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path: root/drivers/block/nbd.c
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Diffstat (limited to 'drivers/block/nbd.c')
-rw-r--r--drivers/block/nbd.c117
1 files changed, 75 insertions, 42 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 855fdf5c3b4e..b6414e1e645b 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -67,6 +67,7 @@ struct nbd_sock {
struct recv_thread_args {
struct work_struct work;
struct nbd_device *nbd;
+ struct nbd_sock *nsock;
int index;
};
@@ -395,6 +396,22 @@ static u32 req_to_nbd_cmd_type(struct request *req)
}
}
+static struct nbd_config *nbd_get_config_unlocked(struct nbd_device *nbd)
+{
+ if (refcount_inc_not_zero(&nbd->config_refs)) {
+ /*
+ * Add smp_mb__after_atomic to ensure that reading nbd->config_refs
+ * and reading nbd->config is ordered. The pair is the barrier in
+ * nbd_alloc_and_init_config(), avoid nbd->config_refs is set
+ * before nbd->config.
+ */
+ smp_mb__after_atomic();
+ return nbd->config;
+ }
+
+ return NULL;
+}
+
static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
@@ -409,13 +426,13 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req)
return BLK_EH_DONE;
}
- if (!refcount_inc_not_zero(&nbd->config_refs)) {
+ config = nbd_get_config_unlocked(nbd);
+ if (!config) {
cmd->status = BLK_STS_TIMEOUT;
__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
mutex_unlock(&cmd->lock);
goto done;
}
- config = nbd->config;
if (config->num_connections > 1 ||
(config->num_connections == 1 && nbd->tag_set.timeout)) {
@@ -489,15 +506,9 @@ done:
return BLK_EH_DONE;
}
-/*
- * Send or receive packet. Return a positive value on success and
- * negtive value on failue, and never return 0.
- */
-static int sock_xmit(struct nbd_device *nbd, int index, int send,
- struct iov_iter *iter, int msg_flags, int *sent)
+static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
+ struct iov_iter *iter, int msg_flags, int *sent)
{
- struct nbd_config *config = nbd->config;
- struct socket *sock = config->socks[index]->sock;
int result;
struct msghdr msg;
unsigned int noreclaim_flag;
@@ -541,6 +552,19 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send,
}
/*
+ * Send or receive packet. Return a positive value on success and
+ * negtive value on failure, and never return 0.
+ */
+static int sock_xmit(struct nbd_device *nbd, int index, int send,
+ struct iov_iter *iter, int msg_flags, int *sent)
+{
+ struct nbd_config *config = nbd->config;
+ struct socket *sock = config->socks[index]->sock;
+
+ return __sock_xmit(nbd, sock, send, iter, msg_flags, sent);
+}
+
+/*
* Different settings for sk->sk_sndtimeo can result in different return values
* if there is a signal pending when we enter sendmsg, because reasons?
*/
@@ -696,7 +720,7 @@ out:
return 0;
}
-static int nbd_read_reply(struct nbd_device *nbd, int index,
+static int nbd_read_reply(struct nbd_device *nbd, struct socket *sock,
struct nbd_reply *reply)
{
struct kvec iov = {.iov_base = reply, .iov_len = sizeof(*reply)};
@@ -705,7 +729,7 @@ static int nbd_read_reply(struct nbd_device *nbd, int index,
reply->magic = 0;
iov_iter_kvec(&to, ITER_DEST, &iov, 1, sizeof(*reply));
- result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
+ result = __sock_xmit(nbd, sock, 0, &to, MSG_WAITALL, NULL);
if (result < 0) {
if (!nbd_disconnected(nbd->config))
dev_err(disk_to_dev(nbd->disk),
@@ -829,14 +853,14 @@ static void recv_work(struct work_struct *work)
struct nbd_device *nbd = args->nbd;
struct nbd_config *config = nbd->config;
struct request_queue *q = nbd->disk->queue;
- struct nbd_sock *nsock;
+ struct nbd_sock *nsock = args->nsock;
struct nbd_cmd *cmd;
struct request *rq;
while (1) {
struct nbd_reply reply;
- if (nbd_read_reply(nbd, args->index, &reply))
+ if (nbd_read_reply(nbd, nsock->sock, &reply))
break;
/*
@@ -871,7 +895,6 @@ static void recv_work(struct work_struct *work)
percpu_ref_put(&q->q_usage_counter);
}
- nsock = config->socks[args->index];
mutex_lock(&nsock->tx_lock);
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
@@ -977,12 +1000,12 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
struct nbd_sock *nsock;
int ret;
- if (!refcount_inc_not_zero(&nbd->config_refs)) {
