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Commit | Line | Data |
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5274f052 JA |
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 and fixing the initial implementation | |
13 | * bugs. | |
14 | * | |
15 | * Copyright (C) 2005 Jens Axboe <axboe@suse.de> | |
16 | * Copyright (C) 2005 Linus Torvalds <torvalds@osdl.org> | |
17 | * | |
18 | */ | |
19 | #include <linux/fs.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/pagemap.h> | |
22 | #include <linux/pipe_fs_i.h> | |
23 | #include <linux/mm_inline.h> | |
5abc97aa | 24 | #include <linux/swap.h> |
4f6f0bd2 JA |
25 | #include <linux/writeback.h> |
26 | #include <linux/buffer_head.h> | |
a0f06780 | 27 | #include <linux/module.h> |
4f6f0bd2 | 28 | #include <linux/syscalls.h> |
5274f052 JA |
29 | |
30 | /* | |
31 | * Passed to the actors | |
32 | */ | |
33 | struct splice_desc { | |
34 | unsigned int len, total_len; /* current and remaining length */ | |
35 | unsigned int flags; /* splice flags */ | |
36 | struct file *file; /* file to read/write */ | |
37 | loff_t pos; /* file position */ | |
38 | }; | |
39 | ||
5abc97aa JA |
40 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, |
41 | struct pipe_buffer *buf) | |
42 | { | |
43 | struct page *page = buf->page; | |
4f6f0bd2 | 44 | struct address_space *mapping = page_mapping(page); |
5abc97aa JA |
45 | |
46 | WARN_ON(!PageLocked(page)); | |
47 | WARN_ON(!PageUptodate(page)); | |
48 | ||
4f6f0bd2 JA |
49 | if (PagePrivate(page)) |
50 | try_to_release_page(page, mapping_gfp_mask(mapping)); | |
51 | ||
52 | if (!remove_mapping(mapping, page)) | |
5abc97aa JA |
53 | return 1; |
54 | ||
55 | if (PageLRU(page)) { | |
56 | struct zone *zone = page_zone(page); | |
57 | ||
58 | spin_lock_irq(&zone->lru_lock); | |
59 | BUG_ON(!PageLRU(page)); | |
60 | __ClearPageLRU(page); | |
61 | del_page_from_lru(zone, page); | |
62 | spin_unlock_irq(&zone->lru_lock); | |
63 | } | |
64 | ||
5abc97aa JA |
65 | return 0; |
66 | } | |
67 | ||
5274f052 JA |
68 | static void page_cache_pipe_buf_release(struct pipe_inode_info *info, |
69 | struct pipe_buffer *buf) | |
70 | { | |
71 | page_cache_release(buf->page); | |
72 | buf->page = NULL; | |
73 | } | |
74 | ||
75 | static void *page_cache_pipe_buf_map(struct file *file, | |
76 | struct pipe_inode_info *info, | |
77 | struct pipe_buffer *buf) | |
78 | { | |
79 | struct page *page = buf->page; | |
80 | ||
81 | lock_page(page); | |
82 | ||
83 | if (!PageUptodate(page)) { | |
84 | unlock_page(page); | |
85 | return ERR_PTR(-EIO); | |
86 | } | |
87 | ||
88 | if (!page->mapping) { | |
89 | unlock_page(page); | |
90 | return ERR_PTR(-ENODATA); | |
91 | } | |
92 | ||
93 | return kmap(buf->page); | |
94 | } | |
95 | ||
96 | static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info, | |
97 | struct pipe_buffer *buf) | |
98 | { | |
4f6f0bd2 | 99 | unlock_page(buf->page); |
5274f052 JA |
100 | kunmap(buf->page); |
101 | } | |
102 | ||
103 | static struct pipe_buf_operations page_cache_pipe_buf_ops = { | |
104 | .can_merge = 0, | |
105 | .map = page_cache_pipe_buf_map, | |
106 | .unmap = page_cache_pipe_buf_unmap, | |
107 | .release = page_cache_pipe_buf_release, | |
5abc97aa | 108 | .steal = page_cache_pipe_buf_steal, |
5274f052 JA |
109 | }; |
110 | ||
111 | static ssize_t move_to_pipe(struct inode *inode, struct page **pages, | |
112 | int nr_pages, unsigned long offset, | |
29e35094 | 113 | unsigned long len, unsigned int flags) |
5274f052 JA |
114 | { |
115 | struct pipe_inode_info *info; | |
116 | int ret, do_wakeup, i; | |
