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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 | 152 | for (;;) { |
3a326a2c | 153 | if (!pipe->readers) { |
5274f052 JA |
154 | send_sig(SIGPIPE, current, 0); |
155 | if (!ret) | |
156 | ret = -EPIPE; | |
157 | break; | |
158 | } | |
159 | ||
6f767b04 JA |
160 | if (pipe->nrbufs < PIPE_BUFFERS) { |
161 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); | |
3a326a2c | 162 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
5274f052 JA |
163 | struct page *page = pages[i++]; |
164 | unsigned long this_len; | |
165 | ||
166 | this_len = PAGE_CACHE_SIZE - offset; | |
167 | if (this_len > len) | |
168 | this_len = len; | |
169 | ||
170 | buf->page = page; | |
171 | buf->offset = offset; | |
172 | buf->len = this_len; | |
173 | buf->ops = &page_cache_pipe_buf_ops; | |
6f767b04 JA |
174 | pipe->nrbufs++; |
175 | if (pipe->inode) | |
176 | do_wakeup = 1; | |
5274f052 JA |
177 | |
178 | ret += this_len; | |
179 | len -= this_len; | |
180 | offset = 0; | |
181 | if (!--nr_pages) | |
182 | break; | |
183 | if (!len) | |
184 | break; | |
6f767b04 | 185 | if (pipe->nrbufs < PIPE_BUFFERS) |
5274f052 JA |
186 | continue; |
187 | ||
188 | break; | |
189 | } | |
190 | ||
29e35094 LT |
191 | if (flags & SPLICE_F_NONBLOCK) { |
192 | if (!ret) | |
193 | ret = -EAGAIN; | |
194 | break; | |
195 | } | |
196 | ||
5274f052 JA |
197 | if (signal_pending(current)) { |
198 | if (!ret) | |
199 | ret = -ERESTARTSYS; | |
200 | break; | |
201 | } | |
202 | ||
203 | if (do_wakeup) { | |
c0bd1f65 | 204 | smp_mb(); |
3a326a2c IM |
205 | if (waitqueue_active(&pipe->wait)) |
206 | wake_up_interruptible_sync(&pipe->wait); | |
207 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
208 | do_wakeup = 0; |
209 | } | |
210 | ||
3a326a2c IM |
211 | pipe->waiting_writers++; |
212 | pipe_wait(pipe); | |
213 | pipe->waiting_writers--; | |
5274f052 JA |
214 | } |
215 | ||
3a326a2c IM |
216 | if (pipe->inode) |
217 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
218 | |
219 | if (do_wakeup) { | |
c0bd1f65 | 220 | smp_mb(); |
3a326a2c IM |
221 | if (waitqueue_active(&pipe->wait)) |
222 | wake_up_interruptible(&pipe->wait); | |
223 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
224 | } |
225 | ||
226 | while (i < nr_pages) | |
227 | page_cache_release(pages[i++]); | |
228 | ||
229 | return ret; | |
230 | } | |
231 | ||
3a326a2c IM |
232 | static int |
233 | __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe, | |
234 | size_t len, unsigned int flags) | |
5274f052 JA |
235 | { |
236 | struct address_space *mapping = in->f_mapping; | |
237 | unsigned int offset, nr_pages; | |
16c523dd | 238 | struct page *pages[PIPE_BUFFERS]; |
5274f052 | 239 | struct page *page; |
16c523dd | 240 | pgoff_t index; |
7480a904 | 241 | int i, error; |
5274f052 JA |
242 | |
243 | index = in->f_pos >> PAGE_CACHE_SHIFT; | |
244 | offset = in->f_pos & ~PAGE_CACHE_MASK; | |
245 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
246 | ||
247 | if (nr_pages > PIPE_BUFFERS) | |
248 | nr_pages = PIPE_BUFFERS; | |
249 | ||
250 | /* | |
0b749ce3 JA |
251 | * initiate read-ahead on this page range. however, don't call into |
252 | * read-ahead if this is a non-zero offset (we are likely doing small | |
