1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * "splice": joining two ropes together by interweaving their strands. |
4 | * |
5 | * This is the "extended pipe" functionality, where a pipe is used as |
6 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel |
7 | * buffer that you can use to transfer data from one end to the other. |
8 | * |
9 | * The traditional unix read/write is extended with a "splice()" operation |
10 | * that transfers data buffers to or from a pipe buffer. |
11 | * |
12 | * Named by Larry McVoy, original implementation from Linus, extended by |
13 | * Jens to support splicing to files, network, direct splicing, etc and |
14 | * fixing lots of bugs. |
15 | * |
16 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
17 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
18 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> |
19 | * |
20 | */ |
21 | #include <linux/bvec.h> |
22 | #include <linux/fs.h> |
23 | #include <linux/file.h> |
24 | #include <linux/pagemap.h> |
25 | #include <linux/splice.h> |
26 | #include <linux/memcontrol.h> |
27 | #include <linux/mm_inline.h> |
28 | #include <linux/swap.h> |
29 | #include <linux/writeback.h> |
30 | #include <linux/export.h> |
31 | #include <linux/syscalls.h> |
32 | #include <linux/uio.h> |
33 | #include <linux/fsnotify.h> |
34 | #include <linux/security.h> |
35 | #include <linux/gfp.h> |
36 | #include <linux/net.h> |
37 | #include <linux/socket.h> |
38 | #include <linux/sched/signal.h> |
39 | |
40 | #include "internal.h" |
41 | |
42 | /* |
43 | * Splice doesn't support FMODE_NOWAIT. Since pipes may set this flag to |
44 | * indicate they support non-blocking reads or writes, we must clear it |
45 | * here if set to avoid blocking other users of this pipe if splice is |
46 | * being done on it. |
47 | */ |
48 | static noinline void noinline pipe_clear_nowait(struct file *file) |
49 | { |
50 | fmode_t fmode = READ_ONCE(file->f_mode); |
51 | |
52 | do { |
53 | if (!(fmode & FMODE_NOWAIT)) |
54 | break; |
55 | } while (!try_cmpxchg(&file->f_mode, &fmode, fmode & ~FMODE_NOWAIT)); |
56 | } |
57 | |
58 | /* |
59 | * Attempt to steal a page from a pipe buffer. This should perhaps go into |
60 | * a vm helper function, it's already simplified quite a bit by the |
61 | * addition of remove_mapping(). If success is returned, the caller may |
62 | * attempt to reuse this page for another destination. |
63 | */ |
64 | static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
65 | struct pipe_buffer *buf) |
66 | { |
67 | struct folio *folio = page_folio(buf->page); |
68 | struct address_space *mapping; |
69 | |
70 | folio_lock(folio); |
71 | |
72 | mapping = folio_mapping(folio); |
73 | if (mapping) { |
74 | WARN_ON(!folio_test_uptodate(folio)); |
75 | |
76 | /* |
77 | * At least for ext2 with nobh option, we need to wait on |
78 | * writeback completing on this folio, since we'll remove it |
79 | * from the pagecache. Otherwise truncate wont wait on the |
80 | * folio, allowing the disk blocks to be reused by someone else |
81 | * before we actually wrote our data to them. fs corruption |
82 | * ensues. |
83 | */ |
84 | folio_wait_writeback(folio); |
85 | |
86 | if (!filemap_release_folio(folio, GFP_KERNEL)) |
87 | goto out_unlock; |
88 | |
89 | /* |
90 | * If we succeeded in removing the mapping, set LRU flag |
91 | * and return good. |
92 | */ |
93 | if (remove_mapping(mapping, folio)) { |
94 | buf->flags |= PIPE_BUF_FLAG_LRU; |
95 | return true; |
96 | } |
97 | } |
98 | |
99 | /* |
100 | * Raced with truncate or failed to remove folio from current |
101 | * address space, unlock and return failure. |
102 | */ |
103 | out_unlock: |
104 | folio_unlock(folio); |
105 | return false; |
106 | } |
107 | |
108 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
109 | struct pipe_buffer *buf) |
110 | { |
111 | put_page(page: buf->page); |
112 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
113 | } |
114 | |
115 | /* |
116 | * Check whether the contents of buf is OK to access. Since the content |
117 | * is a page cache page, IO may be in flight. |
118 | */ |
119 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
120 | struct pipe_buffer *buf) |
121 | { |
122 | struct folio *folio = page_folio(buf->page); |
123 | int err; |
124 | |
125 | if (!folio_test_uptodate(folio)) { |
126 | folio_lock(folio); |
127 | |
128 | /* |
129 | * Folio got truncated/unhashed. This will cause a 0-byte |
130 | * splice, if this is the first page. |
131 | */ |
132 | if (!folio->mapping) { |
133 | err = -ENODATA; |
134 | goto error; |
135 | } |
136 | |
137 | /* |
138 | * Uh oh, read-error from disk. |
139 | */ |
140 | if (!folio_test_uptodate(folio)) { |
141 | err = -EIO; |
142 | goto error; |
143 | } |
144 | |
145 | /* Folio is ok after all, we are done */ |
146 | folio_unlock(folio); |
147 | } |
148 | |
149 | return 0; |
150 | error: |
151 | folio_unlock(folio); |
152 | return err; |
153 | } |
154 | |
155 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
156 | .confirm = page_cache_pipe_buf_confirm, |
157 | .release = page_cache_pipe_buf_release, |
158 | .try_steal = page_cache_pipe_buf_try_steal, |
159 | .get = generic_pipe_buf_get, |
160 | }; |
161 | |
162 | static bool user_page_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
163 | struct pipe_buffer *buf) |
164 | { |
165 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
166 | return false; |
167 | |
168 | buf->flags |= PIPE_BUF_FLAG_LRU; |
169 | return generic_pipe_buf_try_steal(pipe, buf); |
170 | } |
171 | |
172 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
173 | .release = page_cache_pipe_buf_release, |
174 | .try_steal = user_page_pipe_buf_try_steal, |
175 | .get = generic_pipe_buf_get, |
176 | }; |
177 | |
178 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
179 | { |
180 | smp_mb(); |
181 | if (waitqueue_active(wq_head: &pipe->rd_wait)) |
182 | wake_up_interruptible(&pipe->rd_wait); |
183 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
184 | } |
185 | |
186 | /** |
187 | * splice_to_pipe - fill passed data into a pipe |
188 | * @pipe: pipe to fill |
189 | * @spd: data to fill |
190 | * |
191 | * Description: |
192 | * @spd contains a map of pages and len/offset tuples, along with |
193 | * the struct pipe_buf_operations associated with these pages. This |
194 | * function will link that data to the pipe. |
195 | * |
196 | */ |
197 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
198 | struct splice_pipe_desc *spd) |
199 | { |
200 | unsigned int spd_pages = spd->nr_pages; |
201 | unsigned int tail = pipe->tail; |
202 | unsigned int head = pipe->head; |
203 | unsigned int mask = pipe->ring_size - 1; |
204 | int ret = 0, page_nr = 0; |
205 | |
206 | if (!spd_pages) |
207 | return 0; |
208 | |
209 | if (unlikely(!pipe->readers)) { |
210 | send_sig(SIGPIPE, current, 0); |
211 | ret = -EPIPE; |
212 | goto out; |
213 | } |
214 | |
215 | while (!pipe_full(head, tail, limit: pipe->max_usage)) { |
216 | struct pipe_buffer *buf = &pipe->bufs[head & mask]; |
217 | |
218 | buf->page = spd->pages[page_nr]; |
219 | buf->offset = spd->partial[page_nr].offset; |
220 | buf->len = spd->partial[page_nr].len; |
221 | buf->private = spd->partial[page_nr].private; |
222 | buf->ops = spd->ops; |
223 | buf->flags = 0; |
224 | |
225 | head++; |
226 | pipe->head = head; |
227 | page_nr++; |
228 | ret += buf->len; |
229 | |
230 | if (!--spd->nr_pages) |
231 | break; |
232 | } |
