Enable metadata encryption for userdata_gsi.

When running a live GSI, userdata is a logical partition. If we don't
fix up the fstab we'll derive the underlying block device instead of
the device-mapper node for userdat_gsi, resulting in a corrupt data
partition for both images.

Bug: 123906417
Test: manual test
Change-Id: Ic0101f30504de26e725442da2da3888008c31b63

main.cpp

@@ -226,7 +226,7 @@ static int process_config(VolumeManager* vm, bool* has_adoptable, bool* has_quot
     *has_adoptable = false;
     *has_quota = false;
     *has_reserved = false;
-    for (const auto& entry : fstab_default) {
+    for (auto& entry : fstab_default) {
         if (entry.fs_mgr_flags.quota) {
             *has_quota = true;
         }
@@ -234,6 +234,11 @@ static int process_config(VolumeManager* vm, bool* has_adoptable, bool* has_quot
             *has_reserved = true;
         }
 
+        /* Make sure logical partitions have an updated blk_device. */
+        if (entry.fs_mgr_flags.logical && !fs_mgr_update_logical_partition(&entry)) {
+            PLOG(FATAL) << "could not find logical partition " << entry.blk_device;
+        }
+
         if (entry.fs_mgr_flags.vold_managed) {
             if (entry.fs_mgr_flags.nonremovable) {
                 LOG(WARNING) << "nonremovable no longer supported; ignoring volume";