scsiback: free resources after error

In case of an error during preparing an I/O the already allocated resources
should all be freed again and the frontend request should be terminated
accordingly.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Some formatting adjustments to the changes above, and some more releasing
of resources (in the VSCSIIF_ACT_SCSI_RESET and default cases of the switch
in scsiback_do_cmd_fn()).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/drivers/xen/scsiback/common.h
+++ b/drivers/xen/scsiback/common.h
@@ -163,13 +163,13 @@ struct scsi_device *scsiback_do_translat
 void scsiback_release_translation_entry(struct vscsibk_info *info);
 
 
-void scsiback_cmd_exec(pending_req_t *pending_req);
+int scsiback_cmd_exec(pending_req_t *pending_req);
 void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,
 			uint32_t resid, pending_req_t *pending_req);
 void scsiback_fast_flush_area(pending_req_t *req);
 
 void scsiback_rsp_emulation(pending_req_t *pending_req);
-void scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req);
+int scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req);
 void scsiback_emulation_init(void);
 
 
--- a/drivers/xen/scsiback/emulate.c
+++ b/drivers/xen/scsiback/emulate.c
@@ -345,16 +345,16 @@ void scsiback_rsp_emulation(pending_req_
 }
 
 
-void scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req)
+int scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req)
 {
-	if (__pre_do_emulation(pending_req, NULL)) {
-		scsiback_cmd_exec(pending_req);
-	}
-	else {
-		scsiback_fast_flush_area(pending_req);
-		scsiback_do_resp_with_sense(pending_req->sense_buffer,
-		  pending_req->rslt, pending_req->resid, pending_req);
-	}
+	if (__pre_do_emulation(pending_req, NULL))
+		return scsiback_cmd_exec(pending_req);
+
+	scsiback_fast_flush_area(pending_req);
+	scsiback_do_resp_with_sense(pending_req->sense_buffer,
+				    pending_req->rslt, pending_req->resid,
+				    pending_req);
+	return 0;
 }
 
 
--- a/drivers/xen/scsiback/scsiback.c
+++ b/drivers/xen/scsiback/scsiback.c
@@ -429,14 +429,14 @@ free_bios:
 }
 
 
-void scsiback_cmd_exec(pending_req_t *pending_req)
+int scsiback_cmd_exec(pending_req_t *pending_req)
 {
 	int cmd_len  = (int)pending_req->cmd_len;
 	int data_dir = (int)pending_req->sc_data_direction;
 	unsigned int nr_segments = (unsigned int)pending_req->nr_segments;
 	unsigned int timeout;
 	struct request *rq;
-	int write;
+	int write, err;
 
 	DPRINTK("%s\n",__FUNCTION__);
 
@@ -463,17 +463,19 @@ void scsiback_cmd_exec(pending_req_t *pe
 	rq->end_io_data = pending_req;
 
 	if (nr_segments) {
-
-		if (request_map_sg(rq, pending_req, nr_segments)) {
-			printk(KERN_ERR "scsiback: SG Request Map Error\n");
-			return;
+		err = request_map_sg(rq, pending_req, nr_segments);
+		if (err) {
+			printk(KERN_ERR "scsiback: SG Request Map error %d\n",
+			       err);
+			blk_put_request(rq);
+			return err;
 		}
 	}
 
 	scsiback_get(pending_req->info);
 	blk_execute_rq_nowait(rq->q, NULL, rq, 1, scsiback_cmd_done);
 
-	return ;
+	return 0;
 }
 
 
@@ -615,17 +617,28 @@ static int scsiback_do_cmd_fn(struct vsc
 		switch (err ?: pending_req->act) {
 		case VSCSIIF_ACT_SCSI_CDB:
 			/* The Host mode is through as for Emulation. */
-			if (info->feature == VSCSI_TYPE_HOST)
-				scsiback_cmd_exec(pending_req);
-			else
-				scsiback_req_emulation_or_cmdexec(pending_req);
+			if (info->feature == VSCSI_TYPE_HOST ?
+			    scsiback_cmd_exec(pending_req) :
+			    scsiback_req_emulation_or_cmdexec(pending_req)) {
+				scsiback_fast_flush_area(pending_req);
+				scsiback_do_resp_with_sense(NULL,
+							    DRIVER_ERROR << 24,
+							    0, pending_req);
+			}
 			break;
 		case VSCSIIF_ACT_SCSI_RESET:
+			/* Just for pointlessly specified segments: */
+			scsiback_fast_flush_area(pending_req);
 			scsiback_device_reset_exec(pending_req);
 			break;
 		default:
-			if(!err && printk_ratelimit())
-				printk(KERN_ERR "scsiback: invalid request\n");
+			if(!err) {
+				scsiback_fast_flush_area(pending_req);
+				if (printk_ratelimit())
+					printk(KERN_ERR
+					       "scsiback: invalid request %#x\n",
+					       pending_req->act);
+			}
 			scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24,
 						    0, pending_req);
 			break;