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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/pipe_fs_i.h> | |
17 | #include <linux/uio.h> | |
18 | #include <linux/highmem.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/audit.h> | |
21 | #include <linux/syscalls.h> | |
22 | #include <linux/fcntl.h> | |
23 | ||
24 | #include <asm/uaccess.h> | |
25 | #include <asm/ioctls.h> | |
26 | ||
27 | /* | |
28 | * The max size that a non-root user is allowed to grow the pipe. Can | |
29 | * be set by root in /proc/sys/fs/pipe-max-size | |
30 | */ | |
31 | unsigned int pipe_max_size = 1048576; | |
32 | ||
33 | /* | |
34 | * Minimum pipe size, as required by POSIX | |
35 | */ | |
36 | unsigned int pipe_min_size = PAGE_SIZE; | |
37 | ||
38 | /* | |
39 | * We use a start+len construction, which provides full use of the | |
40 | * allocated memory. | |
41 | * -- Florian Coosmann (FGC) | |
42 | * | |
43 | * Reads with count = 0 should always return 0. | |
44 | * -- Julian Bradfield 1999-06-07. | |
45 | * | |
46 | * FIFOs and Pipes now generate SIGIO for both readers and writers. | |
47 | * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16 | |
48 | * | |
49 | * pipe_read & write cleanup | |
50 | * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09 | |
51 | */ | |
52 | ||
53 | static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass) | |
54 | { | |
55 | if (pipe->inode) | |
56 | mutex_lock_nested(&pipe->inode->i_mutex, subclass); | |
57 | } | |
58 | ||
59 | void pipe_lock(struct pipe_inode_info *pipe) | |
60 | { | |
61 | /* | |
62 | * pipe_lock() nests non-pipe inode locks (for writing to a file) | |
63 | */ | |
64 | pipe_lock_nested(pipe, I_MUTEX_PARENT); | |
65 | } | |
66 | EXPORT_SYMBOL(pipe_lock); | |
67 | ||
68 | void pipe_unlock(struct pipe_inode_info *pipe) | |
69 | { | |
70 | if (pipe->inode) | |
71 | mutex_unlock(&pipe->inode->i_mutex); | |
72 | } | |
73 | EXPORT_SYMBOL(pipe_unlock); | |
74 | ||
75 | void pipe_double_lock(struct pipe_inode_info *pipe1, | |
76 | struct pipe_inode_info *pipe2) | |
77 | { | |
78 | BUG_ON(pipe1 == pipe2); | |
79 | ||
80 | if (pipe1 < pipe2) { | |
81 | pipe_lock_nested(pipe1, I_MUTEX_PARENT); | |
82 | pipe_lock_nested(pipe2, I_MUTEX_CHILD); | |
83 | } else { | |
84 | pipe_lock_nested(pipe2, I_MUTEX_PARENT); | |
85 | pipe_lock_nested(pipe1, I_MUTEX_CHILD); | |
86 | } | |
87 | } | |
88 | ||
89 | /* Drop the inode semaphore and wait for a pipe event, atomically */ | |
90 | void pipe_wait(struct pipe_inode_info *pipe) | |
91 | { | |
92 | DEFINE_WAIT(wait); | |
93 | ||
94 | /* | |
95 | * Pipes are system-local resources, so sleeping on them | |
96 | * is considered a noninteractive wait: | |
97 | */ | |
98 | prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE); | |
99 | pipe_unlock(pipe); | |
100 | schedule(); | |
101 | finish_wait(&pipe->wait, &wait); | |
102 | pipe_lock(pipe); | |
103 | } | |
104 | ||
105 | static int | |
106 | pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len, | |
107 | int atomic) | |
108 | { | |
109 | unsigned long copy; | |
110 | ||
111 | while (len > 0) { | |
112 | while (!iov->iov_len) | |
113 | iov++; | |
114 | copy = min_t(unsigned long, len, iov->iov_len); | |
115 | ||
116 | if (atomic) { | |
117 | if (__copy_from_user_inatomic(to, iov->iov_base, copy)) | |
118 | return -EFAULT; | |
119 | } else { | |
120 | if (copy_from_user(to, iov->iov_base, copy)) | |
121 | return -EFAULT; | |
122 | } | |
123 | to += copy; | |
124 | len -= copy; | |
125 | iov->iov_base += copy; | |
126 | iov->iov_len -= copy; | |
127 | } | |
128 | return 0; | |
129 | } | |
130 | ||
131 | static int | |
132 | pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len, | |
133 | int atomic) | |
134 | { | |
135 | unsigned long copy; | |
136 | ||
137 | while (len > 0) { | |
138 | while (!iov->iov_len) | |
139 | iov++; | |
140 | copy = min_t(unsigned long, len, iov->iov_len); | |
141 | ||
142 | if (atomic) { | |
143 | if (__copy_to_user_inatomic(iov->iov_base, from, copy)) | |
144 | return -EFAULT; | |
145 | } else { | |
146 | if (copy_to_user(iov->iov_base, from, copy)) | |
147 | return -EFAULT; | |
148 | } | |
149 | from += copy; | |
150 | len -= copy; | |
151 | iov->iov_base += copy; | |
152 | iov->iov_len -= copy; | |
153 | } | |
154 | return 0; | |
155 | } | |
156 | ||
157 | /* | |
158 | * Attempt to pre-fault in the user memory, so we can use atomic copies. | |
159 | * Returns the number of bytes not faulted in. | |
160 | */ | |
161 | static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len) | |
162 | { | |
163 | while (!iov->iov_len) | |
164 | iov++; | |
165 | ||
166 | while (len > 0) { | |
167 | unsigned long this_len; | |
168 | ||
169 | this_len = min_t(unsigned long, len, iov->iov_len); | |
170 | if (fault_in_pages_writeable(iov->iov_base, this_len)) | |
171 | break; | |
172 | ||
173 | len -= this_len; | |
