I recently switched a Windows server over to Linux, and needed a way to use the Digital Filing feature of an HP Officejet Pro 7680 (C8189A) to continue to provide users with the ability to scan to PDF. Samba is a great tool which allows Linux machines to offer file and print services to SMB/CIFS clients, including any version of Windows. I've used Samba frequently in the past, but had a hard time getting the Digital Filing feature on the L7680 working with it. When I tried to initiate a scan to pdf with Digital Filing, I would get an error that the HP L7680 was unable to write to the Samba share, even though it was easily accessible and writable from any Windows XP or Vista desktop.
I tried changing various Samba configuration settings, including turning off oplocks (setting oplocks = false, and level 2 oplocks = false in smb.conf). Unfortunately, none of those changes fixed the problem that the L7680 claimed it couldn't write to the Samba shared drive.
Finally, I decided to try changing from share-based security to user-based security in Samba ("security = user" vs "security = share" in smb.conf), which fixed the issue. It seems the L7680 expects user-based security, and refuses to function under share-based security. After changing the security type, setting up a Linux user, and running smbpasswd for the user, the L7680's Digital Filing worked as expected.