[SCSI] use the scsi data buffer length to extract transfer size

martinkpetersen · James Bottomley · commit 5616b0a46ed8 · 2014-07-03T10:50:31.000-07:00
Commit 8846bab introduced a helper that can be used to query the wire transfer size for a SCSI command taking protection information into account. However, some commands do not have a 1:1 mapping between the block range they work on and the payload size (discard, write same). After the scatterlist has been set up these requests use __data_len to store the number of bytes to report completion on. This means that callers of scsi_transfer_length() would get the wrong byte count for these types of requests. To overcome this we make scsi_transfer_length() use the scatterlist length in the scsi_data_buffer as basis for the wire transfer calculation instead of __data_len. Reported-by: Christoph Hellwig <hch@infradead.org> Debugged-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagig@mellanox.com> Fixes: d77e653 Cc: stable@vger.kernel.org Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
@@ -318,7 +318,7 @@ static inline void set_driver_byte(struct scsi_cmnd *cmd, char status)
 
 static inline unsigned scsi_transfer_length(struct scsi_cmnd *scmd)
 {
-	unsigned int xfer_len = blk_rq_bytes(scmd->request);
+	unsigned int xfer_len = scsi_out(scmd)->length;
 	unsigned int prot_op = scsi_get_prot_op(scmd);
 	unsigned int sector_size = scmd->device->sector_size;
 

Original file line number	Diff line number	Diff line change
`@@ -318,7 +318,7 @@ static inline void set_driver_byte(struct scsi_cmnd *cmd, char status)`
`318`	`318`
`319`	`319`	`static inline unsigned scsi_transfer_length(struct scsi_cmnd *scmd)`
`320`	`320`	`{`
`321`		`- unsigned int xfer_len = blk_rq_bytes(scmd->request);`
	`321`	`+ unsigned int xfer_len = scsi_out(scmd)->length;`
`322`	`322`	`unsigned int prot_op = scsi_get_prot_op(scmd);`
`323`	`323`	`unsigned int sector_size = scmd->device->sector_size;`
`324`	`324`