174 | iov++; | |
175 | } | |
176 | ||
177 | return len; | |
178 | } | |
179 | ||
180 | /* | |
181 | * Pre-fault in the user memory, so we can use atomic copies. | |
182 | */ | |
183 | static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len) | |
184 | { | |
185 | while (!iov->iov_len) | |
186 | iov++; | |
187 | ||
188 | while (len > 0) { | |
189 | unsigned long this_len; | |
190 | ||
191 | this_len = min_t(unsigned long, len, iov->iov_len); | |
192 | fault_in_pages_readable(iov->iov_base, this_len); | |
193 | len -= this_len; | |
194 | iov++; | |
195 | } | |
196 | } | |
197 | ||
198 | static void anon_pipe_buf_release(struct pipe_inode_info *pipe, | |
199 | struct pipe_buffer *buf) | |
200 | { | |
201 | struct page *page = buf->page; | |
202 | ||
203 | /* | |
204 | * If nobody else uses this page, and we don't already have a | |
205 | * temporary page, let's keep track of it as a one-deep | |
206 | * allocation cache. (Otherwise just release our reference to it) | |
207 | */ | |
208 | if (page_count(page) == 1 && !pipe->tmp_page) | |
209 | pipe->tmp_page = page; | |
210 | else | |
211 | page_cache_release(page); | |
212 | } | |
213 | ||
214 | /** | |
215 | * generic_pipe_buf_map - virtually map a pipe buffer | |
216 | * @pipe: the pipe that the buffer belongs to | |
217 | * @buf: the buffer that should be mapped | |
218 | * @atomic: whether to use an atomic map | |
219 | * | |
220 | * Description: | |
221 | * This function returns a kernel virtual address mapping for the | |
222 | * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided | |
223 | * and the caller has to be careful not to fault before calling | |
224 | * the unmap function. | |
225 | * | |
226 | * Note that this function occupies KM_USER0 if @atomic != 0. | |
227 | */ | |
228 | void *generic_pipe_buf_map(struct pipe_inode_info *pipe, | |
229 | struct pipe_buffer *buf, int atomic) | |
230 | { | |
231 | if (atomic) { | |
232 | buf->flags |= PIPE_BUF_FLAG_ATOMIC; | |
233 | return kmap_atomic(buf->page, KM_USER0); | |
234 | } | |
235 | ||
236 | return kmap(buf->page); | |
237 | } | |
238 | EXPORT_SYMBOL(generic_pipe_buf_map); | |
239 | ||
240 | /** | |
241 | * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer | |
242 | * @pipe: the pipe that the buffer belongs to | |
243 | * @buf: the buffer that should be unmapped | |
244 | * @map_data: the data that the mapping function returned | |
245 | * | |
246 | * Description: | |
247 | * This function undoes the mapping that ->map() provided. | |
248 | */ | |
249 | void generic_pipe_buf_unmap(struct pipe_inode_info *pipe, | |
250 | struct pipe_buffer *buf, void *map_data) | |
251 | { | |
252 | if (buf->flags & PIPE_BUF_FLAG_ATOMIC) { | |
253 | buf->flags &= ~PIPE_BUF_FLAG_ATOMIC; | |
254 | kunmap_atomic(map_data, KM_USER0); | |
255 | } else | |
256 | kunmap(buf->page); | |
257 | } | |
258 | EXPORT_SYMBOL(generic_pipe_buf_unmap); | |
259 | ||
260 | /** | |
261 | * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer | |
262 | * @pipe: the pipe that the buffer belongs to | |
263 | * @buf: the buffer to attempt to steal | |
264 | * | |
265 | * Description: | |
266 | * This function attempts to steal the &struct page attached to | |
267 | * @buf. If successful, this function returns 0 and returns with | |
268 | * the page locked. The caller may then reuse the page for whatever | |
269 | * he wishes; the typical use is insertion into a different file | |
270 | * page cache. | |
271 | */ | |
272 | int generic_pipe_buf_steal(struct pipe_inode_info *pipe, | |
273 | struct pipe_buffer *buf) | |
274 | { | |
275 | struct page *page = buf->page; | |
276 | ||
277 | /* | |
278 | * A reference of one is golden, that means that the owner of this | |
279 | * page is the only one holding a reference to it. lock the page | |
280 | * and return OK. | |
281 | */ | |
282 | if (page_count(page) == 1) { | |
283 | lock_page(page); | |
284 | return 0; | |
285 | } | |
286 | ||
287 | return 1; | |
288 | } | |
289 | EXPORT_SYMBOL(generic_pipe_buf_steal); | |
290 | ||
291 | /** | |
292 | * generic_pipe_buf_get - get a reference to a &struct pipe_buffer | |
293 | * @pipe: the pipe that the buffer belongs to | |
294 | * @buf: the buffer to get a reference to | |
295 | * | |
296 | * Description: | |
297 | * This function grabs an extra reference to @buf. It's used in | |
298 | * in the tee() system call, when we duplicate the buffers in one | |
299 | * pipe into another. | |
300 | */ | |
301 | void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) | |
302 | { | |
303 | page_cache_get(buf->page); | |
304 | } | |
305 | EXPORT_SYMBOL(generic_pipe_buf_get); | |
306 | ||
307 | /** | |
308 | * generic_pipe_buf_confirm - verify contents of the pipe buffer | |
309 | * @info: the pipe that the buffer belongs to | |
310 | * @buf: the buffer to confirm | |
311 | * | |
312 | * Description: | |
