Jan Kara wrote: > Hi, > >> We have a proposal to implement a 2-level disk quota on ext3 and ext4. >> >> In two words - the aim is to have directories on ext3/4 partitions >> which are limited by its disk usage and the number of inodes. Further >> the plan is to allow configuring uid and gid quotas within them. > If I understand it right, this is something like XFS's project quota, > right? Not exactly. XFS tree quota actually replaces gid one. My proposal is to add the 3rd id. > Note that such thing has implications such as you have to forbid > hardlinks between different "quota trees", otherwise it just won't fly... Yes, I know it. We know other things we'll have to disable, but this is OK to live without them. > Also by 2-level, you mean it won't be possible to nest such subtrees? As I see it - nesting can be done on top of it. I mean - once we have a tree id of an inode and if we say "id A is a sub-id of id B" we're done. As far as containers are concerned - we'll have to map container id to quota tree id, since changing a container id is fast and simple, but it's not so for tree id. That said, this treeid is just a way do distinguish inodes from one sub-tree from the others. > I.e. have a quota on directories a/, b/, a/b, a/c? > >> The main usage of this is containers. When two or more of them are >> located on one disk their roots will be marked with a unique tree id >> and thus the disk consumption of each container will be limited. While >> achieving this goal having an id of what tree an inode belongs to is >> a key requirement. >> >> So first we would like to ask to reserve a place on ext3 and ext4 inodes >> for that ID. > Do you really need to store tree ID on disk? I'd think that it should > be enough to keep some id / pointer in memory and initialize it when we > load inode into memory (from an id / pointer of parent directory). Then > it would be enough to store a fact that some directory is a root of > "quota tree" somewhere - either in extended attributes, as a flag in > the inode, or together with quota data. We can't do it inside ext4_nfs_get_inode unfortunately :( > Honza -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
