cifs: Fix prepare_write to negotiate wsize if needed

Fix cifs_prepare_write() to negotiate the wsize if it is unset.

Reviewed-by: Shyam Prasad N <nspmangalore@gmail.com>
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: dhowells

fs/smb/client/file.c

@@ -52,6 +52,7 @@ static void cifs_prepare_write(struct netfs_io_subrequest *subreq)
 	struct netfs_io_stream *stream = &req->rreq.io_streams[subreq->stream_nr];
 	struct TCP_Server_Info *server;
 	struct cifsFileInfo *open_file = req->cfile;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(wdata->rreq->inode->i_sb);
 	size_t wsize = req->rreq.wsize;
 	int rc;
 
@@ -63,6 +64,10 @@ static void cifs_prepare_write(struct netfs_io_subrequest *subreq)
 	server = cifs_pick_channel(tlink_tcon(open_file->tlink)->ses);
 	wdata->server = server;
 
+	if (cifs_sb->ctx->wsize == 0)
+		cifs_negotiate_wsize(server, cifs_sb->ctx,
+				     tlink_tcon(req->cfile->tlink));
+
 retry:
 	if (open_file->invalidHandle) {
 		rc = cifs_reopen_file(open_file, false);
@@ -160,10 +165,9 @@ static int cifs_prepare_read(struct netfs_io_subrequest *subreq)
 	server = cifs_pick_channel(tlink_tcon(req->cfile->tlink)->ses);
 	rdata->server = server;
 
-	if (cifs_sb->ctx->rsize == 0) {
+	if (cifs_sb->ctx->rsize == 0)
 		cifs_negotiate_rsize(server, cifs_sb->ctx,
 				     tlink_tcon(req->cfile->tlink));
-	}
 
 	rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->rsize,
 					   &size, &rdata->credits);