Point init_task's fs_struct (root and pwd) at a private nullfs instance instead of the mutable rootfs. All kthreads now start isolated in nullfs and must use scoped_with_init_fs() for any path resolution. PID 1 is moved from nullfs into the initramfs by init_userspace_fs(). Usermodehelper threads use userspace_init_fs via the umh flag in copy_fs(). All subsystems that need init's filesystem state for path resolution already use scoped_with_init_fs() from earlier commits in this series. This isolates kthreads from userspace filesystem state and makes it hard to perform filesystem operations from kthread context. Signed-off-by: Christian Brauner --- fs/namespace.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 668131aa5de1..2a530109eb36 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -6188,12 +6188,14 @@ static void __init init_mount_tree(void) init_mnt_ns.nr_mounts++; } + nullfs_mnt = kern_mount(&nullfs_fs_type); + if (IS_ERR(nullfs_mnt)) + panic("VFS: Failed to create private nullfs instance"); + root.mnt = nullfs_mnt; + root.dentry = nullfs_mnt->mnt_root; + init_task.nsproxy->mnt_ns = &init_mnt_ns; get_mnt_ns(&init_mnt_ns); - - /* The root and pwd always point to the mutable rootfs. */ - root.mnt = mnt; - root.dentry = mnt->mnt_root; set_fs_pwd(current->fs, &root); set_fs_root(current->fs, &root); -- 2.47.3