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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 | |
c2058e06 JA |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. | |
5274f052 | 14 | * |
0fe23479 | 15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
c2058e06 JA |
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> | |
d6b29d7c | 23 | #include <linux/splice.h> |
5274f052 | 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> |
912d35f8 | 30 | #include <linux/uio.h> |
5274f052 | 31 | |
83f9135b JA |
32 | /* |
33 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
34 | * a vm helper function, it's already simplified quite a bit by the | |
35 | * addition of remove_mapping(). If success is returned, the caller may | |
36 | * attempt to reuse this page for another destination. | |
37 | */ | |
76ad4d11 | 38 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
5abc97aa JA |
39 | struct pipe_buffer *buf) |
40 | { | |
41 | struct page *page = buf->page; | |
9e94cd4f | 42 | struct address_space *mapping; |
5abc97aa | 43 | |
9e0267c2 JA |
44 | lock_page(page); |
45 | ||
9e94cd4f JA |
46 | mapping = page_mapping(page); |
47 | if (mapping) { | |
48 | WARN_ON(!PageUptodate(page)); | |
5abc97aa | 49 | |
9e94cd4f JA |
50 | /* |
51 | * At least for ext2 with nobh option, we need to wait on | |
52 | * writeback completing on this page, since we'll remove it | |
53 | * from the pagecache. Otherwise truncate wont wait on the | |
54 | * page, allowing the disk blocks to be reused by someone else | |
55 | * before we actually wrote our data to them. fs corruption | |
56 | * ensues. | |
57 | */ | |
58 | wait_on_page_writeback(page); | |
ad8d6f0a | 59 | |
9e94cd4f | 60 | if (PagePrivate(page)) |
2ae88149 | 61 | try_to_release_page(page, GFP_KERNEL); |
4f6f0bd2 | 62 | |
9e94cd4f JA |
63 | /* |
64 | * If we succeeded in removing the mapping, set LRU flag | |
65 | * and return good. | |
66 | */ | |
67 | if (remove_mapping(mapping, page)) { | |
68 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
69 | return 0; | |
70 | } | |
9e0267c2 | 71 | } |
5abc97aa | 72 | |
9e94cd4f JA |
73 | /* |
74 | * Raced with truncate or failed to remove page from current | |
75 | * address space, unlock and return failure. | |
76 | */ | |
77 | unlock_page(page); | |
78 | return 1; | |
5abc97aa JA |
79 | } |
80 | ||
76ad4d11 | 81 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
5274f052 JA |
82 | struct pipe_buffer *buf) |
83 | { | |
84 | page_cache_release(buf->page); | |
1432873a | 85 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
86 | } |
87 | ||
0845718d JA |
88 | /* |
89 | * Check whether the contents of buf is OK to access. Since the content | |
90 | * is a page cache page, IO may be in flight. | |
91 | */ | |
cac36bb0 JA |
92 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
93 | struct pipe_buffer *buf) | |
5274f052 JA |
94 | { |
95 | struct page *page = buf->page; | |
49d0b21b | 96 | int err; |
5274f052 JA |
97 | |
98 | if (!PageUptodate(page)) { | |
49d0b21b JA |
99 | lock_page(page); |
100 | ||
101 | /* | |
102 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 103 | * splice, if this is the first page. |
49d0b21b JA |
104 | */ |
105 | if (!page->mapping) { | |
106 | err = -ENODATA; | |
107 | goto error; | |
108 | } | |
5274f052 | 109 | |
49d0b21b | 110 | /* |
73d62d83 | 111 | * Uh oh, read-error from disk. |
49d0b21b JA |
112 | */ |
113 | if (!PageUptodate(page)) { | |
114 | err = -EIO; | |
115 | goto error; | |
116 | } | |
117 | ||
118 | /* | |
f84d7519 | 119 | * Page is ok afterall, we are done. |
49d0b21b | 120 | */ |
5274f052 | 121 | unlock_page(page); |
5274f052 JA |
122 | } |
123 | ||
f84d7519 | 124 | return 0; |
49d0b21b JA |
125 | error: |
126 | unlock_page(page); | |
f84d7519 | 127 | return err; |
70524490 JA |
128 | } |
129 | ||
d4c3cca9 | 130 | static const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
5274f052 | 131 | .can_merge = 0, |
f84d7519 JA |
132 | .map = generic_pipe_buf_map, |
133 | .unmap = generic_pipe_buf_unmap, | |
cac36bb0 | 134 | .confirm = page_cache_pipe_buf_confirm, |
5274f052 | 135 | .release = page_cache_pipe_buf_release, |
5abc97aa | 136 | .steal = page_cache_pipe_buf_steal, |
f84d7519 | 137 | .get = generic_pipe_buf_get, |
5274f052 JA |
138 | }; |
139 | ||
912d35f8 JA |
140 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
141 | struct pipe_buffer *buf) | |
142 | { | |
7afa6fd0 JA |
143 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
144 | return 1; | |
145 | ||
1432873a | 146 | buf->flags |= PIPE_BUF_FLAG_LRU; |
330ab716 | 147 | return generic_pipe_buf_steal(pipe, buf); |
912d35f8 JA |
148 | } |
149 | ||
d4c3cca9 | 150 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
912d35f8 | 151 | .can_merge = 0, |
f84d7519 JA |
152 | .map = generic_pipe_buf_map, |
153 | .unmap = generic_pipe_buf_unmap, | |
cac36bb0 | 154 | .confirm = generic_pipe_buf_confirm, |
912d35f8 JA |
155 | .release = page_cache_pipe_buf_release, |
156 | .steal = user_page_pipe_buf_steal, | |
f84d7519 | 157 | .get = generic_pipe_buf_get, |
912d35f8 JA |
158 | }; |
159 | ||
932cc6d4 JA |
160 | /** |
161 | * splice_to_pipe - fill passed data into a pipe | |
162 | * @pipe: pipe to fill | |
163 | * @spd: data to fill | |
164 | * | |
165 | * Description: | |
166 | * @spd contains a map of pages and len/offset tupples, a long with | |
167 | * the struct pipe_buf_operations associated with these pages. This | |
168 | * function will link that data to the pipe. | |
169 | * | |
83f9135b | 170 | */ |
d6b29d7c JA |
171 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
172 | struct splice_pipe_desc *spd) | |
5274f052 | 173 | { |
00de00bd | 174 | unsigned int spd_pages = spd->nr_pages; |
912d35f8 | 175 | int ret, do_wakeup, page_nr; |
5274f052 JA |
176 | |
177 | ret = 0; | |
178 | do_wakeup = 0; | |
912d35f8 | 179 | page_nr = 0; |
5274f052 | 180 | |
3a326a2c IM |
181 | if (pipe->inode) |
182 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 183 | |
5274f052 | 184 | for (;;) { |
3a326a2c | 185 | if (!pipe->readers) { |
5274f052 JA |
186 | send_sig(SIGPIPE, current, 0); |
187 | if (!ret) | |
188 | ret = -EPIPE; | |
189 | break; | |
190 | } | |
191 | ||
6f767b04 JA |
192 | if (pipe->nrbufs < PIPE_BUFFERS) { |
193 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); | |
3a326a2c | 194 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
5274f052 | 195 | |
912d35f8 JA |
196 | buf->page = spd->pages[page_nr]; |
197 | buf->offset = spd->partial[page_nr].offset; | |
198 | buf->len = spd->partial[page_nr].len; | |
497f9625 | 199 | buf->private = spd->partial[page_nr].private; |
912d35f8 | 200 | buf->ops = spd->ops; |
7afa6fd0 JA |
201 | if (spd->flags & SPLICE_F_GIFT) |
202 | buf->flags |= PIPE_BUF_FLAG_GIFT; | |
203 | ||
6f767b04 | 204 | pipe->nrbufs++; |
912d35f8 JA |
205 | page_nr++; |
206 | ret += buf->len; | |
207 | ||
6f767b04 JA |
208 | if (pipe->inode) |
209 | do_wakeup = 1; | |
5274f052 | 210 | |
912d35f8 | 211 | if (!--spd->nr_pages) |
5274f052 | 212 | break; |
6f767b04 | 213 | if (pipe->nrbufs < PIPE_BUFFERS) |
5274f052 JA |
214 | continue; |
215 | ||
216 | break; | |
217 | } | |
218 | ||
912d35f8 | 219 | if (spd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
220 | if (!ret) |
221 | ret = -EAGAIN; | |
222 | break; | |
223 | } | |
224 | ||
5274f052 JA |
225 | if (signal_pending(current)) { |
226 | if (!ret) | |
227 | ret = -ERESTARTSYS; | |
