smb: server: make use of smbdirect_socket.send_io.bcredits

It turns out that our code will corrupt the stream of
reassabled data transfer messages when we trigger an
immendiate (empty) send.

In order to fix this we'll have a single 'batch' credit per
connection. And code getting that credit is free to use
as much messages until remaining_length reaches 0, then
the batch credit it given back and the next logical send can
happen.

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 4a473df1f2b3adf403c1b11f9d07cfda23f49232..38248b6a1b5caf16e98e7a0ebd5e0591f8241803 100644 (file)
--- a/fs/smb/server/transport_rdma.c
+++ b/fs/smb/server/transport_rdma.c
@@ -221,6 +221,7 @@ static void smb_direct_disconnect_wake_up_all(struct smbdirect_socket *sc)
         * in order to notice the broken connection.
         */
        wake_up_all(&sc->status_wait);
+       wake_up_all(&sc->send_io.bcredits.wait_queue);
        wake_up_all(&sc->send_io.lcredits.wait_queue);
        wake_up_all(&sc->send_io.credits.wait_queue);
        wake_up_all(&sc->send_io.pending.zero_wait_queue);
@@ -1152,6 +1153,7 @@ static void smb_direct_send_ctx_init(struct smbdirect_send_batch *send_ctx,
        send_ctx->wr_cnt = 0;
        send_ctx->need_invalidate_rkey = need_invalidate_rkey;
        send_ctx->remote_key = remote_key;
+       send_ctx->credit = 0;
 }
 
 static int smb_direct_flush_send_list(struct smbdirect_socket *sc,
@@ -1159,10 +1161,10 @@ static int smb_direct_flush_send_list(struct smbdirect_socket *sc,
                                      bool is_last)
 {
        struct smbdirect_send_io *first, *last;
-       int ret;
+       int ret = 0;
 
        if (list_empty(&send_ctx->msg_list))
-               return 0;
+               goto release_credit;
 
        first = list_first_entry(&send_ctx->msg_list,
                                 struct smbdirect_send_io,
@@ -1204,6 +1206,13 @@ static int smb_direct_flush_send_list(struct smbdirect_socket *sc,
                smb_direct_free_sendmsg(sc, last);
        }
 
+release_credit:
+       if (is_last && !ret && send_ctx->credit) {
+               atomic_add(send_ctx->credit, &sc->send_io.bcredits.count);
+               send_ctx->credit = 0;
+               wake_up(&sc->send_io.bcredits.wait_queue);
+       }
+
        return ret;
 }
 
@@ -1229,6 +1238,25 @@ static int wait_for_credits(struct smbdirect_socket *sc,
        } while (true);
 }
 
+static int wait_for_send_bcredit(struct smbdirect_socket *sc,
+                                struct smbdirect_send_batch *send_ctx)
+{
+       int ret;
+
+       if (send_ctx->credit)
+               return 0;
+
+       ret = wait_for_credits(sc,
+                              &sc->send_io.bcredits.wait_queue,
+                              &sc->send_io.bcredits.count,
+                              1);
+       if (ret)
+               return ret;
+
+       send_ctx->credit = 1;
+       return 0;
+}
+
 static int wait_for_send_lcredit(struct smbdirect_socket *sc,
                                 struct smbdirect_send_batch *send_ctx)
 {
@@ -1430,6 +1458,16 @@ static int smb_direct_post_send_data(struct smbdirect_socket *sc,
        struct smbdirect_send_io *msg;
        int data_length;
        struct scatterlist sg[SMBDIRECT_SEND_IO_MAX_SGE - 1];
+       struct smbdirect_send_batch _send_ctx;
+
+       if (!send_ctx) {
+               smb_direct_send_ctx_init(&_send_ctx, false, 0);
+               send_ctx = &_send_ctx;
+       }
+
+       ret = wait_for_send_bcredit(sc, send_ctx);
+       if (ret)
+               goto bcredit_failed;
 
        ret = wait_for_send_lcredit(sc, send_ctx);
        if (ret)
@@ -1482,6 +1520,13 @@ static int smb_direct_post_send_data(struct smbdirect_socket *sc,
        ret = post_sendmsg(sc, send_ctx, msg);
        if (ret)
                goto err;
+
+       if (send_ctx == &_send_ctx) {
+               ret = smb_direct_flush_send_list(sc, send_ctx, true);
+               if (ret)
+                       goto err;
+       }
+
        return 0;
 err:
        smb_direct_free_sendmsg(sc, msg);
@@ -1490,6 +1535,9 @@ header_failed:
 credit_failed:
        atomic_inc(&sc->send_io.lcredits.count);
 lcredit_failed:
+       atomic_add(send_ctx->credit, &sc->send_io.bcredits.count);
+       send_ctx->credit = 0;
+bcredit_failed:
        return ret;
 }
 
@@ -1961,6 +2009,7 @@ static int smb_direct_send_negotiate_response(struct smbdirect_socket *sc,
                resp->max_fragmented_size =
                                cpu_to_le32(sp->max_fragmented_recv_size);
 
+               atomic_set(&sc->send_io.bcredits.count, 1);
                sc->recv_io.expected = SMBDIRECT_EXPECT_DATA_TRANSFER;
                sc->status = SMBDIRECT_SOCKET_CONNECTED;
        }