cifs: smbd: Avoid allocating iov on the stack

It's not necessary to allocate another iov when going through the buffers
in smbd_send() through RDMA send.

Remove it to reduce stack size.

Thanks to Matt for spotting a printk typo in the earlier version of this.

CC: Matt Redfearn <matt.redfearn@mips.com>
Signed-off-by: Long Li <longli@microsoft.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index 87817ddcc096d49036fb4b3421a2bbb3b2fe6b8a..c62f7c95683c513213bc786152f78b60a2f8fbd6 100644 (file)
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -2086,7 +2086,7 @@ int smbd_send(struct smbd_connection *info, struct smb_rqst *rqst)
        int start, i, j;
        int max_iov_size =
                info->max_send_size - sizeof(struct smbd_data_transfer);
-       struct kvec iov[SMBDIRECT_MAX_SGE];
+       struct kvec *iov;
        int rc;
 
        info->smbd_send_pending++;
@@ -2096,32 +2096,20 @@ int smbd_send(struct smbd_connection *info, struct smb_rqst *rqst)
        }
 
        /*
-        * This usually means a configuration error
-        * We use RDMA read/write for packet size > rdma_readwrite_threshold
-        * as long as it's properly configured we should never get into this
-        * situation
-        */
-       if (rqst->rq_nvec + rqst->rq_npages > SMBDIRECT_MAX_SGE) {
-               log_write(ERR, "maximum send segment %x exceeding %x\n",
-                        rqst->rq_nvec + rqst->rq_npages, SMBDIRECT_MAX_SGE);
-               rc = -EINVAL;
-               goto done;
-       }
-
-       /*
-        * Remove the RFC1002 length defined in MS-SMB2 section 2.1
-        * It is used only for TCP transport
+        * Skip the RFC1002 length defined in MS-SMB2 section 2.1
+        * It is used only for TCP transport in the iov[0]
         * In future we may want to add a transport layer under protocol
         * layer so this will only be issued to TCP transport
         */
-       iov[0].iov_base = (char *)rqst->rq_iov[0].iov_base + 4;
-       iov[0].iov_len = rqst->rq_iov[0].iov_len - 4;
-       buflen += iov[0].iov_len;
+
+       if (rqst->rq_iov[0].iov_len != 4) {
+               log_write(ERR, "expected the pdu length in 1st iov, but got %zu\n", rqst->rq_iov[0].iov_len);
+               return -EINVAL;
+       }
+       iov = &rqst->rq_iov[1];
 
        /* total up iov array first */
-       for (i = 1; i < rqst->rq_nvec; i++) {
-               iov[i].iov_base = rqst->rq_iov[i].iov_base;
-               iov[i].iov_len = rqst->rq_iov[i].iov_len;
+       for (i = 0; i < rqst->rq_nvec-1; i++) {
                buflen += iov[i].iov_len;
        }
 
@@ -2198,14 +2186,14 @@ int smbd_send(struct smbd_connection *info, struct smb_rqst *rqst)
                                                goto done;
                                }
                                i++;
-                               if (i == rqst->rq_nvec)
+                               if (i == rqst->rq_nvec-1)
                                        break;
                        }
                        start = i;
                        buflen = 0;
                } else {
                        i++;
-                       if (i == rqst->rq_nvec) {
+                       if (i == rqst->rq_nvec-1) {
                                /* send out all remaining vecs */
                                remaining_data_length -= buflen;
                                log_write(INFO,