diff options
authorRob Landley <rob@landley.net>2013-09-11 14:26:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:59:38 -0700
commit6e19eded3684dc184181093af3bff2ff440f5b53 (patch)
parent16203a7a9422315bc929461503e3a046459ea5ff (diff)
initmpfs: use initramfs if rootfstype= or root= specified
Command line option rootfstype=ramfs to obtain old initramfs behavior, and use ramfs instead of tmpfs for stub when root= defined (for cosmetic reasons). [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Rob Landley <rob@landley.net> Cc: Jeff Layton <jlayton@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Stephen Warren <swarren@nvidia.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jim Cromie <jim.cromie@gmail.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2 files changed, 15 insertions, 4 deletions
diff --git a/Documentation/filesystems/ramfs-rootfs-initramfs.txt b/Documentation/filesystems/ramfs-rootfs-initramfs.txt
index 59b4a0962e0f..b176928e6963 100644
--- a/Documentation/filesystems/ramfs-rootfs-initramfs.txt
+++ b/Documentation/filesystems/ramfs-rootfs-initramfs.txt
@@ -79,6 +79,10 @@ to just make sure certain lists can't become empty.
Most systems just mount another filesystem over rootfs and ignore it. The
amount of space an empty instance of ramfs takes up is tiny.
+If CONFIG_TMPFS is enabled, rootfs will use tmpfs instead of ramfs by
+default. To force ramfs, add "rootfstype=ramfs" to the kernel command
What is initramfs?
diff --git a/init/do_mounts.c b/init/do_mounts.c
index e27908b949d4..a51cddc2ff8c 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -591,16 +591,20 @@ out:
+static bool is_tmpfs;
static struct dentry *rootfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
static unsigned long once;
+ void *fill = ramfs_fill_super;
if (test_and_set_bit(0, &once))
return ERR_PTR(-ENODEV);
- return mount_nodev(fs_type, flags, data,
- IS_ENABLED(CONFIG_TMPFS) ? shmem_fill_super : ramfs_fill_super);
+ if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
+ fill = shmem_fill_super;
+ return mount_nodev(fs_type, flags, data, fill);
static struct file_system_type rootfs_fs_type = {
@@ -616,10 +620,13 @@ int __init init_rootfs(void)
if (err)
return err;
+ if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
+ (!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
err = shmem_init();
- else
+ is_tmpfs = true;
+ } else {
err = init_ramfs_fs();
+ }
if (err)

Privacy Policy