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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 "internal.h" | |
37 | ||
38 | /* | |
39 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
40 | * a vm helper function, it's already simplified quite a bit by the | |
41 | * addition of remove_mapping(). If success is returned, the caller may | |
42 | * attempt to reuse this page for another destination. | |
43 | */ | |
44 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, | |
45 | struct pipe_buffer *buf) | |
46 | { | |
47 | struct page *page = buf->page; | |
48 | struct address_space *mapping; | |
49 | ||
50 | lock_page(page); | |
51 | ||
52 | mapping = page_mapping(page); | |
53 | if (mapping) { | |
54 | WARN_ON(!PageUptodate(page)); | |
55 | ||
56 | /* | |
57 | * At least for ext2 with nobh option, we need to wait on | |
58 | * writeback completing on this page, since we'll remove it | |
59 | * from the pagecache. Otherwise truncate wont wait on the | |
60 | * page, allowing the disk blocks to be reused by someone else | |
61 | * before we actually wrote our data to them. fs corruption | |
62 | * ensues. | |
63 | */ | |
64 | wait_on_page_writeback(page); | |
65 | ||
66 | if (page_has_private(page) && | |
67 | !try_to_release_page(page, GFP_KERNEL)) | |
68 | goto out_unlock; | |
69 | ||
70 | /* | |
71 | * If we succeeded in removing the mapping, set LRU flag | |
72 | * and return good. | |
73 | */ | |
74 | if (remove_mapping(mapping, page)) { | |
75 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
76 | return 0; | |
77 | } | |
78 | } | |
79 | ||
80 | /* | |
81 | * Raced with truncate or failed to remove page from current | |
82 | * address space, unlock and return failure. | |
83 | */ | |
84 | out_unlock: | |
85 | unlock_page(page); | |
86 | return 1; | |
87 | } | |
88 | ||
89 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, | |
90 | struct pipe_buffer *buf) | |
91 | { | |
92 | put_page(buf->page); | |
93 | buf->flags &= ~PIPE_BUF_FLAG_LRU; | |
94 | } | |
95 | ||
96 | /* | |
97 | * Check whether the contents of buf is OK to access. Since the content | |
98 | * is a page cache page, IO may be in flight. | |
99 | */ | |
100 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, | |
101 | struct pipe_buffer *buf) | |
102 | { | |
103 | struct page *page = buf->page; | |
104 | int err; | |
105 | ||
106 | if (!PageUptodate(page)) { | |
107 | lock_page(page); | |
108 | ||
109 | /* | |
110 | * Page got truncated/unhashed. This will cause a 0-byte | |
111 | * splice, if this is the first page. | |
112 | */ | |
113 | if (!page->mapping) { | |
114 | err = -ENODATA; | |
115 | goto error; | |
116 | } | |
117 | ||
118 | /* | |
119 | * Uh oh, read-error from disk. | |
120 | */ | |
121 | if (!PageUptodate(page)) { | |
122 | err = -EIO; | |
123 | goto error; | |
124 | } | |
125 | ||
126 | /* | |
127 | * Page is ok afterall, we are done. | |
128 | */ | |
129 | unlock_page(page); | |
130 | } | |
131 | ||
132 | return 0; | |
133 | error: | |
134 | unlock_page(page); | |
135 | return err; | |
136 | } | |
137 | ||
138 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { | |
139 | .can_merge = 0, | |
140 | .confirm = page_cache_pipe_buf_confirm, | |
141 | .release = page_cache_pipe_buf_release, | |
142 | .steal = page_cache_pipe_buf_steal, | |
143 | .get = generic_pipe_buf_get, | |
144 | }; | |
145 | ||
146 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, | |
147 | struct pipe_buffer *buf) | |
148 | { | |
149 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) | |
150 | return 1; | |
151 | ||
152 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
153 | return generic_pipe_buf_steal(pipe, buf); | |
154 | } | |
155 | ||
156 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { | |
157 | .can_merge = 0, | |
158 | .confirm = generic_pipe_buf_confirm, | |
159 | .release = page_cache_pipe_buf_release, | |
160 | .steal = user_page_pipe_buf_steal, | |
161 | .get = generic_pipe_buf_get, | |
162 | }; | |
163 | ||
164 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) | |
165 | { | |
166 | smp_mb(); | |
167 | if (waitqueue_active(&pipe->wait)) | |
168 | wake_up_interruptible(&pipe->wait); | |
169 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
170 | } | |
171 | ||
172 | /** | |
173 | * splice_to_pipe - fill passed data into a pipe | |
174 | * @pipe: pipe to fill | |
175 | * @spd: data to fill | |
176 | * | |
177 | * Description: | |
178 | * @spd contains a map of pages and len/offset tuples, along with | |
179 | * the struct pipe_buf_operations associated with these pages. This | |
180 | * function will link that data to the pipe. | |
181 | * | |
182 | */ | |
183 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, | |
184 | struct splice_pipe_desc *spd) | |
185 | { | |
186 | unsigned int spd_pages = spd->nr_pages; | |
187 | int ret = 0, page_nr = 0; | |
188 | ||
189 | if (!spd_pages) | |
190 | return 0; | |
191 | ||
192 | if (unlikely(!pipe->readers)) { | |
193 | send_sig(SIGPIPE, current, 0); | |
194 | ret = -EPIPE; | |
195 | goto out; | |
196 | } | |
197 | ||
198 | while (pipe->nrbufs < pipe->buffers) { | |
199 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
200 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
201 | ||
202 | buf->page = spd->pages[page_nr]; | |
203 | buf->offset = spd->partial[page_nr].offset; | |
204 | buf->len = spd->partial[page_nr].len; | |
205 | buf->private = spd->partial[page_nr].private; | |
206 | buf->ops = spd->ops; | |
207 | ||
208 | pipe->nrbufs++; | |
209 | page_nr++; | |
210 | ret += buf->len; | |
211 | ||
212 | if (!--spd->nr_pages) | |
213 | break; | |
214 | } | |
215 | ||
216 | if (!ret) | |
217 | ret = -EAGAIN; | |
218 | ||
219 | out: | |
220 | while (page_nr < spd_pages) | |
221 | spd->spd_release(spd, page_nr++); | |
222 | ||
223 | return ret; | |
224 | } | |
225 | EXPORT_SYMBOL_GPL(splice_to_pipe); | |
226 | ||
227 | ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) | |
228 | { | |
229 | int ret; | |
230 | ||
231 | if (unlikely(!pipe->readers)) { | |
232 | send_sig(SIGPIPE, current, 0); | |
233 | ret = -EPIPE; | |
234 | } else if (pipe->nrbufs == pipe->buffers) { | |
235 | ret = -EAGAIN; | |
236 | } else { | |
237 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
238 | pipe->bufs[newbuf] = *buf; | |
239 | pipe->nrbufs++; | |
240 | return buf->len; | |
241 | } | |
242 | pipe_buf_release(pipe, buf); | |
243 | return ret; | |
244 | } | |
245 | EXPORT_SYMBOL(add_to_pipe); | |
246 | ||
247 | void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) | |
248 | { | |
249 | put_page(spd->pages[i]); | |
250 | } | |
