This short series fixes up fuse uid/gid mount option handling.
First, as was done for tmpfs in
0200679fc795 ("tmpfs: verify {g,u}id mount options correctly")
it validates that the requested uid and/or gid is representable in
the filesystem's idmapping. I've shamelessly copied commit description
and code from that commit.
Second, it is switched to use the uid/gid mount helpers proposed at
https://lore.kernel.org/linux-fsdevel/8dca3c11-99f4-446d-a291-35c50ed2dc14@xxxxxxxxxx/T/#t
Both of these are compile-tested only.
Thanks,
-Eric
