[PATCH 10/24] init: handle ubi/mtd root mounting like all other root types

Christoph Hellwig
2023-05-31T12:57:43Z

Assign a Root_Generic magic value for UBI/MTD root and handle the root
mounting in mount_root like all other root types. Besides making the
code more clear this also means that UBI/MTD root can be used together
with an initrd (not that anyone should care).

Also factor parsing of the root name into a helper now that it can
be easily done and will get more complicated with subsequent patches.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/root_dev.h | 1 +
init/do_mounts.c | 23 ++++++++++++++---------
2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/include/linux/root_dev.h b/include/linux/root_dev.h
index ed3ea8da642972..847c9a06101b76 100644
--- a/include/linux/root_dev.h
+++ b/include/linux/root_dev.h
@@ -9,6 +9,7 @@
enum {
Root_NFS = MKDEV(UNNAMED_MAJOR, 255),
Root_CIFS = MKDEV(UNNAMED_MAJOR, 254),
+ Root_Generic = MKDEV(UNNAMED_MAJOR, 253),
Root_RAM0 = MKDEV(RAMDISK_MAJOR, 0),
};

diff --git a/init/do_mounts.c b/init/do_mounts.c
index 74cc96bffbdd71..be6d14733ba02f 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -591,6 +591,10 @@ void __init mount_root(char *root_device_name)
case Root_CIFS:
mount_cifs_root();
break;
+ case Root_Generic:
+ mount_root_generic(root_device_name, root_device_name,
+ root_mountflags);
+ break;
case 0:
if (root_device_name && root_fs_names &&
mount_nodev_root(root_device_name) == 0)
@@ -602,6 +606,14 @@ void __init mount_root(char *root_device_name)
}
}

+static dev_t __init parse_root_device(char *root_device_name)
+{
+ if (!strncmp(root_device_name, "mtd", 3) ||
+ !strncmp(root_device_name, "ubi", 3))
+ return Root_Generic;
+ return name_to_dev_t(root_device_name);
+}
+
/*
* Prepare the namespace - decide what/where to mount, load ramdisks, etc.
*/
@@ -624,15 +636,8 @@ void __init prepare_namespace(void)

md_run_setup();

- if (saved_root_name[0]) {
- if (!strncmp(saved_root_name, "mtd", 3) ||
- !strncmp(saved_root_name, "ubi", 3)) {
- mount_root_generic(saved_root_name, saved_root_name,
- root_mountflags);
- goto out;
- }
- ROOT_DEV = name_to_dev_t(saved_root_name);
- }
+ if (saved_root_name[0])
+ ROOT_DEV = parse_root_device(saved_root_name);

if (initrd_load(saved_root_name))
goto out;
--
2.39.2