svcrdma: Skip put_page() when send_reply() fails

commit 9995237b upstream.

Message from syslogd@klimt at Aug 18 17:00:37 ...
 kernel:page:ffffea0020639b00 count:0 mapcount:0 mapping:          (null) index:0x0
Aug 18 17:00:37 klimt kernel: flags: 0x2fffff80000000()
Aug 18 17:00:37 klimt kernel: page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0)

Aug 18 17:00:37 klimt kernel: kernel BUG at /home/cel/src/linux/linux-2.6/include/linux/mm.h:445!
Aug 18 17:00:37 klimt kernel: RIP: 0010:[<ffffffffa05c21c1>] svc_rdma_sendto+0x641/0x820 [rpcrdma]

send_reply() assigns its page argument as the first page of ctxt. On
error, send_reply() already invokes svc_rdma_put_context(ctxt, 1);
which does a put_page() on that very page. No need to do that again
as svc_rdma_sendto exits.

Fixes: 3e1eeb98 ("svcrdma: Close connection when a send error occurs")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/sunrpc/xprtrdma/svc_rdma_sendto.c

@@ -635,7 +635,7 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
 	ret = send_reply(rdma, rqstp, res_page, rdma_resp, vec,
 			 inline_bytes);
 	if (ret < 0)
-		goto err1;
+		goto err0;
 
 	svc_rdma_put_req_map(rdma, vec);
 	dprintk("svcrdma: send_reply returns %d\n", ret);