Hi,
Possible bug:
It seems that /tmp is created as it’s own tmpfs mount point of size ~462M (half the ram on a RP2). The problem with that is that Firefox for example downloads files to /tmp first – which means you are limited to a file that size for a download.
If you force unmount (with a lazy unmount), it simply defaults onto the “tmp” dir in /, and everything is ok.
I am assuming this is in order to save the SD card from unnecessary writes for junk in /tmp.
Maybe the “bug” is that Firefox is writing to /tmp first and then moving the downloads when complete (will see if there’s a way to change that).
But either way, currently, you can’t download files larger than the size of /tmp, which is pretty limited.
UPDATE:
It looks like many others have mentioned this exact issue on the mozilla bug tracker:
The main issue being that FF either needs to specify a “temp download dir” or simply download the temp files in the real download dir.
It would be nice if /tmp can be mounted onto the SD card. But not sure if that would kill the SD card?