253 | * chunk splice and the page is already there) for a single page. | |
5274f052 | 254 | */ |
0b749ce3 JA |
255 | if (!offset || nr_pages > 1) |
256 | do_page_cache_readahead(mapping, in, index, nr_pages); | |
5274f052 | 257 | |
5274f052 JA |
258 | /* |
259 | * now fill in the holes | |
260 | */ | |
7480a904 | 261 | error = 0; |
16c523dd | 262 | for (i = 0; i < nr_pages; i++, index++) { |
7480a904 | 263 | find_page: |
5274f052 | 264 | /* |
7480a904 | 265 | * lookup the page for this index |
5274f052 | 266 | */ |
7480a904 JA |
267 | page = find_get_page(mapping, index); |
268 | if (!page) { | |
269 | /* | |
270 | * If in nonblock mode then dont block on | |
271 | * readpage (we've kicked readahead so there | |
272 | * will be asynchronous progress): | |
273 | */ | |
274 | if (flags & SPLICE_F_NONBLOCK) | |
275 | break; | |
276 | ||
277 | /* | |
278 | * page didn't exist, allocate one | |
279 | */ | |
280 | page = page_cache_alloc_cold(mapping); | |
281 | if (!page) | |
282 | break; | |
283 | ||
284 | error = add_to_page_cache_lru(page, mapping, index, | |
285 | mapping_gfp_mask(mapping)); | |
286 | if (unlikely(error)) { | |
287 | page_cache_release(page); | |
288 | break; | |
289 | } | |
290 | ||
291 | goto readpage; | |
292 | } | |
293 | ||
294 | /* | |
295 | * If the page isn't uptodate, we may need to start io on it | |
296 | */ | |
297 | if (!PageUptodate(page)) { | |
298 | lock_page(page); | |
299 | ||
300 | /* | |
301 | * page was truncated, stop here. if this isn't the | |
302 | * first page, we'll just complete what we already | |
303 | * added | |
304 | */ | |
305 | if (!page->mapping) { | |
306 | unlock_page(page); | |
307 | page_cache_release(page); | |
308 | break; | |
309 | } | |
310 | /* | |
311 | * page was already under io and is now done, great | |
312 | */ | |
313 | if (PageUptodate(page)) { | |
314 | unlock_page(page); | |
315 | goto fill_it; | |
316 | } | |
5274f052 | 317 | |
7480a904 JA |
318 | readpage: |
319 | /* | |
320 | * need to read in the page | |
321 | */ | |
322 | error = mapping->a_ops->readpage(in, page); | |
5274f052 JA |
323 | |
324 | if (unlikely(error)) { | |
325 | page_cache_release(page); | |
7480a904 JA |
326 | if (error == AOP_TRUNCATED_PAGE) |
327 | goto find_page; | |
5274f052 JA |
328 | break; |
329 | } | |
330 | } | |
7480a904 | 331 | fill_it: |
16c523dd | 332 | pages[i] = page; |
5274f052 JA |
333 | } |
334 | ||
16c523dd JA |
335 | if (i) |
336 | return move_to_pipe(pipe, pages, i, offset, len, flags); | |
5274f052 | 337 | |
7480a904 | 338 | return error; |
5274f052 JA |
339 | } |
340 | ||
83f9135b JA |
341 | /** |
342 | * generic_file_splice_read - splice data from file to a pipe | |
343 | * @in: file to splice from | |
344 | * @pipe: pipe to splice to | |
345 | * @len: number of bytes to splice | |
346 | * @flags: splice modifier flags | |
347 | * | |
348 | * Will read pages from given file and fill them into a pipe. | |
83f9135b | 349 | */ |
3a326a2c | 350 | ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe, |
5274f052 JA |
351 | size_t len, unsigned int flags) |
352 | { | |
353 | ssize_t spliced; | |
354 | int ret; | |
355 | ||
356 | ret = 0; | |
357 | spliced = 0; | |
3a326a2c | 358 | |
5274f052 | 359 | while (len) { |
29e35094 | 360 | ret = __generic_file_splice_read(in, pipe, len, flags); |
