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linux-stable/fs/pipe.c
Andi Kleen d6cbd281d1 [PATCH] Some cleanup in the pipe code 
Split the big and hard to read do_pipe function into smaller pieces.

This creates new create_write_pipe/free_write_pipe/create_read_pipe
functions.  These functions are made global so that they can be used by
other parts of the kernel.

The resulting code is more generic and easier to read and has cleaner error
handling and less gotos.

[akpm@osdl.org: cleanup]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:33 -07:00

1031 lines
22 KiB
C
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/*
* 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,
int atomic)
{
unsigned long copy;
while (len > 0) {
while (!iov->iov_len)
iov++;
copy = min_t(unsigned long, len, iov->iov_len);
if (atomic) {
if (__copy_from_user_inatomic(to, iov->iov_base, copy))
return -EFAULT;
} else {
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,
int atomic)
{
unsigned long copy;
while (len > 0) {
while (!iov->iov_len)
iov++;
copy = min_t(unsigned long, len, iov->iov_len);
if (atomic) {
if (__copy_to_user_inatomic(iov->iov_base, from, copy))
return -EFAULT;
} else {
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;
}
/*
* Attempt to pre-fault in the user memory, so we can use atomic copies.
* Returns the number of bytes not faulted in.
*/
static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
{
while (!iov->iov_len)
iov++;
while (len > 0) {
unsigned long this_len;
this_len = min_t(unsigned long, len, iov->iov_len);
if (fault_in_pages_writeable(iov->iov_base, this_len))
break;
len -= this_len;
iov++;
}
return len;
}
/*
* Pre-fault in the user memory, so we can use atomic copies.
*/
static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
{
while (!iov->iov_len)
iov++;
while (len > 0) {
unsigned long this_len;
this_len = min_t(unsigned long, len, iov->iov_len);
fault_in_pages_readable(iov->iov_base, this_len);
len -= this_len;
iov++;
}
}
static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct page *page = buf->page;
/*
* 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);
}
void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
struct pipe_buffer *buf, int atomic)
{
if (atomic) {
buf->flags |= PIPE_BUF_FLAG_ATOMIC;
return kmap_atomic(buf->page, KM_USER0);
}
return kmap(buf->page);
}
void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
struct pipe_buffer *buf, void *map_data)
{
if (buf->flags & PIPE_BUF_FLAG_ATOMIC) {
buf->flags &= ~PIPE_BUF_FLAG_ATOMIC;
kunmap_atomic(map_data, KM_USER0);
} else
kunmap(buf->page);
}
int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct page *page = buf->page;
if (page_count(page) == 1) {
lock_page(page);
return 0;
}
return 1;
}
void generic_pipe_buf_get(struct pipe_inode_info *info, struct pipe_buffer *buf)
{
page_cache_get(buf->page);
}
int generic_pipe_buf_pin(struct pipe_inode_info *info, struct pipe_buffer *buf)
{
return 0;
}
static struct pipe_buf_operations anon_pipe_buf_ops = {
.can_merge = 1,
.map = generic_pipe_buf_map,
.unmap = generic_pipe_buf_unmap,
.pin = generic_pipe_buf_pin,
.release = anon_pipe_buf_release,
.steal = generic_pipe_buf_steal,
.get = generic_pipe_buf_get,
};
static ssize_t
pipe_read(struct kiocb *iocb, const struct iovec *_iov,
unsigned long nr_segs, loff_t pos)
{
struct file *filp = iocb->ki_filp;
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;
size_t chars = buf->len;
int error, atomic;
if (chars > total_len)
chars = total_len;
error = ops->pin(pipe, buf);
if (error) {
if (!ret)
error = ret;
break;
}
atomic = !iov_fault_in_pages_write(iov, chars);
redo:
addr = ops->map(pipe, buf, atomic);
error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
ops->unmap(pipe, buf, addr);
if (unlikely(error)) {
/*
* Just retry with the slow path if we failed.
*/
if (atomic) {
atomic = 0;
goto redo;
}
if (!ret)
ret = error;
break;
}
ret += chars;
buf->offset += chars;
buf->len -= chars;
if (!buf->len) {
buf->ops = NULL;
ops->release(pipe, buf);
curbuf = (curbuf + 1) & (PIPE_BUFFERS-1);
pipe->curbuf = curbuf;
pipe->nrbufs = --bufs;
do_wakeup = 1;
}
total_len -= chars;
if (!total_len)
break; /* common path: read succeeded */
}
if (bufs) /* More to do? */
continue;
if (!pipe->writers)
break;
if (!pipe->waiting_writers) {
/* syscall merging: Usually we must not sleep
* if O_NONBLOCK is set, or if we got some data.