233 | |
234 | if (!ret) |
235 | ret = -EAGAIN; |
236 | |
237 | out: |
238 | while (page_nr < spd_pages) |
239 | spd->spd_release(spd, page_nr++); |
240 | |
241 | return ret; |
242 | } |
243 | EXPORT_SYMBOL_GPL(splice_to_pipe); |
244 | |
245 | ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
246 | { |
247 | unsigned int head = pipe->head; |
248 | unsigned int tail = pipe->tail; |
249 | unsigned int mask = pipe->ring_size - 1; |
250 | int ret; |
251 | |
252 | if (unlikely(!pipe->readers)) { |
253 | send_sig(SIGPIPE, current, 0); |
254 | ret = -EPIPE; |
255 | } else if (pipe_full(head, tail, limit: pipe->max_usage)) { |
256 | ret = -EAGAIN; |
257 | } else { |
258 | pipe->bufs[head & mask] = *buf; |
259 | pipe->head = head + 1; |
260 | return buf->len; |
261 | } |
262 | pipe_buf_release(pipe, buf); |
263 | return ret; |
264 | } |
265 | EXPORT_SYMBOL(add_to_pipe); |
266 | |
267 | /* |
268 | * Check if we need to grow the arrays holding pages and partial page |
269 | * descriptions. |
270 | */ |
271 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
272 | { |
273 | unsigned int max_usage = READ_ONCE(pipe->max_usage); |
274 | |
275 | spd->nr_pages_max = max_usage; |
276 | if (max_usage <= PIPE_DEF_BUFFERS) |
277 | return 0; |
278 | |
279 | spd->pages = kmalloc_array(n: max_usage, size: sizeof(struct page *), GFP_KERNEL); |
280 | spd->partial = kmalloc_array(n: max_usage, size: sizeof(struct partial_page), |
281 | GFP_KERNEL); |
282 | |
283 | if (spd->pages && spd->partial) |
284 | return 0; |
285 | |
286 | kfree(objp: spd->pages); |
287 | kfree(objp: spd->partial); |
288 | return -ENOMEM; |
289 | } |
290 | |
291 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
292 | { |
293 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
294 | return; |
295 | |
296 | kfree(objp: spd->pages); |
297 | kfree(objp: spd->partial); |
298 | } |
299 | |
300 | /** |
301 | * copy_splice_read - Copy data from a file and splice the copy into a pipe |
302 | * @in: The file to read from |
303 | * @ppos: Pointer to the file position to read from |
304 | * @pipe: The pipe to splice into |
305 | * @len: The amount to splice |
306 | * @flags: The SPLICE_F_* flags |
307 | * |
308 | * This function allocates a bunch of pages sufficient to hold the requested |
309 | * amount of data (but limited by the remaining pipe capacity), passes it to |
310 | * the file's ->read_iter() to read into and then splices the used pages into |
311 | * the pipe. |
312 | * |
313 | * Return: On success, the number of bytes read will be returned and *@ppos |
314 | * will be updated if appropriate; 0 will be returned if there is no more data |
315 | * to be read; -EAGAIN will be returned if the pipe had no space, and some |
316 | * other negative error code will be returned on error. A short read may occur |
317 | * if the pipe has insufficient space, we reach the end of the data or we hit a |
318 | * hole. |
319 | */ |
320 | ssize_t copy_splice_read(struct file *in, loff_t *ppos, |
321 | struct pipe_inode_info *pipe, |
322 | size_t len, unsigned int flags) |
323 | { |
324 | struct iov_iter to; |
325 | struct bio_vec *bv; |
326 | struct kiocb kiocb; |
327 | struct page **pages; |
328 | ssize_t ret; |
329 | size_t used, npages, chunk, remain, keep = 0; |
330 | int i; |
331 | |
332 | /* Work out how much data we can actually add into the pipe */ |
333 | used = pipe_occupancy(head: pipe->head, tail: pipe->tail); |
334 | npages = max_t(ssize_t, pipe->max_usage - used, 0); |
335 | len = min_t(size_t, len, npages * PAGE_SIZE); |
336 | npages = DIV_ROUND_UP(len, PAGE_SIZE); |
337 | |
338 | bv = kzalloc(array_size(npages, sizeof(bv[0])) + |
339 | array_size(npages, sizeof(struct page *)), GFP_KERNEL); |
340 | if (!bv) |
341 | return -ENOMEM; |
342 | |
343 | pages = (struct page **)(bv + npages); |
344 | npages = alloc_pages_bulk_array(GFP_USER, nr_pages: npages, page_array: pages); |
345 | if (!npages) { |
346 | kfree(objp: bv); |
347 | return -ENOMEM; |
348 | } |
349 | |
350 | remain = len = min_t(size_t, len, npages * PAGE_SIZE); |
351 | |
352 | for (i = 0; i < npages; i++) { |
353 | chunk = min_t(size_t, PAGE_SIZE, remain); |
354 | bv[i].bv_page = pages[i]; |
355 | bv[i].bv_offset = 0; |
356 | bv[i].bv_len = chunk; |
357 | remain -= chunk; |
358 | } |
359 | |
360 | /* Do the I/O */ |
361 | iov_iter_bvec(i: &to, ITER_DEST, bvec: bv, nr_segs: npages, count: len); |
362 | init_sync_kiocb(kiocb: &kiocb, filp: in); |
363 | kiocb.ki_pos = *ppos; |
364 | ret = call_read_iter(file: in, kio: &kiocb, iter: &to); |
365 | |
366 | if (ret > 0) { |
367 | keep = DIV_ROUND_UP(ret, PAGE_SIZE); |
368 | *ppos = kiocb.ki_pos; |
369 | } |
370 | |
371 | /* |
372 | * Callers of ->splice_read() expect -EAGAIN on "can't put anything in |
373 | * there", rather than -EFAULT. |
374 | */ |
375 | if (ret == -EFAULT) |
376 | ret = -EAGAIN; |
377 | |
378 | /* Free any pages that didn't get touched at all. */ |
379 | if (keep < npages) |
380 | release_pages(pages + keep, nr: npages - keep); |
381 | |
382 | /* Push the remaining pages into the pipe. */ |
383 | remain = ret; |
384 | for (i = 0; i < keep; i++) { |
385 | struct pipe_buffer *buf = pipe_head_buf(pipe); |
386 | |
387 | chunk = min_t(size_t, remain, PAGE_SIZE); |
388 | *buf = (struct pipe_buffer) { |
389 | .ops = &default_pipe_buf_ops, |
390 | .page = bv[i].bv_page, |
391 | .offset = 0, |
392 | .len = chunk, |
393 | }; |
394 | pipe->head++; |
395 | remain -= chunk; |
396 | } |
397 | |
398 | kfree(objp: bv); |
399 | return ret; |
400 | } |
401 | EXPORT_SYMBOL(copy_splice_read); |
402 | |
403 | const struct pipe_buf_operations default_pipe_buf_ops = { |
404 | .release = generic_pipe_buf_release, |
405 | .try_steal = generic_pipe_buf_try_steal, |
406 | .get = generic_pipe_buf_get, |
407 | }; |
408 | |
409 | /* Pipe buffer operations for a socket and similar. */ |
410 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { |
411 | .release = generic_pipe_buf_release, |
412 | .get = generic_pipe_buf_get, |
413 | }; |
414 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); |
415 | |
416 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
417 | { |
418 | smp_mb(); |
419 | if (waitqueue_active(wq_head: &pipe->wr_wait)) |
420 | wake_up_interruptible(&pipe->wr_wait); |
421 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
422 | } |
423 | |
424 | /** |
425 | * splice_from_pipe_feed - feed available data from a pipe to a file |
426 | * @pipe: pipe to splice from |
427 | * @sd: information to @actor |
428 | * @actor: handler that splices the data |
429 | * |
430 | * Description: |
431 | * This function loops over the pipe and calls @actor to do the |
432 | * actual moving of a single struct pipe_buffer to the desired |
433 | * destination. It returns when there's no more buffers left in |
434 | * the pipe or if the requested number of bytes (@sd->total_len) |
435 | * have been copied. It returns a positive number (one) if the |
436 | * pipe needs to be filled with more data, zero if the required |
437 | * number of bytes have been copied and -errno on error. |
438 | * |
439 | * This, together with splice_from_pipe_{begin,end,next}, may be |
440 | * used to implement the functionality of __splice_from_pipe() when |
441 | * locking is required around copying the pipe buffers to the |
442 | * destination. |
443 | */ |
444 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
445 | splice_actor *actor) |
446 | { |
447 | unsigned int head = pipe->head; |
