On Mon, Jun 3, 2019 at 1:07 PM Ilya Dryomov <idryomov@xxxxxxxxx> wrote: > Can we also discuss how useful is allowing to recover a mount after it > has been blacklisted? After we fail everything with EIO and throw out > all dirty state, how many applications would continue working without > some kind of restart? And if you are restarting your application, why > not get a new mount? > > IOW what is the use case for introducing a new debugfs knob that isn't > that much different from umount+mount? People don't like it when their filesystem refuses to umount, which is what happens when the kernel client can't reconnect to the MDS right now. I'm not sure there's a practical way to deal with that besides some kind of computer admin intervention. (Even if you umount -l, that by design doesn't reply to syscalls and let the applications exit.) So it's not that we expect most applications to work, but we need to give them *something* that isn't a successful return, and we don't currently do that automatically on a disconnect. (And probably don't want to?)
