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authorAlexander Aring <aahringo@redhat.com>2020-07-27 09:13:37 -0400
committerDavid Teigland <teigland@redhat.com>2020-08-06 10:30:54 -0500
commitba3ab3ca68caafb7700c4abae357b7fb7538df11 (patch)
treefc015a963ac2faacbb524eb66ea088d7a7cf8a53 /fs/dlm
parent0ea47e4d2109efd61e9949d014b37ea835f20861 (diff)
fs: dlm: change handling of reconnects
This patch changes the handling of reconnects. At first we only close the connection related to the communication failure. If we get a new connection for an already existing connection we close the existing connection and take the new one. This patch improves significantly the stability of tcp connections while running "tcpkill -9 -i $IFACE port 21064" while generating a lot of dlm messages e.g. on a gfs2 mount with many files. My test setup shows that a deadlock is "more" unlikely. Before this patch I wasn't able to get not a deadlock after 5 seconds. After this patch my observation is that it's more likely to survive after 5 seconds and more, but still a deadlock occurs after certain time. My guess is that there are still "segments" inside the tcp writequeue or retransmit queue which get dropped when receiving a tcp reset [1]. Hard to reproduce because the right message need to be inside these queues, which might even be in the 5 first seconds with this patch. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ipv4/tcp_input.c?h=v5.8-rc6#n4122 Signed-off-by: Alexander Aring <aahringo@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com>
Diffstat (limited to 'fs/dlm')
-rw-r--r--fs/dlm/lowcomms.c25
1 files changed, 10 insertions, 15 deletions
diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 9e6acbb47bb9..289439fdca99 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -713,7 +713,7 @@ out_resched:
out_close:
mutex_unlock(&con->sock_mutex);
if (ret != -EAGAIN) {
- close_connection(con, true, true, false);
+ close_connection(con, false, true, false);
/* Reconnect when there is something to send */
}
/* Don't return success if we really got EOF */
@@ -804,21 +804,16 @@ static int accept_from_sock(struct connection *con)
INIT_WORK(&othercon->swork, process_send_sockets);
INIT_WORK(&othercon->rwork, process_recv_sockets);
set_bit(CF_IS_OTHERCON, &othercon->flags);
+ } else {
+ /* close other sock con if we have something new */
+ close_connection(othercon, false, true, false);
}
+
mutex_lock_nested(&othercon->sock_mutex, 2);
- if (!othercon->sock) {
- newcon->othercon = othercon;
- add_sock(newsock, othercon);
- addcon = othercon;
- mutex_unlock(&othercon->sock_mutex);
- }
- else {
- printk("Extra connection from node %d attempted\n", nodeid);
- result = -EAGAIN;
- mutex_unlock(&othercon->sock_mutex);
- mutex_unlock(&newcon->sock_mutex);
- goto accept_err;
- }
+ newcon->othercon = othercon;
+ add_sock(newsock, othercon);
+ addcon = othercon;
+ mutex_unlock(&othercon->sock_mutex);
}
else {
newcon->rx_action = receive_from_sock;
@@ -1415,7 +1410,7 @@ out:
send_error:
mutex_unlock(&con->sock_mutex);
- close_connection(con, true, false, true);
+ close_connection(con, false, false, true);
/* Requeue the send work. When the work daemon runs again, it will try
a new connection, then call this function again. */
queue_work(send_workqueue, &con->swork);