]>
Commit | Line | Data |
---|---|---|
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 | |
c2058e06 JA |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. | |
5274f052 | 14 | * |
c2058e06 JA |
15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@suse.de> |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> | |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> | |
5274f052 JA |
18 | * |
19 | */ | |
20 | #include <linux/fs.h> | |
21 | #include <linux/file.h> | |
22 | #include <linux/pagemap.h> | |
23 | #include <linux/pipe_fs_i.h> | |
24 | #include <linux/mm_inline.h> | |
5abc97aa | 25 | #include <linux/swap.h> |
4f6f0bd2 JA |
26 | #include <linux/writeback.h> |
27 | #include <linux/buffer_head.h> | |
a0f06780 | 28 | #include <linux/module.h> |
4f6f0bd2 | 29 | #include <linux/syscalls.h> |
5274f052 JA |
30 | |
31 | /* | |
32 | * Passed to the actors | |
33 | */ | |
34 | struct splice_desc { | |
35 | unsigned int len, total_len; /* current and remaining length */ | |
36 | unsigned int flags; /* splice flags */ | |
37 | struct file *file; /* file to read/write */ | |
38 | loff_t pos; /* file position */ | |
39 | }; | |
40 | ||
83f9135b JA |
41 | /* |
42 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
43 | * a vm helper function, it's already simplified quite a bit by the | |
44 | * addition of remove_mapping(). If success is returned, the caller may | |
45 | * attempt to reuse this page for another destination. | |
46 | */ | |
5abc97aa JA |
47 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, |
48 | struct pipe_buffer *buf) | |
49 | { | |
50 | struct page *page = buf->page; | |
4f6f0bd2 | 51 | struct address_space *mapping = page_mapping(page); |
5abc97aa | 52 | |
9e0267c2 JA |
53 | lock_page(page); |
54 | ||
5abc97aa JA |
55 | WARN_ON(!PageUptodate(page)); |
56 | ||
ad8d6f0a JA |
57 | /* |
58 | * At least for ext2 with nobh option, we need to wait on writeback | |
59 | * completing on this page, since we'll remove it from the pagecache. | |
60 | * Otherwise truncate wont wait on the page, allowing the disk | |
61 | * blocks to be reused by someone else before we actually wrote our | |
62 | * data to them. fs corruption ensues. | |
63 | */ | |
64 | wait_on_page_writeback(page); | |
65 | ||
4f6f0bd2 JA |
66 | if (PagePrivate(page)) |
67 | try_to_release_page(page, mapping_gfp_mask(mapping)); | |
68 | ||
9e0267c2 JA |
69 | if (!remove_mapping(mapping, page)) { |
70 | unlock_page(page); | |
5abc97aa | 71 | return 1; |
9e0267c2 | 72 | } |
5abc97aa | 73 | |
3e7ee3e7 | 74 | buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU; |
5abc97aa JA |
75 | return 0; |
76 | } | |
77 | ||
5274f052 JA |
78 | static void page_cache_pipe_buf_release(struct pipe_inode_info *info, |
79 | struct pipe_buffer *buf) | |
80 | { | |
81 | page_cache_release(buf->page); | |
82 | buf->page = NULL; | |
3e7ee3e7 | 83 | buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU); |
5274f052 JA |
84 | } |
85 | ||
86 | static void *page_cache_pipe_buf_map(struct file *file, | |
87 | struct pipe_inode_info *info, | |
88 | struct pipe_buffer *buf) | |
89 | { | |
90 | struct page *page = buf->page; | |
49d0b21b | 91 | int err; |
5274f052 JA |
92 | |
93 | if (!PageUptodate(page)) { | |
49d0b21b JA |
94 | lock_page(page); |
95 | ||
96 | /* | |
97 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 98 | * splice, if this is the first page. |
49d0b21b JA |
99 | */ |
100 | if (!page->mapping) { | |
101 | err = -ENODATA; | |
102 | goto error; | |
103 | } | |
5274f052 | 104 | |
49d0b21b | 105 | /* |
73d62d83 | 106 | * Uh oh, read-error from disk. |
49d0b21b JA |
107 | */ |
108 | if (!PageUptodate(page)) { | |
109 | err = -EIO; | |
110 | goto error; | |
111 | } | |
112 | ||
113 | /* | |
73d62d83 | 114 | * Page is ok afterall, fall through to mapping. |
49d0b21b | 115 | */ |
5274f052 | 116 | unlock_page(page); |
5274f052 JA |
117 | } |
118 | ||
49d0b21b JA |
119 | return kmap(page); |
120 | error: | |
121 | unlock_page(page); | |
122 | return ERR_PTR(err); | |
5274f052 JA |
123 | } |
124 | ||
125 | static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info, | |
126 | struct pipe_buffer *buf) | |
127 | { | |
5274f052 JA |
128 | kunmap(buf->page); |
129 | } | |
130 | ||
70524490 JA |
131 | static void page_cache_pipe_buf_get(struct pipe_inode_info *info, |
132 | struct pipe_buffer *buf) | |
133 | { | |
134 | page_cache_get(buf->page); | |
135 | } | |
136 | ||
5274f052 JA |
137 | static struct pipe_buf_operations page_cache_pipe_buf_ops = { |
138 | .can_merge = 0, | |
139 | .map = page_cache_pipe_buf_map, | |
140 | .unmap = page_cache_pipe_buf_unmap, | |
141 | .release = page_cache_pipe_buf_release, | |
5abc97aa | 142 | .steal = page_cache_pipe_buf_steal, |
70524490 | 143 | .get = page_cache_pipe_buf_get, |
5274f052 JA |
144 | }; |
145 | ||
83f9135b JA |
146 | /* |
147 | * Pipe output worker. This sets up our pipe format with the page cache | |
