kernel26-2.6.12-alx-r9/fs/pipe.c

/*
 *  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 <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 inode * inode)
{
	DEFINE_WAIT(wait);

	/*
	 * Pipes are system-local resources, so sleeping on them
	 * is considered a noninteractive wait:
	 */
	prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE|TASK_NONINTERACTIVE);
	up(PIPE_SEM(*inode));
	schedule();
	finish_wait(PIPE_WAIT(*inode), &wait);
	down(PIPE_SEM(*inode));
}

static inline 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 inline 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 *info, struct pipe_buffer *buf)
{
	struct page *page = buf->page;

	if (info->tmp_page) {
		__free_page(page);
		return;
	}
	info->tmp_page = page;
}

static void *anon_pipe_buf_map(struct file *file, struct pipe_inode_info *info, struct pipe_buffer *buf)
{
	return kmap(buf->page);
}

static void anon_pipe_buf_unmap(struct pipe_inode_info *info, struct pipe_buffer *buf)
{
	kunmap(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,
};

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 *info;
	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;
	down(PIPE_SEM(*inode));
	info = inode->i_pipe;
	for (;;) {
		int bufs = info->nrbufs;
		if (bufs) {
			int curbuf = info->curbuf;
			struct pipe_buffer *buf = info->bufs + curbuf;
			struct pipe_buf_operations *ops = buf->ops;
			void *addr;
			size_t chars = buf->len;
			int error;

			if (chars > total_len)
				chars = total_len;

			addr = ops->map(filp, info, buf);
			error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars);
			ops->unmap(info, buf);
			if (unlikely(error)) {
				if (!ret) ret = -EFAULT;
				break;
			}
			ret += chars;
			buf->offset += chars;
			buf->len -= chars;
			if (!buf->len) {
				buf->ops = NULL;
				ops->release(info, buf);
				curbuf = (curbuf + 1) & (PIPE_BUFFERS-1);
				info->curbuf = curbuf;
				info->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(*inode))
			break;
		if (!PIPE_WAITING_WRITERS(*inode)) {
			/* 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(*inode));
 			kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
		}
		pipe_wait(inode);
	}
	up(PIPE_SEM(*inode));
	/* Signal writers asynchronously that there is more room.  */
	if (do_wakeup) {
		wake_up_interruptible(PIPE_WAIT(*inode));
		kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
	}
	if (ret > 0)
		file_accessed(filp);
	return ret;
}

static ssize_t
pipe_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
	struct iovec iov = { .iov_base = buf, .iov_len = count };
	return pipe_readv(filp, &iov, 1, ppos);
}

static ssize_t
pipe_writev(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 *info;
	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;
	down(PIPE_SEM(*inode));
	info = inode->i_pipe;

	if (!PIPE_READERS(*inode)) {
		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 (info->nrbufs && chars != 0) {
		int lastbuf = (info->curbuf + info->nrbufs - 1) & (PIPE_BUFFERS-1);
		struct pipe_buffer *buf = info->bufs + lastbuf;
		struct pipe_buf_operations *ops = buf->ops;
		int offset = buf->offset + buf->len;
		if (ops->can_merge && offset + chars <= PAGE_SIZE) {
			void *addr = ops->map(filp, info, buf);
			int error = pipe_iov_copy_from_user(offset + addr, iov, chars);
			ops->unmap(info, buf);
			ret = error;
			do_wakeup = 1;
			if (error)
				goto out;
			buf->len += chars;
			total_len -= chars;
			ret = chars;
			if (!total_len)
				goto out;
		}
	}

	for (;;) {
		int bufs;
		if (!PIPE_READERS(*inode)) {
			send_sig(SIGPIPE, current, 0);
			if (!ret) ret = -EPIPE;
			break;
		}
		bufs = info->nrbufs;
		if (bufs < PIPE_BUFFERS) {
			int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS-1);
			struct pipe_buffer *buf = info->bufs + newbuf;
			struct page *page = info->tmp_page;
			int error;

			if (!page) {
				page = alloc_page(GFP_HIGHUSER);
				if (unlikely(!page)) {
					ret = ret ? : -ENOMEM;
					break;
				}
				info->tmp_page = page;
			}
			/* Always wakeup, 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;

			error = pipe_iov_copy_from_user(kmap(page), iov, chars);
			kunmap(page);
			if (unlikely(error)) {
				if (!ret) ret = -EFAULT;
				break;
			}
			ret += chars;

			/* Insert it into the buffer array */
			buf->page = page;
			buf->ops = &anon_pipe_buf_ops;
			buf->offset = 0;
			buf->len = chars;
			info->nrbufs = ++bufs;
			info->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(*inode));
			kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
			do_wakeup = 0;
		}
		PIPE_WAITING_WRITERS(*inode)++;
		pipe_wait(inode);
		PIPE_WAITING_WRITERS(*inode)--;
	}
out:
	up(PIPE_SEM(*inode));
	if (do_wakeup) {
		wake_up_interruptible(PIPE_WAIT(*inode));
		kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
	}
	if (ret > 0)
		inode_update_time(inode, 1);	/* mtime and ctime */
	return ret;
}

static ssize_t
pipe_write(struct file *filp, const char __user *buf,
	   size_t count, loff_t *ppos)
{
	struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
	return pipe_writev(filp, &iov, 1, ppos);
}

