From 7a7c924cf03da2a76ea4dc0aac1a788cf95a9c29 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 1 Feb 2011 21:43:48 +0100 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 Signed-off-by: Rusty Russell --- drivers/block/virtio_blk.c | 88 ++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 78 insertions(+), 10 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 6ecf89c..33a48a8 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -6,10 +6,12 @@ #include #include #include +#include #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)); @@ -508,27 +556,47 @@ 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("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); -- 2.7.4