251 | ||
252 | /* | |
253 | * Check if we need to grow the arrays holding pages and partial page | |
254 | * descriptions. | |
255 | */ | |
256 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) | |
257 | { | |
258 | unsigned int buffers = ACCESS_ONCE(pipe->buffers); | |
259 | ||
260 | spd->nr_pages_max = buffers; | |
261 | if (buffers <= PIPE_DEF_BUFFERS) | |
262 | return 0; | |
263 | ||
264 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); | |
265 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); | |
266 | ||
267 | if (spd->pages && spd->partial) | |
268 | return 0; | |
269 | ||
270 | kfree(spd->pages); | |
271 | kfree(spd->partial); | |
272 | return -ENOMEM; | |
273 | } | |
274 | ||
275 | void splice_shrink_spd(struct splice_pipe_desc *spd) | |
276 | { | |
277 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) | |
278 | return; | |
279 | ||
280 | kfree(spd->pages); | |
281 | kfree(spd->partial); | |
282 | } | |
283 | ||
284 | /** | |
285 | * generic_file_splice_read - splice data from file to a pipe | |
286 | * @in: file to splice from | |
287 | * @ppos: position in @in | |
288 | * @pipe: pipe to splice to | |
289 | * @len: number of bytes to splice | |
290 | * @flags: splice modifier flags | |
291 | * | |
292 | * Description: | |
293 | * Will read pages from given file and fill them into a pipe. Can be | |
294 | * used as long as it has more or less sane ->read_iter(). | |
295 | * | |
296 | */ | |
297 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, | |
298 | struct pipe_inode_info *pipe, size_t len, | |
299 | unsigned int flags) | |
300 | { | |
301 | struct iov_iter to; | |
302 | struct kiocb kiocb; | |
303 | int idx, ret; | |
304 | ||
305 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len); | |
306 | idx = to.idx; | |
307 | init_sync_kiocb(&kiocb, in); | |
308 | kiocb.ki_pos = *ppos; | |
309 | ret = in->f_op->read_iter(&kiocb, &to); | |
310 | if (ret > 0) { | |
311 | *ppos = kiocb.ki_pos; | |
312 | file_accessed(in); | |
313 | } else if (ret < 0) { | |
314 | to.idx = idx; | |
315 | to.iov_offset = 0; | |
316 | iov_iter_advance(&to, 0); /* to free what was emitted */ | |
317 | /* | |
318 | * callers of ->splice_read() expect -EAGAIN on | |
319 | * "can't put anything in there", rather than -EFAULT. | |
320 | */ | |
321 | if (ret == -EFAULT) | |
322 | ret = -EAGAIN; | |
323 | } | |
324 | ||
325 | return ret; | |
326 | } | |
327 | EXPORT_SYMBOL(generic_file_splice_read); | |
328 | ||
329 | const struct pipe_buf_operations default_pipe_buf_ops = { | |
330 | .can_merge = 0, | |
331 | .confirm = generic_pipe_buf_confirm, | |
332 | .release = generic_pipe_buf_release, | |
333 | .steal = generic_pipe_buf_steal, | |
334 | .get = generic_pipe_buf_get, | |
335 | }; | |
336 | ||
337 | static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe, | |
338 | struct pipe_buffer *buf) | |
339 | { | |
340 | return 1; | |
341 | } | |
342 | ||
343 | /* Pipe buffer operations for a socket and similar. */ | |
344 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { | |
345 | .can_merge = 0, | |
346 | .confirm = generic_pipe_buf_confirm, | |
347 | .release = generic_pipe_buf_release, | |
348 | .steal = generic_pipe_buf_nosteal, | |
349 | .get = generic_pipe_buf_get, | |
350 | }; | |
351 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); | |
352 | ||
353 | static ssize_t kernel_readv(struct file *file, const struct kvec *vec, | |
354 | unsigned long vlen, loff_t offset) | |
355 | { | |
356 | mm_segment_t old_fs; | |
357 | loff_t pos = offset; | |
358 | ssize_t res; | |
359 | ||
360 | old_fs = get_fs(); | |
361 | set_fs(get_ds()); | |
362 | /* The cast to a user pointer is valid due to the set_fs() */ | |
363 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0); | |
364 | set_fs(old_fs); | |
365 | ||
366 | return res; | |
367 | } | |
368 | ||
369 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, | |
370 | loff_t pos) | |
371 | { | |
372 | mm_segment_t old_fs; | |
373 | ssize_t res; | |
374 | ||
375 | old_fs = get_fs(); | |
376 | set_fs(get_ds()); | |
377 | /* The cast to a user pointer is valid due to the set_fs() */ | |
378 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); | |
379 | set_fs(old_fs); | |
380 | ||
381 | return res; | |
382 | } | |
383 | EXPORT_SYMBOL(kernel_write); | |
384 | ||
385 | static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, | |
386 | struct pipe_inode_info *pipe, size_t len, | |
387 | unsigned int flags) | |
388 | { | |
389 | struct kvec *vec, __vec[PIPE_DEF_BUFFERS]; | |
390 | struct iov_iter to; | |
391 | struct page **pages; | |
392 | unsigned int nr_pages; | |
393 | size_t offset, dummy, copied = 0; | |
394 | ssize_t res; | |
395 | int i; | |
396 | ||
397 | if (pipe->nrbufs == pipe->buffers) | |
398 | return -EAGAIN; | |
399 | ||
400 | /* | |
401 | * Try to keep page boundaries matching to source pagecache ones - | |
402 | * it probably won't be much help, but... | |
403 | */ | |
404 | offset = *ppos & ~PAGE_MASK; | |
405 | ||
406 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset); | |
407 | ||
408 | res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &dummy); | |
409 | if (res <= 0) | |
410 | return -ENOMEM; | |
411 | ||
412 | BUG_ON(dummy); | |
413 | nr_pages = DIV_ROUND_UP(res, PAGE_SIZE); | |
414 | ||
415 | vec = __vec; | |
416 | if (nr_pages > PIPE_DEF_BUFFERS) { | |
417 | vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL); | |
418 | if (unlikely(!vec)) { | |
419 | res = -ENOMEM; | |
420 | goto out; | |
421 | } | |
422 | } | |
423 | ||
424 | pipe->bufs[to.idx].offset = offset; | |
425 | pipe->bufs[to.idx].len -= offset; | |
426 | ||
427 | for (i = 0; i < nr_pages; i++) { | |
428 | size_t this_len = min_t(size_t, len, PAGE_SIZE - offset); | |
429 | vec[i].iov_base = page_address(pages[i]) + offset; | |
430 | vec[i].iov_len = this_len; | |
431 | len -= this_len; | |
432 | offset = 0; | |
433 | } | |
434 | ||
435 | res = kernel_readv(in, vec, nr_pages, *ppos); | |
436 | if (res > 0) { | |
437 | copied = res; | |
438 | *ppos += res; | |
439 | } | |
440 | ||
441 | if (vec != __vec) | |
442 | kfree(vec); | |
443 | out: | |
444 | for (i = 0; i < nr_pages; i++) | |
445 | put_page(pages[i]); | |
446 | kvfree(pages); | |
447 | iov_iter_advance(&to, copied); /* truncates and discards */ | |
448 | return res; | |
449 | } | |
450 | ||
451 | /* | |
452 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' | |
453 | * using sendpage(). Return the number of bytes sent. | |
454 | */ | |
455 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, | |
456 | struct pipe_buffer *buf, struct splice_desc *sd) | |
457 | { | |