5274f052 JA |
361 | |
362 | if (ret <= 0) | |
363 | break; | |
364 | ||
365 | in->f_pos += ret; | |
366 | len -= ret; | |
367 | spliced += ret; | |
29e35094 LT |
368 | |
369 | if (!(flags & SPLICE_F_NONBLOCK)) | |
370 | continue; | |
371 | ret = -EAGAIN; | |
372 | break; | |
5274f052 JA |
373 | } |
374 | ||
375 | if (spliced) | |
376 | return spliced; | |
377 | ||
378 | return ret; | |
379 | } | |
380 | ||
059a8f37 JA |
381 | EXPORT_SYMBOL(generic_file_splice_read); |
382 | ||
5274f052 | 383 | /* |
4f6f0bd2 JA |
384 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
385 | * using sendpage(). | |
5274f052 JA |
386 | */ |
387 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
388 | struct pipe_buffer *buf, struct splice_desc *sd) | |
389 | { | |
390 | struct file *file = sd->file; | |
391 | loff_t pos = sd->pos; | |
392 | unsigned int offset; | |
393 | ssize_t ret; | |
394 | void *ptr; | |
b2b39fa4 | 395 | int more; |
5274f052 JA |
396 | |
397 | /* | |
398 | * sub-optimal, but we are limited by the pipe ->map. we don't | |
399 | * need a kmap'ed buffer here, we just want to make sure we | |
400 | * have the page pinned if the pipe page originates from the | |
401 | * page cache | |
402 | */ | |
403 | ptr = buf->ops->map(file, info, buf); | |
404 | if (IS_ERR(ptr)) | |
405 | return PTR_ERR(ptr); | |
406 | ||
407 | offset = pos & ~PAGE_CACHE_MASK; | |
b2b39fa4 | 408 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
5274f052 | 409 | |
b2b39fa4 | 410 | ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more); |
5274f052 JA |
411 | |
412 | buf->ops->unmap(info, buf); | |
413 | if (ret == sd->len) | |
414 | return 0; | |
415 | ||
416 | return -EIO; | |
417 | } | |
418 | ||
419 | /* | |
420 | * This is a little more tricky than the file -> pipe splicing. There are | |
421 | * basically three cases: | |
422 | * | |
423 | * - Destination page already exists in the address space and there | |
424 | * are users of it. For that case we have no other option that | |
425 | * copying the data. Tough luck. | |
426 | * - Destination page already exists in the address space, but there | |
427 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
428 | * through to last case. | |
429 | * - Destination page does not exist, we can add the pipe page to | |
430 | * the page cache and avoid the copy. | |
431 | * | |
83f9135b JA |
432 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
433 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
434 | * file address space page cache. This is possible if no one else has | |
435 | * the pipe page referenced outside of the pipe and page cache. If | |
436 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
437 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 JA |
438 | */ |
439 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
440 | struct splice_desc *sd) | |
441 | { | |
442 | struct file *file = sd->file; | |
443 | struct address_space *mapping = file->f_mapping; | |
3e7ee3e7 | 444 | gfp_t gfp_mask = mapping_gfp_mask(mapping); |
5274f052 JA |
445 | unsigned int offset; |
446 | struct page *page; | |
5274f052 | 447 | pgoff_t index; |
5abc97aa | 448 | char *src; |
3e7ee3e7 | 449 | int ret; |
5274f052 JA |
450 | |
451 | /* | |
