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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 | ||
83f9135b JA |
40 | /* |
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 | */ | |
5abc97aa JA |
46 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, |
47 | struct pipe_buffer *buf) | |
48 | { | |
49 | struct page *page = buf->page; | |
4f6f0bd2 | 50 | struct address_space *mapping = page_mapping(page); |
5abc97aa JA |
51 | |
52 | WARN_ON(!PageLocked(page)); | |
53 | WARN_ON(!PageUptodate(page)); | |
54 | ||
ad8d6f0a JA |
55 | /* |
56 | * At least for ext2 with nobh option, we need to wait on writeback | |
57 | * completing on this page, since we'll remove it from the pagecache. | |
58 | * Otherwise truncate wont wait on the page, allowing the disk | |
59 | * blocks to be reused by someone else before we actually wrote our | |
60 | * data to them. fs corruption ensues. | |
61 | */ | |
62 | wait_on_page_writeback(page); | |
63 | ||
4f6f0bd2 JA |
64 | if (PagePrivate(page)) |
65 | try_to_release_page(page, mapping_gfp_mask(mapping)); | |
66 | ||
67 | if (!remove_mapping(mapping, page)) | |
5abc97aa JA |
68 | return 1; |
69 | ||
3e7ee3e7 | 70 | buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU; |
5abc97aa JA |
71 | return 0; |
72 | } | |
73 | ||
5274f052 JA |
74 | static 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; | |
3e7ee3e7 | 79 | buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU); |
5274f052 JA |
80 | } |
81 | ||
82 | static void *page_cache_pipe_buf_map(struct file *file, | |
83 | struct pipe_inode_info *info, | |
84 | struct pipe_buffer *buf) | |
85 | { | |
86 | struct page *page = buf->page; | |
87 | ||
88 | lock_page(page); | |
89 | ||
90 | if (!PageUptodate(page)) { | |
91 | unlock_page(page); | |
92 | return ERR_PTR(-EIO); | |
93 | } | |
94 | ||
95 | if (!page->mapping) { | |
96 | unlock_page(page); | |
97 | return ERR_PTR(-ENODATA); | |
98 | } | |
99 | ||
100 | return kmap(buf->page); | |
101 | } | |
102 | ||
103 | static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info, | |
104 | struct pipe_buffer *buf) | |
105 | { | |
4f6f0bd2 | 106 | unlock_page(buf->page); |
5274f052 JA |
107 | kunmap(buf->page); |
108 | } | |
109 | ||
110 | static struct pipe_buf_operations page_cache_pipe_buf_ops = { | |
111 | .can_merge = 0, | |
112 | .map = page_cache_pipe_buf_map, | |
113 | .unmap = page_cache_pipe_buf_unmap, | |
114 | .release = page_cache_pipe_buf_release, | |
5abc97aa | 115 | .steal = page_cache_pipe_buf_steal, |
5274f052 JA |
116 | }; |
117 | ||
83f9135b JA |
118 | /* |
119 | * Pipe output worker. This sets up our pipe format with the page cache | |
120 | * pipe buffer operations. Otherwise very similar to the regular pipe_writev(). | |
121 | */ | |
5274f052 JA |
122 | static ssize_t move_to_pipe(struct inode *inode, struct page **pages, |
123 | int nr_pages, unsigned long offset, | |
29e35094 | 124 | unsigned long len, unsigned int flags) |
5274f052 JA |
125 | { |
126 | struct pipe_inode_info *info; | |
127 | int ret, do_wakeup, i; | |
128 | ||
129 | ret = 0; | |
130 | do_wakeup = 0; | |
131 | i = 0; | |
132 | ||
133 | mutex_lock(PIPE_MUTEX(*inode)); | |
134 | ||
135 | info = inode->i_pipe; | |
136 | for (;;) { | |
137 | int bufs; | |
138 | ||
139 | if (!PIPE_READERS(*inode)) { | |
140 | send_sig(SIGPIPE, current, 0); | |
