linux-kernel - [PATCH -next v2 3/6] nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed

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Message-ID: <20220518122618.1702997-4-yukuai3@huawei.com>
Date:   Wed, 18 May 2022 20:26:15 +0800
From:   Yu Kuai <yukuai3@...wei.com>
To:     <josef@...icpanda.com>, <axboe@...nel.dk>, <ming.lei@...hat.com>
CC:     <linux-block@...r.kernel.org>, <nbd@...er.debian.org>,
        <linux-kernel@...r.kernel.org>, <yukuai3@...wei.com>,
        <yi.zhang@...wei.com>
Subject: [PATCH -next v2 3/6] nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed

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@...wei.com>
---
 drivers/block/nbd.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 2ee1e376d5c4..a0d0910dae2a 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;
@@ -854,8 +856,16 @@ 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);
+		if (likely(!blk_should_fake_timeout(rq->q))) {
+			bool complete;
+
+			mutex_lock(&cmd->lock);
+			complete = __test_and_clear_bit(NBD_CMD_INFLIGHT,
+							&cmd->flags);
+			mutex_unlock(&cmd->lock);
+			if (complete)
+				blk_mq_complete_request(rq);
+		}
 		percpu_ref_put(&q->q_usage_counter);
 	}
 
-- 
2.31.1