JFFS2 destroys CRAMFS!

JFFS2 destroys CRAMFS!

[Bao C. Ha]

We are using RedBoot and have several MTD partitions.
One of the partitions has our minimal CRAMFS.  The
other contains JFFS2.  I made a mistake of compiling
a kernel with jffs2 built-in, but not cramfs.  The
bootup process tells the kernel to mount the cramfs
partition as the root device.  It just goes through 
and erased everything there, then it panics!

This behavior is not consistent with all other Linux
filesystems.  I would like to propose changes to the
designs of jffs2 as follows:

- Only make.jffs2 can create a jffs2 filesystem
- Unless jffs2 detects its MAGIC, it can't make
changes to the MTD partition.

It will save a lot of griefs later.  I know that
there are many work-arounds.  But, I had a mental
block that had refused to believe that a read-only
cramfs can be destroyed that easily.

Thanks.
Bao

Re: JFFS2 destroys CRAMFS!

[Jörn Engel]

Moin!

> - Unless jffs2 detects its MAGIC, it can't make
> changes to the MTD partition.

That appears to be a sane suggestion and would make me happy, too.
But, apart from the problem of existing FSs w/out the magic number,
there is also the question whether to use one MAGIC per FS or one per
delete block. The latter would definitely be nicer but might be
problematic with NAND flashes.

Jörn

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