Commit | Line | Data |
---|---|---|
5274f052 JA |
1 | /* |
2 | * "splice": joining two ropes together by interweaving their strands. | |
3 | * | |
4 | * This is the "extended pipe" functionality, where a pipe is used as | |
5 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel | |
6 | * buffer that you can use to transfer data from one end to the other. | |
7 | * | |
8 | * The traditional unix read/write is extended with a "splice()" operation | |
9 | * that transfers data buffers to or from a pipe buffer. | |
10 | * | |
11 | * Named by Larry McVoy, original implementation from Linus, extended by | |
c2058e06 JA |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. | |
5274f052 | 14 | * |
c2058e06 JA |
15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@suse.de> |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> | |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> | |
5274f052 JA |
18 | * |
19 | */ | |
20 | #include <linux/fs.h> | |
21 | #include <linux/file.h> | |
22 | #include <linux/pagemap.h> | |
23 | #include <linux/pipe_fs_i.h> | |
24 | #include <linux/mm_inline.h> | |
5abc97aa | 25 | #include <linux/swap.h> |
4f6f0bd2 JA |
26 | #include <linux/writeback.h> |
27 | #include <linux/buffer_head.h> | |
a0f06780 | 28 | #include <linux/module.h> |
4f6f0bd2 | 29 | #include <linux/syscalls.h> |
912d35f8 | 30 | #include <linux/uio.h> |
5274f052 | 31 | |
912d35f8 JA |
32 | struct partial_page { |
33 | unsigned int offset; | |
34 | unsigned int len; | |
35 | }; | |
36 | ||
37 | /* | |
00522fb4 | 38 | * Passed to splice_to_pipe |
912d35f8 JA |
39 | */ |
40 | struct splice_pipe_desc { | |
41 | struct page **pages; /* page map */ | |
42 | struct partial_page *partial; /* pages[] may not be contig */ | |
43 | int nr_pages; /* number of pages in map */ | |
44 | unsigned int flags; /* splice flags */ | |
45 | struct pipe_buf_operations *ops;/* ops associated with output pipe */ | |
46 | }; | |
47 | ||
83f9135b JA |
48 | /* |
49 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
50 | * a vm helper function, it's already simplified quite a bit by the | |
51 | * addition of remove_mapping(). If success is returned, the caller may | |
52 | * attempt to reuse this page for another destination. | |
53 | */ | |
5abc97aa JA |
54 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, |
55 | struct pipe_buffer *buf) | |
56 | { | |
57 | struct page *page = buf->page; | |
4f6f0bd2 | 58 | struct address_space *mapping = page_mapping(page); |
5abc97aa | 59 | |
9e0267c2 JA |
60 | lock_page(page); |
61 | ||
5abc97aa JA |
62 | WARN_ON(!PageUptodate(page)); |
63 | ||
ad8d6f0a JA |
64 | /* |
65 | * At least for ext2 with nobh option, we need to wait on writeback | |
66 | * completing on this page, since we'll remove it from the pagecache. | |
67 | * Otherwise truncate wont wait on the page, allowing the disk | |
68 | * blocks to be reused by someone else before we actually wrote our | |
69 | * data to them. fs corruption ensues. | |
70 | */ | |
71 | wait_on_page_writeback(page); | |
72 | ||
4f6f0bd2 JA |
73 | if (PagePrivate(page)) |
74 | try_to_release_page(page, mapping_gfp_mask(mapping)); | |
75 | ||
9e0267c2 JA |
76 | if (!remove_mapping(mapping, page)) { |
77 | unlock_page(page); | |
5abc97aa | 78 | return 1; |
9e0267c2 | 79 | } |
5abc97aa | 80 | |
3e7ee3e7 | 81 | buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU; |
5abc97aa JA |
82 | return 0; |
83 | } | |
84 | ||
5274f052 JA |
85 | static void page_cache_pipe_buf_release(struct pipe_inode_info *info, |
86 | struct pipe_buffer *buf) | |
87 | { | |
88 | page_cache_release(buf->page); | |
89 | buf->page = NULL; | |
3e7ee3e7 | 90 | buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU); |
5274f052 JA |
91 | } |
92 | ||
93 | static void *page_cache_pipe_buf_map(struct file *file, | |
94 | struct pipe_inode_info *info, | |
95 | struct pipe_buffer *buf) | |
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 | /* | |
73d62d83 | 121 | * Page is ok afterall, fall through to mapping. |
49d0b21b | 122 | */ |
5274f052 | 123 | unlock_page(page); |
5274f052 JA |
124 | } |
125 | ||
49d0b21b JA |
126 | return kmap(page); |
127 | error: | |
128 | unlock_page(page); | |
129 | return ERR_PTR(err); | |
5274f052 JA |
130 | } |
131 | ||
132 | static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info, | |
133 | struct pipe_buffer *buf) | |
134 | { | |
5274f052 JA |
135 | kunmap(buf->page); |
136 | } | |
137 | ||
912d35f8 JA |
138 | static void *user_page_pipe_buf_map(struct file *file, |
139 | struct pipe_inode_info *pipe, | |
140 | struct pipe_buffer *buf) | |
141 | { | |
142 | return kmap(buf->page); | |
143 | } | |
144 | ||
145 | static void user_page_pipe_buf_unmap(struct pipe_inode_info *pipe, | |
146 | struct pipe_buffer *buf) | |
147 | { | |
148 | kunmap(buf->page); | |
149 | } | |
150 | ||
70524490 JA |
151 | static void page_cache_pipe_buf_get(struct pipe_inode_info *info, |
152 | struct pipe_buffer *buf) | |
153 | { | |
154 | page_cache_get(buf->page); | |
155 | } | |
156 | ||
5274f052 JA |
157 | static struct pipe_buf_operations page_cache_pipe_buf_ops = { |
158 | .can_merge = 0, | |
159 | .map = page_cache_pipe_buf_map, | |
160 | .unmap = page_cache_pipe_buf_unmap, | |
161 | .release = page_cache_pipe_buf_release, | |
5abc97aa | 162 | .steal = page_cache_pipe_buf_steal, |
70524490 | 163 | .get = page_cache_pipe_buf_get, |
5274f052 JA |
164 | }; |
165 | ||
912d35f8 JA |
166 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
167 | struct pipe_buffer *buf) | |
168 | { | |
169 | return 1; | |
170 | } | |
171 | ||
172 | static struct pipe_buf_operations user_page_pipe_buf_ops = { | |
173 | .can_merge = 0, | |
174 | .map = user_page_pipe_buf_map, | |
175 | .unmap = user_page_pipe_buf_unmap, | |
176 | .release = page_cache_pipe_buf_release, | |
177 | .steal = user_page_pipe_buf_steal, | |
178 | .get = page_cache_pipe_buf_get, | |
179 | }; | |
180 | ||
83f9135b JA |
181 | /* |
182 | * Pipe output worker. This sets up our pipe format with the page cache | |
183 | * pipe buffer operations. Otherwise very similar to the regular pipe_writev(). | |
