Not sure if this suits you but if your fabric isn’t ripped - just doesn't block light - you might try coating the inside with Loctite Color Guard:
http://www.acehardwareoutlet.com/Pro...SKU=1000003835
(didn't find a Canadian retailer online yet)
This is what the people at Clam shelters recommend when the black lining starts to wear off their tents:
http://www.clamcorp.com/AboutUs/Cust...5/Default.aspx
From their website:
"Q: There are cracks on the inside finish of the fabric of my shelter. Is this normal? Can anything be done to fix this?
A: It is normal for some of the dark colored coating to come off the inside of the tent. Over time, as you set up and take down the shelter, the dark coating can begin to flake off, especially along the folds in the fabric when the shelter is collapsed. This does not affect the function of the fabric. If you feel that too much light is now entering your shelter in the places where some of the coating has come off, you may wish to apply a new layer of rubberized coating. A product you may use for this is Loctite Color Guard (black), available in liquid (paint-on) or aerosol form. The product number is LOC 34894. This is available at many hardware or home improvement stores."