I have a new flash drive of sandisk, I plugged in to the laptop. It mounted okay, but can’t do anything into it. I inspected it, and it read only.
According to the source here, there was something wrong with the mount utility. I have to do the following command in console to fix it.
sudo umount /dev/sdb1 (this is where my flash is mounted)
sudo dosfsck /dev/sdb1
But there was a warning said
fsck, dirty bit is set. Fs was not properly unmounted and some data may be corrupt.
1. Remove dirty bit
2. No action
bla bla bla …
Free cluster summary wrong (1753721 vs really 1873745)
2. Don’ Correct
I chose all the number 1 option.
Finally the verification to perform, I chose yes.
Then unplugged the flash and plug it in.
Now it is okay. I can read and write again.