dm mpath: check if scsi_dh module already loaded before trying to load
[zen-stable.git] / fs / pipe.c
blob82e651b8dff1d1a290669d828f7bdea6a8248a49
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-size
31 unsigned int pipe_max_size = 1048576;
34 * Minimum pipe size, as required by POSIX
36 unsigned int pipe_min_size = PAGE_SIZE;
39 * We use a start+len construction, which provides full use of the
40 * allocated memory.
41 * -- Florian Coosmann (FGC)
43 * Reads with count = 0 should always return 0.
44 * -- Julian Bradfield 1999-06-07.
46 * FIFOs and Pipes now generate SIGIO for both readers and writers.
47 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
49 * pipe_read & write cleanup
50 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
53 static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
55 if (pipe->inode)
56 mutex_lock_nested(&pipe->inode->i_mutex, subclass);
59 void pipe_lock(struct pipe_inode_info *pipe)
62 * pipe_lock() nests non-pipe inode locks (for writing to a file)
64 pipe_lock_nested(pipe, I_MUTEX_PARENT);
66 EXPORT_SYMBOL(pipe_lock);
68 void pipe_unlock(struct pipe_inode_info *pipe)
70 if (pipe->inode)
71 mutex_unlock(&pipe->inode->i_mutex);
73 EXPORT_SYMBOL(pipe_unlock);
75 void pipe_double_lock(struct pipe_inode_info *pipe1,
76 struct pipe_inode_info *pipe2)
78 BUG_ON(pipe1 == pipe2);
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);
89 /* Drop the inode semaphore and wait for a pipe event, atomically */
90 void pipe_wait(struct pipe_inode_info *pipe)
92 DEFINE_WAIT(wait);
95 * Pipes are system-local resources, so sleeping on them
96 * is considered a noninteractive wait:
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);
105 static int
106 pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
107 int atomic)
109 unsigned long copy;
111 while (len > 0) {
112 while (!iov->iov_len)
113 iov++;
114 copy = min_t(unsigned long, len, iov->iov_len);
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;
123 to += copy;
124 len -= copy;
125 iov->iov_base += copy;
126 iov->iov_len -= copy;
128 return 0;
131 static int
132 pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len,
133 int atomic)
135 unsigned long copy;
137 while (len > 0) {
138 while (!iov->iov_len)
139 iov++;
140 copy = min_t(unsigned long, len, iov->iov_len);
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;
149 from += copy;
150 len -= copy;
151 iov->iov_base += copy;
152 iov->iov_len -= copy;
154 return 0;
158 * Attempt to pre-fault in the user memory, so we can use atomic copies.
159 * Returns the number of bytes not faulted in.
161 static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
163 while (!iov->iov_len)
164 iov++;
166 while (len > 0) {
167 unsigned long this_len;
169 this_len = min_t(unsigned long, len, iov->iov_len);
170 if (fault_in_pages_writeable(iov->iov_base, this_len))
171 break;
173 len -= this_len;
174 iov++;
177 return len;
181 * Pre-fault in the user memory, so we can use atomic copies.
183 static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
185 while (!iov->iov_len)
186 iov++;
188 while (len > 0) {
189 unsigned long this_len;
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++;
198 static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
199 struct pipe_buffer *buf)
201 struct page *page = buf->page;
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)
208 if (page_count(page) == 1 && !pipe->tmp_page)
209 pipe->tmp_page = page;
210 else
211 page_cache_release(page);
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
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.
226 * Note that this function occupies KM_USER0 if @atomic != 0.
228 void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
229 struct pipe_buffer *buf, int atomic)
231 if (atomic) {
232 buf->flags |= PIPE_BUF_FLAG_ATOMIC;
233 return kmap_atomic(buf->page, KM_USER0);
236 return kmap(buf->page);
238 EXPORT_SYMBOL(generic_pipe_buf_map);
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
246 * Description:
247 * This function undoes the mapping that ->map() provided.
249 void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
250 struct pipe_buffer *buf, void *map_data)
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);
258 EXPORT_SYMBOL(generic_pipe_buf_unmap);
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
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.
272 int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
273 struct pipe_buffer *buf)
275 struct page *page = buf->page;
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.
282 if (page_count(page) == 1) {
283 lock_page(page);
284 return 0;
287 return 1;
289 EXPORT_SYMBOL(generic_pipe_buf_steal);
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
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.
