block: split scsi_request out of struct request

And require all drivers that want to support BLOCK_PC to allocate it
as the first thing of their private data.  To support this the legacy
IDE and BSG code is switched to set cmd_size on their queues to let
the block layer allocate the additional space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/include/scsi/scsi_request.h b/include/scsi/scsi_request.h
new file mode 100644
index 000000000000..ba0aeb980f7e
--- /dev/null
+++ b/include/scsi/scsi_request.h
@@ -0,0 +1,30 @@
+#ifndef _SCSI_SCSI_REQUEST_H
+#define _SCSI_SCSI_REQUEST_H
+
+#include <linux/blk-mq.h>
+
+#define BLK_MAX_CDB	16
+
+struct scsi_request {
+	unsigned char	__cmd[BLK_MAX_CDB];
+	unsigned char	*cmd;
+	unsigned short	cmd_len;
+	unsigned int	sense_len;
+	unsigned int	resid_len;	/* residual count */
+	void		*sense;
+};
+
+static inline struct scsi_request *scsi_req(struct request *rq)
+{
+	return blk_mq_rq_to_pdu(rq);
+}
+
+static inline void scsi_req_free_cmd(struct scsi_request *req)
+{
+	if (req->cmd != req->__cmd)
+		kfree(req->cmd);
+}
+
+void scsi_req_init(struct request *);
+
+#endif /* _SCSI_SCSI_REQUEST_H */