Re: [RESEND][PATCH] Send uevents for disk write_protect changes

Jens Axboe
2009-07-28T07:12:59Z

On Tue, Jul 21 2009, Nikanth Karthikesan wrote:
> Hi
>
> This patch is needed for the dm-multipath, so that the daemon can capture the
> event and reload the dm table when the read-only setting of the disk changes.
> Can this be merged?

Looks fine to me, merged for 2.6.32.

>
> Thanks
> Nikanth
>
> From: Hannes Reinecke <hare@suse.de>
> Subject: Send uevents for write_protect changes
>
> Whenever a block device changes it's read-only attribute
> notify the userspace about it.
>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
>
> ---
>
> diff --git a/block/genhd.c b/block/genhd.c
> index f4c64c2..b89328e 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -1215,6 +1215,16 @@ void put_disk(struct gendisk *disk)
>
> EXPORT_SYMBOL(put_disk);
>
> +static void set_disk_ro_uevent(struct gendisk *gd, int ro)
> +{
> + char event[] = "DISK_RO=1";
> + char *envp[] = { event, NULL };
> +
> + if (!ro)
> + event[8] = '0';
> + kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
> +}
> +
> void set_device_ro(struct block_device *bdev, int flag)
> {
> bdev->bd_part->policy = flag;
> @@ -1227,8 +1237,12 @@ void set_disk_ro(struct gendisk *disk, int flag)
> struct disk_part_iter piter;
> struct hd_struct *part;
>
> - disk_part_iter_init(&piter, disk,
> - DISK_PITER_INCL_EMPTY | DISK_PITER_INCL_PART0);
> + if (disk->part0.policy != flag) {
> + set_disk_ro_uevent(disk, flag);
> + disk->part0.policy = flag;
> + }
> +
> + disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
> while ((part = disk_part_iter_next(&piter)))
> part->policy = flag;
> disk_part_iter_exit(&piter);
>
>

--
Jens Axboe