md: move the early init autodetect code to drivers/md/

Just like the NFS and CIFS root code this better lives with the
driver it is tightly integrated with.

Signed-off-by: Christoph Hellwig <[e-mail]>
Acked-by: Song Liu <[e-mail]>
Acked-by: Linus Torvalds <[e-mail]>

drivers/md/Makefile

···
 obj-$(CONFIG_MD_CLUSTER)	+= md-cluster.o
 obj-$(CONFIG_BCACHE)		+= bcache/
 obj-$(CONFIG_BLK_DEV_MD)	+= md-mod.o
+ifeq ($(CONFIG_BLK_DEV_MD),y)
+obj-y				+= md-autodetect.o
+endif
 obj-$(CONFIG_BLK_DEV_DM)	+= dm-mod.o
 obj-$(CONFIG_BLK_DEV_DM_BUILTIN) += dm-builtin.o
 obj-$(CONFIG_DM_UNSTRIPED)	+= dm-unstripe.o

include/linux/raid/detect.h

···
 /* SPDX-License-Identifier: GPL-2.0 */
 
 void md_autodetect_dev(dev_t dev);
+
+#ifdef CONFIG_BLK_DEV_MD
+void md_run_setup(void);
+#else
+static inline void md_run_setup(void)
+{
+}
+#endif

init/Makefile

···
 mounts-y			:= do_mounts.o
 mounts-$(CONFIG_BLK_DEV_RAM)	+= do_mounts_rd.o
 mounts-$(CONFIG_BLK_DEV_INITRD)	+= do_mounts_initrd.o
-mounts-$(CONFIG_BLK_DEV_MD)	+= do_mounts_md.o
 
 # dependencies on generated files need to be listed explicitly
 $(obj)/version.o: include/generated/compile.h

init/do_mounts.c

···
 #include <linux/nfs_fs.h>
 #include <linux/nfs_fs_sb.h>
 #include <linux/nfs_mount.h>
+#include <linux/raid/detect.h>
 #include <uapi/linux/mount.h>
 
 #include "do_mounts.h"

init/do_mounts.h

···
 static inline bool initrd_load(void) { return false; }
 
 #endif
-
-#ifdef CONFIG_BLK_DEV_MD
-
-void md_run_setup(void);
-
-#else
-
-static inline void md_run_setup(void) {}
-
-#endif

init/do_mounts_md.c drivers/md/md-autodetect.c

···
 // SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/init.h>
+#include <linux/syscalls.h>
+#include <linux/mount.h>
+#include <linux/major.h>
 #include <linux/delay.h>
+#include <linux/raid/detect.h>
 #include <linux/raid/md_u.h>
 #include <linux/raid/md_p.h>
-
-#include "do_mounts.h"
 
 /*
  * When md (and any require personalities) are compiled into the kernel
···
 	md_setup_args[ent].minor = minor;
 
 	return 1;
+}
+
+static inline int create_dev(char *name, dev_t dev)
+{
+	ksys_unlink(name);
+	return ksys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));
 }
 
 static void __init md_setup_drive(void)