49d0b21b | 452 | * make sure the data in this buffer is uptodate |
5274f052 JA |
453 | */ |
454 | src = buf->ops->map(file, info, buf); | |
455 | if (IS_ERR(src)) | |
456 | return PTR_ERR(src); | |
457 | ||
458 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
459 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
460 | ||
5274f052 | 461 | /* |
5abc97aa | 462 | * reuse buf page, if SPLICE_F_MOVE is set |
5274f052 | 463 | */ |
5abc97aa | 464 | if (sd->flags & SPLICE_F_MOVE) { |
83f9135b JA |
465 | /* |
466 | * If steal succeeds, buf->page is now pruned from the vm | |
467 | * side (LRU and page cache) and we can reuse it. | |
468 | */ | |
5abc97aa JA |
469 | if (buf->ops->steal(info, buf)) |
470 | goto find_page; | |
471 | ||
49d0b21b JA |
472 | /* |
473 | * this will also set the page locked | |
474 | */ | |
5abc97aa | 475 | page = buf->page; |
3e7ee3e7 | 476 | if (add_to_page_cache(page, mapping, index, gfp_mask)) |
5abc97aa | 477 | goto find_page; |
3e7ee3e7 JA |
478 | |
479 | if (!(buf->flags & PIPE_BUF_FLAG_LRU)) | |
480 | lru_cache_add(page); | |
5abc97aa JA |
481 | } else { |
482 | find_page: | |
483 | ret = -ENOMEM; | |
3e7ee3e7 | 484 | page = find_or_create_page(mapping, index, gfp_mask); |
5abc97aa | 485 | if (!page) |
9aefe431 | 486 | goto out_nomem; |
5abc97aa JA |
487 | |
488 | /* | |
489 | * If the page is uptodate, it is also locked. If it isn't | |
490 | * uptodate, we can mark it uptodate if we are filling the | |
491 | * full page. Otherwise we need to read it in first... | |
492 | */ | |
493 | if (!PageUptodate(page)) { | |
494 | if (sd->len < PAGE_CACHE_SIZE) { | |
495 | ret = mapping->a_ops->readpage(file, page); | |
496 | if (unlikely(ret)) | |
497 | goto out; | |
498 | ||
499 | lock_page(page); | |
500 | ||
501 | if (!PageUptodate(page)) { | |
502 | /* | |
503 | * page got invalidated, repeat | |
504 | */ | |
505 | if (!page->mapping) { | |
506 | unlock_page(page); | |
507 | page_cache_release(page); | |
508 | goto find_page; | |
509 | } | |
510 | ret = -EIO; | |
511 | goto out; | |
5274f052 | 512 | } |
5abc97aa JA |
513 | } else { |
514 | WARN_ON(!PageLocked(page)); | |
515 | SetPageUptodate(page); | |
5274f052 | 516 | } |
5274f052 JA |
517 | } |
518 | } | |
519 | ||
520 | ret = mapping->a_ops->prepare_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
521 | if (ret == AOP_TRUNCATED_PAGE) { |
522 | page_cache_release(page); | |
523 | goto find_page; | |
524 | } else if (ret) | |
5274f052 JA |
525 | goto out; |
526 | ||
3e7ee3e7 | 527 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa JA |
528 | char *dst = kmap_atomic(page, KM_USER0); |
529 | ||
530 | memcpy(dst + offset, src + buf->offset, sd->len); | |
531 | flush_dcache_page(page); | |
532 | kunmap_atomic(dst, KM_USER0); | |
533 | } | |
5274f052 JA |
534 | |
535 | ret = mapping->a_ops->commit_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
536 | if (ret == AOP_TRUNCATED_PAGE) { |
537 | page_cache_release(page); | |
538 | goto find_page; | |
539 | } else if (ret) | |
5274f052 JA |
540 | goto out; |
541 | ||
c7f21e4f | 542 | mark_page_accessed(page); |
4f6f0bd2 | 543 | balance_dirty_pages_ratelimited(mapping); |
5274f052 | 544 | out: |
3e7ee3e7 | 545 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa | 546 | page_cache_release(page); |
