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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/memcontrol.h> | |
25 | #include <linux/mm_inline.h> | |
26 | #include <linux/swap.h> | |
27 | #include <linux/writeback.h> | |
28 | #include <linux/buffer_head.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/syscalls.h> | |
31 | #include <linux/uio.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/gfp.h> | |
34 | ||
35 | /* | |
36 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
37 | * a vm helper function, it's already simplified quite a bit by the | |
38 | * addition of remove_mapping(). If success is returned, the caller may | |
39 | * attempt to reuse this page for another destination. | |
40 | */ | |
41 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, | |
42 | struct pipe_buffer *buf) | |
43 | { | |
44 | struct page *page = buf->page; | |
45 | struct address_space *mapping; | |
46 | ||
47 | lock_page(page); | |
48 | ||
49 | mapping = page_mapping(page); | |
50 | if (mapping) { | |
51 | WARN_ON(!PageUptodate(page)); | |
52 | ||
53 | /* | |
54 | * At least for ext2 with nobh option, we need to wait on | |
55 | * writeback completing on this page, since we'll remove it | |
56 | * from the pagecache. Otherwise truncate wont wait on the | |
57 | * page, allowing the disk blocks to be reused by someone else | |
58 | * before we actually wrote our data to them. fs corruption | |
59 | * ensues. | |
60 | */ | |
61 | wait_on_page_writeback(page); | |
62 | ||
63 | if (page_has_private(page) && | |
64 | !try_to_release_page(page, GFP_KERNEL)) | |
65 | goto out_unlock; | |
66 | ||
67 | /* | |
68 | * If we succeeded in removing the mapping, set LRU flag | |
69 | * and return good. | |
70 | */ | |
71 | if (remove_mapping(mapping, page)) { | |
72 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
73 | return 0; | |
74 | } | |
75 | } | |
76 | ||
77 | /* | |
78 | * Raced with truncate or failed to remove page from current | |
79 | * address space, unlock and return failure. | |
80 | */ | |
81 | out_unlock: | |
82 | unlock_page(page); | |
83 | return 1; | |
84 | } | |
85 | ||
86 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, | |
87 | struct pipe_buffer *buf) | |
88 | { | |
89 | page_cache_release(buf->page); | |
90 | buf->flags &= ~PIPE_BUF_FLAG_LRU; | |
91 | } | |
92 | ||
93 | /* | |
94 | * Check whether the contents of buf is OK to access. Since the content | |
95 | * is a page cache page, IO may be in flight. | |
96 | */ | |
97 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, | |
98 | struct pipe_buffer *buf) | |
99 | { | |
100 | struct page *page = buf->page; | |
101 | int err; | |
102 | ||
103 | if (!PageUptodate(page)) { | |
104 | lock_page(page); | |
105 | ||
106 | /* | |
107 | * Page got truncated/unhashed. This will cause a 0-byte | |
108 | * splice, if this is the first page. | |
109 | */ | |
110 | if (!page->mapping) { | |
111 | err = -ENODATA; | |
112 | goto error; | |
113 | } | |
114 | ||
115 | /* | |
116 | * Uh oh, read-error from disk. | |
117 | */ | |
118 | if (!PageUptodate(page)) { | |
119 | err = -EIO; | |
120 | goto error; | |
121 | } | |
122 | ||
123 | /* | |
124 | * Page is ok afterall, we are done. | |
125 | */ | |
126 | unlock_page(page); | |
127 | } | |
128 | ||
129 | return 0; | |
130 | error: | |
131 | unlock_page(page); | |
132 | return err; | |
133 | } | |
134 | ||
135 | static const struct pipe_buf_operations page_cache_pipe_buf_ops = { | |
136 | .can_merge = 0, | |
137 | .map = generic_pipe_buf_map, | |
138 | .unmap = generic_pipe_buf_unmap, | |
139 | .confirm = page_cache_pipe_buf_confirm, | |
140 | .release = page_cache_pipe_buf_release, | |
141 | .steal = page_cache_pipe_buf_steal, | |
142 | .get = generic_pipe_buf_get, | |
143 | }; | |
144 | ||
145 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, | |
146 | struct pipe_buffer *buf) | |
147 | { | |
148 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) | |
149 | return 1; | |
150 | ||
151 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
152 | return generic_pipe_buf_steal(pipe, buf); | |
153 | } | |
154 | ||
155 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { | |
156 | .can_merge = 0, | |
157 | .map = generic_pipe_buf_map, | |
158 | .unmap = generic_pipe_buf_unmap, | |
159 | .confirm = generic_pipe_buf_confirm, | |
160 | .release = page_cache_pipe_buf_release, | |
161 | .steal = user_page_pipe_buf_steal, | |
162 | .get = generic_pipe_buf_get, | |
163 | }; | |
164 | ||
165 | /** | |
166 | * splice_to_pipe - fill passed data into a pipe | |
167 | * @pipe: pipe to fill | |
168 | * @spd: data to fill | |
169 | * | |
170 | * Description: | |
171 | * @spd contains a map of pages and len/offset tuples, along with | |
172 | * the struct pipe_buf_operations associated with these pages. This | |
173 | * function will link that data to the pipe. | |
174 | * | |
175 | */ | |
176 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, | |
177 | struct splice_pipe_desc *spd) | |
178 | { | |
179 | unsigned int spd_pages = spd->nr_pages; | |
180 | int ret, do_wakeup, page_nr; | |
181 | ||
182 | ret = 0; | |
183 | do_wakeup = 0; | |
184 | page_nr = 0; | |
185 | ||
186 | pipe_lock(pipe); | |
187 | ||
188 | for (;;) { | |
189 | if (!pipe->readers) { | |
190 | send_sig(SIGPIPE, current, 0); | |
191 | if (!ret) | |
192 | ret = -EPIPE; | |
193 | break; | |
194 | } | |
195 | ||
196 | if (pipe->nrbufs < pipe->buffers) { | |
197 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
198 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
199 | ||
200 | buf->page = spd->pages[page_nr]; | |
201 | buf->offset = spd->partial[page_nr].offset; | |
202 | buf->len = spd->partial[page_nr].len; | |
203 | buf->private = spd->partial[page_nr].private; | |
204 | buf->ops = spd->ops; | |
205 | if (spd->flags & SPLICE_F_GIFT) | |
206 | buf->flags |= PIPE_BUF_FLAG_GIFT; | |
207 | ||
208 | pipe->nrbufs++; | |
209 | page_nr++; | |
210 | ret += buf->len; | |
211 | ||
212 | if (pipe->inode) | |
213 | do_wakeup = 1; | |
214 | ||
215 | if (!--spd->nr_pages) | |
216 | break; | |
217 | if (pipe->nrbufs < pipe->buffers) | |
218 | continue; | |
219 | ||
220 | break; | |
221 | } | |
222 | ||
223 | if (spd->flags & SPLICE_F_NONBLOCK) { | |
224 | if (!ret) | |
225 | ret = -EAGAIN; | |
226 | break; | |
227 | } | |
228 | ||
229 | if (signal_pending(current)) { | |
230 | if (!ret) | |
231 | ret = -ERESTARTSYS; | |
232 | break; | |
233 | } | |
234 | ||
235 | if (do_wakeup) { | |
236 | smp_mb(); | |
237 | if (waitqueue_active(&pipe->wait)) | |
238 | wake_up_interruptible_sync(&pipe->wait); | |
239 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
240 | do_wakeup = 0; | |
241 | } | |
242 | ||
243 | pipe->waiting_writers++; | |
244 | pipe_wait(pipe); | |
245 | pipe->waiting_writers--; | |
246 | } | |
247 | ||
248 | pipe_unlock(pipe); | |
249 | ||
250 | if (do_wakeup) { | |
251 | smp_mb(); | |
252 | if (waitqueue_active(&pipe->wait)) | |
253 | wake_up_interruptible(&pipe->wait); | |
254 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
255 | } | |
256 | ||
257 | while (page_nr < spd_pages) | |
258 | spd->spd_release(spd, page_nr++); | |
259 | ||
260 | return ret; | |
261 | } | |
262 | ||
263 | static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) | |
264 | { | |
265 | page_cache_release(spd->pages[i]); | |
266 | } | |
267 | ||
268 | /* | |
269 | * Check if we need to grow the arrays holding pages and partial page | |
270 | * descriptions. | |
271 | */ | |
272 | int splice_grow_spd(struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) | |
273 | { | |
274 | if (pipe->buffers <= PIPE_DEF_BUFFERS) | |
275 | return 0; | |
276 | ||
277 | spd->pages = kmalloc(pipe->buffers * sizeof(struct page *), GFP_KERNEL); | |
