rapidio: modify initialization of switch operations
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / pipe.c
blobd79872eba09a56a03ade25f28a9d9cc8c8b86cb8
1 /*
2 * linux/fs/pipe.c
4 * Copyright (C) 1991, 1992, 1999 Linus Torvalds
5 */
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>
24 #include <asm/uaccess.h>
25 #include <asm/ioctls.h>
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-pages
31 unsigned int pipe_max_pages = PIPE_DEF_BUFFERS * 16;
34 * We use a start+len construction, which provides full use of the
35 * allocated memory.
36 * -- Florian Coosmann (FGC)
38 * Reads with count = 0 should always return 0.
39 * -- Julian Bradfield 1999-06-07.
41 * FIFOs and Pipes now generate SIGIO for both readers and writers.
42 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
44 * pipe_read & write cleanup
45 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
48 static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
50 if (pipe->inode)
51 mutex_lock_nested(&pipe->inode->i_mutex, subclass);
54 void pipe_lock(struct pipe_inode_info *pipe)
57 * pipe_lock() nests non-pipe inode locks (for writing to a file)
59 pipe_lock_nested(pipe, I_MUTEX_PARENT);
61 EXPORT_SYMBOL(pipe_lock);
63 void pipe_unlock(struct pipe_inode_info *pipe)
65 if (pipe->inode)
66 mutex_unlock(&pipe->inode->i_mutex);
68 EXPORT_SYMBOL(pipe_unlock);
70 void pipe_double_lock(struct pipe_inode_info *pipe1,
71 struct pipe_inode_info *pipe2)
73 BUG_ON(pipe1 == pipe2);
75 if (pipe1 < pipe2) {
76 pipe_lock_nested(pipe1, I_MUTEX_PARENT);
77 pipe_lock_nested(pipe2, I_MUTEX_CHILD);
78 } else {
79 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
80 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
84 /* Drop the inode semaphore and wait for a pipe event, atomically */
85 void pipe_wait(struct pipe_inode_info *pipe)
87 DEFINE_WAIT(wait);
90 * Pipes are system-local resources, so sleeping on them
91 * is considered a noninteractive wait:
93 prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
94 pipe_unlock(pipe);
95 schedule();
96 finish_wait(&pipe->wait, &wait);
97 pipe_lock(pipe);
100 static int
101 pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
102 int atomic)
104 unsigned long copy;
106 while (len > 0) {
107 while (!iov->iov_len)
108 iov++;
109 copy = min_t(unsigned long, len, iov->iov_len);
111 if (atomic) {
112 if (__copy_from_user_inatomic(to, iov->iov_base, copy))
113 return -EFAULT;
114 } else {
115 if (copy_from_user(to, iov->iov_base, copy))
116 return -EFAULT;
118 to += copy;
119 len -= copy;
120 iov->iov_base += copy;
121 iov->iov_len -= copy;
123 return 0;
126 static int
127 pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len,
128 int atomic)
130 unsigned long copy;
132 while (len > 0) {
133 while (!iov->iov_len)
134 iov++;
135 copy = min_t(unsigned long, len, iov->iov_len);
137 if (atomic) {
138 if (__copy_to_user_inatomic(iov->iov_base, from, copy))
139 return -EFAULT;
140 } else {
141 if (copy_to_user(iov->iov_base, from, copy))
142 return -EFAULT;
144 from += copy;
145 len -= copy;
146 iov->iov_base += copy;
147 iov->iov_len -= copy;
149 return 0;
153 * Attempt to pre-fault in the user memory, so we can use atomic copies.
154 * Returns the number of bytes not faulted in.
156 static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
158 while (!iov->iov_len)
159 iov++;
161 while (len > 0) {
162 unsigned long this_len;
164 this_len = min_t(unsigned long, len, iov->iov_len);
165 if (fault_in_pages_writeable(iov->iov_base, this_len))
166 break;
168 len -= this_len;
169 iov++;
172 return len;
176 * Pre-fault in the user memory, so we can use atomic copies.
