blob: 7c2abd4504d702fea0fe514abe6bcbcfdbf0adbf [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 Axboe83f91352006-04-02 23:05:09 +020040/*
41 * Attempt to steal a page from a pipe buffer. This should perhaps go into
42 * a vm helper function, it's already simplified quite a bit by the
43 * addition of remove_mapping(). If success is returned, the caller may
44 * attempt to reuse this page for another destination.
45 */
Jens Axboe5abc97a2006-03-30 15:16:46 +020046static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
47 struct pipe_buffer *buf)
48{
49 struct page *page = buf->page;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020050 struct address_space *mapping = page_mapping(page);
Jens Axboe5abc97a2006-03-30 15:16:46 +020051
52 WARN_ON(!PageLocked(page));
53 WARN_ON(!PageUptodate(page));
54
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020055 if (PagePrivate(page))
56 try_to_release_page(page, mapping_gfp_mask(mapping));
57
58 if (!remove_mapping(mapping, page))
Jens Axboe5abc97a2006-03-30 15:16:46 +020059 return 1;
60
61 if (PageLRU(page)) {
62 struct zone *zone = page_zone(page);
63
64 spin_lock_irq(&zone->lru_lock);
65 BUG_ON(!PageLRU(page));
66 __ClearPageLRU(page);
67 del_page_from_lru(zone, page);
68 spin_unlock_irq(&zone->lru_lock);
69 }
70
Jens Axboe5abc97a2006-03-30 15:16:46 +020071 return 0;
72}
73
Jens Axboe5274f052006-03-30 15:15:30 +020074static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
75 struct pipe_buffer *buf)
76{
77 page_cache_release(buf->page);
78 buf->page = NULL;
79}
80
81static void *page_cache_pipe_buf_map(struct file *file,
82 struct pipe_inode_info *info,
83 struct pipe_buffer *buf)
84{
85 struct page *page = buf->page;
86
87 lock_page(page);
88
89 if (!PageUptodate(page)) {
90 unlock_page(page);
91 return ERR_PTR(-EIO);
92 }
93
94 if (!page->mapping) {
95 unlock_page(page);
96 return ERR_PTR(-ENODATA);
97 }
98
99 return kmap(buf->page);
100}
101
102static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
103 struct pipe_buffer *buf)
104{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200105 unlock_page(buf->page);
Jens Axboe5274f052006-03-30 15:15:30 +0200106 kunmap(buf->page);
107}
108
109static struct pipe_buf_operations page_cache_pipe_buf_ops = {
110 .can_merge = 0,
111 .map = page_cache_pipe_buf_map,
112 .unmap = page_cache_pipe_buf_unmap,
113 .release = page_cache_pipe_buf_release,
Jens Axboe5abc97a2006-03-30 15:16:46 +0200114 .steal = page_cache_pipe_buf_steal,
Jens Axboe5274f052006-03-30 15:15:30 +0200115};
116
Jens Axboe83f91352006-04-02 23:05:09 +0200117/*
118 * Pipe output worker. This sets up our pipe format with the page cache
119 * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
120 */
Jens Axboe5274f052006-03-30 15:15:30 +0200121static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
122 int nr_pages, unsigned long offset,
Linus Torvalds29e35092006-04-02 12:46:35 -0700123 unsigned long len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200124{
125 struct pipe_inode_info *info;
126 int ret, do_wakeup, i;
127
128 ret = 0;
129 do_wakeup = 0;
130 i = 0;
131
132 mutex_lock(PIPE_MUTEX(*inode));
133
134 info = inode->i_pipe;
135 for (;;) {
136 int bufs;
137
138 if (!PIPE_READERS(*inode)) {
139 send_sig(SIGPIPE, current, 0);
140 if (!ret)
141 ret = -EPIPE;
142 break;
143 }
144
145 bufs = info->nrbufs;
146 if (bufs < PIPE_BUFFERS) {
147 int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS - 1);
148 struct pipe_buffer *buf = info->bufs + newbuf;
149 struct page *page = pages[i++];
150 unsigned long this_len;
151
