JFFS2 SUMMARY nodes aren't working

[Joakim Tjernlund]

On Mon, 2007-03-26 at 07:37 -0500, Josh Boyer wrote:
> On Fri, 2007-03-23 at 18:24 +0100, Joakim Tjernlund wrote: 
> > 
> > I found that an all empty FS took about the same time to mount
> > which I find very strange.
> > 
> > Looking into the code in scan.c I found that even though I have
> > cleanmarkers in all EB:s, JFFS2 still scans the whole EB. Do
> > you really need to scan the whole area after the cleanmarker?
> > Should be enough to only check a few words after the clean marker
> > and if that is 0xffffffff then assume that the EB is clean
> > since it had a valid clean marker at the beginning.
> 
> No,  you can't just read a few words.  On some flash, the cleanmarker
> cannot be marked invalid in place so you still need to scan the rest of
> the block.  Sucks.

Not quite true, for the non XIP case you don't read more than
EMPTY_SCAN_SIZE(c->sector_size) before declaring it free.

JFFS2 has relied on this behavior in 2.4 and I see no reason to
change that.