148 | * pipe buffer operations. Otherwise very similar to the regular pipe_writev(). | |
149 | */ | |
3a326a2c | 150 | static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages, |
91ad66ef JA |
151 | int nr_pages, unsigned long len, |
152 | unsigned int offset, unsigned int flags) | |
5274f052 | 153 | { |
5274f052 JA |
154 | int ret, do_wakeup, i; |
155 | ||
156 | ret = 0; | |
157 | do_wakeup = 0; | |
158 | i = 0; | |
159 | ||
3a326a2c IM |
160 | if (pipe->inode) |
161 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 162 | |
5274f052 | 163 | for (;;) { |
3a326a2c | 164 | if (!pipe->readers) { |
5274f052 JA |
165 | send_sig(SIGPIPE, current, 0); |
166 | if (!ret) | |
167 | ret = -EPIPE; | |
168 | break; | |
169 | } | |
170 | ||
6f767b04 JA |
171 | if (pipe->nrbufs < PIPE_BUFFERS) { |
172 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); | |
3a326a2c | 173 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
5274f052 JA |
174 | struct page *page = pages[i++]; |
175 | unsigned long this_len; | |
176 | ||
177 | this_len = PAGE_CACHE_SIZE - offset; | |
178 | if (this_len > len) | |
179 | this_len = len; | |
180 | ||
181 | buf->page = page; | |
182 | buf->offset = offset; | |
183 | buf->len = this_len; | |
184 | buf->ops = &page_cache_pipe_buf_ops; | |
6f767b04 JA |
185 | pipe->nrbufs++; |
186 | if (pipe->inode) | |
187 | do_wakeup = 1; | |
5274f052 JA |
188 | |
189 | ret += this_len; | |
190 | len -= this_len; | |
191 | offset = 0; | |
192 | if (!--nr_pages) | |
193 | break; | |
194 | if (!len) | |
195 | break; | |
6f767b04 | 196 | if (pipe->nrbufs < PIPE_BUFFERS) |
5274f052 JA |
197 | continue; |
198 | ||
199 | break; | |
200 | } | |
201 | ||
29e35094 LT |
202 | if (flags & SPLICE_F_NONBLOCK) { |
203 | if (!ret) | |
204 | ret = -EAGAIN; | |
205 | break; | |
206 | } | |
207 | ||
5274f052 JA |
208 | if (signal_pending(current)) { |
209 | if (!ret) | |
210 | ret = -ERESTARTSYS; | |
211 | break; | |
212 | } | |
213 | ||
214 | if (do_wakeup) { | |
c0bd1f65 | 215 | smp_mb(); |
3a326a2c IM |
216 | if (waitqueue_active(&pipe->wait)) |
217 | wake_up_interruptible_sync(&pipe->wait); | |
218 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
219 | do_wakeup = 0; |
220 | } | |
221 | ||
3a326a2c IM |
222 | pipe->waiting_writers++; |
223 | pipe_wait(pipe); | |
224 | pipe->waiting_writers--; | |
5274f052 JA |
225 | } |
226 | ||
3a326a2c IM |
227 | if (pipe->inode) |
228 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
229 | |
230 | if (do_wakeup) { | |
c0bd1f65 | 231 | smp_mb(); |
3a326a2c IM |
232 | if (waitqueue_active(&pipe->wait)) |
233 | wake_up_interruptible(&pipe->wait); | |
234 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
235 | } |
236 | ||
237 | while (i < nr_pages) | |
238 | page_cache_release(pages[i++]); | |
239 | ||
240 | return ret; | |
241 | } | |
242 | ||
3a326a2c | 243 | static int |
cbb7e577 JA |
244 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
245 | struct pipe_inode_info *pipe, size_t len, | |
246 | unsigned int flags) | |
5274f052 JA |
247 | { |
248 | struct address_space *mapping = in->f_mapping; | |
91ad66ef | 249 | unsigned int loff, offset, nr_pages; |
16c523dd | 250 | struct page *pages[PIPE_BUFFERS]; |
5274f052 | 251 | struct page *page; |
91ad66ef JA |
252 | pgoff_t index, end_index; |
253 | loff_t isize; | |
254 | size_t bytes; | |
7480a904 | 255 | int i, error; |
5274f052 | 256 | |
cbb7e577 | 257 | index = *ppos >> PAGE_CACHE_SHIFT; |
91ad66ef | 258 | loff = offset = *ppos & ~PAGE_CACHE_MASK; |
5274f052 JA |
259 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
260 | ||
261 | if (nr_pages > PIPE_BUFFERS) | |
262 | nr_pages = PIPE_BUFFERS; | |
263 | ||
264 | /* | |
73d62d83 | 265 | * Initiate read-ahead on this page range. however, don't call into |
0b749ce3 JA |
266 | * read-ahead if this is a non-zero offset (we are likely doing small |
267 | * chunk splice and the page is already there) for a single page. | |
5274f052 | 268 | */ |
0b749ce3 JA |
269 | if (!offset || nr_pages > 1) |
270 | do_page_cache_readahead(mapping, in, index, nr_pages); | |
5274f052 | 271 | |
5274f052 | 272 | /* |
73d62d83 | 273 | * Now fill in the holes: |
5274f052 | 274 | */ |
7480a904 | 275 | error = 0; |
91ad66ef | 276 | bytes = 0; |
16c523dd | 277 | for (i = 0; i < nr_pages; i++, index++) { |
7480a904 | 278 | find_page: |
5274f052 | 279 | /* |
7480a904 | 280 | * lookup the page for this index |
5274f052 | 281 | */ |
7480a904 JA |
282 | page = find_get_page(mapping, index); |
283 | if (!page) { | |
7480a904 JA |
284 | /* |
285 | * page didn't exist, allocate one | |
286 | */ | |
287 | page = page_cache_alloc_cold(mapping); | |
288 | if (!page) | |
289 | break; | |
290 | ||
291 | error = add_to_page_cache_lru(page, mapping, index, | |
292 | mapping_gfp_mask(mapping)); | |
293 | if (unlikely(error)) { | |
294 | page_cache_release(page); | |
295 | break; | |
296 | } | |
297 | ||
298 | goto readpage; | |
299 | } | |
300 | ||
301 | /* | |
302 | * If the page isn't uptodate, we may need to start io on it | |
