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++) { |
82aa5d61 JA |
278 | unsigned int this_len; |
279 | ||
280 | if (!len) | |
281 | break; | |
282 | ||
283 | /* | |
284 | * this_len is the max we'll use from this page | |
285 | */ | |
286 | this_len = min(len, PAGE_CACHE_SIZE - loff); | |
7480a904 | 287 | find_page: |
5274f052 | 288 | /* |
7480a904 | 289 | * lookup the page for this index |
5274f052 | 290 | */ |
7480a904 JA |
291 | page = find_get_page(mapping, index); |
292 | if (!page) { | |
7480a904 JA |
293 | /* |
294 | * page didn't exist, allocate one | |
295 | */ | |
296 | page = page_cache_alloc_cold(mapping); | |
297 | if (!page) | |
298 | break; | |
299 | ||
300 | error = add_to_page_cache_lru(page, mapping, index, | |
301 | mapping_gfp_mask(mapping)); | |
302 | if (unlikely(error)) { | |
303 | page_cache_release(page); | |
304 | break; | |
305 | } | |
306 | ||
307 | goto readpage; | |
308 | } | |
309 | ||
310 | /* | |
311 | * If the page isn't uptodate, we may need to start io on it | |
312 | */ | |
313 | if (!PageUptodate(page)) { | |
c4f895cb JA |
314 | /* |
315 | * If in nonblock mode then dont block on waiting | |
316 | * for an in-flight io page | |
317 | */ | |
318 | if (flags & SPLICE_F_NONBLOCK) | |
319 | break; | |
320 | ||
7480a904 JA |
321 | lock_page(page); |
322 | ||
323 | /* | |
324 | * page was truncated, stop here. if this isn't the | |
325 | * first page, we'll just complete what we already | |
326 | * added | |
327 | */ | |
328 | if (!page->mapping) { | |
329 | unlock_page(page); | |
330 | page_cache_release(page); | |
331 | break; | |
332 | } | |
333 | /* | |
334 | * page was already under io and is now done, great | |
335 | */ | |
336 | if (PageUptodate(page)) { | |
337 | unlock_page(page); | |
338 | goto fill_it; | |
339 | } | |
5274f052 | 340 | |
7480a904 JA |
341 | readpage: |
342 | /* | |
343 | * need to read in the page | |
344 | */ | |
345 | error = mapping->a_ops->readpage(in, page); | |
5274f052 JA |
346 | |
347 | if (unlikely(error)) { | |
348 | page_cache_release(page); | |
7480a904 JA |
349 | if (error == AOP_TRUNCATED_PAGE) |
350 | goto find_page; | |
5274f052 JA |
351 | break; |
352 | } | |
91ad66ef JA |
353 | |
354 | /* | |
355 | * i_size must be checked after ->readpage(). | |
356 | */ | |
357 | isize = i_size_read(mapping->host); | |
358 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
359 | if (unlikely(!isize || index > end_index)) { | |
360 | page_cache_release(page); | |
361 | break; | |
362 | } | |
363 | ||
364 | /* | |
365 | * if this is the last page, see if we need to shrink | |
366 | * the length and stop | |
367 | */ | |
368 | if (end_index == index) { | |
369 | loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK); | |
370 | if (bytes + loff > isize) { | |
371 | page_cache_release(page); | |
372 | break; | |
373 | } | |
374 | /* | |
375 | * force quit after adding this page | |
376 | */ | |
377 | nr_pages = i; | |
82aa5d61 | 378 | this_len = min(this_len, loff); |
91ad66ef | 379 | } |
5274f052 | 380 | } |
7480a904 | 381 | fill_it: |
16c523dd | 382 | pages[i] = page; |
82aa5d61 JA |
383 | bytes += this_len; |
384 | len -= this_len; | |
91ad66ef | 385 | loff = 0; |
5274f052 JA |
386 | } |
387 | ||
16c523dd | 388 | if (i) |
91ad66ef | 389 | return move_to_pipe(pipe, pages, i, bytes, offset, flags); |
5274f052 | 390 | |
7480a904 | 391 | return error; |
5274f052 JA |
392 | } |
393 | ||
83f9135b JA |
394 | /** |
395 | * generic_file_splice_read - splice data from file to a pipe | |
396 | * @in: file to splice from | |
397 | * @pipe: pipe to splice to | |
398 | * @len: number of bytes to splice | |
399 | * @flags: splice modifier flags | |
400 | * | |
401 | * Will read pages from given file and fill them into a pipe. | |
83f9135b | 402 | */ |
cbb7e577 JA |
403 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