152 this_len = PAGE_CACHE_SIZE - offset;
153 if (this_len > len)
154 this_len = len;
155
156 buf->page = page;
157 buf->offset = offset;
158 buf->len = this_len;
159 buf->ops = &page_cache_pipe_buf_ops;
160 info->nrbufs = ++bufs;
161 do_wakeup = 1;
162
163 ret += this_len;
164 len -= this_len;
165 offset = 0;
166 if (!--nr_pages)
167 break;
168 if (!len)
169 break;
170 if (bufs < PIPE_BUFFERS)
171 continue;
172
173 break;
174 }
175
Linus Torvalds29e35092006-04-02 12:46:35 -0700176 if (flags & SPLICE_F_NONBLOCK) {
177 if (!ret)
178 ret = -EAGAIN;
179 break;
180 }
181
Jens Axboe5274f052006-03-30 15:15:30 +0200182 if (signal_pending(current)) {
183 if (!ret)
184 ret = -ERESTARTSYS;
185 break;
186 }
187
188 if (do_wakeup) {
189 wake_up_interruptible_sync(PIPE_WAIT(*inode));
190 kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO,
191 POLL_IN);
192 do_wakeup = 0;
193 }
194
195 PIPE_WAITING_WRITERS(*inode)++;
196 pipe_wait(inode);
197 PIPE_WAITING_WRITERS(*inode)--;
198 }
199
200 mutex_unlock(PIPE_MUTEX(*inode));
201
202 if (do_wakeup) {
203 wake_up_interruptible(PIPE_WAIT(*inode));
204 kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
205 }
206
207 while (i < nr_pages)
208 page_cache_release(pages[i++]);
209
210 return ret;
211}
212
213static int __generic_file_splice_read(struct file *in, struct inode *pipe,
Linus Torvalds29e35092006-04-02 12:46:35 -0700214 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200215{
216 struct address_space *mapping = in->f_mapping;
217 unsigned int offset, nr_pages;
218 struct page *pages[PIPE_BUFFERS], *shadow[PIPE_BUFFERS];
219 struct page *page;
220 pgoff_t index, pidx;
221 int i, j;
222
223 index = in->f_pos >> PAGE_CACHE_SHIFT;
224 offset = in->f_pos & ~PAGE_CACHE_MASK;
225 nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
226
227 if (nr_pages > PIPE_BUFFERS)
228 nr_pages = PIPE_BUFFERS;
229
230 /*
231 * initiate read-ahead on this page range
232 */
233 do_page_cache_readahead(mapping, in, index, nr_pages);
234
235 /*
236 * Get as many pages from the page cache as possible..
237 * Start IO on the page cache entries we create (we
238 * can assume that any pre-existing ones we find have
239 * already had IO started on them).
240 */
241 i = find_get_pages(mapping, index, nr_pages, pages);
242
243 /*
244 * common case - we found all pages and they are contiguous,
245 * kick them off
246 */
247 if (i && (pages[i - 1]->index == index + i - 1))
248 goto splice_them;
249
250 /*
251 * fill shadow[] with pages at the right locations, so we only
252 * have to fill holes
253 */
Jens Axboe53cd9ae2006-04-02 23:04:21 +0200254 memset(shadow, 0, nr_pages * sizeof(struct page *));
255 for (j = 0; j < i; j++)
256 shadow[pages[j]->index - index] = pages[j];
Jens Axboe5274f052006-03-30 15:15:30 +0200257
258 /*
259 * now fill in the holes
260 */
261 for (i = 0, pidx = index; i < nr_pages; pidx++, i++) {
262 int error;
263
264 if (shadow[i])
265 continue;
266
267 /*
268 * no page there, look one up / create it
269 */
270 page = find_or_create_page(mapping, pidx,
271 mapping_gfp_mask(mapping));
272 if (!page)
273 break;
274
275 if (PageUptodate(page))
276 unlock_page(page);
277 else {
278 error = mapping->a_ops->readpage(in, page);
279
280 if (unlikely(error)) {
281 page_cache_release(page);
282 break;
283 }
284 }
285 shadow[i] = page;
286 }
287
288 if (!i) {
289 for (i = 0; i < nr_pages; i++) {
290 if (shadow[i])
291 page_cache_release(shadow[i]);
292 }
293 return 0;
294 }
295
296 memcpy(pages, shadow, i * sizeof(struct page *));
297
298 /*
299 * Now we splice them into the pipe..