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 *info;
	int count, buf, nrbufs;

	switch (cmd) {
		case FIONREAD:
			down(PIPE_SEM(*inode));
			info =  inode->i_pipe;
			count = 0;
			buf = info->curbuf;
			nrbufs = info->nrbufs;
			while (--nrbufs >= 0) {
				count += info->bufs[buf].len;
				buf = (buf+1) & (PIPE_BUFFERS-1);
			}
			up(PIPE_SEM(*inode));
			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 *info = inode->i_pipe;
	int nrbufs;

	poll_wait(filp, PIPE_WAIT(*inode), wait);

	/* Reading only -- no need for acquiring the semaphore.  */
	nrbufs = info->nrbufs;
	mask = 0;
	if (filp->f_mode & FMODE_READ) {
		mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
		if (!PIPE_WRITERS(*inode) && filp->f_version != PIPE_WCOUNTER(*inode))
			mask |= POLLHUP;
	}

	if (filp->f_mode & FMODE_WRITE) {
		mask |= (nrbufs < PIPE_BUFFERS) ? POLLOUT | POLLWRNORM : 0;
		if (!PIPE_READERS(*inode))
			mask |= POLLERR;
	}

	return mask;
}

/* FIXME: most Unices do not set POLLERR for fifos */
#define fifo_poll pipe_poll

static int
pipe_release(struct inode *inode, int decr, int decw)
{
	down(PIPE_SEM(*inode));
	PIPE_READERS(*inode) -= decr;
	PIPE_WRITERS(*inode) -= decw;
	if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) {
		free_pipe_info(inode);
	} else {
		wake_up_interruptible(PIPE_WAIT(*inode));
		kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
		kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
	}
	up(PIPE_SEM(*inode));

	return 0;
}

static int
pipe_read_fasync(int fd, struct file *filp, int on)
{
	struct inode *inode = filp->f_dentry->d_inode;
	int retval;

	down(PIPE_SEM(*inode));
	retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
	up(PIPE_SEM(*inode));

	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;

	down(PIPE_SEM(*inode));
	retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
	up(PIPE_SEM(*inode));

	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;
	int retval;

	down(PIPE_SEM(*inode));

	retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));

	if (retval >= 0)
		retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));

	up(PIPE_SEM(*inode));

	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.  */
	down(PIPE_SEM(*inode));
	PIPE_READERS(*inode)++;
	up(PIPE_SEM(*inode));

	return 0;
}

static int
pipe_write_open(struct inode *inode, struct file *filp)
{
	down(PIPE_SEM(*inode));
	PIPE_WRITERS(*inode)++;
	up(PIPE_SEM(*inode));

	return 0;
}

static int
pipe_rdwr_open(struct inode *inode, struct file *filp)
{
	down(PIPE_SEM(*inode));
	if (filp->f_mode & FMODE_READ)
		PIPE_READERS(*inode)++;
	if (filp->f_mode & FMODE_WRITE)
		PIPE_WRITERS(*inode)++;
	up(PIPE_SEM(*inode));

	return 0;
}

/*
 * The file_operations structs are not static because they
 * are also used in linux/fs/fifo.c to do operations on FIFOs.
 */
struct file_operations read_fifo_fops = {
	.llseek		= no_llseek,
	.read		= pipe_read,
	.readv		= pipe_readv,
	.write		= bad_pipe_w,
	.poll		= fifo_poll,
	.ioctl		= pipe_ioctl,
	.open		= pipe_read_open,
	.release	= pipe_read_release,
	.fasync		= pipe_read_fasync,
};

struct file_operations write_fifo_fops = {
	.llseek		= no_llseek,
	.read		= bad_pipe_r,
	.write		= pipe_write,
	.writev		= pipe_writev,
	.poll		= fifo_poll,
	.ioctl		= pipe_ioctl,
	.open		= pipe_write_open,
	.release	= pipe_write_release,
	.fasync		= pipe_write_fasync,
};

struct file_operations rdwr_fifo_fops = {
	.llseek		= no_llseek,
	.read		= pipe_read,
	.readv		= pipe_readv,
	.write		= pipe_write,
	.writev		= pipe_writev,
	.poll		= fifo_poll,
	.ioctl		= pipe_ioctl,
	.open		= pipe_rdwr_open,
	.release	= pipe_rdwr_release,
	.fasync		= pipe_rdwr_fasync,
};

struct file_operations read_pipe_fops = {
	.llseek		= no_llseek,
	.read		= pipe_read,
	.readv		= pipe_readv,
	.write		= bad_pipe_w,
	.poll		= pipe_poll,
	.ioctl		= pipe_ioctl,
	.open		= pipe_read_open,
	.release	= pipe_read_release,
	.fasync		= pipe_read_fasync,
};

