It's possible that the device map is smaller than the offset into the device
for the I/O we're adding. Add a check for it and bail out, otherwise we
risk botching the bio calculations that follow.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trondmy@gmail.com>
f34462c3c8