From: Alexander Lobakin <alobakin@xxxxx> Date: Fri, 02 Jul 2021 23:44:35 +0000 > Inspired by the situation from [0]. > > The roots of choosing tmpfs/ramfs backend for rootfs go far back > in history, and it's unclear at all why it was decided to select > full-blown tmpfs when "root=" is not specified and feature-poor > ramfs otherwise. > There are several cases when "root=" is not needed at all to work, > and it doesn't break anything or make any [negative] sense. On the > other hand, such separation is rather counter-intuitive and makes > debugging more difficult. > Simply always use tmpfs when it's available -- just like devtmpfs > does [for over a decade]. > > [0] https://lore.kernel.org/kernel-hardening/20210701234807.50453-1-alobakin@xxxxx/ > > Signed-off-by: Alexander Lobakin <alobakin@xxxxx> Ping? > --- > fs/namespace.c | 2 -- > include/linux/init.h | 1 - > init/do_mounts.c | 26 +++++++------------------- > 3 files changed, 7 insertions(+), 22 deletions(-) > > diff --git a/fs/namespace.c b/fs/namespace.c > index ab4174a3c802..310ab44fdbe7 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -17,7 +17,6 @@ > #include <linux/security.h> > #include <linux/cred.h> > #include <linux/idr.h> > -#include <linux/init.h> /* init_rootfs */ > #include <linux/fs_struct.h> /* get_fs_root et.al. */ > #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ > #include <linux/file.h> > @@ -4248,7 +4247,6 @@ void __init mnt_init(void) > if (!fs_kobj) > printk(KERN_WARNING "%s: kobj create error\n", __func__); > shmem_init(); > - init_rootfs(); > init_mount_tree(); > } > > diff --git a/include/linux/init.h b/include/linux/init.h > index d82b4b2e1d25..10839922a1d3 100644 > --- a/include/linux/init.h > +++ b/include/linux/init.h > @@ -148,7 +148,6 @@ extern unsigned int reset_devices; > /* used by init/main.c */ > void setup_arch(char **); > void prepare_namespace(void); > -void __init init_rootfs(void); > extern struct file_system_type rootfs_fs_type; > > #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) > diff --git a/init/do_mounts.c b/init/do_mounts.c > index 74aede860de7..c00b05015a66 100644 > --- a/init/do_mounts.c > +++ b/init/do_mounts.c > @@ -611,24 +611,12 @@ void __init prepare_namespace(void) > init_chroot("."); > } > > -static bool is_tmpfs; > -static int rootfs_init_fs_context(struct fs_context *fc) > -{ > - if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs) > - return shmem_init_fs_context(fc); > - > - return ramfs_init_fs_context(fc); > -} > - > struct file_system_type rootfs_fs_type = { > - .name = "rootfs", > - .init_fs_context = rootfs_init_fs_context, > - .kill_sb = kill_litter_super, > + .name = "rootfs", > +#ifdef CONFIG_TMPFS > + .init_fs_context = shmem_init_fs_context, > +#else > + .init_fs_context = ramfs_init_fs_context, > +#endif > + .kill_sb = kill_litter_super, > }; > - > -void __init init_rootfs(void) > -{ > - if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] && > - (!root_fs_names || strstr(root_fs_names, "tmpfs"))) > - is_tmpfs = true; > -} > -- > 2.32.0 Thanks, Al
