]>
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 | * |
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> |
29ce2058 | 31 | #include <linux/security.h> |
5274f052 | 32 | |
83f9135b JA |
33 | /* |
34 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
35 | * a vm helper function, it's already simplified quite a bit by the | |
36 | * addition of remove_mapping(). If success is returned, the caller may | |
37 | * attempt to reuse this page for another destination. | |
38 | */ | |
76ad4d11 | 39 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
5abc97aa JA |
40 | struct pipe_buffer *buf) |
41 | { | |
42 | struct page *page = buf->page; | |
9e94cd4f | 43 | struct address_space *mapping; |
5abc97aa | 44 | |
9e0267c2 JA |
45 | lock_page(page); |
46 | ||
9e94cd4f JA |
47 | mapping = page_mapping(page); |
48 | if (mapping) { | |
49 | WARN_ON(!PageUptodate(page)); | |
5abc97aa | 50 | |
9e94cd4f JA |
51 | /* |
52 | * At least for ext2 with nobh option, we need to wait on | |
53 | * writeback completing on this page, since we'll remove it | |
54 | * from the pagecache. Otherwise truncate wont wait on the | |
55 | * page, allowing the disk blocks to be reused by someone else | |
56 | * before we actually wrote our data to them. fs corruption | |
57 | * ensues. | |
58 | */ | |
59 | wait_on_page_writeback(page); | |
ad8d6f0a | 60 | |
ca39d651 JA |
61 | if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL)) |
62 | goto out_unlock; | |
4f6f0bd2 | 63 | |
9e94cd4f JA |
64 | /* |
65 | * If we succeeded in removing the mapping, set LRU flag | |
66 | * and return good. | |
67 | */ | |
68 | if (remove_mapping(mapping, page)) { | |
69 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
70 | return 0; | |
71 | } | |
9e0267c2 | 72 | } |
5abc97aa | 73 | |
9e94cd4f JA |
74 | /* |
75 | * Raced with truncate or failed to remove page from current | |
76 | * address space, unlock and return failure. | |
77 | */ | |
ca39d651 | 78 | out_unlock: |
9e94cd4f JA |
79 | unlock_page(page); |
80 | return 1; | |
5abc97aa JA |
81 | } |
82 | ||
76ad4d11 | 83 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
5274f052 JA |
84 | struct pipe_buffer *buf) |
85 | { | |
86 | page_cache_release(buf->page); | |
1432873a | 87 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
88 | } |
89 | ||
0845718d JA |
90 | /* |
91 | * Check whether the contents of buf is OK to access. Since the content | |
92 | * is a page cache page, IO may be in flight. | |
93 | */ | |
cac36bb0 JA |
94 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
95 | struct pipe_buffer *buf) | |
5274f052 JA |
96 | { |
97 | struct page *page = buf->page; | |
49d0b21b | 98 | int err; |
5274f052 JA |
99 | |
100 | if (!PageUptodate(page)) { | |
49d0b21b JA |
101 | lock_page(page); |
102 | ||
103 | /* | |
104 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 105 | * splice, if this is the first page. |
49d0b21b JA |
106 | */ |
107 | if (!page->mapping) { | |
108 | err = -ENODATA; | |
109 | goto error; | |
110 | } | |
5274f052 | 111 | |
49d0b21b | 112 | /* |
73d62d83 | 113 | * Uh oh, read-error from disk. |
49d0b21b JA |
114 | */ |
115 | if (!PageUptodate(page)) { | |
116 | err = -EIO; | |
117 | goto error; | |
118 | } | |
119 | ||
120 | /* | |
f84d7519 | 121 | * Page is ok afterall, we are done. |
49d0b21b | 122 | */ |
5274f052 | 123 | unlock_page(page); |
5274f052 JA |
124 | } |
125 | ||
f84d7519 | 126 | return 0; |
49d0b21b JA |
127 | error: |
128 | unlock_page(page); | |
f84d7519 | 129 | return err; |
70524490 JA |
130 | } |
131 | ||
d4c3cca9 | 132 | static const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
5274f052 | 133 | .can_merge = 0, |
f84d7519 JA |
134 | .map = generic_pipe_buf_map, |
135 | .unmap = generic_pipe_buf_unmap, | |
cac36bb0 | 136 | .confirm = page_cache_pipe_buf_confirm, |
5274f052 | 137 | .release = page_cache_pipe_buf_release, |
5abc97aa | 138 | .steal = page_cache_pipe_buf_steal, |
f84d7519 | 139 | .get = generic_pipe_buf_get, |
5274f052 JA |
140 | }; |
141 | ||
912d35f8 JA |
142 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
143 | struct pipe_buffer *buf) | |
144 | { | |
7afa6fd0 JA |
145 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
146 | return 1; | |
147 | ||
1432873a | 148 | buf->flags |= PIPE_BUF_FLAG_LRU; |
330ab716 | 149 | return generic_pipe_buf_steal(pipe, buf); |
912d35f8 JA |
150 | } |
151 | ||
d4c3cca9 | 152 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
912d35f8 | 153 | .can_merge = 0, |
f84d7519 JA |
154 | .map = generic_pipe_buf_map, |
155 | .unmap = generic_pipe_buf_unmap, | |
cac36bb0 | 156 | .confirm = generic_pipe_buf_confirm, |
912d35f8 JA |
157 | .release = page_cache_pipe_buf_release, |
158 | .steal = user_page_pipe_buf_steal, | |
f84d7519 | 159 | .get = generic_pipe_buf_get, |
912d35f8 JA |
160 | }; |
161 | ||
932cc6d4 JA |
162 | /** |
163 | * splice_to_pipe - fill passed data into a pipe | |
164 | * @pipe: pipe to fill | |
165 | * @spd: data to fill | |
166 | * | |
167 | * Description: | |
79685b8d | 168 | * @spd contains a map of pages and len/offset tuples, along with |
932cc6d4 JA |
169 | * the struct pipe_buf_operations associated with these pages. This |
170 | * function will link that data to the pipe. | |
171 | * | |
83f9135b | 172 | */ |
d6b29d7c JA |
173 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
174 | struct splice_pipe_desc *spd) | |
5274f052 | 175 | { |
00de00bd | 176 | unsigned int spd_pages = spd->nr_pages; |
912d35f8 | 177 | int ret, do_wakeup, page_nr; |
5274f052 JA |
178 | |
179 | ret = 0; | |
180 | do_wakeup = 0; | |
912d35f8 | 181 | page_nr = 0; |
5274f052 | 182 | |
3a326a2c IM |
183 | if (pipe->inode) |
184 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 185 | |
5274f052 | 186 | for (;;) { |
3a326a2c | 187 | if (!pipe->readers) { |
5274f052 JA |
188 | send_sig(SIGPIPE, current, 0); |
189 | if (!ret) | |
190 | ret = -EPIPE; | |
191 | break; | |
192 | } | |
193 | ||
6f767b04 JA |
194 | if (pipe->nrbufs < PIPE_BUFFERS) { |
195 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); | |
3a326a2c | 196 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
5274f052 | 197 | |
912d35f8 JA |
198 | buf->page = spd->pages[page_nr]; |
199 | buf->offset = spd->partial[page_nr].offset; | |
200 | buf->len = spd->partial[page_nr].len; | |
497f9625 | 201 | buf->private = spd->partial[page_nr].private; |
912d35f8 | 202 | buf->ops = spd->ops; |
7afa6fd0 JA |
203 | if (spd->flags & SPLICE_F_GIFT) |
204 | buf->flags |= PIPE_BUF_FLAG_GIFT; | |
205 | ||
6f767b04 | 206 | pipe->nrbufs++; |
912d35f8 JA |
207 | page_nr++; |
208 | ret += buf->len; | |
209 | ||
6f767b04 JA |
210 | if (pipe->inode) |
211 | do_wakeup = 1; | |
5274f052 | 212 | |
912d35f8 | 213 | if (!--spd->nr_pages) |
5274f052 | 214 | break; |
6f767b04 | 215 | if (pipe->nrbufs < PIPE_BUFFERS) |
5274f052 JA |
216 | continue; |
217 | ||
218 | break; | |
219 | } | |
220 | ||
912d35f8 | 221 | if (spd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
222 | if (!ret) |
223 | ret = -EAGAIN; | |
224 | break; | |
225 | } | |
226 | ||
5274f052 JA |
227 | if (signal_pending(current)) { |
228 | if (!ret) | |
229 | ret = -ERESTARTSYS; | |
230 | break; | |
231 | } | |
232 | ||
233 | if (do_wakeup) { | |
c0bd1f65 | 234 | smp_mb(); |
3a326a2c IM |