+ config = nbd_get_config_unlocked(nbd);
+ if (!config) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Socks array is empty\n");
return -EINVAL;
}
- config = nbd->config;
if (index >= config->num_connections) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
@@ -1215,6 +1238,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
INIT_WORK(&args->work, recv_work);
args->index = i;
args->nbd = nbd;
+ args->nsock = nsock;
nsock->cookie++;
mutex_unlock(&nsock->tx_lock);
sockfd_put(old);
@@ -1397,6 +1421,7 @@ static int nbd_start_device(struct nbd_device *nbd)
refcount_inc(&nbd->config_refs);
INIT_WORK(&args->work, recv_work);
args->nbd = nbd;
+ args->nsock = config->socks[i];
args->index = i;
queue_work(nbd->recv_workq, &args->work);
}
@@ -1530,17 +1555,20 @@ static int nbd_ioctl(struct block_device *bdev, blk_mode_t mode,
return error;
}
-static struct nbd_config *nbd_alloc_config(void)
+static int nbd_alloc_and_init_config(struct nbd_device *nbd)
{
struct nbd_config *config;
+ if (WARN_ON(nbd->config))
+ return -EINVAL;
+
if (!try_module_get(THIS_MODULE))
- return ERR_PTR(-ENODEV);
+ return -ENODEV;
config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
if (!config) {
module_put(THIS_MODULE);
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
}
atomic_set(&config->recv_threads, 0);
@@ -1548,12 +1576,24 @@ static struct nbd_config *nbd_alloc_config(void)
init_waitqueue_head(&config->conn_wait);
config->blksize_bits = NBD_DEF_BLKSIZE_BITS;
atomic_set(&config->live_connections, 0);
- return config;
+
+ nbd->config = config;
+ /*
+ * Order refcount_set(&nbd->config_refs, 1) and nbd->config assignment,
+ * its pair is the barrier in nbd_get_config_unlocked().
+ * So nbd_get_config_unlocked() won't see nbd->config as null after
+ * refcount_inc_not_zero() succeed.
+ */
+ smp_mb__before_atomic();
+ refcount_set(&nbd->config_refs, 1);
+
+ return 0;
}
static int nbd_open(struct gendisk *disk, blk_mode_t mode)
{
struct nbd_device *nbd;
+ struct nbd_config *config;
int ret = 0;
mutex_lock(&nbd_index_mutex);
@@ -1566,27 +1606,25 @@ static int nbd_open(struct gendisk *disk, blk_mode_t mode)
ret = -ENXIO;
goto out;
}
- if (!refcount_inc_not_zero(&nbd->config_refs)) {
- struct nbd_config *config;
+ config = nbd_get_config_unlocked(nbd);
+ if (!config) {
mutex_lock(&nbd->config_lock);
if (refcount_inc_not_zero(&nbd->config_refs)) {
mutex_unlock(&nbd->config_lock);
goto out;
}
- config = nbd_alloc_config();
- if (IS_ERR(config)) {
- ret = PTR_ERR(config);
+ ret = nbd_alloc_and_init_config(nbd);
+ if (ret) {
mutex_unlock(&nbd->config_lock);
goto out;
}
- nbd->config = config;
- refcount_set(&nbd->config_refs, 1);
+
refcount_inc(&nbd->refs);
mutex_unlock(&nbd->config_lock);
if (max_part)
set_bit(GD_NEED_PART_SCAN, &disk->state);
- } else if (nbd_disconnected(nbd->config)) {
+ } else if (nbd_disconnected(config)) {
if (max_part)
set_bit(GD_NEED_PART_SCAN, &disk->state);
}
@@ -1990,22 +2028,17 @@ again:
pr_err("nbd%d already in use\n", index);
return -EBUSY;
}
- if (WARN_ON(nbd->config)) {
- mutex_unlock(&nbd->config_lock);
- nbd_put(nbd);
- return -EINVAL;
- }
- config = nbd_alloc_config();
- if (IS_ERR(config)) {
+
+ ret = nbd_alloc_and_init_config(nbd);
+ if (ret) {
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
pr_err("couldn't allocate config\n");
- return PTR_ERR(config);
+ return ret;
}
- nbd->config = config;
- refcount_set(&nbd->config_refs, 1);
- set_bit(NBD_RT_BOUND, &config->runtime_flags);
+ config = nbd->config;
+ set_bit(NBD_RT_BOUND, &config->runtime_flags);
ret = nbd_genl_size_set(info, nbd);
if (ret)
goto out;
@@ -2208,7 +2241,8 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
}
mutex_unlock(&nbd_index_mutex);
- if (!refcount_inc_not_zero(&nbd->config_refs)) {
+ config = nbd_get_config_unlocked(nbd);
+ if (!config) {
dev_err(nbd_to_dev(nbd),
"not configured, cannot reconfigure\n");
nbd_put(nbd);
@@ -2216,7 +2250,6 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
}
mutex_lock(&nbd->config_lock);
- config = nbd->config;
if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
!nbd->pid) {
dev_err(nbd_to_dev(nbd),
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-12 22:53:53 +0300