scsi: add a scsi_alloc_request helper

Add a new helper that calls blk_get_request and initializes the
scsi_request to avoid the indirect call through ->.initialize_rq_fn.

Note that this makes the pktcdvd driver depend on the SCSI core, but
given that only SCSI devices support SCSI passthrough requests that
is not a functional change.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20211021060607.264371-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/Kconfig

@@ -304,8 +304,8 @@ config BLK_DEV_RAM_SIZE
 config CDROM_PKTCDVD
 	tristate "Packet writing on CD/DVD media (DEPRECATED)"
 	depends on !UML
+	depends on SCSI
 	select CDROM
-	select SCSI_COMMON
 	help
 	  Note: This driver is deprecated and will be removed from the
 	  kernel in the near future!

drivers/block/pktcdvd.c

@@ -703,7 +703,7 @@ static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *
 	struct request *rq;
 	int ret = 0;
 
-	rq = blk_get_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?
+	rq = scsi_alloc_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?
 			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);

drivers/scsi/scsi_bsg.c

@@ -25,8 +25,8 @@ static int scsi_bsg_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 		return -EOPNOTSUPP;
 	}
 
-	rq = blk_get_request(q, hdr->dout_xfer_len ?
+	rq = scsi_alloc_request(q, hdr->dout_xfer_len ?
-			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
+				REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
 	rq->timeout = timeout;

drivers/scsi/scsi_error.c

@@ -1998,7 +1998,7 @@ static void scsi_eh_lock_door(struct scsi_device *sdev)
 	struct request *req;
 	struct scsi_request *rq;
 
-	req = blk_get_request(sdev->request_queue, REQ_OP_DRV_IN, 0);
+	req = scsi_alloc_request(sdev->request_queue, REQ_OP_DRV_IN, 0);
 	if (IS_ERR(req))
 		return;
 	rq = scsi_req(req);

drivers/scsi/scsi_ioctl.c

@@ -438,7 +438,7 @@ static int sg_io(struct scsi_device *sdev, struct gendisk *disk,
 		at_head = 1;
 
 	ret = -ENOMEM;
-	rq = blk_get_request(sdev->request_queue, writing ?
+	rq = scsi_alloc_request(sdev->request_queue, writing ?
 			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
@@ -561,7 +561,7 @@ static int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk,
 
 	}
 
-	rq = blk_get_request(q, in_len ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
+	rq = scsi_alloc_request(q, in_len ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(rq)) {
 		err = PTR_ERR(rq);
 		goto error_free_buffer;

drivers/scsi/scsi_lib.c

@@ -216,7 +216,7 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 	struct scsi_request *rq;
 	int ret;
 
-	req = blk_get_request(sdev->request_queue,
+	req = scsi_alloc_request(sdev->request_queue,
 			data_direction == DMA_TO_DEVICE ?
 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN,
 			rq_flags & RQF_PM ? BLK_MQ_REQ_PM : 0);
@@ -1079,9 +1079,6 @@ EXPORT_SYMBOL(scsi_alloc_sgtables);
  * This function initializes the members of struct scsi_cmnd that must be
  * initialized before request processing starts and that won't be
  * reinitialized if a SCSI command is requeued.
- *
- * Called from inside blk_get_request() for pass-through requests and from
- * inside scsi_init_command() for filesystem requests.
  */
 static void scsi_initialize_rq(struct request *rq)
 {
@@ -1098,6 +1095,18 @@ static void scsi_initialize_rq(struct request *rq)
 	cmd->retries = 0;
 }
 