117 | ||
118 | ret = 0; | |
119 | do_wakeup = 0; | |
120 | i = 0; | |
121 | ||
122 | mutex_lock(PIPE_MUTEX(*inode)); | |
123 | ||
124 | info = inode->i_pipe; | |
125 | for (;;) { | |
126 | int bufs; | |
127 | ||
128 | if (!PIPE_READERS(*inode)) { | |
129 | send_sig(SIGPIPE, current, 0); | |
130 | if (!ret) | |
131 | ret = -EPIPE; | |
132 | break; | |
133 | } | |
134 | ||
135 | bufs = info->nrbufs; | |
136 | if (bufs < PIPE_BUFFERS) { | |
137 | int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS - 1); | |
138 | struct pipe_buffer *buf = info->bufs + newbuf; | |
139 | struct page *page = pages[i++]; | |
140 | unsigned long this_len; | |
141 | ||
142 | this_len = PAGE_CACHE_SIZE - offset; | |
143 | if (this_len > len) | |
144 | this_len = len; | |
145 | ||
146 | buf->page = page; | |
147 | buf->offset = offset; | |
148 | buf->len = this_len; | |
149 | buf->ops = &page_cache_pipe_buf_ops; | |
150 | info->nrbufs = ++bufs; | |
151 | do_wakeup = 1; | |
152 | ||
153 | ret += this_len; | |
154 | len -= this_len; | |
155 | offset = 0; | |
156 | if (!--nr_pages) | |
157 | break; | |
158 | if (!len) | |
159 | break; | |
160 | if (bufs < PIPE_BUFFERS) | |
161 | continue; | |
162 | ||
163 | break; | |
164 | } | |
165 | ||
29e35094 LT |
166 | if (flags & SPLICE_F_NONBLOCK) { |
167 | if (!ret) | |
168 | ret = -EAGAIN; | |
169 | break; | |
170 | } | |
171 | ||
5274f052 JA |
172 | if (signal_pending(current)) { |
173 | if (!ret) | |
174 | ret = -ERESTARTSYS; | |
175 | break; | |
176 | } | |
177 | ||
178 | if (do_wakeup) { | |
179 | wake_up_interruptible_sync(PIPE_WAIT(*inode)); | |
180 | kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, | |
181 | POLL_IN); | |
182 | do_wakeup = 0; | |
183 | } | |
184 | ||
185 | PIPE_WAITING_WRITERS(*inode)++; | |
186 | pipe_wait(inode); | |
187 | PIPE_WAITING_WRITERS(*inode)--; | |
188 | } | |
189 | ||
190 | mutex_unlock(PIPE_MUTEX(*inode)); | |
191 | ||
192 | if (do_wakeup) { | |
193 | wake_up_interruptible(PIPE_WAIT(*inode)); | |
194 | kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN); | |
195 | } | |
196 | ||
197 | while (i < nr_pages) | |
198 | page_cache_release(pages[i++]); | |
199 | ||
200 | return ret; | |
201 | } | |
202 | ||
203 | static int __generic_file_splice_read(struct file *in, struct inode *pipe, | |
29e35094 | 204 | size_t len, unsigned int flags) |
5274f052 JA |
205 | { |
206 | struct address_space *mapping = in->f_mapping; | |
207 | unsigned int offset, nr_pages; | |
208 | struct page *pages[PIPE_BUFFERS], *shadow[PIPE_BUFFERS]; | |
209 | struct page *page; | |
210 | pgoff_t index, pidx; | |
211 | int i, j; | |
212 | ||
213 | index = in->f_pos >> PAGE_CACHE_SHIFT; | |
214 | offset = in->f_pos & ~PAGE_CACHE_MASK; | |
215 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
216 | ||
217 | if (nr_pages > PIPE_BUFFERS) | |
218 | nr_pages = PIPE_BUFFERS; | |
219 | ||
220 | /* | |
221 | * initiate read-ahead on this page range | |
222 | */ | |
223 | do_page_cache_readahead(mapping, in, index, nr_pages); | |
224 | ||
225 | /* | |
226 | * Get as many pages from the page cache as possible.. | |
227 | * Start IO on the page cache entries we create (we | |
228 | * can assume that any pre-existing ones we find have | |
229 | * already had IO started on them). | |
230 | */ | |
231 | i = find_get_pages(mapping, index, nr_pages, pages); | |
232 | ||
233 | /* | |
234 | * common case - we found all pages and they are contiguous, | |
235 | * kick them off | |
236 | */ | |
237 | if (i && (pages[i - 1]->index == index + i - 1)) | |
238 | goto splice_them; | |