struct file_operations write_pipe_fops = {
	.llseek		= no_llseek,
	.read		= bad_pipe_r,
	.write		= pipe_write,
	.writev		= pipe_writev,
	.poll		= pipe_poll,
	.ioctl		= pipe_ioctl,
	.open		= pipe_write_open,
	.release	= pipe_write_release,
	.fasync		= pipe_write_fasync,
};

struct file_operations rdwr_pipe_fops = {
	.llseek		= no_llseek,
	.read		= pipe_read,
	.readv		= pipe_readv,
	.write		= pipe_write,
	.writev		= pipe_writev,
	.poll		= pipe_poll,
	.ioctl		= pipe_ioctl,
	.open		= pipe_rdwr_open,
	.release	= pipe_rdwr_release,
	.fasync		= pipe_rdwr_fasync,
};

void free_pipe_info(struct inode *inode)
{
	int i;
	struct pipe_inode_info *info = inode->i_pipe;

	inode->i_pipe = NULL;
	for (i = 0; i < PIPE_BUFFERS; i++) {
		struct pipe_buffer *buf = info->bufs + i;
		if (buf->ops)
			buf->ops->release(info, buf);
	}
	if (info->tmp_page)
		__free_page(info->tmp_page);
	kfree(info);
}

struct inode* pipe_new(struct inode* inode)
{
	struct pipe_inode_info *info;

	info = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
	if (!info)
		goto fail_page;
	memset(info, 0, sizeof(*info));
	inode->i_pipe = info;

	init_waitqueue_head(PIPE_WAIT(*inode));
	PIPE_RCOUNTER(*inode) = PIPE_WCOUNTER(*inode) = 1;

	return inode;
fail_page:
	return NULL;
}

static struct vfsmount *pipe_mnt;
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);

	if (!inode)
		goto fail_inode;

	if(!pipe_new(inode))
		goto fail_iput;
	PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 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;
	inode->i_blksize = PAGE_SIZE;
	return inode;

fail_iput:
	iput(inode);
fail_inode:
	return NULL;
}

int do_pipe(int *fd)
{
	struct qstr this;
	char name[32];
	struct dentry *dentry;
	struct inode * inode;
	struct file *f1, *f2;
	int error;
	int i,j;

	error = -ENFILE;
	f1 = get_empty_filp();
	if (!f1)
		goto no_files;

	f2 = get_empty_filp();
	if (!f2)
		goto close_f1;

	inode = get_pipe_inode();
	if (!inode)
		goto close_f12;

	error = get_unused_fd();
	if (error < 0)
		goto close_f12_inode;
	i = error;

	error = get_unused_fd();
	if (error < 0)
		goto close_f12_inode_i;
	j = error;

	error = -ENOMEM;
	sprintf(name, "[%lu]", inode->i_ino);
	this.name = name;
	this.len = strlen(name);
	this.hash = inode->i_ino; /* will go */
	dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &this);
	if (!dentry)
		goto close_f12_inode_i_j;
	dentry->d_op = &pipefs_dentry_operations;
	d_add(dentry, inode);
	f1->f_vfsmnt = f2->f_vfsmnt = mntget(mntget(pipe_mnt));
	f1->f_dentry = f2->f_dentry = dget(dentry);
	f1->f_mapping = f2->f_mapping = inode->i_mapping;

	/* read file */
	f1->f_pos = f2->f_pos = 0;
	f1->f_flags = O_RDONLY;
	f1->f_op = &read_pipe_fops;
	f1->f_mode = FMODE_READ;
	f1->f_version = 0;

	/* write file */
	f2->f_flags = O_WRONLY;
	f2->f_op = &write_pipe_fops;
	f2->f_mode = FMODE_WRITE;
	f2->f_version = 0;

	fd_install(i, f1);
	fd_install(j, f2);
	fd[0] = i;
	fd[1] = j;
	return 0;

close_f12_inode_i_j:
	put_unused_fd(j);
close_f12_inode_i:
	put_unused_fd(i);
close_f12_inode:
	free_pipe_info(inode);
	iput(inode);
close_f12:
	put_filp(f2);
close_f1:
	put_filp(f1);
no_files:
	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 struct super_block *pipefs_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC);
}