458 | struct file *file = sd->u.file; | |
459 | loff_t pos = sd->pos; | |
460 | int more; | |
461 | ||
462 | if (!likely(file->f_op->sendpage)) | |
463 | return -EINVAL; | |
464 | ||
465 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; | |
466 | ||
467 | if (sd->len < sd->total_len && pipe->nrbufs > 1) | |
468 | more |= MSG_SENDPAGE_NOTLAST; | |
469 | ||
470 | return file->f_op->sendpage(file, buf->page, buf->offset, | |
471 | sd->len, &pos, more); | |
472 | } | |
473 | ||
474 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) | |
475 | { | |
476 | smp_mb(); | |
477 | if (waitqueue_active(&pipe->wait)) | |
478 | wake_up_interruptible(&pipe->wait); | |
479 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
480 | } | |
481 | ||
482 | /** | |
483 | * splice_from_pipe_feed - feed available data from a pipe to a file | |
484 | * @pipe: pipe to splice from | |
485 | * @sd: information to @actor | |
486 | * @actor: handler that splices the data | |
487 | * | |
488 | * Description: | |
489 | * This function loops over the pipe and calls @actor to do the | |
490 | * actual moving of a single struct pipe_buffer to the desired | |
491 | * destination. It returns when there's no more buffers left in | |
492 | * the pipe or if the requested number of bytes (@sd->total_len) | |
493 | * have been copied. It returns a positive number (one) if the | |
494 | * pipe needs to be filled with more data, zero if the required | |
495 | * number of bytes have been copied and -errno on error. | |
496 | * | |
497 | * This, together with splice_from_pipe_{begin,end,next}, may be | |
498 | * used to implement the functionality of __splice_from_pipe() when | |
499 | * locking is required around copying the pipe buffers to the | |
500 | * destination. | |
501 | */ | |
502 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
503 | splice_actor *actor) | |
504 | { | |
505 | int ret; | |
506 | ||
507 | while (pipe->nrbufs) { | |
508 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
509 | ||
510 | sd->len = buf->len; | |
511 | if (sd->len > sd->total_len) | |
512 | sd->len = sd->total_len; | |
513 | ||
514 | ret = pipe_buf_confirm(pipe, buf); | |
515 | if (unlikely(ret)) { | |
516 | if (ret == -ENODATA) | |
517 | ret = 0; | |
518 | return ret; | |
519 | } | |
520 | ||
521 | ret = actor(pipe, buf, sd); | |
522 | if (ret <= 0) | |
523 | return ret; | |
524 | ||
525 | buf->offset += ret; | |
526 | buf->len -= ret; | |
527 | ||
528 | sd->num_spliced += ret; | |
529 | sd->len -= ret; | |
530 | sd->pos += ret; | |
531 | sd->total_len -= ret; | |
532 | ||
533 | if (!buf->len) { | |
534 | pipe_buf_release(pipe, buf); | |
535 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); | |
536 | pipe->nrbufs--; | |
537 | if (pipe->files) | |
538 | sd->need_wakeup = true; | |
539 | } | |
540 | ||
541 | if (!sd->total_len) | |
542 | return 0; | |
543 | } | |
544 | ||
545 | return 1; | |
546 | } | |
547 | ||
548 | /** | |
549 | * splice_from_pipe_next - wait for some data to splice from | |
550 | * @pipe: pipe to splice from | |
551 | * @sd: information about the splice operation | |
552 | * | |
553 | * Description: | |
554 | * This function will wait for some data and return a positive | |
555 | * value (one) if pipe buffers are available. It will return zero | |
556 | * or -errno if no more data needs to be spliced. | |
557 | */ | |
558 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) | |
559 | { | |
560 | /* | |
561 | * Check for signal early to make process killable when there are | |
562 | * always buffers available | |
563 | */ | |
564 | if (signal_pending(current)) | |
565 | return -ERESTARTSYS; | |
566 | ||
567 | while (!pipe->nrbufs) { | |
568 | if (!pipe->writers) | |
569 | return 0; | |
570 | ||
571 | if (!pipe->waiting_writers && sd->num_spliced) | |
572 | return 0; | |
573 | ||
574 | if (sd->flags & SPLICE_F_NONBLOCK) | |
575 | return -EAGAIN; | |
576 | ||
577 | if (signal_pending(current)) | |
578 | return -ERESTARTSYS; | |
579 | ||
580 | if (sd->need_wakeup) { | |
581 | wakeup_pipe_writers(pipe); | |
582 | sd->need_wakeup = false; | |
583 | } | |
584 | ||
585 | pipe_wait(pipe); | |
586 | } | |
587 | ||
588 | return 1; | |
589 | } | |
590 | ||
591 | /** | |
592 | * splice_from_pipe_begin - start splicing from pipe | |
593 | * @sd: information about the splice operation | |
594 | * | |
595 | * Description: | |
596 | * This function should be called before a loop containing | |
597 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
598 | * initialize the necessary fields of @sd. | |
599 | */ | |
600 | static void splice_from_pipe_begin(struct splice_desc *sd) | |
601 | { | |
602 | sd->num_spliced = 0; | |
603 | sd->need_wakeup = false; | |
604 | } | |
605 | ||
606 | /** | |
607 | * splice_from_pipe_end - finish splicing from pipe | |
608 | * @pipe: pipe to splice from | |
609 | * @sd: information about the splice operation | |
610 | * | |
611 | * Description: | |
612 | * This function will wake up pipe writers if necessary. It should | |
613 | * be called after a loop containing splice_from_pipe_next() and | |
614 | * splice_from_pipe_feed(). | |
615 | */ | |
616 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) | |
617 | { | |
618 | if (sd->need_wakeup) | |
619 | wakeup_pipe_writers(pipe); | |
620 | } | |
621 | ||
622 | /** | |
623 | * __splice_from_pipe - splice data from a pipe to given actor | |
624 | * @pipe: pipe to splice from | |
625 | * @sd: information to @actor | |
626 | * @actor: handler that splices the data | |
627 | * | |
628 | * Description: | |
629 | * This function does little more than loop over the pipe and call | |
630 | * @actor to do the actual moving of a single struct pipe_buffer to | |
631 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
632 | * pipe_to_user. | |
633 | * | |
634 | */ | |
635 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
636 | splice_actor *actor) | |
637 | { | |
638 | int ret; | |
639 | ||
640 | splice_from_pipe_begin(sd); | |
641 | do { | |
642 | cond_resched(); | |
643 | ret = splice_from_pipe_next(pipe, sd); | |
644 | if (ret > 0) | |
645 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
646 | } while (ret > 0); | |
647 | splice_from_pipe_end(pipe, sd); | |
648 | ||
649 | return sd->num_spliced ? sd->num_spliced : ret; | |
650 | } | |
651 | EXPORT_SYMBOL(__splice_from_pipe); | |
652 | ||
653 | /** | |
654 | * splice_from_pipe - splice data from a pipe to a file | |
655 | * @pipe: pipe to splice from | |
656 | * @out: file to splice to | |
657 | * @ppos: position in @out | |
658 | * @len: how many bytes to splice | |
