On Sun, Oct 01, 2023 at 07:10:53PM +0200, Wouter Verhelst wrote:

quoted

So what are the semantics of clearing the socket?

The <= 6.5 behavior of invalidating fs caches, but not actually marking
the fs shutdown is pretty broken, especially if this expects to resurrect
the device and thus the file system later on.

nbd-client -d calls

ioctl(nbd, NBD_DISCONNECT);
ioctl(nbd, NBD_CLEAR_SOCK);

(error handling removed for clarity)

where "nbd" is the file handle to the nbd device. This expects that the
device is cleared and that then the device can be reused for a different
connection, much like "losetup -d". Expecting that the next connection
would talk to the same file system is wrong.

So a fs shutdown seems like a the right thing.  So I'm a little confused
on what actualy broke here.