[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>

fs/coda/dir.c

@@ -146,6 +146,9 @@ int coda_permission(struct inode *inode, int mask)
 	if (!mask)
 		return 0; 
 
+	if ((mask & MAY_EXEC) && !execute_ok(inode))
+		return -EACCES;
+
 	lock_kernel();
 
 	if (coda_cache_check(inode, mask))