141 | if (!ret) | |
142 | ret = -EPIPE; | |
143 | break; | |
144 | } | |
145 | ||
146 | bufs = info->nrbufs; | |
147 | if (bufs < PIPE_BUFFERS) { | |
148 | int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS - 1); | |
149 | struct pipe_buffer *buf = info->bufs + newbuf; | |
150 | struct page *page = pages[i++]; | |
151 | unsigned long this_len; | |
152 | ||
153 | this_len = PAGE_CACHE_SIZE - offset; | |
154 | if (this_len > len) | |
155 | this_len = len; | |
156 | ||
157 | buf->page = page; | |
158 | buf->offset = offset; | |
159 | buf->len = this_len; | |
160 | buf->ops = &page_cache_pipe_buf_ops; | |
161 | info->nrbufs = ++bufs; | |
162 | do_wakeup = 1; | |
163 | ||
164 | ret += this_len; | |
165 | len -= this_len; | |
166 | offset = 0; | |
167 | if (!--nr_pages) | |
168 | break; | |
169 | if (!len) | |
170 | break; | |
171 | if (bufs < PIPE_BUFFERS) | |
172 | continue; | |
173 | ||
174 | break; | |
175 | } | |
176 | ||
29e35094 LT |
177 | if (flags & SPLICE_F_NONBLOCK) { |
178 | if (!ret) | |
179 | ret = -EAGAIN; | |
180 | break; | |
181 | } | |
182 | ||
5274f052 JA |
183 | if (signal_pending(current)) { |
184 | if (!ret) | |
185 | ret = -ERESTARTSYS; | |
186 | break; | |
187 | } | |
188 | ||
189 | if (do_wakeup) { | |
190 | wake_up_interruptible_sync(PIPE_WAIT(*inode)); | |
191 | kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, | |
192 | POLL_IN); | |
193 | do_wakeup = 0; | |
194 | } | |
195 | ||
196 | PIPE_WAITING_WRITERS(*inode)++; | |
197 | pipe_wait(inode); | |
198 | PIPE_WAITING_WRITERS(*inode)--; | |
199 | } | |
200 | ||
201 | mutex_unlock(PIPE_MUTEX(*inode)); | |
202 | ||
203 | if (do_wakeup) { | |
204 | wake_up_interruptible(PIPE_WAIT(*inode)); | |
205 | kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN); | |
206 | } | |
207 | ||
208 | while (i < nr_pages) | |
209 | page_cache_release(pages[i++]); | |
210 | ||
211 | return ret; | |
212 | } | |
213 | ||
214 | static int __generic_file_splice_read(struct file *in, struct inode *pipe, | |
29e35094 | 215 | size_t len, unsigned int flags) |
5274f052 JA |
216 | { |
217 | struct address_space *mapping = in->f_mapping; | |
218 | unsigned int offset, nr_pages; | |
219 | struct page *pages[PIPE_BUFFERS], *shadow[PIPE_BUFFERS]; | |
220 | struct page *page; | |
221 | pgoff_t index, pidx; | |
222 | int i, j; | |
223 | ||
224 | index = in->f_pos >> PAGE_CACHE_SHIFT; | |
225 | offset = in->f_pos & ~PAGE_CACHE_MASK; | |
226 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
227 | ||
228 | if (nr_pages > PIPE_BUFFERS) | |
229 | nr_pages = PIPE_BUFFERS; | |
230 | ||
231 | /* | |
232 | * initiate read-ahead on this page range | |
233 | */ | |
234 | do_page_cache_readahead(mapping, in, index, nr_pages); | |
235 | ||
236 | /* | |
237 | * Get as many pages from the page cache as possible.. | |
238 | * Start IO on the page cache entries we create (we | |
239 | * can assume that any pre-existing ones we find have | |
240 | * already had IO started on them). | |
241 | */ | |
242 | i = find_get_pages(mapping, index, nr_pages, pages); | |
243 | ||
244 | /* | |
245 | * common case - we found all pages and they are contiguous, | |
246 | * kick them off | |
247 | */ | |
248 | if (i && (pages[i - 1]->index == index + i - 1)) | |
249 | goto splice_them; | |
250 | ||
251 | /* | |
252 | * fill shadow[] with pages at the right locations, so we only | |
