Re: [RFC] vfs generic subtree support

[Dmitry Monakhov <dmonakhov@openvz.org>]

Matthew Wilcox <matthew@wil.cx> writes:

> On Tue, Feb 16, 2010 at 06:00:32PM +0300, Dmitry Monakhov wrote:
>> Use-cases:
>> *Assing maximum disc space consumption for some hierarchy *
>> 
>>   1) Create chroot environment
>>     # tar  xf chroot_env.tar /var/xxx/chroot
>>   2) Assign some metagroup id to the chroot content (via not yet
>>      existent ./metagroup cmd-tool)
>>     # find /var/xxx/chroot  | xargs ./metagroup --set 1000
>> 
>>   3) Setup quota limits
>>     # quota-set --type metagroup --blk_soft=1024M blk_hard=1024M /var
>> 
>>   4) Export this tree (it may be more complex)
>>     # mount /var/xxx/chroot /mnt/chroot -obound
>> 
>>   5)Now we may use this /mnt/chroot as:
>>     5A) A regular chroot envirement, user is unable to exceed metagroup
>>         quota, regardless to real available space on /var/
>>     5B) As a container's (namespace) root. 
>>     5C) export this /mnt/chroot to nfs server and nfs client can not
>>         overcome given metagroup quota limit. 
>
> This all seems quota-related ... do you envisage uses that aren't
> quota-related?
Yes. Since link/rename behavior is no longer depends on metagroup
I'm consider it as quota related only.