[dm-devel] [PATCH 2/3] scsi_dh: add scsi_dh_attached_handler_name
Mike Snitzer
snitzer at redhat.com
Tue May 8 03:19:06 UTC 2012
The following dm-mpath patch may be considered PATCH 1/3 of this series:
http://www.redhat.com/archives/dm-devel/2012-May/msg00006.html
----8<---------
Introduce scsi_dh_attached_handler_name() to retrieve the name of the
scsi_dh that is attached to the scsi_device associated with the provided
request queue. Returns NULL if a scsi_dh is not attached.
Also, fix scsi_dh_{attach,detach} function header comments to document
@q rather than @sdev.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/scsi/device_handler/scsi_dh.c | 31 +++++++++++++++++++++++++++++--
include/scsi/scsi_dh.h | 5 +++++
2 files changed, 34 insertions(+), 2 deletions(-)
Index: linux-2.6/drivers/scsi/device_handler/scsi_dh.c
===================================================================
--- linux-2.6.orig/drivers/scsi/device_handler/scsi_dh.c
+++ linux-2.6/drivers/scsi/device_handler/scsi_dh.c
@@ -468,7 +468,8 @@ EXPORT_SYMBOL_GPL(scsi_dh_handler_exist)
/*
* scsi_dh_attach - Attach device handler
- * @sdev - sdev the handler should be attached to
+ * @q - Request queue that is associated with the scsi_device
+ * the handler should be attached to
* @name - name of the handler to attach
*/
int scsi_dh_attach(struct request_queue *q, const char *name)
@@ -498,7 +499,8 @@ EXPORT_SYMBOL_GPL(scsi_dh_attach);
/*
* scsi_dh_detach - Detach device handler
- * @sdev - sdev the handler should be detached from
+ * @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
@@ -527,6 +529,31 @@ void scsi_dh_detach(struct request_queue
}
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
+ *
+ * Returns name of attached scsi_dh, NULL if no handler is attached.
+ */
+const char *scsi_dh_attached_handler_name(struct request_queue *q)
+{
+ unsigned long flags;
+ struct scsi_device *sdev;
+
+ 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 || !sdev->scsi_dh_data)
+ return NULL;
+
+ return sdev->scsi_dh_data->scsi_dh->name;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);
+
static struct notifier_block scsi_dh_nb = {
.notifier_call = scsi_dh_notifier
};
Index: linux-2.6/include/scsi/scsi_dh.h
===================================================================
--- linux-2.6.orig/include/scsi/scsi_dh.h
+++ linux-2.6/include/scsi/scsi_dh.h
@@ -60,6 +60,7 @@ extern int scsi_dh_activate(struct reque
extern int scsi_dh_handler_exist(const char *);
extern int scsi_dh_attach(struct request_queue *, const char *);
extern void scsi_dh_detach(struct request_queue *);
+extern const char *scsi_dh_attached_handler_name(struct request_queue *q);
extern int scsi_dh_set_params(struct request_queue *, const char *);
#else
static inline int scsi_dh_activate(struct request_queue *req,
@@ -80,6 +81,10 @@ static inline void scsi_dh_detach(struct
{
return;
}
+static inline const char *scsi_dh_attached_handler_name(struct request_queue *q)
+{
+ return NULL;
+}
static inline int scsi_dh_set_params(struct request_queue *req, const char *params)
{
return -SCSI_DH_NOSYS;
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