Re: [PATCH]fs/jffs2/wbuf.c: add compatibility support for OOB data block

Artem B. Bityuckiy
2005-08-15T13:39:24Z

Ok, let's change JFFS2. I would prefer just alwayse assume 1:1 mapping
and always use vmalloc in JFFS2 for c->blocks[] (no 128K limitation).

For compatimility, we need to be able to fallback to the old JFFS2
algorithms.

And here we definitely must introduce the way to recognise versions of
the image. We may introduce the version number to clean markers. We also
must set INCOMPAT flag in clean markers to prevent new images to be
mounted by old JFFS2s. New JFFS2s will mount the FS only if the version
is <= then the current JFFS2 version. Something like this. Versioning
will anyway be useful in future.

Moreover, Forrest is adding the trick to store the erase count at the
beginning of each eraseblock. So, we may store this erasecount in clean
markers as well. Then we may rename "clean marker" to "node header".

On NAND, clean marker is in OOB of the first page. As new cleanmarkers
become larger, we may span them to the 2nd, the 3rd, etc OOBs.

Comments?

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.