235 | if (waitqueue_active(&pipe->wait)) |
236 | wake_up_interruptible_sync(&pipe->wait); | |
237 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
238 | do_wakeup = 0; |
239 | } | |
240 | ||
3a326a2c IM |
241 | pipe->waiting_writers++; |
242 | pipe_wait(pipe); | |
243 | pipe->waiting_writers--; | |
5274f052 JA |
244 | } |
245 | ||
02676e5a | 246 | if (pipe->inode) { |
3a326a2c | 247 | mutex_unlock(&pipe->inode->i_mutex); |
5274f052 | 248 | |
02676e5a JA |
249 | if (do_wakeup) { |
250 | smp_mb(); | |
251 | if (waitqueue_active(&pipe->wait)) | |
252 | wake_up_interruptible(&pipe->wait); | |
253 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
254 | } | |
5274f052 JA |
255 | } |
256 | ||
00de00bd | 257 | while (page_nr < spd_pages) |
bbdfc2f7 | 258 | spd->spd_release(spd, page_nr++); |
5274f052 JA |
259 | |
260 | return ret; | |
261 | } | |
262 | ||
bbdfc2f7 JA |
263 | static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
264 | { | |
265 | page_cache_release(spd->pages[i]); | |
266 | } | |
267 | ||
3a326a2c | 268 | static int |
cbb7e577 JA |
269 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
270 | struct pipe_inode_info *pipe, size_t len, | |
271 | unsigned int flags) | |
5274f052 JA |
272 | { |
273 | struct address_space *mapping = in->f_mapping; | |
d8983910 | 274 | unsigned int loff, nr_pages, req_pages; |
16c523dd | 275 | struct page *pages[PIPE_BUFFERS]; |
912d35f8 | 276 | struct partial_page partial[PIPE_BUFFERS]; |
5274f052 | 277 | struct page *page; |
91ad66ef JA |
278 | pgoff_t index, end_index; |
279 | loff_t isize; | |
eb20796b | 280 | int error, page_nr; |
912d35f8 JA |
281 | struct splice_pipe_desc spd = { |
282 | .pages = pages, | |
283 | .partial = partial, | |
284 | .flags = flags, | |
285 | .ops = &page_cache_pipe_buf_ops, | |
bbdfc2f7 | 286 | .spd_release = spd_release_page, |
912d35f8 | 287 | }; |
5274f052 | 288 | |
cbb7e577 | 289 | index = *ppos >> PAGE_CACHE_SHIFT; |
912d35f8 | 290 | loff = *ppos & ~PAGE_CACHE_MASK; |
d8983910 FW |
291 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
292 | nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS); | |
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); | |
431a4820 | 298 | index += spd.nr_pages; |
82aa5d61 | 299 | |
eb20796b JA |
300 | /* |
301 | * If find_get_pages_contig() returned fewer pages than we needed, | |
431a4820 | 302 | * readahead/allocate the rest and fill in the holes. |
eb20796b | 303 | */ |
431a4820 | 304 | if (spd.nr_pages < nr_pages) |
cf914a7d RR |
305 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
306 | index, req_pages - spd.nr_pages); | |
431a4820 | 307 | |
932cc6d4 | 308 | error = 0; |
eb20796b | 309 | while (spd.nr_pages < nr_pages) { |
82aa5d61 | 310 | /* |
eb20796b JA |
311 | * Page could be there, find_get_pages_contig() breaks on |
312 | * the first hole. | |
5274f052 | 313 | */ |
7480a904 JA |
314 | page = find_get_page(mapping, index); |
315 | if (!page) { | |
7480a904 | 316 | /* |
eb20796b | 317 | * page didn't exist, allocate one. |
7480a904 JA |
318 | */ |
319 | page = page_cache_alloc_cold(mapping); | |
320 | if (!page) | |
321 | break; | |
322 | ||
323 | error = add_to_page_cache_lru(page, mapping, index, | |
4cd13504 | 324 | mapping_gfp_mask(mapping)); |
7480a904 JA |
325 | if (unlikely(error)) { |
326 | page_cache_release(page); | |
a0548871 JA |
327 | if (error == -EEXIST) |
328 | continue; | |
7480a904 JA |
329 | break; |
330 | } | |
eb20796b JA |
331 | /* |
332 | * add_to_page_cache() locks the page, unlock it | |
333 | * to avoid convoluting the logic below even more. | |
334 | */ | |
335 | unlock_page(page); | |
7480a904 JA |
336 | } |
337 | ||
eb20796b JA |
338 | pages[spd.nr_pages++] = page; |
339 | index++; | |
340 | } | |
341 | ||
342 | /* | |
343 | * Now loop over the map and see if we need to start IO on any | |
344 | * pages, fill in the partial map, etc. | |
345 | */ | |
346 | index = *ppos >> PAGE_CACHE_SHIFT; | |
347 | nr_pages = spd.nr_pages; | |
348 | spd.nr_pages = 0; | |
349 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
350 | unsigned int this_len; | |
351 | ||
352 | if (!len) | |
353 | break; | |
354 | ||
355 | /* | |
356 | * this_len is the max we'll use from this page | |
357 | */ | |
358 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
359 | page = pages[page_nr]; | |
360 | ||
a08a166f | 361 | if (PageReadahead(page)) |
cf914a7d | 362 | page_cache_async_readahead(mapping, &in->f_ra, in, |
d8983910 | 363 | page, index, req_pages - page_nr); |
a08a166f | 364 | |
7480a904 JA |
365 | /* |
366 | * If the page isn't uptodate, we may need to start io on it | |
367 | */ | |
368 | if (!PageUptodate(page)) { | |
c4f895cb JA |
369 | /* |
370 | * If in nonblock mode then dont block on waiting | |
371 | * for an in-flight io page | |
372 | */ | |
9ae9d68c | 373 | if (flags & SPLICE_F_NONBLOCK) { |
8191ecd1 JA |
374 | if (TestSetPageLocked(page)) { |
375 | error = -EAGAIN; | |
9ae9d68c | 376 | break; |
8191ecd1 | 377 | } |
9ae9d68c FW |
378 | } else |
379 | lock_page(page); | |
7480a904 JA |
380 | |
381 | /* | |
382 | * page was truncated, stop here. if this isn't the | |
383 | * first page, we'll just complete what we already | |
384 | * added | |
385 | */ | |
386 | if (!page->mapping) { | |
387 | unlock_page(page); | |
7480a904 JA |
388 | break; |
389 | } | |
390 | /* | |
391 | * page was already under io and is now done, great | |
392 | */ | |
393 | if (PageUptodate(page)) { | |
394 | unlock_page(page); | |
395 | goto fill_it; | |
396 | } | |
5274f052 | 397 | |
7480a904 JA |
398 | /* |
399 | * need to read in the page | |
400 | */ | |
401 | error = mapping->a_ops->readpage(in, page); | |
5274f052 | 402 | if (unlikely(error)) { |
eb20796b JA |
403 | /* |
404 | * We really should re-lookup the page here, | |
405 | * but it complicates things a lot. Instead | |
406 | * lets just do what we already stored, and | |
407 | * we'll get it the next time we are called. | |
408 | */ | |
7480a904 | 409 | if (error == AOP_TRUNCATED_PAGE) |
eb20796b JA |
410 | error = 0; |
411 | ||
5274f052 JA |
412 | break; |
413 | } | |
620a324b JA |
414 | } |
415 | fill_it: | |
416 | /* | |
417 | * i_size must be checked after PageUptodate. | |
418 | */ | |
419 | isize = i_size_read(mapping->host); | |
420 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
421 | if (unlikely(!isize || index > end_index)) | |
422 | break; | |
423 | ||
424 | /* | |
425 | * if this is the last page, see if we need to shrink | |
426 | * the length and stop | |
427 | */ | |
428 | if (end_index == index) { | |
429 | unsigned int plen; | |
91ad66ef JA |
430 | |
431 | /* | |
620a324b | 432 | * max good bytes in this page |
91ad66ef | 433 | */ |
620a324b JA |
434 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
435 | if (plen <= loff) | |
91ad66ef | 436 | break; |
91ad66ef JA |
437 | |
438 | /* | |
620a324b | 439 | * force quit after adding this page |
91ad66ef | 440 | */ |
620a324b JA |
441 | this_len = min(this_len, plen - loff); |
442 | len = this_len; | |
5274f052 | 443 | } |
620a324b | 444 | |
eb20796b JA |
445 | partial[page_nr].offset = loff; |
446 | partial[page_nr].len = this_len; | |
82aa5d61 | 447 | len -= this_len; |
91ad66ef | 448 | loff = 0; |
eb20796b JA |
449 | spd.nr_pages++; |
450 | index++; | |