303 | */ | |
304 | if (!PageUptodate(page)) { | |
c4f895cb JA |
305 | /* |
306 | * If in nonblock mode then dont block on waiting | |
307 | * for an in-flight io page | |
308 | */ | |
309 | if (flags & SPLICE_F_NONBLOCK) | |
310 | break; | |
311 | ||
7480a904 JA |
312 | lock_page(page); |
313 | ||
314 | /* | |
315 | * page was truncated, stop here. if this isn't the | |
316 | * first page, we'll just complete what we already | |
317 | * added | |
318 | */ | |
319 | if (!page->mapping) { | |
320 | unlock_page(page); | |
321 | page_cache_release(page); | |
322 | break; | |
323 | } | |
324 | /* | |
325 | * page was already under io and is now done, great | |
326 | */ | |
327 | if (PageUptodate(page)) { | |
328 | unlock_page(page); | |
329 | goto fill_it; | |
330 | } | |
5274f052 | 331 | |
7480a904 JA |
332 | readpage: |
333 | /* | |
334 | * need to read in the page | |
335 | */ | |
336 | error = mapping->a_ops->readpage(in, page); | |
5274f052 JA |
337 | |
338 | if (unlikely(error)) { | |
339 | page_cache_release(page); | |
7480a904 JA |
340 | if (error == AOP_TRUNCATED_PAGE) |
341 | goto find_page; | |
5274f052 JA |
342 | break; |
343 | } | |
91ad66ef JA |
344 | |
345 | /* | |
346 | * i_size must be checked after ->readpage(). | |
347 | */ | |
348 | isize = i_size_read(mapping->host); | |
349 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
350 | if (unlikely(!isize || index > end_index)) { | |
351 | page_cache_release(page); | |
352 | break; | |
353 | } | |
354 | ||
355 | /* | |
356 | * if this is the last page, see if we need to shrink | |
357 | * the length and stop | |
358 | */ | |
359 | if (end_index == index) { | |
360 | loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK); | |
361 | if (bytes + loff > isize) { | |
362 | page_cache_release(page); | |
363 | break; | |
364 | } | |
365 | /* | |
366 | * force quit after adding this page | |
367 | */ | |
368 | nr_pages = i; | |
369 | } | |
5274f052 | 370 | } |
7480a904 | 371 | fill_it: |
16c523dd | 372 | pages[i] = page; |
91ad66ef JA |
373 | bytes += PAGE_CACHE_SIZE - loff; |
374 | loff = 0; | |
5274f052 JA |
375 | } |
376 | ||
16c523dd | 377 | if (i) |
91ad66ef | 378 | return move_to_pipe(pipe, pages, i, bytes, offset, flags); |
5274f052 | 379 | |
7480a904 | 380 | return error; |
5274f052 JA |
381 | } |
382 | ||
83f9135b JA |
383 | /** |
384 | * generic_file_splice_read - splice data from file to a pipe | |
385 | * @in: file to splice from | |
386 | * @pipe: pipe to splice to | |
387 | * @len: number of bytes to splice | |
388 | * @flags: splice modifier flags | |
389 | * | |
390 | * Will read pages from given file and fill them into a pipe. | |
83f9135b | 391 | */ |
cbb7e577 JA |
392 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
393 | struct pipe_inode_info *pipe, size_t len, | |
394 | unsigned int flags) | |
5274f052 JA |
395 | { |
396 | ssize_t spliced; | |
397 | int ret; | |
398 | ||
399 | ret = 0; | |
400 | spliced = 0; | |
3a326a2c | 401 | |
5274f052 | 402 | while (len) { |
cbb7e577 | 403 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
5274f052 | 404 | |
c4f895cb | 405 | if (ret < 0) |
5274f052 | 406 | break; |
c4f895cb JA |
407 | else if (!ret) { |
408 | if (spliced) | |
409 | break; | |
410 | if (flags & SPLICE_F_NONBLOCK) { | |
411 | ret = -EAGAIN; | |
412 | break; | |
413 | } | |
414 | } | |
5274f052 | 415 | |
cbb7e577 | 416 | *ppos += ret; |
5274f052 JA |
417 | len -= ret; |
418 | spliced += ret; | |
419 | } | |
420 | ||
421 | if (spliced) | |
422 | return spliced; | |
423 | ||
424 | return ret; | |
425 | } | |
426 | ||
059a8f37 JA |
427 | EXPORT_SYMBOL(generic_file_splice_read); |
428 | ||
5274f052 | 429 | /* |
4f6f0bd2 JA |
430 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
431 | * using sendpage(). | |
5274f052 JA |
432 | */ |
433 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
434 | struct pipe_buffer *buf, struct splice_desc *sd) | |
435 | { | |
436 | struct file *file = sd->file; | |
437 | loff_t pos = sd->pos; | |
438 | unsigned int offset; | |
439 | ssize_t ret; | |
440 | void *ptr; | |
b2b39fa4 | 441 | int more; |
5274f052 JA |
442 | |
443 | /* | |
73d62d83 | 444 | * Sub-optimal, but we are limited by the pipe ->map. We don't |
5274f052 JA |
445 | * need a kmap'ed buffer here, we just want to make sure we |
446 | * have the page pinned if the pipe page originates from the | |
73d62d83 | 447 | * page cache. |
5274f052 JA |
448 | */ |
449 | ptr = buf->ops->map(file, info, buf); | |
450 | if (IS_ERR(ptr)) | |
451 | return PTR_ERR(ptr); | |
452 | ||
453 | offset = pos & ~PAGE_CACHE_MASK; | |
b2b39fa4 | 454 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
5274f052 | 455 | |
b2b39fa4 | 456 | ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more); |
5274f052 JA |
457 | |
458 | buf->ops->unmap(info, buf); | |
459 | if (ret == sd->len) | |
460 | return 0; | |
461 | ||
462 | return -EIO; | |
463 | } | |
464 | ||
465 | /* | |
