drbd: Do not call generic_make_request() while holding req_lock

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

drivers/block/drbd/drbd_req.c

@@ -31,6 +31,8 @@
 #include "drbd_req.h"
 
 
+static bool drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int size);
+
 /* Update disk stats at start of I/O request */
 static void _drbd_start_io_acct(struct drbd_conf *mdev, struct drbd_request *req, struct bio *bio)
 {
@@ -558,20 +560,21 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 		/* assert something? */
 		if (req->rq_state & RQ_NET_PENDING)
 			dec_ap_pending(mdev);
+
+		p = !(req->rq_state & RQ_WRITE) && req->rq_state & RQ_NET_PENDING;
+
 		req->rq_state &= ~(RQ_NET_OK|RQ_NET_PENDING);
 		req->rq_state |= RQ_NET_DONE;
 		if (req->rq_state & RQ_NET_SENT && req->rq_state & RQ_WRITE)
 			atomic_sub(req->i.size >> 9, &mdev->ap_in_flight);
 
-		if (!(req->rq_state & RQ_WRITE) &&
-		    mdev->state.disk == D_UP_TO_DATE &&
-		    !IS_ERR_OR_NULL(req->private_bio))
-			goto goto_read_retry_local;
-
 		/* if it is still queued, we may not complete it here.
 		 * it will be canceled soon. */
-		if (!(req->rq_state & RQ_NET_QUEUED))
+		if (!(req->rq_state & RQ_NET_QUEUED)) {
+			if (p)
+				goto goto_read_retry_local;
 			_req_may_be_done(req, m); /* Allowed while state.susp */
+		}
 		break;
 
 	case WRITE_ACKED_BY_PEER_AND_SIS:
@@ -631,19 +634,24 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 
 		req->rq_state |= RQ_NET_DONE;
 
-		if (!(req->rq_state & RQ_WRITE) &&
-		    mdev->state.disk == D_UP_TO_DATE &&
-		    !IS_ERR_OR_NULL(req->private_bio))
+		if (!(req->rq_state & RQ_WRITE))
 			goto goto_read_retry_local;
 
 		_req_may_be_done_not_susp(req, m);
 		/* else: done by HANDED_OVER_TO_NETWORK */
 		break;
 
 	goto_read_retry_local:
+		if (!drbd_may_do_local_read(mdev, req->i.sector, req->i.size)) {
+			_req_may_be_done_not_susp(req, m);
+			break;
+		}
+		D_ASSERT(!(req->rq_state & RQ_LOCAL_PENDING));
 		req->rq_state |= RQ_LOCAL_PENDING;
-		req->private_bio->bi_bdev = mdev->ldev->backing_bdev;
-		generic_make_request(req->private_bio);
+
+		get_ldev(mdev);
+		req->w.cb = w_restart_disk_io;
+		drbd_queue_work(&mdev->tconn->data.work, &req->w);
 		break;
 
 	case FAIL_FROZEN_DISK_IO:
@@ -706,11 +714,6 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 		dec_ap_pending(mdev);
 		req->rq_state &= ~RQ_NET_PENDING;
 		req->rq_state |= (RQ_NET_OK|RQ_NET_DONE);
-		if (!IS_ERR_OR_NULL(req->private_bio)) {
-			bio_put(req->private_bio);
-			req->private_bio = NULL;
-			put_ldev(mdev);
-		}
 		_req_may_be_done_not_susp(req, m);
 		break;
 	};
@@ -840,7 +843,8 @@ int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long s
 	} else {
 		/* READ || READA */
 		if (local) {
-			if (!drbd_may_do_local_read(mdev, sector, size)) {
+			if (!drbd_may_do_local_read(mdev, sector, size) ||
+			    remote_due_to_read_balancing(mdev, sector)) {
 				/* we could kick the syncer to
 				 * sync this extent asap, wait for
 				 * it, then continue locally.
@@ -850,10 +854,6 @@ int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long s
 				bio_put(req->private_bio);
 				req->private_bio = NULL;
 				put_ldev(mdev);
-			} else if (remote_due_to_read_balancing(mdev, sector)) {
-				/* Keep the private bio in case we need it
-				   for a local retry */
-				local = 0;
 			}
 		}
 		remote = !local && mdev->state.pdsk >= D_UP_TO_DATE;
@@ -1081,7 +1081,7 @@ int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long s
 	if (req->rq_state & RQ_IN_ACT_LOG)
 		drbd_al_complete_io(mdev, &req->i);
 fail_and_free_req:
-	if (!IS_ERR_OR_NULL(req->private_bio)) {
+	if (local) {
 		bio_put(req->private_bio);
 		req->private_bio = NULL;
 		put_ldev(mdev);