virtio-blk: emit udev event when device is resized
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>
Tested-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor simplification)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 8ad21a2..922bcb9 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -539,6 +539,7 @@
struct virtio_device *vdev = vblk->vdev;
struct request_queue *q = vblk->disk->queue;
char cap_str_2[10], cap_str_10[10];
+ char *envp[] = { "RESIZE=1", NULL };
u64 capacity, size;
mutex_lock(&vblk->config_lock);
@@ -568,6 +569,7 @@
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);
}