Hello Chuck and John,

Chuck Smith:
> and my /proc/mounts for aufs looks like this
> aufs / aufs 
> rw,si=f6a293c0,xino=/mnt/ram/memory/.aufs.xino,nowarn_perm,br:/mnt/ram/memory/changes=rw:/mnt/ram/aufs/cls-cd-devel.lzm=ro:/mnt/ram/aufs/x11-081005.lzm=ro:/mnt/ram/aufs/srv-081005.lzm=ro:/mnt/ram/aufs/oth-081005.lzm=ro:/mnt/ram/aufs/off-081005.lzm=ro:/mnt/ram/aufs/med-081005.lzm=ro:/mnt/ram/aufs/kde-081005.lzm=ro:/mnt/ram/aufs/dev-081005.lzm=ro:/mnt/ram/aufs/con-081005.lzm=ro:/mnt/ram/aufs/X-081005.lzm=ro:/mnt/ram/aufs/bas-081005.lzm=ro
>  
> 0 0
> 
> which means this script would probably will not help most people as I don't 
> know how to find the aufs branches any other way  :(

There are similar procedure in the scripts under $AufsCVS/aufs/util. I
hope they will help you.

Basically there are two approaches to find the specified name from aufs
branches.
- run find(1)
- ask aufs itself

The former is the one which Chuck took (and
$AufsCVS/aufs/sample/unionctl --whereis). Several years ago I had a plan
to implement in this way, but set its priority lowest now because I
don't think it is useful. The incompleted script is left
$AufsCVS/aufs/util/aufind.sh still.
In this approach, you may get the lower path which is whiteouted by the
upper branch.

The latter is ioctl(2) (plus alpha) essentially, and aufs returns the
branch index which the specified name exist. In this case, the
whiteouted names which exist on the lower branch will not be returned
since aufs doesn't keep them. I am not sure this behaviour is expected
by John.
Additionally, when the name is a special file, ioctl(2) will not work
since the corresponding handler is out of aufs. So such ioctl will be
implemented for a dir in aufs and it will lookup the name. The interface
is what I am considering now.


J. R. Okajima

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