CIFS: Fix an issue with re-sending wdata when transport returning -EAGAIN

When sending a wdata, transport may return -EAGAIN. In this case
we should re-obtain credits because the session may have been
reconnected.

Change in v2: adjust_credits before re-sending
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/file.c

@@ -2632,43 +2632,56 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
 	struct TCP_Server_Info *server =
 		tlink_tcon(wdata->cfile->tlink)->ses->server;
 
+	do {
+		if (wdata->cfile->invalidHandle) {
+			rc = cifs_reopen_file(wdata->cfile, false);
+			if (rc == -EAGAIN)
+				continue;
+			else if (rc)
+				break;
+		}
+
+
 		/*
 		 * Wait for credits to resend this wdata.
-	 * Note: we are attempting to resend the whole wdata not in segments
+		 * Note: we are attempting to resend the whole wdata not in
+		 * segments
 		 */
 		do {
-		rc = server->ops->wait_mtu_credits(server, wdata->bytes, &wsize,
-						   &credits);
-
+			rc = server->ops->wait_mtu_credits(server, wdata->bytes,
+						&wsize, &credits);
 			if (rc)
-			goto out;
+				goto fail;
 
 			if (wsize < wdata->bytes) {
 				add_credits_and_wake_if(server, &credits, 0);
 				msleep(1000);
 			}
 		} while (wsize < wdata->bytes);
-
 		wdata->credits = credits;
-	rc = -EAGAIN;
-	while (rc == -EAGAIN) {
-		rc = 0;
+
+		rc = adjust_credits(server, &wdata->credits, wdata->bytes);
+
+		if (!rc) {
 			if (wdata->cfile->invalidHandle)
-			rc = cifs_reopen_file(wdata->cfile, false);
-		if (!rc)
+				rc = -EAGAIN;
+			else
 				rc = server->ops->async_writev(wdata,
 					cifs_uncached_writedata_release);
 		}
 
+		/* If the write was successfully sent, we are done */
 		if (!rc) {
 			list_add_tail(&wdata->list, wdata_list);
 			return 0;
 		}
 
+		/* Roll back credits and retry if needed */
 		add_credits_and_wake_if(server, &wdata->credits, 0);
-out:
-	kref_put(&wdata->refcount, cifs_uncached_writedata_release);
+	} while (rc == -EAGAIN);
 
+fail:
+	kref_put(&wdata->refcount, cifs_uncached_writedata_release);
 	return rc;
 }
 
@@ -2896,12 +2909,12 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
 						wdata->bytes, &tmp_from,
 						ctx->cfile, cifs_sb, &tmp_list,
 						ctx);
-				}
-
-				list_splice(&tmp_list, &ctx->list);
 
 					kref_put(&wdata->refcount,
 						cifs_uncached_writedata_release);
+				}
+
+				list_splice(&tmp_list, &ctx->list);
 				goto restart_loop;
 			}
 		}