[TUHS] VFS prior to 1984

[Dave Horsfall]

On Wed, 24 Jun 2020, Larry McVoy wrote:

>> In the end, early NFS was notorious for putting 'holes' in the files 
>> because of the automatic seek in every operation and errors not coming 
>> until close(2) time.
>
> You have no idea how many of those holes that 16 bit SCCS checksum has 
> found (BitKeeper kept it).

Aren't holes part of the file system semantics?  Seek beyond EOF, write a 
block, and you've created unallocated holes.  Of course, they are filled 
with zeroes as soon as you copy the file...  I did fiddle with "cp" to 
detect those holes and preserve them, but gave up for some reason 
(performance hit in checking for all-zero blocks, I think, along with some 
weird problem with the last block being all zeroes).

I used NFS when it first appeared and got bitten quite badly; I've never 
really trusted it ever since, but I understand that it's vastly improved.

-- Dave