2003-06-30 07:22:19

by Frederick, Fabian

[permalink] [raw]
Subject: [PATCH] Trying to improve /proc/filesystems

Hi,
I'm trying to do

nodev xxx 0
yyy 2
(or replace nodev by 0->x)

with the following but Linux complains : VFS : unable to mount
root....Someone could help ?

--- linux-2.5.72/fs/filesystems.c 2003-06-22 20:33:07.000000000 +0200
+++ linux-2.5.72FF/fs/filesystems.c 2003-06-29 18:53:08.000000000 +0200
@@ -194,15 +194,25 @@

int get_filesystem_list(char * buf)
{
- int len = 0;
+ int len = 0, dev = 0;
struct file_system_type * tmp;
+ struct list_head *p;
+ char buf2[6];

read_lock(&file_systems_lock);
tmp = file_systems;
while (tmp && len < PAGE_SIZE - 80) {
- len += sprintf(buf+len, "%s\t%s\n",
+ dev=0;
+ list_for_each(p,&tmp->fs_supers){
+ dev++;
+ }
+ len += sprintf(buf+len, "%s\t%s\t%d\n",
(tmp->fs_flags & FS_REQUIRES_DEV) ? "" : "nodev",
- tmp->name);
+ tmp->name,
+ dev);
tmp = tmp->next;
}
read_unlock(&file_systems_lock);


2003-06-30 07:38:25

by Al Viro

[permalink] [raw]
Subject: Re: [PATCH] Trying to improve /proc/filesystems

On Mon, Jun 30, 2003 at 09:21:00AM +0200, Frederick, Fabian wrote:
> Hi,
> I'm trying to do
>
> nodev xxx 0
> yyy 2
> (or replace nodev by 0->x)
>
> with the following but Linux complains : VFS : unable to mount
> root....Someone could help ?

Yes. Layout of files in procfs should be treated as a part of ABI.
IOW, you make incompatible change - things break.

Folks, file in /proc is not different from a syscall in that respect -
changing layout has the same effect as changes of layout in syscall
arguments.

IOW, don't do that.

2003-06-30 07:57:43

by Frederick, Fabian

[permalink] [raw]
Subject: RE: [PATCH] Trying to improve /proc/filesystems

Alexander,

Why don't we have centralized /proc/filesystems access ? 2 fields
file for fs can't be a standard
Take a look at slab outputs evolution for instance....

Regards,
Fabian

-----Message d'origine-----
De : [email protected]
[mailto:[email protected]]
Envoy? : lundi 30 juin 2003 09:53
? : Frederick, Fabian
Cc : '[email protected]'
Objet : Re: [PATCH] Trying to improve /proc/filesystems


On Mon, Jun 30, 2003 at 09:21:00AM +0200, Frederick, Fabian wrote:
> Hi,
> I'm trying to do
>
> nodev xxx 0
> yyy 2
> (or replace nodev by 0->x)
>
> with the following but Linux complains : VFS : unable to mount
> root....Someone could help ?

Yes. Layout of files in procfs should be treated as a part of ABI.
IOW, you make incompatible change - things break.

Folks, file in /proc is not different from a syscall in that respect -
changing layout has the same effect as changes of layout in syscall
arguments.

IOW, don't do that.

2003-06-30 08:01:47

by Al Viro

[permalink] [raw]
Subject: Re: [PATCH] Trying to improve /proc/filesystems

On Mon, Jun 30, 2003 at 09:55:45AM +0200, Frederick, Fabian wrote:
> Alexander,
>
> Why don't we have centralized /proc/filesystems access ? 2 fields
> file for fs can't be a standard

"Centralized"? In which sense? Any shell script might be using that
animal and expect the format to remain stable.