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 | |
0568b409 | 81 | buf->flags |= 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; | |
0568b409 | 90 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
91 | } |
92 | ||
f84d7519 JA |
93 | static int page_cache_pipe_buf_pin(struct pipe_inode_info *info, |
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 | ||
5274f052 JA |
131 | static struct pipe_buf_operations page_cache_pipe_buf_ops = { |
132 | .can_merge = 0, | |
f84d7519 JA |
133 | .map = generic_pipe_buf_map, |
134 | .unmap = generic_pipe_buf_unmap, | |
135 | .pin = page_cache_pipe_buf_pin, | |
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 | { | |
144 | return 1; | |
145 | } | |
146 | ||
147 | static struct pipe_buf_operations user_page_pipe_buf_ops = { | |
148 | .can_merge = 0, | |
f84d7519 JA |
149 | .map = generic_pipe_buf_map, |
150 | .unmap = generic_pipe_buf_unmap, | |
151 | .pin = generic_pipe_buf_pin, | |
912d35f8 JA |
152 | .release = page_cache_pipe_buf_release, |
153 | .steal = user_page_pipe_buf_steal, | |
f84d7519 | 154 | .get = generic_pipe_buf_get, |
912d35f8 JA |
155 | }; |
156 | ||
83f9135b JA |
157 | /* |
158 | * Pipe output worker. This sets up our pipe format with the page cache | |
159 | * pipe buffer operations. Otherwise very similar to the regular pipe_writev(). | |
160 | */ | |
00522fb4 JA |
161 | static ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
162 | struct splice_pipe_desc *spd) | |
5274f052 | 163 | { |
912d35f8 | 164 | int ret, do_wakeup, page_nr; |
5274f052 JA |
165 | |
166 | ret = 0; | |
167 | do_wakeup = 0; | |
912d35f8 | 168 | page_nr = 0; |
5274f052 | 169 | |
3a326a2c IM |
170 | if (pipe->inode) |
171 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 172 | |
5274f052 | 173 | for (;;) { |
3a326a2c | 174 | if (!pipe->readers) { |
5274f052 JA |
175 | send_sig(SIGPIPE, current, 0); |
176 | if (!ret) | |
177 | ret = -EPIPE; | |
178 | break; | |
179 | } | |
180 | ||
6f767b04 JA |
181 | if (pipe->nrbufs < PIPE_BUFFERS) { |
182 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); | |
3a326a2c | 183 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
5274f052 | 184 | |
912d35f8 JA |
185 | buf->page = spd->pages[page_nr]; |
186 | buf->offset = spd->partial[page_nr].offset; | |
187 | buf->len = spd->partial[page_nr].len; | |
188 | buf->ops = spd->ops; | |
6f767b04 | 189 | pipe->nrbufs++; |
912d35f8 JA |
190 | page_nr++; |
191 | ret += buf->len; | |
192 | ||
6f767b04 JA |
193 | if (pipe->inode) |
194 | do_wakeup = 1; | |
5274f052 | 195 | |
912d35f8 | 196 | if (!--spd->nr_pages) |
5274f052 | 197 | break; |
6f767b04 | 198 | if (pipe->nrbufs < PIPE_BUFFERS) |
5274f052 JA |
199 | continue; |
200 | ||
201 | break; | |
202 | } | |
203 | ||
912d35f8 | 204 | if (spd->flags & SPLICE_F_NONBLOCK) { |
29e35094 LT |
205 | if (!ret) |
206 | ret = -EAGAIN; | |
207 | break; | |
208 | } | |
209 | ||
5274f052 JA |
210 | if (signal_pending(current)) { |
211 | if (!ret) | |
212 | ret = -ERESTARTSYS; | |
213 | break; | |
214 | } | |
215 | ||
216 | if (do_wakeup) { | |
c0bd1f65 | 217 | smp_mb(); |
3a326a2c IM |
218 | if (waitqueue_active(&pipe->wait)) |
219 | wake_up_interruptible_sync(&pipe->wait); | |
220 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
221 | do_wakeup = 0; |
222 | } | |
223 | ||
3a326a2c IM |
224 | pipe->waiting_writers++; |
225 | pipe_wait(pipe); | |
226 | pipe->waiting_writers--; | |
5274f052 JA |
227 | } |
228 | ||
3a326a2c IM |
229 | if (pipe->inode) |
230 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
231 | |
232 | if (do_wakeup) { | |
c0bd1f65 | 233 | smp_mb(); |
3a326a2c IM |
234 | if (waitqueue_active(&pipe->wait)) |
235 | wake_up_interruptible(&pipe->wait); | |
236 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
5274f052 JA |
237 | } |
238 | ||
912d35f8 JA |
239 | while (page_nr < spd->nr_pages) |
240 | page_cache_release(spd->pages[page_nr++]); | |
5274f052 JA |
241 | |
242 | return ret; | |
243 | } | |
244 | ||
3a326a2c | 245 | static int |
cbb7e577 JA |
246 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
247 | struct pipe_inode_info *pipe, size_t len, | |
248 | unsigned int flags) | |
5274f052 JA |
249 | { |
250 | struct address_space *mapping = in->f_mapping; | |
912d35f8 | 251 | unsigned int loff, nr_pages; |
16c523dd | 252 | struct page *pages[PIPE_BUFFERS]; |
912d35f8 | 253 | struct partial_page partial[PIPE_BUFFERS]; |
5274f052 | 254 | struct page *page; |
91ad66ef JA |
255 | pgoff_t index, end_index; |
256 | loff_t isize; | |
912d35f8 | 257 | size_t total_len; |
eb20796b | 258 | int error, page_nr; |
912d35f8 JA |
259 | struct splice_pipe_desc spd = { |
260 | .pages = pages, | |
261 | .partial = partial, | |
262 | .flags = flags, | |
263 | .ops = &page_cache_pipe_buf_ops, | |
264 | }; | |
5274f052 | 265 | |
cbb7e577 | 266 | index = *ppos >> PAGE_CACHE_SHIFT; |
912d35f8 JA |
267 | loff = *ppos & ~PAGE_CACHE_MASK; |
268 | nr_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
5274f052 JA |
269 | |
270 | if (nr_pages > PIPE_BUFFERS) | |
271 | nr_pages = PIPE_BUFFERS; | |
272 | ||
273 | /* | |
73d62d83 | 274 | * Initiate read-ahead on this page range. however, don't call into |
0b749ce3 JA |
275 | * read-ahead if this is a non-zero offset (we are likely doing small |
276 | * chunk splice and the page is already there) for a single page. | |
5274f052 | 277 | */ |
eb645a24 JA |
278 | if (!loff || nr_pages > 1) |
279 | page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages); | |
5274f052 | 280 | |
5274f052 | 281 | /* |
