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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 | |
12 | * Jens to support splicing to files, network, direct splicing, etc and | |
13 | * fixing lots of bugs. | |
14 | * | |
15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> | |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> | |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> | |
18 | * | |
19 | */ | |
20 | #include <linux/bvec.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/file.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/splice.h> | |
25 | #include <linux/memcontrol.h> | |
26 | #include <linux/mm_inline.h> | |
27 | #include <linux/swap.h> | |
28 | #include <linux/writeback.h> | |
29 | #include <linux/export.h> | |
30 | #include <linux/syscalls.h> | |
31 | #include <linux/uio.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/gfp.h> | |
34 | #include <linux/socket.h> | |
35 | #include <linux/compat.h> | |
36 | #include <linux/sched/signal.h> | |
37 | ||
38 | #include "internal.h" | |
39 | ||
40 | /* | |
41 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
42 | * a vm helper function, it's already simplified quite a bit by the | |
43 | * addition of remove_mapping(). If success is returned, the caller may | |
44 | * attempt to reuse this page for another destination. | |
45 | */ | |
46 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, | |
47 | struct pipe_buffer *buf) | |
48 | { | |
49 | struct page *page = buf->page; | |
50 | struct address_space *mapping; | |
51 | ||
52 | lock_page(page); | |
53 | ||
54 | mapping = page_mapping(page); | |
55 | if (mapping) { | |
56 | WARN_ON(!PageUptodate(page)); | |
57 | ||
58 | /* | |
59 | * At least for ext2 with nobh option, we need to wait on | |
60 | * writeback completing on this page, since we'll remove it | |
61 | * from the pagecache. Otherwise truncate wont wait on the | |
62 | * page, allowing the disk blocks to be reused by someone else | |
63 | * before we actually wrote our data to them. fs corruption | |
64 | * ensues. | |
65 | */ | |
66 | wait_on_page_writeback(page); | |
67 | ||
68 | if (page_has_private(page) && | |
69 | !try_to_release_page(page, GFP_KERNEL)) | |
70 | goto out_unlock; | |
71 | ||
72 | /* | |
73 | * If we succeeded in removing the mapping, set LRU flag | |
74 | * and return good. | |
75 | */ | |
76 | if (remove_mapping(mapping, page)) { | |
77 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
78 | return 0; | |
79 | } | |
80 | } | |
81 | ||
82 | /* | |
83 | * Raced with truncate or failed to remove page from current | |
84 | * address space, unlock and return failure. | |
85 | */ | |
86 | out_unlock: | |
87 | unlock_page(page); | |
88 | return 1; | |
89 | } | |
90 | ||
91 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, | |
92 | struct pipe_buffer *buf) | |
93 | { | |
94 | put_page(buf->page); | |
95 | buf->flags &= ~PIPE_BUF_FLAG_LRU; | |
96 | } | |
97 | ||
98 | /* | |
99 | * Check whether the contents of buf is OK to access. Since the content | |
100 | * is a page cache page, IO may be in flight. | |
101 | */ | |
102 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, | |
103 | struct pipe_buffer *buf) | |
104 | { | |
105 | struct page *page = buf->page; | |
106 | int err; | |
107 | ||
108 | if (!PageUptodate(page)) { | |
109 | lock_page(page); | |
110 | ||
111 | /* | |
112 | * Page got truncated/unhashed. This will cause a 0-byte | |
113 | * splice, if this is the first page. | |
114 | */ | |
115 | if (!page->mapping) { | |
116 | err = -ENODATA; | |
117 | goto error; | |
118 | } | |
119 | ||
120 | /* | |
121 | * Uh oh, read-error from disk. | |
122 | */ | |
123 | if (!PageUptodate(page)) { | |
124 | err = -EIO; | |
125 | goto error; | |
126 | } | |
127 | ||
128 | /* | |
129 | * Page is ok afterall, we are done. | |
130 | */ | |
131 | unlock_page(page); | |
132 | } | |
133 | ||
134 | return 0; | |
135 | error: | |
136 | unlock_page(page); | |
137 | return err; | |
138 | } | |
139 | ||
140 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { | |
141 | .can_merge = 0, | |
142 | .confirm = page_cache_pipe_buf_confirm, | |
143 | .release = page_cache_pipe_buf_release, | |
144 | .steal = page_cache_pipe_buf_steal, | |
145 | .get = generic_pipe_buf_get, | |
146 | }; | |
147 | ||
148 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, | |
149 | struct pipe_buffer *buf) | |
150 | { | |
151 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) | |
152 | return 1; | |
153 | ||
154 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
155 | return generic_pipe_buf_steal(pipe, buf); | |
156 | } | |
157 | ||
158 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { | |
159 | .can_merge = 0, | |
160 | .confirm = generic_pipe_buf_confirm, | |
161 | .release = page_cache_pipe_buf_release, | |
162 | .steal = user_page_pipe_buf_steal, | |
163 | .get = generic_pipe_buf_get, | |
164 | }; | |
165 | ||
166 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) | |
167 | { | |
168 | smp_mb(); | |
169 | if (waitqueue_active(&pipe->wait)) | |
170 | wake_up_interruptible(&pipe->wait); | |
171 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
172 | } | |
173 | ||
174 | /** | |
175 | * splice_to_pipe - fill passed data into a pipe | |
176 | * @pipe: pipe to fill | |
177 | * @spd: data to fill | |
178 | * | |
179 | * Description: | |
180 | * @spd contains a map of pages and len/offset tuples, along with | |
181 | * the struct pipe_buf_operations associated with these pages. This | |
182 | * function will link that data to the pipe. | |
183 | * | |
184 | */ | |
185 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, | |
186 | struct splice_pipe_desc *spd) | |
187 | { | |
188 | unsigned int spd_pages = spd->nr_pages; | |
189 | int ret = 0, page_nr = 0; | |
190 | ||
191 | if (!spd_pages) | |
192 | return 0; | |
193 | ||
194 | if (unlikely(!pipe->readers)) { | |
195 | send_sig(SIGPIPE, current, 0); | |
196 | ret = -EPIPE; | |
197 | goto out; | |
198 | } | |
199 | ||
200 | while (pipe->nrbufs < pipe->buffers) { | |
201 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
202 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
203 | ||
204 | buf->page = spd->pages[page_nr]; | |
205 | buf->offset = spd->partial[page_nr].offset; | |
206 | buf->len = spd->partial[page_nr].len; | |
207 | buf->private = spd->partial[page_nr].private; | |
208 | buf->ops = spd->ops; | |
209 | buf->flags = 0; | |
210 | ||
211 | pipe->nrbufs++; | |
212 | page_nr++; | |
213 | ret += buf->len; | |
214 | ||
215 | if (!--spd->nr_pages) | |
216 | break; | |
217 | } | |
218 | ||
219 | if (!ret) | |
220 | ret = -EAGAIN; | |
221 | ||
222 | out: | |
223 | while (page_nr < spd_pages) | |