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);
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/mount.h>
15	#include <linux/pipe_fs_i.h>
16	#include <linux/uio.h>
17	#include <linux/highmem.h>
18
19	#include <asm/uaccess.h>
20	#include <asm/ioctls.h>
21
22	/*
23	* We use a start+len construction, which provides full use of the
24	* allocated memory.
25	* -- Florian Coosmann (FGC)
26	*
27	* Reads with count = 0 should always return 0.
28	* -- Julian Bradfield 1999-06-07.
29	*
30	* FIFOs and Pipes now generate SIGIO for both readers and writers.
31	* -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
32	*
33	* pipe_read & write cleanup
34	* -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
35	*/
36
37	/* Drop the inode semaphore and wait for a pipe event, atomically */
38	void pipe_wait(struct inode * inode)
39	{
40	DEFINE_WAIT(wait);
41
42	/*
43	* Pipes are system-local resources, so sleeping on them
44	* is considered a noninteractive wait:
45	*/
46	prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE\|TASK_NONINTERACTIVE);
47	up(PIPE_SEM(*inode));
48	schedule();
49	finish_wait(PIPE_WAIT(*inode), &wait);
50	down(PIPE_SEM(*inode));
51	}
52
53	static inline int
54	pipe_iov_copy_from_user(void to, struct iovec iov, unsigned long len)
55	{
56	unsigned long copy;
57
58	while (len > 0) {
59	while (!iov->iov_len)
60	iov++;
61	copy = min_t(unsigned long, len, iov->iov_len);
62
63	if (copy_from_user(to, iov->iov_base, copy))
64	return -EFAULT;
65	to += copy;
66	len -= copy;
67	iov->iov_base += copy;
68	iov->iov_len -= copy;
69	}
70	return 0;
71	}
72
73	static inline int
74	pipe_iov_copy_to_user(struct iovec iov, const void from, unsigned long len)
75	{
76	unsigned long copy;
77
78	while (len > 0) {
79	while (!iov->iov_len)
80	iov++;
81	copy = min_t(unsigned long, len, iov->iov_len);
82
83	if (copy_to_user(iov->iov_base, from, copy))
84	return -EFAULT;
85	from += copy;
86	len -= copy;
87	iov->iov_base += copy;
88	iov->iov_len -= copy;
89	}
90	return 0;
91	}
92
93	static void anon_pipe_buf_release(struct pipe_inode_info info, struct pipe_buffer buf)
94	{
95	struct page *page = buf->page;
96
97	if (info->tmp_page) {
98	__free_page(page);
99	return;
100	}
101	info->tmp_page = page;
102	}
103
104	static void anon_pipe_buf_map(struct file file, struct pipe_inode_info info, struct pipe_buffer buf)
105	{
106	return kmap(buf->page);
107	}
108
109	static void anon_pipe_buf_unmap(struct pipe_inode_info info, struct pipe_buffer buf)
110	{
111	kunmap(buf->page);
112	}
113
114	static struct pipe_buf_operations anon_pipe_buf_ops = {
115	.can_merge = 1,
116	.map = anon_pipe_buf_map,
117	.unmap = anon_pipe_buf_unmap,
118	.release = anon_pipe_buf_release,
119	};
120
121	static ssize_t
122	pipe_readv(struct file filp, const struct iovec _iov,
123	unsigned long nr_segs, loff_t *ppos)
124	{
125	struct inode *inode = filp->f_dentry->d_inode;
126	struct pipe_inode_info *info;
127	int do_wakeup;
128	ssize_t ret;
129	struct iovec iov = (struct iovec )_iov;
130	size_t total_len;
131
132	total_len = iov_length(iov, nr_segs);
133	/* Null read succeeds. */
134	if (unlikely(total_len == 0))
135	return 0;
136
137	do_wakeup = 0;
138	ret = 0;
139	down(PIPE_SEM(*inode));
140	info = inode->i_pipe;
141	for (;;) {
142	int bufs = info->nrbufs;
143	if (bufs) {
144	int curbuf = info->curbuf;
145	struct pipe_buffer *buf = info->bufs + curbuf;
146	struct pipe_buf_operations *ops = buf->ops;
147	void *addr;
148	size_t chars = buf->len;
149	int error;
150
151	if (chars > total_len)
152	chars = total_len;
153
154	addr = ops->map(filp, info, buf);
155	error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars);
156	ops->unmap(info, buf);
157	if (unlikely(error)) {
158	if (!ret) ret = -EFAULT;
159	break;
160	}
161	ret += chars;
162	buf->offset += chars;
163	buf->len -= chars;
164	if (!buf->len) {
165	buf->ops = NULL;
166	ops->release(info, buf);
167	curbuf = (curbuf + 1) & (PIPE_BUFFERS-1);
168	info->curbuf = curbuf;
169	info->nrbufs = --bufs;
170	do_wakeup = 1;
171	}
172	total_len -= chars;
173	if (!total_len)
174	break; /* common path: read succeeded */
