[dm-devel] question regarding snapshot chunk size.

[Dave Olien]

I'm using your udm1 patch set to linux 2.6.6-rc2.
The man page for lvcreate says the chunksize parameter for a
snapshot can be a power of two value between 4k and 1024k.

When I try --chunksize 1024, I hit a BUG() in the bvec_index()
function.

Putting some checking code into snapshot_ctr(), I observe that
when the lvcreate --chunksize 1024 parameter is used, snapshot_ctr()
reports a chunksize of 2048.  This is the value just after the
simple_strtoul() call.

So, why is the value being doubled (by the lvcreate command?).

Also, why is there no range check on the value in snapshot_ctr(),
with a error code failure, rather than a BUG() call in bvec_index?

Thanks!

Dave Olien