313 | * This function does nothing, because the generic pipe code uses | |
314 | * pages that are always good when inserted into the pipe. | |
315 | */ | |
316 | int generic_pipe_buf_confirm(struct pipe_inode_info *info, | |
317 | struct pipe_buffer *buf) | |
318 | { | |
319 | return 0; | |
320 | } | |
321 | EXPORT_SYMBOL(generic_pipe_buf_confirm); | |
322 | ||
323 | /** | |
324 | * generic_pipe_buf_release - put a reference to a &struct pipe_buffer | |
325 | * @pipe: the pipe that the buffer belongs to | |
326 | * @buf: the buffer to put a reference to | |
327 | * | |
328 | * Description: | |
329 | * This function releases a reference to @buf. | |
330 | */ | |
331 | void generic_pipe_buf_release(struct pipe_inode_info *pipe, | |
332 | struct pipe_buffer *buf) | |
333 | { | |
334 | page_cache_release(buf->page); | |
335 | } | |
336 | EXPORT_SYMBOL(generic_pipe_buf_release); | |
337 | ||
338 | static const struct pipe_buf_operations anon_pipe_buf_ops = { | |
339 | .can_merge = 1, | |
340 | .map = generic_pipe_buf_map, | |
341 | .unmap = generic_pipe_buf_unmap, | |
342 | .confirm = generic_pipe_buf_confirm, | |
343 | .release = anon_pipe_buf_release, | |
344 | .steal = generic_pipe_buf_steal, | |
345 | .get = generic_pipe_buf_get, | |
346 | }; | |
347 | ||
348 | static ssize_t | |
349 | pipe_read(struct kiocb *iocb, const struct iovec *_iov, | |
350 | unsigned long nr_segs, loff_t pos) | |
351 | { | |
352 | struct file *filp = iocb->ki_filp; | |
353 | struct inode *inode = filp->f_path.dentry->d_inode; | |
354 | struct pipe_inode_info *pipe; | |
355 | int do_wakeup; | |
356 | ssize_t ret; | |
357 | struct iovec *iov = (struct iovec *)_iov; | |
358 | size_t total_len; | |
359 | ||
360 | total_len = iov_length(iov, nr_segs); | |
361 | /* Null read succeeds. */ | |
362 | if (unlikely(total_len == 0)) | |
363 | return 0; | |
364 | ||
365 | do_wakeup = 0; | |
366 | ret = 0; | |
367 | mutex_lock(&inode->i_mutex); | |
368 | pipe = inode->i_pipe; | |
369 | for (;;) { | |
370 | int bufs = pipe->nrbufs; | |
371 | if (bufs) { | |
372 | int curbuf = pipe->curbuf; | |
373 | struct pipe_buffer *buf = pipe->bufs + curbuf; | |
374 | const struct pipe_buf_operations *ops = buf->ops; | |
375 | void *addr; | |
376 | size_t chars = buf->len; | |
377 | int error, atomic; | |
378 | ||
379 | if (chars > total_len) | |
380 | chars = total_len; | |
381 | ||
382 | error = ops->confirm(pipe, buf); | |
383 | if (error) { | |
384 | if (!ret) | |
385 | ret = error; | |
386 | break; | |
387 | } | |
388 | ||
389 | atomic = !iov_fault_in_pages_write(iov, chars); | |
390 | redo: | |
391 | addr = ops->map(pipe, buf, atomic); | |
392 | error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic); | |
393 | ops->unmap(pipe, buf, addr); | |
394 | if (unlikely(error)) { | |
395 | /* | |
396 | * Just retry with the slow path if we failed. | |
397 | */ | |
398 | if (atomic) { | |
399 | atomic = 0; | |
400 | goto redo; | |
401 | } | |
402 | if (!ret) | |
403 | ret = error; | |
404 | break; | |
405 | } | |
406 | ret += chars; | |
407 | buf->offset += chars; | |
408 | buf->len -= chars; | |
409 | if (!buf->len) { | |
410 | buf->ops = NULL; | |
411 | ops->release(pipe, buf); | |
412 | curbuf = (curbuf + 1) & (pipe->buffers - 1); | |
413 | pipe->curbuf = curbuf; | |
414 | pipe->nrbufs = --bufs; | |
415 | do_wakeup = 1; | |
416 | } | |
417 | total_len -= chars; | |
418 | if (!total_len) | |
419 | break; /* common path: read succeeded */ | |
420 | } | |
421 | if (bufs) /* More to do? */ | |
422 | continue; | |
423 | if (!pipe->writers) | |
424 | break; | |
425 | if (!pipe->waiting_writers) { | |
426 | /* syscall merging: Usually we must not sleep | |
427 | * if O_NONBLOCK is set, or if we got some data. | |
428 | * But if a writer sleeps in kernel space, then | |
429 | * we can wait for that data without violating POSIX. | |
430 | */ | |
431 | if (ret) | |
432 | break; | |
433 | if (filp->f_flags & O_NONBLOCK) { | |
434 | ret = -EAGAIN; | |
435 | break; | |
436 | } | |
437 | } | |
438 | if (signal_pending(current)) { | |
439 | if (!ret) | |
440 | ret = -ERESTARTSYS; | |
441 | break; | |
442 | } | |
443 | if (do_wakeup) { | |
444 | wake_up_interruptible_sync(&pipe->wait); | |
445 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
446 | } | |
447 | pipe_wait(pipe); | |
448 | } | |
449 | mutex_unlock(&inode->i_mutex); | |
450 | ||
451 | /* Signal writers asynchronously that there is more room. */ | |
452 | if (do_wakeup) { | |
453 | wake_up_interruptible_sync(&pipe->wait); | |
454 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
455 | } | |
456 | if (ret > 0) | |
457 | file_accessed(filp); | |
458 | return ret; | |
459 | } | |
460 | ||
461 | static ssize_t | |
462 | pipe_write(struct kiocb *iocb, const struct iovec *_iov, | |
463 | unsigned long nr_segs, loff_t ppos) | |
464 | { | |
