* [PATCH] nbd: clear DISCONNECT_REQUESTED flag once disconnection occurs.
@ 2018-05-29 23:09 kvigor
2018-05-30 15:41 ` Jens Axboe
0 siblings, 1 reply; 5+ messages in thread
From: kvigor @ 2018-05-29 23:09 UTC (permalink / raw)
To: linux-block; +Cc: josef, axboe, Kevin Vigor
From: Kevin Vigor <kvigor@fb.com>
When a userspace client requests a NBD device be disconnected, the
DISCONNECT_REQUESTED flag is set. While this flag is set, the driver
will not inform userspace when a connection is closed.
Unfortunately the flag was never cleared, so once a disconnect was
requested the driver would thereafter never tell userspace about a
closed connection. Thus when connections failed due to timeout, no
attempt to reconnect was made and eventually the device would fail.
Fix by clearing the DISCONNECT_REQUESTED flag (and setting the
DISCONNECTED flag) once all connections are closed.
Additionally wake all tasks waiting in wait_for_reconnect() when a
connection is established instead of only waking one and letting the
rest timeout.
Signed-off-by: Kevin Vigor <kvigor@fb.com>
---
drivers/block/nbd.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index afbc202..11956d4 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -213,7 +213,15 @@ static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
}
if (!nsock->dead) {
kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
- atomic_dec(&nbd->config->live_connections);
+ if (atomic_dec_return(&nbd->config->live_connections) == 0) {
+ if (test_and_clear_bit(NBD_DISCONNECT_REQUESTED,
+ &nbd->config->runtime_flags)) {
+ set_bit(NBD_DISCONNECTED,
+ &nbd->config->runtime_flags);
+ dev_info(nbd_to_dev(nbd),
+ "Disconnected due to user request.\n");
+ }
+ }
}
nsock->dead = true;
nsock->pending = NULL;
@@ -292,7 +300,9 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
if (config->num_connections > 1) {
dev_err_ratelimited(nbd_to_dev(nbd),
- "Connection timed out, retrying\n");
+ "Connection timed out, retrying (%d/%d alive)\n",
+ atomic_read(&config->live_connections),
+ config->num_connections);
/*
* Hooray we have more connections, requeue this IO, the submit
* path will put it on a real connection.
@@ -714,10 +724,9 @@ static int wait_for_reconnect(struct nbd_device *nbd)
return 0;
if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
return 0;
- wait_event_timeout(config->conn_wait,
- atomic_read(&config->live_connections),
- config->dead_conn_timeout);
- return atomic_read(&config->live_connections);
+ return wait_event_timeout(config->conn_wait,
+ atomic_read(&config->live_connections) > 0,
+ config->dead_conn_timeout) > 0;
}
static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
@@ -937,7 +946,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
queue_work(recv_workqueue, &args->work);
atomic_inc(&config->live_connections);
- wake_up(&config->conn_wait);
+ wake_up_all(&config->conn_wait);
return 0;
}
sockfd_put(sock);
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] nbd: clear DISCONNECT_REQUESTED flag once disconnection occurs.
2018-05-29 23:09 [PATCH] nbd: clear DISCONNECT_REQUESTED flag once disconnection occurs kvigor
@ 2018-05-30 15:41 ` Jens Axboe
0 siblings, 0 replies; 5+ messages in thread
From: Jens Axboe @ 2018-05-30 15:41 UTC (permalink / raw)
To: kvigor, linux-block; +Cc: josef, Kevin Vigor
On 5/29/18 5:09 PM, kvigor@gmail.com wrote:
> @@ -937,7 +946,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
> queue_work(recv_workqueue, &args->work);
>
> atomic_inc(&config->live_connections);
> - wake_up(&config->conn_wait);
> + wake_up_all(&config->conn_wait);
> return 0;
> }
> sockfd_put(sock);
Unless you're using exclusive waits, and you are not, then wake_up() is
equivalent to wake_up_all().
--
Jens Axboe
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] nbd: clear DISCONNECT_REQUESTED flag once disconnection occurs.
2018-05-30 16:45 kvigor
2018-05-30 17:28 ` Josef Bacik
@ 2018-05-30 17:31 ` Jens Axboe
1 sibling, 0 replies; 5+ messages in thread
From: Jens Axboe @ 2018-05-30 17:31 UTC (permalink / raw)
To: kvigor, linux-block; +Cc: josef, Kevin Vigor
On 5/30/18 10:45 AM, kvigor@gmail.com wrote:
> From: Kevin Vigor <kvigor@fb.com>
>
> When a userspace client requests a NBD device be disconnected, the
> DISCONNECT_REQUESTED flag is set. While this flag is set, the driver
> will not inform userspace when a connection is closed.
>
> Unfortunately the flag was never cleared, so once a disconnect was
> requested the driver would thereafter never tell userspace about a
> closed connection. Thus when connections failed due to timeout, no
> attempt to reconnect was made and eventually the device would fail.