175	}
176	if (bufs) /* More to do? */
177	continue;
178	if (!PIPE_WRITERS(*inode))
179	break;
180	if (!PIPE_WAITING_WRITERS(*inode)) {
181	/* syscall merging: Usually we must not sleep
182	* if O_NONBLOCK is set, or if we got some data.
183	* But if a writer sleeps in kernel space, then
184	* we can wait for that data without violating POSIX.
185	*/
186	if (ret)
187	break;
188	if (filp->f_flags & O_NONBLOCK) {
189	ret = -EAGAIN;
190	break;
191	}
192	}
193	if (signal_pending(current)) {
194	if (!ret) ret = -ERESTARTSYS;
195	break;
196	}
197	if (do_wakeup) {
198	wake_up_interruptible_sync(PIPE_WAIT(*inode));
199	kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
200	}
201	pipe_wait(inode);
202	}
203	up(PIPE_SEM(*inode));
204	/* Signal writers asynchronously that there is more room. */
205	if (do_wakeup) {
206	wake_up_interruptible(PIPE_WAIT(*inode));
207	kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
208	}
209	if (ret > 0)
210	file_accessed(filp);
211	return ret;
212	}
213
214	static ssize_t
215	pipe_read(struct file filp, char __user buf, size_t count, loff_t *ppos)
216	{
217	struct iovec iov = { .iov_base = buf, .iov_len = count };
218	return pipe_readv(filp, &iov, 1, ppos);
219	}
220
221	static ssize_t
222	pipe_writev(struct file filp, const struct iovec _iov,
223	unsigned long nr_segs, loff_t *ppos)
224	{
225	struct inode *inode = filp->f_dentry->d_inode;
226	struct pipe_inode_info *info;
227	ssize_t ret;
228	int do_wakeup;
229	struct iovec iov = (struct iovec )_iov;
230	size_t total_len;
231	ssize_t chars;
232
233	total_len = iov_length(iov, nr_segs);
234	/* Null write succeeds. */
235	if (unlikely(total_len == 0))
236	return 0;
237
238	do_wakeup = 0;
239	ret = 0;
240	down(PIPE_SEM(*inode));
241	info = inode->i_pipe;
242
243	if (!PIPE_READERS(*inode)) {
244	send_sig(SIGPIPE, current, 0);
245	ret = -EPIPE;
246	goto out;
247	}
248
249	/* We try to merge small writes */
250	chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
251	if (info->nrbufs && chars != 0) {
252	int lastbuf = (info->curbuf + info->nrbufs - 1) & (PIPE_BUFFERS-1);
253	struct pipe_buffer *buf = info->bufs + lastbuf;
254	struct pipe_buf_operations *ops = buf->ops;
255	int offset = buf->offset + buf->len;
256	if (ops->can_merge && offset + chars <= PAGE_SIZE) {
257	void *addr = ops->map(filp, info, buf);
258	int error = pipe_iov_copy_from_user(offset + addr, iov, chars);
259	ops->unmap(info, buf);
260	ret = error;
261	do_wakeup = 1;
262	if (error)
263	goto out;
264	buf->len += chars;
265	total_len -= chars;
266	ret = chars;
267	if (!total_len)
268	goto out;
269	}
270	}
271
272	for (;;) {
273	int bufs;
274	if (!PIPE_READERS(*inode)) {
275	send_sig(SIGPIPE, current, 0);
276	if (!ret) ret = -EPIPE;
277	break;
278	}
279	bufs = info->nrbufs;
280	if (bufs < PIPE_BUFFERS) {
281	int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS-1);
282	struct pipe_buffer *buf = info->bufs + newbuf;
283	struct page *page = info->tmp_page;
284	int error;
285
286	if (!page) {
287	page = alloc_page(GFP_HIGHUSER);
288	if (unlikely(!page)) {
289	ret = ret ? : -ENOMEM;
290	break;
291	}
292	info->tmp_page = page;
293	}
294	/* Always wakeup, even if the copy fails. Otherwise
295	* we lock up (O_NONBLOCK-)readers that sleep due to
296	* syscall merging.
297	* FIXME! Is this really true?
298	*/
299	do_wakeup = 1;
300	chars = PAGE_SIZE;
301	if (chars > total_len)
302	chars = total_len;
303
304	error = pipe_iov_copy_from_user(kmap(page), iov, chars);
305	kunmap(page);
306	if (unlikely(error)) {
307	if (!ret) ret = -EFAULT;
308	break;
309	}
310	ret += chars;
311
312	/* Insert it into the buffer array */
313	buf->page = page;
314	buf->ops = &anon_pipe_buf_ops;
315	buf->offset = 0;
316	buf->len = chars;
317	info->nrbufs = ++bufs;
318	info->tmp_page = NULL;
319
320	total_len -= chars;
321	if (!total_len)
322	break;
323	}
324	if (bufs < PIPE_BUFFERS)
325	continue;
326	if (filp->f_flags & O_NONBLOCK) {
327	if (!ret) ret = -EAGAIN;
328	break;
329	}
330	if (signal_pending(current)) {
331	if (!ret) ret = -ERESTARTSYS;
332	break;
333	}
334	if (do_wakeup) {
