makefs: zfs uberblock location is calculated wrong
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Authored by tsoome on Aug 11 2025, 1:43 PM.

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rG6e25c4321cd5: makefs: zfs uberblock location is calculated wrong

Summary

The shift used to calculate uberblock location depends both
on minimum size (UBERBLOCK_SHIFT) and MAX_UBERBLOCK_SHIFT.
Since makefs defaults to use ashift 12, it incidentally
does get the correct size, but ashift 9 does not work with
current code.

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rG FreeBSD src repository

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Buildable 66258
Build 63141: arc lint + arc unit

Event Timeline

tsoome created this revision.Aug 11 2025, 1:43 PM

Herald added subscribers: delphij, imp. · View Herald TranscriptAug 11 2025, 1:43 PM

tsoome requested review of this revision.Aug 11 2025, 1:43 PM

Harbormaster completed remote builds in B66163: Diff 160181.Aug 11 2025, 1:43 PM

tsoome added a reviewer: markj.Aug 11 2025, 1:44 PM

It'd be nice to have a helper macro for this, basically the same as VDEV_UBERBLOCK_SHIFT but just taking an integer ashift as a parameter. There is already one such macro in OpenZFS, ASHIFT_UBERBLOCK_SHIFT in zhack.c.

This revision is now accepted and ready to land.Aug 12 2025, 1:22 PM

use ASHIFT_UBERBLOCK_SIZE().

This revision now requires review to proceed.Aug 15 2025, 7:36 AM

Harbormaster completed remote builds in B66258: Diff 160390.Aug 15 2025, 7:36 AM

markj accepted this revision.Aug 15 2025, 11:12 AM

This revision is now accepted and ready to land.Aug 15 2025, 11:12 AM

Closed by commit rG6e25c4321cd5: makefs: zfs uberblock location is calculated wrong (authored by tsoome). · Explain WhyAug 15 2025, 12:12 PM

This revision was automatically updated to reflect the committed changes.

tsoome added a commit: rG6e25c4321cd5: makefs: zfs uberblock location is calculated wrong.