Re: [RFC] Draft Linux kernel interfaces for SMR/ZBC drives

[Theodore Ts'o <tytso@mit.edu>]

On Tue, Feb 11, 2014 at 12:04:12PM -0700, Andreas Dilger wrote:
> 
> Should ZBCRESETZONE take a length or number of zones to reset?

I was assuming that we would reset one zone at a time, which I think
is the main way this would be used.

Thinking about this some more, one other way we could do is to reuse
BLKDISCARD, with the restriction that the starting LBA (offset) must
be the first LBA for a zone, and offset + length - 1 must be last LBA
for a zone.  If either of these restrictions are violated, then
BLKDISCARD would return EINVAL --- or maybe some other error code,
since EINVAL can also mean an invalid ioctl code.  

Hmm... ERANGE would be good, but the strerror(ERANGE) returns "Math
result not representable", which would be highly confusing, although
it falls within the grand tradition of confusing Unix error messages,
such as "not a typewriter".  :-)

Any other suggestions?

						- Ted