Re: Stale XFS mount for Kernel 2.6.25.14

[Dave Chinner <david@fromorbit.com>]

On Sun, Oct 12, 2008 at 10:10:54PM -0400, Ngo, Andrew wrote:
> Hi,  
>  
> This is my first attempt to report a stale mount problem.  If this is
> not the relevant mail list, please let me know.  I suspect that my
> problem is xfs related, thus I select this mailing list.
>  
> I have a system that recently upgraded it's kernel to 2.6.25.14.  The
> system's previous kernel was 2.6.18.-8.el5.  With the previous kernel, I
> have no problem with executing the following commands when the system is
> in operation.  Note that the /mnt/mountpoint is mounted on a XFS file
> system.
>  
> mount -o rw,remount /mnt/mountpoint
> mount -o ro,remount /mnt/mountpoint
>  
> With kernel 2.6.25.14, however, the mount command may be hang when
> changing from rw to ro.  When this happen, system is very sluggish.

That's because the remount,ro is actually flushing all the dirty
data to disk in 2.6.25. There is also a check to catch when the
remount,ro fails to clean everything that is dirty - that's probably
what is triggering. Do you have an oops in the dmesg log when
mount hangs?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com