Fix zfs_vdev_aggregation_limit bounds checking

Update the bounds checking for zfs_vdev_aggregation_limit so that it has a floor of zero and a maximum value of the supported block size for the pool. Additionally add an early return when zfs_vdev_aggregation_limit equals zero to disable aggregation. For very fast solid state or memory devices it may be more expensive to perform the aggregation than to issue the IO immediately. Signed-off-by: Brian Behlendorf <[email protected]> Requires-spl: refs/pull/515/head
openzfs · Dec 18, 2015 · da42296 · da42296
1 parent 74ee48b
commit da42296
Showing 1 changed file with 5 additions and 8 deletions.
diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c
@@ -504,15 +504,12 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
 	enum zio_flag flags = zio->io_flags & ZIO_FLAG_AGG_INHERIT;
 	void *buf;
 
-	if (zio->io_flags & ZIO_FLAG_DONT_AGGREGATE)
-		return (NULL);
+	zfs_vdev_aggregation_limit = MAX(MIN(zfs_vdev_aggregation_limit,
+	    spa_maxblocksize(vq->vq_vdev->vdev_spa)), 0);
 
-	/*
-	 * Prevent users from setting the zfs_vdev_aggregation_limit
-	 * tuning larger than SPA_MAXBLOCKSIZE.
-	 */
-	zfs_vdev_aggregation_limit =
-	    MIN(zfs_vdev_aggregation_limit, SPA_MAXBLOCKSIZE);
+	if (zio->io_flags & ZIO_FLAG_DONT_AGGREGATE ||
+	    zfs_vdev_aggregation_limit == 0)
+		return (NULL);
 
 	first = last = zio;