scsi: scsi_ioctl: add sg_io_to_blk_status()

This helper converts the SCSI result in a sg_io_hdr struct to a blk_status_t.
It will be used in the SG_IO code path for dm-multipath. Putting it into
scsi_ioctl.c avoids open-coding SCSI specific code in the dm layer.

Signed-off-by: Martin Wilck <mwilck@suse.com>

block/scsi_ioctl.c

@@ -929,6 +929,26 @@ blk_status_t __scsi_result_to_blk_status(int *cmd_result, int result)
 }
 EXPORT_SYMBOL(__scsi_result_to_blk_status);
 
+blk_status_t sg_io_to_blk_status(struct sg_io_hdr *hdr)
+{
+	int result;
+	blk_status_t sts;
+
+	if (!hdr->info & SG_INFO_CHECK)
+		return BLK_STS_OK;
+
+	result = hdr->status |
+		(hdr->msg_status << 8) |
+		(hdr->host_status << 16) |
+		(hdr->driver_status << 24);
+
+	sts = __scsi_result_to_blk_status(&result, result);
+	hdr->host_status = host_byte(result);
+
+	return sts;
+}
+EXPORT_SYMBOL(sg_io_to_blk_status);
+
 static int __init blk_scsi_ioctl_init(void)
 {
 	blk_set_cmd_filter_defaults(&blk_default_cmd_filter);

include/linux/blkdev.h

@@ -2022,4 +2022,5 @@ int freeze_bdev(struct block_device *bdev);
 int thaw_bdev(struct block_device *bdev);
 
 blk_status_t __scsi_result_to_blk_status(int *cmd_result, int result);
+blk_status_t sg_io_to_blk_status(struct sg_io_hdr *hdr);
 #endif /* _LINUX_BLKDEV_H */