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 | |
9e94cd4f | 61 | if (PagePrivate(page)) |
2ae88149 | 62 | try_to_release_page(page, GFP_KERNEL); |
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 | */ | |
78 | unlock_page(page); | |
79 | return 1; | |
5abc97aa JA |
80 | } |
81 | ||
76ad4d11 | 82 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
5274f052 JA |
83 | struct pipe_buffer *buf) |
84 | { | |
85 | page_cache_release(buf->page); | |
1432873a | 86 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
87 | } |
88 | ||
0845718d JA |
89 | /* |
90 | * Check whether the contents of buf is OK to access. Since the content | |
91 | * is a page cache page, IO may be in flight. | |
92 | */ | |
cac36bb0 JA |
93 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
94 | struct pipe_buffer *buf) | |
5274f052 JA |
95 | { |
96 | struct page *page = buf->page; | |
49d0b21b | 97 | int err; |
5274f052 JA |
98 | |
99 | if (!PageUptodate(page)) { | |
49d0b21b JA |
100 | lock_page(page); |
101 | ||
102 | /* | |
103 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 104 | * splice, if this is the first page. |
49d0b21b JA |
105 | */ |
106 | if (!page->mapping) { | |
107 | err = -ENODATA; | |
108 | goto error; | |
109 | } | |
5274f052 | 110 | |
49d0b21b | 111 | /* |
73d62d83 | 112 | * Uh oh, read-error from disk. |
49d0b21b JA |
113 | */ |
114 | if (!PageUptodate(page)) { | |
115 | err = -EIO; | |
116 | goto error; | |
117 | } | |
118 | ||
119 | /* | |
f84d7519 | 120 | * Page is ok afterall, we are done. |
49d0b21b | 121 | */ |
5274f052 | 122 | unlock_page(page); |
5274f052 JA |
123 | } |
124 | ||
f84d7519 | 125 | return 0; |
49d0b21b JA |
126 | error: |
127 | unlock_page(page); | |
f84d7519 | 128 | return err; |
70524490 JA |
129 | } |
130 | ||
d4c3cca9 | 131 | static const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
5274f052 | 132 | .can_merge = 0, |
f84d7519 JA |
133 | .map = generic_pipe_buf_map, |
134 | .unmap = generic_pipe_buf_unmap, | |
cac36bb0 | 135 | .confirm = page_cache_pipe_buf_confirm, |
5274f052 | 136 | .release = page_cache_pipe_buf_release, |
5abc97aa | 137 | .steal = page_cache_pipe_buf_steal, |
f84d7519 | 138 | .get = generic_pipe_buf_get, |
5274f052 JA |
139 | }; |
140 | ||
912d35f8 JA |
141 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
142 | struct pipe_buffer *buf) | |
143 | { | |
7afa6fd0 JA |
144 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
145 | return 1; | |
146 | ||
1432873a | 147 | buf->flags |= PIPE_BUF_FLAG_LRU; |
330ab716 | 148 | return generic_pipe_buf_steal(pipe, buf); |
912d35f8 JA |
149 | } |
150 | ||
d4c3cca9 | 151 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
912d35f8 | 152 | .can_merge = 0, |
f84d7519 JA |
153 | .map = generic_pipe_buf_map, |
154 | .unmap = generic_pipe_buf_unmap, | |
cac36bb0 | 155 | .confirm = generic_pipe_buf_confirm, |
912d35f8 JA |
156 | .release = page_cache_pipe_buf_release, |
157 | .steal = user_page_pipe_buf_steal, | |
f84d7519 | 158 | .get = generic_pipe_buf_get, |
912d35f8 JA |
159 | }; |
160 | ||
932cc6d4 JA |
161 | /** |
162 | * splice_to_pipe - fill passed data into a pipe | |
163 | * @pipe: pipe to fill | |
164 | * @spd: data to fill | |
165 | * | |
166 | * Description: | |
79685b8d | 167 | * @spd contains a map of pages and len/offset tuples, along with |
932cc6d4 JA |
168 | * the struct pipe_buf_operations associated with these pages. This |
169 | * function will link that data to the pipe. | |
170 | * | |
83f9135b | 171 | */ |
d6b29d7c JA |
172 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
173 | struct splice_pipe_desc *spd) | |
5274f052 | 174 | { |
00de00bd | 175 | unsigned int spd_pages = spd->nr_pages; |
912d35f8 | 176 | int ret, do_wakeup, page_nr; |
5274f052 JA |
177 | |
178 | ret = 0; | |
179 | do_wakeup = 0; | |
912d35f8 | 180 | page_nr = 0; |
5274f052 | 181 | |
3a326a2c IM |
182 | if (pipe->inode) |
183 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 184 | |
5274f052 | 185 | for (;;) { |
3a326a2c | 186 | if (!pipe->readers) { |
5274f052 JA |
187 | send_sig(SIGPIPE, current, 0); |
188 | if (!ret) | |
189 | ret = -EPIPE; | |
190 | break; | |
191 | } | |
192 | ||
6f767b04 JA |
193 | if (pipe->nrbufs < PIPE_BUFFERS) { |
194 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); | |
3a326a2c | 195 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
5274f052 | 196 | |
912d35f8 JA |
197 | buf->page = spd->pages[page_nr]; |
198 | buf->offset = spd->partial[page_nr].offset; | |
199 | buf->len = spd->partial[page_nr].len; | |
497f9625 | 200 | buf->private = spd->partial[page_nr].private; |
912d35f8 | 201 | buf->ops = spd->ops; |
7afa6fd0 JA |
202 | if (spd->flags & SPLICE_F_GIFT) |
203 | buf->flags |= PIPE_BUF_FLAG_GIFT; | |
204 | ||
6f767b04 | 205 | pipe->nrbufs++; |
912d35f8 JA |
206 | page_nr++; |
207 | ret += buf->len; | |
208 | ||
6f767b04 JA |
209 | if (pipe->inode) |
210 | do_wakeup = 1; | |
5274f052 | 211 | |
912d35f8 | 212 | if (!--spd->nr_pages) |
5274f052 | 213 | break; |
6f767b04 | 214 | if (pipe->nrbufs < PIPE_BUFFERS) |
5274f052 JA |
215 | continue; |
216 | ||
217 | break; | |
218 | } | |
219 | ||
912d35f8 | 220 | if (spd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
221 | if (!ret) |
222 | ret = -EAGAIN; | |
223 | break; | |
224 | } | |
225 | ||
5274f052 JA |
226 | if (signal_pending(current)) { |
227 | if (!ret) | |
228 | ret = -ERESTARTSYS; | |
229 | break; | |
230 | } | |
231 | ||
232 | if (do_wakeup) { | |
c0bd1f65 | 233 | smp_mb(); |
3a326a2c IM |
234 | if (waitqueue_active(&pipe->wait)) |
235 | wake_up_interruptible_sync(&pipe->wait); | |
236 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
237 | do_wakeup = 0; |
238 | } | |
239 | ||
3a326a2c IM |
240 | pipe->waiting_writers++; |
241 | pipe_wait(pipe); | |
242 | pipe->waiting_writers--; | |
5274f052 JA |
243 | } |
244 | ||
02676e5a | 245 | if (pipe->inode) { |
3a326a2c | 246 | mutex_unlock(&pipe->inode->i_mutex); |
5274f052 | 247 | |
02676e5a JA |
248 | if (do_wakeup) { |
249 | smp_mb(); | |
250 | if (waitqueue_active(&pipe->wait)) | |
251 | wake_up_interruptible(&pipe->wait); | |
252 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
253 | } | |
5274f052 JA |
254 | } |
255 | ||
00de00bd | 256 | while (page_nr < spd_pages) |
bbdfc2f7 | 257 | spd->spd_release(spd, page_nr++); |
5274f052 JA |
258 | |
259 | return ret; | |
260 | } | |
261 | ||
bbdfc2f7 JA |
262 | static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
263 | { | |
264 | page_cache_release(spd->pages[i]); | |
265 | } | |
266 | ||
3a326a2c | 267 | static int |
cbb7e577 JA |
268 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
269 | struct pipe_inode_info *pipe, size_t len, | |
270 | unsigned int flags) | |
5274f052 JA |
271 | { |
272 | struct address_space *mapping = in->f_mapping; | |
d8983910 | 273 | unsigned int loff, nr_pages, req_pages; |
16c523dd | 274 | struct page *pages[PIPE_BUFFERS]; |
912d35f8 | 275 | struct partial_page partial[PIPE_BUFFERS]; |
5274f052 | 276 | struct page *page; |
91ad66ef JA |
277 | pgoff_t index, end_index; |
278 | loff_t isize; | |
