[Bug 296466] copy_file_range can be very slow on zfs even for small files

From: <bugzilla-noreply_at_freebsd.org>
Date: Fri, 10 Jul 2026 23:51:26 UTC 
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=296466

--- Comment #9 from Rick Macklem <rmacklem@FreeBSD.org> ---
(In reply to martin from comment #8)
I'm not sure how frequent holes are, but maybe adding a "hole was created since
the last sync" flag would allow it to decide whether to force a sync before
looking for holes?

Is there an explanation why setting compression=off makes it fast?

You've mistaken me for someone that knows how ZFS works.;-)

You might try asking on OpenZFS? (I am aware that they know there
are issues with performance for SEEK_DATA/SEEK_HOLE and related
things.)

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