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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; | |
49d0b21b | 87 | int err; |
5274f052 JA |
88 | |
89 | if (!PageUptodate(page)) { | |
49d0b21b JA |
90 | lock_page(page); |
91 | ||
92 | /* | |
93 | * Page got truncated/unhashed. This will cause a 0-byte | |
94 | * splice, if this is the first page | |
95 | */ | |
96 | if (!page->mapping) { | |
97 | err = -ENODATA; | |
98 | goto error; | |
99 | } | |
5274f052 | 100 | |
49d0b21b JA |
101 | /* |
102 | * uh oh, read-error from disk | |
103 | */ | |
104 | if (!PageUptodate(page)) { | |
105 | err = -EIO; | |
106 | goto error; | |
107 | } | |
108 | ||
109 | /* | |
110 | * page is ok afterall, fall through to mapping | |
111 | */ | |
5274f052 | 112 | unlock_page(page); |
5274f052 JA |
113 | } |
114 | ||
49d0b21b JA |
115 | return kmap(page); |
116 | error: | |
117 | unlock_page(page); | |
118 | return ERR_PTR(err); | |
5274f052 JA |
119 | } |
120 | ||
121 | static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info, | |
122 | struct pipe_buffer *buf) | |
123 | { | |
5274f052 JA |
124 | kunmap(buf->page); |
125 | } | |
126 | ||
127 | static struct pipe_buf_operations page_cache_pipe_buf_ops = { | |
128 | .can_merge = 0, | |
129 | .map = page_cache_pipe_buf_map, | |
130 | .unmap = page_cache_pipe_buf_unmap, | |
131 | .release = page_cache_pipe_buf_release, | |
5abc97aa | 132 | .steal = page_cache_pipe_buf_steal, |
5274f052 JA |
133 | }; |
134 | ||
83f9135b JA |
135 | /* |
136 | * Pipe output worker. This sets up our pipe format with the page cache | |
137 | * pipe buffer operations. Otherwise very similar to the regular pipe_writev(). | |
138 | */ | |
3a326a2c | 139 | static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages, |
5274f052 | 140 | int nr_pages, unsigned long offset, |
29e35094 | 141 | unsigned long len, unsigned int flags) |
5274f052 | 142 | { |
5274f052 JA |
143 | int ret, do_wakeup, i; |
144 | ||
145 | ret = 0; | |
146 | do_wakeup = 0; | |
147 | i = 0; | |
148 | ||
3a326a2c IM |
149 | if (pipe->inode) |
150 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 151 | |
5274f052 JA |
152 | for (;;) { |
153 | int bufs; | |
154 | ||
3a326a2c | 155 | if (!pipe->readers) { |
5274f052 JA |
156 | send_sig(SIGPIPE, current, 0); |
157 | if (!ret) | |
158 | ret = -EPIPE; | |
159 | break; | |
160 | } | |
161 | ||
3a326a2c | 162 | bufs = pipe->nrbufs; |
5274f052 | 163 | if (bufs < PIPE_BUFFERS) { |
3a326a2c IM |
164 | int newbuf = (pipe->curbuf + bufs) & (PIPE_BUFFERS - 1); |
165 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
5274f052 JA |
166 | struct page *page = pages[i++]; |
167 | unsigned long this_len; | |
168 | ||
169 | this_len = PAGE_CACHE_SIZE - offset; | |
170 | if (this_len > len) | |
171 | this_len = len; | |
172 | ||
173 | buf->page = page; | |
174 | buf->offset = offset; | |
175 | buf->len = this_len; | |
176 | buf->ops = &page_cache_pipe_buf_ops; | |
3a326a2c | 177 | pipe->nrbufs = ++bufs; |
5274f052 JA |
178 | do_wakeup = 1; |
179 | ||
180 | ret += this_len; | |
181 | len -= this_len; | |
182 | offset = 0; | |
183 | if (!--nr_pages) | |
184 | break; | |
185 | if (!len) | |
186 | break; | |
187 | if (bufs < PIPE_BUFFERS) | |
188 | continue; | |
189 | ||
190 | break; | |
191 | } | |
192 | ||
29e35094 LT |
193 | if (flags & SPLICE_F_NONBLOCK) { |
194 | if (!ret) | |
195 | ret = -EAGAIN; | |
196 | break; | |
197 | } | |
198 | ||
5274f052 JA |
199 | if (signal_pending(current)) { |
200 | if (!ret) | |
201 | ret = -ERESTARTSYS; | |