465 | struct file *filp = iocb->ki_filp; | |
466 | struct inode *inode = filp->f_path.dentry->d_inode; | |
467 | struct pipe_inode_info *pipe; | |
468 | ssize_t ret; | |
469 | int do_wakeup; | |
470 | struct iovec *iov = (struct iovec *)_iov; | |
471 | size_t total_len; | |
472 | ssize_t chars; | |
473 | ||
474 | total_len = iov_length(iov, nr_segs); | |
475 | /* Null write succeeds. */ | |
476 | if (unlikely(total_len == 0)) | |
477 | return 0; | |
478 | ||
479 | do_wakeup = 0; | |
480 | ret = 0; | |
481 | mutex_lock(&inode->i_mutex); | |
482 | pipe = inode->i_pipe; | |
483 | ||
484 | if (!pipe->readers) { | |
485 | send_sig(SIGPIPE, current, 0); | |
486 | ret = -EPIPE; | |
487 | goto out; | |
488 | } | |
489 | ||
490 | /* We try to merge small writes */ | |
491 | chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */ | |
492 | if (pipe->nrbufs && chars != 0) { | |
493 | int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) & | |
494 | (pipe->buffers - 1); | |
495 | struct pipe_buffer *buf = pipe->bufs + lastbuf; | |
496 | const struct pipe_buf_operations *ops = buf->ops; | |
497 | int offset = buf->offset + buf->len; | |
498 | ||
499 | if (ops->can_merge && offset + chars <= PAGE_SIZE) { | |
500 | int error, atomic = 1; | |
501 | void *addr; | |
502 | ||
503 | error = ops->confirm(pipe, buf); | |
504 | if (error) | |
505 | goto out; | |
506 | ||
507 | iov_fault_in_pages_read(iov, chars); | |
508 | redo1: | |
509 | addr = ops->map(pipe, buf, atomic); | |
510 | error = pipe_iov_copy_from_user(offset + addr, iov, | |
511 | chars, atomic); | |
512 | ops->unmap(pipe, buf, addr); | |
513 | ret = error; | |
514 | do_wakeup = 1; | |
515 | if (error) { | |
516 | if (atomic) { | |
517 | atomic = 0; | |
518 | goto redo1; | |
519 | } | |
520 | goto out; | |
521 | } | |
522 | buf->len += chars; | |
523 | total_len -= chars; | |
524 | ret = chars; | |
525 | if (!total_len) | |
526 | goto out; | |
527 | } | |
528 | } | |
529 | ||
530 | for (;;) { | |
531 | int bufs; | |
532 | ||
533 | if (!pipe->readers) { | |
534 | send_sig(SIGPIPE, current, 0); | |
535 | if (!ret) | |
536 | ret = -EPIPE; | |
537 | break; | |
538 | } | |
539 | bufs = pipe->nrbufs; | |
540 | if (bufs < pipe->buffers) { | |
541 | int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1); | |
542 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
543 | struct page *page = pipe->tmp_page; | |
544 | char *src; | |
545 | int error, atomic = 1; | |
546 | ||
547 | if (!page) { | |
548 | page = alloc_page(GFP_HIGHUSER); | |
549 | if (unlikely(!page)) { | |
550 | ret = ret ? : -ENOMEM; | |
551 | break; | |
552 | } | |
553 | pipe->tmp_page = page; | |
554 | } | |
555 | /* Always wake up, even if the copy fails. Otherwise | |
556 | * we lock up (O_NONBLOCK-)readers that sleep due to | |
557 | * syscall merging. | |
558 | * FIXME! Is this really true? | |
559 | */ | |
560 | do_wakeup = 1; | |
561 | chars = PAGE_SIZE; | |
562 | if (chars > total_len) | |
563 | chars = total_len; | |
564 | ||
565 | iov_fault_in_pages_read(iov, chars); | |
566 | redo2: | |
567 | if (atomic) | |
568 | src = kmap_atomic(page, KM_USER0); | |
569 | else | |
570 | src = kmap(page); | |
571 | ||
572 | error = pipe_iov_copy_from_user(src, iov, chars, | |
573 | atomic); | |
574 | if (atomic) | |
575 | kunmap_atomic(src, KM_USER0); | |
576 | else | |
577 | kunmap(page); | |
578 | ||
579 | if (unlikely(error)) { | |
580 | if (atomic) { | |
581 | atomic = 0; | |
582 | goto redo2; | |
583 | } | |
584 | if (!ret) | |
585 | ret = error; | |
586 | break; | |
587 | } | |
588 | ret += chars; | |
589 | ||
590 | /* Insert it into the buffer array */ | |
591 | buf->page = page; | |
592 | buf->ops = &anon_pipe_buf_ops; | |
593 | buf->offset = 0; | |
594 | buf->len = chars; | |
595 | pipe->nrbufs = ++bufs; | |
596 | pipe->tmp_page = NULL; | |
597 | ||
598 | total_len -= chars; | |
599 | if (!total_len) | |
600 | break; | |
601 | } | |
602 | if (bufs < pipe->buffers) | |
603 | continue; | |
604 | if (filp->f_flags & O_NONBLOCK) { | |
605 | if (!ret) | |
606 | ret = -EAGAIN; | |
607 | break; | |
608 | } | |
609 | if (signal_pending(current)) { | |
610 | if (!ret) | |
611 | ret = -ERESTARTSYS; | |
612 | break; | |
613 | } | |
614 | if (do_wakeup) { | |
615 | wake_up_interruptible_sync(&pipe->wait); | |
616 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
617 | do_wakeup = 0; | |
618 | } | |
619 | pipe->waiting_writers++; | |
620 | pipe_wait(pipe); | |
621 | pipe->waiting_writers--; | |
622 | } | |
623 | out: | |
624 | mutex_unlock(&inode->i_mutex); | |
625 | if (do_wakeup) { | |
626 | wake_up_interruptible_sync(&pipe->wait); | |
627 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
628 | } | |
629 | if (ret > 0) | |
630 | file_update_time(filp); | |
631 | return ret; | |
632 | } | |
633 | ||
634 | static ssize_t | |
635 | bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos) | |