178 static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
180 while (!iov->iov_len)
181 iov++;
183 while (len > 0) {
184 unsigned long this_len;
186 this_len = min_t(unsigned long, len, iov->iov_len);
187 fault_in_pages_readable(iov->iov_base, this_len);
188 len -= this_len;
189 iov++;
193 static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
194 struct pipe_buffer *buf)
196 struct page *page = buf->page;
199 * If nobody else uses this page, and we don't already have a
200 * temporary page, let's keep track of it as a one-deep
201 * allocation cache. (Otherwise just release our reference to it)
203 if (page_count(page) == 1 && !pipe->tmp_page)
204 pipe->tmp_page = page;
205 else
206 page_cache_release(page);
210 * generic_pipe_buf_map - virtually map a pipe buffer
211 * @pipe: the pipe that the buffer belongs to
212 * @buf: the buffer that should be mapped
213 * @atomic: whether to use an atomic map
215 * Description:
216 * This function returns a kernel virtual address mapping for the
217 * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided
218 * and the caller has to be careful not to fault before calling
219 * the unmap function.
221 * Note that this function occupies KM_USER0 if @atomic != 0.
223 void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
224 struct pipe_buffer *buf, int atomic)
226 if (atomic) {
227 buf->flags |= PIPE_BUF_FLAG_ATOMIC;
228 return kmap_atomic(buf->page, KM_USER0);
231 return kmap(buf->page);
235 * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer
236 * @pipe: the pipe that the buffer belongs to
237 * @buf: the buffer that should be unmapped
238 * @map_data: the data that the mapping function returned
240 * Description:
241 * This function undoes the mapping that ->map() provided.
243 void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
244 struct pipe_buffer *buf, void *map_data)
246 if (buf->flags & PIPE_BUF_FLAG_ATOMIC) {
247 buf->flags &= ~PIPE_BUF_FLAG_ATOMIC;
248 kunmap_atomic(map_data, KM_USER0);
249 } else
250 kunmap(buf->page);
254 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
255 * @pipe: the pipe that the buffer belongs to
256 * @buf: the buffer to attempt to steal
258 * Description:
259 * This function attempts to steal the &struct page attached to
260 * @buf. If successful, this function returns 0 and returns with
261 * the page locked. The caller may then reuse the page for whatever
262 * he wishes; the typical use is insertion into a different file
263 * page cache.
265 int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
266 struct pipe_buffer *buf)
268 struct page *page = buf->page;
271 * A reference of one is golden, that means that the owner of this
272 * page is the only one holding a reference to it. lock the page
273 * and return OK.
275 if (page_count(page) == 1) {
276 lock_page(page);
277 return 0;
280 return 1;
284 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
285 * @pipe: the pipe that the buffer belongs to
286 * @buf: the buffer to get a reference to
288 * Description:
289 * This function grabs an extra reference to @buf. It's used in
290 * in the tee() system call, when we duplicate the buffers in one
291 * pipe into another.
293 void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
295 page_cache_get(buf->page);
299 * generic_pipe_buf_confirm - verify contents of the pipe buffer
300 * @info: the pipe that the buffer belongs to
301 * @buf: the buffer to confirm
303 * Description:
304 * This function does nothing, because the generic pipe code uses
305 * pages that are always good when inserted into the pipe.
307 int generic_pipe_buf_confirm(struct pipe_inode_info *info,
308 struct pipe_buffer *buf)
310 return 0;
314 * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
315 * @pipe: the pipe that the buffer belongs to
316 * @buf: the buffer to put a reference to
318 * Description:
319 * This function releases a reference to @buf.
