partially fix up the lookup_one_noperm mess

Try to fix the mess created by sysfs braindamage.

 - refactor code internal to fs/namei.c a little to avoid too much
   duplication:
	o __lookup_hash_kern is renamed back to __lookup_hash
	o the old __lookup_hash goes away, permission checks moves to
	  the two callers
	o useless inline qualifiers on above functions go away
 - lookup_one_len_kern loses it's last argument and is renamed to
   lookup_one_noperm to make it's useage a little more clear
 - added kerneldoc comments to describe lookup_one_len aswell as
   lookup_one_noperm and make it very clear that no one should use
   the latter ever.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/sysfs/dir.c

@@ -112,8 +112,7 @@ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
 		/* look it up */
 		parent = dentry;
 		mutex_lock(&parent->d_inode->i_mutex);
-		dentry = lookup_one_len_kern(cur->s_name, parent,
-					     strlen(cur->s_name));
+		dentry = lookup_one_noperm(cur->s_name, parent);
 		mutex_unlock(&parent->d_inode->i_mutex);
 		dput(parent);