[PATCH -next v3 3/6] nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed

Yu Kuai
2022-05-21T07:24:33Z

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@huawei.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