selinux: Don't sleep inside inode_getsecid hook

The inode_getsecid hook is called from contexts in which sleeping is not
allowed, so we cannot revalidate inode security labels from there. Use
the non-validating version of inode_security() instead.
Reported-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -3249,7 +3249,7 @@ static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t
 
 static void selinux_inode_getsecid(struct inode *inode, u32 *secid)
 {
-	struct inode_security_struct *isec = inode_security(inode);
+	struct inode_security_struct *isec = inode_security_novalidate(inode);
 	*secid = isec->sid;
 }