[PATCH v2] nbd: Issue a uevent when disconnecting

[Wouter Verhelst <w@uter.be>]

There already is a uevent by default when closing a device upon connect
of the device. However, the same isn't true on disconnect.

This makes it hard for userspace to keep track of whether a device is
connected, since we are notified when the connection is created, but not
when it is removed again.

Explicitly issue a "change" uevent to remedy.

[v2: incorporate feedback from udev maintainer and make sure that we
issue a uevent upon connect as well as disconnect, rather than connect
only]

Signed-off-by: Wouter Verhelst <w@uter.be>
---
 drivers/block/nbd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index e4c5cc1..04d9563 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -417,6 +417,8 @@ static int nbd_thread_recv(struct nbd_device *nbd)
 	spin_unlock_irqrestore(&nbd->tasks_lock, flags);
 
 	ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
+	kobject_uevent(&disk_to_dev(nbd->disk)->kobj, KOBJ_CHANGE);
+
 	if (ret) {
 		dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
 
@@ -438,6 +440,7 @@ static int nbd_thread_recv(struct nbd_device *nbd)
 	}
 
 	device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
+	kobject_uevent(&disk_to_dev(nbd->disk)->kobj, KOBJ_CHANGE);
 
 	spin_lock_irqsave(&nbd->tasks_lock, flags);
 	nbd->task_recv = NULL;
-- 
2.7.0