636 | { | |
637 | return -EBADF; | |
638 | } | |
639 | ||
640 | static ssize_t | |
641 | bad_pipe_w(struct file *filp, const char __user *buf, size_t count, | |
642 | loff_t *ppos) | |
643 | { | |
644 | return -EBADF; | |
645 | } | |
646 | ||
647 | static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
648 | { | |
649 | struct inode *inode = filp->f_path.dentry->d_inode; | |
650 | struct pipe_inode_info *pipe; | |
651 | int count, buf, nrbufs; | |
652 | ||
653 | switch (cmd) { | |
654 | case FIONREAD: | |
655 | mutex_lock(&inode->i_mutex); | |
656 | pipe = inode->i_pipe; | |
657 | count = 0; | |
658 | buf = pipe->curbuf; | |
659 | nrbufs = pipe->nrbufs; | |
660 | while (--nrbufs >= 0) { | |
661 | count += pipe->bufs[buf].len; | |
662 | buf = (buf+1) & (pipe->buffers - 1); | |
663 | } | |
664 | mutex_unlock(&inode->i_mutex); | |
665 | ||
666 | return put_user(count, (int __user *)arg); | |
667 | default: | |
668 | return -EINVAL; | |
669 | } | |
670 | } | |
671 | ||
672 | /* No kernel lock held - fine */ | |
673 | static unsigned int | |
674 | pipe_poll(struct file *filp, poll_table *wait) | |
675 | { | |
676 | unsigned int mask; | |
677 | struct inode *inode = filp->f_path.dentry->d_inode; | |
678 | struct pipe_inode_info *pipe = inode->i_pipe; | |
679 | int nrbufs; | |
680 | ||
681 | poll_wait(filp, &pipe->wait, wait); | |
682 | ||
683 | /* Reading only -- no need for acquiring the semaphore. */ | |
684 | nrbufs = pipe->nrbufs; | |
685 | mask = 0; | |
686 | if (filp->f_mode & FMODE_READ) { | |
687 | mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0; | |
688 | if (!pipe->writers && filp->f_version != pipe->w_counter) | |
689 | mask |= POLLHUP; | |
690 | } | |
691 | ||
692 | if (filp->f_mode & FMODE_WRITE) { | |
693 | mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0; | |
694 | /* | |
695 | * Most Unices do not set POLLERR for FIFOs but on Linux they | |
696 | * behave exactly like pipes for poll(). | |
697 | */ | |
698 | if (!pipe->readers) | |
699 | mask |= POLLERR; | |
700 | } | |
701 | ||
702 | return mask; | |
703 | } | |
704 | ||
705 | static int | |
706 | pipe_release(struct inode *inode, int decr, int decw) | |
707 | { | |
708 | struct pipe_inode_info *pipe; | |
709 | ||
710 | mutex_lock(&inode->i_mutex); | |
711 | pipe = inode->i_pipe; | |
712 | pipe->readers -= decr; | |
713 | pipe->writers -= decw; | |
714 | ||
715 | if (!pipe->readers && !pipe->writers) { | |
716 | free_pipe_info(inode); | |
717 | } else { | |
718 | wake_up_interruptible_sync(&pipe->wait); | |
719 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
720 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
721 | } | |
722 | mutex_unlock(&inode->i_mutex); | |
723 | ||
724 | return 0; | |
725 | } | |
726 | ||
727 | static int | |
728 | pipe_read_fasync(int fd, struct file *filp, int on) | |
729 | { | |
730 | struct inode *inode = filp->f_path.dentry->d_inode; | |
731 | int retval; | |
732 | ||
733 | mutex_lock(&inode->i_mutex); | |
734 | retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers); | |
735 | mutex_unlock(&inode->i_mutex); | |
736 | ||
737 | return retval; | |
738 | } | |
739 | ||
740 | ||
741 | static int | |
742 | pipe_write_fasync(int fd, struct file *filp, int on) | |
743 | { | |
744 | struct inode *inode = filp->f_path.dentry->d_inode; | |
745 | int retval; | |
746 | ||
747 | mutex_lock(&inode->i_mutex); | |
748 | retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers); | |
749 | mutex_unlock(&inode->i_mutex); | |
750 | ||
751 | return retval; | |
752 | } | |
753 | ||
754 | ||
755 | static int | |
756 | pipe_rdwr_fasync(int fd, struct file *filp, int on) | |
757 | { | |
758 | struct inode *inode = filp->f_path.dentry->d_inode; | |
759 | struct pipe_inode_info *pipe = inode->i_pipe; | |
760 | int retval; | |
761 | ||
762 | mutex_lock(&inode->i_mutex); | |
763 | retval = fasync_helper(fd, filp, on, &pipe->fasync_readers); | |
764 | if (retval >= 0) { | |
765 | retval = fasync_helper(fd, filp, on, &pipe->fasync_writers); | |
766 | if (retval < 0) /* this can happen only if on == T */ | |
767 | fasync_helper(-1, filp, 0, &pipe->fasync_readers); | |
768 | } | |
769 | mutex_unlock(&inode->i_mutex); | |
770 | return retval; | |
771 | } | |
772 | ||
773 | ||
774 | static int | |
775 | pipe_read_release(struct inode *inode, struct file *filp) | |
776 | { | |
777 | return pipe_release(inode, 1, 0); | |
778 | } | |
779 | ||
780 | static int | |
781 | pipe_write_release(struct inode *inode, struct file *filp) | |
782 | { | |
783 | return pipe_release(inode, 0, 1); | |
784 | } | |
785 | ||
786 | static int | |
787 | pipe_rdwr_release(struct inode *inode, struct file *filp) | |
788 | { | |
789 | int decr, decw; | |
790 | ||
791 | decr = (filp->f_mode & FMODE_READ) != 0; | |
792 | decw = (filp->f_mode & FMODE_WRITE) != 0; | |
793 | return pipe_release(inode, decr, decw); | |
