1 files changed, 33 insertions, 10 deletions

diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index 9305bd894..860572336 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -3149,9 +3149,9 @@ vdev_dtl_should_excise(vdev_t *vd, boolean_t rebuild_done)
  * Reassess DTLs after a config change or scrub completion. If txg == 0 no
  * write operations will be issued to the pool.
  */
-void
-vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg,
-    boolean_t scrub_done, boolean_t rebuild_done)
+static void
+vdev_dtl_reassess_impl(vdev_t *vd, uint64_t txg, uint64_t scrub_txg,
+    boolean_t scrub_done, boolean_t rebuild_done, boolean_t faulting)
 {
 	spa_t *spa = vd->vdev_spa;
 	avl_tree_t reftree;
@@ -3160,8 +3160,8 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg,
 	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
 
 	for (int c = 0; c < vd->vdev_children; c++)
-		vdev_dtl_reassess(vd->vdev_child[c], txg,
-		    scrub_txg, scrub_done, rebuild_done);
+		vdev_dtl_reassess_impl(vd->vdev_child[c], txg,
+		    scrub_txg, scrub_done, rebuild_done, faulting);
 
 	if (vd == spa->spa_root_vdev || !vdev_is_concrete(vd) || vd->vdev_aux)
 		return;
@@ -3255,11 +3255,21 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg,
 		if (scrub_done)
 			range_tree_vacate(vd->vdev_dtl[DTL_SCRUB], NULL, NULL);
 		range_tree_vacate(vd->vdev_dtl[DTL_OUTAGE], NULL, NULL);
-		if (!vdev_readable(vd))
+
+		/*
+		 * For the faulting case, treat members of a replacing vdev
+		 * as if they are not available. It's more likely than not that
+		 * a vdev in a replacing vdev could encounter read errors so
+		 * treat it as not being able to contribute.
+		 */
+		if (!vdev_readable(vd) ||
+		    (faulting && vd->vdev_parent != NULL &&
+		    vd->vdev_parent->vdev_ops == &vdev_replacing_ops)) {
 			range_tree_add(vd->vdev_dtl[DTL_OUTAGE], 0, -1ULL);
-		else
+		} else {
 			range_tree_walk(vd->vdev_dtl[DTL_MISSING],
 			    range_tree_add, vd->vdev_dtl[DTL_OUTAGE]);
+		}
 
 		/*
 		 * If the vdev was resilvering or rebuilding and no longer
@@ -3321,6 +3331,14 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg,
 	}
 }
 
+void
+vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg,
+    boolean_t scrub_done, boolean_t rebuild_done)
+{
+	return (vdev_dtl_reassess_impl(vd, txg, scrub_txg, scrub_done,
+	    rebuild_done, B_FALSE));
+}
+
 /*
  * Iterate over all the vdevs except spare, and post kobj events
  */
@@ -3548,7 +3566,11 @@ vdev_dtl_sync(vdev_t *vd, uint64_t txg)
 }
 
 /*
- * Determine whether the specified vdev can be offlined/detached/removed
+ * Determine whether the specified vdev can be
+ * - offlined
+ * - detached
+ * - removed
+ * - faulted
  * without losing data.
  */
 boolean_t
@@ -3558,6 +3580,7 @@ vdev_dtl_required(vdev_t *vd)
 	vdev_t *tvd = vd->vdev_top;
 	uint8_t cant_read = vd->vdev_cant_read;
 	boolean_t required;
+	boolean_t faulting = vd->vdev_state == VDEV_STATE_FAULTED;
 
 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
 
@@ -3570,10 +3593,10 @@ vdev_dtl_required(vdev_t *vd)
 	 * If not, we can safely offline/detach/remove the device.
 	 */
 	vd->vdev_cant_read = B_TRUE;
-	vdev_dtl_reassess(tvd, 0, 0, B_FALSE, B_FALSE);
+	vdev_dtl_reassess_impl(tvd, 0, 0, B_FALSE, B_FALSE, faulting);
 	required = !vdev_dtl_empty(tvd, DTL_OUTAGE);
 	vd->vdev_cant_read = cant_read;
-	vdev_dtl_reassess(tvd, 0, 0, B_FALSE, B_FALSE);
+	vdev_dtl_reassess_impl(tvd, 0, 0, B_FALSE, B_FALSE, faulting);
 
 	if (!required && zio_injection_enabled) {
 		required = !!zio_handle_device_injection(vd, NULL,