[PATCH v4 3/3] init/do_mounts.c: fix rootfs_fs_type with ramfs

[menglong8 . dong]

From: Menglong Dong <dong.menglong@xxxxxxxxxx>

As for the existence of second mount which is introduced in previous
patch, 'rootfs_fs_type', which is used as the root of mount tree, is
not used directly any more. So it make no sense to make it tmpfs
while 'CONFIG_INITRAMFS_MOUNT' is enabled.

Make 'rootfs_fs_type' ramfs when 'CONFIG_INITRAMFS_MOUNT' enabled.

Signed-off-by: Menglong Dong <dong.menglong@xxxxxxxxxx>
---
 include/linux/init.h |  4 ++++
 init/do_mounts.c     | 16 ++++++++++------
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index 045ad1650ed1..45ab6970851f 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -148,7 +148,11 @@ extern unsigned int reset_devices;
 /* used by init/main.c */
 void setup_arch(char **);
 void prepare_namespace(void);
+#ifndef CONFIG_INITRAMFS_MOUNT
 void __init init_rootfs(void);
+#else
+static inline void __init init_rootfs(void) { }
+#endif
 extern struct file_system_type rootfs_fs_type;
 
 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 5f82db43ac0f..fcdc849a102a 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -700,7 +700,10 @@ void __init finish_mount_rootfs(bool success)
 	init_chdir("/");
 	init_umount(".", 0);
 }
-#endif
+
+#define rootfs_init_fs_context ramfs_init_fs_context
+
+#else
 
 static bool is_tmpfs;
 static int rootfs_init_fs_context(struct fs_context *fc)
@@ -711,13 +714,14 @@ static int rootfs_init_fs_context(struct fs_context *fc)
 	return ramfs_init_fs_context(fc);
 }
 
+void __init init_rootfs(void)
+{
+	is_tmpfs = check_tmpfs_enabled();
+}
+#endif
+
 struct file_system_type rootfs_fs_type = {
 	.name		= "rootfs",
 	.init_fs_context = rootfs_init_fs_context,
 	.kill_sb	= kill_litter_super,
 };
-
-void __init init_rootfs(void)
-{
-	is_tmpfs = check_tmpfs_enabled();
-}
-- 
2.32.0.rc0