794 | } | |
795 | ||
796 | static int | |
797 | pipe_read_open(struct inode *inode, struct file *filp) | |
798 | { | |
799 | int ret = -ENOENT; | |
800 | ||
801 | mutex_lock(&inode->i_mutex); | |
802 | ||
803 | if (inode->i_pipe) { | |
804 | ret = 0; | |
805 | inode->i_pipe->readers++; | |
806 | } | |
807 | ||
808 | mutex_unlock(&inode->i_mutex); | |
809 | ||
810 | return ret; | |
811 | } | |
812 | ||
813 | static int | |
814 | pipe_write_open(struct inode *inode, struct file *filp) | |
815 | { | |
816 | int ret = -ENOENT; | |
817 | ||
818 | mutex_lock(&inode->i_mutex); | |
819 | ||
820 | if (inode->i_pipe) { | |
821 | ret = 0; | |
822 | inode->i_pipe->writers++; | |
823 | } | |
824 | ||
825 | mutex_unlock(&inode->i_mutex); | |
826 | ||
827 | return ret; | |
828 | } | |
829 | ||
830 | static int | |
831 | pipe_rdwr_open(struct inode *inode, struct file *filp) | |
832 | { | |
833 | int ret = -ENOENT; | |
834 | ||
835 | mutex_lock(&inode->i_mutex); | |
836 | ||
837 | if (inode->i_pipe) { | |
838 | ret = 0; | |
839 | if (filp->f_mode & FMODE_READ) | |
840 | inode->i_pipe->readers++; | |
841 | if (filp->f_mode & FMODE_WRITE) | |
842 | inode->i_pipe->writers++; | |
843 | } | |
844 | ||
845 | mutex_unlock(&inode->i_mutex); | |
846 | ||
847 | return ret; | |
848 | } | |
849 | ||
850 | /* | |
851 | * The file_operations structs are not static because they | |
852 | * are also used in linux/fs/fifo.c to do operations on FIFOs. | |
853 | * | |
854 | * Pipes reuse fifos' file_operations structs. | |
855 | */ | |
856 | const struct file_operations read_pipefifo_fops = { | |
857 | .llseek = no_llseek, | |
858 | .read = do_sync_read, | |
859 | .aio_read = pipe_read, | |
860 | .write = bad_pipe_w, | |
861 | .poll = pipe_poll, | |
862 | .unlocked_ioctl = pipe_ioctl, | |
863 | .open = pipe_read_open, | |
864 | .release = pipe_read_release, | |
865 | .fasync = pipe_read_fasync, | |
866 | }; | |
867 | ||
868 | const struct file_operations write_pipefifo_fops = { | |
869 | .llseek = no_llseek, | |
870 | .read = bad_pipe_r, | |
871 | .write = do_sync_write, | |
872 | .aio_write = pipe_write, | |
873 | .poll = pipe_poll, | |
874 | .unlocked_ioctl = pipe_ioctl, | |
875 | .open = pipe_write_open, | |
876 | .release = pipe_write_release, | |
877 | .fasync = pipe_write_fasync, | |
878 | }; | |
879 | ||
880 | const struct file_operations rdwr_pipefifo_fops = { | |
881 | .llseek = no_llseek, | |
882 | .read = do_sync_read, | |
883 | .aio_read = pipe_read, | |
884 | .write = do_sync_write, | |
885 | .aio_write = pipe_write, | |
886 | .poll = pipe_poll, | |
887 | .unlocked_ioctl = pipe_ioctl, | |
888 | .open = pipe_rdwr_open, | |
889 | .release = pipe_rdwr_release, | |
890 | .fasync = pipe_rdwr_fasync, | |
891 | }; | |
892 | ||
893 | struct pipe_inode_info * alloc_pipe_info(struct inode *inode) | |
894 | { | |
895 | struct pipe_inode_info *pipe; | |
896 | ||
897 | pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); | |
898 | if (pipe) { | |
899 | pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL); | |
900 | if (pipe->bufs) { | |
901 | init_waitqueue_head(&pipe->wait); | |
902 | pipe->r_counter = pipe->w_counter = 1; | |
903 | pipe->inode = inode; | |
904 | pipe->buffers = PIPE_DEF_BUFFERS; | |
905 | return pipe; | |
906 | } | |
907 | kfree(pipe); | |
908 | } | |
909 | ||
910 | return NULL; | |
911 | } | |
912 | ||
913 | void __free_pipe_info(struct pipe_inode_info *pipe) | |
914 | { | |
915 | int i; | |
916 | ||
917 | for (i = 0; i < pipe->buffers; i++) { | |
918 | struct pipe_buffer *buf = pipe->bufs + i; | |
919 | if (buf->ops) | |
920 | buf->ops->release(pipe, buf); | |
921 | } | |
922 | if (pipe->tmp_page) | |
923 | __free_page(pipe->tmp_page); | |
924 | kfree(pipe->bufs); | |
925 | kfree(pipe); | |
926 | } | |
927 | ||
928 | void free_pipe_info(struct inode *inode) | |
929 | { | |
930 | __free_pipe_info(inode->i_pipe); | |
931 | inode->i_pipe = NULL; | |
932 | } | |
933 | ||
934 | static struct vfsmount *pipe_mnt __read_mostly; | |
935 | ||
936 | /* | |
937 | * pipefs_dname() is called from d_path(). | |
938 | */ | |
939 | static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen) | |
940 | { | |
941 | return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", | |
942 | dentry->d_inode->i_ino); | |
943 | } | |
944 | ||
945 | static const struct dentry_operations pipefs_dentry_operations = { | |
946 | .d_dname = pipefs_dname, | |
947 | }; | |
948 | ||
949 | static struct inode * get_pipe_inode(void) | |
950 | { | |
951 | struct inode *inode = new_inode(pipe_mnt->mnt_sb); | |
952 | struct pipe_inode_info *pipe; | |
953 | ||
954 | if (!inode) | |
955 | goto fail_inode; | |
956 | ||
957 | inode->i_ino = get_next_ino(); | |
958 | ||
959 | pipe = alloc_pipe_info(inode); | |
960 | if (!pipe) | |
961 | goto fail_iput; | |
962 | inode->i_pipe = pipe; | |
963 | ||
