Re: [patch] ext2/3: document conditions when reliable operation is possible

[Florian Weimer]

* Pavel Machek:

> +Linux block-backed filesystems can only work correctly when several
> +conditions are met in the block layer and below (disks, flash
> +cards). Some of them are obvious ("data on media should not change
> +randomly"), some are less so.

You should make clear that the file lists per-file-system rules and
that some file sytems can recover from some of the error conditions.

> +* don't damage the old data on a failed write (ATOMIC-WRITES)
> +
> +	(Thrash may get written into sectors during powerfail.  And
> +	ext3 handles this surprisingly well at least in the
> +	catastrophic case of garbage getting written into the inode
> +	table, since the journal replay often will "repair" the
> +	garbage that was written into the filesystem metadata blocks.

Isn't this by design?  In other words, if the metadata doesn't survive
non-atomic writes, wouldn't it be an ext3 bug?

-- 
Florian Weimer                <fweimer@xxxxxx>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstraße 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/