eb20796b | 279 | int error, page_nr; |
912d35f8 JA |
280 | struct splice_pipe_desc spd = { |
281 | .pages = pages, | |
282 | .partial = partial, | |
283 | .flags = flags, | |
284 | .ops = &page_cache_pipe_buf_ops, | |
bbdfc2f7 | 285 | .spd_release = spd_release_page, |
912d35f8 | 286 | }; |
5274f052 | 287 | |
cbb7e577 | 288 | index = *ppos >> PAGE_CACHE_SHIFT; |
912d35f8 | 289 | loff = *ppos & ~PAGE_CACHE_MASK; |
d8983910 FW |
290 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
291 | nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS); | |
5274f052 | 292 | |
eb20796b JA |
293 | /* |
294 | * Lookup the (hopefully) full range of pages we need. | |
295 | */ | |
296 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); | |
431a4820 | 297 | index += spd.nr_pages; |
82aa5d61 | 298 | |
eb20796b JA |
299 | /* |
300 | * If find_get_pages_contig() returned fewer pages than we needed, | |
431a4820 | 301 | * readahead/allocate the rest and fill in the holes. |
eb20796b | 302 | */ |
431a4820 | 303 | if (spd.nr_pages < nr_pages) |
cf914a7d RR |
304 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
305 | index, req_pages - spd.nr_pages); | |
431a4820 | 306 | |
932cc6d4 | 307 | error = 0; |
eb20796b | 308 | while (spd.nr_pages < nr_pages) { |
82aa5d61 | 309 | /* |
eb20796b JA |
310 | * Page could be there, find_get_pages_contig() breaks on |
311 | * the first hole. | |
5274f052 | 312 | */ |
7480a904 JA |
313 | page = find_get_page(mapping, index); |
314 | if (!page) { | |
7480a904 | 315 | /* |
eb20796b | 316 | * page didn't exist, allocate one. |
7480a904 JA |
317 | */ |
318 | page = page_cache_alloc_cold(mapping); | |
319 | if (!page) | |
320 | break; | |
321 | ||
322 | error = add_to_page_cache_lru(page, mapping, index, | |
4cd13504 | 323 | mapping_gfp_mask(mapping)); |
7480a904 JA |
324 | if (unlikely(error)) { |
325 | page_cache_release(page); | |
a0548871 JA |
326 | if (error == -EEXIST) |
327 | continue; | |
7480a904 JA |
328 | break; |
329 | } | |
eb20796b JA |
330 | /* |
331 | * add_to_page_cache() locks the page, unlock it | |
332 | * to avoid convoluting the logic below even more. | |
333 | */ | |
334 | unlock_page(page); | |
7480a904 JA |
335 | } |
336 | ||
eb20796b JA |
337 | pages[spd.nr_pages++] = page; |
338 | index++; | |
339 | } | |
340 | ||
341 | /* | |
342 | * Now loop over the map and see if we need to start IO on any | |
343 | * pages, fill in the partial map, etc. | |
344 | */ | |
345 | index = *ppos >> PAGE_CACHE_SHIFT; | |
346 | nr_pages = spd.nr_pages; | |
347 | spd.nr_pages = 0; | |
348 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
349 | unsigned int this_len; | |
350 | ||
351 | if (!len) | |
352 | break; | |
353 | ||
354 | /* | |
355 | * this_len is the max we'll use from this page | |
356 | */ | |
357 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
358 | page = pages[page_nr]; | |
359 | ||
a08a166f | 360 | if (PageReadahead(page)) |
cf914a7d | 361 | page_cache_async_readahead(mapping, &in->f_ra, in, |
d8983910 | 362 | page, index, req_pages - page_nr); |
a08a166f | 363 | |
7480a904 JA |
364 | /* |
365 | * If the page isn't uptodate, we may need to start io on it | |
366 | */ | |
367 | if (!PageUptodate(page)) { | |
c4f895cb JA |
368 | /* |
369 | * If in nonblock mode then dont block on waiting | |
370 | * for an in-flight io page | |
371 | */ | |
9ae9d68c | 372 | if (flags & SPLICE_F_NONBLOCK) { |
8191ecd1 JA |
373 | if (TestSetPageLocked(page)) { |
374 | error = -EAGAIN; | |
9ae9d68c | 375 | break; |
8191ecd1 | 376 | } |
9ae9d68c FW |
377 | } else |
378 | lock_page(page); | |
7480a904 JA |
379 | |
380 | /* | |
381 | * page was truncated, stop here. if this isn't the | |
382 | * first page, we'll just complete what we already | |
383 | * added | |
384 | */ | |
385 | if (!page->mapping) { | |
386 | unlock_page(page); | |
7480a904 JA |
387 | break; |
388 | } | |
389 | /* | |
390 | * page was already under io and is now done, great | |
391 | */ | |
392 | if (PageUptodate(page)) { | |
393 | unlock_page(page); | |
394 | goto fill_it; | |
395 | } | |
5274f052 | 396 | |
7480a904 JA |
397 | /* |
398 | * need to read in the page | |
399 | */ | |
400 | error = mapping->a_ops->readpage(in, page); | |
5274f052 | 401 | if (unlikely(error)) { |
eb20796b JA |
402 | /* |
403 | * We really should re-lookup the page here, | |
404 | * but it complicates things a lot. Instead | |
405 | * lets just do what we already stored, and | |
406 | * we'll get it the next time we are called. | |
407 | */ | |
7480a904 | 408 | if (error == AOP_TRUNCATED_PAGE) |
eb20796b JA |
409 | error = 0; |
410 | ||
5274f052 JA |
411 | break; |
412 | } | |
620a324b JA |
413 | } |
414 | fill_it: | |
415 | /* | |
416 | * i_size must be checked after PageUptodate. | |
417 | */ | |
418 | isize = i_size_read(mapping->host); | |
419 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
420 | if (unlikely(!isize || index > end_index)) | |
421 | break; | |
422 | ||
423 | /* | |
424 | * if this is the last page, see if we need to shrink | |
425 | * the length and stop | |
426 | */ | |
427 | if (end_index == index) { | |
428 | unsigned int plen; | |
91ad66ef JA |
429 | |
430 | /* | |
620a324b | 431 | * max good bytes in this page |
91ad66ef | 432 | */ |
620a324b JA |
433 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
434 | if (plen <= loff) | |
91ad66ef | 435 | break; |
91ad66ef JA |
436 | |
437 | /* | |
620a324b | 438 | * force quit after adding this page |
91ad66ef | 439 | */ |
620a324b JA |
440 | this_len = min(this_len, plen - loff); |
441 | len = this_len; | |
5274f052 | 442 | } |
620a324b | 443 | |
eb20796b JA |
444 | partial[page_nr].offset = loff; |
445 | partial[page_nr].len = this_len; | |
82aa5d61 | 446 | len -= this_len; |
91ad66ef | 447 | loff = 0; |
eb20796b JA |
448 | spd.nr_pages++; |
449 | index++; | |
5274f052 JA |
450 | } |
451 | ||
eb20796b | 452 | /* |
475ecade | 453 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
eb20796b JA |
454 | * we got, 'nr_pages' is how many pages are in the map. |
455 | */ | |
456 | while (page_nr < nr_pages) | |
457 | page_cache_release(pages[page_nr++]); | |
f4e6b498 | 458 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
eb20796b | 459 | |
912d35f8 | 460 | if (spd.nr_pages) |
00522fb4 | 461 | return splice_to_pipe(pipe, &spd); |
5274f052 | 462 | |
7480a904 | 463 | return error; |
5274f052 JA |
464 | } |
465 | ||
83f9135b JA |
466 | /** |
467 | * generic_file_splice_read - splice data from file to a pipe | |
468 | * @in: file to splice from | |
932cc6d4 | 469 | * @ppos: position in @in |
83f9135b JA |
470 | * @pipe: pipe to splice to |
471 | * @len: number of bytes to splice | |
472 | * @flags: splice modifier flags | |
473 | * | |
932cc6d4 JA |
474 | * Description: |
475 | * Will read pages from given file and fill them into a pipe. Can be | |
476 | * used as long as the address_space operations for the source implements | |
477 | * a readpage() hook. | |
478 | * | |
83f9135b | 479 | */ |
cbb7e577 JA |
480 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
481 | struct pipe_inode_info *pipe, size_t len, | |