+struct request *scsi_alloc_request(struct request_queue *q,
+		unsigned int op, blk_mq_req_flags_t flags)
+{
+	struct request *rq;
+
+	rq = blk_get_request(q, op, flags);
+	if (!IS_ERR(rq))
+		scsi_initialize_rq(rq);
+	return rq;
+}
+EXPORT_SYMBOL_GPL(scsi_alloc_request);
+
 /*
  * Only called when the request isn't completed by SCSI, and not freed by
  * SCSI
@@ -1864,7 +1873,6 @@ static const struct blk_mq_ops scsi_mq_ops_no_commit = {
 #endif
 	.init_request	= scsi_mq_init_request,
 	.exit_request	= scsi_mq_exit_request,
-	.initialize_rq_fn = scsi_initialize_rq,
 	.cleanup_rq	= scsi_cleanup_rq,
 	.busy		= scsi_mq_lld_busy,
 	.map_queues	= scsi_map_queues,
@@ -1894,7 +1902,6 @@ static const struct blk_mq_ops scsi_mq_ops = {
 #endif
 	.init_request	= scsi_mq_init_request,
 	.exit_request	= scsi_mq_exit_request,
-	.initialize_rq_fn = scsi_initialize_rq,
 	.cleanup_rq	= scsi_cleanup_rq,
 	.busy		= scsi_mq_lld_busy,
 	.map_queues	= scsi_map_queues,

drivers/scsi/sg.c

@@ -1718,13 +1718,13 @@ sg_start_req(Sg_request *srp, unsigned char *cmd)
 	 *
 	 * With scsi-mq enabled, there are a fixed number of preallocated
 	 * requests equal in number to shost->can_queue.  If all of the
-	 * preallocated requests are already in use, then blk_get_request()
+	 * preallocated requests are already in use, then scsi_alloc_request()
 	 * will sleep until an active command completes, freeing up a request.
 	 * Although waiting in an asynchronous interface is less than ideal, we
 	 * do not want to use BLK_MQ_REQ_NOWAIT here because userspace might
 	 * not expect an EWOULDBLOCK from this condition.
 	 */
-	rq = blk_get_request(q, hp->dxfer_direction == SG_DXFER_TO_DEV ?
+	rq = scsi_alloc_request(q, hp->dxfer_direction == SG_DXFER_TO_DEV ?
 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(rq)) {
 		kfree(long_cmdp);

drivers/scsi/sr.c

@@ -967,7 +967,7 @@ static int sr_read_cdda_bpc(struct cdrom_device_info *cdi, void __user *ubuf,
 	struct bio *bio;
 	int ret;
 
-	rq = blk_get_request(disk->queue, REQ_OP_DRV_IN, 0);
+	rq = scsi_alloc_request(disk->queue, REQ_OP_DRV_IN, 0);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
 	req = scsi_req(rq);

drivers/scsi/st.c

@@ -543,7 +543,7 @@ static int st_scsi_execute(struct st_request *SRpnt, const unsigned char *cmd,
 	int err = 0;
 	struct scsi_tape *STp = SRpnt->stp;
 
-	req = blk_get_request(SRpnt->stp->device->request_queue,
+	req = scsi_alloc_request(SRpnt->stp->device->request_queue,
 			data_direction == DMA_TO_DEVICE ?
 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(req))

drivers/target/target_core_pscsi.c

@@ -980,11 +980,10 @@ pscsi_execute_cmd(struct se_cmd *cmd)
 	memcpy(pt->pscsi_cdb, cmd->t_task_cdb,
 		scsi_command_size(cmd->t_task_cdb));
 
-	req = blk_get_request(pdv->pdv_sd->request_queue,
+	req = scsi_alloc_request(pdv->pdv_sd->request_queue,
 			cmd->data_direction == DMA_TO_DEVICE ?
 			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
 	if (IS_ERR(req)) {
-		pr_err("PSCSI: blk_get_request() failed\n");
 		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 		goto fail;
 	}

include/scsi/scsi_cmnd.h

@@ -396,4 +396,7 @@ static inline unsigned scsi_transfer_length(struct scsi_cmnd *scmd)
 extern void scsi_build_sense(struct scsi_cmnd *scmd, int desc,
 			     u8 key, u8 asc, u8 ascq);
 
+struct request *scsi_alloc_request(struct request_queue *q,
+		unsigned int op, blk_mq_req_flags_t flags);
+
 #endif /* _SCSI_SCSI_CMND_H */