I've been searching for answer to this question for quite some time now and finally decided I should as a question here.
So I've managed to find a kernel module (cifs.ko) for my kernel build on xda-developers forum/site. Then I ssh to my phone (GT-I9300) and as root issue
The module loads correctly. I can mount SMB shares using command
mount -t cifs -o username=login,password=secret //ip.address.goes.here/sharename /mount/point/goes/here
and this mounts correctly. Then I can cd into mounted directory and create, modify, delete, rename files/directories.
But when I start TitaniumBackup and change backup directory location to mounted folder and try to backup any application I get error "insufficient free storage space". Now how I could mount my share (I can host it as scp,sftp,ftp,smb,nfs,webdav) ?
I also tried using busybox to mount nfs share but I cannot find nfs.ko for my kernel and when I try to mount my share using busybox (or normal) I get an error that the device doesn't exist.
What I want to achieve is to backup my apps + data directly to my NAS instead of doing it locally first and then copying backups to my NAS.