; |
1491 | |
1492 | /* |
1493 | * Don't continue if we mapped fewer pages than we asked for, |
1494 | * or if we mapped the max number of pages that we have |
1495 | * room for. |
1496 | */ |
1497 | if (error < npages || buffers == pipe_buffers) |
1498 | break; |
1499 | |
1500 | nr_vecs--; |
1501 | iov++; |
1502 | } |
1503 | |
1504 | if (buffers) |
1505 | return buffers; |
1506 | |
1507 | return error; |
1508 | } |
1509 | |
1510 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1511 | struct splice_desc *sd) |
1512 | { |
1513 | char *src; |
1514 | int ret; |
1515 | |
1516 | /* |
1517 | * See if we can use the atomic maps, by prefaulting in the |
1518 | * pages and doing an atomic copy |
1519 | */ |
1520 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { |
1521 | src = buf->ops->map(pipe, buf, 1); |
1522 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, |
1523 | sd->len); |
1524 | buf->ops->unmap(pipe, buf, src); |
1525 | if (!ret) { |
1526 | ret = sd->len; |
1527 | goto out; |
1528 | } |
1529 | } |
1530 | |
1531 | /* |
1532 | * No dice, use slow non-atomic map and copy |
1533 | */ |
1534 | src = buf->ops->map(pipe, buf, 0); |
1535 | |
1536 | ret = sd->len; |
1537 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) |
1538 | ret = -EFAULT; |
1539 | |
1540 | buf->ops->unmap(pipe, buf, src); |
1541 | out: |
1542 | if (ret > 0) |
1543 | sd->u.userptr += ret; |
1544 | return ret; |
1545 | } |
1546 | |
1547 | /* |
1548 | * For lack of a better implementation, implement vmsplice() to userspace |
1549 | * as a simple copy of the pipes pages to the user iov. |
1550 | */ |
1551 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, |
1552 | unsigned long nr_segs, unsigned int flags) |
1553 | { |
1554 | struct pipe_inode_info *pipe; |
1555 | struct splice_desc sd; |
1556 | ssize_t size; |
1557 | int error; |
1558 | long ret; |
1559 | |
1560 | pipe = get_pipe_info(file); |
1561 | if (!pipe) |
1562 | return -EBADF; |
1563 | |
1564 | pipe_lock(pipe); |
1565 | |
1566 | error = ret = 0; |
1567 | while (nr_segs) { |
1568 | void __user *base; |
1569 | size_t len; |
1570 | |
1571 | /* |
1572 | * Get user address base and length for this iovec. |
1573 | */ |
1574 | error = get_user(base, &iov->iov_base); |
1575 | if (unlikely(error)) |
1576 | break; |
1577 | error = get_user(len, &iov->iov_len); |
1578 | if (unlikely(error)) |
1579 | break; |
1580 | |
1581 | /* |
1582 | * Sanity check this iovec. 0 read succeeds. |
1583 | */ |
1584 | if (unlikely(!len)) |
1585 | break; |
1586 | if (unlikely(!base)) { |
1587 | error = -EFAULT; |
1588 | break; |
1589 | } |
1590 | |
1591 | if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { |
1592 | error = -EFAULT; |
1593 | break; |
1594 | } |
1595 | |
1596 | sd.len = 0; |
1597 | sd.total_len = len; |
1598 | sd.flags = flags; |
1599 | sd.u.userptr = base; |
1600 | sd.pos = 0; |
1601 | |
1602 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); |
1603 | if (size < 0) { |
1604 | if (!ret) |
1605 | ret = size; |
1606 | |
1607 | break; |
1608 | } |
1609 | |
1610 | ret += size; |
1611 | |
1612 | if (size < len) |
1613 | break; |
1614 | |
1615 | nr_segs--; |
1616 | iov++; |
1617 | } |
1618 | |
1619 | pipe_unlock(pipe); |
1620 | |
1621 | if (!ret) |
1622 | ret = error; |
1623 | |
1624 | return ret; |
1625 | } |
1626 | |
1627 | /* |
1628 | * vmsplice splices a user address range into a pipe. It can be thought of |
