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xprtrdma: Prevent inline overflow

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When deciding whether to send a Call inline, rpcrdma_marshal_req
doesn't take into account header bytes consumed by chunk lists.
This results in Call messages on the wire that are sometimes larger
than the inline threshold.

Likewise, when a Write list or Reply chunk is in play, the server's
reply has to emit an RDMA Send that includes a larger-than-minimal
RPC-over-RDMA header.

The actual size of a Call message cannot be estimated until after
the chunk lists have been registered. Thus the size of each
RPC-over-RDMA header can be estimated only after chunks are
registered; but the decision to register chunks is based on the size
of that header. Chicken, meet egg.

The best a client can do is estimate header size based on the
largest header that might occur, and then ensure that inline content
is always smaller than that.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever
2016-05-02 14:41:05 -04:00
committed by Anna Schumaker
parent 949317464b
commit 302d3deb20
5 changed files with 90 additions and 11 deletions
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5
net/sunrpc/xprtrdma/xprt_rdma.h
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@@ -73,6 +73,8 @@ struct rpcrdma_ia {
struct completion ri_done;
int ri_async_rc;
unsigned int ri_max_frmr_depth;
unsigned int ri_max_inline_write;
unsigned int ri_max_inline_read;
struct ib_qp_attr ri_qp_attr;
struct ib_qp_init_attr ri_qp_init_attr;
};
@@ -538,6 +540,9 @@ void rpcrdma_reply_handler(struct rpcrdma_rep *);
* RPC/RDMA protocol calls - xprtrdma/rpc_rdma.c
*/
int rpcrdma_marshal_req(struct rpc_rqst *);
void rpcrdma_set_max_header_sizes(struct rpcrdma_ia *,
struct rpcrdma_create_data_internal *,
unsigned int);
/* RPC/RDMA module init - xprtrdma/transport.c
*/