fix for slow unmount on ext4 - bug 543617 on lp

[Kees Cook]

Hi Stefan,

On Mon, Jun 07, 2010 at 02:10:43PM +0200, Stefan Bader wrote:
> Ok, so upstream seems to have officially reverted the changes for now. Given
> that the changes in that area seem to have unexpected side effects and we do not
> really know the other patch would not do the same. When reverting the
> work-around we got huge sync times. IIRC the side effects of that patch were not
> as bad timewise (2 seconds?). So maybe for now, we stay with what we got and
> wait for the proper upstream solution?

Upstream gave up on fixing the problem?  Argh.

Huge sync times in Lucid?  When what was changed?

I think we need to revert 5e1941884c700b7b97bcad52c2d8212ac56a7ebc even
if there isn't a good fix for the umount slow-down since it solves the
slow umount only under certain conditions, and makes other more common
umount scenarios slower.

-Kees

-- 
Kees Cook
Ubuntu Security Team