UBUNTU-CVE-2026-90095: Medium severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: fuse: Fix the condition to enable over-io-uring The existing condition in fuseuringcmd() is there only to avoid disabling io-uring for connections that already run with it, missing was a condition to refuse any IORINGOPURINGCMD if the connection/channel didn't get enabled because of missing FUSEINIT reply flag FUSEOVERIOURING. Without the reply flag the barrier in fuseuringready() doesn't work and IO could already be going on and cause deadlock states (at a minimum one between fch->bglock and queue->lock). The change itself is trivial, but brings behavior change, FUSEOVERIOURING has to be set in the FUSEINITREPLY by fuse servers to accept any IORINGOPURINGCMD. Libfuse does that and the only non-libfuse implementation I found (fractal-fuse) also does it. Qemu patches for fuse-io-uring are not merged yet, as far as I know. Moved up is the smploadacquire(&fch->initialized) check, as a fuse-server implementation might try to setup io-uring before FUSEINIT is processed and might have gotten -EOPNOTSUPP instead of -EAGAIN. Also fixed is a stale comment that explains the handling of the FUSEOVERIOURING flag in early RFC versions. If there should be a report from any library or application we probably need to revert this commit.