301 void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
303 page_cache_get(buf->page);
305 EXPORT_SYMBOL(generic_pipe_buf_get);
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
312 * Description:
313 * This function does nothing, because the generic pipe code uses
314 * pages that are always good when inserted into the pipe.
316 int generic_pipe_buf_confirm(struct pipe_inode_info *info,
317 struct pipe_buffer *buf)
319 return 0;
321 EXPORT_SYMBOL(generic_pipe_buf_confirm);
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
328 * Description:
329 * This function releases a reference to @buf.
331 void generic_pipe_buf_release(struct pipe_inode_info *pipe,
332 struct pipe_buffer *buf)
334 page_cache_release(buf->page);
336 EXPORT_SYMBOL(generic_pipe_buf_release);
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,
348 static const struct pipe_buf_operations packet_pipe_buf_ops = {
349 .can_merge = 0,
350 .map = generic_pipe_buf_map,
351 .unmap = generic_pipe_buf_unmap,
352 .confirm = generic_pipe_buf_confirm,
353 .release = anon_pipe_buf_release,
354 .steal = generic_pipe_buf_steal,
355 .get = generic_pipe_buf_get,
358 static ssize_t
359 pipe_read(struct kiocb *iocb, const struct iovec *_iov,
360 unsigned long nr_segs, loff_t pos)
362 struct file *filp = iocb->ki_filp;
363 struct inode *inode = filp->f_path.dentry->d_inode;
364 struct pipe_inode_info *pipe;
365 int do_wakeup;
366 ssize_t ret;
367 struct iovec *iov = (struct iovec *)_iov;
368 size_t total_len;
370 total_len = iov_length(iov, nr_segs);
371 /* Null read succeeds. */
372 if (unlikely(total_len == 0))
373 return 0;
375 do_wakeup = 0;
376 ret = 0;
377 mutex_lock(&inode->i_mutex);
378 pipe = inode->i_pipe;
379 for (;;) {
380 int bufs = pipe->nrbufs;
381 if (bufs) {
382 int curbuf = pipe->curbuf;
383 struct pipe_buffer *buf = pipe->bufs + curbuf;
384 const struct pipe_buf_operations *ops = buf->ops;
385 void *addr;
386 size_t chars = buf->len;
387 int error, atomic;
389 if (chars > total_len)
390 chars = total_len;
392 error = ops->confirm(pipe, buf);
393 if (error) {
394 if (!ret)
395 ret = error;
396 break;
399 atomic = !iov_fault_in_pages_write(iov, chars);
400 redo:
401 addr = ops->map(pipe, buf, atomic);
402 error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
403 ops->unmap(pipe, buf, addr);
404 if (unlikely(error)) {
406 * Just retry with the slow path if we failed.
408 if (atomic) {
409 atomic = 0;
410 goto redo;
412 if (!ret)
413 ret = error;
414 break;
416 ret += chars;
417 buf->offset += chars;
418 buf->len -= chars;
420 /* Was it a packet buffer? Clean up and exit */
421 if (buf->flags & PIPE_BUF_FLAG_PACKET) {
422 total_len = chars;
423 buf->len = 0;
426 if (!buf->len) {
427 buf->ops = NULL;
428 ops->release(pipe, buf);
429 curbuf = (curbuf + 1) & (pipe->buffers - 1);
430 pipe->curbuf = curbuf;
431 pipe->nrbufs = --bufs;
432 do_wakeup = 1;
434 total_len -= chars;
435 if (!total_len)
436 break; /* common path: read succeeded */
438 if (bufs) /* More to do? */
439 continue;
440 if (!pipe->writers)
441 break;
442 if (!pipe->waiting_writers) {
443 /* syscall merging: Usually we must not sleep
444 * if O_NONBLOCK is set, or if we got some data.
445 * But if a writer sleeps in kernel space, then
446 * we can wait for that data without violating POSIX.