278 | spd->partial = kmalloc(pipe->buffers * sizeof(struct partial_page), GFP_KERNEL); | |
279 | ||
280 | if (spd->pages && spd->partial) | |
281 | return 0; | |
282 | ||
283 | kfree(spd->pages); | |
284 | kfree(spd->partial); | |
285 | return -ENOMEM; | |
286 | } | |
287 | ||
288 | void splice_shrink_spd(struct pipe_inode_info *pipe, | |
289 | struct splice_pipe_desc *spd) | |
290 | { | |
291 | if (pipe->buffers <= PIPE_DEF_BUFFERS) | |
292 | return; | |
293 | ||
294 | kfree(spd->pages); | |
295 | kfree(spd->partial); | |
296 | } | |
297 | ||
298 | static int | |
299 | __generic_file_splice_read(struct file *in, loff_t *ppos, | |
300 | struct pipe_inode_info *pipe, size_t len, | |
301 | unsigned int flags) | |
302 | { | |
303 | struct address_space *mapping = in->f_mapping; | |
304 | unsigned int loff, nr_pages, req_pages; | |
305 | struct page *pages[PIPE_DEF_BUFFERS]; | |
306 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
307 | struct page *page; | |
308 | pgoff_t index, end_index; | |
309 | loff_t isize; | |
310 | int error, page_nr; | |
311 | struct splice_pipe_desc spd = { | |
312 | .pages = pages, | |
313 | .partial = partial, | |
314 | .flags = flags, | |
315 | .ops = &page_cache_pipe_buf_ops, | |
316 | .spd_release = spd_release_page, | |
317 | }; | |
318 | ||
319 | if (splice_grow_spd(pipe, &spd)) | |
320 | return -ENOMEM; | |
321 | ||
322 | index = *ppos >> PAGE_CACHE_SHIFT; | |
323 | loff = *ppos & ~PAGE_CACHE_MASK; | |
324 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
325 | nr_pages = min(req_pages, pipe->buffers); | |
326 | ||
327 | /* | |
328 | * Lookup the (hopefully) full range of pages we need. | |
329 | */ | |
330 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); | |
331 | index += spd.nr_pages; | |
332 | ||
333 | /* | |
334 | * If find_get_pages_contig() returned fewer pages than we needed, | |
335 | * readahead/allocate the rest and fill in the holes. | |
336 | */ | |
337 | if (spd.nr_pages < nr_pages) | |
338 | page_cache_sync_readahead(mapping, &in->f_ra, in, | |
339 | index, req_pages - spd.nr_pages); | |
340 | ||
341 | error = 0; | |
342 | while (spd.nr_pages < nr_pages) { | |
343 | /* | |
344 | * Page could be there, find_get_pages_contig() breaks on | |
345 | * the first hole. | |
346 | */ | |
347 | page = find_get_page(mapping, index); | |
348 | if (!page) { | |
349 | /* | |
350 | * page didn't exist, allocate one. | |
351 | */ | |
352 | page = page_cache_alloc_cold(mapping); | |
353 | if (!page) | |
354 | break; | |
355 | ||
356 | error = add_to_page_cache_lru(page, mapping, index, | |
357 | mapping_gfp_mask(mapping)); | |
358 | if (unlikely(error)) { | |
359 | page_cache_release(page); | |
360 | if (error == -EEXIST) | |
361 | continue; | |
362 | break; | |
363 | } | |
364 | /* | |
365 | * add_to_page_cache() locks the page, unlock it | |
366 | * to avoid convoluting the logic below even more. | |
367 | */ | |
368 | unlock_page(page); | |
369 | } | |
370 | ||
371 | spd.pages[spd.nr_pages++] = page; | |
372 | index++; | |
373 | } | |
374 | ||
375 | /* | |
376 | * Now loop over the map and see if we need to start IO on any | |
377 | * pages, fill in the partial map, etc. | |
378 | */ | |
379 | index = *ppos >> PAGE_CACHE_SHIFT; | |
380 | nr_pages = spd.nr_pages; | |
381 | spd.nr_pages = 0; | |
382 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
383 | unsigned int this_len; | |
384 | ||
385 | if (!len) | |
386 | break; | |
387 | ||
388 | /* | |
389 | * this_len is the max we'll use from this page | |
390 | */ | |
391 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
392 | page = spd.pages[page_nr]; | |
393 | ||
394 | if (PageReadahead(page)) | |
395 | page_cache_async_readahead(mapping, &in->f_ra, in, | |
396 | page, index, req_pages - page_nr); | |
397 | ||
398 | /* | |
399 | * If the page isn't uptodate, we may need to start io on it | |
400 | */ | |
401 | if (!PageUptodate(page)) { | |
402 | /* | |
403 | * If in nonblock mode then dont block on waiting | |
404 | * for an in-flight io page | |
405 | */ | |
406 | if (flags & SPLICE_F_NONBLOCK) { | |
407 | if (!trylock_page(page)) { | |
408 | error = -EAGAIN; | |
409 | break; | |
410 | } | |
411 | } else | |
412 | lock_page(page); | |
413 | ||
414 | /* | |
415 | * Page was truncated, or invalidated by the | |
416 | * filesystem. Redo the find/create, but this time the | |
417 | * page is kept locked, so there's no chance of another | |
418 | * race with truncate/invalidate. | |
419 | */ | |
420 | if (!page->mapping) { | |
421 | unlock_page(page); | |
422 | page = find_or_create_page(mapping, index, | |
423 | mapping_gfp_mask(mapping)); | |
424 | ||
425 | if (!page) { | |
426 | error = -ENOMEM; | |
427 | break; | |
428 | } | |
429 | page_cache_release(spd.pages[page_nr]); | |
430 | spd.pages[page_nr] = page; | |
431 | } | |
432 | /* | |
433 | * page was already under io and is now done, great | |
434 | */ | |
435 | if (PageUptodate(page)) { | |
436 | unlock_page(page); | |
437 | goto fill_it; | |
438 | } | |
439 | ||
440 | /* | |
441 | * need to read in the page | |
442 | */ | |
443 | error = mapping->a_ops->readpage(in, page); | |
444 | if (unlikely(error)) { | |
445 | /* | |
446 | * We really should re-lookup the page here, | |
447 | * but it complicates things a lot. Instead | |
448 | * lets just do what we already stored, and | |
449 | * we'll get it the next time we are called. | |
450 | */ | |
451 | if (error == AOP_TRUNCATED_PAGE) | |
452 | error = 0; | |
453 | ||
454 | break; | |
455 | } | |
456 | } | |
457 | fill_it: | |
458 | /* | |
459 | * i_size must be checked after PageUptodate. | |
460 | */ | |
461 | isize = i_size_read(mapping->host); | |
462 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
463 | if (unlikely(!isize || index > end_index)) | |
464 | break; | |
465 | ||
466 | /* | |
467 | * if this is the last page, see if we need to shrink | |
468 | * the length and stop | |
469 | */ | |
470 | if (end_index == index) { | |
471 | unsigned int plen; | |
472 | ||
473 | /* | |
474 | * max good bytes in this page | |
475 | */ | |
476 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
477 | if (plen <= loff) | |
478 | break; | |
479 | ||
480 | /* | |
481 | * force quit after adding this page | |
482 | */ | |
483 | this_len = min(this_len, plen - loff); | |
484 | len = this_len; | |
485 | } | |
486 | ||
487 | spd.partial[page_nr].offset = loff; | |
488 | spd.partial[page_nr].len = this_len; | |
489 | len -= this_len; | |
490 | loff = 0; | |
491 | spd.nr_pages++; | |
492 | index++; | |
493 | } | |
494 | ||
495 | /* | |
496 | * Release any pages at the end, if we quit early. 'page_nr' is how far | |
497 | * we got, 'nr_pages' is how many pages are in the map. | |
498 | */ | |
499 | while (page_nr < nr_pages) | |
500 | page_cache_release(spd.pages[page_nr++]); | |
501 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; | |
502 | ||
503 | if (spd.nr_pages) | |
504 | error = splice_to_pipe(pipe, &spd); | |
505 | ||
506 | splice_shrink_spd(pipe, &spd); | |
507 | return error; | |
508 | } | |
509 | ||
510 | /** | |
511 | * generic_file_splice_read - splice data from file to a pipe | |
512 | * @in: file to splice from | |
513 | * @ppos: position in @in | |
514 | * @pipe: pipe to splice to | |
515 | * @len: number of bytes to splice | |
516 | * @flags: splice modifier flags | |
517 | * | |
518 | * Description: | |
519 | * Will read pages from given file and fill them into a pipe. Can be | |
520 | * used as long as the address_space operations for the source implements | |
521 | * a readpage() hook. | |
522 | * | |
523 | */ | |
524 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, | |
525 | struct pipe_inode_info *pipe, size_t len, | |
526 | unsigned int flags) | |
527 | { | |
528 | loff_t isize, left; | |
529 | int ret; | |
530 | ||
531 | isize = i_size_read(in->f_mapping->host); | |