404 | struct pipe_inode_info *pipe, size_t len, | |
405 | unsigned int flags) | |
5274f052 JA |
406 | { |
407 | ssize_t spliced; | |
408 | int ret; | |
409 | ||
410 | ret = 0; | |
411 | spliced = 0; | |
3a326a2c | 412 | |
5274f052 | 413 | while (len) { |
cbb7e577 | 414 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
5274f052 | 415 | |
c4f895cb | 416 | if (ret < 0) |
5274f052 | 417 | break; |
c4f895cb JA |
418 | else if (!ret) { |
419 | if (spliced) | |
420 | break; | |
421 | if (flags & SPLICE_F_NONBLOCK) { | |
422 | ret = -EAGAIN; | |
423 | break; | |
424 | } | |
425 | } | |
5274f052 | 426 | |
cbb7e577 | 427 | *ppos += ret; |
5274f052 JA |
428 | len -= ret; |
429 | spliced += ret; | |
430 | } | |
431 | ||
432 | if (spliced) | |
433 | return spliced; | |
434 | ||
435 | return ret; | |
436 | } | |
437 | ||
059a8f37 JA |
438 | EXPORT_SYMBOL(generic_file_splice_read); |
439 | ||
5274f052 | 440 | /* |
4f6f0bd2 JA |
441 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
442 | * using sendpage(). | |
5274f052 JA |
443 | */ |
444 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
445 | struct pipe_buffer *buf, struct splice_desc *sd) | |
446 | { | |
447 | struct file *file = sd->file; | |
448 | loff_t pos = sd->pos; | |
449 | unsigned int offset; | |
450 | ssize_t ret; | |
451 | void *ptr; | |
b2b39fa4 | 452 | int more; |
5274f052 JA |
453 | |
454 | /* | |
73d62d83 | 455 | * Sub-optimal, but we are limited by the pipe ->map. We don't |
5274f052 JA |
456 | * need a kmap'ed buffer here, we just want to make sure we |
457 | * have the page pinned if the pipe page originates from the | |
73d62d83 | 458 | * page cache. |
5274f052 JA |
459 | */ |
460 | ptr = buf->ops->map(file, info, buf); | |
461 | if (IS_ERR(ptr)) | |
462 | return PTR_ERR(ptr); | |
463 | ||
464 | offset = pos & ~PAGE_CACHE_MASK; | |
b2b39fa4 | 465 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
5274f052 | 466 | |
b2b39fa4 | 467 | ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more); |
5274f052 JA |
468 | |
469 | buf->ops->unmap(info, buf); | |
470 | if (ret == sd->len) | |
471 | return 0; | |
472 | ||
473 | return -EIO; | |
474 | } | |
475 | ||
476 | /* | |
477 | * This is a little more tricky than the file -> pipe splicing. There are | |
478 | * basically three cases: | |
479 | * | |
480 | * - Destination page already exists in the address space and there | |
481 | * are users of it. For that case we have no other option that | |
482 | * copying the data. Tough luck. | |
483 | * - Destination page already exists in the address space, but there | |
484 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
485 | * through to last case. | |
486 | * - Destination page does not exist, we can add the pipe page to | |
487 | * the page cache and avoid the copy. | |
488 | * | |
83f9135b JA |
489 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
490 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
491 | * file address space page cache. This is possible if no one else has | |
492 | * the pipe page referenced outside of the pipe and page cache. If | |
493 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
494 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 JA |
495 | */ |
496 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
497 | struct splice_desc *sd) | |
498 | { | |
499 | struct file *file = sd->file; | |
500 | struct address_space *mapping = file->f_mapping; | |
3e7ee3e7 | 501 | gfp_t gfp_mask = mapping_gfp_mask(mapping); |
5274f052 JA |
502 | unsigned int offset; |
503 | struct page *page; | |
5274f052 | 504 | pgoff_t index; |
5abc97aa | 505 | char *src; |
3e7ee3e7 | 506 | int ret; |
5274f052 JA |
507 | |
508 | /* | |
49d0b21b | 509 | * make sure the data in this buffer is uptodate |
5274f052 JA |
510 | */ |
511 | src = buf->ops->map(file, info, buf); | |
512 | if (IS_ERR(src)) | |
