[Ocfs2-users] debugfs.ocfs2 and Feature Incompat

[Sunil Mushran]

On 06/01/2010 04:06 AM, Stefan Priebe - allied internet ag wrote:

<snip>
>           Feature Compat: 3 backup-super strict-journal-super
>           Feature Incompat: 8016 sparse extended-slotmap inline-data
> metaecc xattr indexed-dirs refcount
>           Tunefs Incomplete: 0
>           Feature RO compat: 1 unwritten
>
<snip>

> But why is inline-data, indexed-dirs and so on incompatible?

incompat means that a version of the fs not aware of this feature
should not mount the fs. And that fsck should abort. Users encountering
this error need to mount the fs with a newer version of the fs. Or, use
tunefs.ocfs2 to disable that feature.

Similarly, ro compat features means that a version of the fs not aware
of the feature can mount fs in read-only mode only.

As to which feature is incompat/ro/compat is a function of the disk format
change involved. Changes that do not negatively affect the functioning when
mounted with an older version are "compat". Changes that will corrupt the
fs if mounted with an older version are "incompat". "ro compat" are changes
that will work as long as the older fs does not write to it.