drbd: Adding support for BIO/Request flags: REQ_FUA, REQ_FLUSH and REQ_DISCARD

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_int.h

@@ -374,9 +374,13 @@ union p_header {
  */
 
 /* these defines must not be changed without changing the protocol version */
-#define DP_HARDBARRIER	      1
-#define DP_RW_SYNC	      2
+#define DP_HARDBARRIER	      1 /* depricated */
+#define DP_RW_SYNC	      2 /* equals REQ_SYNC    */
 #define DP_MAY_SET_IN_SYNC    4
+#define DP_UNPLUG             8 /* equals REQ_UNPLUG  */
+#define DP_FUA               16 /* equals REQ_FUA     */
+#define DP_FLUSH             32 /* equals REQ_FLUSH   */
+#define DP_DISCARD           64 /* equals REQ_DISCARD */
 
 struct p_data {
 	union p_header head;

drivers/block/drbd/drbd_main.c

@@ -2426,6 +2426,18 @@ static int _drbd_send_zc_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
 	return 1;
 }
 
+static u32 bio_flags_to_wire(struct drbd_conf *mdev, unsigned long bi_rw)
+{
+	if (mdev->agreed_pro_version >= 95)
+		return  (bi_rw & REQ_SYNC ? DP_RW_SYNC : 0) |
+			(bi_rw & REQ_UNPLUG ? DP_UNPLUG : 0) |
+			(bi_rw & REQ_FUA ? DP_FUA : 0) |
+			(bi_rw & REQ_FLUSH ? DP_FLUSH : 0) |
+			(bi_rw & REQ_DISCARD ? DP_DISCARD : 0);
+	else
+		return bi_rw & (REQ_SYNC | REQ_UNPLUG) ? DP_RW_SYNC : 0;
+}
+
 /* Used to send write requests
  * R_PRIMARY -> Peer	(P_DATA)
  */
@@ -2459,21 +2471,9 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
 	p.block_id = (unsigned long)req;
 	p.seq_num  = cpu_to_be32(req->seq_num =
 				 atomic_add_return(1, &mdev->packet_seq));
-	dp_flags = 0;
 
-	/* NOTE: no need to check if barriers supported here as we would
-	 *       not pass the test in make_request_common in that case
-	 */
-	if (req->master_bio->bi_rw & REQ_HARDBARRIER) {
-		dev_err(DEV, "ASSERT FAILED would have set DP_HARDBARRIER\n");
-		/* dp_flags |= DP_HARDBARRIER; */
-	}
-	if (req->master_bio->bi_rw & REQ_SYNC)
-		dp_flags |= DP_RW_SYNC;
-	/* for now handle SYNCIO and UNPLUG
-	 * as if they still were one and the same flag */
-	if (req->master_bio->bi_rw & REQ_UNPLUG)
-		dp_flags |= DP_RW_SYNC;
+	dp_flags = bio_flags_to_wire(mdev, req->master_bio->bi_rw);
+
 	if (mdev->state.conn >= C_SYNC_SOURCE &&
 	    mdev->state.conn <= C_PAUSED_SYNC_T)
 		dp_flags |= DP_MAY_SET_IN_SYNC;

drivers/block/drbd/drbd_receiver.c

@@ -1753,6 +1753,18 @@ static int drbd_wait_peer_seq(struct drbd_conf *mdev, const u32 packet_seq)
 	return ret;
 }
 
+static unsigned long write_flags_to_bio(struct drbd_conf *mdev, u32 dpf)
+{
+	if (mdev->agreed_pro_version >= 95)
+		return  (dpf & DP_RW_SYNC ? REQ_SYNC : 0) |
+			(dpf & DP_UNPLUG ? REQ_UNPLUG : 0) |
+			(dpf & DP_FUA ? REQ_FUA : 0) |
+			(dpf & DP_FLUSH ? REQ_FUA : 0) |
+			(dpf & DP_DISCARD ? REQ_DISCARD : 0);
+	else
+		return dpf & DP_RW_SYNC ? (REQ_SYNC | REQ_UNPLUG) : 0;
+}
+
 /* mirrored write */
 static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned int data_size)
 {
@@ -1818,12 +1830,8 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 	spin_unlock(&mdev->epoch_lock);
 
 	dp_flags = be32_to_cpu(p->dp_flags);
-	if (dp_flags & DP_HARDBARRIER) {
-		dev_err(DEV, "ASSERT FAILED would have submitted barrier request\n");
-		/* rw |= REQ_HARDBARRIER; */
-	}
-	if (dp_flags & DP_RW_SYNC)
-		rw |= REQ_SYNC | REQ_UNPLUG;
+	rw |= write_flags_to_bio(mdev, dp_flags);
+
 	if (dp_flags & DP_MAY_SET_IN_SYNC)
 		e->flags |= EE_MAY_SET_IN_SYNC;