513 | return PTR_ERR(src); | |
514 | ||
515 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
516 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
517 | ||
5274f052 | 518 | /* |
73d62d83 | 519 | * Reuse buf page, if SPLICE_F_MOVE is set. |
5274f052 | 520 | */ |
5abc97aa | 521 | if (sd->flags & SPLICE_F_MOVE) { |
83f9135b JA |
522 | /* |
523 | * If steal succeeds, buf->page is now pruned from the vm | |
9e0267c2 JA |
524 | * side (LRU and page cache) and we can reuse it. The page |
525 | * will also be looked on successful return. | |
83f9135b | 526 | */ |
5abc97aa JA |
527 | if (buf->ops->steal(info, buf)) |
528 | goto find_page; | |
529 | ||
530 | page = buf->page; | |
3e7ee3e7 | 531 | if (add_to_page_cache(page, mapping, index, gfp_mask)) |
5abc97aa | 532 | goto find_page; |
3e7ee3e7 JA |
533 | |
534 | if (!(buf->flags & PIPE_BUF_FLAG_LRU)) | |
535 | lru_cache_add(page); | |
5abc97aa JA |
536 | } else { |
537 | find_page: | |
9e0267c2 JA |
538 | page = find_lock_page(mapping, index); |
539 | if (!page) { | |
540 | ret = -ENOMEM; | |
541 | page = page_cache_alloc_cold(mapping); | |
542 | if (unlikely(!page)) | |
543 | goto out_nomem; | |
544 | ||
545 | /* | |
546 | * This will also lock the page | |
547 | */ | |
548 | ret = add_to_page_cache_lru(page, mapping, index, | |
549 | gfp_mask); | |
550 | if (unlikely(ret)) | |
551 | goto out; | |
552 | } | |
5abc97aa JA |
553 | |
554 | /* | |
9e0267c2 JA |
555 | * We get here with the page locked. If the page is also |
556 | * uptodate, we don't need to do more. If it isn't, we | |
557 | * may need to bring it in if we are not going to overwrite | |
558 | * the full page. | |
5abc97aa JA |
559 | */ |
560 | if (!PageUptodate(page)) { | |
561 | if (sd->len < PAGE_CACHE_SIZE) { | |
562 | ret = mapping->a_ops->readpage(file, page); | |
563 | if (unlikely(ret)) | |
564 | goto out; | |
565 | ||
566 | lock_page(page); | |
567 | ||
568 | if (!PageUptodate(page)) { | |
569 | /* | |
73d62d83 | 570 | * Page got invalidated, repeat. |
5abc97aa JA |
571 | */ |
572 | if (!page->mapping) { | |
573 | unlock_page(page); | |
574 | page_cache_release(page); | |
575 | goto find_page; | |
576 | } | |
577 | ret = -EIO; | |
578 | goto out; | |
5274f052 | 579 | } |
9e0267c2 | 580 | } else |
5abc97aa | 581 | SetPageUptodate(page); |
5274f052 JA |
582 | } |
583 | } | |
584 | ||
585 | ret = mapping->a_ops->prepare_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
586 | if (ret == AOP_TRUNCATED_PAGE) { |
587 | page_cache_release(page); | |
588 | goto find_page; | |
589 | } else if (ret) | |
5274f052 JA |
590 | goto out; |
591 | ||
3e7ee3e7 | 592 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa JA |
593 | char *dst = kmap_atomic(page, KM_USER0); |
594 | ||
595 | memcpy(dst + offset, src + buf->offset, sd->len); | |
596 | flush_dcache_page(page); | |
597 | kunmap_atomic(dst, KM_USER0); | |
598 | } | |
5274f052 JA |
599 | |
600 | ret = mapping->a_ops->commit_write(file, page, 0, sd->len); | |
4f6f0bd2 JA |
601 | if (ret == AOP_TRUNCATED_PAGE) { |
602 | page_cache_release(page); | |
603 | goto find_page; | |
604 | } else if (ret) | |
5274f052 JA |
605 | goto out; |
606 | ||
c7f21e4f | 607 | mark_page_accessed(page); |
4f6f0bd2 | 608 | balance_dirty_pages_ratelimited(mapping); |
5274f052 | 609 | out: |
9e0267c2 | 610 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) |
5abc97aa | 611 | page_cache_release(page); |
9e0267c2 JA |
612 | |
613 | unlock_page(page); | |
9aefe431 | 614 | out_nomem: |
5274f052 JA |
615 | buf->ops->unmap(info, buf); |
616 | return ret; | |
617 | } | |
618 | ||
619 | typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, | |
620 | struct splice_desc *); | |
621 | ||
83f9135b JA |
622 | /* |
623 | * Pipe input worker. Most of this logic works like a regular pipe, the | |
624 | * key here is the 'actor' worker passed in that actually moves the data | |