482 | unsigned int flags) | |
5274f052 | 483 | { |
d366d398 | 484 | loff_t isize, left; |
8191ecd1 | 485 | int ret; |
d366d398 JA |
486 | |
487 | isize = i_size_read(in->f_mapping->host); | |
488 | if (unlikely(*ppos >= isize)) | |
489 | return 0; | |
490 | ||
491 | left = isize - *ppos; | |
492 | if (unlikely(left < len)) | |
493 | len = left; | |
5274f052 | 494 | |
8191ecd1 JA |
495 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
496 | if (ret > 0) | |
cbb7e577 | 497 | *ppos += ret; |
5274f052 JA |
498 | |
499 | return ret; | |
500 | } | |
501 | ||
059a8f37 JA |
502 | EXPORT_SYMBOL(generic_file_splice_read); |
503 | ||
5274f052 | 504 | /* |
4f6f0bd2 | 505 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 506 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 507 | */ |
76ad4d11 | 508 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
509 | struct pipe_buffer *buf, struct splice_desc *sd) |
510 | { | |
6a14b90b | 511 | struct file *file = sd->u.file; |
5274f052 | 512 | loff_t pos = sd->pos; |
f84d7519 | 513 | int ret, more; |
5274f052 | 514 | |
cac36bb0 | 515 | ret = buf->ops->confirm(pipe, buf); |
f84d7519 JA |
516 | if (!ret) { |
517 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; | |
5274f052 | 518 | |
f84d7519 JA |
519 | ret = file->f_op->sendpage(file, buf->page, buf->offset, |
520 | sd->len, &pos, more); | |
521 | } | |
5274f052 | 522 | |
016b661e | 523 | return ret; |
5274f052 JA |
524 | } |
525 | ||
526 | /* | |
527 | * This is a little more tricky than the file -> pipe splicing. There are | |
528 | * basically three cases: | |
529 | * | |
530 | * - Destination page already exists in the address space and there | |
531 | * are users of it. For that case we have no other option that | |
532 | * copying the data. Tough luck. | |
533 | * - Destination page already exists in the address space, but there | |
534 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
535 | * through to last case. | |
536 | * - Destination page does not exist, we can add the pipe page to | |
537 | * the page cache and avoid the copy. | |
538 | * | |
83f9135b JA |
539 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
540 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
541 | * file address space page cache. This is possible if no one else has | |
542 | * the pipe page referenced outside of the pipe and page cache. If | |
543 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
544 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 | 545 | */ |
76ad4d11 | 546 | static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
5274f052 JA |
547 | struct splice_desc *sd) |
548 | { | |
6a14b90b | 549 | struct file *file = sd->u.file; |
5274f052 | 550 | struct address_space *mapping = file->f_mapping; |
016b661e | 551 | unsigned int offset, this_len; |
5274f052 | 552 | struct page *page; |
afddba49 | 553 | void *fsdata; |
3e7ee3e7 | 554 | int ret; |
5274f052 JA |
555 | |
556 | /* | |
49d0b21b | 557 | * make sure the data in this buffer is uptodate |
5274f052 | 558 | */ |
cac36bb0 | 559 | ret = buf->ops->confirm(pipe, buf); |
f84d7519 JA |
560 | if (unlikely(ret)) |
561 | return ret; | |
5274f052 | 562 | |
5274f052 JA |
563 | offset = sd->pos & ~PAGE_CACHE_MASK; |
564 | ||
016b661e JA |
565 | this_len = sd->len; |
566 | if (this_len + offset > PAGE_CACHE_SIZE) | |
567 | this_len = PAGE_CACHE_SIZE - offset; | |
568 | ||
afddba49 NP |
569 | ret = pagecache_write_begin(file, mapping, sd->pos, this_len, |
570 | AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); | |
571 | if (unlikely(ret)) | |
572 | goto out; | |
5274f052 | 573 | |
0568b409 | 574 | if (buf->page != page) { |
f84d7519 JA |
575 | /* |
576 | * Careful, ->map() uses KM_USER0! | |
577 | */ | |
76ad4d11 | 578 | char *src = buf->ops->map(pipe, buf, 1); |
f84d7519 | 579 | char *dst = kmap_atomic(page, KM_USER1); |
5abc97aa | 580 | |
016b661e | 581 | memcpy(dst + offset, src + buf->offset, this_len); |
5abc97aa | 582 | flush_dcache_page(page); |
f84d7519 | 583 | kunmap_atomic(dst, KM_USER1); |
76ad4d11 | 584 | buf->ops->unmap(pipe, buf, src); |
5abc97aa | 585 | } |
afddba49 NP |
586 | ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, |
587 | page, fsdata); | |
5274f052 | 588 | out: |
5274f052 JA |
589 | return ret; |
590 | } | |
591 | ||
932cc6d4 JA |
592 | /** |
593 | * __splice_from_pipe - splice data from a pipe to given actor | |
594 | * @pipe: pipe to splice from | |
595 | * @sd: information to @actor | |
596 | * @actor: handler that splices the data | |
597 | * | |
598 | * Description: | |
599 | * This function does little more than loop over the pipe and call | |
600 | * @actor to do the actual moving of a single struct pipe_buffer to | |
601 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
602 | * pipe_to_user. | |
603 | * | |
83f9135b | 604 | */ |
c66ab6fa JA |
605 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
606 | splice_actor *actor) | |
5274f052 | 607 | { |
5274f052 | 608 | int ret, do_wakeup, err; |
5274f052 JA |
609 | |
610 | ret = 0; | |
611 | do_wakeup = 0; | |
612 | ||
5274f052 | 613 | for (;;) { |
6f767b04 JA |
614 | if (pipe->nrbufs) { |
615 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
d4c3cca9 | 616 | const struct pipe_buf_operations *ops = buf->ops; |
5274f052 | 617 | |
c66ab6fa JA |
618 | sd->len = buf->len; |
619 | if (sd->len > sd->total_len) | |
620 | sd->len = sd->total_len; | |
5274f052 | 621 | |
c66ab6fa | 622 | err = actor(pipe, buf, sd); |
016b661e | 623 | if (err <= 0) { |
5274f052 JA |
624 | if (!ret && err != -ENODATA) |
625 | ret = err; | |
626 | ||
627 | break; | |
628 | } | |
629 | ||
016b661e JA |
630 | ret += err; |
631 | buf->offset += err; | |
632 | buf->len -= err; | |
633 | ||
c66ab6fa JA |
634 | sd->len -= err; |
635 | sd->pos += err; | |
636 | sd->total_len -= err; | |
637 | if (sd->len) | |
016b661e | 638 | continue; |
73d62d83 | 639 | |
5274f052 JA |
640 | if (!buf->len) { |
641 | buf->ops = NULL; | |
3a326a2c | 642 | ops->release(pipe, buf); |
6f767b04 JA |
643 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
644 | pipe->nrbufs--; | |
645 | if (pipe->inode) | |
646 | do_wakeup = 1; | |
5274f052 JA |
647 | } |
648 | ||
c66ab6fa | 649 | if (!sd->total_len) |
5274f052 JA |
650 | break; |
651 | } | |
652 | ||
6f767b04 | 653 | if (pipe->nrbufs) |
5274f052 | 654 | continue; |
3a326a2c | 655 | if (!pipe->writers) |
5274f052 | 656 | break; |
3a326a2c | 657 | if (!pipe->waiting_writers) { |
5274f052 JA |
658 | if (ret) |
659 | break; | |
660 | } | |
661 | ||
c66ab6fa | 662 | if (sd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
663 | if (!ret) |
664 | ret = -EAGAIN; | |
665 | break; | |
666 | } | |
667 | ||
5274f052 JA |
668 | if (signal_pending(current)) { |
669 | if (!ret) | |
670 | ret = -ERESTARTSYS; | |
671 | break; | |
672 | } | |
673 | ||
674 | if (do_wakeup) { | |
c0bd1f65 | 675 | smp_mb(); |
3a326a2c IM |
676 | if (waitqueue_active(&pipe->wait)) |
677 | wake_up_interruptible_sync(&pipe->wait); | |
678 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
679 | do_wakeup = 0; |
