Re: Need help debugging NFS issues new to 4.20 kernel

Trond Myklebust
2019-02-16T14:46:53Z

On Fri, 2019-02-15 at 14:33 -0600, Jason L Tibbitts III wrote:
> > > > > > "BC" == Benjamin Coddington <bcodding@redhat.com> writes:
>
> BC> Hmm.. commit c443305529d1d3d3bee0d68fdd14ae89835e091f changed
> BC> xs_read_stream_reply() to return recv.copied instead of "ret" to
> BC> xprt_complete_rqst()..

That's a good thing. xprt_complete_rqst() really dislikes negative
error values.

> BC> You could try reverting that commit and see if the problem goes
> BC> away..
>
> So patching a revert of that into 4.20.7 was beyond me, but I
> received
> some help from Jeremy Cline on IRC (in #fedora-kernel) and ended up
> with
> a patch I'll include at the end. So far it does seem to be better,
> but
> because of secure boot annoyances I haven't been able to roll it out
> more generally. However, it has been stable for a week on a few
> hosts
> which have been problematic with stock 4.20.6.
>
> I will continue to test, but hopefully this helps folks to understand
> what's happening.
>

Hmm... Does the following patch help at all?
---
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 7754aa3e434f..a1a8903ae5d0 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -404,8 +404,8 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr
*msg, int flags,
size_t want, seek_init = seek, offset = 0;
ssize_t ret;

- if (seek < buf->head[0].iov_len) {
- want = min_t(size_t, count, buf->head[0].iov_len);
+ want = min_t(size_t, count, buf->head[0].iov_len);
+ if (seek < want) {
ret = xs_read_kvec(sock, msg, flags, &buf->head[0],
want, seek);
if (ret <= 0)
goto sock_err;
@@ -416,8 +416,8 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr
*msg, int flags,
goto out;
seek = 0;
} else {
- seek -= buf->head[0].iov_len;
- offset += buf->head[0].iov_len;
+ seek -= want;
+ offset += want;
}

want = xs_alloc_sparse_pages(buf,
@@ -442,8 +442,8 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr
*msg, int flags,
offset += want;
}

- if (seek < buf->tail[0].iov_len) {
- want = min_t(size_t, count - offset, buf-
>tail[0].iov_len);
+ want = min_t(size_t, count - offset, buf->tail[0].iov_len);
+ if (seek < want) {
ret = xs_read_kvec(sock, msg, flags, &buf->tail[0],
want, seek);
if (ret <= 0)
goto sock_err;
@@ -453,7 +453,7 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr
*msg, int flags,
if (ret != want)
goto out;
} else
- offset += buf->tail[0].iov_len;
+ offset = seek_init;
ret = -EMSGSIZE;
out:
*read = offset - seek_init;
@@ -497,11 +497,9 @@ xs_read_stream_request(struct sock_xprt
*transport, struct msghdr *msg,
&read);
transport->recv.offset += read;
transport->recv.copied += read;
- if (transport->recv.offset == transport->recv.len) {
- if (xs_read_stream_request_done(transport))
- msg->msg_flags |= MSG_EOR;
- return read;
- }
+ if (transport->recv.offset == transport->recv.len &&
+ xs_read_stream_request_done(transport))
+ msg->msg_flags |= MSG_EOR;

switch (ret) {
default:
@@ -671,6 +669,8 @@ static void xs_stream_data_receive(struct sock_xprt
*transport)
read += ret;
cond_resched();
}
+ if (ret == -ESHUTDOWN)
+ kernel_sock_shutdown(transport->sock, SHUT_RDWR);
out:
mutex_unlock(&transport->recv_mutex);
trace_xs_stream_read_data(&transport->xprt, ret, read);
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com