That is a problem with the drive or tmp mount. Without checking it there's not much that anyone can tell you. Sometimes rebooting resolves it but it should be checked by your datacenter first in case there is a more serious underlying problem.
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A read only filesystem is usually indicative of errors within the filesystem itself. You'll see busier webhosting machines put fs's into read only mode after enough dirty writes and general bad-mojo. This is the filesystems way of protecting itself from further corruption.
Now there's a chance that this may just be the tmp directory that's messed up like this. You can always try creating your own tmp directory in your homedir and referencing that in your scripts.
You might also attempt to upload a small file to your account. If that fails with the same error, you're going to need to fsck the affected partitions in order to correct it.
Also since this is your personal machine, you can always just try to unmount /tmp/ and remount it and see if that clears it up.
from a root shell...
umount /tmp && mount /tmp
Keep in mind after you do this you may need to restart MySQL as well in order for it to recreate it's socket (may and/or may not be in /tmp/).