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SubjectRe: [PATCH] virtio-blk: emit udev event when device is resized
On 02/22/2013 03:02 AM, Milos Vyletel wrote:
> When virtio-blk device is resized from host (using block_resize from QEMU) emit
> KOBJ_CHANGE uevent to notify guest about such change. This allows user to have
> custom udev rules which would take whatever action if such event occurs. As a
> proof of concept I've created simple udev rule that automatically resize
> filesystem on virtio-blk device.
>
> ACTION=="change", KERNEL=="vd*", \
> ENV{RESIZE}=="1", \
> ENV{ID_FS_TYPE}=="ext[3-4]", \
> RUN+="/sbin/resize2fs /dev/%k"
> ACTION=="change", KERNEL=="vd*", \
> ENV{RESIZE}=="1", \
> ENV{ID_FS_TYPE}=="LVM2_member", \
> RUN+="/sbin/pvresize /dev/%k"
>
> Signed-off-by: Milos Vyletel <milos.vyletel@sde.cz>
> ---
> drivers/block/virtio_blk.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 8ad21a2..5990382 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -539,6 +539,8 @@ static void virtblk_config_changed_work(struct work_struct *work)
> struct virtio_device *vdev = vblk->vdev;
> struct request_queue *q = vblk->disk->queue;
> char cap_str_2[10], cap_str_10[10];
> + char event[] = "RESIZE=1";
> + char *envp[] = { event, NULL };

event is not used again. Why not just

char *envp[] = { "RESIZE=1", NULL };


> u64 capacity, size;
>
> mutex_lock(&vblk->config_lock);
> @@ -568,6 +570,7 @@ static void virtblk_config_changed_work(struct work_struct *work)
>
> set_capacity(vblk->disk, capacity);
> revalidate_disk(vblk->disk);
> + kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
> done:
> mutex_unlock(&vblk->config_lock);
> }
>

I tried the following with your automatically resize udev rules.

(qemu) block_resize vd0 500
Check the fs size in guest, it is 500Mb

(qemu) block_resize vd0 1200
Check the fs size in guest, it is still 500Mb

Can you try resizing multiple times? Does it work?

--
Asias

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