532 | if (unlikely(*ppos >= isize)) | |
533 | return 0; | |
534 | ||
535 | left = isize - *ppos; | |
536 | if (unlikely(left < len)) | |
537 | len = left; | |
538 | ||
539 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); | |
540 | if (ret > 0) { | |
541 | *ppos += ret; | |
542 | file_accessed(in); | |
543 | } | |
544 | ||
545 | return ret; | |
546 | } | |
547 | EXPORT_SYMBOL(generic_file_splice_read); | |
548 | ||
549 | static const struct pipe_buf_operations default_pipe_buf_ops = { | |
550 | .can_merge = 0, | |
551 | .map = generic_pipe_buf_map, | |
552 | .unmap = generic_pipe_buf_unmap, | |
553 | .confirm = generic_pipe_buf_confirm, | |
554 | .release = generic_pipe_buf_release, | |
555 | .steal = generic_pipe_buf_steal, | |
556 | .get = generic_pipe_buf_get, | |
557 | }; | |
558 | ||
559 | static ssize_t kernel_readv(struct file *file, const struct iovec *vec, | |
560 | unsigned long vlen, loff_t offset) | |
561 | { | |
562 | mm_segment_t old_fs; | |
563 | loff_t pos = offset; | |
564 | ssize_t res; | |
565 | ||
566 | old_fs = get_fs(); | |
567 | set_fs(get_ds()); | |
568 | /* The cast to a user pointer is valid due to the set_fs() */ | |
569 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos); | |
570 | set_fs(old_fs); | |
571 | ||
572 | return res; | |
573 | } | |
574 | ||
575 | static ssize_t kernel_write(struct file *file, const char *buf, size_t count, | |
576 | loff_t pos) | |
577 | { | |
578 | mm_segment_t old_fs; | |
579 | ssize_t res; | |
580 | ||
581 | old_fs = get_fs(); | |
582 | set_fs(get_ds()); | |
583 | /* The cast to a user pointer is valid due to the set_fs() */ | |
584 | res = vfs_write(file, (const char __user *)buf, count, &pos); | |
585 | set_fs(old_fs); | |
586 | ||
587 | return res; | |
588 | } | |
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 | pgoff_t index; | |
601 | ssize_t res; | |
602 | size_t this_len; | |
603 | int error; | |
604 | int i; | |
605 | struct splice_pipe_desc spd = { | |
606 | .pages = pages, | |
607 | .partial = partial, | |
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 (pipe->buffers > PIPE_DEF_BUFFERS) { | |
619 | vec = kmalloc(pipe->buffers * sizeof(struct iovec), GFP_KERNEL); | |
620 | if (!vec) | |
621 | goto shrink_ret; | |
622 | } | |
623 | ||
624 | index = *ppos >> PAGE_CACHE_SHIFT; | |
625 | offset = *ppos & ~PAGE_CACHE_MASK; | |
626 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
627 | ||
628 | for (i = 0; i < nr_pages && i < pipe->buffers && len; i++) { | |
629 | struct page *page; | |
630 | ||
631 | page = alloc_page(GFP_USER); | |
632 | error = -ENOMEM; | |
633 | if (!page) | |
634 | goto err; | |
635 | ||
636 | this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); | |
637 | vec[i].iov_base = (void __user *) page_address(page); | |
638 | vec[i].iov_len = this_len; | |
639 | spd.pages[i] = page; | |
640 | spd.nr_pages++; | |
641 | len -= this_len; | |
642 | offset = 0; | |
643 | } | |
644 | ||
645 | res = kernel_readv(in, vec, spd.nr_pages, *ppos); | |
646 | if (res < 0) { | |
647 | error = res; | |
648 | goto err; | |
649 | } | |
650 | ||
651 | error = 0; | |
652 | if (!res) | |
653 | goto err; | |
654 | ||
655 | nr_freed = 0; | |
656 | for (i = 0; i < spd.nr_pages; i++) { | |
657 | this_len = min_t(size_t, vec[i].iov_len, res); | |
658 | spd.partial[i].offset = 0; | |
659 | spd.partial[i].len = this_len; | |
660 | if (!this_len) { | |
661 | __free_page(spd.pages[i]); | |
662 | spd.pages[i] = NULL; | |
663 | nr_freed++; | |
664 | } | |
665 | res -= this_len; | |
666 | } | |
667 | spd.nr_pages -= nr_freed; | |
668 | ||
669 | res = splice_to_pipe(pipe, &spd); | |
670 | if (res > 0) | |
671 | *ppos += res; | |
672 | ||
673 | shrink_ret: | |
674 | if (vec != __vec) | |
675 | kfree(vec); | |
676 | splice_shrink_spd(pipe, &spd); | |
677 | return res; | |
678 | ||
679 | err: | |
680 | for (i = 0; i < spd.nr_pages; i++) | |
681 | __free_page(spd.pages[i]); | |
682 | ||
683 | res = error; | |
684 | goto shrink_ret; | |
685 | } | |
686 | EXPORT_SYMBOL(default_file_splice_read); | |
687 | ||
688 | /* | |
689 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' | |
690 | * using sendpage(). Return the number of bytes sent. | |
691 | */ | |
692 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, | |
693 | struct pipe_buffer *buf, struct splice_desc *sd) | |
694 | { | |
695 | struct file *file = sd->u.file; | |
696 | loff_t pos = sd->pos; | |
697 | int ret, more; | |
698 | ||
699 | ret = buf->ops->confirm(pipe, buf); | |
700 | if (!ret) { | |
701 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; | |
702 | if (file->f_op && file->f_op->sendpage) | |
703 | ret = file->f_op->sendpage(file, buf->page, buf->offset, | |
704 | sd->len, &pos, more); | |
705 | else | |
706 | ret = -EINVAL; | |
707 | } | |
708 | ||
709 | return ret; | |
710 | } | |
711 | ||
712 | /* | |
713 | * This is a little more tricky than the file -> pipe splicing. There are | |
714 | * basically three cases: | |
715 | * | |
716 | * - Destination page already exists in the address space and there | |
717 | * are users of it. For that case we have no other option that | |
718 | * copying the data. Tough luck. | |
719 | * - Destination page already exists in the address space, but there | |
720 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
721 | * through to last case. | |
722 | * - Destination page does not exist, we can add the pipe page to | |
723 | * the page cache and avoid the copy. | |
724 | * | |
725 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in | |
726 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
727 | * file address space page cache. This is possible if no one else has | |
728 | * the pipe page referenced outside of the pipe and page cache. If | |
729 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
730 | * a new page in the output file page cache and fill/dirty that. | |
731 | */ | |
732 | int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, | |
733 | struct splice_desc *sd) | |
734 | { | |
735 | struct file *file = sd->u.file; | |
736 | struct address_space *mapping = file->f_mapping; | |
737 | unsigned int offset, this_len; | |
738 | struct page *page; | |
739 | void *fsdata; | |
740 | int ret; | |
741 | ||
742 | /* | |
743 | * make sure the data in this buffer is uptodate | |
744 | */ | |
745 | ret = buf->ops->confirm(pipe, buf); | |
746 | if (unlikely(ret)) | |
747 | return ret; | |
748 | ||
749 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
750 | ||
751 | this_len = sd->len; | |
752 | if (this_len + offset > PAGE_CACHE_SIZE) | |
753 | this_len = PAGE_CACHE_SIZE - offset; | |
754 | ||
755 | ret = pagecache_write_begin(file, mapping, sd->pos, this_len, | |
756 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); | |
757 | if (unlikely(ret)) | |
758 | goto out; | |
759 | ||
760 | if (buf->page != page) { | |
761 | /* | |
762 | * Careful, ->map() uses KM_USER0! | |
763 | */ | |
764 | char *src = buf->ops->map(pipe, buf, 1); | |
765 | char *dst = kmap_atomic(page, KM_USER1); | |
766 | ||
767 | memcpy(dst + offset, src + buf->offset, this_len); | |
768 | flush_dcache_page(page); | |
769 | kunmap_atomic(dst, KM_USER1); | |
770 | buf->ops->unmap(pipe, buf, src); | |
771 | } | |
772 | ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, | |
773 | page, fsdata); | |
774 | out: | |
775 | return ret; | |
776 | } | |
777 | EXPORT_SYMBOL(pipe_to_file); | |
778 | ||
779 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) | |
780 | { | |
781 | smp_mb(); | |
782 | if (waitqueue_active(&pipe->wait)) | |
783 | wake_up_interruptible(&pipe->wait); | |
784 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
785 | } | |
786 | ||
787 | /** | |
788 | * splice_from_pipe_feed - feed available data from a pipe to a file | |
