Subject: Re: UBC problems
To: Chuck Silvers <>
From: Steven M. Bellovin <>
List: tech-kern
Date: 01/15/2005 10:36:39
In message <>, Chuck Silvers writes:

>> -I now believe that the best way to deal with this would be to
>>  have UBC reads just return zero filled pages if the file is
>>  not backed with real data, and let upper layers (above the
>>  trap handler) check whether the read is legal. Just commenting
>>  out the range check in genfs_getpages() isn't enough,
>>  unfortunately. That's a pretty complex matter...
>creating pages for offsets past EOF is to be avoided in general, since
>it's pretty nonsensical.  I checked in a different fix for this issue,
>update uvm_bio.c.

I don't understand -- are you trying to bar files with holes in them?  
That's been part of Unix since the beginning.

		--Prof. Steven M. Bellovin,