184 | */ | |
00522fb4 JA |
185 | static ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
186 | struct splice_pipe_desc *spd) | |
5274f052 | 187 | { |
912d35f8 | 188 | int ret, do_wakeup, page_nr; |
5274f052 JA |
189 | |
190 | ret = 0; | |
191 | do_wakeup = 0; | |
912d35f8 | 192 | page_nr = 0; |
5274f052 | 193 | |
3a326a2c IM |
194 | if (pipe->inode) |
195 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 196 | |
5274f052 | 197 | for (;;) { |
3a326a2c | 198 | if (!pipe->readers) { |
5274f052 JA |
199 | send_sig(SIGPIPE, current, 0); |
200 | if (!ret) | |
201 | ret = -EPIPE; | |
202 | break; | |
203 | } | |
204 | ||
6f767b04 JA |
205 | if (pipe->nrbufs < PIPE_BUFFERS) { |
206 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); | |
3a326a2c | 207 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
5274f052 | 208 | |
912d35f8 JA |
209 | buf->page = spd->pages[page_nr]; |
210 | buf->offset = spd->partial[page_nr].offset; | |
211 | buf->len = spd->partial[page_nr].len; | |
212 | buf->ops = spd->ops; | |
6f767b04 | 213 | pipe->nrbufs++; |
912d35f8 JA |
214 | page_nr++; |
215 | ret += buf->len; | |
216 | ||
6f767b04 JA |
217 | if (pipe->inode) |
218 | do_wakeup = 1; | |
5274f052 | 219 | |
912d35f8 | 220 | if (!--spd->nr_pages) |
5274f052 | 221 | break; |
6f767b04 | 222 | if (pipe->nrbufs < PIPE_BUFFERS) |
5274f052 JA |
223 | continue; |
224 | ||
225 | break; | |
226 | } | |
227 | ||
912d35f8 | 228 | if (spd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
229 | if (!ret) |
230 | ret = -EAGAIN; | |
231 | break; | |
232 | } | |
233 | ||
5274f052 JA |
234 | if (signal_pending(current)) { |
235 | if (!ret) | |
236 | ret = -ERESTARTSYS; | |
237 | break; | |
238 | } | |
239 | ||
240 | if (do_wakeup) { | |
c0bd1f65 | 241 | smp_mb(); |
3a326a2c IM |
242 | if (waitqueue_active(&pipe->wait)) |
243 | wake_up_interruptible_sync(&pipe->wait); | |
244 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
245 | do_wakeup = 0; |
246 | } | |
247 | ||
3a326a2c IM |
248 | pipe->waiting_writers++; |
249 | pipe_wait(pipe); | |
250 | pipe->waiting_writers--; | |
5274f052 JA |
251 | } |
252 | ||
3a326a2c IM |
253 | if (pipe->inode) |
254 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
255 | |
256 | if (do_wakeup) { | |
c0bd1f65 | 257 | smp_mb(); |
3a326a2c IM |
258 | if (waitqueue_active(&pipe->wait)) |
259 | wake_up_interruptible(&pipe->wait); | |
260 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
261 | } |
262 | ||
912d35f8 JA |
263 | while (page_nr < spd->nr_pages) |
264 | page_cache_release(spd->pages[page_nr++]); | |
5274f052 JA |
265 | |
266 | return ret; | |
267 | } | |
268 | ||
3a326a2c | 269 | static int |
cbb7e577 JA |
270 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
271 | struct pipe_inode_info *pipe, size_t len, | |
272 | unsigned int flags) | |
5274f052 JA |
273 | { |
274 | struct address_space *mapping = in->f_mapping; | |
912d35f8 | 275 | unsigned int loff, nr_pages; |
16c523dd | 276 | struct page *pages[PIPE_BUFFERS]; |
912d35f8 | 277 | struct partial_page partial[PIPE_BUFFERS]; |
5274f052 | 278 | struct page *page; |
91ad66ef JA |
279 | pgoff_t index, end_index; |
280 | loff_t isize; | |
912d35f8 | 281 | size_t total_len; |
eb20796b | 282 | int error, page_nr; |
912d35f8 JA |
283 | struct splice_pipe_desc spd = { |
284 | .pages = pages, | |
285 | .partial = partial, | |
286 | .flags = flags, | |
287 | .ops = &page_cache_pipe_buf_ops, | |
288 | }; | |
5274f052 | 289 | |
cbb7e577 | 290 | index = *ppos >> PAGE_CACHE_SHIFT; |
912d35f8 JA |
291 | loff = *ppos & ~PAGE_CACHE_MASK; |
292 | nr_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
5274f052 JA |
293 | |
294 | if (nr_pages > PIPE_BUFFERS) | |
295 | nr_pages = PIPE_BUFFERS; | |
296 | ||
297 | /* | |
73d62d83 | 298 | * Initiate read-ahead on this page range. however, don't call into |
0b749ce3 JA |
299 | * read-ahead if this is a non-zero offset (we are likely doing small |
300 | * chunk splice and the page is already there) for a single page. | |
5274f052 | 301 | */ |
eb645a24 JA |
302 | if (!loff || nr_pages > 1) |
303 | page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages); | |
5274f052 | 304 | |
5274f052 | 305 | /* |
73d62d83 | 306 | * Now fill in the holes: |
5274f052 | 307 | */ |
7480a904 | 308 | error = 0; |
912d35f8 | 309 | total_len = 0; |
82aa5d61 | 310 | |
eb20796b JA |
311 | /* |
312 | * Lookup the (hopefully) full range of pages we need. | |
313 | */ | |
314 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); | |
82aa5d61 | 315 | |
eb20796b JA |
316 | /* |
317 | * If find_get_pages_contig() returned fewer pages than we needed, | |
318 | * allocate the rest. | |
319 | */ | |
320 | index += spd.nr_pages; | |
321 | while (spd.nr_pages < nr_pages) { | |
82aa5d61 | 322 | /* |
eb20796b JA |
323 | * Page could be there, find_get_pages_contig() breaks on |
324 | * the first hole. | |
5274f052 | 325 | */ |
7480a904 JA |
326 | page = find_get_page(mapping, index); |
327 | if (!page) { | |
7480a904 | 328 | /* |
eb20796b | 329 | * page didn't exist, allocate one. |
7480a904 JA |
330 | */ |
331 | page = page_cache_alloc_cold(mapping); | |
332 | if (!page) | |
333 | break; | |
334 | ||
335 | error = add_to_page_cache_lru(page, mapping, index, | |
eb20796b | 336 | mapping_gfp_mask(mapping)); |
7480a904 JA |
337 | if (unlikely(error)) { |
338 | page_cache_release(page); | |
339 | break; | |
340 | } | |
eb20796b JA |
341 | /* |
342 | * add_to_page_cache() locks the page, unlock it | |
343 | * to avoid convoluting the logic below even more. | |
344 | */ | |
345 | unlock_page(page); | |
7480a904 JA |
346 | } |
347 | ||
eb20796b JA |
348 | pages[spd.nr_pages++] = page; |
349 | index++; | |
350 | } | |
351 | ||
352 | /* | |
353 | * Now loop over the map and see if we need to start IO on any | |
354 | * pages, fill in the partial map, etc. | |
355 | */ | |
356 | index = *ppos >> PAGE_CACHE_SHIFT; | |
357 | nr_pages = spd.nr_pages; | |
358 | spd.nr_pages = 0; | |
359 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
360 | unsigned int this_len; | |
361 | ||
362 | if (!len) | |
363 | break; | |
364 | ||
365 | /* | |