659 | * @flags: splice modifier flags | |
660 | * @actor: handler that splices the data | |
661 | * | |
662 | * Description: | |
663 | * See __splice_from_pipe. This function locks the pipe inode, | |
664 | * otherwise it's identical to __splice_from_pipe(). | |
665 | * | |
666 | */ | |
667 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, | |
668 | loff_t *ppos, size_t len, unsigned int flags, | |
669 | splice_actor *actor) | |
670 | { | |
671 | ssize_t ret; | |
672 | struct splice_desc sd = { | |
673 | .total_len = len, | |
674 | .flags = flags, | |
675 | .pos = *ppos, | |
676 | .u.file = out, | |
677 | }; | |
678 | ||
679 | pipe_lock(pipe); | |
680 | ret = __splice_from_pipe(pipe, &sd, actor); | |
681 | pipe_unlock(pipe); | |
682 | ||
683 | return ret; | |
684 | } | |
685 | ||
686 | /** | |
687 | * iter_file_splice_write - splice data from a pipe to a file | |
688 | * @pipe: pipe info | |
689 | * @out: file to write to | |
690 | * @ppos: position in @out | |
691 | * @len: number of bytes to splice | |
692 | * @flags: splice modifier flags | |
693 | * | |
694 | * Description: | |
695 | * Will either move or copy pages (determined by @flags options) from | |
696 | * the given pipe inode to the given file. | |
697 | * This one is ->write_iter-based. | |
698 | * | |
699 | */ | |
700 | ssize_t | |
701 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
702 | loff_t *ppos, size_t len, unsigned int flags) | |
703 | { | |
704 | struct splice_desc sd = { | |
705 | .total_len = len, | |
706 | .flags = flags, | |
707 | .pos = *ppos, | |
708 | .u.file = out, | |
709 | }; | |
710 | int nbufs = pipe->buffers; | |
711 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), | |
712 | GFP_KERNEL); | |
713 | ssize_t ret; | |
714 | ||
715 | if (unlikely(!array)) | |
716 | return -ENOMEM; | |
717 | ||
718 | pipe_lock(pipe); | |
719 | ||
720 | splice_from_pipe_begin(&sd); | |
721 | while (sd.total_len) { | |
722 | struct iov_iter from; | |
723 | size_t left; | |
724 | int n, idx; | |
725 | ||
726 | ret = splice_from_pipe_next(pipe, &sd); | |
727 | if (ret <= 0) | |
728 | break; | |
729 | ||
730 | if (unlikely(nbufs < pipe->buffers)) { | |
731 | kfree(array); | |
732 | nbufs = pipe->buffers; | |
733 | array = kcalloc(nbufs, sizeof(struct bio_vec), | |
734 | GFP_KERNEL); | |
735 | if (!array) { | |
736 | ret = -ENOMEM; | |
737 | break; | |
738 | } | |
739 | } | |
740 | ||
741 | /* build the vector */ | |
742 | left = sd.total_len; | |
743 | for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) { | |
744 | struct pipe_buffer *buf = pipe->bufs + idx; | |
745 | size_t this_len = buf->len; | |
746 | ||
747 | if (this_len > left) | |
748 | this_len = left; | |
749 | ||
750 | if (idx == pipe->buffers - 1) | |
751 | idx = -1; | |
752 | ||
753 | ret = pipe_buf_confirm(pipe, buf); | |
754 | if (unlikely(ret)) { | |
755 | if (ret == -ENODATA) | |
756 | ret = 0; | |
757 | goto done; | |
758 | } | |
759 | ||
760 | array[n].bv_page = buf->page; | |
761 | array[n].bv_len = this_len; | |
762 | array[n].bv_offset = buf->offset; | |
763 | left -= this_len; | |
764 | } | |
765 | ||
766 | iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n, | |
767 | sd.total_len - left); | |
768 | ret = vfs_iter_write(out, &from, &sd.pos); | |
769 | if (ret <= 0) | |
770 | break; | |
771 | ||
772 | sd.num_spliced += ret; | |
773 | sd.total_len -= ret; | |
774 | *ppos = sd.pos; | |
775 | ||
776 | /* dismiss the fully eaten buffers, adjust the partial one */ | |
777 | while (ret) { | |
778 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
779 | if (ret >= buf->len) { | |
780 | ret -= buf->len; | |
781 | buf->len = 0; | |
782 | pipe_buf_release(pipe, buf); | |
783 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); | |
784 | pipe->nrbufs--; | |
785 | if (pipe->files) | |
786 | sd.need_wakeup = true; | |
787 | } else { | |
788 | buf->offset += ret; | |
789 | buf->len -= ret; | |
790 | ret = 0; | |
791 | } | |
792 | } | |
793 | } | |
794 | done: | |
795 | kfree(array); | |
796 | splice_from_pipe_end(pipe, &sd); | |
797 | ||
798 | pipe_unlock(pipe); | |
799 | ||
800 | if (sd.num_spliced) | |
801 | ret = sd.num_spliced; | |
802 | ||
803 | return ret; | |
804 | } | |
805 | ||
806 | EXPORT_SYMBOL(iter_file_splice_write); | |
807 | ||
808 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, | |
809 | struct splice_desc *sd) | |
810 | { | |
811 | int ret; | |
812 | void *data; | |
813 | loff_t tmp = sd->pos; | |
814 | ||
815 | data = kmap(buf->page); | |
816 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); | |
817 | kunmap(buf->page); | |
818 | ||
819 | return ret; | |
820 | } | |
821 | ||
822 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, | |
823 | struct file *out, loff_t *ppos, | |
824 | size_t len, unsigned int flags) | |
825 | { | |
826 | ssize_t ret; | |
827 | ||
828 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); | |
829 | if (ret > 0) | |
830 | *ppos += ret; | |
831 | ||
832 | return ret; | |
833 | } | |
834 | ||
835 | /** | |
836 | * generic_splice_sendpage - splice data from a pipe to a socket | |
837 | * @pipe: pipe to splice from | |
838 | * @out: socket to write to | |
839 | * @ppos: position in @out | |
840 | * @len: number of bytes to splice | |
841 | * @flags: splice modifier flags | |
842 | * | |
843 | * Description: | |
844 | * Will send @len bytes from the pipe to a network socket. No data copying | |
845 | * is involved. | |
846 | * | |
847 | */ | |
848 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, | |
849 | loff_t *ppos, size_t len, unsigned int flags) | |
850 | { | |
851 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); | |
852 | } | |
853 | ||
854 | EXPORT_SYMBOL(generic_splice_sendpage); | |
855 | ||
856 | /* | |
857 | * Attempt to initiate a splice from pipe to file. | |
858 | */ | |
859 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, | |
860 | loff_t *ppos, size_t len, unsigned int flags) | |
861 | { | |
862 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, | |
863 | loff_t *, size_t, unsigned int); | |
864 | ||
865 | if (out->f_op->splice_write) | |
866 | splice_write = out->f_op->splice_write; | |
867 | else | |
868 | splice_write = default_file_splice_write; | |
869 | ||
870 | return splice_write(pipe, out, ppos, len, flags); | |
871 | } | |
872 | ||
873 | /* | |
874 | * Attempt to initiate a splice from a file to a pipe. | |
875 | */ | |
876 | static long do_splice_to(struct file *in, loff_t *ppos, | |
877 | struct pipe_inode_info *pipe, size_t len, | |
878 | unsigned int flags) | |
879 | { | |
880 | ssize_t (*splice_read)(struct file *, loff_t *, | |
