kern/60855: FFSv2ea superblok mismatch

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>Number:         60855
>Category:       kern
>Synopsis:       FFSv2ea superblok mismatch
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Oct 06 08:45:00 +0000 2026
>Originator:     paco
>Release:        11
>Organization:
>Environment:
NetBSD netbsd.home.arpa 11.0 NetBSD 11.0 (GENERIC) #0: Thu Jul 30 15:23:12 UTC 2026  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
When creating with newfs or converting a FFSv2 to FFSv2ea filesystem with fsck_ffs -c ea, the resulting FS has all but the first one superblock with a wrong magic number, running fsck on such filesystem correct the issue and dumpfs then report the alternate blocks with the same magic number and FS type (FFSv2ea and not FFSv2 only) than the first superblock.
>How-To-Repeat:
Create a new FFSv2ea FS or convert a FFSv2 to FFSv2ea and run fsck or dumpfs -a on it.
>Fix:
I guess that creating and converting the FS whith the correct magic number on all superblocks should correct the issue.