448 if (ret)
449 break;
450 if (filp->f_flags & O_NONBLOCK) {
451 ret = -EAGAIN;
452 break;
455 if (signal_pending(current)) {
456 if (!ret)
457 ret = -ERESTARTSYS;
458 break;
460 if (do_wakeup) {
461 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
462 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
464 pipe_wait(pipe);
466 mutex_unlock(&inode->i_mutex);
468 /* Signal writers asynchronously that there is more room. */
469 if (do_wakeup) {
470 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
471 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
473 if (ret > 0)
474 file_accessed(filp);
475 return ret;
478 static inline int is_packetized(struct file *file)
480 return (file->f_flags & O_DIRECT) != 0;
483 static ssize_t
484 pipe_write(struct kiocb *iocb, const struct iovec *_iov,
485 unsigned long nr_segs, loff_t ppos)
487 struct file *filp = iocb->ki_filp;
488 struct inode *inode = filp->f_path.dentry->d_inode;
489 struct pipe_inode_info *pipe;
490 ssize_t ret;
491 int do_wakeup;
492 struct iovec *iov = (struct iovec *)_iov;
493 size_t total_len;
494 ssize_t chars;
496 total_len = iov_length(iov, nr_segs);
497 /* Null write succeeds. */
498 if (unlikely(total_len == 0))
499 return 0;
501 do_wakeup = 0;
502 ret = 0;
503 mutex_lock(&inode->i_mutex);
504 pipe = inode->i_pipe;
506 if (!pipe->readers) {
507 send_sig(SIGPIPE, current, 0);
508 ret = -EPIPE;
509 goto out;
512 /* We try to merge small writes */
513 chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
514 if (pipe->nrbufs && chars != 0) {
515 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
516 (pipe->buffers - 1);
517 struct pipe_buffer *buf = pipe->bufs + lastbuf;
518 const struct pipe_buf_operations *ops = buf->ops;
519 int offset = buf->offset + buf->len;
521 if (ops->can_merge && offset + chars <= PAGE_SIZE) {
522 int error, atomic = 1;
523 void *addr;
525 error = ops->confirm(pipe, buf);
526 if (error)
527 goto out;
529 iov_fault_in_pages_read(iov, chars);
530 redo1:
531 addr = ops->map(pipe, buf, atomic);
532 error = pipe_iov_copy_from_user(offset + addr, iov,
533 chars, atomic);
534 ops->unmap(pipe, buf, addr);
535 ret = error;
536 do_wakeup = 1;
537 if (error) {
538 if (atomic) {
539 atomic = 0;
540 goto redo1;
542 goto out;
544 buf->len += chars;
545 total_len -= chars;
546 ret = chars;
547 if (!total_len)
548 goto out;
552 for (;;) {
553 int bufs;
555 if (!pipe->readers) {
556 send_sig(SIGPIPE, current, 0);
557 if (!ret)
558 ret = -EPIPE;
559 break;
561 bufs = pipe->nrbufs;
562 if (bufs < pipe->buffers) {
563 int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
564 struct pipe_buffer *buf = pipe->bufs + newbuf;
565 struct page *page = pipe->tmp_page;
566 char *src;
567 int error, atomic = 1;
569 if (!page) {
570 page = alloc_page(GFP_HIGHUSER);
571 if (unlikely(!page)) {
572 ret = ret ? : -ENOMEM;
573 break;
575 pipe->tmp_page = page;
577 /* Always wake up, even if the copy fails. Otherwise
578 * we lock up (O_NONBLOCK-)readers that sleep due to
579 * syscall merging.
580 * FIXME! Is this really true?
