CVE-2026-80859 fuse: fix missing barrier when checking io-uring readiness

In the Linux kernel, the following vulnerability has been resolved: fuse: fix missing barrier when checking io-uring readiness fuseblockalloc reads fch-initialized and then fch-iouring. fch-iouring is set before fch-initialized, ordered by the smpwmb in fusechansetintialized, but fuseblockalloc h...