5274f052 JA |
451 | } |
452 | ||
eb20796b | 453 | /* |
475ecade | 454 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
eb20796b JA |
455 | * we got, 'nr_pages' is how many pages are in the map. |
456 | */ | |
457 | while (page_nr < nr_pages) | |
458 | page_cache_release(pages[page_nr++]); | |
f4e6b498 | 459 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
eb20796b | 460 | |
912d35f8 | 461 | if (spd.nr_pages) |
00522fb4 | 462 | return splice_to_pipe(pipe, &spd); |
5274f052 | 463 | |
7480a904 | 464 | return error; |
5274f052 JA |
465 | } |
466 | ||
83f9135b JA |
467 | /** |
468 | * generic_file_splice_read - splice data from file to a pipe | |
469 | * @in: file to splice from | |
932cc6d4 | 470 | * @ppos: position in @in |
83f9135b JA |
471 | * @pipe: pipe to splice to |
472 | * @len: number of bytes to splice | |
473 | * @flags: splice modifier flags | |
474 | * | |
932cc6d4 JA |
475 | * Description: |
476 | * Will read pages from given file and fill them into a pipe. Can be | |
477 | * used as long as the address_space operations for the source implements | |
478 | * a readpage() hook. | |
479 | * | |
83f9135b | 480 | */ |
cbb7e577 JA |
481 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
482 | struct pipe_inode_info *pipe, size_t len, | |
483 | unsigned int flags) | |
5274f052 | 484 | { |
d366d398 | 485 | loff_t isize, left; |
8191ecd1 | 486 | int ret; |
d366d398 JA |
487 | |
488 | isize = i_size_read(in->f_mapping->host); | |
489 | if (unlikely(*ppos >= isize)) | |
490 | return 0; | |
491 | ||
492 | left = isize - *ppos; | |
493 | if (unlikely(left < len)) | |
494 | len = left; | |
5274f052 | 495 | |
8191ecd1 JA |
496 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
497 | if (ret > 0) | |
cbb7e577 | 498 | *ppos += ret; |
5274f052 JA |
499 | |
500 | return ret; | |
501 | } | |
502 | ||
059a8f37 JA |
503 | EXPORT_SYMBOL(generic_file_splice_read); |
504 | ||
5274f052 | 505 | /* |
4f6f0bd2 | 506 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 507 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 508 | */ |
76ad4d11 | 509 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
510 | struct pipe_buffer *buf, struct splice_desc *sd) |
511 | { | |
6a14b90b | 512 | struct file *file = sd->u.file; |
5274f052 | 513 | loff_t pos = sd->pos; |
f84d7519 | 514 | int ret, more; |
5274f052 | 515 | |
cac36bb0 | 516 | ret = buf->ops->confirm(pipe, buf); |
f84d7519 JA |
517 | if (!ret) { |
518 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; | |
5274f052 | 519 | |
f84d7519 JA |
520 | ret = file->f_op->sendpage(file, buf->page, buf->offset, |
521 | sd->len, &pos, more); | |
522 | } | |
5274f052 | 523 | |
016b661e | 524 | return ret; |
5274f052 JA |
525 | } |
526 | ||
527 | /* | |
528 | * This is a little more tricky than the file -> pipe splicing. There are | |
529 | * basically three cases: | |
530 | * | |
531 | * - Destination page already exists in the address space and there | |
532 | * are users of it. For that case we have no other option that | |
533 | * copying the data. Tough luck. | |
534 | * - Destination page already exists in the address space, but there | |
535 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
536 | * through to last case. | |
537 | * - Destination page does not exist, we can add the pipe page to | |
538 | * the page cache and avoid the copy. | |
539 | * | |
83f9135b JA |
540 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
541 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
542 | * file address space page cache. This is possible if no one else has | |
543 | * the pipe page referenced outside of the pipe and page cache. If | |
544 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
545 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 | 546 | */ |
76ad4d11 | 547 | static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
5274f052 JA |
548 | struct splice_desc *sd) |
549 | { | |
6a14b90b | 550 | struct file *file = sd->u.file; |
5274f052 | 551 | struct address_space *mapping = file->f_mapping; |
016b661e | 552 | unsigned int offset, this_len; |
5274f052 | 553 | struct page *page; |
afddba49 | 554 | void *fsdata; |
3e7ee3e7 | 555 | int ret; |
5274f052 JA |
556 | |
557 | /* | |
49d0b21b | 558 | * make sure the data in this buffer is uptodate |
5274f052 | 559 | */ |
cac36bb0 | 560 | ret = buf->ops->confirm(pipe, buf); |
f84d7519 JA |
561 | if (unlikely(ret)) |
562 | return ret; | |
5274f052 | 563 | |
5274f052 JA |
564 | offset = sd->pos & ~PAGE_CACHE_MASK; |
565 | ||
016b661e JA |
566 | this_len = sd->len; |
567 | if (this_len + offset > PAGE_CACHE_SIZE) | |
568 | this_len = PAGE_CACHE_SIZE - offset; | |
569 | ||
afddba49 NP |
570 | ret = pagecache_write_begin(file, mapping, sd->pos, this_len, |
571 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); | |
572 | if (unlikely(ret)) | |
573 | goto out; | |
5274f052 | 574 | |
0568b409 | 575 | if (buf->page != page) { |
f84d7519 JA |
576 | /* |
577 | * Careful, ->map() uses KM_USER0! | |
578 | */ | |
76ad4d11 | 579 | char *src = buf->ops->map(pipe, buf, 1); |
f84d7519 | 580 | char *dst = kmap_atomic(page, KM_USER1); |
5abc97aa | 581 | |
016b661e | 582 | memcpy(dst + offset, src + buf->offset, this_len); |
5abc97aa | 583 | flush_dcache_page(page); |
f84d7519 | 584 | kunmap_atomic(dst, KM_USER1); |
76ad4d11 | 585 | buf->ops->unmap(pipe, buf, src); |
5abc97aa | 586 | } |
afddba49 NP |
587 | ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, |
588 | page, fsdata); | |
5274f052 | 589 | out: |
5274f052 JA |
590 | return ret; |
591 | } | |
592 | ||
932cc6d4 JA |
593 | /** |
594 | * __splice_from_pipe - splice data from a pipe to given actor | |
595 | * @pipe: pipe to splice from | |
596 | * @sd: information to @actor | |
597 | * @actor: handler that splices the data | |
598 | * | |
599 | * Description: | |
600 | * This function does little more than loop over the pipe and call | |
601 | * @actor to do the actual moving of a single struct pipe_buffer to | |
602 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
603 | * pipe_to_user. | |
604 | * | |
83f9135b | 605 | */ |
c66ab6fa JA |
606 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
607 | splice_actor *actor) | |
5274f052 | 608 | { |
5274f052 | 609 | int ret, do_wakeup, err; |
5274f052 JA |
610 | |
611 | ret = 0; | |
612 | do_wakeup = 0; | |
613 | ||
5274f052 | 614 | for (;;) { |
6f767b04 JA |
615 | if (pipe->nrbufs) { |
616 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
d4c3cca9 | 617 | const struct pipe_buf_operations *ops = buf->ops; |
5274f052 | 618 | |
c66ab6fa JA |
619 | sd->len = buf->len; |
620 | if (sd->len > sd->total_len) | |
621 | sd->len = sd->total_len; | |
5274f052 | 622 | |
c66ab6fa | 623 | err = actor(pipe, buf, sd); |
016b661e | 624 | if (err <= 0) { |
5274f052 JA |
625 | if (!ret && err != -ENODATA) |
626 | ret = err; | |
627 | ||
628 | break; | |
629 | } | |
630 | ||
016b661e JA |
631 | ret += err; |
632 | buf->offset += err; | |
633 | buf->len -= err; | |
634 | ||
c66ab6fa JA |
635 | sd->len -= err; |
636 | sd->pos += err; | |
637 | sd->total_len -= err; | |
638 | if (sd->len) | |
016b661e | 639 | continue; |
73d62d83 | 640 | |
5274f052 JA |
641 | if (!buf->len) { |
642 | buf->ops = NULL; | |
3a326a2c | 643 | ops->release(pipe, buf); |
