unfuck sysfs_mount()

new_sb is left uninitialized in case of early failures in kernfs_mount_ns(),
and while IS_ERR(root) is true in all such cases, using IS_ERR(root) || !new_sb
is not a solution - IS_ERR(root) is true in some cases when new_sb is true.

Make sure new_sb is initialized (and matches the reality) in all cases and
fix the condition for dropping kobj reference - we want it done precisely
in those situations where the reference has not been transferred into a new
super_block instance.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index b428d317ae92a74d40ddf20ee3e64a830a04433b..92682fcc41f6c976f1d38cf3111eab509a9028d8 100644 (file)
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -25,7 +25,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 {
        struct dentry *root;
        void *ns;
-       bool new_sb;
+       bool new_sb = false;
 
        if (!(flags & SB_KERNMOUNT)) {
                if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
@@ -35,9 +35,9 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
        ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
        root = kernfs_mount_ns(fs_type, flags, sysfs_root,
                                SYSFS_MAGIC, &new_sb, ns);
-       if (IS_ERR(root) || !new_sb)
+       if (!new_sb)
                kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
-       else if (new_sb)
+       else if (!IS_ERR(root))
                root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE;
 
        return root;