466 | * This is a little more tricky than the file -> pipe splicing. There are | |
467 | * basically three cases: | |
468 | * | |
469 | * - Destination page already exists in the address space and there | |
470 | * are users of it. For that case we have no other option that | |
471 | * copying the data. Tough luck. | |
472 | * - Destination page already exists in the address space, but there | |
473 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
474 | * through to last case. | |
475 | * - Destination page does not exist, we can add the pipe page to | |
476 | * the page cache and avoid the copy. | |
477 | * | |
83f9135b JA |
478 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
479 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
480 | * file address space page cache. This is possible if no one else has | |
481 | * the pipe page referenced outside of the pipe and page cache. If | |
482 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
483 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 JA |
484 | */ |
485 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
486 | struct splice_desc *sd) | |
487 | { | |
488 | struct file *file = sd->file; | |
489 | struct address_space *mapping = file->f_mapping; | |
3e7ee3e7 | 490 | gfp_t gfp_mask = mapping_gfp_mask(mapping); |
5274f052 JA |
491 | unsigned int offset; |
492 | struct page *page; | |
5274f052 | 493 | pgoff_t index; |
5abc97aa | 494 | char *src; |
3e7ee3e7 | 495 | int ret; |
5274f052 JA |
496 | |
497 | /* | |
49d0b21b | 498 | * make sure the data in this buffer is uptodate |
5274f052 JA |
499 | */ |
500 | src = buf->ops->map(file, info, buf); | |
501 | if (IS_ERR(src)) | |
502 | return PTR_ERR(src); | |
503 | ||
504 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
505 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
506 | ||
5274f052 | 507 | /* |
73d62d83 | 508 | * Reuse buf page, if SPLICE_F_MOVE is set. |
5274f052 | 509 | */ |
5abc97aa | 510 | if (sd->flags & SPLICE_F_MOVE) { |
83f9135b JA |
511 | /* |
512 | * If steal succeeds, buf->page is now pruned from the vm | |
9e0267c2 JA |
513 | * side (LRU and page cache) and we can reuse it. The page |
514 | * will also be looked on successful return. | |
83f9135b | 515 | */ |
5abc97aa JA |
516 | if (buf->ops->steal(info, buf)) |
517 | goto find_page; | |
518 | ||
519 | page = buf->page; | |
3e7ee3e7 | 520 | if (add_to_page_cache(page, mapping, index, gfp_mask)) |
5abc97aa | 521 | goto find_page; |
3e7ee3e7 JA |
522 | |
523 | if (!(buf->flags & PIPE_BUF_FLAG_LRU)) | |
524 | lru_cache_add(page); | |
5abc97aa JA |
525 | } else { |
526 | find_page: | |
9e0267c2 JA |
527 | page = find_lock_page(mapping, index); |
528 | if (!page) { | |
529 | ret = -ENOMEM; | |
530 | page = page_cache_alloc_cold(mapping); | |
531 | if (unlikely(!page)) | |
532 | goto out_nomem; | |
533 | ||
534 | /* | |
535 | * This will also lock the page | |
536 | */ | |
537 | ret = add_to_page_cache_lru(page, mapping, index, | |
538 | gfp_mask); | |
539 | if (unlikely(ret)) | |
540 | goto out; | |
541 | } | |
5abc97aa JA |
542 | |
543 | /* | |
9e0267c2 JA |
544 | * We get here with the page locked. If the page is also |
545 | * uptodate, we don't need to do more. If it isn't, we | |
546 | * may need to bring it in if we are not going to overwrite | |
547 | * the full page. | |
5abc97aa JA |
548 | */ |
549 | if (!PageUptodate(page)) { | |
550 | if (sd->len < PAGE_CACHE_SIZE) { | |
551 | ret = mapping->a_ops->readpage(file, page); | |
552 | if (unlikely(ret)) | |
553 | goto out; | |
554 | ||
555 | lock_page(page); | |
556 | ||
557 | if (!PageUptodate(page)) { | |
558 | /* | |
73d62d83 | 559 | * Page got invalidated, repeat. |
5abc97aa JA |
560 | */ |
561 | if (!page->mapping) { | |
562 | unlock_page(page); | |
563 | page_cache_release(page); | |
564 | goto find_page; | |
565 | } | |
566 | ret = -EIO; | |
567 | goto out; | |
5274f052 | 568 | } |
9e0267c2 | 569 | } else |
5abc97aa | 570 | SetPageUptodate(page); |
5274f052 JA |
571 | } |
572 | } | |
573 | ||
574 | ret = mapping->a_ops->prepare_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
575 | if (ret == AOP_TRUNCATED_PAGE) { |
576 | page_cache_release(page); | |
577 | goto find_page; | |
578 | } else if (ret) | |
5274f052 JA |
579 | goto out; |
580 | ||
3e7ee3e7 | 581 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa JA |
582 | char *dst = kmap_atomic(page, KM_USER0); |
583 | ||
584 | memcpy(dst + offset, src + buf->offset, sd->len); | |
585 | flush_dcache_page(page); | |
586 | kunmap_atomic(dst, KM_USER0); | |
587 | } | |
5274f052 JA |
588 | |
589 | ret = mapping->a_ops->commit_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
590 | if (ret == AOP_TRUNCATED_PAGE) { |
591 | page_cache_release(page); | |
592 | goto find_page; | |
593 | } else if (ret) | |
5274f052 JA |
594 | goto out; |
595 | ||
c7f21e4f | 596 | mark_page_accessed(page); |
4f6f0bd2 | 597 | balance_dirty_pages_ratelimited(mapping); |
5274f052 | 598 | out: |
