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Commit 7a7c924c authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Rusty Russell
Browse files

virtio_blk: allow re-reading config space at runtime 



Wire up the virtio_driver config_changed method to get notified about
config changes raised by the host.  For now we just re-read the device
size to support online resizing of devices, but once we add more
attributes that might be changeable they could be added as well.

Note that the config_changed method is called from irq context, so
we'll have to use the workqueue infrastructure to provide us a proper
user context for our changes.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 990c91f0

drivers/block/virtio_blk.c

+78 −10
Original line number Diff line number Diff line
@@ -6,10 +6,12 @@ 
#include <linux/virtio.h>

#include <linux/virtio_blk.h>

#include <linux/scatterlist.h>

#include <linux/string_helpers.h>



#define PART_BITS 4



static int major, index;

struct workqueue_struct *virtblk_wq;



struct virtio_blk

{
@@ -26,6 +28,9 @@ struct virtio_blk 


	mempool_t *pool;



	/* Process context for config space updates */

	struct work_struct config_work;



	/* What host tells us, plus 2 for header & tailer. */

	unsigned int sg_elems;
@@ -291,6 +296,46 @@ static ssize_t virtblk_serial_show(struct device *dev, 
}

DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);



static void virtblk_config_changed_work(struct work_struct *work)

{

	struct virtio_blk *vblk =

		container_of(work, struct virtio_blk, config_work);

	struct virtio_device *vdev = vblk->vdev;

	struct request_queue *q = vblk->disk->queue;

	char cap_str_2[10], cap_str_10[10];

	u64 capacity, size;



	/* Host must always specify the capacity. */

	vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),

			  &capacity, sizeof(capacity));



	/* If capacity is too big, truncate with warning. */

	if ((sector_t)capacity != capacity) {

		dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",

			 (unsigned long long)capacity);

		capacity = (sector_t)-1;

	}



	size = capacity * queue_logical_block_size(q);

	string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));

	string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));



	dev_notice(&vdev->dev,

		  "new size: %llu %d-byte logical blocks (%s/%s)\n",

		  (unsigned long long)capacity,

		  queue_logical_block_size(q),

		  cap_str_10, cap_str_2);



	set_capacity(vblk->disk, capacity);

}



static void virtblk_config_changed(struct virtio_device *vdev)

{

	struct virtio_blk *vblk = vdev->priv;



	queue_work(virtblk_wq, &vblk->config_work);

}



static int __devinit virtblk_probe(struct virtio_device *vdev)

{

	struct virtio_blk *vblk;
@@ -327,6 +372,7 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) 
	vblk->vdev = vdev;

	vblk->sg_elems = sg_elems;

	sg_init_table(vblk->sg, vblk->sg_elems);

	INIT_WORK(&vblk->config_work, virtblk_config_changed_work);



	/* We expect one virtqueue, for output. */

	vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests");
@@ -477,6 +523,8 @@ static void __devexit virtblk_remove(struct virtio_device *vdev) 
{

	struct virtio_blk *vblk = vdev->priv;



	flush_work(&vblk->config_work);



	/* Nothing should be pending. */

	BUG_ON(!list_empty(&vblk->reqs));
@@ -515,20 +563,40 @@ static struct virtio_driver __refdata virtio_blk = { 
	.id_table		= id_table,

	.probe			= virtblk_probe,

	.remove			= __devexit_p(virtblk_remove),

	.config_changed		= virtblk_config_changed,

};



static int __init init(void)

{

	int error;



	virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);

	if (!virtblk_wq)

		return -ENOMEM;



	major = register_blkdev(0, "virtblk");

	if (major < 0)

		return major;

	return register_virtio_driver(&virtio_blk);

	if (major < 0) {

		error = major;

		goto out_destroy_workqueue;

	}



	error = register_virtio_driver(&virtio_blk);

	if (error)

		goto out_unregister_blkdev;

	return 0;



out_unregister_blkdev:

	unregister_blkdev(major, "virtblk");

out_destroy_workqueue:

	destroy_workqueue(virtblk_wq);

	return error;

}



static void __exit fini(void)

{

	unregister_blkdev(major, "virtblk");

	unregister_virtio_driver(&virtio_blk);

	destroy_workqueue(virtblk_wq);

}

module_init(init);

module_exit(fini);