userns: Convert hostfs to use kuid and kgid where appropriate

Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fs/hostfs/hostfs_kern.c

@@ -542,8 +542,8 @@ static int read_name(struct inode *ino, char *name)
 	ino->i_ino = st.ino;
 	ino->i_mode = st.mode;
 	set_nlink(ino, st.nlink);
-	ino->i_uid = st.uid;
-	ino->i_gid = st.gid;
+	i_uid_write(ino, st.uid);
+	i_gid_write(ino, st.gid);
 	ino->i_atime = st.atime;
 	ino->i_mtime = st.mtime;
 	ino->i_ctime = st.ctime;
@@ -808,11 +808,11 @@ int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 	}
 	if (attr->ia_valid & ATTR_UID) {
 		attrs.ia_valid |= HOSTFS_ATTR_UID;
-		attrs.ia_uid = attr->ia_uid;
+		attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
 	}
 	if (attr->ia_valid & ATTR_GID) {
 		attrs.ia_valid |= HOSTFS_ATTR_GID;
-		attrs.ia_gid = attr->ia_gid;
+		attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
 	}
 	if (attr->ia_valid & ATTR_SIZE) {
 		attrs.ia_valid |= HOSTFS_ATTR_SIZE;

init/Kconfig

@@ -957,8 +957,6 @@ config UIDGID_CONVERTED
 	depends on UFS_FS = n
 	depends on XFS_FS = n
 
-	depends on !UML || HOSTFS = n
-
 	# The rare drivers that won't build
 	depends on ANDROID_BINDER_IPC = n