366 | * this_len is the max we'll use from this page | |
367 | */ | |
368 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
369 | page = pages[page_nr]; | |
370 | ||
7480a904 JA |
371 | /* |
372 | * If the page isn't uptodate, we may need to start io on it | |
373 | */ | |
374 | if (!PageUptodate(page)) { | |
c4f895cb JA |
375 | /* |
376 | * If in nonblock mode then dont block on waiting | |
377 | * for an in-flight io page | |
378 | */ | |
379 | if (flags & SPLICE_F_NONBLOCK) | |
380 | break; | |
381 | ||
7480a904 JA |
382 | lock_page(page); |
383 | ||
384 | /* | |
385 | * page was truncated, stop here. if this isn't the | |
386 | * first page, we'll just complete what we already | |
387 | * added | |
388 | */ | |
389 | if (!page->mapping) { | |
390 | unlock_page(page); | |
7480a904 JA |
391 | break; |
392 | } | |
393 | /* | |
394 | * page was already under io and is now done, great | |
395 | */ | |
396 | if (PageUptodate(page)) { | |
397 | unlock_page(page); | |
398 | goto fill_it; | |
399 | } | |
5274f052 | 400 | |
7480a904 JA |
401 | /* |
402 | * need to read in the page | |
403 | */ | |
404 | error = mapping->a_ops->readpage(in, page); | |
5274f052 | 405 | if (unlikely(error)) { |
eb20796b JA |
406 | /* |
407 | * We really should re-lookup the page here, | |
408 | * but it complicates things a lot. Instead | |
409 | * lets just do what we already stored, and | |
410 | * we'll get it the next time we are called. | |
411 | */ | |
7480a904 | 412 | if (error == AOP_TRUNCATED_PAGE) |
eb20796b JA |
413 | error = 0; |
414 | ||
5274f052 JA |
415 | break; |
416 | } | |
91ad66ef JA |
417 | |
418 | /* | |
419 | * i_size must be checked after ->readpage(). | |
420 | */ | |
421 | isize = i_size_read(mapping->host); | |
422 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
eb20796b | 423 | if (unlikely(!isize || index > end_index)) |
91ad66ef | 424 | break; |
91ad66ef JA |
425 | |
426 | /* | |
427 | * if this is the last page, see if we need to shrink | |
428 | * the length and stop | |
429 | */ | |
430 | if (end_index == index) { | |
431 | loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK); | |
eb20796b | 432 | if (total_len + loff > isize) |
91ad66ef | 433 | break; |
91ad66ef JA |
434 | /* |
435 | * force quit after adding this page | |
436 | */ | |
eb20796b | 437 | len = this_len; |
82aa5d61 | 438 | this_len = min(this_len, loff); |
912d35f8 | 439 | loff = 0; |
91ad66ef | 440 | } |
5274f052 | 441 | } |
7480a904 | 442 | fill_it: |
eb20796b JA |
443 | partial[page_nr].offset = loff; |
444 | partial[page_nr].len = this_len; | |
82aa5d61 | 445 | len -= this_len; |
912d35f8 | 446 | total_len += this_len; |
91ad66ef | 447 | loff = 0; |
eb20796b JA |
448 | spd.nr_pages++; |
449 | index++; | |
5274f052 JA |
450 | } |
451 | ||
eb20796b JA |
452 | /* |
453 | * Release any pages at the end, if we quit early. 'i' is how far | |
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++]); | |
458 | ||
912d35f8 | 459 | if (spd.nr_pages) |
00522fb4 | 460 | return splice_to_pipe(pipe, &spd); |
5274f052 | 461 | |
7480a904 | 462 | return error; |
5274f052 JA |
463 | } |
464 | ||
83f9135b JA |
465 | /** |
466 | * generic_file_splice_read - splice data from file to a pipe | |
467 | * @in: file to splice from | |
468 | * @pipe: pipe to splice to | |
469 | * @len: number of bytes to splice | |
470 | * @flags: splice modifier flags | |
471 | * | |
472 | * Will read pages from given file and fill them into a pipe. | |
83f9135b | 473 | */ |
cbb7e577 JA |
474 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
475 | struct pipe_inode_info *pipe, size_t len, | |
476 | unsigned int flags) | |
5274f052 JA |
477 | { |
478 | ssize_t spliced; | |
479 | int ret; | |
480 | ||
481 | ret = 0; | |
482 | spliced = 0; | |
3a326a2c | 483 | |
5274f052 | 484 | while (len) { |
cbb7e577 | 485 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
5274f052 | 486 | |
c4f895cb | 487 | if (ret < 0) |
5274f052 | 488 | break; |
c4f895cb JA |
489 | else if (!ret) { |
490 | if (spliced) | |
491 | break; | |
492 | if (flags & SPLICE_F_NONBLOCK) { | |
493 | ret = -EAGAIN; | |
494 | break; | |
495 | } | |
496 | } | |
5274f052 | 497 | |
cbb7e577 | 498 | *ppos += ret; |
5274f052 JA |
499 | len -= ret; |
500 | spliced += ret; | |
501 | } | |
502 | ||
503 | if (spliced) | |
504 | return spliced; | |
505 | ||
506 | return ret; | |
507 | } | |
508 | ||
059a8f37 JA |
509 | EXPORT_SYMBOL(generic_file_splice_read); |
510 | ||
5274f052 | 511 | /* |
4f6f0bd2 | 512 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 513 | * using sendpage(). Return the number of bytes sent. |
5274f052 JA |
514 | */ |
515 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
516 | struct pipe_buffer *buf, struct splice_desc *sd) | |
517 | { | |
518 | struct file *file = sd->file; | |
519 | loff_t pos = sd->pos; | |
5274f052 JA |
520 | ssize_t ret; |
521 | void *ptr; | |
b2b39fa4 | 522 | int more; |
5274f052 JA |
523 | |
524 | /* | |
73d62d83 | 525 | * Sub-optimal, but we are limited by the pipe ->map. We don't |
5274f052 JA |
526 | * need a kmap'ed buffer here, we just want to make sure we |
527 | * have the page pinned if the pipe page originates from the | |
73d62d83 | 528 | * page cache. |
5274f052 JA |
529 | */ |
530 | ptr = buf->ops->map(file, info, buf); | |
531 | if (IS_ERR(ptr)) | |
532 | return PTR_ERR(ptr); | |
533 | ||
b2b39fa4 | 534 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
5274f052 | 535 | |
016b661e JA |
536 | ret = file->f_op->sendpage(file, buf->page, buf->offset, sd->len, |
537 | &pos, more); | |
5274f052 JA |
538 | |
539 | buf->ops->unmap(info, buf); | |
016b661e | 540 | return ret; |
5274f052 JA |
541 | } |
542 | ||
543 | /* | |
544 | * This is a little more tricky than the file -> pipe splicing. There are | |
545 | * basically three cases: | |
546 | * | |
547 | * - Destination page already exists in the address space and there | |
548 | * are users of it. For that case we have no other option that | |
549 | * copying the data. Tough luck. | |
550 | * - Destination page already exists in the address space, but there | |