881 | struct pipe_inode_info *, size_t, unsigned int); | |
882 | int ret; | |
883 | ||
884 | if (unlikely(!(in->f_mode & FMODE_READ))) | |
885 | return -EBADF; | |
886 | ||
887 | ret = rw_verify_area(READ, in, ppos, len); | |
888 | if (unlikely(ret < 0)) | |
889 | return ret; | |
890 | ||
891 | if (unlikely(len > MAX_RW_COUNT)) | |
892 | len = MAX_RW_COUNT; | |
893 | ||
894 | if (in->f_op->splice_read) | |
895 | splice_read = in->f_op->splice_read; | |
896 | else | |
897 | splice_read = default_file_splice_read; | |
898 | ||
899 | return splice_read(in, ppos, pipe, len, flags); | |
900 | } | |
901 | ||
902 | /** | |
903 | * splice_direct_to_actor - splices data directly between two non-pipes | |
904 | * @in: file to splice from | |
905 | * @sd: actor information on where to splice to | |
906 | * @actor: handles the data splicing | |
907 | * | |
908 | * Description: | |
909 | * This is a special case helper to splice directly between two | |
910 | * points, without requiring an explicit pipe. Internally an allocated | |
911 | * pipe is cached in the process, and reused during the lifetime of | |
912 | * that process. | |
913 | * | |
914 | */ | |
915 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
916 | splice_direct_actor *actor) | |
917 | { | |
918 | struct pipe_inode_info *pipe; | |
919 | long ret, bytes; | |
920 | umode_t i_mode; | |
921 | size_t len; | |
922 | int i, flags, more; | |
923 | ||
924 | /* | |
925 | * We require the input being a regular file, as we don't want to | |
926 | * randomly drop data for eg socket -> socket splicing. Use the | |
927 | * piped splicing for that! | |
928 | */ | |
929 | i_mode = file_inode(in)->i_mode; | |
930 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) | |
931 | return -EINVAL; | |
932 | ||
933 | /* | |
934 | * neither in nor out is a pipe, setup an internal pipe attached to | |
935 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
936 | */ | |
937 | pipe = current->splice_pipe; | |
938 | if (unlikely(!pipe)) { | |
939 | pipe = alloc_pipe_info(); | |
940 | if (!pipe) | |
941 | return -ENOMEM; | |
942 | ||
943 | /* | |
944 | * We don't have an immediate reader, but we'll read the stuff | |
945 | * out of the pipe right after the splice_to_pipe(). So set | |
946 | * PIPE_READERS appropriately. | |
947 | */ | |
948 | pipe->readers = 1; | |
949 | ||
950 | current->splice_pipe = pipe; | |
951 | } | |
952 | ||
953 | /* | |
954 | * Do the splice. | |
955 | */ | |
956 | ret = 0; | |
957 | bytes = 0; | |
958 | len = sd->total_len; | |
959 | flags = sd->flags; | |
960 | ||
961 | /* | |
962 | * Don't block on output, we have to drain the direct pipe. | |
963 | */ | |
964 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
965 | more = sd->flags & SPLICE_F_MORE; | |
966 | ||
967 | while (len) { | |
968 | size_t read_len; | |
969 | loff_t pos = sd->pos, prev_pos = pos; | |
970 | ||
971 | ret = do_splice_to(in, &pos, pipe, len, flags); | |
972 | if (unlikely(ret <= 0)) | |
973 | goto out_release; | |
974 | ||
975 | read_len = ret; | |
976 | sd->total_len = read_len; | |
977 | ||
978 | /* | |
979 | * If more data is pending, set SPLICE_F_MORE | |
980 | * If this is the last data and SPLICE_F_MORE was not set | |
981 | * initially, clears it. | |
982 | */ | |
983 | if (read_len < len) | |
984 | sd->flags |= SPLICE_F_MORE; | |
985 | else if (!more) | |
986 | sd->flags &= ~SPLICE_F_MORE; | |
987 | /* | |
988 | * NOTE: nonblocking mode only applies to the input. We | |
989 | * must not do the output in nonblocking mode as then we | |
990 | * could get stuck data in the internal pipe: | |
991 | */ | |
992 | ret = actor(pipe, sd); | |
993 | if (unlikely(ret <= 0)) { | |
994 | sd->pos = prev_pos; | |
995 | goto out_release; | |
996 | } | |
997 | ||
998 | bytes += ret; | |
999 | len -= ret; | |
1000 | sd->pos = pos; | |
1001 | ||
1002 | if (ret < read_len) { | |
1003 | sd->pos = prev_pos + ret; | |
1004 | goto out_release; | |
1005 | } | |
1006 | } | |
1007 | ||
1008 | done: | |
1009 | pipe->nrbufs = pipe->curbuf = 0; | |
1010 | file_accessed(in); | |
1011 | return bytes; | |
1012 | ||
1013 | out_release: | |
1014 | /* | |
1015 | * If we did an incomplete transfer we must release | |
1016 | * the pipe buffers in question: | |
1017 | */ | |
1018 | for (i = 0; i < pipe->buffers; i++) { | |
1019 | struct pipe_buffer *buf = pipe->bufs + i; | |
1020 | ||
1021 | if (buf->ops) | |
1022 | pipe_buf_release(pipe, buf); | |
1023 | } | |
1024 | ||
1025 | if (!bytes) | |
1026 | bytes = ret; | |
1027 | ||
1028 | goto done; | |
1029 | } | |
1030 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1031 | ||
1032 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1033 | struct splice_desc *sd) | |
1034 | { | |
1035 | struct file *file = sd->u.file; | |
1036 | ||
1037 | return do_splice_from(pipe, file, sd->opos, sd->total_len, | |
1038 | sd->flags); | |
1039 | } | |
1040 | ||
1041 | /** | |
1042 | * do_splice_direct - splices data directly between two files | |
1043 | * @in: file to splice from | |
1044 | * @ppos: input file offset | |
1045 | * @out: file to splice to | |
1046 | * @opos: output file offset | |
1047 | * @len: number of bytes to splice | |
1048 | * @flags: splice modifier flags | |
1049 | * | |
1050 | * Description: | |
1051 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1052 | * doing it in the application would incur an extra system call | |
1053 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1054 | * can splice directly through a process-private pipe. | |
1055 | * | |
1056 | */ | |
1057 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, | |
1058 | loff_t *opos, size_t len, unsigned int flags) | |
1059 | { | |
1060 | struct splice_desc sd = { | |
1061 | .len = len, | |
1062 | .total_len = len, | |
1063 | .flags = flags, | |
1064 | .pos = *ppos, | |
1065 | .u.file = out, | |
1066 | .opos = opos, | |
1067 | }; | |
1068 | long ret; | |
1069 | ||
1070 | if (unlikely(!(out->f_mode & FMODE_WRITE))) | |
1071 | return -EBADF; | |
1072 | ||
1073 | if (unlikely(out->f_flags & O_APPEND)) | |
1074 | return -EINVAL; | |
1075 | ||
1076 | ret = rw_verify_area(WRITE, out, opos, len); | |
1077 | if (unlikely(ret < 0)) | |
1078 | return ret; | |
1079 | ||
1080 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); | |
1081 | if (ret > 0) | |
1082 | *ppos = sd.pos; | |
1083 | ||
1084 | return ret; | |
1085 | } | |
1086 | EXPORT_SYMBOL(do_splice_direct); | |
1087 | ||
1088 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) | |
1089 | { | |
1090 | for (;;) { | |
1091 | if (unlikely(!pipe->readers)) { | |
1092 | send_sig(SIGPIPE, current, 0); | |
1093 | return -EPIPE; | |