6f767b04 JA |
644 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
645 | pipe->nrbufs--; | |
646 | if (pipe->inode) | |
647 | do_wakeup = 1; | |
5274f052 JA |
648 | } |
649 | ||
c66ab6fa | 650 | if (!sd->total_len) |
5274f052 JA |
651 | break; |
652 | } | |
653 | ||
6f767b04 | 654 | if (pipe->nrbufs) |
5274f052 | 655 | continue; |
3a326a2c | 656 | if (!pipe->writers) |
5274f052 | 657 | break; |
3a326a2c | 658 | if (!pipe->waiting_writers) { |
5274f052 JA |
659 | if (ret) |
660 | break; | |
661 | } | |
662 | ||
c66ab6fa | 663 | if (sd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
664 | if (!ret) |
665 | ret = -EAGAIN; | |
666 | break; | |
667 | } | |
668 | ||
5274f052 JA |
669 | if (signal_pending(current)) { |
670 | if (!ret) | |
671 | ret = -ERESTARTSYS; | |
672 | break; | |
673 | } | |
674 | ||
675 | if (do_wakeup) { | |
c0bd1f65 | 676 | smp_mb(); |
3a326a2c IM |
677 | if (waitqueue_active(&pipe->wait)) |
678 | wake_up_interruptible_sync(&pipe->wait); | |
679 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
680 | do_wakeup = 0; |
681 | } | |
682 | ||
3a326a2c | 683 | pipe_wait(pipe); |
5274f052 JA |
684 | } |
685 | ||
5274f052 | 686 | if (do_wakeup) { |
c0bd1f65 | 687 | smp_mb(); |
3a326a2c IM |
688 | if (waitqueue_active(&pipe->wait)) |
689 | wake_up_interruptible(&pipe->wait); | |
690 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
691 | } |
692 | ||
5274f052 | 693 | return ret; |
5274f052 | 694 | } |
40bee44e | 695 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 696 | |
932cc6d4 JA |
697 | /** |
698 | * splice_from_pipe - splice data from a pipe to a file | |
699 | * @pipe: pipe to splice from | |
700 | * @out: file to splice to | |
701 | * @ppos: position in @out | |
702 | * @len: how many bytes to splice | |
703 | * @flags: splice modifier flags | |
704 | * @actor: handler that splices the data | |
705 | * | |
706 | * Description: | |
707 | * See __splice_from_pipe. This function locks the input and output inodes, | |
708 | * otherwise it's identical to __splice_from_pipe(). | |
709 | * | |
710 | */ | |
6da61809 MF |
711 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
712 | loff_t *ppos, size_t len, unsigned int flags, | |
713 | splice_actor *actor) | |
714 | { | |
715 | ssize_t ret; | |
716 | struct inode *inode = out->f_mapping->host; | |
c66ab6fa JA |
717 | struct splice_desc sd = { |
718 | .total_len = len, | |
719 | .flags = flags, | |
720 | .pos = *ppos, | |
6a14b90b | 721 | .u.file = out, |
c66ab6fa | 722 | }; |
6da61809 MF |
723 | |
724 | /* | |
725 | * The actor worker might be calling ->prepare_write and | |
726 | * ->commit_write. Most of the time, these expect i_mutex to | |
727 | * be held. Since this may result in an ABBA deadlock with | |
728 | * pipe->inode, we have to order lock acquiry here. | |
729 | */ | |
730 | inode_double_lock(inode, pipe->inode); | |
c66ab6fa | 731 | ret = __splice_from_pipe(pipe, &sd, actor); |
6da61809 MF |
732 | inode_double_unlock(inode, pipe->inode); |
733 | ||
734 | return ret; | |
735 | } | |
736 | ||
737 | /** | |
738 | * generic_file_splice_write_nolock - generic_file_splice_write without mutexes | |
739 | * @pipe: pipe info | |
740 | * @out: file to write to | |
932cc6d4 | 741 | * @ppos: position in @out |
6da61809 MF |
742 | * @len: number of bytes to splice |
743 | * @flags: splice modifier flags | |
744 | * | |
932cc6d4 JA |
745 | * Description: |
746 | * Will either move or copy pages (determined by @flags options) from | |
747 | * the given pipe inode to the given file. The caller is responsible | |
748 | * for acquiring i_mutex on both inodes. | |
6da61809 MF |
749 | * |
750 | */ | |
751 | ssize_t | |
752 | generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out, | |
753 | loff_t *ppos, size_t len, unsigned int flags) | |
754 | { | |
755 | struct address_space *mapping = out->f_mapping; | |
756 | struct inode *inode = mapping->host; | |
c66ab6fa JA |
757 | struct splice_desc sd = { |
758 | .total_len = len, | |
759 | .flags = flags, | |
760 | .pos = *ppos, | |
6a14b90b | 761 | .u.file = out, |
c66ab6fa | 762 | }; |
6da61809 MF |
763 | ssize_t ret; |
764 | int err; | |
765 | ||
0f7fc9e4 | 766 | err = remove_suid(out->f_path.dentry); |
8c34e2d6 JA |
767 | if (unlikely(err)) |
768 | return err; | |
769 | ||
c66ab6fa | 770 | ret = __splice_from_pipe(pipe, &sd, pipe_to_file); |
6da61809 | 771 | if (ret > 0) { |
17ee4f49 JA |
772 | unsigned long nr_pages; |
773 | ||
6da61809 | 774 | *ppos += ret; |
17ee4f49 | 775 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
6da61809 MF |
776 | |
777 | /* | |
778 | * If file or inode is SYNC and we actually wrote some data, | |
779 | * sync it. | |
780 | */ | |
781 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
782 | err = generic_osync_inode(inode, mapping, | |
783 | OSYNC_METADATA|OSYNC_DATA); | |
784 | ||
785 | if (err) | |
786 | ret = err; | |
787 | } | |
17ee4f49 | 788 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
6da61809 MF |
789 | } |
790 | ||
791 | return ret; | |
792 | } | |
793 | ||
794 | EXPORT_SYMBOL(generic_file_splice_write_nolock); | |
795 | ||
83f9135b JA |
796 | /** |
797 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 798 | * @pipe: pipe info |
83f9135b | 799 | * @out: file to write to |
932cc6d4 | 800 | * @ppos: position in @out |
83f9135b JA |
801 | * @len: number of bytes to splice |
802 | * @flags: splice modifier flags | |
803 | * | |
932cc6d4 JA |
804 | * Description: |
805 | * Will either move or copy pages (determined by @flags options) from | |
806 | * the given pipe inode to the given file. | |
83f9135b JA |
807 | * |
808 | */ | |
3a326a2c IM |
809 | ssize_t |
810 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
cbb7e577 | 811 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 812 | { |
4f6f0bd2 | 813 | struct address_space *mapping = out->f_mapping; |
8c34e2d6 | 814 | struct inode *inode = mapping->host; |
7f3d4ee1 MS |
815 | struct splice_desc sd = { |
816 | .total_len = len, | |
817 | .flags = flags, | |
818 | .pos = *ppos, | |
819 | .u.file = out, | |
820 | }; | |
3a326a2c IM |
821 | ssize_t ret; |
822 | ||
7f3d4ee1 MS |
823 | inode_double_lock(inode, pipe->inode); |
824 | ret = remove_suid(out->f_path.dentry); | |
825 | if (likely(!ret)) | |
826 | ret = __splice_from_pipe(pipe, &sd, pipe_to_file); | |
827 | inode_double_unlock(inode, pipe->inode); | |
a4514ebd | 828 | if (ret > 0) { |
17ee4f49 JA |
829 | unsigned long nr_pages; |
830 | ||
a4514ebd | 831 | *ppos += ret; |
17ee4f49 | 832 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
a4514ebd JA |
833 | |
834 | /* | |
835 | * If file or inode is SYNC and we actually wrote some data, | |
836 | * sync it. | |
837 | */ | |
838 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
7f3d4ee1 MS |
839 | int err; |
840 | ||
a4514ebd JA |
841 | mutex_lock(&inode->i_mutex); |
842 | err = generic_osync_inode(inode, mapping, | |
843 | OSYNC_METADATA|OSYNC_DATA); | |
844 | mutex_unlock(&inode->i_mutex); | |
4f6f0bd2 | 845 | |
a4514ebd JA |
846 | if (err) |
847 | ret = err; | |
848 | } | |
17ee4f49 | 849 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
4f6f0bd2 JA |
850 | } |
851 | ||
852 | return ret; | |
5274f052 JA |
853 | } |
854 | ||
059a8f37 JA |
855 | EXPORT_SYMBOL(generic_file_splice_write); |