224 | spd->spd_release(spd, page_nr++); | |
225 | ||
226 | return ret; | |
227 | } | |
228 | EXPORT_SYMBOL_GPL(splice_to_pipe); | |
229 | ||
230 | ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) | |
231 | { | |
232 | int ret; | |
233 | ||
234 | if (unlikely(!pipe->readers)) { | |
235 | send_sig(SIGPIPE, current, 0); | |
236 | ret = -EPIPE; | |
237 | } else if (pipe->nrbufs == pipe->buffers) { | |
238 | ret = -EAGAIN; | |
239 | } else { | |
240 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
241 | pipe->bufs[newbuf] = *buf; | |
242 | pipe->nrbufs++; | |
243 | return buf->len; | |
244 | } | |
245 | pipe_buf_release(pipe, buf); | |
246 | return ret; | |
247 | } | |
248 | EXPORT_SYMBOL(add_to_pipe); | |
249 | ||
250 | /* | |
251 | * Check if we need to grow the arrays holding pages and partial page | |
252 | * descriptions. | |
253 | */ | |
254 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) | |
255 | { | |
256 | unsigned int buffers = READ_ONCE(pipe->buffers); | |
257 | ||
258 | spd->nr_pages_max = buffers; | |
259 | if (buffers <= PIPE_DEF_BUFFERS) | |
260 | return 0; | |
261 | ||
262 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); | |
263 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); | |
264 | ||
265 | if (spd->pages && spd->partial) | |
266 | return 0; | |
267 | ||
268 | kfree(spd->pages); | |
269 | kfree(spd->partial); | |
270 | return -ENOMEM; | |
271 | } | |
272 | ||
273 | void splice_shrink_spd(struct splice_pipe_desc *spd) | |
274 | { | |
275 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) | |
276 | return; | |
277 | ||
278 | kfree(spd->pages); | |
279 | kfree(spd->partial); | |
280 | } | |
281 | ||
282 | /** | |
283 | * generic_file_splice_read - splice data from file to a pipe | |
284 | * @in: file to splice from | |
285 | * @ppos: position in @in | |
286 | * @pipe: pipe to splice to | |
287 | * @len: number of bytes to splice | |
288 | * @flags: splice modifier flags | |
289 | * | |
290 | * Description: | |
291 | * Will read pages from given file and fill them into a pipe. Can be | |
292 | * used as long as it has more or less sane ->read_iter(). | |
293 | * | |
294 | */ | |
295 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, | |
296 | struct pipe_inode_info *pipe, size_t len, | |
297 | unsigned int flags) | |
298 | { | |
299 | struct iov_iter to; | |
300 | struct kiocb kiocb; | |
301 | int idx, ret; | |
302 | ||
303 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len); | |
304 | idx = to.idx; | |
305 | init_sync_kiocb(&kiocb, in); | |
306 | kiocb.ki_pos = *ppos; | |
307 | ret = call_read_iter(in, &kiocb, &to); | |
308 | if (ret > 0) { | |
309 | *ppos = kiocb.ki_pos; | |
310 | file_accessed(in); | |
311 | } else if (ret < 0) { | |
312 | to.idx = idx; | |
313 | to.iov_offset = 0; | |
314 | iov_iter_advance(&to, 0); /* to free what was emitted */ | |
315 | /* | |
316 | * callers of ->splice_read() expect -EAGAIN on | |
317 | * "can't put anything in there", rather than -EFAULT. | |
318 | */ | |
319 | if (ret == -EFAULT) | |
320 | ret = -EAGAIN; | |
321 | } | |
322 | ||
323 | return ret; | |
324 | } | |
325 | EXPORT_SYMBOL(generic_file_splice_read); | |
326 | ||
327 | const struct pipe_buf_operations default_pipe_buf_ops = { | |
328 | .can_merge = 0, | |
329 | .confirm = generic_pipe_buf_confirm, | |
330 | .release = generic_pipe_buf_release, | |
331 | .steal = generic_pipe_buf_steal, | |
332 | .get = generic_pipe_buf_get, | |
333 | }; | |
334 | ||
335 | static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe, | |
336 | struct pipe_buffer *buf) | |
337 | { | |
338 | return 1; | |
339 | } | |
340 | ||
341 | /* Pipe buffer operations for a socket and similar. */ | |
342 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { | |
343 | .can_merge = 0, | |
344 | .confirm = generic_pipe_buf_confirm, | |
345 | .release = generic_pipe_buf_release, | |
346 | .steal = generic_pipe_buf_nosteal, | |
347 | .get = generic_pipe_buf_get, | |
348 | }; | |
349 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); | |
350 | ||
351 | static ssize_t kernel_readv(struct file *file, const struct kvec *vec, | |
352 | unsigned long vlen, loff_t offset) | |
353 | { | |
354 | mm_segment_t old_fs; | |
355 | loff_t pos = offset; | |
356 | ssize_t res; | |
357 | ||
358 | old_fs = get_fs(); | |
359 | set_fs(get_ds()); | |
360 | /* The cast to a user pointer is valid due to the set_fs() */ | |
361 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0); | |
362 | set_fs(old_fs); | |
363 | ||
364 | return res; | |
365 | } | |
366 | ||
367 | static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, | |
368 | struct pipe_inode_info *pipe, size_t len, | |
369 | unsigned int flags) | |
370 | { | |
371 | struct kvec *vec, __vec[PIPE_DEF_BUFFERS]; | |
372 | struct iov_iter to; | |
373 | struct page **pages; | |
374 | unsigned int nr_pages; | |
375 | size_t offset, base, copied = 0; | |
376 | ssize_t res; | |
377 | int i; | |
378 | ||
379 | if (pipe->nrbufs == pipe->buffers) | |
380 | return -EAGAIN; | |
381 | ||
382 | /* | |
383 | * Try to keep page boundaries matching to source pagecache ones - | |
384 | * it probably won't be much help, but... | |
385 | */ | |
386 | offset = *ppos & ~PAGE_MASK; | |
387 | ||
388 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset); | |
389 | ||
390 | res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &base); | |
391 | if (res <= 0) | |
392 | return -ENOMEM; | |
393 | ||
394 | nr_pages = DIV_ROUND_UP(res + base, PAGE_SIZE); | |
395 | ||
396 | vec = __vec; | |
397 | if (nr_pages > PIPE_DEF_BUFFERS) { | |
398 | vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL); | |
399 | if (unlikely(!vec)) { | |
400 | res = -ENOMEM; | |
401 | goto out; | |
402 | } | |
403 | } | |
404 | ||
405 | pipe->bufs[to.idx].offset = offset; | |
406 | pipe->bufs[to.idx].len -= offset; | |
407 | ||
408 | for (i = 0; i < nr_pages; i++) { | |
409 | size_t this_len = min_t(size_t, len, PAGE_SIZE - offset); | |
410 | vec[i].iov_base = page_address(pages[i]) + offset; | |
411 | vec[i].iov_len = this_len; | |
412 | len -= this_len; | |
413 | offset = 0; | |
414 | } | |
415 | ||
416 | res = kernel_readv(in, vec, nr_pages, *ppos); | |
417 | if (res > 0) { | |
418 | copied = res; | |
419 | *ppos += res; | |
420 | } | |
421 | ||
422 | if (vec != __vec) | |
423 | kfree(vec); | |
424 | out: | |
425 | for (i = 0; i < nr_pages; i++) | |
426 | put_page(pages[i]); | |
427 | kvfree(pages); | |
428 | iov_iter_advance(&to, copied); /* truncates and discards */ | |
429 | return res; | |
430 | } | |
431 | ||
432 | /* | |
433 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' | |
434 | * using sendpage(). Return the number of bytes sent. | |