253 | * have to fill holes | |
254 | */ | |
53cd9ae8 JA |
255 | memset(shadow, 0, nr_pages * sizeof(struct page *)); |
256 | for (j = 0; j < i; j++) | |
257 | shadow[pages[j]->index - index] = pages[j]; | |
5274f052 JA |
258 | |
259 | /* | |
260 | * now fill in the holes | |
261 | */ | |
262 | for (i = 0, pidx = index; i < nr_pages; pidx++, i++) { | |
263 | int error; | |
264 | ||
265 | if (shadow[i]) | |
266 | continue; | |
267 | ||
268 | /* | |
269 | * no page there, look one up / create it | |
270 | */ | |
271 | page = find_or_create_page(mapping, pidx, | |
272 | mapping_gfp_mask(mapping)); | |
273 | if (!page) | |
274 | break; | |
275 | ||
276 | if (PageUptodate(page)) | |
277 | unlock_page(page); | |
278 | else { | |
279 | error = mapping->a_ops->readpage(in, page); | |
280 | ||
281 | if (unlikely(error)) { | |
282 | page_cache_release(page); | |
283 | break; | |
284 | } | |
285 | } | |
286 | shadow[i] = page; | |
287 | } | |
288 | ||
289 | if (!i) { | |
290 | for (i = 0; i < nr_pages; i++) { | |
291 | if (shadow[i]) | |
292 | page_cache_release(shadow[i]); | |
293 | } | |
294 | return 0; | |
295 | } | |
296 | ||
297 | memcpy(pages, shadow, i * sizeof(struct page *)); | |
298 | ||
299 | /* | |
300 | * Now we splice them into the pipe.. | |
301 | */ | |
302 | splice_them: | |
29e35094 | 303 | return move_to_pipe(pipe, pages, i, offset, len, flags); |
5274f052 JA |
304 | } |
305 | ||
83f9135b JA |
306 | /** |
307 | * generic_file_splice_read - splice data from file to a pipe | |
308 | * @in: file to splice from | |
309 | * @pipe: pipe to splice to | |
310 | * @len: number of bytes to splice | |
311 | * @flags: splice modifier flags | |
312 | * | |
313 | * Will read pages from given file and fill them into a pipe. | |
314 | * | |
315 | */ | |
5274f052 JA |
316 | ssize_t generic_file_splice_read(struct file *in, struct inode *pipe, |
317 | size_t len, unsigned int flags) | |
318 | { | |
319 | ssize_t spliced; | |
320 | int ret; | |
321 | ||
322 | ret = 0; | |
323 | spliced = 0; | |
324 | while (len) { | |
29e35094 | 325 | ret = __generic_file_splice_read(in, pipe, len, flags); |
5274f052 JA |
326 | |
327 | if (ret <= 0) | |
328 | break; | |
329 | ||
330 | in->f_pos += ret; | |
331 | len -= ret; | |
332 | spliced += ret; | |
29e35094 LT |
333 | |
334 | if (!(flags & SPLICE_F_NONBLOCK)) | |
335 | continue; | |
336 | ret = -EAGAIN; | |
337 | break; | |
5274f052 JA |
338 | } |
339 | ||
340 | if (spliced) | |
341 | return spliced; | |
342 | ||
343 | return ret; | |
344 | } | |
345 | ||
059a8f37 JA |
346 | EXPORT_SYMBOL(generic_file_splice_read); |
347 | ||
5274f052 | 348 | /* |
4f6f0bd2 JA |
349 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
350 | * using sendpage(). | |
5274f052 JA |
351 | */ |
352 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
353 | struct pipe_buffer *buf, struct splice_desc *sd) | |
354 | { | |
355 | struct file *file = sd->file; | |
356 | loff_t pos = sd->pos; | |
357 | unsigned int offset; | |
358 | ssize_t ret; | |
359 | void *ptr; | |
b2b39fa4 | 360 | int more; |
5274f052 JA |
361 | |
362 | /* | |
363 | * sub-optimal, but we are limited by the pipe ->map. we don't | |
364 | * need a kmap'ed buffer here, we just want to make sure we | |
365 | * have the page pinned if the pipe page originates from the | |
366 | * page cache | |
367 | */ | |