9e0267c2 | 599 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) |
5abc97aa | 600 | page_cache_release(page); |
9e0267c2 JA |
601 | |
602 | unlock_page(page); | |
9aefe431 | 603 | out_nomem: |
5274f052 JA |
604 | buf->ops->unmap(info, buf); |
605 | return ret; | |
606 | } | |
607 | ||
608 | typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, | |
609 | struct splice_desc *); | |
610 | ||
83f9135b JA |
611 | /* |
612 | * Pipe input worker. Most of this logic works like a regular pipe, the | |
613 | * key here is the 'actor' worker passed in that actually moves the data | |
614 | * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. | |
615 | */ | |
3a326a2c | 616 | static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 617 | loff_t *ppos, size_t len, unsigned int flags, |
5274f052 JA |
618 | splice_actor *actor) |
619 | { | |
5274f052 JA |
620 | int ret, do_wakeup, err; |
621 | struct splice_desc sd; | |
622 | ||
623 | ret = 0; | |
624 | do_wakeup = 0; | |
625 | ||
626 | sd.total_len = len; | |
627 | sd.flags = flags; | |
628 | sd.file = out; | |
cbb7e577 | 629 | sd.pos = *ppos; |
5274f052 | 630 | |
3a326a2c IM |
631 | if (pipe->inode) |
632 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 633 | |
5274f052 | 634 | for (;;) { |
6f767b04 JA |
635 | if (pipe->nrbufs) { |
636 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
5274f052 JA |
637 | struct pipe_buf_operations *ops = buf->ops; |
638 | ||
639 | sd.len = buf->len; | |
640 | if (sd.len > sd.total_len) | |
641 | sd.len = sd.total_len; | |
642 | ||
3a326a2c | 643 | err = actor(pipe, buf, &sd); |
5274f052 JA |
644 | if (err) { |
645 | if (!ret && err != -ENODATA) | |
646 | ret = err; | |
647 | ||
648 | break; | |
649 | } | |
650 | ||
651 | ret += sd.len; | |
652 | buf->offset += sd.len; | |
653 | buf->len -= sd.len; | |
73d62d83 | 654 | |
5274f052 JA |
655 | if (!buf->len) { |
656 | buf->ops = NULL; | |
3a326a2c | 657 | ops->release(pipe, buf); |
6f767b04 JA |
658 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
659 | pipe->nrbufs--; | |
660 | if (pipe->inode) | |
661 | do_wakeup = 1; | |
5274f052 JA |
662 | } |
663 | ||
664 | sd.pos += sd.len; | |
665 | sd.total_len -= sd.len; | |
666 | if (!sd.total_len) | |
667 | break; | |
668 | } | |
669 | ||
6f767b04 | 670 | if (pipe->nrbufs) |
5274f052 | 671 | continue; |
3a326a2c | 672 | if (!pipe->writers) |
5274f052 | 673 | break; |
3a326a2c | 674 | if (!pipe->waiting_writers) { |
5274f052 JA |
675 | if (ret) |
676 | break; | |
677 | } | |
678 | ||
29e35094 LT |
679 | if (flags & SPLICE_F_NONBLOCK) { |
680 | if (!ret) | |
681 | ret = -EAGAIN; | |
682 | break; | |
683 | } | |
684 | ||
5274f052 JA |
685 | if (signal_pending(current)) { |
686 | if (!ret) | |
687 | ret = -ERESTARTSYS; | |
688 | break; | |
689 | } | |
690 | ||
691 | if (do_wakeup) { | |
c0bd1f65 | 692 | smp_mb(); |
3a326a2c IM |
693 | if (waitqueue_active(&pipe->wait)) |
694 | wake_up_interruptible_sync(&pipe->wait); | |
695 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
696 | do_wakeup = 0; |
697 | } | |
698 | ||
3a326a2c | 699 | pipe_wait(pipe); |
5274f052 JA |
700 | } |
701 | ||
3a326a2c IM |
702 | if (pipe->inode) |
703 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
704 | |
705 | if (do_wakeup) { | |
c0bd1f65 | 706 | smp_mb(); |
3a326a2c IM |
707 | if (waitqueue_active(&pipe->wait)) |
708 | wake_up_interruptible(&pipe->wait); | |
709 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
710 | } |
711 | ||
5274f052 | 712 | return ret; |
5274f052 JA |
713 | } |
714 | ||
83f9135b JA |
715 | /** |
716 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 717 | * @pipe: pipe info |
83f9135b JA |
718 | * @out: file to write to |
719 | * @len: number of bytes to splice | |
720 | * @flags: splice modifier flags | |
721 | * | |
722 | * Will either move or copy pages (determined by @flags options) from | |
723 | * the given pipe inode to the given file. | |
724 | * | |
725 | */ | |
3a326a2c IM |
726 | ssize_t |
727 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
cbb7e577 | 728 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 729 | { |
4f6f0bd2 | 730 | struct address_space *mapping = out->f_mapping; |
3a326a2c IM |
731 | ssize_t ret; |
732 | ||
cbb7e577 | 733 | ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file); |
a4514ebd | 734 | if (ret > 0) { |
4f6f0bd2 | 735 | struct inode *inode = mapping->host; |
4f6f0bd2 | 736 | |
a4514ebd JA |
737 | *ppos += ret; |
738 | ||
739 | /* | |
740 | * If file or inode is SYNC and we actually wrote some data, | |
741 | * sync it. | |
742 | */ | |
743 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
744 | int err; | |
745 | ||
746 | mutex_lock(&inode->i_mutex); | |
747 | err = generic_osync_inode(inode, mapping, | |
748 | OSYNC_METADATA|OSYNC_DATA); | |
749 | mutex_unlock(&inode->i_mutex); | |
4f6f0bd2 | 750 | |
a4514ebd JA |
751 | if (err) |
752 | ret = err; | |
753 | } | |
4f6f0bd2 JA |
754 | } |
755 | ||
756 | return ret; | |