300 */
301splice_them:
Linus Torvalds29e35092006-04-02 12:46:35 -0700302 return move_to_pipe(pipe, pages, i, offset, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200303}
304
Jens Axboe83f91352006-04-02 23:05:09 +0200305/**
306 * generic_file_splice_read - splice data from file to a pipe
307 * @in: file to splice from
308 * @pipe: pipe to splice to
309 * @len: number of bytes to splice
310 * @flags: splice modifier flags
311 *
312 * Will read pages from given file and fill them into a pipe.
313 *
314 */
Jens Axboe5274f052006-03-30 15:15:30 +0200315ssize_t generic_file_splice_read(struct file *in, struct inode *pipe,
316 size_t len, unsigned int flags)
317{
318 ssize_t spliced;
319 int ret;
320
321 ret = 0;
322 spliced = 0;
323 while (len) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700324 ret = __generic_file_splice_read(in, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200325
326 if (ret <= 0)
327 break;
328
329 in->f_pos += ret;
330 len -= ret;
331 spliced += ret;
Linus Torvalds29e35092006-04-02 12:46:35 -0700332
333 if (!(flags & SPLICE_F_NONBLOCK))
334 continue;
335 ret = -EAGAIN;
336 break;
Jens Axboe5274f052006-03-30 15:15:30 +0200337 }
338
339 if (spliced)
340 return spliced;
341
342 return ret;
343}
344
Jens Axboe059a8f32006-04-02 23:06:05 +0200345EXPORT_SYMBOL(generic_file_splice_read);
346
Jens Axboe5274f052006-03-30 15:15:30 +0200347/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200348 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
349 * using sendpage().
Jens Axboe5274f052006-03-30 15:15:30 +0200350 */
351static int pipe_to_sendpage(struct pipe_inode_info *info,
352 struct pipe_buffer *buf, struct splice_desc *sd)
353{
354 struct file *file = sd->file;
355 loff_t pos = sd->pos;
356 unsigned int offset;
357 ssize_t ret;
358 void *ptr;
Jens Axboeb2b39fa2006-04-02 23:05:41 +0200359 int more;
Jens Axboe5274f052006-03-30 15:15:30 +0200360
361 /*
362 * sub-optimal, but we are limited by the pipe ->map. we don't
363 * need a kmap'ed buffer here, we just want to make sure we
364 * have the page pinned if the pipe page originates from the
365 * page cache
366 */
367 ptr = buf->ops->map(file, info, buf);
368 if (IS_ERR(ptr))
369 return PTR_ERR(ptr);
370
371 offset = pos & ~PAGE_CACHE_MASK;
Jens Axboeb2b39fa2006-04-02 23:05:41 +0200372 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200373
Jens Axboeb2b39fa2006-04-02 23:05:41 +0200374 ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more);
Jens Axboe5274f052006-03-30 15:15:30 +0200375
376 buf->ops->unmap(info, buf);
377 if (ret == sd->len)
378 return 0;
379
380 return -EIO;
381}
382
383/*
384 * This is a little more tricky than the file -> pipe splicing. There are
385 * basically three cases:
386 *
387 * - Destination page already exists in the address space and there
388 * are users of it. For that case we have no other option that
389 * copying the data. Tough luck.
390 * - Destination page already exists in the address space, but there
391 * are no users of it. Make sure it's uptodate, then drop it. Fall
392 * through to last case.
393 * - Destination page does not exist, we can add the pipe page to
394 * the page cache and avoid the copy.
395 *
Jens Axboe83f91352006-04-02 23:05:09 +0200396 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
397 * sd->flags), we attempt to migrate pages from the pipe to the output
398 * file address space page cache. This is possible if no one else has
399 * the pipe page referenced outside of the pipe and page cache. If
400 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
401 * a new page in the output file page cache and fill/dirty that.
