[OnePlus 3 & 3T Cross Device Development] :
To my knowledge forced encryption is set or unset in fstab:

ingo@adler /usr/local/src/cm14 $ diff -u device/oneplus/oneplus3/rootdir/etc/fstab.qcom ../oxygenos/fstab.qcom
--- device/oneplus/oneplus3/rootdir/etc/fstab.qcom 2017-01-26 16:05:42.185473621 +0100
+++ ../oxygenos/fstab.qcom 2017-04-01 13:53:32.084816150 +0200
@@ -5,18 +5,11 @@
#TODO: Add 'check' as fs_mgr_flags with data partition.
# Currently we dont have e2fsck compiled. So fs check would failed.

-#<src> <mnt_point> <type> <mnt_flags and options> <fs_mgr_flags>
-/dev/block/bootdevice/by-name/boot /boot emmc defaults defaults
-/dev/block/bootdevice/by-name/recovery /recovery emmc defaults defaults
-/dev/block/bootdevice/by-name/system /system ext4 ro,barrier=1,discard wait
-/dev/block/bootdevice/by-name/userdata /data f2fs nosuid,nodev,noatime,inline_xattr,data_flush wait,check,encryptable=footer,formattable,length=-16384
-/dev/block/bootdevice/by-name/userdata /data ext4 nosuid,nodev,noatime,barrier=1,noauto_da_alloc wait,check,encryptable=footer,formattable,length=-16384
-/dev/block/bootdevice/by-name/cache /cache f2fs nosuid,nodev,noatime,inline_xattr,flush_merge,data_flush wait,check,formattable
-/dev/block/bootdevice/by-name/cache /cache ext4 nosuid,nodev,noatime,barrier=1 wait,check,formattable
-/dev/block/bootdevice/by-name/persist /persist ext4 nosuid,nodev,barrier=1 wait
-/dev/block/bootdevice/by-name/dsp /dsp ext4 ro,nosuid,nodev,barrier=1 wait
-/dev/block/bootdevice/by-name/modem /firmware vfat ro,shortname=lower,uid=1000,gid=1000,dmask=227,fmask=337,context=u:object_r:firmware_file:s0 wait
-/dev/block/bootdevice/by-name/bluetooth /bt_firmware vfat ro,shortname=lower,uid=1002,gid=3002,dmask=222,fmask=333,context=u:object_r:bt_firmware_file:s0 wait
-/dev/block/bootdevice/by-name/misc /misc emmc defaults defaults
-
-/devices/soc/6a00000.ssusb/6a00000.dwc3/xhci-hcd.0.auto/usb* auto auto defaults voldmanaged=usbdisk:auto
+#<src> <mnt_point> <type> <mnt_flags and options> <fs_mgr_flags>
+/dev/block/bootdevice/by-name/system /system ext4 ro,barrier=1,discard wait,verify
+/dev/block/bootdevice/by-name/userdata /data f2fs noatime,nosuid,nodev,discard,nodiratime wait,check,forceencrypt=footer,resize
+/dev/block/bootdevice/by-name/userdata /data ext4 nosuid,nodev,barrier=1,noauto_da_alloc,discard,errors=panic wait,check,forceencrypt=footer,resize
+#/devices/soc/74a4900.sdhci/mmc_host* /storage/sdcard1 vfat nosuid,nodev wait,voldmanaged=sdcard1:auto,encryptable=footer
+/dev/block/zram0 none swap defaults zramsize=536870912
+/dev/block/bootdevice/by-name/misc /misc emmc defaults defaults
+/devices/soc/6a00000.ssusb/6a00000.dwc3/xhci-hcd.0.auto/usb* auto auto defaults voldmanaged=usbotg:auto

fstab is in the ramdisk. To change a file in ramdisk, I suggest using https://github.com/osm0sis/AnyKernel2. Done once, you can just flash it after each update.

I don't think it makes sense to bake it in the rom, because nobody would be able to run the rom without encrypted data. partition Also: if your current data partition is NOT encrypted your system will refuse to boot.

Anyway: even without forced encryption you can run the rom with encryption active.

[MENTION=5091734]dianlujitao[/MENTION]: for the TODO: since lineage has e2fsck on board and "check" is allready given as mount option, these two lines should be removed, shouldn't they?

---------- Post added at 09:56 ---------- Previous post was at 09:52 ----------

It crashes the first time you use the frontcam after reboot. Just wait for a minute or two after the crash, restart Snap and use frontcam - untill next reboot.