The way we make changes to the NBD device is inherently racey, as we
could be in the middle of a request and suddenly change the number of
connections. In practice this isn't a big deal, but with timeouts we
have to take the config_lock in order to protect ourselves since it is
important those values don't change. Fix this by freezing the queue
before we do any of our device operations.
Signed-off-by: Josef Bacik <jba...@fb.com>
---
drivers/block/nbd.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 164a548..f8b3ecd 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -199,7 +199,6 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct
request *req,
if (nbd->num_connections > 1) {
dev_err_ratelimited(nbd_to_dev(nbd),
"Connection timed out, retrying\n");
- mutex_lock(&nbd->config_lock);
/*
* Hooray we have more connections, requeue this IO, the submit
* path will put it on a real connection.
@@ -213,11 +212,9 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct
request *req,
kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
mutex_unlock(&nsock->tx_lock);
}
- mutex_unlock(&nbd->config_lock);
blk_mq_requeue_request(req, true);
return BLK_EH_RESET_TIMER;
}
- mutex_unlock(&nbd->config_lock);
} else {
dev_err_ratelimited(nbd_to_dev(nbd),
"Connection timed out\n");
@@ -225,9 +222,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct
request *req,
set_bit(NBD_TIMEDOUT, &nbd->runtime_flags);
req->errors++;
- mutex_lock(&nbd->config_lock);
sock_shutdown(nbd);
- mutex_unlock(&nbd->config_lock);
return BLK_EH_HANDLED;
}
@@ -756,7 +751,9 @@ static int __nbd_ioctl(struct block_device *bdev, struct
nbd_device *nbd,
return -EINVAL;
mutex_unlock(&nbd->config_lock);
+ blk_mq_unfreeze_queue(nbd->disk->queue);
fsync_bdev(bdev);
+ blk_mq_freeze_queue(nbd->disk->queue);
mutex_lock(&nbd->config_lock);
/* Check again after getting mutex back. */
@@ -870,10 +867,14 @@ static int __nbd_ioctl(struct block_device *bdev, struct
nbd_device *nbd,
args[i].index = i;
queue_work(recv_workqueue, &args[i].work);
}
+ blk_mq_unfreeze_queue(nbd->disk->queue);
+
wait_event_interruptible(nbd->recv_wq,
atomic_read(&nbd->recv_threads) == 0);
for (i = 0; i < num_connections; i++)
flush_work(&args[i].work);
+
+ blk_mq_freeze_queue(nbd->disk->queue);
nbd_dev_dbg_close(nbd);
nbd_size_clear(nbd, bdev);
device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
@@ -924,9 +925,11 @@ static int nbd_ioctl(struct block_device *bdev, fmode_t
mode,
BUG_ON(nbd->magic != NBD_MAGIC);
+ blk_mq_freeze_queue(nbd->disk->queue);
mutex_lock(&nbd->config_lock);
error = __nbd_ioctl(bdev, nbd, cmd, arg);
mutex_unlock(&nbd->config_lock);
+ blk_mq_unfreeze_queue(nbd->disk->queue);
return error;
}
--
2.7.4
------------------------------------------------------------------------------
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