239 | ||
240 | /* | |
241 | * fill shadow[] with pages at the right locations, so we only | |
242 | * have to fill holes | |
243 | */ | |
53cd9ae8 JA |
244 | memset(shadow, 0, nr_pages * sizeof(struct page *)); |
245 | for (j = 0; j < i; j++) | |
246 | shadow[pages[j]->index - index] = pages[j]; | |
5274f052 JA |
247 | |
248 | /* | |
249 | * now fill in the holes | |
250 | */ | |
251 | for (i = 0, pidx = index; i < nr_pages; pidx++, i++) { | |
252 | int error; | |
253 | ||
254 | if (shadow[i]) | |
255 | continue; | |
256 | ||
257 | /* | |
258 | * no page there, look one up / create it | |
259 | */ | |
260 | page = find_or_create_page(mapping, pidx, | |
261 | mapping_gfp_mask(mapping)); | |
262 | if (!page) | |
263 | break; | |
264 | ||
265 | if (PageUptodate(page)) | |
266 | unlock_page(page); | |
267 | else { | |
268 | error = mapping->a_ops->readpage(in, page); | |
269 | ||
270 | if (unlikely(error)) { | |
271 | page_cache_release(page); | |
272 | break; | |
273 | } | |
274 | } | |
275 | shadow[i] = page; | |
276 | } | |
277 | ||
278 | if (!i) { | |
279 | for (i = 0; i < nr_pages; i++) { | |
280 | if (shadow[i]) | |
281 | page_cache_release(shadow[i]); | |
282 | } | |
283 | return 0; | |
284 | } | |
285 | ||
286 | memcpy(pages, shadow, i * sizeof(struct page *)); | |
287 | ||
288 | /* | |
289 | * Now we splice them into the pipe.. | |
290 | */ | |
291 | splice_them: | |
29e35094 | 292 | return move_to_pipe(pipe, pages, i, offset, len, flags); |
5274f052 JA |
293 | } |
294 | ||
295 | ssize_t generic_file_splice_read(struct file *in, struct inode *pipe, | |
296 | size_t len, unsigned int flags) | |
297 | { | |
298 | ssize_t spliced; | |
299 | int ret; | |
300 | ||
301 | ret = 0; | |
302 | spliced = 0; | |
303 | while (len) { | |
29e35094 | 304 | ret = __generic_file_splice_read(in, pipe, len, flags); |
5274f052 JA |
305 | |
306 | if (ret <= 0) | |
307 | break; | |
308 | ||
309 | in->f_pos += ret; | |
310 | len -= ret; | |
311 | spliced += ret; | |
29e35094 LT |
312 | |
313 | if (!(flags & SPLICE_F_NONBLOCK)) | |
314 | continue; | |
315 | ret = -EAGAIN; | |
316 | break; | |
5274f052 JA |
317 | } |
318 | ||
319 | if (spliced) | |
320 | return spliced; | |
321 | ||
322 | return ret; | |
323 | } | |
324 | ||
325 | /* | |
4f6f0bd2 JA |
326 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
327 | * using sendpage(). | |
5274f052 JA |
328 | */ |
329 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
330 | struct pipe_buffer *buf, struct splice_desc *sd) | |
331 | { | |
332 | struct file *file = sd->file; | |
333 | loff_t pos = sd->pos; | |
334 | unsigned int offset; | |
335 | ssize_t ret; | |
336 | void *ptr; | |
337 | ||
338 | /* | |
339 | * sub-optimal, but we are limited by the pipe ->map. we don't | |
340 | * need a kmap'ed buffer here, we just want to make sure we | |
341 | * have the page pinned if the pipe page originates from the | |
342 | * page cache | |
343 | */ | |
344 | ptr = buf->ops->map(file, info, buf); | |
345 | if (IS_ERR(ptr)) | |
346 | return PTR_ERR(ptr); | |
347 | ||
348 | offset = pos & ~PAGE_CACHE_MASK; | |
349 | ||
350 | ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos, | |
351 | sd->len < sd->total_len); | |
352 | ||
353 | buf->ops->unmap(info, buf); | |
354 | if (ret == sd->len) | |
355 | return 0; | |
356 | ||
357 | return -EIO; | |
358 | } | |
359 | ||
360 | /* | |
361 | * This is a little more tricky than the file -> pipe splicing. There are | |
362 | * basically three cases: | |
363 | * | |
364 | * - Destination page already exists in the address space and there | |