435 | */ | |
436 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, | |
437 | struct pipe_buffer *buf, struct splice_desc *sd) | |
438 | { | |
439 | struct file *file = sd->u.file; | |
440 | loff_t pos = sd->pos; | |
441 | int more; | |
442 | ||
443 | if (!likely(file->f_op->sendpage)) | |
444 | return -EINVAL; | |
445 | ||
446 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; | |
447 | ||
448 | if (sd->len < sd->total_len && pipe->nrbufs > 1) | |
449 | more |= MSG_SENDPAGE_NOTLAST; | |
450 | ||
451 | return file->f_op->sendpage(file, buf->page, buf->offset, | |
452 | sd->len, &pos, more); | |
453 | } | |
454 | ||
455 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) | |
456 | { | |
457 | smp_mb(); | |
458 | if (waitqueue_active(&pipe->wait)) | |
459 | wake_up_interruptible(&pipe->wait); | |
460 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
461 | } | |
462 | ||
463 | /** | |
464 | * splice_from_pipe_feed - feed available data from a pipe to a file | |
465 | * @pipe: pipe to splice from | |
466 | * @sd: information to @actor | |
467 | * @actor: handler that splices the data | |
468 | * | |
469 | * Description: | |
470 | * This function loops over the pipe and calls @actor to do the | |
471 | * actual moving of a single struct pipe_buffer to the desired | |
472 | * destination. It returns when there's no more buffers left in | |
473 | * the pipe or if the requested number of bytes (@sd->total_len) | |
474 | * have been copied. It returns a positive number (one) if the | |
475 | * pipe needs to be filled with more data, zero if the required | |
476 | * number of bytes have been copied and -errno on error. | |
477 | * | |
478 | * This, together with splice_from_pipe_{begin,end,next}, may be | |
479 | * used to implement the functionality of __splice_from_pipe() when | |
480 | * locking is required around copying the pipe buffers to the | |
481 | * destination. | |
482 | */ | |
483 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
484 | splice_actor *actor) | |
485 | { | |
486 | int ret; | |
487 | ||
488 | while (pipe->nrbufs) { | |
489 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
490 | ||
491 | sd->len = buf->len; | |
492 | if (sd->len > sd->total_len) | |
493 | sd->len = sd->total_len; | |
494 | ||
495 | ret = pipe_buf_confirm(pipe, buf); | |
496 | if (unlikely(ret)) { | |
497 | if (ret == -ENODATA) | |
498 | ret = 0; | |
499 | return ret; | |
500 | } | |
501 | ||
502 | ret = actor(pipe, buf, sd); | |
503 | if (ret <= 0) | |
504 | return ret; | |
505 | ||
506 | buf->offset += ret; | |
507 | buf->len -= ret; | |
508 | ||
509 | sd->num_spliced += ret; | |
510 | sd->len -= ret; | |
511 | sd->pos += ret; | |
512 | sd->total_len -= ret; | |
513 | ||
514 | if (!buf->len) { | |
515 | pipe_buf_release(pipe, buf); | |
516 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); | |
517 | pipe->nrbufs--; | |
518 | if (pipe->files) | |
519 | sd->need_wakeup = true; | |
520 | } | |
521 | ||
522 | if (!sd->total_len) | |
523 | return 0; | |
524 | } | |
525 | ||
526 | return 1; | |
527 | } | |
528 | ||
529 | /** | |
530 | * splice_from_pipe_next - wait for some data to splice from | |
531 | * @pipe: pipe to splice from | |
532 | * @sd: information about the splice operation | |
533 | * | |
534 | * Description: | |
535 | * This function will wait for some data and return a positive | |
536 | * value (one) if pipe buffers are available. It will return zero | |
537 | * or -errno if no more data needs to be spliced. | |
538 | */ | |
539 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) | |
540 | { | |
541 | /* | |
542 | * Check for signal early to make process killable when there are | |
543 | * always buffers available | |
544 | */ | |
545 | if (signal_pending(current)) | |
546 | return -ERESTARTSYS; | |
547 | ||
548 | while (!pipe->nrbufs) { | |
549 | if (!pipe->writers) | |
550 | return 0; | |
551 | ||
552 | if (!pipe->waiting_writers && sd->num_spliced) | |
553 | return 0; | |
554 | ||
555 | if (sd->flags & SPLICE_F_NONBLOCK) | |
556 | return -EAGAIN; | |
557 | ||
558 | if (signal_pending(current)) | |
559 | return -ERESTARTSYS; | |
560 | ||
561 | if (sd->need_wakeup) { | |
562 | wakeup_pipe_writers(pipe); | |
563 | sd->need_wakeup = false; | |
564 | } | |
565 | ||
566 | pipe_wait(pipe); | |
567 | } | |
568 | ||
569 | return 1; | |
570 | } | |
571 | ||
572 | /** | |
573 | * splice_from_pipe_begin - start splicing from pipe | |
574 | * @sd: information about the splice operation | |
575 | * | |
576 | * Description: | |
577 | * This function should be called before a loop containing | |
578 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
579 | * initialize the necessary fields of @sd. | |
580 | */ | |
581 | static void splice_from_pipe_begin(struct splice_desc *sd) | |
582 | { | |
583 | sd->num_spliced = 0; | |
584 | sd->need_wakeup = false; | |
585 | } | |
586 | ||
587 | /** | |
588 | * splice_from_pipe_end - finish splicing from pipe | |
589 | * @pipe: pipe to splice from | |
590 | * @sd: information about the splice operation | |
591 | * | |
592 | * Description: | |
593 | * This function will wake up pipe writers if necessary. It should | |
594 | * be called after a loop containing splice_from_pipe_next() and | |
595 | * splice_from_pipe_feed(). | |
596 | */ | |
597 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) | |
598 | { | |
599 | if (sd->need_wakeup) | |
600 | wakeup_pipe_writers(pipe); | |
601 | } | |
602 | ||
603 | /** | |
604 | * __splice_from_pipe - splice data from a pipe to given actor | |
605 | * @pipe: pipe to splice from | |
606 | * @sd: information to @actor | |
607 | * @actor: handler that splices the data | |
608 | * | |
609 | * Description: | |
610 | * This function does little more than loop over the pipe and call | |
611 | * @actor to do the actual moving of a single struct pipe_buffer to | |
612 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
613 | * pipe_to_user. | |
614 | * | |
615 | */ | |
616 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
617 | splice_actor *actor) | |
618 | { | |
619 | int ret; | |
620 | ||
621 | splice_from_pipe_begin(sd); | |
622 | do { | |
623 | cond_resched(); | |
624 | ret = splice_from_pipe_next(pipe, sd); | |
625 | if (ret > 0) | |
626 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
627 | } while (ret > 0); | |
628 | splice_from_pipe_end(pipe, sd); | |
629 | ||
630 | return sd->num_spliced ? sd->num_spliced : ret; | |
631 | } | |
632 | EXPORT_SYMBOL(__splice_from_pipe); | |
633 | ||
634 | /** | |
635 | * splice_from_pipe - splice data from a pipe to a file | |
636 | * @pipe: pipe to splice from | |
637 | * @out: file to splice to | |