73d62d83 | 282 | * Now fill in the holes: |
5274f052 | 283 | */ |
7480a904 | 284 | error = 0; |
912d35f8 | 285 | total_len = 0; |
82aa5d61 | 286 | |
eb20796b JA |
287 | /* |
288 | * Lookup the (hopefully) full range of pages we need. | |
289 | */ | |
290 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); | |
82aa5d61 | 291 | |
eb20796b JA |
292 | /* |
293 | * If find_get_pages_contig() returned fewer pages than we needed, | |
294 | * allocate the rest. | |
295 | */ | |
296 | index += spd.nr_pages; | |
297 | while (spd.nr_pages < nr_pages) { | |
82aa5d61 | 298 | /* |
eb20796b JA |
299 | * Page could be there, find_get_pages_contig() breaks on |
300 | * the first hole. | |
5274f052 | 301 | */ |
7480a904 JA |
302 | page = find_get_page(mapping, index); |
303 | if (!page) { | |
e27dedd8 JA |
304 | /* |
305 | * Make sure the read-ahead engine is notified | |
306 | * about this failure. | |
307 | */ | |
308 | handle_ra_miss(mapping, &in->f_ra, index); | |
309 | ||
7480a904 | 310 | /* |
eb20796b | 311 | * page didn't exist, allocate one. |
7480a904 JA |
312 | */ |
313 | page = page_cache_alloc_cold(mapping); | |
314 | if (!page) | |
315 | break; | |
316 | ||
317 | error = add_to_page_cache_lru(page, mapping, index, | |
eb20796b | 318 | mapping_gfp_mask(mapping)); |
7480a904 JA |
319 | if (unlikely(error)) { |
320 | page_cache_release(page); | |
321 | break; | |
322 | } | |
eb20796b JA |
323 | /* |
324 | * add_to_page_cache() locks the page, unlock it | |
325 | * to avoid convoluting the logic below even more. | |
326 | */ | |
327 | unlock_page(page); | |
7480a904 JA |
328 | } |
329 | ||
eb20796b JA |
330 | pages[spd.nr_pages++] = page; |
331 | index++; | |
332 | } | |
333 | ||
334 | /* | |
335 | * Now loop over the map and see if we need to start IO on any | |
336 | * pages, fill in the partial map, etc. | |
337 | */ | |
338 | index = *ppos >> PAGE_CACHE_SHIFT; | |
339 | nr_pages = spd.nr_pages; | |
340 | spd.nr_pages = 0; | |
341 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
342 | unsigned int this_len; | |
343 | ||
344 | if (!len) | |
345 | break; | |
346 | ||
347 | /* | |
348 | * this_len is the max we'll use from this page | |
349 | */ | |
350 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
351 | page = pages[page_nr]; | |
352 | ||
7480a904 JA |
353 | /* |
354 | * If the page isn't uptodate, we may need to start io on it | |
355 | */ | |
356 | if (!PageUptodate(page)) { | |
c4f895cb JA |
357 | /* |
358 | * If in nonblock mode then dont block on waiting | |
359 | * for an in-flight io page | |
360 | */ | |
361 | if (flags & SPLICE_F_NONBLOCK) | |
362 | break; | |
363 | ||
7480a904 JA |
364 | lock_page(page); |
365 | ||
366 | /* | |
367 | * page was truncated, stop here. if this isn't the | |
368 | * first page, we'll just complete what we already | |
369 | * added | |
370 | */ | |
371 | if (!page->mapping) { | |
372 | unlock_page(page); | |
7480a904 JA |
373 | break; |
374 | } | |
375 | /* | |
376 | * page was already under io and is now done, great | |
377 | */ | |
378 | if (PageUptodate(page)) { | |
379 | unlock_page(page); | |
380 | goto fill_it; | |
381 | } | |
5274f052 | 382 | |
7480a904 JA |
383 | /* |
384 | * need to read in the page | |
385 | */ | |
386 | error = mapping->a_ops->readpage(in, page); | |
5274f052 | 387 | if (unlikely(error)) { |
eb20796b JA |
388 | /* |
389 | * We really should re-lookup the page here, | |
390 | * but it complicates things a lot. Instead | |
391 | * lets just do what we already stored, and | |
392 | * we'll get it the next time we are called. | |
393 | */ | |
7480a904 | 394 | if (error == AOP_TRUNCATED_PAGE) |
eb20796b JA |
395 | error = 0; |
396 | ||
5274f052 JA |
397 | break; |
398 | } | |
91ad66ef JA |
399 | |
400 | /* | |
401 | * i_size must be checked after ->readpage(). | |
402 | */ | |
403 | isize = i_size_read(mapping->host); | |
404 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
eb20796b | 405 | if (unlikely(!isize || index > end_index)) |
91ad66ef | 406 | break; |
91ad66ef JA |
407 | |
408 | /* | |
409 | * if this is the last page, see if we need to shrink | |
410 | * the length and stop | |
411 | */ | |
412 | if (end_index == index) { | |
413 | loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK); | |
eb20796b | 414 | if (total_len + loff > isize) |
91ad66ef | 415 | break; |
91ad66ef JA |
416 | /* |
417 | * force quit after adding this page | |
418 | */ | |
eb20796b | 419 | len = this_len; |
82aa5d61 | 420 | this_len = min(this_len, loff); |
912d35f8 | 421 | loff = 0; |
91ad66ef | 422 | } |
5274f052 | 423 | } |
7480a904 | 424 | fill_it: |
eb20796b JA |
425 | partial[page_nr].offset = loff; |
426 | partial[page_nr].len = this_len; | |
82aa5d61 | 427 | len -= this_len; |
912d35f8 | 428 | total_len += this_len; |
91ad66ef | 429 | loff = 0; |
eb20796b JA |
430 | spd.nr_pages++; |
431 | index++; | |
5274f052 JA |
432 | } |
433 | ||
eb20796b JA |
434 | /* |
435 | * Release any pages at the end, if we quit early. 'i' is how far | |
436 | * we got, 'nr_pages' is how many pages are in the map. | |
437 | */ | |
438 | while (page_nr < nr_pages) | |
439 | page_cache_release(pages[page_nr++]); | |
440 | ||
912d35f8 | 441 | if (spd.nr_pages) |
00522fb4 | 442 | return splice_to_pipe(pipe, &spd); |
5274f052 | 443 | |
7480a904 | 444 | return error; |
5274f052 JA |
445 | } |
446 | ||
83f9135b JA |
447 | /** |
448 | * generic_file_splice_read - splice data from file to a pipe | |
449 | * @in: file to splice from | |
450 | * @pipe: pipe to splice to | |
451 | * @len: number of bytes to splice | |
