Since the unstripe target takes a target length which is the
size of *one* striped member we're trying to expose, not the
total size of *all* the striped members, the check does not
make sense and fails for some striped setups.
For example, say we have a 4TB striped device:
or 3907018496 sectors per underlying device:
if (sector_div(width, uc->stripes)) :
3907018496 / 2(num stripes) == 1953509248
tmp_len = width;
if (sector_div(tmp_len, uc->chunk_size)) :
1953509248 / 256(chunk size) == 7630895.5
(fails)
Fix this by removing the first check which isn't valid for unstriping.
Signed-off-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This device mapper "unstriped" target remaps and unstripes I/O so it
is issued solely on a single drive in a HW RAID0 or dm-striped target.
In a 4 drive HW RAID0 the striped target exposes 1/4th of the LBA range
as a virtual drive. Each I/O to that virtual drive will only be issued
to the 1 drive that was selected of the 4 drives in the HW RAID0.
This unstriped target is most useful for Intel NVMe drives that have
multiple cores but that do not have firmware control to pin separate LBA
ranges to each discrete cpu core.
Signed-off-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
