Read-only partition, dual boot WIn10
The Windows 10 update reseted it to the default fast startup which is a form of hibernation.
You need to disable this feature (again, probably) in Windows and then shutdown, not reboot. Once done properly you'll be able to access the data partition normally with read/write permissions.
Open the terminal and write the command
sudo fdisk -l
It will show your file system
identify the partition you want permission for read and write
then type the command and give the partition name like this to your specific sda
sudo ntfsfix /dev/sda3
Sometimes the feature "Disable Fastboot" is prohibited to change by non-admin user by group policy restriction.
The below solution will help for all situations.
Login to windows, close all opened windows if any and execute following, from Run dialog
shutdown /f /r /t0
/f Force running applications to close without forewarning users.
/r Full shutdown and restart the computer.
/t xxx Set the time-out period before shutdown to xxx seconds, here /t0 for immediate shutdown.