368 | ptr = buf->ops->map(file, info, buf); | |
369 | if (IS_ERR(ptr)) | |
370 | return PTR_ERR(ptr); | |
371 | ||
372 | offset = pos & ~PAGE_CACHE_MASK; | |
b2b39fa4 | 373 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
5274f052 | 374 | |
b2b39fa4 | 375 | ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more); |
5274f052 JA |
376 | |
377 | buf->ops->unmap(info, buf); | |
378 | if (ret == sd->len) | |
379 | return 0; | |
380 | ||
381 | return -EIO; | |
382 | } | |
383 | ||
384 | /* | |
385 | * This is a little more tricky than the file -> pipe splicing. There are | |
386 | * basically three cases: | |
387 | * | |
388 | * - Destination page already exists in the address space and there | |
389 | * are users of it. For that case we have no other option that | |
390 | * copying the data. Tough luck. | |
391 | * - Destination page already exists in the address space, but there | |
392 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
393 | * through to last case. | |
394 | * - Destination page does not exist, we can add the pipe page to | |
395 | * the page cache and avoid the copy. | |
396 | * | |
83f9135b JA |
397 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
398 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
399 | * file address space page cache. This is possible if no one else has | |
400 | * the pipe page referenced outside of the pipe and page cache. If | |
401 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
402 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 JA |
403 | */ |
404 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
405 | struct splice_desc *sd) | |
406 | { | |
407 | struct file *file = sd->file; | |
408 | struct address_space *mapping = file->f_mapping; | |
3e7ee3e7 | 409 | gfp_t gfp_mask = mapping_gfp_mask(mapping); |
5274f052 JA |
410 | unsigned int offset; |
411 | struct page *page; | |
5274f052 | 412 | pgoff_t index; |
5abc97aa | 413 | char *src; |
3e7ee3e7 | 414 | int ret; |
5274f052 JA |
415 | |
416 | /* | |
417 | * after this, page will be locked and unmapped | |
418 | */ | |
419 | src = buf->ops->map(file, info, buf); | |
420 | if (IS_ERR(src)) | |
421 | return PTR_ERR(src); | |
422 | ||
423 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
424 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
425 | ||
5274f052 | 426 | /* |
5abc97aa | 427 | * reuse buf page, if SPLICE_F_MOVE is set |
5274f052 | 428 | */ |
5abc97aa | 429 | if (sd->flags & SPLICE_F_MOVE) { |
83f9135b JA |
430 | /* |
431 | * If steal succeeds, buf->page is now pruned from the vm | |
432 | * side (LRU and page cache) and we can reuse it. | |
433 | */ | |
5abc97aa JA |
434 | if (buf->ops->steal(info, buf)) |
435 | goto find_page; | |
436 | ||
437 | page = buf->page; | |
3e7ee3e7 | 438 | if (add_to_page_cache(page, mapping, index, gfp_mask)) |
5abc97aa | 439 | goto find_page; |
3e7ee3e7 JA |
440 | |
441 | if (!(buf->flags & PIPE_BUF_FLAG_LRU)) | |
442 | lru_cache_add(page); | |
5abc97aa JA |
443 | } else { |
444 | find_page: | |
445 | ret = -ENOMEM; | |
3e7ee3e7 | 446 | page = find_or_create_page(mapping, index, gfp_mask); |
5abc97aa | 447 | if (!page) |
9aefe431 | 448 | goto out_nomem; |
5abc97aa JA |
449 | |
450 | /* | |
451 | * If the page is uptodate, it is also locked. If it isn't | |
452 | * uptodate, we can mark it uptodate if we are filling the | |