365 | * are users of it. For that case we have no other option that | |
366 | * copying the data. Tough luck. | |
367 | * - Destination page already exists in the address space, but there | |
368 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
369 | * through to last case. | |
370 | * - Destination page does not exist, we can add the pipe page to | |
371 | * the page cache and avoid the copy. | |
372 | * | |
373 | * For now we just do the slower thing and always copy pages over, it's | |
374 | * easier than migrating pages from the pipe to the target file. For the | |
375 | * case of doing file | file splicing, the migrate approach had some LRU | |
376 | * nastiness... | |
377 | */ | |
378 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
379 | struct splice_desc *sd) | |
380 | { | |
381 | struct file *file = sd->file; | |
382 | struct address_space *mapping = file->f_mapping; | |
383 | unsigned int offset; | |
384 | struct page *page; | |
5274f052 | 385 | pgoff_t index; |
5abc97aa | 386 | char *src; |
4f6f0bd2 | 387 | int ret, stolen; |
5274f052 JA |
388 | |
389 | /* | |
390 | * after this, page will be locked and unmapped | |
391 | */ | |
392 | src = buf->ops->map(file, info, buf); | |
393 | if (IS_ERR(src)) | |
394 | return PTR_ERR(src); | |
395 | ||
396 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
397 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
4f6f0bd2 | 398 | stolen = 0; |
5274f052 | 399 | |
5274f052 | 400 | /* |
5abc97aa | 401 | * reuse buf page, if SPLICE_F_MOVE is set |
5274f052 | 402 | */ |
5abc97aa JA |
403 | if (sd->flags & SPLICE_F_MOVE) { |
404 | if (buf->ops->steal(info, buf)) | |
405 | goto find_page; | |
406 | ||
407 | page = buf->page; | |
4f6f0bd2 | 408 | stolen = 1; |
5abc97aa JA |
409 | if (add_to_page_cache_lru(page, mapping, index, |
410 | mapping_gfp_mask(mapping))) | |
411 | goto find_page; | |
412 | } else { | |
413 | find_page: | |
414 | ret = -ENOMEM; | |
415 | page = find_or_create_page(mapping, index, | |
416 | mapping_gfp_mask(mapping)); | |
417 | if (!page) | |
418 | goto out; | |
419 | ||
420 | /* | |
421 | * If the page is uptodate, it is also locked. If it isn't | |
422 | * uptodate, we can mark it uptodate if we are filling the | |
423 | * full page. Otherwise we need to read it in first... | |
424 | */ | |
425 | if (!PageUptodate(page)) { | |
426 | if (sd->len < PAGE_CACHE_SIZE) { | |
427 | ret = mapping->a_ops->readpage(file, page); | |
428 | if (unlikely(ret)) | |
429 | goto out; | |
430 | ||
431 | lock_page(page); | |
432 | ||
433 | if (!PageUptodate(page)) { | |
434 | /* | |
435 | * page got invalidated, repeat | |
436 | */ | |
437 | if (!page->mapping) { | |
438 | unlock_page(page); | |
439 | page_cache_release(page); | |
440 | goto find_page; | |
441 | } | |
442 | ret = -EIO; | |
443 | goto out; | |
5274f052 | 444 | } |
5abc97aa JA |
445 | } else { |
446 | WARN_ON(!PageLocked(page)); | |
447 | SetPageUptodate(page); | |
5274f052 | 448 | } |
5274f052 JA |
449 | } |
450 | } | |
451 | ||
452 | ret = mapping->a_ops->prepare_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
453 | if (ret == AOP_TRUNCATED_PAGE) { |
454 | page_cache_release(page); | |
455 | goto find_page; | |
456 | } else if (ret) | |
5274f052 JA |
457 | goto out; |
458 | ||
4f6f0bd2 | 459 | if (!stolen) { |
5abc97aa JA |
460 | char *dst = kmap_atomic(page, KM_USER0); |
461 | ||
462 | memcpy(dst + offset, src + buf->offset, sd->len); | |
463 | flush_dcache_page(page); | |
464 | kunmap_atomic(dst, KM_USER0); | |
465 | } | |
5274f052 JA |
466 | |