321 void generic_pipe_buf_release(struct pipe_inode_info *pipe,
322 struct pipe_buffer *buf)
324 page_cache_release(buf->page);
327 static const struct pipe_buf_operations anon_pipe_buf_ops = {
328 .can_merge = 1,
329 .map = generic_pipe_buf_map,
330 .unmap = generic_pipe_buf_unmap,
331 .confirm = generic_pipe_buf_confirm,
332 .release = anon_pipe_buf_release,
333 .steal = generic_pipe_buf_steal,
334 .get = generic_pipe_buf_get,
337 static ssize_t
338 pipe_read(struct kiocb *iocb, const struct iovec *_iov,
339 unsigned long nr_segs, loff_t pos)
341 struct file *filp = iocb->ki_filp;
342 struct inode *inode = filp->f_path.dentry->d_inode;
343 struct pipe_inode_info *pipe;
344 int do_wakeup;
345 ssize_t ret;
346 struct iovec *iov = (struct iovec *)_iov;
347 size_t total_len;
349 total_len = iov_length(iov, nr_segs);
350 /* Null read succeeds. */
351 if (unlikely(total_len == 0))
352 return 0;
354 do_wakeup = 0;
355 ret = 0;
356 mutex_lock(&inode->i_mutex);
357 pipe = inode->i_pipe;
358 for (;;) {
359 int bufs = pipe->nrbufs;
360 if (bufs) {
361 int curbuf = pipe->curbuf;
362 struct pipe_buffer *buf = pipe->bufs + curbuf;
363 const struct pipe_buf_operations *ops = buf->ops;
364 void *addr;
365 size_t chars = buf->len;
366 int error, atomic;
368 if (chars > total_len)
369 chars = total_len;
371 error = ops->confirm(pipe, buf);
372 if (error) {
373 if (!ret)
374 error = ret;
375 break;
378 atomic = !iov_fault_in_pages_write(iov, chars);
379 redo:
380 addr = ops->map(pipe, buf, atomic);
381 error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
382 ops->unmap(pipe, buf, addr);
383 if (unlikely(error)) {
385 * Just retry with the slow path if we failed.
387 if (atomic) {
388 atomic = 0;
389 goto redo;
391 if (!ret)
392 ret = error;
393 break;
395 ret += chars;
396 buf->offset += chars;
397 buf->len -= chars;
398 if (!buf->len) {
399 buf->ops = NULL;
400 ops->release(pipe, buf);
401 curbuf = (curbuf + 1) & (pipe->buffers - 1);
402 pipe->curbuf = curbuf;
403 pipe->nrbufs = --bufs;
404 do_wakeup = 1;
406 total_len -= chars;
407 if (!total_len)
408 break; /* common path: read succeeded */
410 if (bufs) /* More to do? */
411 continue;
412 if (!pipe->writers)
413 break;
414 if (!pipe->waiting_writers) {
415 /* syscall merging: Usually we must not sleep
416 * if O_NONBLOCK is set, or if we got some data.
417 * But if a writer sleeps in kernel space, then
418 * we can wait for that data without violating POSIX.
420 if (ret)
421 break;
422 if (filp->f_flags & O_NONBLOCK) {
423 ret = -EAGAIN;
424 break;
427 if (signal_pending(current)) {
428 if (!ret)
429 ret = -ERESTARTSYS;
430 break;
432 if (do_wakeup) {
433 wake_up_interruptible_sync(&pipe->wait);
434 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
436 pipe_wait(pipe);
438 mutex_unlock(&inode->i_mutex);
440 /* Signal writers asynchronously that there is more room. */
441 if (do_wakeup) {
442 wake_up_interruptible_sync(&pipe->wait);
443 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
445 if (ret > 0)
446 file_accessed(filp);
447 return ret;
450 static ssize_t
451 pipe_write(struct kiocb *iocb, const struct iovec *_iov,
452 unsigned long nr_segs, loff_t ppos)
454 struct file *filp = iocb->ki_filp;
455 struct inode *inode = filp->f_path.dentry->d_inode;
456 struct pipe_inode_info *pipe;
457 ssize_t ret;
458 int do_wakeup;
459 struct iovec *iov = (struct iovec *)_iov;
