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nbd: reset NBD to NULL when restarting in nbd_genl_connect

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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: 6177b56c96 ("nbd: refactor device search and allocation in nbd_genl_connect")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210825163108.50713-3-hch@lst.de
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-08-25 18:31:04 +02:00 committed by Jens Axboe
parent 93f63bc41f
commit 409e0ff10e
1 changed files with 18 additions and 14 deletions
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32
drivers/block/nbd.c
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@ -1781,6 +1781,20 @@ out:
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)) {