From: Hannes Reinecke <hare@suse.de>
Subject: Send uevents for write_protect changes
References: bnc#440959

Whenever a block device changes it's read-only attribute
we should notify the userspace about it.

Signed-off-by: Hannes Reinecke <hare@suse.de>

---
 block/genhd.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- a/block/genhd.c
+++ b/block/genhd.c
@@ -813,6 +813,16 @@ 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(&gd->dev.kobj, KOBJ_CHANGE, envp);
+}
+
 void set_device_ro(struct block_device *bdev, int flag)
 {
 	if (bdev->bd_contains != bdev)
@@ -826,6 +836,9 @@ EXPORT_SYMBOL(set_device_ro);
 void set_disk_ro(struct gendisk *disk, int flag)
 {
 	int i;
+	if (disk->policy != flag)
+		set_disk_ro_uevent(disk, flag);
+
 	disk->policy = flag;
 	for (i = 0; i < disk->minors - 1; i++)
 		if (disk->part[i]) disk->part[i]->policy = flag;