[Samba] [samba 4.0] read only = yes + Denymode DENY_WRITE

[danny]

Hello,

Our samba fileserver is a member of a Windows 2008R2 domain, and has 
different shares. These shares are set with a "read only = yes" and have 
an explicit "write list". This works as planned.
But when an "read only" user opens a pdf with Adobe acrobat, the file 
gets DenyMode DENY_WRITE and the user who can edit the file can't save 
the document anymore. After the readonly user closes the file, the file 
can be saved again by the user who is allowed to edit it.

13007        23132      DENY_WRITE 0x120089    RDONLY     NONE 
    /data/testshare   file1.pdf   Fri Dec 19 11:30:16 2014

As far as I can see Word, Excel or any other document don't have this 
problem.

[global]
	workgroup = DOMAIN
	realm = DOMAIN.EU
	server string = %h server
	security = ADS
	log file = /var/log/samba/log.%m
	max log size = 1000
	server max protocol = SMB2
	load printers = No
	winbind separator = +
	winbind enum users = Yes
	winbind enum groups = Yes
	winbind use default domain = Yes
	idmap config DOMAINEU:backend = rid
	idmap config DOMAINEU:range = 20000 - 49999
	idmap config * : range = 2000-2999
	idmap config * : backend = tdb
	hide unreadable = Yes


[testshare]
       path = /data/testshare
       read only = Yes
       write list = @"DOMAINEU+domain admins"
       comment = testshare
       create mask = 770
       directory mask = 770
       ea support = yes
       map hidden = no
       map system = no
       map archive = no
       map readonly = no
       store dos attributes = yes

Is this behaviour of Samba as expected or am I missing something? 
Because the way as I see it, the file shouldn't be locked by a readonly 
user.

Regards,
Danny