1629 | * as splice-from-memory, where the regular splice is splice-from-file (or |
1630 | * to file). In both cases the output is a pipe, naturally. |
1631 | */ |
1632 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1633 | unsigned long nr_segs, unsigned int flags) |
1634 | { |
1635 | struct pipe_inode_info *pipe; |
1636 | struct page *pages[PIPE_DEF_BUFFERS]; |
1637 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1638 | struct splice_pipe_desc spd = { |
1639 | .pages = pages, |
1640 | .partial = partial, |
1641 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1642 | .flags = flags, |
1643 | .ops = &user_page_pipe_buf_ops, |
1644 | .spd_release = spd_release_page, |
1645 | }; |
1646 | long ret; |
1647 | |
1648 | pipe = get_pipe_info(file); |
1649 | if (!pipe) |
1650 | return -EBADF; |
1651 | |
1652 | if (splice_grow_spd(pipe, &spd)) |
1653 | return -ENOMEM; |
1654 | |
1655 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, |
1656 | spd.partial, false, |
1657 | spd.nr_pages_max); |
1658 | if (spd.nr_pages <= 0) |
1659 | ret = spd.nr_pages; |
1660 | else |
1661 | ret = splice_to_pipe(pipe, &spd); |
1662 | |
1663 | splice_shrink_spd(&spd); |
1664 | return ret; |
1665 | } |
1666 | |
1667 | /* |
1668 | * Note that vmsplice only really supports true splicing _from_ user memory |
1669 | * to a pipe, not the other way around. Splicing from user memory is a simple |
1670 | * operation that can be supported without any funky alignment restrictions |
1671 | * or nasty vm tricks. We simply map in the user memory and fill them into |
1672 | * a pipe. The reverse isn't quite as easy, though. There are two possible |
1673 | * solutions for that: |
1674 | * |
1675 | * - memcpy() the data internally, at which point we might as well just |
1676 | * do a regular read() on the buffer anyway. |
1677 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it |
1678 | * has restriction limitations on both ends of the pipe). |
1679 | * |
1680 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). |
1681 | * |
1682 | */ |
1683 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1684 | unsigned long, nr_segs, unsigned int, flags) |
1685 | { |
1686 | struct fd f; |
1687 | long error; |
1688 | |
1689 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1690 | return -EINVAL; |
1691 | else if (unlikely(!nr_segs)) |
1692 | return 0; |
1693 | |
1694 | error = -EBADF; |
1695 | f = fdget(fd); |
1696 | if (f.file) { |
1697 | if (f.file->f_mode & FMODE_WRITE) |
1698 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); |
1699 | else if (f.file->f_mode & FMODE_READ) |
1700 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); |
1701 | |
1702 | fdput(f); |
1703 | } |
1704 | |
1705 | return error; |
1706 | } |
1707 | |
1708 | #ifdef CONFIG_COMPAT |
1709 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, |
1710 | unsigned int, nr_segs, unsigned int, flags) |
1711 | { |
1712 | unsigned i; |
1713 | struct iovec __user *iov; |
1714 | if (nr_segs > UIO_MAXIOV) |
1715 | return -EINVAL; |
1716 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); |
1717 | for (i = 0; i < nr_segs; i++) { |
1718 | struct compat_iovec v; |
1719 | if (get_user(v.iov_base, &iov32[i].iov_base) || |
1720 | get_user(v.iov_len, &iov32[i].iov_len) || |
1721 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || |
