smb: client: let smbd_post_send_iter() respect the peers max_send_size and transmit...

We should not send smbdirect_data_transfer messages larger than
the negotiated max_send_size, typically 1364 bytes, which means
24 bytes of the smbdirect_data_transfer header + 1340 payload bytes.

This happened when doing an SMB2 write with more than 1340 bytes
(which is done inline as it's below rdma_readwrite_threshold).

It means the peer resets the connection.

When testing between cifs.ko and ksmbd.ko something like this
is logged:

client:

    CIFS: VFS: RDMA transport re-established
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    siw: got TERMINATE. layer 1, type 2, code 2
    CIFS: VFS: \\carina Send error in SessSetup = -11
    smb2_reconnect: 12 callbacks suppressed
    CIFS: VFS: reconnect tcon failed rc = -11
    CIFS: VFS: reconnect tcon failed rc = -11
    CIFS: VFS: reconnect tcon failed rc = -11
    CIFS: VFS: SMB: Zero rsize calculated, using minimum value 65536

and:

    CIFS: VFS: RDMA transport re-established
    siw: got TERMINATE. layer 1, type 2, code 2
    CIFS: VFS: smbd_recv:1894 disconnected
    siw: got TERMINATE. layer 1, type 2, code 2

The ksmbd dmesg is showing things like:

    smb_direct: Recv error. status='local length error (1)' opcode=128
    smb_direct: disconnected
    smb_direct: Recv error. status='local length error (1)' opcode=128
    ksmbd: smb_direct: disconnected
    ksmbd: sock_read failed: -107

As smbd_post_send_iter() limits the transmitted number of bytes
we need loop over it in order to transmit the whole iter.

Reviewed-by: David Howells <dhowells@redhat.com>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Meetakshi Setiya <msetiya@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: <stable+noautosel@kernel.org> # sp->max_send_size should be info->max_send_size in backports
Fixes: 3d78fe73fa12 ("cifs: Build the RDMA SGE list directly from an iterator")
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 cbc85bca006f72a852ec8a36182ef30ea4ba1636..a976bcf61226ddb426a363cf08cd3876c059a9dd 100644 (file)
--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -907,8 +907,10 @@ wait_send_queue:
                        .local_dma_lkey = sc->ib.pd->local_dma_lkey,
                        .direction      = DMA_TO_DEVICE,
                };
+               size_t payload_len = umin(*_remaining_data_length,
+                                         sp->max_send_size - sizeof(*packet));
 
-               rc = smb_extract_iter_to_rdma(iter, *_remaining_data_length,
+               rc = smb_extract_iter_to_rdma(iter, payload_len,
                                              &extract);
                if (rc < 0)
                        goto err_dma;
@@ -1013,6 +1015,27 @@ static int smbd_post_send_empty(struct smbd_connection *info)
        return smbd_post_send_iter(info, NULL, &remaining_data_length);
 }
 
+static int smbd_post_send_full_iter(struct smbd_connection *info,
+                                   struct iov_iter *iter,
+                                   int *_remaining_data_length)
+{
+       int rc = 0;
+
+       /*
+        * smbd_post_send_iter() respects the
+        * negotiated max_send_size, so we need to
+        * loop until the full iter is posted
+        */
+
+       while (iov_iter_count(iter) > 0) {
+               rc = smbd_post_send_iter(info, iter, _remaining_data_length);
+               if (rc < 0)
+                       break;
+       }
+
+       return rc;
+}
+
 /*
  * Post a receive request to the transport
  * The remote peer can only send data when a receive request is posted
@@ -2032,14 +2055,14 @@ int smbd_send(struct TCP_Server_Info *server,
                        klen += rqst->rq_iov[i].iov_len;
                iov_iter_kvec(&iter, ITER_SOURCE, rqst->rq_iov, rqst->rq_nvec, klen);
 
-               rc = smbd_post_send_iter(info, &iter, &remaining_data_length);
+               rc = smbd_post_send_full_iter(info, &iter, &remaining_data_length);
                if (rc < 0)
                        break;
 
                if (iov_iter_count(&rqst->rq_iter) > 0) {
                        /* And then the data pages if there are any */
-                       rc = smbd_post_send_iter(info, &rqst->rq_iter,
-                                                &remaining_data_length);
+                       rc = smbd_post_send_full_iter(info, &rqst->rq_iter,
+                                                     &remaining_data_length);
                        if (rc < 0)
                                break;
                }