gmirror: Release pending regular requests when synchronization stops.

Normally gmirror allows colliding requests to proceed whenever a
synchronization request completes and advances to the next offset. However
if an I/O request collides with one of the final g_mirror_syncreqs, nothing
releases it once synchronization completes, resulting in an apparent I/O
hang. The same problem can occur if synchronization is aborted by an
I/O error. Therefore, be sure to requeue pending requests when
mirror synchronization is stopped for any reason.

While here, remove some dead code from g_mirror_regular_release().

MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon

1 files changed, 1 insertions, 7 deletions

diff --git a/sys/geom/mirror/g_mirror.c b/sys/geom/mirror/g_mirror.c
index 308e711fcc1d..4018f8d6d172 100644
--- a/sys/geom/mirror/g_mirror.c
+++ b/sys/geom/mirror/g_mirror.c
@@ -1252,13 +1252,6 @@ g_mirror_regular_release(struct g_mirror_softc *sc)
 		G_MIRROR_LOGREQ(2, bp, "Releasing delayed request (%p).", bp);
 		mtx_lock(&sc->sc_queue_mtx);
 		bioq_insert_head(&sc->sc_queue, bp);
-#if 0
-		/*
-		 * wakeup() is not needed, because this function is called from
-		 * the worker thread.
-		 */
-		wakeup(&sc->sc_queue);
-#endif
 		mtx_unlock(&sc->sc_queue_mtx);
 	}
 }
@@ -2065,6 +2058,7 @@ g_mirror_sync_stop(struct g_mirror_disk *disk, int type)
 		G_MIRROR_DEBUG(0, "Device %s: rebuilding provider %s stopped.",
 		    sc->sc_name, g_mirror_get_diskname(disk));
 	}
+	g_mirror_regular_release(sc);
 	free(disk->d_sync.ds_bios, M_MIRROR);
 	disk->d_sync.ds_bios = NULL;
 	cp = disk->d_sync.ds_consumer;