/*
* linux/fs/pipe.c
*
* Copyright (C) 1991, 1992, 1999 Linus Torvalds
*/
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pipe_fs_i.h>
#include <linux/uio.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
/*
* We use a start+len construction, which provides full use of the
* allocated memory.
* -- Florian Coosmann (FGC)
*
* Reads with count = 0 should always return 0.
* -- Julian Bradfield 1999-06-07.
*
* FIFOs and Pipes now generate SIGIO for both readers and writers.
* -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
*
* pipe_read & write cleanup
* -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
*/
/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct pipe_inode_info *pipe)
{
DEFINE_WAIT(wait);
/*
* Pipes are system-local resources, so sleeping on them
* is considered a noninteractive wait:
*/
prepare_to_wait(&pipe->wait, &wait,
TASK_INTERRUPTIBLE | TASK_NONINTERACTIVE);
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
schedule();
finish_wait(&pipe->wait, &wait);
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
}
static int
pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len)
{
unsigned long copy;
while (len > 0) {
while (!iov->iov_len)
iov++;
copy = min_t(unsigned long, len, iov->iov_len);
if (copy_from_user(to, iov->iov_base, copy))
return -EFAULT;
to += copy;
len -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
return 0;
}
static int
pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len)
{
unsigned long copy;
while (len > 0) {
while (!iov->iov_len)
iov++;
copy = min_t(unsigned long, len, iov->iov_len);
if (copy_to_user(iov->iov_base, from, copy))
return -EFAULT;
from += copy;
len -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
return 0;
}
static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct page *page = buf->page;
buf->flags &= ~PIPE_BUF_FLAG_STOLEN;
/*
* If nobody else uses this page, and we don't already have a
* temporary page, let's keep track of it as a one-deep
* allocation cache. (Otherwise just release our reference to it)
*/
if (page_count(page) == 1 && !pipe->tmp_page)
pipe->tmp_page = page;
else
page_cache_release(page);
}
static void * anon_pipe_buf_map(struct file *file, struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
return kmap(buf->page);
}
static void anon_pipe_buf_unmap(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
kunmap(buf->page);
}
static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
buf->flags |= PIPE_BUF_FLAG_STOLEN;
return 0;
}
static void anon_pipe_buf_get(struct pipe_inode_info *info,
struct pipe_buffer *buf)
{
page_cache_get(buf->page);
}
static struct pipe_buf_operations anon_pipe_buf_ops = {
.can_merge = 1,
.map = anon_pipe_buf_map,
.unmap = anon_pipe_buf_unmap,
.release = anon_pipe_buf_release,
.steal = anon_pipe_buf_steal,
.get = anon_pipe_buf_get,
};
static ssize_t
pipe_readv(struct file *filp, const struct iovec *_iov,
unsigned long nr_segs, loff_t *ppos)
{
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *pipe;
int do_wakeup;
ssize_t ret;
struct iovec *iov = (struct iovec *)_iov;
size_t total_len;
total_len = iov_length(iov, nr_segs);
/* Null read succeeds. */
if (unlikely(total_len == 0))
return 0;
do_wakeup = 0;
ret = 0;
mutex_lock(&inode->i_mutex);
pipe = inode->i_pipe;
for (;;) {
int bufs = pipe->nrbufs;
if (bufs) {
int curbuf = pipe->curbuf;
struct pipe_buffer *buf = pipe->bufs + curbuf;
struct pipe_buf_operations *ops = buf->ops;
void *addr;