453 | * full page. Otherwise we need to read it in first... | |
454 | */ | |
455 | if (!PageUptodate(page)) { | |
456 | if (sd->len < PAGE_CACHE_SIZE) { | |
457 | ret = mapping->a_ops->readpage(file, page); | |
458 | if (unlikely(ret)) | |
459 | goto out; | |
460 | ||
461 | lock_page(page); | |
462 | ||
463 | if (!PageUptodate(page)) { | |
464 | /* | |
465 | * page got invalidated, repeat | |
466 | */ | |
467 | if (!page->mapping) { | |
468 | unlock_page(page); | |
469 | page_cache_release(page); | |
470 | goto find_page; | |
471 | } | |
472 | ret = -EIO; | |
473 | goto out; | |
5274f052 | 474 | } |
5abc97aa JA |
475 | } else { |
476 | WARN_ON(!PageLocked(page)); | |
477 | SetPageUptodate(page); | |
5274f052 | 478 | } |
5274f052 JA |
479 | } |
480 | } | |
481 | ||
482 | ret = mapping->a_ops->prepare_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
483 | if (ret == AOP_TRUNCATED_PAGE) { |
484 | page_cache_release(page); | |
485 | goto find_page; | |
486 | } else if (ret) | |
5274f052 JA |
487 | goto out; |
488 | ||
3e7ee3e7 | 489 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa JA |
490 | char *dst = kmap_atomic(page, KM_USER0); |
491 | ||
492 | memcpy(dst + offset, src + buf->offset, sd->len); | |
493 | flush_dcache_page(page); | |
494 | kunmap_atomic(dst, KM_USER0); | |
495 | } | |
5274f052 JA |
496 | |
497 | ret = mapping->a_ops->commit_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
498 | if (ret == AOP_TRUNCATED_PAGE) { |
499 | page_cache_release(page); | |
500 | goto find_page; | |
501 | } else if (ret) | |
5274f052 JA |
502 | goto out; |
503 | ||
c7f21e4f | 504 | mark_page_accessed(page); |
4f6f0bd2 | 505 | balance_dirty_pages_ratelimited(mapping); |
5274f052 | 506 | out: |
3e7ee3e7 | 507 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa | 508 | page_cache_release(page); |
4f6f0bd2 JA |
509 | unlock_page(page); |
510 | } | |
9aefe431 | 511 | out_nomem: |
5274f052 JA |
512 | buf->ops->unmap(info, buf); |
513 | return ret; | |
514 | } | |
515 | ||
516 | typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, | |
517 | struct splice_desc *); | |
518 | ||
83f9135b JA |
519 | /* |
520 | * Pipe input worker. Most of this logic works like a regular pipe, the | |
521 | * key here is the 'actor' worker passed in that actually moves the data | |
522 | * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. | |
523 | */ | |
5274f052 JA |
524 | static ssize_t move_from_pipe(struct inode *inode, struct file *out, |
525 | size_t len, unsigned int flags, | |
526 | splice_actor *actor) | |
527 | { | |
528 | struct pipe_inode_info *info; | |
529 | int ret, do_wakeup, err; | |
530 | struct splice_desc sd; | |
531 | ||
532 | ret = 0; | |
533 | do_wakeup = 0; | |
534 | ||
535 | sd.total_len = len; | |
536 | sd.flags = flags; | |
537 | sd.file = out; | |
538 | sd.pos = out->f_pos; | |
539 | ||
540 | mutex_lock(PIPE_MUTEX(*inode)); | |
541 | ||
542 | info = inode->i_pipe; | |
543 | for (;;) { | |
544 | int bufs = info->nrbufs; | |
545 | ||
546 | if (bufs) { | |
547 | int curbuf = info->curbuf; | |
548 | struct pipe_buffer *buf = info->bufs + curbuf; | |
549 | struct pipe_buf_operations *ops = buf->ops; | |
550 | ||
551 | sd.len = buf->len; | |
552 | if (sd.len > sd.total_len) | |
553 | sd.len = sd.total_len; | |
554 | ||
555 | err = actor(info, buf, &sd); | |
556 | if (err) { | |
557 | if (!ret && err != -ENODATA) | |
558 | ret = err; | |
559 | ||
560 | break; | |
561 | } | |
562 | ||
563 | ret += sd.len; | |
564 | buf->offset += sd.len; | |
565 | buf->len -= sd.len; | |
566 | if (!buf->len) { | |
567 | buf->ops = NULL; | |
568 | ops->release(info, buf); | |
569 | curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1); | |
570 | info->curbuf = curbuf; | |
571 | info->nrbufs = --bufs; | |
572 | do_wakeup = 1; | |
573 | } | |
574 | ||
575 | sd.pos += sd.len; | |
576 | sd.total_len -= sd.len; | |
577 | if (!sd.total_len) | |
578 | break; | |
579 | } | |
580 | ||
581 | if (bufs) | |
582 | continue; | |
583 | if (!PIPE_WRITERS(*inode)) | |
584 | break; | |
585 | if (!PIPE_WAITING_WRITERS(*inode)) { | |
586 | if (ret) | |
587 | break; | |
588 | } | |
589 | ||
29e35094 LT |
590 | if (flags & SPLICE_F_NONBLOCK) { |
591 | if (!ret) | |
592 | ret = -EAGAIN; | |
593 | break; | |
594 | } | |
595 | ||
5274f052 JA |
596 | if (signal_pending(current)) { |
597 | if (!ret) | |
598 | ret = -ERESTARTSYS; | |
599 | break; | |
600 | } | |
601 | ||
602 | if (do_wakeup) { | |
603 | wake_up_interruptible_sync(PIPE_WAIT(*inode)); | |
604 | kill_fasync(PIPE_FASYNC_WRITERS(*inode),SIGIO,POLL_OUT); | |
605 | do_wakeup = 0; | |
606 | } | |
607 | ||
608 | pipe_wait(inode); | |
609 | } | |
610 | ||
611 | mutex_unlock(PIPE_MUTEX(*inode)); | |
612 | ||
613 | if (do_wakeup) { | |
614 | wake_up_interruptible(PIPE_WAIT(*inode)); | |
615 | kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT); | |
616 | } | |
617 | ||
618 | mutex_lock(&out->f_mapping->host->i_mutex); | |
619 | out->f_pos = sd.pos; | |
620 | mutex_unlock(&out->f_mapping->host->i_mutex); | |
621 | return ret; | |
622 | ||
623 | } | |
624 | ||
83f9135b JA |
625 | /** |
626 | * generic_file_splice_write - splice data from a pipe to a file | |
627 | * @inode: pipe inode | |
628 | * @out: file to write to | |
629 | * @len: number of bytes to splice | |
630 | * @flags: splice modifier flags | |
631 | * | |
632 | * Will either move or copy pages (determined by @flags options) from | |
633 | * the given pipe inode to the given file. | |
634 | * | |
635 | */ | |
5274f052 JA |
636 | ssize_t generic_file_splice_write(struct inode *inode, struct file *out, |
637 | size_t len, unsigned int flags) | |
638 | { | |
4f6f0bd2 JA |
639 | struct address_space *mapping = out->f_mapping; |
640 | ssize_t ret = move_from_pipe(inode, out, len, flags, pipe_to_file); | |
641 | ||
642 | /* | |
643 | * if file or inode is SYNC and we actually wrote some data, sync it | |
644 | */ | |
645 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host)) | |
646 | && ret > 0) { | |
647 | struct inode *inode = mapping->host; | |
648 | int err; | |
649 | ||
650 | mutex_lock(&inode->i_mutex); | |
651 | err = generic_osync_inode(mapping->host, mapping, | |
652 | OSYNC_METADATA|OSYNC_DATA); | |
653 | mutex_unlock(&inode->i_mutex); | |
654 | ||
655 | if (err) | |
656 | ret = err; | |
657 | } | |
658 | ||
659 | return ret; | |
5274f052 JA |
660 | } |
661 | ||
059a8f37 JA |
662 | EXPORT_SYMBOL(generic_file_splice_write); |
663 | ||
83f9135b JA |
664 | /** |
665 | * generic_splice_sendpage - splice data from a pipe to a socket | |
666 | * @inode: pipe inode | |
667 | * @out: socket to write to | |
668 | * @len: number of bytes to splice | |
669 | * @flags: splice modifier flags | |
670 | * | |
671 | * Will send @len bytes from the pipe to a network socket. No data copying | |
672 | * is involved. | |
673 | * | |
674 | */ | |
5274f052 JA |
675 | ssize_t generic_splice_sendpage(struct inode *inode, struct file *out, |
676 | size_t len, unsigned int flags) | |
677 | { | |
678 | return move_from_pipe(inode, out, len, flags, pipe_to_sendpage); | |
679 | } | |
680 | ||
059a8f37 | 681 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 682 | |
83f9135b JA |
683 | /* |
684 | * Attempt to initiate a splice from pipe to file. | |
685 | */ | |
5274f052 JA |
686 | static long do_splice_from(struct inode *pipe, struct file *out, size_t len, |
687 | unsigned int flags) | |
688 | { | |
689 | loff_t pos; | |
690 | int ret; | |
691 | ||
692 | if (!out->f_op || !out->f_op->splice_write) | |
693 | return -EINVAL; | |
694 | ||
695 | if (!(out->f_mode & FMODE_WRITE)) | |
696 | return -EBADF; | |
697 | ||
698 | pos = out->f_pos; | |
699 | ret = rw_verify_area(WRITE, out, &pos, len); | |
700 | if (unlikely(ret < 0)) | |
701 | return ret; | |
702 | ||
703 | return out->f_op->splice_write(pipe, out, len, flags); | |
704 | } | |
705 | ||
83f9135b JA |
706 | /* |
707 | * Attempt to initiate a splice from a file to a pipe. | |
708 | */ | |
5274f052 JA |
709 | static long do_splice_to(struct file *in, struct inode *pipe, size_t len, |
710 | unsigned int flags) | |
711 | { | |
712 | loff_t pos, isize, left; | |
713 | int ret; | |
714 | ||
715 | if (!in->f_op || !in->f_op->splice_read) | |
716 | return -EINVAL; | |
717 | ||
718 | if (!(in->f_mode & FMODE_READ)) | |
719 | return -EBADF; | |
720 | ||
721 | pos = in->f_pos; | |
722 | ret = rw_verify_area(READ, in, &pos, len); | |
723 | if (unlikely(ret < 0)) | |
724 | return ret; | |
725 | ||
726 | isize = i_size_read(in->f_mapping->host); | |
727 | if (unlikely(in->f_pos >= isize)) | |
728 | return 0; | |
729 | ||
730 | left = isize - in->f_pos; | |
731 | if (left < len) | |
732 | len = left; | |
733 | ||
734 | return in->f_op->splice_read(in, pipe, len, flags); | |
735 | } | |
736 | ||
83f9135b JA |
737 | /* |
738 | * Determine where to splice to/from. | |
739 | */ | |
5274f052 JA |
740 | static long do_splice(struct file *in, struct file *out, size_t len, |
741 | unsigned int flags) | |
742 | { | |
743 | struct inode *pipe; | |
744 | ||
745 | pipe = in->f_dentry->d_inode; | |
746 | if (pipe->i_pipe) | |
747 | return do_splice_from(pipe, out, len, flags); | |
748 | ||
749 | pipe = out->f_dentry->d_inode; | |
750 | if (pipe->i_pipe) | |
751 | return do_splice_to(in, pipe, len, flags); | |
752 | ||
753 | return -EINVAL; | |
754 | } | |
755 | ||
756 | asmlinkage long sys_splice(int fdin, int fdout, size_t len, unsigned int flags) | |
757 | { | |
758 | long error; | |
759 | struct file *in, *out; | |
760 | int fput_in, fput_out; | |
761 | ||
762 | if (unlikely(!len)) | |
763 | return 0; | |
764 | ||
765 | error = -EBADF; | |
766 | in = fget_light(fdin, &fput_in); | |
767 | if (in) { | |
768 | if (in->f_mode & FMODE_READ) { | |
769 | out = fget_light(fdout, &fput_out); | |
770 | if (out) { | |
771 | if (out->f_mode & FMODE_WRITE) | |
772 | error = do_splice(in, out, len, flags); | |
773 | fput_light(out, fput_out); | |
774 | } | |
775 | } | |
776 | ||
777 | fput_light(in, fput_in); | |
778 | } | |
779 | ||
780 | return error; | |
781 | } |