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nbd: don't requeue the same request twice.

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We can race with the snd timeout and the per-request timeout and end up
requeuing the same request twice.  We can't use the send_complete
completion to tell if everything is ok because we hold the tx_lock
during send, so the timeout stuff will block waiting to mark the socket
dead, and we could be marked complete and still requeue.  Instead add a
flag to the socket so we know whether we've been requeued yet.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Josef Bacik 2018-07-16 12:11:34 -04:00 committed by Jens Axboe
parent 70dbcc2254
commit d7d94d48a2
1 changed files with 18 additions and 3 deletions
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21
drivers/block/nbd.c
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@ -112,12 +112,15 @@ struct nbd_device {
struct task_struct *task_setup;
};
#define NBD_CMD_REQUEUED 1
struct nbd_cmd {
struct nbd_device *nbd;
int index;
int cookie;
struct completion send_complete;
blk_status_t status;
unsigned long flags;
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
@ -146,6 +149,14 @@ static inline struct device *nbd_to_dev(struct nbd_device *nbd)
return disk_to_dev(nbd->disk);
}
static void nbd_requeue_cmd(struct nbd_cmd *cmd)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
blk_mq_requeue_request(req, true);
}
static const char *nbdcmd_to_ascii(int cmd)
{
switch (cmd) {
@ -343,7 +354,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
}
blk_mq_requeue_request(req, true);
nbd_requeue_cmd(cmd);
nbd_config_put(nbd);
return BLK_EH_DONE;
}
@ -500,6 +511,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
nsock->pending = req;
nsock->sent = sent;
}
set_bit(NBD_CMD_REQUEUED, &cmd->flags);
return BLK_STS_RESOURCE;
}
dev_err_ratelimited(disk_to_dev(nbd->disk),
@ -541,6 +553,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
*/
nsock->pending = req;
nsock->sent = sent;
set_bit(NBD_CMD_REQUEUED, &cmd->flags);
return BLK_STS_RESOURCE;
}
dev_err(disk_to_dev(nbd->disk),
@ -805,7 +818,7 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
*/
blk_mq_start_request(req);
if (unlikely(nsock->pending && nsock->pending != req)) {
blk_mq_requeue_request(req, true);
nbd_requeue_cmd(cmd);
ret = 0;
goto out;
}
@ -818,7 +831,7 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Request send failed, requeueing\n");
nbd_mark_nsock_dead(nbd, nsock, 1);
blk_mq_requeue_request(req, true);
nbd_requeue_cmd(cmd);
ret = 0;
}
out:
@ -843,6 +856,7 @@ static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
* done sending everything over the wire.
*/
init_completion(&cmd->send_complete);
clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
/* We can be called directly from the user space process, which means we
* could possibly have signals pending so our sendmsg will fail. In
@ -1460,6 +1474,7 @@ static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
cmd->nbd = set->driver_data;
cmd->flags = 0;
return 0;
}