TRIM the whole vdev on create/add/attach.

With this patch, ZFS will attempt to TRIM the whole vdev in the
following cases:

 - zpool create, zpool add, zpool attach any vdev
 - zpool import spare and L2ARC devices

We do this to make sure we start from a "clean state". This way, the
physical device knows that all the data it held before it was added to
the pool is now obsolete. This is similar to what mke2fs does.

include/sys/zio.h

@@ -516,7 +516,8 @@ extern int zio_alloc_zil(spa_t *spa, uint64_t txg, blkptr_t *new_bp,
     blkptr_t *old_bp, uint64_t size, boolean_t use_slog);
 extern void zio_free_zil(spa_t *spa, uint64_t txg, blkptr_t *bp);
 extern void zio_flush(zio_t *zio, vdev_t *vd);
-extern void zio_trim(zio_t *zio, vdev_t *vd, uint64_t offset, uint64_t size);
+extern zio_t *zio_trim(zio_t *zio, spa_t *spa, vdev_t *vd,
+    uint64_t offset, uint64_t size);
 extern void zio_shrink(zio_t *zio, uint64_t size);
 
 extern int zio_wait(zio_t *zio);

module/zfs/trim_map.c

@@ -392,7 +392,8 @@ trim_map_vdev_commit(spa_t *spa, zio_t *zio, vdev_t *vd)
 		list_remove(&tm->tm_head, ts);
 		avl_remove(&tm->tm_queued_frees, ts);
 		avl_add(&tm->tm_inflight_frees, ts);
-		zio_trim(zio, vd, ts->ts_start, ts->ts_end - ts->ts_start);
+		zio_nowait(zio_trim(zio, spa, vd, ts->ts_start,
+		    ts->ts_end - ts->ts_start));
 	}
 	mutex_exit(&tm->tm_lock);
 }

module/zfs/vdev_label.c

@@ -688,6 +688,16 @@ vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
 			return (0);
 		ASSERT(reason == VDEV_LABEL_REPLACE);
 	}
+
+	/*
+	 * TRIM the whole thing so that we start with a clean slate.
+	 * It's just an optimization, so we don't care if it fails.
+	 * Don't TRIM if removing so that we don't interfere with zpool
+	 * disaster recovery.
+	 */
+	if (reason == VDEV_LABEL_CREATE || reason == VDEV_LABEL_SPARE
+	    || reason == VDEV_LABEL_L2CACHE)
+		zio_wait(zio_trim(NULL, spa, vd, 0, vd->vdev_psize));
 
 	/*
 	 * Initialize its label.

module/zfs/zio.c

@@ -981,15 +981,15 @@ zio_flush(zio_t *zio, vdev_t *vd)
 	    ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY));
 }
 
-void
-zio_trim(zio_t *zio, vdev_t *vd, uint64_t offset, uint64_t size)
+zio_t *
+zio_trim(zio_t *zio, spa_t *spa, vdev_t *vd, uint64_t offset, uint64_t size)
 {
 
 	ASSERT(vd->vdev_ops->vdev_op_leaf);
 
-	zio_nowait(zio_ioctl(zio, zio->io_spa, vd, DKIOCTRIM, offset, size,
+	return zio_ioctl(zio, spa, vd, DKIOCTRIM, offset, size,
 	    NULL, NULL, ZIO_PRIORITY_TRIM,
-	    ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY));
+	    ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY);
 }
 
 void