460 size_t total_len;
461 ssize_t chars;
463 total_len = iov_length(iov, nr_segs);
464 /* Null write succeeds. */
465 if (unlikely(total_len == 0))
466 return 0;
468 do_wakeup = 0;
469 ret = 0;
470 mutex_lock(&inode->i_mutex);
471 pipe = inode->i_pipe;
473 if (!pipe->readers) {
474 send_sig(SIGPIPE, current, 0);
475 ret = -EPIPE;
476 goto out;
479 /* We try to merge small writes */
480 chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
481 if (pipe->nrbufs && chars != 0) {
482 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
483 (pipe->buffers - 1);
484 struct pipe_buffer *buf = pipe->bufs + lastbuf;
485 const struct pipe_buf_operations *ops = buf->ops;
486 int offset = buf->offset + buf->len;
488 if (ops->can_merge && offset + chars <= PAGE_SIZE) {
489 int error, atomic = 1;
490 void *addr;
492 error = ops->confirm(pipe, buf);
493 if (error)
494 goto out;
496 iov_fault_in_pages_read(iov, chars);
497 redo1:
498 addr = ops->map(pipe, buf, atomic);
499 error = pipe_iov_copy_from_user(offset + addr, iov,
500 chars, atomic);
501 ops->unmap(pipe, buf, addr);
502 ret = error;
503 do_wakeup = 1;
504 if (error) {
505 if (atomic) {
506 atomic = 0;
507 goto redo1;
509 goto out;
511 buf->len += chars;
512 total_len -= chars;
513 ret = chars;
514 if (!total_len)
515 goto out;
519 for (;;) {
520 int bufs;
522 if (!pipe->readers) {
523 send_sig(SIGPIPE, current, 0);
524 if (!ret)
525 ret = -EPIPE;
526 break;
528 bufs = pipe->nrbufs;
529 if (bufs < pipe->buffers) {
530 int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
531 struct pipe_buffer *buf = pipe->bufs + newbuf;
532 struct page *page = pipe->tmp_page;
533 char *src;
534 int error, atomic = 1;
536 if (!page) {
537 page = alloc_page(GFP_HIGHUSER);
538 if (unlikely(!page)) {
539 ret = ret ? : -ENOMEM;
540 break;
542 pipe->tmp_page = page;
544 /* Always wake up, even if the copy fails. Otherwise
545 * we lock up (O_NONBLOCK-)readers that sleep due to
546 * syscall merging.
547 * FIXME! Is this really true?
549 do_wakeup = 1;
550 chars = PAGE_SIZE;
551 if (chars > total_len)
552 chars = total_len;
554 iov_fault_in_pages_read(iov, chars);
555 redo2:
556 if (atomic)
557 src = kmap_atomic(page, KM_USER0);
558 else
559 src = kmap(page);
561 error = pipe_iov_copy_from_user(src, iov, chars,
562 atomic);
563 if (atomic)
564 kunmap_atomic(src, KM_USER0);
565 else
566 kunmap(page);
568 if (unlikely(error)) {
569 if (atomic) {
570 atomic = 0;
571 goto redo2;
573 if (!ret)
574 ret = error;
575 break;
577 ret += chars;
579 /* Insert it into the buffer array */
580 buf->page = page;
581 buf->ops = &anon_pipe_buf_ops;
582 buf->offset = 0;
583 buf->len = chars;
584 pipe->nrbufs = ++bufs;
585 pipe->tmp_page = NULL;
587 total_len -= chars;
588 if (!total_len)
589 break;
591 if (bufs < pipe->buffers)
592 continue;
593 if (filp->f_flags & O_NONBLOCK) {
594 if (!ret)
595 ret = -EAGAIN;
596 break;
598 if (signal_pending(current)) {
599 if (!ret)
600 ret = -ERESTARTSYS;
601 break;
603 if (do_wakeup) {
604 wake_up_interruptible_sync(&pipe->wait);
605 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
606 do_wakeup = 0;
608 pipe->waiting_writers++;
609 pipe_wait(pipe);
610 pipe->waiting_writers--;
612 out:
613 mutex_unlock(&inode->i_mutex);
614 if (do_wakeup) {
615 wake_up_interruptible_sync(&pipe->wait);
616 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
