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Commit | Line | Data |
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1 | /* | |
2 | * linux/fs/pipe.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | #include <linux/mm.h> | |
8 | #include <linux/file.h> | |
9 | #include <linux/poll.h> | |
10 | #include <linux/slab.h> | |
11 | #include <linux/module.h> | |
12 | #include <linux/init.h> | |
13 | #include <linux/fs.h> | |
14 | #include <linux/log2.h> | |
15 | #include <linux/mount.h> | |
16 | #include <linux/magic.h> | |
17 | #include <linux/pipe_fs_i.h> | |
18 | #include <linux/uio.h> | |
19 | #include <linux/highmem.h> | |
20 | #include <linux/pagemap.h> | |
21 | #include <linux/audit.h> | |
22 | #include <linux/syscalls.h> | |
23 | #include <linux/fcntl.h> | |
24 | ||
25 | #include <asm/uaccess.h> | |
26 | #include <asm/ioctls.h> | |
27 | ||
28 | #include "internal.h" | |
29 | ||
30 | /* | |
31 | * The max size that a non-root user is allowed to grow the pipe. Can | |
32 | * be set by root in /proc/sys/fs/pipe-max-size | |
33 | */ | |
34 | unsigned int pipe_max_size = 1048576; | |
35 | ||
36 | /* | |
37 | * Minimum pipe size, as required by POSIX | |
38 | */ | |
39 | unsigned int pipe_min_size = PAGE_SIZE; | |
40 | ||
41 | /* | |
42 | * We use a start+len construction, which provides full use of the | |
43 | * allocated memory. | |
44 | * -- Florian Coosmann (FGC) | |
45 | * | |
46 | * Reads with count = 0 should always return 0. | |
47 | * -- Julian Bradfield 1999-06-07. | |
48 | * | |
49 | * FIFOs and Pipes now generate SIGIO for both readers and writers. | |
50 | * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16 | |
51 | * | |
52 | * pipe_read & write cleanup | |
53 | * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09 | |
54 | */ | |
55 | ||
56 | static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass) | |
57 | { | |
58 | if (pipe->inode) | |
59 | mutex_lock_nested(&pipe->mutex, subclass); | |
60 | } | |
61 | ||
62 | void pipe_lock(struct pipe_inode_info *pipe) | |
63 | { | |
64 | /* | |
65 | * pipe_lock() nests non-pipe inode locks (for writing to a file) | |
66 | */ | |
67 | pipe_lock_nested(pipe, I_MUTEX_PARENT); | |
68 | } | |
69 | EXPORT_SYMBOL(pipe_lock); | |
70 | ||
71 | void pipe_unlock(struct pipe_inode_info *pipe) | |
72 | { | |
73 | if (pipe->inode) | |
74 | mutex_unlock(&pipe->mutex); | |
75 | } | |
76 | EXPORT_SYMBOL(pipe_unlock); | |
77 | ||
78 | static inline void __pipe_lock(struct pipe_inode_info *pipe) | |
79 | { | |
80 | mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT); | |
81 | } | |
82 | ||
83 | static inline void __pipe_unlock(struct pipe_inode_info *pipe) | |
84 | { | |
85 | mutex_unlock(&pipe->mutex); | |
86 | } | |
87 | ||
88 | void pipe_double_lock(struct pipe_inode_info *pipe1, | |
89 | struct pipe_inode_info *pipe2) | |
90 | { | |
91 | BUG_ON(pipe1 == pipe2); | |
92 | ||
93 | if (pipe1 < pipe2) { | |
94 | pipe_lock_nested(pipe1, I_MUTEX_PARENT); | |
95 | pipe_lock_nested(pipe2, I_MUTEX_CHILD); | |
96 | } else { | |
97 | pipe_lock_nested(pipe2, I_MUTEX_PARENT); | |
98 | pipe_lock_nested(pipe1, I_MUTEX_CHILD); | |
99 | } | |
100 | } | |
101 | ||
102 | /* Drop the inode semaphore and wait for a pipe event, atomically */ | |
103 | void pipe_wait(struct pipe_inode_info *pipe) | |
104 | { | |
105 | DEFINE_WAIT(wait); | |
106 | ||
107 | /* | |
108 | * Pipes are system-local resources, so sleeping on them | |
109 | * is considered a noninteractive wait: | |
110 | */ | |
111 | prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE); | |
112 | pipe_unlock(pipe); | |
113 | schedule(); | |
114 | finish_wait(&pipe->wait, &wait); | |
115 | pipe_lock(pipe); | |
116 | } | |
117 | ||
118 | static int | |
119 | pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len, | |
120 | int atomic) | |
121 | { | |
122 | unsigned long copy; | |
123 | ||
124 | while (len > 0) { | |
125 | while (!iov->iov_len) | |
126 | iov++; | |
127 | copy = min_t(unsigned long, len, iov->iov_len); | |
128 | ||
129 | if (atomic) { | |
130 | if (__copy_from_user_inatomic(to, iov->iov_base, copy)) | |
131 | return -EFAULT; | |
132 | } else { | |
133 | if (copy_from_user(to, iov->iov_base, copy)) | |
134 | return -EFAULT; | |
135 | } | |
136 | to += copy; | |
137 | len -= copy; | |
138 | iov->iov_base += copy; | |
139 | iov->iov_len -= copy; | |
140 | } | |
141 | return 0; | |
142 | } | |
143 | ||
144 | static int | |
145 | pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len, | |
146 | int atomic) | |
147 | { | |
148 | unsigned long copy; | |
149 | ||
150 | while (len > 0) { | |
151 | while (!iov->iov_len) | |
152 | iov++; | |
153 | copy = min_t(unsigned long, len, iov->iov_len); | |
154 | ||
155 | if (atomic) { | |
156 | if (__copy_to_user_inatomic(iov->iov_base, from, copy)) | |
157 | return -EFAULT; | |
158 | } else { | |
159 | if (copy_to_user(iov->iov_base, from, copy)) | |
160 | return -EFAULT; | |
161 | } | |
162 | from += copy; | |
163 | len -= copy; | |
164 | iov->iov_base += copy; | |
165 | iov->iov_len -= copy; | |
166 | } | |
167 | return 0; | |
168 | } | |
169 | ||
170 | /* | |
