blob: 07f4d863c2d4021679ad90084ac27a17ee875177 [file] [log] [blame]
Jens Axboe5274f052006-03-30 15:15:30 +02001/*
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>
Jens Axboe5abc97a2006-03-30 15:16:46 +020024#include <linux/swap.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020025#include <linux/writeback.h>
26#include <linux/buffer_head.h>
Jeff Garzika0f06782006-03-30 23:06:13 -050027#include <linux/module.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020028#include <linux/syscalls.h>
Jens Axboe5274f052006-03-30 15:15:30 +020029
30/*
31 * Passed to the actors
32 */
33struct 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
Jens Axboe5abc97a2006-03-30 15:16:46 +020040static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
41 struct pipe_buffer *buf)
42{
43 struct page *page = buf->page;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020044 struct address_space *mapping = page_mapping(page);
Jens Axboe5abc97a2006-03-30 15:16:46 +020045
46 WARN_ON(!PageLocked(page));
47 WARN_ON(!PageUptodate(page));
48
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020049 if (PagePrivate(page))
50 try_to_release_page(page, mapping_gfp_mask(mapping));
51
52 if (!remove_mapping(mapping, page))
Jens Axboe5abc97a2006-03-30 15:16:46 +020053 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
Jens Axboe5abc97a2006-03-30 15:16:46 +020065 return 0;
66}
67
Jens Axboe5274f052006-03-30 15:15:30 +020068static 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
75static 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
96static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
97 struct pipe_buffer *buf)
98{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020099 unlock_page(buf->page);
Jens Axboe5274f052006-03-30 15:15:30 +0200100 kunmap(buf->page);
101}
102
103static 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,
Jens Axboe5abc97a2006-03-30 15:16:46 +0200108 .steal = page_cache_pipe_buf_steal,
Jens Axboe5274f052006-03-30 15:15:30 +0200109};
110
111static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
112 int nr_pages, unsigned long offset,
Linus Torvalds29e35092006-04-02 12:46:35 -0700113 unsigned long len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200114{
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
Linus Torvalds29e35092006-04-02 12:46:35 -0700166 if (flags & SPLICE_F_NONBLOCK) {
167 if (!ret)
168 ret = -EAGAIN;
169 break;
170 }
171
Jens Axboe5274f052006-03-30 15:15:30 +0200172 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
203static int __generic_file_splice_read(struct file *in, struct inode *pipe,
Linus Torvalds29e35092006-04-02 12:46:35 -0700204 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200205{
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 */
Jens Axboe53cd9ae2006-04-02 23:04:21 +0200244 memset(shadow, 0, nr_pages * sizeof(struct page *));
245 for (j = 0; j < i; j++)
246 shadow[pages[j]->index - index] = pages[j];
Jens Axboe5274f052006-03-30 15:15:30 +0200247
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 */
291splice_them:
Linus Torvalds29e35092006-04-02 12:46:35 -0700292 return move_to_pipe(pipe, pages, i, offset, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200293}
294
295ssize_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) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700304 ret = __generic_file_splice_read(in, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200305
306 if (ret <= 0)
307 break;
308
309 in->f_pos += ret;
310 len -= ret;
311 spliced += ret;
Linus Torvalds29e35092006-04-02 12:46:35 -0700312
313 if (!(flags & SPLICE_F_NONBLOCK))
314 continue;
315 ret = -EAGAIN;
316 break;
Jens Axboe5274f052006-03-30 15:15:30 +0200317 }
318
319 if (spliced)
320 return spliced;
321
322 return ret;
323}
324
325/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200326 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
327 * using sendpage().
