smb: client: 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: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/smbdirect.c b/fs/smb/client/smbdirect.c
index ef3b237bccc132642b884e933e9d0bc592a0160d..dbb2d939bc44d7d400be558fd59fbbf3d81c7605 100644 (file)
--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -657,6 +657,7 @@ static bool process_negotiation_response(
                        sp->max_frmr_depth * PAGE_SIZE);
        sp->max_frmr_depth = sp->max_read_write_size / PAGE_SIZE;
 
+       atomic_set(&sc->send_io.bcredits.count, 1);
        sc->recv_io.expected = SMBDIRECT_EXPECT_DATA_TRANSFER;
        return true;
 }
@@ -1214,6 +1215,7 @@ static void smbd_send_batch_init(struct smbdirect_send_batch *batch,
        batch->wr_cnt = 0;
        batch->need_invalidate_rkey = need_invalidate_rkey;
        batch->remote_key = remote_key;
+       batch->credit = 0;
 }
 
 static int smbd_send_batch_flush(struct smbdirect_socket *sc,
@@ -1224,7 +1226,7 @@ static int smbd_send_batch_flush(struct smbdirect_socket *sc,
        int ret = 0;
 
        if (list_empty(&batch->msg_list))
-               return 0;
+               goto release_credit;
 
        first = list_first_entry(&batch->msg_list,
                                 struct smbdirect_send_io,
@@ -1266,6 +1268,13 @@ static int smbd_send_batch_flush(struct smbdirect_socket *sc,
                smbd_free_send_io(last);
        }
 
+release_credit:
+       if (is_last && !ret && batch->credit) {
+               atomic_add(batch->credit, &sc->send_io.bcredits.count);
+               batch->credit = 0;
+               wake_up(&sc->send_io.bcredits.wait_queue);
+       }
+
        return ret;
 }
 
@@ -1291,6 +1300,25 @@ 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 *batch)
+{
+       int ret;
+
+       if (batch->credit)
+               return 0;
+
+       ret = wait_for_credits(sc,
+                              &sc->send_io.bcredits.wait_queue,
+                              &sc->send_io.bcredits.count,
+                              1);
+       if (ret)
+               return ret;
+
+       batch->credit = 1;
+       return 0;
+}
+
 static int wait_for_send_lcredit(struct smbdirect_socket *sc,
                                 struct smbdirect_send_batch *batch)
 {
@@ -1338,6 +1366,19 @@ static int smbd_post_send_iter(struct smbdirect_socket *sc,
        struct smbdirect_send_io *request;
        struct smbdirect_data_transfer *packet;
        int new_credits = 0;
+       struct smbdirect_send_batch _batch;
+
+       if (!batch) {
+               smbd_send_batch_init(&_batch, false, 0);
+               batch = &_batch;
+       }
+
+       rc = wait_for_send_bcredit(sc, batch);
+       if (rc) {
+               log_outgoing(ERR, "disconnected not sending on wait_bcredit\n");
+               rc = -EAGAIN;
+               goto err_wait_bcredit;
+       }
 
        rc = wait_for_send_lcredit(sc, batch);
        if (rc) {
@@ -1432,8 +1473,14 @@ static int smbd_post_send_iter(struct smbdirect_socket *sc,
                     le32_to_cpu(packet->remaining_data_length));
 
        rc = smbd_post_send(sc, batch, request);
-       if (!rc)
-               return 0;
+       if (!rc) {
+               if (batch != &_batch)
+                       return 0;
+
+               rc = smbd_send_batch_flush(sc, batch, true);
+               if (!rc)
+                       return 0;
+       }
 
 err_dma:
        smbd_free_send_io(request);
@@ -1447,6 +1494,11 @@ err_wait_credit:
        wake_up(&sc->send_io.lcredits.wait_queue);
 
 err_wait_lcredit:
+       atomic_add(batch->credit, &sc->send_io.bcredits.count);
+       batch->credit = 0;
+       wake_up(&sc->send_io.bcredits.wait_queue);
+
+err_wait_bcredit:
        return rc;
 }