856 | ||
83f9135b JA |
857 | /** |
858 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 859 | * @pipe: pipe to splice from |
83f9135b | 860 | * @out: socket to write to |
932cc6d4 | 861 | * @ppos: position in @out |
83f9135b JA |
862 | * @len: number of bytes to splice |
863 | * @flags: splice modifier flags | |
864 | * | |
932cc6d4 JA |
865 | * Description: |
866 | * Will send @len bytes from the pipe to a network socket. No data copying | |
867 | * is involved. | |
83f9135b JA |
868 | * |
869 | */ | |
3a326a2c | 870 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 871 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 872 | { |
00522fb4 | 873 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
874 | } |
875 | ||
059a8f37 | 876 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 877 | |
83f9135b JA |
878 | /* |
879 | * Attempt to initiate a splice from pipe to file. | |
880 | */ | |
3a326a2c | 881 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 882 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 883 | { |
5274f052 JA |
884 | int ret; |
885 | ||
49570e9b | 886 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
887 | return -EINVAL; |
888 | ||
49570e9b | 889 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
890 | return -EBADF; |
891 | ||
cbb7e577 | 892 | ret = rw_verify_area(WRITE, out, ppos, len); |
5274f052 JA |
893 | if (unlikely(ret < 0)) |
894 | return ret; | |
895 | ||
cbb7e577 | 896 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
897 | } |
898 | ||
83f9135b JA |
899 | /* |
900 | * Attempt to initiate a splice from a file to a pipe. | |
901 | */ | |
cbb7e577 JA |
902 | static long do_splice_to(struct file *in, loff_t *ppos, |
903 | struct pipe_inode_info *pipe, size_t len, | |
904 | unsigned int flags) | |
5274f052 | 905 | { |
5274f052 JA |
906 | int ret; |
907 | ||
49570e9b | 908 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
909 | return -EINVAL; |
910 | ||
49570e9b | 911 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
912 | return -EBADF; |
913 | ||
cbb7e577 | 914 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
915 | if (unlikely(ret < 0)) |
916 | return ret; | |
917 | ||
cbb7e577 | 918 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 JA |
919 | } |
920 | ||
932cc6d4 JA |
921 | /** |
922 | * splice_direct_to_actor - splices data directly between two non-pipes | |
923 | * @in: file to splice from | |
924 | * @sd: actor information on where to splice to | |
925 | * @actor: handles the data splicing | |
926 | * | |
927 | * Description: | |
928 | * This is a special case helper to splice directly between two | |
929 | * points, without requiring an explicit pipe. Internally an allocated | |
79685b8d | 930 | * pipe is cached in the process, and reused during the lifetime of |
932cc6d4 JA |
931 | * that process. |
932 | * | |
c66ab6fa JA |
933 | */ |
934 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
935 | splice_direct_actor *actor) | |
b92ce558 JA |
936 | { |
937 | struct pipe_inode_info *pipe; | |
938 | long ret, bytes; | |
939 | umode_t i_mode; | |
c66ab6fa JA |
940 | size_t len; |
941 | int i, flags; | |
b92ce558 JA |
942 | |
943 | /* | |
944 | * We require the input being a regular file, as we don't want to | |
945 | * randomly drop data for eg socket -> socket splicing. Use the | |
946 | * piped splicing for that! | |
947 | */ | |
0f7fc9e4 | 948 | i_mode = in->f_path.dentry->d_inode->i_mode; |
b92ce558 JA |
949 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
950 | return -EINVAL; | |
951 | ||
952 | /* | |
953 | * neither in nor out is a pipe, setup an internal pipe attached to | |
954 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
955 | */ | |
956 | pipe = current->splice_pipe; | |
49570e9b | 957 | if (unlikely(!pipe)) { |
b92ce558 JA |
958 | pipe = alloc_pipe_info(NULL); |
959 | if (!pipe) | |
960 | return -ENOMEM; | |
961 | ||
962 | /* | |
963 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 964 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
965 | * PIPE_READERS appropriately. |
966 | */ | |
967 | pipe->readers = 1; | |
968 | ||
969 | current->splice_pipe = pipe; | |
970 | } | |
971 | ||
972 | /* | |
73d62d83 | 973 | * Do the splice. |
b92ce558 JA |
974 | */ |
975 | ret = 0; | |
976 | bytes = 0; | |
c66ab6fa JA |
977 | len = sd->total_len; |
978 | flags = sd->flags; | |
979 | ||
980 | /* | |
981 | * Don't block on output, we have to drain the direct pipe. | |
982 | */ | |
983 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
b92ce558 JA |
984 | |
985 | while (len) { | |
51a92c0f | 986 | size_t read_len; |
a82c53a0 | 987 | loff_t pos = sd->pos, prev_pos = pos; |
b92ce558 | 988 | |
bcd4f3ac | 989 | ret = do_splice_to(in, &pos, pipe, len, flags); |
51a92c0f | 990 | if (unlikely(ret <= 0)) |
b92ce558 JA |
991 | goto out_release; |
992 | ||
993 | read_len = ret; | |
c66ab6fa | 994 | sd->total_len = read_len; |
b92ce558 JA |
995 | |
996 | /* | |
997 | * NOTE: nonblocking mode only applies to the input. We | |
998 | * must not do the output in nonblocking mode as then we | |
999 | * could get stuck data in the internal pipe: | |
1000 | */ | |
c66ab6fa | 1001 | ret = actor(pipe, sd); |
a82c53a0 TZ |
1002 | if (unlikely(ret <= 0)) { |
1003 | sd->pos = prev_pos; | |
b92ce558 | 1004 | goto out_release; |
a82c53a0 | 1005 | } |
b92ce558 JA |
1006 | |
1007 | bytes += ret; | |
1008 | len -= ret; | |
bcd4f3ac | 1009 | sd->pos = pos; |
b92ce558 | 1010 | |
a82c53a0 TZ |
1011 | if (ret < read_len) { |
1012 | sd->pos = prev_pos + ret; | |
51a92c0f | 1013 | goto out_release; |
a82c53a0 | 1014 | } |
b92ce558 JA |
1015 | } |
1016 | ||
9e97198d | 1017 | done: |
b92ce558 | 1018 | pipe->nrbufs = pipe->curbuf = 0; |
80848708 | 1019 | file_accessed(in); |
b92ce558 JA |
1020 | return bytes; |
1021 | ||
1022 | out_release: | |
1023 | /* | |
1024 | * If we did an incomplete transfer we must release | |
1025 | * the pipe buffers in question: | |
1026 | */ | |
1027 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
1028 | struct pipe_buffer *buf = pipe->bufs + i; | |
1029 | ||
1030 | if (buf->ops) { | |
1031 | buf->ops->release(pipe, buf); | |
1032 | buf->ops = NULL; | |
1033 | } | |
1034 | } | |
b92ce558 | 1035 | |
9e97198d JA |
1036 | if (!bytes) |
1037 | bytes = ret; | |
c66ab6fa | 1038 | |
9e97198d | 1039 | goto done; |
c66ab6fa JA |
1040 | } |
1041 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1042 | ||
1043 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1044 | struct splice_desc *sd) | |
1045 | { | |
6a14b90b | 1046 | struct file *file = sd->u.file; |
c66ab6fa JA |
1047 | |
1048 | return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags); | |
1049 | } | |
1050 | ||
932cc6d4 JA |
1051 | /** |
1052 | * do_splice_direct - splices data directly between two files | |
1053 | * @in: file to splice from | |
1054 | * @ppos: input file offset | |
1055 | * @out: file to splice to | |
1056 | * @len: number of bytes to splice | |
1057 | * @flags: splice modifier flags | |
1058 | * | |
1059 | * Description: | |
1060 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1061 | * doing it in the application would incur an extra system call | |
1062 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1063 | * can splice directly through a process-private pipe. | |
