ZIL: Change ZIOs issue order.

In zil_lwb_write_issue(), after issuing lwb_root_zio/lwb_write_zio, we have no right to access lwb->lwb_child_zio. If it was not there, the first two ZIOs may have already completed and freed the lwb. ZIOs issue in opposite order from children to parent should keep the lwb valid till the end, since the lwb can be freed only after lwb_root_zio completion callback. Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc.
openzfs · Sep 1, 2023 · db1d254 · db1d254
1 parent eda3fcd
commit db1d254
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/module/zfs/zil.c b/module/zfs/zil.c
@@ -1929,10 +1929,10 @@ zil_lwb_write_issue(zilog_t *zilog, lwb_t *lwb)
 		    BP_GET_LSIZE(&lwb->lwb_blk));
 	}
 	lwb->lwb_issued_timestamp = gethrtime();
-	zio_nowait(lwb->lwb_root_zio);
-	zio_nowait(lwb->lwb_write_zio);
 	if (lwb->lwb_child_zio)
 		zio_nowait(lwb->lwb_child_zio);
+	zio_nowait(lwb->lwb_write_zio);
+	zio_nowait(lwb->lwb_root_zio);
 
 	/*
 	 * If nlwb was ready when we gave it the block pointer,