638 | * @ppos: position in @out | |
639 | * @len: how many bytes to splice | |
640 | * @flags: splice modifier flags | |
641 | * @actor: handler that splices the data | |
642 | * | |
643 | * Description: | |
644 | * See __splice_from_pipe. This function locks the pipe inode, | |
645 | * otherwise it's identical to __splice_from_pipe(). | |
646 | * | |
647 | */ | |
648 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, | |
649 | loff_t *ppos, size_t len, unsigned int flags, | |
650 | splice_actor *actor) | |
651 | { | |
652 | ssize_t ret; | |
653 | struct splice_desc sd = { | |
654 | .total_len = len, | |
655 | .flags = flags, | |
656 | .pos = *ppos, | |
657 | .u.file = out, | |
658 | }; | |
659 | ||
660 | pipe_lock(pipe); | |
661 | ret = __splice_from_pipe(pipe, &sd, actor); | |
662 | pipe_unlock(pipe); | |
663 | ||
664 | return ret; | |
665 | } | |
666 | ||
667 | /** | |
668 | * iter_file_splice_write - splice data from a pipe to a file | |
669 | * @pipe: pipe info | |
670 | * @out: file to write to | |
671 | * @ppos: position in @out | |
672 | * @len: number of bytes to splice | |
673 | * @flags: splice modifier flags | |
674 | * | |
675 | * Description: | |
676 | * Will either move or copy pages (determined by @flags options) from | |
677 | * the given pipe inode to the given file. | |
678 | * This one is ->write_iter-based. | |
679 | * | |
680 | */ | |
681 | ssize_t | |
682 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
683 | loff_t *ppos, size_t len, unsigned int flags) | |
684 | { | |
685 | struct splice_desc sd = { | |
686 | .total_len = len, | |
687 | .flags = flags, | |
688 | .pos = *ppos, | |
689 | .u.file = out, | |
690 | }; | |
691 | int nbufs = pipe->buffers; | |
692 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), | |
693 | GFP_KERNEL); | |
694 | ssize_t ret; | |
695 | ||
696 | if (unlikely(!array)) | |
697 | return -ENOMEM; | |
698 | ||
699 | pipe_lock(pipe); | |
700 | ||
701 | splice_from_pipe_begin(&sd); | |
702 | while (sd.total_len) { | |
703 | struct iov_iter from; | |
704 | size_t left; | |
705 | int n, idx; | |
706 | ||
707 | ret = splice_from_pipe_next(pipe, &sd); | |
708 | if (ret <= 0) | |
709 | break; | |
710 | ||
711 | if (unlikely(nbufs < pipe->buffers)) { | |
712 | kfree(array); | |
713 | nbufs = pipe->buffers; | |
714 | array = kcalloc(nbufs, sizeof(struct bio_vec), | |
715 | GFP_KERNEL); | |
716 | if (!array) { | |
717 | ret = -ENOMEM; | |
718 | break; | |
719 | } | |
720 | } | |
721 | ||
722 | /* build the vector */ | |
723 | left = sd.total_len; | |
724 | for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) { | |
725 | struct pipe_buffer *buf = pipe->bufs + idx; | |
726 | size_t this_len = buf->len; | |
727 | ||
728 | if (this_len > left) | |
729 | this_len = left; | |
730 | ||
731 | if (idx == pipe->buffers - 1) | |
732 | idx = -1; | |
733 | ||
734 | ret = pipe_buf_confirm(pipe, buf); | |
735 | if (unlikely(ret)) { | |
736 | if (ret == -ENODATA) | |
737 | ret = 0; | |
738 | goto done; | |
739 | } | |
740 | ||
741 | array[n].bv_page = buf->page; | |
742 | array[n].bv_len = this_len; | |
743 | array[n].bv_offset = buf->offset; | |
744 | left -= this_len; | |
745 | } | |
746 | ||
747 | iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n, | |
748 | sd.total_len - left); | |
749 | ret = vfs_iter_write(out, &from, &sd.pos, 0); | |
750 | if (ret <= 0) | |
751 | break; | |
752 | ||
753 | sd.num_spliced += ret; | |
754 | sd.total_len -= ret; | |
755 | *ppos = sd.pos; | |
756 | ||
757 | /* dismiss the fully eaten buffers, adjust the partial one */ | |
758 | while (ret) { | |
759 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
760 | if (ret >= buf->len) { | |
761 | ret -= buf->len; | |
762 | buf->len = 0; | |
763 | pipe_buf_release(pipe, buf); | |
764 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); | |
765 | pipe->nrbufs--; | |
766 | if (pipe->files) | |
767 | sd.need_wakeup = true; | |
768 | } else { | |
769 | buf->offset += ret; | |
770 | buf->len -= ret; | |
771 | ret = 0; | |
772 | } | |
773 | } | |
774 | } | |
775 | done: | |
776 | kfree(array); | |
777 | splice_from_pipe_end(pipe, &sd); | |
778 | ||
779 | pipe_unlock(pipe); | |
780 | ||
781 | if (sd.num_spliced) | |
782 | ret = sd.num_spliced; | |
783 | ||
784 | return ret; | |
785 | } | |
786 | ||
787 | EXPORT_SYMBOL(iter_file_splice_write); | |
788 | ||
789 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, | |
790 | struct splice_desc *sd) | |
791 | { | |
792 | int ret; | |
793 | void *data; | |
794 | loff_t tmp = sd->pos; | |
795 | ||
796 | data = kmap(buf->page); | |
797 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); | |
798 | kunmap(buf->page); | |
799 | ||
800 | return ret; | |
801 | } | |
802 | ||
803 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, | |
804 | struct file *out, loff_t *ppos, | |
805 | size_t len, unsigned int flags) | |
806 | { | |
807 | ssize_t ret; | |
808 | ||
809 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); | |
810 | if (ret > 0) | |
811 | *ppos += ret; | |
812 | ||
813 | return ret; | |
814 | } | |
815 | ||
816 | /** | |
817 | * generic_splice_sendpage - splice data from a pipe to a socket | |
818 | * @pipe: pipe to splice from | |
819 | * @out: socket to write to | |
820 | * @ppos: position in @out | |
821 | * @len: number of bytes to splice | |
822 | * @flags: splice modifier flags | |
823 | * | |
824 | * Description: | |
825 | * Will send @len bytes from the pipe to a network socket. No data copying | |
826 | * is involved. | |
827 | * | |
828 | */ | |
829 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, | |
830 | loff_t *ppos, size_t len, unsigned int flags) | |
831 | { | |
832 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); | |
833 | } | |
834 | ||
835 | EXPORT_SYMBOL(generic_splice_sendpage); | |
836 | ||
837 | /* | |
838 | * Attempt to initiate a splice from pipe to file. | |
839 | */ | |
840 | long do_splice_from(struct pipe_inode_info *pipe, struct file *out, | |
841 | loff_t *ppos, size_t len, unsigned int flags) | |
842 | { | |
843 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, | |
844 | loff_t *, size_t, unsigned int); | |
845 | ||
846 | if (out->f_op->splice_write) | |
847 | splice_write = out->f_op->splice_write; | |
848 | else | |
849 | splice_write = default_file_splice_write; | |
850 | ||
851 | return splice_write(pipe, out, ppos, len, flags); | |
852 | } | |
853 | EXPORT_SYMBOL_GPL(do_splice_from); | |
854 | ||
855 | /* | |
856 | * Attempt to initiate a splice from a file to a pipe. | |
857 | */ | |
858 | long do_splice_to(struct file *in, loff_t *ppos, | |
859 | struct pipe_inode_info *pipe, size_t len, | |
860 | unsigned int flags) | |
861 | { | |
