linux-ext4 - Re: How to enable CONFIG_EXT4

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Message-ID: <20170807193138.GA46084@gmail.com>
Date:   Mon, 7 Aug 2017 12:31:38 -0700
From:   Eric Biggers <ebiggers3@...il.com>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Dai Xiang <xiangx.dai@...el.com>, linux-ext4@...r.kernel.org
Subject: Re: How to enable CONFIG_EXT4_ENCRYPTION

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