On Tue, 1 Jun 2010 13:25:24 +0530
"Prakash, Sathya" <Sathya.Prakash@xxxxxxx> wrote:
> I was trying to use scsi_get_lba to get the lba associated with a particular scsi_cmnd. I am able to get proper values when I send I/O through dd or FS. But when I use the sg interface either sg_dd or sg_raw the value I am getting through scsi_get_lba is not matching with the one in the CDB.
>
> Do we need to have some change in sg module for handling this, or is there anything wrong in the way I access the scsi_get_lba or sending command through sg?
>
> Any suggestion or help is highly appreciated.
Seems that scsi_get_lba() can't use REQ_TYPE_BLOCK_PC commands (via
sg, bsg, etc) because request->__sector is not set.
We need to parse sc->cmnd like this.
The following scsi_get_transfer_info() is taken from scsi_debug. Some
(like libata) have similar code so it would make sense to convert it
to a library function.
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index a5e885a..5bd697e 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -7,6 +7,7 @@
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/scatterlist.h>
+#include <scsi/scsi.h>
struct Scsi_Host;
struct scsi_device;
@@ -264,9 +265,75 @@ static inline unsigned char scsi_get_prot_type(struct scsi_cmnd *scmd)
return scmd->prot_type;
}
+static inline void scsi_get_transfer_info(unsigned char *cmd,
+ unsigned long long *lba, unsigned int *num,
+ unsigned int *ei_lba)
+{
+ *ei_lba = 0;
+
+ switch (*cmd) {
+ case VARIABLE_LENGTH_CMD:
+ *lba = (u64)cmd[19] | (u64)cmd[18] << 8 |
+ (u64)cmd[17] << 16 | (u64)cmd[16] << 24 |
+ (u64)cmd[15] << 32 | (u64)cmd[14] << 40 |
+ (u64)cmd[13] << 48 | (u64)cmd[12] << 56;
+
+ *ei_lba = (u32)cmd[23] | (u32)cmd[22] << 8 |
+ (u32)cmd[21] << 16 | (u32)cmd[20] << 24;
+
+ *num = (u32)cmd[31] | (u32)cmd[30] << 8 | (u32)cmd[29] << 16 |
+ (u32)cmd[28] << 24;
+ break;
+
+ case WRITE_SAME_16:
+ case WRITE_16:
+ case READ_16:
+ *lba = (u64)cmd[9] | (u64)cmd[8] << 8 |
+ (u64)cmd[7] << 16 | (u64)cmd[6] << 24 |
+ (u64)cmd[5] << 32 | (u64)cmd[4] << 40 |
+ (u64)cmd[3] << 48 | (u64)cmd[2] << 56;
+
+ *num = (u32)cmd[13] | (u32)cmd[12] << 8 | (u32)cmd[11] << 16 |
+ (u32)cmd[10] << 24;
+ break;
+ case WRITE_12:
+ case READ_12:
+ *lba = (u32)cmd[5] | (u32)cmd[4] << 8 | (u32)cmd[3] << 16 |
+ (u32)cmd[2] << 24;
+
+ *num = (u32)cmd[9] | (u32)cmd[8] << 8 | (u32)cmd[7] << 16 |
+ (u32)cmd[6] << 24;
+ break;
+ case WRITE_SAME:
+ case WRITE_10:
+ case READ_10:
+ case XDWRITEREAD_10:
+ *lba = (u32)cmd[5] | (u32)cmd[4] << 8 | (u32)cmd[3] << 16 |
+ (u32)cmd[2] << 24;
+
+ *num = (u32)cmd[8] | (u32)cmd[7] << 8;
+ break;
+ case WRITE_6:
+ case READ_6:
+ *lba = (u32)cmd[3] | (u32)cmd[2] << 8 |
+ (u32)(cmd[1] & 0x1f) << 16;
+ *num = (0 == cmd[4]) ? 256 : cmd[4];
+ break;
+ default:
+ break;
+ }
+}
+
static inline sector_t scsi_get_lba(struct scsi_cmnd *scmd)
{
- return blk_rq_pos(scmd->request);
+ if (scmd->request->cmd_type == REQ_TYPE_BLOCK_PC) {
+ unsigned long long lba;
+ unsigned int num;
+ unsigned int ei_lba;
+ scsi_get_transfer_info(scmd->cmnd, &lba, &num, &ei_lba);
+ return lba;
+ } else
+ return blk_rq_pos(scmd->request);
}
static inline unsigned scsi_prot_sg_count(struct scsi_cmnd *cmd)
--
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