genhd: send async notification on media change

Send an uevent to user space to indicate that a media change event has
occurred.
Signed-off-by: NKristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

block/genhd.c

@@ -696,6 +696,27 @@ struct seq_operations diskstats_op = {
 	.show	= diskstats_show
 };
 
+static void media_change_notify_thread(struct work_struct *work)
+{
+	struct gendisk *gd = container_of(work, struct gendisk, async_notify);
+	char event[] = "MEDIA_CHANGE=1";
+	char *envp[] = { event, NULL };
+
+	/*
+	 * set enviroment vars to indicate which event this is for
+	 * so that user space will know to go check the media status.
+	 */
+	kobject_uevent_env(&gd->kobj, KOBJ_CHANGE, envp);
+	put_device(gd->driverfs_dev);
+}
+
+void genhd_media_change_notify(struct gendisk *disk)
+{
+	get_device(disk->driverfs_dev);
+	schedule_work(&disk->async_notify);
+}
+EXPORT_SYMBOL_GPL(genhd_media_change_notify);
+
 struct gendisk *alloc_disk(int minors)
 {
 	return alloc_disk_node(minors, -1);
@@ -725,6 +746,8 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
 		kobj_set_kset_s(disk,block_subsys);
 		kobject_init(&disk->kobj);
 		rand_initialize_disk(disk);
+		INIT_WORK(&disk->async_notify,
+			media_change_notify_thread);
 	}
 	return disk;
 }

include/linux/genhd.h

@@ -66,6 +66,7 @@ struct partition {
 #include <linux/smp.h>
 #include <linux/string.h>
 #include <linux/fs.h>
+#include <linux/workqueue.h>
 
 struct partition {
 	unsigned char boot_ind;		/* 0x80 - active */
@@ -139,6 +140,7 @@ struct gendisk {
 #else
 	struct disk_stats dkstats;
 #endif
+	struct work_struct async_notify;
 };
 
 /* Structure for sysfs attributes on block devices */
@@ -420,7 +422,7 @@ extern struct gendisk *alloc_disk_node(int minors, int node_id);
 extern struct gendisk *alloc_disk(int minors);
 extern struct kobject *get_disk(struct gendisk *disk);
 extern void put_disk(struct gendisk *disk);
-
+extern void genhd_media_change_notify(struct gendisk *disk);
 extern void blk_register_region(dev_t dev, unsigned long range,
 			struct module *module,
 			struct kobject *(*probe)(dev_t, int *, void *),