Hi Bart,

thanks for looking at this.

On Thu, 2021-04-29 at 09:20 -0700, Bart Van Assche wrote:

On 4/29/21 8:50 AM, mwilck@suse.com wrote:

quoted

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

I think that's the wrong reason to make a function inline. Please
consider moving scsi_result_to_blk_status() into one of the block
layer
source code files that already deals with SG I/O, e.g.
block/scsi_ioctl.c.

scsi_ioctl.c, are you certain? scsi_result_to_blk_status() is an
important part of the block/scsi interface... You're right that that
this function is not a prime candidate for inlining, but I'm still
wondering where it belongs if we don't.

Looking forward to see what others think.

quoted

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);
 }

The layout of the SCSI result won't change since it is used in
multiple
UAPI data structures. I'd prefer to open-code host_byte() in
scsi_result_to_blk_status() instead of making the above changes.

OK. I'm generally no fan of hard-coding but I guess you're right
in this case.

Thanks,
Martin