Commit 6177b56c authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

nbd: refactor device search and allocation in nbd_genl_connect 



Use idr_for_each_entry instead of the awkward callback to find an
existing device for the index == -1 case, and de-duplicate the device
allocation if no existing device was found.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210811124428.2368491-6-hch@lst.de


Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7bdc00cf

drivers/block/nbd.c

+14 −31
Original line number Diff line number Diff line
@@ -1767,18 +1767,6 @@ static struct nbd_device *nbd_dev_add(int index) 
	return ERR_PTR(err);

}



static int find_free_cb(int id, void *ptr, void *data)

{

	struct nbd_device *nbd = ptr;

	struct nbd_device **found = data;



	if (!refcount_read(&nbd->config_refs)) {

		*found = nbd;

		return 1;

	}

	return 0;

}



/* Netlink interface. */

static const struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {

	[NBD_ATTR_INDEX]		=	{ .type = NLA_U32 },
@@ -1848,32 +1836,27 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) 
again:

	mutex_lock(&nbd_index_mutex);

	if (index == -1) {

		ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);

		if (ret == 0) {

			nbd = nbd_dev_add(-1);

			if (IS_ERR(nbd)) {

				mutex_unlock(&nbd_index_mutex);

				printk(KERN_ERR "nbd: failed to add new device\n");

				return PTR_ERR(nbd);

		struct nbd_device *tmp;

		int id;



		idr_for_each_entry(&nbd_index_idr, tmp, id) {

			if (!refcount_read(&tmp->config_refs)) {

				nbd = tmp;

				break;

			}

		}

	} else {

		nbd = idr_find(&nbd_index_idr, index);

	}



	if (!nbd) {

		nbd = nbd_dev_add(index);

		if (IS_ERR(nbd)) {

			mutex_unlock(&nbd_index_mutex);

				printk(KERN_ERR "nbd: failed to add new device\n");

			pr_err("nbd: failed to add new device\n");

			return PTR_ERR(nbd);

		}

	}

	}

	if (!nbd) {

		printk(KERN_ERR "nbd: couldn't find device at index %d\n",

		       index);

		mutex_unlock(&nbd_index_mutex);

		return -EINVAL;

	}



	if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&

	    test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) {