diff mbox

rqdm: fix stall when ->map_rq returns DM_MAPIO_REQUEUE

Message ID 4B691FAF.6030509@ct.jp.nec.com (mailing list archive)
State Accepted, archived
Delegated to: Alasdair Kergon
Headers show

Commit Message

Kiyoshi Ueda Feb. 3, 2010, 7:03 a.m. UTC
None
diff mbox

Patch

Index: 2.6.33-rc6/drivers/md/dm.c
===================================================================
--- 2.6.33-rc6.orig/drivers/md/dm.c
+++ 2.6.33-rc6/drivers/md/dm.c
@@ -1595,10 +1595,15 @@  static int dm_prep_fn(struct request_que
 	return BLKPREP_OK;
 }
 
-static void map_request(struct dm_target *ti, struct request *clone,
-			struct mapped_device *md)
+/*
+ * Returns:
+ * 0  : the request has been processed (not requeued)
+ * !0 : the request has been requeued
+ */
+static int map_request(struct dm_target *ti, struct request *clone,
+		       struct mapped_device *md)
 {
-	int r;
+	int r, requeued = 0;
 	struct dm_rq_target_io *tio = clone->end_io_data;
 
 	/*
@@ -1625,6 +1630,7 @@  static void map_request(struct dm_target
 	case DM_MAPIO_REQUEUE:
 		/* The target wants to requeue the I/O */
 		dm_requeue_unmapped_request(clone);
+		requeued = 1;
 		break;
 	default:
 		if (r > 0) {
@@ -1636,6 +1642,8 @@  static void map_request(struct dm_target
 		dm_kill_unmapped_request(clone, r);
 		break;
 	}
+
+	return requeued;
 }
 
 /*
@@ -1677,12 +1685,17 @@  static void dm_request_fn(struct request
 		atomic_inc(&md->pending[rq_data_dir(clone)]);
 
 		spin_unlock(q->queue_lock);
-		map_request(ti, clone, md);
+		if (map_request(ti, clone, md))
+			goto requeued;
+
 		spin_lock_irq(q->queue_lock);
 	}
 
 	goto out;
 
+requeued:
+	spin_lock_irq(q->queue_lock);
+
 plug_and_out:
 	if (!elv_queue_empty(q))
 		/* Some requests still remain, retry later */