I changed partition label and i used this without reboot... safe or dangerous?

[newbie_]

I used the commands

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sudo umount /dev/sda5
and then

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sudo e2labl /dev/sda5 data
for change a partition label on my HD.
Then i mounted and used this partition without reboot (the label changed only after a reboot), is this safe or dangerous? i have very important data on this partition... thank you.