summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorChuck Lever <chuck.lever@oracle.com>2022-04-02 00:08:21 +0300
committerChuck Lever <chuck.lever@oracle.com>2022-04-06 21:01:27 +0300
commit773f91b2cf3f52df0d7508fdbf60f37567cdaee4 (patch)
tree09fbe39e6553910ebedee2ecd627cd264fb5f363
parent999397926ab3f78c7d1235cc4ca6e3c89d2769bf (diff)
downloadlinux-773f91b2cf3f52df0d7508fdbf60f37567cdaee4.tar.xz
SUNRPC: Fix NFSD's request deferral on RDMA transports
Trond Myklebust reports an NFSD crash in svc_rdma_sendto(). Further investigation shows that the crash occurred while NFSD was handling a deferred request. This patch addresses two inter-related issues that prevent request deferral from working correctly for RPC/RDMA requests: 1. Prevent the crash by ensuring that the original svc_rqst::rq_xprt_ctxt value is available when the request is revisited. Otherwise svc_rdma_sendto() does not have a Receive context available with which to construct its reply. 2. Possibly since before commit 71641d99ce03 ("svcrdma: Properly compute .len and .buflen for received RPC Calls"), svc_rdma_recvfrom() did not include the transport header in the returned xdr_buf. There should have been no need for svc_defer() and friends to save and restore that header, as of that commit. This issue is addressed in a backport-friendly way by simply having svc_rdma_recvfrom() set rq_xprt_hlen to zero unconditionally, just as svc_tcp_recvfrom() does. This enables svc_deferred_recv() to correctly reconstruct an RPC message received via RPC/RDMA. Reported-by: Trond Myklebust <trondmy@hammerspace.com> Link: https://lore.kernel.org/linux-nfs/82662b7190f26fb304eb0ab1bb04279072439d4e.camel@hammerspace.com/ Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Cc: <stable@vger.kernel.org>
-rw-r--r--include/linux/sunrpc/svc.h1
-rw-r--r--net/sunrpc/svc_xprt.c3
-rw-r--r--net/sunrpc/xprtrdma/svc_rdma_recvfrom.c2
3 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index a5dda4987e8b..217711fc9cac 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -395,6 +395,7 @@ struct svc_deferred_req {
size_t addrlen;
struct sockaddr_storage daddr; /* where reply must come from */
size_t daddrlen;
+ void *xprt_ctxt;
struct cache_deferred_req handle;
size_t xprt_hlen;
int argslen;
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 0c117d3bfda8..b42cfffa7395 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -1231,6 +1231,8 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
dr->daddr = rqstp->rq_daddr;
dr->argslen = rqstp->rq_arg.len >> 2;
dr->xprt_hlen = rqstp->rq_xprt_hlen;
+ dr->xprt_ctxt = rqstp->rq_xprt_ctxt;
+ rqstp->rq_xprt_ctxt = NULL;
/* back up head to the start of the buffer and copy */
skip = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len;
@@ -1269,6 +1271,7 @@ static noinline int svc_deferred_recv(struct svc_rqst *rqstp)
rqstp->rq_xprt_hlen = dr->xprt_hlen;
rqstp->rq_daddr = dr->daddr;
rqstp->rq_respages = rqstp->rq_pages;
+ rqstp->rq_xprt_ctxt = dr->xprt_ctxt;
svc_xprt_received(rqstp->rq_xprt);
return (dr->argslen<<2) - dr->xprt_hlen;
}
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index cf76a6ad127b..864131a9fc6e 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -831,7 +831,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
goto out_err;
if (ret == 0)
goto out_drop;
- rqstp->rq_xprt_hlen = ret;
+ rqstp->rq_xprt_hlen = 0;
if (svc_rdma_is_reverse_direction_reply(xprt, ctxt))
goto out_backchannel;