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