171 | * Attempt to pre-fault in the user memory, so we can use atomic copies. | |
172 | * Returns the number of bytes not faulted in. | |
173 | */ | |
174 | static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len) | |
175 | { | |
176 | while (!iov->iov_len) | |
177 | iov++; | |
178 | ||
179 | while (len > 0) { | |
180 | unsigned long this_len; | |
181 | ||
182 | this_len = min_t(unsigned long, len, iov->iov_len); | |
183 | if (fault_in_pages_writeable(iov->iov_base, this_len)) | |
184 | break; | |
185 | ||
186 | len -= this_len; | |
187 | iov++; | |
188 | } | |
189 | ||
190 | return len; | |
191 | } | |
192 | ||
193 | /* | |
194 | * Pre-fault in the user memory, so we can use atomic copies. | |
195 | */ | |
196 | static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len) | |
197 | { | |
198 | while (!iov->iov_len) | |
199 | iov++; | |
200 | ||
201 | while (len > 0) { | |
202 | unsigned long this_len; | |
203 | ||
204 | this_len = min_t(unsigned long, len, iov->iov_len); | |
205 | fault_in_pages_readable(iov->iov_base, this_len); | |
206 | len -= this_len; | |
207 | iov++; | |
208 | } | |
209 | } | |
210 | ||
211 | static void anon_pipe_buf_release(struct pipe_inode_info *pipe, | |
212 | struct pipe_buffer *buf) | |
213 | { | |
214 | struct page *page = buf->page; | |
215 | ||
216 | /* | |
217 | * If nobody else uses this page, and we don't already have a | |
218 | * temporary page, let's keep track of it as a one-deep | |
219 | * allocation cache. (Otherwise just release our reference to it) | |
220 | */ | |
221 | if (page_count(page) == 1 && !pipe->tmp_page) | |
222 | pipe->tmp_page = page; | |
223 | else | |
224 | page_cache_release(page); | |
225 | } | |
226 | ||
227 | /** | |
228 | * generic_pipe_buf_map - virtually map a pipe buffer | |
229 | * @pipe: the pipe that the buffer belongs to | |
230 | * @buf: the buffer that should be mapped | |
231 | * @atomic: whether to use an atomic map | |
232 | * | |
233 | * Description: | |
234 | * This function returns a kernel virtual address mapping for the | |
235 | * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided | |
236 | * and the caller has to be careful not to fault before calling | |
237 | * the unmap function. | |
238 | * | |
239 | * Note that this function calls kmap_atomic() if @atomic != 0. | |
240 | */ | |
241 | void *generic_pipe_buf_map(struct pipe_inode_info *pipe, | |
242 | struct pipe_buffer *buf, int atomic) | |
243 | { | |
244 | if (atomic) { | |
245 | buf->flags |= PIPE_BUF_FLAG_ATOMIC; | |
246 | return kmap_atomic(buf->page); | |
247 | } | |
248 | ||
249 | return kmap(buf->page); | |
250 | } | |
251 | EXPORT_SYMBOL(generic_pipe_buf_map); | |
252 | ||
253 | /** | |
254 | * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer | |
255 | * @pipe: the pipe that the buffer belongs to | |
256 | * @buf: the buffer that should be unmapped | |
257 | * @map_data: the data that the mapping function returned | |
258 | * | |
259 | * Description: | |
260 | * This function undoes the mapping that ->map() provided. | |
261 | */ | |
262 | void generic_pipe_buf_unmap(struct pipe_inode_info *pipe, | |
263 | struct pipe_buffer *buf, void *map_data) | |
264 | { | |
265 | if (buf->flags & PIPE_BUF_FLAG_ATOMIC) { | |
266 | buf->flags &= ~PIPE_BUF_FLAG_ATOMIC; | |
267 | kunmap_atomic(map_data); | |
268 | } else | |
269 | kunmap(buf->page); | |
270 | } | |
271 | EXPORT_SYMBOL(generic_pipe_buf_unmap); | |
272 | ||
273 | /** | |
274 | * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer | |
275 | * @pipe: the pipe that the buffer belongs to | |
276 | * @buf: the buffer to attempt to steal | |
277 | * | |
278 | * Description: | |
279 | * This function attempts to steal the &struct page attached to | |
280 | * @buf. If successful, this function returns 0 and returns with | |
281 | * the page locked. The caller may then reuse the page for whatever | |
282 | * he wishes; the typical use is insertion into a different file | |
283 | * page cache. | |
284 | */ | |
285 | int generic_pipe_buf_steal(struct pipe_inode_info *pipe, | |
286 | struct pipe_buffer *buf) | |
287 | { | |
288 | struct page *page = buf->page; | |
289 | ||
290 | /* | |
291 | * A reference of one is golden, that means that the owner of this | |
292 | * page is the only one holding a reference to it. lock the page | |
293 | * and return OK. | |
294 | */ | |
295 | if (page_count(page) == 1) { | |
296 | lock_page(page); | |
297 | return 0; | |
298 | } | |
299 | ||
300 | return 1; | |
301 | } | |
302 | EXPORT_SYMBOL(generic_pipe_buf_steal); | |
303 | ||
304 | /** | |
305 | * generic_pipe_buf_get - get a reference to a &struct pipe_buffer | |
306 | * @pipe: the pipe that the buffer belongs to | |
307 | * @buf: the buffer to get a reference to | |
308 | * | |
309 | * Description: | |
310 | * This function grabs an extra reference to @buf. It's used in | |
311 | * in the tee() system call, when we duplicate the buffers in one | |
312 | * pipe into another. | |
313 | */ | |
314 | void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) | |
315 | { | |
316 | page_cache_get(buf->page); | |
317 | } | |
318 | EXPORT_SYMBOL(generic_pipe_buf_get); | |
