@@ -650,6 +650,50 @@ void __init prepare_namespace(void)
}
static bool is_tmpfs;
+#ifdef CONFIG_INITRAMFS_MOUNT
+
+/*
+ * Give systems running from the initramfs and making use of pivot_root a
+ * proper mount so it can be umounted during pivot_root.
+ */
+int __init prepare_mount_rootfs(void)
+{
+ char *rootfs = "ramfs";
+
+ if (is_tmpfs)
+ rootfs = "tmpfs";
+
+ init_mkdir("/root", 0700);
+ return do_mount_root(rootfs, rootfs,
+ root_mountflags & ~MS_RDONLY,
+ root_mount_data);
+}
+
+/*
+ * Revert to previous mount by chdir to '/' and unmounting the second
+ * mount.
+ */
+void __init revert_mount_rootfs(void)
+{
+ init_chdir("/");
+ init_umount(".", MNT_DETACH);
+}
+
+/*
+ * Change root to the new rootfs that mounted in prepare_mount_rootfs()
+ * if cpio is unpacked successfully and 'ramdisk_execute_command' exist.
+ */
+void __init finish_mount_rootfs(void)
+{
+ init_mount(".", "/", NULL, MS_MOVE, NULL);
+ if (likely(ramdisk_exec_exist()))
+ init_chroot(".");
+ else
+ revert_mount_rootfs();
+}
+
+#define rootfs_init_fs_context ramfs_init_fs_context
+#else
static int rootfs_init_fs_context(struct fs_context *fc)
{
if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
@@ -657,6 +701,7 @@ static int rootfs_init_fs_context(struct fs_context *fc)
return ramfs_init_fs_context(fc);
}
+#endif
struct file_system_type rootfs_fs_type = {
.name = "rootfs",
@@ -10,9 +10,24 @@
#include <linux/root_dev.h>
#include <linux/init_syscalls.h>
+extern int root_mountflags;
+
void mount_block_root(char *name, int flags);
void mount_root(void);
-extern int root_mountflags;
+
+#ifdef CONFIG_INITRAMFS_MOUNT
+
+int prepare_mount_rootfs(void);
+void finish_mount_rootfs(void);
+void revert_mount_rootfs(void);
+
+#else
+
+static inline int prepare_mount_rootfs(void) { return 0; }
+static inline void finish_mount_rootfs(void) { }
+static inline void revert_mount_rootfs(void) { }
+
+#endif
static inline __init int create_dev(char *name, dev_t dev)
{
@@ -17,6 +17,8 @@
#include <linux/init_syscalls.h>
#include <linux/umh.h>
+#include "do_mounts.h"
+
static ssize_t __init xwrite(struct file *file, const char *p, size_t count,
loff_t *pos)
{
@@ -671,7 +673,12 @@ static void __init populate_initrd_image(char *err)
static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
{
/* Load the built in initramfs */
- char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
+ char *err;
+
+ if (prepare_mount_rootfs())
+ panic("Failed to mount rootfs\n");
+
+ err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
if (err)
panic_show_mem("%s", err); /* Failed to decompress INTERNAL initramfs */
@@ -685,11 +692,14 @@ static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
if (err) {
+ revert_mount_rootfs();
#ifdef CONFIG_BLK_DEV_RAM
populate_initrd_image(err);
#else
printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
#endif
+ } else {
+ finish_mount_rootfs();
}
done:
@@ -52,6 +52,16 @@ config INITRAMFS_ROOT_GID
If you are not sure, leave it set to "0".
+config INITRAMFS_MOUNT
+ bool "Create second mount to make pivot_root() supported"
+ default y
+ help
+ Before unpacking cpio, create a second mount and make it become
+ the root filesystem. Therefore, initramfs will be supported by
+ pivot_root().
+
+ If container platforms is used with initramfs, say Y.
+
config RD_GZIP
bool "Support initial ramdisk/ramfs compressed using gzip"
default y