8baed3606be67900df9f02e42fcdb091b78c5def parent 7d76345da6ed3927c9cbf5d3f7a7021e8bba7374 author Andi Kleen 1231211109 +0000 committer Alasdair G Kergon 1231211109 +0000 dm: support barriers on simple devices Implement barrier support for single device DM devices This patch implements barrier support in DM for the common case of dm linear just remapping a single underlying device. In this case we can safely pass the barrier through because there can be no reordering between devices. NB. Any DM device might cease to support barriers if it gets reconfigured so code must continue to allow for a possible -EOPNOTSUPP on every barrier bio submitted. - agk Signed-off-by: Andi Kleen Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon FS