618 if (ret > 0)
619 file_update_time(filp);
620 return ret;
623 static ssize_t
624 bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
626 return -EBADF;
629 static ssize_t
630 bad_pipe_w(struct file *filp, const char __user *buf, size_t count,
631 loff_t *ppos)
633 return -EBADF;
636 static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
638 struct inode *inode = filp->f_path.dentry->d_inode;
639 struct pipe_inode_info *pipe;
640 int count, buf, nrbufs;
642 switch (cmd) {
643 case FIONREAD:
644 mutex_lock(&inode->i_mutex);
645 pipe = inode->i_pipe;
646 count = 0;
647 buf = pipe->curbuf;
648 nrbufs = pipe->nrbufs;
649 while (--nrbufs >= 0) {
650 count += pipe->bufs[buf].len;
651 buf = (buf+1) & (pipe->buffers - 1);
653 mutex_unlock(&inode->i_mutex);
655 return put_user(count, (int __user *)arg);
656 default:
657 return -EINVAL;
661 /* No kernel lock held - fine */
662 static unsigned int
663 pipe_poll(struct file *filp, poll_table *wait)
665 unsigned int mask;
666 struct inode *inode = filp->f_path.dentry->d_inode;
667 struct pipe_inode_info *pipe = inode->i_pipe;
668 int nrbufs;
670 poll_wait(filp, &pipe->wait, wait);
672 /* Reading only -- no need for acquiring the semaphore. */
673 nrbufs = pipe->nrbufs;
674 mask = 0;
675 if (filp->f_mode & FMODE_READ) {
676 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
677 if (!pipe->writers && filp->f_version != pipe->w_counter)
678 mask |= POLLHUP;
681 if (filp->f_mode & FMODE_WRITE) {
682 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
684 * Most Unices do not set POLLERR for FIFOs but on Linux they
685 * behave exactly like pipes for poll().
687 if (!pipe->readers)
688 mask |= POLLERR;
691 return mask;
694 static int
695 pipe_release(struct inode *inode, int decr, int decw)
697 struct pipe_inode_info *pipe;
699 mutex_lock(&inode->i_mutex);
700 pipe = inode->i_pipe;
701 pipe->readers -= decr;
702 pipe->writers -= decw;
704 if (!pipe->readers && !pipe->writers) {
705 free_pipe_info(inode);
706 } else {
707 wake_up_interruptible_sync(&pipe->wait);
708 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
709 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
711 mutex_unlock(&inode->i_mutex);
713 return 0;
716 static int
717 pipe_read_fasync(int fd, struct file *filp, int on)
719 struct inode *inode = filp->f_path.dentry->d_inode;
720 int retval;
722 mutex_lock(&inode->i_mutex);
723 retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
724 mutex_unlock(&inode->i_mutex);
726 return retval;
730 static int
731 pipe_write_fasync(int fd, struct file *filp, int on)
733 struct inode *inode = filp->f_path.dentry->d_inode;
734 int retval;
736 mutex_lock(&inode->i_mutex);
737 retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
738 mutex_unlock(&inode->i_mutex);
740 return retval;
744 static int
745 pipe_rdwr_fasync(int fd, struct file *filp, int on)
747 struct inode *inode = filp->f_path.dentry->d_inode;
748 struct pipe_inode_info *pipe = inode->i_pipe;
749 int retval;
751 mutex_lock(&inode->i_mutex);
752 retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
753 if (retval >= 0) {
754 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
755 if (retval < 0) /* this can happen only if on == T */
756 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
758 mutex_unlock(&inode->i_mutex);
759 return retval;
763 static int