1064 | * | |
1065 | */ | |
c66ab6fa JA |
1066 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1067 | size_t len, unsigned int flags) | |
1068 | { | |
1069 | struct splice_desc sd = { | |
1070 | .len = len, | |
1071 | .total_len = len, | |
1072 | .flags = flags, | |
1073 | .pos = *ppos, | |
6a14b90b | 1074 | .u.file = out, |
c66ab6fa | 1075 | }; |
51a92c0f | 1076 | long ret; |
c66ab6fa JA |
1077 | |
1078 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); | |
51a92c0f | 1079 | if (ret > 0) |
a82c53a0 | 1080 | *ppos = sd.pos; |
51a92c0f | 1081 | |
c66ab6fa | 1082 | return ret; |
b92ce558 JA |
1083 | } |
1084 | ||
ddac0d39 JA |
1085 | /* |
1086 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same | |
1087 | * location, so checking ->i_pipe is not enough to verify that this is a | |
1088 | * pipe. | |
1089 | */ | |
1090 | static inline struct pipe_inode_info *pipe_info(struct inode *inode) | |
1091 | { | |
1092 | if (S_ISFIFO(inode->i_mode)) | |
1093 | return inode->i_pipe; | |
1094 | ||
1095 | return NULL; | |
1096 | } | |
1097 | ||
83f9135b JA |
1098 | /* |
1099 | * Determine where to splice to/from. | |
1100 | */ | |
529565dc IM |
1101 | static long do_splice(struct file *in, loff_t __user *off_in, |
1102 | struct file *out, loff_t __user *off_out, | |
1103 | size_t len, unsigned int flags) | |
5274f052 | 1104 | { |
3a326a2c | 1105 | struct pipe_inode_info *pipe; |
cbb7e577 | 1106 | loff_t offset, *off; |
a4514ebd | 1107 | long ret; |
5274f052 | 1108 | |
0f7fc9e4 | 1109 | pipe = pipe_info(in->f_path.dentry->d_inode); |
529565dc IM |
1110 | if (pipe) { |
1111 | if (off_in) | |
1112 | return -ESPIPE; | |
b92ce558 JA |
1113 | if (off_out) { |
1114 | if (out->f_op->llseek == no_llseek) | |
1115 | return -EINVAL; | |
cbb7e577 | 1116 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1117 | return -EFAULT; |
cbb7e577 JA |
1118 | off = &offset; |
1119 | } else | |
1120 | off = &out->f_pos; | |
529565dc | 1121 | |
a4514ebd JA |
1122 | ret = do_splice_from(pipe, out, off, len, flags); |
1123 | ||
1124 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
1125 | ret = -EFAULT; | |
1126 | ||
1127 | return ret; | |
529565dc | 1128 | } |
5274f052 | 1129 | |
0f7fc9e4 | 1130 | pipe = pipe_info(out->f_path.dentry->d_inode); |
529565dc IM |
1131 | if (pipe) { |
1132 | if (off_out) | |
1133 | return -ESPIPE; | |
b92ce558 JA |
1134 | if (off_in) { |
1135 | if (in->f_op->llseek == no_llseek) | |
1136 | return -EINVAL; | |
cbb7e577 | 1137 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1138 | return -EFAULT; |
cbb7e577 JA |
1139 | off = &offset; |
1140 | } else | |
1141 | off = &in->f_pos; | |
529565dc | 1142 | |
a4514ebd JA |
1143 | ret = do_splice_to(in, off, pipe, len, flags); |
1144 | ||
1145 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
1146 | ret = -EFAULT; | |
1147 | ||
1148 | return ret; | |
529565dc | 1149 | } |
5274f052 JA |
1150 | |
1151 | return -EINVAL; | |
1152 | } | |
1153 | ||
75723957 LT |
1154 | /* |
1155 | * Do a copy-from-user while holding the mmap_semaphore for reading, in a | |
1156 | * manner safe from deadlocking with simultaneous mmap() (grabbing mmap_sem | |
1157 | * for writing) and page faulting on the user memory pointed to by src. | |
1158 | * This assumes that we will very rarely hit the partial != 0 path, or this | |
1159 | * will not be a win. | |
1160 | */ | |
1161 | static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n) | |
1162 | { | |
1163 | int partial; | |
1164 | ||
8811930d JA |
1165 | if (!access_ok(VERIFY_READ, src, n)) |
1166 | return -EFAULT; | |
1167 | ||
75723957 LT |
1168 | pagefault_disable(); |
1169 | partial = __copy_from_user_inatomic(dst, src, n); | |
1170 | pagefault_enable(); | |
1171 | ||
1172 | /* | |
1173 | * Didn't copy everything, drop the mmap_sem and do a faulting copy | |
1174 | */ | |
1175 | if (unlikely(partial)) { | |
1176 | up_read(¤t->mm->mmap_sem); | |
1177 | partial = copy_from_user(dst, src, n); | |
1178 | down_read(¤t->mm->mmap_sem); | |
1179 | } | |
1180 | ||
1181 | return partial; | |
1182 | } | |
1183 | ||
912d35f8 JA |
1184 | /* |
1185 | * Map an iov into an array of pages and offset/length tupples. With the | |
1186 | * partial_page structure, we can map several non-contiguous ranges into | |
1187 | * our ones pages[] map instead of splitting that operation into pieces. | |
1188 | * Could easily be exported as a generic helper for other users, in which | |
1189 | * case one would probably want to add a 'max_nr_pages' parameter as well. | |
1190 | */ | |
1191 | static int get_iovec_page_array(const struct iovec __user *iov, | |
1192 | unsigned int nr_vecs, struct page **pages, | |
7afa6fd0 | 1193 | struct partial_page *partial, int aligned) |
912d35f8 JA |
1194 | { |
1195 | int buffers = 0, error = 0; | |
1196 | ||
912d35f8 JA |
1197 | down_read(¤t->mm->mmap_sem); |
1198 | ||
1199 | while (nr_vecs) { | |
1200 | unsigned long off, npages; | |
75723957 | 1201 | struct iovec entry; |
912d35f8 JA |
1202 | void __user *base; |
1203 | size_t len; | |
1204 | int i; | |
1205 | ||
75723957 LT |
1206 | error = -EFAULT; |
1207 | if (copy_from_user_mmap_sem(&entry, iov, sizeof(entry))) | |
912d35f8 JA |
1208 | break; |
1209 | ||
75723957 LT |
1210 | base = entry.iov_base; |
1211 | len = entry.iov_len; | |
1212 | ||
912d35f8 JA |
1213 | /* |
1214 | * Sanity check this iovec. 0 read succeeds. | |
1215 | */ | |
75723957 | 1216 | error = 0; |
912d35f8 JA |
1217 | if (unlikely(!len)) |
1218 | break; | |
1219 | error = -EFAULT; | |
712a30e6 | 1220 | if (!access_ok(VERIFY_READ, base, len)) |
912d35f8 JA |
1221 | break; |
1222 | ||
1223 | /* | |
1224 | * Get this base offset and number of pages, then map | |
1225 | * in the user pages. | |
1226 | */ | |
1227 | off = (unsigned long) base & ~PAGE_MASK; | |
7afa6fd0 JA |
1228 | |
1229 | /* | |
1230 | * If asked for alignment, the offset must be zero and the | |
1231 | * length a multiple of the PAGE_SIZE. | |
1232 | */ | |
1233 | error = -EINVAL; | |
1234 | if (aligned && (off || len & ~PAGE_MASK)) | |
1235 | break; | |
1236 | ||
912d35f8 JA |
1237 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1238 | if (npages > PIPE_BUFFERS - buffers) | |
1239 | npages = PIPE_BUFFERS - buffers; | |
1240 | ||
1241 | error = get_user_pages(current, current->mm, | |
1242 | (unsigned long) base, npages, 0, 0, | |
1243 | &pages[buffers], NULL); | |
1244 | ||
1245 | if (unlikely(error <= 0)) | |
1246 | break; | |
1247 | ||
1248 | /* | |
1249 | * Fill this contiguous range into the partial page map. | |
1250 | */ | |
1251 | for (i = 0; i < error; i++) { | |
7591489a | 1252 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
912d35f8 JA |
1253 | |
1254 | partial[buffers].offset = off; | |
1255 | partial[buffers].len = plen; | |
1256 | ||
1257 | off = 0; | |
1258 | len -= plen; | |
1259 | buffers++; | |
1260 | } | |
1261 | ||
1262 | /* | |
1263 | * We didn't complete this iov, stop here since it probably | |
1264 | * means we have to move some of this into a pipe to | |
1265 | * be able to continue. | |
1266 | */ | |
1267 | if (len) | |
1268 | break; | |
1269 | ||
1270 | /* | |
1271 | * Don't continue if we mapped fewer pages than we asked for, | |
1272 | * or if we mapped the max number of pages that we have | |
