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[SCSI] scsi_dh: add scsi_dh_attached_handler_name

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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@redhat.com>
Tested-by: Babu Moger <babu.moger@netapp.com>
Reviewed-by: Chandra Seetharaman <sekharan@us.ibm.com>
Acked-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Mike Snitzer 2012-06-26 14:32:03 -04:00 committed by James Bottomley
parent 6aca4112f6
commit 7e8a74b177
2 changed files with 42 additions and 2 deletions
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38
drivers/scsi/device_handler/scsi_dh.c
View file

@ -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 +529,38 @@ void scsi_dh_detach(struct request_queue *q)
}
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
* @gfp - the GFP mask used in the kmalloc() call when allocating memory
*
* Returns name of attached handler, NULL if no handler is attached.
* Caller must take care to free the returned string.
*/
const char *scsi_dh_attached_handler_name(struct request_queue *q, gfp_t gfp)
{
unsigned long flags;
struct scsi_device *sdev;
const char *handler_name = 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 NULL;
if (sdev->scsi_dh_data)
handler_name = kstrdup(sdev->scsi_dh_data->scsi_dh->name, gfp);
put_device(&sdev->sdev_gendev);
return handler_name;
}
EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);
static struct notifier_block scsi_dh_nb = {
.notifier_call = scsi_dh_notifier
};

6
include/scsi/scsi_dh.h
View file

@ -60,6 +60,7 @@ extern int scsi_dh_activate(struct request_queue *, activate_complete, void *);
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 *, gfp_t);
extern int scsi_dh_set_params(struct request_queue *, const char *);
#else
static inline int scsi_dh_activate(struct request_queue *req,
@ -80,6 +81,11 @@ static inline void scsi_dh_detach(struct request_queue *q)
{
return;
}
static inline const char *scsi_dh_attached_handler_name(struct request_queue *q,
gfp_t gfp)
{
return NULL;
}
static inline int scsi_dh_set_params(struct request_queue *req, const char *params)
{
return -SCSI_DH_NOSYS;