ping.. > Hello, Arne > > Steps to reproduce: > > > mkfs.btrfs <disk> > mount <disk> <mnt> > btrfs quota enable <mnt> > > btrfs sub create <mnt>/sub > btrfs qgroup create 1/1 <mnt> > btrfs qgroup assign sub_qgroupid 1/1 <mnt> > > > dd if=/dev/zero of=<mnt>/sub/data bs=1M count=1 > sync > btrfs qgroup show <mnt> > #until now, every thing goes well, however, if snapshot happens > #the quota accounting will go wrong > > btrfs sub snapshot <mnt>/sub <mnt>/snap > sync > btrfs qgroup show <mnt> > #the accounting information of group(1/1) is not expected > #here exclusive of group (1/1) do not change as expected. > > So i took a close look at the algorithm of quota accounting, the 3 > steps of algorithm don't > consider some cases like the above example. > > In fact, i think you try to put some work on users, especially when > snapshot happens. > It is complex to track all the group's accounting when having > snapshots..See the following > commands. > > btrfs sub snapshot -c src_qgroupid:dst_qgroupid <mnt> > btrfs sub snapshot -x src_qgroupid:dst_qgroupid <mnt> > > > Are these commands designed for some cases regarding to > snapshots/subvolume cases? > If so, i think it really confusing and too complex for users to do > such work, is't it?... > > 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...~_~ > > Thanks, > Wang
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