319 | ||
320 | /** | |
321 | * generic_pipe_buf_confirm - verify contents of the pipe buffer | |
322 | * @info: the pipe that the buffer belongs to | |
323 | * @buf: the buffer to confirm | |
324 | * | |
325 | * Description: | |
326 | * This function does nothing, because the generic pipe code uses | |
327 | * pages that are always good when inserted into the pipe. | |
328 | */ | |
329 | int generic_pipe_buf_confirm(struct pipe_inode_info *info, | |
330 | struct pipe_buffer *buf) | |
331 | { | |
332 | return 0; | |
333 | } | |
334 | EXPORT_SYMBOL(generic_pipe_buf_confirm); | |
335 | ||
336 | /** | |
337 | * generic_pipe_buf_release - put a reference to a &struct pipe_buffer | |
338 | * @pipe: the pipe that the buffer belongs to | |
339 | * @buf: the buffer to put a reference to | |
340 | * | |
341 | * Description: | |
342 | * This function releases a reference to @buf. | |
343 | */ | |
344 | void generic_pipe_buf_release(struct pipe_inode_info *pipe, | |
345 | struct pipe_buffer *buf) | |
346 | { | |
347 | page_cache_release(buf->page); | |
348 | } | |
349 | EXPORT_SYMBOL(generic_pipe_buf_release); | |
350 | ||
351 | static const struct pipe_buf_operations anon_pipe_buf_ops = { | |
352 | .can_merge = 1, | |
353 | .map = generic_pipe_buf_map, | |
354 | .unmap = generic_pipe_buf_unmap, | |
355 | .confirm = generic_pipe_buf_confirm, | |
356 | .release = anon_pipe_buf_release, | |
357 | .steal = generic_pipe_buf_steal, | |
358 | .get = generic_pipe_buf_get, | |
359 | }; | |
360 | ||
361 | static const struct pipe_buf_operations packet_pipe_buf_ops = { | |
362 | .can_merge = 0, | |
363 | .map = generic_pipe_buf_map, | |
364 | .unmap = generic_pipe_buf_unmap, | |
365 | .confirm = generic_pipe_buf_confirm, | |
366 | .release = anon_pipe_buf_release, | |
367 | .steal = generic_pipe_buf_steal, | |
368 | .get = generic_pipe_buf_get, | |
369 | }; | |
370 | ||
371 | static ssize_t | |
372 | pipe_read(struct kiocb *iocb, const struct iovec *_iov, | |
373 | unsigned long nr_segs, loff_t pos) | |
374 | { | |
375 | struct file *filp = iocb->ki_filp; | |
376 | struct pipe_inode_info *pipe = filp->private_data; | |
377 | int do_wakeup; | |
378 | ssize_t ret; | |
379 | struct iovec *iov = (struct iovec *)_iov; | |
380 | size_t total_len; | |
381 | ||
382 | total_len = iov_length(iov, nr_segs); | |
383 | /* Null read succeeds. */ | |
384 | if (unlikely(total_len == 0)) | |
385 | return 0; | |
386 | ||
387 | do_wakeup = 0; | |
388 | ret = 0; | |
389 | __pipe_lock(pipe); | |
390 | for (;;) { | |
391 | int bufs = pipe->nrbufs; | |
392 | if (bufs) { | |
393 | int curbuf = pipe->curbuf; | |
394 | struct pipe_buffer *buf = pipe->bufs + curbuf; | |
395 | const struct pipe_buf_operations *ops = buf->ops; | |
396 | void *addr; | |
397 | size_t chars = buf->len; | |
398 | int error, atomic; | |
399 | ||
400 | if (chars > total_len) | |
401 | chars = total_len; | |
402 | ||
403 | error = ops->confirm(pipe, buf); | |
404 | if (error) { | |
405 | if (!ret) | |
406 | ret = error; | |
407 | break; | |
408 | } | |
409 | ||
410 | atomic = !iov_fault_in_pages_write(iov, chars); | |
411 | redo: | |
412 | addr = ops->map(pipe, buf, atomic); | |
413 | error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic); | |
414 | ops->unmap(pipe, buf, addr); | |
415 | if (unlikely(error)) { | |
416 | /* | |
417 | * Just retry with the slow path if we failed. | |
418 | */ | |
419 | if (atomic) { | |
420 | atomic = 0; | |
421 | goto redo; | |
422 | } | |
423 | if (!ret) | |
424 | ret = error; | |
425 | break; | |
426 | } | |
427 | ret += chars; | |
428 | buf->offset += chars; | |
429 | buf->len -= chars; | |
430 | ||
431 | /* Was it a packet buffer? Clean up and exit */ | |
432 | if (buf->flags & PIPE_BUF_FLAG_PACKET) { | |
433 | total_len = chars; | |
434 | buf->len = 0; | |
435 | } | |
436 | ||
437 | if (!buf->len) { | |
438 | buf->ops = NULL; | |
439 | ops->release(pipe, buf); | |
440 | curbuf = (curbuf + 1) & (pipe->buffers - 1); | |
441 | pipe->curbuf = curbuf; | |
442 | pipe->nrbufs = --bufs; | |
443 | do_wakeup = 1; | |
444 | } | |
445 | total_len -= chars; | |
446 | if (!total_len) | |
447 | break; /* common path: read succeeded */ | |
448 | } | |
449 | if (bufs) /* More to do? */ | |
450 | continue; | |
451 | if (!pipe->writers) | |
452 | break; | |
453 | if (!pipe->waiting_writers) { | |
454 | /* syscall merging: Usually we must not sleep | |
455 | * if O_NONBLOCK is set, or if we got some data. | |
456 | * But if a writer sleeps in kernel space, then | |
457 | * we can wait for that data without violating POSIX. | |
458 | */ | |
459 | if (ret) | |
460 | break; | |
461 | if (filp->f_flags & O_NONBLOCK) { | |
462 | ret = -EAGAIN; | |
463 | break; | |
464 | } | |
465 | } | |
466 | if (signal_pending(current)) { | |
467 | if (!ret) | |
468 | ret = -ERESTARTSYS; | |
469 | break; | |
470 | } | |
471 | if (do_wakeup) { | |
472 | wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM); | |
473 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
474 | } | |
475 | pipe_wait(pipe); | |
476 | } | |
477 | __pipe_unlock(pipe); | |
478 | ||
479 | /* Signal writers asynchronously that there is more room. */ | |