789 | * @pipe: pipe to splice from | |
790 | * @sd: information to @actor | |
791 | * @actor: handler that splices the data | |
792 | * | |
793 | * Description: | |
794 | * This function loops over the pipe and calls @actor to do the | |
795 | * actual moving of a single struct pipe_buffer to the desired | |
796 | * destination. It returns when there's no more buffers left in | |
797 | * the pipe or if the requested number of bytes (@sd->total_len) | |
798 | * have been copied. It returns a positive number (one) if the | |
799 | * pipe needs to be filled with more data, zero if the required | |
800 | * number of bytes have been copied and -errno on error. | |
801 | * | |
802 | * This, together with splice_from_pipe_{begin,end,next}, may be | |
803 | * used to implement the functionality of __splice_from_pipe() when | |
804 | * locking is required around copying the pipe buffers to the | |
805 | * destination. | |
806 | */ | |
807 | int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
808 | splice_actor *actor) | |
809 | { | |
810 | int ret; | |
811 | ||
812 | while (pipe->nrbufs) { | |
813 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
814 | const struct pipe_buf_operations *ops = buf->ops; | |
815 | ||
816 | sd->len = buf->len; | |
817 | if (sd->len > sd->total_len) | |
818 | sd->len = sd->total_len; | |
819 | ||
820 | ret = actor(pipe, buf, sd); | |
821 | if (ret <= 0) { | |
822 | if (ret == -ENODATA) | |
823 | ret = 0; | |
824 | return ret; | |
825 | } | |
826 | buf->offset += ret; | |
827 | buf->len -= ret; | |
828 | ||
829 | sd->num_spliced += ret; | |
830 | sd->len -= ret; | |
831 | sd->pos += ret; | |
832 | sd->total_len -= ret; | |
833 | ||
834 | if (!buf->len) { | |
835 | buf->ops = NULL; | |
836 | ops->release(pipe, buf); | |
837 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); | |
838 | pipe->nrbufs--; | |
839 | if (pipe->inode) | |
840 | sd->need_wakeup = true; | |
841 | } | |
842 | ||
843 | if (!sd->total_len) | |
844 | return 0; | |
845 | } | |
846 | ||
847 | return 1; | |
848 | } | |
849 | EXPORT_SYMBOL(splice_from_pipe_feed); | |
850 | ||
851 | /** | |
852 | * splice_from_pipe_next - wait for some data to splice from | |
853 | * @pipe: pipe to splice from | |
854 | * @sd: information about the splice operation | |
855 | * | |
856 | * Description: | |
857 | * This function will wait for some data and return a positive | |
858 | * value (one) if pipe buffers are available. It will return zero | |
859 | * or -errno if no more data needs to be spliced. | |
860 | */ | |
861 | int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) | |
862 | { | |
863 | while (!pipe->nrbufs) { | |
864 | if (!pipe->writers) | |
865 | return 0; | |
866 | ||
867 | if (!pipe->waiting_writers && sd->num_spliced) | |
868 | return 0; | |
869 | ||
870 | if (sd->flags & SPLICE_F_NONBLOCK) | |
871 | return -EAGAIN; | |
872 | ||
873 | if (signal_pending(current)) | |
874 | return -ERESTARTSYS; | |
875 | ||
876 | if (sd->need_wakeup) { | |
877 | wakeup_pipe_writers(pipe); | |
878 | sd->need_wakeup = false; | |
879 | } | |
880 | ||
881 | pipe_wait(pipe); | |
882 | } | |
883 | ||
884 | return 1; | |
885 | } | |
886 | EXPORT_SYMBOL(splice_from_pipe_next); | |
887 | ||
888 | /** | |
889 | * splice_from_pipe_begin - start splicing from pipe | |
890 | * @sd: information about the splice operation | |
891 | * | |
892 | * Description: | |
893 | * This function should be called before a loop containing | |
894 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
895 | * initialize the necessary fields of @sd. | |
896 | */ | |
897 | void splice_from_pipe_begin(struct splice_desc *sd) | |
898 | { | |
899 | sd->num_spliced = 0; | |
900 | sd->need_wakeup = false; | |
901 | } | |
902 | EXPORT_SYMBOL(splice_from_pipe_begin); | |
903 | ||
904 | /** | |
905 | * splice_from_pipe_end - finish splicing from pipe | |
906 | * @pipe: pipe to splice from | |
907 | * @sd: information about the splice operation | |
908 | * | |
909 | * Description: | |
910 | * This function will wake up pipe writers if necessary. It should | |
911 | * be called after a loop containing splice_from_pipe_next() and | |
912 | * splice_from_pipe_feed(). | |
913 | */ | |
914 | void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) | |
915 | { | |
916 | if (sd->need_wakeup) | |
917 | wakeup_pipe_writers(pipe); | |
918 | } | |
919 | EXPORT_SYMBOL(splice_from_pipe_end); | |
920 | ||
921 | /** | |
922 | * __splice_from_pipe - splice data from a pipe to given actor | |
923 | * @pipe: pipe to splice from | |
924 | * @sd: information to @actor | |
925 | * @actor: handler that splices the data | |
926 | * | |
927 | * Description: | |
928 | * This function does little more than loop over the pipe and call | |
929 | * @actor to do the actual moving of a single struct pipe_buffer to | |
930 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
931 | * pipe_to_user. | |
932 | * | |
933 | */ | |
934 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
935 | splice_actor *actor) | |
936 | { | |
937 | int ret; | |
938 | ||
939 | splice_from_pipe_begin(sd); | |
940 | do { | |
941 | ret = splice_from_pipe_next(pipe, sd); | |
942 | if (ret > 0) | |
943 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
944 | } while (ret > 0); | |
945 | splice_from_pipe_end(pipe, sd); | |
946 | ||
947 | return sd->num_spliced ? sd->num_spliced : ret; | |
948 | } | |
949 | EXPORT_SYMBOL(__splice_from_pipe); | |
950 | ||
951 | /** | |
952 | * splice_from_pipe - splice data from a pipe to a file | |
953 | * @pipe: pipe to splice from | |
954 | * @out: file to splice to | |
955 | * @ppos: position in @out | |
956 | * @len: how many bytes to splice | |
957 | * @flags: splice modifier flags | |
958 | * @actor: handler that splices the data | |
959 | * | |
960 | * Description: | |
961 | * See __splice_from_pipe. This function locks the pipe inode, | |
962 | * otherwise it's identical to __splice_from_pipe(). | |
963 | * | |
964 | */ | |
965 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, | |
966 | loff_t *ppos, size_t len, unsigned int flags, | |
967 | splice_actor *actor) | |
968 | { | |
969 | ssize_t ret; | |
970 | struct splice_desc sd = { | |
971 | .total_len = len, | |
972 | .flags = flags, | |
973 | .pos = *ppos, | |
974 | .u.file = out, | |
975 | }; | |
976 | ||
977 | pipe_lock(pipe); | |
978 | ret = __splice_from_pipe(pipe, &sd, actor); | |
979 | pipe_unlock(pipe); | |
980 | ||
981 | return ret; | |
982 | } | |
983 | ||
984 | /** | |
985 | * generic_file_splice_write - splice data from a pipe to a file | |
986 | * @pipe: pipe info | |
987 | * @out: file to write to | |
988 | * @ppos: position in @out | |
989 | * @len: number of bytes to splice | |
990 | * @flags: splice modifier flags | |
991 | * | |
992 | * Description: | |
993 | * Will either move or copy pages (determined by @flags options) from | |
994 | * the given pipe inode to the given file. | |
995 | * | |
996 | */ | |
997 | ssize_t | |
998 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
999 | loff_t *ppos, size_t len, unsigned int flags) | |
1000 | { | |
1001 | struct address_space *mapping = out->f_mapping; | |
1002 | struct inode *inode = mapping->host; | |
1003 | struct splice_desc sd = { | |
1004 | .total_len = len, | |
1005 | .flags = flags, | |
1006 | .pos = *ppos, | |
1007 | .u.file = out, | |
1008 | }; | |
1009 | ssize_t ret; | |
1010 | ||
1011 | pipe_lock(pipe); | |
1012 | ||
1013 | splice_from_pipe_begin(&sd); | |
1014 | do { | |
1015 | ret = splice_from_pipe_next(pipe, &sd); | |
1016 | if (ret <= 0) | |
1017 | break; | |
1018 | ||
1019 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); | |
1020 | ret = file_remove_suid(out); | |
1021 | if (!ret) { | |
1022 | file_update_time(out); | |
1023 | ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file); | |
