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virtio_blk: Dont waste major numbers

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Rusty,

currently virtio_blk uses one major number per device. While this works
quite well on most systems it is wasteful and will exhaust major numbers
on larger installations.

This patch allocates a major number on init and will use 16 minor numbers
for each disk. That will allow ~64k virtio_blk disks.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Christian Borntraeger 2008-01-31 15:53:53 +01:00 committed by Rusty Russell
parent 135da0b037
commit 4f3bf19c6e
1 changed files with 16 additions and 12 deletions
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28
drivers/block/virtio_blk.c
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@ -7,8 +7,11 @@
#include <linux/scatterlist.h>
#define VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS)
#define PART_BITS 4
static unsigned char virtblk_index = 'a';
static int major, minor;
struct virtio_blk
{
spinlock_t lock;
@ -171,10 +174,13 @@ static struct block_device_operations virtblk_fops = {
static int virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
int err, major;
int err;
u64 cap;
u32 v;
if (minor >= 1 << MINORBITS)
return -ENOSPC;
vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
if (!vblk) {
err = -ENOMEM;
@ -198,17 +204,11 @@ static int virtblk_probe(struct virtio_device *vdev)
goto out_free_vq;
}
major = register_blkdev(0, "virtblk");
if (major < 0) {
err = major;
goto out_mempool;
}
/* FIXME: How many partitions? How long is a piece of string? */
vblk->disk = alloc_disk(1 << 4);
vblk->disk = alloc_disk(1 << PART_BITS);
if (!vblk->disk) {
err = -ENOMEM;
goto out_unregister_blkdev;
goto out_mempool;
}
vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
@ -219,10 +219,12 @@ static int virtblk_probe(struct virtio_device *vdev)
sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
vblk->disk->major = major;
vblk->disk->first_minor = 0;
vblk->disk->first_minor = minor;
vblk->disk->private_data = vblk;
vblk->disk->fops = &virtblk_fops;
minor += 1 << PART_BITS;
/* If barriers are supported, tell block layer that queue is ordered */
if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER))
blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
@ -258,8 +260,6 @@ static int virtblk_probe(struct virtio_device *vdev)
out_put_disk:
put_disk(vblk->disk);
out_unregister_blkdev:
unregister_blkdev(major, "virtblk");
out_mempool:
mempool_destroy(vblk->pool);
out_free_vq:
@ -304,11 +304,15 @@ static struct virtio_driver virtio_blk = {
static int __init init(void)
{
major = register_blkdev(0, "virtblk");
if (major < 0)
return major;
return register_virtio_driver(&virtio_blk);
}
static void __exit fini(void)
{
unregister_blkdev(major, "virtblk");
unregister_virtio_driver(&virtio_blk);
}
module_init(init);