228 | break; | |
229 | } | |
230 | ||
231 | if (do_wakeup) { | |
c0bd1f65 | 232 | smp_mb(); |
3a326a2c IM |
233 | if (waitqueue_active(&pipe->wait)) |
234 | wake_up_interruptible_sync(&pipe->wait); | |
235 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
236 | do_wakeup = 0; |
237 | } | |
238 | ||
3a326a2c IM |
239 | pipe->waiting_writers++; |
240 | pipe_wait(pipe); | |
241 | pipe->waiting_writers--; | |
5274f052 JA |
242 | } |
243 | ||
02676e5a | 244 | if (pipe->inode) { |
3a326a2c | 245 | mutex_unlock(&pipe->inode->i_mutex); |
5274f052 | 246 | |
02676e5a JA |
247 | if (do_wakeup) { |
248 | smp_mb(); | |
249 | if (waitqueue_active(&pipe->wait)) | |
250 | wake_up_interruptible(&pipe->wait); | |
251 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
252 | } | |
5274f052 JA |
253 | } |
254 | ||
00de00bd | 255 | while (page_nr < spd_pages) |
912d35f8 | 256 | page_cache_release(spd->pages[page_nr++]); |
5274f052 JA |
257 | |
258 | return ret; | |
259 | } | |
260 | ||
3a326a2c | 261 | static int |
cbb7e577 JA |
262 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
263 | struct pipe_inode_info *pipe, size_t len, | |
264 | unsigned int flags) | |
5274f052 JA |
265 | { |
266 | struct address_space *mapping = in->f_mapping; | |
912d35f8 | 267 | unsigned int loff, nr_pages; |
16c523dd | 268 | struct page *pages[PIPE_BUFFERS]; |
912d35f8 | 269 | struct partial_page partial[PIPE_BUFFERS]; |
5274f052 | 270 | struct page *page; |
91ad66ef JA |
271 | pgoff_t index, end_index; |
272 | loff_t isize; | |
eb20796b | 273 | int error, page_nr; |
912d35f8 JA |
274 | struct splice_pipe_desc spd = { |
275 | .pages = pages, | |
276 | .partial = partial, | |
277 | .flags = flags, | |
278 | .ops = &page_cache_pipe_buf_ops, | |
279 | }; | |
5274f052 | 280 | |
cbb7e577 | 281 | index = *ppos >> PAGE_CACHE_SHIFT; |
912d35f8 JA |
282 | loff = *ppos & ~PAGE_CACHE_MASK; |
283 | nr_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
5274f052 JA |
284 | |
285 | if (nr_pages > PIPE_BUFFERS) | |
286 | nr_pages = PIPE_BUFFERS; | |
287 | ||
288 | /* | |
86aa5ac5 JA |
289 | * Don't try to 2nd guess the read-ahead logic, call into |
290 | * page_cache_readahead() like the page cache reads would do. | |
5274f052 | 291 | */ |
86aa5ac5 | 292 | page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages); |
5274f052 | 293 | |
eb20796b JA |
294 | /* |
295 | * Lookup the (hopefully) full range of pages we need. | |
296 | */ | |
297 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); | |
82aa5d61 | 298 | |
eb20796b JA |
299 | /* |
300 | * If find_get_pages_contig() returned fewer pages than we needed, | |
932cc6d4 | 301 | * allocate the rest and fill in the holes. |
eb20796b | 302 | */ |
932cc6d4 | 303 | error = 0; |
eb20796b JA |
304 | index += spd.nr_pages; |
305 | while (spd.nr_pages < nr_pages) { | |
82aa5d61 | 306 | /* |
eb20796b JA |
307 | * Page could be there, find_get_pages_contig() breaks on |
308 | * the first hole. | |
5274f052 | 309 | */ |
7480a904 JA |
310 | page = find_get_page(mapping, index); |
311 | if (!page) { | |
e27dedd8 JA |
312 | /* |
313 | * Make sure the read-ahead engine is notified | |
314 | * about this failure. | |
315 | */ | |
316 | handle_ra_miss(mapping, &in->f_ra, index); | |
317 | ||
7480a904 | 318 | /* |
eb20796b | 319 | * page didn't exist, allocate one. |
7480a904 JA |
320 | */ |
321 | page = page_cache_alloc_cold(mapping); | |
322 | if (!page) | |
323 | break; | |
324 | ||
325 | error = add_to_page_cache_lru(page, mapping, index, | |
2ae88149 | 326 | GFP_KERNEL); |
7480a904 JA |
327 | if (unlikely(error)) { |
328 | page_cache_release(page); | |
a0548871 JA |
329 | if (error == -EEXIST) |
330 | continue; | |
7480a904 JA |
331 | break; |
332 | } | |
eb20796b JA |
333 | /* |
334 | * add_to_page_cache() locks the page, unlock it | |
335 | * to avoid convoluting the logic below even more. | |
336 | */ | |
337 | unlock_page(page); | |
7480a904 JA |
338 | } |
339 | ||
eb20796b JA |
340 | pages[spd.nr_pages++] = page; |
341 | index++; | |
342 | } | |
343 | ||
344 | /* | |
345 | * Now loop over the map and see if we need to start IO on any | |
346 | * pages, fill in the partial map, etc. | |
347 | */ | |
348 | index = *ppos >> PAGE_CACHE_SHIFT; | |
349 | nr_pages = spd.nr_pages; | |
350 | spd.nr_pages = 0; | |
351 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
352 | unsigned int this_len; | |
353 | ||
354 | if (!len) | |
355 | break; | |
356 | ||
357 | /* | |
358 | * this_len is the max we'll use from this page | |
359 | */ | |
360 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
361 | page = pages[page_nr]; | |
362 | ||
7480a904 JA |
363 | /* |
364 | * If the page isn't uptodate, we may need to start io on it | |
365 | */ | |
366 | if (!PageUptodate(page)) { | |
c4f895cb JA |
367 | /* |
368 | * If in nonblock mode then dont block on waiting | |
369 | * for an in-flight io page | |
370 | */ | |
9ae9d68c FW |
371 | if (flags & SPLICE_F_NONBLOCK) { |
372 | if (TestSetPageLocked(page)) | |
373 | break; | |
374 | } else | |
375 | lock_page(page); | |
7480a904 JA |
376 | |
377 | /* | |
378 | * page was truncated, stop here. if this isn't the | |
379 | * first page, we'll just complete what we already | |
380 | * added | |
381 | */ | |
382 | if (!page->mapping) { | |
383 | unlock_page(page); | |
7480a904 JA |
384 | break; |
385 | } | |
386 | /* | |
387 | * page was already under io and is now done, great | |
388 | */ | |
389 | if (PageUptodate(page)) { | |
390 | unlock_page(page); | |
391 | goto fill_it; | |
392 | } | |
5274f052 | 393 | |
7480a904 JA |
394 | /* |
395 | * need to read in the page | |
396 | */ | |
397 | error = mapping->a_ops->readpage(in, page); | |
5274f052 | 398 | if (unlikely(error)) { |
eb20796b JA |
399 | /* |
400 | * We really should re-lookup the page here, | |
401 | * but it complicates things a lot. Instead | |
402 | * lets just do what we already stored, and | |
403 | * we'll get it the next time we are called. | |
404 | */ | |
7480a904 | 405 | if (error == AOP_TRUNCATED_PAGE) |
eb20796b JA |
406 | error = 0; |
407 | ||
5274f052 JA |
408 | break; |
409 | } | |
620a324b JA |
410 | } |
411 | fill_it: | |
412 | /* | |
413 | * i_size must be checked after PageUptodate. | |
414 | */ | |
415 | isize = i_size_read(mapping->host); | |
416 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
417 | if (unlikely(!isize || index > end_index)) | |
418 | break; | |
419 | ||
420 | /* | |
421 | * if this is the last page, see if we need to shrink | |
422 | * the length and stop | |
423 | */ | |
424 | if (end_index == index) { | |
425 | unsigned int plen; | |
91ad66ef JA |
426 | |
427 | /* | |
620a324b | 428 | * max good bytes in this page |
91ad66ef | 429 | */ |
620a324b JA |
430 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
431 | if (plen <= loff) | |
91ad66ef | 432 | break; |
91ad66ef JA |
433 | |
434 | /* | |
620a324b | 435 | * force quit after adding this page |
91ad66ef | 436 | */ |
620a324b JA |
437 | this_len = min(this_len, plen - loff); |
438 | len = this_len; | |
5274f052 | 439 | } |
620a324b | 440 | |
eb20796b JA |
441 | partial[page_nr].offset = loff; |
442 | partial[page_nr].len = this_len; | |
82aa5d61 | 443 | len -= this_len; |
91ad66ef | 444 | loff = 0; |
eb20796b JA |
445 | spd.nr_pages++; |
446 | index++; | |
5274f052 JA |
447 | } |
448 | ||
eb20796b | 449 | /* |
475ecade | 450 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
eb20796b JA |
451 | * we got, 'nr_pages' is how many pages are in the map. |
452 | */ | |
453 | while (page_nr < nr_pages) | |
454 | page_cache_release(pages[page_nr++]); | |
455 | ||
912d35f8 | 456 | if (spd.nr_pages) |
00522fb4 | 457 | return splice_to_pipe(pipe, &spd); |
5274f052 | 458 | |
7480a904 | 459 | return error; |
5274f052 JA |
460 | } |
461 | ||
83f9135b JA |
462 | /** |
463 | * generic_file_splice_read - splice data from file to a pipe | |
464 | * @in: file to splice from | |
932cc6d4 | 465 | * @ppos: position in @in |
83f9135b JA |
466 | * @pipe: pipe to splice to |
467 | * @len: number of bytes to splice | |
468 | * @flags: splice modifier flags | |
469 | * | |
932cc6d4 JA |
470 | * Description: |
471 | * Will read pages from given file and fill them into a pipe. Can be | |
472 | * used as long as the address_space operations for the source implements | |
473 | * a readpage() hook. | |
474 | * | |
83f9135b | 475 | */ |
cbb7e577 JA |
476 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
477 | struct pipe_inode_info *pipe, size_t len, | |
478 | unsigned int flags) | |
5274f052 JA |
479 | { |
480 | ssize_t spliced; | |
481 | int ret; | |
d366d398 JA |
482 | loff_t isize, left; |
483 | ||
484 | isize = i_size_read(in->f_mapping->host); | |
485 | if (unlikely(*ppos >= isize)) | |
486 | return 0; | |
487 | ||
488 | left = isize - *ppos; | |
489 | if (unlikely(left < len)) | |
490 | len = left; | |
5274f052 JA |
491 | |
492 | ret = 0; | |
493 | spliced = 0; | |
494 | while (len) { | |
cbb7e577 | 495 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
5274f052 | 496 | |
c4f895cb | 497 | if (ret < 0) |
5274f052 | 498 | break; |
c4f895cb JA |
499 | else if (!ret) { |
500 | if (spliced) | |
501 | break; | |
502 | if (flags & SPLICE_F_NONBLOCK) { | |
503 | ret = -EAGAIN; | |
504 | break; | |
505 | } | |
506 | } | |
5274f052 | 507 | |
cbb7e577 | 508 | *ppos += ret; |
5274f052 JA |
509 | len -= ret; |
510 | spliced += ret; | |
511 | } | |
512 | ||
513 | if (spliced) | |
514 | return spliced; | |
515 | ||
516 | return ret; | |
517 | } | |
518 | ||
059a8f37 JA |
519 | EXPORT_SYMBOL(generic_file_splice_read); |
520 | ||
5274f052 | 521 | /* |
4f6f0bd2 | 522 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 523 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 524 | */ |
76ad4d11 | 525 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
526 | struct pipe_buffer *buf, struct splice_desc *sd) |
527 | { | |
6a14b90b | 528 | struct file *file = sd->u.file; |
5274f052 | 529 | loff_t pos = sd->pos; |
f84d7519 | 530 | int ret, more; |
5274f052 | 531 | |
cac36bb0 | 532 | ret = buf->ops->confirm(pipe, buf); |
f84d7519 JA |
533 | if (!ret) { |
534 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; | |
5274f052 | 535 | |
f84d7519 JA |
536 | ret = file->f_op->sendpage(file, buf->page, buf->offset, |
537 | sd->len, &pos, more); | |
538 | } | |
5274f052 | 539 | |
016b661e | 540 | return ret; |
5274f052 JA |
541 | } |
542 | ||
543 | /* | |
544 | * This is a little more tricky than the file -> pipe splicing. There are | |
545 | * basically three cases: | |
546 | * | |
547 | * - Destination page already exists in the address space and there | |
548 | * are users of it. For that case we have no other option that | |
549 | * copying the data. Tough luck. | |
550 | * - Destination page already exists in the address space, but there | |
551 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
552 | * through to last case. | |
553 | * - Destination page does not exist, we can add the pipe page to | |
554 | * the page cache and avoid the copy. | |
555 | * | |
83f9135b JA |
556 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
557 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
558 | * file address space page cache. This is possible if no one else has | |
559 | * the pipe page referenced outside of the pipe and page cache. If | |
560 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
561 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 | 562 | */ |
76ad4d11 | 563 | static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
5274f052 JA |
564 | struct splice_desc *sd) |
565 | { | |
6a14b90b | 566 | struct file *file = sd->u.file; |
5274f052 | 567 | struct address_space *mapping = file->f_mapping; |
016b661e | 568 | unsigned int offset, this_len; |
5274f052 | 569 | struct page *page; |
5274f052 | 570 | pgoff_t index; |
3e7ee3e7 | 571 | int ret; |
5274f052 JA |
572 | |
573 | /* | |
49d0b21b | 574 | * make sure the data in this buffer is uptodate |
5274f052 | 575 | */ |
cac36bb0 | 576 | ret = buf->ops->confirm(pipe, buf); |
f84d7519 JA |
577 | if (unlikely(ret)) |
578 | return ret; | |
5274f052 JA |
579 | |
580 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
581 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
582 | ||
016b661e JA |
583 | this_len = sd->len; |
584 | if (this_len + offset > PAGE_CACHE_SIZE) | |
585 | this_len = PAGE_CACHE_SIZE - offset; | |
586 | ||
485ddb4b NP |
587 | find_page: |
588 | page = find_lock_page(mapping, index); | |
589 | if (!page) { | |
590 | ret = -ENOMEM; | |
591 | page = page_cache_alloc_cold(mapping); | |
592 | if (unlikely(!page)) | |
593 | goto out_ret; | |
594 | ||
83f9135b | 595 | /* |
485ddb4b | 596 | * This will also lock the page |
83f9135b | 597 | */ |
485ddb4b NP |
598 | ret = add_to_page_cache_lru(page, mapping, index, |
599 | GFP_KERNEL); | |
600 | if (unlikely(ret)) | |
601 | goto out; | |
602 | } | |
9e0267c2 | 603 | |
016b661e | 604 | ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len); |
bfc4ee39 JA |
605 | if (unlikely(ret)) { |
606 | loff_t isize = i_size_read(mapping->host); | |
607 | ||
608 | if (ret != AOP_TRUNCATED_PAGE) | |
609 | unlock_page(page); | |
4f6f0bd2 | 610 | page_cache_release(page); |
bfc4ee39 JA |
611 | if (ret == AOP_TRUNCATED_PAGE) |
612 | goto find_page; | |
613 | ||
614 | /* | |
615 | * prepare_write() may have instantiated a few blocks | |
616 | * outside i_size. Trim these off again. | |
617 | */ | |
618 | if (sd->pos + this_len > isize) | |
619 | vmtruncate(mapping->host, isize); | |
620 | ||
e6e80f29 | 621 | goto out_ret; |
bfc4ee39 | 622 | } |
5274f052 | 623 | |
0568b409 | 624 | if (buf->page != page) { |
f84d7519 JA |
625 | /* |
626 | * Careful, ->map() uses KM_USER0! | |
627 | */ | |
76ad4d11 | 628 | char *src = buf->ops->map(pipe, buf, 1); |
f84d7519 | 629 | char *dst = kmap_atomic(page, KM_USER1); |
5abc97aa | 630 | |
016b661e | 631 | memcpy(dst + offset, src + buf->offset, this_len); |
5abc97aa | 632 | flush_dcache_page(page); |
f84d7519 | 633 | kunmap_atomic(dst, KM_USER1); |
76ad4d11 | 634 | buf->ops->unmap(pipe, buf, src); |
5abc97aa | 635 | } |
5274f052 | 636 | |
016b661e | 637 | ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len); |
d9993c37 DM |
638 | if (ret) { |
639 | if (ret == AOP_TRUNCATED_PAGE) { | |
640 | page_cache_release(page); | |
641 | goto find_page; | |
642 | } | |
643 | if (ret < 0) | |
644 | goto out; | |
0568b409 | 645 | /* |
d9993c37 DM |
646 | * Partial write has happened, so 'ret' already initialized by |
647 | * number of bytes written, Where is nothing we have to do here. | |
0568b409 | 648 | */ |
d9993c37 | 649 | } else |
0568b409 | 650 | ret = this_len; |
d9993c37 DM |
651 | /* |
652 | * Return the number of bytes written and mark page as | |
653 | * accessed, we are now done! | |
654 | */ | |
655 | mark_page_accessed(page); | |
5274f052 | 656 | out: |
0568b409 | 657 | page_cache_release(page); |
9e0267c2 | 658 | unlock_page(page); |
e6e80f29 | 659 | out_ret: |
5274f052 JA |
660 | return ret; |
661 | } | |
662 | ||
932cc6d4 JA |
663 | /** |
664 | * __splice_from_pipe - splice data from a pipe to given actor | |
665 | * @pipe: pipe to splice from | |
666 | * @sd: information to @actor | |
667 | * @actor: handler that splices the data | |
668 | * | |
669 | * Description: | |
670 | * This function does little more than loop over the pipe and call | |
671 | * @actor to do the actual moving of a single struct pipe_buffer to | |
672 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
673 | * pipe_to_user. | |
674 | * | |
83f9135b | 675 | */ |
c66ab6fa JA |
676 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
677 | splice_actor *actor) | |
5274f052 | 678 | { |
5274f052 | 679 | int ret, do_wakeup, err; |
5274f052 JA |
680 | |
681 | ret = 0; | |
682 | do_wakeup = 0; | |
683 | ||
5274f052 | 684 | for (;;) { |
6f767b04 JA |
685 | if (pipe->nrbufs) { |
686 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
d4c3cca9 | 687 | const struct pipe_buf_operations *ops = buf->ops; |
5274f052 | 688 | |
c66ab6fa JA |
689 | sd->len = buf->len; |
690 | if (sd->len > sd->total_len) | |
691 | sd->len = sd->total_len; | |
5274f052 | 692 | |
c66ab6fa | 693 | err = actor(pipe, buf, sd); |
016b661e | 694 | if (err <= 0) { |
5274f052 JA |
695 | if (!ret && err != -ENODATA) |
696 | ret = err; | |
697 | ||
698 | break; | |
699 | } | |
700 | ||
016b661e JA |
701 | ret += err; |
702 | buf->offset += err; | |
703 | buf->len -= err; | |
704 | ||
c66ab6fa JA |
705 | sd->len -= err; |
706 | sd->pos += err; | |
707 | sd->total_len -= err; | |
708 | if (sd->len) | |
016b661e | 709 | continue; |
73d62d83 | 710 | |
5274f052 JA |
711 | if (!buf->len) { |
712 | buf->ops = NULL; | |
3a326a2c | 713 | ops->release(pipe, buf); |
6f767b04 JA |
714 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
715 | pipe->nrbufs--; | |
716 | if (pipe->inode) | |
717 | do_wakeup = 1; | |
5274f052 JA |
718 | } |
719 | ||
c66ab6fa | 720 | if (!sd->total_len) |
5274f052 JA |
721 | break; |
722 | } | |
723 | ||
6f767b04 | 724 | if (pipe->nrbufs) |
5274f052 | 725 | continue; |
3a326a2c | 726 | if (!pipe->writers) |
5274f052 | 727 | break; |
3a326a2c | 728 | if (!pipe->waiting_writers) { |
5274f052 JA |
729 | if (ret) |
730 | break; | |
731 | } | |
732 | ||
c66ab6fa | 733 | if (sd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
734 | if (!ret) |
735 | ret = -EAGAIN; | |
736 | break; | |
737 | } | |
738 | ||
5274f052 JA |
739 | if (signal_pending(current)) { |
740 | if (!ret) | |
741 | ret = -ERESTARTSYS; | |
742 | break; | |
743 | } | |
744 | ||
745 | if (do_wakeup) { | |
c0bd1f65 | 746 | smp_mb(); |
3a326a2c IM |
747 | if (waitqueue_active(&pipe->wait)) |
748 | wake_up_interruptible_sync(&pipe->wait); | |
749 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
750 | do_wakeup = 0; |
751 | } | |
752 | ||
3a326a2c | 753 | pipe_wait(pipe); |
5274f052 JA |
754 | } |
755 | ||
5274f052 | 756 | if (do_wakeup) { |
c0bd1f65 | 757 | smp_mb(); |
3a326a2c IM |
758 | if (waitqueue_active(&pipe->wait)) |
759 | wake_up_interruptible(&pipe->wait); | |
760 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
761 | } |
762 | ||
5274f052 | 763 | return ret; |
5274f052 | 764 | } |
40bee44e | 765 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 766 | |
932cc6d4 JA |
767 | /** |
768 | * splice_from_pipe - splice data from a pipe to a file | |
769 | * @pipe: pipe to splice from | |
770 | * @out: file to splice to | |
771 | * @ppos: position in @out | |
772 | * @len: how many bytes to splice | |
773 | * @flags: splice modifier flags | |
774 | * @actor: handler that splices the data | |
775 | * | |
776 | * Description: | |
777 | * See __splice_from_pipe. This function locks the input and output inodes, | |
778 | * otherwise it's identical to __splice_from_pipe(). | |
779 | * | |
780 | */ | |
6da61809 MF |
781 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
782 | loff_t *ppos, size_t len, unsigned int flags, | |
783 | splice_actor *actor) | |
784 | { | |
785 | ssize_t ret; | |
786 | struct inode *inode = out->f_mapping->host; | |
c66ab6fa JA |
787 | struct splice_desc sd = { |
788 | .total_len = len, | |
789 | .flags = flags, | |
790 | .pos = *ppos, | |
6a14b90b | 791 | .u.file = out, |
c66ab6fa | 792 | }; |
6da61809 MF |
793 | |
794 | /* | |
795 | * The actor worker might be calling ->prepare_write and | |
796 | * ->commit_write. Most of the time, these expect i_mutex to | |
797 | * be held. Since this may result in an ABBA deadlock with | |
798 | * pipe->inode, we have to order lock acquiry here. | |
799 | */ | |
800 | inode_double_lock(inode, pipe->inode); | |
c66ab6fa | 801 | ret = __splice_from_pipe(pipe, &sd, actor); |
6da61809 MF |
802 | inode_double_unlock(inode, pipe->inode); |
803 | ||
804 | return ret; | |
805 | } | |
806 | ||
807 | /** | |
808 | * generic_file_splice_write_nolock - generic_file_splice_write without mutexes | |
809 | * @pipe: pipe info | |
810 | * @out: file to write to | |
932cc6d4 | 811 | * @ppos: position in @out |
6da61809 MF |
812 | * @len: number of bytes to splice |
813 | * @flags: splice modifier flags | |
814 | * | |
932cc6d4 JA |
815 | * Description: |
816 | * Will either move or copy pages (determined by @flags options) from | |
817 | * the given pipe inode to the given file. The caller is responsible | |
818 | * for acquiring i_mutex on both inodes. | |
6da61809 MF |
819 | * |
820 | */ | |
821 | ssize_t | |
822 | generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out, | |
823 | loff_t *ppos, size_t len, unsigned int flags) | |
824 | { | |
825 | struct address_space *mapping = out->f_mapping; | |
826 | struct inode *inode = mapping->host; | |
c66ab6fa JA |
827 | struct splice_desc sd = { |
828 | .total_len = len, | |
829 | .flags = flags, | |
830 | .pos = *ppos, | |
6a14b90b | 831 | .u.file = out, |
c66ab6fa | 832 | }; |
6da61809 MF |
833 | ssize_t ret; |
834 | int err; | |
835 | ||
0f7fc9e4 | 836 | err = remove_suid(out->f_path.dentry); |
8c34e2d6 JA |
837 | if (unlikely(err)) |
838 | return err; | |
839 | ||
c66ab6fa | 840 | ret = __splice_from_pipe(pipe, &sd, pipe_to_file); |
6da61809 | 841 | if (ret > 0) { |
17ee4f49 JA |
842 | unsigned long nr_pages; |
843 | ||
6da61809 | 844 | *ppos += ret; |
17ee4f49 | 845 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
6da61809 MF |
846 | |
847 | /* | |
848 | * If file or inode is SYNC and we actually wrote some data, | |
849 | * sync it. | |
850 | */ | |
851 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
852 | err = generic_osync_inode(inode, mapping, | |
853 | OSYNC_METADATA|OSYNC_DATA); | |
854 | ||
855 | if (err) | |
856 | ret = err; | |
857 | } | |
17ee4f49 | 858 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
6da61809 MF |
859 | } |
860 | ||
861 | return ret; | |
862 | } | |
863 | ||
864 | EXPORT_SYMBOL(generic_file_splice_write_nolock); | |
865 | ||
83f9135b JA |
866 | /** |
867 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 868 | * @pipe: pipe info |
83f9135b | 869 | * @out: file to write to |
932cc6d4 | 870 | * @ppos: position in @out |
83f9135b JA |
871 | * @len: number of bytes to splice |
872 | * @flags: splice modifier flags | |
873 | * | |
932cc6d4 JA |
874 | * Description: |
