4896568 

Summary:
All comments in bug apply.

Patch:
http://icculus.org/~eviltypeguy/6249699.patch

Solution:
The solution appears to be exactly what was stated in the bug. Returning ENTOP instead of EINVAL since the error case in the UFS code is that you can't remount UFS read-only. Doing this should cause a correct error message instead of a puzzling and misleading one to be returned by mount.

Testing:
No testing beyond compilation and code review has been done. I am unsure how to test this particular change as I'm on a build 18 system and I don't think it would be a good idea to BFU using the build 16(?) sources for ON.