448 | unsigned int tail = pipe->tail; |
449 | unsigned int mask = pipe->ring_size - 1; |
450 | int ret; |
451 | |
452 | while (!pipe_empty(head, tail)) { |
453 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
454 | |
455 | sd->len = buf->len; |
456 | if (sd->len > sd->total_len) |
457 | sd->len = sd->total_len; |
458 | |
459 | ret = pipe_buf_confirm(pipe, buf); |
460 | if (unlikely(ret)) { |
461 | if (ret == -ENODATA) |
462 | ret = 0; |
463 | return ret; |
464 | } |
465 | |
466 | ret = actor(pipe, buf, sd); |
467 | if (ret <= 0) |
468 | return ret; |
469 | |
470 | buf->offset += ret; |
471 | buf->len -= ret; |
472 | |
473 | sd->num_spliced += ret; |
474 | sd->len -= ret; |
475 | sd->pos += ret; |
476 | sd->total_len -= ret; |
477 | |
478 | if (!buf->len) { |
479 | pipe_buf_release(pipe, buf); |
480 | tail++; |
481 | pipe->tail = tail; |
482 | if (pipe->files) |
483 | sd->need_wakeup = true; |
484 | } |
485 | |
486 | if (!sd->total_len) |
487 | return 0; |
488 | } |
489 | |
490 | return 1; |
491 | } |
492 | |
493 | /* We know we have a pipe buffer, but maybe it's empty? */ |
494 | static inline bool eat_empty_buffer(struct pipe_inode_info *pipe) |
495 | { |
496 | unsigned int tail = pipe->tail; |
497 | unsigned int mask = pipe->ring_size - 1; |
498 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
499 | |
500 | if (unlikely(!buf->len)) { |
501 | pipe_buf_release(pipe, buf); |
502 | pipe->tail = tail+1; |
503 | return true; |
504 | } |
505 | |
506 | return false; |
507 | } |
508 | |
509 | /** |
510 | * splice_from_pipe_next - wait for some data to splice from |
511 | * @pipe: pipe to splice from |
512 | * @sd: information about the splice operation |
513 | * |
514 | * Description: |
515 | * This function will wait for some data and return a positive |
516 | * value (one) if pipe buffers are available. It will return zero |
517 | * or -errno if no more data needs to be spliced. |
518 | */ |
519 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
520 | { |
521 | /* |
522 | * Check for signal early to make process killable when there are |
523 | * always buffers available |
524 | */ |
525 | if (signal_pending(current)) |
526 | return -ERESTARTSYS; |
527 | |
528 | repeat: |
529 | while (pipe_empty(head: pipe->head, tail: pipe->tail)) { |
530 | if (!pipe->writers) |
531 | return 0; |
532 | |
533 | if (sd->num_spliced) |
534 | return 0; |
535 | |
536 | if (sd->flags & SPLICE_F_NONBLOCK) |
537 | return -EAGAIN; |
538 | |
539 | if (signal_pending(current)) |
540 | return -ERESTARTSYS; |
541 | |
542 | if (sd->need_wakeup) { |
543 | wakeup_pipe_writers(pipe); |
544 | sd->need_wakeup = false; |
545 | } |
546 | |
547 | pipe_wait_readable(pipe); |
548 | } |
549 | |
550 | if (eat_empty_buffer(pipe)) |
551 | goto repeat; |
552 | |
553 | return 1; |
554 | } |
555 | |
556 | /** |
557 | * splice_from_pipe_begin - start splicing from pipe |
558 | * @sd: information about the splice operation |
559 | * |
560 | * Description: |
561 | * This function should be called before a loop containing |
562 | * splice_from_pipe_next() and splice_from_pipe_feed() to |
563 | * initialize the necessary fields of @sd. |
564 | */ |
565 | static void splice_from_pipe_begin(struct splice_desc *sd) |
566 | { |
567 | sd->num_spliced = 0; |
568 | sd->need_wakeup = false; |
569 | } |
570 | |
571 | /** |
572 | * splice_from_pipe_end - finish splicing from pipe |
573 | * @pipe: pipe to splice from |
574 | * @sd: information about the splice operation |
575 | * |
576 | * Description: |
577 | * This function will wake up pipe writers if necessary. It should |
578 | * be called after a loop containing splice_from_pipe_next() and |
579 | * splice_from_pipe_feed(). |
580 | */ |
581 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
582 | { |
583 | if (sd->need_wakeup) |
584 | wakeup_pipe_writers(pipe); |
585 | } |
586 | |
587 | /** |
588 | * __splice_from_pipe - splice data from a pipe to given actor |
589 | * @pipe: pipe to splice from |
590 | * @sd: information to @actor |
591 | * @actor: handler that splices the data |
592 | * |
593 | * Description: |
594 | * This function does little more than loop over the pipe and call |
595 | * @actor to do the actual moving of a single struct pipe_buffer to |
596 | * the desired destination. See pipe_to_file, pipe_to_sendmsg, or |
597 | * pipe_to_user. |
598 | * |
599 | */ |
600 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
601 | splice_actor *actor) |
602 | { |
603 | int ret; |
604 | |
605 | splice_from_pipe_begin(sd); |
606 | do { |
607 | cond_resched(); |
608 | ret = splice_from_pipe_next(pipe, sd); |
609 | if (ret > 0) |
610 | ret = splice_from_pipe_feed(pipe, sd, actor); |
611 | } while (ret > 0); |
612 | splice_from_pipe_end(pipe, sd); |
613 | |
614 | return sd->num_spliced ? sd->num_spliced : ret; |
615 | } |
616 | EXPORT_SYMBOL(__splice_from_pipe); |
617 | |
618 | /** |
619 | * splice_from_pipe - splice data from a pipe to a file |
620 | * @pipe: pipe to splice from |
621 | * @out: file to splice to |
622 | * @ppos: position in @out |
623 | * @len: how many bytes to splice |
624 | * @flags: splice modifier flags |
625 | * @actor: handler that splices the data |
626 | * |
627 | * Description: |
628 | * See __splice_from_pipe. This function locks the pipe inode, |
629 | * otherwise it's identical to __splice_from_pipe(). |
630 | * |
631 | */ |
632 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
633 | loff_t *ppos, size_t len, unsigned int flags, |
634 | splice_actor *actor) |
635 | { |
636 | ssize_t ret; |
637 | struct splice_desc sd = { |
638 | .total_len = len, |
639 | .flags = flags, |
640 | .pos = *ppos, |
641 | .u.file = out, |
642 | }; |
643 | |
644 | pipe_lock(pipe); |
645 | ret = __splice_from_pipe(pipe, &sd, actor); |
646 | pipe_unlock(pipe); |
647 | |
648 | return ret; |
649 | } |
650 | |
651 | /** |
652 | * iter_file_splice_write - splice data from a pipe to a file |
653 | * @pipe: pipe info |
654 | * @out: file to write to |
655 | * @ppos: position in @out |
656 | * @len: number of bytes to splice |
657 | * @flags: splice modifier flags |
658 | * |
659 | * Description: |
660 | * Will either move or copy pages (determined by @flags options) from |
661 | * the given pipe inode to the given file. |
662 | * This one is ->write_iter-based. |
663 | * |
664 | */ |
665 | ssize_t |
666 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, |
667 | loff_t *ppos, size_t len, unsigned int flags) |
668 | { |
669 | struct splice_desc sd = { |
670 | .total_len = len, |
671 | .flags = flags, |
672 | .pos = *ppos, |
673 | .u.file = out, |
674 | }; |
675 | int nbufs = pipe->max_usage; |
676 | struct bio_vec *array = kcalloc(n: nbufs, size: sizeof(struct bio_vec), |
677 | GFP_KERNEL); |
678 | ssize_t ret; |
679 | |
680 | if (unlikely(!array)) |
681 | return -ENOMEM; |
682 | |
683 | pipe_lock(pipe); |
684 | |
685 | splice_from_pipe_begin(sd: &sd); |
686 | while (sd.total_len) { |
687 | struct iov_iter from; |
688 | unsigned int head, tail, mask; |
689 | size_t left; |
690 | int n; |
691 | |
692 | ret = splice_from_pipe_next(pipe, sd: &sd); |
693 | if (ret <= 0) |
694 | break; |
695 | |
696 | if (unlikely(nbufs < pipe->max_usage)) { |
697 | kfree(objp: array); |
698 | nbufs = pipe->max_usage; |
699 | array = kcalloc(n: nbufs, size: sizeof(struct bio_vec), |
700 | GFP_KERNEL); |
701 | if (!array) { |
702 | ret = -ENOMEM; |
703 | break; |
704 | } |
705 | } |
706 | |