582 do_wakeup = 1;
583 chars = PAGE_SIZE;
584 if (chars > total_len)
585 chars = total_len;
587 iov_fault_in_pages_read(iov, chars);
588 redo2:
589 if (atomic)
590 src = kmap_atomic(page, KM_USER0);
591 else
592 src = kmap(page);
594 error = pipe_iov_copy_from_user(src, iov, chars,
595 atomic);
596 if (atomic)
597 kunmap_atomic(src, KM_USER0);
598 else
599 kunmap(page);
601 if (unlikely(error)) {
602 if (atomic) {
603 atomic = 0;
604 goto redo2;
606 if (!ret)
607 ret = error;
608 break;
610 ret += chars;
612 /* Insert it into the buffer array */
613 buf->page = page;
614 buf->ops = &anon_pipe_buf_ops;
615 buf->offset = 0;
616 buf->len = chars;
617 buf->flags = 0;
618 if (is_packetized(filp)) {
619 buf->ops = &packet_pipe_buf_ops;
620 buf->flags = PIPE_BUF_FLAG_PACKET;
622 pipe->nrbufs = ++bufs;
623 pipe->tmp_page = NULL;
625 total_len -= chars;
626 if (!total_len)
627 break;
629 if (bufs < pipe->buffers)
630 continue;
631 if (filp->f_flags & O_NONBLOCK) {
632 if (!ret)
633 ret = -EAGAIN;
634 break;
636 if (signal_pending(current)) {
637 if (!ret)
638 ret = -ERESTARTSYS;
639 break;
641 if (do_wakeup) {
642 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
643 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
644 do_wakeup = 0;
646 pipe->waiting_writers++;
647 pipe_wait(pipe);
648 pipe->waiting_writers--;
650 out:
651 mutex_unlock(&inode->i_mutex);
652 if (do_wakeup) {
653 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
654 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
656 if (ret > 0)
657 file_update_time(filp);
658 return ret;
661 static ssize_t
662 bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
664 return -EBADF;
667 static ssize_t
668 bad_pipe_w(struct file *filp, const char __user *buf, size_t count,
669 loff_t *ppos)
671 return -EBADF;
674 static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
676 struct inode *inode = filp->f_path.dentry->d_inode;
677 struct pipe_inode_info *pipe;
678 int count, buf, nrbufs;
680 switch (cmd) {
681 case FIONREAD:
682 mutex_lock(&inode->i_mutex);
683 pipe = inode->i_pipe;
684 count = 0;
685 buf = pipe->curbuf;
686 nrbufs = pipe->nrbufs;
687 while (--nrbufs >= 0) {
688 count += pipe->bufs[buf].len;
689 buf = (buf+1) & (pipe->buffers - 1);
691 mutex_unlock(&inode->i_mutex);
693 return put_user(count, (int __user *)arg);
694 default:
695 return -EINVAL;
699 /* No kernel lock held - fine */
700 static unsigned int
701 pipe_poll(struct file *filp, poll_table *wait)
703 unsigned int mask;
704 struct inode *inode = filp->f_path.dentry->d_inode;
705 struct pipe_inode_info *pipe = inode->i_pipe;
706 int nrbufs;
708 poll_wait(filp, &pipe->wait, wait);
710 /* Reading only -- no need for acquiring the semaphore. */
711 nrbufs = pipe->nrbufs;
712 mask = 0;
713 if (filp->f_mode & FMODE_READ) {
714 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
715 if (!pipe->writers && filp->f_version != pipe->w_counter)
716 mask |= POLLHUP;
719 if (filp->f_mode & FMODE_WRITE) {
720 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
722 * Most Unices do not set POLLERR for FIFOs but on Linux they
723 * behave exactly like pipes for poll().
725 if (!pipe->readers)
726 mask |= POLLERR;
729 return mask;
732 static int
733 pipe_release(struct inode *inode, int decr, int decw)
735 struct pipe_inode_info *pipe;
737 mutex_lock(&inode->i_mutex);
738 pipe = inode->i_pipe;
739 pipe->readers -= decr;
740 pipe->writers -= decw;
742 if (!pipe->readers && !pipe->writers) {
743 free_pipe_info(inode);
744 } else {
745 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
746 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
747 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
749 mutex_unlock(&inode->i_mutex);
751 return 0;
754 static int
755 pipe_read_fasync(int fd, struct file *filp, int on)
757 struct inode *inode = filp->f_path.dentry->d_inode;
758 int retval;
760 mutex_lock(&inode->i_mutex);
761 retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
762 mutex_unlock(&inode->i_mutex);
764 return retval;
768 static int
769 pipe_write_fasync(int fd, struct file *filp, int on)
771 struct inode *inode = filp->f_path.dentry->d_inode;