4f6f0bd2 JA |
547 | unlock_page(page); |
548 | } | |
9aefe431 | 549 | out_nomem: |
5274f052 JA |
550 | buf->ops->unmap(info, buf); |
551 | return ret; | |
552 | } | |
553 | ||
554 | typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, | |
555 | struct splice_desc *); | |
556 | ||
83f9135b JA |
557 | /* |
558 | * Pipe input worker. Most of this logic works like a regular pipe, the | |
559 | * key here is the 'actor' worker passed in that actually moves the data | |
560 | * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. | |
561 | */ | |
3a326a2c | 562 | static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
5274f052 JA |
563 | size_t len, unsigned int flags, |
564 | splice_actor *actor) | |
565 | { | |
5274f052 JA |
566 | int ret, do_wakeup, err; |
567 | struct splice_desc sd; | |
568 | ||
569 | ret = 0; | |
570 | do_wakeup = 0; | |
571 | ||
572 | sd.total_len = len; | |
573 | sd.flags = flags; | |
574 | sd.file = out; | |
575 | sd.pos = out->f_pos; | |
576 | ||
3a326a2c IM |
577 | if (pipe->inode) |
578 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 579 | |
5274f052 | 580 | for (;;) { |
6f767b04 JA |
581 | if (pipe->nrbufs) { |
582 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
5274f052 JA |
583 | struct pipe_buf_operations *ops = buf->ops; |
584 | ||
585 | sd.len = buf->len; | |
586 | if (sd.len > sd.total_len) | |
587 | sd.len = sd.total_len; | |
588 | ||
3a326a2c | 589 | err = actor(pipe, buf, &sd); |
5274f052 JA |
590 | if (err) { |
591 | if (!ret && err != -ENODATA) | |
592 | ret = err; | |
593 | ||
594 | break; | |
595 | } | |
596 | ||
597 | ret += sd.len; | |
598 | buf->offset += sd.len; | |
599 | buf->len -= sd.len; | |
600 | if (!buf->len) { | |
601 | buf->ops = NULL; | |
3a326a2c | 602 | ops->release(pipe, buf); |
6f767b04 JA |
603 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
604 | pipe->nrbufs--; | |
605 | if (pipe->inode) | |
606 | do_wakeup = 1; | |
5274f052 JA |
607 | } |
608 | ||
609 | sd.pos += sd.len; | |
610 | sd.total_len -= sd.len; | |
611 | if (!sd.total_len) | |
612 | break; | |
613 | } | |
614 | ||
6f767b04 | 615 | if (pipe->nrbufs) |
5274f052 | 616 | continue; |
3a326a2c | 617 | if (!pipe->writers) |
5274f052 | 618 | break; |
3a326a2c | 619 | if (!pipe->waiting_writers) { |
5274f052 JA |
620 | if (ret) |
621 | break; | |
622 | } | |
623 | ||
29e35094 LT |
624 | if (flags & SPLICE_F_NONBLOCK) { |
625 | if (!ret) | |
626 | ret = -EAGAIN; | |
627 | break; | |
628 | } | |
629 | ||
5274f052 JA |
630 | if (signal_pending(current)) { |
631 | if (!ret) | |
632 | ret = -ERESTARTSYS; | |
633 | break; | |
634 | } | |
635 | ||
636 | if (do_wakeup) { | |
c0bd1f65 | 637 | smp_mb(); |
3a326a2c IM |
638 | if (waitqueue_active(&pipe->wait)) |
639 | wake_up_interruptible_sync(&pipe->wait); | |
640 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
641 | do_wakeup = 0; |
642 | } | |
643 | ||
3a326a2c | 644 | pipe_wait(pipe); |
5274f052 JA |
645 | } |
646 | ||
3a326a2c IM |
647 | if (pipe->inode) |
648 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
649 | |
650 | if (do_wakeup) { | |
c0bd1f65 | 651 | smp_mb(); |
3a326a2c IM |
652 | if (waitqueue_active(&pipe->wait)) |
653 | wake_up_interruptible(&pipe->wait); | |
654 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