335	wake_up_interruptible_sync(PIPE_WAIT(*inode));
336	kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
337	do_wakeup = 0;
338	}
339	PIPE_WAITING_WRITERS(*inode)++;
340	pipe_wait(inode);
341	PIPE_WAITING_WRITERS(*inode)--;
342	}
343	out:
344	up(PIPE_SEM(*inode));
345	if (do_wakeup) {
346	wake_up_interruptible(PIPE_WAIT(*inode));
347	kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
348	}
349	if (ret > 0)
350	inode_update_time(inode, 1); /* mtime and ctime */
351	return ret;
352	}
353
354	static ssize_t
355	pipe_write(struct file filp, const char __user buf,
356	size_t count, loff_t *ppos)
357	{
358	struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
359	return pipe_writev(filp, &iov, 1, ppos);
360	}
361
362	static ssize_t
363	bad_pipe_r(struct file filp, char __user buf, size_t count, loff_t *ppos)
364	{
365	return -EBADF;
366	}
367
368	static ssize_t
369	bad_pipe_w(struct file filp, const char __user buf, size_t count, loff_t *ppos)
370	{
371	return -EBADF;
372	}
373
374	static int
375	pipe_ioctl(struct inode pino, struct file filp,
376	unsigned int cmd, unsigned long arg)
377	{
378	struct inode *inode = filp->f_dentry->d_inode;
379	struct pipe_inode_info *info;
380	int count, buf, nrbufs;
381
382	switch (cmd) {
383	case FIONREAD:
384	down(PIPE_SEM(*inode));
385	info = inode->i_pipe;
386	count = 0;
387	buf = info->curbuf;
388	nrbufs = info->nrbufs;
389	while (--nrbufs >= 0) {
390	count += info->bufs[buf].len;
391	buf = (buf+1) & (PIPE_BUFFERS-1);
392	}
393	up(PIPE_SEM(*inode));
394	return put_user(count, (int __user *)arg);
395	default:
396	return -EINVAL;
397	}
398	}
399
400	/* No kernel lock held - fine */
401	static unsigned int
402	pipe_poll(struct file filp, poll_table wait)
403	{
404	unsigned int mask;
405	struct inode *inode = filp->f_dentry->d_inode;
406	struct pipe_inode_info *info = inode->i_pipe;
407	int nrbufs;
408
409	poll_wait(filp, PIPE_WAIT(*inode), wait);
410
411	/* Reading only -- no need for acquiring the semaphore. */
412	nrbufs = info->nrbufs;
413	mask = 0;
414	if (filp->f_mode & FMODE_READ) {
415	mask = (nrbufs > 0) ? POLLIN \| POLLRDNORM : 0;
416	if (!PIPE_WRITERS(inode) && filp->f_version != PIPE_WCOUNTER(inode))
417	mask \|= POLLHUP;
418	}
419
420	if (filp->f_mode & FMODE_WRITE) {
421	mask \|= (nrbufs < PIPE_BUFFERS) ? POLLOUT \| POLLWRNORM : 0;
422	if (!PIPE_READERS(*inode))
423	mask \|= POLLERR;
424	}
425
426	return mask;
427	}
428
429	/* FIXME: most Unices do not set POLLERR for fifos */
430	#define fifo_poll pipe_poll
431
432	static int
433	pipe_release(struct inode *inode, int decr, int decw)
434	{
435	down(PIPE_SEM(*inode));
436	PIPE_READERS(*inode) -= decr;
437	PIPE_WRITERS(*inode) -= decw;
438	if (!PIPE_READERS(inode) && !PIPE_WRITERS(inode)) {
439	free_pipe_info(inode);
440	} else {
441	wake_up_interruptible(PIPE_WAIT(*inode));
442	kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
443	kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
444	}
445	up(PIPE_SEM(*inode));
446
447	return 0;
448	}
449
450	static int
451	pipe_read_fasync(int fd, struct file *filp, int on)
452	{
453	struct inode *inode = filp->f_dentry->d_inode;
454	int retval;
455
456	down(PIPE_SEM(*inode));
457	retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
458	up(PIPE_SEM(*inode));
459
460	if (retval < 0)
461	return retval;
462
463	return 0;
464	}
465
466
467	static int
468	pipe_write_fasync(int fd, struct file *filp, int on)
469	{
470	struct inode *inode = filp->f_dentry->d_inode;
471	int retval;
472
473	down(PIPE_SEM(*inode));
474	retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
475	up(PIPE_SEM(*inode));
476
477	if (retval < 0)
478	return retval;
479
480	return 0;
481	}
482
483
484	static int
485	pipe_rdwr_fasync(int fd, struct file *filp, int on)
486	{
487	struct inode *inode = filp->f_dentry->d_inode;
488	int retval;
489
490	down(PIPE_SEM(*inode));
491
492	retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
493
494	if (retval >= 0)
495	retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
496
497	up(PIPE_SEM(*inode));
498
499	if (retval < 0)
500	return retval;
501
502	return 0;
503	}