772 int retval;
774 mutex_lock(&inode->i_mutex);
775 retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
776 mutex_unlock(&inode->i_mutex);
778 return retval;
782 static int
783 pipe_rdwr_fasync(int fd, struct file *filp, int on)
785 struct inode *inode = filp->f_path.dentry->d_inode;
786 struct pipe_inode_info *pipe = inode->i_pipe;
787 int retval;
789 mutex_lock(&inode->i_mutex);
790 retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
791 if (retval >= 0) {
792 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
793 if (retval < 0) /* this can happen only if on == T */
794 fasync_helper(-1, filp, 0, &pipe->fasync_readers);
796 mutex_unlock(&inode->i_mutex);
797 return retval;
801 static int
802 pipe_read_release(struct inode *inode, struct file *filp)
804 return pipe_release(inode, 1, 0);
807 static int
808 pipe_write_release(struct inode *inode, struct file *filp)
810 return pipe_release(inode, 0, 1);
813 static int
814 pipe_rdwr_release(struct inode *inode, struct file *filp)
816 int decr, decw;
818 decr = (filp->f_mode & FMODE_READ) != 0;
819 decw = (filp->f_mode & FMODE_WRITE) != 0;
820 return pipe_release(inode, decr, decw);
823 static int
824 pipe_read_open(struct inode *inode, struct file *filp)
826 int ret = -ENOENT;
828 mutex_lock(&inode->i_mutex);
830 if (inode->i_pipe) {
831 ret = 0;
832 inode->i_pipe->readers++;
835 mutex_unlock(&inode->i_mutex);
837 return ret;
840 static int
841 pipe_write_open(struct inode *inode, struct file *filp)
843 int ret = -ENOENT;
845 mutex_lock(&inode->i_mutex);
847 if (inode->i_pipe) {
848 ret = 0;
849 inode->i_pipe->writers++;
852 mutex_unlock(&inode->i_mutex);
854 return ret;
857 static int
858 pipe_rdwr_open(struct inode *inode, struct file *filp)
860 int ret = -ENOENT;
862 mutex_lock(&inode->i_mutex);
864 if (inode->i_pipe) {
865 ret = 0;
866 if (filp->f_mode & FMODE_READ)
867 inode->i_pipe->readers++;
868 if (filp->f_mode & FMODE_WRITE)
869 inode->i_pipe->writers++;
872 mutex_unlock(&inode->i_mutex);
874 return ret;
878 * The file_operations structs are not static because they
879 * are also used in linux/fs/fifo.c to do operations on FIFOs.
881 * Pipes reuse fifos' file_operations structs.
883 const struct file_operations read_pipefifo_fops = {
884 .llseek = no_llseek,
885 .read = do_sync_read,
886 .aio_read = pipe_read,
887 .write = bad_pipe_w,
888 .poll = pipe_poll,
889 .unlocked_ioctl = pipe_ioctl,
890 .open = pipe_read_open,
891 .release = pipe_read_release,
892 .fasync = pipe_read_fasync,
895 const struct file_operations write_pipefifo_fops = {
896 .llseek = no_llseek,
897 .read = bad_pipe_r,
898 .write = do_sync_write,
899 .aio_write = pipe_write,
900 .poll = pipe_poll,
901 .unlocked_ioctl = pipe_ioctl,
902 .open = pipe_write_open,
903 .release = pipe_write_release,
904 .fasync = pipe_write_fasync,
907 const struct file_operations rdwr_pipefifo_fops = {
908 .llseek = no_llseek,
909 .read = do_sync_read,
910 .aio_read = pipe_read,
911 .write = do_sync_write,
912 .aio_write = pipe_write,
913 .poll = pipe_poll,
914 .unlocked_ioctl = pipe_ioctl,
915 .open = pipe_rdwr_open,
916 .release = pipe_rdwr_release,
917 .fasync = pipe_rdwr_fasync,
920 struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
922 struct pipe_inode_info *pipe;
924 pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
925 if (pipe) {
926 pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
927 if (pipe->bufs) {
928 init_waitqueue_head(&pipe->wait);
929 pipe->r_counter = pipe->w_counter = 1;
930 pipe->inode = inode;
931 pipe->buffers = PIPE_DEF_BUFFERS;
932 return pipe;
934 kfree(pipe);
937 return NULL;
940 void __free_pipe_info(struct pipe_inode_info *pipe)
942 int i;
944 for (i = 0; i < pipe->buffers; i++) {
945 struct pipe_buffer *buf = pipe->bufs + i;
946 if (buf->ops)
947 buf->ops->release(pipe, buf);
949 if (pipe->tmp_page)
950 __free_page(pipe->tmp_page);
951 kfree(pipe->bufs);
952 kfree(pipe);
955 void free_pipe_info(struct inode *inode)
957 __free_pipe_info(inode->i_pipe);
958 inode->i_pipe = NULL;
961 static struct vfsmount *pipe_mnt __read_mostly;
964 * pipefs_dname() is called from d_path().
966 static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
968 return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
969 dentry->d_inode->i_ino);
972 static const struct dentry_operations pipefs_dentry_operations = {
973 .d_dname = pipefs_dname,
976 static struct inode * get_pipe_inode(void)
978 struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
979 struct pipe_inode_info *pipe;
981 if (!inode)
982 goto fail_inode;
984 inode->i_ino = get_next_ino();
986 pipe = alloc_pipe_info(inode);
987 if (!pipe)
988 goto fail_iput;
989 inode->i_pipe = pipe;
991 pipe->readers = pipe->writers = 1;
992 inode->i_fop = &rdwr_pipefifo_fops;
995 * Mark the inode dirty from the very beginning,
996 * that way it will never be moved to the dirty
997 * list because "mark_inode_dirty()" will think
998 * that it already _is_ on the dirty list.
1000 inode->i_state = I_DIRTY;
1001 inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
1002 inode->i_uid = current_fsuid();
1003 inode->i_gid = current_fsgid();
1004 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1006 return inode;
1008 fail_iput:
1009 iput(inode);
1011 fail_inode:
1012 return NULL;
1015 struct file *create_write_pipe(int flags)
1017 int err;
1018 struct inode *inode;
1019 struct file *f;
1020 struct path path;
1021 struct qstr name = { .name = "" };
1023 err = -ENFILE;
1024 inode = get_pipe_inode();
1025 if (!inode)
1026 goto err;
1028 err = -ENOMEM;
1029 path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
1030 if (!path.dentry)
1031 goto err_inode;
1032 path.mnt = mntget(pipe_mnt);
1034 d_instantiate(path.dentry, inode);
1036 err = -ENFILE;
1037 f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops);
1038 if (!f)
1039 goto err_dentry;
1040 f->f_mapping = inode->i_mapping;
1042 f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
1043 f->f_version = 0;
1045 return f;
1047 err_dentry:
1048 free_pipe_info(inode);
1049 path_put(&path);
1050 return ERR_PTR(err);
1052 err_inode:
1053 free_pipe_info(inode);
1054 iput(inode);
1055 err:
1056 return ERR_PTR(err);
1059 void free_write_pipe(struct file *f)
1061 free_pipe_info(f->f_dentry->d_inode);
1062 path_put(&f->f_path);
1063 put_filp(f);
1066 struct file *create_read_pipe(struct file *wrf, int flags)
1068 /* Grab pipe from the writer */
1069 struct file *f = alloc_file(&wrf->f_path, FMODE_READ,
1070 &read_pipefifo_fops);
1071 if (!f)
1072 return ERR_PTR(-ENFILE);
1074 path_get(&wrf->f_path);
1075 f->f_flags = O_RDONLY | (flags & O_NONBLOCK);
1077 return f;
1080 int do_pipe_flags(int *fd, int flags)
1082 struct file *fw, *fr;
1083 int error;
1084 int fdw, fdr;
1086 if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
1087 return -EINVAL;
1089 fw = create_write_pipe(flags);
1090 if (IS_ERR(fw))
1091 return PTR_ERR(fw);
1092 fr = create_read_pipe(fw, flags);
1093 error = PTR_ERR(fr);
1094 if (IS_ERR(fr))
1095 goto err_write_pipe;
1097 error = get_unused_fd_flags(flags);
1098 if (error < 0)
1099 goto err_read_pipe;
1100 fdr = error;
1102 error = get_unused_fd_flags(flags);
1103 if (error < 0)
1104 goto err_fdr;
1105 fdw = error;
1107 audit_fd_pair(fdr, fdw);
1108 fd_install(fdr, fr);
1109 fd_install(fdw, fw);
1110 fd[0] = fdr;
1111 fd[1] = fdw;
1113 return 0;
1115 err_fdr:
1116 put_unused_fd(fdr);
1117 err_read_pipe:
1118 path_put(&fr->f_path);
1119 put_filp(fr);
1120 err_write_pipe:
1121 free_write_pipe(fw);
1122 return error;
1126 * sys_pipe() is the normal C calling standard for creating
1127 * a pipe. It's not the way Unix traditionally does this, though.
1129 SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
1131 int fd[2];
1132 int error;
1134 error = do_pipe_flags(fd, flags);
1135 if (!error) {
1136 if (copy_to_user(fildes, fd, sizeof(fd))) {
1137 sys_close(fd[0]);
1138 sys_close(fd[1]);
1139 error = -EFAULT;
1142 return error;
1145 SYSCALL_DEFINE1(pipe, int __user *, fildes)
1147 return sys_pipe2(fildes, 0);
1151 * Allocate a new array of pipe buffers and copy the info over. Returns the
1152 * pipe size if successful, or return -ERROR on error.