862 | ssize_t (*splice_read)(struct file *, loff_t *, | |
863 | struct pipe_inode_info *, size_t, unsigned int); | |
864 | int ret; | |
865 | ||
866 | if (unlikely(!(in->f_mode & FMODE_READ))) | |
867 | return -EBADF; | |
868 | ||
869 | ret = rw_verify_area(READ, in, ppos, len); | |
870 | if (unlikely(ret < 0)) | |
871 | return ret; | |
872 | ||
873 | if (unlikely(len > MAX_RW_COUNT)) | |
874 | len = MAX_RW_COUNT; | |
875 | ||
876 | if (in->f_op->splice_read) | |
877 | splice_read = in->f_op->splice_read; | |
878 | else | |
879 | splice_read = default_file_splice_read; | |
880 | ||
881 | return splice_read(in, ppos, pipe, len, flags); | |
882 | } | |
883 | EXPORT_SYMBOL_GPL(do_splice_to); | |
884 | ||
885 | /** | |
886 | * splice_direct_to_actor - splices data directly between two non-pipes | |
887 | * @in: file to splice from | |
888 | * @sd: actor information on where to splice to | |
889 | * @actor: handles the data splicing | |
890 | * | |
891 | * Description: | |
892 | * This is a special case helper to splice directly between two | |
893 | * points, without requiring an explicit pipe. Internally an allocated | |
894 | * pipe is cached in the process, and reused during the lifetime of | |
895 | * that process. | |
896 | * | |
897 | */ | |
898 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
899 | splice_direct_actor *actor) | |
900 | { | |
901 | struct pipe_inode_info *pipe; | |
902 | long ret, bytes; | |
903 | umode_t i_mode; | |
904 | size_t len; | |
905 | int i, flags, more; | |
906 | ||
907 | /* | |
908 | * We require the input being a regular file, as we don't want to | |
909 | * randomly drop data for eg socket -> socket splicing. Use the | |
910 | * piped splicing for that! | |
911 | */ | |
912 | i_mode = file_inode(in)->i_mode; | |
913 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
914 | return -EINVAL; | |
915 | ||
916 | /* | |
917 | * neither in nor out is a pipe, setup an internal pipe attached to | |
918 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
919 | */ | |
920 | pipe = current->splice_pipe; | |
921 | if (unlikely(!pipe)) { | |
922 | pipe = alloc_pipe_info(); | |
923 | if (!pipe) | |
924 | return -ENOMEM; | |
925 | ||
926 | /* | |
927 | * We don't have an immediate reader, but we'll read the stuff | |
928 | * out of the pipe right after the splice_to_pipe(). So set | |
929 | * PIPE_READERS appropriately. | |
930 | */ | |
931 | pipe->readers = 1; | |
932 | ||
933 | current->splice_pipe = pipe; | |
934 | } | |
935 | ||
936 | /* | |
937 | * Do the splice. | |
938 | */ | |
939 | ret = 0; | |
940 | bytes = 0; | |
941 | len = sd->total_len; | |
942 | flags = sd->flags; | |
943 | ||
944 | /* | |
945 | * Don't block on output, we have to drain the direct pipe. | |
946 | */ | |
947 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
948 | more = sd->flags & SPLICE_F_MORE; | |
949 | ||
950 | while (len) { | |
951 | size_t read_len; | |
952 | loff_t pos = sd->pos, prev_pos = pos; | |
953 | ||
954 | ret = do_splice_to(in, &pos, pipe, len, flags); | |
955 | if (unlikely(ret <= 0)) | |
956 | goto out_release; | |
957 | ||
958 | read_len = ret; | |
959 | sd->total_len = read_len; | |
960 | ||
961 | /* | |
962 | * If more data is pending, set SPLICE_F_MORE | |
963 | * If this is the last data and SPLICE_F_MORE was not set | |
964 | * initially, clears it. | |
965 | */ | |
966 | if (read_len < len) | |
967 | sd->flags |= SPLICE_F_MORE; | |
968 | else if (!more) | |
969 | sd->flags &= ~SPLICE_F_MORE; | |
970 | /* | |
971 | * NOTE: nonblocking mode only applies to the input. We | |
972 | * must not do the output in nonblocking mode as then we | |
973 | * could get stuck data in the internal pipe: | |
974 | */ | |
975 | ret = actor(pipe, sd); | |
976 | if (unlikely(ret <= 0)) { | |
977 | sd->pos = prev_pos; | |
978 | goto out_release; | |
979 | } | |
980 | ||
981 | bytes += ret; | |
982 | len -= ret; | |
983 | sd->pos = pos; | |
984 | ||
985 | if (ret < read_len) { | |
986 | sd->pos = prev_pos + ret; | |
987 | goto out_release; | |
988 | } | |
989 | } | |
990 | ||
991 | done: | |
992 | pipe->nrbufs = pipe->curbuf = 0; | |
993 | file_accessed(in); | |
994 | return bytes; | |
995 | ||
996 | out_release: | |
997 | /* | |
998 | * If we did an incomplete transfer we must release | |
999 | * the pipe buffers in question: | |
1000 | */ | |
1001 | for (i = 0; i < pipe->buffers; i++) { | |
1002 | struct pipe_buffer *buf = pipe->bufs + i; | |
1003 | ||
1004 | if (buf->ops) | |
1005 | pipe_buf_release(pipe, buf); | |
1006 | } | |
1007 | ||
1008 | if (!bytes) | |
1009 | bytes = ret; | |
1010 | ||
1011 | goto done; | |
1012 | } | |
1013 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1014 | ||
1015 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1016 | struct splice_desc *sd) | |
1017 | { | |
1018 | struct file *file = sd->u.file; | |
1019 | ||
1020 | return do_splice_from(pipe, file, sd->opos, sd->total_len, | |
1021 | sd->flags); | |
1022 | } | |
1023 | ||
1024 | /** | |
1025 | * do_splice_direct - splices data directly between two files | |
1026 | * @in: file to splice from | |
1027 | * @ppos: input file offset | |
1028 | * @out: file to splice to | |
1029 | * @opos: output file offset | |
1030 | * @len: number of bytes to splice | |
1031 | * @flags: splice modifier flags | |
1032 | * | |
1033 | * Description: | |
1034 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1035 | * doing it in the application would incur an extra system call | |
1036 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1037 | * can splice directly through a process-private pipe. | |
1038 | * | |
1039 | */ | |
1040 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, | |
1041 | loff_t *opos, size_t len, unsigned int flags) | |
1042 | { | |
1043 | struct splice_desc sd = { | |
1044 | .len = len, | |
1045 | .total_len = len, | |
1046 | .flags = flags, | |
1047 | .pos = *ppos, | |
1048 | .u.file = out, | |
1049 | .opos = opos, | |
1050 | }; | |
1051 | long ret; | |
1052 | ||
1053 | if (unlikely(!(out->f_mode & FMODE_WRITE))) | |
1054 | return -EBADF; | |
1055 | ||
1056 | if (unlikely(out->f_flags & O_APPEND)) | |
1057 | return -EINVAL; | |
1058 | ||
1059 | ret = rw_verify_area(WRITE, out, opos, len); | |
1060 | if (unlikely(ret < 0)) | |
1061 | return ret; | |
1062 | ||
1063 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); | |
1064 | if (ret > 0) | |
1065 | *ppos = sd.pos; | |
1066 | ||
1067 | return ret; | |
1068 | } | |
1069 | EXPORT_SYMBOL(do_splice_direct); | |
1070 | ||
1071 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) | |
1072 | { | |
1073 | for (;;) { | |
1074 | if (unlikely(!pipe->readers)) { | |
1075 | send_sig(SIGPIPE, current, 0); | |
1076 | return -EPIPE; | |
