Re: [PATCH v2 2/3] ext4: add support for IV_INO_LBLK_64 encryption policies

["Theodore Y. Ts'o" <tytso@mit.edu>]

On Thu, Oct 24, 2019 at 02:54:37PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> IV_INO_LBLK_64 encryption policies have special requirements from the
> filesystem beyond those of the existing encryption policies:
> 
> - Inode numbers must never change, even if the filesystem is resized.
> - Inode numbers must be <= 32 bits.
> - File logical block numbers must be <= 32 bits.
> 
> ext4 has 32-bit inode and file logical block numbers.  However,
> resize2fs can re-number inodes when shrinking an ext4 filesystem.
> 
> However, typically the people who would want to use this format don't
> care about filesystem shrinking.  They'd be fine with a solution that
> just prevents the filesystem from being shrunk.
> 
> Therefore, add a new feature flag EXT4_FEATURE_COMPAT_STABLE_INODES that
> will do exactly that.  Then wire up the fscrypt_operations to expose
> this flag to fs/crypto/, so that it allows IV_INO_LBLK_64 policies when
> this flag is set.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

LGTM

Acked-by: Theodore Ts'o <tytso@mit.edu>

						- Ted