467 | ret = mapping->a_ops->commit_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
468 | if (ret == AOP_TRUNCATED_PAGE) { |
469 | page_cache_release(page); | |
470 | goto find_page; | |
471 | } else if (ret) | |
5274f052 JA |
472 | goto out; |
473 | ||
4f6f0bd2 | 474 | balance_dirty_pages_ratelimited(mapping); |
5274f052 | 475 | out: |
4f6f0bd2 | 476 | if (!stolen) { |
5abc97aa | 477 | page_cache_release(page); |
4f6f0bd2 JA |
478 | unlock_page(page); |
479 | } | |
5274f052 JA |
480 | buf->ops->unmap(info, buf); |
481 | return ret; | |
482 | } | |
483 | ||
484 | typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, | |
485 | struct splice_desc *); | |
486 | ||
487 | static ssize_t move_from_pipe(struct inode *inode, struct file *out, | |
488 | size_t len, unsigned int flags, | |
489 | splice_actor *actor) | |
490 | { | |
491 | struct pipe_inode_info *info; | |
492 | int ret, do_wakeup, err; | |
493 | struct splice_desc sd; | |
494 | ||
495 | ret = 0; | |
496 | do_wakeup = 0; | |
497 | ||
498 | sd.total_len = len; | |
499 | sd.flags = flags; | |
500 | sd.file = out; | |
501 | sd.pos = out->f_pos; | |
502 | ||
503 | mutex_lock(PIPE_MUTEX(*inode)); | |
504 | ||
505 | info = inode->i_pipe; | |
506 | for (;;) { | |
507 | int bufs = info->nrbufs; | |
508 | ||
509 | if (bufs) { | |
510 | int curbuf = info->curbuf; | |
511 | struct pipe_buffer *buf = info->bufs + curbuf; | |
512 | struct pipe_buf_operations *ops = buf->ops; | |
513 | ||
514 | sd.len = buf->len; | |
515 | if (sd.len > sd.total_len) | |
516 | sd.len = sd.total_len; | |
517 | ||
518 | err = actor(info, buf, &sd); | |
519 | if (err) { | |
520 | if (!ret && err != -ENODATA) | |
521 | ret = err; | |
522 | ||
523 | break; | |
524 | } | |
525 | ||
526 | ret += sd.len; | |
527 | buf->offset += sd.len; | |
528 | buf->len -= sd.len; | |
529 | if (!buf->len) { | |
530 | buf->ops = NULL; | |
531 | ops->release(info, buf); | |
532 | curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1); | |
533 | info->curbuf = curbuf; | |
534 | info->nrbufs = --bufs; | |
535 | do_wakeup = 1; | |
536 | } | |
537 | ||
538 | sd.pos += sd.len; | |
539 | sd.total_len -= sd.len; | |
540 | if (!sd.total_len) | |
541 | break; | |
542 | } | |
543 | ||
544 | if (bufs) | |
545 | continue; | |
546 | if (!PIPE_WRITERS(*inode)) | |
547 | break; | |
548 | if (!PIPE_WAITING_WRITERS(*inode)) { | |
549 | if (ret) | |
550 | break; | |
551 | } | |
552 | ||
29e35094 LT |
553 | if (flags & SPLICE_F_NONBLOCK) { |
554 | if (!ret) | |
555 | ret = -EAGAIN; | |
556 | break; | |
557 | } | |
558 | ||
5274f052 JA |
559 | if (signal_pending(current)) { |
560 | if (!ret) | |
561 | ret = -ERESTARTSYS; | |
562 | break; | |
563 | } | |
564 | ||
565 | if (do_wakeup) { | |
566 | wake_up_interruptible_sync(PIPE_WAIT(*inode)); | |
567 | kill_fasync(PIPE_FASYNC_WRITERS(*inode),SIGIO,POLL_OUT); | |
568 | do_wakeup = 0; | |
569 | } | |
570 | ||
571 | pipe_wait(inode); | |
572 | } | |
573 | ||
574 | mutex_unlock(PIPE_MUTEX(*inode)); | |
575 | ||
576 | if (do_wakeup) { | |
577 | wake_up_interruptible(PIPE_WAIT(*inode)); | |
578 | kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT); | |
579 | } | |
580 | ||
581 | mutex_lock(&out->f_mapping->host->i_mutex); | |
582 | out->f_pos = sd.pos; | |
583 | mutex_unlock(&out->f_mapping->host->i_mutex); | |
584 | return ret; | |
585 | ||
586 | } | |
587 | ||
588 | ssize_t generic_file_splice_write(struct inode *inode, struct file *out, | |
589 | size_t len, unsigned int flags) | |
590 | { | |
4f6f0bd2 JA |
591 | struct address_space *mapping = out->f_mapping; |