707 | head = pipe->head; |
708 | tail = pipe->tail; |
709 | mask = pipe->ring_size - 1; |
710 | |
711 | /* build the vector */ |
712 | left = sd.total_len; |
713 | for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) { |
714 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
715 | size_t this_len = buf->len; |
716 | |
717 | /* zero-length bvecs are not supported, skip them */ |
718 | if (!this_len) |
719 | continue; |
720 | this_len = min(this_len, left); |
721 | |
722 | ret = pipe_buf_confirm(pipe, buf); |
723 | if (unlikely(ret)) { |
724 | if (ret == -ENODATA) |
725 | ret = 0; |
726 | goto done; |
727 | } |
728 | |
729 | bvec_set_page(bv: &array[n], page: buf->page, len: this_len, |
730 | offset: buf->offset); |
731 | left -= this_len; |
732 | n++; |
733 | } |
734 | |
735 | iov_iter_bvec(i: &from, ITER_SOURCE, bvec: array, nr_segs: n, count: sd.total_len - left); |
736 | ret = vfs_iter_write(file: out, iter: &from, ppos: &sd.pos, flags: 0); |
737 | if (ret <= 0) |
738 | break; |
739 | |
740 | sd.num_spliced += ret; |
741 | sd.total_len -= ret; |
742 | *ppos = sd.pos; |
743 | |
744 | /* dismiss the fully eaten buffers, adjust the partial one */ |
745 | tail = pipe->tail; |
746 | while (ret) { |
747 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
748 | if (ret >= buf->len) { |
749 | ret -= buf->len; |
750 | buf->len = 0; |
751 | pipe_buf_release(pipe, buf); |
752 | tail++; |
753 | pipe->tail = tail; |
754 | if (pipe->files) |
755 | sd.need_wakeup = true; |
756 | } else { |
757 | buf->offset += ret; |
758 | buf->len -= ret; |
759 | ret = 0; |
760 | } |
761 | } |
762 | } |
763 | done: |
764 | kfree(objp: array); |
765 | splice_from_pipe_end(pipe, sd: &sd); |
766 | |
767 | pipe_unlock(pipe); |
768 | |
769 | if (sd.num_spliced) |
770 | ret = sd.num_spliced; |
771 | |
772 | return ret; |
773 | } |
774 | |
775 | EXPORT_SYMBOL(iter_file_splice_write); |
776 | |
777 | #ifdef CONFIG_NET |
778 | /** |
779 | * splice_to_socket - splice data from a pipe to a socket |
780 | * @pipe: pipe to splice from |
781 | * @out: socket to write to |
782 | * @ppos: position in @out |
783 | * @len: number of bytes to splice |
784 | * @flags: splice modifier flags |
785 | * |
786 | * Description: |
787 | * Will send @len bytes from the pipe to a network socket. No data copying |
788 | * is involved. |
789 | * |
790 | */ |
791 | ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out, |
792 | loff_t *ppos, size_t len, unsigned int flags) |
793 | { |
794 | struct socket *sock = sock_from_file(file: out); |
795 | struct bio_vec bvec[16]; |
796 | struct msghdr msg = {}; |
797 | ssize_t ret = 0; |
798 | size_t spliced = 0; |
799 | bool need_wakeup = false; |
800 | |
801 | pipe_lock(pipe); |
802 | |
803 | while (len > 0) { |
804 | unsigned int head, tail, mask, bc = 0; |
805 | size_t remain = len; |
806 | |
807 | /* |
808 | * Check for signal early to make process killable when there |
809 | * are always buffers available |
810 | */ |
811 | ret = -ERESTARTSYS; |
812 | if (signal_pending(current)) |
813 | break; |
814 | |
815 | while (pipe_empty(head: pipe->head, tail: pipe->tail)) { |
816 | ret = 0; |
817 | if (!pipe->writers) |
818 | goto out; |
819 | |
820 | if (spliced) |
821 | goto out; |
822 | |
823 | ret = -EAGAIN; |
824 | if (flags & SPLICE_F_NONBLOCK) |
825 | goto out; |
826 | |
827 | ret = -ERESTARTSYS; |
828 | if (signal_pending(current)) |
829 | goto out; |
830 | |
831 | if (need_wakeup) { |
832 | wakeup_pipe_writers(pipe); |
833 | need_wakeup = false; |
834 | } |
835 | |
836 | pipe_wait_readable(pipe); |
837 | } |
838 | |
839 | head = pipe->head; |
840 | tail = pipe->tail; |
841 | mask = pipe->ring_size - 1; |
842 | |
843 | while (!pipe_empty(head, tail)) { |
844 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
845 | size_t seg; |
846 | |
847 | if (!buf->len) { |
848 | tail++; |
849 | continue; |
850 | } |
851 | |
852 | seg = min_t(size_t, remain, buf->len); |
853 | |
854 | ret = pipe_buf_confirm(pipe, buf); |
855 | if (unlikely(ret)) { |
856 | if (ret == -ENODATA) |
857 | ret = 0; |
858 | break; |
859 | } |
860 | |
861 | bvec_set_page(bv: &bvec[bc++], page: buf->page, len: seg, offset: buf->offset); |
862 | remain -= seg; |
863 | if (remain == 0 || bc >= ARRAY_SIZE(bvec)) |
864 | break; |
865 | tail++; |
866 | } |
867 | |
868 | if (!bc) |
869 | break; |
870 | |
871 | msg.msg_flags = MSG_SPLICE_PAGES; |
872 | if (flags & SPLICE_F_MORE) |
873 | msg.msg_flags |= MSG_MORE; |
874 | if (remain && pipe_occupancy(head: pipe->head, tail) > 0) |
875 | msg.msg_flags |= MSG_MORE; |
876 | if (out->f_flags & O_NONBLOCK) |
877 | msg.msg_flags |= MSG_DONTWAIT; |
878 | |
879 | iov_iter_bvec(i: &msg.msg_iter, ITER_SOURCE, bvec, nr_segs: bc, |
880 | count: len - remain); |
881 | ret = sock_sendmsg(sock, msg: &msg); |
882 | if (ret <= 0) |
883 | break; |
884 | |
885 | spliced += ret; |
886 | len -= ret; |
887 | tail = pipe->tail; |
888 | while (ret > 0) { |
889 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
890 | size_t seg = min_t(size_t, ret, buf->len); |
891 | |
892 | buf->offset += seg; |
893 | buf->len -= seg; |
894 | ret -= seg; |
895 | |
896 | if (!buf->len) { |
897 | pipe_buf_release(pipe, buf); |
898 | tail++; |
899 | } |
900 | } |
901 | |
902 | if (tail != pipe->tail) { |
903 | pipe->tail = tail; |
904 | if (pipe->files) |
905 | need_wakeup = true; |
906 | } |
907 | } |
908 | |
909 | out: |
910 | pipe_unlock(pipe); |
911 | if (need_wakeup) |
912 | wakeup_pipe_writers(pipe); |
913 | return spliced ?: ret; |
914 | } |
915 | #endif |
916 | |
917 | static int warn_unsupported(struct file *file, const char *op) |
918 | { |
919 | pr_debug_ratelimited( |
920 | "splice %s not supported for file %pD4 (pid: %d comm: %.20s)\n" , |
921 | op, file, current->pid, current->comm); |
922 | return -EINVAL; |
923 | } |
924 | |
925 | /* |
926 | * Attempt to initiate a splice from pipe to file. |
927 | */ |
928 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
929 | loff_t *ppos, size_t len, unsigned int flags) |
930 | { |
931 | if (unlikely(!out->f_op->splice_write)) |
932 | return warn_unsupported(file: out, op: "write" ); |
933 | return out->f_op->splice_write(pipe, out, ppos, len, flags); |
934 | } |
935 | |
936 | /* |
937 | * Indicate to the caller that there was a premature EOF when reading from the |
938 | * source and the caller didn't indicate they would be sending more data after |
939 | * this. |
940 | */ |
941 | static void do_splice_eof(struct splice_desc *sd) |
942 | { |
943 | if (sd->splice_eof) |
944 | sd->splice_eof(sd); |
945 | } |
946 | |
947 | /** |
948 | * vfs_splice_read - Read data from a file and splice it into a pipe |
949 | * @in: File to splice from |
950 | * @ppos: Input file offset |
951 | * @pipe: Pipe to splice to |
952 | * @len: Number of bytes to splice |
953 | * @flags: Splice modifier flags (SPLICE_F_*) |
954 | * |
955 | * Splice the requested amount of data from the input file to the pipe. This |
956 | * is synchronous as the caller must hold the pipe lock across the entire |
957 | * operation. |
958 | * |
959 | * If successful, it returns the amount of data spliced, 0 if it hit the EOF or |
960 | * a hole and a negative error code otherwise. |
961 | */ |
962 | long vfs_splice_read(struct file *in, loff_t *ppos, |
963 | struct pipe_inode_info *pipe, size_t len, |
964 | unsigned int flags) |
965 | { |
966 | unsigned int p_space; |
967 | int ret; |
968 | |
969 | if (unlikely(!(in->f_mode & FMODE_READ))) |
