> - just make it return -EAGAIN instead of sleeping (which probably > just works fine and doesn't break anything and is simple)
It is very simple. But it does break things :-(. If I read one of these files using "dd bs=1", that used to read the whole file (while generating lots of SMI). With the -EAGAIN it just reads 100 bytes and says: dd: error reading 'DefSetup-e8a99903-302c-4851-a6be-ab2731873b2f': Resource temporarily unavailable 100+0 records in 100+0 records out 100 bytes copied, 0.153943 s, 0.6 kB/s > - add a per-user mutex, and do the usleep inside of it, so that > anybody who tries to do a thousand threads will just be serialized by > the mutex. > > Note that the mutex needs to be per-user, because otherwise it will be > a DoS for the other users. I can try that tomorrow (adding the per-user mutex to struct user_struct right next to the ratelimit I added. -Tony
