RE: [PATCH] Trying to improve /proc/filesystems

RE: [PATCH] Trying to improve /proc/filesystems

[Frederick, Fabian]

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 : viro@parcelfarce.linux.theplanet.co.uk
[mailto:viro@parcelfarce.linux.theplanet.co.uk]
Envoyé : lundi 30 juin 2003 09:53
À : Frederick, Fabian
Cc : 'linux-kernel@vger.kernel.org'
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.

Re: [PATCH] Trying to improve /proc/filesystems

[viro]

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.

[PATCH] Trying to improve /proc/filesystems

[Frederick, Fabian]

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);

Re: [PATCH] Trying to improve /proc/filesystems

[viro]

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.