* But if a writer sleeps in kernel space, then
* we can wait for that data without violating POSIX.
*/
if (ret)
break;
if (filp->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
break;
}
}
if (signal_pending(current)) {
if (!ret)
ret = -ERESTARTSYS;
break;
}
if (do_wakeup) {
wake_up_interruptible_sync(&pipe->wait);
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}
pipe_wait(pipe);
}
mutex_unlock(&inode->i_mutex);
/* Signal writers asynchronously that there is more room. */
if (do_wakeup) {
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}
if (ret > 0)
file_accessed(filp);
return ret;
}
static ssize_t
pipe_write(struct kiocb *iocb, const struct iovec *_iov,
unsigned long nr_segs, loff_t ppos)
{
struct file *filp = iocb->ki_filp;
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *pipe;
ssize_t ret;
int do_wakeup;
struct iovec *iov = (struct iovec *)_iov;
size_t total_len;
ssize_t chars;
total_len = iov_length(iov, nr_segs);
/* Null write succeeds. */
if (unlikely(total_len == 0))
return 0;
do_wakeup = 0;
ret = 0;
mutex_lock(&inode->i_mutex);
pipe = inode->i_pipe;
if (!pipe->readers) {
send_sig(SIGPIPE, current, 0);
ret = -EPIPE;
goto out;
}
/* We try to merge small writes */
chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
if (pipe->nrbufs && chars != 0) {
int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
(PIPE_BUFFERS-1);
struct pipe_buffer *buf = pipe->bufs + lastbuf;
struct pipe_buf_operations *ops = buf->ops;
int offset = buf->offset + buf->len;
if (ops->can_merge && offset + chars <= PAGE_SIZE) {
int error, atomic = 1;
void *addr;
error = ops->pin(pipe, buf);
if (error)
goto out;
iov_fault_in_pages_read(iov, chars);
redo1:
addr = ops->map(pipe, buf, atomic);
error = pipe_iov_copy_from_user(offset + addr, iov,
chars, atomic);
ops->unmap(pipe, buf, addr);
ret = error;
do_wakeup = 1;
if (error) {
if (atomic) {
atomic = 0;
goto redo1;
}
goto out;
}
buf->len += chars;
total_len -= chars;
ret = chars;
if (!total_len)
goto out;
}
}
for (;;) {
int bufs;
if (!pipe->readers) {
send_sig(SIGPIPE, current, 0);
if (!ret)
ret = -EPIPE;
break;
}
bufs = pipe->nrbufs;
if (bufs < PIPE_BUFFERS) {
int newbuf = (pipe->curbuf + bufs) & (PIPE_BUFFERS-1);
struct pipe_buffer *buf = pipe->bufs + newbuf;
struct page *page = pipe->tmp_page;
char *src;
int error, atomic = 1;
if (!page) {
page = alloc_page(GFP_HIGHUSER);
if (unlikely(!page)) {
ret = ret ? : -ENOMEM;
break;
}
pipe->tmp_page = page;
}
/* Always wake up, even if the copy fails. Otherwise
* we lock up (O_NONBLOCK-)readers that sleep due to
* syscall merging.
* FIXME! Is this really true?
