logfs doesn't need ->permission() at all

... and never did, what with its ->permission() being what we do by default
when ->permission is NULL...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/logfs/dir.c

@@ -555,13 +555,6 @@ static int logfs_symlink(struct inode *dir, struct dentry *dentry,
 	return __logfs_create(dir, dentry, inode, target, destlen);
 }
 
-static int logfs_permission(struct inode *inode, int mask, unsigned int flags)
-{
-	if (flags & IPERM_FLAG_RCU)
-		return -ECHILD;
-	return generic_permission(inode, mask, flags, NULL);
-}
-
 static int logfs_link(struct dentry *old_dentry, struct inode *dir,
 		struct dentry *dentry)
 {
@@ -820,7 +813,6 @@ const struct inode_operations logfs_dir_iops = {
 	.mknod		= logfs_mknod,
 	.rename		= logfs_rename,
 	.rmdir		= logfs_rmdir,
-	.permission	= logfs_permission,
 	.symlink	= logfs_symlink,
 	.unlink		= logfs_unlink,
 };