970 | return -EBADF; |
971 | if (!len) |
972 | return 0; |
973 | |
974 | /* Don't try to read more the pipe has space for. */ |
975 | p_space = pipe->max_usage - pipe_occupancy(head: pipe->head, tail: pipe->tail); |
976 | len = min_t(size_t, len, p_space << PAGE_SHIFT); |
977 | |
978 | ret = rw_verify_area(READ, in, ppos, len); |
979 | if (unlikely(ret < 0)) |
980 | return ret; |
981 | |
982 | if (unlikely(len > MAX_RW_COUNT)) |
983 | len = MAX_RW_COUNT; |
984 | |
985 | if (unlikely(!in->f_op->splice_read)) |
986 | return warn_unsupported(file: in, op: "read" ); |
987 | /* |
988 | * O_DIRECT and DAX don't deal with the pagecache, so we allocate a |
989 | * buffer, copy into it and splice that into the pipe. |
990 | */ |
991 | if ((in->f_flags & O_DIRECT) || IS_DAX(in->f_mapping->host)) |
992 | return copy_splice_read(in, ppos, pipe, len, flags); |
993 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
994 | } |
995 | EXPORT_SYMBOL_GPL(vfs_splice_read); |
996 | |
997 | /** |
998 | * splice_direct_to_actor - splices data directly between two non-pipes |
999 | * @in: file to splice from |
1000 | * @sd: actor information on where to splice to |
1001 | * @actor: handles the data splicing |
1002 | * |
1003 | * Description: |
1004 | * This is a special case helper to splice directly between two |
1005 | * points, without requiring an explicit pipe. Internally an allocated |
1006 | * pipe is cached in the process, and reused during the lifetime of |
1007 | * that process. |
1008 | * |
1009 | */ |
1010 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, |
1011 | splice_direct_actor *actor) |
1012 | { |
1013 | struct pipe_inode_info *pipe; |
1014 | long ret, bytes; |
1015 | size_t len; |
1016 | int i, flags, more; |
1017 | |
1018 | /* |
1019 | * We require the input to be seekable, as we don't want to randomly |
1020 | * drop data for eg socket -> socket splicing. Use the piped splicing |
1021 | * for that! |
1022 | */ |
1023 | if (unlikely(!(in->f_mode & FMODE_LSEEK))) |
1024 | return -EINVAL; |
1025 | |
1026 | /* |
1027 | * neither in nor out is a pipe, setup an internal pipe attached to |
1028 | * 'out' and transfer the wanted data from 'in' to 'out' through that |
1029 | */ |
1030 | pipe = current->splice_pipe; |
1031 | if (unlikely(!pipe)) { |
1032 | pipe = alloc_pipe_info(); |
1033 | if (!pipe) |
1034 | return -ENOMEM; |
1035 | |
1036 | /* |
1037 | * We don't have an immediate reader, but we'll read the stuff |
1038 | * out of the pipe right after the splice_to_pipe(). So set |
1039 | * PIPE_READERS appropriately. |
1040 | */ |
1041 | pipe->readers = 1; |
1042 | |
1043 | current->splice_pipe = pipe; |
1044 | } |
1045 | |
1046 | /* |
1047 | * Do the splice. |
1048 | */ |
1049 | bytes = 0; |
1050 | len = sd->total_len; |
1051 | |
1052 | /* Don't block on output, we have to drain the direct pipe. */ |
1053 | flags = sd->flags; |
1054 | sd->flags &= ~SPLICE_F_NONBLOCK; |
1055 | |
1056 | /* |
1057 | * We signal MORE until we've read sufficient data to fulfill the |
1058 | * request and we keep signalling it if the caller set it. |
1059 | */ |
1060 | more = sd->flags & SPLICE_F_MORE; |
1061 | sd->flags |= SPLICE_F_MORE; |
1062 | |
1063 | WARN_ON_ONCE(!pipe_empty(pipe->head, pipe->tail)); |
1064 | |
1065 | while (len) { |
1066 | size_t read_len; |
1067 | loff_t pos = sd->pos, prev_pos = pos; |
1068 | |
1069 | ret = vfs_splice_read(in, &pos, pipe, len, flags); |
1070 | if (unlikely(ret <= 0)) |
1071 | goto read_failure; |
1072 | |
1073 | read_len = ret; |
1074 | sd->total_len = read_len; |
1075 | |
1076 | /* |
1077 | * If we now have sufficient data to fulfill the request then |
1078 | * we clear SPLICE_F_MORE if it was not set initially. |
1079 | */ |
1080 | if (read_len >= len && !more) |
1081 | sd->flags &= ~SPLICE_F_MORE; |
1082 | |
1083 | /* |
1084 | * NOTE: nonblocking mode only applies to the input. We |
1085 | * must not do the output in nonblocking mode as then we |
1086 | * could get stuck data in the internal pipe: |
1087 | */ |
1088 | ret = actor(pipe, sd); |
1089 | if (unlikely(ret <= 0)) { |
1090 | sd->pos = prev_pos; |
1091 | goto out_release; |
1092 | } |
1093 | |
1094 | bytes += ret; |
1095 | len -= ret; |
1096 | sd->pos = pos; |
1097 | |
1098 | if (ret < read_len) { |
1099 | sd->pos = prev_pos + ret; |
1100 | goto out_release; |
1101 | } |
1102 | } |
1103 | |
1104 | done: |
1105 | pipe->tail = pipe->head = 0; |
1106 | file_accessed(file: in); |
1107 | return bytes; |
1108 | |
1109 | read_failure: |
1110 | /* |
1111 | * If the user did *not* set SPLICE_F_MORE *and* we didn't hit that |
1112 | * "use all of len" case that cleared SPLICE_F_MORE, *and* we did a |
1113 | * "->splice_in()" that returned EOF (ie zero) *and* we have sent at |
1114 | * least 1 byte *then* we will also do the ->splice_eof() call. |
1115 | */ |
1116 | if (ret == 0 && !more && len > 0 && bytes) |
1117 | do_splice_eof(sd); |
1118 | out_release: |
1119 | /* |
1120 | * If we did an incomplete transfer we must release |
1121 | * the pipe buffers in question: |
1122 | */ |
1123 | for (i = 0; i < pipe->ring_size; i++) { |
1124 | struct pipe_buffer *buf = &pipe->bufs[i]; |
1125 | |
1126 | if (buf->ops) |
1127 | pipe_buf_release(pipe, buf); |
1128 | } |
1129 | |
1130 | if (!bytes) |
1131 | bytes = ret; |
1132 | |
1133 | goto done; |
1134 | } |
1135 | EXPORT_SYMBOL(splice_direct_to_actor); |
1136 | |
1137 | static int direct_splice_actor(struct pipe_inode_info *pipe, |
1138 | struct splice_desc *sd) |
1139 | { |
1140 | struct file *file = sd->u.file; |
1141 | |
1142 | return do_splice_from(pipe, out: file, ppos: sd->opos, len: sd->total_len, |
1143 | flags: sd->flags); |
1144 | } |
1145 | |
1146 | static void direct_file_splice_eof(struct splice_desc *sd) |
1147 | { |
1148 | struct file *file = sd->u.file; |
1149 | |
1150 | if (file->f_op->splice_eof) |
1151 | file->f_op->splice_eof(file); |
1152 | } |
1153 | |
1154 | /** |
1155 | * do_splice_direct - splices data directly between two files |
1156 | * @in: file to splice from |
1157 | * @ppos: input file offset |
1158 | * @out: file to splice to |
1159 | * @opos: output file offset |
1160 | * @len: number of bytes to splice |
1161 | * @flags: splice modifier flags |
1162 | * |
1163 | * Description: |
1164 | * For use by do_sendfile(). splice can easily emulate sendfile, but |
1165 | * doing it in the application would incur an extra system call |
1166 | * (splice in + splice out, as compared to just sendfile()). So this helper |
1167 | * can splice directly through a process-private pipe. |
1168 | * |
1169 | */ |
1170 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
1171 | loff_t *opos, size_t len, unsigned int flags) |
1172 | { |
1173 | struct splice_desc sd = { |
1174 | .len = len, |
1175 | .total_len = len, |
1176 | .flags = flags, |
1177 | .pos = *ppos, |
1178 | .u.file = out, |
1179 | .splice_eof = direct_file_splice_eof, |
1180 | .opos = opos, |
1181 | }; |
1182 | long ret; |
1183 | |
1184 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1185 | return -EBADF; |
1186 | |
1187 | if (unlikely(out->f_flags & O_APPEND)) |
1188 | return -EINVAL; |
1189 | |
1190 | ret = rw_verify_area(WRITE, out, opos, len); |
1191 | if (unlikely(ret < 0)) |
1192 | return ret; |
1193 | |
1194 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
1195 | if (ret > 0) |
1196 | *ppos = sd.pos; |
1197 | |
1198 | return ret; |
1199 | } |
1200 | EXPORT_SYMBOL(do_splice_direct); |
