[PATCH] move executable checking into ->permission()

For execute permission on a regular files we need to check if file has
any execute bits at all, regardless of capabilites.

This check is normally performed by generic_permission() but was also
added to the case when the filesystem defines its own ->permission()
method.  In the latter case the filesystem should be responsible for
performing this check.

Move the check from inode_permission() inside filesystems which are
not calling generic_permission().

Create a helper function execute_ok() that returns true if the inode
is a directory or if any execute bits are present in i_mode.

Also fix up the following code:

 - coda control file is never executable
 - sysctl files are never executable
 - hfs_permission seems broken on MAY_EXEC, remove
 - hfsplus_permission is eqivalent to generic_permission(), remove

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/coda/pioctl.c b/fs/coda/pioctl.c
index c513654..773f2ce 100644
--- a/fs/coda/pioctl.c
+++ b/fs/coda/pioctl.c
@@ -43,7 +43,7 @@
 /* the coda pioctl inode ops */
 static int coda_ioctl_permission(struct inode *inode, int mask)
 {
-        return 0;
+	return (mask & MAY_EXEC) ? -EACCES : 0;
 }
 
 static int coda_pioctl(struct inode * inode, struct file * filp,