scsi: explicitly release bidi buffers

Instead of trying to guess when we have a BIDI buffer in scsi_release_buffers
add a function to explicitly free the BIDI ressoures in the one place that
handles them.  This avoids needing a special __scsi_release_buffers for the
case where we already have freed the request as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>

drivers/scsi/scsi_lib.c

@@ -512,8 +512,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
 		scsi_run_queue(sdev->request_queue);
 }
 
-static void __scsi_release_buffers(struct scsi_cmnd *, int);
-
 /*
  * Function:    scsi_end_request()
  *
@@ -569,7 +567,7 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
 	 * This will goose the queue request function at the end, so we don't
 	 * need to worry about launching another command.
 	 */
-	__scsi_release_buffers(cmd, 0);
+	scsi_release_buffers(cmd);
 	scsi_next_command(cmd);
 	return NULL;
 }
@@ -625,30 +623,10 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
 	__sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
 }
 
-static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
-{
-
-	if (cmd->sdb.table.nents)
-		scsi_free_sgtable(&cmd->sdb);
-
-	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
-
-	if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
-		struct scsi_data_buffer *bidi_sdb =
-			cmd->request->next_rq->special;
-		scsi_free_sgtable(bidi_sdb);
-		kmem_cache_free(scsi_sdb_cache, bidi_sdb);
-		cmd->request->next_rq->special = NULL;
-	}
-
-	if (scsi_prot_sg_count(cmd))
-		scsi_free_sgtable(cmd->prot_sdb);
-}
-
 /*
  * Function:    scsi_release_buffers()
  *
- * Purpose:     Completion processing for block device I/O requests.
+ * Purpose:     Free resources allocate for a scsi_command.
  *
  * Arguments:   cmd	- command that we are bailing.
  *
@@ -659,15 +637,29 @@ static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
  * Notes:       In the event that an upper level driver rejects a
  *		command, we must release resources allocated during
  *		the __init_io() function.  Primarily this would involve
- *		the scatter-gather table, and potentially any bounce
- *		buffers.
+ *		the scatter-gather table.
  */
 void scsi_release_buffers(struct scsi_cmnd *cmd)
 {
-	__scsi_release_buffers(cmd, 1);
+	if (cmd->sdb.table.nents)
+		scsi_free_sgtable(&cmd->sdb);
+
+	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
+
+	if (scsi_prot_sg_count(cmd))
+		scsi_free_sgtable(cmd->prot_sdb);
 }
 EXPORT_SYMBOL(scsi_release_buffers);
 
+static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
+{
+	struct scsi_data_buffer *bidi_sdb = cmd->request->next_rq->special;
+
+	scsi_free_sgtable(bidi_sdb);
+	kmem_cache_free(scsi_sdb_cache, bidi_sdb);
+	cmd->request->next_rq->special = NULL;
+}
+
 /**
  * __scsi_error_from_host_byte - translate SCSI error code into errno
  * @cmd:	SCSI command (unused)
@@ -801,6 +793,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 			req->next_rq->resid_len = scsi_in(cmd)->resid;
 
 			scsi_release_buffers(cmd);
+			scsi_release_bidi_buffers(cmd);
 			blk_end_request_all(req, 0);
 
 			scsi_next_command(cmd);