Jan Kara <jack@xxxxxxx> writes: >> 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. > Yeah, OK, but it's quite similar :) > >> > 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. > But for implementation, it's kind of important whether there is going > to be just one "tree" limitation for each inode, or arbitrary number of > them... > >> > I.e. have a quota on directories a/, b/, a/b, a/c? >> > I've post fs assumptions to Andreas's replay >> >> 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 :( Also we will have problems with orphan list cleanup on unclean umount. > Right, that's nasty. OK, but as Andreas suggested, extended attributes > are more flexible for this - most notably every fs supporting them would > be able to support your tree quota extension. > > 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
