Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
===================================================================
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c	(revision 232157)
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c	(working copy)
@@ -143,8 +143,10 @@
 extern uint64_t zfs_write_limit_max;
 extern kmutex_t zfs_write_limit_lock;
 
+#ifdef sun
 #define	ARC_REDUCE_DNLC_PERCENT	3
 uint_t arc_reduce_dnlc_percent = ARC_REDUCE_DNLC_PERCENT;
+#endif
 
 typedef enum arc_reclaim_strategy {
 	ARC_RECLAIM_AGGR,		/* Aggressive reclaim strategy */
@@ -2106,6 +2108,26 @@
 }
 
 static void
+arc_adjust_meta(int64_t adjustment)
+{
+	int64_t delta;
+
+	if (adjustment > 0 && arc_mru->arcs_lsize[ARC_BUFC_METADATA] > 0) {
+		delta = MIN(arc_mru->arcs_lsize[ARC_BUFC_METADATA], adjustment);
+		(void) arc_evict(arc_mru, 0, delta, FALSE,
+		    ARC_BUFC_METADATA);
+		adjustment -= delta;
+	}
+
+	if (adjustment > 0 && arc_mfu->arcs_lsize[ARC_BUFC_METADATA] > 0) {
+		int64_t delta = MIN(adjustment,
+		    arc_mfu->arcs_lsize[ARC_BUFC_METADATA]);
+		(void) arc_evict(arc_mfu, 0, delta, FALSE,
+		    ARC_BUFC_METADATA);
+	}
+}
+
+static void
 arc_do_user_evicts(void)
 {
 	static arc_buf_t *tmp_arc_eviction_list;
@@ -2292,6 +2314,7 @@
 	kmem_cache_t		*prev_data_cache = NULL;
 
 #ifdef _KERNEL
+#ifdef sun
 	if (arc_meta_used >= arc_meta_limit) {
 		/*
 		 * We are exceeding our meta-data cache limit.
@@ -2299,6 +2322,7 @@
 		 */
 		dnlc_reduce_cache((void *)(uintptr_t)arc_reduce_dnlc_percent);
 	}
+#endif
 #if defined(__i386)
 	/*
 	 * Reclaim unused memory from all kmem caches.
@@ -2334,6 +2358,7 @@
 	clock_t			growtime = 0;
 	arc_reclaim_strategy_t	last_reclaim = ARC_RECLAIM_CONS;
 	callb_cpr_t		cpr;
+	int64_t			prune;
 
 	CALLB_CPR_INIT(&cpr, &arc_reclaim_thr_lock, callb_generic_cpr, FTAG);
 
@@ -2372,6 +2397,11 @@
 			arc_no_grow = FALSE;
 		}
 
+		prune = (int64_t)arc_meta_used - (int64_t)arc_meta_limit;
+		/* Keep meta data usage within limits */
+		if (prune > 0)
+			arc_adjust_meta(prune);
+
 		arc_adjust();
 
 		if (arc_eviction_list != NULL)
@@ -2567,6 +2597,11 @@
 		if (type == ARC_BUFC_METADATA) {
 			buf->b_data = zio_buf_alloc(size);
 			arc_space_consume(size, ARC_SPACE_DATA);
+			/*
+			 * If we are unable to recycle an existing meta buffer
+			 * signal the reclaim thread.
+			 */
+			cv_signal(&arc_reclaim_thr_cv);
 		} else {
 			ASSERT(type == ARC_BUFC_DATA);
 			buf->b_data = zio_data_buf_alloc(size);