1201 | |
1202 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) |
1203 | { |
1204 | for (;;) { |
1205 | if (unlikely(!pipe->readers)) { |
1206 | send_sig(SIGPIPE, current, 0); |
1207 | return -EPIPE; |
1208 | } |
1209 | if (!pipe_full(head: pipe->head, tail: pipe->tail, limit: pipe->max_usage)) |
1210 | return 0; |
1211 | if (flags & SPLICE_F_NONBLOCK) |
1212 | return -EAGAIN; |
1213 | if (signal_pending(current)) |
1214 | return -ERESTARTSYS; |
1215 | pipe_wait_writable(pipe); |
1216 | } |
1217 | } |
1218 | |
1219 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1220 | struct pipe_inode_info *opipe, |
1221 | size_t len, unsigned int flags); |
1222 | |
1223 | long splice_file_to_pipe(struct file *in, |
1224 | struct pipe_inode_info *opipe, |
1225 | loff_t *offset, |
1226 | size_t len, unsigned int flags) |
1227 | { |
1228 | long ret; |
1229 | |
1230 | pipe_lock(opipe); |
1231 | ret = wait_for_space(pipe: opipe, flags); |
1232 | if (!ret) |
1233 | ret = vfs_splice_read(in, offset, opipe, len, flags); |
1234 | pipe_unlock(opipe); |
1235 | if (ret > 0) |
1236 | wakeup_pipe_readers(pipe: opipe); |
1237 | return ret; |
1238 | } |
1239 | |
1240 | /* |
1241 | * Determine where to splice to/from. |
1242 | */ |
1243 | long do_splice(struct file *in, loff_t *off_in, struct file *out, |
1244 | loff_t *off_out, size_t len, unsigned int flags) |
1245 | { |
1246 | struct pipe_inode_info *ipipe; |
1247 | struct pipe_inode_info *opipe; |
1248 | loff_t offset; |
1249 | long ret; |
1250 | |
1251 | if (unlikely(!(in->f_mode & FMODE_READ) || |
1252 | !(out->f_mode & FMODE_WRITE))) |
1253 | return -EBADF; |
1254 | |
1255 | ipipe = get_pipe_info(file: in, for_splice: true); |
1256 | opipe = get_pipe_info(file: out, for_splice: true); |
1257 | |
1258 | if (ipipe && opipe) { |
1259 | if (off_in || off_out) |
1260 | return -ESPIPE; |
1261 | |
1262 | /* Splicing to self would be fun, but... */ |
1263 | if (ipipe == opipe) |
1264 | return -EINVAL; |
1265 | |
1266 | if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
1267 | flags |= SPLICE_F_NONBLOCK; |
1268 | |
1269 | ret = splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1270 | } else if (ipipe) { |
1271 | if (off_in) |
1272 | return -ESPIPE; |
1273 | if (off_out) { |
1274 | if (!(out->f_mode & FMODE_PWRITE)) |
1275 | return -EINVAL; |
1276 | offset = *off_out; |
1277 | } else { |
1278 | offset = out->f_pos; |
1279 | } |
1280 | |
1281 | if (unlikely(out->f_flags & O_APPEND)) |
1282 | return -EINVAL; |
1283 | |
1284 | ret = rw_verify_area(WRITE, out, &offset, len); |
1285 | if (unlikely(ret < 0)) |
1286 | return ret; |
1287 | |
1288 | if (in->f_flags & O_NONBLOCK) |
1289 | flags |= SPLICE_F_NONBLOCK; |
1290 | |
1291 | file_start_write(file: out); |
1292 | ret = do_splice_from(pipe: ipipe, out, ppos: &offset, len, flags); |
1293 | file_end_write(file: out); |
1294 | |
1295 | if (!off_out) |
1296 | out->f_pos = offset; |
1297 | else |
1298 | *off_out = offset; |
1299 | } else if (opipe) { |
1300 | if (off_out) |
1301 | return -ESPIPE; |
1302 | if (off_in) { |
1303 | if (!(in->f_mode & FMODE_PREAD)) |
1304 | return -EINVAL; |
1305 | offset = *off_in; |
1306 | } else { |
1307 | offset = in->f_pos; |
1308 | } |
1309 | |
1310 | if (out->f_flags & O_NONBLOCK) |
1311 | flags |= SPLICE_F_NONBLOCK; |
1312 | |
1313 | ret = splice_file_to_pipe(in, opipe, offset: &offset, len, flags); |
1314 | |
1315 | if (!off_in) |
1316 | in->f_pos = offset; |
1317 | else |
1318 | *off_in = offset; |
1319 | } else { |
1320 | ret = -EINVAL; |
1321 | } |
1322 | |
1323 | if (ret > 0) { |
1324 | /* |
1325 | * Generate modify out before access in: |
1326 | * do_splice_from() may've already sent modify out, |
1327 | * and this ensures the events get merged. |
1328 | */ |
1329 | fsnotify_modify(file: out); |
1330 | fsnotify_access(file: in); |
1331 | } |
1332 | |
1333 | return ret; |
1334 | } |
1335 | |
1336 | static long __do_splice(struct file *in, loff_t __user *off_in, |
1337 | struct file *out, loff_t __user *off_out, |
1338 | size_t len, unsigned int flags) |
1339 | { |
1340 | struct pipe_inode_info *ipipe; |
1341 | struct pipe_inode_info *opipe; |
1342 | loff_t offset, *__off_in = NULL, *__off_out = NULL; |
1343 | long ret; |
1344 | |
1345 | ipipe = get_pipe_info(file: in, for_splice: true); |
1346 | opipe = get_pipe_info(file: out, for_splice: true); |
1347 | |
1348 | if (ipipe) { |
1349 | if (off_in) |
1350 | return -ESPIPE; |
1351 | pipe_clear_nowait(file: in); |
1352 | } |
1353 | if (opipe) { |
1354 | if (off_out) |
1355 | return -ESPIPE; |
1356 | pipe_clear_nowait(file: out); |
1357 | } |
1358 | |
1359 | if (off_out) { |
1360 | if (copy_from_user(to: &offset, from: off_out, n: sizeof(loff_t))) |
1361 | return -EFAULT; |
1362 | __off_out = &offset; |
1363 | } |
1364 | if (off_in) { |
1365 | if (copy_from_user(to: &offset, from: off_in, n: sizeof(loff_t))) |
1366 | return -EFAULT; |
1367 | __off_in = &offset; |
1368 | } |
1369 | |
1370 | ret = do_splice(in, off_in: __off_in, out, off_out: __off_out, len, flags); |
1371 | if (ret < 0) |
1372 | return ret; |
1373 | |
1374 | if (__off_out && copy_to_user(to: off_out, from: __off_out, n: sizeof(loff_t))) |
1375 | return -EFAULT; |
1376 | if (__off_in && copy_to_user(to: off_in, from: __off_in, n: sizeof(loff_t))) |
1377 | return -EFAULT; |
1378 | |
1379 | return ret; |
1380 | } |
1381 | |
1382 | static int iter_to_pipe(struct iov_iter *from, |
1383 | struct pipe_inode_info *pipe, |
1384 | unsigned flags) |
1385 | { |
1386 | struct pipe_buffer buf = { |
1387 | .ops = &user_page_pipe_buf_ops, |
1388 | .flags = flags |
1389 | }; |
1390 | size_t total = 0; |
1391 | int ret = 0; |
1392 | |
1393 | while (iov_iter_count(i: from)) { |
1394 | struct page *pages[16]; |
1395 | ssize_t left; |
1396 | size_t start; |
1397 | int i, n; |
1398 | |
1399 | left = iov_iter_get_pages2(i: from, pages, maxsize: ~0UL, maxpages: 16, start: &start); |
1400 | if (left <= 0) { |
1401 | ret = left; |
1402 | break; |
1403 | } |
1404 | |
1405 | n = DIV_ROUND_UP(left + start, PAGE_SIZE); |
1406 | for (i = 0; i < n; i++) { |
1407 | int size = min_t(int, left, PAGE_SIZE - start); |
1408 | |
1409 | buf.page = pages[i]; |
1410 | buf.offset = start; |
1411 | buf.len = size; |
1412 | ret = add_to_pipe(pipe, &buf); |
1413 | if (unlikely(ret < 0)) { |
1414 | iov_iter_revert(i: from, bytes: left); |
1415 | // this one got dropped by add_to_pipe() |
1416 | while (++i < n) |
1417 | put_page(page: pages[i]); |
1418 | goto out; |
1419 | } |
1420 | total += ret; |
1421 | left -= size; |
1422 | start = 0; |
1423 | } |
1424 | } |
1425 | out: |
1426 | return total ? total : ret; |
1427 | } |
1428 | |
1429 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1430 | struct splice_desc *sd) |
1431 | { |
1432 | int n = copy_page_to_iter(page: buf->page, offset: buf->offset, bytes: sd->len, i: sd->u.data); |
1433 | return n == sd->len ? n : -EFAULT; |
1434 | } |
1435 | |
1436 | /* |
1437 | * For lack of a better implementation, implement vmsplice() to userspace |
1438 | * as a simple copy of the pipes pages to the user iov. |
1439 | */ |
1440 | static long vmsplice_to_user(struct file *file, struct iov_iter *iter, |
1441 | unsigned int flags) |
1442 | { |
1443 | struct pipe_inode_info *pipe = get_pipe_info(file, for_splice: true); |
1444 | struct splice_desc sd = { |
1445 | .total_len = iov_iter_count(i: iter), |
1446 | .flags = flags, |
1447 | .u.data = iter |
1448 | }; |
1449 | long ret = 0; |
