CIFS: Introduce credit-based flow control
and send no more than credits value requests at once. For SMB/CIFS
it's trivial: increment this value by receiving any message and
decrement by sending one.
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index ed91abc..1d48901 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -642,14 +642,10 @@
spin_unlock(&GlobalMid_Lock);
wake_up_all(&server->response_q);
- /* Check if we have blocked requests that need to free. */
+ /* check if we have blocked requests that need to free */
spin_lock(&server->req_lock);
- if (server->in_flight >= server->maxReq)
- server->in_flight = server->maxReq - 1;
- /*
- * We do not want to set the max_pending too low or we could end up
- * with the counter going negative.
- */
+ if (server->credits <= 0)
+ server->credits = 1;
spin_unlock(&server->req_lock);
/*
* Although there should not be any requests blocked on this queue it
@@ -1906,7 +1902,7 @@
tcp_ses->noautotune = volume_info->noautotune;
tcp_ses->tcp_nodelay = volume_info->sockopt_tcp_nodelay;
tcp_ses->in_flight = 0;
- tcp_ses->maxReq = 1; /* enough to send negotiate request */
+ tcp_ses->credits = 1;
init_waitqueue_head(&tcp_ses->response_q);
init_waitqueue_head(&tcp_ses->request_q);
INIT_LIST_HEAD(&tcp_ses->pending_mid_q);
@@ -3757,9 +3753,11 @@
if (server->maxBuf != 0)
return 0;
+ cifs_set_credits(server, 1);
rc = CIFSSMBNegotiate(xid, ses);
if (rc == -EAGAIN) {
/* retry only once on 1st time connection */
+ cifs_set_credits(server, 1);
rc = CIFSSMBNegotiate(xid, ses);
if (rc == -EAGAIN)
rc = -EHOSTDOWN;