Re: ext2fs superblock updates

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> From the looks of it, the ext2fs code only updates the primary
> superblock: [...]

> I'm under the impression that the secondary ones exist as backups and
> are meant to be usable.

> Is this wrong or am I misunderstanding things?

I don't know ext2.  But I have seen it said that it's basically slimiar
to FFS, and I do know FFS.

If we were talking about FFS instead, I'd say, the backup superblocks
are meant to be usable - for fsck.  Not for live use.  In particular,
all the superblock data that FFS mutates in live use is data that fsck
knows how to regenerate.  Thus, there is never any need to update the
backup superblocks - they are generated by fsck and left untouched
thereafter.

How applicable those remarks are to ext2 depends, of course, on how
similar ext2 is to FFS in these respects.

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