RELENG_4 -> 5 -> 6: significant performance regression

[Mike Jakubik]

Bartosz Fabianowski wrote:
>> You wrote that Giant is needed in 6.0 and now you write it has been
>> removed.
>
> In 4.x, every UFS write requires the Giant lock. In 6.x, Giant is not 
> normally required, making file system operations faster. When you 
> enable QUOTA, you basically get back to the 4.x behavior where Giant 
> is needed for each write. This is why in 6.x UFS will normally be 
> faster but if you enable QUOTA, you lose the newly gained performance 
> again.

Why isn't QUOTA mpsafe then?