ovl: don't allow datadir only

In theory overlayfs could support upper layer directly referring to a data
layer, but there's no current use case for this.

Originally, when data-only layers were introduced, this wasn't allowed,
only introduced by the "datadir+" feature, but without actually handling
this case, resulting in an Oops.

Fix by disallowing datadir without lowerdir.

Reported-by: Giuseppe Scrivano <[email protected]>
Fixes: 24e16e385f22 ("ovl: add support for appending lowerdirs one by one")
Cc: <[email protected]> # v6.7
Reviewed-by: Amir Goldstein <[email protected]>
Reviewed-by: Alexander Larsson <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>

0 files changed, 0 insertions, 0 deletions