virtio_blk: implement naming for vda-vdz,vdaa-vdzz,vdaaa-vdzzz

Am Freitag, 1. Februar 2008 schrieb Christian Borntraeger:
> Right. I will fix that with an additional patch.

This patch goes on top of the minor number patch. Please let me know if
you want a merged patch:

Currently virtio_blk creates the disk name combinging "vd"  with 'a'++.
This will give strange names after vdz. I have implemented names up to
vdzzz - inspired by the sd.c code. That should be sufficient for now.

There is one driver in the kernel (driver/s390/block/dasd_genhd.c) that
implements names from dasda-dasdzzzz allowing even more disks. Maybe
a janitor can come up with a common implementation usable for all kind
of block device drivers.

I have tested this patch with 100 disks - seems to work.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 22 insertions, 7 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 559c322c4ffa..3b1a68d6eddb 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -9,8 +9,7 @@
 #define VIRTIO_MAX_SG   (3+MAX_PHYS_SEGMENTS)
 #define PART_BITS 4
 
-static unsigned char virtblk_index = 'a';
-static int major, minor;
+static int major, index;
 
 struct virtio_blk
 {
@@ -171,6 +170,11 @@ static struct block_device_operations virtblk_fops = {
         .getgeo = virtblk_getgeo,
 };
 
+static int index_to_minor(int index)
+{
+        return index << PART_BITS;
+}
+
 static int virtblk_probe(struct virtio_device *vdev)
 {
         struct virtio_blk *vblk;
@@ -178,7 +182,7 @@ static int virtblk_probe(struct virtio_device *vdev)
         u64 cap;
         u32 v;
 
-        if (minor >= 1 << MINORBITS)
+        if (index_to_minor(index) >= 1 << MINORBITS)
                 return -ENOSPC;
 
         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
@@ -217,13 +221,24 @@ static int virtblk_probe(struct virtio_device *vdev)
                 goto out_put_disk;
         }
 
-        sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
+        if (index < 26) {
+                sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26);
+        } else if (index < (26 + 1) * 26) {
+                sprintf(vblk->disk->disk_name, "vd%c%c",
+                        'a' + index / 26 - 1, 'a' + index % 26);
+        } else {
+                const unsigned int m1 = (index / 26 - 1) / 26 - 1;
+                const unsigned int m2 = (index / 26 - 1) % 26;
+                const unsigned int m3 =  index % 26;
+                sprintf(vblk->disk->disk_name, "vd%c%c%c",
+                        'a' + m1, 'a' + m2, 'a' + m3);
+        }
+
         vblk->disk->major = major;
-        vblk->disk->first_minor = minor;
+        vblk->disk->first_minor = index_to_minor(index);
         vblk->disk->private_data = vblk;
         vblk->disk->fops = &virtblk_fops;
-
-        minor += 1 << PART_BITS;
+        index++;
 
         /* If barriers are supported, tell block layer that queue is ordered */
         if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER))