xprtrdma: Per-connection pad optimization

Pad optimization is changed by echoing into
/proc/sys/sunrpc/rdma_pad_optimize. This is a global setting,
affecting all RPC-over-RDMA connections to all servers.

The marshaling code picks up that value and uses it for decisions
about how to construct each RPC-over-RDMA frame. Having it change
suddenly in mid-operation can result in unexpected failures. And
some servers a client mounts might need chunk round-up, while
others don't.

So instead, copy the pad_optimize setting into each connection's
rpcrdma_ia when the transport is created, and use the copy, which
can't change during the life of the connection, instead.

This also removes a hack: rpcrdma_convert_iovs was using
the remote-invalidation-expected flag to predict when it could leave
out Write chunk padding. This is because the Linux server handles
implicit XDR padding on Write chunks correctly, and only Linux
servers can set the connection's remote-invalidation-expected flag.

It's more sensible to use the pad optimization setting instead.

Fixes: 677eb17e94ed ("xprtrdma: Fix XDR tail buffer marshalling")
Cc: stable@vger.kernel.org # v4.9+
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index a524d3c2e8aca522b7ae8a7d8c28823fd44952c8..c634f0f3f9ceeca55e1cf219fa0ebe06d4d566b8 100644 (file)
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -186,9 +186,9 @@ rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg, int n)
  */
 
 static int
-rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
-       enum rpcrdma_chunktype type, struct rpcrdma_mr_seg *seg,
-       bool reminv_expected)
+rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
+                    unsigned int pos, enum rpcrdma_chunktype type,
+                    struct rpcrdma_mr_seg *seg)
 {
        int len, n, p, page_base;
        struct page **ppages;
@@ -229,14 +229,15 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
        /* When encoding a Read chunk, the tail iovec contains an
         * XDR pad and may be omitted.
         */
-       if (type == rpcrdma_readch && xprt_rdma_pad_optimize)
+       if (type == rpcrdma_readch && r_xprt->rx_ia.ri_implicit_roundup)
                return n;
 
-       /* When encoding the Write list, some servers need to see an extra
-        * segment for odd-length Write chunks. The upper layer provides
-        * space in the tail iovec for this purpose.
+       /* When encoding a Write chunk, some servers need to see an
+        * extra segment for non-XDR-aligned Write chunks. The upper
+        * layer provides space in the tail iovec that may be used
+        * for this purpose.
         */
-       if (type == rpcrdma_writech && reminv_expected)
+       if (type == rpcrdma_writech && r_xprt->rx_ia.ri_implicit_roundup)
                return n;
 
        if (xdrbuf->tail[0].iov_len) {
@@ -291,7 +292,8 @@ rpcrdma_encode_read_list(struct rpcrdma_xprt *r_xprt,
        if (rtype == rpcrdma_areadch)
                pos = 0;
        seg = req->rl_segments;
-       nsegs = rpcrdma_convert_iovs(&rqst->rq_snd_buf, pos, rtype, seg, false);
+       nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_snd_buf, pos,
+                                    rtype, seg);
        if (nsegs < 0)
                return ERR_PTR(nsegs);
 
@@ -353,10 +355,9 @@ rpcrdma_encode_write_list(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
        }
 
        seg = req->rl_segments;
-       nsegs = rpcrdma_convert_iovs(&rqst->rq_rcv_buf,
+       nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf,
                                     rqst->rq_rcv_buf.head[0].iov_len,
-                                    wtype, seg,
-                                    r_xprt->rx_ia.ri_reminv_expected);
+                                    wtype, seg);
        if (nsegs < 0)
                return ERR_PTR(nsegs);
 
@@ -421,8 +422,7 @@ rpcrdma_encode_reply_chunk(struct rpcrdma_xprt *r_xprt,
        }
 
        seg = req->rl_segments;
-       nsegs = rpcrdma_convert_iovs(&rqst->rq_rcv_buf, 0, wtype, seg,
-                                    r_xprt->rx_ia.ri_reminv_expected);
+       nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf, 0, wtype, seg);
        if (nsegs < 0)
                return ERR_PTR(nsegs);
 

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 11d07748f699aeb76f6e7d495ad248fb09dcca79..2a6a367a2dacfa1eb90ba5f9936ffeb2d2a9df2b 100644 (file)
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -208,6 +208,7 @@ rpcrdma_update_connect_private(struct rpcrdma_xprt *r_xprt,
 
        /* Default settings for RPC-over-RDMA Version One */
        r_xprt->rx_ia.ri_reminv_expected = false;
+       r_xprt->rx_ia.ri_implicit_roundup = xprt_rdma_pad_optimize;
        rsize = RPCRDMA_V1_DEF_INLINE_SIZE;
        wsize = RPCRDMA_V1_DEF_INLINE_SIZE;
 

diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index e35efd4ac1e4b6267349702a3286cbdd96435030..c13715431419cdffc24e409f5685cb9e03a99a91 100644 (file)
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -75,6 +75,7 @@ struct rpcrdma_ia {
        unsigned int            ri_max_inline_write;
        unsigned int            ri_max_inline_read;
        bool                    ri_reminv_expected;
+       bool                    ri_implicit_roundup;
        enum ib_mr_type         ri_mrtype;
        struct ib_qp_attr       ri_qp_attr;
        struct ib_qp_init_attr  ri_qp_init_attr;