Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 835 insertions, 0 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
new file mode 100644
index 000000000000..25aa09f9d09d
--- /dev/null
+++ b/fs/pipe.c
@@ -0,0 +1,835 @@
+/*
+ *  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);
+
+        prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE);
+        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);