userfs on 2.2.16 - question about fcheck_task in file.h

From: joel reed (
Date: Fri Jun 16 2000 - 08:37:19 EST

i'm trying to get userfs to work on 2.2.16.

as i understand it, userfs uses pipe(2) to create a communication means
between kernel & userland, passes the fd's to kernel userfs.o module
during the mount(2) call and in read_super userfs does a

        if ((toproc = fcheck_task(current,mntinfo->fromkern)) == NULL )
                printk("userfs_read_super: bad fromkern fd %d\n",
                goto fail;

AFAICT, the mntinfo struct is correctly passed in and the fd number
is correct, but fcheck_task fails...

from /usr/include/linux/file.h

 * Check whether the specified task has the fd open. Since the task
 * may not have a files_struct, we must test for p->files != NULL.

extern inline struct file * fcheck_task(struct task_struct *p, unsigned int fd)
        struct file * file = NULL;

        if (p->files && fd < p->files->max_fds)
                file = p->files->fd[fd];
        return file;

does anyone have an idea why an fd made from pipe(2) passed into userfs.o
would not have an associated file as far the kernel is concerned?

thanks for any help.

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