do_set_group(): use guards

clean fit; namespace_excl to modify propagation graph

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 a6a7b068770a4364d1d76f6eb7e21449898718e7..13e2f3837a269547a58990230ace94eaecbd8cfb 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3349,47 +3349,44 @@ static inline int tree_contains_unbindable(struct mount *mnt)
 
 static int do_set_group(struct path *from_path, struct path *to_path)
 {
-       struct mount *from, *to;
+       struct mount *from = real_mount(from_path->mnt);
+       struct mount *to = real_mount(to_path->mnt);
        int err;
 
-       from = real_mount(from_path->mnt);
-       to = real_mount(to_path->mnt);
-
-       namespace_lock();
+       guard(namespace_excl)();
 
        err = may_change_propagation(from);
        if (err)
-               goto out;
+               return err;
        err = may_change_propagation(to);
        if (err)
-               goto out;
+               return err;
 
-       err = -EINVAL;
        /* To and From paths should be mount roots */
        if (!path_mounted(from_path))
-               goto out;
+               return -EINVAL;
        if (!path_mounted(to_path))
-               goto out;
+               return -EINVAL;
 
        /* Setting sharing groups is only allowed across same superblock */
        if (from->mnt.mnt_sb != to->mnt.mnt_sb)
-               goto out;
+               return -EINVAL;
 
        /* From mount root should be wider than To mount root */
        if (!is_subdir(to->mnt.mnt_root, from->mnt.mnt_root))
-               goto out;
+               return -EINVAL;
 
        /* From mount should not have locked children in place of To's root */
        if (__has_locked_children(from, to->mnt.mnt_root))
-               goto out;
+               return -EINVAL;
 
        /* Setting sharing groups is only allowed on private mounts */
        if (IS_MNT_SHARED(to) || IS_MNT_SLAVE(to))
-               goto out;
+               return -EINVAL;
 
        /* From should not be private */
        if (!IS_MNT_SHARED(from) && !IS_MNT_SLAVE(from))
-               goto out;
+               return -EINVAL;
 
        if (IS_MNT_SLAVE(from)) {
                hlist_add_behind(&to->mnt_slave, &from->mnt_slave);
@@ -3401,11 +3398,7 @@ static int do_set_group(struct path *from_path, struct path *to_path)
                list_add(&to->mnt_share, &from->mnt_share);
                set_mnt_shared(to);
        }
-
-       err = 0;
-out:
-       namespace_unlock();
-       return err;
+       return 0;
 }
 
 /**