1024 | } | |
1025 | mutex_unlock(&inode->i_mutex); | |
1026 | } while (ret > 0); | |
1027 | splice_from_pipe_end(pipe, &sd); | |
1028 | ||
1029 | pipe_unlock(pipe); | |
1030 | ||
1031 | if (sd.num_spliced) | |
1032 | ret = sd.num_spliced; | |
1033 | ||
1034 | if (ret > 0) { | |
1035 | unsigned long nr_pages; | |
1036 | int err; | |
1037 | ||
1038 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1039 | ||
1040 | err = generic_write_sync(out, *ppos, ret); | |
1041 | if (err) | |
1042 | ret = err; | |
1043 | else | |
1044 | *ppos += ret; | |
1045 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); | |
1046 | } | |
1047 | ||
1048 | return ret; | |
1049 | } | |
1050 | ||
1051 | EXPORT_SYMBOL(generic_file_splice_write); | |
1052 | ||
1053 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, | |
1054 | struct splice_desc *sd) | |
1055 | { | |
1056 | int ret; | |
1057 | void *data; | |
1058 | ||
1059 | ret = buf->ops->confirm(pipe, buf); | |
1060 | if (ret) | |
1061 | return ret; | |
1062 | ||
1063 | data = buf->ops->map(pipe, buf, 0); | |
1064 | ret = kernel_write(sd->u.file, data + buf->offset, sd->len, sd->pos); | |
1065 | buf->ops->unmap(pipe, buf, data); | |
1066 | ||
1067 | return ret; | |
1068 | } | |
1069 | ||
1070 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, | |
1071 | struct file *out, loff_t *ppos, | |
1072 | size_t len, unsigned int flags) | |
1073 | { | |
1074 | ssize_t ret; | |
1075 | ||
1076 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); | |
1077 | if (ret > 0) | |
1078 | *ppos += ret; | |
1079 | ||
1080 | return ret; | |
1081 | } | |
1082 | ||
1083 | /** | |
1084 | * generic_splice_sendpage - splice data from a pipe to a socket | |
1085 | * @pipe: pipe to splice from | |
1086 | * @out: socket to write to | |
1087 | * @ppos: position in @out | |
1088 | * @len: number of bytes to splice | |
1089 | * @flags: splice modifier flags | |
1090 | * | |
1091 | * Description: | |
1092 | * Will send @len bytes from the pipe to a network socket. No data copying | |
1093 | * is involved. | |
1094 | * | |
1095 | */ | |
1096 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, | |
1097 | loff_t *ppos, size_t len, unsigned int flags) | |
1098 | { | |
1099 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); | |
1100 | } | |
1101 | ||
1102 | EXPORT_SYMBOL(generic_splice_sendpage); | |
1103 | ||
1104 | /* | |
1105 | * Attempt to initiate a splice from pipe to file. | |
1106 | */ | |
1107 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, | |
1108 | loff_t *ppos, size_t len, unsigned int flags) | |
1109 | { | |
1110 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, | |
1111 | loff_t *, size_t, unsigned int); | |
1112 | int ret; | |
1113 | ||
1114 | if (unlikely(!(out->f_mode & FMODE_WRITE))) | |
1115 | return -EBADF; | |
1116 | ||
1117 | if (unlikely(out->f_flags & O_APPEND)) | |
1118 | return -EINVAL; | |
1119 | ||
1120 | ret = rw_verify_area(WRITE, out, ppos, len); | |
1121 | if (unlikely(ret < 0)) | |
1122 | return ret; | |
1123 | ||
1124 | if (out->f_op && out->f_op->splice_write) | |
1125 | splice_write = out->f_op->splice_write; | |
1126 | else | |
1127 | splice_write = default_file_splice_write; | |
1128 | ||
1129 | return splice_write(pipe, out, ppos, len, flags); | |
1130 | } | |
1131 | ||
1132 | /* | |
1133 | * Attempt to initiate a splice from a file to a pipe. | |
1134 | */ | |
1135 | static long do_splice_to(struct file *in, loff_t *ppos, | |
1136 | struct pipe_inode_info *pipe, size_t len, | |
1137 | unsigned int flags) | |
1138 | { | |
1139 | ssize_t (*splice_read)(struct file *, loff_t *, | |
1140 | struct pipe_inode_info *, size_t, unsigned int); | |
1141 | int ret; | |
1142 | ||
1143 | if (unlikely(!(in->f_mode & FMODE_READ))) | |
1144 | return -EBADF; | |
1145 | ||
1146 | ret = rw_verify_area(READ, in, ppos, len); | |
1147 | if (unlikely(ret < 0)) | |
1148 | return ret; | |
1149 | ||
1150 | if (in->f_op && in->f_op->splice_read) | |
1151 | splice_read = in->f_op->splice_read; | |
1152 | else | |
1153 | splice_read = default_file_splice_read; | |
1154 | ||
1155 | return splice_read(in, ppos, pipe, len, flags); | |
1156 | } | |
1157 | ||
1158 | /** | |
1159 | * splice_direct_to_actor - splices data directly between two non-pipes | |
1160 | * @in: file to splice from | |
1161 | * @sd: actor information on where to splice to | |
1162 | * @actor: handles the data splicing | |
1163 | * | |
1164 | * Description: | |
1165 | * This is a special case helper to splice directly between two | |
1166 | * points, without requiring an explicit pipe. Internally an allocated | |
1167 | * pipe is cached in the process, and reused during the lifetime of | |
1168 | * that process. | |
1169 | * | |
1170 | */ | |
1171 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
1172 | splice_direct_actor *actor) | |
1173 | { | |
1174 | struct pipe_inode_info *pipe; | |
1175 | long ret, bytes; | |
1176 | umode_t i_mode; | |
1177 | size_t len; | |
1178 | int i, flags; | |
1179 | ||
1180 | /* | |
1181 | * We require the input being a regular file, as we don't want to | |
1182 | * randomly drop data for eg socket -> socket splicing. Use the | |
1183 | * piped splicing for that! | |
1184 | */ | |
1185 | i_mode = in->f_path.dentry->d_inode->i_mode; | |
1186 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
1187 | return -EINVAL; | |
1188 | ||
1189 | /* | |
1190 | * neither in nor out is a pipe, setup an internal pipe attached to | |
1191 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
1192 | */ | |
1193 | pipe = current->splice_pipe; | |
1194 | if (unlikely(!pipe)) { | |
1195 | pipe = alloc_pipe_info(NULL); | |
1196 | if (!pipe) | |
1197 | return -ENOMEM; | |
1198 | ||
1199 | /* | |
1200 | * We don't have an immediate reader, but we'll read the stuff | |
1201 | * out of the pipe right after the splice_to_pipe(). So set | |
1202 | * PIPE_READERS appropriately. | |
1203 | */ | |
1204 | pipe->readers = 1; | |
1205 | ||
1206 | current->splice_pipe = pipe; | |
1207 | } | |
1208 | ||
1209 | /* | |
1210 | * Do the splice. | |
1211 | */ | |
1212 | ret = 0; | |
1213 | bytes = 0; | |
1214 | len = sd->total_len; | |
1215 | flags = sd->flags; | |
1216 | ||
1217 | /* | |
1218 | * Don't block on output, we have to drain the direct pipe. | |
1219 | */ | |
1220 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
1221 | ||
1222 | while (len) { | |
1223 | size_t read_len; | |
1224 | loff_t pos = sd->pos, prev_pos = pos; | |
1225 | ||
1226 | ret = do_splice_to(in, &pos, pipe, len, flags); | |
1227 | if (unlikely(ret <= 0)) | |
1228 | goto out_release; | |
1229 | ||
1230 | read_len = ret; | |
1231 | sd->total_len = read_len; | |
1232 | ||
1233 | /* | |
1234 | * NOTE: nonblocking mode only applies to the input. We | |
1235 | * must not do the output in nonblocking mode as then we | |
1236 | * could get stuck data in the internal pipe: | |
1237 | */ | |
1238 | ret = actor(pipe, sd); | |
1239 | if (unlikely(ret <= 0)) { | |
1240 | sd->pos = prev_pos; | |
1241 | goto out_release; | |
1242 | } | |
1243 | ||
1244 | bytes += ret; | |
1245 | len -= ret; | |
1246 | sd->pos = pos; | |
1247 | ||
1248 | if (ret < read_len) { | |
1249 | sd->pos = prev_pos + ret; | |
1250 | goto out_release; | |
1251 | } | |
1252 | } | |
1253 | ||
1254 | done: | |
1255 | pipe->nrbufs = pipe->curbuf = 0; | |
1256 | file_accessed(in); | |
1257 | return bytes; | |
1258 | ||
1259 | out_release: | |
1260 | /* | |
1261 | * If we did an incomplete transfer we must release | |
1262 | * the pipe buffers in question: | |
1263 | */ | |
1264 | for (i = 0; i < pipe->buffers; i++) { | |
1265 | struct pipe_buffer *buf = pipe->bufs + i; | |
1266 | ||
1267 | if (buf->ops) { | |
1268 | buf->ops->release(pipe, buf); | |
1269 | buf->ops = NULL; | |
1270 | } | |