Jens Axboe5274f052006-03-30 15:15:30 +0200402 */
403static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
404 struct splice_desc *sd)
405{
406 struct file *file = sd->file;
407 struct address_space *mapping = file->f_mapping;
408 unsigned int offset;
409 struct page *page;
Jens Axboe5274f052006-03-30 15:15:30 +0200410 pgoff_t index;
Jens Axboe5abc97a2006-03-30 15:16:46 +0200411 char *src;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200412 int ret, stolen;
Jens Axboe5274f052006-03-30 15:15:30 +0200413
414 /*
415 * after this, page will be locked and unmapped
416 */
417 src = buf->ops->map(file, info, buf);
418 if (IS_ERR(src))
419 return PTR_ERR(src);
420
421 index = sd->pos >> PAGE_CACHE_SHIFT;
422 offset = sd->pos & ~PAGE_CACHE_MASK;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200423 stolen = 0;
Jens Axboe5274f052006-03-30 15:15:30 +0200424
Jens Axboe5274f052006-03-30 15:15:30 +0200425 /*
Jens Axboe5abc97a2006-03-30 15:16:46 +0200426 * reuse buf page, if SPLICE_F_MOVE is set
Jens Axboe5274f052006-03-30 15:15:30 +0200427 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200428 if (sd->flags & SPLICE_F_MOVE) {
Jens Axboe83f91352006-04-02 23:05:09 +0200429 /*
430 * If steal succeeds, buf->page is now pruned from the vm
431 * side (LRU and page cache) and we can reuse it.
432 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200433 if (buf->ops->steal(info, buf))
434 goto find_page;
Jens Axboe5274f052006-03-30 15:15:30 +0200435
Jens Axboe5abc97a2006-03-30 15:16:46 +0200436 page = buf->page;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200437 stolen = 1;
Jens Axboe5abc97a2006-03-30 15:16:46 +0200438 if (add_to_page_cache_lru(page, mapping, index,
439 mapping_gfp_mask(mapping)))
440 goto find_page;
441 } else {
442find_page:
443 ret = -ENOMEM;
444 page = find_or_create_page(mapping, index,
445 mapping_gfp_mask(mapping));
446 if (!page)
447 goto out;
Jens Axboe5274f052006-03-30 15:15:30 +0200448
Jens Axboe5abc97a2006-03-30 15:16:46 +0200449 /*
450 * If the page is uptodate, it is also locked. If it isn't
451 * uptodate, we can mark it uptodate if we are filling the
452 * full page. Otherwise we need to read it in first...
453 */
454 if (!PageUptodate(page)) {
455 if (sd->len < PAGE_CACHE_SIZE) {
456 ret = mapping->a_ops->readpage(file, page);
457 if (unlikely(ret))
458 goto out;
459
460 lock_page(page);
461
462 if (!PageUptodate(page)) {
463 /*
464 * page got invalidated, repeat
465 */
466 if (!page->mapping) {
467 unlock_page(page);
468 page_cache_release(page);
469 goto find_page;
470 }
471 ret = -EIO;
472 goto out;
Jens Axboe5274f052006-03-30 15:15:30 +0200473 }
Jens Axboe5abc97a2006-03-30 15:16:46 +0200474 } else {
475 WARN_ON(!PageLocked(page));
476 SetPageUptodate(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200477 }
Jens Axboe5274f052006-03-30 15:15:30 +0200478 }
479 }
480
481 ret = mapping->a_ops->prepare_write(file, page, 0, sd->len);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200482 if (ret == AOP_TRUNCATED_PAGE) {
483 page_cache_release(page);
484 goto find_page;
485 } else if (ret)
Jens Axboe5274f052006-03-30 15:15:30 +0200486 goto out;
487
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200488 if (!stolen) {
Jens Axboe5abc97a2006-03-30 15:16:46 +0200489 char *dst = kmap_atomic(page, KM_USER0);
490
491 memcpy(dst + offset, src + buf->offset, sd->len);
492 flush_dcache_page(page);
493 kunmap_atomic(dst, KM_USER0);
494 }
Jens Axboe5274f052006-03-30 15:15:30 +0200495
496 ret = mapping->a_ops->commit_write(file, page, 0, sd->len);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200497 if (ret == AOP_TRUNCATED_PAGE) {
498 page_cache_release(page);
499 goto find_page;
500 } else if (ret)
Jens Axboe5274f052006-03-30 15:15:30 +0200501 goto out;
502
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200503 balance_dirty_pages_ratelimited(mapping);
Jens Axboe5274f052006-03-30 15:15:30 +0200504out:
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200505 if (!stolen) {
Jens Axboe5abc97a2006-03-30 15:16:46 +0200506 page_cache_release(page);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200507 unlock_page(page);
508 }
Jens Axboe5274f052006-03-30 15:15:30 +0200509 buf->ops->unmap(info, buf);
