Mods to aufs

I have been playing with /usr/sbin/snapmergepuppy, the script that saves the working layer in RAM to a save-layer (usually on a Flash device).

The problem has been that whiteout files themselves do not get saved to the save-layer. What this has meant is that files and directories in lower layers cannot be hidden, which I considered to be a good thing. But, I'm rethinking it, and now experimenting with saving whiteout files to the save-layer, so that files and directories below the save-layer can be "deleted".

A couple of problems with this change:

1. /etc/rc.d/rc.update cleans up the layers whenever the layer-configuration changes, and this also involves making sure that lower files and directories are not hidden. So, it would perhaps reverse the above change.

2. Aufs does not recognise whiteout files in the save-layer, just ignores them. There is a workaround for this though, by changing the attribute of the save-layer from 'ro' to 'ro+wh' in the 'init' script when the layer filesystem is created. There doesn't seem to an equivalent thing for Unionfs.

I'm experimenting, have to follow through with all the ramifications to my change.

CORRECTION
Er, no, the whiteout files are cleaned up in the 'init' script, before the layers get mounted. This occurs whenever a change in the layers is detected. The basic idea is that a whiteout file might be valid when created, but if the layers change then it might not be. So the init script makes sure all lower-level files are visible on top.

Posted on 26 Jan 2009, 8:58


Comments:

Posted on 24 Jan 2009, 17:32 by ferike
Wake on LAN
If you are focusing on these scripts, please include a little modification in rc.networc in 'stop' area
to permit puppy the "wake on LAN".
The condition should be not to disable the NIC on shutdown scrip, if WOL(wake on lan) was enabeled.
in 'rc.network' which is called by 'rc.shutdown', in 'stop_all()' function instead of simple 'ifconfig "$INTERFACE" down'
should be made a test by running 'ethtool "$INTERFACE" ' and testing if ' Wake-on: g ' was reported. If so, it means WOL is enabeld by user ( normaly it report ' Wake-on: d ' or some eror text that module does not support ethtool inquery) and 'ifconfig ethX down'should be skiped.Thanks.....http://www.depicus.com/wake-on-lan/


Posted on 24 Jan 2009, 21:45 by BarryK
rc.network
The current maintainer of the Network Wizard including /etc/rc.d/rc.network is forum member dougal. If he reads this he might check it out, or you can send him a pm via the forum.

I have just upgraded Woof to dougal's Dec. 7 version of the wizard. I did notice one thing, dougal if you are reading this -- rerwin submitted an extra 'sleep 1' in rc.network that I put into Pup 4.1.2 although that was the version of the wizard before the dec. 7. But, looking in the dec 7 version of rc.network, rerwin's patch isn't there. Probably it would be best if rerwin also submitted a patch direct to dougal.