kern/60624: warning fatigue: /dev/fss0: file system not clean (fs_clean=0); please fsck(8)

>Number:         60624
>Category:       kern
>Synopsis:       warning fatigue: /dev/fss0: file system not clean (fs_clean=0); please fsck(8)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Aug 20 19:25:00 +0000 2026
>Originator:     Taylor R Campbell
>Release:        current, 11, 10, 9, ...
>Organization:
Acme Snapshot Cleaning, Inc.
>Environment:
>Description:

	Mounting a snapshot of an ffs file system causes the following
	scary warning to be sent to the console, even though there is
	nothing awry:

		/dev/fss0: file system not clean (fs_clean=0); please fsck(8)

	This happens both with external snapshots and with persistent
	internal snapshots.

>How-To-Repeat:

	1. fssconfig fss0 / /
	2. mount /dev/fss0 /mnt

>Fix:

	Either the superblock should be written back clean, rather than
	dirty, for the snapshot, or the warning should be avoided in
	some other way so it doesn't lead to warning fatigue and making
	fss(4) snapshots seem scarier than they are.