[Samba] Share problem : vfs object and preexec

[Xylle]

Helo,

I'm having a problem creating a share.
When creating a user share, I use the preexec function to create their 
folder. Everything works fine.
If I activate the shadowcopy 2 module, the preexec function no longer 
works for the share. The same applies to the root preexec function.
To get around the problem, I use the preexec function at global level.

I'd like to know whether this is normal operation or a bug.
If it's a bug, would it be possible to know on which platform it should 
be declared?

My share declaration :
------------------------------------------------------------------------
[%U]
   path = /srv/samba/personnel/%U
   read only = no
   guest ok = no
   create mask = 700
   directory mask = 700
   vfs objects = shadow_copy2
   shadow:snapdir = .zfs/snapshot
   shadow:sort = desc
   shadow:format = simple-%Y-%m-%d-%H%M
   shadow:localtime = yes
   # preexec = mkdir -p "/srv/samba/personnel/%U"
------------------------------------------------------------------------