libfs: Modify mount_pseudo_xattr to be clear it is not a userspace mount

Add MS_KERNMOUNT to the flags that are passed.
Use sget_userns and force &init_user_ns instead of calling sget so that
even if called from a weird context the internal filesystem will be
considered to be in the intial user namespace.

Luis Ressel reported that the the failure to pass MS_KERNMOUNT into
mount_pseudo broke his in development graphics driver that uses the
generic drm infrastructure.  I am not certain the deriver was bug
free in it's usage of that infrastructure but since
mount_pseudo_xattr can never be triggered by userspace it is clearer
and less error prone, and less problematic for the code to be explicit.

Reported-by: Luis Ressel <[email protected]>
Tested-by: Luis Ressel <[email protected]>
Acked-by: Al Viro <[email protected]>
Signed-off-by: "Eric W. Biederman" <[email protected]>

0 files changed, 0 insertions, 0 deletions