[PATCH] fix disk->id abuse

[Robert Millan <rmh@aybabtu.com>]

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disk->id is supposed to be filled with a per-disk value so that the disk
cache manager can identify individual disks.

For single-disk drivers, a constant is enough.  But it seems someone started
using pointers to strings for them, and then we all (including me) copied.

Then I see disk/scsi.c doing the same thing, but this time it's a real problem
since it's not a single-disk driver.

So this patch means to solve both issues;  makes single-disk drivers use a
constant directly (since a pointer to string is meaningless and confusing),
and disk/scsi.c use LUNs which (I believe) will work as unique identifiers.

Marco, could you confirm this is ok (specially the latter)?

-- 
Robert Millan

  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
  how) you may access your data; but nobody's threatening your freedom: we
  still allow you to remove your data and not access it at all."

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2008-08-30  Robert Millan  <rmh@aybabtu.com>

	* disk/host.c (grub_host_open): Initialize `disk->id' using
	a constant rather than a pointer to string.
	* disk/memdisk.c (grub_memdisk_open): Likewise.
	* fs/i386/pc/pxe.c (grub_pxe_open): Likewise.
	* disk/scsi.c (grub_scsi_open): Initialize `disk->id' using the
	`lun' variable rather than a pointer to string.

Index: disk/scsi.c
===================================================================
--- disk/scsi.c	(revision 1831)
+++ disk/scsi.c	(working copy)
@@ -248,7 +248,7 @@ grub_scsi_open (const char *name, grub_d
     {
       if (! p->open (name, scsi))
 	{
-	  disk->id = (unsigned long) "scsi"; /* XXX */
+	  disk->id = lun;	/* FIXME: are LUNs unique identifiers? */
 	  disk->data = scsi;
 	  scsi->dev = p;
 	  scsi->lun = lun;
Index: disk/host.c
===================================================================
--- disk/host.c	(revision 1831)
+++ disk/host.c	(working copy)
@@ -41,7 +41,7 @@ grub_host_open (const char *name, grub_d
       return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a host disk");
 
   disk->total_sectors = 0;
-  disk->id = (unsigned long) "host";
+  disk->id = 'host';
   
   disk->has_partitions = 0;
   disk->data = 0;
Index: disk/memdisk.c
===================================================================
--- disk/memdisk.c	(revision 1831)
+++ disk/memdisk.c	(working copy)
@@ -41,7 +41,7 @@ grub_memdisk_open (const char *name, gru
       return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a memdisk");
 
   disk->total_sectors = memdisk_size / GRUB_DISK_SECTOR_SIZE;
-  disk->id = (unsigned long) "mdsk";
+  disk->id = 'mdsk';
   disk->has_partitions = 0;
 
   return GRUB_ERR_NONE;
Index: fs/i386/pc/pxe.c
===================================================================
--- fs/i386/pc/pxe.c	(revision 1831)
+++ fs/i386/pc/pxe.c	(working copy)
@@ -63,7 +63,7 @@ grub_pxe_open (const char *name, grub_di
       return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a pxe disk");
 
   disk->total_sectors = 0;
-  disk->id = (unsigned long) "pxe";
+  disk->id = 'pxe';
 
   disk->has_partitions = 0;
   disk->data = 0;