feature request: --reflink

[Jens Korte]

Hi

When extracting files from an _uncompressed_ tar file on a btrfs
filesystem it would be nice if I could add a
--reflink[=never|_auto_|always], like cp has, and the tar command would
then "perform a lightweight copy" [1]. For cp it may be easier since
the files are referenced as a whole file. With tar the references would
be on block level. Maybe the changes could be written faster by an btrfs
developer.

There is a btrfs speed test from 2017 [2] where tar is used.

Greets
Jens Korte


[1] https://linux.die.net/man/1/cp
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs.git/commit/?h=next&id=5c1aab1dd5445ed8bdcdbb575abc1b0d7ee5b2e7