452 | * @flags: splice modifier flags | |
453 | * | |
454 | * Will read pages from given file and fill them into a pipe. | |
83f9135b | 455 | */ |
cbb7e577 JA |
456 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
457 | struct pipe_inode_info *pipe, size_t len, | |
458 | unsigned int flags) | |
5274f052 JA |
459 | { |
460 | ssize_t spliced; | |
461 | int ret; | |
462 | ||
463 | ret = 0; | |
464 | spliced = 0; | |
3a326a2c | 465 | |
5274f052 | 466 | while (len) { |
cbb7e577 | 467 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
5274f052 | 468 | |
c4f895cb | 469 | if (ret < 0) |
5274f052 | 470 | break; |
c4f895cb JA |
471 | else if (!ret) { |
472 | if (spliced) | |
473 | break; | |
474 | if (flags & SPLICE_F_NONBLOCK) { | |
475 | ret = -EAGAIN; | |
476 | break; | |
477 | } | |
478 | } | |
5274f052 | 479 | |
cbb7e577 | 480 | *ppos += ret; |
5274f052 JA |
481 | len -= ret; |
482 | spliced += ret; | |
483 | } | |
484 | ||
485 | if (spliced) | |
486 | return spliced; | |
487 | ||
488 | return ret; | |
489 | } | |
490 | ||
059a8f37 JA |
491 | EXPORT_SYMBOL(generic_file_splice_read); |
492 | ||
5274f052 | 493 | /* |
4f6f0bd2 | 494 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 495 | * using sendpage(). Return the number of bytes sent. |
5274f052 JA |
496 | */ |
497 | static int pipe_to_sendpage(struct pipe_inode_info *info, | |
498 | struct pipe_buffer *buf, struct splice_desc *sd) | |
499 | { | |
500 | struct file *file = sd->file; | |
501 | loff_t pos = sd->pos; | |
f84d7519 | 502 | int ret, more; |
5274f052 | 503 | |
f84d7519 JA |
504 | ret = buf->ops->pin(info, buf); |
505 | if (!ret) { | |
506 | more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; | |
5274f052 | 507 | |
f84d7519 JA |
508 | ret = file->f_op->sendpage(file, buf->page, buf->offset, |
509 | sd->len, &pos, more); | |
510 | } | |
5274f052 | 511 | |
016b661e | 512 | return ret; |
5274f052 JA |
513 | } |
514 | ||
515 | /* | |
516 | * This is a little more tricky than the file -> pipe splicing. There are | |
517 | * basically three cases: | |
518 | * | |
519 | * - Destination page already exists in the address space and there | |
520 | * are users of it. For that case we have no other option that | |
521 | * copying the data. Tough luck. | |
522 | * - Destination page already exists in the address space, but there | |
523 | * are no users of it. Make sure it's uptodate, then drop it. Fall | |
524 | * through to last case. | |
525 | * - Destination page does not exist, we can add the pipe page to | |
526 | * the page cache and avoid the copy. | |
527 | * | |
83f9135b JA |
528 | * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
529 | * sd->flags), we attempt to migrate pages from the pipe to the output | |
530 | * file address space page cache. This is possible if no one else has | |
531 | * the pipe page referenced outside of the pipe and page cache. If | |
532 | * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create | |
533 | * a new page in the output file page cache and fill/dirty that. | |
5274f052 JA |
534 | */ |
535 | static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, | |
536 | struct splice_desc *sd) | |
537 | { | |
538 | struct file *file = sd->file; | |
539 | struct address_space *mapping = file->f_mapping; | |
3e7ee3e7 | 540 | gfp_t gfp_mask = mapping_gfp_mask(mapping); |
016b661e | 541 | unsigned int offset, this_len; |
5274f052 | 542 | struct page *page; |
5274f052 | 543 | pgoff_t index; |
3e7ee3e7 | 544 | int ret; |
5274f052 JA |
545 | |
546 | /* | |
49d0b21b | 547 | * make sure the data in this buffer is uptodate |
5274f052 | 548 | */ |
f84d7519 JA |
549 | ret = buf->ops->pin(info, buf); |
550 | if (unlikely(ret)) | |
551 | return ret; | |
5274f052 JA |
552 | |
553 | index = sd->pos >> PAGE_CACHE_SHIFT; | |
554 | offset = sd->pos & ~PAGE_CACHE_MASK; | |
555 | ||
016b661e JA |
556 | this_len = sd->len; |
557 | if (this_len + offset > PAGE_CACHE_SIZE) | |
558 | this_len = PAGE_CACHE_SIZE - offset; | |
559 | ||
5274f052 | 560 | /* |
0568b409 JA |
561 | * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full |
562 | * page. | |
5274f052 | 563 | */ |
0568b409 | 564 | if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) { |
83f9135b JA |
565 | /* |
566 | * If steal succeeds, buf->page is now pruned from the vm | |
9e0267c2 JA |
567 | * side (LRU and page cache) and we can reuse it. The page |
568 | * will also be looked on successful return. | |
83f9135b | 569 | */ |
5abc97aa JA |
570 | if (buf->ops->steal(info, buf)) |
571 | goto find_page; | |
572 | ||
573 | page = buf->page; | |
46e678c9 JA |
574 | if (add_to_page_cache(page, mapping, index, gfp_mask)) { |
575 | unlock_page(page); | |
5abc97aa | 576 | goto find_page; |
46e678c9 | 577 | } |
3e7ee3e7 | 578 | |
0568b409 JA |
579 | page_cache_get(page); |
580 | ||
3e7ee3e7 JA |
581 | if (!(buf->flags & PIPE_BUF_FLAG_LRU)) |
582 | lru_cache_add(page); | |
5abc97aa JA |
583 | } else { |
584 | find_page: | |
9e0267c2 JA |
585 | page = find_lock_page(mapping, index); |
586 | if (!page) { | |
587 | ret = -ENOMEM; | |
588 | page = page_cache_alloc_cold(mapping); | |
589 | if (unlikely(!page)) | |
590 | goto out_nomem; | |
591 | ||
592 | /* | |
593 | * This will also lock the page | |
594 | */ | |
595 | ret = add_to_page_cache_lru(page, mapping, index, | |
596 | gfp_mask); | |
597 | if (unlikely(ret)) | |
598 | goto out; | |
599 | } | |
5abc97aa JA |
600 | |
601 | /* | |
9e0267c2 JA |
602 | * We get here with the page locked. If the page is also |
603 | * uptodate, we don't need to do more. If it isn't, we | |
