dm-mpath, scsi_dh: don't let dm detach device handlers
While allowing dm-mpath to attach device handlers is a functionality we need
for backwards compatibility reason there is no reason to reference count
them and detach them if dm-mpath stops using the device for some reason.
If the device handler works for the given device it can just stay attached,
and we can take the retain_hw_handler codepath.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Hannes Reinecke <hare@Suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index 1efebc9..869b5bd 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -100,14 +100,6 @@
{
struct scsi_dh_data *d;
- if (sdev->scsi_dh_data) {
- if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
- return -EBUSY;
-
- kref_get(&sdev->scsi_dh_data->kref);
- return 0;
- }
-
if (!try_module_get(scsi_dh->module))
return -EINVAL;
@@ -120,7 +112,6 @@
}
d->scsi_dh = scsi_dh;
- kref_init(&d->kref);
d->sdev = sdev;
spin_lock_irq(sdev->request_queue->queue_lock);
@@ -129,12 +120,14 @@
return 0;
}
-static void __detach_handler (struct kref *kref)
+/*
+ * scsi_dh_handler_detach - Detach a device handler from a device
+ * @sdev - SCSI device the device handler should be detached from
+ */
+static void scsi_dh_handler_detach(struct scsi_device *sdev)
{
- struct scsi_dh_data *scsi_dh_data =
- container_of(kref, struct scsi_dh_data, kref);
+ struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
struct scsi_device_handler *scsi_dh = scsi_dh_data->scsi_dh;
- struct scsi_device *sdev = scsi_dh_data->sdev;
scsi_dh->detach(sdev);
@@ -147,30 +140,6 @@
}
/*
- * scsi_dh_handler_detach - Detach a device handler from a device
- * @sdev - SCSI device the device handler should be detached from
- * @scsi_dh - Device handler to be detached
- *
- * Detach from a device handler. If a device handler is specified,
- * only detach if the currently attached handler matches @scsi_dh.
- */
-static void scsi_dh_handler_detach(struct scsi_device *sdev,
- struct scsi_device_handler *scsi_dh)
-{
- if (!sdev->scsi_dh_data)
- return;
-
- if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
- return;
-
- if (!scsi_dh)
- scsi_dh = sdev->scsi_dh_data->scsi_dh;
-
- if (scsi_dh)
- kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
-}
-
-/*
* Functions for sysfs attribute 'dh_state'
*/
static ssize_t
@@ -198,7 +167,7 @@
/*
* Detach from a device handler
*/
- scsi_dh_handler_detach(sdev, scsi_dh);
+ scsi_dh_handler_detach(sdev);
err = 0;
} else if (!strncmp(buf, "activate", 8)) {
/*
@@ -290,7 +259,8 @@
err = scsi_dh_handler_attach(sdev, devinfo);
} else if (action == BUS_NOTIFY_DEL_DEVICE) {
device_remove_file(dev, &scsi_dh_state_attr);
- scsi_dh_handler_detach(sdev, NULL);
+ if (sdev->scsi_dh_data)
+ scsi_dh_handler_detach(sdev);
}
return err;
}
@@ -335,7 +305,8 @@
sdev = to_scsi_device(dev);
- scsi_dh_handler_detach(sdev, scsi_dh);
+ if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh == scsi_dh)
+ scsi_dh_handler_detach(sdev);
put_device(dev);
@@ -517,47 +488,24 @@
err = -ENODEV;
spin_unlock_irqrestore(q->queue_lock, flags);
- if (!err) {
- err = scsi_dh_handler_attach(sdev, scsi_dh);
- put_device(&sdev->sdev_gendev);
+ if (err)
+ return err;
+
+ if (sdev->scsi_dh_data) {
+ if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
+ err = -EBUSY;
+ goto out_put_device;
}
+
+ err = scsi_dh_handler_attach(sdev, scsi_dh);
+
+out_put_device:
+ put_device(&sdev->sdev_gendev);
return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_attach);
/*
- * scsi_dh_detach - Detach device handler
- * @q - Request queue that is associated with the scsi_device
- * the handler should be detached from
- *
- * This function will detach the device handler only
- * if the sdev is not part of the internal list, ie
- * if it has been attached manually.
- */
-void scsi_dh_detach(struct request_queue *q)
-{
- unsigned long flags;
- struct scsi_device *sdev;
- struct scsi_device_handler *scsi_dh = NULL;
-
- spin_lock_irqsave(q->queue_lock, flags);
- sdev = q->queuedata;
- if (!sdev || !get_device(&sdev->sdev_gendev))
- sdev = NULL;
- spin_unlock_irqrestore(q->queue_lock, flags);
-
- if (!sdev)
- return;
-
- if (sdev->scsi_dh_data) {
- scsi_dh = sdev->scsi_dh_data->scsi_dh;
- scsi_dh_handler_detach(sdev, scsi_dh);
- }
- put_device(&sdev->sdev_gendev);
-}
-EXPORT_SYMBOL_GPL(scsi_dh_detach);
-
-/*
* scsi_dh_attached_handler_name - Get attached device handler's name
* @q - Request queue that is associated with the scsi_device
* that may have a device handler attached