*/
do_wakeup = 1;
chars = PAGE_SIZE;
if (chars > total_len)
chars = total_len;
iov_fault_in_pages_read(iov, chars);
redo2:
if (atomic)
src = kmap_atomic(page, KM_USER0);
else
src = kmap(page);
error = pipe_iov_copy_from_user(src, iov, chars,
atomic);
if (atomic)
kunmap_atomic(src, KM_USER0);
else
kunmap(page);
if (unlikely(error)) {
if (atomic) {
atomic = 0;
goto redo2;
}
if (!ret)
ret = error;
break;
}
ret += chars;
/* Insert it into the buffer array */
buf->page = page;
buf->ops = &anon_pipe_buf_ops;
buf->offset = 0;
buf->len = chars;
pipe->nrbufs = ++bufs;
pipe->tmp_page = NULL;
total_len -= chars;
if (!total_len)
break;
}
if (bufs < PIPE_BUFFERS)
continue;
if (filp->f_flags & O_NONBLOCK) {
if (!ret)
ret = -EAGAIN;
break;
}
if (signal_pending(current)) {
if (!ret)
ret = -ERESTARTSYS;
break;
}
if (do_wakeup) {
wake_up_interruptible_sync(&pipe->wait);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
do_wakeup = 0;
}
pipe->waiting_writers++;
pipe_wait(pipe);
pipe->waiting_writers--;
}
out:
mutex_unlock(&inode->i_mutex);
if (do_wakeup) {
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
}
if (ret > 0)
file_update_time(filp);
return ret;
}
static ssize_t
bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
return -EBADF;
}
static ssize_t
bad_pipe_w(struct file *filp, const char __user *buf, size_t count,
loff_t *ppos)
{
return -EBADF;
}
static int
pipe_ioctl(struct inode *pino, struct file *filp,
unsigned int cmd, unsigned long arg)
{
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *pipe;
int count, buf, nrbufs;
switch (cmd) {
case FIONREAD:
mutex_lock(&inode->i_mutex);
pipe = inode->i_pipe;
count = 0;
buf = pipe->curbuf;
nrbufs = pipe->nrbufs;
while (--nrbufs >= 0) {
count += pipe->bufs[buf].len;
buf = (buf+1) & (PIPE_BUFFERS-1);
}
mutex_unlock(&inode->i_mutex);
return put_user(count, (int __user *)arg);
default:
return -EINVAL;
}
}
/* No kernel lock held - fine */
static unsigned int
pipe_poll(struct file *filp, poll_table *wait)
{
unsigned int mask;
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *pipe = inode->i_pipe;
int nrbufs;
poll_wait(filp, &pipe->wait, wait);
/* Reading only -- no need for acquiring the semaphore. */
nrbufs = pipe->nrbufs;
mask = 0;
if (filp->f_mode & FMODE_READ) {
mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
if (!pipe->writers && filp->f_version != pipe->w_counter)
mask |= POLLHUP;
}
if (filp->f_mode & FMODE_WRITE) {
mask |= (nrbufs < PIPE_BUFFERS) ? POLLOUT | POLLWRNORM : 0;
/*
* Most Unices do not set POLLERR for FIFOs but on Linux they
* behave exactly like pipes for poll().
*/
if (!pipe->readers)
mask |= POLLERR;
}
return mask;
}
static int
pipe_release(struct inode *inode, int decr, int decw)
{
struct pipe_inode_info *pipe;
mutex_lock(&inode->i_mutex);
pipe = inode->i_pipe;
pipe->readers -= decr;
pipe->writers -= decw;
if (!pipe->readers && !pipe->writers) {
free_pipe_info(inode);
} else {
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}
mutex_unlock(&inode->i_mutex);
return 0;
}
static int
pipe_read_fasync(int fd, struct file *filp, int on)
{
struct inode *inode = filp->f_dentry->d_inode;
int retval;
mutex_lock(&inode->i_mutex);
retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
mutex_unlock(&inode->i_mutex);
if (retval < 0)
return retval;
return 0;
}
static int
pipe_write_fasync(int fd, struct file *filp, int on)
{
struct inode *inode = filp->f_dentry->d_inode;
int retval;
mutex_lock(&inode->i_mutex);
retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
mutex_unlock(&inode->i_mutex);
if (retval < 0)
return retval;
return 0;
}
static int
pipe_rdwr_fasync(int fd, struct file *filp, int on)
{
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *pipe = inode->i_pipe;
int retval;
mutex_lock(&inode->i_mutex);
retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
if (retval >= 0)
retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
mutex_unlock(&inode->i_mutex);
if (retval < 0)
return retval;
return 0;
}
static int
pipe_read_release(struct inode *inode, struct file *filp)
{
pipe_read_fasync(-1, filp, 0);
return pipe_release(inode, 1, 0);
}
static int
pipe_write_release(struct inode *inode, struct file *filp)
{
pipe_write_fasync(-1, filp, 0);
return pipe_release(inode, 0, 1);
}
static int
pipe_rdwr_release(struct inode *inode, struct file *filp)
{
int decr, decw;
pipe_rdwr_fasync(-1, filp, 0);
decr = (filp->f_mode & FMODE_READ) != 0;
decw = (filp->f_mode & FMODE_WRITE) != 0;
return pipe_release(inode, decr, decw);
}
static int
pipe_read_open(struct inode *inode, struct file *filp)
{
/* We could have perhaps used atomic_t, but this and friends
below are the only places. So it doesn't seem worthwhile. */
mutex_lock(&inode->i_mutex);
inode->i_pipe->readers++;
mutex_unlock(&inode->i_mutex);
return 0;
}
static int
pipe_write_open(struct inode *inode, struct file *filp)
{
mutex_lock(&inode->i_mutex);
inode->i_pipe->writers++;
mutex_unlock(&inode->i_mutex);
return 0;
}
static int
pipe_rdwr_open(struct inode *inode, struct file *filp)
{
mutex_lock(&inode->i_mutex);
if (filp->f_mode & FMODE_READ)
inode->i_pipe->readers++;
if (filp->f_mode & FMODE_WRITE)
inode->i_pipe->writers++;
mutex_unlock(&inode->i_mutex);
return 0;
}
/*
* The file_operations structs are not static because they
* are also used in linux/fs/fifo.c to do operations on FIFOs.