551 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
552 | * through to last case. | |
553 | * - Destination page does not exist, we can add the pipe page to | |
554 | * the page cache and avoid the copy. | |
555 | * | |
83f9135b JA |
556 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
557 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
558 | * file address space page cache. This is possible if no one else has | |
559 | * the pipe page referenced outside of the pipe and page cache. If | |
560 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
561 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 JA |
562 | */ |
563 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
564 | struct splice_desc *sd) | |
565 | { | |
566 | struct file *file = sd->file; | |
567 | struct address_space *mapping = file->f_mapping; | |
3e7ee3e7 | 568 | gfp_t gfp_mask = mapping_gfp_mask(mapping); |
016b661e | 569 | unsigned int offset, this_len; |
5274f052 | 570 | struct page *page; |
5274f052 | 571 | pgoff_t index; |
5abc97aa | 572 | char *src; |
3e7ee3e7 | 573 | int ret; |
5274f052 JA |
574 | |
575 | /* | |
49d0b21b | 576 | * make sure the data in this buffer is uptodate |
5274f052 JA |
577 | */ |
578 | src = buf->ops->map(file, info, buf); | |
579 | if (IS_ERR(src)) | |
580 | return PTR_ERR(src); | |
581 | ||
582 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
583 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
584 | ||
016b661e JA |
585 | this_len = sd->len; |
586 | if (this_len + offset > PAGE_CACHE_SIZE) | |
587 | this_len = PAGE_CACHE_SIZE - offset; | |
588 | ||
5274f052 | 589 | /* |
73d62d83 | 590 | * Reuse buf page, if SPLICE_F_MOVE is set. |
5274f052 | 591 | */ |
5abc97aa | 592 | if (sd->flags & SPLICE_F_MOVE) { |
83f9135b JA |
593 | /* |
594 | * If steal succeeds, buf->page is now pruned from the vm | |
9e0267c2 JA |
595 | * side (LRU and page cache) and we can reuse it. The page |
596 | * will also be looked on successful return. | |
83f9135b | 597 | */ |
5abc97aa JA |
598 | if (buf->ops->steal(info, buf)) |
599 | goto find_page; | |
600 | ||
601 | page = buf->page; | |
46e678c9 JA |
602 | if (add_to_page_cache(page, mapping, index, gfp_mask)) { |
603 | unlock_page(page); | |
5abc97aa | 604 | goto find_page; |
46e678c9 | 605 | } |
3e7ee3e7 JA |
606 | |
607 | if (!(buf->flags & PIPE_BUF_FLAG_LRU)) | |
608 | lru_cache_add(page); | |
5abc97aa JA |
609 | } else { |
610 | find_page: | |
9e0267c2 JA |
611 | page = find_lock_page(mapping, index); |
612 | if (!page) { | |
613 | ret = -ENOMEM; | |
614 | page = page_cache_alloc_cold(mapping); | |
615 | if (unlikely(!page)) | |
616 | goto out_nomem; | |
617 | ||
618 | /* | |
619 | * This will also lock the page | |
620 | */ | |
621 | ret = add_to_page_cache_lru(page, mapping, index, | |
622 | gfp_mask); | |
623 | if (unlikely(ret)) | |
624 | goto out; | |
625 | } | |
5abc97aa JA |
626 | |
627 | /* | |
9e0267c2 JA |
628 | * We get here with the page locked. If the page is also |
629 | * uptodate, we don't need to do more. If it isn't, we | |
630 | * may need to bring it in if we are not going to overwrite | |
631 | * the full page. | |
5abc97aa JA |
632 | */ |
633 | if (!PageUptodate(page)) { | |
016b661e | 634 | if (this_len < PAGE_CACHE_SIZE) { |
5abc97aa JA |
635 | ret = mapping->a_ops->readpage(file, page); |
636 | if (unlikely(ret)) | |
637 | goto out; | |
638 | ||
639 | lock_page(page); | |
640 | ||
641 | if (!PageUptodate(page)) { | |
642 | /* | |
73d62d83 | 643 | * Page got invalidated, repeat. |
5abc97aa JA |
644 | */ |
645 | if (!page->mapping) { | |
646 | unlock_page(page); | |
647 | page_cache_release(page); | |
648 | goto find_page; | |
649 | } | |
650 | ret = -EIO; | |
651 | goto out; | |
5274f052 | 652 | } |
9e0267c2 | 653 | } else |
5abc97aa | 654 | SetPageUptodate(page); |
5274f052 JA |
655 | } |
656 | } | |
657 | ||
016b661e | 658 | ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len); |
4f6f0bd2 JA |
659 | if (ret == AOP_TRUNCATED_PAGE) { |
660 | page_cache_release(page); | |
661 | goto find_page; | |
662 | } else if (ret) | |
5274f052 JA |
663 | goto out; |
664 | ||
3e7ee3e7 | 665 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { |
5abc97aa JA |
666 | char *dst = kmap_atomic(page, KM_USER0); |
667 | ||
016b661e | 668 | memcpy(dst + offset, src + buf->offset, this_len); |
5abc97aa JA |
669 | flush_dcache_page(page); |
670 | kunmap_atomic(dst, KM_USER0); | |
671 | } | |
5274f052 | 672 | |
016b661e | 673 | ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len); |
4f6f0bd2 JA |
674 | if (ret == AOP_TRUNCATED_PAGE) { |
675 | page_cache_release(page); | |
676 | goto find_page; | |
677 | } else if (ret) | |
5274f052 JA |
678 | goto out; |
679 | ||
016b661e JA |
680 | /* |
681 | * Return the number of bytes written. | |
682 | */ | |
683 | ret = this_len; | |
c7f21e4f | 684 | mark_page_accessed(page); |
4f6f0bd2 | 685 | balance_dirty_pages_ratelimited(mapping); |
5274f052 | 686 | out: |
9e0267c2 | 687 | if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) |
5abc97aa | 688 | page_cache_release(page); |
9e0267c2 JA |
689 | |
690 | unlock_page(page); | |
9aefe431 | 691 | out_nomem: |
5274f052 JA |
692 | buf->ops->unmap(info, buf); |
693 | return ret; | |
694 | } | |
695 | ||
83f9135b JA |
696 | /* |
697 | * Pipe input worker. Most of this logic works like a regular pipe, the | |
698 | * key here is the 'actor' worker passed in that actually moves the data | |
699 | * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. | |
700 | */ | |
00522fb4 JA |
701 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
702 | loff_t *ppos, size_t len, unsigned int flags, | |
703 | splice_actor *actor) | |
5274f052 | 704 | { |
5274f052 JA |
705 | int ret, do_wakeup, err; |
706 | struct splice_desc sd; | |
707 | ||
708 | ret = 0; | |
709 | do_wakeup = 0; | |
710 | ||
711 | sd.total_len = len; | |
712 | sd.flags = flags; | |
713 | sd.file = out; | |
cbb7e577 | 714 | sd.pos = *ppos; |
5274f052 | 715 | |
3a326a2c IM |
716 | if (pipe->inode) |
717 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 718 | |
5274f052 | 719 | for (;;) { |
