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| author | Chuck Lever <chuck.lever@oracle.com> | 2022-04-02 00:08:21 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-20 10:34:18 +0300 |
| commit | f5e13d700a4d40ccde3d36e383f9247dcb3c1d2d (patch) | |
| tree | 85bc30bd70d33587ff998cd1139bdd39ed19c8a4 /net | |
| parent | 00715427ea778b45a6d2bf2c20bbdff33b44d3f6 (diff) | |
| download | linux-f5e13d700a4d40ccde3d36e383f9247dcb3c1d2d.tar.xz | |
SUNRPC: Fix NFSD's request deferral on RDMA transports
commit 773f91b2cf3f52df0d7508fdbf60f37567cdaee4 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sunrpc/svc_xprt.c | 3 | ||||
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 2 |
2 files changed, 4 insertions, 1 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index d4b663401be1..935bba065636 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1213,6 +1213,8 @@ 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; @@ -1251,6 +1253,7 @@ 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 6be23ce7a93d..387a5da09daf 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -826,7 +826,7 @@ 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; |