Re: 2.4.17:Increase number of anonymous filesystems beyond 256?

[Pete Zaitcev <zaitcev@redhat.com>]

> From: Rainer Krienke <krienke@uni-koblenz.de>
> Date: Thu, 24 Jan 2002 09:58:48 +0100

> diff -Naur linux-2.4.17.orig/fs/super.c linux-2.4.17/fs/super.c
> --- linux-2.4.17.orig/fs/super.c        Fri Dec 21 18:42:03 2001
> +++ linux-2.4.17/fs/super.c     Thu Jan 24 08:23:05 2002
> @@ -489,13 +489,13 @@
>   * filesystems which don't use real block-devices.  -- jrs
>   */
> 
> -static unsigned long unnamed_dev_in_use[256/(8*sizeof(unsigned long))];
> +static unsigned long unnamed_dev_in_use[4096/(8*sizeof(unsigned long))];
> 
>  kdev_t get_unnamed_dev(void)
>  {
>         int i;
> 
> -       for (i = 1; i < 256; i++) {
> +       for (i = 1; i < 4096; i++) {
>                 if (!test_and_set_bit(i,unnamed_dev_in_use))
>                         return MKDEV(UNNAMED_MAJOR, i);
>         }
>[...]
> mount a very high number only limited by the bitmap unnamed_dev_in_use of NFS 
> directories. The problems are:

Rainer, you missed the point. Nobody cares about small things
such as "cannot start nfsd" while your 4096 mounts patch
simply CORRUPTS YOUR DATA TO HELL.

If you need more than 1200 mounts, you have to add more majors
to my patch. There is a number of them between 115 and 198.
I suspect scalability problems may become evident
with this approach, but it will work.

Trond asked if I requested numbers from HPA, and the answer is no,
because I wanted the patch in circulation for a while before it
is worth bothering. Also, I heard that LANA is closed anyways.

-- Pete