655 | } |
656 | ||
5274f052 | 657 | out->f_pos = sd.pos; |
5274f052 JA |
658 | return ret; |
659 | ||
660 | } | |
661 | ||
83f9135b JA |
662 | /** |
663 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 664 | * @pipe: pipe info |
83f9135b JA |
665 | * @out: file to write to |
666 | * @len: number of bytes to splice | |
667 | * @flags: splice modifier flags | |
668 | * | |
669 | * Will either move or copy pages (determined by @flags options) from | |
670 | * the given pipe inode to the given file. | |
671 | * | |
672 | */ | |
3a326a2c IM |
673 | ssize_t |
674 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
675 | size_t len, unsigned int flags) | |
5274f052 | 676 | { |
4f6f0bd2 | 677 | struct address_space *mapping = out->f_mapping; |
3a326a2c IM |
678 | ssize_t ret; |
679 | ||
680 | ret = move_from_pipe(pipe, out, len, flags, pipe_to_file); | |
4f6f0bd2 JA |
681 | |
682 | /* | |
683 | * if file or inode is SYNC and we actually wrote some data, sync it | |
684 | */ | |
685 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host)) | |
686 | && ret > 0) { | |
687 | struct inode *inode = mapping->host; | |
688 | int err; | |
689 | ||
690 | mutex_lock(&inode->i_mutex); | |
691 | err = generic_osync_inode(mapping->host, mapping, | |
49570e9b | 692 | OSYNC_METADATA|OSYNC_DATA); |
4f6f0bd2 JA |
693 | mutex_unlock(&inode->i_mutex); |
694 | ||
695 | if (err) | |
696 | ret = err; | |
697 | } | |
698 | ||
699 | return ret; | |
5274f052 JA |
700 | } |
701 | ||
059a8f37 JA |
702 | EXPORT_SYMBOL(generic_file_splice_write); |
703 | ||
83f9135b JA |
704 | /** |
705 | * generic_splice_sendpage - splice data from a pipe to a socket | |
706 | * @inode: pipe inode | |
707 | * @out: socket to write to | |
708 | * @len: number of bytes to splice | |
709 | * @flags: splice modifier flags | |
710 | * | |
711 | * Will send @len bytes from the pipe to a network socket. No data copying | |
712 | * is involved. | |
713 | * | |
714 | */ | |
3a326a2c | 715 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
5274f052 JA |
716 | size_t len, unsigned int flags) |
717 | { | |
3a326a2c | 718 | return move_from_pipe(pipe, out, len, flags, pipe_to_sendpage); |
5274f052 JA |
719 | } |
720 | ||
059a8f37 | 721 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 722 | |
83f9135b JA |
723 | /* |
724 | * Attempt to initiate a splice from pipe to file. | |
725 | */ | |
3a326a2c | 726 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
b92ce558 | 727 | size_t len, unsigned int flags) |
5274f052 JA |
728 | { |
729 | loff_t pos; | |
730 | int ret; | |
731 | ||
49570e9b | 732 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
733 | return -EINVAL; |
734 | ||
49570e9b | 735 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
736 | return -EBADF; |
737 | ||
738 | pos = out->f_pos; | |
529565dc | 739 | |
5274f052 JA |
740 | ret = rw_verify_area(WRITE, out, &pos, len); |
741 | if (unlikely(ret < 0)) | |
742 | return ret; | |
743 | ||
744 | return out->f_op->splice_write(pipe, out, len, flags); | |
745 | } | |
746 | ||
83f9135b JA |
747 | /* |
748 | * Attempt to initiate a splice from a file to a pipe. | |
749 | */ | |
b92ce558 JA |
750 | static long do_splice_to(struct file *in, struct pipe_inode_info *pipe, |
751 | size_t len, unsigned int flags) | |