Jens Axboe5274f052006-03-30 15:15:30 +0200328 */
329static 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 */
378static 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;
Jens Axboe5274f052006-03-30 15:15:30 +0200385 pgoff_t index;
Jens Axboe5abc97a2006-03-30 15:16:46 +0200386 char *src;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200387 int ret, stolen;
Jens Axboe5274f052006-03-30 15:15:30 +0200388
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;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200398 stolen = 0;
Jens Axboe5274f052006-03-30 15:15:30 +0200399
Jens Axboe5274f052006-03-30 15:15:30 +0200400 /*
Jens Axboe5abc97a2006-03-30 15:16:46 +0200401 * reuse buf page, if SPLICE_F_MOVE is set
Jens Axboe5274f052006-03-30 15:15:30 +0200402 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200403 if (sd->flags & SPLICE_F_MOVE) {
404 if (buf->ops->steal(info, buf))
405 goto find_page;
Jens Axboe5274f052006-03-30 15:15:30 +0200406
Jens Axboe5abc97a2006-03-30 15:16:46 +0200407 page = buf->page;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200408 stolen = 1;
Jens Axboe5abc97a2006-03-30 15:16:46 +0200409 if (add_to_page_cache_lru(page, mapping, index,
410 mapping_gfp_mask(mapping)))
411 goto find_page;
412 } else {
413find_page:
414 ret = -ENOMEM;
415 page = find_or_create_page(mapping, index,
416 mapping_gfp_mask(mapping));
417 if (!page)
418 goto out;
Jens Axboe5274f052006-03-30 15:15:30 +0200419
Jens Axboe5abc97a2006-03-30 15:16:46 +0200420 /*
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;
Jens Axboe5274f052006-03-30 15:15:30 +0200444 }
Jens Axboe5abc97a2006-03-30 15:16:46 +0200445 } else {
446 WARN_ON(!PageLocked(page));
447 SetPageUptodate(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200448 }
Jens Axboe5274f052006-03-30 15:15:30 +0200449 }
450 }
451
452 ret = mapping->a_ops->prepare_write(file, page, 0, sd->len);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200453 if (ret == AOP_TRUNCATED_PAGE) {
454 page_cache_release(page);
455 goto find_page;
456 } else if (ret)
Jens Axboe5274f052006-03-30 15:15:30 +0200457 goto out;
458
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200459 if (!stolen) {
Jens Axboe5abc97a2006-03-30 15:16:46 +0200460 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 }
Jens Axboe5274f052006-03-30 15:15:30 +0200466
467 ret = mapping->a_ops->commit_write(file, page, 0, sd->len);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200468 if (ret == AOP_TRUNCATED_PAGE) {
469 page_cache_release(page);
470 goto find_page;
471 } else if (ret)
Jens Axboe5274f052006-03-30 15:15:30 +0200472 goto out;
473
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200474 balance_dirty_pages_ratelimited(mapping);
Jens Axboe5274f052006-03-30 15:15:30 +0200475out:
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200476 if (!stolen) {
Jens Axboe5abc97a2006-03-30 15:16:46 +0200477 page_cache_release(page);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200478 unlock_page(page);
479 }
Jens Axboe5274f052006-03-30 15:15:30 +0200480 buf->ops->unmap(info, buf);
481 return ret;
482}
483
484typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
485 struct splice_desc *);
486
487static 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
Linus Torvalds29e35092006-04-02 12:46:35 -0700553 if (flags & SPLICE_F_NONBLOCK) {
554 if (!ret)
555 ret = -EAGAIN;
556 break;
557 }
558
Jens Axboe5274f052006-03-30 15:15:30 +0200559 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
588ssize_t generic_file_splice_write(struct inode *inode, struct file *out,
589 size_t len, unsigned int flags)
590{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200591 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;
Jens Axboe5274f052006-03-30 15:15:30 +0200612}
613
614ssize_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
Jeff Garzika0f06782006-03-30 23:06:13 -0500620EXPORT_SYMBOL(generic_file_splice_write);
621EXPORT_SYMBOL(generic_file_splice_read);
622
Jens Axboe5274f052006-03-30 15:15:30 +0200623static 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
643static 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
671static 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
687asmlinkage 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}