forked from luck/tmp_suning_uos_patched
821c791a0b
A single memory allocation is used for the pair of buffers wherein the RPC client builds an RPC call message and decodes its matching reply. These buffers are sized based on the maximum possible size of the RPC call and reply messages for the operation in progress. This means that as the call buffer increases in size, the start of the reply buffer is pushed farther into the memory allocation. RPC requests are growing in size. It used to be that both the call and reply buffers fit inside a single page. But these days, thanks to NFSv4 (and especially security labels in NFSv4.2) the maximum call and reply sizes are large. NFSv4.0 OPEN, for example, now requires a 6KB allocation for a pair of call and reply buffers, and NFSv4 LOOKUP is not far behind. As the maximum size of a call increases, the reply buffer is pushed far enough into the buffer's memory allocation that a page boundary can appear in the middle of it. When the maximum possible reply size is larger than the client's RDMA receive buffers (currently 1KB), the client has to register a Reply chunk for the server to RDMA Write the reply into. The logic in rpcrdma_convert_iovs() assumes that xdr_buf head and tail buffers would always be contained on a single page. It supplies just one segment for the head and one for the tail. FMR, for example, registers up to a page boundary (only a portion of the reply buffer in the OPEN case above). But without additional segments, it doesn't register the rest of the buffer. When the server tries to write the OPEN reply, the RDMA Write fails with a remote access error since the client registered only part of the Reply chunk. rpcrdma_convert_iovs() must split the XDR buffer into multiple segments, each of which are guaranteed not to contain a page boundary. That way fmr_op_map is given the proper number of segments to register the whole reply buffer. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Devesh Sharma <devesh.sharma@broadcom.com> Reviewed-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> |
||
|---|---|---|
| .. | ||
| backchannel.c | ||
| fmr_ops.c | ||
| frwr_ops.c | ||
| Makefile | ||
| module.c | ||
| physical_ops.c | ||
| rpc_rdma.c | ||
| svc_rdma_backchannel.c | ||
| svc_rdma_marshal.c | ||
| svc_rdma_recvfrom.c | ||
| svc_rdma_sendto.c | ||
| svc_rdma_transport.c | ||
| svc_rdma.c | ||
| transport.c | ||
| verbs.c | ||
| xprt_rdma.h | ||