dnotify doesn't deliver signals when user changes

[Mark Weaver]

> Does anyone know if this is a problem with dnotify, samba, or both or 
> could suggest a reasonable workaround?
> 
I did some more digging, the kernel code is not very complicated here:

static void send_sigio_to_task(struct task_struct *p,
        struct fown_struct *fown,
        int fd,
        int reason)
{
        if ((fown->euid != 0) &&
             (fown->euid ^ p->suid) && (fown->euid ^ p->uid) &&
             (fown->uid ^ p->suid) && (fown->uid ^ p->uid))
                 return;

Basically if any of uid/euid isn't the same as the task's uid/suid, and
the file wasn't opened as root, then signals don't get delivered.

I would assume therefore that this is a samba problem.

I hacked around it by shoving a becomme_root/unbecome_root in 
kernel_register_notify but I'm sure that's not correct as it has 
security implications.

For my purposes, it doesn't matter, but it seems that this is a general 
bug in samba.

Any suggestions on a better fix?

Thanks,

Mark