202 | break; | |
203 | } | |
204 | ||
205 | if (do_wakeup) { | |
c0bd1f65 | 206 | smp_mb(); |
3a326a2c IM |
207 | if (waitqueue_active(&pipe->wait)) |
208 | wake_up_interruptible_sync(&pipe->wait); | |
209 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
210 | do_wakeup = 0; |
211 | } | |
212 | ||
3a326a2c IM |
213 | pipe->waiting_writers++; |
214 | pipe_wait(pipe); | |
215 | pipe->waiting_writers--; | |
5274f052 JA |
216 | } |
217 | ||
3a326a2c IM |
218 | if (pipe->inode) |
219 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
220 | |
221 | if (do_wakeup) { | |
c0bd1f65 | 222 | smp_mb(); |
3a326a2c IM |
223 | if (waitqueue_active(&pipe->wait)) |
224 | wake_up_interruptible(&pipe->wait); | |
225 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
226 | } |
227 | ||
228 | while (i < nr_pages) | |
229 | page_cache_release(pages[i++]); | |
230 | ||
231 | return ret; | |
232 | } | |
233 | ||
3a326a2c IM |
234 | static int |
235 | __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe, | |
236 | size_t len, unsigned int flags) | |
5274f052 JA |
237 | { |
238 | struct address_space *mapping = in->f_mapping; | |
239 | unsigned int offset, nr_pages; | |
16c523dd | 240 | struct page *pages[PIPE_BUFFERS]; |
5274f052 | 241 | struct page *page; |
16c523dd | 242 | pgoff_t index; |
7480a904 | 243 | int i, error; |
5274f052 JA |
244 | |
245 | index = in->f_pos >> PAGE_CACHE_SHIFT; | |
246 | offset = in->f_pos & ~PAGE_CACHE_MASK; | |
247 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
248 | ||
249 | if (nr_pages > PIPE_BUFFERS) | |
250 | nr_pages = PIPE_BUFFERS; | |
251 | ||
252 | /* | |
0b749ce3 JA |
253 | * initiate read-ahead on this page range. however, don't call into |
254 | * read-ahead if this is a non-zero offset (we are likely doing small | |
255 | * chunk splice and the page is already there) for a single page. | |
5274f052 | 256 | */ |
0b749ce3 JA |
257 | if (!offset || nr_pages > 1) |
258 | do_page_cache_readahead(mapping, in, index, nr_pages); | |
5274f052 | 259 | |
5274f052 JA |
260 | /* |
261 | * now fill in the holes | |
262 | */ | |
7480a904 | 263 | error = 0; |
16c523dd | 264 | for (i = 0; i < nr_pages; i++, index++) { |
7480a904 | 265 | find_page: |
5274f052 | 266 | /* |
7480a904 | 267 | * lookup the page for this index |
5274f052 | 268 | */ |
7480a904 JA |
269 | page = find_get_page(mapping, index); |
270 | if (!page) { | |
271 | /* | |
272 | * If in nonblock mode then dont block on | |
273 | * readpage (we've kicked readahead so there | |
274 | * will be asynchronous progress): | |
275 | */ | |
276 | if (flags & SPLICE_F_NONBLOCK) | |
277 | break; | |
278 | ||
279 | /* | |
280 | * page didn't exist, allocate one | |
281 | */ | |
282 | page = page_cache_alloc_cold(mapping); | |
283 | if (!page) | |
284 | break; | |
285 | ||
286 | error = add_to_page_cache_lru(page, mapping, index, | |
287 | mapping_gfp_mask(mapping)); | |
288 | if (unlikely(error)) { | |
289 | page_cache_release(page); | |
290 | break; | |
291 | } | |
292 | ||
293 | goto readpage; | |
294 | } | |
295 | ||
296 | /* | |
297 | * If the page isn't uptodate, we may need to start io on it | |
298 | */ | |
299 | if (!PageUptodate(page)) { | |
300 | lock_page(page); | |
301 | ||
302 | /* | |
303 | * page was truncated, stop here. if this isn't the | |
304 | * first page, we'll just complete what we already | |
305 | * added | |
306 | */ | |
307 | if (!page->mapping) { | |
308 | unlock_page(page); | |
309 | page_cache_release(page); | |
310 | break; | |
311 | } | |
312 | /* | |
