smb: server: let recv_done() queue a refill when the peer is low on credits

In captures I saw that Windows was granting 191 credits in a batch
when its peer posted a lot of messages. We are asking for a
credit target of 255 and 191 is 252*3/4.

So we also use that logic in order to fill the
recv buffers available to the peer.

Fixes: a7eef6144c97 ("smb: server: queue post_recv_credits_work in put_recvmsg() and avoid count_avail_recvmsg")
Cc: <stable@vger.kernel.org> # 6.18.x
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/transport_rdma.c b/fs/smb/server/transport_rdma.c
index c66f237dc106b70c326d8482f3066f9c935ea86c..4a473df1f2b3adf403c1b11f9d07cfda23f49232 100644 (file)
--- a/fs/smb/server/transport_rdma.c
+++ b/fs/smb/server/transport_rdma.c
@@ -644,6 +644,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
                struct smbdirect_data_transfer *data_transfer =
                        (struct smbdirect_data_transfer *)recvmsg->packet;
                u32 remaining_data_length, data_offset, data_length;
+               int current_recv_credits;
                u16 old_recv_credit_target;
 
                if (wc->byte_len <
@@ -682,7 +683,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
                }
 
                atomic_dec(&sc->recv_io.posted.count);
-               atomic_dec(&sc->recv_io.credits.count);
+               current_recv_credits = atomic_dec_return(&sc->recv_io.credits.count);
 
                old_recv_credit_target = sc->recv_io.credits.target;
                sc->recv_io.credits.target =
@@ -702,7 +703,8 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
                        wake_up(&sc->send_io.credits.wait_queue);
 
                if (data_length) {
-                       if (sc->recv_io.credits.target > old_recv_credit_target)
+                       if (current_recv_credits <= (sc->recv_io.credits.target / 4) ||
+                           sc->recv_io.credits.target > old_recv_credit_target)
                                queue_work(sc->workqueue, &sc->recv_io.posted.refill_work);
 
                        enqueue_reassembly(sc, recvmsg, (int)data_length);