604 | * may need to bring it in if we are not going to overwrite | |
605 | * the full page. | |
5abc97aa JA |
606 | */ |
607 | if (!PageUptodate(page)) { | |
016b661e | 608 | if (this_len < PAGE_CACHE_SIZE) { |
5abc97aa JA |
609 | ret = mapping->a_ops->readpage(file, page); |
610 | if (unlikely(ret)) | |
611 | goto out; | |
612 | ||
613 | lock_page(page); | |
614 | ||
615 | if (!PageUptodate(page)) { | |
616 | /* | |
73d62d83 | 617 | * Page got invalidated, repeat. |
5abc97aa JA |
618 | */ |
619 | if (!page->mapping) { | |
620 | unlock_page(page); | |
621 | page_cache_release(page); | |
622 | goto find_page; | |
623 | } | |
624 | ret = -EIO; | |
625 | goto out; | |
5274f052 | 626 | } |
9e0267c2 | 627 | } else |
5abc97aa | 628 | SetPageUptodate(page); |
5274f052 JA |
629 | } |
630 | } | |
631 | ||
016b661e | 632 | ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len); |
4f6f0bd2 JA |
633 | if (ret == AOP_TRUNCATED_PAGE) { |
634 | page_cache_release(page); | |
635 | goto find_page; | |
636 | } else if (ret) | |
5274f052 JA |
637 | goto out; |
638 | ||
0568b409 | 639 | if (buf->page != page) { |
f84d7519 JA |
640 | /* |
641 | * Careful, ->map() uses KM_USER0! | |
642 | */ | |
f6762b7a | 643 | char *src = buf->ops->map(info, buf, 1); |
f84d7519 | 644 | char *dst = kmap_atomic(page, KM_USER1); |
5abc97aa | 645 | |
016b661e | 646 | memcpy(dst + offset, src + buf->offset, this_len); |
5abc97aa | 647 | flush_dcache_page(page); |
f84d7519 | 648 | kunmap_atomic(dst, KM_USER1); |
f6762b7a | 649 | buf->ops->unmap(info, buf, src); |
5abc97aa | 650 | } |
5274f052 | 651 | |
016b661e | 652 | ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len); |
0568b409 JA |
653 | if (!ret) { |
654 | /* | |
655 | * Return the number of bytes written and mark page as | |
656 | * accessed, we are now done! | |
657 | */ | |
658 | ret = this_len; | |
659 | mark_page_accessed(page); | |
660 | balance_dirty_pages_ratelimited(mapping); | |
661 | } else if (ret == AOP_TRUNCATED_PAGE) { | |
4f6f0bd2 JA |
662 | page_cache_release(page); |
663 | goto find_page; | |
0568b409 | 664 | } |
5274f052 | 665 | out: |
0568b409 | 666 | page_cache_release(page); |
9e0267c2 | 667 | unlock_page(page); |
9aefe431 | 668 | out_nomem: |
5274f052 JA |
669 | return ret; |
670 | } | |
671 | ||
83f9135b JA |
672 | /* |
673 | * Pipe input worker. Most of this logic works like a regular pipe, the | |
674 | * key here is the 'actor' worker passed in that actually moves the data | |
675 | * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. | |
676 | */ | |
00522fb4 JA |
677 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
678 | loff_t *ppos, size_t len, unsigned int flags, | |
679 | splice_actor *actor) | |
5274f052 | 680 | { |
5274f052 JA |
681 | int ret, do_wakeup, err; |
682 | struct splice_desc sd; | |
683 | ||
684 | ret = 0; | |
685 | do_wakeup = 0; | |
686 | ||
687 | sd.total_len = len; | |
688 | sd.flags = flags; | |
689 | sd.file = out; | |
cbb7e577 | 690 | sd.pos = *ppos; |
5274f052 | 691 | |
3a326a2c IM |
692 | if (pipe->inode) |
693 | mutex_lock(&pipe->inode->i_mutex); | |
5274f052 | 694 | |
5274f052 | 695 | for (;;) { |
6f767b04 JA |
696 | if (pipe->nrbufs) { |
697 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
5274f052 JA |
698 | struct pipe_buf_operations *ops = buf->ops; |
699 | ||
700 | sd.len = buf->len; | |
701 | if (sd.len > sd.total_len) | |
702 | sd.len = sd.total_len; | |
703 | ||
3a326a2c | 704 | err = actor(pipe, buf, &sd); |
016b661e | 705 | if (err <= 0) { |
5274f052 JA |
706 | if (!ret && err != -ENODATA) |
707 | ret = err; | |
708 | ||
709 | break; | |
710 | } | |
711 | ||
016b661e JA |
712 | ret += err; |
713 | buf->offset += err; | |
714 | buf->len -= err; | |
715 | ||
716 | sd.len -= err; | |
717 | sd.pos += err; | |
718 | sd.total_len -= err; | |
719 | if (sd.len) | |
720 | continue; | |
73d62d83 | 721 | |
5274f052 JA |
722 | if (!buf->len) { |
723 | buf->ops = NULL; | |
3a326a2c | 724 | ops->release(pipe, buf); |
6f767b04 JA |
725 | pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
726 | pipe->nrbufs--; | |
727 | if (pipe->inode) | |
728 | do_wakeup = 1; | |
5274f052 JA |
729 | } |
730 | ||
5274f052 JA |
731 | if (!sd.total_len) |
732 | break; | |
733 | } | |
734 | ||
6f767b04 | 735 | if (pipe->nrbufs) |
5274f052 | 736 | continue; |
3a326a2c | 737 | if (!pipe->writers) |
5274f052 | 738 | break; |
3a326a2c | 739 | if (!pipe->waiting_writers) { |
5274f052 JA |
740 | if (ret) |
741 | break; | |
742 | } | |
743 | ||
29e35094 LT |
744 | if (flags & SPLICE_F_NONBLOCK) { |
745 | if (!ret) | |
746 | ret = -EAGAIN; | |
747 | break; | |
748 | } | |
749 | ||
5274f052 JA |
750 | if (signal_pending(current)) { |
751 | if (!ret) | |
752 | ret = -ERESTARTSYS; | |
753 | break; | |
754 | } | |
755 | ||
756 | if (do_wakeup) { | |
c0bd1f65 | 757 | smp_mb(); |
3a326a2c IM |
758 | if (waitqueue_active(&pipe->wait)) |
759 | wake_up_interruptible_sync(&pipe->wait); | |
760 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
761 | do_wakeup = 0; |
762 | } | |
763 | ||
3a326a2c | 764 | pipe_wait(pipe); |
5274f052 JA |
765 | } |
766 | ||
3a326a2c IM |
767 | if (pipe->inode) |
768 | mutex_unlock(&pipe->inode->i_mutex); | |
5274f052 JA |
769 | |
770 | if (do_wakeup) { | |
c0bd1f65 | 771 | smp_mb(); |
3a326a2c IM |
772 | if (waitqueue_active(&pipe->wait)) |
773 | wake_up_interruptible(&pipe->wait); | |
774 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
5274f052 JA |
775 | } |
776 | ||
5274f052 | 777 | return ret; |
5274f052 JA |