764 pipe_read_release(struct inode *inode, struct file *filp)
766 return pipe_release(inode, 1, 0);
769 static int
770 pipe_write_release(struct inode *inode, struct file *filp)
772 return pipe_release(inode, 0, 1);
775 static int
776 pipe_rdwr_release(struct inode *inode, struct file *filp)
778 int decr, decw;
780 decr = (filp->f_mode & FMODE_READ) != 0;
781 decw = (filp->f_mode & FMODE_WRITE) != 0;
782 return pipe_release(inode, decr, decw);
785 static int
786 pipe_read_open(struct inode *inode, struct file *filp)
788 int ret = -ENOENT;
790 mutex_lock(&inode->i_mutex);
792 if (inode->i_pipe) {
793 ret = 0;
794 inode->i_pipe->readers++;
797 mutex_unlock(&inode->i_mutex);
799 return ret;
802 static int
803 pipe_write_open(struct inode *inode, struct file *filp)
805 int ret = -ENOENT;
807 mutex_lock(&inode->i_mutex);
809 if (inode->i_pipe) {
810 ret = 0;
811 inode->i_pipe->writers++;
814 mutex_unlock(&inode->i_mutex);
816 return ret;
819 static int
820 pipe_rdwr_open(struct inode *inode, struct file *filp)
822 int ret = -ENOENT;
824 mutex_lock(&inode->i_mutex);
826 if (inode->i_pipe) {
827 ret = 0;
828 if (filp->f_mode & FMODE_READ)
829 inode->i_pipe->readers++;
830 if (filp->f_mode & FMODE_WRITE)
831 inode->i_pipe->writers++;
834 mutex_unlock(&inode->i_mutex);
836 return ret;
840 * The file_operations structs are not static because they
841 * are also used in linux/fs/fifo.c to do operations on FIFOs.
843 * Pipes reuse fifos' file_operations structs.
845 const struct file_operations read_pipefifo_fops = {
846 .llseek = no_llseek,
847 .read = do_sync_read,
848 .aio_read = pipe_read,
849 .write = bad_pipe_w,
850 .poll = pipe_poll,
851 .unlocked_ioctl = pipe_ioctl,
852 .open = pipe_read_open,
853 .release = pipe_read_release,
854 .fasync = pipe_read_fasync,
857 const struct file_operations write_pipefifo_fops = {
858 .llseek = no_llseek,
859 .read = bad_pipe_r,
860 .write = do_sync_write,
861 .aio_write = pipe_write,
862 .poll = pipe_poll,
863 .unlocked_ioctl = pipe_ioctl,
864 .open = pipe_write_open,
865 .release = pipe_write_release,
866 .fasync = pipe_write_fasync,
869 const struct file_operations rdwr_pipefifo_fops = {
870 .llseek = no_llseek,
871 .read = do_sync_read,
872 .aio_read = pipe_read,
873 .write = do_sync_write,
874 .aio_write = pipe_write,
875 .poll = pipe_poll,
876 .unlocked_ioctl = pipe_ioctl,
877 .open = pipe_rdwr_open,
878 .release = pipe_rdwr_release,
879 .fasync = pipe_rdwr_fasync,
882 struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
884 struct pipe_inode_info *pipe;
886 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
887 if (pipe) {
888 pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
889 if (pipe->bufs) {
890 init_waitqueue_head(&pipe->wait);
891 pipe->r_counter = pipe->w_counter = 1;
892 pipe->inode = inode;
893 pipe->buffers = PIPE_DEF_BUFFERS;
894 return pipe;
896 kfree(pipe);
899 return NULL;
902 void __free_pipe_info(struct pipe_inode_info *pipe)
904 int i;
906 for (i = 0; i < pipe->buffers; i++) {
907 struct pipe_buffer *buf = pipe->bufs + i;
908 if (buf->ops)
909 buf->ops->release(pipe, buf);
911 if (pipe->tmp_page)
912 __free_page(pipe->tmp_page);
913 kfree(pipe->bufs);
914 kfree(pipe);
917 void free_pipe_info(struct inode *inode)
919 __free_pipe_info(inode->i_pipe);
920 inode->i_pipe = NULL;
923 static struct vfsmount *pipe_mnt __read_mostly;
926 * pipefs_dname() is called from d_path().
