diff options
| author | Christoph Hellwig <hch@lst.de> | 2021-08-25 18:31:07 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-08-25 14:20:29 -0600 |
| commit | 438cd318c8dfa5228ffd43af1b98d7cd7d92e1c6 (patch) | |
| tree | d70ba2194a286f02d8fe8359289e6db73c692a4a | |
| parent | b190300decb352a0b865d7aa379e89b17d772a43 (diff) | |
nbd: only return usable devices from nbd_find_unused
Device marked as NBD_DESTROY_ON_DISCONNECT can and should be skipped
given that they won't survive the disconnect. So skip them and try
to grab a reference directly and just continue if the the devices
is being torn down or created and thus has a zero refcount.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210825163108.50713-6-hch@lst.de
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | drivers/block/nbd.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 6a832bf81647..70dc9d80a173 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1790,16 +1790,20 @@ out: return ERR_PTR(err); } -static struct nbd_device *nbd_find_unused(void) +static struct nbd_device *nbd_find_get_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)) + idr_for_each_entry(&nbd_index_idr, nbd, id) { + if (refcount_read(&nbd->config_refs) || + test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags)) + continue; + if (refcount_inc_not_zero(&nbd->refs)) return nbd; + } return NULL; } @@ -1873,10 +1877,10 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) again: mutex_lock(&nbd_index_mutex); if (index == -1) - nbd = nbd_find_unused(); + nbd = nbd_find_get_unused(); else nbd = idr_find(&nbd_index_idr, index); - if (nbd) { + if (nbd && index != -1) { if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) && test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) { nbd->destroy_complete = &destroy_complete; @@ -1889,8 +1893,6 @@ again: if (!refcount_inc_not_zero(&nbd->refs)) { mutex_unlock(&nbd_index_mutex); - if (index == -1) - goto again; pr_err("nbd: device at index %d is going down\n", index); return -EINVAL; |