3 files changed, 13 insertions, 6 deletions

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index bda1497add4c..51bf5155ee75 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 a9f3c6fc3f57..4734c15ab5d6 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 7a12e1c0f371..02986cf8b6f1 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 */