On Tue, 26 May 2009, Menshikov Konstantin wrote:
Yes. But jail cannot allocate block and inode above root path. In
allocation functions, whether for example ffs_alloc we have access to
ucred process and we can check up there is a process in jail.
Yes, you can check this for jailed process. Think about non-jailed
processes that can do allocation below the jail root.
Processes out of jail are not considered. I do not understand, these
processes have what relation to disk to quotas for jail. Please explain more
in detail
Historic UFS quotas are actually not interested in processes at all, really,
except in as much as processes are where exception states are exposed. UFS
quotas count blocks and inodes owned by users based on the 'uid' and 'gid'
fields in the inode. There's now 'jailid' field, so quotas on this model
can't capture the notion of per-jail quotas. In fact, quotacheck relies on
being able to walk the file system looking only at file system data in order
to establish initial usage accounting. You can imagine adding one, or
managing the uid spaces across jails such that all uids are unique, etc, but
all of these require some amount of rethinking.
Or, some other model of quota. Frankly, I've always been a fan of the AFS
model, now accessible locally via ZFS, in which lightweight volumes with quota
limits are used for individual user home directories, virtual machines, etc.
This was hard to do in FreeBSD before ZFS because (a) UFS didn't want to
resize trivially and (b) having lots and lots of mountpoints and file systems
wasn't something we made administratively easy.
Robert N M Watson
Computer Laboratory
University of Cambridge
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