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authorChristoph Hellwig <hch@lst.de>2021-08-25 19:31:08 +0300
committerJens Axboe <axboe@kernel.dk>2021-08-25 23:20:32 +0300
commit7ee656c3ac3d047b4cf1269f83ac9d6c0bba916b (patch)
treecef84e52823c8574a5844e6deab2b125fdfc1a1e /drivers/block
parent438cd318c8dfa5228ffd43af1b98d7cd7d92e1c6 (diff)
downloadlinux-7ee656c3ac3d047b4cf1269f83ac9d6c0bba916b.tar.xz
nbd: remove nbd->destroy_complete
The nbd->destroy_complete pointer is not really needed. For creating a device without a specific index we now simplify skip devices marked NBD_DESTROY_ON_DISCONNECT as there is not much point to reuse them. For device creation with a specific index there is no real need to treat the case of a requested but not finished disconnect different than any other device that is being shutdown, i.e. we can just return an error, as a slightly different race window would anyway. Fixes: 6e4df4c64881 ("nbd: reduce the nbd_index_mutex scope") Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot+2c98885bcd769f56b6d6@syzkaller.appspotmail.com Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210825163108.50713-7-hch@lst.de Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/nbd.c52
1 files changed, 14 insertions, 38 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 70dc9d80a173..44143068c91e 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -120,7 +120,6 @@ struct nbd_device {
struct task_struct *task_recv;
struct task_struct *task_setup;
- struct completion *destroy_complete;
unsigned long flags;
char *backend;
@@ -235,19 +234,6 @@ static const struct device_attribute backend_attr = {
.show = backend_show,
};
-/*
- * Place this in the last just before the nbd is freed to
- * make sure that the disk and the related kobject are also
- * totally removed to avoid duplicate creation of the same
- * one.
- */
-static void nbd_notify_destroy_completion(struct nbd_device *nbd)
-{
- if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
- nbd->destroy_complete)
- complete(nbd->destroy_complete);
-}
-
static void nbd_dev_remove(struct nbd_device *nbd)
{
struct gendisk *disk = nbd->disk;
@@ -262,7 +248,6 @@ static void nbd_dev_remove(struct nbd_device *nbd)
*/
mutex_lock(&nbd_index_mutex);
idr_remove(&nbd_index_idr, nbd->index);
- nbd_notify_destroy_completion(nbd);
mutex_unlock(&nbd_index_mutex);
kfree(nbd);
@@ -1702,7 +1687,6 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
BLK_MQ_F_BLOCKING;
nbd->tag_set.driver_data = nbd;
INIT_WORK(&nbd->remove_work, nbd_dev_remove_work);
- nbd->destroy_complete = NULL;
nbd->backend = NULL;
err = blk_mq_alloc_tag_set(&nbd->tag_set);
@@ -1854,7 +1838,6 @@ 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;
struct nbd_config *config;
int index = -1;
@@ -1876,31 +1859,24 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
}
again:
mutex_lock(&nbd_index_mutex);
- if (index == -1)
+ if (index == -1) {
nbd = nbd_find_get_unused();
- else
+ } else {
nbd = idr_find(&nbd_index_idr, index);
- 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;
- mutex_unlock(&nbd_index_mutex);
-
- /* wait until the nbd device is completely destroyed */
- wait_for_completion(&destroy_complete);
- goto again;
- }
-
- if (!refcount_inc_not_zero(&nbd->refs)) {
- mutex_unlock(&nbd_index_mutex);
- pr_err("nbd: device at index %d is going down\n",
- index);
- return -EINVAL;
+ if (nbd) {
+ if ((test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
+ test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) ||
+ !refcount_inc_not_zero(&nbd->refs)) {
+ mutex_unlock(&nbd_index_mutex);
+ pr_err("nbd: device at index %d is going down\n",
+ index);
+ return -EINVAL;
+ }
}
- mutex_unlock(&nbd_index_mutex);
- } else {
- mutex_unlock(&nbd_index_mutex);
+ }
+ mutex_unlock(&nbd_index_mutex);
+ if (!nbd) {
nbd = nbd_dev_add(index, 2);
if (IS_ERR(nbd)) {
pr_err("nbd: failed to add new device\n");