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. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc. Closes #15233
openzfs · Sep 2, 2023 · 79ac1b2 · 79ac1b2
1 parent 7dc2baa
commit 79ac1b2
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/module/zfs/zil.c b/module/zfs/zil.c
@@ -1924,10 +1924,10 @@ 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,