480 | if (do_wakeup) { | |
481 | wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM); | |
482 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
483 | } | |
484 | if (ret > 0) | |
485 | file_accessed(filp); | |
486 | return ret; | |
487 | } | |
488 | ||
489 | static inline int is_packetized(struct file *file) | |
490 | { | |
491 | return (file->f_flags & O_DIRECT) != 0; | |
492 | } | |
493 | ||
494 | static ssize_t | |
495 | pipe_write(struct kiocb *iocb, const struct iovec *_iov, | |
496 | unsigned long nr_segs, loff_t ppos) | |
497 | { | |
498 | struct file *filp = iocb->ki_filp; | |
499 | struct pipe_inode_info *pipe = filp->private_data; | |
500 | ssize_t ret; | |
501 | int do_wakeup; | |
502 | struct iovec *iov = (struct iovec *)_iov; | |
503 | size_t total_len; | |
504 | ssize_t chars; | |
505 | ||
506 | total_len = iov_length(iov, nr_segs); | |
507 | /* Null write succeeds. */ | |
508 | if (unlikely(total_len == 0)) | |
509 | return 0; | |
510 | ||
511 | do_wakeup = 0; | |
512 | ret = 0; | |
513 | __pipe_lock(pipe); | |
514 | ||
515 | if (!pipe->readers) { | |
516 | send_sig(SIGPIPE, current, 0); | |
517 | ret = -EPIPE; | |
518 | goto out; | |
519 | } | |
520 | ||
521 | /* We try to merge small writes */ | |
522 | chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */ | |
523 | if (pipe->nrbufs && chars != 0) { | |
524 | int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) & | |
525 | (pipe->buffers - 1); | |
526 | struct pipe_buffer *buf = pipe->bufs + lastbuf; | |
527 | const struct pipe_buf_operations *ops = buf->ops; | |
528 | int offset = buf->offset + buf->len; | |
529 | ||
530 | if (ops->can_merge && offset + chars <= PAGE_SIZE) { | |
531 | int error, atomic = 1; | |
532 | void *addr; | |
533 | ||
534 | error = ops->confirm(pipe, buf); | |
535 | if (error) | |
536 | goto out; | |
537 | ||
538 | iov_fault_in_pages_read(iov, chars); | |
539 | redo1: | |
540 | addr = ops->map(pipe, buf, atomic); | |
541 | error = pipe_iov_copy_from_user(offset + addr, iov, | |
542 | chars, atomic); | |
543 | ops->unmap(pipe, buf, addr); | |
544 | ret = error; | |
545 | do_wakeup = 1; | |
546 | if (error) { | |
547 | if (atomic) { | |
548 | atomic = 0; | |
549 | goto redo1; | |
550 | } | |
551 | goto out; | |
552 | } | |
553 | buf->len += chars; | |
554 | total_len -= chars; | |
555 | ret = chars; | |
556 | if (!total_len) | |
557 | goto out; | |
558 | } | |
559 | } | |
560 | ||
561 | for (;;) { | |
562 | int bufs; | |
563 | ||
564 | if (!pipe->readers) { | |
565 | send_sig(SIGPIPE, current, 0); | |
566 | if (!ret) | |
567 | ret = -EPIPE; | |
568 | break; | |
569 | } | |
570 | bufs = pipe->nrbufs; | |
571 | if (bufs < pipe->buffers) { | |
572 | int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1); | |
573 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
574 | struct page *page = pipe->tmp_page; | |
575 | char *src; | |
576 | int error, atomic = 1; | |
577 | ||
578 | if (!page) { | |
579 | page = alloc_page(GFP_HIGHUSER); | |
580 | if (unlikely(!page)) { | |
581 | ret = ret ? : -ENOMEM; | |
582 | break; | |
583 | } | |
584 | pipe->tmp_page = page; | |
585 | } | |
586 | /* Always wake up, even if the copy fails. Otherwise | |
587 | * we lock up (O_NONBLOCK-)readers that sleep due to | |
588 | * syscall merging. | |
589 | * FIXME! Is this really true? | |
590 | */ | |
591 | do_wakeup = 1; | |
592 | chars = PAGE_SIZE; | |
593 | if (chars > total_len) | |
594 | chars = total_len; | |
595 | ||
596 | iov_fault_in_pages_read(iov, chars); | |
597 | redo2: | |
598 | if (atomic) | |
599 | src = kmap_atomic(page); | |
600 | else | |
601 | src = kmap(page); | |
602 | ||
603 | error = pipe_iov_copy_from_user(src, iov, chars, | |
604 | atomic); | |
605 | if (atomic) | |
606 | kunmap_atomic(src); | |
607 | else | |
608 | kunmap(page); | |
609 | ||
610 | if (unlikely(error)) { | |
611 | if (atomic) { | |
612 | atomic = 0; | |
613 | goto redo2; | |
614 | } | |
615 | if (!ret) | |
616 | ret = error; | |
617 | break; | |
618 | } | |
619 | ret += chars; | |
620 | ||
621 | /* Insert it into the buffer array */ | |
622 | buf->page = page; | |
623 | buf->ops = &anon_pipe_buf_ops; | |
624 | buf->offset = 0; | |
625 | buf->len = chars; | |
626 | buf->flags = 0; | |
627 | if (is_packetized(filp)) { | |
628 | buf->ops = &packet_pipe_buf_ops; | |
629 | buf->flags = PIPE_BUF_FLAG_PACKET; | |
630 | } | |
631 | pipe->nrbufs = ++bufs; | |
632 | pipe->tmp_page = NULL; | |
633 | ||
634 | total_len -= chars; | |
635 | if (!total_len) | |
636 | break; | |
637 | } | |
638 | if (bufs < pipe->buffers) | |
639 | continue; | |
640 | if (filp->f_flags & O_NONBLOCK) { | |
641 | if (!ret) | |
642 | ret = -EAGAIN; | |
643 | break; | |
644 | } | |
645 | if (signal_pending(current)) { | |
646 | if (!ret) | |
647 | ret = -ERESTARTSYS; | |
648 | break; | |
649 | } | |
650 | if (do_wakeup) { | |
651 | wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM); | |
652 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
653 | do_wakeup = 0; | |
654 | } | |
655 | pipe->waiting_writers++; | |
656 | pipe_wait(pipe); | |
657 | pipe->waiting_writers--; | |