6f767b04 JA |
720 | if (pipe->nrbufs) { |
721 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
5274f052 JA |
722 | struct pipe_buf_operations *ops = buf->ops; |
723 | ||
724 | sd.len = buf->len; | |
725 | if (sd.len > sd.total_len) | |
726 | sd.len = sd.total_len; | |
727 | ||
3a326a2c | 728 | err = actor(pipe, buf, &sd); |
016b661e | 729 | if (err <= 0) { |
5274f052 JA |
730 | if (!ret && err != -ENODATA) |
731 | ret = err; | |
732 | ||
733 | break; | |
734 | } | |
735 | ||
016b661e JA |
736 | ret += err; |
737 | buf->offset += err; | |
738 | buf->len -= err; | |
739 | ||
740 | sd.len -= err; | |
741 | sd.pos += err; | |
742 | sd.total_len -= err; | |
743 | if (sd.len) | |
744 | continue; | |
73d62d83 | 745 | |
5274f052 JA |
746 | if (!buf->len) { |
747 | buf->ops = NULL; | |
3a326a2c | 748 | ops->release(pipe, buf); |
6f767b04 JA |
749 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
750 | pipe->nrbufs--; | |
751 | if (pipe->inode) | |
752 | do_wakeup = 1; | |
5274f052 JA |
753 | } |
754 | ||
5274f052 JA |
755 | if (!sd.total_len) |
756 | break; | |
757 | } | |
758 | ||
6f767b04 | 759 | if (pipe->nrbufs) |
5274f052 | 760 | continue; |
3a326a2c | 761 | if (!pipe->writers) |
5274f052 | 762 | break; |
3a326a2c | 763 | if (!pipe->waiting_writers) { |
5274f052 JA |
764 | if (ret) |
765 | break; | |
766 | } | |
767 | ||
29e35094 LT |
768 | if (flags & SPLICE_F_NONBLOCK) { |
769 | if (!ret) | |
770 | ret = -EAGAIN; | |
771 | break; | |
772 | } | |
773 | ||
5274f052 JA |
774 | if (signal_pending(current)) { |
775 | if (!ret) | |
776 | ret = -ERESTARTSYS; | |
777 | break; | |
778 | } | |
779 | ||
780 | if (do_wakeup) { | |
c0bd1f65 | 781 | smp_mb(); |
3a326a2c IM |
782 | if (waitqueue_active(&pipe->wait)) |
783 | wake_up_interruptible_sync(&pipe->wait); | |
784 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
785 | do_wakeup = 0; |
786 | } | |
787 | ||
3a326a2c | 788 | pipe_wait(pipe); |
5274f052 JA |
789 | } |
790 | ||
3a326a2c IM |
791 | if (pipe->inode) |
792 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
793 | |
794 | if (do_wakeup) { | |
c0bd1f65 | 795 | smp_mb(); |
3a326a2c IM |
796 | if (waitqueue_active(&pipe->wait)) |
797 | wake_up_interruptible(&pipe->wait); | |
798 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
799 | } |
800 | ||
5274f052 | 801 | return ret; |
5274f052 JA |
802 | } |
803 | ||
83f9135b JA |
804 | /** |
805 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 806 | * @pipe: pipe info |
83f9135b JA |
807 | * @out: file to write to |
808 | * @len: number of bytes to splice | |
809 | * @flags: splice modifier flags | |
810 | * | |
811 | * Will either move or copy pages (determined by @flags options) from | |
812 | * the given pipe inode to the given file. | |
813 | * | |
814 | */ | |
3a326a2c IM |
815 | ssize_t |
816 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
cbb7e577 | 817 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 818 | { |
4f6f0bd2 | 819 | struct address_space *mapping = out->f_mapping; |
3a326a2c IM |
820 | ssize_t ret; |
821 | ||
00522fb4 | 822 | ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file); |
a4514ebd | 823 | if (ret > 0) { |
4f6f0bd2 | 824 | struct inode *inode = mapping->host; |
4f6f0bd2 | 825 | |
a4514ebd JA |
826 | *ppos += ret; |
827 | ||
828 | /* | |
829 | * If file or inode is SYNC and we actually wrote some data, | |
830 | * sync it. | |
831 | */ | |
832 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
833 | int err; | |
834 | ||
835 | mutex_lock(&inode->i_mutex); | |
836 | err = generic_osync_inode(inode, mapping, | |
837 | OSYNC_METADATA|OSYNC_DATA); | |
838 | mutex_unlock(&inode->i_mutex); | |
4f6f0bd2 | 839 | |
a4514ebd JA |
840 | if (err) |
841 | ret = err; | |
842 | } | |
4f6f0bd2 JA |
843 | } |
844 | ||
845 | return ret; | |
5274f052 JA |
846 | } |
847 | ||
059a8f37 JA |
848 | EXPORT_SYMBOL(generic_file_splice_write); |
849 | ||
83f9135b JA |
850 | /** |
851 | * generic_splice_sendpage - splice data from a pipe to a socket | |
852 | * @inode: pipe inode | |
853 | * @out: socket to write to | |
854 | * @len: number of bytes to splice | |
855 | * @flags: splice modifier flags | |
856 | * | |
857 | * Will send @len bytes from the pipe to a network socket. No data copying | |
858 | * is involved. | |
859 | * | |
860 | */ | |
3a326a2c | 861 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 862 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 863 | { |
00522fb4 | 864 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
865 | } |
866 | ||
059a8f37 | 867 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 868 | |
83f9135b JA |
869 | /* |
870 | * Attempt to initiate a splice from pipe to file. | |
871 | */ | |
3a326a2c | 872 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 873 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 874 | { |
5274f052 JA |
875 | int ret; |
876 | ||
49570e9b | 877 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
878 | return -EINVAL; |
879 | ||
49570e9b | 880 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
881 | return -EBADF; |
882 | ||
cbb7e577 | 883 | ret = rw_verify_area(WRITE, out, ppos, len); |
5274f052 JA |
884 | if (unlikely(ret < 0)) |
885 | return ret; | |
886 | ||
cbb7e577 | 887 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
888 | } |
889 | ||
83f9135b JA |
890 | /* |
891 | * Attempt to initiate a splice from a file to a pipe. | |
892 | */ | |
cbb7e577 JA |
893 | static long do_splice_to(struct file *in, loff_t *ppos, |
894 | struct pipe_inode_info *pipe, size_t len, | |
895 | unsigned int flags) | |
5274f052 | 896 | { |
cbb7e577 | 897 | loff_t isize, left; |
5274f052 JA |
898 | int ret; |
899 | ||
49570e9b | 900 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
901 | return -EINVAL; |
902 | ||
49570e9b | 903 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
904 | return -EBADF; |
905 | ||
cbb7e577 | 906 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
907 | if (unlikely(ret < 0)) |
908 | return ret; | |
909 | ||
910 | isize = i_size_read(in->f_mapping->host); | |
cbb7e577 | 911 | if (unlikely(*ppos >= isize)) |