1271 | } | |
1272 | ||
1273 | if (!bytes) | |
1274 | bytes = ret; | |
1275 | ||
1276 | goto done; | |
1277 | } | |
1278 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1279 | ||
1280 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1281 | struct splice_desc *sd) | |
1282 | { | |
1283 | struct file *file = sd->u.file; | |
1284 | ||
1285 | return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags); | |
1286 | } | |
1287 | ||
1288 | /** | |
1289 | * do_splice_direct - splices data directly between two files | |
1290 | * @in: file to splice from | |
1291 | * @ppos: input file offset | |
1292 | * @out: file to splice to | |
1293 | * @len: number of bytes to splice | |
1294 | * @flags: splice modifier flags | |
1295 | * | |
1296 | * Description: | |
1297 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1298 | * doing it in the application would incur an extra system call | |
1299 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1300 | * can splice directly through a process-private pipe. | |
1301 | * | |
1302 | */ | |
1303 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, | |
1304 | size_t len, unsigned int flags) | |
1305 | { | |
1306 | struct splice_desc sd = { | |
1307 | .len = len, | |
1308 | .total_len = len, | |
1309 | .flags = flags, | |
1310 | .pos = *ppos, | |
1311 | .u.file = out, | |
1312 | }; | |
1313 | long ret; | |
1314 | ||
1315 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); | |
1316 | if (ret > 0) | |
1317 | *ppos = sd.pos; | |
1318 | ||
1319 | return ret; | |
1320 | } | |
1321 | ||
1322 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1323 | struct pipe_inode_info *opipe, | |
1324 | size_t len, unsigned int flags); | |
1325 | /* | |
1326 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same | |
1327 | * location, so checking ->i_pipe is not enough to verify that this is a | |
1328 | * pipe. | |
1329 | */ | |
1330 | static inline struct pipe_inode_info *pipe_info(struct inode *inode) | |
1331 | { | |
1332 | if (S_ISFIFO(inode->i_mode)) | |
1333 | return inode->i_pipe; | |
1334 | ||
1335 | return NULL; | |
1336 | } | |
1337 | ||
1338 | /* | |
1339 | * Determine where to splice to/from. | |
1340 | */ | |
1341 | static long do_splice(struct file *in, loff_t __user *off_in, | |
1342 | struct file *out, loff_t __user *off_out, | |
1343 | size_t len, unsigned int flags) | |
1344 | { | |
1345 | struct pipe_inode_info *ipipe; | |
1346 | struct pipe_inode_info *opipe; | |
1347 | loff_t offset, *off; | |
1348 | long ret; | |
1349 | ||
1350 | ipipe = pipe_info(in->f_path.dentry->d_inode); | |
1351 | opipe = pipe_info(out->f_path.dentry->d_inode); | |
1352 | ||
1353 | if (ipipe && opipe) { | |
1354 | if (off_in || off_out) | |
1355 | return -ESPIPE; | |
1356 | ||
1357 | if (!(in->f_mode & FMODE_READ)) | |
1358 | return -EBADF; | |
1359 | ||
1360 | if (!(out->f_mode & FMODE_WRITE)) | |
1361 | return -EBADF; | |
1362 | ||
1363 | /* Splicing to self would be fun, but... */ | |
1364 | if (ipipe == opipe) | |
1365 | return -EINVAL; | |
1366 | ||
1367 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); | |
1368 | } | |
1369 | ||
1370 | if (ipipe) { | |
1371 | if (off_in) | |
1372 | return -ESPIPE; | |
1373 | if (off_out) { | |
1374 | if (!out->f_op || !out->f_op->llseek || | |
1375 | out->f_op->llseek == no_llseek) | |
1376 | return -EINVAL; | |
1377 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) | |
1378 | return -EFAULT; | |
1379 | off = &offset; | |
1380 | } else | |
1381 | off = &out->f_pos; | |
1382 | ||
1383 | ret = do_splice_from(ipipe, out, off, len, flags); | |
1384 | ||
1385 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
1386 | ret = -EFAULT; | |
1387 | ||
1388 | return ret; | |
1389 | } | |
1390 | ||
1391 | if (opipe) { | |
1392 | if (off_out) | |
1393 | return -ESPIPE; | |
1394 | if (off_in) { | |
1395 | if (!in->f_op || !in->f_op->llseek || | |
1396 | in->f_op->llseek == no_llseek) | |
1397 | return -EINVAL; | |
1398 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) | |
1399 | return -EFAULT; | |
1400 | off = &offset; | |
1401 | } else | |
1402 | off = &in->f_pos; | |
1403 | ||
1404 | ret = do_splice_to(in, off, opipe, len, flags); | |
1405 | ||
1406 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
1407 | ret = -EFAULT; | |
1408 | ||
1409 | return ret; | |
1410 | } | |
1411 | ||
1412 | return -EINVAL; | |
1413 | } | |
1414 | ||
1415 | /* | |
1416 | * Map an iov into an array of pages and offset/length tupples. With the | |
1417 | * partial_page structure, we can map several non-contiguous ranges into | |
1418 | * our ones pages[] map instead of splitting that operation into pieces. | |
1419 | * Could easily be exported as a generic helper for other users, in which | |
1420 | * case one would probably want to add a 'max_nr_pages' parameter as well. | |
1421 | */ | |
1422 | static int get_iovec_page_array(const struct iovec __user *iov, | |
1423 | unsigned int nr_vecs, struct page **pages, | |
1424 | struct partial_page *partial, int aligned, | |
1425 | unsigned int pipe_buffers) | |
1426 | { | |
1427 | int buffers = 0, error = 0; | |
1428 | ||
1429 | while (nr_vecs) { | |
1430 | unsigned long off, npages; | |
1431 | struct iovec entry; | |
1432 | void __user *base; | |
1433 | size_t len; | |
1434 | int i; | |
1435 | ||
1436 | error = -EFAULT; | |
1437 | if (copy_from_user(&entry, iov, sizeof(entry))) | |
1438 | break; | |
1439 | ||
1440 | base = entry.iov_base; | |
1441 | len = entry.iov_len; | |
1442 | ||
1443 | /* | |
1444 | * Sanity check this iovec. 0 read succeeds. | |
1445 | */ | |
1446 | error = 0; | |
1447 | if (unlikely(!len)) | |
1448 | break; | |
1449 | error = -EFAULT; | |
1450 | if (!access_ok(VERIFY_READ, base, len)) | |
1451 | break; | |
1452 | ||
1453 | /* | |
1454 | * Get this base offset and number of pages, then map | |
1455 | * in the user pages. | |
1456 | */ | |
1457 | off = (unsigned long) base & ~PAGE_MASK; | |
1458 | ||
1459 | /* | |
1460 | * If asked for alignment, the offset must be zero and the | |
1461 | * length a multiple of the PAGE_SIZE. | |
1462 | */ | |
1463 | error = -EINVAL; | |
1464 | if (aligned && (off || len & ~PAGE_MASK)) | |
1465 | break; | |
1466 | ||
1467 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
1468 | if (npages > pipe_buffers - buffers) | |
1469 | npages = pipe_buffers - buffers; | |
1470 | ||
1471 | error = get_user_pages_fast((unsigned long)base, npages, | |
1472 | 0, &pages[buffers]); | |
1473 | ||
1474 | if (unlikely(error <= 0)) | |
1475 | break; | |
1476 | ||
1477 | /* | |
1478 | * Fill this contiguous range into the partial page map. | |
1479 | */ | |
1480 | for (i = 0; i < error; i++) { | |
1481 | const int plen = min_t(size_t, len, PAGE_SIZE - off); | |
1482 | ||
1483 | partial[buffers].offset = off; | |
1484 | partial[buffers].len = plen; | |
1485 | ||
1486 | off = 0; | |
1487 | len -= plen; | |
1488 | buffers++; | |
1489 | } | |
1490 | ||
1491 | /* | |
1492 | * We didn't complete this iov, stop here since it probably | |
1493 | * means we have to move some of this into a pipe to | |
1494 | * be able to continue. | |
1495 | */ | |
1496 | if (len) | |
1497 | break; | |
1498 | ||
1499 | /* | |
1500 | * Don't continue if we mapped fewer pages than we asked for, | |
1501 | * or if we mapped the max number of pages that we have | |
1502 | * room for. | |
1503 | */ | |
1504 | if (error < npages || buffers == pipe_buffers) | |
1505 | break; | |
1506 | ||
1507 | nr_vecs--; | |
1508 | iov++; | |
1509 | } | |
1510 | ||
1511 | if (buffers) | |
1512 | return buffers; | |
1513 | ||
1514 | return error; | |
1515 | } | |
1516 | ||
1517 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, | |
1518 | struct splice_desc *sd) | |
1519 | { | |
1520 | char *src; | |
1521 | int ret; | |
1522 | ||
1523 | ret = buf->ops->confirm(pipe, buf); | |
