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-rw-r--r--block/scsi_ioctl.c5
-rw-r--r--include/scsi/sg.h3
-rw-r--r--include/uapi/linux/bsg.h11
3 files changed, 13 insertions, 6 deletions
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index bda1497..51bf515 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -290,6 +290,7 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
unsigned long start_time;
ssize_t ret = 0;
int writing = 0;
+ int at_head = 0;
struct request *rq;
char sense[SCSI_SENSE_BUFFERSIZE];
struct bio *bio;
@@ -313,6 +314,8 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
case SG_DXFER_FROM_DEV:
break;
}
+ if (hdr->flags & SG_FLAG_Q_AT_HEAD)
+ at_head = 1;
rq = blk_get_request(q, writing ? WRITE : READ, GFP_KERNEL);
if (!rq)
@@ -369,7 +372,7 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
* (if he doesn't check that is his problem).
* N.B. a non-zero SCSI status is _not_ necessarily an error.
*/
- blk_execute_rq(q, bd_disk, rq, 0);
+ blk_execute_rq(q, bd_disk, rq, at_head);
hdr->duration = jiffies_to_msecs(jiffies - start_time);
diff --git a/include/scsi/sg.h b/include/scsi/sg.h
index a9f3c6f..4734c15 100644
--- a/include/scsi/sg.h
+++ b/include/scsi/sg.h
@@ -129,6 +129,9 @@ typedef struct sg_io_hdr
#define SG_FLAG_MMAP_IO 4 /* request memory mapped IO */
#define SG_FLAG_NO_DXFER 0x10000 /* no transfer of kernel buffers to/from */
/* user space (debug indirect IO) */
+/* defaults:: for sg driver: Q_AT_HEAD; for block layer: Q_AT_TAIL */
+#define SG_FLAG_Q_AT_TAIL 0x10
+#define SG_FLAG_Q_AT_HEAD 0x20
/* following 'info' values are "or"-ed together */
#define SG_INFO_OK_MASK 0x1
diff --git a/include/uapi/linux/bsg.h b/include/uapi/linux/bsg.h
index 7a12e1c..02986cf 100644
--- a/include/uapi/linux/bsg.h
+++ b/include/uapi/linux/bsg.h
@@ -10,12 +10,13 @@
#define BSG_SUB_PROTOCOL_SCSI_TRANSPORT 2
/*
- * For flags member below
- * sg.h sg_io_hdr also has bits defined for it's flags member. However
- * none of these bits are implemented/used by bsg. The bits below are
- * allocated to not conflict with sg.h ones anyway.
+ * For flag constants below:
+ * sg.h sg_io_hdr also has bits defined for it's flags member. These
+ * two flag values (0x10 and 0x20) have the same meaning in sg.h . For
+ * bsg the BSG_FLAG_Q_AT_HEAD flag is ignored since it is the deafult.
*/
-#define BSG_FLAG_Q_AT_TAIL 0x10 /* default, == 0 at this bit, is Q_AT_HEAD */
+#define BSG_FLAG_Q_AT_TAIL 0x10 /* default is Q_AT_HEAD */
+#define BSG_FLAG_Q_AT_HEAD 0x20
struct sg_io_v4 {
__s32 guard; /* [i] 'Q' to differentiate from v3 */
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