313 | * page was already under io and is now done, great | |
314 | */ | |
315 | if (PageUptodate(page)) { | |
316 | unlock_page(page); | |
317 | goto fill_it; | |
318 | } | |
5274f052 | 319 | |
7480a904 JA |
320 | readpage: |
321 | /* | |
322 | * need to read in the page | |
323 | */ | |
324 | error = mapping->a_ops->readpage(in, page); | |
5274f052 JA |
325 | |
326 | if (unlikely(error)) { | |
327 | page_cache_release(page); | |
7480a904 JA |
328 | if (error == AOP_TRUNCATED_PAGE) |
329 | goto find_page; | |
5274f052 JA |
330 | break; |
331 | } | |
332 | } | |
7480a904 | 333 | fill_it: |
16c523dd | 334 | pages[i] = page; |
5274f052 JA |
335 | } |
336 | ||
16c523dd JA |
337 | if (i) |
338 | return move_to_pipe(pipe, pages, i, offset, len, flags); | |
5274f052 | 339 | |
7480a904 | 340 | return error; |
5274f052 JA |
341 | } |
342 | ||
83f9135b JA |
343 | /** |
344 | * generic_file_splice_read - splice data from file to a pipe | |
345 | * @in: file to splice from | |
346 | * @pipe: pipe to splice to | |
347 | * @len: number of bytes to splice | |
348 | * @flags: splice modifier flags | |
349 | * | |
350 | * Will read pages from given file and fill them into a pipe. | |
351 | * | |
352 | */ | |
3a326a2c | 353 | ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe, |
5274f052 JA |
354 | size_t len, unsigned int flags) |
355 | { | |
356 | ssize_t spliced; | |
357 | int ret; | |
358 | ||
359 | ret = 0; | |
360 | spliced = 0; | |
3a326a2c | 361 | |
5274f052 | 362 | while (len) { |
29e35094 | 363 | ret = __generic_file_splice_read(in, pipe, len, flags); |
5274f052 JA |
364 | |
365 | if (ret <= 0) | |
366 | break; | |
367 | ||
368 | in->f_pos += ret; | |
369 | len -= ret; | |
370 | spliced += ret; | |
29e35094 LT |
371 | |
372 | if (!(flags & SPLICE_F_NONBLOCK)) | |
373 | continue; | |
374 | ret = -EAGAIN; | |
375 | break; | |
5274f052 JA |
376 | } |
377 | ||
378 | if (spliced) | |
379 | return spliced; | |
380 | ||
381 | return ret; | |
382 | } | |
383 | ||
059a8f37 JA |
384 | EXPORT_SYMBOL(generic_file_splice_read); |
385 | ||
5274f052 | 386 | /* |
4f6f0bd2 JA |
387 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
388 | * using sendpage(). | |
5274f052 JA |
389 | */ |
390 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
391 | struct pipe_buffer *buf, struct splice_desc *sd) | |
392 | { | |
393 | struct file *file = sd->file; | |
394 | loff_t pos = sd->pos; | |
395 | unsigned int offset; | |
396 | ssize_t ret; | |
397 | void *ptr; | |
b2b39fa4 | 398 | int more; |
5274f052 JA |
399 | |
400 | /* | |
401 | * sub-optimal, but we are limited by the pipe ->map. we don't | |
402 | * need a kmap'ed buffer here, we just want to make sure we | |
403 | * have the page pinned if the pipe page originates from the | |
404 | * page cache | |
405 | */ | |
406 | ptr = buf->ops->map(file, info, buf); | |
407 | if (IS_ERR(ptr)) | |
408 | return PTR_ERR(ptr); | |
409 | ||
410 | offset = pos & ~PAGE_CACHE_MASK; | |
b2b39fa4 | 411 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
5274f052 | 412 | |
b2b39fa4 | 413 | ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more); |
5274f052 JA |
414 | |
415 | buf->ops->unmap(info, buf); | |
416 | if (ret == sd->len) | |
417 | return 0; | |
418 | ||
419 | return -EIO; | |
420 | } | |
421 | ||
422 | /* | |
423 | * This is a little more tricky than the file -> pipe splicing. There are | |
424 | * basically three cases: | |
425 | * | |
426 | * - Destination page already exists in the address space and there | |
427 | * are users of it. For that case we have no other option that | |
428 | * copying the data. Tough luck. | |
429 | * - Destination page already exists in the address space, but there | |
430 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
431 | * through to last case. | |
432 | * - Destination page does not exist, we can add the pipe page to | |
433 | * the page cache and avoid the copy. | |
434 | * | |
83f9135b JA |
435 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
436 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
437 | * file address space page cache. This is possible if no one else has | |
438 | * the pipe page referenced outside of the pipe and page cache. If | |
439 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
440 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 JA |
441 | */ |
442 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
443 | struct splice_desc *sd) | |
444 | { | |
445 | struct file *file = sd->file; | |
446 | struct address_space *mapping = file->f_mapping; | |
3e7ee3e7 | 447 | gfp_t gfp_mask = mapping_gfp_mask(mapping); |
5274f052 JA |
448 | unsigned int offset; |
449 | struct page *page; | |
5274f052 | 450 | pgoff_t index; |
5abc97aa | 451 | char *src; |
3e7ee3e7 | 452 | int ret; |
5274f052 JA |
453 | |
454 | /* | |
49d0b21b | 455 | * make sure the data in this buffer is uptodate |
5274f052 JA |
456 | */ |
457 | src = buf->ops->map(file, info, buf); | |
458 | if (IS_ERR(src)) | |
459 | return PTR_ERR(src); | |
460 | ||
461 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
462 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
463 | ||
5274f052 | 464 | /* |
5abc97aa | 465 | * reuse buf page, if SPLICE_F_MOVE is set |
5274f052 | 466 | */ |
5abc97aa | 467 | if (sd->flags & SPLICE_F_MOVE) { |
83f9135b JA |
468 | /* |
469 | * If steal succeeds, buf->page is now pruned from the vm | |
470 | * side (LRU and page cache) and we can reuse it. | |
471 | */ | |
5abc97aa JA |
472 | if (buf->ops->steal(info, buf)) |
473 | goto find_page; | |
474 | ||
49d0b21b JA |
475 | /* |
476 | * this will also set the page locked | |
477 | */ | |
5abc97aa | 478 | page = buf->page; |
3e7ee3e7 | 479 | if (add_to_page_cache(page, mapping, index, gfp_mask)) |
5abc97aa | 480 | goto find_page; |
3e7ee3e7 JA |
481 | |
482 | if (!(buf->flags & PIPE_BUF_FLAG_LRU)) | |
483 | lru_cache_add(page); | |
5abc97aa JA |
484 | } else { |
485 | find_page: | |
486 | ret = -ENOMEM; | |
3e7ee3e7 | 487 | page = find_or_create_page(mapping, index, gfp_mask); |
5abc97aa | 488 | if (!page) |
9aefe431 | 489 | goto out_nomem; |
5abc97aa JA |
490 | |
491 | /* | |
492 | * If the page is uptodate, it is also locked. If it isn't | |
493 | * uptodate, we can mark it uptodate if we are filling the | |
494 | * full page. Otherwise we need to read it in first... | |
495 | */ | |
496 | if (!PageUptodate(page)) { | |
497 | if (sd->len < PAGE_CACHE_SIZE) { | |
498 | ret = mapping->a_ops->readpage(file, page); | |
499 | if (unlikely(ret)) | |
500 | goto out; | |
501 | ||
502 | lock_page(page); | |
503 | ||
504 | if (!PageUptodate(page)) { | |
505 | /* | |
506 | * page got invalidated, repeat | |
507 | */ | |
508 | if (!page->mapping) { | |
509 | unlock_page(page); | |
510 | page_cache_release(page); | |
511 | goto find_page; | |
512 | } | |
513 | ret = -EIO; | |
514 | goto out; | |
5274f052 | 515 | } |
5abc97aa JA |
516 | } else { |
517 | WARN_ON(!PageLocked(page)); | |
518 | SetPageUptodate(page); | |
5274f052 | 519 | } |
5274f052 JA |
520 | } |
521 | } | |
522 | ||