680 | } | |
681 | ||
3a326a2c | 682 | pipe_wait(pipe); |
5274f052 JA |
683 | } |
684 | ||
5274f052 | 685 | if (do_wakeup) { |
c0bd1f65 | 686 | smp_mb(); |
3a326a2c IM |
687 | if (waitqueue_active(&pipe->wait)) |
688 | wake_up_interruptible(&pipe->wait); | |
689 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
690 | } |
691 | ||
5274f052 | 692 | return ret; |
5274f052 | 693 | } |
40bee44e | 694 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 695 | |
932cc6d4 JA |
696 | /** |
697 | * splice_from_pipe - splice data from a pipe to a file | |
698 | * @pipe: pipe to splice from | |
699 | * @out: file to splice to | |
700 | * @ppos: position in @out | |
701 | * @len: how many bytes to splice | |
702 | * @flags: splice modifier flags | |
703 | * @actor: handler that splices the data | |
704 | * | |
705 | * Description: | |
706 | * See __splice_from_pipe. This function locks the input and output inodes, | |
707 | * otherwise it's identical to __splice_from_pipe(). | |
708 | * | |
709 | */ | |
6da61809 MF |
710 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
711 | loff_t *ppos, size_t len, unsigned int flags, | |
712 | splice_actor *actor) | |
713 | { | |
714 | ssize_t ret; | |
715 | struct inode *inode = out->f_mapping->host; | |
c66ab6fa JA |
716 | struct splice_desc sd = { |
717 | .total_len = len, | |
718 | .flags = flags, | |
719 | .pos = *ppos, | |
6a14b90b | 720 | .u.file = out, |
c66ab6fa | 721 | }; |
6da61809 MF |
722 | |
723 | /* | |
724 | * The actor worker might be calling ->prepare_write and | |
725 | * ->commit_write. Most of the time, these expect i_mutex to | |
726 | * be held. Since this may result in an ABBA deadlock with | |
727 | * pipe->inode, we have to order lock acquiry here. | |
728 | */ | |
729 | inode_double_lock(inode, pipe->inode); | |
c66ab6fa | 730 | ret = __splice_from_pipe(pipe, &sd, actor); |
6da61809 MF |
731 | inode_double_unlock(inode, pipe->inode); |
732 | ||
733 | return ret; | |
734 | } | |
735 | ||
736 | /** | |
737 | * generic_file_splice_write_nolock - generic_file_splice_write without mutexes | |
738 | * @pipe: pipe info | |
739 | * @out: file to write to | |
932cc6d4 | 740 | * @ppos: position in @out |
6da61809 MF |
741 | * @len: number of bytes to splice |
742 | * @flags: splice modifier flags | |
743 | * | |
932cc6d4 JA |
744 | * Description: |
745 | * Will either move or copy pages (determined by @flags options) from | |
746 | * the given pipe inode to the given file. The caller is responsible | |
747 | * for acquiring i_mutex on both inodes. | |
6da61809 MF |
748 | * |
749 | */ | |
750 | ssize_t | |
751 | generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out, | |
752 | loff_t *ppos, size_t len, unsigned int flags) | |
753 | { | |
754 | struct address_space *mapping = out->f_mapping; | |
755 | struct inode *inode = mapping->host; | |
c66ab6fa JA |
756 | struct splice_desc sd = { |
757 | .total_len = len, | |
758 | .flags = flags, | |
759 | .pos = *ppos, | |
6a14b90b | 760 | .u.file = out, |
c66ab6fa | 761 | }; |
6da61809 MF |
762 | ssize_t ret; |
763 | int err; | |
764 | ||
0f7fc9e4 | 765 | err = remove_suid(out->f_path.dentry); |
8c34e2d6 JA |
766 | if (unlikely(err)) |
767 | return err; | |
768 | ||
c66ab6fa | 769 | ret = __splice_from_pipe(pipe, &sd, pipe_to_file); |
6da61809 | 770 | if (ret > 0) { |
17ee4f49 JA |
771 | unsigned long nr_pages; |
772 | ||
6da61809 | 773 | *ppos += ret; |
17ee4f49 | 774 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
6da61809 MF |
775 | |
776 | /* | |
777 | * If file or inode is SYNC and we actually wrote some data, | |
778 | * sync it. | |
779 | */ | |
780 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
781 | err = generic_osync_inode(inode, mapping, | |
782 | OSYNC_METADATA|OSYNC_DATA); | |
783 | ||
784 | if (err) | |
785 | ret = err; | |
786 | } | |
17ee4f49 | 787 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
6da61809 MF |
788 | } |
789 | ||
790 | return ret; | |
791 | } | |
792 | ||
793 | EXPORT_SYMBOL(generic_file_splice_write_nolock); | |
794 | ||
83f9135b JA |
795 | /** |
796 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 797 | * @pipe: pipe info |
83f9135b | 798 | * @out: file to write to |
932cc6d4 | 799 | * @ppos: position in @out |
83f9135b JA |
800 | * @len: number of bytes to splice |
801 | * @flags: splice modifier flags | |
802 | * | |
932cc6d4 JA |
803 | * Description: |
804 | * Will either move or copy pages (determined by @flags options) from | |
805 | * the given pipe inode to the given file. | |
83f9135b JA |
806 | * |
807 | */ | |
3a326a2c IM |
808 | ssize_t |
809 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
cbb7e577 | 810 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 811 | { |
4f6f0bd2 | 812 | struct address_space *mapping = out->f_mapping; |
8c34e2d6 | 813 | struct inode *inode = mapping->host; |
b5376771 | 814 | int killsuid, killpriv; |
3a326a2c | 815 | ssize_t ret; |
b5376771 | 816 | int err = 0; |
8c34e2d6 | 817 | |
b5376771 SH |
818 | killpriv = security_inode_need_killpriv(out->f_path.dentry); |
819 | killsuid = should_remove_suid(out->f_path.dentry); | |
820 | if (unlikely(killsuid || killpriv)) { | |
8c34e2d6 | 821 | mutex_lock(&inode->i_mutex); |
b5376771 SH |
822 | if (killpriv) |
823 | err = security_inode_killpriv(out->f_path.dentry); | |
824 | if (!err && killsuid) | |
825 | err = __remove_suid(out->f_path.dentry, killsuid); | |
8c34e2d6 JA |
826 | mutex_unlock(&inode->i_mutex); |
827 | if (err) | |
828 | return err; | |
829 | } | |
3a326a2c | 830 | |
00522fb4 | 831 | ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file); |
a4514ebd | 832 | if (ret > 0) { |
17ee4f49 JA |
833 | unsigned long nr_pages; |
834 | ||
a4514ebd | 835 | *ppos += ret; |
17ee4f49 | 836 | nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
a4514ebd JA |
837 | |
838 | /* | |
839 | * If file or inode is SYNC and we actually wrote some data, | |
840 | * sync it. | |
841 | */ | |
842 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
a4514ebd JA |
843 | mutex_lock(&inode->i_mutex); |
844 | err = generic_osync_inode(inode, mapping, | |
845 | OSYNC_METADATA|OSYNC_DATA); | |
846 | mutex_unlock(&inode->i_mutex); | |
4f6f0bd2 | 847 | |
a4514ebd JA |
848 | if (err) |
849 | ret = err; | |
850 | } | |
17ee4f49 | 851 | balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
4f6f0bd2 JA |
852 | } |
853 | ||
854 | return ret; | |
5274f052 JA |
855 | } |
856 | ||
059a8f37 JA |
857 | EXPORT_SYMBOL(generic_file_splice_write); |
858 | ||
83f9135b JA |
859 | /** |
860 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 861 | * @pipe: pipe to splice from |
83f9135b | 862 | * @out: socket to write to |
932cc6d4 | 863 | * @ppos: position in @out |
83f9135b JA |
864 | * @len: number of bytes to splice |
865 | * @flags: splice modifier flags | |
866 | * | |
932cc6d4 JA |
867 | * Description: |
868 | * Will send @len bytes from the pipe to a network socket. No data copying | |
869 | * is involved. | |
83f9135b JA |
870 | * |
871 | */ | |
3a326a2c | 872 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 873 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 874 | { |