5274f052 JA |
757 | } |
758 | ||
059a8f37 JA |
759 | EXPORT_SYMBOL(generic_file_splice_write); |
760 | ||
83f9135b JA |
761 | /** |
762 | * generic_splice_sendpage - splice data from a pipe to a socket | |
763 | * @inode: pipe inode | |
764 | * @out: socket to write to | |
765 | * @len: number of bytes to splice | |
766 | * @flags: splice modifier flags | |
767 | * | |
768 | * Will send @len bytes from the pipe to a network socket. No data copying | |
769 | * is involved. | |
770 | * | |
771 | */ | |
3a326a2c | 772 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 773 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 774 | { |
cbb7e577 | 775 | return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
776 | } |
777 | ||
059a8f37 | 778 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 779 | |
83f9135b JA |
780 | /* |
781 | * Attempt to initiate a splice from pipe to file. | |
782 | */ | |
3a326a2c | 783 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 784 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 785 | { |
5274f052 JA |
786 | int ret; |
787 | ||
49570e9b | 788 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
789 | return -EINVAL; |
790 | ||
49570e9b | 791 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
792 | return -EBADF; |
793 | ||
cbb7e577 | 794 | ret = rw_verify_area(WRITE, out, ppos, len); |
5274f052 JA |
795 | if (unlikely(ret < 0)) |
796 | return ret; | |
797 | ||
cbb7e577 | 798 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
799 | } |
800 | ||
83f9135b JA |
801 | /* |
802 | * Attempt to initiate a splice from a file to a pipe. | |
803 | */ | |
cbb7e577 JA |
804 | static long do_splice_to(struct file *in, loff_t *ppos, |
805 | struct pipe_inode_info *pipe, size_t len, | |
806 | unsigned int flags) | |
5274f052 | 807 | { |
cbb7e577 | 808 | loff_t isize, left; |
5274f052 JA |
809 | int ret; |
810 | ||
49570e9b | 811 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
812 | return -EINVAL; |
813 | ||
49570e9b | 814 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
815 | return -EBADF; |
816 | ||
cbb7e577 | 817 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
818 | if (unlikely(ret < 0)) |
819 | return ret; | |
820 | ||
821 | isize = i_size_read(in->f_mapping->host); | |
cbb7e577 | 822 | if (unlikely(*ppos >= isize)) |
5274f052 JA |
823 | return 0; |
824 | ||
cbb7e577 | 825 | left = isize - *ppos; |
49570e9b | 826 | if (unlikely(left < len)) |
5274f052 JA |
827 | len = left; |
828 | ||
cbb7e577 | 829 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 JA |
830 | } |
831 | ||
cbb7e577 JA |
832 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
833 | size_t len, unsigned int flags) | |
b92ce558 JA |
834 | { |
835 | struct pipe_inode_info *pipe; | |
836 | long ret, bytes; | |
cbb7e577 | 837 | loff_t out_off; |
b92ce558 JA |
838 | umode_t i_mode; |
839 | int i; | |
840 | ||
841 | /* | |
842 | * We require the input being a regular file, as we don't want to | |
843 | * randomly drop data for eg socket -> socket splicing. Use the | |
844 | * piped splicing for that! | |
845 | */ | |
846 | i_mode = in->f_dentry->d_inode->i_mode; | |
847 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
848 | return -EINVAL; | |
849 | ||
850 | /* | |
851 | * neither in nor out is a pipe, setup an internal pipe attached to | |
852 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
853 | */ | |
854 | pipe = current->splice_pipe; | |
49570e9b | 855 | if (unlikely(!pipe)) { |
b92ce558 JA |
856 | pipe = alloc_pipe_info(NULL); |
857 | if (!pipe) | |
858 | return -ENOMEM; | |
859 | ||
860 | /* | |
861 | * We don't have an immediate reader, but we'll read the stuff | |
862 | * out of the pipe right after the move_to_pipe(). So set | |
863 | * PIPE_READERS appropriately. | |
864 | */ | |
865 | pipe->readers = 1; | |
866 | ||
867 | current->splice_pipe = pipe; | |
868 | } | |
869 | ||
870 | /* | |
73d62d83 | 871 | * Do the splice. |
b92ce558 JA |
872 | */ |
873 | ret = 0; | |
874 | bytes = 0; | |
cbb7e577 | 875 | out_off = 0; |
b92ce558 JA |
876 | |
877 | while (len) { | |
878 | size_t read_len, max_read_len; | |
879 | ||
880 | /* | |
881 | * Do at most PIPE_BUFFERS pages worth of transfer: | |
882 | */ | |
883 | max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); | |
884 | ||
cbb7e577 | 885 | ret = do_splice_to(in, ppos, pipe, max_read_len, flags); |
b92ce558 JA |
886 | if (unlikely(ret < 0)) |
887 | goto out_release; | |
888 | ||
889 | read_len = ret; | |
890 | ||
891 | /* | |
892 | * NOTE: nonblocking mode only applies to the input. We | |
893 | * must not do the output in nonblocking mode as then we | |
894 | * could get stuck data in the internal pipe: | |
895 | */ | |
cbb7e577 | 896 | ret = do_splice_from(pipe, out, &out_off, read_len, |
b92ce558 JA |
897 | flags & ~SPLICE_F_NONBLOCK); |
898 | if (unlikely(ret < 0)) | |
899 | goto out_release; | |
900 | ||
901 | bytes += ret; | |
902 | len -= ret; | |
903 | ||