625 | * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. | |
626 | */ | |
3a326a2c | 627 | static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 628 | loff_t *ppos, size_t len, unsigned int flags, |
5274f052 JA |
629 | splice_actor *actor) |
630 | { | |
5274f052 JA |
631 | int ret, do_wakeup, err; |
632 | struct splice_desc sd; | |
633 | ||
634 | ret = 0; | |
635 | do_wakeup = 0; | |
636 | ||
637 | sd.total_len = len; | |
638 | sd.flags = flags; | |
639 | sd.file = out; | |
cbb7e577 | 640 | sd.pos = *ppos; |
5274f052 | 641 | |
3a326a2c IM |
642 | if (pipe->inode) |
643 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 644 | |
5274f052 | 645 | for (;;) { |
6f767b04 JA |
646 | if (pipe->nrbufs) { |
647 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
5274f052 JA |
648 | struct pipe_buf_operations *ops = buf->ops; |
649 | ||
650 | sd.len = buf->len; | |
651 | if (sd.len > sd.total_len) | |
652 | sd.len = sd.total_len; | |
653 | ||
3a326a2c | 654 | err = actor(pipe, buf, &sd); |
5274f052 JA |
655 | if (err) { |
656 | if (!ret && err != -ENODATA) | |
657 | ret = err; | |
658 | ||
659 | break; | |
660 | } | |
661 | ||
662 | ret += sd.len; | |
663 | buf->offset += sd.len; | |
664 | buf->len -= sd.len; | |
73d62d83 | 665 | |
5274f052 JA |
666 | if (!buf->len) { |
667 | buf->ops = NULL; | |
3a326a2c | 668 | ops->release(pipe, buf); |
6f767b04 JA |
669 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
670 | pipe->nrbufs--; | |
671 | if (pipe->inode) | |
672 | do_wakeup = 1; | |
5274f052 JA |
673 | } |
674 | ||
675 | sd.pos += sd.len; | |
676 | sd.total_len -= sd.len; | |
677 | if (!sd.total_len) | |
678 | break; | |
679 | } | |
680 | ||
6f767b04 | 681 | if (pipe->nrbufs) |
5274f052 | 682 | continue; |
3a326a2c | 683 | if (!pipe->writers) |
5274f052 | 684 | break; |
3a326a2c | 685 | if (!pipe->waiting_writers) { |
5274f052 JA |
686 | if (ret) |
687 | break; | |
688 | } | |
689 | ||
29e35094 LT |
690 | if (flags & SPLICE_F_NONBLOCK) { |
691 | if (!ret) | |
692 | ret = -EAGAIN; | |
693 | break; | |
694 | } | |
695 | ||
5274f052 JA |
696 | if (signal_pending(current)) { |
697 | if (!ret) | |
698 | ret = -ERESTARTSYS; | |
699 | break; | |
700 | } | |
701 | ||
702 | if (do_wakeup) { | |
c0bd1f65 | 703 | smp_mb(); |
3a326a2c IM |
704 | if (waitqueue_active(&pipe->wait)) |
705 | wake_up_interruptible_sync(&pipe->wait); | |
706 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
707 | do_wakeup = 0; |
708 | } | |
709 | ||
3a326a2c | 710 | pipe_wait(pipe); |
5274f052 JA |
711 | } |
712 | ||
3a326a2c IM |
713 | if (pipe->inode) |
714 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
715 | |
716 | if (do_wakeup) { | |
c0bd1f65 | 717 | smp_mb(); |
3a326a2c IM |
718 | if (waitqueue_active(&pipe->wait)) |
719 | wake_up_interruptible(&pipe->wait); | |
720 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
721 | } |
722 | ||
5274f052 | 723 | return ret; |
5274f052 JA |
724 | } |
725 | ||
83f9135b JA |
726 | /** |
727 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 728 | * @pipe: pipe info |
83f9135b JA |
729 | * @out: file to write to |
730 | * @len: number of bytes to splice | |
731 | * @flags: splice modifier flags | |
732 | * | |
733 | * Will either move or copy pages (determined by @flags options) from | |
734 | * the given pipe inode to the given file. | |
735 | * | |
736 | */ | |
3a326a2c IM |
737 | ssize_t |
738 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
cbb7e577 | 739 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 740 | { |
4f6f0bd2 | 741 | struct address_space *mapping = out->f_mapping; |
3a326a2c IM |
742 | ssize_t ret; |
743 | ||
cbb7e577 | 744 | ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file); |
a4514ebd | 745 | if (ret > 0) { |
4f6f0bd2 | 746 | struct inode *inode = mapping->host; |
4f6f0bd2 | 747 | |
a4514ebd JA |