964 | pipe->readers = pipe->writers = 1; | |
965 | inode->i_fop = &rdwr_pipefifo_fops; | |
966 | ||
967 | /* | |
968 | * Mark the inode dirty from the very beginning, | |
969 | * that way it will never be moved to the dirty | |
970 | * list because "mark_inode_dirty()" will think | |
971 | * that it already _is_ on the dirty list. | |
972 | */ | |
973 | inode->i_state = I_DIRTY; | |
974 | inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR; | |
975 | inode->i_uid = current_fsuid(); | |
976 | inode->i_gid = current_fsgid(); | |
977 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
978 | ||
979 | return inode; | |
980 | ||
981 | fail_iput: | |
982 | iput(inode); | |
983 | ||
984 | fail_inode: | |
985 | return NULL; | |
986 | } | |
987 | ||
988 | struct file *create_write_pipe(int flags) | |
989 | { | |
990 | int err; | |
991 | struct inode *inode; | |
992 | struct file *f; | |
993 | struct path path; | |
994 | struct qstr name = { .name = "" }; | |
995 | ||
996 | err = -ENFILE; | |
997 | inode = get_pipe_inode(); | |
998 | if (!inode) | |
999 | goto err; | |
1000 | ||
1001 | err = -ENOMEM; | |
1002 | path.dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &name); | |
1003 | if (!path.dentry) | |
1004 | goto err_inode; | |
1005 | path.mnt = mntget(pipe_mnt); | |
1006 | ||
1007 | path.dentry->d_op = &pipefs_dentry_operations; | |
1008 | d_instantiate(path.dentry, inode); | |
1009 | ||
1010 | err = -ENFILE; | |
1011 | f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops); | |
1012 | if (!f) | |
1013 | goto err_dentry; | |
1014 | f->f_mapping = inode->i_mapping; | |
1015 | ||
1016 | f->f_flags = O_WRONLY | (flags & O_NONBLOCK); | |
1017 | f->f_version = 0; | |
1018 | ||
1019 | return f; | |
1020 | ||
1021 | err_dentry: | |
1022 | free_pipe_info(inode); | |
1023 | path_put(&path); | |
1024 | return ERR_PTR(err); | |
1025 | ||
1026 | err_inode: | |
1027 | free_pipe_info(inode); | |
1028 | iput(inode); | |
1029 | err: | |
1030 | return ERR_PTR(err); | |
1031 | } | |
1032 | ||
1033 | void free_write_pipe(struct file *f) | |
1034 | { | |
1035 | free_pipe_info(f->f_dentry->d_inode); | |
1036 | path_put(&f->f_path); | |
1037 | put_filp(f); | |
1038 | } | |
1039 | ||
1040 | struct file *create_read_pipe(struct file *wrf, int flags) | |
1041 | { | |
1042 | /* Grab pipe from the writer */ | |
1043 | struct file *f = alloc_file(&wrf->f_path, FMODE_READ, | |
1044 | &read_pipefifo_fops); | |
1045 | if (!f) | |
1046 | return ERR_PTR(-ENFILE); | |
1047 | ||
1048 | path_get(&wrf->f_path); | |
1049 | f->f_flags = O_RDONLY | (flags & O_NONBLOCK); | |
1050 | ||
1051 | return f; | |
1052 | } | |
1053 | ||
1054 | int do_pipe_flags(int *fd, int flags) | |
1055 | { | |
1056 | struct file *fw, *fr; | |
1057 | int error; | |
1058 | int fdw, fdr; | |
1059 | ||
1060 | if (flags & ~(O_CLOEXEC | O_NONBLOCK)) | |
1061 | return -EINVAL; | |
1062 | ||
1063 | fw = create_write_pipe(flags); | |
1064 | if (IS_ERR(fw)) | |
1065 | return PTR_ERR(fw); | |
1066 | fr = create_read_pipe(fw, flags); | |
1067 | error = PTR_ERR(fr); | |
1068 | if (IS_ERR(fr)) | |
1069 | goto err_write_pipe; | |
1070 | ||
1071 | error = get_unused_fd_flags(flags); | |
1072 | if (error < 0) | |
1073 | goto err_read_pipe; | |
1074 | fdr = error; | |
1075 | ||
1076 | error = get_unused_fd_flags(flags); | |
1077 | if (error < 0) | |
1078 | goto err_fdr; | |
1079 | fdw = error; | |
1080 | ||
1081 | audit_fd_pair(fdr, fdw); | |
1082 | fd_install(fdr, fr); | |
1083 | fd_install(fdw, fw); | |
1084 | fd[0] = fdr; | |
1085 | fd[1] = fdw; | |
1086 | ||
1087 | return 0; | |
1088 | ||
1089 | err_fdr: | |
1090 | put_unused_fd(fdr); | |
1091 | err_read_pipe: | |
1092 | path_put(&fr->f_path); | |
1093 | put_filp(fr); | |
1094 | err_write_pipe: | |
1095 | free_write_pipe(fw); | |
1096 | return error; | |
1097 | } | |
1098 | ||
1099 | /* | |
1100 | * sys_pipe() is the normal C calling standard for creating | |
1101 | * a pipe. It's not the way Unix traditionally does this, though. | |
1102 | */ | |
1103 | SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags) | |
1104 | { | |
1105 | int fd[2]; | |
1106 | int error; | |
1107 | ||
1108 | error = do_pipe_flags(fd, flags); | |
1109 | if (!error) { | |
1110 | if (copy_to_user(fildes, fd, sizeof(fd))) { | |
1111 | sys_close(fd[0]); | |
1112 | sys_close(fd[1]); | |
1113 | error = -EFAULT; | |
1114 | } | |
1115 | } | |
1116 | return error; | |
1117 | } | |
1118 | ||
1119 | SYSCALL_DEFINE1(pipe, int __user *, fildes) | |
1120 | { | |
1121 | return sys_pipe2(fildes, 0); | |
1122 | } | |
1123 | ||
1124 | /* | |
1125 | * Allocate a new array of pipe buffers and copy the info over. Returns the | |
1126 | * pipe size if successful, or return -ERROR on error. | |
1127 | */ | |
1128 | static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) | |
1129 | { | |
1130 | struct pipe_buffer *bufs; | |