523 | ret = mapping->a_ops->prepare_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
524 | if (ret == AOP_TRUNCATED_PAGE) { |
525 | page_cache_release(page); | |
526 | goto find_page; | |
527 | } else if (ret) | |
5274f052 JA |
528 | goto out; |
529 | ||
3e7ee3e7 | 530 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa JA |
531 | char *dst = kmap_atomic(page, KM_USER0); |
532 | ||
533 | memcpy(dst + offset, src + buf->offset, sd->len); | |
534 | flush_dcache_page(page); | |
535 | kunmap_atomic(dst, KM_USER0); | |
536 | } | |
5274f052 JA |
537 | |
538 | ret = mapping->a_ops->commit_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
539 | if (ret == AOP_TRUNCATED_PAGE) { |
540 | page_cache_release(page); | |
541 | goto find_page; | |
542 | } else if (ret) | |
5274f052 JA |
543 | goto out; |
544 | ||
c7f21e4f | 545 | mark_page_accessed(page); |
4f6f0bd2 | 546 | balance_dirty_pages_ratelimited(mapping); |
5274f052 | 547 | out: |
3e7ee3e7 | 548 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa | 549 | page_cache_release(page); |
4f6f0bd2 JA |
550 | unlock_page(page); |
551 | } | |
9aefe431 | 552 | out_nomem: |
5274f052 JA |
553 | buf->ops->unmap(info, buf); |
554 | return ret; | |
555 | } | |
556 | ||
557 | typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, | |
558 | struct splice_desc *); | |
559 | ||
83f9135b JA |
560 | /* |
561 | * Pipe input worker. Most of this logic works like a regular pipe, the | |
562 | * key here is the 'actor' worker passed in that actually moves the data | |
563 | * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. | |
564 | */ | |
3a326a2c | 565 | static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
5274f052 JA |
566 | size_t len, unsigned int flags, |
567 | splice_actor *actor) | |
568 | { | |
5274f052 JA |
569 | int ret, do_wakeup, err; |
570 | struct splice_desc sd; | |
571 | ||
572 | ret = 0; | |
573 | do_wakeup = 0; | |
574 | ||
575 | sd.total_len = len; | |
576 | sd.flags = flags; | |
577 | sd.file = out; | |
578 | sd.pos = out->f_pos; | |
579 | ||
3a326a2c IM |
580 | if (pipe->inode) |
581 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 582 | |
5274f052 | 583 | for (;;) { |
3a326a2c | 584 | int bufs = pipe->nrbufs; |
5274f052 JA |
585 | |
586 | if (bufs) { | |
3a326a2c IM |
587 | int curbuf = pipe->curbuf; |
588 | struct pipe_buffer *buf = pipe->bufs + curbuf; | |
5274f052 JA |
589 | struct pipe_buf_operations *ops = buf->ops; |
590 | ||
591 | sd.len = buf->len; | |
592 | if (sd.len > sd.total_len) | |
593 | sd.len = sd.total_len; | |
594 | ||
3a326a2c | 595 | err = actor(pipe, buf, &sd); |
5274f052 JA |
596 | if (err) { |
597 | if (!ret && err != -ENODATA) | |
598 | ret = err; | |
599 | ||
600 | break; | |
601 | } | |
602 | ||
603 | ret += sd.len; | |
604 | buf->offset += sd.len; | |
605 | buf->len -= sd.len; | |
606 | if (!buf->len) { | |
607 | buf->ops = NULL; | |
3a326a2c | 608 | ops->release(pipe, buf); |
5274f052 | 609 | curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1); |
3a326a2c IM |
610 | pipe->curbuf = curbuf; |
611 | pipe->nrbufs = --bufs; | |
5274f052 JA |
612 | do_wakeup = 1; |
613 | } | |
614 | ||
615 | sd.pos += sd.len; | |
616 | sd.total_len -= sd.len; | |
617 | if (!sd.total_len) | |
618 | break; | |
619 | } | |
620 | ||
621 | if (bufs) | |
622 | continue; | |
3a326a2c | 623 | if (!pipe->writers) |
5274f052 | 624 | break; |
3a326a2c | 625 | if (!pipe->waiting_writers) { |
5274f052 JA |
626 | if (ret) |
627 | break; | |
628 | } | |
629 | ||
29e35094 LT |
630 | if (flags & SPLICE_F_NONBLOCK) { |
631 | if (!ret) | |
