1 files changed, 65 insertions, 19 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 42439a4c1c5..810cf831edd 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2471,26 +2471,67 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
 				struct stripe_head_state *s, int disks)
 {
 	set_bit(STRIPE_HANDLE, &sh->state);
-	if (s->failed == 0) {
-		BUG_ON(s->uptodate != disks);
-		compute_parity5(sh, CHECK_PARITY);
-		s->uptodate--;
-		if (page_is_zero(sh->dev[sh->pd_idx].page)) {
-			/* parity is correct (on disc, not in buffer any more)
-			 */
-			set_bit(STRIPE_INSYNC, &sh->state);
-		} else {
-			conf->mddev->resync_mismatches += STRIPE_SECTORS;
-			if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
-				/* don't try to repair!! */
+	/* Take one of the following actions:
+	 * 1/ start a check parity operation if (uptodate == disks)
+	 * 2/ finish a check parity operation and act on the result
+	 * 3/ skip to the writeback section if we previously
+	 *    initiated a recovery operation
+	 */
+	if (s->failed == 0 &&
+	    !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
+		if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
+			BUG_ON(s->uptodate != disks);
+			clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
+			sh->ops.count++;
+			s->uptodate--;
+		} else if (
+		       test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) {
+			clear_bit(STRIPE_OP_CHECK, &sh->ops.ack);
+			clear_bit(STRIPE_OP_CHECK, &sh->ops.pending);
+
+			if (sh->ops.zero_sum_result == 0)
+				/* parity is correct (on disc,
+				 * not in buffer any more)
+				 */
 				set_bit(STRIPE_INSYNC, &sh->state);
 			else {
-				compute_block(sh, sh->pd_idx);
-				s->uptodate++;
+				conf->mddev->resync_mismatches +=
+					STRIPE_SECTORS;
+				if (test_bit(
+				     MD_RECOVERY_CHECK, &conf->mddev->recovery))
+					/* don't try to repair!! */
+					set_bit(STRIPE_INSYNC, &sh->state);
+				else {
+					set_bit(STRIPE_OP_COMPUTE_BLK,
+						&sh->ops.pending);
+					set_bit(STRIPE_OP_MOD_REPAIR_PD,
+						&sh->ops.pending);
+					set_bit(R5_Wantcompute,
+						&sh->dev[sh->pd_idx].flags);
+					sh->ops.target = sh->pd_idx;
+					sh->ops.count++;
+					s->uptodate++;
+				}
 			}
 		}
 	}
-	if (!test_bit(STRIPE_INSYNC, &sh->state)) {
+
+	/* check if we can clear a parity disk reconstruct */
+	if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
+		test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
+
+		clear_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending);
+		clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
+		clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
+		clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
+	}
+
+	/* Wait for check parity and compute block operations to complete
+	 * before write-back
+	 */
+	if (!test_bit(STRIPE_INSYNC, &sh->state) &&
+		!test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
+		!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
 		struct r5dev *dev;
 		/* either failed parity check, or recovery is happening */
 		if (s->failed == 0)
@@ -2855,12 +2896,17 @@ static void handle_stripe5(struct stripe_head *sh)
 		handle_issuing_new_write_requests5(conf, sh, &s, disks);
 
 	/* maybe we need to check and possibly fix the parity for this stripe
-	 * Any reads will already have been scheduled, so we just see if enough data
-	 * is available
+	 * Any reads will already have been scheduled, so we just see if enough
+	 * data is available.  The parity check is held off while parity
+	 * dependent operations are in flight.
 	 */
-	if (s.syncing && s.locked == 0 &&
-	    !test_bit(STRIPE_INSYNC, &sh->state))
+	if ((s.syncing && s.locked == 0 &&
+	     !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
+	     !test_bit(STRIPE_INSYNC, &sh->state)) ||
+	      test_bit(STRIPE_OP_CHECK, &sh->ops.pending) ||
+	      test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending))
 		handle_parity_checks5(conf, sh, &s, disks);
+
 	if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
 		md_done_sync(conf->mddev, STRIPE_SECTORS,1);
 		clear_bit(STRIPE_SYNCING, &sh->state);