1722 | put_user(v.iov_len, &iov[i].iov_len)) |
1723 | return -EFAULT; |
1724 | } |
1725 | return sys_vmsplice(fd, iov, nr_segs, flags); |
1726 | } |
1727 | #endif |
1728 | |
1729 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1730 | int, fd_out, loff_t __user *, off_out, |
1731 | size_t, len, unsigned int, flags) |
1732 | { |
1733 | struct fd in, out; |
1734 | long error; |
1735 | |
1736 | if (unlikely(!len)) |
1737 | return 0; |
1738 | |
1739 | error = -EBADF; |
1740 | in = fdget(fd_in); |
1741 | if (in.file) { |
1742 | if (in.file->f_mode & FMODE_READ) { |
1743 | out = fdget(fd_out); |
1744 | if (out.file) { |
1745 | if (out.file->f_mode & FMODE_WRITE) |
1746 | error = do_splice(in.file, off_in, |
1747 | out.file, off_out, |
1748 | len, flags); |
1749 | fdput(out); |
1750 | } |
1751 | } |
1752 | fdput(in); |
1753 | } |
1754 | return error; |
1755 | } |
1756 | |
1757 | /* |
1758 | * Make sure there's data to read. Wait for input if we can, otherwise |
1759 | * return an appropriate error. |
1760 | */ |
1761 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1762 | { |
1763 | int ret; |
1764 | |
1765 | /* |
1766 | * Check ->nrbufs without the inode lock first. This function |
1767 | * is speculative anyways, so missing one is ok. |
1768 | */ |
1769 | if (pipe->nrbufs) |
1770 | return 0; |
1771 | |
1772 | ret = 0; |
1773 | pipe_lock(pipe); |
1774 | |
1775 | while (!pipe->nrbufs) { |
1776 | if (signal_pending(current)) { |
1777 | ret = -ERESTARTSYS; |
1778 | break; |
1779 | } |
1780 | if (!pipe->writers) |
1781 | break; |
1782 | if (!pipe->waiting_writers) { |
1783 | if (flags & SPLICE_F_NONBLOCK) { |
1784 | ret = -EAGAIN; |
1785 | break; |
1786 | } |
1787 | } |
1788 | pipe_wait(pipe); |
1789 | } |
1790 | |
1791 | pipe_unlock(pipe); |
1792 | return ret; |
1793 | } |
1794 | |
1795 | /* |
1796 | * Make sure there's writeable room. Wait for room if we can, otherwise |
1797 | * return an appropriate error. |
1798 | */ |
1799 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1800 | { |
1801 | int ret; |
1802 | |
1803 | /* |
1804 | * Check ->nrbufs without the inode lock first. This function |
1805 | * is speculative anyways, so missing one is ok. |
1806 | */ |
1807 | if (pipe->nrbufs < pipe->buffers) |
1808 | return 0; |
1809 | |
1810 | ret = 0; |
1811 | pipe_lock(pipe); |
1812 | |
1813 | while (pipe->nrbufs >= pipe->buffers) { |
1814 | if (!pipe->readers) { |
1815 | send_sig(SIGPIPE, current, 0); |
1816 | ret = -EPIPE; |
1817 | break; |
1818 | } |
1819 | if (flags & SPLICE_F_NONBLOCK) { |
1820 | ret = -EAGAIN; |
1821 | break; |
1822 | } |
1823 | if (signal_pending(current)) { |
1824 | ret = -ERESTARTSYS; |
1825 | break; |
1826 | } |
1827 | pipe->waiting_writers++; |
1828 | pipe_wait(pipe); |
1829 | pipe->waiting_writers--; |
1830 | } |
1831 | |
1832 | pipe_unlock(pipe); |
1833 | return ret; |
1834 | } |
1835 | |
1836 | /* |
1837 | * Splice contents of ipipe to opipe. |
1838 | */ |
1839 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1840 | struct pipe_inode_info *opipe, |
1841 | size_t len, unsigned int flags) |
1842 | { |
1843 | struct pipe_buffer *ibuf, *obuf; |
1844 | int ret = 0, nbuf; |
1845 | bool input_wakeup = false; |
1846 | |
1847 | |
1848 | retry: |
1849 | ret = ipipe_prep(ipipe, flags); |
1850 | if (ret) |
1851 | return ret; |
1852 | |
1853 | ret = opipe_prep(opipe, flags); |
1854 | if (ret) |
1855 | return ret; |