658 | } | |
659 | out: | |
660 | __pipe_unlock(pipe); | |
661 | if (do_wakeup) { | |
662 | wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM); | |
663 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
664 | } | |
665 | if (ret > 0) { | |
666 | int err = file_update_time(filp); | |
667 | if (err) | |
668 | ret = err; | |
669 | } | |
670 | return ret; | |
671 | } | |
672 | ||
673 | static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
674 | { | |
675 | struct pipe_inode_info *pipe = filp->private_data; | |
676 | int count, buf, nrbufs; | |
677 | ||
678 | switch (cmd) { | |
679 | case FIONREAD: | |
680 | __pipe_lock(pipe); | |
681 | count = 0; | |
682 | buf = pipe->curbuf; | |
683 | nrbufs = pipe->nrbufs; | |
684 | while (--nrbufs >= 0) { | |
685 | count += pipe->bufs[buf].len; | |
686 | buf = (buf+1) & (pipe->buffers - 1); | |
687 | } | |
688 | __pipe_unlock(pipe); | |
689 | ||
690 | return put_user(count, (int __user *)arg); | |
691 | default: | |
692 | return -ENOIOCTLCMD; | |
693 | } | |
694 | } | |
695 | ||
696 | /* No kernel lock held - fine */ | |
697 | static unsigned int | |
698 | pipe_poll(struct file *filp, poll_table *wait) | |
699 | { | |
700 | unsigned int mask; | |
701 | struct pipe_inode_info *pipe = filp->private_data; | |
702 | int nrbufs; | |
703 | ||
704 | poll_wait(filp, &pipe->wait, wait); | |
705 | ||
706 | /* Reading only -- no need for acquiring the semaphore. */ | |
707 | nrbufs = pipe->nrbufs; | |
708 | mask = 0; | |
709 | if (filp->f_mode & FMODE_READ) { | |
710 | mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0; | |
711 | if (!pipe->writers && filp->f_version != pipe->w_counter) | |
712 | mask |= POLLHUP; | |
713 | } | |
714 | ||
715 | if (filp->f_mode & FMODE_WRITE) { | |
716 | mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0; | |
717 | /* | |
718 | * Most Unices do not set POLLERR for FIFOs but on Linux they | |
719 | * behave exactly like pipes for poll(). | |
720 | */ | |
721 | if (!pipe->readers) | |
722 | mask |= POLLERR; | |
723 | } | |
724 | ||
725 | return mask; | |
726 | } | |
727 | ||
728 | static int | |
729 | pipe_release(struct inode *inode, struct file *file) | |
730 | { | |
731 | struct pipe_inode_info *pipe = inode->i_pipe; | |
732 | int kill = 0; | |
733 | ||
734 | __pipe_lock(pipe); | |
735 | if (file->f_mode & FMODE_READ) | |
736 | pipe->readers--; | |
737 | if (file->f_mode & FMODE_WRITE) | |
738 | pipe->writers--; | |
739 | ||
740 | if (pipe->readers || pipe->writers) { | |
741 | wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP); | |
742 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
743 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
744 | } | |
745 | spin_lock(&inode->i_lock); | |
746 | if (!--pipe->files) { | |
747 | inode->i_pipe = NULL; | |
748 | kill = 1; | |
749 | } | |
750 | spin_unlock(&inode->i_lock); | |
751 | __pipe_unlock(pipe); | |
752 | ||
753 | if (kill) | |
754 | __free_pipe_info(pipe); | |
755 | ||
756 | return 0; | |
757 | } | |
758 | ||
759 | static int | |
760 | pipe_fasync(int fd, struct file *filp, int on) | |
761 | { | |
762 | struct pipe_inode_info *pipe = filp->private_data; | |
763 | int retval = 0; | |
764 | ||
765 | __pipe_lock(pipe); | |
766 | if (filp->f_mode & FMODE_READ) | |
767 | retval = fasync_helper(fd, filp, on, &pipe->fasync_readers); | |
768 | if ((filp->f_mode & FMODE_WRITE) && retval >= 0) { | |
769 | retval = fasync_helper(fd, filp, on, &pipe->fasync_writers); | |
770 | if (retval < 0 && (filp->f_mode & FMODE_READ)) | |
771 | /* this can happen only if on == T */ | |
772 | fasync_helper(-1, filp, 0, &pipe->fasync_readers); | |
773 | } | |
774 | __pipe_unlock(pipe); | |
775 | return retval; | |
776 | } | |
777 | ||
778 | struct pipe_inode_info * alloc_pipe_info(struct inode *inode) | |
779 | { | |
780 | struct pipe_inode_info *pipe; | |
781 | ||
782 | pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); | |
783 | if (pipe) { | |
784 | pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL); | |
785 | if (pipe->bufs) { | |
786 | init_waitqueue_head(&pipe->wait); | |
787 | pipe->r_counter = pipe->w_counter = 1; | |
788 | pipe->inode = inode; | |
789 | pipe->buffers = PIPE_DEF_BUFFERS; | |
790 | mutex_init(&pipe->mutex); | |
791 | return pipe; | |
792 | } | |
793 | kfree(pipe); | |
794 | } | |
795 | ||
796 | return NULL; | |
797 | } | |
798 | ||
799 | void __free_pipe_info(struct pipe_inode_info *pipe) | |
800 | { | |
801 | int i; | |
802 | ||
803 | for (i = 0; i < pipe->buffers; i++) { | |
804 | struct pipe_buffer *buf = pipe->bufs + i; | |
805 | if (buf->ops) | |
806 | buf->ops->release(pipe, buf); | |
807 | } | |
808 | if (pipe->tmp_page) | |
809 | __free_page(pipe->tmp_page); | |
810 | kfree(pipe->bufs); | |
811 | kfree(pipe); | |
812 | } | |
813 | ||
814 | void free_pipe_info(struct inode *inode) | |
815 | { | |
816 | __free_pipe_info(inode->i_pipe); | |
817 | inode->i_pipe = NULL; | |
818 | } | |
819 | ||
820 | static struct vfsmount *pipe_mnt __read_mostly; | |
821 | ||
822 | /* | |
823 | * pipefs_dname() is called from d_path(). | |
824 | */ | |
825 | static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen) | |
