[RFC PATCH v2 1/2] scsi: convert scsi_result_to_blk_status() to inline

[mwilck@suse.com]

From: Martin Wilck <mwilck@suse.com>

This makes it possible to use scsi_result_to_blk_status() from
code that shouldn't depend on scsi_mod (e.g. device mapper).

Also, create variants of set_host_byte() etc. that don't expect
a struct scsi_cmnd *, but just a pointer to the result to be
modified/fixed.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 drivers/scsi/scsi_lib.c  | 40 -------------------
 include/scsi/scsi_cmnd.h | 83 ++++++++++++++++++++++++++++++++++++++--
 2 files changed, 79 insertions(+), 44 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index d7c0d5a5f263..e423184f2bba 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -610,46 +610,6 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
 	return false;
 }
 
-/**
- * scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
- * @cmd:	SCSI command
- * @result:	scsi error code
- *
- * Translate a SCSI result code into a blk_status_t value. May reset the host
- * byte of @cmd->result.
- */
-static blk_status_t scsi_result_to_blk_status(struct scsi_cmnd *cmd, int result)
-{
-	switch (host_byte(result)) {
-	case DID_OK:
-		/*
-		 * Also check the other bytes than the status byte in result
-		 * to handle the case when a SCSI LLD sets result to
-		 * DRIVER_SENSE << 24 without setting SAM_STAT_CHECK_CONDITION.
-		 */
-		if (scsi_status_is_good(result) && (result & ~0xff) == 0)
-			return BLK_STS_OK;
-		return BLK_STS_IOERR;
-	case DID_TRANSPORT_FAILFAST:
-	case DID_TRANSPORT_MARGINAL:
-		return BLK_STS_TRANSPORT;
-	case DID_TARGET_FAILURE:
-		set_host_byte(cmd, DID_OK);
-		return BLK_STS_TARGET;
-	case DID_NEXUS_FAILURE:
-		set_host_byte(cmd, DID_OK);
-		return BLK_STS_NEXUS;
-	case DID_ALLOC_FAILURE:
-		set_host_byte(cmd, DID_OK);
-		return BLK_STS_NOSPC;
-	case DID_MEDIUM_ERROR:
-		set_host_byte(cmd, DID_OK);
-		return BLK_STS_MEDIUM;
-	default:
-		return BLK_STS_IOERR;
-	}
-}
-
 /* Helper for scsi_io_completion() when "reprep" action required. */
 static void scsi_io_completion_reprep(struct scsi_cmnd *cmd,
 				      struct request_queue *q)
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 83f7e520be48..ba1e69d3bed9 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -311,24 +311,44 @@ static inline struct scsi_data_buffer *scsi_prot(struct scsi_cmnd *cmd)
 #define scsi_for_each_prot_sg(cmd, sg, nseg, __i)		\
 	for_each_sg(scsi_prot_sglist(cmd), sg, nseg, __i)
 
+static inline void __set_status_byte(int *result, char status)
+{
+	*result = (*result & 0xffffff00) | status;
+}
+
 static inline void set_status_byte(struct scsi_cmnd *cmd, char status)
 {
-	cmd->result = (cmd->result & 0xffffff00) | status;
+	__set_status_byte(&cmd->result, status);
+}
+
+static inline void __set_msg_byte(int *result, char status)
+{
+	*result = (*result & 0xffff00ff) | (status << 8);
 }
 
 static inline void set_msg_byte(struct scsi_cmnd *cmd, char status)
 {
-	cmd->result = (cmd->result & 0xffff00ff) | (status << 8);
+	__set_msg_byte(&cmd->result, status);
+}
+
+static inline void __set_host_byte(int *result, char status)
+{
+	*result = (*result & 0xff00ffff) | (status << 16);
 }
 
 static inline void set_host_byte(struct scsi_cmnd *cmd, char status)
 {
-	cmd->result = (cmd->result & 0xff00ffff) | (status << 16);
+	__set_host_byte(&cmd->result, status);
+}
+
+static inline void __set_driver_byte(int *result, char status)
+{
+	*result = (*result & 0x00ffffff) | (status << 24);
 }
 
 static inline void set_driver_byte(struct scsi_cmnd *cmd, char status)
 {
-	cmd->result = (cmd->result & 0x00ffffff) | (status << 24);
+	__set_driver_byte(&cmd->result, status);
 }
 
 static inline unsigned scsi_transfer_length(struct scsi_cmnd *scmd)
@@ -342,4 +362,59 @@ static inline unsigned scsi_transfer_length(struct scsi_cmnd *scmd)
 	return xfer_len;
 }
 
+/**
+ * scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
+ * @result:	scsi error code
+ * @cmd_result: pointer to scsi cmnd result code to be possibly changed
+ *
+ * Translate a SCSI result code into a blk_status_t value. May reset the host
+ * byte of @cmd_result.
+ */
+static inline blk_status_t __scsi_result_to_blk_status(int *cmd_result, int result)
+{
+	switch (host_byte(result)) {
+	case DID_OK:
+		/*
+		 * Also check the other bytes than the status byte in result
+		 * to handle the case when a SCSI LLD sets result to
+		 * DRIVER_SENSE << 24 without setting SAM_STAT_CHECK_CONDITION.
+		 */
+		if (scsi_status_is_good(result) && (result & ~0xff) == 0)
+			return BLK_STS_OK;
+		return BLK_STS_IOERR;
+	case DID_TRANSPORT_FAILFAST:
+	case DID_TRANSPORT_MARGINAL:
+		return BLK_STS_TRANSPORT;
+	case DID_TARGET_FAILURE:
+		__set_host_byte(cmd_result, DID_OK);
+		return BLK_STS_TARGET;
+	case DID_NEXUS_FAILURE:
+		__set_host_byte(cmd_result, DID_OK);
+		return BLK_STS_NEXUS;
+	case DID_ALLOC_FAILURE:
+		__set_host_byte(cmd_result, DID_OK);
+		return BLK_STS_NOSPC;
+	case DID_MEDIUM_ERROR:
+		__set_host_byte(cmd_result, DID_OK);
+		return BLK_STS_MEDIUM;
+	default:
+		return BLK_STS_IOERR;
+	}
+}
+
+/**
+ * scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
+ * @cmd:	SCSI command
+ * @result:	scsi error code
+ *
+ * Translate a SCSI result code into a blk_status_t value. May reset the host
+ * byte of @cmd->result.
+ */
+static inline blk_status_t scsi_result_to_blk_status(struct scsi_cmnd *cmd,
+						     int result)
+{
+	return __scsi_result_to_blk_status(&cmd->result, result);
+}
+
+
 #endif /* _SCSI_SCSI_CMND_H */
-- 
2.31.1