1077 | } | |
1078 | if (pipe->nrbufs != pipe->buffers) | |
1079 | return 0; | |
1080 | if (flags & SPLICE_F_NONBLOCK) | |
1081 | return -EAGAIN; | |
1082 | if (signal_pending(current)) | |
1083 | return -ERESTARTSYS; | |
1084 | pipe->waiting_writers++; | |
1085 | pipe_wait(pipe); | |
1086 | pipe->waiting_writers--; | |
1087 | } | |
1088 | } | |
1089 | ||
1090 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1091 | struct pipe_inode_info *opipe, | |
1092 | size_t len, unsigned int flags); | |
1093 | ||
1094 | /* | |
1095 | * Determine where to splice to/from. | |
1096 | */ | |
1097 | static long do_splice(struct file *in, loff_t __user *off_in, | |
1098 | struct file *out, loff_t __user *off_out, | |
1099 | size_t len, unsigned int flags) | |
1100 | { | |
1101 | struct pipe_inode_info *ipipe; | |
1102 | struct pipe_inode_info *opipe; | |
1103 | loff_t offset; | |
1104 | long ret; | |
1105 | ||
1106 | ipipe = get_pipe_info(in); | |
1107 | opipe = get_pipe_info(out); | |
1108 | ||
1109 | if (ipipe && opipe) { | |
1110 | if (off_in || off_out) | |
1111 | return -ESPIPE; | |
1112 | ||
1113 | if (!(in->f_mode & FMODE_READ)) | |
1114 | return -EBADF; | |
1115 | ||
1116 | if (!(out->f_mode & FMODE_WRITE)) | |
1117 | return -EBADF; | |
1118 | ||
1119 | /* Splicing to self would be fun, but... */ | |
1120 | if (ipipe == opipe) | |
1121 | return -EINVAL; | |
1122 | ||
1123 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); | |
1124 | } | |
1125 | ||
1126 | if (ipipe) { | |
1127 | if (off_in) | |
1128 | return -ESPIPE; | |
1129 | if (off_out) { | |
1130 | if (!(out->f_mode & FMODE_PWRITE)) | |
1131 | return -EINVAL; | |
1132 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) | |
1133 | return -EFAULT; | |
1134 | } else { | |
1135 | offset = out->f_pos; | |
1136 | } | |
1137 | ||
1138 | if (unlikely(!(out->f_mode & FMODE_WRITE))) | |
1139 | return -EBADF; | |
1140 | ||
1141 | if (unlikely(out->f_flags & O_APPEND)) | |
1142 | return -EINVAL; | |
1143 | ||
1144 | ret = rw_verify_area(WRITE, out, &offset, len); | |
1145 | if (unlikely(ret < 0)) | |
1146 | return ret; | |
1147 | ||
1148 | file_start_write(out); | |
1149 | ret = do_splice_from(ipipe, out, &offset, len, flags); | |
1150 | file_end_write(out); | |
1151 | ||
1152 | if (!off_out) | |
1153 | out->f_pos = offset; | |
1154 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) | |
1155 | ret = -EFAULT; | |
1156 | ||
1157 | return ret; | |
1158 | } | |
1159 | ||
1160 | if (opipe) { | |
1161 | if (off_out) | |
1162 | return -ESPIPE; | |
1163 | if (off_in) { | |
1164 | if (!(in->f_mode & FMODE_PREAD)) | |
1165 | return -EINVAL; | |
1166 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) | |
1167 | return -EFAULT; | |
1168 | } else { | |
1169 | offset = in->f_pos; | |
1170 | } | |
1171 | ||
1172 | pipe_lock(opipe); | |
1173 | ret = wait_for_space(opipe, flags); | |
1174 | if (!ret) | |
1175 | ret = do_splice_to(in, &offset, opipe, len, flags); | |
1176 | pipe_unlock(opipe); | |
1177 | if (ret > 0) | |
1178 | wakeup_pipe_readers(opipe); | |
1179 | if (!off_in) | |
1180 | in->f_pos = offset; | |
1181 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) | |
1182 | ret = -EFAULT; | |
1183 | ||
1184 | return ret; | |
1185 | } | |
1186 | ||
1187 | return -EINVAL; | |
1188 | } | |
1189 | ||
1190 | static int iter_to_pipe(struct iov_iter *from, | |
1191 | struct pipe_inode_info *pipe, | |
1192 | unsigned flags) | |
1193 | { | |
1194 | struct pipe_buffer buf = { | |
1195 | .ops = &user_page_pipe_buf_ops, | |
1196 | .flags = flags | |
1197 | }; | |
1198 | size_t total = 0; | |
1199 | int ret = 0; | |
1200 | bool failed = false; | |
1201 | ||
1202 | while (iov_iter_count(from) && !failed) { | |
1203 | struct page *pages[16]; | |
1204 | ssize_t copied; | |
1205 | size_t start; | |
1206 | int n; | |
1207 | ||
1208 | copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start); | |
1209 | if (copied <= 0) { | |
1210 | ret = copied; | |
1211 | break; | |
1212 | } | |
1213 | ||
1214 | for (n = 0; copied; n++, start = 0) { | |
1215 | int size = min_t(int, copied, PAGE_SIZE - start); | |
1216 | if (!failed) { | |
1217 | buf.page = pages[n]; | |
1218 | buf.offset = start; | |
1219 | buf.len = size; | |
1220 | ret = add_to_pipe(pipe, &buf); | |
1221 | if (unlikely(ret < 0)) { | |
1222 | failed = true; | |
1223 | } else { | |
1224 | iov_iter_advance(from, ret); | |
1225 | total += ret; | |
1226 | } | |
1227 | } else { | |
1228 | put_page(pages[n]); | |
1229 | } | |
1230 | copied -= size; | |
1231 | } | |
1232 | } | |
1233 | return total ? total : ret; | |
1234 | } | |
1235 | ||
1236 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, | |
1237 | struct splice_desc *sd) | |
1238 | { | |
1239 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); | |
1240 | return n == sd->len ? n : -EFAULT; | |
1241 | } | |
1242 | ||
1243 | /* | |
1244 | * For lack of a better implementation, implement vmsplice() to userspace | |
1245 | * as a simple copy of the pipes pages to the user iov. | |
1246 | */ | |
1247 | static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov, | |
1248 | unsigned long nr_segs, unsigned int flags) | |
1249 | { | |
1250 | struct pipe_inode_info *pipe; | |
1251 | struct splice_desc sd; | |
1252 | long ret; | |
1253 | struct iovec iovstack[UIO_FASTIOV]; | |
1254 | struct iovec *iov = iovstack; | |
1255 | struct iov_iter iter; | |
1256 | ||
1257 | pipe = get_pipe_info(file); | |
1258 | if (!pipe) | |
1259 | return -EBADF; | |
1260 | ||
1261 | ret = import_iovec(READ, uiov, nr_segs, | |
1262 | ARRAY_SIZE(iovstack), &iov, &iter); | |
1263 | if (ret < 0) | |
1264 | return ret; | |
1265 | ||
1266 | sd.total_len = iov_iter_count(&iter); | |
1267 | sd.len = 0; | |
1268 | sd.flags = flags; | |
1269 | sd.u.data = &iter; | |
1270 | sd.pos = 0; | |
1271 | ||
1272 | if (sd.total_len) { | |
1273 | pipe_lock(pipe); | |
1274 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1275 | pipe_unlock(pipe); | |
1276 | } | |
1277 | ||
1278 | kfree(iov); | |
1279 | return ret; | |
1280 | } | |
1281 | ||
1282 | /* | |
1283 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1284 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1285 | * to file). In both cases the output is a pipe, naturally. | |
1286 | */ | |
1287 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov, | |
1288 | unsigned long nr_segs, unsigned int flags) | |
1289 | { | |
1290 | struct pipe_inode_info *pipe; | |
1291 | struct iovec iovstack[UIO_FASTIOV]; | |
1292 | struct iovec *iov = iovstack; | |
1293 | struct iov_iter from; | |
1294 | long ret; | |
1295 | unsigned buf_flag = 0; | |
1296 | ||
1297 | if (flags & SPLICE_F_GIFT) | |
1298 | buf_flag = PIPE_BUF_FLAG_GIFT; | |
