virtio_blk: Dont waste major numbers
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>
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135da0b037
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@ -7,8 +7,11 @@
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#include <linux/scatterlist.h>
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#include <linux/scatterlist.h>
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#define VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS)
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#define VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS)
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#define PART_BITS 4
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static unsigned char virtblk_index = 'a';
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static unsigned char virtblk_index = 'a';
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static int major, minor;
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struct virtio_blk
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struct virtio_blk
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{
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{
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spinlock_t lock;
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spinlock_t lock;
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@ -171,10 +174,13 @@ static struct block_device_operations virtblk_fops = {
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static int virtblk_probe(struct virtio_device *vdev)
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static int virtblk_probe(struct virtio_device *vdev)
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{
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{
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struct virtio_blk *vblk;
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struct virtio_blk *vblk;
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int err, major;
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int err;
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u64 cap;
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u64 cap;
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u32 v;
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u32 v;
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if (minor >= 1 << MINORBITS)
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return -ENOSPC;
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vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
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vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
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if (!vblk) {
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if (!vblk) {
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err = -ENOMEM;
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err = -ENOMEM;
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@ -198,17 +204,11 @@ static int virtblk_probe(struct virtio_device *vdev)
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goto out_free_vq;
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goto out_free_vq;
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}
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}
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major = register_blkdev(0, "virtblk");
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if (major < 0) {
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err = major;
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goto out_mempool;
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}
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/* FIXME: How many partitions? How long is a piece of string? */
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/* FIXME: How many partitions? How long is a piece of string? */
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vblk->disk = alloc_disk(1 << 4);
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vblk->disk = alloc_disk(1 << PART_BITS);
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if (!vblk->disk) {
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if (!vblk->disk) {
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err = -ENOMEM;
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err = -ENOMEM;
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goto out_unregister_blkdev;
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goto out_mempool;
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}
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}
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vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
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vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
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@ -219,10 +219,12 @@ static int virtblk_probe(struct virtio_device *vdev)
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sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
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sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
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vblk->disk->major = major;
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vblk->disk->major = major;
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vblk->disk->first_minor = 0;
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vblk->disk->first_minor = minor;
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vblk->disk->private_data = vblk;
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vblk->disk->private_data = vblk;
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vblk->disk->fops = &virtblk_fops;
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vblk->disk->fops = &virtblk_fops;
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minor += 1 << PART_BITS;
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/* If barriers are supported, tell block layer that queue is ordered */
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/* If barriers are supported, tell block layer that queue is ordered */
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if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER))
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if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER))
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blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
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blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
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@ -258,8 +260,6 @@ static int virtblk_probe(struct virtio_device *vdev)
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out_put_disk:
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out_put_disk:
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put_disk(vblk->disk);
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put_disk(vblk->disk);
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out_unregister_blkdev:
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unregister_blkdev(major, "virtblk");
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out_mempool:
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out_mempool:
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mempool_destroy(vblk->pool);
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mempool_destroy(vblk->pool);
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out_free_vq:
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out_free_vq:
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@ -304,11 +304,15 @@ static struct virtio_driver virtio_blk = {
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static int __init init(void)
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static int __init init(void)
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{
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{
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major = register_blkdev(0, "virtblk");
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if (major < 0)
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return major;
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return register_virtio_driver(&virtio_blk);
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return register_virtio_driver(&virtio_blk);
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}
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}
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static void __exit fini(void)
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static void __exit fini(void)
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{
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{
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unregister_blkdev(major, "virtblk");
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unregister_virtio_driver(&virtio_blk);
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unregister_virtio_driver(&virtio_blk);
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}
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}
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module_init(init);
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module_init(init);
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