00522fb4 | 875 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
876 | } |
877 | ||
059a8f37 | 878 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 879 | |
83f9135b JA |
880 | /* |
881 | * Attempt to initiate a splice from pipe to file. | |
882 | */ | |
3a326a2c | 883 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 884 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 885 | { |
5274f052 JA |
886 | int ret; |
887 | ||
49570e9b | 888 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
889 | return -EINVAL; |
890 | ||
49570e9b | 891 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
892 | return -EBADF; |
893 | ||
cbb7e577 | 894 | ret = rw_verify_area(WRITE, out, ppos, len); |
5274f052 JA |
895 | if (unlikely(ret < 0)) |
896 | return ret; | |
897 | ||
cbb7e577 | 898 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
899 | } |
900 | ||
83f9135b JA |
901 | /* |
902 | * Attempt to initiate a splice from a file to a pipe. | |
903 | */ | |
cbb7e577 JA |
904 | static long do_splice_to(struct file *in, loff_t *ppos, |
905 | struct pipe_inode_info *pipe, size_t len, | |
906 | unsigned int flags) | |
5274f052 | 907 | { |
5274f052 JA |
908 | int ret; |
909 | ||
49570e9b | 910 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
911 | return -EINVAL; |
912 | ||
49570e9b | 913 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
914 | return -EBADF; |
915 | ||
cbb7e577 | 916 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
917 | if (unlikely(ret < 0)) |
918 | return ret; | |
919 | ||
cbb7e577 | 920 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 JA |
921 | } |
922 | ||
932cc6d4 JA |
923 | /** |
924 | * splice_direct_to_actor - splices data directly between two non-pipes | |
925 | * @in: file to splice from | |
926 | * @sd: actor information on where to splice to | |
927 | * @actor: handles the data splicing | |
928 | * | |
929 | * Description: | |
930 | * This is a special case helper to splice directly between two | |
931 | * points, without requiring an explicit pipe. Internally an allocated | |
79685b8d | 932 | * pipe is cached in the process, and reused during the lifetime of |
932cc6d4 JA |
933 | * that process. |
934 | * | |
c66ab6fa JA |
935 | */ |
936 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
937 | splice_direct_actor *actor) | |
b92ce558 JA |
938 | { |
939 | struct pipe_inode_info *pipe; | |
940 | long ret, bytes; | |
941 | umode_t i_mode; | |
c66ab6fa JA |
942 | size_t len; |
943 | int i, flags; | |
b92ce558 JA |
944 | |
945 | /* | |
946 | * We require the input being a regular file, as we don't want to | |
947 | * randomly drop data for eg socket -> socket splicing. Use the | |
948 | * piped splicing for that! | |
949 | */ | |
0f7fc9e4 | 950 | i_mode = in->f_path.dentry->d_inode->i_mode; |
b92ce558 JA |
951 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
952 | return -EINVAL; | |
953 | ||
954 | /* | |
955 | * neither in nor out is a pipe, setup an internal pipe attached to | |
956 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
957 | */ | |
958 | pipe = current->splice_pipe; | |
49570e9b | 959 | if (unlikely(!pipe)) { |
b92ce558 JA |
960 | pipe = alloc_pipe_info(NULL); |
961 | if (!pipe) | |
962 | return -ENOMEM; | |
963 | ||
964 | /* | |
965 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 966 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
967 | * PIPE_READERS appropriately. |
968 | */ | |
969 | pipe->readers = 1; | |
970 | ||
971 | current->splice_pipe = pipe; | |
972 | } | |
973 | ||
974 | /* | |
73d62d83 | 975 | * Do the splice. |
b92ce558 JA |
976 | */ |
977 | ret = 0; | |
978 | bytes = 0; | |
c66ab6fa JA |
979 | len = sd->total_len; |
980 | flags = sd->flags; | |
981 | ||
982 | /* | |
983 | * Don't block on output, we have to drain the direct pipe. | |
984 | */ | |
985 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
b92ce558 JA |
986 | |
987 | while (len) { | |
51a92c0f | 988 | size_t read_len; |
bcd4f3ac | 989 | loff_t pos = sd->pos; |
b92ce558 | 990 | |
bcd4f3ac | 991 | ret = do_splice_to(in, &pos, pipe, len, flags); |
51a92c0f | 992 | if (unlikely(ret <= 0)) |
b92ce558 JA |
993 | goto out_release; |
994 | ||
995 | read_len = ret; | |
c66ab6fa | 996 | sd->total_len = read_len; |
b92ce558 JA |
997 | |
998 | /* | |
999 | * NOTE: nonblocking mode only applies to the input. We | |
1000 | * must not do the output in nonblocking mode as then we | |
1001 | * could get stuck data in the internal pipe: | |
1002 | */ | |
c66ab6fa | 1003 | ret = actor(pipe, sd); |
51a92c0f | 1004 | if (unlikely(ret <= 0)) |
b92ce558 JA |
1005 | goto out_release; |
1006 | ||
1007 | bytes += ret; | |
1008 | len -= ret; | |
bcd4f3ac | 1009 | sd->pos = pos; |
b92ce558 | 1010 | |
51a92c0f JA |
1011 | if (ret < read_len) |
1012 | goto out_release; | |
b92ce558 JA |
1013 | } |
1014 | ||
9e97198d | 1015 | done: |
b92ce558 | 1016 | pipe->nrbufs = pipe->curbuf = 0; |
80848708 | 1017 | file_accessed(in); |
b92ce558 JA |
1018 | return bytes; |
1019 | ||
1020 | out_release: | |
1021 | /* | |
1022 | * If we did an incomplete transfer we must release | |
1023 | * the pipe buffers in question: | |
1024 | */ | |
1025 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
1026 | struct pipe_buffer *buf = pipe->bufs + i; | |
1027 | ||
1028 | if (buf->ops) { | |
1029 | buf->ops->release(pipe, buf); | |
1030 | buf->ops = NULL; | |
1031 | } | |
1032 | } | |
b92ce558 | 1033 | |
9e97198d JA |
1034 | if (!bytes) |
1035 | bytes = ret; | |
c66ab6fa | 1036 | |
9e97198d | 1037 | goto done; |
c66ab6fa JA |
1038 | } |
1039 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1040 | ||
1041 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1042 | struct splice_desc *sd) | |
1043 | { | |
6a14b90b | 1044 | struct file *file = sd->u.file; |
c66ab6fa JA |
1045 | |
1046 | return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags); | |
1047 | } | |
1048 | ||
932cc6d4 JA |
1049 | /** |
1050 | * do_splice_direct - splices data directly between two files | |
1051 | * @in: file to splice from | |
1052 | * @ppos: input file offset | |
1053 | * @out: file to splice to | |
1054 | * @len: number of bytes to splice | |
1055 | * @flags: splice modifier flags | |
1056 | * | |
1057 | * Description: | |
1058 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1059 | * doing it in the application would incur an extra system call | |
1060 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1061 | * can splice directly through a process-private pipe. | |
1062 | * | |
1063 | */ | |
c66ab6fa JA |
1064 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1065 | size_t len, unsigned int flags) | |
1066 | { | |
1067 | struct splice_desc sd = { | |
1068 | .len = len, | |
1069 | .total_len = len, | |
1070 | .flags = flags, | |
1071 | .pos = *ppos, | |
6a14b90b | 1072 | .u.file = out, |
c66ab6fa | 1073 | }; |
51a92c0f | 1074 | long ret; |
c66ab6fa JA |
1075 | |
1076 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); | |
51a92c0f JA |
1077 | if (ret > 0) |
1078 | *ppos += ret; | |