504
505
506	static int
507	pipe_read_release(struct inode inode, struct file filp)
508	{
509	pipe_read_fasync(-1, filp, 0);
510	return pipe_release(inode, 1, 0);
511	}
512
513	static int
514	pipe_write_release(struct inode inode, struct file filp)
515	{
516	pipe_write_fasync(-1, filp, 0);
517	return pipe_release(inode, 0, 1);
518	}
519
520	static int
521	pipe_rdwr_release(struct inode inode, struct file filp)
522	{
523	int decr, decw;
524
525	pipe_rdwr_fasync(-1, filp, 0);
526	decr = (filp->f_mode & FMODE_READ) != 0;
527	decw = (filp->f_mode & FMODE_WRITE) != 0;
528	return pipe_release(inode, decr, decw);
529	}
530
531	static int
532	pipe_read_open(struct inode inode, struct file filp)
533	{
534	/* We could have perhaps used atomic_t, but this and friends
535	below are the only places. So it doesn't seem worthwhile. */
536	down(PIPE_SEM(*inode));
537	PIPE_READERS(*inode)++;
538	up(PIPE_SEM(*inode));
539
540	return 0;
541	}
542
543	static int
544	pipe_write_open(struct inode inode, struct file filp)
545	{
546	down(PIPE_SEM(*inode));
547	PIPE_WRITERS(*inode)++;
548	up(PIPE_SEM(*inode));
549
550	return 0;
551	}
552
553	static int
554	pipe_rdwr_open(struct inode inode, struct file filp)
555	{
556	down(PIPE_SEM(*inode));
557	if (filp->f_mode & FMODE_READ)
558	PIPE_READERS(*inode)++;
559	if (filp->f_mode & FMODE_WRITE)
560	PIPE_WRITERS(*inode)++;
561	up(PIPE_SEM(*inode));
562
563	return 0;
564	}
565
566	/*
567	* The file_operations structs are not static because they
568	* are also used in linux/fs/fifo.c to do operations on FIFOs.
569	*/
570	struct file_operations read_fifo_fops = {
571	.llseek = no_llseek,
572	.read = pipe_read,
573	.readv = pipe_readv,
574	.write = bad_pipe_w,
575	.poll = fifo_poll,
576	.ioctl = pipe_ioctl,
577	.open = pipe_read_open,
578	.release = pipe_read_release,
579	.fasync = pipe_read_fasync,
580	};
581
582	struct file_operations write_fifo_fops = {
583	.llseek = no_llseek,
584	.read = bad_pipe_r,
585	.write = pipe_write,
586	.writev = pipe_writev,
587	.poll = fifo_poll,
588	.ioctl = pipe_ioctl,
589	.open = pipe_write_open,
590	.release = pipe_write_release,
591	.fasync = pipe_write_fasync,
592	};
593
594	struct file_operations rdwr_fifo_fops = {
595	.llseek = no_llseek,
596	.read = pipe_read,
597	.readv = pipe_readv,
598	.write = pipe_write,
599	.writev = pipe_writev,
600	.poll = fifo_poll,
601	.ioctl = pipe_ioctl,
602	.open = pipe_rdwr_open,
603	.release = pipe_rdwr_release,
604	.fasync = pipe_rdwr_fasync,
605	};
606
607	struct file_operations read_pipe_fops = {
608	.llseek = no_llseek,
609	.read = pipe_read,
610	.readv = pipe_readv,
611	.write = bad_pipe_w,
612	.poll = pipe_poll,
613	.ioctl = pipe_ioctl,
614	.open = pipe_read_open,
615	.release = pipe_read_release,
616	.fasync = pipe_read_fasync,
617	};
618
619	struct file_operations write_pipe_fops = {
620	.llseek = no_llseek,
621	.read = bad_pipe_r,
622	.write = pipe_write,
623	.writev = pipe_writev,
624	.poll = pipe_poll,
625	.ioctl = pipe_ioctl,
626	.open = pipe_write_open,
627	.release = pipe_write_release,
628	.fasync = pipe_write_fasync,
629	};
630
631	struct file_operations rdwr_pipe_fops = {
632	.llseek = no_llseek,
633	.read = pipe_read,
634	.readv = pipe_readv,
635	.write = pipe_write,
636	.writev = pipe_writev,
637	.poll = pipe_poll,
638	.ioctl = pipe_ioctl,
639	.open = pipe_rdwr_open,
640	.release = pipe_rdwr_release,
641	.fasync = pipe_rdwr_fasync,
642	};
643
644	void free_pipe_info(struct inode *inode)
645	{
646	int i;
647	struct pipe_inode_info *info = inode->i_pipe;
648
649	inode->i_pipe = NULL;
650	for (i = 0; i < PIPE_BUFFERS; i++) {
651	struct pipe_buffer *buf = info->bufs + i;
652	if (buf->ops)
653	buf->ops->release(info, buf);
654	}
655	if (info->tmp_page)
656	__free_page(info->tmp_page);
657	kfree(info);
658	}
659
660	struct inode* pipe_new(struct inode* inode)
661	{
662	struct pipe_inode_info *info;
663
664	info = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
665	if (!info)
666	goto fail_page;
667	memset(info, 0, sizeof(*info));
668	inode->i_pipe = info;
669
670	init_waitqueue_head(PIPE_WAIT(*inode));