748 | *ppos += ret; |
749 | ||
750 | /* | |
751 | * If file or inode is SYNC and we actually wrote some data, | |
752 | * sync it. | |
753 | */ | |
754 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
755 | int err; | |
756 | ||
757 | mutex_lock(&inode->i_mutex); | |
758 | err = generic_osync_inode(inode, mapping, | |
759 | OSYNC_METADATA|OSYNC_DATA); | |
760 | mutex_unlock(&inode->i_mutex); | |
4f6f0bd2 | 761 | |
a4514ebd JA |
762 | if (err) |
763 | ret = err; | |
764 | } | |
4f6f0bd2 JA |
765 | } |
766 | ||
767 | return ret; | |
5274f052 JA |
768 | } |
769 | ||
059a8f37 JA |
770 | EXPORT_SYMBOL(generic_file_splice_write); |
771 | ||
83f9135b JA |
772 | /** |
773 | * generic_splice_sendpage - splice data from a pipe to a socket | |
774 | * @inode: pipe inode | |
775 | * @out: socket to write to | |
776 | * @len: number of bytes to splice | |
777 | * @flags: splice modifier flags | |
778 | * | |
779 | * Will send @len bytes from the pipe to a network socket. No data copying | |
780 | * is involved. | |
781 | * | |
782 | */ | |
3a326a2c | 783 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 784 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 785 | { |
cbb7e577 | 786 | return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
787 | } |
788 | ||
059a8f37 | 789 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 790 | |
83f9135b JA |
791 | /* |
792 | * Attempt to initiate a splice from pipe to file. | |
793 | */ | |
3a326a2c | 794 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 795 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 796 | { |
5274f052 JA |
797 | int ret; |
798 | ||
49570e9b | 799 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
800 | return -EINVAL; |
801 | ||
49570e9b | 802 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
803 | return -EBADF; |
804 | ||
cbb7e577 | 805 | ret = rw_verify_area(WRITE, out, ppos, len); |
5274f052 JA |
806 | if (unlikely(ret < 0)) |
807 | return ret; | |
808 | ||
cbb7e577 | 809 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
810 | } |
811 | ||
83f9135b JA |
812 | /* |
813 | * Attempt to initiate a splice from a file to a pipe. | |
814 | */ | |
cbb7e577 JA |
815 | static long do_splice_to(struct file *in, loff_t *ppos, |
816 | struct pipe_inode_info *pipe, size_t len, | |
817 | unsigned int flags) | |
5274f052 | 818 | { |
cbb7e577 | 819 | loff_t isize, left; |
5274f052 JA |
820 | int ret; |
821 | ||
49570e9b | 822 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
823 | return -EINVAL; |
824 | ||
49570e9b | 825 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
826 | return -EBADF; |
827 | ||
cbb7e577 | 828 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
829 | if (unlikely(ret < 0)) |
830 | return ret; | |
831 | ||
832 | isize = i_size_read(in->f_mapping->host); | |
cbb7e577 | 833 | if (unlikely(*ppos >= isize)) |
5274f052 JA |
834 | return 0; |
835 | ||
cbb7e577 | 836 | left = isize - *ppos; |
49570e9b | 837 | if (unlikely(left < len)) |
5274f052 JA |
838 | len = left; |
839 | ||
cbb7e577 | 840 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 JA |
841 | } |
842 | ||
cbb7e577 JA |
843 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
844 | size_t len, unsigned int flags) | |
b92ce558 JA |
845 | { |
846 | struct pipe_inode_info *pipe; | |
847 | long ret, bytes; | |
cbb7e577 | 848 | loff_t out_off; |
b92ce558 JA |
849 | umode_t i_mode; |
850 | int i; | |
851 | ||
852 | /* | |
853 | * We require the input being a regular file, as we don't want to | |
854 | * randomly drop data for eg socket -> socket splicing. Use the | |
855 | * piped splicing for that! | |
856 | */ | |
857 | i_mode = in->f_dentry->d_inode->i_mode; | |
858 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
859 | return -EINVAL; | |
860 | ||
861 | /* | |
862 | * neither in nor out is a pipe, setup an internal pipe attached to | |
