My brother took our 15'x18' canvas cabin's white wall tent for the weekend and ended up putting a 2-3" tear in the roof

, about 3' in from the edge towards the peak. He had 1' spike anchors holding down the tent (in sandy soil), and the wind came and picked up the whole ******* tent and blew it into a tree with a sharp broken limb.
The tent is about 5 years old and is in pretty good shape otherwise.
Just looking for suggestions for a quality repair. Do you just cut a like piece of fabric and glue it on? What kind of glue? Do you need to sew on the patch in additional to gluing? Sew only?
If home repair will result in a poor job, we would consider a pro. I wouldn't image that someone would touch this for much less than $50 to $75.
Any ideas from someone with tent repair experience?
Thanks
Blind Squirel