How to add custom files to pre-build riscv-ubuntu-20.04-img

[Naminar]

I'm trying to insert new files into pre-build riscv-ubuntu-20.04-img. Gem5 version is 24.0.1:

My steps are:

sudo losetup --partscan --find --show riscv-ubuntu-20.04-img

sudo mount /dev/loop0p1 /mnt

cp some.txt /mnt/home/ubuntu

sudo umount /mnt
sudo losetup -d /dev/loop0

So, when I'm restoring from checkpoint and trying to do:
cat ../home/ubuntu/some.txt

I'm getting like that:

EXT4-fs error (device vda1): ext4_lookup:1857: inode #507905: comm cat: deleted inode referenced: 507922`

I tried to use the modified disk image with that txt file to boot FS from the begging, During booting I got that:

0.083612]  driver: virtio_blk
[    0.083644]   fe01         7746526 vda1 45fa6226-ff94-4f04-be9b-ab2f432e36fe
[    0.083648] 
[    0.083686]   fe0c            4096 vda12 2a94359c-b806-4be3-b5d4-07e26f75b2c4
[    0.083690] 
[    0.083729]   fe0d            1024 vda13 2f80bdb1-4bea-45b1-af13-dc163478cdd7
[    0.083732] 
[    0.083771]   fe0e            4096 vda14 05e63dee-55ca-4646-a48e-3b48ffa7067b
[    0.083775] 
[    0.083813]   fe0f          108544 vda15 991b1afa-4f33-48e9-b2a5-8703046f8c79
[    0.083817] 
[    0.083857] No filesystem could mount root, tried: 
[    0.083859]  ext3
[    0.083881]  ext2
[    0.083892]  ext4
[    0.083903]  vfat
[    0.083914]  msdos
[    0.083925]  iso9660