Re: How can I force a read to hit the disk?

[Alan Stern]

On Mon, 8 Sep 2003, Richard B. Johnson wrote:

> On Mon, 8 Sep 2003, Alan Stern wrote:
> 
> > I tried doing that, but it caused a segmentation violation.  The trouble
> > was this line near the start of fs/direct_io.c:dio_refill_pages()
> >
> > 	down_read(&current->mm->mmap_sem);
> >
> > Unfortunately, in a kernel thread (which is where my code runs)
> > current->mm is NULL.
> >
> > Can anybody offer additional advice?  How about a way to invalidate all
> > the page cache entries that contain a page from the file?
> >
> > Alan Stern
> 
> When your thread code starts up, execute
>                 init_rwsem(&current->mm->mmap_sem);
> 
> ... This is in the thread's code, not the module init code.

That doesn't work either; it also causes a segmentation violation.  As I 
said before, current->mm is NULL.  It gets set that way by exit_mm() which 
is called from daemonize().

Alan Stern

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/