1079 | ||
c66ab6fa | 1080 | return ret; |
b92ce558 JA |
1081 | } |
1082 | ||
ddac0d39 JA |
1083 | /* |
1084 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same | |
1085 | * location, so checking ->i_pipe is not enough to verify that this is a | |
1086 | * pipe. | |
1087 | */ | |
1088 | static inline struct pipe_inode_info *pipe_info(struct inode *inode) | |
1089 | { | |
1090 | if (S_ISFIFO(inode->i_mode)) | |
1091 | return inode->i_pipe; | |
1092 | ||
1093 | return NULL; | |
1094 | } | |
1095 | ||
83f9135b JA |
1096 | /* |
1097 | * Determine where to splice to/from. | |
1098 | */ | |
529565dc IM |
1099 | static long do_splice(struct file *in, loff_t __user *off_in, |
1100 | struct file *out, loff_t __user *off_out, | |
1101 | size_t len, unsigned int flags) | |
5274f052 | 1102 | { |
3a326a2c | 1103 | struct pipe_inode_info *pipe; |
cbb7e577 | 1104 | loff_t offset, *off; |
a4514ebd | 1105 | long ret; |
5274f052 | 1106 | |
0f7fc9e4 | 1107 | pipe = pipe_info(in->f_path.dentry->d_inode); |
529565dc IM |
1108 | if (pipe) { |
1109 | if (off_in) | |
1110 | return -ESPIPE; | |
b92ce558 JA |
1111 | if (off_out) { |
1112 | if (out->f_op->llseek == no_llseek) | |
1113 | return -EINVAL; | |
cbb7e577 | 1114 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1115 | return -EFAULT; |
cbb7e577 JA |
1116 | off = &offset; |
1117 | } else | |
1118 | off = &out->f_pos; | |
529565dc | 1119 | |
a4514ebd JA |
1120 | ret = do_splice_from(pipe, out, off, len, flags); |
1121 | ||
1122 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
1123 | ret = -EFAULT; | |
1124 | ||
1125 | return ret; | |
529565dc | 1126 | } |
5274f052 | 1127 | |
0f7fc9e4 | 1128 | pipe = pipe_info(out->f_path.dentry->d_inode); |
529565dc IM |
1129 | if (pipe) { |
1130 | if (off_out) | |
1131 | return -ESPIPE; | |
b92ce558 JA |
1132 | if (off_in) { |
1133 | if (in->f_op->llseek == no_llseek) | |
1134 | return -EINVAL; | |
cbb7e577 | 1135 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1136 | return -EFAULT; |
cbb7e577 JA |
1137 | off = &offset; |
1138 | } else | |
1139 | off = &in->f_pos; | |
529565dc | 1140 | |
a4514ebd JA |
1141 | ret = do_splice_to(in, off, pipe, len, flags); |
1142 | ||
1143 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
1144 | ret = -EFAULT; | |
1145 | ||
1146 | return ret; | |
529565dc | 1147 | } |
5274f052 JA |
1148 | |
1149 | return -EINVAL; | |
1150 | } | |
1151 | ||
75723957 LT |
1152 | /* |
1153 | * Do a copy-from-user while holding the mmap_semaphore for reading, in a | |
1154 | * manner safe from deadlocking with simultaneous mmap() (grabbing mmap_sem | |
1155 | * for writing) and page faulting on the user memory pointed to by src. | |
1156 | * This assumes that we will very rarely hit the partial != 0 path, or this | |
1157 | * will not be a win. | |
1158 | */ | |
1159 | static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n) | |
1160 | { | |
1161 | int partial; | |
1162 | ||
8811930d JA |
1163 | if (!access_ok(VERIFY_READ, src, n)) |
1164 | return -EFAULT; | |
1165 | ||
75723957 LT |
1166 | pagefault_disable(); |
1167 | partial = __copy_from_user_inatomic(dst, src, n); | |
1168 | pagefault_enable(); | |
1169 | ||
1170 | /* | |
1171 | * Didn't copy everything, drop the mmap_sem and do a faulting copy | |
1172 | */ | |
1173 | if (unlikely(partial)) { | |
1174 | up_read(¤t->mm->mmap_sem); | |
1175 | partial = copy_from_user(dst, src, n); | |
1176 | down_read(¤t->mm->mmap_sem); | |
1177 | } | |
1178 | ||
1179 | return partial; | |
1180 | } | |
1181 | ||
912d35f8 JA |
1182 | /* |
1183 | * Map an iov into an array of pages and offset/length tupples. With the | |
1184 | * partial_page structure, we can map several non-contiguous ranges into | |
1185 | * our ones pages[] map instead of splitting that operation into pieces. | |
1186 | * Could easily be exported as a generic helper for other users, in which | |
1187 | * case one would probably want to add a 'max_nr_pages' parameter as well. | |
1188 | */ | |
1189 | static int get_iovec_page_array(const struct iovec __user *iov, | |
1190 | unsigned int nr_vecs, struct page **pages, | |
7afa6fd0 | 1191 | struct partial_page *partial, int aligned) |
912d35f8 JA |
1192 | { |
1193 | int buffers = 0, error = 0; | |
1194 | ||
912d35f8 JA |
1195 | down_read(¤t->mm->mmap_sem); |
1196 | ||
1197 | while (nr_vecs) { | |
1198 | unsigned long off, npages; | |
75723957 | 1199 | struct iovec entry; |
912d35f8 JA |
1200 | void __user *base; |
1201 | size_t len; | |
1202 | int i; | |
1203 | ||
75723957 LT |
1204 | error = -EFAULT; |
1205 | if (copy_from_user_mmap_sem(&entry, iov, sizeof(entry))) | |
912d35f8 JA |
1206 | break; |
1207 | ||
75723957 LT |
1208 | base = entry.iov_base; |
1209 | len = entry.iov_len; | |
1210 | ||
912d35f8 JA |
1211 | /* |
1212 | * Sanity check this iovec. 0 read succeeds. | |
1213 | */ | |
75723957 | 1214 | error = 0; |
912d35f8 JA |
1215 | if (unlikely(!len)) |
1216 | break; | |
1217 | error = -EFAULT; | |
712a30e6 | 1218 | if (!access_ok(VERIFY_READ, base, len)) |
912d35f8 JA |
1219 | break; |
1220 | ||
1221 | /* | |
1222 | * Get this base offset and number of pages, then map | |
1223 | * in the user pages. | |
1224 | */ | |
1225 | off = (unsigned long) base & ~PAGE_MASK; | |
7afa6fd0 JA |
1226 | |
1227 | /* | |
1228 | * If asked for alignment, the offset must be zero and the | |
1229 | * length a multiple of the PAGE_SIZE. | |
1230 | */ | |
1231 | error = -EINVAL; | |
1232 | if (aligned && (off || len & ~PAGE_MASK)) | |
1233 | break; | |
1234 | ||
912d35f8 JA |
1235 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1236 | if (npages > PIPE_BUFFERS - buffers) | |
1237 | npages = PIPE_BUFFERS - buffers; | |
1238 | ||
1239 | error = get_user_pages(current, current->mm, | |
1240 | (unsigned long) base, npages, 0, 0, | |
1241 | &pages[buffers], NULL); | |
1242 | ||
1243 | if (unlikely(error <= 0)) | |
1244 | break; | |
1245 | ||
1246 | /* | |
1247 | * Fill this contiguous range into the partial page map. | |
1248 | */ | |
1249 | for (i = 0; i < error; i++) { | |
7591489a | 1250 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
912d35f8 JA |
1251 | |
1252 | partial[buffers].offset = off; | |
1253 | partial[buffers].len = plen; | |
1254 | ||
1255 | off = 0; | |
1256 | len -= plen; | |
1257 | buffers++; | |
1258 | } | |
1259 | ||
1260 | /* | |
1261 | * We didn't complete this iov, stop here since it probably | |
1262 | * means we have to move some of this into a pipe to | |
1263 | * be able to continue. | |
1264 | */ | |
1265 | if (len) | |
1266 | break; | |
1267 | ||
1268 | /* | |
1269 | * Don't continue if we mapped fewer pages than we asked for, | |
1270 | * or if we mapped the max number of pages that we have | |
1271 | * room for. | |
1272 | */ | |
1273 | if (error < npages || buffers == PIPE_BUFFERS) | |
1274 | break; | |
1275 | ||
1276 | nr_vecs--; | |
1277 | iov++; | |
1278 | } | |
1279 | ||
1280 | up_read(¤t->mm->mmap_sem); | |
1281 | ||
1282 | if (buffers) | |
1283 | return buffers; | |
1284 | ||
1285 | return error; | |
1286 | } | |
1287 | ||
6a14b90b JA |