904 | /* | |
905 | * In nonblocking mode, if we got back a short read then | |
906 | * that was due to either an IO error or due to the | |
907 | * pagecache entry not being there. In the IO error case | |
908 | * the _next_ splice attempt will produce a clean IO error | |
909 | * return value (not a short read), so in both cases it's | |
910 | * correct to break out of the loop here: | |
911 | */ | |
912 | if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) | |
913 | break; | |
914 | } | |
915 | ||
916 | pipe->nrbufs = pipe->curbuf = 0; | |
917 | ||
918 | return bytes; | |
919 | ||
920 | out_release: | |
921 | /* | |
922 | * If we did an incomplete transfer we must release | |
923 | * the pipe buffers in question: | |
924 | */ | |
925 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
926 | struct pipe_buffer *buf = pipe->bufs + i; | |
927 | ||
928 | if (buf->ops) { | |
929 | buf->ops->release(pipe, buf); | |
930 | buf->ops = NULL; | |
931 | } | |
932 | } | |
933 | pipe->nrbufs = pipe->curbuf = 0; | |
934 | ||
935 | /* | |
936 | * If we transferred some data, return the number of bytes: | |
937 | */ | |
938 | if (bytes > 0) | |
939 | return bytes; | |
940 | ||
941 | return ret; | |
942 | } | |
943 | ||
944 | EXPORT_SYMBOL(do_splice_direct); | |
945 | ||
83f9135b JA |
946 | /* |
947 | * Determine where to splice to/from. | |
948 | */ | |
529565dc IM |
949 | static long do_splice(struct file *in, loff_t __user *off_in, |
950 | struct file *out, loff_t __user *off_out, | |
951 | size_t len, unsigned int flags) | |
5274f052 | 952 | { |
3a326a2c | 953 | struct pipe_inode_info *pipe; |
cbb7e577 | 954 | loff_t offset, *off; |
a4514ebd | 955 | long ret; |
5274f052 | 956 | |
3a326a2c | 957 | pipe = in->f_dentry->d_inode->i_pipe; |
529565dc IM |
958 | if (pipe) { |
959 | if (off_in) | |
960 | return -ESPIPE; | |
b92ce558 JA |
961 | if (off_out) { |
962 | if (out->f_op->llseek == no_llseek) | |
963 | return -EINVAL; | |
cbb7e577 | 964 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 965 | return -EFAULT; |
cbb7e577 JA |
966 | off = &offset; |
967 | } else | |
968 | off = &out->f_pos; | |
529565dc | 969 | |
a4514ebd JA |
970 | ret = do_splice_from(pipe, out, off, len, flags); |
971 | ||
972 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
973 | ret = -EFAULT; | |
974 | ||
975 | return ret; | |
529565dc | 976 | } |
5274f052 | 977 | |
3a326a2c | 978 | pipe = out->f_dentry->d_inode->i_pipe; |
529565dc IM |
979 | if (pipe) { |
980 | if (off_out) | |
981 | return -ESPIPE; | |
b92ce558 JA |
982 | if (off_in) { |
983 | if (in->f_op->llseek == no_llseek) | |
984 | return -EINVAL; | |
cbb7e577 | 985 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 986 | return -EFAULT; |
cbb7e577 JA |
987 | off = &offset; |
988 | } else | |
989 | off = &in->f_pos; | |
529565dc | 990 | |
a4514ebd JA |
991 | ret = do_splice_to(in, off, pipe, len, flags); |
992 | ||
993 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
994 | ret = -EFAULT; | |
995 | ||
996 | return ret; | |
529565dc | 997 | } |
5274f052 JA |
998 | |
999 | return -EINVAL; | |
1000 | } | |
1001 | ||
529565dc IM |
1002 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
1003 | int fd_out, loff_t __user *off_out, | |
1004 | size_t len, unsigned int flags) | |
5274f052 JA |
1005 | { |
1006 | long error; | |
1007 | struct file *in, *out; | |
1008 | int fput_in, fput_out; | |
1009 | ||
1010 | if (unlikely(!len)) | |
1011 | return 0; | |
1012 | ||
1013 | error = -EBADF; | |
529565dc | 1014 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
1015 | if (in) { |
1016 | if (in->f_mode & FMODE_READ) { | |
529565dc | 1017 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
1018 | if (out) { |
1019 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
1020 | error = do_splice(in, off_in, |
1021 | out, off_out, | |
1022 | len, flags); | |
5274f052 JA |
1023 | fput_light(out, fput_out); |
1024 | } | |
1025 | } | |
1026 | ||
1027 | fput_light(in, fput_in); | |
1028 | } | |
1029 | ||
1030 | return error; | |
1031 | } | |
70524490 JA |
1032 | |
1033 | /* | |
1034 | * Link contents of ipipe to opipe. | |
1035 | */ | |
1036 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1037 | struct pipe_inode_info *opipe, | |
1038 | size_t len, unsigned int flags) | |
1039 | { | |
1040 | struct pipe_buffer *ibuf, *obuf; | |
2a27250e JA |
1041 | int ret, do_wakeup, i, ipipe_first; |
1042 | ||
1043 | ret = do_wakeup = ipipe_first = 0; | |
70524490 JA |
1044 | |
1045 | /* | |
1046 | * Potential ABBA deadlock, work around it by ordering lock | |
1047 | * grabbing by inode address. Otherwise two different processes | |
1048 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1049 | */ | |
1050 | if (ipipe->inode < opipe->inode) { | |
2a27250e | 1051 | ipipe_first = 1; |
70524490 JA |
1052 | mutex_lock(&ipipe->inode->i_mutex); |
1053 | mutex_lock(&opipe->inode->i_mutex); | |
1054 | } else { | |
1055 | mutex_lock(&opipe->inode->i_mutex); | |
