WireGuard for the Linux kernel https://git.zx2c4.com/wireguard-linux/atom/tools/testing/selftests/filesystems/ustat_test.c?h=stable 2026-06-29T08:31:54Z 2026-06-29T08:31:54Z Christian Brauner brauner@kernel.org 2026-06-16T14:08:34Z urn:sha1:a21db4dcaf4ad617c6f7aa9e4c879cf0d797631b user_get_super() is now backed by the global device-to-superblock table instead of a walk of the super_blocks list. ustat(2) is its most direct user-visible consumer but nothing in the tree exercises it. Add a small regression test: the device number of a mounted tmpfs (an anonymous device, registered in the table by sget_fc()) must resolve, it must stop resolving after the unmount (the entry is dropped again in kill_super_notify()), and bogus device numbers keep reporting EINVAL. The test passes on kernels before the conversion: it pins down the semantics the table-backed lookup must preserve. Link: https://patch.msgid.link/20260616-work-super-bdev_holder_global-v2-18-7df6b864028e@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>