1288 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1289 | struct splice_desc *sd) | |
1290 | { | |
1291 | char *src; | |
1292 | int ret; | |
1293 | ||
cac36bb0 | 1294 | ret = buf->ops->confirm(pipe, buf); |
6a14b90b JA |
1295 | if (unlikely(ret)) |
1296 | return ret; | |
1297 | ||
1298 | /* | |
1299 | * See if we can use the atomic maps, by prefaulting in the | |
1300 | * pages and doing an atomic copy | |
1301 | */ | |
1302 | if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { | |
1303 | src = buf->ops->map(pipe, buf, 1); | |
1304 | ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, | |
1305 | sd->len); | |
1306 | buf->ops->unmap(pipe, buf, src); | |
1307 | if (!ret) { | |
1308 | ret = sd->len; | |
1309 | goto out; | |
1310 | } | |
1311 | } | |
1312 | ||
1313 | /* | |
1314 | * No dice, use slow non-atomic map and copy | |
1315 | */ | |
1316 | src = buf->ops->map(pipe, buf, 0); | |
1317 | ||
1318 | ret = sd->len; | |
1319 | if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) | |
1320 | ret = -EFAULT; | |
1321 | ||
6866bef4 | 1322 | buf->ops->unmap(pipe, buf, src); |
6a14b90b JA |
1323 | out: |
1324 | if (ret > 0) | |
1325 | sd->u.userptr += ret; | |
6a14b90b JA |
1326 | return ret; |
1327 | } | |
1328 | ||
1329 | /* | |
1330 | * For lack of a better implementation, implement vmsplice() to userspace | |
1331 | * as a simple copy of the pipes pages to the user iov. | |
1332 | */ | |
1333 | static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, | |
1334 | unsigned long nr_segs, unsigned int flags) | |
1335 | { | |
1336 | struct pipe_inode_info *pipe; | |
1337 | struct splice_desc sd; | |
1338 | ssize_t size; | |
1339 | int error; | |
1340 | long ret; | |
1341 | ||
1342 | pipe = pipe_info(file->f_path.dentry->d_inode); | |
1343 | if (!pipe) | |
1344 | return -EBADF; | |
1345 | ||
1346 | if (pipe->inode) | |
1347 | mutex_lock(&pipe->inode->i_mutex); | |
1348 | ||
1349 | error = ret = 0; | |
1350 | while (nr_segs) { | |
1351 | void __user *base; | |
1352 | size_t len; | |
1353 | ||
1354 | /* | |
1355 | * Get user address base and length for this iovec. | |
1356 | */ | |
1357 | error = get_user(base, &iov->iov_base); | |
1358 | if (unlikely(error)) | |
1359 | break; | |
1360 | error = get_user(len, &iov->iov_len); | |
1361 | if (unlikely(error)) | |
1362 | break; | |
1363 | ||
1364 | /* | |
1365 | * Sanity check this iovec. 0 read succeeds. | |
1366 | */ | |
1367 | if (unlikely(!len)) | |
1368 | break; | |
1369 | if (unlikely(!base)) { | |
1370 | error = -EFAULT; | |
1371 | break; | |
1372 | } | |
1373 | ||
8811930d JA |
1374 | if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { |
1375 | error = -EFAULT; | |
1376 | break; | |
1377 | } | |
1378 | ||
6a14b90b JA |
1379 | sd.len = 0; |
1380 | sd.total_len = len; | |
1381 | sd.flags = flags; | |
1382 | sd.u.userptr = base; | |
1383 | sd.pos = 0; | |
1384 | ||
1385 | size = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1386 | if (size < 0) { | |
1387 | if (!ret) | |
1388 | ret = size; | |
1389 | ||
1390 | break; | |
1391 | } | |
1392 | ||
1393 | ret += size; | |
1394 | ||
1395 | if (size < len) | |
1396 | break; | |
1397 | ||
1398 | nr_segs--; | |
1399 | iov++; | |
1400 | } | |
1401 | ||
1402 | if (pipe->inode) | |
1403 | mutex_unlock(&pipe->inode->i_mutex); | |
1404 | ||
1405 | if (!ret) | |
1406 | ret = error; | |
1407 | ||
1408 | return ret; | |
1409 | } | |
1410 | ||
912d35f8 JA |
1411 | /* |
1412 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1413 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1414 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1415 | */ |
6a14b90b JA |
1416 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
1417 | unsigned long nr_segs, unsigned int flags) | |
912d35f8 | 1418 | { |
ddac0d39 | 1419 | struct pipe_inode_info *pipe; |
912d35f8 JA |
1420 | struct page *pages[PIPE_BUFFERS]; |
1421 | struct partial_page partial[PIPE_BUFFERS]; | |
1422 | struct splice_pipe_desc spd = { | |
1423 | .pages = pages, | |
1424 | .partial = partial, | |
1425 | .flags = flags, | |
1426 | .ops = &user_page_pipe_buf_ops, | |
bbdfc2f7 | 1427 | .spd_release = spd_release_page, |
912d35f8 JA |
1428 | }; |
1429 | ||
0f7fc9e4 | 1430 | pipe = pipe_info(file->f_path.dentry->d_inode); |
ddac0d39 | 1431 | if (!pipe) |
912d35f8 | 1432 | return -EBADF; |
912d35f8 | 1433 | |
7afa6fd0 JA |
1434 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial, |
1435 | flags & SPLICE_F_GIFT); | |
912d35f8 JA |
1436 | if (spd.nr_pages <= 0) |
1437 | return spd.nr_pages; | |
1438 | ||
00522fb4 | 1439 | return splice_to_pipe(pipe, &spd); |
912d35f8 JA |
1440 | } |
1441 | ||
6a14b90b JA |
1442 | /* |
1443 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1444 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1445 | * operation that can be supported without any funky alignment restrictions | |
1446 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1447 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1448 | * solutions for that: | |
1449 | * | |
1450 | * - memcpy() the data internally, at which point we might as well just | |
1451 | * do a regular read() on the buffer anyway. | |
1452 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1453 | * has restriction limitations on both ends of the pipe). | |
1454 | * | |
1455 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1456 | * | |
1457 | */ | |
912d35f8 JA |
1458 | asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov, |
1459 | unsigned long nr_segs, unsigned int flags) | |
1460 | { | |
1461 | struct file *file; | |
1462 | long error; | |
1463 | int fput; | |
1464 | ||
6a14b90b JA |
1465 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1466 | return -EINVAL; | |
1467 | else if (unlikely(!nr_segs)) | |
1468 | return 0; | |
1469 | ||
912d35f8 JA |
1470 | error = -EBADF; |
1471 | file = fget_light(fd, &fput); | |
1472 | if (file) { | |
1473 | if (file->f_mode & FMODE_WRITE) | |
6a14b90b JA |
1474 | error = vmsplice_to_pipe(file, iov, nr_segs, flags); |
1475 | else if (file->f_mode & FMODE_READ) | |
1476 | error = vmsplice_to_user(file, iov, nr_segs, flags); | |
912d35f8 JA |
1477 | |
1478 | fput_light(file, fput); | |
1479 | } | |
1480 | ||
1481 | return error; | |
1482 | } | |
1483 | ||
529565dc IM |
1484 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
1485 | int fd_out, loff_t __user *off_out, | |
1486 | size_t len, unsigned int flags) | |
5274f052 JA |
1487 | { |
1488 | long error; | |
1489 | struct file *in, *out; | |
1490 | int fput_in, fput_out; | |
1491 | ||
1492 | if (unlikely(!len)) | |
1493 | return 0; | |
1494 | ||
1495 | error = -EBADF; | |
529565dc | 1496 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
1497 | if (in) { |
1498 | if (in->f_mode & FMODE_READ) { | |
529565dc | 1499 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
1500 | if (out) { |
1501 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
1502 | error = do_splice(in, off_in, |
1503 | out, off_out, | |
1504 | len, flags); | |
5274f052 JA |
1505 | fput_light(out, fput_out); |
1506 | } | |
1507 | } | |
1508 | ||