632 | ret = -EAGAIN; | |
633 | break; | |
634 | } | |
635 | ||
5274f052 JA |
636 | if (signal_pending(current)) { |
637 | if (!ret) | |
638 | ret = -ERESTARTSYS; | |
639 | break; | |
640 | } | |
641 | ||
642 | if (do_wakeup) { | |
c0bd1f65 | 643 | smp_mb(); |
3a326a2c IM |
644 | if (waitqueue_active(&pipe->wait)) |
645 | wake_up_interruptible_sync(&pipe->wait); | |
646 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
647 | do_wakeup = 0; |
648 | } | |
649 | ||
3a326a2c | 650 | pipe_wait(pipe); |
5274f052 JA |
651 | } |
652 | ||
3a326a2c IM |
653 | if (pipe->inode) |
654 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
655 | |
656 | if (do_wakeup) { | |
c0bd1f65 | 657 | smp_mb(); |
3a326a2c IM |
658 | if (waitqueue_active(&pipe->wait)) |
659 | wake_up_interruptible(&pipe->wait); | |
660 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
661 | } |
662 | ||
663 | mutex_lock(&out->f_mapping->host->i_mutex); | |
664 | out->f_pos = sd.pos; | |
665 | mutex_unlock(&out->f_mapping->host->i_mutex); | |
666 | return ret; | |
667 | ||
668 | } | |
669 | ||
83f9135b JA |
670 | /** |
671 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 672 | * @pipe: pipe info |
83f9135b JA |
673 | * @out: file to write to |
674 | * @len: number of bytes to splice | |
675 | * @flags: splice modifier flags | |
676 | * | |
677 | * Will either move or copy pages (determined by @flags options) from | |
678 | * the given pipe inode to the given file. | |
679 | * | |
680 | */ | |
3a326a2c IM |
681 | ssize_t |
682 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
683 | size_t len, unsigned int flags) | |
5274f052 | 684 | { |
4f6f0bd2 | 685 | struct address_space *mapping = out->f_mapping; |
3a326a2c IM |
686 | ssize_t ret; |
687 | ||
688 | ret = move_from_pipe(pipe, out, len, flags, pipe_to_file); | |
4f6f0bd2 JA |
689 | |
690 | /* | |
691 | * if file or inode is SYNC and we actually wrote some data, sync it | |
692 | */ | |
693 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host)) | |
694 | && ret > 0) { | |
695 | struct inode *inode = mapping->host; | |
696 | int err; | |
697 | ||
698 | mutex_lock(&inode->i_mutex); | |
699 | err = generic_osync_inode(mapping->host, mapping, | |
700 | OSYNC_METADATA|OSYNC_DATA); | |
701 | mutex_unlock(&inode->i_mutex); | |
702 | ||
703 | if (err) | |
704 | ret = err; | |
705 | } | |
706 | ||
707 | return ret; | |
5274f052 JA |
708 | } |
709 | ||
059a8f37 JA |
710 | EXPORT_SYMBOL(generic_file_splice_write); |
711 | ||
83f9135b JA |
712 | /** |
713 | * generic_splice_sendpage - splice data from a pipe to a socket | |
714 | * @inode: pipe inode | |
715 | * @out: socket to write to | |
716 | * @len: number of bytes to splice | |
717 | * @flags: splice modifier flags | |
718 | * | |
719 | * Will send @len bytes from the pipe to a network socket. No data copying | |
720 | * is involved. | |
721 | * | |
722 | */ | |
3a326a2c | 723 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
5274f052 JA |
724 | size_t len, unsigned int flags) |
725 | { | |
3a326a2c | 726 | return move_from_pipe(pipe, out, len, flags, pipe_to_sendpage); |
5274f052 JA |
727 | } |
728 | ||
059a8f37 | 729 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 730 | |
83f9135b JA |
731 | /* |
732 | * Attempt to initiate a splice from pipe to file. | |
733 | */ | |
3a326a2c | 734 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
b92ce558 | 735 | size_t len, unsigned int flags) |
5274f052 JA |
736 | { |
737 | loff_t pos; | |
738 | int ret; | |
739 | ||
740 | if (!out->f_op || !out->f_op->splice_write) | |
