This is a proposal patch for cp to have default behavior of doing reflink copies. Many in the BTRFS community have for some time expected that this should be the default behavior for cp as it is for mv, but it seems that this is not the case.
This patch is inspired by David Sterba's 2014 patch: commit b47231be6813e6cb5305266e391b4bb745f27f13 mv: use reflink=auto mode by default