1856 | |
1857 | /* |
1858 | * Potential ABBA deadlock, work around it by ordering lock |
1859 | * grabbing by pipe info address. Otherwise two different processes |
1860 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1861 | */ |
1862 | pipe_double_lock(ipipe, opipe); |
1863 | |
1864 | do { |
1865 | if (!opipe->readers) { |
1866 | send_sig(SIGPIPE, current, 0); |
1867 | if (!ret) |
1868 | ret = -EPIPE; |
1869 | break; |
1870 | } |
1871 | |
1872 | if (!ipipe->nrbufs && !ipipe->writers) |
1873 | break; |
1874 | |
1875 | /* |
1876 | * Cannot make any progress, because either the input |
1877 | * pipe is empty or the output pipe is full. |
1878 | */ |
1879 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
1880 | /* Already processed some buffers, break */ |
1881 | if (ret) |
1882 | break; |
1883 | |
1884 | if (flags & SPLICE_F_NONBLOCK) { |
1885 | ret = -EAGAIN; |
1886 | break; |
1887 | } |
1888 | |
1889 | /* |
1890 | * We raced with another reader/writer and haven't |
1891 | * managed to process any buffers. A zero return |
1892 | * value means EOF, so retry instead. |
1893 | */ |
1894 | pipe_unlock(ipipe); |
1895 | pipe_unlock(opipe); |
1896 | goto retry; |
1897 | } |
1898 | |
1899 | ibuf = ipipe->bufs + ipipe->curbuf; |
1900 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1901 | obuf = opipe->bufs + nbuf; |
1902 | |
1903 | if (len >= ibuf->len) { |
1904 | /* |
1905 | * Simply move the whole buffer from ipipe to opipe |
1906 | */ |
1907 | *obuf = *ibuf; |
1908 | ibuf->ops = NULL; |
1909 | opipe->nrbufs++; |
1910 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
1911 | ipipe->nrbufs--; |
1912 | input_wakeup = true; |
1913 | } else { |
1914 | /* |
1915 | * Get a reference to this pipe buffer, |
1916 | * so we can copy the contents over. |
1917 | */ |
1918 | ibuf->ops->get(ipipe, ibuf); |
1919 | *obuf = *ibuf; |
1920 | |
1921 | /* |
1922 | * Don't inherit the gift flag, we need to |
1923 | * prevent multiple steals of this page. |
1924 | */ |
1925 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1926 | |
1927 | obuf->len = len; |
1928 | opipe->nrbufs++; |
1929 | ibuf->offset += obuf->len; |
1930 | ibuf->len -= obuf->len; |
1931 | } |
1932 | ret += obuf->len; |
1933 | len -= obuf->len; |
1934 | } while (len); |
1935 | |
1936 | pipe_unlock(ipipe); |
1937 | pipe_unlock(opipe); |
1938 | |
1939 | /* |
1940 | * If we put data in the output pipe, wakeup any potential readers. |
1941 | */ |
1942 | if (ret > 0) |
1943 | wakeup_pipe_readers(opipe); |
1944 | |
1945 | if (input_wakeup) |
1946 | wakeup_pipe_writers(ipipe); |
1947 | |
1948 | return ret; |
1949 | } |
1950 | |
1951 | /* |
1952 | * Link contents of ipipe to opipe. |
1953 | */ |
1954 | static int link_pipe(struct pipe_inode_info *ipipe, |
1955 | struct pipe_inode_info *opipe, |
1956 | size_t len, unsigned int flags) |
1957 | { |
1958 | struct pipe_buffer *ibuf, *obuf; |
1959 | int ret = 0, i = 0, nbuf; |
1960 | |
1961 | /* |
1962 | * Potential ABBA deadlock, work around it by ordering lock |
1963 | * grabbing by pipe info address. Otherwise two different processes |
1964 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1965 | */ |
1966 | pipe_double_lock(ipipe, opipe); |
1967 | |
1968 | do { |
1969 | if (!opipe->readers) { |
1970 | send_sig(SIGPIPE, current, 0); |
1971 | if (!ret) |
1972 | ret = -EPIPE; |
1973 | break; |
1974 | } |
1975 | |
