[SCSI] add retries field to request for REQ_BLOCK_PC use

For tape we need to control the retries. This patch adds a retries
counter on the request for REQ_BLOCK_PC commands originating from
scsi_execute* to use. REQ_BLOCK_PC commands comming from the block
layer SG_IO path continue to use the retires set in the ULD init_command.
(scsi_execute* does not set the gendisk so we do not execute
the init_command in that path).

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_lib.c

@@ -259,6 +259,7 @@ int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 	memcpy(req->cmd, cmd, req->cmd_len);
 	req->sense = sense;
 	req->sense_len = 0;
+	req->retries = retries;
 	req->timeout = timeout;
 	req->flags |= flags | REQ_BLOCK_PC | REQ_SPECIAL | REQ_QUIET;
 
@@ -472,6 +473,7 @@ int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
 	req->sense = sioc->sense;
 	req->sense_len = 0;
 	req->timeout = timeout;
+	req->retries = retries;
 	req->flags |= REQ_BLOCK_PC | REQ_QUIET;
 	req->end_io_data = sioc;
 
@@ -1393,7 +1395,7 @@ static int scsi_prep_fn(struct request_queue *q, struct request *req)
 				cmd->sc_data_direction = DMA_NONE;
 
 			cmd->transfersize = req->data_len;
-			cmd->allowed = 3;
+			cmd->allowed = req->retries;
 			cmd->timeout_per_command = req->timeout;
 			cmd->done = scsi_generic_done;
 		}

include/linux/blkdev.h

@@ -184,6 +184,7 @@ struct request {
 	void *sense;
 
 	unsigned int timeout;
+	int retries;
 
 	/*
 	 * For Power Management requests