[PATCH] add sysfs attr to re-emit device hotplug event

A "coldplug + udevstart" can be simple like this:
  for i in /sys/block/*/*/uevent; do echo 1 > $i; done
  for i in /sys/class/*/*/uevent; do echo 1 > $i; done
  for i in /sys/bus/*/devices/*/uevent; do echo 1 > $i; done

Signed-off-by: Kay Sievers <kay.sievers@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/block/genhd.c b/drivers/block/genhd.c
index d42840cc0d1d..486ce1fdeb8c 100644
--- a/drivers/block/genhd.c
+++ b/drivers/block/genhd.c
@@ -337,10 +337,30 @@ static ssize_t disk_attr_show(struct kobject *kobj, struct attribute *attr,
         return ret;
 }
 
+static ssize_t disk_attr_store(struct kobject * kobj, struct attribute * attr,
+                               const char *page, size_t count)
+{
+        struct gendisk *disk = to_disk(kobj);
+        struct disk_attribute *disk_attr =
+                container_of(attr,struct disk_attribute,attr);
+        ssize_t ret = 0;
+
+        if (disk_attr->store)
+                ret = disk_attr->store(disk, page, count);
+        return ret;
+}
+
 static struct sysfs_ops disk_sysfs_ops = {
         .show   = &disk_attr_show,
+        .store  = &disk_attr_store,
 };
 
+static ssize_t disk_uevent_store(struct gendisk * disk,
+                                 const char *buf, size_t count)
+{
+        kobject_hotplug(&disk->kobj, KOBJ_ADD);
+        return count;
+}
 static ssize_t disk_dev_read(struct gendisk * disk, char *page)
 {
         dev_t base = MKDEV(disk->major, disk->first_minor); 
@@ -382,6 +402,10 @@ static ssize_t disk_stats_read(struct gendisk * disk, char *page)
                 jiffies_to_msecs(disk_stat_read(disk, io_ticks)),
                 jiffies_to_msecs(disk_stat_read(disk, time_in_queue)));
 }
+static struct disk_attribute disk_attr_uevent = {
+        .attr = {.name = "uevent", .mode = S_IWUSR },
+        .store  = disk_uevent_store
+};
 static struct disk_attribute disk_attr_dev = {
         .attr = {.name = "dev", .mode = S_IRUGO },
         .show   = disk_dev_read
@@ -404,6 +428,7 @@ static struct disk_attribute disk_attr_stat = {
 };
 
 static struct attribute * default_attrs[] = {
+        &disk_attr_uevent.attr,
         &disk_attr_dev.attr,
         &disk_attr_range.attr,
         &disk_attr_removable.attr,