592 | ssize_t ret = move_from_pipe(inode, out, len, flags, pipe_to_file); | |
593 | ||
594 | /* | |
595 | * if file or inode is SYNC and we actually wrote some data, sync it | |
596 | */ | |
597 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host)) | |
598 | && ret > 0) { | |
599 | struct inode *inode = mapping->host; | |
600 | int err; | |
601 | ||
602 | mutex_lock(&inode->i_mutex); | |
603 | err = generic_osync_inode(mapping->host, mapping, | |
604 | OSYNC_METADATA|OSYNC_DATA); | |
605 | mutex_unlock(&inode->i_mutex); | |
606 | ||
607 | if (err) | |
608 | ret = err; | |
609 | } | |
610 | ||
611 | return ret; | |
5274f052 JA |
612 | } |
613 | ||
614 | ssize_t generic_splice_sendpage(struct inode *inode, struct file *out, | |
615 | size_t len, unsigned int flags) | |
616 | { | |
617 | return move_from_pipe(inode, out, len, flags, pipe_to_sendpage); | |
618 | } | |
619 | ||
a0f06780 JG |
620 | EXPORT_SYMBOL(generic_file_splice_write); |
621 | EXPORT_SYMBOL(generic_file_splice_read); | |
622 | ||
5274f052 JA |
623 | static long do_splice_from(struct inode *pipe, struct file *out, size_t len, |
624 | unsigned int flags) | |
625 | { | |
626 | loff_t pos; | |
627 | int ret; | |
628 | ||
629 | if (!out->f_op || !out->f_op->splice_write) | |
630 | return -EINVAL; | |
631 | ||
632 | if (!(out->f_mode & FMODE_WRITE)) | |
633 | return -EBADF; | |
634 | ||
635 | pos = out->f_pos; | |
636 | ret = rw_verify_area(WRITE, out, &pos, len); | |
637 | if (unlikely(ret < 0)) | |
638 | return ret; | |
639 | ||
640 | return out->f_op->splice_write(pipe, out, len, flags); | |
641 | } | |
642 | ||
643 | static long do_splice_to(struct file *in, struct inode *pipe, size_t len, | |
644 | unsigned int flags) | |
645 | { | |
646 | loff_t pos, isize, left; | |
647 | int ret; | |
648 | ||
649 | if (!in->f_op || !in->f_op->splice_read) | |
650 | return -EINVAL; | |
651 | ||
652 | if (!(in->f_mode & FMODE_READ)) | |
653 | return -EBADF; | |
654 | ||
655 | pos = in->f_pos; | |
656 | ret = rw_verify_area(READ, in, &pos, len); | |
657 | if (unlikely(ret < 0)) | |
658 | return ret; | |
659 | ||
660 | isize = i_size_read(in->f_mapping->host); | |
661 | if (unlikely(in->f_pos >= isize)) | |
662 | return 0; | |
663 | ||
664 | left = isize - in->f_pos; | |
665 | if (left < len) | |
666 | len = left; | |
667 | ||
668 | return in->f_op->splice_read(in, pipe, len, flags); | |
669 | } | |
670 | ||
671 | static long do_splice(struct file *in, struct file *out, size_t len, | |
672 | unsigned int flags) | |
673 | { | |
674 | struct inode *pipe; | |
675 | ||
676 | pipe = in->f_dentry->d_inode; | |
677 | if (pipe->i_pipe) | |
678 | return do_splice_from(pipe, out, len, flags); | |
679 | ||
680 | pipe = out->f_dentry->d_inode; | |
681 | if (pipe->i_pipe) | |
682 | return do_splice_to(in, pipe, len, flags); | |
683 | ||
684 | return -EINVAL; | |
685 | } | |
686 | ||
687 | asmlinkage long sys_splice(int fdin, int fdout, size_t len, unsigned int flags) | |
688 | { | |
689 | long error; | |
690 | struct file *in, *out; | |
691 | int fput_in, fput_out; | |
692 | ||
693 | if (unlikely(!len)) | |
694 | return 0; | |
695 | ||
696 | error = -EBADF; | |
697 | in = fget_light(fdin, &fput_in); | |
698 | if (in) { | |
699 | if (in->f_mode & FMODE_READ) { | |
700 | out = fget_light(fdout, &fput_out); | |
701 | if (out) { | |
702 | if (out->f_mode & FMODE_WRITE) | |
703 | error = do_splice(in, out, len, flags); | |
704 | fput_light(out, fput_out); | |
705 | } | |
706 | } | |
707 | ||
708 | fput_light(in, fput_in); | |
709 | } | |
710 | ||
711 | return error; | |
712 | } |