928 static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
930 return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
931 dentry->d_inode->i_ino);
934 static const struct dentry_operations pipefs_dentry_operations = {
935 .d_dname = pipefs_dname,
938 static struct inode * get_pipe_inode(void)
940 struct inode *inode = new_inode(pipe_mnt->mnt_sb);
941 struct pipe_inode_info *pipe;
943 if (!inode)
944 goto fail_inode;
946 pipe = alloc_pipe_info(inode);
947 if (!pipe)
948 goto fail_iput;
949 inode->i_pipe = pipe;
951 pipe->readers = pipe->writers = 1;
952 inode->i_fop = &rdwr_pipefifo_fops;
955 * Mark the inode dirty from the very beginning,
956 * that way it will never be moved to the dirty
957 * list because "mark_inode_dirty()" will think
958 * that it already _is_ on the dirty list.
960 inode->i_state = I_DIRTY;
961 inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
962 inode->i_uid = current_fsuid();
963 inode->i_gid = current_fsgid();
964 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
966 return inode;
968 fail_iput:
969 iput(inode);
971 fail_inode:
972 return NULL;
975 struct file *create_write_pipe(int flags)
977 int err;
978 struct inode *inode;
979 struct file *f;
980 struct path path;
981 struct qstr name = { .name = "" };
983 err = -ENFILE;
984 inode = get_pipe_inode();
985 if (!inode)
986 goto err;
988 err = -ENOMEM;
989 path.dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &name);
990 if (!path.dentry)
991 goto err_inode;
992 path.mnt = mntget(pipe_mnt);
994 path.dentry->d_op = &pipefs_dentry_operations;
995 d_instantiate(path.dentry, inode);
997 err = -ENFILE;
998 f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops);
999 if (!f)
1000 goto err_dentry;
1001 f->f_mapping = inode->i_mapping;
1003 f->f_flags = O_WRONLY | (flags & O_NONBLOCK);
1004 f->f_version = 0;
1006 return f;
1008 err_dentry:
1009 free_pipe_info(inode);
1010 path_put(&path);
1011 return ERR_PTR(err);
1013 err_inode:
1014 free_pipe_info(inode);
1015 iput(inode);
1016 err:
1017 return ERR_PTR(err);
1020 void free_write_pipe(struct file *f)
1022 free_pipe_info(f->f_dentry->d_inode);
1023 path_put(&f->f_path);
1024 put_filp(f);
1027 struct file *create_read_pipe(struct file *wrf, int flags)
1029 /* Grab pipe from the writer */
1030 struct file *f = alloc_file(&wrf->f_path, FMODE_READ,
1031 &read_pipefifo_fops);
1032 if (!f)
1033 return ERR_PTR(-ENFILE);
1035 path_get(&wrf->f_path);
1036 f->f_flags = O_RDONLY | (flags & O_NONBLOCK);
1038 return f;
1041 int do_pipe_flags(int *fd, int flags)
1043 struct file *fw, *fr;
1044 int error;
1045 int fdw, fdr;
1047 if (flags & ~(O_CLOEXEC | O_NONBLOCK))
1048 return -EINVAL;
1050 fw = create_write_pipe(flags);
1051 if (IS_ERR(fw))
1052 return PTR_ERR(fw);
1053 fr = create_read_pipe(fw, flags);
1054 error = PTR_ERR(fr);
1055 if (IS_ERR(fr))
1056 goto err_write_pipe;
1058 error = get_unused_fd_flags(flags);
1059 if (error < 0)
1060 goto err_read_pipe;
1061 fdr = error;
1063 error = get_unused_fd_flags(flags);
1064 if (error < 0)
1065 goto err_fdr;
1066 fdw = error;
1068 audit_fd_pair(fdr, fdw);
1069 fd_install(fdr, fr);
1070 fd_install(fdw, fw);
1071 fd[0] = fdr;
1072 fd[1] = fdw;
1074 return 0;
1076 err_fdr:
1077 put_unused_fd(fdr);
1078 err_read_pipe:
1079 path_put(&fr->f_path);
1080 put_filp(fr);
1081 err_write_pipe:
1082 free_write_pipe(fw);
1083 return error;
1087 * sys_pipe() is the normal C calling standard for creating
1088 * a pipe. It's not the way Unix traditionally does this, though.
