On Fri, Jun 3, 2011 at 8:47 PM, Hugo Mills <[email protected]> wrote: > On Fri, Jun 03, 2011 at 06:24:41PM +0200, Arne Jansen wrote: >> Hi, >> >> If no one is already working on it, I'd like to take the Quota lock and >> see how far I come. >> Let me sketch out in short what I'm planning to do: >> >> - Quota will be subvolume based. Only the FS-trees and data extents >> will be accounted. >> - Quota Groups can be defined. Every quota group can comprise any >> number of subvolumes. A subvolume can be assigned to any number >> of quota groups. >> - A Quota Group can account/limit the total amount of space that is >> referenced by it and/or the amount of space that is exclusively >> referenced (i.e. referenced by no other quota group). >> - With this it is possible to define a hierarchical quota that need >> not necessarily reflect the filesystem hierarchy. >> - It is also possible to decide for each snapshot if it should be >> accounted into the parent group. So in a scenario where each >> subvolume reflect a user home, it's possible to have some snapshots >> accounted to the user and others not (e.g. the ones needed for system >> backups). >> - Quota information will be stored in new records, possibly in a >> separate tree. >> - It should be possible to change the Quota config and group >> assignments online, though this might need a full re-scan of the fs. >> - It does NOT include any kind of user/group (UID/GID) quota. >> >> Any addenda or arguments why it's impossible or insane welcome. > > There's a problem in that in some cases, it's possible to get into > a situation where you can't *delete* files because you're going over > quota. If I have two subvolumes that share most of their data > (e.g. one is a snapshot of the other), and both subvolumes have a > limit under the "exclusive use" clause, then deleting material from > subvolume A could cause subvolume B to go over quota. > > If users can create their own subvolumes, then using the "exclusive > use" form is also pointless, because as a user, I can simply snapshot > (or otherwise CoW copy) all my data into a snapshot, and I then don't > pay for it. That one probably comes under the "admin shot himself in > the foot", though. > > Getting out the bike-shed brush, I might suggest the use of some > name other than "quota", because inevitably people will think of > UID/GID-type quotas, and we've got enough confusingly-modified > terminology already. "Size bounds", "storage bounds", possibly?
Budget :)? Regards, Andrey > > Hugo. > > -- > === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === > PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk > --- Is it true that "last known good" on Windows XP --- > boots into CP/M? > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.10 (GNU/Linux) > > iD8DBQFN6RAiIKyzvlFcI40RAkkQAKCAulO65dL1F/vaO7W20qJEAKuonwCghfvH > XlliA+eCfmLmP/G0quVALe0= > =m513 > -----END PGP SIGNATURE----- > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