1450 | |
1451 | if (!pipe) |
1452 | return -EBADF; |
1453 | |
1454 | pipe_clear_nowait(file); |
1455 | |
1456 | if (sd.total_len) { |
1457 | pipe_lock(pipe); |
1458 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); |
1459 | pipe_unlock(pipe); |
1460 | } |
1461 | |
1462 | if (ret > 0) |
1463 | fsnotify_access(file); |
1464 | |
1465 | return ret; |
1466 | } |
1467 | |
1468 | /* |
1469 | * vmsplice splices a user address range into a pipe. It can be thought of |
1470 | * as splice-from-memory, where the regular splice is splice-from-file (or |
1471 | * to file). In both cases the output is a pipe, naturally. |
1472 | */ |
1473 | static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter, |
1474 | unsigned int flags) |
1475 | { |
1476 | struct pipe_inode_info *pipe; |
1477 | long ret = 0; |
1478 | unsigned buf_flag = 0; |
1479 | |
1480 | if (flags & SPLICE_F_GIFT) |
1481 | buf_flag = PIPE_BUF_FLAG_GIFT; |
1482 | |
1483 | pipe = get_pipe_info(file, for_splice: true); |
1484 | if (!pipe) |
1485 | return -EBADF; |
1486 | |
1487 | pipe_clear_nowait(file); |
1488 | |
1489 | pipe_lock(pipe); |
1490 | ret = wait_for_space(pipe, flags); |
1491 | if (!ret) |
1492 | ret = iter_to_pipe(from: iter, pipe, flags: buf_flag); |
1493 | pipe_unlock(pipe); |
1494 | if (ret > 0) { |
1495 | wakeup_pipe_readers(pipe); |
1496 | fsnotify_modify(file); |
1497 | } |
1498 | return ret; |
1499 | } |
1500 | |
1501 | static int vmsplice_type(struct fd f, int *type) |
1502 | { |
1503 | if (!f.file) |
1504 | return -EBADF; |
1505 | if (f.file->f_mode & FMODE_WRITE) { |
1506 | *type = ITER_SOURCE; |
1507 | } else if (f.file->f_mode & FMODE_READ) { |
1508 | *type = ITER_DEST; |
1509 | } else { |
1510 | fdput(fd: f); |
1511 | return -EBADF; |
1512 | } |
1513 | return 0; |
1514 | } |
1515 | |
1516 | /* |
1517 | * Note that vmsplice only really supports true splicing _from_ user memory |
1518 | * to a pipe, not the other way around. Splicing from user memory is a simple |
1519 | * operation that can be supported without any funky alignment restrictions |
1520 | * or nasty vm tricks. We simply map in the user memory and fill them into |
1521 | * a pipe. The reverse isn't quite as easy, though. There are two possible |
1522 | * solutions for that: |
1523 | * |
1524 | * - memcpy() the data internally, at which point we might as well just |
1525 | * do a regular read() on the buffer anyway. |
1526 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it |
1527 | * has restriction limitations on both ends of the pipe). |
1528 | * |
1529 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). |
1530 | * |
1531 | */ |
1532 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, uiov, |
1533 | unsigned long, nr_segs, unsigned int, flags) |
1534 | { |
1535 | struct iovec iovstack[UIO_FASTIOV]; |
1536 | struct iovec *iov = iovstack; |
1537 | struct iov_iter iter; |
1538 | ssize_t error; |
1539 | struct fd f; |
1540 | int type; |
1541 | |
1542 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1543 | return -EINVAL; |
1544 | |
1545 | f = fdget(fd); |
1546 | error = vmsplice_type(f, type: &type); |
1547 | if (error) |
1548 | return error; |
1549 | |
1550 | error = import_iovec(type, uvec: uiov, nr_segs, |
1551 | ARRAY_SIZE(iovstack), iovp: &iov, i: &iter); |
1552 | if (error < 0) |
1553 | goto out_fdput; |
1554 | |
1555 | if (!iov_iter_count(i: &iter)) |
1556 | error = 0; |
1557 | else if (type == ITER_SOURCE) |
1558 | error = vmsplice_to_pipe(file: f.file, iter: &iter, flags); |
1559 | else |
1560 | error = vmsplice_to_user(file: f.file, iter: &iter, flags); |
1561 | |
1562 | kfree(objp: iov); |
1563 | out_fdput: |
1564 | fdput(fd: f); |
1565 | return error; |
1566 | } |
1567 | |
1568 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1569 | int, fd_out, loff_t __user *, off_out, |
1570 | size_t, len, unsigned int, flags) |
1571 | { |
1572 | struct fd in, out; |
1573 | long error; |
1574 | |
1575 | if (unlikely(!len)) |
1576 | return 0; |
1577 | |
1578 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1579 | return -EINVAL; |
1580 | |
1581 | error = -EBADF; |
1582 | in = fdget(fd: fd_in); |
1583 | if (in.file) { |
1584 | out = fdget(fd: fd_out); |
1585 | if (out.file) { |
1586 | error = __do_splice(in: in.file, off_in, out: out.file, off_out, |
1587 | len, flags); |
1588 | fdput(fd: out); |
1589 | } |
1590 | fdput(fd: in); |
1591 | } |
1592 | return error; |
1593 | } |
1594 | |
1595 | /* |
1596 | * Make sure there's data to read. Wait for input if we can, otherwise |
1597 | * return an appropriate error. |
1598 | */ |
1599 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1600 | { |
1601 | int ret; |
1602 | |
1603 | /* |
1604 | * Check the pipe occupancy without the inode lock first. This function |
1605 | * is speculative anyways, so missing one is ok. |
1606 | */ |
1607 | if (!pipe_empty(head: pipe->head, tail: pipe->tail)) |
1608 | return 0; |
1609 | |
1610 | ret = 0; |
1611 | pipe_lock(pipe); |
1612 | |
1613 | while (pipe_empty(head: pipe->head, tail: pipe->tail)) { |
1614 | if (signal_pending(current)) { |
1615 | ret = -ERESTARTSYS; |
1616 | break; |
1617 | } |
1618 | if (!pipe->writers) |
1619 | break; |
1620 | if (flags & SPLICE_F_NONBLOCK) { |
1621 | ret = -EAGAIN; |
1622 | break; |
1623 | } |
1624 | pipe_wait_readable(pipe); |
1625 | } |
1626 | |
1627 | pipe_unlock(pipe); |
1628 | return ret; |
1629 | } |
1630 | |
1631 | /* |
1632 | * Make sure there's writeable room. Wait for room if we can, otherwise |
1633 | * return an appropriate error. |
1634 | */ |
1635 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
1636 | { |
1637 | int ret; |
1638 | |
1639 | /* |
1640 | * Check pipe occupancy without the inode lock first. This function |
1641 | * is speculative anyways, so missing one is ok. |
1642 | */ |
1643 | if (!pipe_full(head: pipe->head, tail: pipe->tail, limit: pipe->max_usage)) |
1644 | return 0; |
1645 | |
1646 | ret = 0; |
1647 | pipe_lock(pipe); |
1648 | |
1649 | while (pipe_full(head: pipe->head, tail: pipe->tail, limit: pipe->max_usage)) { |
1650 | if (!pipe->readers) { |
1651 | send_sig(SIGPIPE, current, 0); |
1652 | ret = -EPIPE; |
1653 | break; |
1654 | } |
1655 | if (flags & SPLICE_F_NONBLOCK) { |
1656 | ret = -EAGAIN; |
1657 | break; |
1658 | } |
1659 | if (signal_pending(current)) { |
1660 | ret = -ERESTARTSYS; |
1661 | break; |
1662 | } |
1663 | pipe_wait_writable(pipe); |
1664 | } |
1665 | |
1666 | pipe_unlock(pipe); |
1667 | return ret; |
1668 | } |
1669 | |
1670 | /* |
1671 | * Splice contents of ipipe to opipe. |
1672 | */ |
1673 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1674 | struct pipe_inode_info *opipe, |
1675 | size_t len, unsigned int flags) |
1676 | { |
1677 | struct pipe_buffer *ibuf, *obuf; |
1678 | unsigned int i_head, o_head; |
1679 | unsigned int i_tail, o_tail; |
1680 | unsigned int i_mask, o_mask; |
1681 | int ret = 0; |
1682 | bool input_wakeup = false; |
1683 | |
1684 | |
1685 | retry: |
1686 | ret = ipipe_prep(pipe: ipipe, flags); |
1687 | if (ret) |
1688 | return ret; |
1689 | |
1690 | ret = opipe_prep(pipe: opipe, flags); |
1691 | if (ret) |
1692 | return ret; |
1693 | |
1694 | /* |
1695 | * Potential ABBA deadlock, work around it by ordering lock |
1696 | * grabbing by pipe info address. Otherwise two different processes |
1697 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1698 | */ |
1699 | pipe_double_lock(ipipe, opipe); |
1700 | |
1701 | i_tail = ipipe->tail; |