1056 | mutex_lock(&ipipe->inode->i_mutex); | |
1057 | } | |
1058 | ||
1059 | for (i = 0;; i++) { | |
1060 | if (!opipe->readers) { | |
1061 | send_sig(SIGPIPE, current, 0); | |
1062 | if (!ret) | |
1063 | ret = -EPIPE; | |
1064 | break; | |
1065 | } | |
1066 | if (ipipe->nrbufs - i) { | |
1067 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); | |
1068 | ||
1069 | /* | |
1070 | * If we have room, fill this buffer | |
1071 | */ | |
1072 | if (opipe->nrbufs < PIPE_BUFFERS) { | |
1073 | int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); | |
1074 | ||
1075 | /* | |
1076 | * Get a reference to this pipe buffer, | |
1077 | * so we can copy the contents over. | |
1078 | */ | |
1079 | ibuf->ops->get(ipipe, ibuf); | |
1080 | ||
1081 | obuf = opipe->bufs + nbuf; | |
1082 | *obuf = *ibuf; | |
1083 | ||
1084 | if (obuf->len > len) | |
1085 | obuf->len = len; | |
1086 | ||
1087 | opipe->nrbufs++; | |
1088 | do_wakeup = 1; | |
1089 | ret += obuf->len; | |
1090 | len -= obuf->len; | |
1091 | ||
1092 | if (!len) | |
1093 | break; | |
1094 | if (opipe->nrbufs < PIPE_BUFFERS) | |
1095 | continue; | |
1096 | } | |
1097 | ||
1098 | /* | |
1099 | * We have input available, but no output room. | |
2a27250e JA |
1100 | * If we already copied data, return that. If we |
1101 | * need to drop the opipe lock, it must be ordered | |
1102 | * last to avoid deadlocks. | |
70524490 | 1103 | */ |
2a27250e | 1104 | if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) { |
70524490 JA |
1105 | if (!ret) |
1106 | ret = -EAGAIN; | |
1107 | break; | |
1108 | } | |
1109 | if (signal_pending(current)) { | |
1110 | if (!ret) | |
1111 | ret = -ERESTARTSYS; | |
1112 | break; | |
1113 | } | |
1114 | if (do_wakeup) { | |
1115 | smp_mb(); | |
1116 | if (waitqueue_active(&opipe->wait)) | |
1117 | wake_up_interruptible(&opipe->wait); | |
1118 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1119 | do_wakeup = 0; | |
1120 | } | |
1121 | ||
1122 | opipe->waiting_writers++; | |
1123 | pipe_wait(opipe); | |
1124 | opipe->waiting_writers--; | |
1125 | continue; | |
1126 | } | |
1127 | ||
1128 | /* | |
1129 | * No input buffers, do the usual checks for available | |
1130 | * writers and blocking and wait if necessary | |
1131 | */ | |
1132 | if (!ipipe->writers) | |
1133 | break; | |
1134 | if (!ipipe->waiting_writers) { | |
1135 | if (ret) | |
1136 | break; | |
1137 | } | |
2a27250e JA |
1138 | /* |
1139 | * pipe_wait() drops the ipipe mutex. To avoid deadlocks | |
1140 | * with another process, we can only safely do that if | |
1141 | * the ipipe lock is ordered last. | |
1142 | */ | |
1143 | if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) { | |
70524490 JA |
1144 | if (!ret) |
1145 | ret = -EAGAIN; | |
1146 | break; | |
1147 | } | |
1148 | if (signal_pending(current)) { | |
1149 | if (!ret) | |
1150 | ret = -ERESTARTSYS; | |
1151 | break; | |
1152 | } | |
1153 | ||
1154 | if (waitqueue_active(&ipipe->wait)) | |
1155 | wake_up_interruptible_sync(&ipipe->wait); | |
1156 | kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT); | |
1157 | ||
1158 | pipe_wait(ipipe); | |
1159 | } | |
1160 | ||
1161 | mutex_unlock(&ipipe->inode->i_mutex); | |
1162 | mutex_unlock(&opipe->inode->i_mutex); | |
1163 | ||
1164 | if (do_wakeup) { | |
1165 | smp_mb(); | |
1166 | if (waitqueue_active(&opipe->wait)) | |
1167 | wake_up_interruptible(&opipe->wait); | |
1168 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1169 | } | |
1170 | ||
1171 | return ret; | |
1172 | } | |
1173 | ||
1174 | /* | |
1175 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1176 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1177 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1178 | * applicable one is SPLICE_F_NONBLOCK. | |
1179 | */ | |
1180 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1181 | unsigned int flags) | |
1182 | { | |
1183 | struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe; | |
1184 | struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe; | |
1185 | ||
1186 | /* | |
1187 | * Link ipipe to the two output pipes, consuming as we go along. | |
1188 | */ | |
1189 | if (ipipe && opipe) | |
1190 | return link_pipe(ipipe, opipe, len, flags); | |
1191 | ||
1192 | return -EINVAL; | |
1193 | } | |
1194 | ||
1195 | asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) | |
1196 | { | |
1197 | struct file *in; | |
1198 | int error, fput_in; | |
1199 | ||
1200 | if (unlikely(!len)) | |
1201 | return 0; | |
1202 | ||
1203 | error = -EBADF; | |
1204 | in = fget_light(fdin, &fput_in); | |
1205 | if (in) { | |
1206 | if (in->f_mode & FMODE_READ) { | |
1207 | int fput_out; | |
1208 | struct file *out = fget_light(fdout, &fput_out); | |
1209 | ||
1210 | if (out) { | |
1211 | if (out->f_mode & FMODE_WRITE) | |
1212 | error = do_tee(in, out, len, flags); | |
1213 | fput_light(out, fput_out); | |
1214 | } | |
1215 | } | |
1216 | fput_light(in, fput_in); | |
1217 | } | |
1218 | ||
1219 | return error; | |
1220 | } |