unionfs: stowing feature

[Sergiu Ivanov]

Hello,

Recently I have been browsing the code implementing the stowing
feature in unionfs it struck me that I cannot figure out the reason
for it to be implemented in the way it is.

Normally the stowing feature works as follows: one starts unionfs in
the following way:

 $ settrans -a <node> unionfs --stow=<stow-directory>

At startup and at every change in <stow-directory>, unionfs reads the
list of subdirectories of <stow-directory> and adds all new
directories it finds to the list of merged directories and/or removes
the directories which are not longer present in <stow-directory>.

The stowing feature also allows a pattern-matching option, and it is
this option that confuses me.  When starting unionfs, one can specify
a shell wildcard via the ``--match=<wildcard>'' option which will be
used to filter the directories from <stow-directory>.  The filtering
is done in the following way: unionfs iterates through *all*
subdirectories of <stow-directory>, then it goes through all
sub-subdirectories of every subdirectory and adds those
sub-subdirectories which match the wildcard.  In other words, unionfs
adds the sub-subdirectories matching <stow-directory>/*/<wildcard>.

My problem is that I cannot see how this could be more useful than
filtering the first-level subdirectories of <stow-directory> (that is,
adding the subdirectories matching <stow-directory>/<wildcard>).
Also, such treatment of the wildcard is not something obvious, IMHO.
For instance, it makes the following two commands fundamentally
different:

 $ settrans -a <node> unionfs --stow=<stow-directory>
 $ settrans -a <node> unionfs -m "*" --stow=<stow-directory>

However, I would expect the second command to yield the same results
as the first one.

Could somebody tell me whether I'm missing something crucial?

Regards,
scolobb