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	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>
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					 2 changed files with 15 additions and 4 deletions
				
			
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			@ -79,6 +79,10 @@ to just make sure certain lists can't become empty.
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Most systems just mount another filesystem over rootfs and ignore it.  The
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amount of space an empty instance of ramfs takes up is tiny.
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If CONFIG_TMPFS is enabled, rootfs will use tmpfs instead of ramfs by
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default.  To force ramfs, add "rootfstype=ramfs" to the kernel command
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line.
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What is initramfs?
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------------------
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			@ -591,16 +591,20 @@ void __init prepare_namespace(void)
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	sys_chroot(".");
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}
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static bool is_tmpfs;
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static struct dentry *rootfs_mount(struct file_system_type *fs_type,
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	int flags, const char *dev_name, void *data)
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{
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	static unsigned long once;
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	void *fill = ramfs_fill_super;
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	if (test_and_set_bit(0, &once))
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		return ERR_PTR(-ENODEV);
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	return mount_nodev(fs_type, flags, data,
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		IS_ENABLED(CONFIG_TMPFS) ? shmem_fill_super : ramfs_fill_super);
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	if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
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		fill = shmem_fill_super;
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	return mount_nodev(fs_type, flags, data, fill);
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}
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static struct file_system_type rootfs_fs_type = {
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			@ -616,10 +620,13 @@ int __init init_rootfs(void)
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	if (err)
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		return err;
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	if (IS_ENABLED(CONFIG_TMPFS))
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	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
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		(!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
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		err = shmem_init();
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	else
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		is_tmpfs = true;
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	} else {
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		err = init_ramfs_fs();
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	}
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	if (err)
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		unregister_filesystem(&rootfs_fs_type);
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