+void free_write_pipe(struct file *f)
+{
+ free_pipe_info(f->f_dentry->d_inode);
+ dput(f->f_path.dentry);
+ mntput(f->f_path.mnt);
+ 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_path.mnt = mntget(wrf->f_path.mnt);
+ f->f_path.dentry = dget(wrf->f_path.dentry);
+ f->f_mapping = wrf->f_path.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:
+ dput(fr->f_dentry);
+ mntput(fr->f_vfsmnt);
+ put_filp(fr);
+ err_write_pipe:
+ free_write_pipe(fw);
+ return error;
+}