Re: How to enable CONFIG_EXT4_ENCRYPTION

Eric Biggers
2017-08-07T19:31:41Z

On Mon, Aug 07, 2017 at 09:49:42AM -0400, Theodore Ts'o wrote:
> On Mon, Aug 07, 2017 at 05:51:26PM +0800, Dai Xiang wrote:
> > On Mon, Aug 07, 2017 at 11:25:02AM +0800, Dai Xiang wrote:
> > > Hi!
> > >
> > > I use xfstests with ext4 fs to test, and i found a skip:
> > >
> > > ext4/024 [not run] kernel does not support ext4 encryption
>
> Yeah, the message printed is misleading, and should be fixed.
> Checking to see whether the kernel supports encryption can be done by
> checking for the existence of the file:
>
> /sys/fs/ext4/features/encryption
>
> > i print the cmd:
> > /usr/sbin/xfs_io -i -c set_encpolicy /fs/scratch/tmpdir
> > /fs/scratch/tmpdir: failed to set encryption policy: Inappropriate
> > ioctl for device <===
> >
> > Seems do not related to kconfig?
>
> Yes, the issue is that you need to create the file system (or set via
> tune2fs) the feature flag "encrypt". To best test the read/write
> paths, you should set the mount option test_dummy_encryption. The
> kvm-xfstests and gce-xfstests framework do all of this automatically.
> From xfstests-bld/kvm-xfstests/test-appliance/files/root/cfg/fs/ext4/encrypt:
>
> SIZE=small
> export EXT_MKFS_OPTIONS="-O encrypt"
> export EXT_MOUNT_OPTIONS="test_dummy_encryption"
> REQUIRE_FEATURE=encryption
> TESTNAME="Ext4 encryption"
>
> There are a number tests that are known to fail; primarily having to
> do with quota support, which doesn't play well with
> test_dummy_encryption (that's more of a test problem than anything
> else). See the encrypt.exclude file in that directory for more
> details.
>

Actually, this is one of the tests in the "encrypt" group, which format the
scratch device with "-O encrypt". So I believe the printed message is correct.
Are you 100% sure that CONFIG_EXT4_ENCRYPTION is enabled in your kernel config
and that you are running the correct kernel?

Eric