741 | return -EINVAL; | |
742 | ||
743 | if (!(out->f_mode & FMODE_WRITE)) | |
744 | return -EBADF; | |
745 | ||
746 | pos = out->f_pos; | |
529565dc | 747 | |
5274f052 JA |
748 | ret = rw_verify_area(WRITE, out, &pos, len); |
749 | if (unlikely(ret < 0)) | |
750 | return ret; | |
751 | ||
752 | return out->f_op->splice_write(pipe, out, len, flags); | |
753 | } | |
754 | ||
83f9135b JA |
755 | /* |
756 | * Attempt to initiate a splice from a file to a pipe. | |
757 | */ | |
b92ce558 JA |
758 | static long do_splice_to(struct file *in, struct pipe_inode_info *pipe, |
759 | size_t len, unsigned int flags) | |
5274f052 JA |
760 | { |
761 | loff_t pos, isize, left; | |
762 | int ret; | |
763 | ||
764 | if (!in->f_op || !in->f_op->splice_read) | |
765 | return -EINVAL; | |
766 | ||
767 | if (!(in->f_mode & FMODE_READ)) | |
768 | return -EBADF; | |
769 | ||
770 | pos = in->f_pos; | |
529565dc | 771 | |
5274f052 JA |
772 | ret = rw_verify_area(READ, in, &pos, len); |
773 | if (unlikely(ret < 0)) | |
774 | return ret; | |
775 | ||
776 | isize = i_size_read(in->f_mapping->host); | |
777 | if (unlikely(in->f_pos >= isize)) | |
778 | return 0; | |
779 | ||
780 | left = isize - in->f_pos; | |
781 | if (left < len) | |
782 | len = left; | |
783 | ||
784 | return in->f_op->splice_read(in, pipe, len, flags); | |
785 | } | |
786 | ||
b92ce558 JA |
787 | long do_splice_direct(struct file *in, struct file *out, size_t len, |
788 | unsigned int flags) | |
789 | { | |
790 | struct pipe_inode_info *pipe; | |
791 | long ret, bytes; | |
792 | umode_t i_mode; | |
793 | int i; | |
794 | ||
795 | /* | |
796 | * We require the input being a regular file, as we don't want to | |
797 | * randomly drop data for eg socket -> socket splicing. Use the | |
798 | * piped splicing for that! | |
799 | */ | |
800 | i_mode = in->f_dentry->d_inode->i_mode; | |
801 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
802 | return -EINVAL; | |
803 | ||
804 | /* | |
805 | * neither in nor out is a pipe, setup an internal pipe attached to | |
806 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
807 | */ | |
808 | pipe = current->splice_pipe; | |
809 | if (!pipe) { | |
810 | pipe = alloc_pipe_info(NULL); | |
811 | if (!pipe) | |
812 | return -ENOMEM; | |
813 | ||
814 | /* | |
815 | * We don't have an immediate reader, but we'll read the stuff | |
816 | * out of the pipe right after the move_to_pipe(). So set | |
817 | * PIPE_READERS appropriately. | |
818 | */ | |
819 | pipe->readers = 1; | |
820 | ||
821 | current->splice_pipe = pipe; | |
822 | } | |
823 | ||
824 | /* | |
825 | * do the splice | |
826 | */ | |
827 | ret = 0; | |
828 | bytes = 0; | |
829 | ||
830 | while (len) { | |
831 | size_t read_len, max_read_len; | |
832 | ||
833 | /* | |
834 | * Do at most PIPE_BUFFERS pages worth of transfer: | |
835 | */ | |
836 | max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); | |
837 | ||
838 | ret = do_splice_to(in, pipe, max_read_len, flags); | |
839 | if (unlikely(ret < 0)) | |
840 | goto out_release; | |
841 | ||
842 | read_len = ret; | |
843 | ||
844 | /* | |
845 | * NOTE: nonblocking mode only applies to the input. We | |
846 | * must not do the output in nonblocking mode as then we | |
847 | * could get stuck data in the internal pipe: | |
848 | */ | |
849 | ret = do_splice_from(pipe, out, read_len, | |
850 | flags & ~SPLICE_F_NONBLOCK); | |
851 | if (unlikely(ret < 0)) | |
852 | goto out_release; | |
853 | ||
854 | bytes += ret; | |
855 | len -= ret; | |
856 | ||
857 | /* | |