778 | } |
779 | ||
83f9135b JA |
780 | /** |
781 | * generic_file_splice_write - splice data from a pipe to a file | |
3a326a2c | 782 | * @pipe: pipe info |
83f9135b JA |
783 | * @out: file to write to |
784 | * @len: number of bytes to splice | |
785 | * @flags: splice modifier flags | |
786 | * | |
787 | * Will either move or copy pages (determined by @flags options) from | |
788 | * the given pipe inode to the given file. | |
789 | * | |
790 | */ | |
3a326a2c IM |
791 | ssize_t |
792 | generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
cbb7e577 | 793 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 794 | { |
4f6f0bd2 | 795 | struct address_space *mapping = out->f_mapping; |
3a326a2c IM |
796 | ssize_t ret; |
797 | ||
00522fb4 | 798 | ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file); |
a4514ebd | 799 | if (ret > 0) { |
4f6f0bd2 | 800 | struct inode *inode = mapping->host; |
4f6f0bd2 | 801 | |
a4514ebd JA |
802 | *ppos += ret; |
803 | ||
804 | /* | |
805 | * If file or inode is SYNC and we actually wrote some data, | |
806 | * sync it. | |
807 | */ | |
808 | if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
809 | int err; | |
810 | ||
811 | mutex_lock(&inode->i_mutex); | |
812 | err = generic_osync_inode(inode, mapping, | |
813 | OSYNC_METADATA|OSYNC_DATA); | |
814 | mutex_unlock(&inode->i_mutex); | |
4f6f0bd2 | 815 | |
a4514ebd JA |
816 | if (err) |
817 | ret = err; | |
818 | } | |
4f6f0bd2 JA |
819 | } |
820 | ||
821 | return ret; | |
5274f052 JA |
822 | } |
823 | ||
059a8f37 JA |
824 | EXPORT_SYMBOL(generic_file_splice_write); |
825 | ||
83f9135b JA |
826 | /** |
827 | * generic_splice_sendpage - splice data from a pipe to a socket | |
828 | * @inode: pipe inode | |
829 | * @out: socket to write to | |
830 | * @len: number of bytes to splice | |
831 | * @flags: splice modifier flags | |
832 | * | |
833 | * Will send @len bytes from the pipe to a network socket. No data copying | |
834 | * is involved. | |
835 | * | |
836 | */ | |
3a326a2c | 837 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 838 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 839 | { |
00522fb4 | 840 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
841 | } |
842 | ||
059a8f37 | 843 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 844 | |
83f9135b JA |
845 | /* |
846 | * Attempt to initiate a splice from pipe to file. | |
847 | */ | |
3a326a2c | 848 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 849 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 850 | { |
5274f052 JA |
851 | int ret; |
852 | ||
49570e9b | 853 | if (unlikely(!out->f_op || !out->f_op->splice_write)) |
5274f052 JA |
854 | return -EINVAL; |
855 | ||
49570e9b | 856 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
5274f052 JA |
857 | return -EBADF; |
858 | ||
cbb7e577 | 859 | ret = rw_verify_area(WRITE, out, ppos, len); |
5274f052 JA |
860 | if (unlikely(ret < 0)) |
861 | return ret; | |
862 | ||
cbb7e577 | 863 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
864 | } |
865 | ||
83f9135b JA |
866 | /* |
867 | * Attempt to initiate a splice from a file to a pipe. | |
868 | */ | |
cbb7e577 JA |
869 | static long do_splice_to(struct file *in, loff_t *ppos, |
870 | struct pipe_inode_info *pipe, size_t len, | |
871 | unsigned int flags) | |
5274f052 | 872 | { |
cbb7e577 | 873 | loff_t isize, left; |
5274f052 JA |
874 | int ret; |
875 | ||
49570e9b | 876 | if (unlikely(!in->f_op || !in->f_op->splice_read)) |
5274f052 JA |
877 | return -EINVAL; |
878 | ||
49570e9b | 879 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
880 | return -EBADF; |
881 | ||
cbb7e577 | 882 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
883 | if (unlikely(ret < 0)) |
884 | return ret; | |
885 | ||
886 | isize = i_size_read(in->f_mapping->host); | |
cbb7e577 | 887 | if (unlikely(*ppos >= isize)) |
5274f052 JA |
888 | return 0; |
889 | ||
cbb7e577 | 890 | left = isize - *ppos; |
49570e9b | 891 | if (unlikely(left < len)) |
5274f052 JA |
892 | len = left; |
893 | ||
cbb7e577 | 894 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 JA |
895 | } |
896 | ||
cbb7e577 JA |
897 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
898 | size_t len, unsigned int flags) | |
b92ce558 JA |
899 | { |
900 | struct pipe_inode_info *pipe; | |
901 | long ret, bytes; | |
cbb7e577 | 902 | loff_t out_off; |
b92ce558 JA |
903 | umode_t i_mode; |
904 | int i; | |
905 | ||
906 | /* | |
907 | * We require the input being a regular file, as we don't want to | |
908 | * randomly drop data for eg socket -> socket splicing. Use the | |
909 | * piped splicing for that! | |
910 | */ | |
911 | i_mode = in->f_dentry->d_inode->i_mode; | |
912 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
913 | return -EINVAL; | |
914 | ||
915 | /* | |
916 | * neither in nor out is a pipe, setup an internal pipe attached to | |
917 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
918 | */ | |
919 | pipe = current->splice_pipe; | |
49570e9b | 920 | if (unlikely(!pipe)) { |
b92ce558 JA |
921 | pipe = alloc_pipe_info(NULL); |
922 | if (!pipe) | |
923 | return -ENOMEM; | |
924 | ||
925 | /* | |
926 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 927 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
928 | * PIPE_READERS appropriately. |
929 | */ | |
930 | pipe->readers = 1; | |
931 | ||
932 | current->splice_pipe = pipe; | |
933 | } | |
934 | ||
935 | /* | |
73d62d83 | 936 | * Do the splice. |
b92ce558 JA |
937 | */ |
938 | ret = 0; | |
939 | bytes = 0; | |
cbb7e577 | 940 | out_off = 0; |