863 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
864 | */ | |
865 | pipe = current->splice_pipe; | |
49570e9b | 866 | if (unlikely(!pipe)) { |
b92ce558 JA |
867 | pipe = alloc_pipe_info(NULL); |
868 | if (!pipe) | |
869 | return -ENOMEM; | |
870 | ||
871 | /* | |
872 | * We don't have an immediate reader, but we'll read the stuff | |
873 | * out of the pipe right after the move_to_pipe(). So set | |
874 | * PIPE_READERS appropriately. | |
875 | */ | |
876 | pipe->readers = 1; | |
877 | ||
878 | current->splice_pipe = pipe; | |
879 | } | |
880 | ||
881 | /* | |
73d62d83 | 882 | * Do the splice. |
b92ce558 JA |
883 | */ |
884 | ret = 0; | |
885 | bytes = 0; | |
cbb7e577 | 886 | out_off = 0; |
b92ce558 JA |
887 | |
888 | while (len) { | |
889 | size_t read_len, max_read_len; | |
890 | ||
891 | /* | |
892 | * Do at most PIPE_BUFFERS pages worth of transfer: | |
893 | */ | |
894 | max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); | |
895 | ||
cbb7e577 | 896 | ret = do_splice_to(in, ppos, pipe, max_read_len, flags); |
b92ce558 JA |
897 | if (unlikely(ret < 0)) |
898 | goto out_release; | |
899 | ||
900 | read_len = ret; | |
901 | ||
902 | /* | |
903 | * NOTE: nonblocking mode only applies to the input. We | |
904 | * must not do the output in nonblocking mode as then we | |
905 | * could get stuck data in the internal pipe: | |
906 | */ | |
cbb7e577 | 907 | ret = do_splice_from(pipe, out, &out_off, read_len, |
b92ce558 JA |
908 | flags & ~SPLICE_F_NONBLOCK); |
909 | if (unlikely(ret < 0)) | |
910 | goto out_release; | |
911 | ||
912 | bytes += ret; | |
913 | len -= ret; | |
914 | ||
915 | /* | |
916 | * In nonblocking mode, if we got back a short read then | |
917 | * that was due to either an IO error or due to the | |
918 | * pagecache entry not being there. In the IO error case | |
919 | * the _next_ splice attempt will produce a clean IO error | |
920 | * return value (not a short read), so in both cases it's | |
921 | * correct to break out of the loop here: | |
922 | */ | |
923 | if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) | |
924 | break; | |
925 | } | |
926 | ||
927 | pipe->nrbufs = pipe->curbuf = 0; | |
928 | ||
929 | return bytes; | |
930 | ||
931 | out_release: | |
932 | /* | |
933 | * If we did an incomplete transfer we must release | |
934 | * the pipe buffers in question: | |
935 | */ | |
936 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
937 | struct pipe_buffer *buf = pipe->bufs + i; | |
938 | ||
939 | if (buf->ops) { | |
940 | buf->ops->release(pipe, buf); | |
941 | buf->ops = NULL; | |
942 | } | |
943 | } | |
944 | pipe->nrbufs = pipe->curbuf = 0; | |
945 | ||
946 | /* | |
947 | * If we transferred some data, return the number of bytes: | |
948 | */ | |
949 | if (bytes > 0) | |
950 | return bytes; | |
951 | ||
952 | return ret; | |
953 | } | |
954 | ||
955 | EXPORT_SYMBOL(do_splice_direct); | |
956 | ||
83f9135b JA |
957 | /* |
958 | * Determine where to splice to/from. | |
959 | */ | |
529565dc IM |
960 | static long do_splice(struct file *in, loff_t __user *off_in, |
961 | struct file *out, loff_t __user *off_out, | |
962 | size_t len, unsigned int flags) | |
5274f052 | 963 | { |
3a326a2c | 964 | struct pipe_inode_info *pipe; |
cbb7e577 | 965 | loff_t offset, *off; |
a4514ebd | 966 | long ret; |
5274f052 | 967 | |
3a326a2c | 968 | pipe = in->f_dentry->d_inode->i_pipe; |
529565dc IM |
969 | if (pipe) { |
970 | if (off_in) | |
971 | return -ESPIPE; | |
b92ce558 JA |
972 | if (off_out) { |
973 | if (out->f_op->llseek == no_llseek) | |
974 | return -EINVAL; | |
cbb7e577 | 975 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 976 | return -EFAULT; |
cbb7e577 JA |
977 | off = &offset; |
978 | } else | |
979 | off = &out->f_pos; | |
529565dc | 980 | |
a4514ebd JA |
981 | ret = do_splice_from(pipe, out, off, len, flags); |
982 | ||