875 | * Will either move or copy pages (determined by @flags options) from | |
876 | * the given pipe inode to the given file. | |
83f9135b JA |
877 | * |
878 | */ | |
3a326a2c IM |
879 | ssize_t |
880 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
cbb7e577 | 881 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 882 | { |
4f6f0bd2 | 883 | struct address_space *mapping = out->f_mapping; |
8c34e2d6 | 884 | struct inode *inode = mapping->host; |
3a326a2c | 885 | ssize_t ret; |
8c34e2d6 JA |
886 | int err; |
887 | ||
0f7fc9e4 | 888 | err = should_remove_suid(out->f_path.dentry); |
8c34e2d6 JA |
889 | if (unlikely(err)) { |
890 | mutex_lock(&inode->i_mutex); | |
0f7fc9e4 | 891 | err = __remove_suid(out->f_path.dentry, err); |
8c34e2d6 JA |
892 | mutex_unlock(&inode->i_mutex); |
893 | if (err) | |
894 | return err; | |
895 | } | |
3a326a2c | 896 | |
00522fb4 | 897 | ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file); |
a4514ebd | 898 | if (ret > 0) { |
17ee4f49 JA |
899 | unsigned long nr_pages; |
900 | ||
a4514ebd | 901 | *ppos += ret; |
17ee4f49 | 902 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
a4514ebd JA |
903 | |
904 | /* | |
905 | * If file or inode is SYNC and we actually wrote some data, | |
906 | * sync it. | |
907 | */ | |
908 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
a4514ebd JA |
909 | mutex_lock(&inode->i_mutex); |
910 | err = generic_osync_inode(inode, mapping, | |
911 | OSYNC_METADATA|OSYNC_DATA); | |
912 | mutex_unlock(&inode->i_mutex); | |
4f6f0bd2 | 913 | |
a4514ebd JA |
914 | if (err) |
915 | ret = err; | |
916 | } | |
17ee4f49 | 917 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
4f6f0bd2 JA |
918 | } |
919 | ||
920 | return ret; | |
5274f052 JA |
921 | } |
922 | ||
059a8f37 JA |
923 | EXPORT_SYMBOL(generic_file_splice_write); |
924 | ||
83f9135b JA |
925 | /** |
926 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 927 | * @pipe: pipe to splice from |
83f9135b | 928 | * @out: socket to write to |
932cc6d4 | 929 | * @ppos: position in @out |
83f9135b JA |
930 | * @len: number of bytes to splice |
931 | * @flags: splice modifier flags | |
932 | * | |
932cc6d4 JA |
933 | * Description: |
934 | * Will send @len bytes from the pipe to a network socket. No data copying | |
935 | * is involved. | |
83f9135b JA |
936 | * |
937 | */ | |
3a326a2c | 938 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 939 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 940 | { |
00522fb4 | 941 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
942 | } |
943 | ||
059a8f37 | 944 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 945 | |
83f9135b JA |
946 | /* |
947 | * Attempt to initiate a splice from pipe to file. | |
948 | */ | |
3a326a2c | 949 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 950 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 951 | { |
5274f052 JA |
952 | int ret; |
953 | ||
49570e9b | 954 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
955 | return -EINVAL; |
956 | ||
49570e9b | 957 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
958 | return -EBADF; |
959 | ||
cbb7e577 | 960 | ret = rw_verify_area(WRITE, out, ppos, len); |
5274f052 JA |
961 | if (unlikely(ret < 0)) |
962 | return ret; | |
963 | ||
cbb7e577 | 964 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
965 | } |
966 | ||
83f9135b JA |
967 | /* |
968 | * Attempt to initiate a splice from a file to a pipe. | |
969 | */ | |
cbb7e577 JA |
970 | static long do_splice_to(struct file *in, loff_t *ppos, |
971 | struct pipe_inode_info *pipe, size_t len, | |
972 | unsigned int flags) | |
5274f052 | 973 | { |
5274f052 JA |
974 | int ret; |
975 | ||
49570e9b | 976 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
977 | return -EINVAL; |
978 | ||
49570e9b | 979 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
980 | return -EBADF; |
981 | ||
cbb7e577 | 982 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
983 | if (unlikely(ret < 0)) |
984 | return ret; | |
985 | ||
cbb7e577 | 986 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 JA |
987 | } |
988 | ||
932cc6d4 JA |
989 | /** |
990 | * splice_direct_to_actor - splices data directly between two non-pipes | |
991 | * @in: file to splice from | |
992 | * @sd: actor information on where to splice to | |
993 | * @actor: handles the data splicing | |
994 | * | |
995 | * Description: | |
996 | * This is a special case helper to splice directly between two | |
997 | * points, without requiring an explicit pipe. Internally an allocated | |
998 | * pipe is cached in the process, and reused during the life time of | |
999 | * that process. | |
1000 | * | |
c66ab6fa JA |
1001 | */ |
1002 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
1003 | splice_direct_actor *actor) | |
b92ce558 JA |
1004 | { |
1005 | struct pipe_inode_info *pipe; | |
1006 | long ret, bytes; | |
1007 | umode_t i_mode; | |
c66ab6fa JA |
1008 | size_t len; |
1009 | int i, flags; | |
b92ce558 JA |
1010 | |
1011 | /* | |
1012 | * We require the input being a regular file, as we don't want to | |
1013 | * randomly drop data for eg socket -> socket splicing. Use the | |
1014 | * piped splicing for that! | |
1015 | */ | |
0f7fc9e4 | 1016 | i_mode = in->f_path.dentry->d_inode->i_mode; |
b92ce558 JA |
1017 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
1018 | return -EINVAL; | |
1019 | ||
1020 | /* | |
1021 | * neither in nor out is a pipe, setup an internal pipe attached to | |
1022 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
1023 | */ | |
1024 | pipe = current->splice_pipe; | |
49570e9b | 1025 | if (unlikely(!pipe)) { |
b92ce558 JA |
1026 | pipe = alloc_pipe_info(NULL); |
1027 | if (!pipe) | |
1028 | return -ENOMEM; | |
1029 | ||
1030 | /* | |
1031 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 1032 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
1033 | * PIPE_READERS appropriately. |
1034 | */ | |
1035 | pipe->readers = 1; | |
1036 | ||
1037 | current->splice_pipe = pipe; | |
1038 | } | |
1039 | ||
1040 | /* | |
73d62d83 | 1041 | * Do the splice. |
b92ce558 JA |
1042 | */ |
1043 | ret = 0; | |
1044 | bytes = 0; | |
c66ab6fa JA |
1045 | len = sd->total_len; |
1046 | flags = sd->flags; | |
1047 | ||
1048 | /* | |
1049 | * Don't block on output, we have to drain the direct pipe. | |
1050 | */ | |
1051 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
b92ce558 JA |
1052 | |
1053 | while (len) { | |
1054 | size_t read_len, max_read_len; | |
1055 | ||
1056 | /* | |
1057 | * Do at most PIPE_BUFFERS pages worth of transfer: | |
1058 | */ | |
1059 | max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); | |
1060 | ||
c66ab6fa | 1061 | ret = do_splice_to(in, &sd->pos, pipe, max_read_len, flags); |
b92ce558 JA |
1062 | if (unlikely(ret < 0)) |
1063 | goto out_release; | |
1064 | ||
1065 | read_len = ret; | |
c66ab6fa | 1066 | sd->total_len = read_len; |
b92ce558 JA |
1067 | |
1068 | /* | |
1069 | * NOTE: nonblocking mode only applies to the input. We | |
1070 | * must not do the output in nonblocking mode as then we | |
1071 | * could get stuck data in the internal pipe: | |
1072 | */ | |
c66ab6fa | 1073 | ret = actor(pipe, sd); |
b92ce558 JA |
1074 | if (unlikely(ret < 0)) |
1075 | goto out_release; | |
1076 | ||
1077 | bytes += ret; | |
1078 | len -= ret; | |
1079 | ||
1080 | /* | |
1081 | * In nonblocking mode, if we got back a short read then | |
1082 | * that was due to either an IO error or due to the | |
