> On 11.03.2013 15:15, Wang Shilong wrote: >> >> <snip> >> >>>> The worst thing is that i don't think users can master this magic >>>> concept very well. >>> >>> Normally users don't need very sophisticated scenarios. In fact, they >>> don't even need higher level quota groups, the basic tracking is >>> enough. In this case, everything just works as expected for the user. >>> If you start creating and assigning qgroups manually, prepare to handle >>> the complexity. >>> >> Considering this case: >> >> a subvolume related to a user, we limit the space by limiting every subvolume >> qgroup, but we also want to limit the total space all the users can use. >> So we create >> a parent qgroup(1/1 for example) and assign all subvolume group to this >> parent group. >> >> The above case is regularly used i think, What's more, many snapshots may be >> done. >> So i think what i am concerning is not a corner case.. > > So you just missed to assign the new subvolume to 1/1 by using -i on > snapshot creation. >
When snapshot happens, the exclusive of 1/1 will go wrong even with this simple case.. However, thanks very much for your patience and kindly reply ^_^ Thanks, Wang > -Arne > >> >> Thanks, >> Wang >>> >>>> >>>>> >>>>>> If so, i think it really confusing and too complex for users to do >>>>>> such work, is't it?... >>>>> >>>>> It is complex. That is why I always point anyone asking to do some work >>>>> on btrfs or qgroups to writing an enhanced interface to simplify this >>>>> task for the user. I don't think the kernel should handle this. >>>>> And that's why I took the effort to write a pdf to explain the >>>>> concepts :) >>>> >>>> I don't have any good ideas about this yet.. >>>> >>>>> But the current interface is not only complex, it also is very powerful. >>>>> You can solve problems with it that no other quota system I know of can >>>>> solve. >>>>> >>>>>> >>>>>> BTW, i have a question about the function btrfs_qgroup_inherit(), >>>>>> when copying exclusive value from src_qgroup to dst_qgroup: >>>>>> >>>>>> dst_qgroup->exclusive = src_qgroup->exclusive + level_size >>>>>> >>>>>> while copying referenced value from src_qgroup to dot_qgroup: >>>>>> >>>>>> dst_qgroup->referenced = src_qgroup->referenced -level_size >>>>>> >>>>>> I can't really figure out...~_~ >>>>> >>>>> level_size is just a small correction for the space the tree root >>>>> occupies. The tree root is never shared between sub volumes. >>>> >>>> O.K. I got it.. >>>> >>>> Thanks, >>>> Wang >>>> >>>>> >>>>> -Arne >>>>> >>>>>> >>>>>> Thanks, >>>>>> Wang >>>>> >>>> >>> >> > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