b92ce558 JA |
941 | |
942 | while (len) { | |
943 | size_t read_len, max_read_len; | |
944 | ||
945 | /* | |
946 | * Do at most PIPE_BUFFERS pages worth of transfer: | |
947 | */ | |
948 | max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); | |
949 | ||
cbb7e577 | 950 | ret = do_splice_to(in, ppos, pipe, max_read_len, flags); |
b92ce558 JA |
951 | if (unlikely(ret < 0)) |
952 | goto out_release; | |
953 | ||
954 | read_len = ret; | |
955 | ||
956 | /* | |
957 | * NOTE: nonblocking mode only applies to the input. We | |
958 | * must not do the output in nonblocking mode as then we | |
959 | * could get stuck data in the internal pipe: | |
960 | */ | |
cbb7e577 | 961 | ret = do_splice_from(pipe, out, &out_off, read_len, |
b92ce558 JA |
962 | flags & ~SPLICE_F_NONBLOCK); |
963 | if (unlikely(ret < 0)) | |
964 | goto out_release; | |
965 | ||
966 | bytes += ret; | |
967 | len -= ret; | |
968 | ||
969 | /* | |
970 | * In nonblocking mode, if we got back a short read then | |
971 | * that was due to either an IO error or due to the | |
972 | * pagecache entry not being there. In the IO error case | |
973 | * the _next_ splice attempt will produce a clean IO error | |
974 | * return value (not a short read), so in both cases it's | |
975 | * correct to break out of the loop here: | |
976 | */ | |
977 | if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) | |
978 | break; | |
979 | } | |
980 | ||
981 | pipe->nrbufs = pipe->curbuf = 0; | |
982 | ||
983 | return bytes; | |
984 | ||
985 | out_release: | |
986 | /* | |
987 | * If we did an incomplete transfer we must release | |
988 | * the pipe buffers in question: | |
989 | */ | |
990 | for (i = 0; i < PIPE_BUFFERS; i++) { | |
991 | struct pipe_buffer *buf = pipe->bufs + i; | |
992 | ||
993 | if (buf->ops) { | |
994 | buf->ops->release(pipe, buf); | |
995 | buf->ops = NULL; | |
996 | } | |
997 | } | |
998 | pipe->nrbufs = pipe->curbuf = 0; | |
999 | ||
1000 | /* | |
1001 | * If we transferred some data, return the number of bytes: | |
1002 | */ | |
1003 | if (bytes > 0) | |
1004 | return bytes; | |
1005 | ||
1006 | return ret; | |
1007 | } | |
1008 | ||
1009 | EXPORT_SYMBOL(do_splice_direct); | |
1010 | ||
83f9135b JA |
1011 | /* |
1012 | * Determine where to splice to/from. | |
1013 | */ | |
529565dc IM |
1014 | static long do_splice(struct file *in, loff_t __user *off_in, |
1015 | struct file *out, loff_t __user *off_out, | |
1016 | size_t len, unsigned int flags) | |
5274f052 | 1017 | { |
3a326a2c | 1018 | struct pipe_inode_info *pipe; |
cbb7e577 | 1019 | loff_t offset, *off; |
a4514ebd | 1020 | long ret; |
5274f052 | 1021 | |
3a326a2c | 1022 | pipe = in->f_dentry->d_inode->i_pipe; |
529565dc IM |
1023 | if (pipe) { |
1024 | if (off_in) | |
1025 | return -ESPIPE; | |
b92ce558 JA |
1026 | if (off_out) { |
1027 | if (out->f_op->llseek == no_llseek) | |
1028 | return -EINVAL; | |
cbb7e577 | 1029 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1030 | return -EFAULT; |
cbb7e577 JA |
1031 | off = &offset; |
1032 | } else | |
1033 | off = &out->f_pos; | |
529565dc | 1034 | |
a4514ebd JA |
1035 | ret = do_splice_from(pipe, out, off, len, flags); |
1036 | ||
1037 | if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) | |
1038 | ret = -EFAULT; | |
1039 | ||
1040 | return ret; | |
529565dc | 1041 | } |
5274f052 | 1042 | |
3a326a2c | 1043 | pipe = out->f_dentry->d_inode->i_pipe; |
529565dc IM |
1044 | if (pipe) { |
1045 | if (off_out) | |
1046 | return -ESPIPE; | |
b92ce558 JA |
1047 | if (off_in) { |
1048 | if (in->f_op->llseek == no_llseek) | |
1049 | return -EINVAL; | |
cbb7e577 | 1050 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1051 | return -EFAULT; |
cbb7e577 JA |
1052 | off = &offset; |
1053 | } else | |
1054 | off = &in->f_pos; | |
529565dc | 1055 | |
a4514ebd JA |
1056 | ret = do_splice_to(in, off, pipe, len, flags); |
1057 | ||
1058 | if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) | |
1059 | ret = -EFAULT; | |
1060 | ||
1061 | return ret; | |
529565dc | 1062 | } |
5274f052 JA |
1063 | |
1064 | return -EINVAL; | |
1065 | } | |
1066 | ||
912d35f8 JA |
1067 | /* |
1068 | * Map an iov into an array of pages and offset/length tupples. With the | |
1069 | * partial_page structure, we can map several non-contiguous ranges into | |
1070 | * our ones pages[] map instead of splitting that operation into pieces. | |
1071 | * Could easily be exported as a generic helper for other users, in which | |
1072 | * case one would probably want to add a 'max_nr_pages' parameter as well. | |
1073 | */ | |
1074 | static int get_iovec_page_array(const struct iovec __user *iov, | |
1075 | unsigned int nr_vecs, struct page **pages, | |
1076 | struct partial_page *partial) | |
1077 | { | |
1078 | int buffers = 0, error = 0; | |
1079 | ||
1080 | /* | |
1081 | * It's ok to take the mmap_sem for reading, even | |
1082 | * across a "get_user()". | |
1083 | */ | |
1084 | down_read(¤t->mm->mmap_sem); | |
1085 | ||
1086 | while (nr_vecs) { | |
1087 | unsigned long off, npages; | |
1088 | void __user *base; | |
1089 | size_t len; | |
1090 | int i; | |
1091 | ||
1092 | /* | |
1093 | * Get user address base and length for this iovec. | |
1094 | */ | |
1095 | error = get_user(base, &iov->iov_base); | |
1096 | if (unlikely(error)) | |
1097 | break; | |
1098 | error = get_user(len, &iov->iov_len); | |
1099 | if (unlikely(error)) | |
1100 | break; | |
1101 | ||
1102 | /* | |
1103 | * Sanity check this iovec. 0 read succeeds. | |
1104 | */ | |
1105 | if (unlikely(!len)) | |
1106 | break; | |
