do_move_mount(): get rid of 'attached' flag

'attached' serves as a proxy for "source is a subtree of our namespace
and not the entirety of anon namespace"; finish massaging it away.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namespace.c b/fs/namespace.c
index e5f8fde57c9971266567340aaeb88da7ad646c9e..7c7cc14da1ee2d110f8dbe4fcbb185fb26fd6698 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3600,7 +3600,7 @@ static int do_move_mount(struct path *old_path,
        struct mount *parent;
        struct mountpoint *mp;
        int err;
-       bool attached, beneath = flags & MNT_TREE_BENEATH;
+       bool beneath = flags & MNT_TREE_BENEATH;
 
        mp = do_lock_mount(new_path, beneath);
        if (IS_ERR(mp))
@@ -3609,7 +3609,6 @@ static int do_move_mount(struct path *old_path,
        old = real_mount(old_path->mnt);
        p = real_mount(new_path->mnt);
        parent = old->mnt_parent;
-       attached = mnt_has_parent(old);
        ns = old->mnt_ns;
 
        err = -EINVAL;
@@ -3622,6 +3621,9 @@ static int do_move_mount(struct path *old_path,
                /* ... and the target should be in our namespace */
                if (!check_mnt(p))
                        goto out;
+               /* parent of the source should not be shared */
+               if (IS_MNT_SHARED(parent))
+                       goto out;
        } else {
                /*
                 * otherwise the source must be the root of some anon namespace.
@@ -3649,11 +3651,6 @@ static int do_move_mount(struct path *old_path,
        if (d_is_dir(new_path->dentry) !=
            d_is_dir(old_path->dentry))
                goto out;
-       /*
-        * Don't move a mount residing in a shared parent.
-        */
-       if (attached && IS_MNT_SHARED(parent))
-               goto out;
 
        if (beneath) {
                err = can_move_mount_beneath(old_path, new_path, mp);
@@ -3686,7 +3683,7 @@ static int do_move_mount(struct path *old_path,
 out:
        unlock_mount(mp);
        if (!err) {
-               if (attached) {
+               if (!is_anon_ns(ns)) {
                        mntput_no_expire(parent);
                } else {
                        /* Make sure we notice when we leak mounts. */