Smack: fix smack_new_inode bogosities

In January of 2012 Al Viro pointed out three bits of code that
he titled "new_inode_smack bogosities". This patch repairs these
errors.

1. smack_sb_kern_mount() included a NULL check that is impossible.
   The check and NULL case are removed.
2. smack_kb_kern_mount() included pointless locking. The locking is
   removed. Since this is the only place that lock was used the lock
   is removed from the superblock_smack structure.
3. smk_fill_super() incorrectly and unnecessarily set the Smack label
   for the smackfs root inode. The assignment has been removed.

Targeted for git://gitorious.org/smack-next/kernel.gitSigned-off-by: NCasey Schaufler <casey@schaufler-ca.com>

security/smack/smack.h

@@ -43,7 +43,6 @@ struct superblock_smack {
 	char		*smk_hat;
 	char		*smk_default;
 	int		smk_initialized;
-	spinlock_t	smk_sblock;	/* for initialization */
 };
 
 struct socket_smack {

security/smack/smack_lsm.c

@@ -251,7 +251,6 @@ static int smack_sb_alloc_security(struct super_block *sb)
 	sbsp->smk_floor = smack_known_floor.smk_known;
 	sbsp->smk_hat = smack_known_hat.smk_known;
 	sbsp->smk_initialized = 0;
-	spin_lock_init(&sbsp->smk_sblock);
 
 	sb->s_security = sbsp;
 
@@ -332,13 +331,10 @@ static int smack_sb_kern_mount(struct super_block *sb, int flags, void *data)
 	char *commap;
 	char *nsp;
 
-	spin_lock(&sp->smk_sblock);
-	if (sp->smk_initialized != 0) {
-		spin_unlock(&sp->smk_sblock);
+	if (sp->smk_initialized != 0)
 		return 0;
-	}
+
 	sp->smk_initialized = 1;
-	spin_unlock(&sp->smk_sblock);
 
 	for (op = data; op != NULL; op = commap) {
 		commap = strchr(op, ',');

security/smack/smackfs.c

@@ -2051,7 +2051,6 @@ static int smk_fill_super(struct super_block *sb, void *data, int silent)
 	}
 
 	root_inode = sb->s_root->d_inode;
-	root_inode->i_security = new_inode_smack(smack_known_floor.smk_known);
 
 	return 0;
 }