671	PIPE_RCOUNTER(inode) = PIPE_WCOUNTER(inode) = 1;
672
673	return inode;
674	fail_page:
675	return NULL;
676	}
677
678	static struct vfsmount *pipe_mnt;
679	static int pipefs_delete_dentry(struct dentry *dentry)
680	{
681	return 1;
682	}
683	static struct dentry_operations pipefs_dentry_operations = {
684	.d_delete = pipefs_delete_dentry,
685	};
686
687	static struct inode * get_pipe_inode(void)
688	{
689	struct inode *inode = new_inode(pipe_mnt->mnt_sb);
690
691	if (!inode)
692	goto fail_inode;
693
694	if(!pipe_new(inode))
695	goto fail_iput;
696	PIPE_READERS(inode) = PIPE_WRITERS(inode) = 1;
697	inode->i_fop = &rdwr_pipe_fops;
698
699	/*
700	* Mark the inode dirty from the very beginning,
701	* that way it will never be moved to the dirty
702	* list because "mark_inode_dirty()" will think
703	* that it already _is_ on the dirty list.
704	*/
705	inode->i_state = I_DIRTY;
706	inode->i_mode = S_IFIFO \| S_IRUSR \| S_IWUSR;
707	inode->i_uid = current->fsuid;
708	inode->i_gid = current->fsgid;
709	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
710	inode->i_blksize = PAGE_SIZE;
711	return inode;
712
713	fail_iput:
714	iput(inode);
715	fail_inode:
716	return NULL;
717	}
718
719	int do_pipe(int *fd)
720	{
721	struct qstr this;
722	char name[32];
723	struct dentry *dentry;
724	struct inode * inode;
725	struct file f1, f2;
726	int error;
727	int i,j;
728
729	error = -ENFILE;
730	f1 = get_empty_filp();
731	if (!f1)
732	goto no_files;
733
734	f2 = get_empty_filp();
735	if (!f2)
736	goto close_f1;
737
738	inode = get_pipe_inode();
739	if (!inode)
740	goto close_f12;
741
742	error = get_unused_fd();
743	if (error < 0)
744	goto close_f12_inode;
745	i = error;
746
747	error = get_unused_fd();
748	if (error < 0)
749	goto close_f12_inode_i;
750	j = error;
751
752	error = -ENOMEM;
753	sprintf(name, "[%lu]", inode->i_ino);
754	this.name = name;
755	this.len = strlen(name);
756	this.hash = inode->i_ino; /* will go */
757	dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &this);
758	if (!dentry)
759	goto close_f12_inode_i_j;
760	dentry->d_op = &pipefs_dentry_operations;
761	d_add(dentry, inode);
762	f1->f_vfsmnt = f2->f_vfsmnt = mntget(mntget(pipe_mnt));
763	f1->f_dentry = f2->f_dentry = dget(dentry);
764	f1->f_mapping = f2->f_mapping = inode->i_mapping;
765
766	/* read file */
767	f1->f_pos = f2->f_pos = 0;
768	f1->f_flags = O_RDONLY;
769	f1->f_op = &read_pipe_fops;
770	f1->f_mode = FMODE_READ;
771	f1->f_version = 0;
772
773	/* write file */
774	f2->f_flags = O_WRONLY;
775	f2->f_op = &write_pipe_fops;
776	f2->f_mode = FMODE_WRITE;
777	f2->f_version = 0;
778
779	fd_install(i, f1);
780	fd_install(j, f2);
781	fd[0] = i;
782	fd[1] = j;
783	return 0;
784
785	close_f12_inode_i_j:
786	put_unused_fd(j);
787	close_f12_inode_i:
788	put_unused_fd(i);
789	close_f12_inode:
790	free_pipe_info(inode);
791	iput(inode);
792	close_f12:
793	put_filp(f2);
794	close_f1:
795	put_filp(f1);
796	no_files:
797	return error;
798	}
799
800	/*
801	* pipefs should _never_ be mounted by userland - too much of security hassle,
802	* no real gain from having the whole whorehouse mounted. So we don't need
803	* any operations on the root directory. However, we need a non-trivial
804	* d_name - pipe: will go nicely and kill the special-casing in procfs.
805	*/
806
807	static struct super_block pipefs_get_sb(struct file_system_type fs_type,
808	int flags, const char dev_name, void data)
809	{
810	return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC);
811	}
812
813	static struct file_system_type pipe_fs_type = {
814	.name = "pipefs",
815	.get_sb = pipefs_get_sb,
816	.kill_sb = kill_anon_super,
817	};
818
819	static int __init init_pipe_fs(void)
820	{
821	int err = register_filesystem(&pipe_fs_type);
822	if (!err) {
823	pipe_mnt = kern_mount(&pipe_fs_type);
824	if (IS_ERR(pipe_mnt)) {
825	err = PTR_ERR(pipe_mnt);
826	unregister_filesystem(&pipe_fs_type);
827	}
828	}
829	return err;
830	}
831
832	static void __exit exit_pipe_fs(void)
833	{
834	unregister_filesystem(&pipe_fs_type);
835	mntput(pipe_mnt);
836	}
837
838	fs_initcall(init_pipe_fs);
839	module_exit(exit_pipe_fs);