1524 | if (unlikely(ret)) | |
1525 | return ret; | |
1526 | ||
1527 | /* | |
1528 | * See if we can use the atomic maps, by prefaulting in the | |
1529 | * pages and doing an atomic copy | |
1530 | */ | |
1531 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { | |
1532 | src = buf->ops->map(pipe, buf, 1); | |
1533 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, | |
1534 | sd->len); | |
1535 | buf->ops->unmap(pipe, buf, src); | |
1536 | if (!ret) { | |
1537 | ret = sd->len; | |
1538 | goto out; | |
1539 | } | |
1540 | } | |
1541 | ||
1542 | /* | |
1543 | * No dice, use slow non-atomic map and copy | |
1544 | */ | |
1545 | src = buf->ops->map(pipe, buf, 0); | |
1546 | ||
1547 | ret = sd->len; | |
1548 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) | |
1549 | ret = -EFAULT; | |
1550 | ||
1551 | buf->ops->unmap(pipe, buf, src); | |
1552 | out: | |
1553 | if (ret > 0) | |
1554 | sd->u.userptr += ret; | |
1555 | return ret; | |
1556 | } | |
1557 | ||
1558 | /* | |
1559 | * For lack of a better implementation, implement vmsplice() to userspace | |
1560 | * as a simple copy of the pipes pages to the user iov. | |
1561 | */ | |
1562 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, | |
1563 | unsigned long nr_segs, unsigned int flags) | |
1564 | { | |
1565 | struct pipe_inode_info *pipe; | |
1566 | struct splice_desc sd; | |
1567 | ssize_t size; | |
1568 | int error; | |
1569 | long ret; | |
1570 | ||
1571 | pipe = pipe_info(file->f_path.dentry->d_inode); | |
1572 | if (!pipe) | |
1573 | return -EBADF; | |
1574 | ||
1575 | pipe_lock(pipe); | |
1576 | ||
1577 | error = ret = 0; | |
1578 | while (nr_segs) { | |
1579 | void __user *base; | |
1580 | size_t len; | |
1581 | ||
1582 | /* | |
1583 | * Get user address base and length for this iovec. | |
1584 | */ | |
1585 | error = get_user(base, &iov->iov_base); | |
1586 | if (unlikely(error)) | |
1587 | break; | |
1588 | error = get_user(len, &iov->iov_len); | |
1589 | if (unlikely(error)) | |
1590 | break; | |
1591 | ||
1592 | /* | |
1593 | * Sanity check this iovec. 0 read succeeds. | |
1594 | */ | |
1595 | if (unlikely(!len)) | |
1596 | break; | |
1597 | if (unlikely(!base)) { | |
1598 | error = -EFAULT; | |
1599 | break; | |
1600 | } | |
1601 | ||
1602 | if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { | |
1603 | error = -EFAULT; | |
1604 | break; | |
1605 | } | |
1606 | ||
1607 | sd.len = 0; | |
1608 | sd.total_len = len; | |
1609 | sd.flags = flags; | |
1610 | sd.u.userptr = base; | |
1611 | sd.pos = 0; | |
1612 | ||
1613 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1614 | if (size < 0) { | |
1615 | if (!ret) | |
1616 | ret = size; | |
1617 | ||
1618 | break; | |
1619 | } | |
1620 | ||
1621 | ret += size; | |
1622 | ||
1623 | if (size < len) | |
1624 | break; | |
1625 | ||
1626 | nr_segs--; | |
1627 | iov++; | |
1628 | } | |
1629 | ||
1630 | pipe_unlock(pipe); | |
1631 | ||
1632 | if (!ret) | |
1633 | ret = error; | |
1634 | ||
1635 | return ret; | |
1636 | } | |
1637 | ||
1638 | /* | |
1639 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1640 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1641 | * to file). In both cases the output is a pipe, naturally. | |
1642 | */ | |
1643 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, | |
1644 | unsigned long nr_segs, unsigned int flags) | |
1645 | { | |
1646 | struct pipe_inode_info *pipe; | |
1647 | struct page *pages[PIPE_DEF_BUFFERS]; | |
1648 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1649 | struct splice_pipe_desc spd = { | |
1650 | .pages = pages, | |
1651 | .partial = partial, | |
1652 | .flags = flags, | |
1653 | .ops = &user_page_pipe_buf_ops, | |
1654 | .spd_release = spd_release_page, | |
1655 | }; | |
1656 | long ret; | |
1657 | ||
1658 | pipe = pipe_info(file->f_path.dentry->d_inode); | |
1659 | if (!pipe) | |
1660 | return -EBADF; | |
1661 | ||
1662 | if (splice_grow_spd(pipe, &spd)) | |
1663 | return -ENOMEM; | |
1664 | ||
1665 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, | |
1666 | spd.partial, flags & SPLICE_F_GIFT, | |
1667 | pipe->buffers); | |
1668 | if (spd.nr_pages <= 0) | |
1669 | ret = spd.nr_pages; | |
1670 | else | |
1671 | ret = splice_to_pipe(pipe, &spd); | |
1672 | ||
1673 | splice_shrink_spd(pipe, &spd); | |
1674 | return ret; | |
1675 | } | |
1676 | ||
1677 | /* | |
1678 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1679 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1680 | * operation that can be supported without any funky alignment restrictions | |
1681 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1682 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1683 | * solutions for that: | |
1684 | * | |
1685 | * - memcpy() the data internally, at which point we might as well just | |
1686 | * do a regular read() on the buffer anyway. | |
1687 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1688 | * has restriction limitations on both ends of the pipe). | |
1689 | * | |
1690 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1691 | * | |
1692 | */ | |
1693 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, | |
1694 | unsigned long, nr_segs, unsigned int, flags) | |
1695 | { | |
1696 | struct file *file; | |
1697 | long error; | |
1698 | int fput; | |
1699 | ||
1700 | if (unlikely(nr_segs > UIO_MAXIOV)) | |
1701 | return -EINVAL; | |
1702 | else if (unlikely(!nr_segs)) | |
1703 | return 0; | |
1704 | ||
1705 | error = -EBADF; | |
1706 | file = fget_light(fd, &fput); | |
1707 | if (file) { | |
1708 | if (file->f_mode & FMODE_WRITE) | |
1709 | error = vmsplice_to_pipe(file, iov, nr_segs, flags); | |
1710 | else if (file->f_mode & FMODE_READ) | |
1711 | error = vmsplice_to_user(file, iov, nr_segs, flags); | |
1712 | ||
1713 | fput_light(file, fput); | |
1714 | } | |
1715 | ||
1716 | return error; | |
1717 | } | |
1718 | ||
1719 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, | |
1720 | int, fd_out, loff_t __user *, off_out, | |
1721 | size_t, len, unsigned int, flags) | |
1722 | { | |
1723 | long error; | |
1724 | struct file *in, *out; | |
1725 | int fput_in, fput_out; | |
1726 | ||
1727 | if (unlikely(!len)) | |
1728 | return 0; | |
1729 | ||
1730 | error = -EBADF; | |
1731 | in = fget_light(fd_in, &fput_in); | |
1732 | if (in) { | |
1733 | if (in->f_mode & FMODE_READ) { | |
1734 | out = fget_light(fd_out, &fput_out); | |
1735 | if (out) { | |
1736 | if (out->f_mode & FMODE_WRITE) | |
1737 | error = do_splice(in, off_in, | |
1738 | out, off_out, | |
1739 | len, flags); | |
1740 | fput_light(out, fput_out); | |
1741 | } | |
1742 | } | |
1743 | ||
1744 | fput_light(in, fput_in); | |
1745 | } | |
1746 | ||
1747 | return error; | |
1748 | } | |
1749 | ||
1750 | /* | |
1751 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1752 | * return an appropriate error. | |
1753 | */ | |
1754 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1755 | { | |
1756 | int ret; | |
1757 | ||
1758 | /* | |
1759 | * Check ->nrbufs without the inode lock first. This function | |
1760 | * is speculative anyways, so missing one is ok. | |
1761 | */ | |
1762 | if (pipe->nrbufs) | |
1763 | return 0; | |
1764 | ||
1765 | ret = 0; | |
1766 | pipe_lock(pipe); | |
1767 | ||
1768 | while (!pipe->nrbufs) { | |
1769 | if (signal_pending(current)) { | |
1770 | ret = -ERESTARTSYS; | |
1771 | break; | |
1772 | } | |
1773 | if (!pipe->writers) | |
1774 | break; | |
1775 | if (!pipe->waiting_writers) { | |
1776 | if (flags & SPLICE_F_NONBLOCK) { | |
1777 | ret = -EAGAIN; | |
1778 | break; | |
1779 | } | |
1780 | } | |
1781 | pipe_wait(pipe); | |
1782 | } | |
1783 | ||
1784 | pipe_unlock(pipe); | |
1785 | return ret; | |
1786 | } | |
1787 | ||
1788 | /* | |
1789 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1790 | * return an appropriate error. | |
