commit 5d6b9255ccf3f190ad1f2fe0c3fbfba718b33175
Author: Andriy Gapon <avg@icyb.net.ua>
Date:   Mon Feb 6 20:57:10 2017 +0200

    l2arc: try to fix write size calculation broken by compressed arc

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
index bd2204737af4d..c46ba94f4680c 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
@@ -6911,7 +6911,7 @@ top:
 		}
 
 		if (!all && HDR_HAS_L2HDR(hdr) &&
-		    (hdr->b_l2hdr.b_daddr > taddr ||
+		    (hdr->b_l2hdr.b_daddr >= taddr ||
 		    hdr->b_l2hdr.b_daddr < dev->l2ad_hand)) {
 			/*
 			 * We've evicted to the target address,
@@ -7045,7 +7045,22 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 				continue;
 			}
 
-			if ((write_asize + HDR_GET_LSIZE(hdr)) > target_sz) {
+			/*
+			 * We rely on the L1 portion of the header below, so
+			 * it's invalid for this header to have been evicted out
+			 * of the ghost cache, prior to being written out. The
+			 * ARC_FLAG_L2_WRITING bit ensures this won't happen.
+			 */
+			ASSERT(HDR_HAS_L1HDR(hdr));
+
+			ASSERT3U(HDR_GET_PSIZE(hdr), >, 0);
+			ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
+			ASSERT3U(arc_hdr_size(hdr), >, 0);
+			uint64_t size = arc_hdr_size(hdr);
+			uint64_t asize = vdev_psize_to_asize(dev->l2ad_vdev,
+			    size);
+
+			if ((write_psize + asize) > target_sz) {
 				full = B_TRUE;
 				mutex_exit(hash_lock);
 				ARCSTAT_BUMP(arcstat_l2_write_full);
@@ -7080,21 +7095,6 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 			list_insert_head(&dev->l2ad_buflist, hdr);
 			mutex_exit(&dev->l2ad_mtx);
 
-			/*
-			 * We rely on the L1 portion of the header below, so
-			 * it's invalid for this header to have been evicted out
-			 * of the ghost cache, prior to being written out. The
-			 * ARC_FLAG_L2_WRITING bit ensures this won't happen.
-			 */
-			ASSERT(HDR_HAS_L1HDR(hdr));
-
-			ASSERT3U(HDR_GET_PSIZE(hdr), >, 0);
-			ASSERT3P(hdr->b_l1hdr.b_pdata, !=, NULL);
-			ASSERT3U(arc_hdr_size(hdr), >, 0);
-			uint64_t size = arc_hdr_size(hdr);
-			uint64_t asize = vdev_psize_to_asize(dev->l2ad_vdev,
-			    size);
-
 			(void) refcount_add_many(&dev->l2ad_alloc, size, hdr);
 
 			/*
@@ -7156,7 +7156,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 		return (0);
 	}
 
-	ASSERT3U(write_asize, <=, target_sz);
+	ASSERT3U(write_psize, <=, target_sz);
 	ARCSTAT_BUMP(arcstat_l2_writes_sent);
 	ARCSTAT_INCR(arcstat_l2_write_bytes, write_asize);
 	ARCSTAT_INCR(arcstat_l2_size, write_sz);