Hi,

在 2022/09/15 0:16, Logan Gunthorpe 写道:

On 2022-09-13 19:49, Yu Kuai wrote:

quoted

From: Yu Kuai <redacted>

Currently the nasty condition is wait_barrier() is hard to read. This
patch factor out the condition into a function.

There are no functional changes.

Signed-off-by: Yu Kuai <redacted>
---
  drivers/md/raid10.c | 56 ++++++++++++++++++++++++++-------------------
  1 file changed, 32 insertions(+), 24 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 64d6e4cd8a3a..56458a53043d 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c

@@ -957,44 +957,52 @@ static void lower_barrier(struct r10conf *conf)
  	wake_up(&conf->wait_barrier);
  }
  
+static bool stop_waiting_barrier(struct r10conf *conf)
+{
+	/* barrier is dropped */
+	if (!conf->barrier)
+		return true;
+
+	/*
+	 * If there are already pending requests (preventing the barrier from
+	 * rising completely), and the pre-process bio queue isn't empty, then
+	 * don't wait, as we need to empty that queue to get the nr_pending
+	 * count down.
+	 */
+	if (atomic_read(&conf->nr_pending)) {
+		struct bio_list *bio_list = current->bio_list;

I'd probably just put the bio_list declaration at the top of this
function, then the nested if statements are not necessary. The compiler
should be able to optimize the access just fine.

quoted

  	if (conf->barrier) {
-		struct bio_list *bio_list = current->bio_list;
-		conf->nr_waiting++;
-		/* Wait for the barrier to drop.
-		 * However if there are already pending
-		 * requests (preventing the barrier from
-		 * rising completely), and the
-		 * pre-process bio queue isn't empty,
-		 * then don't wait, as we need to empty
-		 * that queue to get the nr_pending
-		 * count down.
-		 */
  		/* Return false when nowait flag is set */
  		if (nowait) {
  			ret = false;
  		} else {
+			conf->nr_waiting++;

Technically speaking, I think moving nr_waiting counts as a functional
change. As best as I can see it is correct, but it should probably be at
least mentioned in the commit message, or maybe done as a separate
commit with it's own justification. That way if it causes problems down
the road, a bisect will make the issue clearer.

Thanks for your advice, I just think increase and decrease nr_waiting in
the case 'nowait' is pointless, and I move it incidentally.

I'll post a separate clean up patch to do that.

Paul, can I still add your Acked-by for this patch?

Thanks,
Kuai

Thanks,

Logan
.