smack: fix cache of access labels

Before this commit, removing the access property of
a file, aka, the extended attribute security.SMACK64
was not effictive until the cache had been cleaned.

This patch fixes that problem.
Signed-off-by: José Bollo <jobol@nonadev.net>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>

security/smack/smack_lsm.c

@@ -1442,9 +1442,13 @@ static int smack_inode_removexattr(struct dentry *dentry, const char *name)
 	 * Don't do anything special for these.
 	 *	XATTR_NAME_SMACKIPIN
 	 *	XATTR_NAME_SMACKIPOUT
-	 *	XATTR_NAME_SMACKEXEC
 	 */
-	if (strcmp(name, XATTR_NAME_SMACK) == 0)
+	if (strcmp(name, XATTR_NAME_SMACK) == 0) {
+		struct super_block *sbp = d_backing_inode(dentry)->i_sb;
+		struct superblock_smack *sbsp = sbp->s_security;
+
+		isp->smk_inode = sbsp->smk_default;
+	} else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0)
 		isp->smk_task = NULL;
 	else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0)
 		isp->smk_mmap = NULL;