bcachefs: Optimize fiemap

Reflink caused fiemap performance to regress badly - this gets us back
to where we were.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2019-08-22 16:12:28 -04:00 • committed by Kent Overstreet
commit 7d5224fcdc