>
> Fix by clearing the DISCONNECT_REQUESTED flag (and setting the
> DISCONNECTED flag) once all connections are closed.
Applied, thanks Kevin.
--
Jens Axboe
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] nbd: clear DISCONNECT_REQUESTED flag once disconnection occurs.
2018-05-30 16:45 kvigor
@ 2018-05-30 17:28 ` Josef Bacik
2018-05-30 17:31 ` Jens Axboe
1 sibling, 0 replies; 5+ messages in thread
From: Josef Bacik @ 2018-05-30 17:28 UTC (permalink / raw)
To: kvigor; +Cc: linux-block, josef, axboe, Kevin Vigor
On Wed, May 30, 2018 at 10:45:11AM -0600, kvigor@gmail.com wrote:
> From: Kevin Vigor <kvigor@fb.com>
>
> When a userspace client requests a NBD device be disconnected, the
> DISCONNECT_REQUESTED flag is set. While this flag is set, the driver
> will not inform userspace when a connection is closed.
>
> Unfortunately the flag was never cleared, so once a disconnect was
> requested the driver would thereafter never tell userspace about a
> closed connection. Thus when connections failed due to timeout, no
> attempt to reconnect was made and eventually the device would fail.
>
> Fix by clearing the DISCONNECT_REQUESTED flag (and setting the
> DISCONNECTED flag) once all connections are closed.
>
> Changes relative to v1 (https://marc.info/?l=linux-block&m=152763540418902):
>
> * remove pointless wake_up() -> wake_up_all() change.
>
Usually you want to put the changelog after the --- bit below so we can all see
it but it doesn't end up in the git changelog.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Thanks,
Josef
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] nbd: clear DISCONNECT_REQUESTED flag once disconnection occurs.
@ 2018-05-30 16:45 kvigor
2018-05-30 17:28 ` Josef Bacik
2018-05-30 17:31 ` Jens Axboe
0 siblings, 2 replies; 5+ messages in thread
From: kvigor @ 2018-05-30 16:45 UTC (permalink / raw)
To: linux-block; +Cc: josef, axboe, Kevin Vigor
From: Kevin Vigor <kvigor@fb.com>
When a userspace client requests a NBD device be disconnected, the
DISCONNECT_REQUESTED flag is set. While this flag is set, the driver
will not inform userspace when a connection is closed.
Unfortunately the flag was never cleared, so once a disconnect was
requested the driver would thereafter never tell userspace about a
closed connection. Thus when connections failed due to timeout, no
attempt to reconnect was made and eventually the device would fail.
Fix by clearing the DISCONNECT_REQUESTED flag (and setting the
DISCONNECTED flag) once all connections are closed.
Changes relative to v1 (https://marc.info/?l=linux-block&m=152763540418902):
* remove pointless wake_up() -> wake_up_all() change.
Signed-off-by: Kevin Vigor <kvigor@fb.com>
---
drivers/block/nbd.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index afbc202..1cd041b 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -213,7 +213,15 @@ static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
}
if (!nsock->dead) {
kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
- atomic_dec(&nbd->config->live_connections);
+ if (atomic_dec_return(&nbd->config->live_connections) == 0) {
+ if (test_and_clear_bit(NBD_DISCONNECT_REQUESTED,
+ &nbd->config->runtime_flags)) {
+ set_bit(NBD_DISCONNECTED,
+ &nbd->config->runtime_flags);
+ dev_info(nbd_to_dev(nbd),
+ "Disconnected due to user request.\n");
+ }
+ }
}
nsock->dead = true;
nsock->pending = NULL;
@@ -292,7 +300,9 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
if (config->num_connections > 1) {
dev_err_ratelimited(nbd_to_dev(nbd),
- "Connection timed out, retrying\n");
+ "Connection timed out, retrying (%d/%d alive)\n",
+ atomic_read(&config->live_connections),
+ config->num_connections);
/*
* Hooray we have more connections, requeue this IO, the submit
* path will put it on a real connection.
@@ -714,10 +724,9 @@ static int wait_for_reconnect(struct nbd_device *nbd)
return 0;
if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
return 0;
- wait_event_timeout(config->conn_wait,
- atomic_read(&config->live_connections),
- config->dead_conn_timeout);
- return atomic_read(&config->live_connections);
+ return wait_event_timeout(config->conn_wait,
+ atomic_read(&config->live_connections) > 0,
+ config->dead_conn_timeout) > 0;
}
static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
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2018-05-29 23:09 [PATCH] nbd: clear DISCONNECT_REQUESTED flag once disconnection occurs kvigor
2018-05-30 15:41 ` Jens Axboe
2018-05-30 16:45 kvigor
2018-05-30 17:28 ` Josef Bacik
2018-05-30 17:31 ` Jens Axboe
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