*/
const struct file_operations read_fifo_fops = {
.llseek = no_llseek,
.read = do_sync_read,
.aio_read = pipe_read,
.write = bad_pipe_w,
.poll = pipe_poll,
.ioctl = pipe_ioctl,
.open = pipe_read_open,
.release = pipe_read_release,
.fasync = pipe_read_fasync,
};
const struct file_operations write_fifo_fops = {
.llseek = no_llseek,
.read = bad_pipe_r,
.write = do_sync_write,
.aio_write = pipe_write,
.poll = pipe_poll,
.ioctl = pipe_ioctl,
.open = pipe_write_open,
.release = pipe_write_release,
.fasync = pipe_write_fasync,
};
const struct file_operations rdwr_fifo_fops = {
.llseek = no_llseek,
.read = do_sync_read,
.aio_read = pipe_read,
.write = do_sync_write,
.aio_write = pipe_write,
.poll = pipe_poll,
.ioctl = pipe_ioctl,
.open = pipe_rdwr_open,
.release = pipe_rdwr_release,
.fasync = pipe_rdwr_fasync,
};
static struct file_operations read_pipe_fops = {
.llseek = no_llseek,
.read = do_sync_read,
.aio_read = pipe_read,
.write = bad_pipe_w,
.poll = pipe_poll,
.ioctl = pipe_ioctl,
.open = pipe_read_open,
.release = pipe_read_release,
.fasync = pipe_read_fasync,
};
static struct file_operations write_pipe_fops = {
.llseek = no_llseek,
.read = bad_pipe_r,
.write = do_sync_write,
.aio_write = pipe_write,
.poll = pipe_poll,
.ioctl = pipe_ioctl,
.open = pipe_write_open,
.release = pipe_write_release,
.fasync = pipe_write_fasync,
};
static struct file_operations rdwr_pipe_fops = {
.llseek = no_llseek,
.read = do_sync_read,
.aio_read = pipe_read,
.write = do_sync_write,
.aio_write = pipe_write,
.poll = pipe_poll,
.ioctl = pipe_ioctl,
.open = pipe_rdwr_open,
.release = pipe_rdwr_release,
.fasync = pipe_rdwr_fasync,
};
struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
{
struct pipe_inode_info *pipe;
pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
if (pipe) {
init_waitqueue_head(&pipe->wait);
pipe->r_counter = pipe->w_counter = 1;
pipe->inode = inode;
}
return pipe;
}
void __free_pipe_info(struct pipe_inode_info *pipe)
{
int i;
for (i = 0; i < PIPE_BUFFERS; i++) {
struct pipe_buffer *buf = pipe->bufs + i;
if (buf->ops)
buf->ops->release(pipe, buf);
}
if (pipe->tmp_page)
__free_page(pipe->tmp_page);
kfree(pipe);
}
void free_pipe_info(struct inode *inode)
{
__free_pipe_info(inode->i_pipe);
inode->i_pipe = NULL;
}
static struct vfsmount *pipe_mnt __read_mostly;
static int pipefs_delete_dentry(struct dentry *dentry)
{
return 1;
}
static struct dentry_operations pipefs_dentry_operations = {
.d_delete = pipefs_delete_dentry,
};
static struct inode * get_pipe_inode(void)
{
struct inode *inode = new_inode(pipe_mnt->mnt_sb);
struct pipe_inode_info *pipe;
if (!inode)
goto fail_inode;
pipe = alloc_pipe_info(inode);
if (!pipe)
goto fail_iput;
inode->i_pipe = pipe;
pipe->readers = pipe->writers = 1;
inode->i_fop = &rdwr_pipe_fops;
/*
* Mark the inode dirty from the very beginning,
* that way it will never be moved to the dirty
* list because "mark_inode_dirty()" will think
* that it already _is_ on the dirty list.
