Issue while using tune2fs
Solution 1:
Reserved blocks are already a part of the filesystem, you shouldn't have any expectation of getting a 'lot of extra space'.
If you fill up the filesystem as a regular (non-root) user it's not actually full. The reserved blocks are still there and ready for use, but only by the root user. Reducing the reserved blocks does not increase the space one bit, it simply allows a non-root user to fill up more of the space that is already available.