1154 static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
1156 struct pipe_buffer *bufs;
1159 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1160 * expect a lot of shrink+grow operations, just free and allocate
1161 * again like we would do for growing. If the pipe currently
1162 * contains more buffers than arg, then return busy.
1164 if (nr_pages < pipe->nrbufs)
1165 return -EBUSY;
1167 bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL | __GFP_NOWARN);
1168 if (unlikely(!bufs))
1169 return -ENOMEM;
1172 * The pipe array wraps around, so just start the new one at zero
1173 * and adjust the indexes.
1175 if (pipe->nrbufs) {
1176 unsigned int tail;
1177 unsigned int head;
1179 tail = pipe->curbuf + pipe->nrbufs;
1180 if (tail < pipe->buffers)
1181 tail = 0;
1182 else
1183 tail &= (pipe->buffers - 1);
1185 head = pipe->nrbufs - tail;
1186 if (head)
1187 memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1188 if (tail)
1189 memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1192 pipe->curbuf = 0;
1193 kfree(pipe->bufs);
1194 pipe->bufs = bufs;
1195 pipe->buffers = nr_pages;
1196 return nr_pages * PAGE_SIZE;
1200 * Currently we rely on the pipe array holding a power-of-2 number
1201 * of pages.
1203 static inline unsigned int round_pipe_size(unsigned int size)
1205 unsigned long nr_pages;
1207 nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1208 return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
1212 * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax
1213 * will return an error.
1215 int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
1216 size_t *lenp, loff_t *ppos)
1218 int ret;
1220 ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
1221 if (ret < 0 || !write)
1222 return ret;
1224 pipe_max_size = round_pipe_size(pipe_max_size);
1225 return ret;
1229 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1230 * location, so checking ->i_pipe is not enough to verify that this is a
1231 * pipe.
1233 struct pipe_inode_info *get_pipe_info(struct file *file)
1235 struct inode *i = file->f_path.dentry->d_inode;
1237 return S_ISFIFO(i->i_mode) ? i->i_pipe : NULL;
1240 long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1242 struct pipe_inode_info *pipe;
1243 long ret;
1245 pipe = get_pipe_info(file);
1246 if (!pipe)
1247 return -EBADF;
1249 mutex_lock(&pipe->inode->i_mutex);
1251 switch (cmd) {
1252 case F_SETPIPE_SZ: {
1253 unsigned int size, nr_pages;
1255 size = round_pipe_size(arg);
1256 nr_pages = size >> PAGE_SHIFT;
1258 ret = -EINVAL;
1259 if (!nr_pages)
1260 goto out;
1262 if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
1263 ret = -EPERM;
1264 goto out;
1266 ret = pipe_set_size(pipe, nr_pages);
1267 break;
1269 case F_GETPIPE_SZ:
1270 ret = pipe->buffers * PAGE_SIZE;
1271 break;
1272 default:
1273 ret = -EINVAL;
1274 break;
1277 out:
1278 mutex_unlock(&pipe->inode->i_mutex);
1279 return ret;
1282 static const struct super_operations pipefs_ops = {
1283 .destroy_inode = free_inode_nonrcu,
1284 .statfs = simple_statfs,
1288 * pipefs should _never_ be mounted by userland - too much of security hassle,
1289 * no real gain from having the whole whorehouse mounted. So we don't need
1290 * any operations on the root directory. However, we need a non-trivial
1291 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1293 static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1294 int flags, const char *dev_name, void *data)
1296 return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1297 &pipefs_dentry_operations, PIPEFS_MAGIC);
1300 static struct file_system_type pipe_fs_type = {
1301 .name = "pipefs",
1302 .mount = pipefs_mount,
1303 .kill_sb = kill_anon_super,
1306 static int __init init_pipe_fs(void)
1308 int err = register_filesystem(&pipe_fs_type);
1310 if (!err) {
1311 pipe_mnt = kern_mount(&pipe_fs_type);
1312 if (IS_ERR(pipe_mnt)) {
1313 err = PTR_ERR(pipe_mnt);
1314 unregister_filesystem(&pipe_fs_type);
1317 return err;
1320 fs_initcall(init_pipe_fs);