svcrdma: send_write() must not overflow the device's max sge

Function send_write() must stop creating sges when it reaches the device
max and return the amount sent in the RDMA Write to the caller.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 15 insertions, 24 deletions

diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index 49fd21a5c215..9f1b50689c0f 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -192,6 +192,8 @@ static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,
                 xdr_sge_no++;
                 BUG_ON(xdr_sge_no > vec->count);
                 bc -= sge_bytes;
+                if (sge_no == xprt->sc_max_sge)
+                        break;
         }
 
         /* Prepare WRITE WR */
@@ -209,7 +211,7 @@ static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,
         atomic_inc(&rdma_stat_write);
         if (svc_rdma_send(xprt, &write_wr))
                 goto err;
-        return 0;
+        return write_len - bc;
  err:
         svc_rdma_unmap_dma(ctxt);
         svc_rdma_put_context(ctxt, 0);
@@ -225,7 +227,6 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
 {
         u32 xfer_len = rqstp->rq_res.page_len + rqstp->rq_res.tail[0].iov_len;
         int write_len;
-        int max_write;
         u32 xdr_off;
         int chunk_off;
         int chunk_no;
@@ -239,8 +240,6 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
         res_ary = (struct rpcrdma_write_array *)
                 &rdma_resp->rm_body.rm_chunks[1];
 
-        max_write = xprt->sc_max_sge * PAGE_SIZE;
-
         /* Write chunks start at the pagelist */
         for (xdr_off = rqstp->rq_res.head[0].iov_len, chunk_no = 0;
              xfer_len && chunk_no < arg_ary->wc_nchunks;
@@ -260,23 +259,21 @@ static int send_write_chunks(struct svcxprt_rdma *xprt,
                                                 write_len);
                 chunk_off = 0;
                 while (write_len) {
-                        int this_write;
-                        this_write = min(write_len, max_write);
                         ret = send_write(xprt, rqstp,
                                          ntohl(arg_ch->rs_handle),
                                          rs_offset + chunk_off,
                                          xdr_off,
-                                         this_write,
+                                         write_len,
                                          vec);
-                        if (ret) {
+                        if (ret <= 0) {
                                 dprintk("svcrdma: RDMA_WRITE failed, ret=%d\n",
                                         ret);
                                 return -EIO;
                         }
-                        chunk_off += this_write;
-                        xdr_off += this_write;
-                        xfer_len -= this_write;
-                        write_len -= this_write;
+                        chunk_off += ret;
+                        xdr_off += ret;
+                        xfer_len -= ret;
+                        write_len -= ret;
                 }
         }
         /* Update the req with the number of chunks actually used */
@@ -293,7 +290,6 @@ static int send_reply_chunks(struct svcxprt_rdma *xprt,
 {
         u32 xfer_len = rqstp->rq_res.len;
         int write_len;
-        int max_write;
         u32 xdr_off;
         int chunk_no;
         int chunk_off;
@@ -311,8 +307,6 @@ static int send_reply_chunks(struct svcxprt_rdma *xprt,
         res_ary = (struct rpcrdma_write_array *)
                 &rdma_resp->rm_body.rm_chunks[2];
 
-        max_write = xprt->sc_max_sge * PAGE_SIZE;
-
         /* xdr offset starts at RPC message */
         nchunks = ntohl(arg_ary->wc_nchunks);
         for (xdr_off = 0, chunk_no = 0;
@@ -330,24 +324,21 @@ static int send_reply_chunks(struct svcxprt_rdma *xprt,
                                                 write_len);
                 chunk_off = 0;
                 while (write_len) {
-                        int this_write;
-
-                        this_write = min(write_len, max_write);
                         ret = send_write(xprt, rqstp,
                                          ntohl(ch->rs_handle),
                                          rs_offset + chunk_off,
                                          xdr_off,
-                                         this_write,
+                                         write_len,
                                          vec);
-                        if (ret) {
+                        if (ret <= 0) {
                                 dprintk("svcrdma: RDMA_WRITE failed, ret=%d\n",
                                         ret);
                                 return -EIO;
                         }
-                        chunk_off += this_write;
-                        xdr_off += this_write;
-                        xfer_len -= this_write;
-                        write_len -= this_write;
+                        chunk_off += ret;
+                        xdr_off += ret;
+                        xfer_len -= ret;
+                        write_len -= ret;
                 }
         }
         /* Update the req with the number of chunks actually used */