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