1131 | ||
1132 | /* | |
1133 | * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't | |
1134 | * expect a lot of shrink+grow operations, just free and allocate | |
1135 | * again like we would do for growing. If the pipe currently | |
1136 | * contains more buffers than arg, then return busy. | |
1137 | */ | |
1138 | if (nr_pages < pipe->nrbufs) | |
1139 | return -EBUSY; | |
1140 | ||
1141 | bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL); | |
1142 | if (unlikely(!bufs)) | |
1143 | return -ENOMEM; | |
1144 | ||
1145 | /* | |
1146 | * The pipe array wraps around, so just start the new one at zero | |
1147 | * and adjust the indexes. | |
1148 | */ | |
1149 | if (pipe->nrbufs) { | |
1150 | unsigned int tail; | |
1151 | unsigned int head; | |
1152 | ||
1153 | tail = pipe->curbuf + pipe->nrbufs; | |
1154 | if (tail < pipe->buffers) | |
1155 | tail = 0; | |
1156 | else | |
1157 | tail &= (pipe->buffers - 1); | |
1158 | ||
1159 | head = pipe->nrbufs - tail; | |
1160 | if (head) | |
1161 | memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer)); | |
1162 | if (tail) | |
1163 | memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer)); | |
1164 | } | |
1165 | ||
1166 | pipe->curbuf = 0; | |
1167 | kfree(pipe->bufs); | |
1168 | pipe->bufs = bufs; | |
1169 | pipe->buffers = nr_pages; | |
1170 | return nr_pages * PAGE_SIZE; | |
1171 | } | |
1172 | ||
1173 | /* | |
1174 | * Currently we rely on the pipe array holding a power-of-2 number | |
1175 | * of pages. | |
1176 | */ | |
1177 | static inline unsigned int round_pipe_size(unsigned int size) | |
1178 | { | |
1179 | unsigned long nr_pages; | |
1180 | ||
1181 | nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
1182 | return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; | |
1183 | } | |
1184 | ||
1185 | /* | |
1186 | * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax | |
1187 | * will return an error. | |
1188 | */ | |
1189 | int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf, | |
1190 | size_t *lenp, loff_t *ppos) | |
1191 | { | |
1192 | int ret; | |
1193 | ||
1194 | ret = proc_dointvec_minmax(table, write, buf, lenp, ppos); | |
1195 | if (ret < 0 || !write) | |
1196 | return ret; | |
1197 | ||
1198 | pipe_max_size = round_pipe_size(pipe_max_size); | |
1199 | return ret; | |
1200 | } | |
1201 | ||
1202 | long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) | |
1203 | { | |
1204 | struct pipe_inode_info *pipe; | |
1205 | long ret; | |
1206 | ||
1207 | pipe = file->f_path.dentry->d_inode->i_pipe; | |
1208 | if (!pipe) | |
1209 | return -EBADF; | |
1210 | ||
1211 | mutex_lock(&pipe->inode->i_mutex); | |
1212 | ||
1213 | switch (cmd) { | |
1214 | case F_SETPIPE_SZ: { | |
1215 | unsigned int size, nr_pages; | |
1216 | ||
1217 | size = round_pipe_size(arg); | |
1218 | nr_pages = size >> PAGE_SHIFT; | |
1219 | ||
1220 | ret = -EINVAL; | |
1221 | if (!nr_pages) | |
1222 | goto out; | |
1223 | ||
1224 | if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) { | |
1225 | ret = -EPERM; | |
1226 | goto out; | |
1227 | } | |
1228 | ret = pipe_set_size(pipe, nr_pages); | |
1229 | break; | |
1230 | } | |
1231 | case F_GETPIPE_SZ: | |
1232 | ret = pipe->buffers * PAGE_SIZE; | |
1233 | break; | |
1234 | default: | |
1235 | ret = -EINVAL; | |
1236 | break; | |
1237 | } | |
1238 | ||
1239 | out: | |
1240 | mutex_unlock(&pipe->inode->i_mutex); | |
1241 | return ret; | |
1242 | } | |
1243 | ||
1244 | /* | |
1245 | * pipefs should _never_ be mounted by userland - too much of security hassle, | |
1246 | * no real gain from having the whole whorehouse mounted. So we don't need | |
1247 | * any operations on the root directory. However, we need a non-trivial | |
1248 | * d_name - pipe: will go nicely and kill the special-casing in procfs. | |
1249 | */ | |
1250 | static struct dentry *pipefs_mount(struct file_system_type *fs_type, | |
1251 | int flags, const char *dev_name, void *data) | |
1252 | { | |
1253 | return mount_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC); | |
1254 | } | |
1255 | ||
1256 | static struct file_system_type pipe_fs_type = { | |
1257 | .name = "pipefs", | |
1258 | .mount = pipefs_mount, | |
1259 | .kill_sb = kill_anon_super, | |
1260 | }; | |
1261 | ||
1262 | static int __init init_pipe_fs(void) | |
1263 | { | |
1264 | int err = register_filesystem(&pipe_fs_type); | |
1265 | ||
1266 | if (!err) { | |
1267 | pipe_mnt = kern_mount(&pipe_fs_type); | |
1268 | if (IS_ERR(pipe_mnt)) { | |
1269 | err = PTR_ERR(pipe_mnt); | |
1270 | unregister_filesystem(&pipe_fs_type); | |
1271 | } | |
1272 | } | |
1273 | return err; | |
1274 | } | |
1275 | ||
1276 | static void __exit exit_pipe_fs(void) | |
1277 | { | |
1278 | unregister_filesystem(&pipe_fs_type); | |
1279 | mntput(pipe_mnt); | |
1280 | } | |
1281 | ||
1282 | fs_initcall(init_pipe_fs); | |
1283 | module_exit(exit_pipe_fs); |