1107 | error = -EFAULT; | |
1108 | if (unlikely(!base)) | |
1109 | break; | |
1110 | ||
1111 | /* | |
1112 | * Get this base offset and number of pages, then map | |
1113 | * in the user pages. | |
1114 | */ | |
1115 | off = (unsigned long) base & ~PAGE_MASK; | |
1116 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
1117 | if (npages > PIPE_BUFFERS - buffers) | |
1118 | npages = PIPE_BUFFERS - buffers; | |
1119 | ||
1120 | error = get_user_pages(current, current->mm, | |
1121 | (unsigned long) base, npages, 0, 0, | |
1122 | &pages[buffers], NULL); | |
1123 | ||
1124 | if (unlikely(error <= 0)) | |
1125 | break; | |
1126 | ||
1127 | /* | |
1128 | * Fill this contiguous range into the partial page map. | |
1129 | */ | |
1130 | for (i = 0; i < error; i++) { | |
1131 | const int plen = min_t(size_t, len, PAGE_SIZE) - off; | |
1132 | ||
1133 | partial[buffers].offset = off; | |
1134 | partial[buffers].len = plen; | |
1135 | ||
1136 | off = 0; | |
1137 | len -= plen; | |
1138 | buffers++; | |
1139 | } | |
1140 | ||
1141 | /* | |
1142 | * We didn't complete this iov, stop here since it probably | |
1143 | * means we have to move some of this into a pipe to | |
1144 | * be able to continue. | |
1145 | */ | |
1146 | if (len) | |
1147 | break; | |
1148 | ||
1149 | /* | |
1150 | * Don't continue if we mapped fewer pages than we asked for, | |
1151 | * or if we mapped the max number of pages that we have | |
1152 | * room for. | |
1153 | */ | |
1154 | if (error < npages || buffers == PIPE_BUFFERS) | |
1155 | break; | |
1156 | ||
1157 | nr_vecs--; | |
1158 | iov++; | |
1159 | } | |
1160 | ||
1161 | up_read(¤t->mm->mmap_sem); | |
1162 | ||
1163 | if (buffers) | |
1164 | return buffers; | |
1165 | ||
1166 | return error; | |
1167 | } | |
1168 | ||
1169 | /* | |
1170 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1171 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1172 | * to file). In both cases the output is a pipe, naturally. | |
1173 | * | |
1174 | * Note that vmsplice only supports splicing _from_ user memory to a pipe, | |
1175 | * not the other way around. Splicing from user memory is a simple operation | |
1176 | * that can be supported without any funky alignment restrictions or nasty | |
1177 | * vm tricks. We simply map in the user memory and fill them into a pipe. | |
1178 | * The reverse isn't quite as easy, though. There are two possible solutions | |
1179 | * for that: | |
1180 | * | |
1181 | * - memcpy() the data internally, at which point we might as well just | |
1182 | * do a regular read() on the buffer anyway. | |
1183 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1184 | * has restriction limitations on both ends of the pipe). | |
1185 | * | |
1186 | * Alas, it isn't here. | |
1187 | * | |
1188 | */ | |
1189 | static long do_vmsplice(struct file *file, const struct iovec __user *iov, | |
1190 | unsigned long nr_segs, unsigned int flags) | |
1191 | { | |
1192 | struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe; | |
1193 | struct page *pages[PIPE_BUFFERS]; | |
1194 | struct partial_page partial[PIPE_BUFFERS]; | |
1195 | struct splice_pipe_desc spd = { | |
1196 | .pages = pages, | |
1197 | .partial = partial, | |
1198 | .flags = flags, | |
1199 | .ops = &user_page_pipe_buf_ops, | |
1200 | }; | |
1201 | ||
1202 | if (unlikely(!pipe)) | |
1203 | return -EBADF; | |
1204 | if (unlikely(nr_segs > UIO_MAXIOV)) | |
1205 | return -EINVAL; | |
1206 | else if (unlikely(!nr_segs)) | |
1207 | return 0; | |
1208 | ||
1209 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial); | |
1210 | if (spd.nr_pages <= 0) | |
1211 | return spd.nr_pages; | |
1212 | ||
00522fb4 | 1213 | return splice_to_pipe(pipe, &spd); |
912d35f8 JA |
1214 | } |
1215 | ||
1216 | asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov, | |
1217 | unsigned long nr_segs, unsigned int flags) | |
1218 | { | |
1219 | struct file *file; | |
1220 | long error; | |
1221 | int fput; | |
1222 | ||
1223 | error = -EBADF; | |
1224 | file = fget_light(fd, &fput); | |
1225 | if (file) { | |
1226 | if (file->f_mode & FMODE_WRITE) | |
1227 | error = do_vmsplice(file, iov, nr_segs, flags); | |
1228 | ||
1229 | fput_light(file, fput); | |
1230 | } | |
1231 | ||
1232 | return error; | |
1233 | } | |
1234 | ||
529565dc IM |
1235 | asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
1236 | int fd_out, loff_t __user *off_out, | |
1237 | size_t len, unsigned int flags) | |
5274f052 JA |
1238 | { |
1239 | long error; | |
1240 | struct file *in, *out; | |
1241 | int fput_in, fput_out; | |
1242 | ||
1243 | if (unlikely(!len)) | |
1244 | return 0; | |
1245 | ||
1246 | error = -EBADF; | |
529565dc | 1247 | in = fget_light(fd_in, &fput_in); |
5274f052 JA |
1248 | if (in) { |
1249 | if (in->f_mode & FMODE_READ) { | |
529565dc | 1250 | out = fget_light(fd_out, &fput_out); |
5274f052 JA |
1251 | if (out) { |
1252 | if (out->f_mode & FMODE_WRITE) | |
529565dc IM |
1253 | error = do_splice(in, off_in, |
1254 | out, off_out, | |
1255 | len, flags); | |
5274f052 JA |
1256 | fput_light(out, fput_out); |
1257 | } | |
1258 | } | |
1259 | ||
1260 | fput_light(in, fput_in); | |
1261 | } | |
1262 | ||
1263 | return error; | |
1264 | } | |
70524490 JA |
1265 | |
1266 | /* | |
1267 | * Link contents of ipipe to opipe. | |
1268 | */ | |
1269 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1270 | struct pipe_inode_info *opipe, | |
1271 | size_t len, unsigned int flags) | |
1272 | { | |
1273 | struct pipe_buffer *ibuf, *obuf; | |
2a27250e JA |
1274 | int ret, do_wakeup, i, ipipe_first; |