1509 | fput_light(in, fput_in); | |
1510 | } | |
1511 | ||
1512 | return error; | |
1513 | } | |
70524490 | 1514 | |
aadd06e5 JA |
1515 | /* |
1516 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1517 | * return an appropriate error. | |
1518 | */ | |
1519 | static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1520 | { | |
1521 | int ret; | |
1522 | ||
1523 | /* | |
1524 | * Check ->nrbufs without the inode lock first. This function | |
1525 | * is speculative anyways, so missing one is ok. | |
1526 | */ | |
1527 | if (pipe->nrbufs) | |
1528 | return 0; | |
1529 | ||
1530 | ret = 0; | |
1531 | mutex_lock(&pipe->inode->i_mutex); | |
1532 | ||
1533 | while (!pipe->nrbufs) { | |
1534 | if (signal_pending(current)) { | |
1535 | ret = -ERESTARTSYS; | |
1536 | break; | |
1537 | } | |
1538 | if (!pipe->writers) | |
1539 | break; | |
1540 | if (!pipe->waiting_writers) { | |
1541 | if (flags & SPLICE_F_NONBLOCK) { | |
1542 | ret = -EAGAIN; | |
1543 | break; | |
1544 | } | |
1545 | } | |
1546 | pipe_wait(pipe); | |
1547 | } | |
1548 | ||
1549 | mutex_unlock(&pipe->inode->i_mutex); | |
1550 | return ret; | |
1551 | } | |
1552 | ||
1553 | /* | |
1554 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1555 | * return an appropriate error. | |
1556 | */ | |
1557 | static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1558 | { | |
1559 | int ret; | |
1560 | ||
1561 | /* | |
1562 | * Check ->nrbufs without the inode lock first. This function | |
1563 | * is speculative anyways, so missing one is ok. | |
1564 | */ | |
1565 | if (pipe->nrbufs < PIPE_BUFFERS) | |
1566 | return 0; | |
1567 | ||
1568 | ret = 0; | |
1569 | mutex_lock(&pipe->inode->i_mutex); | |
1570 | ||
1571 | while (pipe->nrbufs >= PIPE_BUFFERS) { | |
1572 | if (!pipe->readers) { | |
1573 | send_sig(SIGPIPE, current, 0); | |
1574 | ret = -EPIPE; | |
1575 | break; | |
1576 | } | |
1577 | if (flags & SPLICE_F_NONBLOCK) { | |
1578 | ret = -EAGAIN; | |
1579 | break; | |
1580 | } | |
1581 | if (signal_pending(current)) { | |
1582 | ret = -ERESTARTSYS; | |
1583 | break; | |
1584 | } | |
1585 | pipe->waiting_writers++; | |
1586 | pipe_wait(pipe); | |
1587 | pipe->waiting_writers--; | |
1588 | } | |
1589 | ||
1590 | mutex_unlock(&pipe->inode->i_mutex); | |
1591 | return ret; | |
1592 | } | |
1593 | ||
70524490 JA |
1594 | /* |
1595 | * Link contents of ipipe to opipe. | |
1596 | */ | |
1597 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1598 | struct pipe_inode_info *opipe, | |
1599 | size_t len, unsigned int flags) | |
1600 | { | |
1601 | struct pipe_buffer *ibuf, *obuf; | |
aadd06e5 | 1602 | int ret = 0, i = 0, nbuf; |
70524490 JA |
1603 | |
1604 | /* | |
1605 | * Potential ABBA deadlock, work around it by ordering lock | |
1606 | * grabbing by inode address. Otherwise two different processes | |
1607 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1608 | */ | |
62752ee1 | 1609 | inode_double_lock(ipipe->inode, opipe->inode); |
70524490 | 1610 | |
aadd06e5 | 1611 | do { |
70524490 JA |
1612 | if (!opipe->readers) { |
1613 | send_sig(SIGPIPE, current, 0); | |
1614 | if (!ret) | |
1615 | ret = -EPIPE; | |
1616 | break; | |
1617 | } | |
70524490 | 1618 | |
aadd06e5 JA |
1619 | /* |
1620 | * If we have iterated all input buffers or ran out of | |
1621 | * output room, break. | |
1622 | */ | |
1623 | if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) | |
1624 | break; | |
70524490 | 1625 | |
aadd06e5 JA |
1626 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); |
1627 | nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); | |
70524490 JA |
1628 | |
1629 | /* | |
aadd06e5 JA |
1630 | * Get a reference to this pipe buffer, |
1631 | * so we can copy the contents over. | |
70524490 | 1632 | */ |
aadd06e5 JA |
1633 | ibuf->ops->get(ipipe, ibuf); |
1634 | ||
1635 | obuf = opipe->bufs + nbuf; | |
1636 | *obuf = *ibuf; | |
1637 | ||
2a27250e | 1638 | /* |
aadd06e5 JA |
1639 | * Don't inherit the gift flag, we need to |
1640 | * prevent multiple steals of this page. | |
2a27250e | 1641 | */ |
aadd06e5 | 1642 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
70524490 | 1643 | |
aadd06e5 JA |
1644 | if (obuf->len > len) |
1645 | obuf->len = len; | |
70524490 | 1646 | |
aadd06e5 JA |
1647 | opipe->nrbufs++; |
1648 | ret += obuf->len; | |
1649 | len -= obuf->len; | |
1650 | i++; | |
1651 | } while (len); | |
70524490 | 1652 | |
02cf01ae JA |
1653 | /* |
1654 | * return EAGAIN if we have the potential of some data in the | |
1655 | * future, otherwise just return 0 | |
1656 | */ | |
1657 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
1658 | ret = -EAGAIN; | |
1659 | ||
62752ee1 | 1660 | inode_double_unlock(ipipe->inode, opipe->inode); |
70524490 | 1661 | |
aadd06e5 JA |
1662 | /* |
1663 | * If we put data in the output pipe, wakeup any potential readers. | |
1664 | */ | |
1665 | if (ret > 0) { | |
70524490 JA |
1666 | smp_mb(); |
1667 | if (waitqueue_active(&opipe->wait)) | |
1668 | wake_up_interruptible(&opipe->wait); | |
1669 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1670 | } | |
1671 | ||
1672 | return ret; | |
1673 | } | |
1674 | ||
1675 | /* | |
1676 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1677 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1678 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1679 | * applicable one is SPLICE_F_NONBLOCK. | |
1680 | */ | |
1681 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1682 | unsigned int flags) | |
1683 | { | |
0f7fc9e4 JJS |
1684 | struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode); |
1685 | struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode); | |
aadd06e5 | 1686 | int ret = -EINVAL; |
70524490 JA |
1687 | |
1688 | /* | |
aadd06e5 JA |
1689 | * Duplicate the contents of ipipe to opipe without actually |
1690 | * copying the data. | |
70524490 | 1691 | */ |
aadd06e5 JA |
1692 | if (ipipe && opipe && ipipe != opipe) { |
1693 | /* | |
1694 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1695 | * ordering doesn't really matter. | |
1696 | */ | |
1697 | ret = link_ipipe_prep(ipipe, flags); | |
1698 | if (!ret) { | |
1699 | ret = link_opipe_prep(opipe, flags); | |
02cf01ae | 1700 | if (!ret) |
aadd06e5 | 1701 | ret = link_pipe(ipipe, opipe, len, flags); |
aadd06e5 JA |
1702 | } |
1703 | } | |
70524490 | 1704 | |
aadd06e5 | 1705 | return ret; |
70524490 JA |
1706 | } |
1707 | ||
1708 | asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) | |
1709 | { | |
1710 | struct file *in; | |
1711 | int error, fput_in; | |
1712 | ||
1713 | if (unlikely(!len)) | |
1714 | return 0; | |
1715 | ||
1716 | error = -EBADF; | |
1717 | in = fget_light(fdin, &fput_in); | |
1718 | if (in) { | |
1719 | if (in->f_mode & FMODE_READ) { | |
1720 | int fput_out; | |
1721 | struct file *out = fget_light(fdout, &fput_out); | |
1722 | ||
1723 | if (out) { | |
1724 | if (out->f_mode & FMODE_WRITE) | |
1725 | error = do_tee(in, out, len, flags); | |
1726 | fput_light(out, fput_out); | |
1727 | } | |
1728 | } | |
1729 | fput_light(in, fput_in); | |
1730 | } | |
1731 | ||
1732 | return error; | |
1733 | } |