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nbd: use our own workqueue for recv threads 

Since we are in the memory reclaim path we need our recv work to be on a
workqueue that has WQ_MEM_RECLAIM set so we can avoid deadlocks.  Also
set WQ_HIGHPRI since we are in the completion path for IO.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Josef Bacik 2017-02-01 16:11:11 -05:00 committed by Jens Axboe
parent 72f2f8f692
commit 124d6db07c
1 changed files with 11 additions and 2 deletions
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13
drivers/block/nbd.c
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@ -91,6 +91,7 @@ static struct dentry *nbd_dbg_dir;
static unsigned int nbds_max = 16;
static struct nbd_device *nbd_dev;
static int max_part;
static struct workqueue_struct *recv_workqueue;
static inline struct device *nbd_to_dev(struct nbd_device *nbd)
{
@ -781,7 +782,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
INIT_WORK(&args[i].work, recv_work);
args[i].nbd = nbd;
args[i].index = i;
queue_work(system_long_wq, &args[i].work);
queue_work(recv_workqueue, &args[i].work);
}
wait_event_interruptible(nbd->recv_wq,
atomic_read(&nbd->recv_threads) == 0);
@ -1030,10 +1031,16 @@ static int __init nbd_init(void)
if (nbds_max > 1UL << (MINORBITS - part_shift))
return -EINVAL;
recv_workqueue = alloc_workqueue("knbd-recv",
WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
if (!recv_workqueue)
return -ENOMEM;
nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
if (!nbd_dev)
if (!nbd_dev) {
destroy_workqueue(recv_workqueue);
return -ENOMEM;
}
for (i = 0; i < nbds_max; i++) {
struct request_queue *q;
@ -1113,6 +1120,7 @@ static int __init nbd_init(void)
put_disk(nbd_dev[i].disk);
}
kfree(nbd_dev);
destroy_workqueue(recv_workqueue);
return err;
}
@ -1132,6 +1140,7 @@ static void __exit nbd_cleanup(void)
put_disk(disk);
}
}
destroy_workqueue(recv_workqueue);
unregister_blkdev(NBD_MAJOR, "nbd");
kfree(nbd_dev);
printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);