5274f052 JA |
912 | return 0; |
913 | ||
cbb7e577 | 914 | left = isize - *ppos; |
49570e9b | 915 | if (unlikely(left < len)) |
5274f052 JA |
916 | len = left; |
917 | ||
cbb7e577 | 918 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 JA |
919 | } |
920 | ||
cbb7e577 JA |
921 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
922 | size_t len, unsigned int flags) | |
b92ce558 JA |
923 | { |
924 | struct pipe_inode_info *pipe; | |
925 | long ret, bytes; | |
cbb7e577 | 926 | loff_t out_off; |
b92ce558 JA |
927 | umode_t i_mode; |
928 | int i; | |
929 | ||
930 | /* | |
931 | * We require the input being a regular file, as we don't want to | |
932 | * randomly drop data for eg socket -> socket splicing. Use the | |
933 | * piped splicing for that! | |
934 | */ | |
935 | i_mode = in->f_dentry->d_inode->i_mode; | |
936 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
937 | return -EINVAL; | |
938 | ||
939 | /* | |
940 | * neither in nor out is a pipe, setup an internal pipe attached to | |
941 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
942 | */ | |
943 | pipe = current->splice_pipe; | |
49570e9b | 944 | if (unlikely(!pipe)) { |
b92ce558 JA |
945 | pipe = alloc_pipe_info(NULL); |
946 | if (!pipe) | |
947 | return -ENOMEM; | |
948 | ||
949 | /* | |
950 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 951 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
952 | * PIPE_READERS appropriately. |
953 | */ | |
954 | pipe->readers = 1; | |
955 | ||
956 | current->splice_pipe = pipe; | |
957 | } | |
958 | ||
959 | /* | |
73d62d83 | 960 | * Do the splice. |
b92ce558 JA |
961 | */ |
962 | ret = 0; | |
963 | bytes = 0; | |
cbb7e577 | 964 | out_off = 0; |
b92ce558 JA |
965 | |
966 | while (len) { | |
967 | size_t read_len, max_read_len; | |
968 | ||
969 | /* | |
970 | * Do at most PIPE_BUFFERS pages worth of transfer: | |
971 | */ | |
972 | max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); | |
973 | ||
cbb7e577 | 974 | ret = do_splice_to(in, ppos, pipe, max_read_len, flags); |
b92ce558 JA |
975 | if (unlikely(ret < 0)) |
976 | goto out_release; | |
977 | ||
978 | read_len = ret; | |
979 | ||
980 | /* | |
981 | * NOTE: nonblocking mode only applies to the input. We | |
982 | * must not do the output in nonblocking mode as then we | |
983 | * could get stuck data in the internal pipe: | |
984 | */ | |
cbb7e577 | 985 | ret = do_splice_from(pipe, out, &out_off, read_len, |
b92ce558 JA |
986 | flags & ~SPLICE_F_NONBLOCK); |
987 | if (unlikely(ret < 0)) | |
988 | goto out_release; | |
989 | ||
990 | bytes += ret; | |
991 | len -= ret; | |
992 | ||
993 | /* | |
994 | * In nonblocking mode, if we got back a short read then | |
995 | * that was due to either an IO error or due to the | |
996 | * pagecache entry not being there. In the IO error case | |
997 | * the _next_ splice attempt will produce a clean IO error | |
998 | * return value (not a short read), so in both cases it's | |
999 | * correct to break out of the loop here: | |
1000 | */ | |
1001 | if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) | |
1002 | break; | |
1003 | } | |
1004 | ||
1005 | pipe->nrbufs = pipe->curbuf = 0; | |
1006 | ||
1007 | return bytes; | |
1008 | ||
1009 | out_release: | |
1010 | /* | |
1011 | * If we did an incomplete transfer we must release | |
1012 | * the pipe buffers in question: | |
1013 | */ | |
1014 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
1015 | struct pipe_buffer *buf = pipe->bufs + i; | |
1016 | ||
1017 | if (buf->ops) { | |
1018 | buf->ops->release(pipe, buf); | |
1019 | buf->ops = NULL; | |
1020 | } | |
1021 | } | |
1022 | pipe->nrbufs = pipe->curbuf = 0; | |
1023 | ||
1024 | /* | |
1025 | * If we transferred some data, return the number of bytes: | |
1026 | */ | |
1027 | if (bytes > 0) | |
1028 | return bytes; | |
1029 | ||
1030 | return ret; | |
1031 | } | |
1032 | ||
1033 | EXPORT_SYMBOL(do_splice_direct); | |
1034 | ||
83f9135b JA |
1035 | /* |
1036 | * Determine where to splice to/from. | |
1037 | */ | |
529565dc IM |
1038 | static long do_splice(struct file *in, loff_t __user *off_in, |
1039 | struct file *out, loff_t __user *off_out, | |
1040 | size_t len, unsigned int flags) | |
5274f052 | 1041 | { |
3a326a2c | 1042 | struct pipe_inode_info *pipe; |
cbb7e577 | 1043 | loff_t offset, *off; |
a4514ebd | 1044 | long ret; |
5274f052 | 1045 | |
3a326a2c | 1046 | pipe = in->f_dentry->d_inode->i_pipe; |
529565dc IM |
1047 | if (pipe) { |
1048 | if (off_in) | |
1049 | return -ESPIPE; | |
b92ce558 JA |
1050 | if (off_out) { |
1051 | if (out->f_op->llseek == no_llseek) | |
1052 | return -EINVAL; | |
cbb7e577 | 1053 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1054 | return -EFAULT; |
cbb7e577 JA |
1055 | off = &offset; |
1056 | } else | |
1057 | off = &out->f_pos; | |
529565dc | 1058 | |
a4514ebd JA |
1059 | ret = do_splice_from(pipe, out, off, len, flags); |
1060 | ||
1061 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
1062 | ret = -EFAULT; | |
1063 | ||
1064 | return ret; | |
529565dc | 1065 | } |
5274f052 | 1066 | |
3a326a2c | 1067 | pipe = out->f_dentry->d_inode->i_pipe; |
529565dc IM |
1068 | if (pipe) { |
1069 | if (off_out) | |
1070 | return -ESPIPE; | |
b92ce558 JA |
1071 | if (off_in) { |
1072 | if (in->f_op->llseek == no_llseek) | |
1073 | return -EINVAL; | |
cbb7e577 | 1074 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1075 | return -EFAULT; |
cbb7e577 JA |
1076 | off = &offset; |
1077 | } else | |
1078 | off = &in->f_pos; | |
529565dc | 1079 | |
a4514ebd JA |
1080 | ret = do_splice_to(in, off, pipe, len, flags); |
1081 | ||
1082 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
1083 | ret = -EFAULT; | |
1084 | ||
1085 | return ret; | |
529565dc | 1086 | } |
5274f052 JA |
1087 | |
1088 | return -EINVAL; | |
1089 | } | |
1090 | ||
912d35f8 JA |
1091 | /* |
1092 | * Map an iov into an array of pages and offset/length tupples. With the | |
1093 | * partial_page structure, we can map several non-contiguous ranges into | |
1094 | * our ones pages[] map instead of splitting that operation into pieces. | |
