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initmpfs: use initramfs if rootfstype= or root= specified

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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>
This commit is contained in:
Rob Landley 2013-09-11 14:26:13 -07:00 • committed by Linus Torvalds
parent 16203a7a94
commit 6e19eded36
2 changed files with 15 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

4
Documentation/filesystems/ramfs-rootfs-initramfs.txt
View file

@ -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 Most systems just mount another filesystem over rootfs and ignore it. The
amount of space an empty instance of ramfs takes up is tiny. 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
line.
What is initramfs? What is initramfs?
------------------ ------------------

15
init/do_mounts.c
View file

@ -591,16 +591,20 @@ out:
sys_chroot("."); sys_chroot(".");
} }
static bool is_tmpfs;
static struct dentry *rootfs_mount(struct file_system_type *fs_type, static struct dentry *rootfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data) int flags, const char *dev_name, void *data)
{ {
static unsigned long once; static unsigned long once;
void *fill = ramfs_fill_super;
if (test_and_set_bit(0, &once)) if (test_and_set_bit(0, &once))
return ERR_PTR(-ENODEV); return ERR_PTR(-ENODEV);
return mount_nodev(fs_type, flags, data, if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
IS_ENABLED(CONFIG_TMPFS) ? shmem_fill_super : ramfs_fill_super); fill = shmem_fill_super;
return mount_nodev(fs_type, flags, data, fill);
} }
static struct file_system_type rootfs_fs_type = { static struct file_system_type rootfs_fs_type = {
@ -616,10 +620,13 @@ int __init init_rootfs(void)
if (err) if (err)
return err; return err;
if (IS_ENABLED(CONFIG_TMPFS)) if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
(!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
err = shmem_init(); err = shmem_init();
else is_tmpfs = true;
} else {
err = init_ramfs_fs(); err = init_ramfs_fs();
}
if (err) if (err)
unregister_filesystem(&rootfs_fs_type); unregister_filesystem(&rootfs_fs_type);