Add a new API for incremental copying in or out of an iovec, and replace
current code to use the new API.
Signed-off-by: John Levon <john.levon@nutanix.com>
Change-Id: I088b784aef821310699478989e61411952066c18
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16193
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>