1976 | /* |
1977 | * If we have iterated all input buffers or ran out of |
1978 | * output room, break. |
1979 | */ |
1980 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
1981 | break; |
1982 | |
1983 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
1984 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
1985 | |
1986 | /* |
1987 | * Get a reference to this pipe buffer, |
1988 | * so we can copy the contents over. |
1989 | */ |
1990 | ibuf->ops->get(ipipe, ibuf); |
1991 | |
1992 | obuf = opipe->bufs + nbuf; |
1993 | *obuf = *ibuf; |
1994 | |
1995 | /* |
1996 | * Don't inherit the gift flag, we need to |
1997 | * prevent multiple steals of this page. |
1998 | */ |
1999 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
2000 | |
2001 | if (obuf->len > len) |
2002 | obuf->len = len; |
2003 | |
2004 | opipe->nrbufs++; |
2005 | ret += obuf->len; |
2006 | len -= obuf->len; |
2007 | i++; |
2008 | } while (len); |
2009 | |
2010 | /* |
2011 | * return EAGAIN if we have the potential of some data in the |
2012 | * future, otherwise just return 0 |
2013 | */ |
2014 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) |
2015 | ret = -EAGAIN; |
2016 | |
2017 | pipe_unlock(ipipe); |
2018 | pipe_unlock(opipe); |
2019 | |
2020 | /* |
2021 | * If we put data in the output pipe, wakeup any potential readers. |
2022 | */ |
2023 | if (ret > 0) |
2024 | wakeup_pipe_readers(opipe); |
2025 | |
2026 | return ret; |
2027 | } |
2028 | |
2029 | /* |
2030 | * This is a tee(1) implementation that works on pipes. It doesn't copy |
2031 | * any data, it simply references the 'in' pages on the 'out' pipe. |
2032 | * The 'flags' used are the SPLICE_F_* variants, currently the only |
2033 | * applicable one is SPLICE_F_NONBLOCK. |
2034 | */ |
2035 | static long do_tee(struct file *in, struct file *out, size_t len, |
2036 | unsigned int flags) |
2037 | { |
2038 | struct pipe_inode_info *ipipe = get_pipe_info(in); |
2039 | struct pipe_inode_info *opipe = get_pipe_info(out); |
2040 | int ret = -EINVAL; |
2041 | |
2042 | /* |
2043 | * Duplicate the contents of ipipe to opipe without actually |
2044 | * copying the data. |
2045 | */ |
2046 | if (ipipe && opipe && ipipe != opipe) { |
2047 | /* |
2048 | * Keep going, unless we encounter an error. The ipipe/opipe |
2049 | * ordering doesn't really matter. |
2050 | */ |
2051 | ret = ipipe_prep(ipipe, flags); |
2052 | if (!ret) { |
2053 | ret = opipe_prep(opipe, flags); |
2054 | if (!ret) |
2055 | ret = link_pipe(ipipe, opipe, len, flags); |
2056 | } |
2057 | } |
2058 | |
2059 | return ret; |
2060 | } |
2061 | |
2062 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
2063 | { |
2064 | struct fd in; |
2065 | int error; |
2066 | |
2067 | if (unlikely(!len)) |
2068 | return 0; |
2069 | |
2070 | error = -EBADF; |
2071 | in = fdget(fdin); |
2072 | if (in.file) { |
2073 | if (in.file->f_mode & FMODE_READ) { |
2074 | struct fd out = fdget(fdout); |
2075 | if (out.file) { |
2076 | if (out.file->f_mode & FMODE_WRITE) |
2077 | error = do_tee(in.file, out.file, |
2078 | len, flags); |
2079 | fdput(out); |
2080 | } |
2081 | } |
2082 | fdput(in); |
2083 | } |
2084 | |
2085 | return error; |
2086 | } |
2087 |
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Tags:
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od-2011-09-18
v2.6.34-rc5
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