*/
inode->i_state = I_DIRTY;
inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
inode->i_uid = current->fsuid;
inode->i_gid = current->fsgid;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
return inode;
fail_iput:
iput(inode);
fail_inode:
return NULL;
}
struct file *create_write_pipe(void)
{
int err;
struct inode *inode;
struct file *f;
struct dentry *dentry;
char name[32];
struct qstr this;
f = get_empty_filp();
if (!f)
return ERR_PTR(-ENFILE);
err = -ENFILE;
inode = get_pipe_inode();
if (!inode)
goto err_file;
sprintf(name, "[%lu]", inode->i_ino);
this.name = name;
this.len = strlen(name);
this.hash = inode->i_ino; /* will go */
err = -ENOMEM;
dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &this);
if (!dentry)
goto err_inode;
dentry->d_op = &pipefs_dentry_operations;
d_add(dentry, inode);
f->f_vfsmnt = mntget(pipe_mnt);
f->f_dentry = dentry;
f->f_mapping = inode->i_mapping;
f->f_flags = O_WRONLY;
f->f_op = &write_pipe_fops;
f->f_mode = FMODE_WRITE;
f->f_version = 0;
return f;
err_inode:
free_pipe_info(inode);
iput(inode);
err_file:
put_filp(f);
return ERR_PTR(err);
}
void free_write_pipe(struct file *f)
{
mntput(f->f_vfsmnt);
dput(f->f_dentry);
put_filp(f);
}
struct file *create_read_pipe(struct file *wrf)
{
struct file *f = get_empty_filp();
if (!f)
return ERR_PTR(-ENFILE);
/* Grab pipe from the writer */
f->f_vfsmnt = mntget(wrf->f_vfsmnt);
f->f_dentry = dget(wrf->f_dentry);
f->f_mapping = wrf->f_dentry->d_inode->i_mapping;
f->f_pos = 0;
f->f_flags = O_RDONLY;
f->f_op = &read_pipe_fops;
f->f_mode = FMODE_READ;
f->f_version = 0;
return f;
}
int do_pipe(int *fd)
{
struct file *fw, *fr;
int error;
int fdw, fdr;
fw = create_write_pipe();
if (IS_ERR(fw))
return PTR_ERR(fw);
fr = create_read_pipe(fw);
error = PTR_ERR(fr);
if (IS_ERR(fr))
goto err_write_pipe;
error = get_unused_fd();
if (error < 0)
goto err_read_pipe;
fdr = error;
error = get_unused_fd();
if (error < 0)
goto err_fdr;
fdw = error;
fd_install(fdr, fr);
fd_install(fdw, fw);
fd[0] = fdr;
fd[1] = fdw;
return 0;
err_fdr:
put_unused_fd(fdr);
err_read_pipe:
put_filp(fr);
err_write_pipe:
free_write_pipe(fw);
return error;
}
/*
* pipefs should _never_ be mounted by userland - too much of security hassle,
* no real gain from having the whole whorehouse mounted. So we don't need
* any operations on the root directory. However, we need a non-trivial
* d_name - pipe: will go nicely and kill the special-casing in procfs.
*/
static int pipefs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data,
struct vfsmount *mnt)
{
return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC, mnt);
}
static struct file_system_type pipe_fs_type = {
.name = "pipefs",
.get_sb = pipefs_get_sb,
.kill_sb = kill_anon_super,
};
static int __init init_pipe_fs(void)
{
int err = register_filesystem(&pipe_fs_type);
if (!err) {
pipe_mnt = kern_mount(&pipe_fs_type);
if (IS_ERR(pipe_mnt)) {
err = PTR_ERR(pipe_mnt);
unregister_filesystem(&pipe_fs_type);
}
}
return err;
}
static void __exit exit_pipe_fs(void)
{
unregister_filesystem(&pipe_fs_type);
mntput(pipe_mnt);
}
fs_initcall(init_pipe_fs);
module_exit(exit_pipe_fs);
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