[Xen-changelog] [linux-2.6.18-xen] Blkfront greater-than-16-vbd fixes

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1215596709 -3600
# Node ID 29228a5f9fea2cf5b30645c4bb23852b1fb3802f
# Parent  f1d726b984a35e13ff69402b30b57611328c85bb
Blkfront greater-than-16-vbd fixes

While reading through the code again, I realized that if you did
something like:

block-attach xvdb
block-attach xvdq
block-attach xvdc

The extended blkfront code would allocate the wrong device for xvdc,
since we had changed mi->type along the way.  To fix this, have a
separate "major_info" entry for the extended block devices, even
though it isn't technically a different major number.  With these
fixes in place, the above sequence works for me.

Signed-off-by: Chris Lalancette <clalance@xxxxxxxxxx>
---
 drivers/xen/blkfront/vbd.c |   52 ++++++++++++++++++++++++++++++---------------
 1 files changed, 35 insertions(+), 17 deletions(-)

diff -r f1d726b984a3 -r 29228a5f9fea drivers/xen/blkfront/vbd.c
--- a/drivers/xen/blkfront/vbd.c        Wed Jul 09 10:44:08 2008 +0100
+++ b/drivers/xen/blkfront/vbd.c        Wed Jul 09 10:45:09 2008 +0100
@@ -56,7 +56,7 @@
 
 #define NUM_IDE_MAJORS 10
 #define NUM_SCSI_MAJORS 17
-#define NUM_VBD_MAJORS 1
+#define NUM_VBD_MAJORS 2
 
 static struct xlbd_type_info xlbd_ide_type = {
        .partn_shift = 6,
@@ -114,12 +114,14 @@ xlbd_alloc_major_info(int major, int min
 xlbd_alloc_major_info(int major, int minor, int index)
 {
        struct xlbd_major_info *ptr;
+       int do_register;
 
        ptr = kzalloc(sizeof(struct xlbd_major_info), GFP_KERNEL);
        if (ptr == NULL)
                return NULL;
 
        ptr->major = major;
+       do_register = 1;
 
        switch (index) {
        case XLBD_MAJOR_IDE_RANGE:
@@ -131,23 +133,36 @@ xlbd_alloc_major_info(int major, int min
                ptr->index = index - XLBD_MAJOR_SCSI_START;
                break;
        case XLBD_MAJOR_VBD_RANGE:
-               ptr->type = &xlbd_vbd_type;
-               ptr->index = index - XLBD_MAJOR_VBD_START;
-               break;
-       }
-
-       if (register_blkdev(ptr->major, ptr->type->devname)) {
-               kfree(ptr);
-               return NULL;
-       }
-
-       printk("xen-vbd: registered block device major %i\n", ptr->major);
+               ptr->index = 0;
+               if ((index - XLBD_MAJOR_VBD_START) == 0)
+                       ptr->type = &xlbd_vbd_type;
+               else
+                       ptr->type = &xlbd_vbd_type_ext;
+
+               /* 
+                * if someone already registered block major 202,
+                * don't try to register it again
+                */
+               if (major_info[XLBD_MAJOR_VBD_START] != NULL)
+                       do_register = 0;
+               break;
+       }
+
+       if (do_register) {
+               if (register_blkdev(ptr->major, ptr->type->devname)) {
+                       kfree(ptr);
+                       return NULL;
+               }
+
+               printk("xen-vbd: registered block device major %i\n", 
ptr->major);
+       }
+
        major_info[index] = ptr;
        return ptr;
 }
 
 static struct xlbd_major_info *
-xlbd_get_major_info(int major, int minor)
+xlbd_get_major_info(int major, int minor, int vdevice)
 {
        struct xlbd_major_info *mi;
        int index;
@@ -171,7 +186,12 @@ xlbd_get_major_info(int major, int minor
                 index = 18 + major - SCSI_DISK8_MAJOR;
                 break;
         case SCSI_CDROM_MAJOR: index = 26; break;
-        default: index = 27; break;
+        default:
+               if (!VDEV_IS_EXTENDED(vdevice))
+                       index = 27;
+               else
+                       index = 28;
+               break;
        }
 
        mi = ((major_info[index] != NULL) ? major_info[index] :
@@ -241,11 +261,9 @@ xlvbd_alloc_gendisk(int major, int minor
        BUG_ON(info->mi != NULL);
        BUG_ON(info->rq != NULL);
 
-       mi = xlbd_get_major_info(major, minor);
+       mi = xlbd_get_major_info(major, minor, vdevice);
        if (mi == NULL)
                goto out;
-       if (VDEV_IS_EXTENDED(vdevice))
-               mi->type = &xlbd_vbd_type_ext;
        info->mi = mi;
 
        if ((minor & ((1 << mi->type->partn_shift) - 1)) == 0)

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