Fix suspend Godfather I/Os io_reexecute bits

After resuming a pool the godfather zio could have both the
ZIO_REEXECUTE_NOW and ZIO_REEXECUTE_SUSPEND bits set.  This
can occur if some child zios set ZIO_REEXECUTE_NOW while
other set ZIO_REEXECUTE_SUSPEND.  The godfather zio can
inherit both flags in zio_notify_parent().

The child zios which assigned the ZIO_REEXECUTE_SUSPEND flag
will be removed from the godfather's child list and added to
the spa->spa_suspend_zio_root child list.   While child zios
with the ZIO_REEXECUTE_NOW bit set remain being monitored
by the godfather zio.

When the godfather zio executes zio_done() the presence of
the ZIO_REEXECUTE_SUSPEND bit results in all io_reexecute
being cleared.  These child zios will then not be re-executed
and instead will be destroyed and lost.

The most straight forward way to address this situation is
to only clear the ZIO_REEXECUTE_SUSPEND bit and leave the
ZIO_REEXECUTE_NOW bit set.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: yuxiang <[email protected]>

module/zfs/zio.c

@@ -3885,7 +3885,7 @@ zio_done(zio_t *zio)
 	 */
 	if ((zio->io_flags & ZIO_FLAG_GODFATHER) &&
 	    (zio->io_reexecute & ZIO_REEXECUTE_SUSPEND))
-		zio->io_reexecute = 0;
+		zio->io_reexecute &= ~ZIO_REEXECUTE_SUSPEND;
 
 	if (zio->io_reexecute) {
 		/*