devtmpfs: support !CONFIG_TMPFS

Make devtmpfs available on (embedded) configurations without SHMEM/TMPFS,
using ramfs instead.

Saves ~15KB.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 10 insertions, 2 deletions

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index fd52c48ee762..ef38aff737eb 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -18,9 +18,9 @@ config UEVENT_HELPER_PATH
 
 config DEVTMPFS
         bool "Maintain a devtmpfs filesystem to mount at /dev"
-        depends on HOTPLUG && SHMEM && TMPFS
+        depends on HOTPLUG
         help
-          This creates a tmpfs filesystem instance early at bootup.
+          This creates a tmpfs/ramfs filesystem instance early at bootup.
           In this filesystem, the kernel driver core maintains device
           nodes with their default names and permissions for all
           registered devices with an assigned major/minor number.
@@ -33,6 +33,9 @@ config DEVTMPFS
           functional /dev without any further help. It also allows simple
           rescue systems, and reliably handles dynamic major/minor numbers.
 
+          Notice: if CONFIG_TMPFS isn't enabled, the simpler ramfs
+          file system will be used instead.
+
 config DEVTMPFS_MOUNT
         bool "Automount devtmpfs at /dev, after the kernel mounted the rootfs"
         depends on DEVTMPFS
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 057cf11326bf..af0600143d1c 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -20,6 +20,7 @@
 #include <linux/namei.h>
 #include <linux/fs.h>
 #include <linux/shmem_fs.h>
+#include <linux/ramfs.h>
 #include <linux/cred.h>
 #include <linux/sched.h>
 #include <linux/init_task.h>
@@ -45,7 +46,11 @@ __setup("devtmpfs.mount=", mount_param);
 static int dev_get_sb(struct file_system_type *fs_type, int flags,
                       const char *dev_name, void *data, struct vfsmount *mnt)
 {
+#ifdef CONFIG_TMPFS
         return get_sb_single(fs_type, flags, data, shmem_fill_super, mnt);
+#else
+        return get_sb_single(fs_type, flags, data, ramfs_fill_super, mnt);
+#endif
 }
 
 static struct file_system_type dev_fs_type = {