826 | { | |
827 | return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", | |
828 | dentry->d_inode->i_ino); | |
829 | } | |
830 | ||
831 | static const struct dentry_operations pipefs_dentry_operations = { | |
832 | .d_dname = pipefs_dname, | |
833 | }; | |
834 | ||
835 | static struct inode * get_pipe_inode(void) | |
836 | { | |
837 | struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb); | |
838 | struct pipe_inode_info *pipe; | |
839 | ||
840 | if (!inode) | |
841 | goto fail_inode; | |
842 | ||
843 | inode->i_ino = get_next_ino(); | |
844 | ||
845 | pipe = alloc_pipe_info(inode); | |
846 | if (!pipe) | |
847 | goto fail_iput; | |
848 | ||
849 | inode->i_pipe = pipe; | |
850 | pipe->files = 2; | |
851 | pipe->readers = pipe->writers = 1; | |
852 | inode->i_fop = &pipefifo_fops; | |
853 | ||
854 | /* | |
855 | * Mark the inode dirty from the very beginning, | |
856 | * that way it will never be moved to the dirty | |
857 | * list because "mark_inode_dirty()" will think | |
858 | * that it already _is_ on the dirty list. | |
859 | */ | |
860 | inode->i_state = I_DIRTY; | |
861 | inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR; | |
862 | inode->i_uid = current_fsuid(); | |
863 | inode->i_gid = current_fsgid(); | |
864 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
865 | ||
866 | return inode; | |
867 | ||
868 | fail_iput: | |
869 | iput(inode); | |
870 | ||
871 | fail_inode: | |
872 | return NULL; | |
873 | } | |
874 | ||
875 | int create_pipe_files(struct file **res, int flags) | |
876 | { | |
877 | int err; | |
878 | struct inode *inode = get_pipe_inode(); | |
879 | struct file *f; | |
880 | struct path path; | |
881 | static struct qstr name = { .name = "" }; | |
882 | ||
883 | if (!inode) | |
884 | return -ENFILE; | |
885 | ||
886 | err = -ENOMEM; | |
887 | path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name); | |
888 | if (!path.dentry) | |
889 | goto err_inode; | |
890 | path.mnt = mntget(pipe_mnt); | |
891 | ||
892 | d_instantiate(path.dentry, inode); | |
893 | ||
894 | err = -ENFILE; | |
895 | f = alloc_file(&path, FMODE_WRITE, &pipefifo_fops); | |
896 | if (IS_ERR(f)) | |
897 | goto err_dentry; | |
898 | ||
899 | f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT)); | |
900 | f->private_data = inode->i_pipe; | |
901 | ||
902 | res[0] = alloc_file(&path, FMODE_READ, &pipefifo_fops); | |
903 | if (IS_ERR(res[0])) | |
904 | goto err_file; | |
905 | ||
906 | path_get(&path); | |
907 | res[0]->private_data = inode->i_pipe; | |
908 | res[0]->f_flags = O_RDONLY | (flags & O_NONBLOCK); | |
909 | res[1] = f; | |
910 | return 0; | |
911 | ||
912 | err_file: | |
913 | put_filp(f); | |
914 | err_dentry: | |
915 | free_pipe_info(inode); | |
916 | path_put(&path); | |
917 | return err; | |
918 | ||
919 | err_inode: | |
920 | free_pipe_info(inode); | |
921 | iput(inode); | |
922 | return err; | |
923 | } | |
924 | ||
925 | static int __do_pipe_flags(int *fd, struct file **files, int flags) | |
926 | { | |
927 | int error; | |
928 | int fdw, fdr; | |
929 | ||
930 | if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT)) | |
931 | return -EINVAL; | |
932 | ||
933 | error = create_pipe_files(files, flags); | |
934 | if (error) | |
935 | return error; | |
936 | ||
937 | error = get_unused_fd_flags(flags); | |
938 | if (error < 0) | |
939 | goto err_read_pipe; | |
940 | fdr = error; | |
941 | ||
942 | error = get_unused_fd_flags(flags); | |
943 | if (error < 0) | |
944 | goto err_fdr; | |
945 | fdw = error; | |
946 | ||
947 | audit_fd_pair(fdr, fdw); | |
948 | fd[0] = fdr; | |
949 | fd[1] = fdw; | |
950 | return 0; | |
951 | ||
952 | err_fdr: | |
953 | put_unused_fd(fdr); | |
954 | err_read_pipe: | |
955 | fput(files[0]); | |
956 | fput(files[1]); | |
957 | return error; | |
958 | } | |
959 | ||
960 | int do_pipe_flags(int *fd, int flags) | |
961 | { | |
962 | struct file *files[2]; | |
963 | int error = __do_pipe_flags(fd, files, flags); | |
964 | if (!error) { | |
965 | fd_install(fd[0], files[0]); | |
966 | fd_install(fd[1], files[1]); | |
967 | } | |
968 | return error; | |
969 | } | |
970 | ||
971 | /* | |
972 | * sys_pipe() is the normal C calling standard for creating | |
973 | * a pipe. It's not the way Unix traditionally does this, though. | |
974 | */ | |
975 | SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags) | |
976 | { | |
977 | struct file *files[2]; | |
978 | int fd[2]; | |
979 | int error; | |
980 | ||
981 | error = __do_pipe_flags(fd, files, flags); | |
982 | if (!error) { | |
983 | if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) { | |
984 | fput(files[0]); | |
985 | fput(files[1]); | |
986 | put_unused_fd(fd[0]); | |
987 | put_unused_fd(fd[1]); | |
988 | error = -EFAULT; | |
989 | } else { | |
990 | fd_install(fd[0], files[0]); | |
991 | fd_install(fd[1], files[1]); | |
992 | } | |
993 | } | |
994 | return error; | |
995 | } | |
996 | ||
997 | SYSCALL_DEFINE1(pipe, int __user *, fildes) | |
998 | { | |
999 | return sys_pipe2(fildes, 0); | |
1000 | } | |
1001 | ||
1002 | static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt) | |
1003 | { | |