5274f052 JA |
752 | { |
753 | loff_t pos, isize, left; | |
754 | int ret; | |
755 | ||
49570e9b | 756 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
757 | return -EINVAL; |
758 | ||
49570e9b | 759 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
760 | return -EBADF; |
761 | ||
762 | pos = in->f_pos; | |
529565dc | 763 | |
5274f052 JA |
764 | ret = rw_verify_area(READ, in, &pos, len); |
765 | if (unlikely(ret < 0)) | |
766 | return ret; | |
767 | ||
768 | isize = i_size_read(in->f_mapping->host); | |
769 | if (unlikely(in->f_pos >= isize)) | |
770 | return 0; | |
771 | ||
772 | left = isize - in->f_pos; | |
49570e9b | 773 | if (unlikely(left < len)) |
5274f052 JA |
774 | len = left; |
775 | ||
776 | return in->f_op->splice_read(in, pipe, len, flags); | |
777 | } | |
778 | ||
b92ce558 JA |
779 | long do_splice_direct(struct file *in, struct file *out, size_t len, |
780 | unsigned int flags) | |
781 | { | |
782 | struct pipe_inode_info *pipe; | |
783 | long ret, bytes; | |
784 | umode_t i_mode; | |
785 | int i; | |
786 | ||
787 | /* | |
788 | * We require the input being a regular file, as we don't want to | |
789 | * randomly drop data for eg socket -> socket splicing. Use the | |
790 | * piped splicing for that! | |
791 | */ | |
792 | i_mode = in->f_dentry->d_inode->i_mode; | |
793 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
794 | return -EINVAL; | |
795 | ||
796 | /* | |
797 | * neither in nor out is a pipe, setup an internal pipe attached to | |
798 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
799 | */ | |
800 | pipe = current->splice_pipe; | |
49570e9b | 801 | if (unlikely(!pipe)) { |
b92ce558 JA |
802 | pipe = alloc_pipe_info(NULL); |
803 | if (!pipe) | |
804 | return -ENOMEM; | |
805 | ||
806 | /* | |
807 | * We don't have an immediate reader, but we'll read the stuff | |
808 | * out of the pipe right after the move_to_pipe(). So set | |
809 | * PIPE_READERS appropriately. | |
810 | */ | |
811 | pipe->readers = 1; | |
812 | ||
813 | current->splice_pipe = pipe; | |
814 | } | |
815 | ||
816 | /* | |
817 | * do the splice | |
818 | */ | |
819 | ret = 0; | |
820 | bytes = 0; | |
821 | ||
822 | while (len) { | |
823 | size_t read_len, max_read_len; | |
824 | ||
825 | /* | |
826 | * Do at most PIPE_BUFFERS pages worth of transfer: | |
827 | */ | |
828 | max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); | |
829 | ||
830 | ret = do_splice_to(in, pipe, max_read_len, flags); | |
831 | if (unlikely(ret < 0)) | |
832 | goto out_release; | |
833 | ||
834 | read_len = ret; | |
835 | ||
836 | /* | |
837 | * NOTE: nonblocking mode only applies to the input. We | |
838 | * must not do the output in nonblocking mode as then we | |
839 | * could get stuck data in the internal pipe: | |
840 | */ | |
841 | ret = do_splice_from(pipe, out, read_len, | |
842 | flags & ~SPLICE_F_NONBLOCK); | |
843 | if (unlikely(ret < 0)) | |
844 | goto out_release; | |
845 | ||
846 | bytes += ret; | |
847 | len -= ret; | |
848 | ||
849 | /* | |
850 | * In nonblocking mode, if we got back a short read then | |
851 | * that was due to either an IO error or due to the | |
852 | * pagecache entry not being there. In the IO error case | |
853 | * the _next_ splice attempt will produce a clean IO error | |
