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@xxxxxxxxxx> --- 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; -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
