It would be useful if ikiwiki could reject adding file with names
longer than some limit, like 255 bytes. I've had some git-annex users
complain that some files ended up longer than that, which won't work on
some OS's and filesystems.

255 might be a good default value, even.

This would apply to pages created following broken wikilinks and using
blogpost forms, as well as to uploaded attachments, and perhaps aggregated
pages. In the wikilink case, I guess ikiwiki would need to reject it as
too long; in the other cases it could simply pick a shorter version of
the proposed filename.

--[[Joey]] 
