Layout issue when parsing line

[Antara-Prabhat]

Hi,

I'm new to Lilypond.
I've learned only the very basics. 
When I typeset this score with Lilypond 2.18.0-1 on my mac, 
the 2nd dotted half note is being obscured by the glissando line.
Please help me resolve this issue by providing the solution 
or directing me to a documentation page where I may do so myself.
Thank you!

\version "2.18.0-1"
\include "english.ly"

        \relative c'' {
        \override Staff.BarLine #'break-visibility = #'#(#t #f #t)
        \key gf \major

\override Glissando #'style = #'trill

        bf8 bf df2. \glissando bf8 bf c2. \glissando af8 af bf2. 
\glissando gf8 gf af2.
}