Commit 409e0ff1 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

nbd: reset NBD to NULL when restarting in nbd_genl_connect 



When nbd_genl_connect restarts to wait for a disconnecting device, nbd
needs to be reset to NULL.  Do that by facoring out a helper to find
an unused device.

Fixes: 6177b56c ("nbd: refactor device search and allocation in nbd_genl_connect")
Reported-by: default avatarTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: default avatarHillf Danton <hdanton@sina.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210825163108.50713-3-hch@lst.de


Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 93f63bc4

drivers/block/nbd.c

+18 −14
Original line number Diff line number Diff line
@@ -1781,6 +1781,20 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs) 
	return ERR_PTR(err);

}



static struct nbd_device *nbd_find_unused(void)

{

	struct nbd_device *nbd;

	int id;



	lockdep_assert_held(&nbd_index_mutex);



	idr_for_each_entry(&nbd_index_idr, nbd, id)

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

			return nbd;



	return NULL;

}



/* Netlink interface. */

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

	[NBD_ATTR_INDEX]		=	{ .type = NLA_U32 },
@@ -1828,7 +1842,7 @@ static int nbd_genl_size_set(struct genl_info *info, struct nbd_device *nbd) 
static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)

{

	DECLARE_COMPLETION_ONSTACK(destroy_complete);

	struct nbd_device *nbd = NULL;

	struct nbd_device *nbd;

	struct nbd_config *config;

	int index = -1;

	int ret;
@@ -1849,20 +1863,10 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) 
	}

again:

	mutex_lock(&nbd_index_mutex);

	if (index == -1) {

		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 {

	if (index == -1)

		nbd = nbd_find_unused();

	else

		nbd = idr_find(&nbd_index_idr, index);

	}



	if (nbd) {

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

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