I want to give read-only permission to specific ip(say 1.1.1.111) and r/w permission to ip (1.1.1.112) on same share.
;[sdfs_vol1]
; path = /mnt/share1
; public = yes
; writable = yes
; read only = no
; force user = nobody
; hosts allow = 1.1.1.112

;[sdfs_vol1]
; path = /mnt/share1
; public = yes
; writable = no
; read only = yes
; force user = nobody
; hosts allow = 1.1.1.111
As suggestions I could search on net.But it seems that samba only takes last configuration.In upper case it would see every ip as read only and if I reverse it would become r/w for both ips.
Please help.

The problem you seem to be facing is your restricting access based on IP and not user accounts. That's not really the way SAMBA works, in addition to being file server software, it's also a user permissions repository and domain controller.

You'd probably have better luck creating a system account on the client machine, giving it sufficient local permissions to mount the slice and on the SAMBA server, restrict that account to "read only".