Re: [PATCH -next v4 3/6] nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed

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在 2022/05/28 10:12, Yu Kuai 写道:
Otherwise io will hung because request will only be completed if the
cmd has the flag 'NBD_CMD_INFLIGHT'.

Fixes: 07175cb1baf4 ("nbd: make sure request completion won't concurrent")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
  drivers/block/nbd.c | 13 +++++++++----
  1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 2ee1e376d5c4..a673a97b9b6b 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -403,13 +403,14 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
  	if (!mutex_trylock(&cmd->lock))
  		return BLK_EH_RESET_TIMER;
- if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) {
+	if (!test_bit(NBD_CMD_INFLIGHT, &cmd->flags)) {
  		mutex_unlock(&cmd->lock);
  		return BLK_EH_DONE;
  	}
if (!refcount_inc_not_zero(&nbd->config_refs)) {
  		cmd->status = BLK_STS_TIMEOUT;
+		__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
  		mutex_unlock(&cmd->lock);
  		goto done;
  	}
@@ -478,6 +479,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
  	dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n");
  	set_bit(NBD_RT_TIMEDOUT, &config->runtime_flags);
  	cmd->status = BLK_STS_IOERR;
+	__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
  	mutex_unlock(&cmd->lock);
  	sock_shutdown(nbd);
  	nbd_config_put(nbd);
@@ -745,7 +747,7 @@ static struct nbd_cmd *nbd_handle_reply(struct nbd_device *nbd, int index,
  	cmd = blk_mq_rq_to_pdu(req);
mutex_lock(&cmd->lock);
-	if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) {
+	if (!test_bit(NBD_CMD_INFLIGHT, &cmd->flags)) {
  		dev_err(disk_to_dev(nbd->disk), "Suspicious reply %d (status %u flags %lu)",
  			tag, cmd->status, cmd->flags);
  		ret = -ENOENT;
@@ -813,6 +815,10 @@ static struct nbd_cmd *nbd_handle_reply(struct nbd_device *nbd, int index,
  	}
  out:
  	trace_nbd_payload_received(req, handle);
+	if (!ret && likely(!blk_should_fake_timeout(req->q)))
+		__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
+	else if (!ret)
+		ret = -ENOENT;

Hi, Josef

Do you prefer to move blk_should_fake_time() into nbd_handle_reply()
like this ? Code is a litter simplier.

Thanks,
Kuai
  	mutex_unlock(&cmd->lock);
  	return ret ? ERR_PTR(ret) : cmd;
  }
@@ -854,8 +860,7 @@ static void recv_work(struct work_struct *work)
  		}
rq = blk_mq_rq_from_pdu(cmd);
-		if (likely(!blk_should_fake_timeout(rq->q)))
-			blk_mq_complete_request(rq);
+		blk_mq_complete_request(rq);
  		percpu_ref_put(&q->q_usage_counter);
  	}



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