510 return ret;
511}
512
513typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
514 struct splice_desc *);
515
Jens Axboe83f91352006-04-02 23:05:09 +0200516/*
517 * Pipe input worker. Most of this logic works like a regular pipe, the
518 * key here is the 'actor' worker passed in that actually moves the data
519 * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
520 */
Jens Axboe5274f052006-03-30 15:15:30 +0200521static ssize_t move_from_pipe(struct inode *inode, struct file *out,
522 size_t len, unsigned int flags,
523 splice_actor *actor)
524{
525 struct pipe_inode_info *info;
526 int ret, do_wakeup, err;
527 struct splice_desc sd;
528
529 ret = 0;
530 do_wakeup = 0;
531
532 sd.total_len = len;
533 sd.flags = flags;
534 sd.file = out;
535 sd.pos = out->f_pos;
536
537 mutex_lock(PIPE_MUTEX(*inode));
538
539 info = inode->i_pipe;
540 for (;;) {
541 int bufs = info->nrbufs;
542
543 if (bufs) {
544 int curbuf = info->curbuf;
545 struct pipe_buffer *buf = info->bufs + curbuf;
546 struct pipe_buf_operations *ops = buf->ops;
547
548 sd.len = buf->len;
549 if (sd.len > sd.total_len)
550 sd.len = sd.total_len;
551
552 err = actor(info, buf, &sd);
553 if (err) {
554 if (!ret && err != -ENODATA)
555 ret = err;
556
557 break;
558 }
559
560 ret += sd.len;
561 buf->offset += sd.len;
562 buf->len -= sd.len;
563 if (!buf->len) {
564 buf->ops = NULL;
565 ops->release(info, buf);
566 curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1);
567 info->curbuf = curbuf;
568 info->nrbufs = --bufs;
569 do_wakeup = 1;
570 }
571
572 sd.pos += sd.len;
573 sd.total_len -= sd.len;
574 if (!sd.total_len)
575 break;
576 }
577
578 if (bufs)
579 continue;
580 if (!PIPE_WRITERS(*inode))
581 break;
582 if (!PIPE_WAITING_WRITERS(*inode)) {
583 if (ret)
584 break;
585 }
586
Linus Torvalds29e35092006-04-02 12:46:35 -0700587 if (flags & SPLICE_F_NONBLOCK) {
588 if (!ret)
589 ret = -EAGAIN;
590 break;
591 }
592
Jens Axboe5274f052006-03-30 15:15:30 +0200593 if (signal_pending(current)) {
594 if (!ret)
595 ret = -ERESTARTSYS;
596 break;
597 }
598
599 if (do_wakeup) {
600 wake_up_interruptible_sync(PIPE_WAIT(*inode));
601 kill_fasync(PIPE_FASYNC_WRITERS(*inode),SIGIO,POLL_OUT);
602 do_wakeup = 0;
603 }
604
605 pipe_wait(inode);
606 }
607
608 mutex_unlock(PIPE_MUTEX(*inode));
609
610 if (do_wakeup) {
611 wake_up_interruptible(PIPE_WAIT(*inode));
612 kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
613 }
614
615 mutex_lock(&out->f_mapping->host->i_mutex);
616 out->f_pos = sd.pos;
617 mutex_unlock(&out->f_mapping->host->i_mutex);
618 return ret;
619
620}
621
Jens Axboe83f91352006-04-02 23:05:09 +0200622/**
623 * generic_file_splice_write - splice data from a pipe to a file
624 * @inode: pipe inode
625 * @out: file to write to
626 * @len: number of bytes to splice
627 * @flags: splice modifier flags
628 *
629 * Will either move or copy pages (determined by @flags options) from
630 * the given pipe inode to the given file.
631 *
632 */
Jens Axboe5274f052006-03-30 15:15:30 +0200633ssize_t generic_file_splice_write(struct inode *inode, struct file *out,
634 size_t len, unsigned int flags)
635{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200636 struct address_space *mapping = out->f_mapping;
637 ssize_t ret = move_from_pipe(inode, out, len, flags, pipe_to_file);
638
639 /*
640 * if file or inode is SYNC and we actually wrote some data, sync it
641 */
642 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host))
643 && ret > 0) {
644 struct inode *inode = mapping->host;
645 int err;
646
647 mutex_lock(&inode->i_mutex);
648 err = generic_osync_inode(mapping->host, mapping,
649 OSYNC_METADATA|OSYNC_DATA);
650 mutex_unlock(&inode->i_mutex);
651
652 if (err)
653 ret = err;
654 }
655
656 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200657}
658
Jens Axboe059a8f32006-04-02 23:06:05 +0200659EXPORT_SYMBOL(generic_file_splice_write);
660
Jens Axboe83f91352006-04-02 23:05:09 +0200661/**
662 * generic_splice_sendpage - splice data from a pipe to a socket
663 * @inode: pipe inode
664 * @out: socket to write to
665 * @len: number of bytes to splice
666 * @flags: splice modifier flags
667 *
668 * Will send @len bytes from the pipe to a network socket. No data copying
669 * is involved.
