On Wed, Jan 12, 2022 at 02:03:45AM +0800, Yamadaえりな wrote: > For a debian based system, how can I setup that, if a dir has total storage > size reached to the max, it won’t be writable anymore?
That sounds tricky. It depends on your exact needs, and the exact "threat" you're protecting against. My initial thought, if you don't have too many of these "directories", is to make each of them a separate file system, and mount it. The file system can be created with the size you want, and then when that file system is full, nothing more can be written to it. Using LVM would be my preference if you go this way. It allows the creation of lots of file systems "on the fly". Using real partitions might also work in theory, but it would be my second choice, by far. If you don't want a file system per directory, e.g. if you've got a *whole* lot of these directories, or if you need them to be create-able without root being involved, then maybe you can cobble something together to restrict permissions after the fact. E.g. a cron job that runs every 5 minutes (or whatever), looks at the directories that are still writable (ignoring the ones that aren't), and if any one of them is over its size limit, change the permissions on it, and on all the files inside it. Of course, there are obvious flaws with that approach. A lot of data could be written in those 5 minutes, and could put a directory *way* over the limit you intended. And if a file is already opened for writing inside one of the directories, changing the permissions won't stop the process from continuing to write to that open file. It only stops new files being created, or subsequent file opens.
