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Comment by ryao | Hacker News Reader

A FreeBSD developer wrote this code.

and then there were deep concerns about the stability of same, so vfs.zfs.bclone_enabled = 0 was left in-place

So far nobody has proven that this bug exists on FreeBSD, though. :)

Because FreeBSD is behind Linux in copying with reflinks. They couldn't even reproduce the issue if they wanted to.

This code was implemented for FreeBSD before it was implemented for Linux. I do not think it has made it to a FreeBSD release yet though.

It’s in FreeBSD 14. But they disabled block cloning by default.

This hit Linux first, which is why Linux experienced the issue. FreeBSD does not currently have reflink cp.

The bugs are in cross platform code beneath the VFS. They exist on FreeBSD too.

Looks like a deeper bug has been exposed due to the way bclone works? They're finding issues now on ZFS versions predating bclone

Edit: yep, it's an older bug. Set zfs_dmu_offset_next_sync=0 to save your data

Not sure what's your point. The comment I linked to just confirmed that the bug (whichever it might be) has reproduced on FreeBSD.

Just following up for the readers of the thread

Nope, somebody managed to reproduce this issue even with zfs_dmu_offset_next_sync=0

Apply this patch, it appears to be the real fix.