1273 | * room for. | |
1274 | */ | |
1275 | if (error < npages || buffers == PIPE_BUFFERS) | |
1276 | break; | |
1277 | ||
1278 | nr_vecs--; | |
1279 | iov++; | |
1280 | } | |
1281 | ||
1282 | up_read(¤t->mm->mmap_sem); | |
1283 | ||
1284 | if (buffers) | |
1285 | return buffers; | |
1286 | ||
1287 | return error; | |
1288 | } | |
1289 | ||
6a14b90b JA |
1290 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1291 | struct splice_desc *sd) | |
1292 | { | |
1293 | char *src; | |
1294 | int ret; | |
1295 | ||
cac36bb0 | 1296 | ret = buf->ops->confirm(pipe, buf); |
6a14b90b JA |
1297 | if (unlikely(ret)) |
1298 | return ret; | |
1299 | ||
1300 | /* | |
1301 | * See if we can use the atomic maps, by prefaulting in the | |
1302 | * pages and doing an atomic copy | |
1303 | */ | |
1304 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { | |
1305 | src = buf->ops->map(pipe, buf, 1); | |
1306 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, | |
1307 | sd->len); | |
1308 | buf->ops->unmap(pipe, buf, src); | |
1309 | if (!ret) { | |
1310 | ret = sd->len; | |
1311 | goto out; | |
1312 | } | |
1313 | } | |
1314 | ||
1315 | /* | |
1316 | * No dice, use slow non-atomic map and copy | |
1317 | */ | |
1318 | src = buf->ops->map(pipe, buf, 0); | |
1319 | ||
1320 | ret = sd->len; | |
1321 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) | |
1322 | ret = -EFAULT; | |
1323 | ||
6866bef4 | 1324 | buf->ops->unmap(pipe, buf, src); |
6a14b90b JA |
1325 | out: |
1326 | if (ret > 0) | |
1327 | sd->u.userptr += ret; | |
6a14b90b JA |
1328 | return ret; |
1329 | } | |
1330 | ||
1331 | /* | |
1332 | * For lack of a better implementation, implement vmsplice() to userspace | |
1333 | * as a simple copy of the pipes pages to the user iov. | |
1334 | */ | |
1335 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, | |
1336 | unsigned long nr_segs, unsigned int flags) | |
1337 | { | |
1338 | struct pipe_inode_info *pipe; | |
1339 | struct splice_desc sd; | |
1340 | ssize_t size; | |
1341 | int error; | |
1342 | long ret; | |
1343 | ||
1344 | pipe = pipe_info(file->f_path.dentry->d_inode); | |
1345 | if (!pipe) | |
1346 | return -EBADF; | |
1347 | ||
1348 | if (pipe->inode) | |
1349 | mutex_lock(&pipe->inode->i_mutex); | |
1350 | ||
1351 | error = ret = 0; | |
1352 | while (nr_segs) { | |
1353 | void __user *base; | |
1354 | size_t len; | |
1355 | ||
1356 | /* | |
1357 | * Get user address base and length for this iovec. | |
1358 | */ | |
1359 | error = get_user(base, &iov->iov_base); | |
1360 | if (unlikely(error)) | |
1361 | break; | |
1362 | error = get_user(len, &iov->iov_len); | |
1363 | if (unlikely(error)) | |
1364 | break; | |
1365 | ||
1366 | /* | |
1367 | * Sanity check this iovec. 0 read succeeds. | |
1368 | */ | |
1369 | if (unlikely(!len)) | |
1370 | break; | |
1371 | if (unlikely(!base)) { | |
1372 | error = -EFAULT; | |
1373 | break; | |
1374 | } | |
1375 | ||
8811930d JA |
1376 | if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { |
1377 | error = -EFAULT; | |
1378 | break; | |
1379 | } | |
1380 | ||
6a14b90b JA |
1381 | sd.len = 0; |
1382 | sd.total_len = len; | |
1383 | sd.flags = flags; | |
1384 | sd.u.userptr = base; | |
1385 | sd.pos = 0; | |
1386 | ||
1387 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1388 | if (size < 0) { | |
1389 | if (!ret) | |
1390 | ret = size; | |
1391 | ||
1392 | break; | |
1393 | } | |
1394 | ||
1395 | ret += size; | |
1396 | ||
1397 | if (size < len) | |
1398 | break; | |
1399 | ||
1400 | nr_segs--; | |
1401 | iov++; | |
1402 | } | |
1403 | ||
1404 | if (pipe->inode) | |
1405 | mutex_unlock(&pipe->inode->i_mutex); | |
1406 | ||
1407 | if (!ret) | |
1408 | ret = error; | |
1409 | ||
1410 | return ret; | |
1411 | } | |
1412 | ||
912d35f8 JA |
1413 | /* |
1414 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1415 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1416 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1417 | */ |
6a14b90b JA |
1418 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1419 | unsigned long nr_segs, unsigned int flags) | |
912d35f8 | 1420 | { |
ddac0d39 | 1421 | struct pipe_inode_info *pipe; |
912d35f8 JA |
1422 | struct page *pages[PIPE_BUFFERS]; |
1423 | struct partial_page partial[PIPE_BUFFERS]; | |
1424 | struct splice_pipe_desc spd = { | |
1425 | .pages = pages, | |
1426 | .partial = partial, | |
1427 | .flags = flags, | |
1428 | .ops = &user_page_pipe_buf_ops, | |
bbdfc2f7 | 1429 | .spd_release = spd_release_page, |
912d35f8 JA |
1430 | }; |
1431 | ||
0f7fc9e4 | 1432 | pipe = pipe_info(file->f_path.dentry->d_inode); |
ddac0d39 | 1433 | if (!pipe) |
912d35f8 | 1434 | return -EBADF; |
912d35f8 | 1435 | |
7afa6fd0 JA |
1436 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial, |
1437 | flags & SPLICE_F_GIFT); | |
912d35f8 JA |
1438 | if (spd.nr_pages <= 0) |
1439 | return spd.nr_pages; | |
1440 | ||
00522fb4 | 1441 | return splice_to_pipe(pipe, &spd); |
912d35f8 JA |
1442 | } |
1443 | ||
6a14b90b JA |
1444 | /* |
1445 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1446 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1447 | * operation that can be supported without any funky alignment restrictions | |
1448 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1449 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1450 | * solutions for that: | |
1451 | * | |
1452 | * - memcpy() the data internally, at which point we might as well just | |
1453 | * do a regular read() on the buffer anyway. | |
1454 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1455 | * has restriction limitations on both ends of the pipe). | |
1456 | * | |
1457 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1458 | * | |
1459 | */ | |
912d35f8 JA |
1460 | asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov, |
1461 | unsigned long nr_segs, unsigned int flags) | |
1462 | { | |
1463 | struct file *file; | |
1464 | long error; | |
1465 | int fput; | |
1466 | ||
6a14b90b JA |
1467 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1468 | return -EINVAL; | |
1469 | else if (unlikely(!nr_segs)) | |
1470 | return 0; | |
1471 | ||
912d35f8 JA |
1472 | error = -EBADF; |
1473 | file = fget_light(fd, &fput); | |
1474 | if (file) { | |
1475 | if (file->f_mode & FMODE_WRITE) | |
6a14b90b JA |
1476 | error = vmsplice_to_pipe(file, iov, nr_segs, flags); |
1477 | else if (file->f_mode & FMODE_READ) | |
1478 | error = vmsplice_to_user(file, iov, nr_segs, flags); | |
912d35f8 JA |
1479 | |
1480 | fput_light(file, fput); | |
1481 | } | |
1482 | ||
1483 | return error; | |
1484 | } | |
1485 | ||
529565dc IM |
1486 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
1487 | int fd_out, loff_t __user *off_out, | |
1488 | size_t len, unsigned int flags) | |
5274f052 JA |
1489 | { |
1490 | long error; | |
1491 | struct file *in, *out; | |
1492 | int fput_in, fput_out; | |
1493 | ||
1494 | if (unlikely(!len)) | |
1495 | return 0; | |
1496 | ||
1497 | error = -EBADF; | |
529565dc | 1498 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
1499 | if (in) { |
1500 | if (in->f_mode & FMODE_READ) { | |
529565dc | 1501 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
1502 | if (out) { |
1503 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
