A couple corrections I'll include in the next version: On Sat, Apr 30, 2022 at 10:08:55PM -0700, Eric Biggers wrote: > + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) { > + if (fscrypt_dummy_policies_equal(&sbi->s_dummy_enc_policy, > + &ctx->dummy_enc_policy)) > + return 0; > ext4_msg(NULL, KERN_WARNING, > - "Can't set test_dummy_encryption on remount"); > + "Can't set or change test_dummy_encryption on remount"); > return -EINVAL; > } I think this needs to be 'fc->purpose == FS_CONTEXT_FOR_RECONFIGURE || fscrypt_is_dummy_policy_set(&sbi->s_dummy_enc_policy)', since ext4 can parse mount options from both s_mount_opts and the regular mount options. > +static void ext4_apply_test_dummy_encryption(struct ext4_fs_context *ctx, > + struct super_block *sb) > +{ > + if (!fscrypt_is_dummy_policy_set(&ctx->dummy_enc_policy)) > + return; To handle remounts correctly, this needs to be '!fscrypt_is_dummy_policy_set(&ctx->dummy_enc_policy) || fscrypt_is_dummy_policy_set(&EXT4_SB(sb)->s_dummy_enc_policy)'. - Eric