Re: [NFS] RE: [autofs] multiple servers per automount

[Mike Waychison]

Ingo Oeser wrote:
> On Wednesday 15 October 2003 01:12, Mike Waychison wrote:
>
> > The problem still remains in 2.6 that we limit the count to 256.  I've
> > attached a quick patch that I've compiled and tested.  I don't know if
> > there is a better way to handle dynamic assignment of minors (haven't
> > kept up to date in that realm), but if there is, then we should probably
> >  use it instead.
>
>
>
> In your patch you allocate inside the spinlock.
>
> I would suggest to do sth. like the following:

Better yet..  we could move it into an __init section that will panic if 
the allocation fails (this should be the desired behaviour..).  This way 
we don't even have to grab the lock either.

Mike Waychison
===== fs/namespace.c 1.49 vs edited =====
--- 1.49/fs/namespace.c	Thu Jul 17 22:30:49 2003
+++ edited/fs/namespace.c	Wed Oct 15 15:59:11 2003
@@ -23,6 +23,7 @@
 #include <linux/mount.h>
 #include <asm/uaccess.h>
 
+extern void __init super_init(void);
 extern int __init init_rootfs(void);
 extern int __init sysfs_init(void);
 
@@ -1154,6 +1155,7 @@
 		d++;
 		i--;
 	} while (i);
+	super_init();
 	sysfs_init();
 	init_rootfs();
 	init_mount_tree();
===== fs/super.c 1.108 vs edited =====
--- 1.108/fs/super.c	Wed Oct  1 15:36:45 2003
+++ edited/fs/super.c	Wed Oct 15 15:59:50 2003
@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
+#include <linux/init.h>
 #include <linux/acct.h>
 #include <linux/blkdev.h>
 #include <linux/quotaops.h>
@@ -527,15 +528,22 @@
  * Unnamed block devices are dummy devices used by virtual
  * filesystems which don't use real block-devices.  -- jrs
  */
-
-enum {Max_anon = 256};
-static unsigned long unnamed_dev_in_use[Max_anon/(8*sizeof(unsigned long))];
+enum {Max_anon = PAGE_SIZE * 8};
+static void *unnamed_dev_in_use;
 static spinlock_t unnamed_dev_lock = SPIN_LOCK_UNLOCKED;/* protects the above */
 
+void __init super_init(void)
+{
+	unnamed_dev_in_use = (void *)get_zeroed_page(GFP_KERNEL);
+	if (!unnamed_dev_in_use)
+		panic("Could not allocate anonymous device map");
+}
+
 int set_anon_super(struct super_block *s, void *data)
 {
 	int dev;
 	spin_lock(&unnamed_dev_lock);
+
 	dev = find_first_zero_bit(unnamed_dev_in_use, Max_anon);
 	if (dev == Max_anon) {
 		spin_unlock(&unnamed_dev_lock);