selinux: drop super_block backpointer from superblock_security_struct

It appears to have been needed for selinux_complete_init() in the past,
but today it's useless.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -600,7 +600,7 @@ static int selinux_set_mnt_opts(struct super_block *sb,
 {
 	const struct cred *cred = current_cred();
 	struct superblock_security_struct *sbsec = sb->s_security;
-	struct dentry *root = sbsec->sb->s_root;
+	struct dentry *root = sb->s_root;
 	struct selinux_mnt_opts *opts = mnt_opts;
 	struct inode_security_struct *root_isec;
 	u32 fscontext_sid = 0, context_sid = 0, rootcontext_sid = 0;
@@ -1080,7 +1080,7 @@ static int selinux_sb_show_options(struct seq_file *m, struct super_block *sb)
 			return rc;
 	}
 	if (sbsec->flags & ROOTCONTEXT_MNT) {
-		struct dentry *root = sbsec->sb->s_root;
+		struct dentry *root = sb->s_root;
 		struct inode_security_struct *isec = backing_inode_security(root);
 		seq_putc(m, ',');
 		seq_puts(m, ROOTCONTEXT_STR);
@@ -2568,7 +2568,6 @@ static int selinux_sb_alloc_security(struct super_block *sb)
 	mutex_init(&sbsec->lock);
 	INIT_LIST_HEAD(&sbsec->isec_head);
 	spin_lock_init(&sbsec->isec_lock);
-	sbsec->sb = sb;
 	sbsec->sid = SECINITSID_UNLABELED;
 	sbsec->def_sid = SECINITSID_FILE;
 	sbsec->mntpoint_sid = SECINITSID_UNLABELED;

security/selinux/include/objsec.h

@@ -61,7 +61,6 @@ struct file_security_struct {
 };
 
 struct superblock_security_struct {
-	struct super_block *sb;		/* back pointer to sb object */
 	u32 sid;			/* SID of file system superblock */
 	u32 def_sid;			/* default SID for labeling */
 	u32 mntpoint_sid;		/* SECURITY_FS_USE_MNTPOINT context for files */