1702 | i_mask = ipipe->ring_size - 1; |
1703 | o_head = opipe->head; |
1704 | o_mask = opipe->ring_size - 1; |
1705 | |
1706 | do { |
1707 | size_t o_len; |
1708 | |
1709 | if (!opipe->readers) { |
1710 | send_sig(SIGPIPE, current, 0); |
1711 | if (!ret) |
1712 | ret = -EPIPE; |
1713 | break; |
1714 | } |
1715 | |
1716 | i_head = ipipe->head; |
1717 | o_tail = opipe->tail; |
1718 | |
1719 | if (pipe_empty(head: i_head, tail: i_tail) && !ipipe->writers) |
1720 | break; |
1721 | |
1722 | /* |
1723 | * Cannot make any progress, because either the input |
1724 | * pipe is empty or the output pipe is full. |
1725 | */ |
1726 | if (pipe_empty(head: i_head, tail: i_tail) || |
1727 | pipe_full(head: o_head, tail: o_tail, limit: opipe->max_usage)) { |
1728 | /* Already processed some buffers, break */ |
1729 | if (ret) |
1730 | break; |
1731 | |
1732 | if (flags & SPLICE_F_NONBLOCK) { |
1733 | ret = -EAGAIN; |
1734 | break; |
1735 | } |
1736 | |
1737 | /* |
1738 | * We raced with another reader/writer and haven't |
1739 | * managed to process any buffers. A zero return |
1740 | * value means EOF, so retry instead. |
1741 | */ |
1742 | pipe_unlock(ipipe); |
1743 | pipe_unlock(opipe); |
1744 | goto retry; |
1745 | } |
1746 | |
1747 | ibuf = &ipipe->bufs[i_tail & i_mask]; |
1748 | obuf = &opipe->bufs[o_head & o_mask]; |
1749 | |
1750 | if (len >= ibuf->len) { |
1751 | /* |
1752 | * Simply move the whole buffer from ipipe to opipe |
1753 | */ |
1754 | *obuf = *ibuf; |
1755 | ibuf->ops = NULL; |
1756 | i_tail++; |
1757 | ipipe->tail = i_tail; |
1758 | input_wakeup = true; |
1759 | o_len = obuf->len; |
1760 | o_head++; |
1761 | opipe->head = o_head; |
1762 | } else { |
1763 | /* |
1764 | * Get a reference to this pipe buffer, |
1765 | * so we can copy the contents over. |
1766 | */ |
1767 | if (!pipe_buf_get(pipe: ipipe, buf: ibuf)) { |
1768 | if (ret == 0) |
1769 | ret = -EFAULT; |
1770 | break; |
1771 | } |
1772 | *obuf = *ibuf; |
1773 | |
1774 | /* |
1775 | * Don't inherit the gift and merge flags, we need to |
1776 | * prevent multiple steals of this page. |
1777 | */ |
1778 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1779 | obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
1780 | |
1781 | obuf->len = len; |
1782 | ibuf->offset += len; |
1783 | ibuf->len -= len; |
1784 | o_len = len; |
1785 | o_head++; |
1786 | opipe->head = o_head; |
1787 | } |
1788 | ret += o_len; |
1789 | len -= o_len; |
1790 | } while (len); |
1791 | |
1792 | pipe_unlock(ipipe); |
1793 | pipe_unlock(opipe); |
1794 | |
1795 | /* |
1796 | * If we put data in the output pipe, wakeup any potential readers. |
1797 | */ |
1798 | if (ret > 0) |
1799 | wakeup_pipe_readers(pipe: opipe); |
1800 | |
1801 | if (input_wakeup) |
1802 | wakeup_pipe_writers(pipe: ipipe); |
1803 | |
1804 | return ret; |
1805 | } |
1806 | |
1807 | /* |
1808 | * Link contents of ipipe to opipe. |
1809 | */ |
1810 | static int link_pipe(struct pipe_inode_info *ipipe, |
1811 | struct pipe_inode_info *opipe, |
1812 | size_t len, unsigned int flags) |
1813 | { |
1814 | struct pipe_buffer *ibuf, *obuf; |
1815 | unsigned int i_head, o_head; |
1816 | unsigned int i_tail, o_tail; |
1817 | unsigned int i_mask, o_mask; |
1818 | int ret = 0; |
1819 | |
1820 | /* |
1821 | * Potential ABBA deadlock, work around it by ordering lock |
1822 | * grabbing by pipe info address. Otherwise two different processes |
1823 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1824 | */ |
1825 | pipe_double_lock(ipipe, opipe); |
1826 | |
1827 | i_tail = ipipe->tail; |
1828 | i_mask = ipipe->ring_size - 1; |
1829 | o_head = opipe->head; |
1830 | o_mask = opipe->ring_size - 1; |
1831 | |
1832 | do { |
1833 | if (!opipe->readers) { |
1834 | send_sig(SIGPIPE, current, 0); |
1835 | if (!ret) |
1836 | ret = -EPIPE; |
1837 | break; |
1838 | } |
1839 | |
1840 | i_head = ipipe->head; |
1841 | o_tail = opipe->tail; |
1842 | |
1843 | /* |
1844 | * If we have iterated all input buffers or run out of |
1845 | * output room, break. |
1846 | */ |
1847 | if (pipe_empty(head: i_head, tail: i_tail) || |
1848 | pipe_full(head: o_head, tail: o_tail, limit: opipe->max_usage)) |
1849 | break; |
1850 | |
1851 | ibuf = &ipipe->bufs[i_tail & i_mask]; |
1852 | obuf = &opipe->bufs[o_head & o_mask]; |
1853 | |
1854 | /* |
1855 | * Get a reference to this pipe buffer, |
1856 | * so we can copy the contents over. |
1857 | */ |
1858 | if (!pipe_buf_get(pipe: ipipe, buf: ibuf)) { |
1859 | if (ret == 0) |
1860 | ret = -EFAULT; |
1861 | break; |
1862 | } |
1863 | |
1864 | *obuf = *ibuf; |
1865 | |
1866 | /* |
1867 | * Don't inherit the gift and merge flag, we need to prevent |
1868 | * multiple steals of this page. |
1869 | */ |
1870 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
1871 | obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
1872 | |
1873 | if (obuf->len > len) |
1874 | obuf->len = len; |
1875 | ret += obuf->len; |
1876 | len -= obuf->len; |
1877 | |
1878 | o_head++; |
1879 | opipe->head = o_head; |
1880 | i_tail++; |
1881 | } while (len); |
1882 | |
1883 | pipe_unlock(ipipe); |
1884 | pipe_unlock(opipe); |
1885 | |
1886 | /* |
1887 | * If we put data in the output pipe, wakeup any potential readers. |
1888 | */ |
1889 | if (ret > 0) |
1890 | wakeup_pipe_readers(pipe: opipe); |
1891 | |
1892 | return ret; |
1893 | } |
1894 | |
1895 | /* |
1896 | * This is a tee(1) implementation that works on pipes. It doesn't copy |
1897 | * any data, it simply references the 'in' pages on the 'out' pipe. |
1898 | * The 'flags' used are the SPLICE_F_* variants, currently the only |
1899 | * applicable one is SPLICE_F_NONBLOCK. |
1900 | */ |
1901 | long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags) |
1902 | { |
1903 | struct pipe_inode_info *ipipe = get_pipe_info(file: in, for_splice: true); |
1904 | struct pipe_inode_info *opipe = get_pipe_info(file: out, for_splice: true); |
1905 | int ret = -EINVAL; |
1906 | |
1907 | if (unlikely(!(in->f_mode & FMODE_READ) || |
1908 | !(out->f_mode & FMODE_WRITE))) |
1909 | return -EBADF; |
1910 | |
1911 | /* |
1912 | * Duplicate the contents of ipipe to opipe without actually |
1913 | * copying the data. |
1914 | */ |
1915 | if (ipipe && opipe && ipipe != opipe) { |
1916 | if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
1917 | flags |= SPLICE_F_NONBLOCK; |
1918 | |
1919 | /* |
1920 | * Keep going, unless we encounter an error. The ipipe/opipe |
1921 | * ordering doesn't really matter. |
1922 | */ |
1923 | ret = ipipe_prep(pipe: ipipe, flags); |
1924 | if (!ret) { |
1925 | ret = opipe_prep(pipe: opipe, flags); |
1926 | if (!ret) |
1927 | ret = link_pipe(ipipe, opipe, len, flags); |
1928 | } |
1929 | } |
1930 | |
1931 | if (ret > 0) { |
1932 | fsnotify_access(file: in); |
1933 | fsnotify_modify(file: out); |
1934 | } |
1935 | |
1936 | return ret; |
1937 | } |
1938 | |
1939 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
1940 | { |
1941 | struct fd in, out; |
1942 | int error; |
1943 | |
1944 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1945 | return -EINVAL; |
1946 | |
1947 | if (unlikely(!len)) |
1948 | return 0; |
1949 | |
1950 | error = -EBADF; |
1951 | in = fdget(fd: fdin); |
1952 | if (in.file) { |
1953 | out = fdget(fd: fdout); |
1954 | if (out.file) { |
1955 | error = do_tee(in: in.file, out: out.file, len, flags); |
1956 | fdput(fd: out); |
1957 | } |
1958 | fdput(fd: in); |
1959 | } |
1960 | |
1961 | return error; |
1962 | } |
1963 | |