858 | * In nonblocking mode, if we got back a short read then | |
859 | * that was due to either an IO error or due to the | |
860 | * pagecache entry not being there. In the IO error case | |
861 | * the _next_ splice attempt will produce a clean IO error | |
862 | * return value (not a short read), so in both cases it's | |
863 | * correct to break out of the loop here: | |
864 | */ | |
865 | if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) | |
866 | break; | |
867 | } | |
868 | ||
869 | pipe->nrbufs = pipe->curbuf = 0; | |
870 | ||
871 | return bytes; | |
872 | ||
873 | out_release: | |
874 | /* | |
875 | * If we did an incomplete transfer we must release | |
876 | * the pipe buffers in question: | |
877 | */ | |
878 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
879 | struct pipe_buffer *buf = pipe->bufs + i; | |
880 | ||
881 | if (buf->ops) { | |
882 | buf->ops->release(pipe, buf); | |
883 | buf->ops = NULL; | |
884 | } | |
885 | } | |
886 | pipe->nrbufs = pipe->curbuf = 0; | |
887 | ||
888 | /* | |
889 | * If we transferred some data, return the number of bytes: | |
890 | */ | |
891 | if (bytes > 0) | |
892 | return bytes; | |
893 | ||
894 | return ret; | |
895 | } | |
896 | ||
897 | EXPORT_SYMBOL(do_splice_direct); | |
898 | ||
83f9135b JA |
899 | /* |
900 | * Determine where to splice to/from. | |
901 | */ | |
529565dc IM |
902 | static long do_splice(struct file *in, loff_t __user *off_in, |
903 | struct file *out, loff_t __user *off_out, | |
904 | size_t len, unsigned int flags) | |
5274f052 | 905 | { |
3a326a2c | 906 | struct pipe_inode_info *pipe; |
5274f052 | 907 | |
3a326a2c | 908 | pipe = in->f_dentry->d_inode->i_pipe; |
529565dc IM |
909 | if (pipe) { |
910 | if (off_in) | |
911 | return -ESPIPE; | |
b92ce558 JA |
912 | if (off_out) { |
913 | if (out->f_op->llseek == no_llseek) | |
914 | return -EINVAL; | |
915 | if (copy_from_user(&out->f_pos, off_out, | |
916 | sizeof(loff_t))) | |
917 | return -EFAULT; | |
918 | } | |
529565dc | 919 | |
b92ce558 | 920 | return do_splice_from(pipe, out, len, flags); |
529565dc | 921 | } |
5274f052 | 922 | |
3a326a2c | 923 | pipe = out->f_dentry->d_inode->i_pipe; |
529565dc IM |
924 | if (pipe) { |
925 | if (off_out) | |
926 | return -ESPIPE; | |
b92ce558 JA |
927 | if (off_in) { |
928 | if (in->f_op->llseek == no_llseek) | |
929 | return -EINVAL; | |
930 | if (copy_from_user(&in->f_pos, off_in, sizeof(loff_t))) | |
931 | return -EFAULT; | |
932 | } | |
529565dc | 933 | |
b92ce558 | 934 | return do_splice_to(in, pipe, len, flags); |
529565dc | 935 | } |
5274f052 JA |
936 | |
937 | return -EINVAL; | |
938 | } | |
939 | ||
529565dc IM |
940 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
941 | int fd_out, loff_t __user *off_out, | |
942 | size_t len, unsigned int flags) | |
5274f052 JA |
943 | { |
944 | long error; | |
945 | struct file *in, *out; | |
946 | int fput_in, fput_out; | |
947 | ||
948 | if (unlikely(!len)) | |
949 | return 0; | |
950 | ||
951 | error = -EBADF; | |
529565dc | 952 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
953 | if (in) { |
954 | if (in->f_mode & FMODE_READ) { | |
529565dc | 955 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
956 | if (out) { |
957 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
958 | error = do_splice(in, off_in, |
959 | out, off_out, | |
960 | len, flags); | |
5274f052 JA |
961 | fput_light(out, fput_out); |
962 | } | |
963 | } | |
964 | ||
965 | fput_light(in, fput_in); | |
966 | } | |
967 | ||
968 | return error; | |
969 | } |