983 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
984 | ret = -EFAULT; | |
985 | ||
986 | return ret; | |
529565dc | 987 | } |
5274f052 | 988 | |
3a326a2c | 989 | pipe = out->f_dentry->d_inode->i_pipe; |
529565dc IM |
990 | if (pipe) { |
991 | if (off_out) | |
992 | return -ESPIPE; | |
b92ce558 JA |
993 | if (off_in) { |
994 | if (in->f_op->llseek == no_llseek) | |
995 | return -EINVAL; | |
cbb7e577 | 996 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 997 | return -EFAULT; |
cbb7e577 JA |
998 | off = &offset; |
999 | } else | |
1000 | off = &in->f_pos; | |
529565dc | 1001 | |
a4514ebd JA |
1002 | ret = do_splice_to(in, off, pipe, len, flags); |
1003 | ||
1004 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
1005 | ret = -EFAULT; | |
1006 | ||
1007 | return ret; | |
529565dc | 1008 | } |
5274f052 JA |
1009 | |
1010 | return -EINVAL; | |
1011 | } | |
1012 | ||
529565dc IM |
1013 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
1014 | int fd_out, loff_t __user *off_out, | |
1015 | size_t len, unsigned int flags) | |
5274f052 JA |
1016 | { |
1017 | long error; | |
1018 | struct file *in, *out; | |
1019 | int fput_in, fput_out; | |
1020 | ||
1021 | if (unlikely(!len)) | |
1022 | return 0; | |
1023 | ||
1024 | error = -EBADF; | |
529565dc | 1025 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
1026 | if (in) { |
1027 | if (in->f_mode & FMODE_READ) { | |
529565dc | 1028 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
1029 | if (out) { |
1030 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
1031 | error = do_splice(in, off_in, |
1032 | out, off_out, | |
1033 | len, flags); | |
5274f052 JA |
1034 | fput_light(out, fput_out); |
1035 | } | |
1036 | } | |
1037 | ||
1038 | fput_light(in, fput_in); | |
1039 | } | |
1040 | ||
1041 | return error; | |
1042 | } | |
70524490 JA |
1043 | |
1044 | /* | |
1045 | * Link contents of ipipe to opipe. | |
1046 | */ | |
1047 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1048 | struct pipe_inode_info *opipe, | |
1049 | size_t len, unsigned int flags) | |
1050 | { | |
1051 | struct pipe_buffer *ibuf, *obuf; | |
2a27250e JA |
1052 | int ret, do_wakeup, i, ipipe_first; |
1053 | ||
1054 | ret = do_wakeup = ipipe_first = 0; | |
70524490 JA |
1055 | |
1056 | /* | |
1057 | * Potential ABBA deadlock, work around it by ordering lock | |
1058 | * grabbing by inode address. Otherwise two different processes | |
1059 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1060 | */ | |
1061 | if (ipipe->inode < opipe->inode) { | |
2a27250e | 1062 | ipipe_first = 1; |
70524490 JA |
1063 | mutex_lock(&ipipe->inode->i_mutex); |
1064 | mutex_lock(&opipe->inode->i_mutex); | |
1065 | } else { | |
1066 | mutex_lock(&opipe->inode->i_mutex); | |
1067 | mutex_lock(&ipipe->inode->i_mutex); | |
1068 | } | |
1069 | ||
1070 | for (i = 0;; i++) { | |
1071 | if (!opipe->readers) { | |
1072 | send_sig(SIGPIPE, current, 0); | |
1073 | if (!ret) | |
1074 | ret = -EPIPE; | |
1075 | break; | |
1076 | } | |
1077 | if (ipipe->nrbufs - i) { | |
1078 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); | |
1079 | ||
1080 | /* | |
1081 | * If we have room, fill this buffer | |
1082 | */ | |
1083 | if (opipe->nrbufs < PIPE_BUFFERS) { | |
1084 | int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); | |
1085 | ||
1086 | /* | |
1087 | * Get a reference to this pipe buffer, | |
1088 | * so we can copy the contents over. | |
1089 | */ | |
1090 | ibuf->ops->get(ipipe, ibuf); | |
1091 | ||
1092 | obuf = opipe->bufs + nbuf; | |
1093 | *obuf = *ibuf; | |
1094 | ||
1095 | if (obuf->len > len) | |
1096 | obuf->len = len; | |
1097 | ||
1098 | opipe->nrbufs++; | |
1099 | do_wakeup = 1; | |
1100 | ret += obuf->len; | |
1101 | len -= obuf->len; | |
1102 | ||
1103 | if (!len) | |
1104 | break; | |
1105 | if (opipe->nrbufs < PIPE_BUFFERS) | |
1106 | continue; | |