1004 | int cur = *cnt; | |
1005 | ||
1006 | while (cur == *cnt) { | |
1007 | pipe_wait(pipe); | |
1008 | if (signal_pending(current)) | |
1009 | break; | |
1010 | } | |
1011 | return cur == *cnt ? -ERESTARTSYS : 0; | |
1012 | } | |
1013 | ||
1014 | static void wake_up_partner(struct pipe_inode_info *pipe) | |
1015 | { | |
1016 | wake_up_interruptible(&pipe->wait); | |
1017 | } | |
1018 | ||
1019 | static int fifo_open(struct inode *inode, struct file *filp) | |
1020 | { | |
1021 | struct pipe_inode_info *pipe; | |
1022 | bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC; | |
1023 | int kill = 0; | |
1024 | int ret; | |
1025 | ||
1026 | filp->f_version = 0; | |
1027 | ||
1028 | spin_lock(&inode->i_lock); | |
1029 | if (inode->i_pipe) { | |
1030 | pipe = inode->i_pipe; | |
1031 | pipe->files++; | |
1032 | spin_unlock(&inode->i_lock); | |
1033 | } else { | |
1034 | spin_unlock(&inode->i_lock); | |
1035 | pipe = alloc_pipe_info(inode); | |
1036 | if (!pipe) | |
1037 | return -ENOMEM; | |
1038 | pipe->files = 1; | |
1039 | spin_lock(&inode->i_lock); | |
1040 | if (unlikely(inode->i_pipe)) { | |
1041 | inode->i_pipe->files++; | |
1042 | spin_unlock(&inode->i_lock); | |
1043 | __free_pipe_info(pipe); | |
1044 | pipe = inode->i_pipe; | |
1045 | } else { | |
1046 | inode->i_pipe = pipe; | |
1047 | spin_unlock(&inode->i_lock); | |
1048 | } | |
1049 | } | |
1050 | filp->private_data = pipe; | |
1051 | /* OK, we have a pipe and it's pinned down */ | |
1052 | ||
1053 | __pipe_lock(pipe); | |
1054 | ||
1055 | /* We can only do regular read/write on fifos */ | |
1056 | filp->f_mode &= (FMODE_READ | FMODE_WRITE); | |
1057 | ||
1058 | switch (filp->f_mode) { | |
1059 | case FMODE_READ: | |
1060 | /* | |
1061 | * O_RDONLY | |
1062 | * POSIX.1 says that O_NONBLOCK means return with the FIFO | |
1063 | * opened, even when there is no process writing the FIFO. | |
1064 | */ | |
1065 | pipe->r_counter++; | |
1066 | if (pipe->readers++ == 0) | |
1067 | wake_up_partner(pipe); | |
1068 | ||
1069 | if (!is_pipe && !pipe->writers) { | |
1070 | if ((filp->f_flags & O_NONBLOCK)) { | |
1071 | /* suppress POLLHUP until we have | |
1072 | * seen a writer */ | |
1073 | filp->f_version = pipe->w_counter; | |
1074 | } else { | |
1075 | if (wait_for_partner(pipe, &pipe->w_counter)) | |
1076 | goto err_rd; | |
1077 | } | |
1078 | } | |
1079 | break; | |
1080 | ||
1081 | case FMODE_WRITE: | |
1082 | /* | |
1083 | * O_WRONLY | |
1084 | * POSIX.1 says that O_NONBLOCK means return -1 with | |
1085 | * errno=ENXIO when there is no process reading the FIFO. | |
1086 | */ | |
1087 | ret = -ENXIO; | |
1088 | if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers) | |
1089 | goto err; | |
1090 | ||
1091 | pipe->w_counter++; | |
1092 | if (!pipe->writers++) | |
1093 | wake_up_partner(pipe); | |
1094 | ||
1095 | if (!is_pipe && !pipe->readers) { | |
1096 | if (wait_for_partner(pipe, &pipe->r_counter)) | |
1097 | goto err_wr; | |
1098 | } | |
1099 | break; | |
1100 | ||
1101 | case FMODE_READ | FMODE_WRITE: | |
1102 | /* | |
1103 | * O_RDWR | |
1104 | * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set. | |
1105 | * This implementation will NEVER block on a O_RDWR open, since | |
1106 | * the process can at least talk to itself. | |
1107 | */ | |
1108 | ||
1109 | pipe->readers++; | |
1110 | pipe->writers++; | |
1111 | pipe->r_counter++; | |
1112 | pipe->w_counter++; | |
1113 | if (pipe->readers == 1 || pipe->writers == 1) | |
1114 | wake_up_partner(pipe); | |
1115 | break; | |
1116 | ||
1117 | default: | |
1118 | ret = -EINVAL; | |
1119 | goto err; | |
1120 | } | |
1121 | ||
1122 | /* Ok! */ | |
1123 | __pipe_unlock(pipe); | |
1124 | return 0; | |
1125 | ||
1126 | err_rd: | |
1127 | if (!--pipe->readers) | |
1128 | wake_up_interruptible(&pipe->wait); | |
1129 | ret = -ERESTARTSYS; | |
1130 | goto err; | |
1131 | ||
1132 | err_wr: | |
1133 | if (!--pipe->writers) | |
1134 | wake_up_interruptible(&pipe->wait); | |
1135 | ret = -ERESTARTSYS; | |
1136 | goto err; | |
1137 | ||
1138 | err: | |
1139 | spin_lock(&inode->i_lock); | |
1140 | if (!--pipe->files) { | |
1141 | inode->i_pipe = NULL; | |
1142 | kill = 1; | |
1143 | } | |
1144 | spin_unlock(&inode->i_lock); | |
1145 | __pipe_unlock(pipe); | |
1146 | if (kill) | |
1147 | __free_pipe_info(pipe); | |
1148 | return ret; | |
1149 | } | |
1150 | ||
1151 | const struct file_operations pipefifo_fops = { | |
1152 | .open = fifo_open, | |
1153 | .llseek = no_llseek, | |
1154 | .read = do_sync_read, | |
1155 | .aio_read = pipe_read, | |
1156 | .write = do_sync_write, | |
1157 | .aio_write = pipe_write, | |
1158 | .poll = pipe_poll, | |
1159 | .unlocked_ioctl = pipe_ioctl, | |
1160 | .release = pipe_release, | |
1161 | .fasync = pipe_fasync, | |
1162 | }; | |
1163 | ||
1164 | /* | |
1165 | * Allocate a new array of pipe buffers and copy the info over. Returns the | |
1166 | * pipe size if successful, or return -ERROR on error. | |
1167 | */ | |
1168 | static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) | |
1169 | { | |
1170 | struct pipe_buffer *bufs; | |
1171 | ||
1172 | /* | |
1173 | * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't | |