1094 | } | |
1095 | if (pipe->nrbufs != pipe->buffers) | |
1096 | return 0; | |
1097 | if (flags & SPLICE_F_NONBLOCK) | |
1098 | return -EAGAIN; | |
1099 | if (signal_pending(current)) | |
1100 | return -ERESTARTSYS; | |
1101 | pipe->waiting_writers++; | |
1102 | pipe_wait(pipe); | |
1103 | pipe->waiting_writers--; | |
1104 | } | |
1105 | } | |
1106 | ||
1107 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1108 | struct pipe_inode_info *opipe, | |
1109 | size_t len, unsigned int flags); | |
1110 | ||
1111 | /* | |
1112 | * Determine where to splice to/from. | |
1113 | */ | |
1114 | static long do_splice(struct file *in, loff_t __user *off_in, | |
1115 | struct file *out, loff_t __user *off_out, | |
1116 | size_t len, unsigned int flags) | |
1117 | { | |
1118 | struct pipe_inode_info *ipipe; | |
1119 | struct pipe_inode_info *opipe; | |
1120 | loff_t offset; | |
1121 | long ret; | |
1122 | ||
1123 | ipipe = get_pipe_info(in); | |
1124 | opipe = get_pipe_info(out); | |
1125 | ||
1126 | if (ipipe && opipe) { | |
1127 | if (off_in || off_out) | |
1128 | return -ESPIPE; | |
1129 | ||
1130 | if (!(in->f_mode & FMODE_READ)) | |
1131 | return -EBADF; | |
1132 | ||
1133 | if (!(out->f_mode & FMODE_WRITE)) | |
1134 | return -EBADF; | |
1135 | ||
1136 | /* Splicing to self would be fun, but... */ | |
1137 | if (ipipe == opipe) | |
1138 | return -EINVAL; | |
1139 | ||
1140 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); | |
1141 | } | |
1142 | ||
1143 | if (ipipe) { | |
1144 | if (off_in) | |
1145 | return -ESPIPE; | |
1146 | if (off_out) { | |
1147 | if (!(out->f_mode & FMODE_PWRITE)) | |
1148 | return -EINVAL; | |
1149 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) | |
1150 | return -EFAULT; | |
1151 | } else { | |
1152 | offset = out->f_pos; | |
1153 | } | |
1154 | ||
1155 | if (unlikely(!(out->f_mode & FMODE_WRITE))) | |
1156 | return -EBADF; | |
1157 | ||
1158 | if (unlikely(out->f_flags & O_APPEND)) | |
1159 | return -EINVAL; | |
1160 | ||
1161 | ret = rw_verify_area(WRITE, out, &offset, len); | |
1162 | if (unlikely(ret < 0)) | |
1163 | return ret; | |
1164 | ||
1165 | file_start_write(out); | |
1166 | ret = do_splice_from(ipipe, out, &offset, len, flags); | |
1167 | file_end_write(out); | |
1168 | ||
1169 | if (!off_out) | |
1170 | out->f_pos = offset; | |
1171 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) | |
1172 | ret = -EFAULT; | |
1173 | ||
1174 | return ret; | |
1175 | } | |
1176 | ||
1177 | if (opipe) { | |
1178 | if (off_out) | |
1179 | return -ESPIPE; | |
1180 | if (off_in) { | |
1181 | if (!(in->f_mode & FMODE_PREAD)) | |
1182 | return -EINVAL; | |
1183 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) | |
1184 | return -EFAULT; | |
1185 | } else { | |
1186 | offset = in->f_pos; | |
1187 | } | |
1188 | ||
1189 | pipe_lock(opipe); | |
1190 | ret = wait_for_space(opipe, flags); | |
1191 | if (!ret) | |
1192 | ret = do_splice_to(in, &offset, opipe, len, flags); | |
1193 | pipe_unlock(opipe); | |
1194 | if (ret > 0) | |
1195 | wakeup_pipe_readers(opipe); | |
1196 | if (!off_in) | |
1197 | in->f_pos = offset; | |
1198 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) | |
1199 | ret = -EFAULT; | |
1200 | ||
1201 | return ret; | |
1202 | } | |
1203 | ||
1204 | return -EINVAL; | |
1205 | } | |
1206 | ||
1207 | static int iter_to_pipe(struct iov_iter *from, | |
1208 | struct pipe_inode_info *pipe, | |
1209 | unsigned flags) | |
1210 | { | |
1211 | struct pipe_buffer buf = { | |
1212 | .ops = &user_page_pipe_buf_ops, | |
1213 | .flags = flags | |
1214 | }; | |
1215 | size_t total = 0; | |
1216 | int ret = 0; | |
1217 | bool failed = false; | |
1218 | ||
1219 | while (iov_iter_count(from) && !failed) { | |
1220 | struct page *pages[16]; | |
1221 | ssize_t copied; | |
1222 | size_t start; | |
1223 | int n; | |
1224 | ||
1225 | copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start); | |
1226 | if (copied <= 0) { | |
1227 | ret = copied; | |
1228 | break; | |
1229 | } | |
1230 | ||
1231 | for (n = 0; copied; n++, start = 0) { | |
1232 | int size = min_t(int, copied, PAGE_SIZE - start); | |
1233 | if (!failed) { | |
1234 | buf.page = pages[n]; | |
1235 | buf.offset = start; | |
1236 | buf.len = size; | |
1237 | ret = add_to_pipe(pipe, &buf); | |
1238 | if (unlikely(ret < 0)) { | |
1239 | failed = true; | |
1240 | } else { | |
1241 | iov_iter_advance(from, ret); | |
1242 | total += ret; | |
1243 | } | |
1244 | } else { | |
1245 | put_page(pages[n]); | |
1246 | } | |
1247 | copied -= size; | |
1248 | } | |
1249 | } | |
1250 | return total ? total : ret; | |
1251 | } | |
1252 | ||
1253 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, | |
1254 | struct splice_desc *sd) | |
1255 | { | |
1256 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); | |
1257 | return n == sd->len ? n : -EFAULT; | |
1258 | } | |
1259 | ||
1260 | /* | |
1261 | * For lack of a better implementation, implement vmsplice() to userspace | |
1262 | * as a simple copy of the pipes pages to the user iov. | |
1263 | */ | |
1264 | static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov, | |
1265 | unsigned long nr_segs, unsigned int flags) | |
1266 | { | |
1267 | struct pipe_inode_info *pipe; | |
1268 | struct splice_desc sd; | |
1269 | long ret; | |
1270 | struct iovec iovstack[UIO_FASTIOV]; | |
1271 | struct iovec *iov = iovstack; | |
1272 | struct iov_iter iter; | |
1273 | ||
1274 | pipe = get_pipe_info(file); | |
1275 | if (!pipe) | |
1276 | return -EBADF; | |
1277 | ||
1278 | ret = import_iovec(READ, uiov, nr_segs, | |
1279 | ARRAY_SIZE(iovstack), &iov, &iter); | |
1280 | if (ret < 0) | |
1281 | return ret; | |
1282 | ||
1283 | sd.total_len = iov_iter_count(&iter); | |
1284 | sd.len = 0; | |
1285 | sd.flags = flags; | |
1286 | sd.u.data = &iter; | |
1287 | sd.pos = 0; | |
1288 | ||
1289 | if (sd.total_len) { | |
1290 | pipe_lock(pipe); | |
1291 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1292 | pipe_unlock(pipe); | |
1293 | } | |
1294 | ||
1295 | kfree(iov); | |
1296 | return ret; | |
1297 | } | |
1298 | ||
1299 | /* | |
1300 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1301 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1302 | * to file). In both cases the output is a pipe, naturally. | |
1303 | */ | |
1304 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov, | |
1305 | unsigned long nr_segs, unsigned int flags) | |
1306 | { | |
1307 | struct pipe_inode_info *pipe; | |
1308 | struct iovec iovstack[UIO_FASTIOV]; | |
1309 | struct iovec *iov = iovstack; | |
1310 | struct iov_iter from; | |
1311 | long ret; | |
1312 | unsigned buf_flag = 0; | |