1090 SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
1092 int fd[2];
1093 int error;
1095 error = do_pipe_flags(fd, flags);
1096 if (!error) {
1097 if (copy_to_user(fildes, fd, sizeof(fd))) {
1098 sys_close(fd[0]);
1099 sys_close(fd[1]);
1100 error = -EFAULT;
1103 return error;
1106 SYSCALL_DEFINE1(pipe, int __user *, fildes)
1108 return sys_pipe2(fildes, 0);
1112 * Allocate a new array of pipe buffers and copy the info over. Returns the
1113 * pipe size if successful, or return -ERROR on error.
1115 static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
1117 struct pipe_buffer *bufs;
1120 * Must be a power-of-2 currently
1122 if (!is_power_of_2(arg))
1123 return -EINVAL;
1126 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1127 * expect a lot of shrink+grow operations, just free and allocate
1128 * again like we would do for growing. If the pipe currently
1129 * contains more buffers than arg, then return busy.
1131 if (arg < pipe->nrbufs)
1132 return -EBUSY;
1134 bufs = kcalloc(arg, sizeof(struct pipe_buffer), GFP_KERNEL);
1135 if (unlikely(!bufs))
1136 return -ENOMEM;
1139 * The pipe array wraps around, so just start the new one at zero
1140 * and adjust the indexes.
1142 if (pipe->nrbufs) {
1143 const unsigned int tail = pipe->nrbufs & (pipe->buffers - 1);
1144 const unsigned int head = pipe->nrbufs - tail;
1146 if (head)
1147 memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1148 if (tail)
1149 memcpy(bufs + head, pipe->bufs + pipe->curbuf, tail * sizeof(struct pipe_buffer));
1152 pipe->curbuf = 0;
1153 kfree(pipe->bufs);
1154 pipe->bufs = bufs;
1155 pipe->buffers = arg;
1156 return arg;
1159 long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1161 struct pipe_inode_info *pipe;
1162 long ret;
1164 pipe = file->f_path.dentry->d_inode->i_pipe;
1165 if (!pipe)
1166 return -EBADF;
1168 mutex_lock(&pipe->inode->i_mutex);
1170 switch (cmd) {
1171 case F_SETPIPE_SZ:
1172 if (!capable(CAP_SYS_ADMIN) && arg > pipe_max_pages)
1173 return -EINVAL;
1175 * The pipe needs to be at least 2 pages large to
1176 * guarantee POSIX behaviour.
1178 if (arg < 2)
1179 return -EINVAL;
1180 ret = pipe_set_size(pipe, arg);
1181 break;
1182 case F_GETPIPE_SZ:
1183 ret = pipe->buffers;
1184 break;
1185 default:
1186 ret = -EINVAL;
1187 break;
1190 mutex_unlock(&pipe->inode->i_mutex);
1191 return ret;
1195 * pipefs should _never_ be mounted by userland - too much of security hassle,
1196 * no real gain from having the whole whorehouse mounted. So we don't need
1197 * any operations on the root directory. However, we need a non-trivial
1198 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1200 static int pipefs_get_sb(struct file_system_type *fs_type,
1201 int flags, const char *dev_name, void *data,
1202 struct vfsmount *mnt)
1204 return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC, mnt);
1207 static struct file_system_type pipe_fs_type = {
1208 .name = "pipefs",
1209 .get_sb = pipefs_get_sb,
1210 .kill_sb = kill_anon_super,
1213 static int __init init_pipe_fs(void)
1215 int err = register_filesystem(&pipe_fs_type);
1217 if (!err) {
1218 pipe_mnt = kern_mount(&pipe_fs_type);
1219 if (IS_ERR(pipe_mnt)) {
1220 err = PTR_ERR(pipe_mnt);
1221 unregister_filesystem(&pipe_fs_type);
1224 return err;
1227 static void __exit exit_pipe_fs(void)
1229 unregister_filesystem(&pipe_fs_type);
1230 mntput(pipe_mnt);
1233 fs_initcall(init_pipe_fs);
1234 module_exit(exit_pipe_fs);