1174 | * expect a lot of shrink+grow operations, just free and allocate | |
1175 | * again like we would do for growing. If the pipe currently | |
1176 | * contains more buffers than arg, then return busy. | |
1177 | */ | |
1178 | if (nr_pages < pipe->nrbufs) | |
1179 | return -EBUSY; | |
1180 | ||
1181 | bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL | __GFP_NOWARN); | |
1182 | if (unlikely(!bufs)) | |
1183 | return -ENOMEM; | |
1184 | ||
1185 | /* | |
1186 | * The pipe array wraps around, so just start the new one at zero | |
1187 | * and adjust the indexes. | |
1188 | */ | |
1189 | if (pipe->nrbufs) { | |
1190 | unsigned int tail; | |
1191 | unsigned int head; | |
1192 | ||
1193 | tail = pipe->curbuf + pipe->nrbufs; | |
1194 | if (tail < pipe->buffers) | |
1195 | tail = 0; | |
1196 | else | |
1197 | tail &= (pipe->buffers - 1); | |
1198 | ||
1199 | head = pipe->nrbufs - tail; | |
1200 | if (head) | |
1201 | memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer)); | |
1202 | if (tail) | |
1203 | memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer)); | |
1204 | } | |
1205 | ||
1206 | pipe->curbuf = 0; | |
1207 | kfree(pipe->bufs); | |
1208 | pipe->bufs = bufs; | |
1209 | pipe->buffers = nr_pages; | |
1210 | return nr_pages * PAGE_SIZE; | |
1211 | } | |
1212 | ||
1213 | /* | |
1214 | * Currently we rely on the pipe array holding a power-of-2 number | |
1215 | * of pages. | |
1216 | */ | |
1217 | static inline unsigned int round_pipe_size(unsigned int size) | |
1218 | { | |
1219 | unsigned long nr_pages; | |
1220 | ||
1221 | nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
1222 | return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; | |
1223 | } | |
1224 | ||
1225 | /* | |
1226 | * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax | |
1227 | * will return an error. | |
1228 | */ | |
1229 | int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf, | |
1230 | size_t *lenp, loff_t *ppos) | |
1231 | { | |
1232 | int ret; | |
1233 | ||
1234 | ret = proc_dointvec_minmax(table, write, buf, lenp, ppos); | |
1235 | if (ret < 0 || !write) | |
1236 | return ret; | |
1237 | ||
1238 | pipe_max_size = round_pipe_size(pipe_max_size); | |
1239 | return ret; | |
1240 | } | |
1241 | ||
1242 | /* | |
1243 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same | |
1244 | * location, so checking ->i_pipe is not enough to verify that this is a | |
1245 | * pipe. | |
1246 | */ | |
1247 | struct pipe_inode_info *get_pipe_info(struct file *file) | |
1248 | { | |
1249 | return file->f_op == &pipefifo_fops ? file->private_data : NULL; | |
1250 | } | |
1251 | ||
1252 | long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) | |
1253 | { | |
1254 | struct pipe_inode_info *pipe; | |
1255 | long ret; | |
1256 | ||
1257 | pipe = get_pipe_info(file); | |
1258 | if (!pipe) | |
1259 | return -EBADF; | |
1260 | ||
1261 | __pipe_lock(pipe); | |
1262 | ||
1263 | switch (cmd) { | |
1264 | case F_SETPIPE_SZ: { | |
1265 | unsigned int size, nr_pages; | |
1266 | ||
1267 | size = round_pipe_size(arg); | |
1268 | nr_pages = size >> PAGE_SHIFT; | |
1269 | ||
1270 | ret = -EINVAL; | |
1271 | if (!nr_pages) | |
1272 | goto out; | |
1273 | ||
1274 | if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) { | |
1275 | ret = -EPERM; | |
1276 | goto out; | |
1277 | } | |
1278 | ret = pipe_set_size(pipe, nr_pages); | |
1279 | break; | |
1280 | } | |
1281 | case F_GETPIPE_SZ: | |
1282 | ret = pipe->buffers * PAGE_SIZE; | |
1283 | break; | |
1284 | default: | |
1285 | ret = -EINVAL; | |
1286 | break; | |
1287 | } | |
1288 | ||
1289 | out: | |
1290 | __pipe_unlock(pipe); | |
1291 | return ret; | |
1292 | } | |
1293 | ||
1294 | static const struct super_operations pipefs_ops = { | |
1295 | .destroy_inode = free_inode_nonrcu, | |
1296 | .statfs = simple_statfs, | |
1297 | }; | |
1298 | ||
1299 | /* | |
1300 | * pipefs should _never_ be mounted by userland - too much of security hassle, | |
1301 | * no real gain from having the whole whorehouse mounted. So we don't need | |
1302 | * any operations on the root directory. However, we need a non-trivial | |
1303 | * d_name - pipe: will go nicely and kill the special-casing in procfs. | |
1304 | */ | |
1305 | static struct dentry *pipefs_mount(struct file_system_type *fs_type, | |
1306 | int flags, const char *dev_name, void *data) | |
1307 | { | |
1308 | return mount_pseudo(fs_type, "pipe:", &pipefs_ops, | |
1309 | &pipefs_dentry_operations, PIPEFS_MAGIC); | |
1310 | } | |
1311 | ||
1312 | static struct file_system_type pipe_fs_type = { | |
1313 | .name = "pipefs", | |
1314 | .mount = pipefs_mount, | |
1315 | .kill_sb = kill_anon_super, | |
1316 | }; | |
1317 | ||
1318 | static int __init init_pipe_fs(void) | |
1319 | { | |
1320 | int err = register_filesystem(&pipe_fs_type); | |
1321 | ||
1322 | if (!err) { | |
1323 | pipe_mnt = kern_mount(&pipe_fs_type); | |
1324 | if (IS_ERR(pipe_mnt)) { | |
1325 | err = PTR_ERR(pipe_mnt); | |
1326 | unregister_filesystem(&pipe_fs_type); | |
1327 | } | |
1328 | } | |
1329 | return err; | |
1330 | } | |
1331 | ||
1332 | fs_initcall(init_pipe_fs); |