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Message-ID: <20110114160137.GA18721@lst.de>
Date: Fri, 14 Jan 2011 17:01:37 +0100
From: Christoph Hellwig <hch@....de>
To: Rusty Russell <rusty@...tcorp.com.au>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] 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: Christoph Hellwig <hch@....de>
Index: xfs/drivers/block/virtio_blk.c
===================================================================
--- xfs.orig/drivers/block/virtio_blk.c 2011-01-13 18:17:23.730254665 +0100
+++ xfs/drivers/block/virtio_blk.c 2011-01-14 16:57:50.572032906 +0100
@@ -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
{
@@ -42,6 +44,11 @@ struct virtblk_req
u8 status;
};
+struct virtblk_config_change {
+ struct virtio_device *vdev;
+ struct work_struct work;
+};
+
static void blk_done(struct virtqueue *vq)
{
struct virtio_blk *vblk = vq->vdev->priv;
@@ -291,6 +298,57 @@ static ssize_t virtblk_serial_show(struc
}
DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
+static void virtblk_config_changed_work(struct work_struct *work)
+{
+ struct virtblk_config_change *cfg =
+ container_of(work, struct virtblk_config_change, work);
+ struct virtio_device *vdev = cfg->vdev;
+ struct virtio_blk *vblk = vdev->priv;
+ 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 virtblk_config_change *cfg;
+
+ cfg = kmalloc(sizeof(*cfg), GFP_ATOMIC);
+ if (!cfg) {
+ dev_info(&vdev->dev, "skipping config change\n");
+ return;
+ }
+
+ cfg->vdev = vdev;
+ INIT_WORK(&cfg->work, virtblk_config_changed_work);
+ queue_work(virtblk_wq, &cfg->work);
+}
+
+
static int __devinit virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
@@ -508,27 +566,47 @@ static unsigned int features[] = {
* Use __refdata to avoid this warning.
*/
static struct virtio_driver __refdata virtio_blk = {
- .feature_table = features,
- .feature_table_size = ARRAY_SIZE(features),
- .driver.name = KBUILD_MODNAME,
- .driver.owner = THIS_MODULE,
- .id_table = id_table,
- .probe = virtblk_probe,
- .remove = __devexit_p(virtblk_remove),
+ .feature_table = features,
+ .feature_table_size = ARRAY_SIZE(features),
+ .driver.name = KBUILD_MODNAME,
+ .driver.owner = THIS_MODULE,
+ .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("md_misc", 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);
--
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