1083 | * pagecache entry not being there. In the IO error case | |
1084 | * the _next_ splice attempt will produce a clean IO error | |
1085 | * return value (not a short read), so in both cases it's | |
1086 | * correct to break out of the loop here: | |
1087 | */ | |
1088 | if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) | |
1089 | break; | |
1090 | } | |
1091 | ||
1092 | pipe->nrbufs = pipe->curbuf = 0; | |
1093 | ||
1094 | return bytes; | |
1095 | ||
1096 | out_release: | |
1097 | /* | |
1098 | * If we did an incomplete transfer we must release | |
1099 | * the pipe buffers in question: | |
1100 | */ | |
1101 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
1102 | struct pipe_buffer *buf = pipe->bufs + i; | |
1103 | ||
1104 | if (buf->ops) { | |
1105 | buf->ops->release(pipe, buf); | |
1106 | buf->ops = NULL; | |
1107 | } | |
1108 | } | |
1109 | pipe->nrbufs = pipe->curbuf = 0; | |
1110 | ||
1111 | /* | |
1112 | * If we transferred some data, return the number of bytes: | |
1113 | */ | |
1114 | if (bytes > 0) | |
1115 | return bytes; | |
1116 | ||
1117 | return ret; | |
c66ab6fa JA |
1118 | |
1119 | } | |
1120 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1121 | ||
1122 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1123 | struct splice_desc *sd) | |
1124 | { | |
6a14b90b | 1125 | struct file *file = sd->u.file; |
c66ab6fa JA |
1126 | |
1127 | return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags); | |
1128 | } | |
1129 | ||
932cc6d4 JA |
1130 | /** |
1131 | * do_splice_direct - splices data directly between two files | |
1132 | * @in: file to splice from | |
1133 | * @ppos: input file offset | |
1134 | * @out: file to splice to | |
1135 | * @len: number of bytes to splice | |
1136 | * @flags: splice modifier flags | |
1137 | * | |
1138 | * Description: | |
1139 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1140 | * doing it in the application would incur an extra system call | |
1141 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1142 | * can splice directly through a process-private pipe. | |
1143 | * | |
1144 | */ | |
c66ab6fa JA |
1145 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1146 | size_t len, unsigned int flags) | |
1147 | { | |
1148 | struct splice_desc sd = { | |
1149 | .len = len, | |
1150 | .total_len = len, | |
1151 | .flags = flags, | |
1152 | .pos = *ppos, | |
6a14b90b | 1153 | .u.file = out, |
c66ab6fa JA |
1154 | }; |
1155 | size_t ret; | |
1156 | ||
1157 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); | |
1158 | *ppos = sd.pos; | |
1159 | return ret; | |
b92ce558 JA |
1160 | } |
1161 | ||
ddac0d39 JA |
1162 | /* |
1163 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same | |
1164 | * location, so checking ->i_pipe is not enough to verify that this is a | |
1165 | * pipe. | |
1166 | */ | |
1167 | static inline struct pipe_inode_info *pipe_info(struct inode *inode) | |
1168 | { | |
1169 | if (S_ISFIFO(inode->i_mode)) | |
1170 | return inode->i_pipe; | |
1171 | ||
1172 | return NULL; | |
1173 | } | |
1174 | ||
83f9135b JA |
1175 | /* |
1176 | * Determine where to splice to/from. | |
1177 | */ | |
529565dc IM |
1178 | static long do_splice(struct file *in, loff_t __user *off_in, |
1179 | struct file *out, loff_t __user *off_out, | |
1180 | size_t len, unsigned int flags) | |
5274f052 | 1181 | { |
3a326a2c | 1182 | struct pipe_inode_info *pipe; |
cbb7e577 | 1183 | loff_t offset, *off; |
a4514ebd | 1184 | long ret; |
5274f052 | 1185 | |
0f7fc9e4 | 1186 | pipe = pipe_info(in->f_path.dentry->d_inode); |
529565dc IM |
1187 | if (pipe) { |
1188 | if (off_in) | |
1189 | return -ESPIPE; | |
b92ce558 JA |
1190 | if (off_out) { |
1191 | if (out->f_op->llseek == no_llseek) | |
1192 | return -EINVAL; | |
cbb7e577 | 1193 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1194 | return -EFAULT; |
cbb7e577 JA |
1195 | off = &offset; |
1196 | } else | |
1197 | off = &out->f_pos; | |
529565dc | 1198 | |
a4514ebd JA |
1199 | ret = do_splice_from(pipe, out, off, len, flags); |
1200 | ||
1201 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
1202 | ret = -EFAULT; | |
1203 | ||
1204 | return ret; | |
529565dc | 1205 | } |
5274f052 | 1206 | |
0f7fc9e4 | 1207 | pipe = pipe_info(out->f_path.dentry->d_inode); |
529565dc IM |
1208 | if (pipe) { |
1209 | if (off_out) | |
1210 | return -ESPIPE; | |
b92ce558 JA |
1211 | if (off_in) { |
1212 | if (in->f_op->llseek == no_llseek) | |
1213 | return -EINVAL; | |
cbb7e577 | 1214 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1215 | return -EFAULT; |
cbb7e577 JA |
1216 | off = &offset; |
1217 | } else | |
1218 | off = &in->f_pos; | |
529565dc | 1219 | |
a4514ebd JA |
1220 | ret = do_splice_to(in, off, pipe, len, flags); |
1221 | ||
1222 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
1223 | ret = -EFAULT; | |
1224 | ||
1225 | return ret; | |
529565dc | 1226 | } |
5274f052 JA |
1227 | |
1228 | return -EINVAL; | |
1229 | } | |
1230 | ||
912d35f8 JA |
1231 | /* |
1232 | * Map an iov into an array of pages and offset/length tupples. With the | |
1233 | * partial_page structure, we can map several non-contiguous ranges into | |
1234 | * our ones pages[] map instead of splitting that operation into pieces. | |
1235 | * Could easily be exported as a generic helper for other users, in which | |
1236 | * case one would probably want to add a 'max_nr_pages' parameter as well. | |
1237 | */ | |
1238 | static int get_iovec_page_array(const struct iovec __user *iov, | |
1239 | unsigned int nr_vecs, struct page **pages, | |
7afa6fd0 | 1240 | struct partial_page *partial, int aligned) |
912d35f8 JA |
1241 | { |
1242 | int buffers = 0, error = 0; | |
1243 | ||
1244 | /* | |
1245 | * It's ok to take the mmap_sem for reading, even | |
1246 | * across a "get_user()". | |
1247 | */ | |
1248 | down_read(¤t->mm->mmap_sem); | |
1249 | ||
1250 | while (nr_vecs) { | |
1251 | unsigned long off, npages; | |
1252 | void __user *base; | |
1253 | size_t len; | |
1254 | int i; | |
1255 | ||
1256 | /* | |
1257 | * Get user address base and length for this iovec. | |
1258 | */ | |
1259 | error = get_user(base, &iov->iov_base); | |
1260 | if (unlikely(error)) | |
1261 | break; | |
1262 | error = get_user(len, &iov->iov_len); | |
1263 | if (unlikely(error)) | |
1264 | break; | |
1265 | ||
1266 | /* | |
1267 | * Sanity check this iovec. 0 read succeeds. | |
1268 | */ | |
1269 | if (unlikely(!len)) | |
1270 | break; | |
1271 | error = -EFAULT; | |
1272 | if (unlikely(!base)) | |
1273 | break; | |
1274 | ||
1275 | /* | |
1276 | * Get this base offset and number of pages, then map | |
1277 | * in the user pages. | |
1278 | */ | |
1279 | off = (unsigned long) base & ~PAGE_MASK; | |
7afa6fd0 JA |
1280 | |
1281 | /* | |
1282 | * If asked for alignment, the offset must be zero and the | |
1283 | * length a multiple of the PAGE_SIZE. | |
1284 | */ | |
1285 | error = -EINVAL; | |
1286 | if (aligned && (off || len & ~PAGE_MASK)) | |
1287 | break; | |
1288 | ||
912d35f8 JA |
1289 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1290 | if (npages > PIPE_BUFFERS - buffers) | |
1291 | npages = PIPE_BUFFERS - buffers; | |
1292 | ||
1293 | error = get_user_pages(current, current->mm, | |
1294 | (unsigned long) base, npages, 0, 0, | |
1295 | &pages[buffers], NULL); | |
1296 | ||
1297 | if (unlikely(error <= 0)) | |
1298 | break; | |
1299 | ||
1300 | /* | |
1301 | * Fill this contiguous range into the partial page map. | |
1302 | */ | |
1303 | for (i = 0; i < error; i++) { | |
7591489a | 1304 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
912d35f8 JA |
1305 | |
1306 | partial[buffers].offset = off; | |
1307 | partial[buffers].len = plen; | |
1308 | ||
1309 | off = 0; | |
1310 | len -= plen; | |
1311 | buffers++; | |
1312 | } | |
1313 | ||
1314 | /* | |
1315 | * We didn't complete this iov, stop here since it probably | |
1316 | * means we have to move some of this into a pipe to | |
1317 | * be able to continue. | |
1318 | */ | |
1319 | if (len) | |
1320 | break; | |
1321 | ||
1322 | /* | |
1323 | * Don't continue if we mapped fewer pages than we asked for, | |
1324 | * or if we mapped the max number of pages that we have | |
1325 | * room for. | |
1326 | */ | |
1327 | if (error < npages || buffers == PIPE_BUFFERS) | |
1328 | break; | |
1329 | ||
1330 | nr_vecs--; | |
1331 | iov++; | |
1332 | } | |
1333 | ||
1334 | up_read(¤t->mm->mmap_sem); | |
1335 | ||
1336 | if (buffers) | |
1337 | return buffers; | |
1338 | ||
1339 | return error; | |
1340 | } | |
1341 | ||
6a14b90b JA |
1342 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1343 | struct splice_desc *sd) | |
1344 | { | |
1345 | char *src; | |
1346 | int ret; | |
1347 | ||
cac36bb0 | 1348 | ret = buf->ops->confirm(pipe, buf); |
6a14b90b JA |
1349 | if (unlikely(ret)) |
1350 | return ret; | |
1351 | ||
1352 | /* | |
1353 | * See if we can use the atomic maps, by prefaulting in the | |
1354 | * pages and doing an atomic copy | |
1355 | */ | |
1356 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { | |
1357 | src = buf->ops->map(pipe, buf, 1); | |
1358 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, | |
1359 | sd->len); | |
1360 | buf->ops->unmap(pipe, buf, src); | |
1361 | if (!ret) { | |
1362 | ret = sd->len; | |
1363 | goto out; | |
1364 | } | |
1365 | } | |
1366 | ||
1367 | /* | |
1368 | * No dice, use slow non-atomic map and copy | |
1369 | */ | |
1370 | src = buf->ops->map(pipe, buf, 0); | |
1371 | ||
1372 | ret = sd->len; | |
1373 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) | |
1374 | ret = -EFAULT; | |
1375 | ||
1376 | out: | |
1377 | if (ret > 0) | |
1378 | sd->u.userptr += ret; | |
1379 | buf->ops->unmap(pipe, buf, src); | |
1380 | return ret; | |
1381 | } | |
1382 | ||
1383 | /* | |
1384 | * For lack of a better implementation, implement vmsplice() to userspace | |
1385 | * as a simple copy of the pipes pages to the user iov. | |
1386 | */ | |
1387 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, | |
1388 | unsigned long nr_segs, unsigned int flags) | |
1389 | { | |
1390 | struct pipe_inode_info *pipe; | |
1391 | struct splice_desc sd; | |
1392 | ssize_t size; | |
1393 | int error; | |
1394 | long ret; | |
1395 | ||
1396 | pipe = pipe_info(file->f_path.dentry->d_inode); | |
1397 | if (!pipe) | |
1398 | return -EBADF; | |
1399 | ||
1400 | if (pipe->inode) | |
1401 | mutex_lock(&pipe->inode->i_mutex); | |
1402 | ||
1403 | error = ret = 0; | |
1404 | while (nr_segs) { | |
1405 | void __user *base; | |
1406 | size_t len; | |
1407 | ||
1408 | /* | |
1409 | * Get user address base and length for this iovec. | |
1410 | */ | |
1411 | error = get_user(base, &iov->iov_base); | |
1412 | if (unlikely(error)) | |
1413 | break; | |
1414 | error = get_user(len, &iov->iov_len); | |
1415 | if (unlikely(error)) | |
1416 | break; | |
1417 | ||
1418 | /* | |
1419 | * Sanity check this iovec. 0 read succeeds. | |
1420 | */ | |
1421 | if (unlikely(!len)) | |
1422 | break; | |
1423 | if (unlikely(!base)) { | |
1424 | error = -EFAULT; | |
1425 | break; | |
1426 | } | |
1427 | ||
1428 | sd.len = 0; | |
1429 | sd.total_len = len; | |
1430 | sd.flags = flags; | |
1431 | sd.u.userptr = base; | |
1432 | sd.pos = 0; | |
1433 | ||
1434 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1435 | if (size < 0) { | |
1436 | if (!ret) | |
1437 | ret = size; | |
1438 | ||
1439 | break; | |
1440 | } | |
1441 | ||
1442 | ret += size; | |
1443 | ||
1444 | if (size < len) | |
1445 | break; | |
1446 | ||
1447 | nr_segs--; | |
1448 | iov++; | |
1449 | } | |
1450 | ||
1451 | if (pipe->inode) | |
1452 | mutex_unlock(&pipe->inode->i_mutex); | |
1453 | ||
1454 | if (!ret) | |
1455 | ret = error; | |
1456 | ||
1457 | return ret; | |
1458 | } | |
1459 | ||
912d35f8 JA |
1460 | /* |
1461 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1462 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1463 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1464 | */ |
6a14b90b JA |
1465 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1466 | unsigned long nr_segs, unsigned int flags) | |
912d35f8 | 1467 | { |
ddac0d39 | 1468 | struct pipe_inode_info *pipe; |
912d35f8 JA |
1469 | struct page *pages[PIPE_BUFFERS]; |
1470 | struct partial_page partial[PIPE_BUFFERS]; | |
1471 | struct splice_pipe_desc spd = { | |
1472 | .pages = pages, | |
1473 | .partial = partial, | |
1474 | .flags = flags, | |
1475 | .ops = &user_page_pipe_buf_ops, | |
1476 | }; | |
1477 | ||
0f7fc9e4 | 1478 | pipe = pipe_info(file->f_path.dentry->d_inode); |
ddac0d39 | 1479 | if (!pipe) |
912d35f8 | 1480 | return -EBADF; |
912d35f8 | 1481 | |
7afa6fd0 JA |
1482 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial, |
1483 | flags & SPLICE_F_GIFT); | |
912d35f8 JA |
1484 | if (spd.nr_pages <= 0) |
1485 | return spd.nr_pages; | |
1486 | ||
00522fb4 | 1487 | return splice_to_pipe(pipe, &spd); |
912d35f8 JA |
1488 | } |
1489 | ||
6a14b90b JA |
1490 | /* |
1491 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1492 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1493 | * operation that can be supported without any funky alignment restrictions | |
1494 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1495 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1496 | * solutions for that: | |
1497 | * | |
1498 | * - memcpy() the data internally, at which point we might as well just | |
1499 | * do a regular read() on the buffer anyway. | |
1500 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1501 | * has restriction limitations on both ends of the pipe). | |
1502 | * | |
1503 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1504 | * | |
1505 | */ | |
912d35f8 JA |
1506 | asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov, |
1507 | unsigned long nr_segs, unsigned int flags) | |
1508 | { | |
1509 | struct file *file; | |
1510 | long error; | |
1511 | int fput; | |
1512 | ||
6a14b90b JA |
1513 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1514 | return -EINVAL; | |
1515 | else if (unlikely(!nr_segs)) | |
1516 | return 0; | |
1517 | ||
912d35f8 JA |
1518 | error = -EBADF; |
1519 | file = fget_light(fd, &fput); | |
1520 | if (file) { | |
1521 | if (file->f_mode & FMODE_WRITE) | |
6a14b90b JA |
1522 | error = vmsplice_to_pipe(file, iov, nr_segs, flags); |
1523 | else if (file->f_mode & FMODE_READ) | |
1524 | error = vmsplice_to_user(file, iov, nr_segs, flags); | |
912d35f8 JA |
1525 | |
1526 | fput_light(file, fput); | |
1527 | } | |
1528 | ||
1529 | return error; | |
1530 | } | |
1531 | ||
529565dc IM |
1532 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
1533 | int fd_out, loff_t __user *off_out, | |
1534 | size_t len, unsigned int flags) | |
5274f052 JA |
1535 | { |
1536 | long error; | |
1537 | struct file *in, *out; | |
1538 | int fput_in, fput_out; | |
1539 | ||
1540 | if (unlikely(!len)) | |