1095 | * Could easily be exported as a generic helper for other users, in which | |
1096 | * case one would probably want to add a 'max_nr_pages' parameter as well. | |
1097 | */ | |
1098 | static int get_iovec_page_array(const struct iovec __user *iov, | |
1099 | unsigned int nr_vecs, struct page **pages, | |
1100 | struct partial_page *partial) | |
1101 | { | |
1102 | int buffers = 0, error = 0; | |
1103 | ||
1104 | /* | |
1105 | * It's ok to take the mmap_sem for reading, even | |
1106 | * across a "get_user()". | |
1107 | */ | |
1108 | down_read(¤t->mm->mmap_sem); | |
1109 | ||
1110 | while (nr_vecs) { | |
1111 | unsigned long off, npages; | |
1112 | void __user *base; | |
1113 | size_t len; | |
1114 | int i; | |
1115 | ||
1116 | /* | |
1117 | * Get user address base and length for this iovec. | |
1118 | */ | |
1119 | error = get_user(base, &iov->iov_base); | |
1120 | if (unlikely(error)) | |
1121 | break; | |
1122 | error = get_user(len, &iov->iov_len); | |
1123 | if (unlikely(error)) | |
1124 | break; | |
1125 | ||
1126 | /* | |
1127 | * Sanity check this iovec. 0 read succeeds. | |
1128 | */ | |
1129 | if (unlikely(!len)) | |
1130 | break; | |
1131 | error = -EFAULT; | |
1132 | if (unlikely(!base)) | |
1133 | break; | |
1134 | ||
1135 | /* | |
1136 | * Get this base offset and number of pages, then map | |
1137 | * in the user pages. | |
1138 | */ | |
1139 | off = (unsigned long) base & ~PAGE_MASK; | |
1140 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
1141 | if (npages > PIPE_BUFFERS - buffers) | |
1142 | npages = PIPE_BUFFERS - buffers; | |
1143 | ||
1144 | error = get_user_pages(current, current->mm, | |
1145 | (unsigned long) base, npages, 0, 0, | |
1146 | &pages[buffers], NULL); | |
1147 | ||
1148 | if (unlikely(error <= 0)) | |
1149 | break; | |
1150 | ||
1151 | /* | |
1152 | * Fill this contiguous range into the partial page map. | |
1153 | */ | |
1154 | for (i = 0; i < error; i++) { | |
1155 | const int plen = min_t(size_t, len, PAGE_SIZE) - off; | |
1156 | ||
1157 | partial[buffers].offset = off; | |
1158 | partial[buffers].len = plen; | |
1159 | ||
1160 | off = 0; | |
1161 | len -= plen; | |
1162 | buffers++; | |
1163 | } | |
1164 | ||
1165 | /* | |
1166 | * We didn't complete this iov, stop here since it probably | |
1167 | * means we have to move some of this into a pipe to | |
1168 | * be able to continue. | |
1169 | */ | |
1170 | if (len) | |
1171 | break; | |
1172 | ||
1173 | /* | |
1174 | * Don't continue if we mapped fewer pages than we asked for, | |
1175 | * or if we mapped the max number of pages that we have | |
1176 | * room for. | |
1177 | */ | |
1178 | if (error < npages || buffers == PIPE_BUFFERS) | |
1179 | break; | |
1180 | ||
1181 | nr_vecs--; | |
1182 | iov++; | |
1183 | } | |
1184 | ||
1185 | up_read(¤t->mm->mmap_sem); | |
1186 | ||
1187 | if (buffers) | |
1188 | return buffers; | |
1189 | ||
1190 | return error; | |
1191 | } | |
1192 | ||
1193 | /* | |
1194 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1195 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1196 | * to file). In both cases the output is a pipe, naturally. | |
1197 | * | |
1198 | * Note that vmsplice only supports splicing _from_ user memory to a pipe, | |
1199 | * not the other way around. Splicing from user memory is a simple operation | |
1200 | * that can be supported without any funky alignment restrictions or nasty | |
1201 | * vm tricks. We simply map in the user memory and fill them into a pipe. | |
1202 | * The reverse isn't quite as easy, though. There are two possible solutions | |
1203 | * for that: | |
1204 | * | |
1205 | * - memcpy() the data internally, at which point we might as well just | |
1206 | * do a regular read() on the buffer anyway. | |
1207 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1208 | * has restriction limitations on both ends of the pipe). | |
1209 | * | |
1210 | * Alas, it isn't here. | |
1211 | * | |
1212 | */ | |
1213 | static long do_vmsplice(struct file *file, const struct iovec __user *iov, | |
1214 | unsigned long nr_segs, unsigned int flags) | |
1215 | { | |
1216 | struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe; | |
1217 | struct page *pages[PIPE_BUFFERS]; | |
1218 | struct partial_page partial[PIPE_BUFFERS]; | |
1219 | struct splice_pipe_desc spd = { | |
1220 | .pages = pages, | |
1221 | .partial = partial, | |
1222 | .flags = flags, | |
1223 | .ops = &user_page_pipe_buf_ops, | |
1224 | }; | |
1225 | ||
1226 | if (unlikely(!pipe)) | |
1227 | return -EBADF; | |
1228 | if (unlikely(nr_segs > UIO_MAXIOV)) | |
1229 | return -EINVAL; | |
1230 | else if (unlikely(!nr_segs)) | |
1231 | return 0; | |
1232 | ||
1233 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial); | |
1234 | if (spd.nr_pages <= 0) | |
1235 | return spd.nr_pages; | |
1236 | ||
00522fb4 | 1237 | return splice_to_pipe(pipe, &spd); |
912d35f8 JA |
1238 | } |
1239 | ||
1240 | asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov, | |
1241 | unsigned long nr_segs, unsigned int flags) | |
1242 | { | |
1243 | struct file *file; | |
1244 | long error; | |
1245 | int fput; | |
1246 | ||
1247 | error = -EBADF; | |
1248 | file = fget_light(fd, &fput); | |
1249 | if (file) { | |
1250 | if (file->f_mode & FMODE_WRITE) | |
1251 | error = do_vmsplice(file, iov, nr_segs, flags); | |
1252 | ||
1253 | fput_light(file, fput); | |
1254 | } | |
1255 | ||
1256 | return error; | |
1257 | } | |
1258 | ||
529565dc IM |
1259 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
1260 | int fd_out, loff_t __user *off_out, | |
1261 | size_t len, unsigned int flags) | |
5274f052 JA |
1262 | { |
1263 | long error; | |
1264 | struct file *in, *out; | |
1265 | int fput_in, fput_out; | |
1266 | ||
1267 | if (unlikely(!len)) | |
1268 | return 0; | |
1269 | ||
1270 | error = -EBADF; | |
529565dc | 1271 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
1272 | if (in) { |
1273 | if (in->f_mode & FMODE_READ) { | |
529565dc | 1274 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
1275 | if (out) { |
1276 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
1277 | error = do_splice(in, off_in, |
1278 | out, off_out, | |