1504 | error = do_splice(in, off_in, |
1505 | out, off_out, | |
1506 | len, flags); | |
5274f052 JA |
1507 | fput_light(out, fput_out); |
1508 | } | |
1509 | } | |
1510 | ||
1511 | fput_light(in, fput_in); | |
1512 | } | |
1513 | ||
1514 | return error; | |
1515 | } | |
70524490 | 1516 | |
aadd06e5 JA |
1517 | /* |
1518 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1519 | * return an appropriate error. | |
1520 | */ | |
1521 | static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1522 | { | |
1523 | int ret; | |
1524 | ||
1525 | /* | |
1526 | * Check ->nrbufs without the inode lock first. This function | |
1527 | * is speculative anyways, so missing one is ok. | |
1528 | */ | |
1529 | if (pipe->nrbufs) | |
1530 | return 0; | |
1531 | ||
1532 | ret = 0; | |
1533 | mutex_lock(&pipe->inode->i_mutex); | |
1534 | ||
1535 | while (!pipe->nrbufs) { | |
1536 | if (signal_pending(current)) { | |
1537 | ret = -ERESTARTSYS; | |
1538 | break; | |
1539 | } | |
1540 | if (!pipe->writers) | |
1541 | break; | |
1542 | if (!pipe->waiting_writers) { | |
1543 | if (flags & SPLICE_F_NONBLOCK) { | |
1544 | ret = -EAGAIN; | |
1545 | break; | |
1546 | } | |
1547 | } | |
1548 | pipe_wait(pipe); | |
1549 | } | |
1550 | ||
1551 | mutex_unlock(&pipe->inode->i_mutex); | |
1552 | return ret; | |
1553 | } | |
1554 | ||
1555 | /* | |
1556 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1557 | * return an appropriate error. | |
1558 | */ | |
1559 | static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1560 | { | |
1561 | int ret; | |
1562 | ||
1563 | /* | |
1564 | * Check ->nrbufs without the inode lock first. This function | |
1565 | * is speculative anyways, so missing one is ok. | |
1566 | */ | |
1567 | if (pipe->nrbufs < PIPE_BUFFERS) | |
1568 | return 0; | |
1569 | ||
1570 | ret = 0; | |
1571 | mutex_lock(&pipe->inode->i_mutex); | |
1572 | ||
1573 | while (pipe->nrbufs >= PIPE_BUFFERS) { | |
1574 | if (!pipe->readers) { | |
1575 | send_sig(SIGPIPE, current, 0); | |
1576 | ret = -EPIPE; | |
1577 | break; | |
1578 | } | |
1579 | if (flags & SPLICE_F_NONBLOCK) { | |
1580 | ret = -EAGAIN; | |
1581 | break; | |
1582 | } | |
1583 | if (signal_pending(current)) { | |
1584 | ret = -ERESTARTSYS; | |
1585 | break; | |
1586 | } | |
1587 | pipe->waiting_writers++; | |
1588 | pipe_wait(pipe); | |
1589 | pipe->waiting_writers--; | |
1590 | } | |
1591 | ||
1592 | mutex_unlock(&pipe->inode->i_mutex); | |
1593 | return ret; | |
1594 | } | |
1595 | ||
70524490 JA |
1596 | /* |
1597 | * Link contents of ipipe to opipe. | |
1598 | */ | |
1599 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1600 | struct pipe_inode_info *opipe, | |
1601 | size_t len, unsigned int flags) | |
1602 | { | |
1603 | struct pipe_buffer *ibuf, *obuf; | |
aadd06e5 | 1604 | int ret = 0, i = 0, nbuf; |
70524490 JA |
1605 | |
1606 | /* | |
1607 | * Potential ABBA deadlock, work around it by ordering lock | |
1608 | * grabbing by inode address. Otherwise two different processes | |
1609 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1610 | */ | |
62752ee1 | 1611 | inode_double_lock(ipipe->inode, opipe->inode); |
70524490 | 1612 | |
aadd06e5 | 1613 | do { |
70524490 JA |
1614 | if (!opipe->readers) { |
1615 | send_sig(SIGPIPE, current, 0); | |
1616 | if (!ret) | |
1617 | ret = -EPIPE; | |
1618 | break; | |
1619 | } | |
70524490 | 1620 | |
aadd06e5 JA |
1621 | /* |
1622 | * If we have iterated all input buffers or ran out of | |
1623 | * output room, break. | |
1624 | */ | |
1625 | if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) | |
1626 | break; | |
70524490 | 1627 | |
aadd06e5 JA |
1628 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); |
1629 | nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); | |
70524490 JA |
1630 | |
1631 | /* | |
aadd06e5 JA |
1632 | * Get a reference to this pipe buffer, |
1633 | * so we can copy the contents over. | |
70524490 | 1634 | */ |
aadd06e5 JA |
1635 | ibuf->ops->get(ipipe, ibuf); |
1636 | ||
1637 | obuf = opipe->bufs + nbuf; | |
1638 | *obuf = *ibuf; | |
1639 | ||
2a27250e | 1640 | /* |
aadd06e5 JA |
1641 | * Don't inherit the gift flag, we need to |
1642 | * prevent multiple steals of this page. | |
2a27250e | 1643 | */ |
aadd06e5 | 1644 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
70524490 | 1645 | |
aadd06e5 JA |
1646 | if (obuf->len > len) |
1647 | obuf->len = len; | |
70524490 | 1648 | |
aadd06e5 JA |
1649 | opipe->nrbufs++; |
1650 | ret += obuf->len; | |
1651 | len -= obuf->len; | |
1652 | i++; | |
1653 | } while (len); | |
70524490 | 1654 | |
02cf01ae JA |
1655 | /* |
1656 | * return EAGAIN if we have the potential of some data in the | |
1657 | * future, otherwise just return 0 | |
1658 | */ | |
1659 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
1660 | ret = -EAGAIN; | |
1661 | ||
62752ee1 | 1662 | inode_double_unlock(ipipe->inode, opipe->inode); |
70524490 | 1663 | |
aadd06e5 JA |
1664 | /* |
1665 | * If we put data in the output pipe, wakeup any potential readers. | |
1666 | */ | |
1667 | if (ret > 0) { | |
70524490 JA |
1668 | smp_mb(); |
1669 | if (waitqueue_active(&opipe->wait)) | |
1670 | wake_up_interruptible(&opipe->wait); | |
1671 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1672 | } | |
1673 | ||
1674 | return ret; | |
1675 | } | |
1676 | ||
1677 | /* | |
1678 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1679 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1680 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1681 | * applicable one is SPLICE_F_NONBLOCK. | |
1682 | */ | |
1683 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1684 | unsigned int flags) | |
1685 | { | |
0f7fc9e4 JJS |
1686 | struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode); |
1687 | struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode); | |
aadd06e5 | 1688 | int ret = -EINVAL; |
70524490 JA |
1689 | |
1690 | /* | |
aadd06e5 JA |
1691 | * Duplicate the contents of ipipe to opipe without actually |
1692 | * copying the data. | |
70524490 | 1693 | */ |
aadd06e5 JA |
1694 | if (ipipe && opipe && ipipe != opipe) { |
1695 | /* | |
1696 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1697 | * ordering doesn't really matter. | |
1698 | */ | |
1699 | ret = link_ipipe_prep(ipipe, flags); | |
1700 | if (!ret) { | |
1701 | ret = link_opipe_prep(opipe, flags); | |
02cf01ae | 1702 | if (!ret) |
aadd06e5 | 1703 | ret = link_pipe(ipipe, opipe, len, flags); |
aadd06e5 JA |
1704 | } |
1705 | } | |
70524490 | 1706 | |
aadd06e5 | 1707 | return ret; |
70524490 JA |
1708 | } |
1709 | ||
1710 | asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) | |
1711 | { | |
1712 | struct file *in; | |
1713 | int error, fput_in; | |
1714 | ||
1715 | if (unlikely(!len)) | |
1716 | return 0; | |
1717 | ||
1718 | error = -EBADF; | |
1719 | in = fget_light(fdin, &fput_in); | |
1720 | if (in) { | |
1721 | if (in->f_mode & FMODE_READ) { | |
1722 | int fput_out; | |
1723 | struct file *out = fget_light(fdout, &fput_out); | |
1724 | ||
1725 | if (out) { | |
1726 | if (out->f_mode & FMODE_WRITE) | |
1727 | error = do_tee(in, out, len, flags); | |
1728 | fput_light(out, fput_out); | |
1729 | } | |
1730 | } | |
1731 | fput_light(in, fput_in); | |
1732 | } | |
1733 | ||
1734 | return error; | |
1735 | } |