1313 | ||
1314 | if (flags & SPLICE_F_GIFT) | |
1315 | buf_flag = PIPE_BUF_FLAG_GIFT; | |
1316 | ||
1317 | pipe = get_pipe_info(file); | |
1318 | if (!pipe) | |
1319 | return -EBADF; | |
1320 | ||
1321 | ret = import_iovec(WRITE, uiov, nr_segs, | |
1322 | ARRAY_SIZE(iovstack), &iov, &from); | |
1323 | if (ret < 0) | |
1324 | return ret; | |
1325 | ||
1326 | pipe_lock(pipe); | |
1327 | ret = wait_for_space(pipe, flags); | |
1328 | if (!ret) | |
1329 | ret = iter_to_pipe(&from, pipe, buf_flag); | |
1330 | pipe_unlock(pipe); | |
1331 | if (ret > 0) | |
1332 | wakeup_pipe_readers(pipe); | |
1333 | kfree(iov); | |
1334 | return ret; | |
1335 | } | |
1336 | ||
1337 | /* | |
1338 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1339 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1340 | * operation that can be supported without any funky alignment restrictions | |
1341 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1342 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1343 | * solutions for that: | |
1344 | * | |
1345 | * - memcpy() the data internally, at which point we might as well just | |
1346 | * do a regular read() on the buffer anyway. | |
1347 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1348 | * has restriction limitations on both ends of the pipe). | |
1349 | * | |
1350 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1351 | * | |
1352 | */ | |
1353 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, | |
1354 | unsigned long, nr_segs, unsigned int, flags) | |
1355 | { | |
1356 | struct fd f; | |
1357 | long error; | |
1358 | ||
1359 | if (unlikely(nr_segs > UIO_MAXIOV)) | |
1360 | return -EINVAL; | |
1361 | else if (unlikely(!nr_segs)) | |
1362 | return 0; | |
1363 | ||
1364 | error = -EBADF; | |
1365 | f = fdget(fd); | |
1366 | if (f.file) { | |
1367 | if (f.file->f_mode & FMODE_WRITE) | |
1368 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); | |
1369 | else if (f.file->f_mode & FMODE_READ) | |
1370 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); | |
1371 | ||
1372 | fdput(f); | |
1373 | } | |
1374 | ||
1375 | return error; | |
1376 | } | |
1377 | ||
1378 | #ifdef CONFIG_COMPAT | |
1379 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, | |
1380 | unsigned int, nr_segs, unsigned int, flags) | |
1381 | { | |
1382 | unsigned i; | |
1383 | struct iovec __user *iov; | |
1384 | if (nr_segs > UIO_MAXIOV) | |
1385 | return -EINVAL; | |
1386 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); | |
1387 | for (i = 0; i < nr_segs; i++) { | |
1388 | struct compat_iovec v; | |
1389 | if (get_user(v.iov_base, &iov32[i].iov_base) || | |
1390 | get_user(v.iov_len, &iov32[i].iov_len) || | |
1391 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || | |
1392 | put_user(v.iov_len, &iov[i].iov_len)) | |
1393 | return -EFAULT; | |
1394 | } | |
1395 | return sys_vmsplice(fd, iov, nr_segs, flags); | |
1396 | } | |
1397 | #endif | |
1398 | ||
1399 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, | |
1400 | int, fd_out, loff_t __user *, off_out, | |
1401 | size_t, len, unsigned int, flags) | |
1402 | { | |
1403 | struct fd in, out; | |
1404 | long error; | |
1405 | ||
1406 | if (unlikely(!len)) | |
1407 | return 0; | |
1408 | ||
1409 | error = -EBADF; | |
1410 | in = fdget(fd_in); | |
1411 | if (in.file) { | |
1412 | if (in.file->f_mode & FMODE_READ) { | |
1413 | out = fdget(fd_out); | |
1414 | if (out.file) { | |
1415 | if (out.file->f_mode & FMODE_WRITE) | |
1416 | error = do_splice(in.file, off_in, | |
1417 | out.file, off_out, | |
1418 | len, flags); | |
1419 | fdput(out); | |
1420 | } | |
1421 | } | |
1422 | fdput(in); | |
1423 | } | |
1424 | return error; | |
1425 | } | |
1426 | ||
1427 | /* | |
1428 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1429 | * return an appropriate error. | |
1430 | */ | |
1431 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1432 | { | |
1433 | int ret; | |
1434 | ||
1435 | /* | |
1436 | * Check ->nrbufs without the inode lock first. This function | |
1437 | * is speculative anyways, so missing one is ok. | |
1438 | */ | |
1439 | if (pipe->nrbufs) | |
1440 | return 0; | |
1441 | ||
1442 | ret = 0; | |
1443 | pipe_lock(pipe); | |
1444 | ||
1445 | while (!pipe->nrbufs) { | |
1446 | if (signal_pending(current)) { | |
1447 | ret = -ERESTARTSYS; | |
1448 | break; | |
1449 | } | |
1450 | if (!pipe->writers) | |
1451 | break; | |
1452 | if (!pipe->waiting_writers) { | |
1453 | if (flags & SPLICE_F_NONBLOCK) { | |
1454 | ret = -EAGAIN; | |
1455 | break; | |
1456 | } | |
1457 | } | |
1458 | pipe_wait(pipe); | |
1459 | } | |
1460 | ||
1461 | pipe_unlock(pipe); | |
1462 | return ret; | |
1463 | } | |
1464 | ||
1465 | /* | |
1466 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1467 | * return an appropriate error. | |
1468 | */ | |
1469 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) | |
1470 | { | |
1471 | int ret; | |
1472 | ||
1473 | /* | |
1474 | * Check ->nrbufs without the inode lock first. This function | |
1475 | * is speculative anyways, so missing one is ok. | |
1476 | */ | |
1477 | if (pipe->nrbufs < pipe->buffers) | |
1478 | return 0; | |
1479 | ||
1480 | ret = 0; | |
1481 | pipe_lock(pipe); | |
1482 | ||
1483 | while (pipe->nrbufs >= pipe->buffers) { | |
1484 | if (!pipe->readers) { | |
1485 | send_sig(SIGPIPE, current, 0); | |
1486 | ret = -EPIPE; | |
1487 | break; | |
1488 | } | |
1489 | if (flags & SPLICE_F_NONBLOCK) { | |
1490 | ret = -EAGAIN; | |
1491 | break; | |
1492 | } | |
1493 | if (signal_pending(current)) { | |
1494 | ret = -ERESTARTSYS; | |
1495 | break; | |
1496 | } | |
1497 | pipe->waiting_writers++; | |
1498 | pipe_wait(pipe); | |
1499 | pipe->waiting_writers--; | |
1500 | } | |
1501 | ||
1502 | pipe_unlock(pipe); | |
1503 | return ret; | |
1504 | } | |
1505 | ||
1506 | /* | |
1507 | * Splice contents of ipipe to opipe. | |
1508 | */ | |
1509 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1510 | struct pipe_inode_info *opipe, | |
1511 | size_t len, unsigned int flags) | |
1512 | { | |
1513 | struct pipe_buffer *ibuf, *obuf; | |
1514 | int ret = 0, nbuf; | |
1515 | bool input_wakeup = false; | |
1516 | ||
1517 | ||
1518 | retry: | |
1519 | ret = ipipe_prep(ipipe, flags); | |
1520 | if (ret) | |
1521 | return ret; | |
1522 | ||
1523 | ret = opipe_prep(opipe, flags); | |
1524 | if (ret) | |
1525 | return ret; | |
1526 | ||
1527 | /* | |
1528 | * Potential ABBA deadlock, work around it by ordering lock | |
1529 | * grabbing by pipe info address. Otherwise two different processes | |
1530 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1531 | */ | |
