Let's update the list with the latest file-systems that added support. You can easily verify this by "git grep FS_ALLOW_IDMAP" on the given Linux version to see that the fs is listed and then checkout the previous Linux version to see that it is not listed, therefore it was added in that version. $ diff -w -U0 \ <(git grep FS_ALLOW_IDMAP v6.8 | sed 's/^v6.8://') \ <(git grep FS_ALLOW_IDMAP v6.9-rc4 | sed 's/^v6.9-rc4://') \ | tail -n+4; +fs/hugetlbfs/inode.c: .fs_flags = FS_ALLOW_IDMAP, $ diff -w -U0 \ <(git grep FS_ALLOW_IDMAP v6.6 | sed 's/^v6.6://') \ <(git grep FS_ALLOW_IDMAP v6.7 | sed 's/^v6.7://') \ | tail -n+4; +fs/ceph/super.c: .fs_flags = FS_RENAME_DOES_D_MOVE | FS_ALLOW_IDMAP, $ diff -w -U0 \ <(git grep FS_ALLOW_IDMAP v6.2 | sed 's/^v6.2://') \ <(git grep FS_ALLOW_IDMAP v6.3 | sed 's/^v6.3://') \ | tail -n+4; +mm/shmem.c: .fs_flags = FS_USERNS_MOUNT | FS_ALLOW_IDMAP, $ diff -w -U0 \ <(git grep FS_ALLOW_IDMAP v6.1 | sed 's/^v6.1://') \ <(git grep FS_ALLOW_IDMAP v6.2 | sed 's/^v6.2://') \ | tail -n+4; +fs/squashfs/super.c: .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP, Signed-off-by: Rodrigo Campos <rodrigo@sdfg.com.ar> Signed-off-by: Alejandro Colomar <alx@kernel.org>