670 *
671 */
Jens Axboe5274f052006-03-30 15:15:30 +0200672ssize_t generic_splice_sendpage(struct inode *inode, struct file *out,
673 size_t len, unsigned int flags)
674{
675 return move_from_pipe(inode, out, len, flags, pipe_to_sendpage);
676}
677
Jens Axboe059a8f32006-04-02 23:06:05 +0200678EXPORT_SYMBOL(generic_splice_sendpage);
Jeff Garzika0f06782006-03-30 23:06:13 -0500679
Jens Axboe83f91352006-04-02 23:05:09 +0200680/*
681 * Attempt to initiate a splice from pipe to file.
682 */
Jens Axboe5274f052006-03-30 15:15:30 +0200683static long do_splice_from(struct inode *pipe, struct file *out, size_t len,
684 unsigned int flags)
685{
686 loff_t pos;
687 int ret;
688
689 if (!out->f_op || !out->f_op->splice_write)
690 return -EINVAL;
691
692 if (!(out->f_mode & FMODE_WRITE))
693 return -EBADF;
694
695 pos = out->f_pos;
696 ret = rw_verify_area(WRITE, out, &pos, len);
697 if (unlikely(ret < 0))
698 return ret;
699
700 return out->f_op->splice_write(pipe, out, len, flags);
701}
702
Jens Axboe83f91352006-04-02 23:05:09 +0200703/*
704 * Attempt to initiate a splice from a file to a pipe.
705 */
Jens Axboe5274f052006-03-30 15:15:30 +0200706static long do_splice_to(struct file *in, struct inode *pipe, size_t len,
707 unsigned int flags)
708{
709 loff_t pos, isize, left;
710 int ret;
711
712 if (!in->f_op || !in->f_op->splice_read)
713 return -EINVAL;
714
715 if (!(in->f_mode & FMODE_READ))
716 return -EBADF;
717
718 pos = in->f_pos;
719 ret = rw_verify_area(READ, in, &pos, len);
720 if (unlikely(ret < 0))
721 return ret;
722
723 isize = i_size_read(in->f_mapping->host);
724 if (unlikely(in->f_pos >= isize))
725 return 0;
726
727 left = isize - in->f_pos;
728 if (left < len)
729 len = left;
730
731 return in->f_op->splice_read(in, pipe, len, flags);
732}
733
Jens Axboe83f91352006-04-02 23:05:09 +0200734/*
735 * Determine where to splice to/from.
736 */
Jens Axboe5274f052006-03-30 15:15:30 +0200737static long do_splice(struct file *in, struct file *out, size_t len,
738 unsigned int flags)
739{
740 struct inode *pipe;
741
742 pipe = in->f_dentry->d_inode;
743 if (pipe->i_pipe)
744 return do_splice_from(pipe, out, len, flags);
745
746 pipe = out->f_dentry->d_inode;
747 if (pipe->i_pipe)
748 return do_splice_to(in, pipe, len, flags);
749
750 return -EINVAL;
751}
752
753asmlinkage long sys_splice(int fdin, int fdout, size_t len, unsigned int flags)
754{
755 long error;
756 struct file *in, *out;
757 int fput_in, fput_out;
758
759 if (unlikely(!len))
760 return 0;
761
762 error = -EBADF;
763 in = fget_light(fdin, &fput_in);
764 if (in) {
765 if (in->f_mode & FMODE_READ) {
766 out = fget_light(fdout, &fput_out);
767 if (out) {
768 if (out->f_mode & FMODE_WRITE)
769 error = do_splice(in, out, len, flags);
770 fput_light(out, fput_out);
771 }
772 }
773
774 fput_light(in, fput_in);
775 }
776
777 return error;
778}