linux-stable.git/tools/testing/selftests/filesystems/ustat_test.c, branch master Linux kernel stable tree selftests/filesystems: add ustat() coverage 2026-06-29T08:31:54+00:00 Christian Brauner brauner@kernel.org 2026-06-16T14:08:34+00:00 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> 
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>