1532 | pipe_double_lock(ipipe, opipe); | |
1533 | ||
1534 | do { | |
1535 | if (!opipe->readers) { | |
1536 | send_sig(SIGPIPE, current, 0); | |
1537 | if (!ret) | |
1538 | ret = -EPIPE; | |
1539 | break; | |
1540 | } | |
1541 | ||
1542 | if (!ipipe->nrbufs && !ipipe->writers) | |
1543 | break; | |
1544 | ||
1545 | /* | |
1546 | * Cannot make any progress, because either the input | |
1547 | * pipe is empty or the output pipe is full. | |
1548 | */ | |
1549 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { | |
1550 | /* Already processed some buffers, break */ | |
1551 | if (ret) | |
1552 | break; | |
1553 | ||
1554 | if (flags & SPLICE_F_NONBLOCK) { | |
1555 | ret = -EAGAIN; | |
1556 | break; | |
1557 | } | |
1558 | ||
1559 | /* | |
1560 | * We raced with another reader/writer and haven't | |
1561 | * managed to process any buffers. A zero return | |
1562 | * value means EOF, so retry instead. | |
1563 | */ | |
1564 | pipe_unlock(ipipe); | |
1565 | pipe_unlock(opipe); | |
1566 | goto retry; | |
1567 | } | |
1568 | ||
1569 | ibuf = ipipe->bufs + ipipe->curbuf; | |
1570 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
1571 | obuf = opipe->bufs + nbuf; | |
1572 | ||
1573 | if (len >= ibuf->len) { | |
1574 | /* | |
1575 | * Simply move the whole buffer from ipipe to opipe | |
1576 | */ | |
1577 | *obuf = *ibuf; | |
1578 | ibuf->ops = NULL; | |
1579 | opipe->nrbufs++; | |
1580 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); | |
1581 | ipipe->nrbufs--; | |
1582 | input_wakeup = true; | |
1583 | } else { | |
1584 | /* | |
1585 | * Get a reference to this pipe buffer, | |
1586 | * so we can copy the contents over. | |
1587 | */ | |
1588 | pipe_buf_get(ipipe, ibuf); | |
1589 | *obuf = *ibuf; | |
1590 | ||
1591 | /* | |
1592 | * Don't inherit the gift flag, we need to | |
1593 | * prevent multiple steals of this page. | |
1594 | */ | |
1595 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1596 | ||
1597 | obuf->len = len; | |
1598 | opipe->nrbufs++; | |
1599 | ibuf->offset += obuf->len; | |
1600 | ibuf->len -= obuf->len; | |
1601 | } | |
1602 | ret += obuf->len; | |
1603 | len -= obuf->len; | |
1604 | } while (len); | |
1605 | ||
1606 | pipe_unlock(ipipe); | |
1607 | pipe_unlock(opipe); | |
1608 | ||
1609 | /* | |
1610 | * If we put data in the output pipe, wakeup any potential readers. | |
1611 | */ | |
1612 | if (ret > 0) | |
1613 | wakeup_pipe_readers(opipe); | |
1614 | ||
1615 | if (input_wakeup) | |
1616 | wakeup_pipe_writers(ipipe); | |
1617 | ||
1618 | return ret; | |
1619 | } | |
1620 | ||
1621 | /* | |
1622 | * Link contents of ipipe to opipe. | |
1623 | */ | |
1624 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1625 | struct pipe_inode_info *opipe, | |
1626 | size_t len, unsigned int flags) | |
1627 | { | |
1628 | struct pipe_buffer *ibuf, *obuf; | |
1629 | int ret = 0, i = 0, nbuf; | |
1630 | ||
1631 | /* | |
1632 | * Potential ABBA deadlock, work around it by ordering lock | |
1633 | * grabbing by pipe info address. Otherwise two different processes | |
1634 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1635 | */ | |
1636 | pipe_double_lock(ipipe, opipe); | |
1637 | ||
1638 | do { | |
1639 | if (!opipe->readers) { | |
1640 | send_sig(SIGPIPE, current, 0); | |
1641 | if (!ret) | |
1642 | ret = -EPIPE; | |
1643 | break; | |
1644 | } | |
1645 | ||
1646 | /* | |
1647 | * If we have iterated all input buffers or ran out of | |
1648 | * output room, break. | |
1649 | */ | |
1650 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) | |
1651 | break; | |
1652 | ||
1653 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); | |
1654 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
1655 | ||
1656 | /* | |
1657 | * Get a reference to this pipe buffer, | |
1658 | * so we can copy the contents over. | |
1659 | */ | |
1660 | pipe_buf_get(ipipe, ibuf); | |
1661 | ||
1662 | obuf = opipe->bufs + nbuf; | |
1663 | *obuf = *ibuf; | |
1664 | ||
1665 | /* | |
1666 | * Don't inherit the gift flag, we need to | |
1667 | * prevent multiple steals of this page. | |
1668 | */ | |
1669 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1670 | ||
1671 | if (obuf->len > len) | |
1672 | obuf->len = len; | |
1673 | ||
1674 | opipe->nrbufs++; | |
1675 | ret += obuf->len; | |
1676 | len -= obuf->len; | |
1677 | i++; | |
1678 | } while (len); | |
1679 | ||
1680 | /* | |
1681 | * return EAGAIN if we have the potential of some data in the | |
1682 | * future, otherwise just return 0 | |
1683 | */ | |
1684 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
1685 | ret = -EAGAIN; | |
1686 | ||
1687 | pipe_unlock(ipipe); | |
1688 | pipe_unlock(opipe); | |
1689 | ||
1690 | /* | |
1691 | * If we put data in the output pipe, wakeup any potential readers. | |
1692 | */ | |
1693 | if (ret > 0) | |
1694 | wakeup_pipe_readers(opipe); | |
1695 | ||
1696 | return ret; | |
1697 | } | |
1698 | ||
1699 | /* | |
1700 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1701 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1702 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1703 | * applicable one is SPLICE_F_NONBLOCK. | |
1704 | */ | |
1705 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1706 | unsigned int flags) | |
1707 | { | |
1708 | struct pipe_inode_info *ipipe = get_pipe_info(in); | |
1709 | struct pipe_inode_info *opipe = get_pipe_info(out); | |
1710 | int ret = -EINVAL; | |
1711 | ||
1712 | /* | |
1713 | * Duplicate the contents of ipipe to opipe without actually | |
1714 | * copying the data. | |
1715 | */ | |
1716 | if (ipipe && opipe && ipipe != opipe) { | |
1717 | /* | |
1718 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1719 | * ordering doesn't really matter. | |
1720 | */ | |
1721 | ret = ipipe_prep(ipipe, flags); | |
1722 | if (!ret) { | |
1723 | ret = opipe_prep(opipe, flags); | |
1724 | if (!ret) | |
1725 | ret = link_pipe(ipipe, opipe, len, flags); | |
1726 | } | |
1727 | } | |
1728 | ||
1729 | return ret; | |
1730 | } | |
1731 | ||
1732 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) | |
1733 | { | |
1734 | struct fd in; | |
1735 | int error; | |
1736 | ||
1737 | if (unlikely(!len)) | |
1738 | return 0; | |
1739 | ||
1740 | error = -EBADF; | |
1741 | in = fdget(fdin); | |
1742 | if (in.file) { | |
1743 | if (in.file->f_mode & FMODE_READ) { | |
1744 | struct fd out = fdget(fdout); | |
1745 | if (out.file) { | |
1746 | if (out.file->f_mode & FMODE_WRITE) | |
1747 | error = do_tee(in.file, out.file, | |
1748 | len, flags); | |
1749 | fdput(out); | |
1750 | } | |
1751 | } | |
1752 | fdput(in); | |
1753 | } | |
1754 | ||
1755 | return error; | |
1756 | } |