>From ATA spec proposal 1e:


8.55.3.8 Description (SMART ENABLE OPERATIONS)

This command enables access to all SMART capabilities within the device.
Prior to receipt of this command SMART data are neither monitored nor saved
by the device.

You HAVE to enable SMART as early as possible to have any meaningful data. 
And, as best I can tell, it is never DISABLED anywhere.  So once you read
from /proc/.../smart_values SMART is on.  

I think the patch is actually OK.  Unless you can point out where in the
spec I am missing something.

Tim
-- 
Tim Hockin
Systems Software Engineer
Sun Microsystems, Cobalt Server Appliances
thockin@sun.com