1299 | ||
1300 | pipe = get_pipe_info(file); | |
1301 | if (!pipe) | |
1302 | return -EBADF; | |
1303 | ||
1304 | ret = import_iovec(WRITE, uiov, nr_segs, | |
1305 | ARRAY_SIZE(iovstack), &iov, &from); | |
1306 | if (ret < 0) | |
1307 | return ret; | |
1308 | ||
1309 | pipe_lock(pipe); | |
1310 | ret = wait_for_space(pipe, flags); | |
1311 | if (!ret) | |
1312 | ret = iter_to_pipe(&from, pipe, buf_flag); | |
1313 | pipe_unlock(pipe); | |
1314 | if (ret > 0) | |
1315 | wakeup_pipe_readers(pipe); | |
1316 | kfree(iov); | |
1317 | return ret; | |
1318 | } | |
1319 | ||
1320 | /* | |
1321 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1322 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1323 | * operation that can be supported without any funky alignment restrictions | |
1324 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1325 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1326 | * solutions for that: | |
1327 | * | |
1328 | * - memcpy() the data internally, at which point we might as well just | |
1329 | * do a regular read() on the buffer anyway. | |
1330 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1331 | * has restriction limitations on both ends of the pipe). | |
1332 | * | |
1333 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1334 | * | |
1335 | */ | |
1336 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, | |
1337 | unsigned long, nr_segs, unsigned int, flags) | |
1338 | { | |
1339 | struct fd f; | |
1340 | long error; | |
1341 | ||
1342 | if (unlikely(flags & ~SPLICE_F_ALL)) | |
1343 | return -EINVAL; | |
1344 | if (unlikely(nr_segs > UIO_MAXIOV)) | |
1345 | return -EINVAL; | |
1346 | else if (unlikely(!nr_segs)) | |
1347 | return 0; | |
1348 | ||
1349 | error = -EBADF; | |
1350 | f = fdget(fd); | |
1351 | if (f.file) { | |
1352 | if (f.file->f_mode & FMODE_WRITE) | |
1353 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); | |
1354 | else if (f.file->f_mode & FMODE_READ) | |
1355 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); | |
1356 | ||
1357 | fdput(f); | |
1358 | } | |
1359 | ||
1360 | return error; | |
1361 | } | |
1362 | ||
1363 | #ifdef CONFIG_COMPAT | |
1364 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, | |
1365 | unsigned int, nr_segs, unsigned int, flags) | |
1366 | { | |
1367 | unsigned i; | |
1368 | struct iovec __user *iov; | |
1369 | if (nr_segs > UIO_MAXIOV) | |
1370 | return -EINVAL; | |
1371 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); | |
1372 | for (i = 0; i < nr_segs; i++) { | |
1373 | struct compat_iovec v; | |
1374 | if (get_user(v.iov_base, &iov32[i].iov_base) || | |
1375 | get_user(v.iov_len, &iov32[i].iov_len) || | |
1376 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || | |
1377 | put_user(v.iov_len, &iov[i].iov_len)) | |
1378 | return -EFAULT; | |
1379 | } | |
1380 | return sys_vmsplice(fd, iov, nr_segs, flags); | |
1381 | } | |
1382 | #endif | |
1383 | ||
1384 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, | |
1385 | int, fd_out, loff_t __user *, off_out, | |
1386 | size_t, len, unsigned int, flags) | |
1387 | { | |
1388 | struct fd in, out; | |
1389 | long error; | |
1390 | ||
1391 | if (unlikely(!len)) | |
1392 | return 0; | |
1393 | ||
1394 | if (unlikely(flags & ~SPLICE_F_ALL)) | |
1395 | return -EINVAL; | |
1396 | ||
1397 | error = -EBADF; | |
1398 | in = fdget(fd_in); | |
1399 | if (in.file) { | |
1400 | if (in.file->f_mode & FMODE_READ) { | |
1401 | out = fdget(fd_out); | |
1402 | if (out.file) { | |
1403 | if (out.file->f_mode & FMODE_WRITE) | |
1404 | error = do_splice(in.file, off_in, | |
1405 | out.file, off_out, | |
1406 | len, flags); | |
1407 | fdput(out); | |
1408 | } | |
1409 | } | |
1410 | fdput(in); | |
1411 | } | |
1412 | return error; | |
1413 | } | |
1414 | ||
1415 | /* | |
1416 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1417 | * return an appropriate error. | |
1418 | */ | |
1419 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1420 | { | |
1421 | int ret; | |
1422 | ||
1423 | /* | |
1424 | * Check ->nrbufs without the inode lock first. This function | |
1425 | * is speculative anyways, so missing one is ok. | |
1426 | */ | |
1427 | if (pipe->nrbufs) | |
1428 | return 0; | |
1429 | ||
1430 | ret = 0; | |
1431 | pipe_lock(pipe); | |
1432 | ||
1433 | while (!pipe->nrbufs) { | |
1434 | if (signal_pending(current)) { | |
1435 | ret = -ERESTARTSYS; | |
1436 | break; | |
1437 | } | |
1438 | if (!pipe->writers) | |
1439 | break; | |
1440 | if (!pipe->waiting_writers) { | |
1441 | if (flags & SPLICE_F_NONBLOCK) { | |
1442 | ret = -EAGAIN; | |
1443 | break; | |
1444 | } | |
1445 | } | |
1446 | pipe_wait(pipe); | |
1447 | } | |
1448 | ||
1449 | pipe_unlock(pipe); | |
1450 | return ret; | |
1451 | } | |
1452 | ||
1453 | /* | |
1454 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1455 | * return an appropriate error. | |
1456 | */ | |
1457 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1458 | { | |
1459 | int ret; | |
1460 | ||
1461 | /* | |
1462 | * Check ->nrbufs without the inode lock first. This function | |
1463 | * is speculative anyways, so missing one is ok. | |
1464 | */ | |
1465 | if (pipe->nrbufs < pipe->buffers) | |
1466 | return 0; | |
1467 | ||
1468 | ret = 0; | |
1469 | pipe_lock(pipe); | |
1470 | ||
1471 | while (pipe->nrbufs >= pipe->buffers) { | |
1472 | if (!pipe->readers) { | |
1473 | send_sig(SIGPIPE, current, 0); | |
1474 | ret = -EPIPE; | |
1475 | break; | |
1476 | } | |
1477 | if (flags & SPLICE_F_NONBLOCK) { | |
1478 | ret = -EAGAIN; | |
1479 | break; | |
1480 | } | |
1481 | if (signal_pending(current)) { | |
1482 | ret = -ERESTARTSYS; | |
1483 | break; | |
1484 | } | |
1485 | pipe->waiting_writers++; | |
1486 | pipe_wait(pipe); | |
1487 | pipe->waiting_writers--; | |
1488 | } | |
1489 | ||
1490 | pipe_unlock(pipe); | |
1491 | return ret; | |
1492 | } | |
1493 | ||
1494 | /* | |
1495 | * Splice contents of ipipe to opipe. | |
1496 | */ | |
1497 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1498 | struct pipe_inode_info *opipe, | |
1499 | size_t len, unsigned int flags) | |
1500 | { | |
1501 | struct pipe_buffer *ibuf, *obuf; | |
1502 | int ret = 0, nbuf; | |
1503 | bool input_wakeup = false; | |
1504 | ||
1505 | ||
1506 | retry: | |
1507 | ret = ipipe_prep(ipipe, flags); | |
1508 | if (ret) | |
1509 | return ret; | |
1510 | ||
1511 | ret = opipe_prep(opipe, flags); | |
1512 | if (ret) | |
1513 | return ret; | |
1514 | ||
1515 | /* | |
1516 | * Potential ABBA deadlock, work around it by ordering lock | |
1517 | * grabbing by pipe info address. Otherwise two different processes | |
1518 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1519 | */ | |
