scsi: bfa: fix type conversion warning

A regression fix introduced a harmless type mismatch warning:

drivers/scsi/bfa/bfad_bsg.c: In function 'bfad_im_bsg_vendor_request':
drivers/scsi/bfa/bfad_bsg.c:3137:35: error: initialization of 'struct bfad_im_port_s *' from 'long unsigned int' makes pointer from integer without a cast [-Werror=int-conversion]
struct bfad_im_port_s *im_port = shost->hostdata[0];
^~~~~
drivers/scsi/bfa/bfad_bsg.c: In function 'bfad_im_bsg_els_ct_request':
drivers/scsi/bfa/bfad_bsg.c:3353:35: error: initialization of 'struct bfad_im_port_s *' from 'long unsigned int' makes pointer from integer without a cast [-Werror=int-conversion]
struct bfad_im_port_s *im_port = shost->hostdata[0];

This changes the code back to shost_priv() once more, but encapsulates
it in an inline function to document the rather unusual way of
using the private data only as a pointer to the previously allocated
structure.

I did not try to get rid of the extra indirection level entirely,
which would have been rather invasive and required reworking the entire
initialization sequence.

Fixes: 45349821ab3a ("scsi: bfa: fix access to bfad_im_port_s")
Signed-off-by: Arnd Bergmann <[e-mail]>
Reviewed-by: Johannes Thumshirn <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/bfa/bfad_bsg.c

···
 	struct fc_bsg_reply *bsg_reply = job->reply;
 	uint32_t vendor_cmd = bsg_request->rqst_data.h_vendor.vendor_cmd[0];
 	struct Scsi_Host *shost = fc_bsg_to_shost(job);
-	struct bfad_im_port_s *im_port = shost->hostdata[0];
+	struct bfad_im_port_s *im_port = bfad_get_im_port(shost);
 	struct bfad_s *bfad = im_port->bfad;
 	void *payload_kbuf;
 	int rc = -EINVAL;
···
 {
 	struct bfa_bsg_data *bsg_data;
 	struct Scsi_Host *shost = fc_bsg_to_shost(job);
-	struct bfad_im_port_s *im_port = shost->hostdata[0];
+	struct bfad_im_port_s *im_port = bfad_get_im_port(shost);
 	struct bfad_s *bfad = im_port->bfad;
 	bfa_bsg_fcpt_t *bsg_fcpt;
 	struct bfad_fcxp    *drv_fcxp;

drivers/scsi/bfa/bfad_im.c

···
 bfad_im_scsi_host_alloc(struct bfad_s *bfad, struct bfad_im_port_s *im_port,
 			struct device *dev)
 {
+	struct bfad_im_port_pointer *im_portp;
 	int error = 1;
 
 	mutex_lock(&bfad_mutex);
···
 		goto out_free_idr;
 	}
 
-	im_port->shost->hostdata[0] = (unsigned long)im_port;
+	im_portp = shost_priv(im_port->shost);
+	im_portp->p = im_port;
 	im_port->shost->unique_id = im_port->idr_id;
 	im_port->shost->this_id = -1;
 	im_port->shost->max_id = MAX_FCP_TARGET;
···
 
 	sht->sg_tablesize = bfad->cfg_data.io_max_sge;
 
-	return scsi_host_alloc(sht, sizeof(unsigned long));
+	return scsi_host_alloc(sht, sizeof(struct bfad_im_port_pointer));
 }
 
 void

drivers/scsi/bfa/bfad_im.h

···
 	struct fc_vport *fc_vport;
 };
 
+struct bfad_im_port_pointer {
+	struct bfad_im_port_s *p;
+};
+
+static inline struct bfad_im_port_s *bfad_get_im_port(struct Scsi_Host *host)
+{
+	struct bfad_im_port_pointer *im_portp = shost_priv(host);
+	return im_portp->p;
+}
+
 enum bfad_itnim_state {
 	ITNIM_STATE_NONE,
 	ITNIM_STATE_ONLINE,