1107 | } | |
1108 | ||
1109 | /* | |
1110 | * We have input available, but no output room. | |
2a27250e JA |
1111 | * If we already copied data, return that. If we |
1112 | * need to drop the opipe lock, it must be ordered | |
1113 | * last to avoid deadlocks. | |
70524490 | 1114 | */ |
2a27250e | 1115 | if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) { |
70524490 JA |
1116 | if (!ret) |
1117 | ret = -EAGAIN; | |
1118 | break; | |
1119 | } | |
1120 | if (signal_pending(current)) { | |
1121 | if (!ret) | |
1122 | ret = -ERESTARTSYS; | |
1123 | break; | |
1124 | } | |
1125 | if (do_wakeup) { | |
1126 | smp_mb(); | |
1127 | if (waitqueue_active(&opipe->wait)) | |
1128 | wake_up_interruptible(&opipe->wait); | |
1129 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1130 | do_wakeup = 0; | |
1131 | } | |
1132 | ||
1133 | opipe->waiting_writers++; | |
1134 | pipe_wait(opipe); | |
1135 | opipe->waiting_writers--; | |
1136 | continue; | |
1137 | } | |
1138 | ||
1139 | /* | |
1140 | * No input buffers, do the usual checks for available | |
1141 | * writers and blocking and wait if necessary | |
1142 | */ | |
1143 | if (!ipipe->writers) | |
1144 | break; | |
1145 | if (!ipipe->waiting_writers) { | |
1146 | if (ret) | |
1147 | break; | |
1148 | } | |
2a27250e JA |
1149 | /* |
1150 | * pipe_wait() drops the ipipe mutex. To avoid deadlocks | |
1151 | * with another process, we can only safely do that if | |
1152 | * the ipipe lock is ordered last. | |
1153 | */ | |
1154 | if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) { | |
70524490 JA |
1155 | if (!ret) |
1156 | ret = -EAGAIN; | |
1157 | break; | |
1158 | } | |
1159 | if (signal_pending(current)) { | |
1160 | if (!ret) | |
1161 | ret = -ERESTARTSYS; | |
1162 | break; | |
1163 | } | |
1164 | ||
1165 | if (waitqueue_active(&ipipe->wait)) | |
1166 | wake_up_interruptible_sync(&ipipe->wait); | |
1167 | kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT); | |
1168 | ||
1169 | pipe_wait(ipipe); | |
1170 | } | |
1171 | ||
1172 | mutex_unlock(&ipipe->inode->i_mutex); | |
1173 | mutex_unlock(&opipe->inode->i_mutex); | |
1174 | ||
1175 | if (do_wakeup) { | |
1176 | smp_mb(); | |
1177 | if (waitqueue_active(&opipe->wait)) | |
1178 | wake_up_interruptible(&opipe->wait); | |
1179 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1180 | } | |
1181 | ||
1182 | return ret; | |
1183 | } | |
1184 | ||
1185 | /* | |
1186 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1187 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1188 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1189 | * applicable one is SPLICE_F_NONBLOCK. | |
1190 | */ | |
1191 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1192 | unsigned int flags) | |
1193 | { | |
1194 | struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe; | |
1195 | struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe; | |
1196 | ||
1197 | /* | |
1198 | * Link ipipe to the two output pipes, consuming as we go along. | |
1199 | */ | |
1200 | if (ipipe && opipe) | |
1201 | return link_pipe(ipipe, opipe, len, flags); | |
1202 | ||
1203 | return -EINVAL; | |
1204 | } | |
1205 | ||
1206 | asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) | |
1207 | { | |
1208 | struct file *in; | |
1209 | int error, fput_in; | |
1210 | ||
1211 | if (unlikely(!len)) | |
1212 | return 0; | |
1213 | ||
1214 | error = -EBADF; | |
1215 | in = fget_light(fdin, &fput_in); | |
1216 | if (in) { | |
1217 | if (in->f_mode & FMODE_READ) { | |
1218 | int fput_out; | |
1219 | struct file *out = fget_light(fdout, &fput_out); | |
1220 | ||
1221 | if (out) { | |
1222 | if (out->f_mode & FMODE_WRITE) | |
1223 | error = do_tee(in, out, len, flags); | |
1224 | fput_light(out, fput_out); | |
1225 | } | |
1226 | } | |
1227 | fput_light(in, fput_in); | |
1228 | } | |
1229 | ||
1230 | return error; | |
1231 | } |