1541 | return 0; | |
1542 | ||
1543 | error = -EBADF; | |
529565dc | 1544 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
1545 | if (in) { |
1546 | if (in->f_mode & FMODE_READ) { | |
529565dc | 1547 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
1548 | if (out) { |
1549 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
1550 | error = do_splice(in, off_in, |
1551 | out, off_out, | |
1552 | len, flags); | |
5274f052 JA |
1553 | fput_light(out, fput_out); |
1554 | } | |
1555 | } | |
1556 | ||
1557 | fput_light(in, fput_in); | |
1558 | } | |
1559 | ||
1560 | return error; | |
1561 | } | |
70524490 | 1562 | |
aadd06e5 JA |
1563 | /* |
1564 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1565 | * return an appropriate error. | |
1566 | */ | |
1567 | static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1568 | { | |
1569 | int ret; | |
1570 | ||
1571 | /* | |
1572 | * Check ->nrbufs without the inode lock first. This function | |
1573 | * is speculative anyways, so missing one is ok. | |
1574 | */ | |
1575 | if (pipe->nrbufs) | |
1576 | return 0; | |
1577 | ||
1578 | ret = 0; | |
1579 | mutex_lock(&pipe->inode->i_mutex); | |
1580 | ||
1581 | while (!pipe->nrbufs) { | |
1582 | if (signal_pending(current)) { | |
1583 | ret = -ERESTARTSYS; | |
1584 | break; | |
1585 | } | |
1586 | if (!pipe->writers) | |
1587 | break; | |
1588 | if (!pipe->waiting_writers) { | |
1589 | if (flags & SPLICE_F_NONBLOCK) { | |
1590 | ret = -EAGAIN; | |
1591 | break; | |
1592 | } | |
1593 | } | |
1594 | pipe_wait(pipe); | |
1595 | } | |
1596 | ||
1597 | mutex_unlock(&pipe->inode->i_mutex); | |
1598 | return ret; | |
1599 | } | |
1600 | ||
1601 | /* | |
1602 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1603 | * return an appropriate error. | |
1604 | */ | |
1605 | static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1606 | { | |
1607 | int ret; | |
1608 | ||
1609 | /* | |
1610 | * Check ->nrbufs without the inode lock first. This function | |
1611 | * is speculative anyways, so missing one is ok. | |
1612 | */ | |
1613 | if (pipe->nrbufs < PIPE_BUFFERS) | |
1614 | return 0; | |
1615 | ||
1616 | ret = 0; | |
1617 | mutex_lock(&pipe->inode->i_mutex); | |
1618 | ||
1619 | while (pipe->nrbufs >= PIPE_BUFFERS) { | |
1620 | if (!pipe->readers) { | |
1621 | send_sig(SIGPIPE, current, 0); | |
1622 | ret = -EPIPE; | |
1623 | break; | |
1624 | } | |
1625 | if (flags & SPLICE_F_NONBLOCK) { | |
1626 | ret = -EAGAIN; | |
1627 | break; | |
1628 | } | |
1629 | if (signal_pending(current)) { | |
1630 | ret = -ERESTARTSYS; | |
1631 | break; | |
1632 | } | |
1633 | pipe->waiting_writers++; | |
1634 | pipe_wait(pipe); | |
1635 | pipe->waiting_writers--; | |
1636 | } | |
1637 | ||
1638 | mutex_unlock(&pipe->inode->i_mutex); | |
1639 | return ret; | |
1640 | } | |
1641 | ||
70524490 JA |
1642 | /* |
1643 | * Link contents of ipipe to opipe. | |
1644 | */ | |
1645 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1646 | struct pipe_inode_info *opipe, | |
1647 | size_t len, unsigned int flags) | |
1648 | { | |
1649 | struct pipe_buffer *ibuf, *obuf; | |
aadd06e5 | 1650 | int ret = 0, i = 0, nbuf; |
70524490 JA |
1651 | |
1652 | /* | |
1653 | * Potential ABBA deadlock, work around it by ordering lock | |
1654 | * grabbing by inode address. Otherwise two different processes | |
1655 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1656 | */ | |
62752ee1 | 1657 | inode_double_lock(ipipe->inode, opipe->inode); |
70524490 | 1658 | |
aadd06e5 | 1659 | do { |
70524490 JA |
1660 | if (!opipe->readers) { |
1661 | send_sig(SIGPIPE, current, 0); | |
1662 | if (!ret) | |
1663 | ret = -EPIPE; | |
1664 | break; | |
1665 | } | |
70524490 | 1666 | |
aadd06e5 JA |
1667 | /* |
1668 | * If we have iterated all input buffers or ran out of | |
1669 | * output room, break. | |
1670 | */ | |
1671 | if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) | |
1672 | break; | |
70524490 | 1673 | |
aadd06e5 JA |
1674 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); |
1675 | nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); | |
70524490 JA |
1676 | |
1677 | /* | |
aadd06e5 JA |
1678 | * Get a reference to this pipe buffer, |
1679 | * so we can copy the contents over. | |
70524490 | 1680 | */ |
aadd06e5 JA |
1681 | ibuf->ops->get(ipipe, ibuf); |
1682 | ||
1683 | obuf = opipe->bufs + nbuf; | |
1684 | *obuf = *ibuf; | |
1685 | ||
2a27250e | 1686 | /* |
aadd06e5 JA |
1687 | * Don't inherit the gift flag, we need to |
1688 | * prevent multiple steals of this page. | |
2a27250e | 1689 | */ |
aadd06e5 | 1690 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
70524490 | 1691 | |
aadd06e5 JA |
1692 | if (obuf->len > len) |
1693 | obuf->len = len; | |
70524490 | 1694 | |
aadd06e5 JA |
1695 | opipe->nrbufs++; |
1696 | ret += obuf->len; | |
1697 | len -= obuf->len; | |
1698 | i++; | |
1699 | } while (len); | |
70524490 | 1700 | |
62752ee1 | 1701 | inode_double_unlock(ipipe->inode, opipe->inode); |
70524490 | 1702 | |
aadd06e5 JA |
1703 | /* |
1704 | * If we put data in the output pipe, wakeup any potential readers. | |
1705 | */ | |
1706 | if (ret > 0) { | |
70524490 JA |
1707 | smp_mb(); |
1708 | if (waitqueue_active(&opipe->wait)) | |
1709 | wake_up_interruptible(&opipe->wait); | |
1710 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1711 | } | |
1712 | ||
1713 | return ret; | |
1714 | } | |
1715 | ||
1716 | /* | |
1717 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1718 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1719 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1720 | * applicable one is SPLICE_F_NONBLOCK. | |
1721 | */ | |
1722 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1723 | unsigned int flags) | |
1724 | { | |
0f7fc9e4 JJS |
1725 | struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode); |
1726 | struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode); | |
aadd06e5 | 1727 | int ret = -EINVAL; |
70524490 JA |
1728 | |
1729 | /* | |
aadd06e5 JA |
1730 | * Duplicate the contents of ipipe to opipe without actually |
1731 | * copying the data. | |
70524490 | 1732 | */ |
aadd06e5 JA |
1733 | if (ipipe && opipe && ipipe != opipe) { |
1734 | /* | |
1735 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1736 | * ordering doesn't really matter. | |
1737 | */ | |
1738 | ret = link_ipipe_prep(ipipe, flags); | |
1739 | if (!ret) { | |
1740 | ret = link_opipe_prep(opipe, flags); | |
1741 | if (!ret) { | |
1742 | ret = link_pipe(ipipe, opipe, len, flags); | |
1743 | if (!ret && (flags & SPLICE_F_NONBLOCK)) | |
1744 | ret = -EAGAIN; | |
1745 | } | |
1746 | } | |
1747 | } | |
70524490 | 1748 | |
aadd06e5 | 1749 | return ret; |
70524490 JA |
1750 | } |
1751 | ||
1752 | asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) | |
1753 | { | |
1754 | struct file *in; | |
1755 | int error, fput_in; | |
1756 | ||
1757 | if (unlikely(!len)) | |
1758 | return 0; | |
1759 | ||
1760 | error = -EBADF; | |
1761 | in = fget_light(fdin, &fput_in); | |
1762 | if (in) { | |
1763 | if (in->f_mode & FMODE_READ) { | |
1764 | int fput_out; | |
1765 | struct file *out = fget_light(fdout, &fput_out); | |
1766 | ||
1767 | if (out) { | |
1768 | if (out->f_mode & FMODE_WRITE) | |
1769 | error = do_tee(in, out, len, flags); | |
1770 | fput_light(out, fput_out); | |
1771 | } | |
1772 | } | |
1773 | fput_light(in, fput_in); | |
1774 | } | |
1775 | ||
1776 | return error; | |
1777 | } |