854 | * return value (not a short read), so in both cases it's | |
855 | * correct to break out of the loop here: | |
856 | */ | |
857 | if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) | |
858 | break; | |
859 | } | |
860 | ||
861 | pipe->nrbufs = pipe->curbuf = 0; | |
862 | ||
863 | return bytes; | |
864 | ||
865 | out_release: | |
866 | /* | |
867 | * If we did an incomplete transfer we must release | |
868 | * the pipe buffers in question: | |
869 | */ | |
870 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
871 | struct pipe_buffer *buf = pipe->bufs + i; | |
872 | ||
873 | if (buf->ops) { | |
874 | buf->ops->release(pipe, buf); | |
875 | buf->ops = NULL; | |
876 | } | |
877 | } | |
878 | pipe->nrbufs = pipe->curbuf = 0; | |
879 | ||
880 | /* | |
881 | * If we transferred some data, return the number of bytes: | |
882 | */ | |
883 | if (bytes > 0) | |
884 | return bytes; | |
885 | ||
886 | return ret; | |
887 | } | |
888 | ||
889 | EXPORT_SYMBOL(do_splice_direct); | |
890 | ||
83f9135b JA |
891 | /* |
892 | * Determine where to splice to/from. | |
893 | */ | |
529565dc IM |
894 | static long do_splice(struct file *in, loff_t __user *off_in, |
895 | struct file *out, loff_t __user *off_out, | |
896 | size_t len, unsigned int flags) | |
5274f052 | 897 | { |
3a326a2c | 898 | struct pipe_inode_info *pipe; |
5274f052 | 899 | |
3a326a2c | 900 | pipe = in->f_dentry->d_inode->i_pipe; |
529565dc IM |
901 | if (pipe) { |
902 | if (off_in) | |
903 | return -ESPIPE; | |
b92ce558 JA |
904 | if (off_out) { |
905 | if (out->f_op->llseek == no_llseek) | |
906 | return -EINVAL; | |
907 | if (copy_from_user(&out->f_pos, off_out, | |
908 | sizeof(loff_t))) | |
909 | return -EFAULT; | |
910 | } | |
529565dc | 911 | |
b92ce558 | 912 | return do_splice_from(pipe, out, len, flags); |
529565dc | 913 | } |
5274f052 | 914 | |
3a326a2c | 915 | pipe = out->f_dentry->d_inode->i_pipe; |
529565dc IM |
916 | if (pipe) { |
917 | if (off_out) | |
918 | return -ESPIPE; | |
b92ce558 JA |
919 | if (off_in) { |
920 | if (in->f_op->llseek == no_llseek) | |
921 | return -EINVAL; | |
922 | if (copy_from_user(&in->f_pos, off_in, sizeof(loff_t))) | |
923 | return -EFAULT; | |
924 | } | |
529565dc | 925 | |
b92ce558 | 926 | return do_splice_to(in, pipe, len, flags); |
529565dc | 927 | } |
5274f052 JA |
928 | |
929 | return -EINVAL; | |
930 | } | |
931 | ||
529565dc IM |
932 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
933 | int fd_out, loff_t __user *off_out, | |
934 | size_t len, unsigned int flags) | |
5274f052 JA |
935 | { |
936 | long error; | |
937 | struct file *in, *out; | |
938 | int fput_in, fput_out; | |
939 | ||
940 | if (unlikely(!len)) | |
941 | return 0; | |
942 | ||
943 | error = -EBADF; | |
529565dc | 944 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
945 | if (in) { |
946 | if (in->f_mode & FMODE_READ) { | |
529565dc | 947 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
948 | if (out) { |
949 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
950 | error = do_splice(in, off_in, |
951 | out, off_out, | |
952 | len, flags); | |
5274f052 JA |
953 | fput_light(out, fput_out); |
954 | } | |
955 | } | |
956 | ||
957 | fput_light(in, fput_in); | |
958 | } | |
959 | ||
960 | return error; | |
961 | } |