1791 | */ | |
1792 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1793 | { | |
1794 | int ret; | |
1795 | ||
1796 | /* | |
1797 | * Check ->nrbufs without the inode lock first. This function | |
1798 | * is speculative anyways, so missing one is ok. | |
1799 | */ | |
1800 | if (pipe->nrbufs < pipe->buffers) | |
1801 | return 0; | |
1802 | ||
1803 | ret = 0; | |
1804 | pipe_lock(pipe); | |
1805 | ||
1806 | while (pipe->nrbufs >= pipe->buffers) { | |
1807 | if (!pipe->readers) { | |
1808 | send_sig(SIGPIPE, current, 0); | |
1809 | ret = -EPIPE; | |
1810 | break; | |
1811 | } | |
1812 | if (flags & SPLICE_F_NONBLOCK) { | |
1813 | ret = -EAGAIN; | |
1814 | break; | |
1815 | } | |
1816 | if (signal_pending(current)) { | |
1817 | ret = -ERESTARTSYS; | |
1818 | break; | |
1819 | } | |
1820 | pipe->waiting_writers++; | |
1821 | pipe_wait(pipe); | |
1822 | pipe->waiting_writers--; | |
1823 | } | |
1824 | ||
1825 | pipe_unlock(pipe); | |
1826 | return ret; | |
1827 | } | |
1828 | ||
1829 | /* | |
1830 | * Splice contents of ipipe to opipe. | |
1831 | */ | |
1832 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1833 | struct pipe_inode_info *opipe, | |
1834 | size_t len, unsigned int flags) | |
1835 | { | |
1836 | struct pipe_buffer *ibuf, *obuf; | |
1837 | int ret = 0, nbuf; | |
1838 | bool input_wakeup = false; | |
1839 | ||
1840 | ||
1841 | retry: | |
1842 | ret = ipipe_prep(ipipe, flags); | |
1843 | if (ret) | |
1844 | return ret; | |
1845 | ||
1846 | ret = opipe_prep(opipe, flags); | |
1847 | if (ret) | |
1848 | return ret; | |
1849 | ||
1850 | /* | |
1851 | * Potential ABBA deadlock, work around it by ordering lock | |
1852 | * grabbing by pipe info address. Otherwise two different processes | |
1853 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1854 | */ | |
1855 | pipe_double_lock(ipipe, opipe); | |
1856 | ||
1857 | do { | |
1858 | if (!opipe->readers) { | |
1859 | send_sig(SIGPIPE, current, 0); | |
1860 | if (!ret) | |
1861 | ret = -EPIPE; | |
1862 | break; | |
1863 | } | |
1864 | ||
1865 | if (!ipipe->nrbufs && !ipipe->writers) | |
1866 | break; | |
1867 | ||
1868 | /* | |
1869 | * Cannot make any progress, because either the input | |
1870 | * pipe is empty or the output pipe is full. | |
1871 | */ | |
1872 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { | |
1873 | /* Already processed some buffers, break */ | |
1874 | if (ret) | |
1875 | break; | |
1876 | ||
1877 | if (flags & SPLICE_F_NONBLOCK) { | |
1878 | ret = -EAGAIN; | |
1879 | break; | |
1880 | } | |
1881 | ||
1882 | /* | |
1883 | * We raced with another reader/writer and haven't | |
1884 | * managed to process any buffers. A zero return | |
1885 | * value means EOF, so retry instead. | |
1886 | */ | |
1887 | pipe_unlock(ipipe); | |
1888 | pipe_unlock(opipe); | |
1889 | goto retry; | |
1890 | } | |
1891 | ||
1892 | ibuf = ipipe->bufs + ipipe->curbuf; | |
1893 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
1894 | obuf = opipe->bufs + nbuf; | |
1895 | ||
1896 | if (len >= ibuf->len) { | |
1897 | /* | |
1898 | * Simply move the whole buffer from ipipe to opipe | |
1899 | */ | |
1900 | *obuf = *ibuf; | |
1901 | ibuf->ops = NULL; | |
1902 | opipe->nrbufs++; | |
1903 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); | |
1904 | ipipe->nrbufs--; | |
1905 | input_wakeup = true; | |
1906 | } else { | |
1907 | /* | |
1908 | * Get a reference to this pipe buffer, | |
1909 | * so we can copy the contents over. | |
1910 | */ | |
1911 | ibuf->ops->get(ipipe, ibuf); | |
1912 | *obuf = *ibuf; | |
1913 | ||
1914 | /* | |
1915 | * Don't inherit the gift flag, we need to | |
1916 | * prevent multiple steals of this page. | |
1917 | */ | |
1918 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1919 | ||
1920 | obuf->len = len; | |
1921 | opipe->nrbufs++; | |
1922 | ibuf->offset += obuf->len; | |
1923 | ibuf->len -= obuf->len; | |
1924 | } | |
1925 | ret += obuf->len; | |
1926 | len -= obuf->len; | |
1927 | } while (len); | |
1928 | ||
1929 | pipe_unlock(ipipe); | |
1930 | pipe_unlock(opipe); | |
1931 | ||
1932 | /* | |
1933 | * If we put data in the output pipe, wakeup any potential readers. | |
1934 | */ | |
1935 | if (ret > 0) { | |
1936 | smp_mb(); | |
1937 | if (waitqueue_active(&opipe->wait)) | |
1938 | wake_up_interruptible(&opipe->wait); | |
1939 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1940 | } | |
1941 | if (input_wakeup) | |
1942 | wakeup_pipe_writers(ipipe); | |
1943 | ||
1944 | return ret; | |
1945 | } | |
1946 | ||
1947 | /* | |
1948 | * Link contents of ipipe to opipe. | |
1949 | */ | |
1950 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1951 | struct pipe_inode_info *opipe, | |
1952 | size_t len, unsigned int flags) | |
1953 | { | |
1954 | struct pipe_buffer *ibuf, *obuf; | |
1955 | int ret = 0, i = 0, nbuf; | |
1956 | ||
1957 | /* | |
1958 | * Potential ABBA deadlock, work around it by ordering lock | |
1959 | * grabbing by pipe info address. Otherwise two different processes | |
1960 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1961 | */ | |
1962 | pipe_double_lock(ipipe, opipe); | |
1963 | ||
1964 | do { | |
1965 | if (!opipe->readers) { | |
1966 | send_sig(SIGPIPE, current, 0); | |
1967 | if (!ret) | |
1968 | ret = -EPIPE; | |
1969 | break; | |
1970 | } | |
1971 | ||
1972 | /* | |
1973 | * If we have iterated all input buffers or ran out of | |
1974 | * output room, break. | |
1975 | */ | |
1976 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) | |
1977 | break; | |
1978 | ||
1979 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); | |
1980 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
1981 | ||
1982 | /* | |
1983 | * Get a reference to this pipe buffer, | |
1984 | * so we can copy the contents over. | |
1985 | */ | |
1986 | ibuf->ops->get(ipipe, ibuf); | |
1987 | ||
1988 | obuf = opipe->bufs + nbuf; | |
1989 | *obuf = *ibuf; | |
1990 | ||
1991 | /* | |
1992 | * Don't inherit the gift flag, we need to | |
1993 | * prevent multiple steals of this page. | |
1994 | */ | |
1995 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1996 | ||
1997 | if (obuf->len > len) | |
1998 | obuf->len = len; | |
1999 | ||
2000 | opipe->nrbufs++; | |
2001 | ret += obuf->len; | |
2002 | len -= obuf->len; | |
2003 | i++; | |
2004 | } while (len); | |
2005 | ||
2006 | /* | |
2007 | * return EAGAIN if we have the potential of some data in the | |
2008 | * future, otherwise just return 0 | |
2009 | */ | |
2010 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
2011 | ret = -EAGAIN; | |
2012 | ||
2013 | pipe_unlock(ipipe); | |
2014 | pipe_unlock(opipe); | |
2015 | ||
2016 | /* | |
2017 | * If we put data in the output pipe, wakeup any potential readers. | |
2018 | */ | |
2019 | if (ret > 0) { | |
2020 | smp_mb(); | |
2021 | if (waitqueue_active(&opipe->wait)) | |
2022 | wake_up_interruptible(&opipe->wait); | |
2023 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
2024 | } | |
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 = pipe_info(in->f_path.dentry->d_inode); | |
2039 | struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode); | |
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 file *in; | |
2065 | int error, fput_in; | |
2066 | ||
2067 | if (unlikely(!len)) | |
2068 | return 0; | |
2069 | ||
2070 | error = -EBADF; | |
2071 | in = fget_light(fdin, &fput_in); | |
2072 | if (in) { | |
2073 | if (in->f_mode & FMODE_READ) { | |
2074 | int fput_out; | |
2075 | struct file *out = fget_light(fdout, &fput_out); | |
2076 | ||
2077 | if (out) { | |
2078 | if (out->f_mode & FMODE_WRITE) | |
2079 | error = do_tee(in, out, len, flags); | |
2080 | fput_light(out, fput_out); | |
2081 | } | |
2082 | } | |
2083 | fput_light(in, fput_in); | |
2084 | } | |
2085 | ||
2086 | return error; | |
2087 | } |