Commit 2b7bbc96 authored by Chuck Lever's avatar Chuck Lever Committed by Trond Myklebust

SUNRPC: Fix large reads on NFS/RDMA

After commit a11a2bf4, "SUNRPC: Optimise away unnecessary data moves
in xdr_align_pages", Thu Aug 2 13:21:43 2012, READs larger than a
few hundred bytes via NFS/RDMA no longer work.  This commit exposed
a long-standing bug in rpcrdma_inline_fixup().

I reproduce this with an rsize=4096 mount using the cthon04 basic
tests.  Test 5 fails with an EIO error.

For my reproducer, kernel log shows:

  NFS: server cheating in read reply: count 4096 > recvd 0

rpcrdma_inline_fixup() is zeroing the xdr_stream::page_len field,
and xdr_align_pages() is now returning that value to the READ XDR
decoder function.

That field is set up by xdr_inline_pages() by the READ XDR encoder
function.  As far as I can tell, it is supposed to be left alone
after that, as it describes the dimensions of the reply xdr_stream,
not the contents of that stream.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=68391Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent a7697f6f
...@@ -649,9 +649,7 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad) ...@@ -649,9 +649,7 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
break; break;
page_base = 0; page_base = 0;
} }
rqst->rq_rcv_buf.page_len = olen - copy_len; }
} else
rqst->rq_rcv_buf.page_len = 0;
if (copy_len && rqst->rq_rcv_buf.tail[0].iov_len) { if (copy_len && rqst->rq_rcv_buf.tail[0].iov_len) {
curlen = copy_len; curlen = copy_len;
......
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