1279 | len, flags); | |
5274f052 JA |
1280 | fput_light(out, fput_out); |
1281 | } | |
1282 | } | |
1283 | ||
1284 | fput_light(in, fput_in); | |
1285 | } | |
1286 | ||
1287 | return error; | |
1288 | } | |
70524490 JA |
1289 | |
1290 | /* | |
1291 | * Link contents of ipipe to opipe. | |
1292 | */ | |
1293 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1294 | struct pipe_inode_info *opipe, | |
1295 | size_t len, unsigned int flags) | |
1296 | { | |
1297 | struct pipe_buffer *ibuf, *obuf; | |
2a27250e JA |
1298 | int ret, do_wakeup, i, ipipe_first; |
1299 | ||
1300 | ret = do_wakeup = ipipe_first = 0; | |
70524490 JA |
1301 | |
1302 | /* | |
1303 | * Potential ABBA deadlock, work around it by ordering lock | |
1304 | * grabbing by inode address. Otherwise two different processes | |
1305 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1306 | */ | |
1307 | if (ipipe->inode < opipe->inode) { | |
2a27250e | 1308 | ipipe_first = 1; |
70524490 JA |
1309 | mutex_lock(&ipipe->inode->i_mutex); |
1310 | mutex_lock(&opipe->inode->i_mutex); | |
1311 | } else { | |
1312 | mutex_lock(&opipe->inode->i_mutex); | |
1313 | mutex_lock(&ipipe->inode->i_mutex); | |
1314 | } | |
1315 | ||
1316 | for (i = 0;; i++) { | |
1317 | if (!opipe->readers) { | |
1318 | send_sig(SIGPIPE, current, 0); | |
1319 | if (!ret) | |
1320 | ret = -EPIPE; | |
1321 | break; | |
1322 | } | |
1323 | if (ipipe->nrbufs - i) { | |
1324 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); | |
1325 | ||
1326 | /* | |
1327 | * If we have room, fill this buffer | |
1328 | */ | |
1329 | if (opipe->nrbufs < PIPE_BUFFERS) { | |
1330 | int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); | |
1331 | ||
1332 | /* | |
1333 | * Get a reference to this pipe buffer, | |
1334 | * so we can copy the contents over. | |
1335 | */ | |
1336 | ibuf->ops->get(ipipe, ibuf); | |
1337 | ||
1338 | obuf = opipe->bufs + nbuf; | |
1339 | *obuf = *ibuf; | |
1340 | ||
1341 | if (obuf->len > len) | |
1342 | obuf->len = len; | |
1343 | ||
1344 | opipe->nrbufs++; | |
1345 | do_wakeup = 1; | |
1346 | ret += obuf->len; | |
1347 | len -= obuf->len; | |
1348 | ||
1349 | if (!len) | |
1350 | break; | |
1351 | if (opipe->nrbufs < PIPE_BUFFERS) | |
1352 | continue; | |
1353 | } | |
1354 | ||
1355 | /* | |
1356 | * We have input available, but no output room. | |
2a27250e JA |
1357 | * If we already copied data, return that. If we |
1358 | * need to drop the opipe lock, it must be ordered | |
1359 | * last to avoid deadlocks. | |
70524490 | 1360 | */ |
2a27250e | 1361 | if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) { |
70524490 JA |
1362 | if (!ret) |
1363 | ret = -EAGAIN; | |
1364 | break; | |
1365 | } | |
1366 | if (signal_pending(current)) { | |
1367 | if (!ret) | |
1368 | ret = -ERESTARTSYS; | |
1369 | break; | |
1370 | } | |
1371 | if (do_wakeup) { | |
1372 | smp_mb(); | |
1373 | if (waitqueue_active(&opipe->wait)) | |
1374 | wake_up_interruptible(&opipe->wait); | |
1375 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1376 | do_wakeup = 0; | |
1377 | } | |
1378 | ||
1379 | opipe->waiting_writers++; | |
1380 | pipe_wait(opipe); | |
1381 | opipe->waiting_writers--; | |
1382 | continue; | |
1383 | } | |
1384 | ||
1385 | /* | |
1386 | * No input buffers, do the usual checks for available | |
1387 | * writers and blocking and wait if necessary | |
1388 | */ | |
1389 | if (!ipipe->writers) | |
1390 | break; | |
1391 | if (!ipipe->waiting_writers) { | |
1392 | if (ret) | |
1393 | break; | |
1394 | } | |
2a27250e JA |
1395 | /* |
1396 | * pipe_wait() drops the ipipe mutex. To avoid deadlocks | |
1397 | * with another process, we can only safely do that if | |
1398 | * the ipipe lock is ordered last. | |
1399 | */ | |
1400 | if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) { | |
70524490 JA |
1401 | if (!ret) |
1402 | ret = -EAGAIN; | |
1403 | break; | |
1404 | } | |
1405 | if (signal_pending(current)) { | |
1406 | if (!ret) | |
1407 | ret = -ERESTARTSYS; | |
1408 | break; | |
1409 | } | |
1410 | ||
1411 | if (waitqueue_active(&ipipe->wait)) | |
1412 | wake_up_interruptible_sync(&ipipe->wait); | |
1413 | kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT); | |
1414 | ||
1415 | pipe_wait(ipipe); | |
1416 | } | |
1417 | ||
1418 | mutex_unlock(&ipipe->inode->i_mutex); | |
1419 | mutex_unlock(&opipe->inode->i_mutex); | |
1420 | ||
1421 | if (do_wakeup) { | |
1422 | smp_mb(); | |
1423 | if (waitqueue_active(&opipe->wait)) | |
1424 | wake_up_interruptible(&opipe->wait); | |
1425 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1426 | } | |
1427 | ||
1428 | return ret; | |
1429 | } | |
1430 | ||
1431 | /* | |
1432 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1433 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1434 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1435 | * applicable one is SPLICE_F_NONBLOCK. | |
1436 | */ | |
1437 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1438 | unsigned int flags) | |
1439 | { | |
1440 | struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe; | |
1441 | struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe; | |
1442 | ||
1443 | /* | |
1444 | * Link ipipe to the two output pipes, consuming as we go along. | |
1445 | */ | |
1446 | if (ipipe && opipe) | |
1447 | return link_pipe(ipipe, opipe, len, flags); | |
1448 | ||
1449 | return -EINVAL; | |
1450 | } | |
1451 | ||
1452 | asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) | |
1453 | { | |
1454 | struct file *in; | |
1455 | int error, fput_in; | |
1456 | ||
1457 | if (unlikely(!len)) | |
1458 | return 0; | |
1459 | ||
1460 | error = -EBADF; | |
1461 | in = fget_light(fdin, &fput_in); | |
1462 | if (in) { | |
1463 | if (in->f_mode & FMODE_READ) { | |
1464 | int fput_out; | |
1465 | struct file *out = fget_light(fdout, &fput_out); | |
1466 | ||
1467 | if (out) { | |
1468 | if (out->f_mode & FMODE_WRITE) | |
1469 | error = do_tee(in, out, len, flags); | |
1470 | fput_light(out, fput_out); | |
1471 | } | |
1472 | } | |
1473 | fput_light(in, fput_in); | |
1474 | } | |
1475 | ||
1476 | return error; | |
1477 | } |