1520 | pipe_double_lock(ipipe, opipe); | |
1521 | ||
1522 | do { | |
1523 | if (!opipe->readers) { | |
1524 | send_sig(SIGPIPE, current, 0); | |
1525 | if (!ret) | |
1526 | ret = -EPIPE; | |
1527 | break; | |
1528 | } | |
1529 | ||
1530 | if (!ipipe->nrbufs && !ipipe->writers) | |
1531 | break; | |
1532 | ||
1533 | /* | |
1534 | * Cannot make any progress, because either the input | |
1535 | * pipe is empty or the output pipe is full. | |
1536 | */ | |
1537 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { | |
1538 | /* Already processed some buffers, break */ | |
1539 | if (ret) | |
1540 | break; | |
1541 | ||
1542 | if (flags & SPLICE_F_NONBLOCK) { | |
1543 | ret = -EAGAIN; | |
1544 | break; | |
1545 | } | |
1546 | ||
1547 | /* | |
1548 | * We raced with another reader/writer and haven't | |
1549 | * managed to process any buffers. A zero return | |
1550 | * value means EOF, so retry instead. | |
1551 | */ | |
1552 | pipe_unlock(ipipe); | |
1553 | pipe_unlock(opipe); | |
1554 | goto retry; | |
1555 | } | |
1556 | ||
1557 | ibuf = ipipe->bufs + ipipe->curbuf; | |
1558 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
1559 | obuf = opipe->bufs + nbuf; | |
1560 | ||
1561 | if (len >= ibuf->len) { | |
1562 | /* | |
1563 | * Simply move the whole buffer from ipipe to opipe | |
1564 | */ | |
1565 | *obuf = *ibuf; | |
1566 | ibuf->ops = NULL; | |
1567 | opipe->nrbufs++; | |
1568 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); | |
1569 | ipipe->nrbufs--; | |
1570 | input_wakeup = true; | |
1571 | } else { | |
1572 | /* | |
1573 | * Get a reference to this pipe buffer, | |
1574 | * so we can copy the contents over. | |
1575 | */ | |
1576 | pipe_buf_get(ipipe, ibuf); | |
1577 | *obuf = *ibuf; | |
1578 | ||
1579 | /* | |
1580 | * Don't inherit the gift flag, we need to | |
1581 | * prevent multiple steals of this page. | |
1582 | */ | |
1583 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1584 | ||
1585 | obuf->len = len; | |
1586 | opipe->nrbufs++; | |
1587 | ibuf->offset += obuf->len; | |
1588 | ibuf->len -= obuf->len; | |
1589 | } | |
1590 | ret += obuf->len; | |
1591 | len -= obuf->len; | |
1592 | } while (len); | |
1593 | ||
1594 | pipe_unlock(ipipe); | |
1595 | pipe_unlock(opipe); | |
1596 | ||
1597 | /* | |
1598 | * If we put data in the output pipe, wakeup any potential readers. | |
1599 | */ | |
1600 | if (ret > 0) | |
1601 | wakeup_pipe_readers(opipe); | |
1602 | ||
1603 | if (input_wakeup) | |
1604 | wakeup_pipe_writers(ipipe); | |
1605 | ||
1606 | return ret; | |
1607 | } | |
1608 | ||
1609 | /* | |
1610 | * Link contents of ipipe to opipe. | |
1611 | */ | |
1612 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1613 | struct pipe_inode_info *opipe, | |
1614 | size_t len, unsigned int flags) | |
1615 | { | |
1616 | struct pipe_buffer *ibuf, *obuf; | |
1617 | int ret = 0, i = 0, nbuf; | |
1618 | ||
1619 | /* | |
1620 | * Potential ABBA deadlock, work around it by ordering lock | |
1621 | * grabbing by pipe info address. Otherwise two different processes | |
1622 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1623 | */ | |
1624 | pipe_double_lock(ipipe, opipe); | |
1625 | ||
1626 | do { | |
1627 | if (!opipe->readers) { | |
1628 | send_sig(SIGPIPE, current, 0); | |
1629 | if (!ret) | |
1630 | ret = -EPIPE; | |
1631 | break; | |
1632 | } | |
1633 | ||
1634 | /* | |
1635 | * If we have iterated all input buffers or ran out of | |
1636 | * output room, break. | |
1637 | */ | |
1638 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) | |
1639 | break; | |
1640 | ||
1641 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); | |
1642 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
1643 | ||
1644 | /* | |
1645 | * Get a reference to this pipe buffer, | |
1646 | * so we can copy the contents over. | |
1647 | */ | |
1648 | pipe_buf_get(ipipe, ibuf); | |
1649 | ||
1650 | obuf = opipe->bufs + nbuf; | |
1651 | *obuf = *ibuf; | |
1652 | ||
1653 | /* | |
1654 | * Don't inherit the gift flag, we need to | |
1655 | * prevent multiple steals of this page. | |
1656 | */ | |
1657 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1658 | ||
1659 | if (obuf->len > len) | |
1660 | obuf->len = len; | |
1661 | ||
1662 | opipe->nrbufs++; | |
1663 | ret += obuf->len; | |
1664 | len -= obuf->len; | |
1665 | i++; | |
1666 | } while (len); | |
1667 | ||
1668 | /* | |
1669 | * return EAGAIN if we have the potential of some data in the | |
1670 | * future, otherwise just return 0 | |
1671 | */ | |
1672 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
1673 | ret = -EAGAIN; | |
1674 | ||
1675 | pipe_unlock(ipipe); | |
1676 | pipe_unlock(opipe); | |
1677 | ||
1678 | /* | |
1679 | * If we put data in the output pipe, wakeup any potential readers. | |
1680 | */ | |
1681 | if (ret > 0) | |
1682 | wakeup_pipe_readers(opipe); | |
1683 | ||
1684 | return ret; | |
1685 | } | |
1686 | ||
1687 | /* | |
1688 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1689 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1690 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1691 | * applicable one is SPLICE_F_NONBLOCK. | |
1692 | */ | |
1693 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1694 | unsigned int flags) | |
1695 | { | |
1696 | struct pipe_inode_info *ipipe = get_pipe_info(in); | |
1697 | struct pipe_inode_info *opipe = get_pipe_info(out); | |
1698 | int ret = -EINVAL; | |
1699 | ||
1700 | /* | |
1701 | * Duplicate the contents of ipipe to opipe without actually | |
1702 | * copying the data. | |
1703 | */ | |
1704 | if (ipipe && opipe && ipipe != opipe) { | |
1705 | /* | |
1706 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1707 | * ordering doesn't really matter. | |
1708 | */ | |
1709 | ret = ipipe_prep(ipipe, flags); | |
1710 | if (!ret) { | |
1711 | ret = opipe_prep(opipe, flags); | |
1712 | if (!ret) | |
1713 | ret = link_pipe(ipipe, opipe, len, flags); | |
1714 | } | |
1715 | } | |
1716 | ||
1717 | return ret; | |
1718 | } | |
1719 | ||
1720 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) | |
1721 | { | |
1722 | struct fd in; | |
1723 | int error; | |
1724 | ||
1725 | if (unlikely(flags & ~SPLICE_F_ALL)) | |
1726 | return -EINVAL; | |
1727 | ||
1728 | if (unlikely(!len)) | |
1729 | return 0; | |
1730 | ||
1731 | error = -EBADF; | |
1732 | in = fdget(fdin); | |
1733 | if (in.file) { | |
1734 | if (in.file->f_mode & FMODE_READ) { | |
1735 | struct fd out = fdget(fdout); | |
1736 | if (out.file) { | |
1737 | if (out.file->f_mode & FMODE_WRITE) | |
1738 | error = do_tee(in.file, out.file, | |
1739 | len, flags); | |
1740 | fdput(out); | |
1741 | } | |
1742 | } | |
1743 | fdput(in); | |
1744 | } | |
1745 | ||
1746 | return error; | |
1747 | } |