1275 | ||
1276 | ret = do_wakeup = ipipe_first = 0; | |
70524490 JA |
1277 | |
1278 | /* | |
1279 | * Potential ABBA deadlock, work around it by ordering lock | |
1280 | * grabbing by inode address. Otherwise two different processes | |
1281 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1282 | */ | |
1283 | if (ipipe->inode < opipe->inode) { | |
2a27250e | 1284 | ipipe_first = 1; |
70524490 JA |
1285 | mutex_lock(&ipipe->inode->i_mutex); |
1286 | mutex_lock(&opipe->inode->i_mutex); | |
1287 | } else { | |
1288 | mutex_lock(&opipe->inode->i_mutex); | |
1289 | mutex_lock(&ipipe->inode->i_mutex); | |
1290 | } | |
1291 | ||
1292 | for (i = 0;; i++) { | |
1293 | if (!opipe->readers) { | |
1294 | send_sig(SIGPIPE, current, 0); | |
1295 | if (!ret) | |
1296 | ret = -EPIPE; | |
1297 | break; | |
1298 | } | |
1299 | if (ipipe->nrbufs - i) { | |
1300 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); | |
1301 | ||
1302 | /* | |
1303 | * If we have room, fill this buffer | |
1304 | */ | |
1305 | if (opipe->nrbufs < PIPE_BUFFERS) { | |
1306 | int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); | |
1307 | ||
1308 | /* | |
1309 | * Get a reference to this pipe buffer, | |
1310 | * so we can copy the contents over. | |
1311 | */ | |
1312 | ibuf->ops->get(ipipe, ibuf); | |
1313 | ||
1314 | obuf = opipe->bufs + nbuf; | |
1315 | *obuf = *ibuf; | |
1316 | ||
1317 | if (obuf->len > len) | |
1318 | obuf->len = len; | |
1319 | ||
1320 | opipe->nrbufs++; | |
1321 | do_wakeup = 1; | |
1322 | ret += obuf->len; | |
1323 | len -= obuf->len; | |
1324 | ||
1325 | if (!len) | |
1326 | break; | |
1327 | if (opipe->nrbufs < PIPE_BUFFERS) | |
1328 | continue; | |
1329 | } | |
1330 | ||
1331 | /* | |
1332 | * We have input available, but no output room. | |
2a27250e JA |
1333 | * If we already copied data, return that. If we |
1334 | * need to drop the opipe lock, it must be ordered | |
1335 | * last to avoid deadlocks. | |
70524490 | 1336 | */ |
2a27250e | 1337 | if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) { |
70524490 JA |
1338 | if (!ret) |
1339 | ret = -EAGAIN; | |
1340 | break; | |
1341 | } | |
1342 | if (signal_pending(current)) { | |
1343 | if (!ret) | |
1344 | ret = -ERESTARTSYS; | |
1345 | break; | |
1346 | } | |
1347 | if (do_wakeup) { | |
1348 | smp_mb(); | |
1349 | if (waitqueue_active(&opipe->wait)) | |
1350 | wake_up_interruptible(&opipe->wait); | |
1351 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1352 | do_wakeup = 0; | |
1353 | } | |
1354 | ||
1355 | opipe->waiting_writers++; | |
1356 | pipe_wait(opipe); | |
1357 | opipe->waiting_writers--; | |
1358 | continue; | |
1359 | } | |
1360 | ||
1361 | /* | |
1362 | * No input buffers, do the usual checks for available | |
1363 | * writers and blocking and wait if necessary | |
1364 | */ | |
1365 | if (!ipipe->writers) | |
1366 | break; | |
1367 | if (!ipipe->waiting_writers) { | |
1368 | if (ret) | |
1369 | break; | |
1370 | } | |
2a27250e JA |
1371 | /* |
1372 | * pipe_wait() drops the ipipe mutex. To avoid deadlocks | |
1373 | * with another process, we can only safely do that if | |
1374 | * the ipipe lock is ordered last. | |
1375 | */ | |
1376 | if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) { | |
70524490 JA |
1377 | if (!ret) |
1378 | ret = -EAGAIN; | |
1379 | break; | |
1380 | } | |
1381 | if (signal_pending(current)) { | |
1382 | if (!ret) | |
1383 | ret = -ERESTARTSYS; | |
1384 | break; | |
1385 | } | |
1386 | ||
1387 | if (waitqueue_active(&ipipe->wait)) | |
1388 | wake_up_interruptible_sync(&ipipe->wait); | |
1389 | kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT); | |
1390 | ||
1391 | pipe_wait(ipipe); | |
1392 | } | |
1393 | ||
1394 | mutex_unlock(&ipipe->inode->i_mutex); | |
1395 | mutex_unlock(&opipe->inode->i_mutex); | |
1396 | ||
1397 | if (do_wakeup) { | |
1398 | smp_mb(); | |
1399 | if (waitqueue_active(&opipe->wait)) | |
1400 | wake_up_interruptible(&opipe->wait); | |
1401 | kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); | |
1402 | } | |
1403 | ||
1404 | return ret; | |
1405 | } | |
1406 | ||
1407 | /* | |
1408 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1409 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1410 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1411 | * applicable one is SPLICE_F_NONBLOCK. | |
1412 | */ | |
1413 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1414 | unsigned int flags) | |
1415 | { | |
1416 | struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe; | |
1417 | struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe; | |
1418 | ||
1419 | /* | |
1420 | * Link ipipe to the two output pipes, consuming as we go along. | |
1421 | */ | |
1422 | if (ipipe && opipe) | |
1423 | return link_pipe(ipipe, opipe, len, flags); | |
1424 | ||
1425 | return -EINVAL; | |
1426 | } | |
1427 | ||
1428 | asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) | |
1429 | { | |
1430 | struct file *in; | |
1431 | int error, fput_in; | |
1432 | ||
1433 | if (unlikely(!len)) | |
1434 | return 0; | |
1435 | ||
1436 | error = -EBADF; | |
1437 | in = fget_light(fdin, &fput_in); | |
1438 | if (in) { | |
1439 | if (in->f_mode & FMODE_READ) { | |
1440 | int fput_out; | |
1441 | struct file *out = fget_light(fdout, &fput_out); | |
1442 | ||
1443 | if (out) { | |
1444 | if (out->f_mode & FMODE_WRITE) | |
1445 | error = do_tee(in, out, len, flags); | |
1446 | fput_light(out, fput_out); | |
1447 | } | |
1448 | } | |
1449 | fput_light(in, fput_in); | |
1450 | } | |
1451 | ||
1452 | return error; | |
1453 | } |